ABUNDANCE AND DISTRIBUTION OF INDIGENOUS, NONINDIGENOUS, AND CRYPTOGENIC BENTHIC MACROFAUNA IN WILLAPA BAY, WASHINGTON, USA

EPA Science Inventory

Benthic macrofaunal samples were collected in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Zostera, Spartina, U...

A new Arctic seepage site? Preliminary evidence from benthic community

NASA Astrophysics Data System (ADS)

Caridi, Francesca; Sabbatini, Anna; Morigi, Caterina; Giulia Lucchi, Renata

2017-04-01

The Kveithola Trough is an abrupt and narrow sedimentary system located in the NW Barents Sea. The hydrographic, bio-geochemical conditions and the possible existence of gas seepage activity of the area have been investigated during the Eurofleets 2- BURSTER cruise, conducted on board the German icebreaker RV Polarstern. The aim of our work is to characterize the benthic biota and more specifically the macrofaunal community structure coupled to the study of benthic foraminiferal meiofauna. Preliminary qualitative results revealed that in the inner Kveithola Trough, the macrofaunal community is composed by abundant black worm tubes (Chaetopteridae worms and Siboglinidae-like taxa) with presence of Thyasiridae bivalve species. The occurrence of these macrofaunal taxa is usually associated to oxygen-reduced environments, hydrothermal vents and cold seeps. The living benthic foraminiferal assemblage in the same stations is characterized by the presence of typically oxygen-depleted environmental taxa including the calcareous species Nonionellina labradorica and Globobulimina spp.. Conversely, in the outer Kveithola trough, both benthic macrofauna and foraminiferal meiofauna assemblages are characterized by less opportunistic taxa with a higher biodiversity suggesting very distinct oceanographic sea bottom conditions. The organic matter richness plays a large role in the Kveithola Trough environmental setting and may bring anoxic conditions that could affect the biota of the area. In fact, the benthic community structure of this area inhabits suboxic, anoxic and organic-enriched sediments and disturbed environments, forming assemblages with low diversity and high abundances of a few tolerant and/or specialized species. This preliminary finding could be consistent with other studies examining benthic community structure around Svalbard and in particular cold seep and vents habitats where faunal characteristics are patchy, suggesting small-scale heterogeneity in the environment surrounding cold seeps. For said reasons we envisage the presence of a new Arctic seepage site having a strong local impact on the benthic system.

Assessing benthic ecological impacts of bottom aquaculture using macrofaunal assemblages.

PubMed

Wang, Lu; Fan, Ying; Yan, Cunjun; Gao, Chunzi; Xu, Zhaodong; Liu, Xiaoshou

2017-01-15

Bottom aquaculture of bivalves is a high-yield culture method, which is increasingly adopted by shellfish farmers worldwide. However, the effects of bottom aquaculture on benthic ecosystems are not well-known. Manila clam (Ruditapes philippinarum), is a widely distributed bottom aquaculture mollusk species. To assess the ecological impacts of Manila clam bottom aquaculture, clams and other macrofaunal assemblages were investigated during four cruises (July and November 2011, February and May 2012) at six sampling sites in Jiaozhou Bay, China. Correlation analysis showed that macrofaunal assemblages had significant negative correlations with the abundance of Manila clams. However, according to the results of several biotic indices, a low disturbance was detected by Manila clam bottom aquaculture. In conclusion, AMBI (AZTI'S Marine Biotic Index) and M-AMBI (Multivariate AZTI Marine Biotic Index) indices are more suitable for assessing ecological quality than polychaete/amphipod ratios when the disturbance is slight, such as at a bivalve bottom aquaculture. Copyright © 2016 Elsevier Ltd. All rights reserved.

Benthic Community Structure and Sediment Geochemical Properties at Hydrocarbon Seeps Along the Continental Slope of the Western North Atlantic

NASA Astrophysics Data System (ADS)

Demopoulos, A. W.; Bourque, J. R.; Brooke, S.

2015-12-01

Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410-450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared to other seeps found throughout the region.

Benthic Macrofaunal Communities at Newly Explored Caribbean Seamounts in the Greater/Lesser Antilles Transition Zone and a Comparison to Nearby Habitats

NASA Astrophysics Data System (ADS)

Demopoulos, A. W.; Bourque, J. R.; Cordes, E. E.; Chaytor, J. D.; Quattrini, A.

2016-02-01

Seamounts are topographically and oceanographically complex features with environmental characteristics, including substrate types, carbon flux, and current patterns, that vary greatly within and among seamounts. While seamounts are reputed to be oases and biodiversity hotspots, comparisons across multiple spatial scales of a seamount chain have yet to be explored. Along the margins of the Caribbean Sea basin, numerous seamounts punctuate the seafloor. In 2013 and 2014, we investigated the deep-sea benthic community ecology at Noroît, Dog, and Conrad Seamounts and nearby ridge, bank, and rift environments at depths ranging from 630 to 2930 m. Sediment push cores were collected to quantify macrofaunal (> 300 μm) density, diversity, community composition, grain size, and organic content. In addition, environmental data collected from CTDs and extracted from high resolution multibeam mapping efforts (e.g. slope, rugosity, roughness, slope orientation), allowed us to evaluate the role of microhabitats in structuring these communities. Preliminary results indicate that macrofaunal density across all sites decreased with depth in both seamount and non-seamount sediments, with the highest densities occurring in non-seamount environments. However, macrofaunal density patterns varied on individual seamounts. Macrofaunal densities on shallow seamounts (Conrad and Dog) increased with depth, whereas densities decreased with depth on the deeper Noroît seamount. The relationship between environmental parameters and macrofaunal community structure and biodiversity varied among seamounts and non-seamount environments. This study represents the first investigation of seamount infauna in the region and places this baseline information on seamount faunal biodiversity, spatial distribution of taxa, and overall ecology into a broader biogeographic context.

Spatial and temporal patterns of benthic macrofaunal communities on the deep continental margin in the Gulf of Guinea

NASA Astrophysics Data System (ADS)

Galéron, J.; Menot, L.; Renaud, N.; Crassous, P.; Khripounoff, A.; Treignier, C.; Sibuet, M.

2009-12-01

Density, taxonomic composition at higher taxon level and vertical distribution of benthic macrofaunal communities and sediment characteristics (pore water, nitrogen, organic carbon, sulfur, C/N ratio, n-alcohol biomarkers) were examined at three deep sites on the Congo-Gabon continental margin. This study was part of the multidisciplinary BIOZAIRE project that aimed at studying the deep benthic ecosystems in the Gulf of Guinea. Sampling of macrofaunal communities and of sediment was conducted during three cruises (January 2001, December 2001 and December 2003) at two downslope sites (4000 m depth), one located near the Congo submarine channel (15 km in the south) and the other one far from the channel (150 km in the South). The third area located 8 km north of the Congo channel in the surroundings of a giant pockmark at 3160 m depth was sampled during one cruise in December 2003. At these three locations the macrofaunal communities presented relatively high densities (327-987 ind. 0.25 m -2) compared with macrofaunal communities at similar depths; that is due to high levels of food input related to the Congo river and submarine system activities that affect the whole study area. The communities were different from each other in terms of taxonomic composition at higher taxon level (phylum, class, order for all the groups except for the polychaetes classified into families). The polychaetes dominated the communities and were responsible for the increase in densities observed at both deep sites (4000 m) between January 2001 and December 2003 whereas the tanaidaceans, the isopods and the bivalves were the other most abundant taxa responsible for the spatial differences between these sites. The community at 3150 m differed from the two deep communities by higher abundances in bivalves, nemerteans and holothuroids. The composition of the polychaete community also differed among sites. In the vicinity of the Congo channel, the expected positive effect of the additional organic matter transported through the turbiditic currents on to the surrounding benthic communities was not observed, as the increase in densities during the study period was higher at the site located away from the Congo channel than near the channel (80% vs 30%). That may be due to the low food value of the organic matter of terrestrial origin carried through the turbidites, and/or to the disturbance caused by these turbidites. Conversely, far from the channel the macrofaunal communities benefit from organic matter of higher energetic value originating mainly from marine sources, but also from continental sources, carried by the Congo plume or by near-bed currents across or along the continental slope. Spatial and temporal variability in trophic and physical characteristics of the sediment habitat at both deep sites also affected the vertical distribution of the macrofaunal communities. The activities of the very active Congo system structure the deep macrofaunal communities on a large area in terms of densities, composition and vertical distribution. The food input is enhanced at regional scale as well as the heterogeneity of the sediment characteristics, mainly in terms of organic matter quality (marine vs terrigenous). In turn, the densities are enhanced as well as the regional diversity of the macrofaunal communities in terms of taxonomic composition and distribution.

Food and disturbance effects on Arctic benthic biomass and production size spectra

NASA Astrophysics Data System (ADS)

Górska, Barbara; Włodarska-Kowalczuk, Maria

2017-03-01

Body size is a fundamental biological unit that is closely coupled to key ecological properties and processes. At the community level, changes in size distributions may influence energy transfer pathways in benthic food webs and ecosystem carbon cycling; nevertheless they remain poorly explored in benthic systems, particularly in the polar regions. Here, we present the first assessment of the patterns of benthic biomass size spectra in Arctic coastal sediments and explore the effects of glacial disturbance and food availability on the partitioning of biomass and secondary productivity among size-defined components of benthic communities. The samples were collected in two Arctic fjords off west Spitsbergen (76 and 79°N), at 6 stations that represent three regimes of varying food availability (indicated by chlorophyll a concentration in the sediments) and glacial sedimentation disturbance intensity (indicated by sediment accumulation rates). The organisms were measured using image analysis to assess the biovolume, biomass and the annual production of each individual. The shape of benthic biomass size spectra at most stations was bimodal, with the location of a trough and peaks similar to those previously reported in lower latitudes. In undisturbed sediments macrofauna comprised 89% of the total benthic biomass and 56% of the total production. The lower availability of food resources seemed to suppress the biomass and secondary production across the whole size spectra (a 6-fold decrease in biomass and a 4-fold decrease in production in total) rather than reshape the spectrum. At locations where poor nutritional conditions were coupled with disturbance, the biomass was strongly reduced in selected macrofaunal size classes (class 10 and 11), while meiofaunal biomass and production were much higher, most likely due to a release from macrofaunal predation and competition pressure. As a result, the partitioning of benthic biomass and production shifted towards meiofauna (39% of biomass and 83% of production), which took over the benthic metazoan key-player role in terms of processing organic matter in sediments. Macrofaunal nematodes composed a considerable portion of the benthic community in terms of biomass (up to 9%) and production (up to 12%), but only in undisturbed sediments with high organic matter content. Our study indicates that food availability and disturbance controls the total bulk and partitioning of biomass and production among the size classes in Arctic benthic communities.

Can the source–sink hypothesis explain macrofaunal abundance patterns in the abyss? A modelling test

PubMed Central

Hardy, Sarah M.; Smith, Craig R.; Thurnherr, Andreas M.

2015-01-01

Low food availability is a major structuring force in deep-sea benthic communities, sustaining only very low densities of organisms in parts of the abyss. These low population densities may result in an Allee effect, whereby local reproductive success is inhibited, and populations are maintained by larval dispersal from bathyal slopes. This slope–abyss source–sink (SASS) hypothesis suggests that the abyssal seafloor constitutes a vast sink habitat with macrofaunal populations sustained only by an influx of larval ‘refugees' from source areas on continental slopes, where higher productivity sustains greater population densities. Abyssal macrofaunal population densities would thus be directly related to larval inputs from bathyal source populations. We evaluate three predictions derived from the SASS hypothesis: (i) slope-derived larvae can be passively transported to central abyssal regions within a single larval period, (ii) projected larval export from slopes to the abyss reproduces global patterns of macrofaunal abundance and (iii) macrofaunal abundance decreases with distance from the continental slope. We find that abyssal macrofaunal populations are unlikely to be sustained solely through influx of larvae from slope sources. Rather, local reproduction probably sustains macrofaunal populations in relatively high-productivity abyssal areas, which must also be considered as potential larval source areas for more food-poor abyssal regions. PMID:25948686

Distribution of benthic macrofaunal communities in the western Baltic Sea with regard to near-bottom environmental parameters. 1. Causal analysis

NASA Astrophysics Data System (ADS)

Gogina, Mayya; Glockzin, Michael; Zettler, Michael L.

2010-01-01

In this study we relate patterns in the spatial distribution of macrofaunal communities to patterns in near-bottom environmental parameters, analysing the data observed in a limited area in the western Baltic Sea. The data used represents 208 stations, sampled during the years 2000 to 2007 simultaneously for benthic macrofauna, associated sediment and near-bottom environmental characteristics, in a depth range from 7.5 to 30 m. Only one degree of longitude wide, the study area is geographically bounded by the eastern part of the Mecklenburg Bight and the southwestern Darss Sill Area. Spatial distribution of benthic macrofauna is related to near-bottom environmental patterns by means of various statistical methods (e.g. rank correlation, hierarchical clustering, nMDS, BIO-ENV, CCA). Thus, key environmental descriptors were disclosed. Within the area of investigation, these were: water depth, regarded as a proxy for other environmental factors, and total organic content. Distinct benthic assemblages are defined and discriminated by particular species ( Hydrobia ulvae-Scoloplos armiger, Lagis koreni-Mysella bidentata and Capitella capitata-Halicryptus spinulosus). Each assemblage is related to different spatial subarea and characterised by a certain variability of environmental factors. This study represents a basis for the predictive modeling of species distribution in the selected study area.

Biological effects of long term fine limestone tailings discharge in a fjord ecosystem.

PubMed

Brooks, Lucy; Melsom, Fredrik; Glette, Tormod

2015-07-15

Benthic infaunal data collected from 1993 to 2010 were analysed to examine the effect of long term discharge of fine limestone tailings on macrofaunal species assemblages in a fjord. Relative distance from the outfall and proportion of fine tailings in the sediment were correlated with benthic community structure. Diversity decreased with increasing proportion of fine tailings. Biological Traits Analysis (BTA) was used to explore the temporal and spatial effects of the tailings gradient on macrofaunal functional attributes. BTA revealed that all stations along a pressure gradient of fine limestone tailings were dominated by free-living species. As the proportion of fine tailings in the sediment increased, there was an increase in fauna that were smaller, highly mobile, living on or nearer the surface sediment, with shorter lifespans. There was a decrease in permanent tube dwellers, those fauna with low or no mobility, that live deeper in the sediment and have longer lifespans (>5 yrs). Copyright © 2015 Elsevier Ltd. All rights reserved.

DETERMINING THE CAUSES OF ADVERSE EFFECTS IN NEAR COASTAL ECOSYSTEMS: FROM TOXICITY IDENTIFICATION EVALUATIONS TO WATERSHED DIAGNOTICS

EPA Science Inventory

Several approaches are available for evaluating adverse effects in near coastal ecosystems. These range from performing toxicity tests with individual organisms on water column and sediment samples to conducting macrofaunal compositional analyses on pelagic and benthic communiti...

Using a RIVPACS model to predict expected macrofaunal species richness in Puget Sound

EPA Science Inventory

As part of a project to develop regional indicators for Pacific coastal environments using soft-bottom benthic species, we are evaluating a RIVPACS predictive model (River InVertebrate Prediction and Classification System). This approach was originally developed for rivers and s...

Composition of abyssal macrofauna along the Vema Fracture Zone and the hadal Puerto Rico Trench, northern tropical Atlantic

NASA Astrophysics Data System (ADS)

Brandt, A.; Frutos, I.; Bober, S.; Brix, S.; Brenke, N.; Guggolz, T.; Heitland, N.; Malyutina, M.; Minzlaff, U.; Riehl, T.; Schwabe, E.; Zinkann, A.-C.; Linse, K.

2018-02-01

We analyzed composition and variations in benthic macrofaunal communities along a transect of the entire length of the Vema-Fracture Zone on board of RV Sonne (SO-237) between December 2014 and January 2015 in order to test whether the Mid-Atlantic Ridge serves as a barrier limiting benthic taxon distribution in the abyssal basins on both sides of the ridge or whether the fracture zone permits the migration of species between the western and eastern abyssal Atlantic basins. The Puerto Rico Trench, much deeper than the surrounding abyssal West Atlantic, was sampled to determine whether the biodiversity of its hadal macrofauna differs from that of the abyssal Atlantic. The composition of the macrofauna from the epibenthic sledge catches yielded a total of 21,332 invertebrates. Crustacea occurred most frequently (59%) with 12,538 individuals followed by Annelida (mostly Polychaeta) (26%) with 5491 individuals, Mollusca (7%) with 1458 individuals, Echinodermata (4%) with 778 individuals, Nematoda (2%) with 502 individuals and Chaetognatha (1%) with 152 and Porifera (1%) with 131 individuals. All other taxa occurred with overall less than ten individuals (Hemichordata, Phoronida, Priapulida, Brachiopoda, invertebrate Chordata, Echiurida, Foraminifera (here refereed to macrofaunal Komokiacea only), Chelicerata, Platyhelminthes). Within the Crustacea, Peracarida (62.6%) with 7848 individuals and Copepoda (36.1%) with 44,526 individuals were the most abundant taxa. Along the abyssal Vema-Fracture Zone macrofaunal abundances (ind./1000 m2) were generally higher on the eastern side, while the highest normalized abundance value was reported in the Puerto Rico Trench at abyssal station 14-1 2313 individuals/1000 m2. The lowest abundance was reported at station 11-4 with 120 ind./1000 m2 located at the western side of the Vema-Fracture Zone. The number of major macrofaunal taxa (phylum, class) ranged between five (stations 12-5, 13-4 and 13-5 at hadal depths in the Puerto Rico Trench) and 14 (station 9-8) in the western abyssal basin of the Vema-Fracture Zone. Differences are seen in the distribution of Porifera at macrofaunal level between eastern and western sides of the Vema-Fracture Zone. Macrofaunal composition of the study area is compared with data from other expeditions in the Atlantic and the northwest Pacific Ocean.

Benthic macrofaunal dynamics and environmental stress across a salt wedge Mediterranean estuary.

PubMed

Nebra, Alfonso; Alcaraz, Carles; Caiola, Nuno; Muñoz-Camarillo, Gloria; Ibáñez, Carles

2016-06-01

The spatial distribution of benthic macroinvertebrate community in relation to environmental factors was studied along the Ebro Estuary (NE Iberian Peninsula), a salt wedge Mediterranean estuary. Both ordination methods and generalized additive models were performed to identify the different benthic assemblages and their relationship to abiotic factors. Our results showed a strong relationship between macrofaunal assemblages and the predominant environmental gradients (e.g. salinity); thus revealing spatial differences in their structure and composition. Two different stretches were identified, namely the upper (UE) and the lower Ebro Estuary (LE). UE showed riverine characteristics and hence was colonized by a freshwater community; whereas LE was influenced by marine intrusion and sustained a complex marine-origin community. However, within each stretch, water and sediment characteristics played an important role in explaining species composition differences among sampling stations. Moreover, outcomes suggested a total species replacement pattern, instead of the nestedness pattern usually associated with well-mixed temperate estuaries. The sharp species turnover together with the estuarine stratification point out that the Ebro Estuary is working, in terms of ecological boundaries, under an ecotone model. Finally, despite obvious differences with well mixed estuaries (i.e. lack of tidal influence, stratification and species turnover), the Ebro Estuary shares important ecological attributes with well-mixed temperate estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Link between Microbial Diversity and Nitrogen Cycling in Marine Sediments Is Modulated by Macrofaunal Bioturbation

PubMed Central

Yazdani Foshtomi, Maryam; Braeckman, Ulrike; Derycke, Sofie; Sapp, Melanie; Van Gansbeke, Dirk; Sabbe, Koen; Willems, Anne; Vincx, Magda; Vanaverbeke, Jan

2015-01-01

Objectives The marine benthic nitrogen cycle is affected by both the presence and activity of macrofauna and the diversity of N-cycling microbes. However, integrated research simultaneously investigating macrofauna, microbes and N-cycling is lacking. We investigated spatio-temporal patterns in microbial community composition and diversity, macrofaunal abundance and their sediment reworking activity, and N-cycling in seven subtidal stations in the Southern North Sea. Spatio-Temporal Patterns of the Microbial Communities Our results indicated that bacteria (total and β-AOB) showed more spatio-temporal variation than archaea (total and AOA) as sedimentation of organic matter and the subsequent changes in the environment had a stronger impact on their community composition and diversity indices in our study area. However, spatio-temporal patterns of total bacterial and β-AOB communities were different and related to the availability of ammonium for the autotrophic β-AOB. Highest bacterial richness and diversity were observed in June at the timing of the phytoplankton bloom deposition, while richness of β-AOB as well as AOA peaked in September. Total archaeal community showed no temporal variation in diversity indices. Macrofauna, Microbes and the Benthic N-Cycle Distance based linear models revealed that, independent from the effect of grain size and the quality and quantity of sediment organic matter, nitrification and N-mineralization were affected by respectively the diversity of metabolically active β-AOB and AOA, and the total bacteria, near the sediment-water interface. Separate models demonstrated a significant and independent effect of macrofaunal activities on community composition and richness of total bacteria, and diversity indices of metabolically active AOA. Diversity of β-AOB was significantly affected by macrofaunal abundance. Our results support the link between microbial biodiversity and ecosystem functioning in marine sediments, and provided broad correlative support for the hypothesis that this relationship is modulated by macrofaunal activity. We hypothesized that the latter effect can be explained by their bioturbating and bio-irrigating activities, increasing the spatial complexity of the biogeochemical environment. PMID:26102286

Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

NASA Astrophysics Data System (ADS)

Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

2017-07-01

Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages. The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the other hand, rebounded more rapidly due to their fast growth rate and short generation time and thus did not display bathymetric pattern in the canyon. To our knowledge, this is the first benthic ecological study in a submarine canyon connected to a high-sediment-yield SMR. The biological responses to extreme physical conditions in the GPSC could have broad implications on understanding the anthropogenic and climate change impacts in the deep-sea ecosystems.

Effects of an oil spill on benthic community production and respiration on subtropical intertidal sandflats.

PubMed

Lee, Li-Hua; Lin, Hsing-Juh

2013-08-15

This study determined effects of an oil spill on subtropical benthic community production and respiration by monitoring CO2 fluxes in benthic chambers on intertidal sandflats during emersion before and after an accidental spill. The oil spill decreased sediment chlorophyll a concentrations, altered benthic macrofaunal community, and affected ecological functioning by suppressing or even stopping microalgal production, increasing bacterial respiration, and causing a shift from an autotrophic system to a heterotrophic system. Effects of the oil spill on the macrofauna were more severe than on benthic microalgae, and affected sedentary infauna more than motile epifauna. Despite the oil spill's impact on the benthic community and carbon metabolism, the affected area appeared to return to normal in about 23 days. Our results suggest that the prompt response of benthic metabolism to exposure to petroleum hydrocarbons can serve as a useful indicator of the impact of an oil spill. Copyright © 2013 Elsevier Ltd. All rights reserved.

Benthic macrofauna habitat associations in Willapa Bay, Washington, USA

NASA Astrophysics Data System (ADS)

Ferraro, Steven P.; Cole, Faith A.

2007-02-01

Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [ Zostera marina], Atlantic cordgrass [ Spartina alterniflora], mud shrimp [ Upogebia pugettensis], ghost shrimp [ Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [ Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray-Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species ( S), abundance ( A), biomass ( B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index ( H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna-habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna-habitat associations in this study can be used to help identify critical habitats, prioritize habitats for environmental protection, index habitat suitability, assess habitat equivalency, and as habitat value criteria in ecological risk assessments in Willapa Bay.

Assessing differences in macrofaunal assemblages as a factor of sieve mesh size, distance between samples, and time of sampling.

PubMed

Hemery, Lenaïg G; Politano, Kristin K; Henkel, Sarah K

2017-08-01

With increasing cascading effects of climate change on the marine environment, as well as pollution and anthropogenic utilization of the seafloor, there is increasing interest in tracking changes to benthic communities. Macrofaunal surveys are traditionally conducted as part of pre-incident environmental assessment studies and post-incident monitoring studies when there is a potential impact to the seafloor. These surveys usually characterize the structure and/or spatiotemporal distribution of macrofaunal assemblages collected with sediment cores; however, many different sampling protocols have been used. An assessment of the comparability of past and current survey methods was in need to facilitate future surveys and comparisons. This was the aim of the present study, conducted off the Oregon coast in waters 25-35 m deep. Our results show that the use of a sieve with a 1.0-mm mesh size gives results for community structure comparable to results obtained from a 0.5-mm mesh size, which allows reliable comparisons of recent and past spatiotemporal surveys of macroinfauna. In addition to our primary objective of comparing methods, we also found interacting effects of seasons and depths of collection. Seasonal differences (summer and fall) were seen in infaunal assemblages in the wave-induced sediment motion zone but not deeper. Thus, studies where wave-induced sediment motion can structure the benthic communities, especially during the winter months, should consider this effect when making temporal comparisons. In addition, some macrofauna taxa-like polychaetes and amphipods show high interannual variabilities, so spatiotemporal studies should make sure to cover several years before drawing any conclusions.

Food web flows through a sub-arctic deep-sea benthic community

NASA Astrophysics Data System (ADS)

Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

2011-11-01

The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (<1% and 5% of carbon requirements of nematodes and macrofauna respectively). Predation on nematodes was generally low with the exception of sub-surface deposit-feeding polychaetes that obtained 35% of their energy requirements from nematode ingestion. Carnivorous polychaetes also covered 35% of their carbon demand through predation although the preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

Limited impact of an invasive oyster on intertidal assemblage structure and biodiversity: the importance of environmental context and functional equivalency with native species.

PubMed

Zwerschke, Nadescha; Hollyman, Philip R; Wild, Romy; Strigner, Robin; Turner, John R; King, Jonathan W

2018-01-01

Impacts of invasive species are context dependent and linked to the ecosystem they occur within. To broaden the understanding of the impact of a globally widespread invasive oyster, Crassostrea ( Magallana ) gigas, intertidal surveys were carried out at 15 different sites in Europe. The impact of C. gigas on macro- (taxa surrounding oyster > 1 cm) and epifaunal (taxa on oyster < 1 cm) benthic communities and α and β-diversity was assessed and compared to those associated with native ecosystem engineers, including the flat oyster Ostrea edulis . Whilst the effect of C. gigas on benthic community structures was dependent on habitat type, epifaunal communities associated with low densities of O. edulis and C. gigas did not differ and changes in benthic assemblage structure owing to the abundance of C. gigas were therefore attributed to the presence of oyster shells. Macrofaunal α-diversity increased with C. gigas cover in muddy habitats, while epifaunal α-diversity decreased at greater oyster densities. Macrofaunal β-diversity was greatest at low densities of C. gigas ; however, it did not differ between samples without and increased densities of oysters. In contrast, epifaunal β-diversity decreased with increasing oyster cover. Different environmental contexts enabled more independent predictions of the effect of C. gigas on native communities. These were found to be low and more importantly not differing from O. edulis . This indicates that, at low densities, C. gigas may be functionally equivalent to the declining native oyster in terms of biodiversity facilitation and aid in re-establishing benthic communities on shores where O. edulis has become extinct.

Spatio-temporal biodiversity of soft bottom macrofaunal assemblages in shallow coastal waters exposed to episodic hypoxic events.

PubMed

Veas, Rodrigo; Hernández-Miranda, Eduardo; Quiñones, Renato A; Carrasco, Franklin D

2012-07-01

The Humboldt Current System (HCS) has one of the three most important oxygen minimum zones (OMZ) of the global ocean. Several studies have looked at the macrofaunal benthic assemblages inhabiting the continental shelf and shallow bays off central-southern Chile associated with low oxygen areas, but little is known about open coast macrofaunal communities within this zone, which are frequently subjected to the low oxygen conditions of Equatorial Subsurface Waters (ESSW). In order to assess local and mesoscale coastal macrofauna dynamics, the sampling area (ca. 40 linear km) was divided into seven local zones (Cobquecura, southern Cobquecura, northern Itata, Itata River mouth, external, southern Itata, and Coliumo). Eight oceanographic cruises were carried out between May 2006 and February 2008 covering 16 coastal sampling sites, between 36°07'S and 36°30'S. The macrofaunal assemblage was dominated by polychaetes, crustaceans, and mollusks. Our results suggest a high degree of temporal faunal stability on the mesoscale in soft bottom communities along the open coast, given the persistence of a faunal assemblage dominated by organisms tolerant of low oxygen conditions. While there is some local variability in community attributes, the main structuring factor for soft bottom communities in the shallow coastal area off central-southern Chile is the seasonal intrusion of low oxygen ESSW. Copyright © 2012 Elsevier Ltd. All rights reserved.

Linking Environmental Forcing and Trophic Supply to Benthic Communities in the Vercelli Seamount Area (Tyrrhenian Sea)

PubMed Central

Covazzi Harriague, Anabella; Bavestrello, Giorgio; Bo, Marzia; Borghini, Mireno; Castellano, Michela; Majorana, Margherita; Massa, Francesco; Montella, Alessandro; Povero, Paolo; Misic, Cristina

2014-01-01

Seamounts and their influence on the surrounding environment are currently being extensively debated but, surprisingly, scant information is available for the Mediterranean area. Furthermore, although the deep Tyrrhenian Sea is characterised by a complex bottom morphology and peculiar hydrodynamic features, which would suggest a variable influence on the benthic domain, few studies have been carried out there, especially for soft-bottom macrofaunal assemblages. In order to fill this gap, the structure of the meio-and macrofaunal assemblages of the Vercelli Seamount and the surrounding deep area (northern Tyrrhenian Sea – western Mediterranean) were studied in relation to environmental features. Sediment was collected with a box-corer from the seamount summit and flanks and at two far-field sites in spring 2009, in order to analyse the metazoan communities, the sediment texture and the sedimentary organic matter. At the summit station, the heterogeneity of the habitat, the shallowness of the site and the higher trophic supply (water column phytopigments and macroalgal detritus, for instance) supported a very rich macrofaunal community, with high abundance, biomass and diversity. In fact, its trophic features resembled those observed in coastal environments next to seagrass meadows. At the flank and far-field stations, sediment heterogeneity and depth especially influenced the meiofaunal distribution. From a trophic point of view, the low content of the valuable sedimentary proteins that was found confirmed the general oligotrophy of the Tyrrhenian Sea, and exerted a limiting influence on the abundance and biomass of the assemblages. In this scenario, the rather refractory sedimentary carbohydrates became a food source for metazoans, which increased their abundance and biomass at the stations where the hydrolytic-enzyme-mediated turnover of carbohydrates was faster, highlighting high lability. PMID:25343621

Macrofaunal communities associated with chemosynthetic habitats from the U.S. Atlantic margin: A comparison among depth and habitat types

USGS Publications Warehouse

Bourque, Jill R.; Robertson, Craig M.; Brooke, Sandra; Demopoulos, Amanda W.J.

2016-01-01

Hydrocarbon seeps support distinct benthic communities capable of tolerating extreme environmental conditions and utilizing reduced chemical compounds for nutrition. In recent years, several locations of methane seepage have been mapped along the U.S. Atlantic continental slope. In 2012 and 2013, two newly discovered seeps were investigated in this region: a shallow site near Baltimore Canyon (BCS, 366–412 m) and a deep site near Norfolk Canyon (NCS, 1467–1602 m), with both sites containing extensive chemosynthetic mussel bed and microbial mat habitats. Sediment push cores, suction samples, and Ekman box cores were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 μm) in mussel beds, mats, and slope habitats at both sites. Community data from the deep site were also assessed in relation to the associated sediment environment (organic carbon and nitrogen, stable carbon and nitrogen isotopes, grain size, and depth). Infaunal assemblages and densities differed both between depths and among habitat types. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments and were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in BCS microbial mat habitats, but higher in mussel and slope sediments compared to NCS habitats. Multivariate statistical analysis revealed specific sediment properties as important for distinguishing the macrofaunal communities, including larger grain sizes present within NCS microbial mat habitats and depleted stable carbon isotopes (δ13C) in sediments present at mussel beds. These results suggest that habitat differences in the quality and source of organic matter are driving the observed patterns in the infaunal assemblages, including high β diversity and high variability in the macrofaunal community composition. This study is the first investigation of seep infauna along the U.S. Atlantic slope north of the Blake Ridge Diapir and provides a baseline for future regional comparisons to other seep habitats along the Atlantic margin.

Macrofaunal communities associated with chemosynthetic habitats from the U.S. Atlantic margin: A comparison among depth and habitat types

NASA Astrophysics Data System (ADS)

Bourque, Jill R.; Robertson, Craig M.; Brooke, Sandra; Demopoulos, Amanda W. J.

2017-03-01

Hydrocarbon seeps support distinct benthic communities capable of tolerating extreme environmental conditions and utilizing reduced chemical compounds for nutrition. In recent years, several locations of methane seepage have been mapped along the U.S. Atlantic continental slope. In 2012 and 2013, two newly discovered seeps were investigated in this region: a shallow site near Baltimore Canyon (BCS, 366-412 m) and a deep site near Norfolk Canyon (NCS, 1467-1602 m), with both sites containing extensive chemosynthetic mussel bed and microbial mat habitats. Sediment push cores, suction samples, and Ekman box cores were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 μm) in mussel beds, mats, and slope habitats at both sites. Community data from the deep site were also assessed in relation to the associated sediment environment (organic carbon and nitrogen, stable carbon and nitrogen isotopes, grain size, and depth). Infaunal assemblages and densities differed both between depths and among habitat types. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments and were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in BCS microbial mat habitats, but higher in mussel and slope sediments compared to NCS habitats. Multivariate statistical analysis revealed specific sediment properties as important for distinguishing the macrofaunal communities, including larger grain sizes present within NCS microbial mat habitats and depleted stable carbon isotopes (δ13C) in sediments present at mussel beds. These results suggest that habitat differences in the quality and source of organic matter are driving the observed patterns in the infaunal assemblages, including high β diversity and high variability in the macrofaunal community composition. This study is the first investigation of seep infauna along the U.S. Atlantic slope north of the Blake Ridge Diapir and provides a baseline for future regional comparisons to other seep habitats along the Atlantic margin.

Biogeochemistry in highly reduced mussel farm sediments during macrofaunal recolonization by Amphiura filiformis and Nephtys sp.

PubMed

Lindqvist, Stina; Norling, Karl; Hulth, Stefan

2009-04-01

Mussel farming is considered a viable means for reducing coastal eutrophication. This study assessed the importance of bioturbation by recolonizing fauna for benthic solute fluxes and porewater distributions in manipulated mussel farm sediments. Three consecutive time-series flux incubations were performed during an experimental period of three weeks in sieved farm sediment treated with the brittle star Amphiura filiformis and the polychaete Nephtys sp. The functional behavior of Nephtys sp. and interactions between Nephtys sp. and the spontaneously colonizing spionid Malacoceros fuliginosus determined the biogeochemical response in the Nephtys sp. treatment. For example, the oxic zone was restricted and benthic nitrate and silicate fluxes were reduced compared to the brittle star treatment. A. filiformis seemed to enhance the bioadvective solute transport, although an increased supply of oxygen was due to the highly reducing conditions of the sediment mainly seen as secondary effects related to porewater distributions and benthic nutrient fluxes.

Spatiotemporal patterns of the macrofaunal community structure in the East China Sea, off the coast of Zhejiang, China, and the impact of the Kuroshio Branch Current.

PubMed

Xu, Yong; Yu, Fei; Li, Xinzheng; Ma, Lin; Dong, Dong; Kou, Qi; Sui, Jixing; Gan, Zhibin; Gong, Lin; Yang, Mei; Wang, Yueyun; Sun, Yue; Wang, Jinbao; Wang, Hongfa

2018-01-01

The Kuroshio Current intrudes in the bottom layer of the East China Sea continental shelf from the northeast of Taiwan via two bottom branches named the Nearshore Kuroshio Branch Current (NKBC, along the 60 m isobath) and the Offshore Kuroshio Branch Current (OKBC, along the 100 m isobath). However, knowledge on the macrofaunal responses to these bottom branches is limited. This study examined the variations in the benthic macrofaunal community in a section of the East China Sea under the influence of the NKBC. Seven sites corresponding to three regions (the west, middle and east region) were sampled using an Agassiz trawl net at a monthly rate from February to November 2015 (except in August). A total of 270 macrofaunal species were collected in this study. Cluster analysis and nMDS ordination revealed three communities: the inshore, Kuroshio and offshore communities, roughly corresponding to the west, middle and east of NKBC route. Significant differences in the species composition (one-way PERMANOVA) and diversity indices (one-way ANOVA) among the regions and communities were observed, while no statistically significant difference among the months was detected. The indicator species also varied among the communities, with Sternaspis scutata and Odontamblyopus rubicundus dominating the inshore community, Camatopsis rubida, Schizaster lacunosus and Craspidaster hesperus dominating the Kuroshio community, and Portunus argentatus, Champsodon snyderi and Coelorinchus multispinulosus dominating the offshore community. Some rare species (e.g., Neobythites sivicola) may indicate the passage of the NKBC better than the indicator species. A redundancy analysis was used to describe the relationship between the macrofaunal species and environmental variables in this study. Water depth and turbidity played important roles in the distribution of the macrofauna. S. scutata and O. rubicundus were associated with high turbidity and shallow depth, while Plesionika izumiae and P. argentatus were associated with low turbidity and deep depth. This study outlines the impact of the NKBC on the distribution patterns of the macrofaunal community of the East China Sea. More studies are needed to understand the detailed interactions between macrofauna and the NKBC in the future.

Response of soft-bottom macrobenthic assemblages to artisanal trawling fisheries in a subtropical estuary

NASA Astrophysics Data System (ADS)

Ortega, Ileana; Colling, Leonir André; Dumont, Luiz Felipe Cestari

2018-07-01

Bottom trawling is one of the most harmful and widespread activities affecting benthic habitats and fauna. In this study, we analyzed the impact of shrimp trawling fisheries on the densities, assemblage structure and vertical stratification of the benthic macrofauna in shallow mudflats of the Patos Lagoon Estuary (Brazil). Experimental trawls of different intensities were performed during three shrimp fishing seasons (2015-2017), comparing macrofauna among before and after trawling, and a control zone. The changes in macrofaunal assemblages were more consistently related to natural variability than to trawling impact, being mostly influenced by sediment structure and salinity variation. The trawling impact was mainly detected in the area with higher percentages of fine sediments, with different macrofaunal responses in each month and stratum. Some non-significant decreases on total densities after trawling were observed, mainly on the superficial stratum, and signs of burial activities. The response to trawling disturbance of each species was different and it highly depended on their natural variability. Only five species showed significant variation to the trawling treatment (Erodona mactroides, Heleobia australis, H. charruana, Heteromastus similis and Laeonereis acuta), with temporally different responses. Decreasing densities were more related to the high impact treatment. In some seasons, decreases on the abundance of Monokalliapseudes schubarti after high impact trawls were up to 60% of the seasonal mean densities. Trawling fisheries may reduce macrobenthic densities but not their vertical stratification. The impact of trawling on key species may compromise the ecosystem function, as benthic macrofauna provide food sources for many aquatic resources. This study highlights trawling impacts in an estuarine nursery area, which should be fully considered since they may be reflected in the trophic webs.

Dynamics of the bathyal Benthic Boundary Layer in the northwestern Mediterranean: depth and temporal variations in macrofaunal megafaunal communities and their possible connections within deep-sea trophic webs

NASA Astrophysics Data System (ADS)

Cartes, Joan E.

1998-01-01

The distribution patterns of benthopelagic fauna and the macrofauna-megafauna trophic relationships in the Benthic Boundary Layer (BBL) were studied. The study is based on data collected during 6 sampling cruises off the Catalan coast (western Mediterranean) during 1991-1995 at depths ranging from 389-1355 m. Crustaceans were the dominant benthopelagic macrofauna in the BBL level closest to the sea bed (~0-1.5 m above bottom) on the Catalan Sea slope. Copepods and peracarid crustaceans (mysids, amphipods, isopods, and cumaceans) were dominant, whereas euphausiids and natantian decapods, some taxa of gelatinous plankton (siphonophores, medusae, and chaetognaths), and benthopelagic fishes were also well represented groups. Seasonal changes in megafaunal decapod crustaceans abundance seem to be linked to changes in the density and the biological cycle of BBL macrofauna, which constitute an important part of the available food exploited by megafauna. Both the advective and the vertical flow of organic matter in the north-western Mediterranean should simultaneously influence peaks of available food (BBL macrofauna) for bathyal-megafaunal decapods. Recruitment of macrofaunal (suprabenthos and infauna) species at the level of canyons and neighbouring slope zones mainly occurred between late autumn-late winter and would probably be mainly induced by an advective component. However, the macrofaunal sizes consumed by megafaunal decapods are found more abundantly represented in spring and summer populations. In parallel, the vertical fluxes seem to determine maxima in the abundance of planktonic organisms (especially copepods) which also occur in late spring-summer. Size, natatory capability, and energetic value are important factors in the selection of food-resources by megafaunal decapods, which would have a greater availability of food in late spring-summer. This would explain both the seasonal maxima of decapod abundance in summer, and maxima in the catches of some commercial species (i.e. the shrimp Aristeus antennatus) in spring-summer.

The role of mangrove revegetation as a means of restoring macrofaunal communities along degraded coasts.

PubMed

Gorman, Daniel; Turra, Alexander

2016-10-01

As coastal habitats face unprecedented pressure globally, there is a need to better understand how revegetation can fortify or restore biodiversity. We examined the early-stage outcomes of mangrove revegetation efforts for benthic invertebrate communities within degraded mangrove habitats in south eastern Brazil. We followed changes in macrofaunal abundance and species richness within small-scale Avicennia schaueriana revegetation plots over a 12month period. The assemblages of revegetation plots (RP) became progressively more diverse when compared to structural (SC) and blank controls (BC). The trajectory of change also differed with RP communities demonstrating convergence with those of remnant mangrove forest. After 12months, RP had greater abundances of crustaceans (41%) and polychaetes (13%) as well as higher but variable numbers of gastropods and bivalves than both SC and BC. A spatial examination of revegetation outcomes showed that success may vary across sheltered vs. exposed coastal microhabitats. Indeed, subsequent analysis using generalised linear mixed models pointed to a stronger influence of tidal height, than many of the commonly attributed sedimentary variables such as grain-size and organic matter content as determinants of community structure. Given the encouraging results of this study, we advocate an intensification of revegetation initiatives to augment natural recovery, increase benthic biodiversity and restore ecosystems services to degraded coasts. Copyright © 2016 Elsevier B.V. All rights reserved.

Colonization, succession, and nutrition of macrobenthic assemblages in a restored wetland at Tijuana Estuary, California

NASA Astrophysics Data System (ADS)

Moseman, Serena M.; Levin, Lisa A.; Currin, Carolyn; Forder, Charlotte

2004-08-01

Modes of colonization, the successional trajectory, and trophic recovery of a macrofaunal community were analyzed over 19 months in the Friendship marsh, a 20-acre restored wetland in Tijuana Estuary, California. Traditional techniques for quantifying macrofaunal communities were combined with emerging stable isotopic approaches for evaluation of trophic recovery, making comparisons with a nearby natural Spartina foliosa habitat. Life history-based predictions successfully identified major colonization modes, although most taxa employed a variety of tactics for colonizing the restored marsh. The presence of S. foliosa did not seem to affect macrofaunal colonization or succession at the scale of this study. However, soil organic matter content in the restored marsh was positively correlated with insect densities, and high initial salinities may have limited the success of early colonists. Total macrofaunal densities recovered to natural marsh levels after 14 months and diversity, measured as species richness and the Shannon index ( H'), was comparable to the natural marsh by 19 months. Some compositional disparities between the natural and created communities persisted after 19 months, including lower percentages of surface-feeding polychaetes ( Polydora spp.) and higher percentages of dipteran insects and turbellarians in the Friendship marsh. As surficial structural similarity of infaunal communities between the Friendship and natural habitat was achieved, isotopic analyses revealed a simultaneous trajectory towards recovery of trophic structure. Enriched δ 13C signatures of benthic microalgae and infauna, observed in the restored marsh shortly after establishment compared to natural Spartina habitat, recovered after 19 months. However, the depletion in δ 15N signatures of macrofauna in the Friendship marsh indicated consumption of microalgae, particularly nitrogen-fixing cyanobacteria, while macroalgae and Spartina made a larger contribution to macrofaunal diets in the natural habitat. Future successional studies must continue to develop and employ novel combinations of techniques for evaluating structural and functional recovery of disturbed and created habitats.

The Link between Microbial Diversity and Nitrogen Cycling in Marine Sediments Is Modulated by Macrofaunal Bioturbation.

PubMed

Yazdani Foshtomi, Maryam; Braeckman, Ulrike; Derycke, Sofie; Sapp, Melanie; Van Gansbeke, Dirk; Sabbe, Koen; Willems, Anne; Vincx, Magda; Vanaverbeke, Jan

2015-01-01

The marine benthic nitrogen cycle is affected by both the presence and activity of macrofauna and the diversity of N-cycling microbes. However, integrated research simultaneously investigating macrofauna, microbes and N-cycling is lacking. We investigated spatio-temporal patterns in microbial community composition and diversity, macrofaunal abundance and their sediment reworking activity, and N-cycling in seven subtidal stations in the Southern North Sea. Our results indicated that bacteria (total and β-AOB) showed more spatio-temporal variation than archaea (total and AOA) as sedimentation of organic matter and the subsequent changes in the environment had a stronger impact on their community composition and diversity indices in our study area. However, spatio-temporal patterns of total bacterial and β-AOB communities were different and related to the availability of ammonium for the autotrophic β-AOB. Highest bacterial richness and diversity were observed in June at the timing of the phytoplankton bloom deposition, while richness of β-AOB as well as AOA peaked in September. Total archaeal community showed no temporal variation in diversity indices. Distance based linear models revealed that, independent from the effect of grain size and the quality and quantity of sediment organic matter, nitrification and N-mineralization were affected by respectively the diversity of metabolically active β-AOB and AOA, and the total bacteria, near the sediment-water interface. Separate models demonstrated a significant and independent effect of macrofaunal activities on community composition and richness of total bacteria, and diversity indices of metabolically active AOA. Diversity of β-AOB was significantly affected by macrofaunal abundance. Our results support the link between microbial biodiversity and ecosystem functioning in marine sediments, and provided broad correlative support for the hypothesis that this relationship is modulated by macrofaunal activity. We hypothesized that the latter effect can be explained by their bioturbating and bio-irrigating activities, increasing the spatial complexity of the biogeochemical environment.

Modelling temporal and spatial dynamics of benthic fauna in North-West-European shelf seas

NASA Astrophysics Data System (ADS)

Lessin, Gennadi; Bruggeman, Jorn; Artioli, Yuri; Butenschön, Momme; Blackford, Jerry

2017-04-01

Benthic zones of shallow shelf seas receive high amounts of organic material. Physical processes such as resuspension, as well as complex transformations mediated by diverse faunal and microbial communities, define fate of this material, which can be returned to the water column, reworked within sediments or ultimately buried. In recent years, numerical models of various complexity and serving different goals have been developed and applied in order to better understand and predict dynamics of benthic processes. ERSEM includes explicit parameterisations of several groups of benthic biota, which makes it particularly applicable for studies of benthic biodiversity, biological interactions within sediments and benthic-pelagic coupling. To assess model skill in reproducing temporal (inter-annual and seasonal) dynamics of major benthic macrofaunal groups, 1D model simulation results were compared with data from the Western Channel Observatory (WCO) benthic survey. The benthic model was forced with organic matter deposition rates inferred from observed phytoplankton abundance and model parameters were subsequently recalibrated. Based on model results and WCO data comparison, deposit-feeders exert clear seasonal variability, while for suspension-feeders inter-annual variability is more pronounced. Spatial distribution of benthic fauna was investigated using results of a full-scale NEMO-ERSEM hindcast simulation of the North-West European Shelf Seas area, covering the period of 1981-2014. Results suggest close relationship between spatial distribution of biomass of benthic faunal functional groups in relation to bathymetry, hydrodynamic conditions and organic matter supply. Our work highlights that it is feasible to construct, implement and validate models that explicitly include functional groups of benthic macrofauna. Moreover, the modelling approach delivers detailed information on benthic biogeochemistry and food-web at spatial and temporal scales that are unavailable through other sources but highly relevant to marine management, planning and policy.

Use of a Novel Sediment Exposure to Determine the Effects of ...

EPA Pesticide Factsheets

Triclosan (5-chloro-2-(2,4-dichlorophenoxy) phenol) is a relatively new, commonly used antimicrobial compound found in many personal care products. Triclosan is toxic to marine organisms at the ug/l level, can photo-degrade to a dioxin, accumulate in humans, and has been found to be stable in marine sediments for over 30 years. To determine the effects of triclosan on marine benthic communities, we brought intact sediment cores into the laboratory and held them under flowing seawater conditions. A two cm layer of triclosan-spiked sediment was applied to the surface, and after a two-week exposure the meio- and macrofaunal communities were assessed for differences in composition relative to non-spiked core. The High Triclosan treatment (180 mg/kg dry weight) affected both the meio- and macro benthic communities. There were no discernable differences in the Low Triclosan treatment (14 mg/kg dry weight dry). This exposure method is effective for testing benthic community response to sediment contaminants, but improvements should be made as to the amount and method of applying the overlying sediment to prevent smothering of fragile benthic organisms. This paper describes the effects of triclosan on meio- and macro-benthic marine communities. It describes a novel system of whole benthic community exposure that is a promising method to evaluate effects on intact marine benthic communities. Triclosan concentrations greater than 180 mg/kg dry weight had a signif

Macrofaunal recolonization of copper-contaminated sediments in San Diego Bay.

PubMed

Neira, Carlos; Mendoza, Guillermo; Porrachia, Magali; Stransky, Chris; Levin, Lisa A

2015-12-30

Effects of Cu-loading on macrofaunal recolonization were examined in Shelter Island Yacht Basin (San Diego Bay, California). Sediments with high and low Cu levels were defaunated and Cu-spiked, translocated, and then placed back into the environment. These demonstrated that the alteration observed in benthic communities associated with Cu contamination occurs during initial recolonization. After a 3-month exposure to sediments with varying Cu levels, two primary colonizing communities were identified: (1) a "mouth assemblage" resembling adjacent background fauna associated with low-Cu levels that was more diverse and predominantly dominated by surface- and subsurface-deposit feeders, burrowers, and tube builders, and (2) a "head assemblage" resembling adjacent background fauna associated with high-Cu concentrations, with few dominant species and an increasing importance of carnivores and mobile epifauna. Cu loading can cause reduced biodiversity and lower structural complexity that may last several months if high concentrations persist, with a direct effect on community functioning. Copyright © 2015 Elsevier Ltd. All rights reserved.

Weak and Habitat-Dependent Effects of Nutrient Pollution on Macrofaunal Communities of Southeast Australian Estuaries

PubMed Central

Nicastro, Andrea; Bishop, Melanie J.

2013-01-01

Among the impacts of coastal settlements to estuaries, nutrient pollution is often singled out as a leading cause of modification to the ecological communities of soft sediments. Through sampling of 48 sites, distributed among 16 estuaries of New South Wales, Australia, we tested the hypotheses that (1) anthropogenic nutrient loads would be a better predictor of macrofaunal communities than estuarine geomorphology or local sediment characteristics; and (2) local environmental context, as determined largely by sediment characteristics, would modify the relationship between nutrient loading and community composition. Contrary to the hypothesis, multivariate multiple regression analyses revealed that sediment grain size was the best predictor of macrofaunal assemblage composition. When samples were stratified according to median grain size, relationships between faunal communities and nitrogen loading and latitude emerged, but only among estuaries with sandier sediments. In these estuaries, capitellid and nereid polychaetes and chironomid larvae were the taxa that showed the strongest correlations with nutrient loading. Overall, this study failed to provide evidence of a differential relationship between diffuse nutrient enrichment and benthic macrofauna across a gradient of 7° of latitude and 4°C temperature. Nevertheless, as human population growth continues to place increasing pressure on southeast Australian estuaries, manipulative field studies examining when and where nutrient loading will lead to significant changes in estuarine community structure are needed. PMID:23799037

Comparing efficacy of different taxonomic resolutions and surrogates in detecting changes in soft bottom assemblages due to coastal defence structures.

PubMed

Bertasi, Fabio; Colangelo, Marina Antonia; Colosio, Francesco; Gregorio, Gianni; Abbiati, Marco; Ceccherelli, Victor Ugo

2009-05-01

Sandy shores on the West coast of the North Adriatic Sea are extensively protected by different types of defence structures to prevent coastal erosion. Coastal defence schemes modify the hydrodynamic regime, the sediment structure and composition thus affecting the benthic assemblages. This study examines the effectiveness in detecting changes in soft bottom assemblages caused by coastal defence structures by using different levels of taxonomic resolution, polychaetes and/or bivalves as surrogates and different data transformations. A synoptic analyses of three datasets of subtidal benthic macrofauna used in studies aimed at assessing the impact of breakwaters along the North Adriatic coast has been done. Analyses of similarities and correlations between distance matrices were done using matrices with different levels of taxonomic resolution, and with polychaetes or bivalves data alone. Lentidium mediterraneum was the most abundant species in all datasets. Its abundance was not consistently related to the presence of defence structures. Moreover, distribution patterns of L. mediterraneum were masking the structure of the whole macrofaunal assemblages. Removal of L. mediterraneum from the datasets allowed the detection of changes in benthic assemblages due to coastal defences. Analyses on different levels of taxonomic resolution showed that the level of family maintained sufficient information to detect the impacts of coastal defence structures on benthic assemblages. Moreover, the outcomes depended on the transformation used. Patterns of distribution of bivalves, used as surrogates, showed low correlations with the patterns of the total macrofaunal species assemblages. Patterns of polychaetes, if identified to the species or genus level showed higher correlations with the whole dataset. However, the identification of polychaetes to species and genus level is as costly as the identification of all macrobenthic taxa at family level. This study provided additional evidences that taxonomic sufficiency is a useful tool in environmental monitoring, also in investigations on the impacts of coastal defence structures on subtidal macrofauna. The use of coarser taxonomic level, being time-efficient, would allow improving sampling designs of monitoring programs by increasing replication in space and time and by allowing long term monitoring studies.

Macrofaunal colonization across the Indian margin oxygen minimum zone

NASA Astrophysics Data System (ADS)

Levin, L. A.; McGregor, A. L.; Mendoza, G. F.; Woulds, C.; Cross, P.; Witte, U.; Gooday, A. J.; Cowie, G.; Kitazato, H.

2013-11-01

There is a growing need to understand the ability of bathyal assemblages to recover from disturbance and oxygen stress, as human activities and expanding oxygen minimum zones increasingly affect deep continental margins. The effects of a pronounced oxygen minimum zone (OMZ) on slope benthic community structure have been studied on every major upwelling margin; however, little is known about the dynamics or resilience of these benthic populations. To examine the influence of oxygen and phytodetritus on short-term settlement patterns, we conducted colonization experiments at 3 depths on the West Indian continental margin. Four colonization trays were deployed at each depth for 4 days at 542 and 802 m (transect 1-16°58' N) and for 9 days at 817 and 1147 m (transect 2-17°31' N). Oxygen concentrations ranged from 0.9 μM (0.02 mL L-1) at 542 m to 22 μM (0.5 mL L-1) at 1147 m. All trays contained local defaunated sediments; half of the trays at each depth also contained 13C/15N-labeled phytodetritus mixed into the sediments. Sediment cores were collected between 535 m and 1140 m from 2 cross-margin transects for analysis of ambient (source) macrofaunal (>300 μm) densities and composition. Ambient macrofaunal densities ranged from 0 ind m-2 (at 535-542 m) to 7400 ind m-2, with maximum values on both transects at 700-800 m. Macrofaunal colonizer densities ranged from 0 ind m-2 at 542 m, where oxygen was lowest, to average values of 142 ind m-2 at 800 m, and 3074 ind m-2 at 1147 m, where oxygen concentration was highest. These were equal to 4.3 and 151% of the ambient community at 800 m and 1147 m, respectively. Community structure of settlers showed no response to the presence of phytodetritus. Increasing depth and oxygen concentration, however, significantly influenced the community composition and abundance of colonizing macrofauna. Polychaetes constituted 92.4% of the total colonizers, followed by crustaceans (4.2%), mollusks (2.5%), and echinoderms (0.8%). The majority of colonizers were found at 1147 m; 88.5% of these were Capitella sp., although they were rare in the ambient community. Colonists at 800 and 1147 m also included ampharetid, spionid, syllid, lumbrinerid, cirratulid, cossurid and sabellid polychaetes. Consumption of 13C/15N-labeled phytodetritus was observed for macrofaunal foraminifera (too large to be colonizers) at the 542 and 802/817 m sites, and by metazoan macrofauna mainly at the deepest, better oxygenated sites. Calcareous foraminifera (Uvigerina, Hoeglundina sp.), capitellid polychaetes and cumaceans were among the major phytodetritus consumers. These preliminary experiments suggest that bottom-water oxygen concentrations may strongly influence ecosystem services on continental margins, as reflected in rates of colonization by benthos and colonizer processing of carbon following disturbance. They may also provide a window into future patterns of settlement on the continental slope as the world's oxygen minimum zones expand.

High-throughput sequencing and morphology perform equally well for benthic monitoring of marine ecosystems

PubMed Central

Lejzerowicz, Franck; Esling, Philippe; Pillet, Loïc; Wilding, Thomas A.; Black, Kenneth D.; Pawlowski, Jan

2015-01-01

Environmental diversity surveys are crucial for the bioassessment of anthropogenic impacts on marine ecosystems. Traditional benthic monitoring relying on morphotaxonomic inventories of macrofaunal communities is expensive, time-consuming and expertise-demanding. High-throughput sequencing of environmental DNA barcodes (metabarcoding) offers an alternative to describe biological communities. However, whether the metabarcoding approach meets the quality standards of benthic monitoring remains to be tested. Here, we compared morphological and eDNA/RNA-based inventories of metazoans from samples collected at 10 stations around a fish farm in Scotland, including near-cage and distant zones. For each of 5 replicate samples per station, we sequenced the V4 region of the 18S rRNA gene using the Illumina technology. After filtering, we obtained 841,766 metazoan sequences clustered in 163 Operational Taxonomic Units (OTUs). We assigned the OTUs by combining local BLAST searches with phylogenetic analyses. We calculated two commonly used indices: the Infaunal Trophic Index and the AZTI Marine Biotic Index. We found that the molecular data faithfully reflect the morphology-based indices and provides an equivalent assessment of the impact associated with fish farms activities. We advocate that future benthic monitoring should integrate metabarcoding as a rapid and accurate tool for the evaluation of the quality of marine benthic ecosystems. PMID:26355099

Quantitative assessment of benthic food resources for juvenile Gulf sturgeon, Acipenser oxyrinchus desotoi in the Suwannee River estuary, Florida, USA

USGS Publications Warehouse

Brooks, R.A.; Sulak, K.J.

2005-01-01

Gulf sturgeon, Acipenser oxyrinchus desotoi, forage extensively in the Suwannee River estuary following emigration out of the Suwannee River, Florida. While in the estuary, juvenile Gulf sturgeon primarily feed on benthic infauna. In June-July 2002 and February-April 2003, random sites within the estuary were sampled for benthic macrofauna (2002 n = 156; 2003 n = 103). A mean abundance of 2,562 ind m-2 (SE ?? 204) was found in the summer, with significantly reduced macrofaunal abundance in the winter (mean density of 1,044 ind m-2, SE ?? 117). Benthic biomass was significantly higher in the summer with an average summer sample dry weight of 5.92 g m-2 (SE ?? 0.82) compared to 3.91 g m-2 (SE ?? 0.67) in the winter. Amphipods and polychaetes were the dominant taxa collected during both sampling periods. Three different estimates of food availability were examined taking into account principal food item information and biomass estimates. All three estimates provided a slightly different view of potential resources but were consistent in indicating that food resource values for juvenile Gulf sturgeon are spatially heterogeneous within the Suwannee River estuary. ?? 2005 Estuarine Research Federation.

Off shore wind farms change the benthic pelagic coupling in the Belgian Part of the North Sea

NASA Astrophysics Data System (ADS)

Vanaverbeke, Jan; Coates, Delphine; Braeckman, Ulrike; Soetaert, Karline; Moens, Tom

2016-04-01

Since Europe enforced renewable energy target figures upon its member states through the implementation of two main European Directives 11 2001/77/EC and 2009/28/EC, the development of offshore wind farms (OWF) has accelerated. Belgium installed OWFs on sandbanks, characterized by permeable sediments, low in organic matter content and a species-poor macrofaunal community with species occurring in low densities. A detailed monitoring campaign in the immediate vicinity of a wind turbine (1-200m), revealed a significant decrease in median grain size and permeability, coinciding with a 6-fold increase in organic matter content. The observed fining of the sediment is explained by an altered benthic-pelagic coupling in the area. The wind turbines are colonized by an abundant fouling community producing high amounts of detritus and faeces, a continuous additional source of organic matter. The changes in sediment composition, and the availability of additional organic matter resulted in drastic increase in macrofaunal densities (from 1390 ind m-2 to 18600 ind m-2), and a change from a species-poor community to a species-rich community dominated by the ecosystem engineer Lanice conchilega. Large densities of L. conchilega, as observed in our samples, are known to trap fine material from the water column, which can result in a further decrease of sediment permeability in the vicinity of the wind turbines. A preliminary experiment, where permeable sediments were subjected to artificial fining, showed a decreased penetration depth of advective water currents and a reduced trapping of diatoms by the sediment in finer sediments. Additionally, sediment community oxygen consumption rates, and efflux of NH4+ from the sediment, measured after a simulated phytoplankton bloom, decreased significantly when sediment permeability was reduced. We hypothesize that the combination of the altered macrofaunal community composition, together with the changes in the physical properties of the sediment matrix, will lead to a change in the biogeochemical properties of the sediment: highly reactive permeable sediments, poor in organic matter will shift towards sediment where organic matter will accumulate. Degradation of organic matter will then no longer be governed by physical processes, but mediated by biological processes (bioturbation, bio-irrigation).

Long-term (1998 vs. 2010) large-scale comparison of soft-bottom benthic macrofauna composition in the Gulf of Lions, NW Mediterranean Sea

NASA Astrophysics Data System (ADS)

Bonifácio, Paulo; Grémare, Antoine; Gauthier, Olivier; Romero-Ramirez, Alicia; Bichon, Sabrina; Amouroux, Jean-Michel; Labrune, Céline

2018-01-01

We achieved a long term (i.e., 1998 vs. 2010) large scale (i.e., whole Gulf of Lions) study of benthic macrofauna composition in the Gulf of Lions based on the resampling of 91 stations located along 21 inshore-offshore transects. Results show that the 3 main benthic communities identified in 1998 were still present in 2010 although their composition changed. Using only year and station of sampling we found a significant space-time interaction explaining changes in macrofaunal community composition, and, in this study, stations differ primarily in terms of depth and distance to the Rhône river mouth. Temporal changes in benthic macrofauna composition were clearly most important at shallow stations (i.e., in the Littoral Fine Sand community) than at deep ones (i.e., Terrigenous Coastal Mud community). These results are in good agreement with the current paradigm according to which climatic oscillations such as NAO (North Atlantic Oscillation) and WeMO (Western Mediterranean Oscillation) are indirectly (i.e., through changes in the frequency of occurrence and the intensity of storms) controlling benthic macrofauna composition in the Gulf of Lions. This hypothesis is further supported by a meta-analysis of changes in the average and maximal yearly abundances of the polychaete Ditrupa arietina. At last, the spatial modelling of 1998 and 2010 benthic macrofauna compositions both suggested a significant effect of Rhône River inputs on the spatial distribution of benthic macrofauna in the Gulf of Lions.

Macrofauna community inside and outside of the Darwin Mounds SAC, NE Atlantic

NASA Astrophysics Data System (ADS)

Serpetti, N.; Gontikaki, E.; Narayanaswamy, B. E.; Witte, U.

2012-11-01

Over the past two decades, growing concerns have been raised regarding the effects of towed fishing gears, such as trawls and dredges, on deep-sea biodiversity and ecosystem functioning. Trawling disturbs the benthic communities both physically and biologically, and can eliminate the most vulnerable organisms and modify habitat structure; chronically disturbed communities are often dominated by opportunistic species. The European Union is under obligation to designate a network of offshore Special Areas of Conservation (SACs) and Marine Protected Areas (MPAs) by the end of 2012 based on the perceived expectation that these networks will help protect marine biodiversity and that within these areas, faunal abundance and diversity will be higher than the surrounding fished areas. The Darwin Mounds, only discovered in 1998, are located in the Rockall Trough, NE Atlantic at a depth of ~ 1000 m. Deep-water trawling regularly took place in the region of the Darwin Mounds; however in 2004 the mounds were designated as the first offshore SAC in UK and the area is now closed to bottom trawling. As part of the HERMIONE programme the influence of human impact on the Oceans was one of the key themes and in June 2011, an investigation of the macrofaunal community structure at comparable sites both inside and outside of the Darwin Mound SAC was undertaken. Macrofaunal communities were found to differ significantly, with the difference mostly driven by changes in the abundance of polychaetes, crustaceans and nematodes whilst no significant differences were seen for the other phyla. Whereas overall macrofaunal abundance was higher outside the SAC compared to within, this pattern varies considerably between phyla. Diversity indices showed no significant differences between protected and unprotected sites. This could indicate that a few years of preservation are not enough time to determine a recovery by the macrofaunal community of cold-water ecosystems and that a continued monitoring over a longer term is necessary to fully understand the impact of fishery closures.

A comparison of top-down and bottom-up approaches to benthic habitat mapping to inform offshore wind energy development

NASA Astrophysics Data System (ADS)

LaFrance, Monique; King, John W.; Oakley, Bryan A.; Pratt, Sheldon

2014-07-01

Recent interest in offshore renewable energy within the United States has amplified the need for marine spatial planning to direct management strategies and address competing user demands. To assist this effort in Rhode Island, benthic habitat classification maps were developed for two sites in offshore waters being considered for wind turbine installation. Maps characterizing and representing the distribution and extent of benthic habitats are valuable tools for improving understanding of ecosystem patterns and processes, and promoting scientifically-sound management decisions. This project presented the opportunity to conduct a comparison of the methodologies and resulting map outputs of two classification approaches, “top-down” and “bottom-up” in the two study areas. This comparison was undertaken to improve understanding of mapping methodologies and their applicability, including the bottom-up approach in offshore environments where data density tends to be lower, as well as to provide case studies for scientists and managers to consider for their own areas of interest. Such case studies can offer guidance for future work for assessing methodologies and translating them to other areas. The traditional top-down mapping approach identifies biological community patterns based on communities occurring within geologically defined habitat map units, under the concept that geologic environments contain distinct biological assemblages. Alternatively, the bottom-up approach aims to establish habitat map units centered on biological similarity and then uses statistics to identify relationships with associated environmental parameters and determine habitat boundaries. When applied to the two study areas, both mapping approaches produced habitat classes with distinct macrofaunal assemblages and each established statistically strong and significant biotic-abiotic relationships with geologic features, sediment characteristics, water depth, and/or habitat heterogeneity over various spatial scales. The approaches were also able to integrate various data at differing spatial resolutions. The classification outputs exhibited similar results, including the number of habitat classes generated, the number of species defining the classes, the level of distinction of the biological communities, and dominance by tube-building amphipods. These results indicate that both approaches are able to discern a comparable degree of habitat variability and produce cohesive macrofaunal assemblages. The mapping approaches identify broadly similar benthic habitats at the two study sites and methods were able to distinguish the differing levels of heterogeneity between them. The top-down approach to habitat classification was faster and simpler to accomplish with the data available in this study when compared to the bottom-up approach. Additionally, the top-down approach generated full-coverage habitat classes that are clearly delineated and can easily be interpreted by the map user, which is desirable from a management perspective for providing a more complete assessment of the areas of interest. However, a higher level of biological variability was noted in some of the habitat classes created, indicating that the biological communities present in this area are influenced by factors not captured in the broad-scale geological habitat units used in this approach. The bottom-up approach was valuable in its ability to more clearly define macrofaunal assemblages among habitats, discern finer-scale habitat characteristics, and directly assess the degree of macrofaunal assemblage variability captured by the environmental parameters. From a user perspective, the map is more complex, which may be perceived as a limitation, though likely reflects natural gradations in habitat structure and likely presents a more ecologically realistic portrayal of the study areas. Though more comprehensive, the bottom-up approach in this study was limited by the reliance on full-coverage data to create full-coverage habitat classes. Such classes could only be developed when sediment data was excluded, since this point-sample dataset could not be interpolated due to high spatial heterogeneity of the study areas. Given a higher density of bottom samples, this issue could be rectified. While the top-down approach was more appropriate for this study, both approaches were found to be suitable for mapping and classifying benthic habitats. In the United States, objectives for mapping and classification for renewable energy development have not been well established. Therefore, at this time, the best-suited approach primarily depends on mapping objectives, resource availability, data quality and coverage, and geographical location, as these factors impact the types of data included, the analyses and modeling that can be performed, and the biotic-abiotic relationships identified.

Bathymetric distribution patterns of Southern Ocean macrofaunal taxa: Bivalvia, Gastropoda, Isopoda and Polychaeta

NASA Astrophysics Data System (ADS)

Brandt, Angelika; Linse, Katrin; Schüller, Myriam

2009-11-01

The aim of this study is to compare the depth distributions of four major Southern Ocean macrobenthic epi- and infaunal taxa, the Bivalvia, Gastropoda, Isopoda, and Polychaeta, from subtidal to abyssal depth. All literature data up to summer 2008, as well as the unpublished data from the most recent ANDEEP I-III (Antarctic benthic deep-sea biodiversity: colonisation history and recent community patterns) expeditions to the Southern Ocean deep sea are included in the analysis. Benthic invertebrates in the Southern Ocean are known for their wide bathymetric ranges. We analysed the distributions of four of the most abundant and species-rich taxa from intertidal to abyssal (5200 m) depths in depth zones of 100 m. The depth distributions of three macrofaunal classes (Bivalvia, Gastropoda, Polychaeta) and one order (Isopoda) showed distinct differences. In the case of bivalves, gastropods and polychaetes, the number of species per depth zone decreased from the shelf to the slope at around 1000 m depth and then showed stable low numbers. The isopods showed the opposite trend; they were less species rich in the upper 1000 m but increased in species numbers from the slope to bathyal and abyssal depths. Depth ranges of families of the studied taxa (Bivalvia: 31 families, Gastropoda: 60, Isopoda: 32, and Polychaeta: 46 families) were compiled and illustrated. At present vast areas of the deep sea in the Southern Ocean remain unexplored and species accumulation curves showed that only a fraction of the species have been discovered to date. We anticipate that further investigations will greatly increase the number of species known in the Southern Ocean deep sea.

Effect of sample area and sieve size on benthic macrofaunal community condition assessments in California enclosed bays and estuaries.

PubMed

Hammerstrom, Kamille K; Ranasinghe, J Ananda; Weisberg, Stephen B; Oliver, John S; Fairey, W Russell; Slattery, Peter N; Oakden, James M

2012-10-01

Benthic macrofauna are used extensively for environmental assessment, but the area sampled and sieve sizes used to capture animals often differ among studies. Here, we sampled 80 sites using 3 different sized sampling areas (0.1, 0.05, 0.0071 m(2)) and sieved those sediments through each of 2 screen sizes (0.5, 1 mm) to evaluate their effect on number of individuals, number of species, dominance, nonmetric multidimensional scaling (MDS) ordination, and benthic community condition indices that are used to assess sediment quality in California. Sample area had little effect on abundance but substantially affected numbers of species, which are not easily scaled to a standard area. Sieve size had a substantial effect on both measures, with the 1-mm screen capturing only 74% of the species and 68% of the individuals collected in the 0.5-mm screen. These differences, though, had little effect on the ability to differentiate samples along gradients in ordination space. Benthic indices generally ranked sample condition in the same order regardless of gear, although the absolute scoring of condition was affected by gear type. The largest differences in condition assessment were observed for the 0.0071-m(2) gear. Benthic indices based on numbers of species were more affected than those based on relative abundance, primarily because we were unable to scale species number to a common area as we did for abundance. Copyright © 2010 SETAC.

Does human pressure affect the community structure of surf zone fish in sandy beaches?

NASA Astrophysics Data System (ADS)

Costa, Leonardo Lopes; Landmann, Júlia G.; Gaelzer, Luiz R.; Zalmon, Ilana R.

2017-01-01

Intense tourism and human activities have resulted in habitat destruction in sandy beach ecosystems with negative impacts on the associated communities. To investigate whether urbanized beaches affect surf zone fish communities, fish and their benthic macrofaunal prey were collected during periods of low and high human pressure at two beaches on the Southeastern Brazilian coast. A BACI experimental design (Before-After-Control-Impact) was adapted for comparisons of tourism impact on fish community composition and structure in urbanized, intermediate and non-urbanized sectors of each beach. At the end of the summer season, we observed a significant reduction in fish richness, abundance, and diversity in the high tourist pressure areas. The negative association between visitors' abundance and the macrofaunal density suggests that urbanized beaches are avoided by surf zone fish due to higher human pressure and the reduction of food availability. Our results indicate that surf zone fish should be included in environmental impact studies in sandy beaches, including commercial species, e.g., the bluefish Pomatomus saltatrix. The comparative results from the less urbanized areas suggest that environmental zoning and visitation limits should be used as effective management and preservation strategies on beaches with high conservation potential.

A big data approach to macrofaunal baseline assessment, monitoring and sustainable exploitation of the seabed.

PubMed

Cooper, K M; Barry, J

2017-09-29

In this study we produce a standardised dataset for benthic macrofauna and sediments through integration of data (33,198 samples) from 777 grab surveys. The resulting dataset is used to identify spatial and temporal patterns in faunal distribution around the UK, and the role of sediment composition and other explanatory variables in determining such patterns. We show how insight into natural variability afforded by the dataset can be used to improve the sustainability of activities which affect sediment composition, by identifying conditions which should remain favourable for faunal recolonisation. Other big data applications and uses of the dataset are discussed.

The impacts of the Samarco mine tailing spill on the Rio Doce estuary, Eastern Brazil.

PubMed

Gomes, Luiz Eduardo de Oliveira; Correa, Lucas Barreto; Sá, Fabian; Neto, Renato Rodrigues; Bernardino, Angelo Fraga

2017-07-15

Over 50 million cubic meters of mining tailings were released in the Rio Doce basin after the collapse of the Fundão dam (Samarco) in November 2015. Predicting significant impacts on the Rio Doce estuary, we sampled sediments to investigate short-term impacts on the benthic assemblages and trace metal accumulation on estuarine sediments. With the arrival of the tailing plumes in the estuary, we detected a predominance of clay particles and increased trace metal concentrations of up to 5 times in some areas. The rapid sedimentation after the impact also impacted estuarine macrofaunal assemblages through loss surface-dwelling taxa. As expected, the impacts on benthic assemblages observed up to 3days after the arrival of tailings were not clearly associated with trace metal concentrations, but long-term effects need to be studied. We recommend that the high spatial variability within the estuary be considered in future impact assessment studies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reciprocal experimental transplantations to assess effects of organic enrichment on the recolonization of benthic macrofauna in a subtropical estuary.

PubMed

Gern, Fabiana Regina; Lana, Paulo da Cunha

2013-02-15

Coastal benthic habitats are usually in a state of continuous recolonization as a consequence of natural disturbances or human activities. Recolonization patterns can be strongly affected by the quality of the sediment. We evaluated herein the macrobenthic recolonization of organically enriched sediments through a manipulative experiment involving reciprocal transplants between contaminated and non-contaminated intertidal areas. Regardless of the experimental treatments, the density of the polychaete Capitella sp. was extremely high in the contaminated area as well as the density of the gastropod Cylichna sp. in the non-contaminated area. We rejected the hypothesis that differences in sediment quality would determine macrofaunal recolonization at least in the considered scales of space in meters and time in weeks. The recolonization process in a subtropical estuarine environment was strongly dependent on the migration of adults present in the sediments adjacent to the experimental units. Copyright © 2012 Elsevier Ltd. All rights reserved.

Organic matter composition and macrofaunal diversity in sediments of the Condor Seamount (Azores, NE Atlantic)

NASA Astrophysics Data System (ADS)

Bongiorni, Lucia; Ravara, Ascensão; Parretti, Paola; Santos, Ricardo S.; Rodrigues, Clara F.; Amaro, Teresa; Cunha, Marina R.

2013-12-01

In recent years increasing knowledge has been accumulated on seamounts ecology; however their sedimentary environments and associated biological communities remain largely understudied. In this study we investigated quantity and biochemical composition of organic matter and macrofaunal diversity in sediments of the Condor Seamount (NE Atlantic, Azores). In order to test the effect of the seamount on organic matter distribution, sediment samples were collected in 6 areas: the summit, the northern and southern flanks and bases, and in an external far field site. Macrofauna abundance and diversity were investigated on the summit, the southern flank and in the far field site. The organic matter distribution reflected the complex hydrodynamic conditions occurring on the Condor. Concentrations of organic matter compounds were generally lower on the whole seamount than in the far field site and on the seamount summit compared to flanks and bases. A clear difference was also evident between the northern and southern slopes of the Condor, suggesting a role of the seamount in conditioning sedimentation processes and distribution of food resources for benthic consumers. Macrofauna assemblages changed significantly among the three sampling sites. High abundance and dominance, accompanied by low biodiversity, characterized the macrofauna community on the Condor summit, while low dominance and high biodiversity were observed at the flank. Our results, although limited to five samples on the seamount and two off the seamount, do not necessarily support the paradigm that seamounts are more biodiverse than the surrounding seafloor. However, the abundance (and biomass), functional diversity and taxonomical distinctiveness of the macrofaunal assemblages from the Condor Seamount suggest that seamounts habitats may play a relevant role in adding to the regional biodiversity.

Biodiversity and community composition of sediment macrofauna associated with deep-sea Lophelia pertusa habitats in the Gulf of Mexico

USGS Publications Warehouse

Demopoulos, Amanda W.J.; Bourque, Jill R.; Frometa, Janessy

2014-01-01

Scleractinian corals create three-dimensional reefs that provide sheltered refuges, facilitate sediment accumulation, and enhance colonization of encrusting fauna. While heterogeneous coral habitats can harbor high levels of biodiversity, their effect on the community composition within nearby sediments remains unclear, particularly in the deep sea. Sediment macrofauna from deep-sea coral habitats (Lophelia pertusa) and non-coral, background sediments were examined at three sites in the northern Gulf of Mexico (VK826, VK906, MC751, 350–500 m depth) to determine whether macrofaunal abundance, diversity, and community composition near corals differed from background soft-sediments. Macrofaunal densities ranged from 26 to 125 individuals 32 cm−2 and were significantly greater near coral versus background sediments only at VK826. Of the 86 benthic invertebrate taxa identified, 16 were exclusive to near-coral habitats, while 14 were found only in background sediments. Diversity (Fisher’s α) and evenness were significantly higher within near-coral sediments only at MC751 while taxon richness was similar among all habitats. Community composition was significantly different both between near-coral and background sediments and among the three primary sites. Polychaetes numerically dominated all samples, accounting for up to 70% of the total individuals near coral, whereas peracarid crustaceans were proportionally more abundant in background sediments (18%) than in those near coral (10%). The reef effect differed among sites, with community patterns potentially influenced by the size of reef habitat. Taxon turnover occurred with distance from the reef, suggesting that reef extent may represent an important factor in structuring sediment communities near L. pertusa. Polychaete communities in both habitats differed from other Gulf of Mexico (GOM) soft sediments based on data from previous studies, and we hypothesize that local environmental conditions found near L. pertusa may influence the macrofaunal community structure beyond the edges of the reef. This study represents the first assessment of L. pertusa-associated sediment communities in the GOM and provides baseline data that can help define the role of transition zones, from deep reefs to soft sediments, in shaping macrofaunal community structure and maintaining biodiversity; this information can help guide future conservation and management activities.

Benthic community structures in the North Sea

NASA Astrophysics Data System (ADS)

Heip, C.; Craeymeersch, J. A.

1995-03-01

Coherent assemblages of marine benthic species have been recognized from the early twentieth century, and the classical papers of Petersen (1914, 1918) were based on studies of limited areas in the North Sea. In 1986, a synoptic survey of the North Sea north to 57°N was undertaken by a group of ten laboratories from seven North Sea countries. The results of this survey have recently been published (Heip et al., 1992a, b; Künitzer et al., 1992; Huys et al., 1992), and some of the results are summarized in this paper. The analysis of the macrofauna is based on slightly more than 700 taxa. In general, the North Sea macrofauna consists of northern species extending south to the northern margins of the Dogger Bank, and southern species extending north to the 100 m depth line. The central North Sea is an area of overlap of southern and northern species, especially around the 70 m depth contour. Consistent groupings of species are recognized that were summarized in seven faunal groupings. Macrofaunal body weight, density and diversity increase linearly towards the north. Macrofaunal biomass for the whole area averages 7 g adwt. m-2 and decreases from south to north. Distribution patterns and trends within the meiofauna were very different. Nematodes, which are the dominant taxon overall, are least abundant in the sandy sediments of the Southern Bight, then increase to a maximum around 53° 30' N and slowly decrease again towards the north. Copepod density and diversity are highest in the Southern Bight, due to the presence of many interstitial species. A large number of species new to science were recorded by the North Sea Benthos Survey and about 1500 species are expected to occur. Copepods show very distinct assemblages according to water depth and sediment type. The contrasting patterns in latitudinal gradients of body weight and number of species of macro- and meiofauna can be only partially explained. Latitude and sediment characteristics, such as grain size and content in plant pigments, and water depth, determine part of the variance in species composition, density and biomass of the benthic fauna, but the patterns that are observed are different for different benthic groups, requiring careful consideration as to their use in biological monitoring procedures. Distributions are related to current patterns in the North Sea, annual temperature variations and availability of food. However, large parts of the variance in many parameters remain unexplained.

Trophic structure on the West Antarctic Peninsula shelf: Detritivory and benthic inertia revealed by δ 13C and δ 15N analysis

NASA Astrophysics Data System (ADS)

Mincks, Sarah L.; Smith, Craig R.; Jeffreys, Rachel M.; Sumida, Paulo Y. G.

2008-11-01

Summer bloom-derived phytodetritus settles rapidly to the seafloor on the West Antarctic Peninsula (WAP) continental shelf, where it appears to degrade relatively slowly, forming a sediment "food bank" for benthic detritivores. We used stable carbon and nitrogen isotopes to examine sources and sinks of particulate organic material (POM) reaching the WAP shelf benthos (550-625 m depths), and to explore trophic linkages among the most abundant benthic megafauna. We measured δ 13C and δ 15N values in major megafaunal taxa ( n=26) and potential food sources, including suspended and sinking POM, ice algae, sediment organic carbon, phytodetritus, and macrofaunal polychaetes. The range in δ 13C values (>14‰) of suspended POM was considerably broader than in sedimentary POC, where little temporal variability in stable isotope signatures was observed. While benthic megafauna also exhibited a broad range of δ 13C values, organic carbon entering the benthic food web appeared to be derived primarily from phytoplankton production, with little input from ice algae. One group of organisms, primarily deposit-feeders, appeared to rely on fresh phytodetritus recovered from the sediments, and sediment organic material that had been reworked by sediment microbes. A second group of animals, including many mobile invertebrate and fish predators, appeared to utilize epibenthic or pelagic food resources such as zooplankton. One surface-deposit-feeding holothurian ( Protelpidia murrayi) exhibited seasonal variability in stable isotope values of body tissue, while other surface- and subsurface-deposit-feeders showed no evidence of seasonal variability in food source or trophic position. Detritus from phytoplankton blooms appears to be the primary source of organic material for the detritivorous benthos; however, seasonal variability in the supply of this material is not mirrored in the sediments, and only to a minor degree in the benthic fauna. This pattern suggests substantial inertia in benthic-pelagic coupling, whereby the sediment ecosystem integrates long-term variability in production processes in the water column above.

Composition and abundance of epibenthic-sledge catches in the South Polar Front of the Atlantic

NASA Astrophysics Data System (ADS)

Brandt, A.; Havermans, C.; Janussen, D.; Jörger, K. M.; Meyer-Löbbecke, A.; Schnurr, S.; Schüller, M.; Schwabe, E.; Brandão, S. N.; Würzberg, L.

2014-10-01

An epibenthic sledge (EBS) was deployed at seven different deep-sea stations along the South Polar Front of the Atlantic in order to explore the composition and abundance of macrofaunal organisms and to identify the most abundant taxa in this transition zone to the Southern Ocean. In total 3,130 specimens were sampled by means of the EBS on board of RV Polarstern during the expedition ANT-XXVIII/3 in the austral summer of 2012. Benthic and suprabenthic Crustacea occurred to be most frequent in the samples. Among those, copepods were by far most numerous, with 1,585 specimens followed by the peracarid taxa Isopoda (236 ind.), Amphipoda (103 ind.), Tanaidacea (78 ind.) and Cumacea (50 ind.). Annelida were represented by a high number of specimens belonging to different polychaete taxa (404 ind.). The molluscan fauna was clearly dominated by Bivalvia (255 ind.), followed in numbers of specimens by Gastropoda (47 ind.). The deep-sea benthos sampled along the Southern Polar Front occurred in surprisingly low abundances, contrasting the largely high surface productivity of the area. Numbers of specimens across different macrofaunal taxa and especially of peracarid crustaceans underscored by far those from South Ocean sites at higher latitudes in the Weddell Sea.

The distribution and diversity of benthic macroinvertebrate fauna in Pondicherry mangroves, India

PubMed Central

2013-01-01

Background Species distribution, abundance and diversity of mangrove benthic macroinvertebrate fauna and the relationships to environmental conditions are important parts of understanding the structure and function of mangrove ecosystems. In this study seasonal variation in the distribution of macrobenthos and related environmental parameters were explored at four mangrove stations along the Pondicherry coast of India, from September 2008 to July 2010. Multivariate statistical analyses, including cluster analysis, principal component analysis and non-multidimensional scales plot were employed to help define trophic status, water quality and benthic characteristic at the four monitoring stations. Results Among the 528 samples collected over 168 ha of mangrove forest 76 species of benthic macroinvertebrate fauna were identified. Macrofauna were mainly composed of deposit feeders, dominated numerically by molluscs and crustaceans. Statistical analyses yielded the following descriptors of benthic macroinvertebrate fauna species distribution: densities between 140–1113 ind. m-2, dominance 0.17-0.50, diversity 1.80-2.83 bits ind-1, richness 0.47-0.74 and evenness 0.45-0.72, equitability 0.38-0.77, berger parker 0.31-0.77 and fisher alpha 2.46-5.70. Increases of species diversity and abundance were recorded during the post monsoon season at station 1 and the lowest diversity was recorded at station 2 during the monsoon season. The pollution indicator organisms Cassidula nucleus, Melampus ceylonicus, Sphaerassiminea minuta were found only at the two most polluted regions, i.e. stations 3 and 4. Benthic macroinvertebrate fauna abundances were inversely related to salinity at the four stations, Based on Bray-Curtis similarity through hierarchical clustering implemented in PAST, it was possible to define three distinct benthic assemblages at the stations. Conclusions From a different multivariate statistical analysis of the different environmental parameters regarding species diversity and abundance of benthic macroinvertebrate fauna, it was found that benthic communities are highly affected by all the environmental parameters governing the distribution and diversity variation of the macrofaunal community in Pondicherry mangroves. Salinity, dissolved oxygen levels, organic matter content, sulphide concentration were the most significant parameters. PMID:23937801

Benthic fluxes in San Francisco Bay

USGS Publications Warehouse

Hammond, Douglas E.; Fuller, C.; Harmon, D.; Hartman, Blayne; Korosec, M.; Miller, L.G.; Rea, R.; Warren, S.; Berelson, W.; Hager, S.W.

1985-01-01

Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal variability is smaller, probably because the annual temperature range in San Francisco Bay is smaller. Budgets constructed for South San Francisco Bay show that large fractions of the net annual productivity of carbon (about 90%) and silica (about 65%) are recycled by the benthos. Substantial rates of simultaneous nitrification and denitrification must occur in shoal areas, apparently resulting in conversion to N2 of 55% of the particulate nitrogen reaching the sediments. In shoal areas, benthic fluxes can replace the water column standing stocks of ammonia in 2-6 days and silica in 17-34 days, indicating the importance of benthic fluxes in the maintenance of productivity. Pore water profiles of nutrients and Rn-222 show that macrofaunal irrigation is extremely important in transport of silica, ammonia, and alkalinity. Calculations of benthic fluxes from these profiles are less accurate, but yield results consistent with chamber measurements and indicate that most of the NH3, SiO2, and alkalinity fluxes are sustained by reactions occurring throughout the upper 20-40 cm of the sediment column. In contrast, O2, CO2, and N + N fluxes must be dominated by reactions occurring within the upper one cm of the sediment-water interface. While most data support the statements made above, a few flux measurements are contradictory and demonstrate the complexity of benthic exchange. ?? 1985 Dr W. Junk Publishers.

Potential changes in benthic macrofaunal distributions from the English Channel simulated under climate change scenarios

NASA Astrophysics Data System (ADS)

Rombouts, Isabelle; Beaugrand, Grégory; Dauvin, Jean-Claude

2012-03-01

Climate-induced changes in the distribution of species are likely to affect the functioning and diversity of marine ecosystems. Therefore, in economic and ecological important areas, such as the English Channel, projections of the future distributions of key species under changing environmental conditions are urgently needed. Ecological Niche Models (ENMs) have been applied successfully to determine potential distributions of species based on the information of the environmental niche of a species (sensu Hutchinson). In this study, the niches of two commercially exploited benthic species, Pecten maximus and Glycymeris glycymeris, and two ecologically important species, Abra alba and Ophelia borealis were derived using four contemporary hydrographic variables, i.e. sea surface temperature, sea surface salinity, water depth and sediment type. Consequently, using these ecological envelopes, the Non-Parametric Probalistic Ecological Niche model (NPPEN) was applied to calculate contemporary probabilities of occurrence for each species in the North East Atlantic and to predict potential re-distributions under the climate change scenario A2 for two time periods 2050-2059 and 2090-2099. Results show general northern displacements of the four benthic species from the English Channel into the North Sea and southern Norwegian coast. The projections mostly indicate a reduction of suitable habitat for benthic species with a notable disappearance of their distributions in the English Channel, except for A. alba. However, interpretations should be treated with caution since many uncertainties and assumptions are attached to ecological niche models in general. Furthermore, opening up potential habitats for benthic species does not necessarily imply that the species will actually occupy these sites in the future. The displacement and colonisation success of species are a function of many other non-climatic factors such as species life histories, dispersal abilities, adaptability and community interactions.

Differences in recovery between deep-sea hydrothermal vent and vent-proximate communities after a volcanic eruption

NASA Astrophysics Data System (ADS)

Gollner, Sabine; Govenar, Breea; Arbizu, Pedro Martinez; Mills, Susan; Le Bris, Nadine; Weinbauer, Markus; Shank, Timothy M.; Bright, Monika

2015-12-01

Deep-sea hydrothermal vents and the surrounding basalt seafloor are subject to major natural disturbance events such as volcanic eruptions. In the near future, anthropogenic disturbance in the form of deep-sea mining could also significantly affect the faunal communities of hydrothermal vents. In this study, we monitor and compare the recovery of insular, highly productive vent communities and vent-proximate basalt communities following a volcanic eruption that destroyed almost all existing communities at the East Pacific Rise, 9°50‧N in 2006. To study the recovery patterns of the benthic communities, we placed settlement substrates at vent sites and their proximate basalt areas and measured the prokaryotic abundance and compared the meio- and macrofaunal species richness and composition at one, two and four years after the eruption. In addition, we collected samples from the overlying water column with a pelagic pump, at one and two years after the volcanic eruption, to determine the abundance of potential meiofauna colonisers. One year after eruption, mean meio- and macrofaunal abundances were not significantly different from pre-eruption values in vent habitats (meio: 8-1838 ind. 64 cm-2 in 2006; 3-6246 ind. 64 cm-2 in 2001/02; macro: 95-1600 ind. 64 cm-2 in 2006; 205-4577 ind. 64 cm-2 in 2001/02) and on non-vent basalt habitats (meio: 10-1922 ind. 64 cm-2 in 2006; 8-328 ind. 64 cm-2 in 2003/04; macro: 14-3351 ind. 64 cm-2 in 2006; 2-63 ind. 64 cm-2 in 2003/04), but species recovery patterns differed between the two habitat types. In the vent habitat, the initial community recovery was relatively quick but incomplete four years after eruption, which may be due to the good dispersal capabilities of vent endemic macrofauna and vent endemic dirivultid copepods. At vents, 42% of the pre-eruption meio- and 39% of macrofaunal species had returned. In addition, some new species not evident prior to the eruption were found. At the tubeworm site Tica, a total of 26 meio- and 19 macrofaunal species were found in 2009, which contrasts with the 24 meio- and 29 macrofauna species detected at the site in 2001/02. In the basalt habitat, community recovery of meiofauna was slower with only 28% of the original 64 species present four years after eruption. The more limited dispersal capabilities of meiofauna basalt specialists such as nematodes or harpacticoid copepods probably caused this pattern. In contrast, 67% of the original 27 macrofaunal species had recolonized the basalt by 2009. Our results suggest that not only vent communities, but also species-rich communities of vent-proximate habitats require attention in conservation efforts.

Consequences of spring phytodetritus sedimentation on the benthic compartment along a depth gradient in the Eastern English Channel.

PubMed

Denis, Lionel; Desroy, Nicolas

2008-11-01

Phaeocystis blooms are of major importance in the Eastern English Channel, where they significantly contribute to spring organic matter input with chlorophyll concentrations commonly higher than 30 microgl(-1) in the water column. Post-bloom deposition of Phaeocystis derived mucilaginous compounds has been shown to have a major importance on benthic intertidal systems, but resulting mineralization processes and consequences on the macrobenthic compartment remain poorly documented in subtidal areas. In this frame, a study was performed along the French coast of the English Channel to quantify mineralization processes, as well as potential consequences on subtidal sediments, especially their geochemistry and associated macrofaunal communities. Seven stations were studied along a depth gradient during four cruises: before (March), during (April, May) and after (June) the spring bloom. Sediment characteristics and organic carbon content were described, as well as sediment-water fluxes of oxygen and ammonium. Macrofaunal characteristics were also analyzed. Stations were chosen as representative of the various benthic communities present in the area, which are directly linked to the granulometric characteristics of the sediments. To account for the general functioning of the water column, characterized by a coastal flow where higher concentrations of Phaeocystis are generally recorded, similar communities were sampled inshore and offshore, when possible: (i) the Abra alba community located only close to the coast, (ii) the Ophelia borealis community located inshore and offshore, and (iii) the Amphioxus lanceolatus community located inshore and offshore. Generally, low exchange rates of oxygen and ammonium were measured (respectively, in the range 50-150 micromol O2 m(-2)h(-1) and -25 to 35 micromol NH4+ m(-2)h(-1)) between the water column and the muddy-sand to coarse sand permeable sediments, as a consequence of the low organic carbon content due to the high hydrodynamic forcing. As a consequence of organic matter accumulation in surficial sediments probably resulting from Phaeocystis post-bloom deposition, an increase of sediment oxygen demand and ammonium release was clearly evidenced up to 660 micromol O2 m(-2)h(-1) and 205 micromol NH4+ m(-2)h(-1) in May, only in stations located close to the coast (<8 kms), in the A. alba community. Despite those significant biogeochemical changes in surficial sediments, no significant consequence was pointed out on macrofauna, neither in the O. borealis and A. lanceolatus communities, nor in the coastal A. alba community. Most of the temporal variations recorded might be attributed to the common spring population dynamics, but this study highlights the potential use of geochemical parameters as a forewarning signal of benthic disequilibrium.

Are hotspots always hotspots? The relationship between diversity, resource and ecosystem functions in the Arctic.

PubMed

Link, Heike; Piepenburg, Dieter; Archambault, Philippe

2013-01-01

The diversity-ecosystem function relationship is an important topic in ecology but has not received much attention in Arctic environments, and has rarely been tested for its stability in time. We studied the temporal variability of benthic ecosystem functioning at hotspots (sites with high benthic boundary fluxes) and coldspots (sites with lower fluxes) across two years in the Canadian Arctic. Benthic remineralisation function was measured as fluxes of oxygen, silicic acid, phosphate, nitrate and nitrite at the sediment-water interface. In addition we determined sediment pigment concentration and taxonomic and functional macrobenthic diversity. To separate temporal from spatial variability, we sampled the same nine sites from the Mackenzie Shelf to Baffin Bay during the same season (summer or fall) in 2008 and 2009. We observed that temporal variability of benthic remineralisation function at hotspots is higher than at coldspots and that taxonomic and functional macrobenthic diversity did not change significantly between years. Temporal variability of food availability (i.e., sediment surface pigment concentration) seemed higher at coldspot than at hotspot areas. Sediment chlorophyll a (Chl a) concentration, taxonomic richness, total abundance, water depth and abundance of the largest gallery-burrowing polychaete Lumbrineristetraura together explained 42% of the total variation in fluxes. Food supply proxies (i.e., sediment Chl a and depth) split hot- from coldspot stations and explained variation on the axis of temporal variability, and macrofaunal community parameters explained variation mostly along the axis separating eastern from western sites with hot- or coldspot regimes. We conclude that variability in benthic remineralisation function, food supply and diversity will react to climate change on different time scales, and that their interactive effects may hide the detection of progressive change, particularly at hotspots. Time-series of benthic functions and its related parameters should be conducted at both hot- and coldspots to produce reliable predictive models.

Submarine groundwater discharges create unique benthic communities in a coastal sandy marine environment

NASA Astrophysics Data System (ADS)

Leitão, Francisco; Encarnação, João; Range, Pedro; Schmelz, Rüdiger M.; Teodósio, Maria A.; Chícharo, Luís

2015-09-01

In this study we assessed the small-scale effects of submarine groundwater discharges (SGD) on macrofaunal assemblages associated with shallow sandy sediments along the south coast of Portugal. Corer samples were collected in a (1) subtidal seep, (2) at the edge of the seep (periphery) and (3) in the surrounding area. Community structure varied across areas, with diversity, species richness and evenness generally low at seep relatively to the surrounding area. Community composition within the seep was reduced to a small number of taxa, although total abundance was similar between seeps and surrounding areas. The seep was characterized by a distinct hydrological environment, with lower salinity and pH, relative to the surroundings sandy areas. More than 93% of the benthic macrofauna in the seep was dominated by Lumbricillus lineatus (enchytraeid oligochaetes). This study is the first to record the presence of this euryaline species in Portuguese marine waters. In the surrounding area Spionidae Polychaetes and Bathyporeia sp. (Amphipoda) were the most frequent and abundant taxa. These findings provide evidence for a direct association between SGD effect and the composition of benthic marine assemblages. The patchy habitat created by groundwater seep allowed euryhaline species with short and fast recruitment times to occur in a fully marine environment. Whether this pattern is consistent, or only occurs when smooth favorable sea conditions are not superimposed on the groundwater effect remains uncertain.

Biological control of trace metal and organometal benthic fluxes in a eutrophic lagoon (Thau Lagoon, Mediterranean Sea, France)

NASA Astrophysics Data System (ADS)

Point, D.; Monperrus, M.; Tessier, E.; Amouroux, D.; Chauvaud, L.; Thouzeau, G.; Jean, F.; Amice, E.; Grall, J.; Leynaert, A.; Clavier, J.; Donard, O. F. X.

2007-04-01

In situ benthic chamber experiments were conducted in the Thau Lagoon that allowed the simultaneous determination of the benthic exchanges of trace metals (Cd, Co, Cu, Mn, Pb and U) and mercury species (iHg and MMHg). Fluxes of organotin compounds (MBT, DBT and TBT) were also investigated for the first time. The benthic incubations were performed during two campaigns at four stations that presented different macrobenthic and macrophytic species distribution and abundance (see [Thouzeau, G., Grall, J., Clavier, J., Chauvaud, L., Jean, F., Leynaert, A., Longpuirt, S., Amice, E., Amouroux, D., 2007. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France). Estuarine, Coastal and Shelf Science 72 (3), 432 446.]). The results indicate that most of the flux intensity as well as the temporal and spatial variability can be explained by the combined influence of microscale and macroscale processes. Microscale changes were identified using Mn flux as a good indicator of the redox conditions at the sediment water interface, and by extension, as an accurate proxy of benthic fluxes for most trace metals and mercury species. We also observed that the redox gradient at the interface is promoted by both microbial and macrobenthic species activity that governs O2 budgets. Macroscale processes have been investigated considering macrobenthic organisms activity (macrofauna and macroalgal cover). The density of such macroorganisms is able to explain most of the spatial and temporal variability of the benthic metal fluxes within a specific site. A tentative estimation of the flux of metals and organometals associated with deposit feeder and suspension feeder activity was found to be in the range of the flux determined within the chambers for most considered elements. Furthermore, a light/dark incubation investigating a dense macroalgal cover present at the sediment surface illustrates the role of photosynthetic activity in controlling benthic exchanges. Significant changes in benthic flux intensity and/or direction were reported for all redox sensitive elements (Cd, Co, Cu, Mn, Pb, U, and iHg). For MMHg and organotin species, other complimentary processes such as photodegradation/uptake and hydrophobic absorption/desorption need to be considered. This work demonstrates that the processes governing benthic exchanges are complex and that benthic organisms play a major role in the significant seasonal, diurnal and spatial variability of trace metals and organometals benthic fluxes in the lagoon.

Effects of wave energy converters on the surrounding soft-bottom macrofauna (west coast of Sweden).

PubMed

Langhamer, O

2010-06-01

Offshore wave energy conversion is expected to develop, thus contributing to an increase in submerged constructions on the seabed. An essential concern related to the deployment of wave energy converters (WECs) is their possible impact on the surrounding soft-bottom habitats. In this study, the macrofaunal assemblages in the seabed around the wave energy converters in the Lysekil research site on the Swedish west coast and a neighbouring reference site were examined yearly during a period of 5 years (2004-2008). Macrobenthic communities living in the WECs' surrounding seabed were mainly composed by organisms typical for the area and depth off the Swedish west coast. At both sites the number of individuals, number of species and biodiversity were low, and were mostly small, juvenile organisms. The species assemblages during the first years of sampling were significantly different between the Lysekil research site and the nearby reference site with higher species abundance in the research site. The high contribution to dissimilarities was mostly due to polychaetes. Sparse macrofaunal densities can be explained by strong hydrodynamic forces and/or earlier trawling. WECs may alter the surrounding seabed with an accumulation of organic matter inside the research area. This indicates that the deployment of WECs in the Lysekil research site tends to have rather minor direct ecological impacts on the surrounding benthic community relative to the natural high variances.

Approach to assess consequences of hypoxia disturbance events for benthic ecosystem functioning

NASA Astrophysics Data System (ADS)

Gogina, Mayya; Darr, Alexander; Zettler, Michael L.

2014-01-01

Our study challenges the functional approach for its usefulness in assessing the consequences of hypoxia disturbance events on macrofaunal communities in the south-western Baltic Sea. Time series for two decades of observations from two monitoring stations, one in the Fehmarnbelt (exposed to aperiodic hypoxia), and another in the Darss Rise (normoxic conditions) is used. Our results designate differences of functional structure of benthic fauna communities between sites based on biological traits that characterise species role in modifying the environment, behavioural strategies, morphology and life history, thus suggesting differences in functioning. Hypoxic years reveal sharp increase of the role of sedentary species, suspension filter feeders, epibenthic structures, globulose form, medium/large size of individuals, preponderance of species with long lifespan (caused for instance by remaining ocean quahog). The link of functional and species diversity to the stagnation periods is proposed for the Darss station that exhibit continuous changes and low temporal variability of traits distribution. Before the major inflow in 1993 the increased role of small size organisms, containing calcium carbonate, filter feeders and grazers, higher presence of semi-pelagic species is observed. The hypoxic events and water renewal processes impact the communities not only in respect to species composition but also functionally.

Detection of environmental impacts of shrimp farming through multiple lines of evidence.

PubMed

Hatje, Vanessa; de Souza, Manuel M; Ribeiro, Luisa F; Eça, Gilmara F; Barros, Francisco

2016-12-01

In order to evaluate the impact of semi-intensive shrimp farming, comparisons between Control and Impact areas were made based on multiple lines of evidence using an asymmetrical design. Water and sediment samples were collected in four shrimp farms located in Todos os Santos Bay, Bahia, Brazil. Nutrients, trace elements and macrobenthic assemblages were evaluated using uni- and multivariate analyzes. Significant differences were observed between Impact and Control areas for the water column dataset (i.e., ancillary variables, SPM, dissolved nutrients and major and trace elements in SPM), whereas no significant differences were observed for the chemistry of sediments. Macrobenthic assemblages were negatively affected by shrimp farm activities. Impacted sites presented the lowest abundance, richness and different structure of macrofaunal benthic assemblages. Farms clearly produced negative impacts in the Todos os Santos Bay. This conclusion was only possible to be reached through the use of multiple lines of evidence. Chemistry and benthic assemblages data combined produced a better description of the quality and impacts of the evaluated environments. Different conclusions would have been reached if chemistry and ecology results were studied separately vs. together. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ecological Functioning in Two Mid-Atlantic Bight Submarine Canyons: Macrofauna Community Trends and the Role of Canyon Specific Processes

NASA Astrophysics Data System (ADS)

Robertson, C.; Bourque, J. R.; Davies, A. J.; Duineveld, G.; Mienis, F.; Brooke, S.; Ross, S. W.; Demopoulos, A. W.

2016-02-01

Submarine canyons are complex systems, acting as major conduits of organic matter along continental shelves and promoting gradients in food resources, turbidity flows, habitat heterogeneity, and areas of sediment resuspension and deposition. In the western North Atlantic, a large multidisciplinary program was conducted in two major Mid-Atlantic Bight (MAB) canyons (Baltimore and Norfolk canyons). This Atlantic Deepwater Canyons project was funded by BOEM, NOAA, and USGS. Here we investigate the `canyon effect' on benthic ecosystem ecology and functioning of two canyon systems by defining canyon specific processes influencing MAB shelf benthic community trends. Sediment cores were collected in 2012 and 2013 with a NIOZ box corer along the main axes ( 180-1200m) of Baltimore and Norfolk Canyon and at comparable depths on the adjacent continental slope. Whole community macrofaunal (>300 μm) abundance and biomass data provided insight into community trends across depth and biogeochemical gradients by coupling diversity metrics and biological trait analyses with sediment biogeochemistry and hydrodynamic data. The canyons exhibited clear differences in sediment profiles, hydrodynamic regimes and enrichment depocenters as well as significantly distinct infauna communities. Interestingly, both canyons showed bimodal distributions in abundances and diversity of infauna and a shallowing of species maxima which was not present on adjacent slopes. We hypothesize that physical canyon processes are important regulators in the depth of observed species maxima and community functioning on the MAB shelf, on local and regional scales. Unique sediment dynamics, organic enrichment, and hydrographic conditions were significant factors in structuring benthic community differences in MAB canyons The study provides a complete benthic infaunal appraisal of two canyon systems in the western Atlantic, incorporating biogeochemistry and oceanography to increase our understanding of canyon ecosystem ecology and provide baseline information on canyon functioning.

The Bering Strait Region: A Window into Changing Benthic Populations in Response to Varying Subarctic-Arctic Connectivity and Ecosystem Dynamics

NASA Astrophysics Data System (ADS)

Grebmeier, J. M.; Cooper, L. W.; Moore, S. E.

2016-02-01

A key ecological organizing principle for the northern Bering Sea and the adjoining southern Chukchi Sea just north of Bering Strait is that the shallow, seasonally productive waters lead to strong pelagic-benthic coupling to the sea floor, with deposition of fresh chlorophyll coinciding with the spring bloom as sea ice retreats. Both in situ production and advection of upstream phytodetritus to these regions support persistent biological hotspots that connect benthic prey to upper trophic benthivores. This northern marine ecosystem is dominated by marine macroinvertebrates (e.g. clams, polychaetes, sipunculids, and amphipods) that feed on the high production deposited rapidly to the seafloor, which in turn serve as food resources for diving mammals and seabirds, such as gray whales, bearded seals, eiders, and walruses. Between St. Lawrence Island and Bering Strait and northwards into the Chukchi Sea, the persistence of seasonal sea ice has significantly declined over the past two decades, and along with warming seawater temperatures, these changes have potential ramifications to ecosystem structure. Times-series data over the last 25 years indicate that these regions have experienced a northward shift in macrofaunal composition and a decline in core benthic biomass that matches patterns of reduced sea ice, warming seawater, and changing sediment grain size that relates to varying current patterns. This presentation will discuss these data in the context of both process studies from the region and results from the Distributed Biological Observatory (DBO), an international network of time series transects that is providing a framework to evaluate status and trends on a latitudinal bases in the Pacific Arctic region.

Is benthic food web structure related to diversity of marine macrobenthic communities?

NASA Astrophysics Data System (ADS)

Sokołowski, A.; Wołowicz, M.; Asmus, H.; Asmus, R.; Carlier, A.; Gasiunaité, Z.; Grémare, A.; Hummel, H.; Lesutiené, J.; Razinkovas, A.; Renaud, P. E.; Richard, P.; Kędra, M.

2012-08-01

Numerical structure and the organisation of food webs within macrozoobenthic communities has been assessed in the European waters (Svalbard, Barents Sea, Baltic Sea, North Sea, Atlantic Ocean and the Mediterranean Sea) to address the interactions between biodiversity and ecosystem functioning. Abundance and classical species diversity indices (S, H', J) of macrofaunal communities were related to principal attributes of food webs (relative trophic level and food chain length, FCL) that were determined from carbon and nitrogen stable isotope values. Structure of marine macrobenthos varies substantially at a geographical scale; total abundance ranges from 63 ind. m-2 to 34,517 ind. m-2, species richness varies from 3 to 166 and the Shannon-Weaver diversity index from 0.26 to 3.26 while Pielou's evenness index is below 0.73. The major source of energy for macrobenthic communities is suspended particulate organic matter, consisting of phytoplankton and detrital particles, sediment particulate organic matter, and microphytobenthos in varying proportions. These food sources support the presence of suspension- and deposit-feeding communities, which dominate numerically on the sea floor. Benthic food webs include usually four to five trophic levels (FCL varies from 3.08 to 4.86). Most species are assigned to the second trophic level (primary consumers), fewer species are grouped in the third trophic level (secondary consumers), and benthic top predators are the least numerous. Most species cluster primarily at the lowest trophic level that is consistent with the typical organization of pyramidal food webs. Food chain length increases with biodiversity, highlighting a positive effect of more complex community structure on food web organisation. In more diverse benthic communities, energy is transferred through more trophic levels while species-poor communities sustain a shorter food chain.

Benthic phosphorus regeneration in the Potomac River Estuary

USGS Publications Warehouse

Callender, E.

1982-01-01

The flux of dissolved reactive phosphate from Potomac riverine and estuarine sediments is controlled by processes occurring at the water-sediment interface and within surficial sediment. In situ benthic fluxes (0.1 to 2.0 mmoles m-2 day-1) are generally five to ten times higher than calculated diffusive fluxes (0.020 to 0.30 mmoles m-2 day-1). The discrepancy between the two flux estimates is greatest in the transition zone (river mile 50 to 70) and is attributd to macrofaunal irrigation. Both in situ and diffusive fluxes of dissolved reactive phosphate from Potomac tidal river sediments are low while those from anoxic lower estuarine sediments are high. The net accumulation rate of phosphorus in benthic sediment exhibits an inverse pattern. Thus a large fraction of phosphorus is retained by Potomac tidal river sediments, which contain a surficial oxidized layer and oligochaete worms tolerant of low oxygen conditions, and a large fraction of phosphorus is released from anoxic lower estuary sediments. Tidal river sediment pore waters are in equilibrium with amorphous Fe (OH)3 while lower estuary pore waters are significantly undersaturated with respect to this phase. Benthic regeneration of dissolved reactive phosphorus is sufficient to supply all the phosphorus requirements for net primary production in the lower tidal river and transition-zone waters of the Potomac River Estuary. Benthic regeneration supplies approximately 25% as much phosphorus as inputs from sewage treatment plants and 10% of all phosphorus inputs to the tidal Potomac River. When all available point source phosphorus data are put into a steady-state conservation of mass model and reasonable coefficients for uptake of dissolved phosphorus, remineralization of particulate phosphorus, and sedimentation of particulate phosphorus are used in the model, a reasonably accurate simulation of dissolved and particulate phosphorus in the water column is obtained for the summer of 1980. ?? 1982 Dr W. Junk Publishers.

Effects of microplastics on European flat oysters, Ostrea edulis and their associated benthic communities.

PubMed

Green, Dannielle Senga

2016-09-01

Plastic pollution is recognised as an emerging threat to aquatic ecosystems, with microplastics now the most abundant type of marine debris. Health effects caused by microplastics have been demonstrated at the species level, but impacts on ecological communities remain unknown. In this study, impacts of microplastics on the health and biological functioning of European flat oysters (Ostrea edulis) and on the structure of associated macrofaunal assemblages were assessed in an outdoor mesocosm experiment using intact sediment cores. Biodegradable and conventional microplastics were added at low (0.8 μg L(-1)) and high (80 μg L(-1)) doses in the water column repeatedly for 60 days. Effects on the oysters were minimal, but benthic assemblage structures differed and species richness and the total number of organisms were ∼1.2 and 1.5 times greater in control mesocosms than in those exposed to high doses of microplastics. Notably, abundances of juvenile Littorina sp. (periwinkles) and Idotea balthica (an isopod) were ∼2 and 8 times greater in controls than in mesocosms with the high dose of either type of microplastic. In addition, the biomass of Scrobicularia plana (peppery furrow shell clam) was ∼1.5 times greater in controls than in mesocosms with the high dose of microplastics. This work indicates that repeated exposure to high concentrations of microplastics could alter assemblages in an important marine habitat by reducing the abundance of benthic fauna. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of an invasive polychaete on benthic phosphorus cycling at sea basin scale: An ecosystem disservice.

PubMed

Sandman, Antonia Nyström; Näslund, Johan; Gren, Ing-Marie; Norling, Karl

2018-05-05

Macrofaunal activities in sediments modify nutrient fluxes in different ways including the expression of species-specific functional traits and density-dependent population processes. The invasive polychaete genus Marenzelleria was first observed in the Baltic Sea in the 1980s. It has caused changes in benthic processes and affected the functioning of ecosystem services such as nutrient regulation. The large-scale effects of these changes are not known. We estimated the current Marenzelleria spp. wet weight biomass in the Baltic Sea to be 60-87 kton (95% confidence interval). We assessed the potential impact of Marenzelleria spp. on phosphorus cycling using a spatially explicit model, comparing estimates of expected sediment to water phosphorus fluxes from a biophysical model to ecologically relevant experimental measurements of benthic phosphorus flux. The estimated yearly net increases (95% CI) in phosphorous flux due to Marenzelleria spp. were 4.2-6.1 kton based on the biophysical model and 6.3-9.1 kton based on experimental data. The current biomass densities of Marenzelleria spp. in the Baltic Sea enhance the phosphorus fluxes from sediment to water on a sea basin scale. Although high densities of Marenzelleria spp. can increase phosphorus retention locally, such biomass densities are uncommon. Thus, the major effect of Marenzelleria seems to be a large-scale net decrease in the self-cleaning capacity of the Baltic Sea that counteracts human efforts to mitigate eutrophication in the region.

Macrofaunal production and biological traits: Spatial relationships along the UK continental shelf

NASA Astrophysics Data System (ADS)

Bolam, S. G.; Eggleton, J. D.

2014-04-01

Biological trait analysis (BTA) is increasingly being employed to improve our understanding of the ecological functioning of marine benthic invertebrate communities. However, changes in trait composition are seldomly compared with concomitant changes in metrics of ecological function. Consequently, inferences regarding the functional implications of any changes are often anecdotal; we currently have a limited understanding of the functional significance of the traits commonly used. In this study, we quantify the relationship between benthic invertebrate trait composition and secondary production estimates using data spanning almost the breadth of the UK continental shelf. Communities described by their composition of 10 traits representing life history, morphology and behaviour showed strong relationships with variations in total secondary production. A much weaker relationship was observed for community productivity (or P:B), a measure of rate of energy turnover. Furthermore, the relationship between total production and multivariate taxonomic community composition was far weaker than that for trait composition. Indeed, the similarities between communities as defined by taxonomy were very different from those depicted by their trait composition. That is, as many studies have demonstrated, taxonomically different communities may display similar trait compositions, and vice versa. Finally, we found that descriptions of community trait composition vary greatly depending on whether abundance or biomass is used as the enumeration weighting method during BTA, and trait assessments based on biomass produced better relations with secondary production than those based on abundance. We discuss the significance of these findings with respect to BTA using marine benthic invertebrates.

Decomposition of jellyfish carrion in situ: Short-term impacts on infauna, benthic nutrient fluxes and sediment redox conditions.

PubMed

Chelsky, Ariella; Pitt, Kylie A; Ferguson, Angus J P; Bennett, William W; Teasdale, Peter R; Welsh, David T

2016-10-01

Jellyfish often form blooms that persist for weeks to months before they collapse en masse, resulting in the sudden release of large amounts of organic matter to the environment. This study investigated the biogeochemical and ecological effects of the decomposition of jellyfish in a shallow coastal lagoon in New South Wales, Australia. Catostylus mosaicus carrion was added to the surface of shallow sub-tidal sediments and biogeochemical parameters and macrofaunal abundance immediately below the jellyfish carrion were measured over three days. Sediment plots without jellyfish served as controls. Sediment oxygen demand and carbon and nitrogen efflux increased by up to 60-fold in the jellyfish plots, compared to control plots, and dissolved organic nutrient fluxes were more sustained than in previous studies due to the use of fresh rather than frozen biomass. The decomposing jellyfish progressively altered sediment redox conditions, indicated by an increase in porewater iron (II) and sulfide concentrations measured by high-resolution in situ diffusive samplers. Abundance of some macrofaunal taxa in the jellyfish plots decreased relative to controls, however, the abundance of a carnivorous gastropod, which was presumably feeding on the carrion, increased in the jellyfish plots. While jellyfish carrion may be a food source for some macrofauna, low oxygen conditions coupled with the accumulation of toxic dissolved sulfides in the near-surface sediments may explain the overall change in the macroinfaunal community. Copyright © 2016 Elsevier B.V. All rights reserved.

Spatial scale-dependent habitat heterogeneity influences submarine canyon macrofaunal abundance and diversity off the Main and Northwest Hawaiian Islands

NASA Astrophysics Data System (ADS)

De Leo, Fabio C.; Vetter, Eric W.; Smith, Craig R.; Rowden, Ashley A.; McGranaghan, Matthew

2014-06-01

The mapping of biodiversity on continental margins on landscape scales is highly relevant to marine spatial planning and conservation. Submarine canyons are widespread topographic features on continental and island margins that enhance benthic biomass across a range of oceanic provinces and productivity regimes. However, it remains unclear whether canyons enhance faunal biodiversity on landscape scales relevant to marine protected area (MPA) design. Furthermore, it is not known which physical attributes and heterogeneity metrics can provide good surrogates for large-scale mapping of canyon benthic biodiversity. To test mechanistic hypotheses evaluating the role of different canyon-landscape attributes in enhancing benthic biodiversity at different spatial scales we conducted 34 submersible dives in six submarine canyons and nearby slopes in the Hawaiian archipelago, sampling infaunal macrobenthos in a depth-stratified sampling design. We employed multivariate multiple regression models to evaluate sediment and topographic heterogeneity, canyon transverse profiles, and overall water mass variability as potential drivers of macrobenthic community structure and species richness. We find that variables related to habitat heterogeneity at medium (0.13 km2) and large (15-33 km2) spatial scales such as slope, backscatter reflectivity and canyon transverse profiles are often good predictors of macrobenthic biodiversity, explaining 16-30% of the variance. Particulate organic carbon (POC) flux and distance from shore are also important variables, implicating food supply as a major predictor of canyon biodiversity. Canyons off the high Main Hawaiian Islands (Oahu and Moloka'i) are significantly affected by organic enrichment, showing enhanced infaunal macrobenthos abundance, whereas this effect is imperceptible around the low Northwest Hawaiian Islands (Nihoa and Maro Reef). Variable canyon alpha-diversity and high rates of species turnover (beta-diversity), particularly for polychaetes, suggest that canyons play important roles in maintaining high levels of regional biodiversity in the extremely oligotrophic system of the North Pacific Subtropical Gyre. This information is of key importance to the process of MPA design, suggesting that canyon habitats be explicitly included in marine spatial planning. The low-islands of Nihoa and Maro Reef in the NWHI showed a lack of sustained input of terrestrial and macrolagae detritus, likely having an influence on the observed low macrofaunal abundances (see further discussion of ‘canyon effects’ in Section 4.3), and showing the fundamental role of coastal landscape characteristics in determining the amount and nature of allochthonous organic matter entering the system. Total and highly-mobile invertebrate megafauna abundances were two to three times higher in the submarine canyons and slopes of the MHI contrasted with the NWHI (Vetter et al., 2010), also demonstrating the role of this larger contribution of terrestrial and coastal organic enrichment in the MHI contrasted with the NWHI.

Diversity, Abundance and Community Structure of Benthic Macro- and Megafauna on the Beaufort Shelf and Slope

PubMed Central

Nephin, Jessica; Juniper, S. Kim; Archambault, Philippe

2014-01-01

Diversity and community patterns of macro- and megafauna were compared on the Canadian Beaufort shelf and slope. Faunal sampling collected 247 taxa from 48 stations with box core and trawl gear over the summers of 2009–2011 between 50 and 1,000 m in depth. Of the 80 macrofaunal and 167 megafaunal taxa, 23% were uniques, present at only one station. Rare taxa were found to increase proportional to total taxa richness and differ between the shelf ( 100 m) where they tended to be sparse and the slope where they were relatively abundant. The macrofauna principally comprised polychaetes with nephtyid polychaetes dominant on the shelf and maldanid polychaetes (up to 92% in relative abundance/station) dominant on the slope. The megafauna principally comprised echinoderms with Ophiocten sp. (up to 90% in relative abundance/station) dominant on the shelf and Ophiopleura sp. dominant on the slope. Macro- and megafauna had divergent patterns of abundance, taxa richness ( diversity) and diversity. A greater degree of macrofaunal than megafaunal variation in abundance, richness and diversity was explained by confounding factors: location (east-west), sampling year and the timing of sampling with respect to sea-ice conditions. Change in megafaunal abundance, richness and diversity was greatest across the depth gradient, with total abundance and richness elevated on the shelf compared to the slope. We conclude that megafaunal slope taxa were differentiated from shelf taxa, as faunal replacement not nestedness appears to be the main driver of megafaunal diversity across the depth gradient. PMID:25007347

Diversity, abundance and community structure of benthic macro- and megafauna on the Beaufort shelf and slope.

PubMed

Nephin, Jessica; Juniper, S Kim; Archambault, Philippe

2014-01-01

Diversity and community patterns of macro- and megafauna were compared on the Canadian Beaufort shelf and slope. Faunal sampling collected 247 taxa from 48 stations with box core and trawl gear over the summers of 2009-2011 between 50 and 1,000 m in depth. Of the 80 macrofaunal and 167 megafaunal taxa, 23% were uniques, present at only one station. Rare taxa were found to increase proportional to total taxa richness and differ between the shelf (< 100 m) where they tended to be sparse and the slope where they were relatively abundant. The macrofauna principally comprised polychaetes with nephtyid polychaetes dominant on the shelf and maldanid polychaetes (up to 92% in relative abundance/station) dominant on the slope. The megafauna principally comprised echinoderms with Ophiocten sp. (up to 90% in relative abundance/station) dominant on the shelf and Ophiopleura sp. dominant on the slope. Macro- and megafauna had divergent patterns of abundance, taxa richness (α diversity) and β diversity. A greater degree of macrofaunal than megafaunal variation in abundance, richness and β diversity was explained by confounding factors: location (east-west), sampling year and the timing of sampling with respect to sea-ice conditions. Change in megafaunal abundance, richness and β diversity was greatest across the depth gradient, with total abundance and richness elevated on the shelf compared to the slope. We conclude that megafaunal slope taxa were differentiated from shelf taxa, as faunal replacement not nestedness appears to be the main driver of megafaunal β diversity across the depth gradient.

Cold-seep-like macrofaunal communities in organic- and sulfide-rich sediments of the Congo deep-sea fan

NASA Astrophysics Data System (ADS)

Olu, K.; Decker, C.; Pastor, L.; Caprais, J.-C.; Khripounoff, A.; Morineaux, M.; Ain Baziz, M.; Menot, L.; Rabouille, C.

2017-08-01

Methane-rich fluids arising from organic matter diagenesis in deep sediment layers sustain chemosynthesis-based ecosystems along continental margins. This type of cold seep develops on pockmarks along the Congo margin, where fluids migrate from deep-buried paleo-channels of the Congo River, acting as reservoirs. Similar ecosystems based on shallow methane production occur in the terminal lobes of the present-day Congo deep-sea fan, which is supplied by huge quantities of primarily terrestrial material carried by turbiditic currents along the 800 km channel, and deposited at depths of up to nearly 5000 m. In this paper, we explore the effect of this carbon enrichment of deep-sea sediments on benthic macrofauna, along the prograding lobes fed by the current active channel, and on older lobes receiving less turbiditic inputs. Macrofaunal communities were sampled using either USNEL cores on the channel levees, or ROV blade cores in the chemosynthesis-based habitats patchily distributed in the active lobe complex. The exceptionally high organic content of the surface sediment in the active lobe complex was correlated with unusual densities of macrofauna for this depth, enhanced by a factor 7-8, compared with those of the older, abandoned lobe, whose sediment carbon content is still higher than in Angola Basin at same depth. Macrofaunal communities, dominated by cossurid polychaetes and tanaids were also more closely related to those colonizing low-flow cold seeps than those of typical deep-sea sediment. In reduced sediments, microbial mats and vesicomyid bivalve beds displayed macrofaunal community patterns that were similar to their cold-seep counterparts, with high densities, low diversity and dominance of sulfide-tolerant polychaetes and gastropods in the most sulfidic habitats. In addition, diversity was higher in vesicomyid bivalve beds, which appeared to bio-irrigate the upper sediment layers. High beta-diversity is underscored by the variability of geochemical gradients in vesicomyid assemblages, and by the vesicomyid population characteristics that vary in density, size and composition. By modifying the sediment geochemistry differently according to their morphology and physiology, the different vesicomyid species play an important role structuring macrofauna composition and vertical distribution. Dynamics of turbiditic deposits at a longer temporal scale (thousands of years) and their spatial distribution in the lobe area also resulted in high heterogeneity of the "cold-seep-like communities". Dynamics of chemosynthetic habitats and associated macrofauna in the active lobe area resembled those previously observed at the Regab pockmark along the Congo margin and rapid succession is expected to cope with high physical disturbance by frequent turbiditic events and huge sedimentation rates. Finally, we propose a model of the temporal evolution of these peculiar habitats and communities on longer timescales in response to changes in distributary channels within the lobe complex.

Influence of Benthic Macrofauna as a Spatial Structuring Agent for Juvenile Haddock (Melanogrammus aeglefinus) on the Eastern Scotian Shelf, Atlantic Canada.

PubMed

Rincón, Beatriz; Kenchington, Ellen L

2016-01-01

We examined the habitat of juvenile haddock on the eastern Scotian Shelf (off Nova Scotia, Canada) in relation to grab-sampled benthic macrofaunal invertebrate species assemblages in order to determine whether there were significant differences in benthic macrofauna between areas of historically persistent high and low juvenile haddock abundance. Our analyses were conducted over two spatial scales in each of two years: among banks (Emerald, Western and Sable Island), approximately 60 km distant from each other, and between areas of high and low juvenile haddock abundance at distances of 10 to 30 km-all in an area that had not experienced groundfishing in the decade prior to sampling. We also examined fine-scale (10s of metres) within-site variability in the macrofauna and used surficial sediment characteristics, along with hydrographic variables, to identify environmental correlates. PERMANOVA identified statistically significant differences in biomass, density and composition of the benthos associated with juvenile haddock abundance; however it was difficult to determine whether the results had biological relevance. Post hoc tests showed that these differences occurred only on Sable Island Bank where both fish and benthos may have been independently responding to sediment type which was most different there (100% sand in the area of low haddock abundance vs. 22% gravel in the area of high haddock abundance). In total, 383 benthic taxa representing 13 phyla were identified. Annelida was the most specious phylum (36.29% of taxa, representing 33 families), followed by Arthropoda (with Crustaceans, mostly Amphipoda, accounting for 25.07% of the total number of taxa). The strongest pattern in the macrofauna was expressed at the largest scale, between banks, accounting for approximately 25% of the variation in the data. Emerald Bank, deeper, warmer and saltier than the Western and Sable Island Banks, had a distinctive fauna.

Influence of Benthic Macrofauna as a Spatial Structuring Agent for Juvenile Haddock (Melanogrammus aeglefinus) on the Eastern Scotian Shelf, Atlantic Canada

PubMed Central

2016-01-01

We examined the habitat of juvenile haddock on the eastern Scotian Shelf (off Nova Scotia, Canada) in relation to grab-sampled benthic macrofaunal invertebrate species assemblages in order to determine whether there were significant differences in benthic macrofauna between areas of historically persistent high and low juvenile haddock abundance. Our analyses were conducted over two spatial scales in each of two years: among banks (Emerald, Western and Sable Island), approximately 60 km distant from each other, and between areas of high and low juvenile haddock abundance at distances of 10 to 30 km–all in an area that had not experienced groundfishing in the decade prior to sampling. We also examined fine-scale (10s of metres) within-site variability in the macrofauna and used surficial sediment characteristics, along with hydrographic variables, to identify environmental correlates. PERMANOVA identified statistically significant differences in biomass, density and composition of the benthos associated with juvenile haddock abundance; however it was difficult to determine whether the results had biological relevance. Post hoc tests showed that these differences occurred only on Sable Island Bank where both fish and benthos may have been independently responding to sediment type which was most different there (100% sand in the area of low haddock abundance vs. 22% gravel in the area of high haddock abundance). In total, 383 benthic taxa representing 13 phyla were identified. Annelida was the most specious phylum (36.29% of taxa, representing 33 families), followed by Arthropoda (with Crustaceans, mostly Amphipoda, accounting for 25.07% of the total number of taxa). The strongest pattern in the macrofauna was expressed at the largest scale, between banks, accounting for approximately 25% of the variation in the data. Emerald Bank, deeper, warmer and saltier than the Western and Sable Island Banks, had a distinctive fauna. PMID:27649419

Bioturbation determines the response of benthic ammonia-oxidizing microorganisms to ocean acidification

PubMed Central

Laverock, B.; Kitidis, V.; Tait, K.; Gilbert, J. A.; Osborn, A. M.; Widdicombe, S.

2013-01-01

Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH ≤ 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79–97%; p < 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms. PMID:23980243

Impacts of environmental and anthropogenic stresses on macrozoobenthic communities in Jinhae Bay, Korea.

PubMed

Bae, Hanna; Lee, Jung-Ho; Song, Sung Joon; Park, Jinsoon; Kwon, Bong-Oh; Hong, Seongjin; Ryu, Jongseong; Choi, Kyungsik; Khim, Jong Seong

2017-03-01

In this study, spatiotemporal dynamics of macrofaunal assemblages and their associations with environmental conditions were examined in Jinhae Bay (10 sites), where the obvious sources of pollution including industries, oyster farms (hanging cultures), and municipal discharges has surrounded. The survey had performed over five consecutive seasons in 2013-2014. Target sedimentary variables included grain size, organic content, C/N ratio, carbon and nitrogen stable isotope ratios, and some heavy metals. Five ecological quality indices (EcoQ) were calculated from the benthic community data to evaluate ecological qualities in site-specific manner. Jinhae Bay is a shallow (depths range, 11-24 m) and typical semi-enclosed bay. The benthic environments represented mud dominated bottoms (>70%) with fairly substantial organic content levels (>2%) over all five seasons. Seasonal patterns were observed with peak abundances in the spring and distinctive macrozoobenthos species shifts in the summer. The spring bloom could be explained by drastic increases of some polychaetes, mainly Capitella sp., at certain site, particularly near the shore. The oyster farms situated in the innermost locations seem to provide organic-rich bottoms being dominated by opportunistic species and/or organic pollution indicator species, such as Lumbrineris longifolia, Capitella sp., and Paraprionospio patiens. In general, the EcoQ indicators indicated that Jinhae Bay was moderately polluted, with exceptionally poor EcoQ in a few locations during the specific season(s). Overall, adverse effects on benthic community was broadly attributable to contaminations of heavy metals and nearby aquatic farm activities in Jinhae Bay, which requires a prompt action toward ecosystem-based management practice in the given area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Constancy despite variability: Local and regional macrofaunal diversity in intertidal seagrass beds

NASA Astrophysics Data System (ADS)

Boyé, Aurélien; Legendre, Pierre; Grall, Jacques; Gauthier, Olivier

2017-12-01

The importance of seagrass habitat for the diversity of benthic fauna has been extensively studied worldwide. Most of the information available is, however, about α diversity while little consideration has been given to β diversity. To fill the knowledge gaps regarding the variability of epifaunal and infaunal seagrass assemblages at large spatial and temporal scales, we scrutinized an extensive dataset covering five years of monitoring of eight intertidal Zostera marina meadows around Brittany (France). High species richness arose at the regional scale from the combination of high local diversity of the meadows and substantial among-meadows β diversity. Epifauna and infauna appeared as distinct self-communities as they displayed different spatial and temporal patterns and varied in their responses to local hydrological conditions. Infauna had higher total β diversity than epifauna due to a tighter link to the great variability of local environmental conditions in the region. Both exhibited substantial variations in species composition and community structure with variations of dominant species that were accompanied by extensive change in numerous rare species. The dominant epifaunal species were all grazers. Changes in species composition were induced mostly by species replacement and rarely by richness differences between meadows. Indeed, species richness remained within a narrow range for all seagrass beds, suggesting a potential carrying capacity for species richness of the meadows. Overall, all meadows contributed equally to the regional turnover of seagrass macrofauna, emphasizing high variability and complementarity among beds at the regional scale. The implications of this substantial within-seagrass variability for the functioning of benthic ecosystems at broad scale and for conservation purposes in habitat mosaics warrant further investigations but our results clearly advocate taking into account within-habitat variation when evaluating the diversity of benthic habitats and the potential effect of habitat loss.

Environmental factors affecting benthic macrofauna along a gradient of intermediate sandy beaches in northern Spain

NASA Astrophysics Data System (ADS)

Rodil, I. F.; Lastra, M.

2004-09-01

Ten sandy beaches along the north coast of Spain were studied during September 1999 to analyse the number of species, abundance and biomass of macroinfauna along a gradient of intermediate beach types and exposure range. Faunal samples were collected with metallic cylinders (25 cm diameter, 15 cm depth) at 10 equally spaced shore levels along six replicated transects separated randomly and extending from above the drift line to the low tide swash zone. Exposure rate, Dean's parameter ( Ω), beach state index (BSI) and relative tidal range (RTR) were estimated at each beach. Length and width of the beach, intertidal slope, sorting and median grain size and also swash amplitude and wave characteristics were measured. The number of species was between 10 and 29. Macrofaunal abundances ranged between 4962 and 71,228 ind. linear m -1 and between 31 and 329 ind. m -2, while biomass (ash free dry weight) ranged between 0.027 and 0.278 g m -2 and between 3 and 61 g linear m -1. The results show some significant trends: the number of species is the biotic variable most affected by physical and morphodynamic factors, increasing linearly with relative tidal range and decreasing with increasing average grain size. The same trend was observed from exposed to very exposed beaches and the biomass decreased exponentially with increasing average grain size. These trends agree with previous studies in different coasts in the world where coarse sands limit the benthic macrofauna. The morphodynamic parameters as Dean's parameter or Beach State Index did not show a predictive value. The results suggest that different characteristics of benthic macrofauna communities in intermediate beaches can be affected in different ways by the physical processes involved in beach morphodynamics.

Size Variation and Recruitment of Macoma sp. in the Southern Chukchi Sea and Possible Implications of Seasonal Ocean Acidification in the Pacific Arctic

NASA Astrophysics Data System (ADS)

Goethel, C.; Grebmeier, J. M.; Cooper, L. W.

2016-02-01

Recent sea ice retreat and seawater warming in the Pacific Arctic are physical changes that can have direct impacts on benthic macrofaunal community composition and biomass. We used recent van Veen grab collections of the tellinid bivalves Macoma calcarea and M. moesta in July 2014 (n=84) and 2015 (n= 284), as well as historical length/weight data from the past twenty years, to follow changes in both size and recruitment of this genus at a highly productive station north of Bering Strait (UTN2; 67.05 N, 168.73 W). These bivalves are common benthic prey items for migrating walrus, bearded seals and diving seaducks, and this location is known to be a productive and biologically significant foraging hotspot. Since size and availability of prey items can affect the success of feeding bouts by benthivores, following the recruitment and size distributions of the benthic food base allows for a better understanding of potential feeding behaviors and shifts in response to biological changes. Clam lengths in 2014 ranged from 14 mm to 55 mm, with an average length of 25.8 mm, and clam lengths in 2015 ranged from 15 mm to 50 mm, with an average size of 21.3 mm. New recruitment is surmised based upon size trend changes within the 20-year data set. In addition, ongoing seasonal ocean acidification may be affecting shell growth and respiration rates, based upon results from on-going laboratory experiments using these Macoma sp.clams. This additional influence has the potential for altering size classes and faunal composition available to the foraging benthivores.

Effect of recreational diving on Patagonian rocky reefs.

PubMed

Bravo, Gonzalo; Márquez, Federico; Marzinelli, Ezequiel M; Mendez, María M; Bigatti, Gregorio

2015-03-01

Tourism has grown considerably in the last decades, promoting activities such as recreational SCUBA diving that may affect marine benthic communities. In Puerto Madryn, Patagonia Argentina, sub-aquatic tourism areas (STA) receive about 7,000 divers per year. Diving is concentrated on a few small rocky reefs and 50% of the dives occur in summer. In this work, we evaluated the effect of recreational diving activities on benthic communities and determined whether diving causes a press (long-term) or a pulse (short-term) response. We quantified the percentage cover of benthic organisms and compared benthic assemblage structure and composition between two sites with contrasting usage by divers, 'highly disturbed' and 'moderately disturbed' sites, and two 'control' sites with similar physical characteristics but no diving activity, twice before and after the diving peak in summer. We found differences in benthic assemblage structure (identity and relative abundance of taxa) and composition (identity only) among diving sites and controls. These differences were consistent before and after the peak of diving in summer, suggesting that recreational diving may produce a press impact on overall benthic assemblage structure and composition in these STA. At the moderately disturbed site, however, covers of specific taxa, such as some key habitat-forming or highly abundant species, usually differed from those in controls only immediately after summer, after which they begun to resemble controls, suggesting a pulse impact. Thus, STA in Golfo Nuevo seem to respond differently to disturbances of diving depending on the usage of the sites. This information is necessary to develop sound management strategies in order to preserve local biodiversity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Macrobenthic diversity and sediment-water exchanges of oxygen and ammonium: Example of two subtidal communities of the eastern English Channel

NASA Astrophysics Data System (ADS)

Tous Rius, Armonie; Denis, Lionel; Dauvin, Jean-Claude; Spilmont, Nicolas

2018-06-01

In organic-rich shallow habitats, benthic macrofauna is known to play a major role in the geochemical functioning of surficial sediments through its metabolism, as well as its bioirrigation and/or bioturbation activity. In this paper, the effects of benthic macrofauna on metabolic fluxes at the sediment-water interface were studied at four dates, from winter to late summer, on two major macrobenthic communities of the eastern English Channel (macrotidal system): the fine sand Abra alba community (2 stations) and the sandy gravel Ophiothrix fragilis community (1 station). Oxygen and ammonium fluxes showed temporal changes that could be attributed to the variation of sea water temperature. Once the effect of temperature removed (using Q10 = 2.5), the average fauna mediated fluxes (FFauna) represented respectively 77% and 76% of average total fluxes. Considering the whole dataset, species number and biomass showed a significant correlation with fauna mediated fluxes of O2 and NH4+, while the relationships with abundance were not significant. The species composition of the community might influence ecosystem functioning, but in the present study, functional groups have a very poor relationship with FFauna (O2) and FFauna (NH4+). Despite the presence of engineer species, establishing general and simple rules to link macrofaunal parameters to functional attributes remains very difficult, suggesting that communities rather followed the idiosyncrasy and rivet hypothesis.

Effect of long-term mechanical perturbation on intertidal soft-bottom meiofaunal community spatial structure

NASA Astrophysics Data System (ADS)

Boldina, Inna; Beninger, Peter G.; Le Coz, Maïwen

2014-01-01

Situated at the interface of the microbial and macrofaunal compartments, soft-bottom meiofauna accomplish important ecological functions. However, little is known of their spatial distribution in the benthic environment. To assess the effects of long-term mechanical disturbance on soft-bottom meiofaunal spatial distribution, we compared a site subjected to long-term clam digging to a nearby site untouched by such activities, in Bourgneuf Bay, on the Atlantic coast of France. Six patterned replicate samples were taken at 3, 6, 9, 12, 15, 18, 21 and 24 cm lags, all sampling stations being separated by 5 m. A combined correlogram-variogram approach was used to enhance interpretation of the meiofaunal spatial distribution; in particular, the definition of autocorrelation strength and its statistical significance, as well as the detailed characteristics of the periodic spatial structure of nematode assemblages, and the determination of the maximum distance of their spatial autocorrelation. At both sites, nematodes and copepods clearly exhibited aggregated spatial structure at the meso scale; this structure was attenuated at the impacted site. The nematode spatial distribution showed periodicity at the non-impacted site, but not at the impacted site. This is the first explicit report of a periodic process in meiofaunal spatial distribution. No such cyclic spatial process was observed for the more motile copepods at either site. This first study to indicate the impacts of long-term anthropogenic mechanical perturbation on meiofaunal spatial structure opens the door to a new dimension of mudflat ecology. Since macrofaunal predator search behaviour is known to be strongly influenced by prey spatial structure, the alteration of this structure may have important consequences for ecosystem functioning.

Macrobenthic Biomass Relations in the Faroe-Shetland Channel: An Arctic-Atlantic Boundary Environment

PubMed Central

Narayanaswamy, Bhavani E.; Bett, Brian J.

2011-01-01

The Faroe-Shetland Channel, located in the NE Atlantic, ranges in depth from 0–1700 m and is an unusual deep-sea environment because of its complex and dynamic hydrographic regime, as well as having numerous different seafloor habitats. Macrofaunal samples have been collected on a 0.5 mm mesh sieve from over 300 stations in a wide area survey and on nested 0.5 and 0.25 mm mesh sieves along a specific depth transect. Contrary to general expectation, macrofauanl biomass in the Channel did not decline with increasing depth. When examined at phylum level, two main biomass patterns with depth were apparent: (a) polychaetes showed little change in biomass on the upper slope then increased markedly below 500 m to a depth of 1100 m before declining; and (b) other phyla showed enhanced biomass between 300–500 m. The polychaete response may be linked with a seafloor environment change to relatively quiescent hydrodynamic conditions and an increasing sediment mud content that occurs at c. 500 m. In contrast, the mid-slope enhancement of other phyla biomass may reflect the hydrodynamically active interface between the warm and cold water masses present in the Channel at c. 300–500 m. Again contrary to expectation, mean macrofaunal body size did not decline with depth, and the relative contribution of smaller (>0.25 mm<0.5 mm) to total (>0.25 mm) macrobenthos did not increase with depth. Overall our total biomass and average individual biomass estimates appear to be greater than those predicted from global analyses. It is clear that global models of benthic biomass distribution may mask significant variations at the local and regional scale. PMID:21526171

Effects of sub-seabed CO2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages.

PubMed

Amaro, T; Bertocci, I; Queiros, A M; Rastelli, E; Borgersen, G; Brkljacic, M; Nunes, J; Sorensen, K; Danovaro, R; Widdicombe, S

2018-03-01

The continued rise in atmospheric carbon dioxide (CO 2 ) levels is driving climate change and temperature shifts at a global scale. CO 2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO 2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO 2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO 2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO 2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO 2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO 2 ), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO 2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO 2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies. Copyright © 2018. Published by Elsevier Ltd.

Large Spatial Scale Variability in Bathyal Macrobenthos Abundance, Biomass, α- and β-Diversity along the Mediterranean Continental Margin

PubMed Central

Baldrighi, Elisa; Lavaleye, Marc; Aliani, Stefano; Conversi, Alessandra; Manini, Elena

2014-01-01

The large-scale deep-sea biodiversity distribution of the benthic fauna was explored in the Mediterranean Sea, which can be seen as a miniature model of the oceans of the world. Within the framework of the BIOFUN project (“Biodiversity and Ecosystem Functioning in Contrasting Southern European Deep-sea Environments: from viruses to megafauna”), we investigated the large spatial scale variability (over >1,000 km) of the bathyal macrofauna communities that inhabit the Mediterranean basin, and their relationships with the environmental variables. The macrofauna abundance, biomass, community structure and functional diversity were analysed and the α-diversity and β-diversity were estimated across six selected slope areas at different longitudes and along three main depths. The macrobenthic standing stock and α-diversity were lower in the deep-sea sediments of the eastern Mediterranean basin, compared to the western and central basins. The macrofaunal standing stock and diversity decreased significantly from the upper bathyal to the lower bathyal slope stations. The major changes in the community composition of the higher taxa and in the trophic (functional) structure occurred at different longitudes, rather than at increasing water depth. For the β-diversity, very high dissimilarities emerged at all levels: (i) between basins; (ii) between slopes within the same basin; and (iii) between stations at different depths; this therefore demonstrates the high macrofaunal diversity of the Mediterranean basins at large spatial scales. Overall, the food sources (i.e., quantity and quality) that characterised the west, central and eastern Mediterranean basins, as well as sediment grain size, appear to influence the macrobenthic standing stock and the biodiversity along the different slope areas. PMID:25225909

Large spatial scale variability in bathyal macrobenthos abundance, biomass, α- and β-diversity along the Mediterranean continental margin.

PubMed

Baldrighi, Elisa; Lavaleye, Marc; Aliani, Stefano; Conversi, Alessandra; Manini, Elena

2014-01-01

The large-scale deep-sea biodiversity distribution of the benthic fauna was explored in the Mediterranean Sea, which can be seen as a miniature model of the oceans of the world. Within the framework of the BIOFUN project ("Biodiversity and Ecosystem Functioning in Contrasting Southern European Deep-sea Environments: from viruses to megafauna"), we investigated the large spatial scale variability (over >1,000 km) of the bathyal macrofauna communities that inhabit the Mediterranean basin, and their relationships with the environmental variables. The macrofauna abundance, biomass, community structure and functional diversity were analysed and the α-diversity and β-diversity were estimated across six selected slope areas at different longitudes and along three main depths. The macrobenthic standing stock and α-diversity were lower in the deep-sea sediments of the eastern Mediterranean basin, compared to the western and central basins. The macrofaunal standing stock and diversity decreased significantly from the upper bathyal to the lower bathyal slope stations. The major changes in the community composition of the higher taxa and in the trophic (functional) structure occurred at different longitudes, rather than at increasing water depth. For the β-diversity, very high dissimilarities emerged at all levels: (i) between basins; (ii) between slopes within the same basin; and (iii) between stations at different depths; this therefore demonstrates the high macrofaunal diversity of the Mediterranean basins at large spatial scales. Overall, the food sources (i.e., quantity and quality) that characterised the west, central and eastern Mediterranean basins, as well as sediment grain size, appear to influence the macrobenthic standing stock and the biodiversity along the different slope areas.

Benthic marine litter in four Gulfs in Greece, Eastern Mediterranean; abundance, composition and source identification

NASA Astrophysics Data System (ADS)

Koutsodendris, Andreas; Papatheodorou, George; Kougiourouki, Ourania; Georgiadis, Michalis

2008-04-01

The types, abundance, distribution and sources of benthic marine litter found in four Greek Gulfs (Patras, Corinth, Echinades and Lakonikos) were studied using bottom trawl nets. Mean distribution and weight densities range between 72-437 Item/km 2 and 6.7-47.4 kg/km 2. Litter items were sorted into material and usage categories. Plastic litter (56%) is the most dominant material category followed by metal (17%) and glass (11%). Beverage packaging (32%) is the dominant usage category followed by general packaging (28%) and food packaging (21%). Based on the typological results three dominant litter sources were identified; land-based, vessel-based and fishery-based. Application of factor analysis (R- and Q-mode) conducted on both material and usage litter datasets confirmed the existence of the three dominant litter sources. Q-mode analysis further resulted in the quantification of the litter sources; land-based ones provided the majority (69%) of the total litter items followed by vessel-based (26%) and fishery-based (5%) sources. Diverse environmental parameters influence significantly these amounts among the four Gulfs.

Dysaerobic trace fossils and ichnofabrics in the upper Jurassic Kimmeridge Clay of southern England

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wignall, P.B.

The trace fossil suite from the Kimmeridge Clay is calibrated against an oxygen gradient derived from previous geochemical, lithological and shelly macrofaunal studies. Several soft-bodied trace markers appear to have tolerated lower oxygen tensions than even the hardiest shelly benthic macrofauna-a common occurrence in both recent and ancient dysaerobic settings. Lowest diversity trace fossil assemblages consist of Astacimorphichnus etchesi (new ichnotaxon), a small endostratal pascichnial trace attributed to pioneering polychaete populations. Ekdale and Masons' (1988) contention that fodinichnia dominate the lowest diversity and lowest oxygen settings is not substantiated as the only example of this feeding strategy, Rhizocorallium irregulare, ismore » encountered in moderately diverse trace fossil assemblages associated with a low diversity shelly macrofauna. Upper dysaerobic conditions are characterized by the development of a surface mixed layer and the consequent destruction of fine lamination. Tiering is only developed under normal oxygen conditions with Chondrites as the deepest trace. In contrast to many previous studies, Chondrites is never found in dysaerobic facies.« less

The structure of soft-bottom benthic communities in the vicinity of the Texas Flower Garden Banks, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Yingst, Josephine Y.; Rhoads, Donald C.

1985-05-01

Biological and sedimentological samples were obtained in June 1980 from box cores taken in 100-200 m of water on sandy-mud sediments near the East and West Flower Garden Bank reefs, on the Texas-Louisiana Continental Shelf. The objective was to obtain baseline information about sedimentary parameters and organisms adjacent to the FGB environments in order to allow inferences to be made about potential effects of physical disturbance of the seafloor on the resident benthos. Most infaunal organisms are found in the upper 3-5 cm of the bottom. Permanent meiofauna dominate in both numbers and biomass. X-radiographs of sediment fabrics show all stations to be reworked by head-down deposit-feeders or errant bioturbators. Taxa responsible for this bioturbation were not quantitatively sampled. Macrofaunal densities range from 3000 to 25000 m -2 and total meiofauna from 221 to 892 × (10 cm) -2. Nematodes dominate followed in equal abundance by foraminiferans, polychaetes, and copepods. Seventy-five percent of the total sediment ATP in the top 3 cm is contributed by meiofauna. These benthic assemblages are hypothesized to represent a mixture of pioneering and high-order successional stages. Bacterial abundances are positively correlated with organic content and inversely correlated with macro- and meiofaunal densities. This inverse relationship may reflect consumer cropping intensities. Both microbial ATP and bacterial biomass are lower than reported for the Georgia Bight Shelf, Cape Blanc, West African Shelf, western coast of Norway, and Long Island Sound. Bacterial counts are lower than those recorded for the East China Sea and the Amazon River shelf. Moderate to low standing stocks of benthos, dominated by meiofaunal-sized taxa, further suggest that this area of the Gulf of Mexico is a relatively oligotrophic system for infaunal benthic consumers. Higher order successional stages are, in general, adversely affected to a greater extent than pioneering stages by physical disturbance. In the Texas-Louisiana shelf region, dilution of an already food limited system by inert barium sulphate would be expected to result in even lower standing stocks of benthic infaunal invertebrates.

Interlinking backscatter, grain size and benthic community structure

NASA Astrophysics Data System (ADS)

McGonigle, Chris; Collier, Jenny S.

2014-06-01

The relationship between acoustic backscatter, sediment grain size and benthic community structure is examined using three different quantitative methods, covering image- and angular response-based approaches. Multibeam time-series backscatter (300 kHz) data acquired in 2008 off the coast of East Anglia (UK) are compared with grain size properties, macrofaunal abundance and biomass from 130 Hamon and 16 Clamshell grab samples. Three predictive methods are used: 1) image-based (mean backscatter intensity); 2) angular response-based (predicted mean grain size), and 3) image-based (1st principal component and classification) from Quester Tangent Corporation Multiview software. Relationships between grain size and backscatter are explored using linear regression. Differences in grain size and benthic community structure between acoustically defined groups are examined using ANOVA and PERMANOVA+. Results for the Hamon grab stations indicate significant correlations between measured mean grain size and mean backscatter intensity, angular response predicted mean grain size, and 1st principal component of QTC analysis (all p < 0.001). Results for the Clamshell grab for two of the methods have stronger positive correlations; mean backscatter intensity (r2 = 0.619; p < 0.001) and angular response predicted mean grain size (r2 = 0.692; p < 0.001). ANOVA reveals significant differences in mean grain size (Hamon) within acoustic groups for all methods: mean backscatter (p < 0.001), angular response predicted grain size (p < 0.001), and QTC class (p = 0.009). Mean grain size (Clamshell) shows a significant difference between groups for mean backscatter (p = 0.001); other methods were not significant. PERMANOVA for the Hamon abundance shows benthic community structure was significantly different between acoustic groups for all methods (p ≤ 0.001). Overall these results show considerable promise in that more than 60% of the variance in the mean grain size of the Clamshell grab samples can be explained by mean backscatter or acoustically-predicted grain size. These results show that there is significant predictive capacity for sediment characteristics from multibeam backscatter and that these acoustic classifications can have ecological validity.

Benthic macroinfaunal community structure, resource utilisation and trophic relationships in two Canadian Arctic Archipelago polynyas

PubMed Central

Witte, Ursula; Archambault, Philippe

2017-01-01

Climate change driven alterations to patterns of Arctic marine primary production, with increasing phytoplankton- and decreasing ice algal production, have the potential to change the resource utilisation and trophic structure of the benthic communities relying on the algae for food. To predict the benthic responses to dietary changes, we studied the macroinfaunal community compositions, and used the faunal δ13C and δ15N signatures to investigate their main food sources and trophic positions in North Water (NOW) and Lancaster Sound (LS) polynyas in the Canadian Arctic Archipelago. Macroinfaunal density (10 952 ind. m-2) and biomass (3190 mg C m-2) recorded in NOW were higher than previously found in the Arctic at depths >500m, and significantly higher than in LS (8355 ind. m-2 and 2110 mg C m-2). This was attributed to higher particulate organic matter fluxes to seafloor in NOW. Polychaetes were significant taxa at both sites in terms of density and biomass, and in addition crustacean density in NOW and bivalve density in LS were high. Facultative filter and surface deposit feeders were highly prevalent at both sites, suggesting feeding plasticity is a successful strategy for accessing different food sources. The macrofaunal δ13C signatures reflected the signatures of pelagic particulate organic matter at the sites, and an isotope mixing model confirmed phytoplankton as the main food source for most taxa and feeding guilds. The food web length in LS was longer than in NOW (3.2 vs. 2.8 trophic levels). This was attributed to a larger reliance on reworked organic matter by the benthic community in LS, whereas the high export fluxes at the highly productive NOW resulted in higher rates of selective consumption of fresh algal matter. Despite studies suggesting that loss of ice algae from consumer diets in the Arctic might have a negative impact on the benthos, this study suggests that Arctic macrobenthic communities thrive using phytoplankton as their main food source and should thus be able to cope or even benefit from predicted changes to patterns of primary production. PMID:28850574

Microfossils, a Key to Unravel Cold-Water Carbonate Mound Evolution through Time: Evidence from the Eastern Alboran Sea

PubMed Central

Stalder, Claudio; Vertino, Agostina; Rosso, Antonietta; Rüggeberg, Andres; Pirkenseer, Claudius; Spangenberg, Jorge E.; Spezzaferri, Silvia; Camozzi, Osvaldo; Rappo, Sacha; Hajdas, Irka

2015-01-01

Cold-water coral (CWC) ecosystems occur worldwide and play a major role in the ocean's carbonate budget and atmospheric CO2 balance since the Danian (~65 m.y. ago). However their temporal and spatial evolution against climatic and oceanographic variability is still unclear. For the first time, we combine the main macrofaunal components of a sediment core from a CWC mound of the Melilla Mounds Field in the Eastern Alboran Sea with the associated microfauna and we highlight the importance of foraminifera and ostracods as indicators of CWC mound evolution in the paleorecord. Abundances of macrofauna along the core reveal alternating periods dominated by distinct CWC taxa (mostly Lophelia pertusa, Madrepora oculata) that correspond to major shifts in foraminiferal and ostracod assemblages. The period dominated by M. oculata coincides with a period characterized by increased export of refractory organic matter to the seafloor and rather unstable oceanographic conditions at the benthic boundary layer with periodically decreased water energy and oxygenation, variable bottom water temperature/density and increased sediment flow. The microfaunal and geochemical data strongly suggest that M. oculata and in particular Dendrophylliidae show a higher tolerance to environmental changes than L. pertusa. Finally, we show evidence for sustained CWC growth during the Alleröd-Younger-Dryas in the Eastern Alboran Sea and that this period corresponds to stable benthic conditions with cold/dense and well oxygenated bottom waters, high fluxes of labile organic matter and relatively strong bottom currents PMID:26447699

Environmental impact of bleufin tuna aquaculture on benthic assemblages in the western coast of Baja California, Mexico

NASA Astrophysics Data System (ADS)

Diaz-Castaneda, V.

2013-05-01

Sea-cage farming results in a constant rain of organic waste onto the surrounding benthos. In Baja California there is growing concern over the effects of sea-cages on the local environment: sediment chemistry and benthic communities. Samples were taken in 18 stations using a Van veen grab (0.1 m2) in Bahía Salsipuedes, Baja California in 2003, 2004, 2006 and 2008. Organisms belonging to 7 Phyla were collected: Polychaeta, Mollusca, Crustacea, Echinodermata, Cnidaria, Sipuncula and Bryozoa. Polychaetes were the dominant group followed by crustaceans and mollusks. Polychaetes were represented by 37 families and 157 species. Best represented families were Paraonidae, Cirratulidae, Spionidae, Glyceridae and Maldanidae. This study shows that in the NW area of the bay organic carbon (2.54%) and organic nitrogen (0.95%) are being accumulated (higher concentrations and lower Eh values) and smaller opportunistic species are increasing rapidly near the tuna pens. It is crucial to maintain "healthy" macrofaunal populations in order to enhance decomposition of organic matter and to prevent its excessive accumulation. The most abundant polychaete species were Aphelochaeta multifinis, Mediomastus ambiseta, Prionospio steenstrupi Spiophanes bombyx, Apoprionospio pygnaea, Paraonella sp, Monticellina sp, Aricidea (Allia) ramosa, Spiophanes bombyx and Levinsenia gracilis. The dominant trophic groups were deposit-feeders and carnivores. The buildup of organic matter on the seafloor has attracted scavenger species particularly peracarid crustaceans. Non-metric multidimensional scaling (MDS) separated stations depending of the distance to the tuna pens.

[Characteristics of soil macrofaunal community structure in secondary forest and forest plantations in western Qinling Mountains of Northwest China].

PubMed

Liu, Ji-Liang; Cao, Jing; Li, Shi-Jie; Pan, Chun-Lin; Pan, Cheng-Chen

2012-09-01

Long-term disturbance of human beings on secondary forest ecosystem would have profound impacts on belowground ecological processes, whereas the community structure and functional diversity of soil fauna would be sensitive to the changes of belowground ecological processes, with significance as an indicator of the changes. In this study, the method of hand-sorting was adopted to investigate the density of soil macrofaunal community in a secondary forest and the Pinus tabulaeformis, Larix kaempferi, Picea abie, and Picea asperata plantations of nearly 30 years old in Xiaolongshan forest area of western Qinling Mountains, and the PCA ordination and one-way ANOVA analysis were applied to analyze the community structure and trophic group composition of soil macrofauna in the five forest types. In the P. tabulaeformis and L. kaempferi plantations, the density of soil macrofaunal community was 3.0 and 2.1 times of that in the secondary forest, respectively, and the consumers/decomposers ratio of the community was obviously higher than that in the secondary forest. Among the plantations, P. tabulaeformis and L. kaempferi plantations had a significantly higher consumers/decomposers ratio of soil macrofaunal community than P. abies and P. asperata plantations. There was an obvious difference in community structure of soil macrofauna among the four plantations. The density of soil macrofaunal community in P. tabulaeformis and L. kaempferi plantations was 3.5 and 2.1 times higher than that in P. asperata plantation, respectively, whereas the group richness of soil macrofaunal community in P. tabulaeformis plantation was 1.5 times of that in P. abies and P. asperata plantations.

Quantitative distribution and functional groups of intertidal macrofaunal assemblages in Fildes Peninsula, King George Island, South Shetland Islands, Southern Ocean.

PubMed

Liu, Xiaoshou; Wang, Lu; Li, Shuai; Huo, Yuanzi; He, Peimin; Zhang, Zhinan

2015-10-15

To evaluate spatial distribution pattern of intertidal macrofauna, quantitative investigation was performed in January to February, 2013 around Fildes Peninsula, King George Island, South Shetland Islands. A total of 34 species were identified, which were dominated by Mollusca, Annelida and Arthropoda. CLUSTER analysis showed that macrofaunal assemblages at sand-bottom sites belonged to one group, which was dominated by Lumbricillus sp. and Kidderia subquadrata. Macrofaunal assemblages at gravel-bottom sites were divided into three groups while Nacella concinna was the dominant species at most sites. The highest values of biomass and Shannon-Wiener diversity index were found in gravel sediment and the highest value of abundance was in sand sediment of eastern coast. In terms of functional group, detritivorous and planktophagous groups had the highest values of abundance and biomass, respectively. Correlation analysis showed that macrofaunal abundance and biomass had significant positive correlations with contents of sediment chlorophyll a, phaeophorbide and organic matter. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of environmental conditions on variation in the sediment-water interface created by complex macrofaunal burrows on a tidal flat

NASA Astrophysics Data System (ADS)

Koo, Bon Joo; Kwon, Kae Kyoung; Hyun, Jung-Ho

2007-11-01

We quantified the increase in the sediment-water interface created by the burrowing activities of the resident macrofaunal community and its variation with respect to the physical conditions of the habitat on a tidal fat. We investigated environmental factors and dimensions of macrofaunal burrows with respect to tidal height and vegetation during spring and summer at three sites. A resin-casting method was used to quantify the dimensions of all burrows at each site. The dimensions of macrofaunal burrows varied both temporally and spatially and the increase in the sediment-water interface reached a maximum of 311%, ranging from 20 to 255% under different habitat conditions. The sediment-water interface depended on the duration of exposure resulting from tidal height, increased temperatures resulting from seasonality, and marsh plant density. Burrows were deeper and more expansive at both higher tidal levels and higher temperatures in summer. Burrow dimensions were sharply reduced with the disappearance of adult macrofauna in areas where the roots of the marsh plant Suaeda japonica were dense. The significance of this study lies in quantifying the burrow dimensions of the entire macrofaunal community, rather than just a single population, and confirming their spatial and temporal variation with respect to physical conditions of the habitat. Environmental factors responsible for variation in burrow dimensions are discussed.

Macrofaunal community structure in Bahía Concepción (Chile) before and after the 8.8 Mw Maule mega-earthquake and tsunami.

PubMed

Cárcamo, Paula J; Hernández-Miranda, Eduardo; Veas, Rodrigo; Quiñones, Renato A

2017-09-01

Faunal assemblages of subtidal sedimentary environments are key components of coastal ecosystems. Benthic communities inhabiting the coastal zone near urban centers in Concepción Bay (Chile) have been described as highly disturbed (i.e. impoverished in diversity and species richness). This is due to the frequent presence of hypoxic conditions at the bottom due to the intrusion of low oxygen Equatorial Subsurface Water, high natural productivity and the high load of organic matter generated by several anthropogenic activities. A mega-earthquake (8.8 Mw) and subsequent tsunami occurred on the coast of south-central Chile on February 27, 2010 (27F), heavily impacting Concepción Bay, which is located 30 km south of the epicenter. The objectives of the present study are: (i) to evaluate the effect produced by the mega-earthquake and tsunami on the benthic community, and (ii) to assess dissimilarity in macrofauna composition and abundance in Concepción Bay at an inter-decadal time scale based on a comparison between our sampling conducted between 2010 and 2013 and information published since 1969. Our results show that the benthic macrofauna of Concepción Bay was disturbed by the 27F (i.e. high community dissimilarity in 2010). Changes in community structure were observed at an inter-annual scale (i.e. diminished community dissimilarity in 2013), suggesting a recovery post-27F. At an inter-decadal scale, community structure post-27F was dissimilar to the structure described for the 1980's and 1990's but more similar to that reported for 1969. The reducing conditions of the sediments due to the high input of organic matter that took place in the 1980's and 1990's may explain this dissimilarity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes in Benthos Associated with Mussel (Mytilus edulis L.) Farms on the West-Coast of Scotland

PubMed Central

Wilding, Thomas A.; Nickell, Thomas D.

2013-01-01

Aquaculture, as a means of food production, is growing rapidly in response to an increasing demand for protein and the over-exploitation of wild fisheries. This expansion includes mussels (family Mytilidae) where production currently stands at 1.5 million tonnes per annum. Mussel culture is frequently perceived as having little environmental impact yet mussel biodeposits and shell debris accumulate around the production site and are linked to changes in the benthos. To assess the extent and nature of changes in benthos associated with mussel farming grab and video sampling around seven mussel farms was conducted. Grab samples were analysed for macrofauna and shell-hash content whilst starfish were counted and the shell-hash cover estimated from video imaging. Shell-hash was patchily distributed and occasionally dominated sediments (maximum of 2116 g per 0.1 m2 grab). Mean shell-hash content decreased rapidly at distances >5 m from the line and, over the distance 1–64 m, decreased by three orders of magnitude. The presence of shell-hash and the distance-from-line influenced macrofaunal assemblages but this effect differed between sites. There was no evidence that mussel farming was associated with changes in macrobenthic diversity, species count or feeding strategy. However, total macrofaunal count was estimated to be 2.5 times higher in close proximity to the lines, compared with 64 m distance, and there was evidence that this effect was conditional on the presence of shell-hash. Starfish density varied considerably between sites but, overall, they were approximately 10 times as abundant close to the mussel-lines compared with 64 m distance. There was no evidence that starfish were more abundant in the presence of shell-hash visible on the sediment surface. In terms of farm-scale benthic impacts these data suggest that mussel farming is a relatively benign way of producing food, compared with intensive fish-farming, in similar environments. PMID:23874583

Impacts of trawling on benthic macro-fauna and -flora of the Spencer Gulf prawn fishing grounds

NASA Astrophysics Data System (ADS)

Svane, Ib; Hammett, Zoe; Lauer, Peter

2009-05-01

The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (˜10,000 m 2) and underwater stereophotography (˜4.5 m 2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994-1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus degeni, and the Melbourne silver belly, Parequula melbournensis). Simpson's Index of Diversity (1 - λ) and species richness in the beam trawl samples were fairly even across all sites, but a significant effect of site was found in the stereophotographic transect samples. It was concluded that prawn trawling has a strong influence on the structure of the benthic habitats of the Spencer Gulf prawn fishing grounds highlighted by the magnitude of change and the strength of the gradient of effects. Confounding factors linked to the biophysical attributes of the sites are believed to be minor.

A cross-taxa study using environmental DNA/RNA metabarcoding to measure biological impacts of offshore oil and gas drilling and production operations.

PubMed

Laroche, Olivier; Wood, Susanna A; Tremblay, Louis A; Ellis, Joanne I; Lear, Gavin; Pochon, Xavier

2018-02-01

Standardized ecosystem-based monitoring surveys are critical for providing information on marine ecosystem health. Environmental DNA/RNA (eDNA/eRNA) metabarcoding may facilitate such surveys by quickly and effectively characterizing multi-trophic levels. In this study, we assessed the suitability of eDNA/eRNA metabarcoding to evaluate changes in benthic assemblages of bacteria, Foraminifera and other eukaryotes along transects at three offshore oil and gas (O&G) drilling and production sites, and compared these to morphologically characterized macro-faunal assemblages. Bacterial communities were the most responsive to O&G activities, followed by Foraminifera, and macro-fauna (the latter assessed by morphology). The molecular approach enabled detection of hydrocarbon degrading taxa such as the bacteria Alcanivorax and Microbulbifer at petroleum impacted stations. Most identified indicator taxa, notably among macro-fauna, were highly specific to site conditions. Based on our results we suggest that eDNA/eRNA metabarcoding can be used as a stand-alone method for biodiversity assessment or as a complement to morphology-based monitoring approaches. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of temperature on biogeochemistry of marine organic-enriched systems: implications in a global warming scenario.

PubMed

Sanz-Lázaro, Carlos; Valdemarsen, Thomas; Marín, Arnaldo; Holmer, Marianne

2011-10-01

Coastal biogeochemical cycles are expected to be affected by global warming. By means of a mesocosm experiment, the effect of increased water temperature on the biogeochemical cycles of coastal sediments affected by organic-matter enrichment was tested, focusing on the carbon, sulfur, and iron cycles. Nereis diversicolor was used as a model species to simulate macrofaunal bioirrigation activity in natural sediments. Although bioirrigation rates of N. diversicolor were not temperature dependent, temperature did have a major effect on the sediment metabolism. Under organic-enrichment conditions, the increase in sediment metabolism was greater than expected and occurred through the enhancement of anaerobic metabolic pathway rates, mainly sulfate reduction. There was a twofold increase in sediment metabolism and the accumulation of reduced sulfur. The increase in the benthic metabolism was maintained by the supply of electron acceptors through bioirrigation and as a result of the availability of iron in the sediment. As long as the sediment buffering capacity toward sulfides is not surpassed, an increase in temperature might promote the recovery of organic-enriched sediments by decreasing the time for mineralization of excess organic matter.

Shading decreases the abundance of the herbivorous California horn snail, Cerithidea californica

USGS Publications Warehouse

Lorda, Julio; Lafferty, Kevin D.

2012-01-01

Most of the intertidal zone in estuaries of California, USA and Baja California, Mexico is covered with vascular vegetation. Shading by these vascular plants influences abiotic and biotic processes that shape benthic community assemblages. We present data on the effects of shading on the California horn snail, Cerithidea californica. This species is important because it is the most common benthic macrofaunal species in these systems and acts as an obligate intermediate host of several species of rematode parasites that infect several other species. Using observational and experimental studies, we found a negative effect of shade on the distribution and abundance of the California horn snail. We hypothesized that shading reduces the abundance of the epipelic diatoms that the snails feeds on, causing snails to leave haded areas. We observed a negative relationship between vascular plant cover, sub-canopy light levels, and snail density in Mugu Lagoon. Then we experimentally manipulated light regimes, by clipping vegetation and adding shade structures, and found higher snail densities at higher light levels. In Goleta Slough, we isolated the effect of shade from vegetation by documenting a negative relationship between the shade created by two bridges and diatom and snail densities. We also found that snails moved the greatest distances over shaded channel banks compared to unshaded channel banks. Further, we documented the effect of water depth and channel bank orientation on shading in this system. An additional effect of shading is the reduction of temperature, providing an alternative explanation for some of our results. These results broaden our knowledge of how variation in the light environment influences the ecology of estuarine ecosystems.

Structure of Infaunal Communities on the Beaufort Sea Shelf and Slope: Insights from Morphological and Environmental DNA Sequencing Approaches

NASA Astrophysics Data System (ADS)

Hardy, S. M.; Bik, H.; Walker, A.; Sharma, J.; Blanchard, A.

2016-02-01

Rapid change is occurring in the Arctic concurrently with increased human activity, yet our knowledge of the structure and function of high-Arctic sediment communities is still rudimentary. The Beaufort Sea is particularly poorly sampled, and largely unexplored at slope depths, providing little information with which to assess the impacts of petroleum exploration activities now beginning in this area. We are investigating diversity and community structure of meio- and macrobenthic infauna on the continental shelf and slope of the Beaufort Sea across a range of depths (50 to 1000 m) using traditional taxonomic and environmental DNA sequencing approaches, and comparing results to additional sites in the adjacent NE Chukchi Sea petroleum lease-sale area. The Beaufort slope is topographically complex and characterized by an east-west gradient in benthic habitat characteristics, with heavy input of terrestrial organic matter particularly in the region of the Mackenzie River delta. Warmer, saltier subsurface Atlantic water masses impact benthic communities at mid-slope depths, likely influencing turnover in community structure observed with depth. Food resources are variable across the region, with very high sediment chlorophyll concentrations at 350 m depth in some areas. Differences in nematode assemblages were detected across the Beaufort Sea shelf/slope, across depths within the Beaufort Sea, and between the Beaufort and adjacent NE Chukchi Sea. These differences were apparent in both morphological and environmental sequencing data. Macrofaunal communities showed variable community structure among transects, with high abundance and high dominance in polychaete assemblages coincident with the chlorophyll maximum. Sequencing data also revealed an abundance of protists in sediments which have been mostly ignored in studies of ecosystem dynamics in this region, and may represent an important component of the food web.

Recent advances in the use of estuarine meiobenthos to assess contaminated sediment effects in multi-species whole sediment microcosms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chandler, G.T.; Coull, B.C.; Schizas, N.V.

1995-12-31

Many marine meiobenthic taxa (i.e. invertebrates passing a 1-mm sieve but retaining on a 0.063 mm sieve) are ideal for ``whole-sediment`` and porewater bioassay of sedimented pollutants. Annual production of meiobenthos is 5--10 times that of the more commonly studied macrobenthos, and > 95% of all meiobenthos live in the oxic zone of muddy sediments at densities of 4--12 million per M{sup 2}. Most spend their entire lifecycles, burrowing freely and feeding on/within the sediment:porewater matrix, many taxa undergo 10--14 generations per year, most larval/juvenile stages are benthic, and many have easily quantifiable reproductive output. Furthermore, many meiobenthic taxa canmore » be cultured indefinitely over multiple life-cycles within simple sediment microcosms consisting of sealed whole-sediment cores collected intact from intertidal mudflats. The authors describe several recent technical developments exploiting meiofaunal sediment culture for rapid contaminated sediment bioassays of toxicant effects on survival, reproduction and population growth of meiobenthic taxa in whole-sediment microcosms. Currently meiobenthic copepods, nematodes, foraminifers and polychaetes are being continuously cultured to study these parameters under exposure to model sediment-associated toxicants (e.g. cadmium). Bioassays are run for 21-d under flowing seawater. With this approach, fertile benthic copepods (e.g. Amphiascus tenuiremis) can be added to core microcosms to assess survival and growth of a fixed population cohort. All other meiobenthic taxa are enumerated relative to controls and evaluated for toxicant effects on higher order community-level endpoints. This approach exploits meiobenthos` high abundance and rapid reproductive rates to yield on a micro scale better endpoints than much larger sediment mesocosms targeted at macrofaunal endpoints.« less

Rapid change with depth in megabenthic structure-forming communities of the Makapu'u deep-sea coral bed

NASA Astrophysics Data System (ADS)

Long, Dustin J.; Baco, Amy R.

2014-01-01

Seamounts are largely unexplored undersea mountains rising abruptly from the ocean floor, which can support an increased abundance and diversity of organisms. Deep-sea corals are important benthic structure-formers on current-swept hard substrates in these habitats. While depth is emerging as a factor structuring the fauna of seamounts on a large spatial scale, most work addressing deep-sea coral and seamount community structure has not considered the role of small-scale variation in species distributions. Video from six ROV dives over a depth range of ~320-530 m were analyzed to assess the diversity and density of benthic megafaunal invertebrates across the Makapu'u deep-sea coral bed, offshore of Oahu, Hawaii. At the same time, the physical environment along the dive track was surveyed to relate biotic patterns with abiotic variables including depth, aspect, rugosity, substrate, slope and relief to test the factors structuring community assemblages. Despite the narrow range examined, depth was found to be the strongest structuring gradient, and six unique macrobenthic communities were found, with a 93% faunal dissimilarity over the depth surveyed. Relief, rugosity and slope were also factors in the final model. Alcyonacean octocorals were the dominant macrofaunal invertebrates at all but the deepest depth zone. The commercially harvested precious coral C. secundum was the dominant species at depths 370-470 m, with a distribution that is on average deeper than similar areas. This may be artificial due to the past harvesting of this species on the shallower portion of its range. Primnoid octocorals were the most abundant octocoral family overall. This work yields new insight on the spatial ecology of seamounts, pointing out that community changes can occur over narrow depth ranges and that communities can be structured by small-scale physiography.

as response to seasonal variability

PubMed

Badano, Ernesto I; Labra, Fabio A; Martínez-Pérez, Cecilia G; Vergara, Carlos H

2016-03-01

Ecologists have been largely interested in the description and understanding of the power scaling relationships between body size and abundance of organisms. Many studies have focused on estimating the exponents of these functions across taxonomic groups and spatial scales, to draw inferences about the processes underlying this pattern. The exponents of these functions usually approximate -3/4 at geographical scales, but they deviate from this value when smaller spatial extensions are considered. This has led to propose that body size-abundance relationships at small spatial scales may reflect the impact of environmental changes. This study tests this hypothesis by examining body size spectra of benthic shrimps (Decapoda: Caridea) and snails (Gastropoda) in the Tamiahua lagoon, a brackish body water located in the Eastern coast of Mexico. We mea- sured water quality parameters (dissolved oxygen, salinity, pH, water temperature, sediment organic matter and chemical oxygen demand) and sampled benthic macrofauna during three different climatic conditions of the year (cold, dry and rainy season). Given the small size of most individuals in the benthic macrofaunal samples, we used body volume, instead of weight, to estimate their body size. Body size-abundance relationships of both taxonomic groups were described by tabulating data from each season into base-2 logarithmic body size bins. In both taxonomic groups, observed frequencies per body size class in each season were standardized to yield densities (i.e., individuals/m(3)). Nonlinear regression analyses were separately performed for each taxonomic group at each season to assess whether body size spectra followed power scaling functions. Additionally, for each taxonomic group, multiple regression analyses were used to determine whether these relationships varied among seasons. Our results indicated that, while body size-abundance relationships in both taxonomic groups followed power functions, the parameters defining the shape of these relationships varied among seasons. These variations in the parameters of the body size-abundance relationships seems to be related to changes in the abundance of individuals within the different body size classes, which seems to follow the seasonal changes that occur in the environmental conditions of the lagoon. Thus, we propose that these body size-abundance relation- ships are influenced by the frequency and intensity of environmental changes affecting this ecosystem.

Macrofaunal Succession and Community Structure in Salicornia Marshes of Southern California

NASA Astrophysics Data System (ADS)

Talley, T. S.; Levin, L. A.

1999-11-01

Lack of basic understanding of ecosystem structure and function forms a major impediment to successful conservation of coastal ecosystems. This paper provides a description of the fauna and examines faunal succession in Salicornia -vegetated sediments of southern California. Environmental attributes (vegetation and sediment properties) and macrofaunal (animals ≥0·3 mm) community structure were examined in sediments of five natural, southern California Salicornia spp. marshes (Tijuana Estuary, San Diego Bay, Mission Bay, Upper Newport Bay and Anaheim Bay) and in created Salicornia marshes 16 months to 10 years in age, located within four of the bays. Oligochaetes and insects were the dominant taxa in both natural (71 to 98% of total fauna) and created (91 to 97%) marshes. In San Diego, Newport and Anaheim Bays, macrofaunal densities were generally higher in the created marshes (88 000 to 290 000 ind m -2) than in their natural counterparts (26 000 to 50 000 ind m -2). In the youngest system, Mission Bay, the reverse was true (natural: 113 000 vs created: 28 000 ind m -2). Similar species numbers were recorded from the created and adjacent natural marshes. Insects, especially chironomids, dolichopodids, and heleids, as well as the naidid oligochaete, Paranais litoralis, characterize early successional stages. Enchytraeid and tubificid oligochaetes reflect later succession evident in natural and older created marshes. Sediment organic matter (both combustible and below-ground plant biomass) was the environmental variable most commonly associated with densities of various macrofaunal taxa. These relationships were generally negative in the natural marshes and positive in the created marshes. Within-bay comparisons of macrofauna from natural Salicornia- vs Spartina -vegetated habitat in San Diego and Mission Bays revealed lower macrofaunal density (San Diego Bay only), proportionally fewer oligochaetes and more insects, and no differences in species richness in the Salicornia habitat. The oldest created Salicornia marsh (San Diego Bay) exhibited an assemblage intermediate in composition between those of the natural Salicornia- and Spartina- vegetated marshes. These results suggest: (a) faunal recovery following Salicornia marsh creation can require 10 or more years, (b) high macrofaunal variability among bays requires marsh creation reference site selection from within the same bay, and (c) Spartina -based research should not be used for Salicornia marsh management decisions.

Geographical variation in oligochaete density and biomass in subtropical mangrove wetlands of China

NASA Astrophysics Data System (ADS)

Chen, Xinwei; Cai, Lizhe; Zhou, Xiping; Rao, Yiyong

2017-10-01

Oligochaetes play an important role in nutrient cycling and energy flow in benthic food webs as well as in mangrove wetlands. However, they have not been as extensively studied as other macrofaunal groups such as polychaetes, gastropods, bivalves, and crustaceans. Under the assumption that oligochaete density and biomass obey specific geographical distribution patterns in subtropical mangrove wetlands of China, we investigated these two parameters in the Luoyang Estuary of Quanzhou Bay, Zhangjiang Estuary and Gaoqiao mangrove wetlands. A geographical gradient in oligochaete density was present in Aegiceras corniculatum and Kandelia obovata habitats, whereby it decreased from lower latitudes to higher latitudes. Further, ANOVA tests on oligochaete distribution revealed that both oligochaete density and biomass were significantly influenced by region, season and region × season at the A. corniculatum and K. obovata habitats. The annual average oligochaete density and biomass at the A. corniculatum habitat were higher than that at the K. obovata habitat, in both the Luoyang and Zhangjiang estuaries. There were significant correlations between oligochaete density and biomass and sediment particle size parameters, confirming that sand, silt, and clay contents were the key environmental factors affecting oligochaete distribution.

Isolation, Characterization, and Polyaromatic Hydrocarbon Degradation Potential of Aerobic Bacteria from Marine Macrofaunal Burrow Sediments and Description of Lutibacterium anuloederans gen. nov., sp. nov., and Cycloclasticus spirillensus sp. nov.†

PubMed Central

Chung, W. K.; King, G. M.

2001-01-01

Two new polyaromatic hydrocarbon-degrading marine bacteria have been isolated from burrow wall sediments of benthic macrofauna by using enrichments on phenanthrene. Strain LC8 (from a polychaete) and strain M4-6 (from a mollusc) are aerobic and gram negative and require sodium chloride (>1%) for growth. Both strains can use 2- and 3-ring polycyclic aromatic hydrocarbons as their sole carbon and energy sources, but they are nutritionally versatile. Physiological and phylogenetic analyses based on 16S ribosomal DNA sequences suggest that strain M4-6 belongs to the genus Cycloclasticus and represents a new species, Cycloclasticus spirillensus sp. nov. Strain LC8 appears to represent a new genus and species, Lutibacterium anuloederans gen. nov., sp. nov., within the Sphingomonadaceae. However, when inoculated into sediment slurries with or without exogenous phenanthrene, only L. anuloederans appeared to sustain a significant phenanthrene uptake potential throughout a 35-day incubation. In addition, only L. anuloederans appeared to enhance phenanthrene degradation in heavily contaminated sediment from Little Mystic Cove, Boston Harbor, Boston, Mass. PMID:11722910

Stable isotopes reveal habitat-related diet shifts in facultative deposit-feeders

NASA Astrophysics Data System (ADS)

Rossi, Francesca; Baeta, Alexandra; Marques, João C.

2015-01-01

Seagrass patches interspersed in a sediment matrix may vary environmental conditions and affect feeding habits of consumers and food-web structure. This paper investigates diet shifts between bare sediments and a Zostera noltei (Hornemann, 1832) meadow for three facultative deposit-feeding macrofaunal consumers, notably the bivalve Scrobicularia plana (da Costa, 1778), the polychaete Hediste diversicolor (O.T. Müller, 1776), and the gastropod Hydrobia ulvae (Pennant, 1778). In July 2008, one eelgrass meadow and two bare sediment locations were chosen in the Mondego estuary (40° 08″ N, 8° 50‧ W, Portugal) and sampled for stable isotope signatures (δ13C and δ15N) of macrofauna consumers and some of their potential basal food sources, such as sedimentary organic matter (SOM), microphytobenthos (MPB), seagrass shoots, leaves and seaweeds laying on the surface sediment. The δ15N of H. diversicolor was 3‰ higher in the eelgrass meadow than in bare sediment, indicating a change of trophic position, whereas the Bayesian stable-isotope mixing model showed that S. plana assimilated more macroalgal detritus than microphytobenthos in the eelgrass bed. Such habitat-related diet shifts have the potential to change structure and spatial dynamics of benthic food webs.

Variation in the macrofaunal community over large temporal and spatial scales in the southern Yellow Sea

NASA Astrophysics Data System (ADS)

Xu, Yong; Sui, Jixing; Yang, Mei; Sun, Yue; Li, Xinzheng; Wang, Hongfa; Zhang, Baolin

2017-09-01

To detect large, temporal- and spatial-scale variations in the macrofaunal community in the southern Yellow Sea, data collected along the western, middle and eastern regions of the southern Yellow Sea from 1958 to 2014 were organized and analyzed. Statistical methods such as cluster analysis, non-metric multidimensional scaling ordination (nMDS), permutational multivariate analysis of variance (PERMANOVA), redundancy analysis (RDA) and canonical correspondence analysis (CCA) were applied. The abundance of polychaetes increased in the western region but decreased in the eastern region from 1958 to 2014, whereas the abundance of echinoderms showed an opposite trend. For the entire macrofaunal community, Margalef's richness (d), the Shannon-Wiener index (H‧) and Pielou's evenness (J‧) were significantly lower in the eastern region when compared with the other two regions. No significant temporal differences were found for d and H‧, but there were significantly lower values of J‧ in 2014. Considerable variation in the macrofaunal community structure over the past several decades and among the geographical regions at the species, genus and family levels were observed. The species, genera and families that contributed to the temporal variation in each region were also identified. The most conspicuous pattern was the increase in the species Ophiura sarsii vadicola in the eastern region. In the western region, five polychaetes (Ninoe palmata, Notomastus latericeus, Paralacydonia paradoxa, Paraprionospio pinnata and Sternaspis scutata) increased consistently from 1958 to 2014. The dominance curves showed that both the species diversity and the dominance patterns were relatively stable in the western and middle regions. Environmental parameters such as depth, temperature and salinity could only partially explain the observed biological variation in the southern Yellow Sea. Anthropogenic activities such as demersal fishing and other unmeasured environmental variables may be more responsible for the long-term changes in the macrofaunal community.

Insights into the benthic communities response to the inflow of Black Sea mesotrophic waters in the North Aegean Sea

NASA Astrophysics Data System (ADS)

Lampadariou, Nikolaos; Sevastou, Katerina; Podaras, Dimitrios; Tselepides, Anastasios

2017-10-01

The effects of the Dardanelles inflow of buoyant, modified Black Sea waters (BSW) of low salinity and temperature, on the meio- and macrobenthic communities of the north Aegean ecosystem was investigated during two cruises in October 2013 and March 2014. Sediment samples were collected from two stations subjected to the BSW effect, one shallow and one deep north of the Dardanelles Straits, and from two stations of similar bathymetry, which were considered to be outside the influence of BSW and were located to the south of the Dardanelles Straits. Results suggest that there is an effect of the BSW on benthos, as both meiofaunal and macrofaunal standing stocks were lower at the most distant, and therefore least affected from the inflow, station, and higher at the station of similar bathymetry which was affected the most by the BSW inflow. Univariate and multivariate non-parametric analyses (nMDS, PERMANOVA) provided further support, indicating differences between the two areas (North vs. South) in the case of the deep stations, while differences between depth categories were evident in the area outside the BSW influence zone. Distance-based linear modeling (DISTLM) indicated that meiofauna correlated with proxies of food availability and sediment characteristics. Macrofauna, on the other hand, showed a rather high significant correlation with depth only. Nematode species composition was statistically significant different between depth categories only, yet the nMDS ordination clearly separated the deep southern station from the rest, with non-selective deposit feeders dominating the stations under the influence of the BSW, and epistratum feeders being important at the stations outside the influence of the BSW. It is concluded that both the meiofaunal and macrofaunal communities at the northern stations benefit from a constant input of high amounts of organic matter to the seafloor, while those at the southern area may be occasionally affected by the thermohaline BSW front, which may reach as far as the southern stations, resulting in higher but rather unpredictable organic enrichment.

Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

NASA Astrophysics Data System (ADS)

Cunha, Marina R.; Paterson, Gordon L. J.; Amaro, Teresa; Blackbird, Sabena; de Stigter, Henko C.; Ferreira, Clarisse; Glover, Adrian; Hilário, Ana; Kiriakoulakis, Konstadinos; Neal, Lenka; Ravara, Ascensão; Rodrigues, Clara F.; Tiago, Áurea; Billett, David S. M.

2011-12-01

The macrofaunal assemblages from three Portuguese submarine canyons, Nazaré, Cascais and Setúbal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes (˜1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m -2) and lower variability in Cascais (583-1125 ind. m -2). The high abundance and dominance of the assemblages in the middle section of Nazaré and Setúbal was accompanied by depressed biodiversity, while in Cascais, Hurlbert's expected species richness showed increasing values from the upper to the middle canyon, and maintained the high values at the lower section. Overall, the Nazaré Canyon showed the lowest expected species richness (ES (100): 16-39) and the Cascais Canyon the highest (39-54). There was a significant negative Kendall's correlation between total organic carbon concentrations in the superficial sediments and ES (100) and a significant positive correlation between total nitrogen and macrofauna density. The influences of organic enrichment, sediment heterogeneity and hydrodynamic regime on the abundance, diversity and community structure of the macrofauna are discussed. It is suggested that altered and localised environmental conditions in the Portuguese canyons play an important role in modifying more common abundance and diversity bathymetric patterns evident in many continental slope environments.

The effects of marine sand and gravel extraction on the sediment composition and macrofaunal community of a commercial dredging site (15 years post-dredging).

PubMed

Waye-Barker, Georgia A; McIlwaine, Paul; Lozach, Sophie; Cooper, Keith M

2015-10-15

A prediction that faunal recovery of a marine aggregate extraction site subjected to high dredging intensity was likely to take 15-20 years was investigated. Samples were collected at the high dredging intensity site and two reference sites in 2011 (15 years post-dredging). Results indicated that the high site had similar sediment characteristics to the reference sites by 2011. Macrofaunal data analyses showed no difference between the values of all calculated univariate measures (abundance, number of taxa, biomass and evenness) between the high and reference sites. Multivariate analyses found that the macrofaunal community at the high site was comparable to those of the reference sites by 2011. Overall, the results supported the predicted recovery time. The findings of the study suggest that persistent physical impacts prolonged the biological recovery of the high site. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Macrofaunal assemblages associated with the sponge Sarcotragus foetidus Schmidt, 1862 (Porifera: Demospongiae) at the coasts of Cyprus and Greece.

PubMed

Pavloudi, Christina; Christodoulou, Magdalini; Mavidis, Michalis

2016-01-01

This paper describes a dataset of macrofaunal organisms associated with the sponge Sarcotragus foetidus Schmidt, 1862, collected by scuba diving from two sampling sites: one in Greece (North Aegean Sea) and one in Cyprus (Levantine Sea). This dataset includes macrofaunal taxa inhabiting the demosponge Sarcotragus foetidus and contributes to the ongoing efforts of the Ocean Biogeographic Information System (OBIS) which aims at filling the gaps in our current knowledge of the world's oceans. This is the first paper, to our knowledge, where the macrofauna associated with S. foetidus from the Levantine Basin is being recorded. In total, 90 taxa were recorded, from which 83 were identified to the species level. Eight of these species are new records for the Levantine Basin. The dataset contains 213 occurrence records, fully annotated with all required metadata. It is accessible at http://lifewww-00.her.hcmr.gr:8080/medobis/resource.do?r=organismic_assemblages_sarcotragus_foetidus_cyprus_greece.

Demonstration of the SeptiStrand benthic microbial fuel cell powering a magnetometer for ship detection

NASA Astrophysics Data System (ADS)

Arias-Thode, Y. Meriah; Hsu, Lewis; Anderson, Greg; Babauta, Jerome; Fransham, Roy; Obraztsova, Anna; Tukeman, Gabriel; Chadwick, D. Bart

2017-07-01

The Navy has a need for monitoring conditions and gathering information in marine environments. Sensors can monitor and report environmental parameters and potential activities such as animal movements, ships, or personnel. However, there has to be a means to power these sensors. One promising enabling technology that has been shown to provide long-term power production in underwater environments is the benthic microbial fuel cells (BMFC). BMFCs are devices that generate energy by coupling bioanodes and biocathodes through an external energy harvester. Recent studies have demonstrated success for usage of BMFCs in powering small instruments and other devices on the seafloor over limited periods of time. In this effort, a seven-stranded BMFC linear array of 30 m was designed to power a seafloor magnetometer to detect passing ship movements through Pearl Harbor, Hawaii. The BMFC system was connected to a flyback energy harvesting circuit that charged the battery powering the magnetometer. The deployment was demonstrated the BMFC supplied power to the battery for approximately 38 days. This is the first large-scale demonstration system for usage of the SeptiStrand BMFC technology to power a relevant sensor.

The vesicomyid bivalve habitat at cold seeps supports heterogeneous and dynamic macrofaunal assemblages

NASA Astrophysics Data System (ADS)

Guillon, Erwan; Menot, Lénaïck; Decker, Carole; Krylova, Elena; Olu, Karine

2017-02-01

The high biodiversity found at cold seeps, despite elevated concentrations of methane and hydrogen sulfide, is attributed to multiple sources of habitat heterogeneity. In addition to geological and geochemical processes, biogenic habitats formed by large symbiont-bearing taxa, such as bivalves and siboglinid tubeworms, or by microbial mats drive the biodiversity of small-sized fauna. However, because these habitat-forming species also depend on geochemical gradients, the respective influence of abiotic and biotic factors in structuring associated macrofaunal communities is often unresolved. The giant pockmark Regab located at 3200 m depth on the Congo margin is characterized by different fluid-flow regimes, providing a mosaic of the most common biogenic habitats encountered at seeps: microbial mats, mussel beds, and vesicomyid clam beds; the latter being distributed along a gradient of environmental conditions from the center to the periphery of the pockmark. Here, we examined the structure of macrofaunal communities in biogenic habitats formed in soft sediment to (1) determine the influence of the habitats on the associated macrofaunal communities (inter-habitat comparison), (2) describe how macrofaunal communities vary among vesicomyid clam beds (intra-habitat comparison) and (3) assess the inter-annual variation in vesicomyid beds based on repeated sampling at a three-year interval. The highest densities were found in the microbial mat communities in intermediate fluid-flow areas, but they had low diversity - also observed in the sediment close to mussel beds. In contrast, vesicomyid beds harbored the highest diversity. The vesicomyid beds did not show a homogeneous macrofaunal community across sampled areas; instead, density and composition of macrofauna varied according to the location of the beds inside the pockmark. The clam bed sampled in the most active, central part of the pockmark resembled bacterial mat communities by the presence of highly sulfide-tolerant species living at the sediment surface, along with vesicomyid juveniles. This similarity suggests a gradual change in community composition from mats to clam beds. Inter-annual comparisons of the different clam beds highlighted that the most active central site had a more variable community than its peripheral counterparts. Finally, a rapid shift in community structure, particularly in polychaete families, in experimentally reduced oxygen concentrations in the central part of Regab, suggests that high beta-diversity communities can withstand intense variation in geochemical conditions. These community dynamics are likely related to the diversity and to the plasticity of the vesicomyids themselves, because they can cope with high spatial and temporal environmental variability at a very local scale.

Size matters at deep-sea hydrothermal vents: different diversity and habitat fidelity patterns of meio- and macrofauna

PubMed Central

Gollner, Sabine; Govenar, Breea; Fisher, Charles R.; Bright, Monika

2015-01-01

Species with markedly different sizes interact when sharing the same habitat. Unravelling mechanisms that control diversity thus requires consideration of a range of size classes. We compared patterns of diversity and community structure for meio- and macrofaunal communities sampled along a gradient of environmental stress at deep-sea hydrothermal vents on the East Pacific Rise (9° 50′ N) and neighboring basalt habitats. Both meio- and macrofaunal species richnesses were lowest in the high-stress vent habitat, but macrofaunal richness was highest among intermediate-stress vent habitats. Meiofaunal species richness was negatively correlated with stress, and highest on the basalt. In these deep-sea basalt habitats surrounding hydrothermal vents, meiofaunal species richness was consistently higher than that of macrofauna. Consideration of the physiological capabilities and life history traits of different-sized animals suggests that different patterns of diversity may be caused by different capabilities to deal with environmental stress in the 2 size classes. In contrast to meiofauna, adaptations of macrofauna may have evolved to allow them to maintain their physiological homeostasis in a variety of hydrothermal vent habitats and exploit this food-rich deep-sea environment in high abundances. The habitat fidelity patterns also differed: macrofaunal species occurred primarily at vents and were generally restricted to this habitat, but meiofaunal species were distributed more evenly across proximate and distant basalt habitats and were thus not restricted to vent habitats. Over evolutionary time scales these contrasting patterns are likely driven by distinct reproduction strategies and food demands inherent to fauna of different sizes. PMID:26166922

Wrack patches and their influence on upper-shore macrofaunal abundance in an Atlantic Canada sandy beach system

NASA Astrophysics Data System (ADS)

MacMillan, Mitchell R.; Quijón, Pedro A.

2012-08-01

Patches of stranded macrophytes (wrack) are a distinctive feature of sandy beaches worldwide and a potential food subsidy for their resident communities. Despite their relevance, the spatial variation of wrack and its potential influence on upper shore beach organisms remain poorly understood. Wrack and macrofauna were surveyed on seven sandy beaches associated with dunes, till bluffs and sandstone cliffs along the north shore of Prince Edward Island, Atlantic Canada. Wrack patch density, cover, and water content were measured, and their associated macrofauna was compared to the communities inhabiting nearby bare sediments. The survey found among-site spatial differences in wrack characteristics and identified rockweeds (Fucus serratus) and eelgrass (Zostera marina) as the main macrophyte species in the area. Macrofaunal abundances were higher in wrack than in bare sediments but this varied among locations. A field manipulation was then conducted at two sandy beaches to measure macrofauna colonization on patches of fresh and aged rockweed and eelgrass. Regardless of macrophyte's age, macrofaunal organisms preferentially colonized sediments associated with rockweeds. In addition, calculations across treatments detected positive relationships between macrofaunal abundance and wet mass, dry mass and water content of the wrack patches, regardless of macrophyte species or state. Macrophyte preferences were further explored by comparing the nutritional value of the plant tissues and assessing macrofauna feeding rates under laboratory conditions. Rockweed tissues had consistently higher protein, lipid and carbohydrate contents than eelgrass and were affected by higher invertebrate consumption rates. Overall, these results suggest that spatial variation and wrack features and species composition play key roles on the structure of the supralittoral macrofauna.

High intraspecific variability in the diet of a deep-sea nematode: Stable isotope and fatty acid analyses of Deontostoma tridentum on Chatham Rise, Southwest Pacific

NASA Astrophysics Data System (ADS)

Leduc, Daniel; Brown, Julie C. S.; Bury, Sarah J.; Lörz, Anne-Nina

2015-03-01

Small deep-sea organisms may exhibit a high degree of intraspecific variability in diet due to their ability to exploit a wide range of food sources and patchiness in food availability. Trophic interactions of small deep-sea benthic organisms, however, remain poorly understood. Here we describe spatial variation in diet/trophic level of the common deep-sea nematode Deontostoma tridentum on Chatham Rise, Southwest Pacific, using carbon and nitrogen stable isotope and fatty acid analyses. We also analysed sediment organic matter (SOM) and compared the isotopic composition of D. tridentum to other benthic and suprabenthic macrofaunal taxa with a variety of feeding modes. Variability in D. tridentum δ13C and δ15N signatures was high both among sites and within a single site on the southern flank of Chatham Rise. Among-site variation in SOM δ13C signatures was not sufficient to explain variation in nematode isotopic signatures. The presence of a positive correlation between δ13C and δ15N signatures of D. tridentum (both among and within sites) could suggest that differences in trophic level is the cause behind this variation. Nitrogen isotope data suggest the presence of 1-3 trophic levels in this species, which may reflect differences in prey availability, nematode body size, or habitat (benthic versus epizoic). Nematode δ15N values exceeded those of all other taxa we investigated, including other predators, but reasons for this enrichment remain unclear. The fatty acid composition of D. tridentum did not vary substantially between sites and was characterised by relatively high levels of 18:1n9 (15-20%) and polyunsaturated fatty acids (PUFAs; 22%). Although limited inferences can be made based on fatty acid composition due to the potential impacts of non-dietary factors, high levels of PUFAs indicate that D. tridentum represents a good source of these essential nutrients to higher trophic levels. In conclusion, our results show that (1) some deep-sea organisms exhibit a high degree of intraspecific variability in diet, and (2) nematodes may be an important source of PUFAs for larger animals in deep-sea environments, where the quality of SOM is low.

Energy transfer in the Congo deep-sea fan: From terrestrially-derived organic matter to chemosynthetic food webs

NASA Astrophysics Data System (ADS)

Pruski, A. M.; Decker, C.; Stetten, E.; Vétion, G.; Martinez, P.; Charlier, K.; Senyarich, C.; Olu, K.

2017-08-01

Large amounts of recent terrestrial organic matter (OM) from the African continent are delivered to the abyssal plain by turbidity currents and accumulate in the Congo deep-sea fan. In the recent lobe complex, large clusters of vesicomyid bivalves are found all along the active channel in areas of reduced sediment. These soft-sediment communities resemble those fuelled by chemoautotrophy in cold-seep settings. The aim of this study was to elucidate feeding strategies in these macrofaunal assemblages as part of a greater effort to understand the link between the inputs of terrestrially-derived OM and the chemosynthetic habitats. The biochemical composition of the sedimentary OM was first analysed in order to evaluate how nutritious the available particulate OM is for the benthic macrofauna. The terrestrial OM is already degraded when it reaches the final depositional area. However, high biopolymeric carbon contents (proteins, carbohydrates and lipids) are found in the channel of the recent lobe complex. In addition, about one to two thirds of the nitrogen can be assigned to peptide-like material. Even if this soil-derived OM is poorly digestible, turbiditic deposits contain such high amounts of organic carbon that there is enough biopolymeric carbon and proteacinous nitrogen to support dense benthic communities that contrast with the usual depauperate abyssal plains. Stable carbon and nitrogen isotopes and fatty acid biomarkers were then used to shed light on the feeding strategies allowing the energy transfer from the terrestrial OM brought by the turbidity currents to the abyssal food web. In the non-reduced sediment, surface detritivorous holothurians and suspension-feeding poriferans rely on detritic OM, thereby depending directly on the turbiditic deposits. The sulphur-oxidising symbiont bearing vesicomyids closely depend on the reprocessing of OM with methane and sulphide as final products. Their carbon and nitrogen isotopic signatures vary greatly among sites and could reflect the intensity of the anaerobic oxidation of methane (AOM) in the sediments. Within the vesicomyid habitats, the heterotrophic fauna exhibits a distinctively light carbon isotopic signature in comparison to the background sediments, clearly indicating the utilisation of chemosynthetically-derived OM. Fatty acid biomarkers further confirm that dorvilleid polychaetes consume aggregates that perform AOM. Terrestrial OM reprocessing by microbial consortium thus ensures its transfer to the benthic food web in the Congo deep-sea fan.

Interpretation of the Relationship between Benthic Fauna, Geologic Distributions, and Methane Seeps at Southern Hydrate Ridge, Oregon Continental Margin

NASA Astrophysics Data System (ADS)

Bigham, K.; Kelley, D. S.; Delaney, J. R.

2016-12-01

Deposits of methane sequestered along continental margins and their associated seeps are found worldwide. These seeps are of increasing interest and importance because of their potential as an energy source, their contribution to greenhouse gases, and the unique community of chemosynthetic microorganisms and fauna that they host. One of the best­studied methane seep sites is Southern Hydrate Ridge, which is at a water depth of 800 m. It is located 90 km west of Newport, Oregon. Despite extensive geophysical and biological research completed here, no studies have quantified the relationship of seep sites and seafloor geology to the spatial distribution and abundances of microbial and macrofaunal communities. High resolution, georeferenced photomosaics of the individual seeps and the associated biological communities at this site were collected in 2011, using the remotely operated vehicle ROPOS. Detailed analyses of these images has allowed for the quantification and characterization of the diversity and structure of the faunal community. Results show that both the distribution and abundances of seep organisms are highly variable. Further examination of these photomosaics may improve understanding of the relationships between faunal distributions and seep locations, with implications for the impacts that chemical gradients have on these ecosystems.

Warming alters community size structure and ecosystem functioning

PubMed Central

Dossena, Matteo; Yvon-Durocher, Gabriel; Grey, Jonathan; Montoya, José M.; Perkins, Daniel M.; Trimmer, Mark; Woodward, Guy

2012-01-01

Global warming can affect all levels of biological complexity, though we currently understand least about its potential impact on communities and ecosystems. At the ecosystem level, warming has the capacity to alter the structure of communities and the rates of key ecosystem processes they mediate. Here we assessed the effects of a 4°C rise in temperature on the size structure and taxonomic composition of benthic communities in aquatic mesocosms, and the rates of detrital decomposition they mediated. Warming had no effect on biodiversity, but altered community size structure in two ways. In spring, warmer systems exhibited steeper size spectra driven by declines in total community biomass and the proportion of large organisms. By contrast, in autumn, warmer systems had shallower size spectra driven by elevated total community biomass and a greater proportion of large organisms. Community-level shifts were mirrored by changes in decomposition rates. Temperature-corrected microbial and macrofaunal decomposition rates reflected the shifts in community structure and were strongly correlated with biomass across mesocosms. Our study demonstrates that the 4°C rise in temperature expected by the end of the century has the potential to alter the structure and functioning of aquatic ecosystems profoundly, as well as the intimate linkages between these levels of ecological organization. PMID:22496185

Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution.

PubMed

Ferrando, Agustina; Gonzalez, Emilia; Franco, Marcos; Commendatore, Marta; Nievas, Marina; Militon, Cécile; Stora, Georges; Gilbert, Franck; Esteves, José Luis; Cuny, Philippe

2015-10-01

The Patagonian coast is characterized by the existence of pristine ecosystems which may be particularly sensitive to oil contamination. In this study, a simulated oil spill at acute and chronic input levels was carried out to assess the effects of contamination on the macrobenthic community structure and the bioturbation activity of sediments sampled in Caleta Valdés creek. Superficial sediments were either noncontaminated or contaminated by Escalante crude oil and incubated in the laboratory for 30 days. Oil contamination induced adverse effects on macrobenthic community at both concentrations with, for the highest concentration, a marked decrease of approximately 40 and 55 % of density and specific richness, respectively. Besides the disappearance of sensitive species, some other species like Oligochaeta sp. 1, Paranebalia sp., and Ostracoda sp. 2 species have a higher resistance to oil contamination. Sediment reworking activity was also affected by oil addition. At the highest level of contamination, nearly no activity was observed due to the high mortality of macroorganisms. The results strongly suggest that an oil spill in this protected marine area with no previous history of contamination would have a deep impact on the non-adapted macrobenthic community.

Marine benthic ecological functioning over decreasing taxonomic richness

NASA Astrophysics Data System (ADS)

Törnroos, Anna; Bonsdorff, Erik; Bremner, Julie; Blomqvist, Mats; Josefson, Alf B.; Garcia, Clement; Warzocha, Jan

2015-04-01

Alterations to ecosystem function due to reductions in species richness are predicted to increase as humans continue to affect the marine environment, especially in coastal areas, which serve as the interface between land and sea. The potential functional consequences due to reductions in species diversity have attracted considerable attention recently but little is known about the consequence of such loss in natural communities. We examined how the potential for function is affected by natural reductions in taxon richness using empirical (non-simulated) coastal marine benthic macrofaunal data from the Skagerrak-Baltic Sea region (N. Europe), where taxon richness decreases 25-fold, from 151 to 6 taxa. To estimate functional changes we defined multiple traits (10 traits and 51 categories) on which trait category richness, functional diversity (FD) and number of taxa per trait category were calculated. Our results show that decrease in taxon richness leads to an overall reduction in function but functional richness remains comparatively high even at the lowest level of taxon richness. Although the taxonomic reduction was sharp, up to 96% of total taxon richness, we identified both potential thresholds in functioning and subtler changes where function was maintained along the gradient. The functional changes were not only caused by reductions in taxa per trait category, some categories were maintained or even increased. Primarily, the reduction in species richness altered trait categories related to feeding, living and movement and thus potentially could have an effect on various ecosystem processes. This highlights the importance of recognising ecosystem multifunctionality, especially at low taxonomic richness. We also found that in this system rare species (singletons) did not stand for the functional complexities and changes. Our findings were consistent with theoretical and experimental predictions and suggest that a large proportion of the information about alterations of function is found in measures such as functional diversity and number of taxa per trait category.

Benthic macrofaunal colonization patterns and preservation of laminated sediments: Observations in an extreme coastal basin environment in the lower Gulf of California

NASA Astrophysics Data System (ADS)

Herguera, J.; Paull, C. K.; Anderson, K.; Gwiazda, R.; Lundsten, E. M.; Kundz, L.; Edwards, B. D.; McGann, M. L.

2012-12-01

New observations and cores obtained with the ROV Doc Ricketts operated from the RV/Western Flyer provide a glimpse into a macrofauna barren sea-floor where laminated sediments are known to accumulate on the sea-floor of Alfonso Basin. This basin, located north of La Paz Bay, Baja California, is known to be an important repository of laminated sediments due to a combination of the relatively high input of terrigenous sediments brought in by summer rains, a moderate to high export productivity from its surface waters, and the very low oxygen concentrations at depth bathed by tropical subsurface waters. These laminated sediments are unique repositories of paleoceanographic and paleoclimatic information for its very high resolution records of past conditions comparable to ice core, tree ring, coral and cave records although spanning continuously much further back in time. However, the paleoceanographic community rarely has had the opportunity to visualize the seafloor surface where these sediments are accumulating and examine the biological abundance patterns in these extreme environments. Here we will show results from ROV Doc Ricketts quantitative video transects providing benthic faunal abundance patterns on the seafloor in these highly oxygen depleted bottom waters. These observations are further compared with the underlying stratigraphy. A coring system carried on the ROV allowed us to replicate cores and to collect a transect of 5 closely spaced cores to evaluate the horizontal extent of the observed variability down-core. We will also show some preliminary results from x-radiographs showing the nature of the laminations and its sediment composition based on elemental analysis on organic carbon, carbonate and biogenic opal analysis. New XRF results from a box core will be used to calibrate its terrigenous components with the historical rainfall record and evaluate its potential to reconstruct summer precipitation patterns in this region.

Long-Term Observations of Epibenthic Fish Zonation in the Deep Northern Gulf of Mexico

PubMed Central

Wei, Chih-Lin; Rowe, Gilbert T.; Haedrich, Richard L.; Boland, Gregory S.

2012-01-01

A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964–1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983–1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m−2), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient. PMID:23056412

Long-term observations of epibenthic fish zonation in the deep northern Gulf of Mexico.

PubMed

Wei, Chih-Lin; Rowe, Gilbert T; Haedrich, Richard L; Boland, Gregory S

2012-01-01

A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964-1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983-1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m(-2)), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.

Population trends, bend use relative to available habitat and within-river-bend habitat use of eight indicator species of Missouri and Lower Kansas River benthic fishes: 15 years after baseline assessment

USGS Publications Warehouse

Wildhaber, Mark L.; Yang, Wen-Hsi; Arab, Ali

2016-01-01

A baseline assessment of the Missouri River fish community and species-specific habitat use patterns conducted from 1996 to 1998 provided the first comprehensive analysis of Missouri River benthic fish population trends and habitat use in the Missouri and Lower Yellowstone rivers, exclusive of reservoirs, and provided the foundation for the present Pallid Sturgeon Population Assessment Program (PSPAP). Data used in such studies are frequently zero inflated. To address this issue, the zero-inflated Poisson (ZIP) model was applied. This follow-up study is based on PSPAP data collected up to 15 years later along with new understanding of how habitat characteristics among and within bends affect habitat use of fish species targeted by PSPAP, including pallid sturgeon. This work demonstrated that a large-scale, large-river, PSPAP-type monitoring program can be an effective tool for assessing population trends and habitat usage of large-river fish species. Using multiple gears, PSPAP was effective in monitoring shovelnose and pallid sturgeons, sicklefin, shoal and sturgeon chubs, sand shiner, blue sucker and sauger. For all species, the relationship between environmental variables and relative abundance differed, somewhat, among river segments suggesting the importance of the overall conditions of Upper and Middle Missouri River and Lower Missouri and Kansas rivers on the habitat usage patterns exhibited. Shoal and sicklefin chubs exhibited many similar habitat usage patterns; blue sucker and shovelnose sturgeon also shared similar responses. For pallid sturgeon, the primary focus of PSPAP, relative abundance tended to increase in Upper and Middle Missouri River paralleling stocking efforts, whereas no evidence of an increasing relative abundance was found in the Lower Missouri River despite stocking.

Bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (Mirounga leonina) in Prydz Bay, East Antarctica

PubMed Central

Bestley, Sophie; Corney, Stuart; Welsford, Dirk; Labrousse, Sara; Sumner, Michael; Hindell, Mark

2017-01-01

Antarctic coastal polynyas are persistent open water areas in the sea ice zone, and regions of high biological productivity thought to be important foraging habitat for marine predators. This study quantified southern elephant seal (Mirounga leonina) habitat use within and around the polynyas of the Prydz Bay region (63°E– 88°E) in East Antarctica, and examined the bio-physical characteristics structuring polynyas as foraging habitat. Output from a climatological regional ocean model was used to provide context for in situ temperature-salinity vertical profiles collected by tagged elephant seals and to characterise the physical properties structuring polynyas. Biological properties were explored using remotely-sensed surface chlorophyll (Chl-a) and, qualitatively, historical fish assemblage data. Spatially gridded residence time of seals was examined in relation to habitat characteristics using generalized additive mixed models. The results showed clear polynya usage during early autumn and increasingly concentrated usage during early winter. Bathymetry, Chl-a, surface net heat flux (representing polynya location), and bottom temperature were identified as significant bio-physical predictors of the spatio-temporal habitat usage. The findings from this study confirm that the most important marine habitats for juvenile male southern elephant seals within Prydz Bay region are polynyas. A hypothesis exists regarding the seasonal evolution of primary productivity, coupling from surface to subsurface productivity and supporting elevated rates of secondary production in the upper water column during summer-autumn. An advancement to this hypothesis is proposed here, whereby this bio-physical coupling is likely to extend throughout the water column as it becomes fully convected during autumn-winter, to also promote pelagic-benthic linkages important for benthic foraging within polynyas. PMID:28902905

Assessing the impacts of bait collection on inter-tidal sediment and the associated macrofaunal and bird communities: The importance of appropriate spatial scales.

PubMed

Watson, G J; Murray, J M; Schaefer, M; Bonner, A; Gillingham, M

2017-09-01

Bait collection is a multibillion dollar worldwide activity that is often managed ineffectively. For managers to understand the impacts on protected inter-tidal mudflats and waders at appropriate spatial scales macrofaunal surveys combined with video recordings of birds and bait collectors were undertaken at two UK sites. Dug sediment constituted approximately 8% of the surveyed area at both sites and is less muddy (lower organic content) than undug sediment. This may have significant implications for turbidity. Differences in the macrofaunal community between dug and undug areas if the same shore height is compared as well as changes in the dispersion of the community occurred at one site. Collection also induces a 'temporary loss of habitat' for some birds as bait collector numbers negatively correlate with wader and gull abundance. Bait collection changes the coherence and ecological structure of inter-tidal mudflats as well as directly affecting wading birds. However, as β diversity increased we suggest that management at appropriate hectare/site scales could maximise biodiversity/function whilst still supporting collection. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Benthic impacts of intertidal oyster culture, with consideration of taxonomic sufficiency.

PubMed

Forrest, Barrie M; Creese, Robert G

2006-01-01

An investigation of the impacts from elevated intertidal Pacific oyster culture in a New Zealand estuary showed enhanced sedimentation beneath culture racks compared with other sites. Seabed elevation beneath racks was generally lower than between them, suggesting that topographic patterns more likely result from a local effect of rack structures on hydrodynamic processes than from enhanced deposition. Compared with control sites, seabed sediments within the farm had a greater silt/clay and organic content, and a lower redox potential and shear strength. While a marked trend in macrofaunal species richness was not evident, species composition and dominance patterns were consistent with a disturbance gradient, with farm effects not evident 35 m from the perimeter of the racks. Of the environmental variables measured, sediment shear strength was most closely associated with the distribution and density of macrofauna, suggesting that human-induced disturbance from farming operations may have contributed to the biological patterns. To evaluate the taxonomic sufficiency needed to document impacts, aggregation to the family level based on Linnean classification was compared with an aggregation scheme based on ;general groups' identifiable with limited taxonomic expertise. Compared with species-level analyses, spatial patterns of impact were equally discernible at both aggregation levels used, provided density rather than presence/absence data were used. Once baseline conditions are established and the efficacy of taxonomic aggregation demonstrated, a ;general group' scheme provides an appropriate and increasingly relevant tool for routine monitoring.

Macrofauna regulate heterotrophic bacterial carbon and nitrogen incorporation in low-oxygen sediments

PubMed Central

Hunter, William R; Veuger, Bart; Witte, Ursula

2012-01-01

Oxygen minimum zones (OMZs) currently impinge upon >1 million km2 of sea floor and are predicted to expand with climate change. We investigated how changes in oxygen availability, macrofaunal biomass and retention of labile organic matter (OM) regulate heterotrophic bacterial C and N incorporation in the sediments of the OMZ-impacted Indian continental margin (540–1100 m; [O2]=0.35–15 μmol l−1). In situ pulse-chase experiments traced 13C:15N-labelled phytodetritus into bulk sediment OM and hydrolysable amino acids, including the bacterial biomarker 𝒟-alanine. Where oxygen availability was lowest ([O2]=0.35 μmol l−1), metazoan macrofauna were absent and bacteria assimilated 30–90% of the labelled phytodetritus within the sediment. At higher oxygen levels ([O2]=2–15 μmol l−1) the macrofaunal presence and lower phytodetritus retention with the sediment occur concomitantly, and bacterial phytodetrital incorporation was reduced and retarded. Bacterial C and N incorporation exhibited a significant negative relationship with macrofaunal biomass across the OMZ. We hypothesise that fauna–bacterial interactions significantly influence OM recycling in low-oxygen sediments and need to be considered when assessing the consequences of global change on biogeochemical cycles. PMID:22592818

Meio- and Macrofaunal Communities in Artificial Water-Filled Tree Holes: Effects of Seasonality, Physical and Chemical Parameters, and Availability of Food Resources

PubMed Central

Ptatscheck, Christoph; Traunspurger, Walter

2015-01-01

Objectives In this study we investigated the dynamics of meiofaunal and macrofaunal communities in artificial water-filled tree holes. The abundances and, for the first time, biomasses and secondary production rates of these communities were examined. The experimental set-up consisted of 300 brown plastic cups placed in temperate mixed forests and sampled five times over a period of 16 months to determine the impact of (i) seasonal events, (ii) physicochemical parameters, and (iii) food resources on the tree hole metazoans. Outcomes Metazoan organisms, especially the meiofauna (rotifers and nematodes) occupied nearly all of the cups (> 99%) throughout the year. Between 55% and 99% of the metazoan community was represented by rotifers (max. 557,000 individuals 100 cm-2) and nematodes (max. 58,000 individuals 100 cm-2). Diptera taxa, particularly Dasyhelea sp. (max. 256 individuals 100 cm-2) dominated the macrofaunal community. Macrofauna accounted for the majority of the metazoan biomass, with a mean dry weight of 5,800 μg 100 cm-2 and an annual production rate of 20,400 μg C 100 cm-2, whereas for meiofauna mean biomass and annual production were 100 μg 100 cm-2 and 5,300 μg C 100 cm-2, respectively. The macrofaunal taxa tended to show more fluctuating population dynamic while the meiofaunal dynamic was rather low with partly asynchronous development. Seasonality (average temperature and rain intervals) had a significant impact on both meiofauna and macrofauna. Furthermore, bottom-up control (chlorophyll-a and organic carbon), mainly attributable to algae, was a significant factor that shaped the metazoan communities. In contrast, physicochemical water parameters had no evident influence. 23.7% of organism density distribution was explained by redundancy analysis (RDA) indicating a high dynamic and asynchrony of the systems. PMID:26284811

Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities.

PubMed

Laroche, Olivier; Wood, Susanna A; Tremblay, Louis A; Lear, Gavin; Ellis, Joanne I; Pochon, Xavier

2017-01-01

Sequencing environmental DNA (eDNA) is increasingly being used as an alternative to traditional morphological-based identification to characterize biological assemblages and monitor anthropogenic impacts in marine environments. Most studies only assess eDNA which, compared to eRNA, can persist longer in the environment after cell death. Therefore, eRNA may provide a more immediate census of the environment due to its relatively weaker stability, leading some researchers to advocate for the use of eRNA as an additional, or perhaps superior proxy for portraying ecological changes. A variety of pre-treatment techniques for screening eDNA and eRNA derived operational taxonomic units (OTUs) have been employed prior to statistical analyses, including removing singleton taxa (i.e., OTUs found only once) and discarding those not present in both eDNA and eRNA datasets. In this study, we used bacterial (16S ribosomal RNA gene) and eukaryotic (18S ribosomal RNA gene) eDNA- and eRNA-derived data from benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand). Macro-infauna (visual classification of benthic invertebrates) and physico-chemical data were analyzed in parallel. We tested the effect of removing singleton taxa, and removing taxa not present in the eDNA and eRNA libraries from the same environmental sample (trimmed by shared OTUs), by comparing the impact of the oil production platform on alpha- and beta-diversity of the eDNA/eRNA-based biological assemblages, and by correlating these to the morphologically identified macro-faunal communities and the physico-chemical data. When trimmed by singletons, presence/absence information from eRNA data represented the best proxy to detect changes on species diversity for both bacteria and eukaryotes. However, assessment of quantitative beta-diversity from read abundance information of bacteria eRNA did not, contrary to eDNA, reveal any impact from the oil production activity. Overall, the data appeared more robust when trimmed by shared OTUs, showing a greater effect of the platform on alpha- and beta-diversity. Trimming by shared OTUs likely removes taxa derived from legacy DNA and technical artefacts introduced through reverse transcriptase, polymerase-chain-reaction and sequencing. Findings from our scoping study suggest that metabarcoding-based biomonitoring surveys should, if funds, time and expertise allow, be assessed using both eDNA and eRNA products.

Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities

PubMed Central

Wood, Susanna A.; Tremblay, Louis A.; Lear, Gavin; Ellis, Joanne I.; Pochon, Xavier

2017-01-01

Sequencing environmental DNA (eDNA) is increasingly being used as an alternative to traditional morphological-based identification to characterize biological assemblages and monitor anthropogenic impacts in marine environments. Most studies only assess eDNA which, compared to eRNA, can persist longer in the environment after cell death. Therefore, eRNA may provide a more immediate census of the environment due to its relatively weaker stability, leading some researchers to advocate for the use of eRNA as an additional, or perhaps superior proxy for portraying ecological changes. A variety of pre-treatment techniques for screening eDNA and eRNA derived operational taxonomic units (OTUs) have been employed prior to statistical analyses, including removing singleton taxa (i.e., OTUs found only once) and discarding those not present in both eDNA and eRNA datasets. In this study, we used bacterial (16S ribosomal RNA gene) and eukaryotic (18S ribosomal RNA gene) eDNA- and eRNA-derived data from benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand). Macro-infauna (visual classification of benthic invertebrates) and physico-chemical data were analyzed in parallel. We tested the effect of removing singleton taxa, and removing taxa not present in the eDNA and eRNA libraries from the same environmental sample (trimmed by shared OTUs), by comparing the impact of the oil production platform on alpha- and beta-diversity of the eDNA/eRNA-based biological assemblages, and by correlating these to the morphologically identified macro-faunal communities and the physico-chemical data. When trimmed by singletons, presence/absence information from eRNA data represented the best proxy to detect changes on species diversity for both bacteria and eukaryotes. However, assessment of quantitative beta-diversity from read abundance information of bacteria eRNA did not, contrary to eDNA, reveal any impact from the oil production activity. Overall, the data appeared more robust when trimmed by shared OTUs, showing a greater effect of the platform on alpha- and beta-diversity. Trimming by shared OTUs likely removes taxa derived from legacy DNA and technical artefacts introduced through reverse transcriptase, polymerase-chain-reaction and sequencing. Findings from our scoping study suggest that metabarcoding-based biomonitoring surveys should, if funds, time and expertise allow, be assessed using both eDNA and eRNA products. PMID:28533985

Macrofaunal communites at newly discovered hydrothermal fields in Central Indian Ridge

NASA Astrophysics Data System (ADS)

Miyazaki, J.; Takai, K.; Nakamura, K.; Watanabe, H.; Noguchi, T.; Matsuzaki, T.; Watsuji, T.; Nemoto, S.; Kawagucci, S.; Shibuya, T.; Okamura, K.; Mochizuki, M.; Orihashi, Y.; Marie, D.; Koonjul, M.; Singh, M.; Beedessee, G.; Bhikajee, M.; Tamaki, K.

2010-12-01

In YK09-13 Leg1 cruise targeted on the segment 15 and 16 in Central Indian Ridge (CIR), we have successfully discovered two hydrothermal fields, DODO field and Solitaire field. We expected that there were unique macrofaunal communities in these hydrothermal fields, because there was in Kairei field on the segment 1 in CIR. Particularly, a gastropod, “scaly-foot”, which has sclerites covered with iron-sulfide has only discovered in Kairei field. Therefore, it was interesting whether this unique scaly-foot only exists in Kairei fields or widely expands in CIR. In DODO fields, there were 10 to 15 active chimneys. However, very few hydrothermal vent-endemic faunas were observed. We observed only crabs and shrimps but we did not found shells. As opposed to in the Dodo field, biomass and composition of macrofaunal communities were highly prosperous in the Solitaire field, being equal to Kairei field. Although we have an only one dive to explore the Solitaire field, many predominant taxa were sampled and observed, for example, Alviniconcha, mussels, vanacles and so on. However, the most outstanding feature was the presence of a new morphotype of ‘scaly-foot’ gastropod. Discovery of this new-morphytpe ‘scary-foot” disproved our knowledge. In this conference, I will present these observations. Especially characterization of two types of scaly-foot (Kairei-type and Solitaire-type) will be focused.

Deep-Sea Biodiversity in the Mediterranean Sea: The Known, the Unknown, and the Unknowable

PubMed Central

Danovaro, Roberto; Company, Joan Batista; Corinaldesi, Cinzia; D'Onghia, Gianfranco; Galil, Bella; Gambi, Cristina; Gooday, Andrew J.; Lampadariou, Nikolaos; Luna, Gian Marco; Morigi, Caterina; Olu, Karine; Polymenakou, Paraskevi; Ramirez-Llodra, Eva; Sabbatini, Anna; Sardà, Francesc; Sibuet, Myriam; Tselepides, Anastasios

2010-01-01

Deep-sea ecosystems represent the largest biome of the global biosphere, but knowledge of their biodiversity is still scant. The Mediterranean basin has been proposed as a hot spot of terrestrial and coastal marine biodiversity but has been supposed to be impoverished of deep-sea species richness. We summarized all available information on benthic biodiversity (Prokaryotes, Foraminifera, Meiofauna, Macrofauna, and Megafauna) in different deep-sea ecosystems of the Mediterranean Sea (200 to more than 4,000 m depth), including open slopes, deep basins, canyons, cold seeps, seamounts, deep-water corals and deep-hypersaline anoxic basins and analyzed overall longitudinal and bathymetric patterns. We show that in contrast to what was expected from the sharp decrease in organic carbon fluxes and reduced faunal abundance, the deep-sea biodiversity of both the eastern and the western basins of the Mediterranean Sea is similarly high. All of the biodiversity components, except Bacteria and Archaea, displayed a decreasing pattern with increasing water depth, but to a different extent for each component. Unlike patterns observed for faunal abundance, highest negative values of the slopes of the biodiversity patterns were observed for Meiofauna, followed by Macrofauna and Megafauna. Comparison of the biodiversity associated with open slopes, deep basins, canyons, and deep-water corals showed that the deep basins were the least diverse. Rarefaction curves allowed us to estimate the expected number of species for each benthic component in different bathymetric ranges. A large fraction of exclusive species was associated with each specific habitat or ecosystem. Thus, each deep-sea ecosystem contributes significantly to overall biodiversity. From theoretical extrapolations we estimate that the overall deep-sea Mediterranean biodiversity (excluding prokaryotes) reaches approximately 2805 species of which about 66% is still undiscovered. Among the biotic components investigated (Prokaryotes excluded), most of the unknown species are within the phylum Nematoda, followed by Foraminifera, but an important fraction of macrofaunal and megafaunal species also remains unknown. Data reported here provide new insights into the patterns of biodiversity in the deep-sea Mediterranean and new clues for future investigations aimed at identifying the factors controlling and threatening deep-sea biodiversity. PMID:20689848

Deep-sea biodiversity in the Mediterranean Sea: the known, the unknown, and the unknowable.

PubMed

Danovaro, Roberto; Company, Joan Batista; Corinaldesi, Cinzia; D'Onghia, Gianfranco; Galil, Bella; Gambi, Cristina; Gooday, Andrew J; Lampadariou, Nikolaos; Luna, Gian Marco; Morigi, Caterina; Olu, Karine; Polymenakou, Paraskevi; Ramirez-Llodra, Eva; Sabbatini, Anna; Sardà, Francesc; Sibuet, Myriam; Tselepides, Anastasios

2010-08-02

Deep-sea ecosystems represent the largest biome of the global biosphere, but knowledge of their biodiversity is still scant. The Mediterranean basin has been proposed as a hot spot of terrestrial and coastal marine biodiversity but has been supposed to be impoverished of deep-sea species richness. We summarized all available information on benthic biodiversity (Prokaryotes, Foraminifera, Meiofauna, Macrofauna, and Megafauna) in different deep-sea ecosystems of the Mediterranean Sea (200 to more than 4,000 m depth), including open slopes, deep basins, canyons, cold seeps, seamounts, deep-water corals and deep-hypersaline anoxic basins and analyzed overall longitudinal and bathymetric patterns. We show that in contrast to what was expected from the sharp decrease in organic carbon fluxes and reduced faunal abundance, the deep-sea biodiversity of both the eastern and the western basins of the Mediterranean Sea is similarly high. All of the biodiversity components, except Bacteria and Archaea, displayed a decreasing pattern with increasing water depth, but to a different extent for each component. Unlike patterns observed for faunal abundance, highest negative values of the slopes of the biodiversity patterns were observed for Meiofauna, followed by Macrofauna and Megafauna. Comparison of the biodiversity associated with open slopes, deep basins, canyons, and deep-water corals showed that the deep basins were the least diverse. Rarefaction curves allowed us to estimate the expected number of species for each benthic component in different bathymetric ranges. A large fraction of exclusive species was associated with each specific habitat or ecosystem. Thus, each deep-sea ecosystem contributes significantly to overall biodiversity. From theoretical extrapolations we estimate that the overall deep-sea Mediterranean biodiversity (excluding prokaryotes) reaches approximately 2805 species of which about 66% is still undiscovered. Among the biotic components investigated (Prokaryotes excluded), most of the unknown species are within the phylum Nematoda, followed by Foraminifera, but an important fraction of macrofaunal and megafaunal species also remains unknown. Data reported here provide new insights into the patterns of biodiversity in the deep-sea Mediterranean and new clues for future investigations aimed at identifying the factors controlling and threatening deep-sea biodiversity.

The environmental impact of sewage and wastewater outfalls in Antarctica: An example from Davis station, East Antarctica.

PubMed

Stark, Jonathan S; Corbett, Patricia A; Dunshea, Glenn; Johnstone, Glenn; King, Catherine; Mondon, Julie A; Power, Michelle L; Samuel, Angelingifta; Snape, Ian; Riddle, Martin

2016-11-15

We present a comprehensive scientific assessment of the environmental impacts of an Antarctic wastewater ocean outfall, at Davis station in East Antarctica. We assessed the effectiveness of current wastewater treatment and disposal requirements under the Protocol on Environmental Protection to the Antarctic Treaty. Macerated wastewater has been discharged from an outfall at Davis since the failure of the secondary treatment plant in 2005. Water, sediment and wildlife were tested for presence of human enteric bacteria and antibiotic resistance mechanisms. Epibiotic and sediment macrofaunal communities were tested for differences between sites near the outfall and controls. Local fish were examined for evidence of histopathological abnormalities. Sediments, fish and gastropods were tested for uptake of sewage as measured by stable isotopes of N and C. Escherichia coli carrying antibiotic resistance determinants were found in water, sediments and wildlife (the filter feeding bivalve Laternula eliptica). Fish (Trematomus bernacchii) within close proximity to the outfall had significantly more severe and greater occurrences of histopathological abnormalities than at controls, consistent with exposure to sewage. There was significant enrichment of 15 N in T. bernacchii and the predatory gastropod Neobuccinum eatoni around the outfall, providing evidence of uptake of sewage. There were significant differences between epibiotic and sediment macrofaunal communities at control and outfall sites (<1.5 km), when sites were separated into groups of similar habitat types. Benthic community composition was also strongly related to habitat and environmental drivers such as sea ice. The combined evidence indicated that the discharge of wastewater from the Davis outfall is causing environmental impacts. These findings suggest that conditions in Antarctic coastal locations, such as Davis, are unlikely to be conducive to initial dilution and rapid dispersal of wastewater as required under the Protocol on Environmental Protection to the Antarctic Treaty. Current minimum requirements for wastewater treatment and disposal in Antarctica are insufficient to ameliorate these risks and are likely to lead to accumulation of contaminants and introduction of non-native microbes and associated genetic elements. This new understanding suggests that modernised approaches to the treatment and disposal of wastewater are required in Antarctica. The most effective solution is advanced levels of wastewater treatment, which are now possible, feasible and a high priority for installation. As a direct outcome of the study, a new advanced treatment system is being installed at Davis, effectively avoiding environmental risks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Footprint of Deepwater Horizon blowout impact to deep-water coral communities

PubMed Central

Fisher, Charles R.; Hsing, Pen-Yuan; Kaiser, Carl L.; Yoerger, Dana R.; Roberts, Harry H.; Shedd, William W.; Cordes, Erik E.; Shank, Timothy M.; Berlet, Samantha P.; Saunders, Miles G.; Larcom, Elizabeth A.; Brooks, James M.

2014-01-01

On April 20, 2010, the Deepwater Horizon (DWH) blowout occurred, releasing more oil than any accidental spill in history. Oil release continued for 87 d and much of the oil and gas remained in, or returned to, the deep sea. A coral community significantly impacted by the spill was discovered in late 2010 at 1,370 m depth. Here we describe the discovery of five previously unknown coral communities near the Macondo wellhead and show that at least two additional coral communities were impacted by the spill. Although the oil-containing flocullent material that was present on corals when the first impacted community was discovered was largely gone, a characteristic patchy covering of hydrozoans on dead portions of the skeleton allowed recognition of impacted colonies at the more recently discovered sites. One of these communities was 6 km south of the Macondo wellhead and over 90% of the corals present showed the characteristic signs of recent impact. The other community, 22 km southeast of the wellhead between 1,850 and 1,950 m depth, was more lightly impacted. However, the discovery of this site considerably extends the distance from Macondo and depth range of significant impact to benthic macrofaunal communities. We also show that most known deep-water coral communities in the Gulf of Mexico do not appear to have been acutely impacted by the spill, although two of the newly discovered communities near the wellhead apparently not impacted by the spill have been impacted by deep-sea fishing operations. PMID:25071200

Best Practices for In-Situ Sediment-Water Incubations with Benthic Landers

NASA Astrophysics Data System (ADS)

Tengberg, Anders; Kononets, Mikhail; Hall, Per; Nilsson, Madeleine; Ekeroth, Nils

2017-04-01

Biological, chemical, physical and geological processes that take place at the seafloor are crucial in influencing and regulating many aquatic environments. One method to estimate exchange rates, fluxes, between the sediment and the overlying water is in-situ sediment-water incubations using autonomous chamber landers. As for all field sampling and measurements best practices methods are needed to obtain high quality data. With experiences form many years usage of the Gothenburg autonomous bottom lander systems this presentation will describe some of the experimental work that has been done with focus on quality control and data evaluation methods.

Swashed away? Storm impacts on sandy beach macrofaunal communities

NASA Astrophysics Data System (ADS)

Harris, Linda; Nel, Ronel; Smale, Malcolm; Schoeman, David

2011-09-01

Storms can have a large impact on sandy shores, with powerful waves eroding large volumes of sand off the beach. Resulting damage to the physical environment has been well-studied but the ecological implications of these natural phenomena are less known. Since climate change predictions suggest an increase in storminess in the near future, understanding these ecological implications is vital if sandy shores are to be proactively managed for resilience. Here, we report on an opportunistic experiment that tests the a priori expectation that storms impact beach macrofaunal communities by modifying natural patterns of beach morphodynamics. Two sites at Sardinia Bay, South Africa, were sampled for macrofauna and physical descriptors following standard sampling methods. This sampling took place five times at three- to four-month intervals between April 2008 and August 2009. The second and last sampling events were undertaken after unusually large storms, the first of which was sufficiently large to transform one site from a sandy beach into a mixed shore for the first time in living memory. A range of univariate (linear mixed-effects models) and multivariate (e.g. non-metric multidimensional scaling, PERMANOVA) methods were employed to describe trends in the time series, and to explore the likelihood of possible explanatory mechanisms. Macrofaunal communities at the dune-backed beach (Site 2) withstood the effects of the first storm but were altered significantly by the second storm. In contrast, macrofauna communities at Site 1, where the supralittoral had been anthropogenically modified so that exchange of sediments with the beach was limited, were strongly affected by the first storm and showed little recovery over the study period. In line with predictions from ecological theory, beach morphodynamics was found to be a strong driver of temporal patterns in the macrofaunal community structure, with the storm events also identified as a significant factor, likely because of their direct effects on beach morphodynamics. Our results also support those of other studies suggesting that developed shores are more impacted by storms than are undeveloped shores. Whilst recognising we cannot generalise too far beyond our limited study, our results contribute to the growing body of evidence that interactions between sea-level rise, increasing storminess and the expansion of anthropogenic modifications to the shoreline will place functional beach ecosystems under severe pressure over the forthcoming decades and we therefore encourage further, formal testing of these concepts.

Gas exchange rates across the sediment-water and air-water interfaces in south San Francisco Bay

USGS Publications Warehouse

Hartman, Blayne; Hammond, Douglas E.

1984-01-01

Radon 222 concentrations in the water and sedimentary columns and radon exchange rates across the sediment-water and air-water interfaces have been measured in a section of south San Francisco Bay. Two independent methods have been used to determine sediment-water exchange rates, and the annual averages of these methods agree within the uncertainty of the determinations, about 20%. The annual average of benthic fluxes from shoal areas is nearly a factor of 2 greater than fluxes from the channel areas. Fluxes from the shoal and channel areas exceed those expected from simple molecular diffusion by factors of 4 and 2, respectively, apparently due to macrofaunal irrigation. Values of the gas transfer coefficient for radon exchange across the air-water interface were determined by constructing a radon mass balance for the water column and by direct measurement using floating chambers. The chamber method appears to yield results which are too high. Transfer coefficients computed using the mass balance method range from 0.4 m/day to 1.8 m/day, with a 6-year average of 1.0 m/day. Gas exchange is linearly dependent upon wind speed over a wind speed range of 3.2–6.4 m/s, but shows no dependence upon current velocity. Gas transfer coefficients predicted from an empirical relationship between gas exchange rates and wind speed observed in lakes and the oceans are within 30% of the coefficients determined from the radon mass balance and are considerably more accurate than coefficients predicted from theoretical gas exchange models.

Effect of physical sediments reworking on hydrocarbon degradation and bacterial community structure in marine coastal sediments.

PubMed

Duran, Robert; Bonin, Patricia; Jezequel, Ronan; Dubosc, Karine; Gassie, Claire; Terrisse, Fanny; Abella, Justine; Cagnon, Christine; Militon, Cecile; Michotey, Valérie; Gilbert, Franck; Cuny, Philippe; Cravo-Laureau, Cristiana

2015-10-01

The present study aimed to examine whether the physical reworking of sediments by harrowing would be suitable for favouring the hydrocarbon degradation in coastal marine sediments. Mudflat sediments were maintained in mesocosms under conditions as closer as possible to those prevailing in natural environments with tidal cycles. Sediments were contaminated with Ural blend crude oil, and in half of them, harrowing treatment was applied in order to mimic physical reworking of surface sediments. Hydrocarbon distribution within the sediment and its removal was followed during 286 days. The harrowing treatment allowed hydrocarbon compounds to penetrate the first 6 cm of the sediments, and biodegradation indexes (such as n-C18/phytane) indicated that biodegradation started 90 days before that observed in untreated control mesocosms. However, the harrowing treatment had a severe impact on benthic organisms reducing drastically the macrofaunal abundance and diversity. In the harrowing-treated mesocosms, the bacterial abundance, determined by 16S rRNA gene Q-PCR, was slightly increased; and terminal restriction fragment length polymorphism (T-RFLP) analyses of 16S rRNA genes showed distinct and specific bacterial community structure. Co-occurrence network and canonical correspondence analyses (CCA) based on T-RFLP data indicated the main correlations between bacterial operational taxonomic units (OTUs) as well as the associations between OTUs and hydrocarbon compound contents further supported by clustered correlation (ClusCor) analysis. The analyses highlighted the OTUs constituting the network structural bases involved in hydrocarbon degradation. Negative correlations indicated the possible shifts in bacterial communities that occurred during the ecological succession.

Benthic foraminiferal biogeography in NW European fjords: A baseline for assessing future change

NASA Astrophysics Data System (ADS)

Murray, John W.; Alve, Elisabeth

2016-11-01

The seaboard extending from northern Svalbard to Scotland is the only region of the world where fjords have been comprehensively studied for their live (stained) benthic foraminiferal faunas. These modern faunas provide essential baseline data for the interpretation of the postglacial and continuing environmental changes in those fjords and this is the first biogeographic synthesis. The data come from the surface sediment assemblages (mainly sampled in the 1990's) from all the available literature. Due to limited information of shallow water assemblages in the north, only the species occurrences in deeper water from below the halocline are considered. Amongst these, only "common species" species occurring in more than one fjord are included. There is a clear pattern of distribution with five groups of taxa: 5 widespread species found throughout the region; 53 species reaching their northern limit; 13 species reaching their southern limit; 11 deep-sea species; 1 recently introduced species. Although there is an abrupt change in temperature from Tanafjorden in northern Norway to Hornsund in southern Svalbard, the faunal change from N to S is progressive throughout the investigated region. The area of overlap of the northern and southern species corresponds with the previously recognised boundary between the Barents Sea Province and the Norwegian Coast Province based on shelf and upper slope invertebrate macrofaunal benthos and plankton. Temperature is the main abiotic control on the distributions. For the fjords which have shallow sills separating them from the open shelf it is likely that most of the foraminiferal colonisers of the deeper fjord basins are sourced from the shelf or slope via propagules. One species has recently been introduced from further south into the southern region probably through the discharge of ballast water from ships. The biodiversity of the pristine Svalbard fjords extends below what is considered to reflect acceptable ecological status for mainland Norway, illustrating the need to introduce new methods to determine possible deviations from the reference conditions as defined in the EU's Water Framework Directive (WFD; 2000/60/EC). Altogether 347 species have so far been recorded in Norwegian waters: 214 in fjords (60 above and 180 below the halocline of which 26 occur both above and below the halocline) and 266 on the shelf and slope (133 of which also occur in fjords).

Two-year temporal response of benthic macrofauna and sediments to hypoxia in a tropical semi-enclosed bay (Cienfuegos, Cuba).

PubMed

Díaz Asencio, Lisbet; Helguera, Yusmila; Fernández-Garcés, Raúl; Gómez-Batista, Miguel; Rosell, Guillermo; Hernández, Yurisbey; Pulido, Anabell; Armenteros, Maickel

2016-03-01

Hypoxia is the depletion of dissolved oxygen below 2 mg O(2)/L. Relatively few studies on hypoxia and its effects on benthic macrofauna have been done in tropical marine ecosystems. This study describes the temporal response of the water column, sediments and macrofauna to seasonal hypoxia in a semi-enclosed bay (Cienfuegos, Caribbean Sea). The Calisito site was sampled monthly from June 2010 until February 2012, yielding 21 sampling times. At each sampling event water and sediment samples were collected for measuring the abiotic variables (temperature, salinity, dissolved oxygen, nutrients, redox potential discontinuity, silt/clay and organic matter content) and macrofauna (abundance and species richness). Temperature and surface salinity followed a typical temporal pattern during the summer/rainy and the winter/dry periods. Salinity stratification occurred in the rainy period, lasting three months in 2010 and six months in 2011. The bottom water dissolved oxygen indicated hypoxic and anoxic events during the wet periods of 2010 and 2011 associated with salinity stratification, low hydrodynamics and oxidation of the accumulated organic matter. Over the study period, 817 individuals were collected and identified. Polychaetes were the dominant group in terms of abundance (57 % of total) followed by mollusks (41%). Hypoxia (and occasionally anoxia) caused strong deleterious effects on the abundance and species richness of macrofaunal communities in the study site. The most abundant polychaetes were opportunistic species with high tolerance to hypoxic conditions: Prionospio steenstrupi, Polydora sp.and Paraprionospio pinnata. Most of them colonized relatively fast once hypoxia ended. Persistent species such as Caecum pulchellum and Parvanachis obesa were present during hypoxia with fluctuating densities and apparently recover to higher abundances when normoxic conditions are re-established. Macoma tenta and Tellina consobrina colonized approximately 1-2 months later than the first polychaete peak during normoxia. Probably, the deleterious effects of hypoxia on the macrofauna were intensified by negative interspecific relationships such as competition by suitable space and predation. The recolonization of macrofauna depended possibly on local transport by currents within the bay because the connection with the Caribbean Sea is relatively limited. In summary, seasonal hypoxia in Cienfuegos Bay influences the water and sediment geochemistry and reduces both the abundance and diversity of macrofauna.

El Niño and similar perturbation effects on the benthos of the Humboldt, California, and Benguela Current upwelling ecosystems

NASA Astrophysics Data System (ADS)

Arntz, W. E.; Gallardo, V. A.; Gutiérrez, D.; Isla, E.; Levin, L. A.; Mendo, J.; Neira, C.; Rowe, G. T.; Tarazona, J.; Wolff, M.

2006-03-01

To a certain degree, Eastern Boundary Current (EBC) ecosystems are similar: Cold bottom water from moderate depths, rich in nutrients, is transported to the euphotic zone by a combination of trade winds, Coriolis force and Ekman transport. The resultant high primary production fuels a rich secondary production in the upper pelagic and nearshore zones, but where O2 exchange is restricted, it creates oxygen minimum zones (OMZs) at shelf and upper slope (Humboldt and Benguela Current) or slope depths (California Current). These hypoxic zones host a specifically adapted, small macro- and meiofauna together with giant sulphur bacteria that use nitrate to oxydise H2S. In all EBC, small polychaetes, large nematodes and other opportunistic benthic species have adapted to the hypoxic conditions and co-exist with sulphur bacteria, which seem to be particularly dominant off Peru and Chile. However, a massive reduction of macrobenthos occurs in the core of the OMZ. In the Humboldt Current area the OMZ ranges between <100 and about 600 m, with decreasing thickness in a poleward direction. The OMZ merges into better oxygenated zones towards the deep sea, where large cold-water mega- and macrofauna occupy a dominant role as in the nearshore strip. The Benguela Current OMZ has a similar upper limit but remains shallower. It also hosts giant sulphur bacteria but little is known about the benthic fauna. However, sulphur eruptions and intense hypoxia might preclude the coexistence of significant mega- und macrobenthos. Conversely, off North America the upper limit of the OMZ is considerably deeper (e.g., 500-600 m off California and Oregon), and the lower boundary may exceed 1000m. The properties described are valid for very cold and cold (La Niña and "normal") ENSO conditions with effective upwelling of nutrient-rich bottom water. During warm (El Niño) episodes, warm water masses of low oxygen concentration from oceanic and equatorial regions enter the upwelling zones, bringing a variety of (sub)tropical immigrants. The autochthonous benthic fauna emigrates to deeper water or poleward, or suffers mortality. However, some local macrofaunal species experience important population proliferations, presumably due to improved oxygenation (in the southern hemisphere), higher temperature tolerance, reduced competition or the capability to use different food. Both these negative and positive effects of El Niño influence local artisanal fisheries and the livelihood of coastal populations. In the Humboldt Current system the hypoxic seafloor at outer shelf depths receives important flushing from the equatorial zone, causing havoc on the sulphur bacteria mats and immediate recolonisation of the sediments by mega- and macrofauna. Conversely, off California, the intruding equatorial water masses appear to have lower oxygen than ambient waters, and may cause oxygen deficiency at upper slope depths. Effects of this change have not been studied in detail, although shrimp and other taxa appear to alter their distribution on the continental margin. Other properties and reactions of the two Pacific EBC benthic ecosystems to El Niño seem to differ, too, as does the overall impact of major episodes (e.g., 1982/1983(1984) vs. 1997/1998). The relation of the "Benguela Niño" to ENSO seems unclear although many Pacific-Atlantic ocean and atmosphere teleconnections have been described. Warm, low-oxygen equatorial water seems to be transported into the upwelling area by similar mechanisms as in the Pacific, but most major impacts on the eukaryotic biota obviously come from other, independent perturbations such as an extreme eutrophication of the sediments ensuing in sulphidic eruptions and toxic algal blooms. Similarities and differences of the Humboldt and California Current benthic ecosystems are discussed with particular reference to ENSO impacts since 1972/73. Where there are data available, the authors include the Benguela Current ecosystem as another important, non-Pacific EBC, which also suffers from the effects of hypoxia.

Macrofaunal community response to extreme concentrations of green macroalgae in a naturally eutrophic estuary

EPA Science Inventory

Increases in the size and frequency of green macroalgal (GMA) blooms in estuarine systems are strongly linked to anthropogenic nutrient enrichment, making it an important concern in managing estuarine water quality worldwide. However, the relationship between macroalgae and anth...

First evaluation of foraminiferal metabarcoding for monitoring environmental impact from an offshore oil drilling site.

PubMed

Laroche, Olivier; Wood, Susanna A; Tremblay, Louis A; Ellis, Joanne I; Lejzerowicz, Franck; Pawlowski, Jan; Lear, Gavin; Atalah, Javier; Pochon, Xavier

2016-09-01

At present, environmental impacts from offshore oil and gas activities are partly determined by measuring changes in macrofauna diversity. Morphological identification of macrofauna is time-consuming, expensive and dependent on taxonomic expertise. In this study, we evaluated the applicability of using foraminiferal-specific metabarcoding for routine monitoring. Sediment samples were collected along distance gradients from two oil platforms off Taranaki (New Zealand) and their physico-chemical properties, foraminiferal environmental DNA/RNA, and macrofaunal composition analyzed. Macrofaunal and foraminiferal assemblages showed similar shifts along impact gradients, but responded differently to environmental perturbations. Macrofauna were affected by hypoxia, whereas sediment grain size appeared to drive shifts in foraminifera. We identified eight foraminiferal molecular operational taxonomic units that have potential to be used as bioindicator taxa. Our results show that metabarcoding represents an effective tool for assessing foraminiferal communities near offshore oil and gas platforms, and that it can be used to complement current monitoring techniques. Copyright © 2016 Elsevier Ltd. All rights reserved.

Limited impact of beach nourishment on macrofaunal recruitment/settlement in a site of community interest in coastal area of the Adriatic Sea (Mediterranean Sea).

PubMed

Danovaro, Roberto; Nepote, Ettore; Martire, Marco Lo; Ciotti, Claudia; De Grandis, Gianluca; Corinaldesi, Cinzia; Carugati, Laura; Cerrano, Carlo; Pica, Daniela; Di Camillo, Cristina Gioia; Dell'Anno, Antonio

2018-03-01

Beach nourishment is a widely utilized solution to counteract the erosion of shorelines, and there is an active discussion on its possible consequences on coastal marine assemblages. We investigated the impact caused by a small-scale beach nourishment carried out in the Western Adriatic Sea on macrofaunal recruitment and post-settlement events. Artificial substrates were deployed in proximity of nourished and non-manipulated beaches and turbidity and sedimentation rates were measured. Our results indicate that sedimentation rates in the impacted site showed a different temporal change compared to the control sites, suggesting potential modifications due to the beach nourishment. The impact site was characterized by subtle changes in terms of polychaete abundance and community structure when compared to controls, possibly due to beach nourishment, although the role of other factors cannot be ruled out. We conclude that small-scale beach nourishments appear to be an eco-sustainable approach to contrast coastal erosion. Copyright © 2018. Published by Elsevier Ltd.

A new macrofaunal limit in the deep biosphere revealed by extreme burrow depths in ancient sediments.

PubMed

Cobain, S L; Hodgson, D M; Peakall, J; Wignall, P B; Cobain, M R D

2018-01-10

Macrofauna is known to inhabit the top few 10s cm of marine sediments, with rare burrows up to two metres below the seabed. Here, we provide evidence from deep-water Permian strata for a previously unrecognised habitat up to at least 8 metres below the sediment-water interface. Infaunal organisms exploited networks of forcibly injected sand below the seabed, forming living traces and reworking sediment. This is the first record that shows sediment injections are responsible for hosting macrofaunal life metres below the contemporaneous seabed. In addition, given the widespread occurrence of thick sandy successions that accumulate in deep-water settings, macrofauna living in the deep biosphere are likely much more prevalent than considered previously. These findings should influence future sampling strategies to better constrain the depth range of infaunal animals living in modern deep-sea sands. One Sentence Summary: The living depth of infaunal macrofauna is shown to reach at least 8 metres in new habitats associated with sand injections.

Endolithic Boring Enhance the Deep-sea Carbonate Lithification on the Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Peng, X.; Xu, H.

2017-12-01

Deep-sea carbonates represent an important type of sedimentary rock due to their effect on the composition of upper oceanic crust and their contribution to deep-sea geochemical cycles. However, the lithification of deep-sea carbonates at the seafloor has remained a mystery for many years. A large lithified carbonate area, characterized by thriving benthic faunas and tremendous amount of endolithic borings, was discovered in 2008, blanketed on the seafloor of ultraslow spreading Southwest Indian Ridge (SWIR). Macrofaunal inhabitants including echinoids, polychaetes, gastropods as well as crustaceans, are abundant in the sample. The most readily apparent feature of the sample is the localized enhancement of density around the borings. The boring features of these carbonate rocks and factors that may enhance deep-sea carbonate lithification are reported. The δ13CPDB values of 46 bulk samples are -0.37 to 1.86‰, while these samples have a relatively narrow δ18OPDB range of 1.35 to 3.79‰. The bulk δ13CPDB values of chalk and gray excrements are positively correlated with bulk δ18OPDB values (r = 0.91) (Fig. 8), which reflects that endolithic boring is possibly a critical factor influence the lithification. We suggest that active boring may trigger the dissolution of the original calcite and thus accelerate deep-sea carbonate lithification on mid-ocean ridges. Our study reports an unfamiliar phenomenon of non-burial carbonate lithification and interested by the observation that it is often associated with boring feature. These carbonate rocks may provide a novel mechanism for deep-sea carbonate lithification at the deep-sea seafloor and also illuminate the geological and biological importance of deep-sea carbonate rocks on mid-ocean ridges.

Ecosystem Services Transcend Boundaries: Estuaries Provide Resource Subsidies and Influence Functional Diversity in Coastal Benthic Communities

PubMed Central

Savage, Candida; Thrush, Simon F.; Lohrer, Andrew M.; Hewitt, Judi E.

2012-01-01

Background Estuaries are highly productive ecosystems that can export organic matter to coastal seas (the ‘outwelling hypothesis’). However the role of this food resource subsidy on coastal ecosystem functioning has not been examined. Methodology/Principal Findings We investigated the influence of estuarine primary production as a resource subsidy and the influence of estuaries on biodiversity and ecosystem functioning in coastal mollusk-dominated sediment communities. Stable isotope values (δ13C, δ15N) demonstrated that estuarine primary production was exported to the adjacent coast and contributed to secondary production up to 4 km from the estuary mouth. Further, isotope signatures of suspension feeding bivalves on the adjacent coast (Dosinia subrosea) closely mirrored the isotope values of the dominant bivalves inside the estuaries (Austrovenus stutchburyi), indicating utilization of similar organic matter sources. However, the food subsidies varied between estuaries; with estuarine suspended particulate organic matter (SPOM) dominant at Tairua estuary, while seagrass and fringing vegetation detritus was proportionately more important at Whangapoua estuary, with lesser contributions of estuarine SPOM. Distance from the estuary mouth and the size and density of large bivalves (Dosinia spp.) had a significant influence on the composition of biological traits in the coastal macrobenthic communities, signaling the potential influence of these spatial subsidies on ecosystem functioning. Conclusions/Significance Our study demonstrated that the locations where ecosystem services like productivity are generated are not necessarily where the services are utilized. Further, we identified indirect positive effects of the nutrient subsidies on biodiversity (the estuarine subsidies influenced the bivalves, which in turn affected the diversity and functional trait composition of the coastal sediment macrofaunal communities). These findings highlight the importance of integrative ecosystem-based management that maintains the connectivity of estuarine and coastal ecosystems. PMID:22880089

Deep-sea benthic megafaunal habitat suitability modelling: A global-scale maximum entropy model for xenophyophores

NASA Astrophysics Data System (ADS)

Ashford, Oliver S.; Davies, Andrew J.; Jones, Daniel O. B.

2014-12-01

Xenophyophores are a group of exclusively deep-sea agglutinating rhizarian protozoans, at least some of which are foraminifera. They are an important constituent of the deep-sea megafauna that are sometimes found in sufficient abundance to act as a significant source of habitat structure for meiofaunal and macrofaunal organisms. This study utilised maximum entropy modelling (Maxent) and a high-resolution environmental database to explore the environmental factors controlling the presence of Xenophyophorea and two frequently sampled xenophyophore species that are taxonomically stable: Syringammina fragilissima and Stannophyllum zonarium. These factors were also used to predict the global distribution of each taxon. Areas of high habitat suitability for xenophyophores were highlighted throughout the world's oceans, including in a large number of areas yet to be suitably sampled, but the Northeast and Southeast Atlantic Ocean, Gulf of Mexico and Caribbean Sea, the Red Sea and deep-water regions of the Malay Archipelago represented particular hotspots. The two species investigated showed more specific habitat requirements when compared to the model encompassing all xenophyophore records, perhaps in part due to the smaller number and relatively more clustered nature of the presence records available for modelling at present. The environmental variables depth, oxygen parameters, nitrate concentration, carbon-chemistry parameters and temperature were of greatest importance in determining xenophyophore distributions, but, somewhat surprisingly, hydrodynamic parameters were consistently shown to have low importance, possibly due to the paucity of well-resolved global hydrodynamic datasets. The results of this study (and others of a similar type) have the potential to guide further sample collection, environmental policy, and spatial planning of marine protected areas and industrial activities that impact the seafloor, particularly those that overlap with aggregations of these conspicuously large single-celled eukaryotes.

The importance of benchmarking habitat structure and composition for understanding the extent of fishing impacts in soft sediment ecosystems

NASA Astrophysics Data System (ADS)

Handley, Sean J.; Willis, Trevor J.; Cole, Russell G.; Bradley, Anna; Cairney, Daniel J.; Brown, Stephen N.; Carter, Megan E.

2014-02-01

Trawling and dredge fisheries remove vulnerable fauna, homogenise sediments and assemblages, and break down biogenic habitats, but the full extent of these effects can be difficult to quantify in the absence of adequate control sites. Our study utilised rare control sites containing biogenic habitat, the Separation Point exclusion zone, formally protected for 28 years, as the basis for assessing the degree of change experienced by adjacent areas subject to benthic fishing. Sidescan sonar surveys verified that intensive trawling and dredging occurred in areas adjacent to, but not inside, the exclusion area. We compared sediment composition, biogenic cover, macrofaunal assemblages, biomass, and productivity of the benthos, inside and outside the exclusion zone. Disturbed sites were dominated by fine mud, with little or no shell-gravel, reduced number of species, and loss of large bodied animals, with concomitant reductions in biomass and productivity. At protected sites, large, rarer molluscs were more abundant and contributed the most to size-based estimates of productivity and biomass. Functional changes in fished assemblages were consistent with previously reported relative increases in scavengers, predators and deposit feeders at the expense of filter feeders and a grazer. We propose that the colonisation of biogenic species in protected sites was contingent on the presence of shell-gravel atop these soft sediments. The process of sediment homogenisation by bottom fishing and elimination of shell-gravels from surficial sediments appeared to have occurred over decades - a ‘shifting baseline’. Therefore, benchmarking historical sediment structure at control site like the Separation Point exclusion zone is necessary to determine the full extent of physical habitat change wrought by contact gears on sheltered soft sediment habitats to better underpin appropriate conservation, restoration or fisheries management goals.

The ecology of xenophyophores (Protista) on eastern Pacific seamounts

NASA Astrophysics Data System (ADS)

Levin, Lisa A.; Thomas, Cynthia L.

1988-12-01

Large, agglutinating protozoans of the class Xenophyophorea are the dominant epifaunal organisms on soft and hard substrates of many bathyal seamounts in the eastern Pacific Ocean off Mexico. Observations made with the submersible Alvin and remotely towed camera sleds on 17 seamounts at 31°, 20°, 13° and 10°N revealed more than ten distinct xenophyophore test morphologies. Most of these appear to represent previously undescribed species. Reticulate forms are numerically dominant at 20°, 13° and 10°N. Xenophyophore abundances increase with decreasing latitude, being rare at 30°N, present at densities of 0.1-1.0 m -2 at 20° and 13°N and often exceeding 1.0 m -2 at 10°N, occasionally reaching 10-18 m -2. Highest concentrations are observed on caldera floors near the base of steep caldera walls, at depths between 1700 and 2500 m. Most individuals select sand-size pelagic foraminiferan tests (63-500 μm) and exclude pebble, silt and clay-size particles for test construction. Xenophyophore on seamounts modify the structure of metazoan communities and may play a role in maintenance of infaunal diversity. Twenty-seven xenophyophore tests were found to provide habitat for 16 major macrofaunal taxa (152 individuals) and three meiofaunal taxa (333 individuals). The presence of xenophyophores also enhances the abundance of isopods, tanaids, ophiuroids, nematodes and harpacticoid copepods dwelling in sediments surrounding the tests. Mobile megafauna are attracted to sediment beneath and adjacent to xenophyophores. We suggest that xenophyophores, which are abundant on many topographic features in deep water (e.g. guyots, trenches, canyons and continental slopes), are a functionally important component of deep-sea benthic communities and require further autecological and synecological investigation.

Anthropogenic disturbance and biodiversity of marine benthic communities in Antarctica: a regional comparison.

PubMed

Stark, Jonathan S; Kim, Stacy L; Oliver, John S

2014-01-01

The impacts of two Antarctic stations in different regions, on marine sediment macrofaunal communities were compared: McMurdo, a very large station in the Ross Sea; and Casey, a more typical small station in East Antarctica. Community structure and diversity were compared along a gradient of anthropogenic disturbance from heavily contaminated to uncontaminated locations. We examined some of the inherent problems in comparing data from unrelated studies, such as different sampling methods, spatial and temporal scales of sampling and taxonomic uncertainty. These issues generated specific biases which were taken into account when interpreting patterns. Control sites in the two regions had very different communities but both were dominated by crustaceans. Community responses to anthropogenic disturbance (sediment contamination by metals, oils and sewage) were also different. At McMurdo the proportion of crustaceans decreased in disturbed areas and polychaetes became dominant, whereas at Casey, crustaceans increased in response to disturbance, largely through an increase in amphipods. Despite differing overall community responses there were some common elements. Ostracods, cumaceans and echinoderms were sensitive to disturbance in both regions. Capitellid, dorvelleid and orbiniid polychaetes were indicative of disturbed sites. Amphipods, isopods and tanaids had different responses at each station. Biodiversity and taxonomic distinctness were significantly lower at disturbed locations in both regions. The size of the impact, however, was not related to the level of contamination, with a larger reduction in biodiversity at Casey, the smaller, less polluted station. The impacts of small stations, with low to moderate levels of contamination, can thus be as great as those of large or heavily contaminated stations. Regional broad scale environmental influences may be important in determining the composition of communities and thus their response to disturbance, but there are some generalizations regarding responses which will aid future management of stations.

Environmental factors controlling macrofaunal assemblages on six microtidal beaches of the Ligurian Sea (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Covazzi Harriague, Anabella; Albertelli, Giancarlo

2007-06-01

Six microtidal beaches along the Ligurian coast (NW Mediterranean, Italy) were sampled in order to study their macrofaunal assemblages. All six beaches are subject to heavy tourism in the swimming season and three were subject to nourishment activities during the study period (May 2000). The beaches of Lavagna, Varazze and Pietra Ligure were sampled three times: before the nourishment and the onset of the swimming season (March 2000), after the nourishment (June 2000) and at the end of the swimming season (October 2000). The beaches of Varigotti, Albisola and Loano were sampled twice: before and after the swimming season (March and October 2000, respectively). Sampling was performed along two transects (T1 and T2), about 500 m apart, each transect having three sampling stations: one placed in the swash zone, one in the surf zone and one in the subtidal zone (depth of 3-5 m), in order to verify how far the nourishment material reached. The beaches were characterised by coarse sediments that became finer towards the sub-littoral station. The Beach Deposit Index and Beach Index classified the beaches as reflective (Lavagna, Varazze, Albisola and Varigotti) or intermediate (Pietra Ligure and Loano). Species richness showed a clearly increasing pattern from the swash zone (average 7) to the subtidal zone (average 103). The beach communities were dominated by polychaetes, in particular Saccocirrus papillocercus, which was mainly responsible for the dissimilarity between the beach and subtidal stations. The highest abundance was observed at the surf station (average 118.6 ind. m -2) and the lowest at the subtidal station (average 82.1 ind. m -2). The sediment composition and macrofaunal assemblages were not affected by the beach nourishment. The beach communities responded to different environmental descriptors: species richness seemed to be governed by environmental harshness, while abundance seemed to be linked to the degree of homogeneity of the sediments and the quality of the food supply.

Habitat segregation mediates predation by the benthic fish Cottus gobio on the exotic amphipod species Gammarus roeseli

NASA Astrophysics Data System (ADS)

Kaldonski, Nicolas; Lagrue, Clément; Motreuil, Sébastien; Rigaud, Thierry; Bollache, Loïc

2008-09-01

Predation is often considered as one of the most important biotic factor determining the success of exotic species. The freshwater amphipod Gammarus roeseli has widely colonized Western Europe, where it is frequently found in sympatry with the native species ( Gammarus pulex). Previous laboratory experiments revealed that G. roeseli may have an advantage over G. pulex through differential predation by native fish (brown trout). Morphological anti-predator defences (spines) were found responsible for lower rates of predation on the invasive G. roeseli. Here, using both field surveys and laboratory experiments, we tested if a differential of predation exists with other fish predators naturally encountered by gammarids. The main predators present in our field site were nocturnal benthic feeders (mainly bullheads, Cottus gobio). Fish diet analysis showed that, compared to its global availability in the river, G. roeseli was less consumed than G. pulex. In the field, however, G. roeseli was found mainly in the aquatic vegetation whereas G. pulex was found in all habitat types. Laboratory experiments in microcosms revealed that G. roeseli was less prone to predation by C. gobio only when vegetation was present. Depending on the type of predator, the differential of predation could therefore be mediated by antipredator behaviour, and a better usage of refuges, rather than by morphological defences.

Sediment chemoautotrophy in the coastal ocean

NASA Astrophysics Data System (ADS)

Vasquez-Cardenas, Diana; Meysman, Filip J. R.; van Breugel, Peter; Boschker, Henricus T. S.

2016-04-01

A key process in the biogeochemistry of coastal sediments is the reoxidation of reduced intermediates formed during anaerobic mineralization which in part is performed by chemoautotrophic micro-organisms. These microbes fix inorganic carbon using the energy derived from reoxidation reactions and in doing so can fix up to 32% of the CO2 released by mineralization. However the importance and distribution of chemoautotrophy has not been systematically investigated in these environments. To address these issues we surveyed nine coastal sediments by means of bacterial biomarker analysis (phospholipid derived fatty acids) combined with stable isotope probing (13C-bicarbonate) which resulted in an almost doubling of the number of observations on coastal sedimentary chemoautotrophy. Firstly, sediment chemoautotrophy rates from this study and rates compiled from literature (0.07 to 36 mmol C m-2 d-1) showed a power-law relation with benthic oxygen uptake (3.4 to 192 mmol O2 m-2 d-1). Benthic oxygen uptake was used as a proxy for carbon mineralization to calculate the ratio of the CO2 fixed by chemoautotrophy over the total CO2 released through mineralization. This CO2 efficiency was 3% in continental shelf, 9% in nearshore and 21% in salt marsh sediments. These results suggest that chemoautotrophy plays an important role in C-cycling in reactive intertidal sediments such as salt marshes rather than in the organic-poor, permeable continental shelf sediments. Globally in the coastal ocean our empirical results show that chemoautotrophy contributes ˜0.05 Pg C y-1 which is four times less than previous estimates. Secondly, five coastal sediment regimes were linked to the depth-distribution of chemoautotrophy: 1) permeable sediments dominated by advective porewater transport, 2) bioturbated sediments, and cohesive sediments dominated by diffusive porewater transport characterized by either 3) canonical sulfur oxidation, 4) nitrate-storing Beggiatoa, or 5) electrogenic sulfur oxidation. Sediments with an O2-H2S interface exhibited highest chemoautotrophy activity in the top centimeter via canonical sulfur oxidation, whereas in the presence of electrogenic sulfur oxidation a uniform distribution of chemoautotrophy throughout the top centimeters of the sediment was evidenced. Lowest dark carbon fixation was found in permeable advective-driven sediments with deep oxygen penetration resulting in higher subsurface than surface activity. Hence, the depth-distribution of chemoautotrophy in coastal sediments varies due to several biogeochemical characteristics such as grain size, organic carbon content, presence of filamentous sulfur oxidizing bacteria, and macrofaunal activity.

Faunal responses to oxygen gradients on the Pakistan margin: A comparison of foraminiferans, macrofauna and megafauna

NASA Astrophysics Data System (ADS)

Gooday, A. J.; Levin, L. A.; Aranda da Silva, A.; Bett, B. J.; Cowie, G. L.; Dissard, D.; Gage, J. D.; Hughes, D. J.; Jeffreys, R.; Lamont, P. A.; Larkin, K. E.; Murty, S. J.; Schumacher, S.; Whitcraft, C.; Woulds, C.

2009-03-01

The Pakistan Margin is characterised by a strong mid-water oxygen minimum zone (OMZ) that intercepts the seabed at bathyal depths (150-1300 m). We investigated whether faunal abundance and diversity trends were similar among protists (foraminiferans and gromiids), metazoan macrofauna and megafauna along a transect (140-1850 m water depth) across the OMZ during the 2003 intermonsoon (March-May) and late/post-monsoon (August-October) seasons. All groups exhibited some drop in abundance in the OMZ core (250-500 m water depth; O 2: 0.10-0.13 mL L -1=4.46-5.80 μM) but to differing degrees. Densities of foraminiferans >63 μm were slightly depressed at 300 m, peaked at 738 m, and were much lower at deeper stations. Foraminiferans >300 μm were the overwhelmingly dominant macrofaunal organisms in the OMZ core. Macrofaunal metazoans reached maximum densities at 140 m depth, with additional peaks at 850, 940 and 1850 m where foraminiferans were less abundant. The polychaete Linopherus sp. was responsible for a macrofaunal biomass peak at 950 m. Apart from large swimming animals (fish and natant decapods), metazoan megafauna were absent between 300 and 900 m (O 2 <0.14-0.15 mL L -1=6.25-6.69 μM) but were represented by a huge, ophiuroid-dominated abundance peak at 1000 m (O 2 ˜0.15-0.18 mL L -1=6.69-8.03 μM). Gromiid protists were confined largely to depths below 1150 m (O 2 >0.2 mL L -1=8.92 μM). The progressively deeper abundance peaks for foraminiferans (>63 μm), Linopherus sp. and ophiuroids probably represent lower OMZ boundary edge effects and suggest a link between body size and tolerance of hypoxia. Macro- and megafaunal organisms collected between 800 and 1100 m were dominated by a succession of different taxa, indicating that the lower part of the OMZ is also a region of rapid faunal change. Species diversity was depressed in all groups in the OMZ core, but this was much more pronounced for macrofauna and megafauna than for foraminiferans. Oxygen levels strongly influenced the taxonomic composition of all faunal groups. Calcareous foraminiferans dominated the seasonally and permanently hypoxic sites (136-300 m); agglutinated foraminiferans were relatively more abundant at deeper stations where oxygen concentrations were >0.13 mL L -1(=5.80 μM). Polychaetes were the main macrofaunal taxon within the OMZ; calcareous macrofauna and megafauna (molluscs and echinoderms) were rare or absent where oxygen levels were lowest. The rarity of larger animals between 300 and 700 m on the Pakistan Margin, compared with the abundant macrofauna in the OMZ core off Oman, is the most notable contrast between the two sides of the Arabian Sea. This difference probably reflects the slightly higher oxygen levels and better food quality on the western side.

Linear alkylbenzene sulfonates (LAS) in sewage sludges, soils and sediments: analytical determination and environmental safety considerations.

PubMed

De Henau, H; Mathijs, E; Hopping, W D

1986-01-01

Linear Alkylbenzenesulphonates (LAS), a major anionic surfactant used in laundry products, can be measured specifically in the environment by instrumental analysis. In addition to a desulphonation-gas chromatography approach, a method based on high performance liquid chromatography has been developed. The main features of the methods are outlined, and LAS concentrations measured in sewage sludge, sediments and sludge amended soils are reported. Knowledge of usage volumes, sewage treatment practices and environmental transport and transformation mechanisms has been used to predict concentrations of LAS. These calculated concentrations were found to agree well with those actually measured in the environment. Both measured and calculated ambient concentrations of LAS are below those which could produce potentially adverse effects in representative surface water, benthic and terrestrial organisms.

Microbial methanogenesis in the sulfate-reducing zone of sediments in the Eckernförde Bay, SW Baltic Sea

NASA Astrophysics Data System (ADS)

Maltby, Johanna; Steinle, Lea; Löscher, Carolin R.; Bange, Hermann W.; Fischer, Martin A.; Schmidt, Mark; Treude, Tina

2018-01-01

Benthic microbial methanogenesis is a known source of methane in marine systems. In most sediments, the majority of methanogenesis is located below the sulfate-reducing zone, as sulfate reducers outcompete methanogens for the major substrates hydrogen and acetate. The coexistence of methanogenesis and sulfate reduction has been shown before and is possible through the usage of noncompetitive substrates by methanogens such as methanol or methylated amines. However, knowledge about the magnitude, seasonality, and environmental controls of this noncompetitive methane production is sparse. In the present study, the presence of methanogenesis within the sulfate reduction zone (SRZ methanogenesis) was investigated in sediments (0-30 cm below seafloor, cm b.s.f.) of the seasonally hypoxic Eckernförde Bay in the southwestern Baltic Sea. Water column parameters such as oxygen, temperature, and salinity together with porewater geochemistry and benthic methanogenesis rates were determined in the sampling area Boknis Eck quarterly from March 2013 to September 2014 to investigate the effect of seasonal environmental changes on the rate and distribution of SRZ methanogenesis, to estimate its potential contribution to benthic methane emissions, and to identify the potential methanogenic groups responsible for SRZ methanogenesis. The metabolic pathway of methanogenesis in the presence or absence of sulfate reducers, which after the addition of a noncompetitive substrate was studied in four experimental setups: (1) unaltered sediment batch incubations (net methanogenesis), (2) 14C-bicarbonate labeling experiments (hydrogenotrophic methanogenesis), (3) manipulated experiments with the addition of either molybdate (sulfate reducer inhibitor), 2-bromoethanesulfonate (methanogen inhibitor), or methanol (noncompetitive substrate, potential methanogenesis), and (4) the addition of 13C-labeled methanol (potential methylotrophic methanogenesis). After incubation with methanol, molecular analyses were conducted to identify key functional methanogenic groups during methylotrophic methanogenesis. To also compare the magnitudes of SRZ methanogenesis with methanogenesis below the sulfate reduction zone (> 30 cm b.s.f.), hydrogenotrophic methanogenesis was determined by 14C-bicarbonate radiotracer incubation in samples collected in September 2013.SRZ methanogenesis changed seasonally in the upper 30 cm b.s.f. with rates increasing from March (0.2 nmol cm-3 d-1) to November (1.3 nmol cm-3 d-1) 2013 and March (0.2 nmol cm-3 d-1) to September (0.4 nmol cm-3 d-1) 2014. Its magnitude and distribution appeared to be controlled by organic matter availability, C / N, temperature, and oxygen in the water column, revealing higher rates in the warm, stratified, hypoxic seasons (September-November) compared to the colder, oxygenated seasons (March-June) of each year. The majority of SRZ methanogenesis was likely driven by the usage of noncompetitive substrates (e.g., methanol and methylated compounds) to avoid competition with sulfate reducers, as was indicated by the 1000-3000-fold increase in potential methanogenesis activity observed after methanol addition. Accordingly, competitive hydrogenotrophic methanogenesis increased in the sediment only below the depth of sulfate penetration (> 30 cm b.s.f.). Members of the family Methanosarcinaceae, which are known for methylotrophic methanogenesis, were detected by PCR using Methanosarcinaceae-specific primers and are likely to be responsible for the observed SRZ methanogenesis.The present study indicates that SRZ methanogenesis is an important component of the benthic methane budget and carbon cycling in Eckernförde Bay. Although its contributions to methane emissions from the sediment into the water column are probably minor, SRZ methanogenesis could directly feed into methane oxidation above the sulfate-methane transition zone.

Destabilization of Cohesive Intertidal Sediments by Infauna

NASA Astrophysics Data System (ADS)

de Deckere, E. M. G. T.; Tolhurst, T. J.; de Brouwer, J. F. C.

2001-11-01

Bioturbation activity was reduced in four plots on an intertidal mudflat in the Humber estuary (UK) during 4 days, by spraying the sediment with an insecticide, namely vydate. Macrofaunal, especially Nereis diversicolor and oligochaeta, and meiofaunal densities decreased, while the diatom biomass did not change. This resulted in a 300% increase in sediment stability, caused by a reduction in bioturbation and grazing pressure and a decrease in the water content.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brook, I.M.

Five Thalassia communities with high blade density (greater than 3,000 blades/m/sup 2/) were sampled by suction dredge in April 1973. Four sites were in south Biscayne Bay, and one was at Murray Key in the Everglades National Park on the southwest coast of Florida. Macrofaunal abundance ranged from 292 to 10,728 individuals/m/sup 2/. It is postulated that a high standing crop of seagrass may not be the primary determining factor in faunal abundance.

Influence of macrofaunal assemblages and environmental heterogeneity on microphytobenthic production in experimental systems

PubMed Central

Dyson, Kirstie E; Bulling, Mark T; Solan, Martin; Hernandez-Milian, Gema; Raffaelli, David G; White, Piran C.L; Paterson, David M

2007-01-01

Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment–water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production. PMID:17698480

Influence of macrofaunal assemblages and environmental heterogeneity on microphytobenthic production in experimental systems.

PubMed

Dyson, Kirstie E; Bulling, Mark T; Solan, Martin; Hernandez-Milian, Gema; Raffaelli, David G; White, Piran C L; Paterson, David M

2007-10-22

Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment-water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production.

Climate change effects on macrofaunal litter decomposition: the interplay of temperature, body masses and stoichiometry.

PubMed

Ott, David; Rall, Björn C; Brose, Ulrich

2012-11-05

Macrofauna invertebrates of forest floors provide important functions in the decomposition process of soil organic matter, which is affected by the nutrient stoichiometry of the leaf litter. Climate change effects on forest ecosystems include warming and decreasing litter quality (e.g. higher C : nutrient ratios) induced by higher atmospheric CO(2) concentrations. While litter-bag experiments unravelled separate effects, a mechanistic understanding of how interactions between temperature and litter stoichiometry are driving decomposition rates is lacking. In a laboratory experiment, we filled this void by quantifying decomposer consumption rates analogous to predator-prey functional responses that include the mechanistic parameters handling time and attack rate. Systematically, we varied the body masses of isopods, the environmental temperature and the resource between poor (hornbeam) and good quality (ash). We found that attack rates increased and handling times decreased (i) with body masses and (ii) temperature. Interestingly, these relationships interacted with litter quality: small isopods possibly avoided the poorer resource, whereas large isopods exhibited increased, compensatory feeding of the poorer resource, which may be explained by their higher metabolic demands. The combination of metabolic theory and ecological stoichiometry provided critically important mechanistic insights into how warming and varying litter quality may modify macrofaunal decomposition rates.

Modeling Benthic Sediment Processes to Predict Water ...

EPA Pesticide Factsheets

The benthic sediment acts as a huge reservoir of particulate and dissolved material (within interstitial water) which can contribute to loading of contaminants and nutrients to the water column. A benthic sediment model is presented in this report to predict spatial and temporal benthic fluxes of nutrients and chemicals in Narragansett Bay. A benthic sediment model is presented in this report to identify benthic flux into the water column in Narragansett Bay. Benthic flux is essential to properly model water quality and ecology in estuarine and coastal systems.

Ferrous iron- and ammonium-rich diffuse vents support habitat-specific communities in a shallow hydrothermal field off the Basiluzzo Islet (Aeolian Volcanic Archipelago).

PubMed

Bortoluzzi, G; Romeo, T; La Cono, V; La Spada, G; Smedile, F; Esposito, V; Sabatino, G; Di Bella, M; Canese, S; Scotti, G; Bo, M; Giuliano, L; Jones, D; Golyshin, P N; Yakimov, M M; Andaloro, F

2017-09-01

Ammonium- and Fe(II)-rich fluid flows, known from deep-sea hydrothermal systems, have been extensively studied in the last decades and are considered as sites with high microbial diversity and activity. Their shallow-submarine counterparts, despite their easier accessibility, have so far been under-investigated, and as a consequence, much less is known about microbial communities inhabiting these ecosystems. A field of shallow expulsion of hydrothermal fluids has been discovered at depths of 170-400 meters off the base of the Basiluzzo Islet (Aeolian Volcanic Archipelago, Southern Tyrrhenian Sea). This area consists predominantly of both actively diffusing and inactive 1-3 meters-high structures in the form of vertical pinnacles, steeples and mounds covered by a thick orange to brown crust deposits hosting rich benthic fauna. Integrated morphological, mineralogical, and geochemical analyses revealed that, above all, these crusts are formed by ferrihydrite-type Fe 3+ oxyhydroxides. Two cruises in 2013 allowed us to monitor and sampled this novel ecosystem, certainly interesting in terms of shallow-water iron-rich site. The main objective of this work was to characterize the composition of extant communities of iron microbial mats in relation to the environmental setting and the observed patterns of macrofaunal colonization. We demonstrated that iron-rich deposits contain complex and stratified microbial communities with a high proportion of prokaryotes akin to ammonium- and iron-oxidizing chemoautotrophs, belonging to Thaumarchaeota, Nitrospira, and Zetaproteobacteria. Colonizers of iron-rich mounds, while composed of the common macrobenthic grazers, predators, filter-feeders, and tube-dwellers with no representatives of vent endemic fauna, differed from the surrounding populations. Thus, it is very likely that reduced electron donors (Fe 2+ and NH 4 + ) are important energy sources in supporting primary production in microbial mats, which form a habitat-specific trophic base of the whole Basiluzzo hydrothermal ecosystem, including macrobenthic fauna. © 2017 John Wiley & Sons Ltd.

Biodiversity of the Deep-Sea Continental Margin Bordering the Gulf of Maine (NW Atlantic): Relationships among Sub-Regions and to Shelf Systems

PubMed Central

Kelly, Noreen E.; Shea, Elizabeth K.; Metaxas, Anna; Haedrich, Richard L.; Auster, Peter J.

2010-01-01

Background In contrast to the well-studied continental shelf region of the Gulf of Maine, fundamental questions regarding the diversity, distribution, and abundance of species living in deep-sea habitats along the adjacent continental margin remain unanswered. Lack of such knowledge precludes a greater understanding of the Gulf of Maine ecosystem and limits development of alternatives for conservation and management. Methodology/Principal Findings We use data from the published literature, unpublished studies, museum records and online sources, to: (1) assess the current state of knowledge of species diversity in the deep-sea habitats adjacent to the Gulf of Maine (39–43°N, 63–71°W, 150–3000 m depth); (2) compare patterns of taxonomic diversity and distribution of megafaunal and macrofaunal species among six distinct sub-regions and to the continental shelf; and (3) estimate the amount of unknown diversity in the region. Known diversity for the deep-sea region is 1,671 species; most are narrowly distributed and known to occur within only one sub-region. The number of species varies by sub-region and is directly related to sampling effort occurring within each. Fishes, corals, decapod crustaceans, molluscs, and echinoderms are relatively well known, while most other taxonomic groups are poorly known. Taxonomic diversity decreases with increasing distance from the continental shelf and with changes in benthic topography. Low similarity in faunal composition suggests the deep-sea region harbours faunal communities distinct from those of the continental shelf. Non-parametric estimators of species richness suggest a minimum of 50% of the deep-sea species inventory remains to be discovered. Conclusions/Significance The current state of knowledge of biodiversity in this deep-sea region is rudimentary. Our ability to answer questions is hampered by a lack of sufficient data for many taxonomic groups, which is constrained by sampling biases, life-history characteristics of target species, and the lack of trained taxonomists. PMID:21124960

Synthesis of benthic flux components in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil

NASA Astrophysics Data System (ADS)

King, J. N.

2012-12-01

The primary objective of this work is to synthesize components of benthic flux in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil. Specifically, the component of benthic discharge flux forced by the terrestrial hydraulic gradient is 0.8 m3 d-1; components of benthic discharge and recharge flux associated with the groundwater tidal prism are both 2.1 m3 d-1; components of benthic discharge and recharge flux forced by surface-gravity wave setup are both 6.3 m3 d-1; the component of benthic discharge flux that transports radium-228 is 350 m3 d-1; and components of benthic discharge and recharge flux forced by surface-gravity waves propagating over a porous medium are both 1400 m3 d-1. (All models are normalized per meter shoreline.) Benthic flux is a function of components forced by individual mechanisms and nonlinear interactions that exist between components. Constructive and destructive interference may enhance or diminish the contribution of benthic flux components. It may not be possible to model benthic flux by summing component magnitudes. Geochemical tracer techniques may not accurately model benthic discharge flux or submarine groundwater discharge (SGD). A conceptual model provides a framework on which to quantitatively characterize benthic discharge flux and SGD with a multifaceted approach.

Synthesis of benthic flux components in the Patos Lagooncoastal zone, Rio Grande do Sul, Brazil

USGS Publications Warehouse

King, Jeffrey N.

2012-01-01

The primary objective of this work is to synthesize components of benthic flux in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil. Specifically, the component of benthic discharge flux forced by the terrestrial hydraulic gradient is 0.8 m3 d-1; components of benthic discharge and recharge flux associated with the groundwater tidal prism are both 2.1 m3 d-1; components of benthic discharge and recharge flux forced by surface-gravity wave setup are both 6.3 m3 d-1; the component of benthic discharge flux that transports radium-228 is 350 m3 d-1; and components of benthic discharge and recharge flux forced by surface-gravity waves propagating over a porous medium are both 1400 m3 d-1. (All models are normalized per meter shoreline.) Benthic flux is a function of components forced by individual mechanisms and nonlinear interactions that exist between components. Constructive and destructive interference may enhance or diminish the contribution of benthic flux components. It may not be possible to model benthic flux by summing component magnitudes. Geochemical tracer techniques may not accurately model benthic discharge flux or submarine groundwater discharge (SGD). A conceptual model provides a framework on which to quantitatively characterize benthic discharge flux and SGD with a multifaceted approach.

Assessing the status of sediment toxicity and macroinvertebrate communities in the Eighteenmile Creek Area of Concern, New York

USGS Publications Warehouse

George, Scott D.; Duffy, Brian T.; Baldigo, Barry P.

2017-01-01

In 1972, the governments of Canada and the United States committed to restoring the physical, chemical, and biological integrity of the Laurentian Great Lakes under the Great Lakes Water Quality Agreement. Through this framework, the downstream-most section of Eighteenmile Creek, a tributary to the south shore of Lake Ontario in New York, was designated as an Area of Concern (AOC) because water quality and bed sediments were contaminated by past industrial and municipal discharges, waste disposal, and pesticide usage. Five beneficial use impairments (BUIs) have been identified in the AOC including the degradation of the “benthos”, or the benthic macroinvertebrate community. This investigation used sediment toxicity testing and macroinvertebrate community assessments to determine if the toxicity of bed sediments in the AOC differed from that of an unimpacted reference stream. Results from 10-day toxicity tests indicated that survival and growth of the dipteran Chironomus dilutus and the amphipod Hyalella azteca did not differ significantly between sediments from the AOC and reference area. Analyses of benthic macroinvertebrate community integrity and structure also indicated that macroinvertebrate communities, while impacted across most sites on both streams, were generally similar between the AOC and reference area. Despite these findings, the upstream-most AOC site consistently scored poorly in all analyses, which suggests that localized sediment toxicity may exist in the AOC, even if large scale differences between the AOC and a comparable reference stream are minimal.

Comparative analysis of different survey methods for monitoring fish assemblages in coastal habitats.

PubMed

Baker, Duncan G L; Eddy, Tyler D; McIver, Reba; Schmidt, Allison L; Thériault, Marie-Hélène; Boudreau, Monica; Courtenay, Simon C; Lotze, Heike K

2016-01-01

Coastal ecosystems are among the most productive yet increasingly threatened marine ecosystems worldwide. Particularly vegetated habitats, such as eelgrass (Zostera marina) beds, play important roles in providing key spawning, nursery and foraging habitats for a wide range of fauna. To properly assess changes in coastal ecosystems and manage these critical habitats, it is essential to develop sound monitoring programs for foundation species and associated assemblages. Several survey methods exist, thus understanding how different methods perform is important for survey selection. We compared two common methods for surveying macrofaunal assemblages: beach seine netting and underwater visual census (UVC). We also tested whether assemblages in shallow nearshore habitats commonly sampled by beach seines are similar to those of nearby eelgrass beds often sampled by UVC. Among five estuaries along the Southern Gulf of St. Lawrence, Canada, our results suggest that the two survey methods yield comparable results for species richness, diversity and evenness, yet beach seines yield significantly higher abundance and different species composition. However, sampling nearshore assemblages does not represent those in eelgrass beds despite considerable overlap and close proximity. These results have important implications for how and where macrofaunal assemblages are monitored in coastal ecosystems. Ideally, multiple survey methods and locations should be combined to complement each other in assessing the entire assemblage and full range of changes in coastal ecosystems, thereby better informing coastal zone management.

Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study.

PubMed

Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh D; Liu, Zhengwen

2015-03-01

Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems.

Diachronous benthic δ18O responses during late Pleistocene terminations

NASA Astrophysics Data System (ADS)

Lisiecki, Lorraine E.; Raymo, Maureen E.

2009-09-01

Benthic δ18O is often used as a stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. However, Skinner and Shackleton (2005) found that the timing of benthic δ18O change at the last termination differed by 3900 years between one Atlantic site and one Pacific site. These results suggest that benthic δ18O change may not always accurately record the timing of deglaciation. We compare benthic δ18O records from 20 Atlantic sites and 14 Pacific sites to evaluate systematic differences in the timing of terminations in benthic δ18O. Analysis of sedimentation rates derived from the alignment of benthic δ18O suggests a statistically significant Atlantic lead over Pacific benthic δ18O change during the last six terminations. We estimate an average Pacific benthic δ18O lag of 1600 years for Terminations 1-5, slightly larger than the delay expected from ocean mixing rates given that most glacial meltwater probably enters the North Atlantic. We additionally find evidence of ˜4000-year Pacific δ18O lags at approximately 128 ka and 330 ka, suggesting that stratigraphic correlation of δ18O has the potential to generate age model errors of several thousand years during terminations. A simple model demonstrates that these lags can be generated by diachronous temperature changes and do not require slower circulation rates. Most importantly, diachronous benthic δ18O responses must be taken into account when comparing Atlantic and Pacific benthic δ18O records or when using benthic δ18O records as a proxy for the timing of ice volume change.

Benthic Macroinvertebrate Assemblages and Environmental Correlates in Springs of the Ridge and Valley Province

EPA Science Inventory

Springs are unique features in the landscape that provide important habitat for benthic invertebrates, yet there are few studies characterizing the distribution of benthic macro invertebrates in springs. Benthic macroinvertebrate and water quality data were collected at 35 spring...

Environmental Support for Project WEAP (Weapons Environmental Acoustic Program), East of Montauk Point, New York, 7-28 May 1982.

DTIC Science & Technology

1983-10-01

scatterer of acoustic energy. During May, the * The objective of Project WEAP (Weapons sound speed gradient would be slightly Environmental Acoustics...remotely collected box site the experiment in a homogeneous cores for small macrofaunal animals. area or at least in an area where heter- Megafauna must...variety of sediment types. bation by both megafauna and macrofauna. DThis data may be required to understand During or after the acoustic experiment, the

APPLICATION OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

EPA Science Inventory

The Chesapeake Bay Benthic Index of Biotic Integrity (B-161) and the Environmental Monitoring and Assessment Program's Virginian Province Benthic Index (EMAP-VP BI) were applied to 294 sampling events in Chesapeake Bay and the results were compared. These benthic indices are inte...

COMPARISON OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

EPA Science Inventory

The Chesapeake Benthic Index of Biotic Integrity (B-IBI) and the EMAP-VP Benthic Index were applied to samples from 239 sites in Chesapeake Bay. The B-IBI weights several community measures equally and uses a simple scoring system while the EMAP-VP Benthic Index uses discriminant...

Using Regional Distribution of Estuarine and Coastal Benthic Invertebrates to Calibrate Benthic Indices of Ecological Condition

EPA Science Inventory

The biogeography of marine benthic macroinvertebrates of the U.S. Atlantic coast from Delaware Bay north to Passamaquoddy Bay, Maine, was studied to define physical-chemical factors affecting broad taxa distributions and provide information needed to calibrate benthic indices of ...

Biological, habitat, and water quality conditions in the upper Merced River drainage, Yosemite National Park, California, 1993-1996

USGS Publications Warehouse

Brown, Larry R.; Short, Terry M.

1999-01-01

The general conclusion from these studies is that water quality in the upper Merced River was very good from 1993-1996, despite high levels of human activities in some areas. Fish communities did not appear to be a useful indicator of habitat and water quality because of low species richness and the apparent importance of physical barriers in determining species distributions. Measurements of fish densities and size-distributions might be useful, but would be logistically difficult. Benthic algae and benthic invertebrates do appear to be useful in monitoring environmental conditions. Benthic algae may be more sensitive than benthic invertebrates to small environmental differences within years. Benthic algae were also more responsive than benthic invertebrates to differences in discharge between years. Thus, benthic invertebrates may be more useful in comparing environmental conditions between years, independent of discharge conditions.

Benthic protists: the under-charted majority.

PubMed

Forster, Dominik; Dunthorn, Micah; Mahé, Fréderic; Dolan, John R; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Edvardsen, Bente; Egge, Elianne; Eikrem, Wenche; Gobet, Angélique; Kooistra, Wiebe H C F; Logares, Ramiro; Massana, Ramon; Montresor, Marina; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Romac, Sarah; Shalchian-Tabrizi, Kamran; Simon, Nathalie; Richards, Thomas A; Santini, Sébastien; Sarno, Diana; Siano, Raffaele; Vaulot, Daniel; Wincker, Patrick; Zingone, Adriana; de Vargas, Colomban; Stoeck, Thorsten

2016-08-01

Marine protist diversity inventories have largely focused on planktonic environments, while benthic protists have received relatively little attention. We therefore hypothesize that current diversity surveys have only skimmed the surface of protist diversity in marine sediments, which may harbor greater diversity than planktonic environments. We tested this by analyzing sequences of the hypervariable V4 18S rRNA from benthic and planktonic protist communities sampled in European coastal regions. Despite a similar number of OTUs in both realms, richness estimations indicated that we recovered at least 70% of the diversity in planktonic protist communities, but only 33% in benthic communities. There was also little overlap of OTUs between planktonic and benthic communities, as well as between separate benthic communities. We argue that these patterns reflect the heterogeneity and diversity of benthic habitats. A comparison of all OTUs against the Protist Ribosomal Reference database showed that a higher proportion of benthic than planktonic protist diversity is missing from public databases; similar results were obtained by comparing all OTUs against environmental references from NCBI's Short Read Archive. We suggest that the benthic realm may therefore be the world's largest reservoir of marine protist diversity, with most taxa at present undescribed. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Compound-Specific Amino Acid Isotopic Analysis of Benthic Food Webs in the Chukchi Sea

NASA Astrophysics Data System (ADS)

Zhang, M.; Cooper, L. W.; Biasatti, D. M.; Grebmeier, J. M.

2014-12-01

The Chukchi Sea is known for locally high standing stocks of benthic macrofauna and strong coupling between pelagic-benthic components of the ecosystem. However, benthic food structure is not fully understood, due to varied sources of particulate organic matter (POM) and the high diversity of benthic invertebrates. We provide the first demonstration of the application of compound-specific amino acid isotope analysis to study the dietary sources and trophic structure for this Arctic marginal sea. About 20 stations in Chukchi Sea were sampled during cruises in August of 2012 and 2013. At each station, phytoplankton, POM and benthic fauna were collected, processed and analyzed using GC-C-IRMS (gas chromatography-combustion-isotope ratio mass spectrometry). Among benthic fauna, dominant species included the following taxonomic groups: Ophiuroidea, Amphipoda, Polychaeta, Gastropoda, Bivalvia, and Cnidaria. The benthic fauna showed similar patterns of individual amino acid δ13C, with glycine the most enriched in 13C and leucine the most depleted in 13C. Specific amino acids including phenylalanine showed spatial variability in δ13C and δ15N values within the sampled area, indicating contributions of different dietary sources including phytoplankton, sea ice algae, benthic algae and terrestrial organic materials. δ15N values of individual amino acids such as the difference between glutamic acid and phenylalanine, i.e. Δ15Nglu-phe (δ15Nglu - δ15Nphe), were also used to identify trophic levels of benthic invertebrates relative to estimates available from bulk δ15N values. These data will ultimately be used to evaluate the spatial variability of organic carbon sources and trophic level interactions of dominant benthic species in the Chukchi Sea.

A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

PubMed

Schwing, Patrick T; Romero, Isabel C; Brooks, Gregg R; Hastings, David W; Larson, Rebekka A; Hollander, David J

2015-01-01

Sediment cores were collected from three sites (1000-1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background) in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long-term effects of the DWH event on a larger spatial scale.

A Decline in Benthic Foraminifera following the Deepwater Horizon Event in the Northeastern Gulf of Mexico

PubMed Central

Schwing, Patrick T.; Romero, Isabel C.; Brooks, Gregg R.; Hastings, David W.; Larson, Rebekka A.; Hollander, David J.

2015-01-01

Sediment cores were collected from three sites (1000–1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (210Pb, 234Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80–93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2–3 times background) in PAH’s, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long-term effects of the DWH event on a larger spatial scale. PMID:25785988

Influence of coral and algal exudates on microbially mediated reef metabolism.

PubMed

Haas, Andreas F; Nelson, Craig E; Rohwer, Forest; Wegley-Kelly, Linda; Quistad, Steven D; Carlson, Craig A; Leichter, James J; Hatay, Mark; Smith, Jennifer E

2013-01-01

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs.

Spatial and Temporal Variation in DeSoto Canyon Macrofaunal Community Structure

NASA Astrophysics Data System (ADS)

Baco-Taylor, A.; Shantharam, A. K.

2016-02-01

Sediment-dwelling macrofauna (polychaetes, bivalves, and assorted crustaceans ≥ 300 µm) have long served as biological indicators of ecosystem stress. As part of evaluating the 2010 impact from the Deepwater Horizon blowout, we sampled 12 sites along and transverse to the DeSoto Canyon axis, Gulf of Mexico, as well as 2 control sites outside the Canyon. Sites ranged in depth from 479-2310 m. Three of the sites (PCB06, S36, and XC4) were sampled annually from 2012-2014. We provide an overview of the macrofauna community structure of canyon and non-canyon sites, as well as trends in community structure and diversity at the time-series sites. Compositionally, polychaetes dominated the communities, followed by tanaid crustaceans and bivalves. The total number of individuals was not significantly correlated with depth while the total number of taxa and species richness were. Rarefaction shows the deepest station, XC4 (2310 m) had the lowest diversity while NT800 (a non-canyon control at 800m) had the highest. Multivariate analysis shows the canyon assemblages fall into eight clusters with the non-canyon stations forming a separate ninth cluster, indicating a detectable difference in canyon and non-canyon communities. Time series stations show an increase in diversity from 2012-2014 with a strong overlap in community structure in 2013 and 2014 samples. Environmental analysis, via BEST, using data from 10 canyon sites and the controls, indicated depth in combination with latitude explain the most variation in macrofaunal community structure.

Long-term recovery of a Mountain Stream from Clearcut Logging: The Effects of Forest Succession on Benthic Invertebrate Community Structure

Treesearch

Michael K. Stone; J. Bruce Wallace

1998-01-01

Summary1. Changes in benthic invertebrate community structure following 16 years of forest succession after logging were examined by estimating benthic invertebrate abundance, biomass and secondary production in streams draining a forested reference and a recovering clear-cut catchment. Benthic invertebrate abundance was three times higher,...

Indicators: Benthic Macroinvertebrates

EPA Pesticide Factsheets

Benthic (meaning “bottom-dwelling”) macroinvertebrates are small aquatic animals and the aquatic larval stages of insects. Benthic macroinvertebrates are commonly used as indicators of the biological condition of waterbodies.

Characterizing the role benthos plays in large coastal seas and estuaries: A modular approach

USGS Publications Warehouse

Tenore, K.R.; Zajac, R.N.; Terwin, J.; Andrade, F.; Blanton, J.; Boynton, W.; Carey, D.; Diaz, R.; Holland, Austin F.; Lopez-Jamar, E.; Montagna, P.; Nichols, F.; Rosenberg, R.; Queiroga, H.; Sprung, M.; Whitlatch, R.B.

2006-01-01

Ecologists studying coastal and estuarine benthic communities have long taken a macroecological view, by relating benthic community patterns to environmental factors across several spatial scales. Although many general ecological patterns have been established, often a significant amount of the spatial and temporal variation in soft-sediment communities within and among systems remains unexplained. Here we propose a framework that may aid in unraveling the complex influence of environmental factors associated with the different components of coastal systems (i.e. the terrestrial and benthic landscapes, and the hydrological seascape) on benthic communities, and use this information to assess the role played by benthos in coastal ecosystems. A primary component of the approach is the recognition of system modules (e.g. marshes, dendritic systems, tidal rivers, enclosed basins, open bays, lagoons). The modules may differentially interact with key forcing functions (e.g. temperature, salinity, currents) that influence system processes and in turn benthic responses and functions. Modules may also constrain benthic characteristics and related processes within certain ecological boundaries and help explain their overall spatio-temporal variation. We present an example of how benthic community characteristics are related to the modular structure of 14 coastal seas and estuaries, and show that benthic functional group composition is significantly related to the modular structure of these systems. We also propose a framework for exploring the role of benthic communities in coastal systems using this modular approach and offer predictions of how benthic communities may vary depending on the modular composition and characteristics of a coastal system. ?? 2006 Elsevier B.V. All rights reserved.

Classification of threespine stickleback along the benthic-limnetic axis.

PubMed

Willacker, James J; von Hippel, Frank A; Wilton, Peter R; Walton, Kelly M

2010-11-01

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have been studied because identifying additional populations as either benthic or limnetic requires detailed dietary or observational studies. Here we develop a Fisher's linear discriminant function based on the skull morphology of known benthic and limnetic stickleback populations from the Cook Inlet Basin of Alaska and test the feasibility of using this function to identify other morphologically divergent populations. Benthic and limnetic morphotypes were separable using this technique and of 45 populations classified, three were identified as morphologically extreme (two benthic and one limnetic), nine as moderately divergent (three benthic and six limnetic) and the remaining 33 populations as morphologically intermediate. Classification scores were found to correlate with eye size, the depth profile of lakes, and the presence of invasive northern pike (Esox lucius). This type of classification function provides a means of integrating the complex morphological differences between morphotypes into a single score that reflects the position of a population along the benthic-limnetic axis and can be used to relate that position to other aspects of stickleback biology.

Classification of threespine stickleback along the benthic-limnetic axis

PubMed Central

Willacker, James J.; von Hippel, Frank A.; Wilton, Peter R.; Walton, Kelly M.

2010-01-01

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have been studied because identifying additional populations as either benthic or limnetic requires detailed dietary or observational studies. Here we develop a Fisher’s linear discriminant function based on the skull morphology of known benthic and limnetic stickleback populations from the Cook Inlet Basin of Alaska and test the feasibility of using this function to identify other morphologically divergent populations. Benthic and limnetic morphotypes were separable using this technique and of 45 populations classified, three were identified as morphologically extreme (two benthic and one limnetic), nine as moderately divergent (three benthic and six limnetic) and the remaining 33 populations as morphologically intermediate. Classification scores were found to correlate with eye size, the depth profile of lakes, and the presence of invasive northern pike (Esox lucius). This type of classification function provides a means of integrating the complex morphological differences between morphotypes into a single score that reflects the position of a population along the benthic-limnetic axis and can be used to relate that position to other aspects of stickleback biology. PMID:21221422

NO3 uptake in shallow, oligotrophic, mountain lakes: The influence of elevated NO3 concentrations

USGS Publications Warehouse

Nydick, K.R.; LaFrancois, B.M.; Baron, Jill S.

2004-01-01

Nutrient enrichment experiments were conducted in 1.2-m deep enclosures in 2 shallow, oligotrophic, mountain lakes. 15N-NO3 isotope tracer was used to compare the importance of phytoplankton and benthic compartments (epilithon, surface sediment [epipelon], and subsurface sediment) for NO3 uptake under high and low NO3 conditions. NO3 uptake approached saturation in the high-N lake, but not in the low-N lake. The capacity of phytoplankton and benthic compartments to take up NO3 differed among treatments and between lakes, and depended on water-column nutrient conditions and the history of NO3 availability. Phytoplankton productivity responded strongly to addition of limiting nutrients, and NO3 uptake was related to phytoplankton biomass and photosynthesis. However, more NO3 usually was taken up by benthic compartments (57–92% combined) than by phytoplankton, even though the response of benthic algal biomass to nutrient additions was less pronounced than that of phytoplankton and benthic NO3 uptake was unrelated to benthic algal biomass. In the low-N lake where NO3 uptake was unsaturated, C content or % was related to NO3 uptake in benthic substrates, suggesting that heterotrophic bacterial processes could be important in benthic NO3 uptake. These results suggest that phytoplankton are most sensitive to nutrient additions, but benthic processes are important for NO3 uptake in shallow, oligotrophic lakes.

Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

USGS Publications Warehouse

Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

2014-01-01

We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

Effects of Benthic Barriers on Macroinvertebrate Communities

DTIC Science & Technology

1993-10-01

Aquatic Plant Control Research Program Effects of Benthic Barriers on Macroinvertebrate Communities by Barry S. Payne, Andrew C. Miller Environmental...Plant Control Technical Report A-93-5Resear h Program Oct ber 1993 Effects of Benthic Barriers on Macroinvertebrate Communities by Barry S. Payne...Effects of benthic barriers on macroinvertebrate communities / by Barry S. Payne, Andrew C. Miller, [and] Thomas Ussery ; prepared for U.S. Army Corps of

Benthic Food Webs of the Chukchi and Beaufort Seas: Relative Importance of Ultimate Carbon Sources in a Changing Climate

NASA Astrophysics Data System (ADS)

Dunton, K. H.; Schonberg, S. V.; Mctigue, N.; Bucolo, P. A.; Connelly, T. L.; McClelland, J. W.

2014-12-01

Changes in sea-ice cover, coastal erosion, and freshwater run-off have the potential to greatly influence carbon assimilation pathways and affect trophic structure in benthic communities across the western Arctic. In the Chukchi Sea, variations in the duration and timing of ice cover affect the delivery of ice algae to a relatively shallow (40-50 m) shelf benthos. Although ice algae are known as an important spring carbon subsidy for marine benthic fauna, ice algal contributions may also help initiate productivity of an active microphytobenthos. Recent studies provide clear evidence that the microphytobenthos are photosynthetically active, and have sufficient light and nutrients for in situ growth. The assimilation of benthic diatoms from both sources may explain the 13C enrichment observed in benthic primary consumers throughout the northern Chukchi. On the eastern Beaufort Sea coast, shallow (2-4 m) estuarine lagoon systems receive massive subsidies of terrestrial carbon that is assimilated by a benthic fauna of significant importance to upper trophic level species, but again, distinct 13C enrichment in benthic primary consumers suggests the existence of an uncharacterized food source. Since ice algae are absent, we believe the 13C enrichment in benthic fauna is caused by the assimilation of benthic microalgae, as reflected in seasonally high benthic chlorophyll in spring under replete light and nutrient conditions. Our observations suggest that changes in ice cover, on both temporal and spatial scales, are likely to have significant effects on the magnitude and timing of organic matter delivery to both shelf and nearshore systems, and that locally produced organic matter may become an increasingly important carbon subsidy that affects trophic assimilation and secondary ecosystem productivity.

Historical assessments and comparisons of benthic communities and physical habitat in two agricultural streams in California's San Joaquin watershed.

PubMed

Hall, Lenwood W; Killen, William D

2006-01-01

This study was designed to assess trends in physical habitat and benthic communities (macroinvertebrates) annually in two agricultural streams (Del Puerto Creek and Salt Slough) in California's San Joaquin Valley from 2001 to 2005, determine the relationship between benthic communities and both water quality and physical habitat from both streams over the 5-year period, and compare benthic communities and physical habitat in both streams from 2001 to 2005. Physical habitat, measured with 10 metrics and a total score, was reported to be fairly stable over 5 years in Del Puerto Creek but somewhat variable in Salt Slough. Benthic communities, measured with 18 metrics, were reported to be marginally variable over time in Del Puerto Creek but fairly stable in Salt Slough. Rank correlation analysis for both water bodies combined showed that channel alteration, embeddedness, riparian buffer, and velocity/depth/diversity were the most important physical habitat metrics influencing the various benthic metrics. Correlations of water quality parameters and benthic community metrics for both water bodies combined showed that turbidity, dissolved oxygen, and conductivity were the most important water quality parameters influencing the different benthic metrics. A comparison of physical habitat metrics (including total score) for both water bodies over the 5-year period showed that habitat metrics were more positive in Del Puerto Creek when compared to Salt Slough. A comparison of benthic metrics in both water bodies showed that approximately one-third of the metrics were significantly different between the two water bodies. Generally, the more positive benthic metric scores were reported in Del Puerto Creek, which suggests that the communities in this creek are more robust than Salt Slough.

Food web heterogeneity and succession in created saltmarshes

USGS Publications Warehouse

Nordstrom, M C; Demopoulos, Amanda W.J.; Whitcraft, CR; Rismondo, A.; McMillan, P.; Gonzales, J P; Levin, L A

2015-01-01

1. Ecological restoration must achieve functional as well as structural recovery. Functional metrics for reestablishment of trophic interactions can be used to complement traditional monitoring of structural attributes. In addition, topographic effects on food web structure provide added information within a restoration context; often, created sites may require spatial heterogeneity to effectively match structure and function of natural habitats. 2. We addressed both of these issues in our study of successional development of benthic food web structure, with focus on bottom–up driven changes in macroinvertebrate consumer assemblages in the salt marshes of the Venice Lagoon, Italy. We combined quantified estimates of the changing community composition with stable isotope data (13C:12C and 15N:14N) to compare the general trophic structure between created (2–14 years) marshes and reference sites and along topographic elevation gradients within salt marshes. 3. Macrofaunal invertebrate consumers exhibited local, habitat-specific trophic patterns. Stable isotope-based trophic structure changed with increasing marsh age, in particular with regards to mid-elevation (Salicornia) habitats. In young marshes, the mid-elevation consumer signatures resembled those of unvegetated ponds. The mid elevation of older and natural marshes had a more distinct Salicornia-zone food web, occasionally resembling that of the highest (Sarcocornia-dominated) elevation. In summary, this indicates that primary producers and availability of vascular plant detritus structure consumer trophic interactions and the flow of carbon. 4. Functionally different consumers, subsurface-feeding detritivores (Oligochaeta) and surface grazers (Hydrobia sp.), showed distinct but converging trajectories of isotopic change over time, indicating that successional development may be asymmetric between ‘brown’ (detrital) guilds and ‘green’ (grazing) guilds in the food web. 5. Synthesis and applications. Created marsh food webs converged into a natural state over about a decade, with successional shifts seen in both consumer community composition and stable isotope space. Strong spatial effects were noted, highlighting the utility of stable isotopes to evaluate functional equivalence in spatially heterogeneous systems. Understanding the recovery of functional properties such as food web support, and their inherent spatial variability, is key to planning and managing successful habitat restoration.

Biodiversity patterns, environmental drivers and indicator species on a high-temperature hydrothermal edifice, Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Sarrazin, Jozée; Legendre, Pierre; de Busserolles, Fanny; Fabri, Marie-Claire; Guilini, Katja; Ivanenko, Viatcheslav N.; Morineaux, Marie; Vanreusel, Ann; Sarradin, Pierre-Marie

2015-11-01

Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe), sulfide (TdS), copper (TdCu) and pH) on the distribution of macro- and meiofaunal species at small spatial scales (<1 m). There were differences in macro- and meiofaunal community structure between the different sampling locations, separating the hydrothermal community of the Eiffel Tower edifice into three types of microhabitats: (1) cold microhabitats characterized by low temperatures (<6 °C), high TdCu (up to 2.4±1.37 μmol l-1), high pH (up to 7.34±0.13) but low TdS concentrations (<6.98±5.01 μmol l-1); (2) warm microhabitats characterized by warmer temperatures (>6 °C), low pH (<6.5) and high TdS/TdFe concentrations (>12.8 μmol l-1/>1.1 μmol l-1 respectively); and (3) the third microhabitat characterized by intermediate abiotic conditions. Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats. Six macrofaunal species (Branchipolynoe seepensis, Amathys lutzi, Bathymodiolus azoricus, Lepetodrilus fucensis, Protolira valvatoides and Chorocaris chacei) and three meiofaunal taxa (Paracanthonchus, Cephalochaetosoma and Microlaimus) were identified as being significant indicator species/taxa of particular microhabitats. Our results also highlight very specific niche separation for copepod juveniles among the different hydrothermal microhabitats. Some sampling units showed unique faunal composition and increased beta diversity on the Eiffel Tower edifice. Contrary to what was expected, the highest beta diversity was not associated with a particular microhabitat type, but rather with location on the central part of the edifice where other structuring factors may predominate.

Microbial biogeography of San Francisco Bay sediments

NASA Astrophysics Data System (ADS)

Lee, J. A.; Francis, C. A.

2014-12-01

The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess whether patterns of diversity observed at the broadest of taxonomic scales also apply to patterns observed within a single extremely diverse gene (nirS). In sum, this project provides a first look at the forces driving the migration and selection of microbial communities in San Francisco Bay.

Are boundary conditions in surface productivity at the Southern Polar Front reflected in benthic activity?

NASA Astrophysics Data System (ADS)

Brandt, Angelika; Vanreusel, Ann; Bracher, Astrid; Jule Marie Hoppe, Clara; Lins, Lidia; Meyer-Löbbecke, Anna; Altenburg Soppa, Mariana; Würzberg, Laura

2014-10-01

In austral summer 2012, during the expedition ANT-XXVIII/3 on board RV Polarstern, two sites were sampled 1600 km apart in the South Polar Front area (52°S) at the boundary of different productivity regimes for meio- and macrobenthos using a multiple-corer and an epibenthic sledge, respectively. Patterns in density and abundance data were compared between different size classes of the benthos and interpreted in relation to surface primary productivity data and sediment oxygen consumption. We tested the hypothesis that long-term satellite-derived surface phytoplankton biomass, in situ real time biomass, and productivity measurements at the surface and throughout the euphotic zone are reflected in abyssal benthos densities, abundances and activity. Specifically, we investigated the effect of boundary conditions for lower and higher surface productivity. Surface and integrated to 100 m depth biomass and primary productivity measurements vary stations, with the lowest values at station 85 (0.083 mg Chl-a m-3 at surface, 9 mg Chl-a m-2 and 161 mg C m-2 d-1- integrated over the first 100 m depth), and the highest values at station 86 (2.231 mg Chl-a m-3 at surface, 180 mg Chl-a m-2 and 2587 mg C m-2 d-1 integrated over first 100 m depth). Total meiofaunal densities varied between 102 and 335 individuals/10 cm². Densities were the highest at station 86-30 (335 individuals) and lowest at station 81-13 (102 individuals). Total macrofaunal densities (individuals/1000 m²) varied between 26 individuals at station 81-17 and 194 individuals at station 86-24. However, three EBS hauls were taken at station 86 with a minimum of 80 and a maximum of 194 individuals. Sediment oxygen consumption did not vary significantly between stations from east to west. Bentho-pelagic coupling of meio- and macrobenthic communities could not be observed in the South Polar Front at the boundary conditions from low to high surface productivity between stations 81 and 86.

Analytical characterization of selective benthic flux components in estuarine and coastal waters

USGS Publications Warehouse

King, Jeffrey N.

2011-01-01

Benthic flux is the rate of flow across the bed of a water body, per unit area of bed. It is forced by component mechanisms, which interact. For example, pressure gradients across the bed, forced by tide, surface gravity waves, density gradients, bed–current interaction, turbulence, and terrestrial hydraulic gradients, drive an advective benthic flux of water and constituents between estuarine and coastal waters, and surficial aquifers. Other mechanisms also force benthic flux, such as chemical gradients, bioturbation, and dispersion. A suite of component mechanisms force a total benthic flux at any given location, where each member of the suite contributes a component benthic flux. Currently, the types and characteristics of component interactions are not fully understood. For example, components may interact linearly or nonlinearly, and the interaction may be constructive or destructive. Benthic flux is a surface water–groundwater interaction process. Its discharge component to a marine water body is referred to, in some literature, as submarine groundwater discharge. Benthic flux is important in characterizing water and constituent budgets of estuarine and coastal systems. Analytical models to characterize selective benthic flux components are reviewed. Specifically, these mechanisms are for the component associated with the groundwater tidal prism, and forced by surface gravity wave setup, surface gravity waves on a plane bed, and the terrestrial hydraulic gradient. Analytical models are applied to the Indian River Lagoon, Florida; Great South Bay, New York; and the South Atlantic Bight in South Carolina and portions of North Carolina.

Benthic Algal Community Structures and Their Response to Geographic Distance and Environmental Variables in the Qinghai-Tibetan Lakes With Different Salinity

PubMed Central

Yang, Jian; Jiang, Hongchen; Liu, Wen; Wang, Beichen

2018-01-01

Uncovering the limiting factors for benthic algal distributions in lakes is of great importance to understanding of their role in global carbon cycling. However, limited is known about the benthic algal community distribution and how they are influenced by geographic distance and environmental variables in alpine lakes. Here, we investigated the benthic algal community compositions in the surface sediments of six lakes on the Qinghai-Tibetan Plateau (QTP), China (salinity ranging from 0.8 to 365.6 g/L; pairwise geographic distance among the studied lakes ranging 8–514 km) employing an integrated approach including Illumina-Miseq sequencing and environmental geochemistry. The results showed that the algal communities of the studied samples were mainly composed of orders of Bacillariales, Ceramiales, Naviculales, Oscillatoriales, Spirulinales, Synechococcales, and Vaucheriales. The benthic algal community compositions in these QTP lakes were significantly (p < 0.05) correlated with many environmental (e.g., dissolved inorganic and organic carbon, illumination intensity, total nitrogen and phosphorus, turbidity and water temperature) and spatial factors, and salinity did not show significant influence on the benthic algal community structures in the studied lakes. Furthermore, geographic distance showed strong, significant correlation (r = 0.578, p < 0.001) with the benthic algal community compositions among the studied lakes, suggesting that spatial factors may play important roles in influencing the benthic algal distribution. These results expand our current knowledge on the influencing factors for the distributions of benthic alga in alpine lakes. PMID:29636745

Oyster reef restoration in the Northern Gulf of Mexico: effect of artificial substrate and sge on nekton and benthic macroinvertebrate assemblage use

USGS Publications Warehouse

Brown, Laura A.; Furlong, Jessica N.; Brown, Kenneth M.; LaPeyre, Megan K.

2013-01-01

In the northern Gulf of Mexico (GOM), reefs built by eastern oysters, Crassostrea virginica, provide critical habitat within shallow estuaries, and recent efforts have focused on restoring reefs to benefit nekton and benthic macroinvertebrates. We compared nekton and benthic macroinvertebrate assemblages at historic, newly created (<5years) and old (>6years) shell and rock substrate reefs. Using crab traps, gill-nets, otter trawls, cast nets, and benthic macroinvertebrate collectors, 20 shallow reefs (<5m) in the northern GOM were sampled throughout the summer of 2011. We compared nekton and benthic assemblage abundance, diversity and composition across reef types. Except for benthic macroinvertebrate abundance, which was significantly higher on old rock reefs as compared to historic reefs, all reefs were similar to historic reefs, suggesting created reefs provide similar support of nekton and benthic assemblages as historic reefs. To determine refuge value of oyster structure for benthic macroinvertebrates compared to bare bottom, we tested preferences of juvenile crabs across depth and refuge complexity in the presence and absence of adult blue crabs (Callinectes sapidus). Juveniles were more likely to use deep water with predators present only when provided oyster structure. Provision of structural material to support and sustain development of benthic and mobile reef communities may be the most important factor in determining reef value to these assemblages, with biophysical characteristics related to reef location influencing assemblage patterns in areas with structure; if so, appropriately locating created reefs is critical.

Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

DTIC Science & Technology

2012-09-30

clearly demonstrates that gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen...We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. Although benthic...Jan Rines (Graduate School of Oceanography / University of Rhode Island = GSO/URI) to identify the benthic microalgae in the samples. Following the

Nutrient and suspended-sediment concentrations and loads and benthic-invertebrate data for tributaries to the St. Croix River, Wisconsin and Minnesota, 1997-99

USGS Publications Warehouse

Lenz, Bernard N.; Robertson, Dale M.; Fallon, James D.; Ferrin, Randy

2001-01-01

Benthic invertebrates were sampled and indices of water quality were calculated at 16 tributaries in fall 1999. Benthic invertebrate indices indicated excellent to good water quality at all tributaries except Valley Creek, Willow River, and Kettle River. No relations were found between benthic invertebrate indices and the calculated and estimated 1999 annual tributary loads and yields.

Habitat used by juvenile lake sturgeon (Acipenser fulvescens) in the North Channel of the St. Clair River (Michigan, USA)

USGS Publications Warehouse

Boase, James C.; Manny, Bruce A.; Donald, Katherine A.L.; Kennedy, Gregory W.; Diana, James S.; Thomas, Michael V.; Chiotti, Justin A.

2014-01-01

Lake sturgeon (Acipenser fulvescens) occupy the St. Clair River, part of a channel connecting lakes Huron and Erie in the Laurentian Great Lakes. In the North Channel of the St. Clair River, juvenile lake sturgeon (3–7 years old and 582–793 mm in length) were studied to determine movement patterns and habitat usage. Fourteen juveniles were implanted with ultrasonic transmitters and tracked June–August of 2004, 2005 and 2006. Telemetry data, Geographic Information System software, side-scan sonar, video images of the river bottom, scuba diving, and benthic substrate samples were used to determine the extent and composition of habitats they occupied. Juvenile lake sturgeon habitat selection was strongly related to water depth. No fish were found in 700 mm in length selected sand and gravel areas mixed with zebra mussels and areas dominated by zebra mussels, while fish < 700 mm used these habitat types in proportion to their availability.

Contribution of benthic microalgae to the temporal variation in phytoplankton assemblages in a macrotidal system.

PubMed

Hernández Fariñas, Tania; Ribeiro, Lourenço; Soudant, Dominique; Belin, Catherine; Bacher, Cédric; Lampert, Luis; Barillé, Laurent

2017-10-01

Suspended marine benthic microalgae in the water column reflect the close relationship between the benthic and pelagic components of coastal ecosystems. In this study, a 12-year phytoplankton time-series was used to investigate the contribution of benthic microalgae to the pelagic system at a site along the French-Atlantic coast. Furthermore, all taxa identified were allocated into different growth forms in order to study their seasonal patterns. The highest contribution of benthic microalgae was observed during the winter period, reaching up to 60% of the carbon biomass in the water column. The haptobenthic growth form showed the highest contribution in terms of biomass, dominant in the fall-winter period when the turbidity and the river flow were high. The epipelic growth form did not follow any seasonal pattern. The epiphytic diatom Licmophora was most commonly found during summer. As benthic microalgae were found in the water column throughout the year, the temporal variation detected in the structure of pelagic assemblages in a macrotidal ecosystem was partly derived from the differentiated contribution of several benthic growth forms. © 2017 Phycological Society of America.

Environmental characteristics and benthic invertebrate assemblages in Colorado mountain lakes

USGS Publications Warehouse

LaFrancois, B.M.; Carlisle, D.M.; Nydick, K.R.; Johnson, B.M.; Baron, Jill S.

2003-01-01

Twenty-two high-elevation lakes (>3000 m) in Rocky Mountain National Park and Indian Peaks Wilderness Area, Colorado, were surveyed during summer 1998 to explore relationships among benthic invertebrates, water chemistry (particularly nitrate concentrations), and other environmental variables. Water samples were collected from the deepest portion of each lake and analyzed for ions and other water chemistry parameters. Benthic invertebrates were collected from the littoral zone using both a sweep net and Hess sampler. Physical and geographical measurements were derived from maps. Relationships among benthic invertebrate assemblages and environmental variables were examined using canonical correspondence analysis, and the importance of sampling methodology and taxonomie resolution on these relationships was evaluated. Choice of sampling methodology strongly influenced the outcome of statistical analyses, whereas taxonomie resolution did not. Presence/absence of benthic invertebrate taxa among the study lakes was best explained by elevation and presence of fish. Relative abundance and density of benthic invertebrate taxa were more strongly influenced by sampling date and water chemistry. Nitrate (NO₃⁻) concentration, potentially on the rise due to regional nitrogen deposition, was unrelated to benthic invertebrate distribution regardless of sampling method or taxonomie resolution.

Habitat associations and distribution of the hyperbenthic shrimp, Nauticaris marionis, around the sub-Antarctic Prince Edward Islands

NASA Astrophysics Data System (ADS)

Haley, Craig; von der Meden, Charles; Atkinson, Lara; Reed, Cecile

2017-09-01

The association of organisms with particular habitats and habitat-forming organisms, can strongly influence species distributions, interactions and wider ecosystem services. At the sub-Antarctic Prince Edward Islands, the caridean shrimp Nauticaris marionis is a principal part of the benthic ecosystem, occurring between ca. 50 m and 600 m. Its role as a trophic link between the primary productivity and higher predators is established, but little is understood of its in situ habitat usage and associations or of how these structure patterns of abundance. We investigated these aspects directly using a benthic camera sled, sampling 27 stations between 50 m and 500 m. Substratum type was characterised, and estimates of percentage cover of the 13 main groups of habitat-forming epibenthic taxa were made, alongside absolute counts of N. marionis within 'digital quadrats' drawn from 300 m transects. The distribution of N. marionis was influenced by depth, substratum type and overall biogenic cover, being limited to habitats between 50 and 160 m depth on mud or gravel substrata only, and having > 50% biogenic cover. The presence/absence of N. marionis related to significantly different epibenthic assemblages (termed biogenic habitats), but this effect was contingent on depth. Likewise, densities of N. marionis were significantly affected by biogenic habitat type, identifying an association with two biogenic habitat groups, one dominated by red-algae, the other by structurally complex bryozoan species. These associations likely relate to the structural complexity of the two habitat groups, rather than the specific taxa involved. The apparent absence of N. marionis at depths > 160 m contrasts with earlier records and poses questions about the trophic importance of the shrimp in deeper habitats.

The influence of reduced light intensity on the response of benthic diatoms to herbicide exposure.

PubMed

Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

2016-09-01

Herbicide pollution events in aquatic ecosystems often coincide with increased turbidity and reduced light intensity. It is therefore important to determine whether reduced light intensity can influence herbicide toxicity, especially to primary producers such as benthic diatoms. Benthic diatoms collected from 4 rivers were exposed to herbicides in 48 h rapid toxicity tests under high light (100 µmol m(-2)  s(-1) ) and low light (20 µmol m(-2)  s(-1) ) intensities. The effects of 2 herbicides (atrazine and glyphosate) were assessed on 26 freshwater benthic diatom taxa. There was no significant interaction of light and herbicide effects at the community level or on the majority (22 of 26) of benthic diatom taxa. This indicates that low light levels will likely have only a minor influence on the response of benthic diatoms to herbicides. Environ Toxicol Chem 2016;35:2252-2260. © 2016 SETAC. © 2016 SETAC.

Benthic meiofaunal community response to the cascading effects of herbivory within an algal halo system of the Great Barrier Reef

PubMed Central

Hammill, Edward; Booth, David J.; Madin, Elizabeth M. P.; Hinchliffe, Charles; Harborne, Alastair R.; Lovelock, Catherine E.; Macreadie, Peter I.; Atwood, Trisha B.

2018-01-01

Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the ‘grazing halos’ of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways. PMID:29513746

Benthic meiofaunal community response to the cascading effects of herbivory within an algal halo system of the Great Barrier Reef.

PubMed

Ollivier, Quinn R; Hammill, Edward; Booth, David J; Madin, Elizabeth M P; Hinchliffe, Charles; Harborne, Alastair R; Lovelock, Catherine E; Macreadie, Peter I; Atwood, Trisha B

2018-01-01

Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the 'grazing halos' of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways.

Benthic Macroinvertebrate Assemblages in the Near Coastal Zone of Lake Erie

EPA Science Inventory

Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

Long-term historical analysis of benthic communities and physical habitat in an agricultural stream in California's San Joaquin River watershed.

PubMed

Hall, Lenwood W; Killen, William D; Alden, Raymond

2009-05-01

This study was designed to characterize long-term annual temporal and spatial trends (2001 to 2007) in physical habitat and benthic communities and to determine relationships of habitat and benthic communities during this 7-year period in an agricultural stream in the San Joaquin River watershed in California (Del Puerto Creek). The canonical discriminant analysis indicated that there were no overall significant temporal patterns for the habitat metrics although spatial patterns were prominent for nearly all the habitat metrics. Channel alteration, riparian vegetative zone, bank stability, vegetative protection and frequency of riffles/bends were the primary habitat metrics associated with these site effects. Approximately 3,700 to 4,500 individual macroinvertebrates were picked and identified from five Del Puerto Creek sites sampled annually from 2001 to 2007. The total number of taxa by year ranged from 81 in 2003 to 106 in 2007. These benthic assemblages were generally comprised of tolerant to moderately tolerant taxa such as blackflies, oligochaetes, snails and chironomids. The metrics % predators, % EPT index, % collectors/filterers and % shredders were the benthic metrics that were most associated with the temporal effects. Ephemeroptera taxa, trichoptera taxa, and % sensitive EPT index were the benthic metrics that were most associated with the site effects. The most upstream site in Del Puerto Creek had the most robust and healthy benthic communites. Strong statistical relationships were reported between certain benthic metrics and habitat metrics. Overall, samples taken from site-year combinations with sediments that were qualitatively less muddy (less fines) and that had higher habitat metric scores for embeddedness, riparian vegetative zone, and channel alteration tended to have benthic communities characterized by higher values of the benthic metrics such as EPT taxa, Ephemeroptera taxa, EPT index, abundance, and taxonomic richness, among others. Conversely, tolerance value and % tolerant taxa, the indicators of stressed benthic communities, were found to be inversely related to Bank Stability and Riparian vegetative zone (respectively), both indicators of habitat quality. Relationships between the quality of the physical habitat and the health of the benthic communities in aquatic systems, such as agricultural streams, needs to be considered before the impact of anthropogenic agents (e.g., pesticides, metals, and other potential toxicants) or other man-made perturbations may be understood. Otherwise, the interpretation of patterns of environmental conditions or causalities may be confounded.

Impacts of the Deepwater Horizon oil spill on deep-sea coral-associated sediment communities

USGS Publications Warehouse

Demopoulos, Amanda W.J.; Bourque, Jill R.; Cordes, Erik E.; Stamler, Katherine

2016-01-01

Cold-water corals support distinct populations of infauna within surrounding sediments that provide vital ecosystem functions and services in the deep sea. Yet due to their sedentary existence, infauna are vulnerable to perturbation and contaminant exposure because they are unable to escape disturbance events. While multiple deep-sea coral habitats were injured by the 2010 Deepwater Horizon (DWH) oil spill, the extent of adverse effects on coral-associated sediment communities is unknown. In 2011, sediments were collected adjacent to several coral habitats located 6 to 183 km from the wellhead in order to quantify the extent of impact of the DWH spill on infaunal communities. Higher variance in macrofaunal abundance and diversity, and different community structure (higher multivariate dispersion) were associated with elevated hydrocarbon concentrations and contaminants at sites closest to the wellhead (MC294, MC297, and MC344), consistent with impacts from the spill. In contrast, variance in meiofaunal diversity was not significantly related to distance from the wellhead and no other community metric (e.g. density or multivariate dispersion) was correlated with contaminants or hydrocarbon concentrations. Concentrations of polycyclic aromatic hydrocarbons (PAH) provided the best statistical explanation for observed macrofaunal community structure, while depth and presence of fine-grained mud best explained meiofaunal community patterns. Impacts associated with contaminants from the DWH spill resulted in a patchwork pattern of infaunal community composition, diversity, and abundance, highlighting the role of variability as an indicator of disturbance. These data represent a useful baseline for tracking post-spill recovery of these deep-sea communities.

Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica

PubMed Central

Majewska, Roksana; Santoro, Mario; Bolaños, Federico; Chaves, Gerardo; De Stefano, Mario

2015-01-01

Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle’s (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal species was Stomatolepas elegans (Cirripedia). Diatom densities ranged from 8179 ± 750 to 27685 ± 4885 cells mm-2. Epizoic microalgae were either partly immersed or entirely encapsulated within an exopolymeric coat. The relatively low diatom species number, stable species composition and low inter-sample dissimilarities (14.4% on average) may indicate a mutualistic relationship between the epibiont and the basibiont. Dispersal of sea turtle diatoms is probably highly restricted and similar studies will help to understand both diatom diversity, evolution and biogeography, and sea turtle ecology and foraging strategies. PMID:26083535

Linkages between benthic macroinvertebrate assemblages and landscape stressors in the US Great Lakes

EPA Science Inventory

We used multiple linear regression analysis to investigate relationships between benthic macroinvertebrate assemblages in the nearshore region of the Laurentian Great Lakes and landscape characteristics in adjacent watersheds. Benthic invertebrate data were obtained from the 201...

The Northern Bering Sea: An Arctic Ecosystem in Change

NASA Astrophysics Data System (ADS)

Grebmeier, J. M.; Cooper, L. W.

2004-12-01

Arctic systems can be rich and diverse habitats for marine life in spite of the extreme cold environment. Benthic faunal populations and associated biogeochemical cycling processes are influenced by sea-ice extent, seawater hydrography (nutrients, salinity, temperature, currents), and water column production. Benthic organisms on the Arctic shelves and margins are long-term integrators of overlying water column processes. Because these organisms have adapted to living at cold extremes, it is reasonable to expect that these communities will be among the most susceptible to climate warming. Recent observations show that Arctic sea ice in the North American Arctic is melting and retreating northward earlier in the season and the timing of these events can have dramatic impacts on the biological system. Changes in overlying primary production, pelagic-benthic coupling, and benthic production and community structure can have cascading effects to higher trophic levels, particularly benthic feeders such as walruses, gray whales, and diving seaducks. Recent indicators of contemporary Arctic change in the northern Bering Sea include seawater warming and reduction in ice extent that coincide with our time-series studies of benthic clam population declines in the shallow northern Bering shelf in the 1990's. In addition, declines in benthic amphipod populations have also likely influenced the movement of feeding gray whales to areas north of Bering Strait during this same time period. Finally a potential consequence of seawater warming and reduced ice extent in the northern Bering Sea could be the northward movement of bottom feeding fish currently in the southern Bering Sea that prey on benthic fauna. This would increase the feeding pressure on the benthic prey base and enhance competition for this food source for benthic-feeding marine mammals and seabirds. This presentation will outline recent biological changes observed in the northern Bering Sea ecosystem as documented in a 20-yr environmental time-series in the Bering Strait region.

Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments.

PubMed

Belley, Rénald; Snelgrove, Paul V R; Archambault, Philippe; Juniper, S Kim

2016-01-01

The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor habitats should consider bottom water temperature variation. Bottom temperature has important implications for estimates of seasonal and spatial benthic flux variation, benthic-pelagic coupling, and impacts of predicted ocean warming at high latitudes.

Compliance of secondary production and eco-exergy as indicators of benthic macroinvertebrates assemblages' response to canopy cover conditions in Neotropical headwater streams.

PubMed

Linares, Marden Seabra; Callisto, Marcos; Marques, João Carlos

2018-02-01

Riparian vegetation cover influences benthic assemblages structure and functioning in headwater streams, as it regulates light availability and autochthonous primary production in these ecosystems.Secondary production, diversity, and exergy-based indicators were applied in capturing how riparian cover influences the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams. Four hypotheses were tested: (1) open canopy will determine the occurrence of higher diversity in benthic macroinvertebrate assemblages; (2) streams with open canopy will exhibit more complex benthic macroinvertebrate communities (in terms of information embedded in the organisms' biomass); (3) in streams with open canopy benthic macroinvertebrate assemblages will be more efficient in using the available resources to build structure, which will be reflected by higher eco-exergy values; (4) benthic assemblages in streams with open canopy will exhibit more secondary productivity. We selected eight non-impacted headwater streams, four shaded and four with open canopy, all located in the Neotropical savannah (Cerrado) of southeastern Brazil. Open canopy streams consistently exhibited significantly higher eco-exergy and instant secondary production values, exemplifying that these streams may support more complex and productive benthic macroinvertebrate assemblages. Nevertheless, diversity indices and specific eco-exergy were not significantly different in shaded and open canopy streams. Since all the studied streams were selected for being considered as non-impacted, this suggests that the potential represented by more available food resources was not used to build a more complex dissipative structure. These results illustrate the role and importance of the canopy cover characteristics on the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams, while autochthonous production appears to play a crucial role as food source for benthic macroinvertebrates. This study also highlights the possible application of thermodynamic based indicators as tools to guide environmental managers in developing and implementing policies in the neotropical savannah. Copyright © 2017 Elsevier B.V. All rights reserved.

Metal contamination in benthic macroinvertebrates in a sub-basin in the southeast of Brazil.

PubMed

Chiba, W A C; Passerini, M D; Tundisi, J G

2011-05-01

Benthic macroinvertebrates have many useful properties that make possible the use of these organisms as sentinel in biomonitoring programmes in freshwater. Combined with the characteristics of the water and sediment, benthic macroinvertebrates are potential indicators of environmental quality. Thus, the spatial occurrence of potentially toxic metals (Al, Zn, Cr, Co, Cu, Fe, Mn and Ni) in the water, sediment and benthic macroinvertebrates samples were investigated in a sub-basin in the southeast of Brazil in the city of São Carlos, São Paulo state, with the aim of verifying the metals and environment interaction with benthic communities regarding bioaccumulation. Hypothetically, there can be contamination by metals in the aquatic environment in the city due to lack of industrial effluent treatment. All samples were analysed by the USEPA adapted method and processed in an atomic absorption spectrophotometer. The sub-basin studied is contaminated by toxic metals in superficial water, sediment and benthic macroinvertebrates. The Bioaccumulation Factor showed a tendency for metal bioaccumulation by the benthic organisms for almost all the metal species. The results show a potential human and ecosystem health risk, contributing to metal contamination studies in aquatic environments in urban areas.

Lake Malawi cichlid evolution along a benthic/limnetic axis.

PubMed

Hulsey, C D; Roberts, R J; Loh, Y-H E; Rupp, M F; Streelman, J T

2013-07-01

Divergence along a benthic to limnetic habitat axis is ubiquitous in aquatic systems. However, this type of habitat divergence has largely been examined in low diversity, high latitude lake systems. In this study, we examined the importance of benthic and limnetic divergence within the incredibly species-rich radiation of Lake Malawi cichlid fishes. Using novel phylogenetic reconstructions, we provided a series of hypotheses regarding the evolutionary relationships among 24 benthic and limnetic species that suggests divergence along this axis has occurred multiple times within Lake Malawi cichlids. Because pectoral fin morphology is often associated with divergence along this habitat axis in other fish groups, we investigated divergence in pectoral fin muscles in these benthic and limnetic cichlid species. We showed that the eight pectoral fin muscles and fin area generally tended to evolve in a tightly correlated manner in the Lake Malawi cichlids. Additionally, we found that larger pectoral fin muscles are strongly associated with the independent evolution of the benthic feeding habit across this group of fish. Evolutionary specialization along a benthic/limnetic axis has occurred multiple times within this tropical lake radiation and has produced repeated convergent matching between exploitation of water column habitats and locomotory morphology.

Spatial and temporal distributions of benthic green macroalgae in Yaquina bay, Oregon

EPA Science Inventory

Coastal estuaries of Oregon, USA, typically support relatively large accumulations of benthic green macroalgae (BGM) during the summer/early fall growing season. This raises questions regarding possible (positive and negative) effects on eelgrass and benthic epifauna and infauna...

Benthic invertebrates of fixed sites in the western Lake Michigan drainages, Wisconsin and Michigan, 1993-95

USGS Publications Warehouse

Lenz, Bernard N.; Rheaume, S.J.

2000-01-01

This report describes the variability in family-level benthic-invertebrate population data and the reliability of the data as a water-quality indicator for 11 fixed surface-water sites in the Western Lake Michigan Drainages study area of the National Water-Quality Assessment Program. Benthic-invertebrate-community measures were computed for the following: number of individuals, Hilsenhoff’s Family-Level Biotic Index, number and percent EPT (Ephemeroptera, Plecoptera, and Tricoptera), Margalef’s Diversity Index, and mean tolerance value. Relations between these measures and environmental setting, habitat, and of chemical water quality are examined. Benthic-invertebrate communities varied greatly among fixed sites and within individual streams among multiple-reach and multiple-year sampling. The variations between multiple reaches and years were sometimes larger than those found between different fixed sites. Factors affecting benthic invertebrates included both habitat and chemical quality. Generally, fixed-site streams with the highest diversity, greatest number of benthic invertebrates, and those at which community measures indicated the best water quality also had the best habitat and chemical quality. Variations among reaches are most likely related to differences in habitat. Variations among years are most likely related to climatic changes, which create variations in flow and/or chemical quality. The variability in the data analyzed in this study shows how benthic invertebrates are affected by differences in both habitat and water quality, making them useful indicators of stream health; however, a single benthic-invertebrate sample alone cannot be relied upon to accurately describe water quality of the streams in this study. Benthic-invertebrate data contributed valuable information on the biological health of the 11 fixed sites when used as one of several data sources for assessing water quality.

Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

NASA Astrophysics Data System (ADS)

Stief, P.

2013-12-01

Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies reveal that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen.

Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

NASA Astrophysics Data System (ADS)

Stief, P.

2013-07-01

Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments often is enhanced even more than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies revealed that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen.

Trace metals, PCBs, and PAHs in benthic (epipelic) diatoms from intertidal sediments; a pilot study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stronkhorst, J.; Misdorp, R.; Vos, P.C.

1994-06-01

Intertidal sediments in many estuaries around the world have a history of contamination resulting from long term discharges of industrial, agricultural and domestic waste effluents. These contaminated sediments are now regarded as a major source of toxicants for bottom-related organisms which, in turn, may pass on certain contaminants (e.g. methylmercury, polychlorinated biphenyls (PCBs)) to organisms higher in the foodchain. Many studies have been conducted on the contamination of benthic macrofauna, estuarine fish and birds, but to our knowledge no research has yet been carried out on benthic diatoms which form the lowest trophic level of an intertidal ecosystem. Research onmore » the effects of micro-contaminants on primary producers in marine ecosystems is mainly performed with phytoplankton. In the estuaries of temperate regions, benthic diatoms make a significant contribution to primary production in the ecosystem and are predated especially by deposit feeding Polychaete and Mollusca. Knowledge of the level of contamination in benthic diatoms is of major importance to recognize possible effects on growth rate and species composition of the benthic diatom populations and to understand the accumulation of toxicants into the foodchain. For chemical analysis it is difficult to obtain [open quote]pure[close quote] samples of benthic diatoms because they form part of the sediment. A similar problem occurs with the sampling of phytoplankton in turbid estuarine waters. The aim of this pilot study was (a) to improve a trap technique to collect pure samples of benthic diatoms of at least 2 gram dry weight for analysis of trace metals, PCBs and polyaromatic hydrocarbons (PAHs) and (b) to compare the concentrations in benthic diatoms with levels in sediment and some bottom-related organisms. 16 refs., 2 figs., 2 tabs.« less

Trawl disturbance on benthic communities: chronic effects and experimental predictions.

PubMed

Hinz, Hilmar; Prieto, Virginia; Kaiser, Michel J

2009-04-01

Bottom trawling has widespread impacts on benthic communities and habitats. While the direct impacts of trawl disturbances on benthic communities have been extensively studied, the consequences from long-term chronic disturbances are less well understood. The response of benthic macrofauna to chronic otter-trawl disturbance from a Nephrops norvegicus (Norway lobster) fishery was investigated along a gradient of fishing intensity over a muddy fishing ground in the northeastern Irish Sea. Chronic otter trawling had a significant, negative effect on benthic infauna abundance, biomass, and species richness. Benthic epifauna abundance and species richness also showed a significant, negative response, while no such effect was evident for epibenthic biomass. Furthermore, chronic trawl disturbance led to clear changes in community composition of benthic infauna and epifauna. The results presented indicate that otter-trawl impacts are cumulative and can lead to profound changes in benthic communities, which may have far-reaching implications for the integrity of marine food webs. Studies investigating the short-term effects of fishing manipulations previously concluded that otter trawling on muddy substrates had only modest effects on the benthic biota. Hence, the results presented by this study highlight that data from experimental studies can not be readily extrapolated to an ecosystem level and that subtle cumulative effects may only become apparent when fishing disturbances are examined over larger spatial and temporal scales. Furthermore, this study shows that data on chronic effects of bottom trawling on the benthos will be vital in informing the recently advocated move toward an ecosystem approach in fisheries management. As bottom-trawl fisheries are expanding into ever deeper muddy habitats, the results presented here are an important step toward understanding the global ecosystem effects of bottom trawling.

Application of multiple index development approaches to benthic invertebrate data from the Virginian Biogeographic Province

EPA Science Inventory

Benthic invertebrate indices have commonly been utilized to assess benthic invertebrate communities. These indices have been constructed using different techniques, but have shown different levels of application success. For example, the EMAP Virginian Province Index did not pe...

Spatial Patterns of Subtidal Benthic Invertebrates and Environmental Factors in the Nearshore Gulf of Maine

EPA Science Inventory

The spatial patterns of subtidal benthic invertebrates and physical-chemical variables in the nearshore Gulf of Maine (Acadian Biogeographic Province) were studied to provide information needed to calibrate benthic indices of environmental condition, determine physical-chemical f...

Computer-Assisted Analysis of Near-Bottom Photos for Benthic Habitat Studies

DTIC Science & Technology

2006-09-01

navigated survey platform greatly increases the efficiency of image analysis and provides new insight about the relationships between benthic organisms...increase in the efficiency of image analysis for benthic habitat studies, and provides the opportunity to assess small scale spatial distribution of

RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA)

EPA Science Inventory

Streams and rivers in the California Central Valley Ecoregion have been substantially modified by human activities. This study examines distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of this region. Benthic...

INDEX OF ESTUARINE BENTHIC INTEGRITY FOR GULF OF MEXICO ESTUARIES

EPA Science Inventory

A benthic index for northern Gulf of Mexico estuaries has been developed and successfully validated by the Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Louisianian Province. The benthic index is a useful indicator of estuarine condition that provi...

The Power of Computer-aided Tomography to Investigate Marine Benthic Communities

EPA Science Inventory

Utilization of Computer-aided-Tomography (CT) technology is a powerful tool to investigate benthic communities in aquatic systems. In this presentation, we will attempt to summarize our 15 years of experience in developing specific CT methods and applications to marine benthic co...

Biodiversity loss in benthic macroinfaunal communities and its consequence for organic mercury trophic availability to benthivorous predators in the lower Hudson River estuary, USA.

PubMed

Goto, Daisuke; Wallace, William G

2009-12-01

Organic mercury such as methylmercury is not only one of the most toxic substances found in coastal ecosystems but also has high trophic transfer efficiency. In this study, we examined implications of chronically altered benthic macroinfaunal assemblages for organic mercury trophic availability (based on organic mercury intracellular partitioning) to their predators in the Arthur Kill-AK (New York, USA). Despite low species diversity, both density and biomass of benthic macroinvertebrates in AK were significantly higher than those at the reference site. Disproportionately high biomass of benthic macroinvertebrates (mostly polychaetes) in the northern AK resulted in a more than twofold increase ('ecological enrichment') in the trophically available organic mercury pool. These results suggest that altered benthic macroinfaunal community structure in AK may play an important role in organic mercury trophic availability at the base of benthic food webs and potentially in mercury biogeochemical cycling in this severely urbanized coastal ecosystem.

Carbon fate in a large temperate human-impacted river system: Focus on benthic dynamics

NASA Astrophysics Data System (ADS)

Vilmin, Lauriane; Flipo, Nicolas; Escoffier, Nicolas; Rocher, Vincent; Groleau, Alexis

2016-07-01

Fluvial networks play an important role in regional and global carbon (C) budgets. The Seine River, from the Paris urban area to the entrance of its estuary (220 km), is studied here as an example of a large human-impacted river system subject to temperate climatic conditions. We assess organic C (OC) budgets upstream and downstream from one of the world's largest wastewater treatment plants and for different hydrological conditions using a hydrobiogeochemical model. The fine representation of sediment accumulation on the river bed allows for the quantification of pelagic and benthic effects on OC export toward the estuary and on river metabolism (i.e., net CO2 production). OC export is significantly affected by benthic dynamics during the driest periods, when 25% of the inputs to the system is transformed or stored in the sediment layer. Benthic processes also substantially affect river metabolism under any hydrological condition. On average, benthic respiration accounts for one third of the total river respiration along the studied stretch (0.27 out of 0.86 g C m-2 d-1). Even though the importance of benthic processes was already acknowledged by the scientific community for headwater streams, these results stress the major influence of benthic dynamics, and thus of physical processes such as sedimentation and resuspension, on C cycling in downstream river systems. It opens the door to new developments in the quantification of C emissions by global models, whereby biogeochemical processing and benthic dynamics should be taken into account.

Role of macrofauna on benthic oxygen consumption in sandy sediments of a high-energy tidal beach

NASA Astrophysics Data System (ADS)

Charbonnier, Céline; Lavesque, Nicolas; Anschutz, Pierre; Bachelet, Guy; Lecroart, Pascal

2016-06-01

Sandy beaches exposed to tide and waves are characterized by low abundance and diversity of benthic macrofauna, because of high-energy conditions. This is the reason why there are few studies on benthic communities living in such highly dynamic environments. It has been shown recently that tidal sandy beaches may act as biogeochemical reactors. Marine organic matter that is supplied in the sand during each flood tide is efficiently mineralized through aerobic respiration. In order to quantify the role of macrofauna in the whole beach benthic respiration, we studied the macrofauna and the pore water oxygen content of an exposed sandy beach (Truc Vert, SW of France) during four seasons in 2011. The results showed that macrofauna was characterised by a low number of species of specialized organisms such as the crustaceans Eurydice naylori and Gastrosaccus spp. and the polychaetes Ophelia bicornis and Scolelepis squamata. The distribution and abundance of macrofauna were clearly affected by exposure degree and emersion time. The combined monitoring of benthic macrofauna and pore waters chemistry allowed us to estimate (1) the macrofauna oxygen uptake, calculated with a standard allometric relationship using biomass data, and (2) the total benthic oxygen uptake, calculated from the oxygen deficit measured in pore waters. This revealed that benthic macrofauna respiration represented a variable but low (<10%) contribution to the total benthic oxygen consumption. This suggests that oxygen was mainly consumed by microbial respiration.

Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels

USGS Publications Warehouse

Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

2010-01-01

Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

Benthic macroinvertebrate assemblages in the US nearshore zone of Lake Erie, 2009: Status and linkages to landscape-derived stressors

EPA Science Inventory

Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

Application of Multiple Index Development Approaches to Benthic Invertebrate Data from the Virginian Biogeographic Province (SETAC NA)

EPA Science Inventory

Benthic invertebrate indices have commonly been utilized to assess benthic invertebrate communities. These indices have been constructed using different techniques, but have shown different levels of application success. For example, the EMAP Virginian Province Index did not pe...

LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES

EPA Science Inventory

The community structure of benthic macroinvertebrates from estuaries along the Atlantic coast of North America from Cape Cod, MA, to Biscayne Bay, FL, were compared. Benthic data were collected over a 5 year period (1990 to 1995) by the U.S. Environmental Protection Agency's Envi...

The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river

USGS Publications Warehouse

Kennedy, Theodore A.; Yackulic, Charles B.; Cross, Wyatt F.; Grams, Paul E.; Yard, Michael D.; Copp, Adam J.

2014-01-01

1. Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (# m−3), but the factors that govern invertebrate drift in larger rivers remain poorly understood. For example, while large increases or decreases in discharge can lead to large increases in invertebrate drift, the role of smaller, incremental changes in discharge is poorly described. In addition, while we might expect invertebrate drift concentrations to be proportional to benthic densities (# m−2), the benthic–drift relation has not been rigorously evaluated. 2. Here, we develop a framework for modelling invertebrate drift that is derived from sediment transport studies. We use this framework to guide the analysis of high-resolution data sets of benthic density and drift concentration for four important invertebrate taxa from the Colorado River downstream of Glen Canyon Dam (mean daily discharge 325 m3 s−1) that were collected over 18 months and include multiple observations within days. Ramping of regulated flows on this river segment provides an experimental treatment that is repeated daily and allowed us to describe the functional relations between invertebrate drift and two primary controls, discharge and benthic densities. 3. Twofold daily variation in discharge resulted in a >10-fold increase in drift concentrations of benthic invertebrates associated with pools and detritus (i.e. Gammarus lacustris and Potamopyrgus antipodarum). In contrast, drift concentrations of sessile blackfly larvae (Simuliium arcticum), which are associated with high-velocity cobble microhabitats, decreased by over 80% as discharge doubled. Drift concentrations of Chironomidae increased proportional to discharge. 4. Drift of all four taxa was positively related to benthic density. Drift concentrations of Gammarus, Potamopyrgus and Chironomidae were proportional to benthic density. Drift concentrations of Simulium were positively related to benthic density, but the benthic–drift relation was less than proportional (i.e. a doubling of benthic density only led to a 40% increase in drift concentrations). 5. Our study demonstrates that invertebrate drift concentrations in the Colorado River are jointly controlled by discharge and benthic densities, but these controls operate at different timescales. Twofold daily variation in discharge associated with hydropeaking was the primary control on within-day variation in invertebrate drift concentrations. In contrast, benthic density, which varied 10- to 1000-fold among sampling dates, depending on the taxa, was the primary control on invertebrate drift concentrations over longer timescales (weeks to months).

History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

NASA Astrophysics Data System (ADS)

Dauvin, Jean-Claude

2015-06-01

Benthic studies in the English Channel (EC), a shallow megatidal and epicontinental sea, began in the 1960s and 1970s with the work of teams led by Norman Holme (UK) and Louis Cabioch (F). During this period, benthic sampling was mainly qualitative, i.e. using a device such as the 'Rallier du Baty' dredge in the case of the French team and a modified anchor dredge in the case of the British team. Studies were focused on acquiring knowledge of the main distributions of benthic communities and species. Surveys on the scale of the whole EC led to the recognition of general features and two main patterns were identified: 1) the role of hydrodynamics on the spatial distribution of sediment, benthic species and communities; 2) the presence of a west-east climatic gradient of faunal impoverishment. Benthic studies in the 1980s-1990s were focused on the beginning of the implementation of long-term survey at a limited number of sites to identify seasonal and multi-annual changes. In the first decade of the 2000s, the implementation of the European Water Framework Directive and the Marine Strategy Framework Directive to define the Ecological Quality Status of marine environments increased the need to acquire better information of the structure and functioning of benthic communities, since benthic species and habitats were recognised as good indicators of human pressure on marine ecosystems. Faced with the increase of human maritime activities, the appearance of invasive species and the need to preserve sensitive marine habitats, benthic studies have been focused on developing a 'toolkit' to help in the decision-making and planning for both sound governance and sustainable management of marine resources and human activities in the English Channel. Multidisciplinary approaches were used to differentiate habitats in a more precise detail. Both indirect (side-scan sonar, ROV) and direct (grab sampling with benthos identification and grain-size analyses) approaches were used and combined to allow the description of benthic habitats using numerous descriptors. These approaches were mainly applied on a local scale, leading to the identification of habitat mosaics mainly in coarse sands, gravels and pebbly areas which cover 80% of the EC seabed. They also allowed the enrichment of the EUNIS habitat classification for infralittoral and circalittoral zones taking into account the scale of observations of benthic habitats. Moreover, several recommendations for future benthic studies are proposed within a HABITAT approach.

Modeling Benthic Sediment Processes to Predict Water Quality and Ecology in Narragansett Bay

EPA Science Inventory

The benthic sediment acts as a huge reservoir of particulate and dissolved material (within interstitial water) which can contribute to loading of contaminants and nutrients to the water column. A benthic sediment model is presented in this report to predict spatial and temporal ...

Development of a National-Scale Indicator of Benthic Condition for the National Coastal Condition Assessment.

EPA Science Inventory

The US EPA has evaluated the application of a national-scale indicator of estuarine benthic condition for the National Coastal Condition Assessment (NCCA). Historically, in the National Coastal Condition Reports (NCCR I-IV), estuarine benthic condition was assessed by applying m...

BENTHIC NUTRIENT FLUX IN A SMALL ESTUARY IN NORTHWESTERNFLORIDA (USA)

EPA Science Inventory

Benthic Nutrient Flux in a Small Estuary in Northwestern Florida(USA).Gulf and Caribbean Research 18, 15-25, 2006.

Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2-+NO3-), phosphate (PO4-), and dissolved silica (DSi) were measured in Escambia Bay, an estuar...

CHANGES IN THE FRESHWATER BENTHIC COMMUNITY OF LAKE ONTARIO SINCE THE INVASION OF DREISSENA 1972-1997

EPA Science Inventory

Population changes of three major benthic taxa are discussed in relation to Dreissena spp. Lake Ontario was sampled pre-invasion (1972) and post-invasion (1994, 1997) for abundance of benthic organisms. In offshore sediments of Lake Ontario, neither species composition nor abunda...

Marine Benthic Communities of Block Island and Rhode Island Sounds and What they're Good For

EPA Science Inventory

The benthic invertebrates of Block Island and Rhode Island Sounds include those adapted to near-shore habitats with variable temperature and salinity, mid-shelf species with narrower requirements, and boreal species that avoid elevated temperatures. Studies of benthic fauna in th...

Coastal Benthic Optical Properties (CoBOP): Optical Properties of Benthic Marine Organisms and Substrates

DTIC Science & Technology

2001-09-30

significance of fluorescence and reflectance characteristics of benthic marine organisms in general, and coral reef cnidarians in particular. We wish to... cnidarians in particular. We wish to determine 1) how biological processes act to produce the optical properties and 2) how optical measurements can be

Explosive diversification following a benthic to pelagic shift in freshwater fishes.

PubMed

Hollingsworth, Phillip R; Simons, Andrew M; Fordyce, James A; Hulsey, C Darrin

2013-12-17

Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America's most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition in this group and generated fossil-calibrated estimates of when this shift occurred. This transition could have represented evolution into a novel adaptive zone, and therefore, we tested for a period of accelerated lineage accumulation after this historical habitat shift. Ancestral state reconstructions inferred a similar and concordant region of our mtDNA and nDNA based gene trees as representing the shift from benthic to pelagic habitats in the OPM clade. Two independent tests conducted on each gene tree suggested an increased diversification rate after this inferred habitat transition. Furthermore, lineage through time analyses indicated rapid early cladogenesis in the clade arising after the benthic to pelagic shift. A burst of diversification followed the earliest benthic to pelagic transition during the radiation of OPM cyprinids in eastern North America. As such, the benthic/pelagic habitat axis has likely influenced the generation of biodiversity across disparate freshwater ecosystems.

Microbial and sponge loops modify fish production in phase-shifting coral reefs.

PubMed

Silveira, Cynthia B; Silva-Lima, Arthur W; Francini-Filho, Ronaldo B; Marques, Jomar S M; Almeida, Marcelo G; Thompson, Cristiane C; Rezende, Carlos E; Paranhos, Rodolfo; Moura, Rodrigo L; Salomon, Paulo S; Thompson, Fabiano L

2015-10-01

Shifts from coral to algae dominance of corals reefs have been correlated to fish biomass loss and increased microbial metabolism. Here we investigated reef benthic and planktonic primary production, benthic dissolved organic carbon (DOC) release and bacterial growth efficiency in the Abrolhos Bank, South Atlantic. Benthic DOC release rates are higher while water column bacterial growth efficiency is lower at impacted reefs. A trophic model based on the benthic and planktonic primary production was able to predict the observed relative fish biomass in healthy reefs. In contrast, in impacted reefs, the observed omnivorous fish biomass is higher, while that of the herbivorous/coralivorous fish is lower than predicted by the primary production-based model. Incorporating recycling of benthic-derived carbon in the model through microbial and sponge loops explains the difference and predicts the relative fish biomass in both reef types. Increased benthic carbon release rates and bacterial carbon metabolism, but decreased bacterial growth efficiency could lead to carbon losses through respiration and account for the uncoupling of benthic and fish production in phase-shifting reefs. Carbon recycling by microbial and sponge loops seems to promote an increase of small-bodied fish productivity in phase-shifting coral reefs. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Lake Ontario benthic prey fish assessment, 2014

USGS Publications Warehouse

Weidel, Brian C.; Walsh, Maureen

2015-01-01

Benthic prey fishes are an important component of the Lake Ontario fish community and serve as vectors that move energy from benthic invertebrates into native and introduced sport fishes. Since the 1970’s, the USGS Lake Ontario Biological Station has assessed benthic fish populations and community dynamics with bottom trawls at depths ranging from 8 m out to depths of 150-225 m along the south and eastern shores of Lake Ontario. From the late 1970’s through the early 2000’s the benthic fish community was dominated by Slimy Sculpin Cottus cognatus, but in 2004 non-native Round Goby Neogobius melanostomus abundance increased and, since then Round Goby have generally been the dominant benthic species. Over the past 10 years the native Deepwater Sculpin Myoxocephalus thompsonii, once considered absent from the lake, have increased. Presently their lake-wide biomass density is equal to, or larger than, Slimy Sculpin. Species-specific assessments found Slimy and Deepwater Sculpin abundance increased slightly in 2014 relative to 2013, while changes in Round Goby abundance differed between spring and fall survey. Recent survey modifications have increased our understanding of benthic prey fish abundance and behavior in Lake Ontario. For instance, increasing the maximum tow depth to 225 m in 2014 improved our understanding of Deepwater Sculpin distribution in this rarely sampled lake habitat.

Effects of contrasting upwelling downwelling on benthic foraminiferal distribution in the Ría de Vigo (NW Spain)

NASA Astrophysics Data System (ADS)

Diz, Paula; Francés, Guillermo; Rosón, Gabriel

2006-04-01

Live benthic foraminifera in the superficial sediments from the muddy central axis of the Ría de Vigo were examined under two contrasting hydrographic conditions: downwelling and upwelling. During downwelling conditions the abundance of benthic foraminifera does not show large differences between sites with different organic carbon contents. The arrival of labile organic carbon to the seafloor delivered during upwelling events causes an increase in the abundance of the most significant species and the appearance of new species in the life assemblage. This suggests that benthic foraminiferal faunas strongly depend on high quality organic carbon supply and the sedimentary organic carbon is not a good indicator of food availability to benthic foraminifera. The response of benthic foraminifera to phytoplankton blooms differs between outer and inner sites. In outer and middle areas benthic foraminiferal assemblages show quick population growth in reaction to phytoplankton blooms (r-strategists), whereas in inner sites the most abundant species displays both growth and reproduction (k-strategists). It is suggested that r-strategy results of adaptation to perturbations on short time-scales (downwelling/upwelling cycles) under favourable microenvironmental conditions, while the k-strategy represents the adaptation to long term perturbations, such as relatively low oxygen concentrations and/or reducing microenvironmental conditions in the sediment.

Concentrations of selected heavy metals in benthic diatoms and sediment in the Westerschelde Estuary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Absil, M.C.P.; Scheppingen, Y. van

1996-12-31

In recent years considerable data have been compiled on heavy metal levels in biota in marine and estuarine environments. With respect to the fauna, much information is available on accumulation and effects of heavy metals in birds, fish and benthic macrofauna. Accumulation of heavy metals in aquatic flora has been studied mostly in benthic macroalgae, in particular in relation to the use as a biological monitor. The response of planktonic algal species to heavy metals has been studied extensively in cultured populations. Also. heavy metal concentrations in natural plankton have been studied. As far as we know, very few datamore » are available on the concentrations of heavy metals in the lowest benthic trophic level, the benthic microflora. It is a major food supply for numerous intertidal species, so it is obvious that microflora might play an important role in the accumulation of contaminants through coastal food chains. The aim of this research was to adjust a recently developed collection technique for benthic diatoms so that it is suitable for large-scale field studies. The method was then used to assess the concentration of the heavy metals Cd, Cu, Pb and Zn in benthic diatoms and sediments along an estuarine gradient. 18 refs., 2 figs., 1 tab.« less

Partitioning the contributions of mega-, macro- and meiofauna to benthic metabolism on the upper continental slope of New Zealand: Potential links with environmental factors and trawling intensity

NASA Astrophysics Data System (ADS)

Leduc, Daniel; Pilditch, Conrad A.; Nodder, Scott D.

2016-02-01

Understanding and predicting change in deep-sea benthic ecosystem function remains a major challenge. Here, we conducted analyses combining data on the abundance and biomass of benthic fauna and sediment community oxygen consumption (SCOC) on New Zealand's continental margin to estimate and compare the contributions of meio-, macro-, and megafauna to total benthic metabolism and identify potential links with environmental factors and trawling intensity. We focussed on two regions in close proximity-the high surface primary productivity Chatham Rise and low surface productivity Challenger Plateau. Mean megafauna biomass was twenty times greater on Chatham Rise than Challenger Plateau, likely reflecting differences in food supply between the two regions; this contrast in megafaunal biomass was mainly due to differences in mean body weight rather than abundance. Meio- and macrofauna made similar contributions to SCOC and together accounted for 12% of benthic metabolism on average. In contrast, the estimated contribution of megafauna never exceeded 1.5%. Significant positive correlations between faunal respiration and food availability indicate a link between food supply and benthic community function. Our analyses also show that fauna made a greater contribution to SCOC in conditions of high food availability, and that microorganisms (i.e., the proportion of SCOC not accounted for by the fauna) tended to be more dominant at sites with low food availability. These findings provide support for the concept that large organisms are more strongly affected by a reduction in food resources than small organisms, which in turn underlies one of the most widely described patterns in the deep-sea benthos, i.e., the reduction in organism body size with depth. Because metabolism in deep-sea sediments is typically dominated by microorganisms and small fauna, the absence of a relationship between bottom trawling intensity and the respiration of benthic fauna in the present study may be explained by benthic communities shifting towards smaller body size following physical disturbance. Future studies of deep-sea benthic ecosystem function will need to quantify the indirect influence of fauna on microbial metabolism through activities such as feeding and bioturbation in order to better understand the total contribution of benthic fauna to benthic processes.

Variability in benthic exchange rate, depth, and residence time beneath a shallow coastal estuary

NASA Astrophysics Data System (ADS)

Russoniello, C. J.; Michael, H. A.; Heiss, J.

2017-12-01

Hydrodynamically-driven exchange of water between the water column and shallow seabed aquifer, benthic exchange, is a significant and dynamic component of coastal and estuarine fluid budgets, but wave-induced benthic exchange has not been measured in the field. Mixing between surface water and groundwater solutes promotes ecologically important chemical reactions, so quantifying benthic exchange rates, depths, and residence times, constrains estimates of coastal chemical cycling. In this study, we present the first field-based direct measurements of wave-induced exchange and compare it to exchange induced by the other primary drivers of exchange - tides, and currents. We deployed instruments in a shallow estuary to measure benthic exchange and temporal variability over an 11-day period. Differential pressure sensors recorded pressure gradients across the seabed, and up-and down-looking ADCPs recorded currents and pressures from which wave parameters, surface-water currents, and water depth were determined. Wave-induced exchange was calculated directly from 1) differential pressure measurements, and indirectly with an analytical solution based on wave parameters from 2) ADCP and 3) weather station data. Groundwater flow models were used to assess the effects of aquifer properties on benthic exchange depth and residence time. Benthic exchange driven by tidal pumping or current-bedform interaction was calculated from tidal stage variation and from ADCP-measured currents at the bed, respectively. Waves were the primary benthic exchange driver (average = 20.0 cm/d, maximum = 92.3 cm/d) during the measurement period. Benthic exchange due to tides (average = 3.7 cm/d) and current-bedform interaction (average = 6.5x10-2 cm/d) was much lower. Wave-induced exchange calculated from pressure measurements and ADCP-measured wave parameters matched well, but wind-based rates underestimated wave energy and exchange. Groundwater models showed that residence time and depth increased in high-permeability, incompressible aquifers, and exchange rates increased in low-permeability, compressible aquifers. These findings support and extend the utility of existing wave-induced exchange solutions and will help managers assess the importance of benthic exchange on coastal chemical cycling.

Lake Ontario benthic prey fish assessment, 2016

USGS Publications Warehouse

Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

2017-01-01

Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Beginning in 1978, Lake Ontario benthic prey fishes were assessed using bottom trawls collected from the lake’s south shore (depth range: 8 – 150 m). Historically, the survey targeted the then dominant species, Slimy Sculpin, however in 2015, the Benthic Prey Fish Survey was cooperatively expanded to a whole-lake survey, to address resource management information needs related to Round Goby, Deepwater Sculpin, and nearshore native fishes. In 2016, 142 trawls were collected at 18 transects, and spanned depths from 6 – 225 m. Trawl catches indicated the benthic and demersal prey fish community was dominated by Round Goby, however the proportional importance of native Deepwater Sculpin is increasing. Species-specific assessments found lake-wide Round Goby density (~600 fish per hectare) was slightly lower in 2016 relative to 2015. Deepwater Sculpin density has generally increased since 2004. In 2016 their estimated density was greater than 100 fish per hectare. Slimy Sculpin density (15 fish/ha) was similar to the past 3 years. Catches of juvenile Slimy Sculpin continue to be low relative to historic catches and the timing of their decline coincides with the proliferation of Round Goby. Additionally, we found a strong negative relationship between trawl catches of Round Goby and near-shore native benthic and demersal fishes such as Trout-perch, Johnny Darter and Spottail Shiner. The introduction of Round Goby and the reappearance of native Deepwater Sculpin have shaped the Lake Ontario benthic prey fish community.

Benthic foraminifera at the Cretaceous-Tertiary boundary around the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Alegret, Laia; Molina, Eustoquio; Thomas, Ellen

2001-10-01

Cretaceous-Tertiary (K-T) boundary sections in northeastern Mexico contain marly formations separated by a controversial clastic unit. Benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls, with the exception of the upper bathyal northernmost section. Mixed neritic-bathyal faunas were present in the clastic unit, indicating redeposition in the deep basin by mass-wasting processes resulting from the K-T bolide impact in the Gulf of Mexico. Benthic foraminifera in the Mexican sections, and at other deep-sea locations, were not subject to major extinction at the time of impact, but there were temporary changes in assemblage composition. Benthic faunas indicate well- oxygenated bottom waters and mesotrophic conditions during the late Maastrichtian and increased food supply during the latest Maastrichtian. The food supply decreased drastically just after the K-T boundary, possibly because of the collapse of surface productivity. Cretaceous and early Paleogene benthic foraminifera, however, did not exhibit the benthic-pelagic coupling of present-day faunas, as documented by the lack of significant extinction at the K-T collapse of surface productivity. Much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions. The decrease in food supply at the K-T boundary might be associated with the processes of mass wasting, which removed surface, food-rich sediment. Benthic faunas show a staggered pattern of faunal recovery in the lowermost Paleogene, consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment.

Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

EPA Science Inventory

This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

BENTHIC MICROALGAL CONTROL ON THE NUTRIENT FLUX IN INTER-TIDAL FLATS OF THE LOWER YAQUINA ESTUARY, OREGON

EPA Science Inventory

Three sites were selected across the intertidal zone of the lower Yaquina Bay to investigate the role of benthic microalgae in benthic nutrient fluxes. Study sites were selected where microalage were present but without seagrass or mud shrimp. Sediment columns were collected th...

Development of a regional littoral benthic macroinvertebrate multi-metric index (MMI) for lakes from the National Lakes Assessment

EPA Science Inventory

During the 2007 National Lakes Assessment (NLA) benthic macroinvertebrate samples were collected from the lake littoral zone. The purpose of the sampling was to assess the feasibility of a multi-metric index (MMI) to assess the condition of the littoral benthic macroinvertebrate...

ALLOMETRIC LENGTH-WEIGHT RELATIONSHIPS FOR BENTHIC PREY OF AQUATIC WILDLIFE IN COASTAL MARINE HABITATS

EPA Science Inventory

We developed models to estimate the soft tissue content of benthic marine invertebrates that are prey for aquatic wildlife. Allometric regression models of tissue wet weight with shell length for 10 species of benthic invertebrates had r2 values ranging from 0.29 for hermit crabs...

Deep-Water Benthic Foraminifers from the Paleocene and Eocene of the North Pacific Region: Paleontology, Biostratigraphy, and Paleoceanological Reconstructions

NASA Astrophysics Data System (ADS)

Olshanetskiy, D. M.

2015-12-01

A zonal scheme for the Lower Paleogene of the northern Pacific Ocean is proposed on the basis of the stratigraphic distribution of benthic foraminifers in the lower bathyal-abyssal beds studied in boreholes in the North and South Pacific regions. This scheme includes eight subdivisions (six zones and two subzones). The boundaries of the benthic zonal subdivisions are defined by bioevents (appearance or disappearance of stratigraphically important taxa) and are linked to the zonal scales based on planktonic foraminifers and calcareous nannoplankton. It is established that most of these bioevents are recognized subglobally. Apart from the evolutionary events, changes in the deep-water benthic foraminiferal assemblages were caused by changes in the paleooceanological environment. This allowed detailed characterization of a global mass extinction of assemblages of deep-water benthic foraminifers in the region studied. It is also established that changes in the assemblages of deep-water benthic foraminifers, observed in either change in their taxonomic composition or changes in abundance and diversity, resulted from the presence of different deep-water masses in the region.

Taxonomic diversity and structure of benthic macroinvertebrates in Aby Lagoon (Ivory Coast, West Africa).

PubMed

Kouadio, K N; Diomandé, D; Ouattara, A; Koné, Y J M; Gourène, G

2008-09-15

The benthic macroinvertebrates of Aby lagoon (West Africa: Ivory coast) was studied during four seasons (high dry season, high rainy season, low dry season and low rainy season, respectively) from June 2006 to March 2007. The distribution of the benthic macroinvertebrates species was recorded at 13 stations on the whole of the lagoon. A total of 62 taxa of benthic macroinvertebrates belonging to 28 families and 10 orders were listed. The molluscs and crustaceans dominate qualitatively by adding up 51 and 24%, respectively of the total number of organisms. Five taxa (Corbula trigona (20%), Pachymelania aurita (12%), Clibernhardius cooki (7%), Oligochaeta (7%) and Crassostrea gasar (6%) accounted for 52% of total abundance. Classification analysis used to perform the characterisation of the lagoon on the basis of benthic macroinvertebrates showed the existence of four main clusters in which the seasonal pattern in benthic macroinvertebrates were very similar in the four seasons. In contrast the species richness and diversity indices were significantly different. Furthermore these indices where higher in the stations closer to the sea and surrounded by mangrove trees (southern area) compared to the inland ones.

Volume 90, Issue1 (February 2005)Articles in the Current Issue:Original PaperSeasonal Dynamics of Benthic and Planktonic Algae in a Nutrient-Rich Lowland River (Spree, Germany)

NASA Astrophysics Data System (ADS)

Werner, Petra; Köhler, Jan

2005-02-01

We studied chlorophyll a (chl. a), biovolume and species composition of benthic algae and phytoplankton in the eutrophic lower River Spree in 1996. The chl. a concentration was estimated as 3.5 (2.7-4.5) μg/cm2 for epipsammon, 9.4 (7.4-11.9) μg/cm2 for epipelon and 6.7 (5.7-7.8) μg/cm2 for the epilithon (median and 95% C. L.). The mean total biomass of benthic algae was significantly higher (6.0 μg chl. a/cm2) than the areal chl. a content of the pelagic zone (1.6 μg chl. a/cm²). Although certain phytoplankton taxa were abundant in the periphyton, benthic taxa generally dominated the assemblages. Seasonal dynamics of benthic algae were probably controlled by light and nitrate supply (sand), discharge fluctuations (sand, mud) and invertebrate grazing (stones). This paper shows the importance of benthic algae even in phytoplankton-rich lowland rivers with sandy or muddy sediments.

Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column

USGS Publications Warehouse

Topping, Brent R.; Kuwabara, James S.; Carter, James L.; Garrettt, Krista K.; Mruz, Eric; Piotter, Sarah; Takekawa, John Y.

2016-01-01

Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for more than a century. Long-term (decadal) salt pond restoration efforts began in 2003. A patented device for sampling porewater at varying depths, to calculate the gradient, was employed between 2010 and 2012. Within the former ponds, the benthic flux of soluble reactive phosphorus and that of dissolved ammonia were consistently positive (i.e., moving out of the sediment into the water column). The lack of measurable nitrate or nitrite concentration gradients across the sediment-water interface suggested negligible fluxes for dissolved nitrate and nitrite. The dominance of ammonia in the porewater indicated anoxic sediment conditions, even at only 1 cm depth, which is consistent with the observed, elevated sediment oxygen demand. Nearby openestuary sediments showed much lower benthic flux values for nutrients than the salt ponds under resortation. Allochthonous solute transport provides a nutrient advective flux for comparison to benthic flux. For ammonia, averaged for all sites and dates, benthic flux was about 80,000 kg/year, well above the advective flux range of −50 to 1500 kg/year, with much of the variability depending on the tidal cycle. By contrast, the average benthic flux of soluble reactive phosphorus was about 12,000 kg/year, of significant magnitude, but less than the advective flux range of 21,500 to 30,000 kg/year. These benthic flux estimates, based on solute diffusion across the sediment-water interface, reveal a significant nutrient source to the water column of the pond which stimulates algal blooms (often autotrophic). This benthic source may be augmented further by bioturbation, bioirrigation and episodic sediment resuspension events.

Consequences of Increasing Hypoxic Disturbance on Benthic Communities and Ecosystem Functioning

PubMed Central

Villnäs, Anna; Norkko, Joanna; Lukkari, Kaarina; Hewitt, Judi; Norkko, Alf

2012-01-01

Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota) effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface) by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days) in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH4 + and dissolved Si. Although effluxes of PO4 3− were not altered significantly, changes were observed in sediment PO4 3− sorption capability. The duration of hypoxia (i.e. number of days of stress) explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the benthic habitat matters, and that the link between biodiversity and ecosystem function is likely to be affected by a range of factors in complex, natural environments. PMID:23091592

Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity

PubMed Central

Haas, Andreas F.; Nelson, Craig E.; Wegley Kelly, Linda; Carlson, Craig A.; Rohwer, Forest; Leichter, James J.; Wyatt, Alex; Smith, Jennifer E.

2011-01-01

Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata – Ochrophyta; Amansia rhodantha – Rhodophyta; Halimeda opuntia – Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h−1 dm−2), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h−1) and concomitant oxygen drawdown (0.16±0.05 µmol L−1 h−1 dm−2). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef microbial dynamics and biogeochemical parameters (i.e., DOC and oxygen availability, bacterial abundance and metabolism) in coral reef communities. PMID:22125645

Do Changes in Current Flow as a Result of Arrays of Tidal Turbines Have an Effect on Benthic Communities?

PubMed

Kregting, Louise; Elsaesser, Bjoern; Kennedy, Robert; Smyth, David; O'Carroll, Jack; Savidge, Graham

2016-01-01

Arrays of tidal energy converters have the potential to provide clean renewable energy for future generations. Benthic communities may, however, be affected by changes in current speeds resulting from arrays of tidal converters located in areas characterised by strong currents. Current speed, together with bottom type and depth, strongly influence benthic community distributions; however the interaction of these factors in controlling benthic dynamics in high energy environments is poorly understood. The Strangford Lough Narrows, the location of SeaGen, the world's first single full-scale, grid-compliant tidal energy extractor, is characterised by spatially heterogenous high current flows. A hydrodynamic model was used to select a range of benthic community study sites that had median flow velocities between 1.5-2.4 m/s in a depth range of 25-30 m. 25 sites were sampled for macrobenthic community structure using drop down video survey to test the sensitivity of the distribution of benthic communities to changes in the flow field. A diverse range of species were recorded which were consistent with those for high current flow environments and corresponding to very tide-swept faunal communities in the EUNIS classification. However, over the velocity range investigated, no changes in benthic communities were observed. This suggested that the high physical disturbance associated with the high current flows in the Strangford Narrows reflected the opportunistic nature of the benthic species present with individuals being continuously and randomly affected by turbulent forces and physical damage. It is concluded that during operation, the removal of energy by marine tidal energy arrays in the far-field is unlikely to have a significant effect on benthic communities in high flow environments. The results are of major significance to developers and regulators in the tidal energy industry when considering the environmental impacts for site licences.

Spatial Variability of Benthic-Pelagic Coupling in an Estuary Ecosystem: Consequences for Microphytobenthos Resuspension Phenomenon

PubMed Central

Ubertini, Martin; Lefebvre, Sébastien; Gangnery, Aline; Grangeré, Karine; Le Gendre, Romain; Orvain, Francis

2012-01-01

The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in summer than in spring, in turn suggesting an important role of macrofauna bioturbation and filter feeding (Cerastoderma edule). PMID:22952910

Do Changes in Current Flow as a Result of Arrays of Tidal Turbines Have an Effect on Benthic Communities?

PubMed Central

Kregting, Louise; Elsaesser, Bjoern; Kennedy, Robert; Smyth, David; O’Carroll, Jack; Savidge, Graham

2016-01-01

Arrays of tidal energy converters have the potential to provide clean renewable energy for future generations. Benthic communities may, however, be affected by changes in current speeds resulting from arrays of tidal converters located in areas characterised by strong currents. Current speed, together with bottom type and depth, strongly influence benthic community distributions; however the interaction of these factors in controlling benthic dynamics in high energy environments is poorly understood. The Strangford Lough Narrows, the location of SeaGen, the world’s first single full-scale, grid-compliant tidal energy extractor, is characterised by spatially heterogenous high current flows. A hydrodynamic model was used to select a range of benthic community study sites that had median flow velocities between 1.5–2.4 m/s in a depth range of 25–30 m. 25 sites were sampled for macrobenthic community structure using drop down video survey to test the sensitivity of the distribution of benthic communities to changes in the flow field. A diverse range of species were recorded which were consistent with those for high current flow environments and corresponding to very tide-swept faunal communities in the EUNIS classification. However, over the velocity range investigated, no changes in benthic communities were observed. This suggested that the high physical disturbance associated with the high current flows in the Strangford Narrows reflected the opportunistic nature of the benthic species present with individuals being continuously and randomly affected by turbulent forces and physical damage. It is concluded that during operation, the removal of energy by marine tidal energy arrays in the far-field is unlikely to have a significant effect on benthic communities in high flow environments. The results are of major significance to developers and regulators in the tidal energy industry when considering the environmental impacts for site licences. PMID:27560657

Interpreting benthic oxygen levels in mudrocks: A new approach

NASA Astrophysics Data System (ADS)

Wignall, Paul B.; Myers, Keith J.

1988-05-01

Quantified paleoecology and gamma-ray spectrometry have been applied in the analysis of the Kimmeridge Clay, a highly organic-rich British Jurassic mudrock. Decreasing benthic oxygen trends are reflected in decreasing species richness and dominance-diversity values. Similarly, the degree of fragmentation of the benthos reflects the benthic energy levels and covaries with benthic oxygen. The calculation of authigenic uranium values from data gathered by gamma-ray spectrometry shows enrichment in more oxygen-deficient environments. The good correlation between the independently derived paleoecological and authigenic U data indicates the importance of these techniques in environmental analysis of marine petroleum source rocks.

Long-term benthic monitoring studies in the freshwater portion of the Potomac River - first annual report. Volume 3. Appendices. Report for September 1982-December 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vannote, R.L.; Sweeney, B.W.

1985-02-28

The report summarizes the results of the first year of a long-term study of the benthic macroinvertebrate fauna of the freshwater portion of the Potomac River extending from Dam No.5 near Williamsport, Maryland downstream to Seneca Pool near Seneca, Maryland. The primary objective of the study was to evaluate long-term trends in the distribution, abundance, and biomass of benthic macroinvertebrates and identify factors controlling the benthic populations, with particular emphasis on factors associated with existing power plant effluents within the study area.

Long-term benthic monitoring studies in the freshwater portion of the Potomac River - first annual report. Volume 1. Text. Report for September 1982-December 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vannote, R.L.; Sweeney, B.W.

1985-02-28

The report summarizes the results of the first year of a long-term study of the benthic macroinvertebrate fauna of the freshwater portion of the Potomac River extending from Dam No. 5 near Williamsport, Maryland downstream to Seneca Pool near Seneca, Maryland. The primary objective of the study was to evaluate long-term trends in the distribution, abundance, and biomass of benthic macroinvertebrates and identify factors controlling the benthic populations, with particular emphasis on factors associated with existing power plant effluents within the study area.

Gulf Coast Deep Water Port Facilities Study. Appendix C. Eastern Gulf Hydrobiological Zones.

DTIC Science & Technology

1973-04-01

MARINE 5IOTA C-22 1. Benthic Plants C-22 2. Plankton C;23 3. Benthic Invertebrates C-27 4. Fish C-33 5. Marine Mammals C-35 6. Marine Birds C-37 7. Rare...56 B. RESIDENT AND TRANSIENT MARINE BIOTA C-56 1. Plankton C-56 2. Benthic Invertebrates C-62 3. Fish C-62 4. Marine Mammals C-684 Artur D Little Inc...TRANSIENT MARINE BIOTA C-78 l.-Plankton C-78 .-2. Benthic Invertebrates C8 3. F ish C-81 4. Marine Mammals C-85 V. ZONAL ANALYSIS C-87 A. ZONE V

Preliminary results from a shallow water benthic grazing study

USGS Publications Warehouse

Jones, N.L.; Monismith, Stephen G.; Thompson, Janet K.

2005-01-01

Despite great improvements in our knowledge on the effects of benthic grazers on seston concentrations in water columns, the effects of different hydrodynamic conditions on grazing rates has not been formulated. This makes it difficult to assess the system-wide effect of the benthic ecosystem on phytoplankton concentrations. Furthermore, it affects our ability to predict the potential success of a benthic species, such as the invasive clams Corbicula fluminea and Potamocorbula amurensis. This paper presents the preliminary results of a control volume approach to elucidate the effect of different hydrodynamic conditions on the grazing rates of Corbicula fluminea.

Explosive diversification following a benthic to pelagic shift in freshwater fishes

PubMed Central

2013-01-01

Background Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America’s most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition in this group and generated fossil-calibrated estimates of when this shift occurred. This transition could have represented evolution into a novel adaptive zone, and therefore, we tested for a period of accelerated lineage accumulation after this historical habitat shift. Results Ancestral state reconstructions inferred a similar and concordant region of our mtDNA and nDNA based gene trees as representing the shift from benthic to pelagic habitats in the OPM clade. Two independent tests conducted on each gene tree suggested an increased diversification rate after this inferred habitat transition. Furthermore, lineage through time analyses indicated rapid early cladogenesis in the clade arising after the benthic to pelagic shift. Conclusions A burst of diversification followed the earliest benthic to pelagic transition during the radiation of OPM cyprinids in eastern North America. As such, the benthic/pelagic habitat axis has likely influenced the generation of biodiversity across disparate freshwater ecosystems. PMID:24341464

Assessing contamination in Great Lakes sediments using benthic invertebrate communities and the sediment quality triad approach

USGS Publications Warehouse

Canfield, Timothy J.; Dwyer, F. James; Fairchild, James F.; Haverland, Pamela S.; Ingersoll, Christopher G.; Kemble, Nile E.; Mount, David R.; La Point, Thomas W.; Burton, G. Allen; Swift, M. C.

1996-01-01

Sediments in many Great Lakes harbors and tributary rivers are contaminated. As part of the USEPA's Assessment and Remediation of Contaminated Sediment (ARCS) program, a number of studies were conducted to determine the nature and extent of sediment contamination in Great Lakes Areas of Concern (AOC). This paper describes the composition of benthic invertebrate communities in contaminated sediments and is one in a series of papers describing studies conducted to evaluate sediment toxicity from three AOC's (Buffalo River, NY; Indiana Harbor, IN; Saginaw River, MI), as part of the ARCS Program. Oligochaeta (worms) and Chironomidae (midge) comprised over 90% of the benthic invertebrate numbers in samples collected from depositional areas. Worms and midge consisted of taxa identified as primarily contaminant tolerant organisms. Structural deformities of mouthparts in midge larvae were pronounced in many of the samples. Good concurrence was evident between measures of laboratory toxicity, sediment contaminant concentration, and benthic invertebrate community composition in extremely contaminated samples. However, in moderately contaminated samples, less concordance was observed between the benthos community composition and either laboratory toxicity test results or sediment contaminant concentration. Laboratory sediment toxicity tests may better identify chemical contamination in sediments than many commonly used measures of benthic invertebrate community composition. Benthic measures may also reflect other factors such as habitat alteration. Evaluation of non-contaminant factors are needed to better interpret the response of benthic invertebrates to sediment contamination.

Benthic contributions to Adriatic and Mediterranean biogeochemical cycles

NASA Astrophysics Data System (ADS)

Capet, Arthur; Lazzari, Paolo; Spagnoli, Federico; Bolzon, Giorgio; Solidoro, Cosimo

2017-04-01

The 3D biogeochemical BFM-OGSTM implementation currently exploited operationally in the Copernicus Marine Environment Monitoring Services Mediterranean Sea Monitoring and Forecasting Centre (CMEMS-Med-MFC; Lazzari et al., 2010) has been complemented with a benthic component. The approach followed that of (Capet et al 2016) and involved a vertically integrated benthic module accounting for the effect of environmental bottom conditions on diagenetic rates (aerobic mineralization, denitrification, nitrification) through transfer functions as well as the effect of waves and bottom currents on sediment deposition and resuspension. A balanced climatological year is simulated for various values of the resuspension parameters, using specifically calibrated transfer functions for the Adriatic Sea and generic formulations for the rest of the Mediterranean basin. The results serves the mapping of distinct provinces of the Adriatic Sea based on the benthic contributions biogeochemical budgets and the seasonal variability of benthic-pelagic fluxes. The differences with the non-benthic reference simulation are highlighted in details regarding the Adriatic, and more generally for the entire Mediterranean Sea. Lazzari, P., Teruzzi, A., Salon, S., Campagna, S., Calonaci, C., Colella, S., Tonani, M., Crise, A. (2010). Pre-operational short-term forecasts for Mediterranean Sea biogeochemistry. Ocean Science, 6(1), 25-39. Capet, A., Meysman, F. J., Akoumianaki, I., Soetaert, K., & Grégoire, M. (2016). Integrating sediment biogeochemistry into 3D oceanic models: A study of benthic-pelagic coupling in the Black Sea. Ocean Modelling, 101, 83-100.

Global occurrence of pyrethroid insecticides in sediment and the associated toxicological effects on benthic invertebrates: An overview.

PubMed

Li, Huizhen; Cheng, Fei; Wei, Yanli; Lydy, Michael J; You, Jing

2017-02-15

Pyrethroids are the third most applied group of insecticides worldwide and are extensively used in agricultural and non-agricultural applications. Pyrethroids exhibit low toxicity to mammals, but have extremely high toxicity to fish and non-target invertebrates. Their high hydrophobicity, along with pseudo-persistence due to continuous input, indicates that pyrethroids will accumulate in sediment, pose long-term exposure concerns to benthic invertebrates and ultimately cause significant risk to benthic communities and aquatic ecosystems. The current review synthesizes the reported sediment concentrations of pyrethroids and associated toxicity to benthic invertebrates on a global scale. Geographically, the most studied area was North America, followed by Asia, Europe, Australia and Africa. Pyrethroids were frequently detected in both agricultural and urban sediments, and bifenthrin and cypermethrin were identified as the main contributors to toxicity in benthic invertebrates. Simulated hazard quotients (HQ) for sediment-associated pyrethroids to benthic organisms ranged from 10.5±31.1 (bifenthrin) to 41.7±204 (cypermethrin), suggesting significant risk. The current study has provided evidence that pyrethroids are not only commonly detected in the aquatic environment, but also can cause toxic effects to benthic invertebrates, and calls for better development of accurate sediment quality criteria and effective ecological risk assessment methods for this emerging class of insecticides. Copyright © 2016 Elsevier B.V. All rights reserved.

Associations between degraded benthic communities and contaminated sediments: Sabine Lake, Lake Pontchartrain, and Choctawhatchee Bay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engle, V.D.; Summers, J.K.; Macauley, J.M.

1994-12-31

The Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Gulf of Mexico supplements its base sampling effort each year with localized, intensive spatial sampling in selected large estuarine systems. By selecting random locations within 70 km{sup 2} hexagonal areas, individual estuaries were sampled using EMAP methods but at four times the density as base sampling. In 1992, 19 sites were sampled in Lake Pontchartrain, Louisiana. In 1 993, 18 sites were sampled in Sabine Lake, Texas and 12 sites were sampled in Choctawhatchee Bay, Florida. At all sites, sediment grabs were taken and analyzed for benthic species compositionmore » and abundance, for toxicity to Ampelisca, and for organic and inorganic sediment contaminants. An indicator of biotic integrity, the benthic index, was calculated to represent the status of benthic communities. A series of statistical techniques, such as stepwise regression analysis, were employed to determine whether the variation in the benthic index could be associated with variation in sediment contaminants, sediment toxicity, or levels of dissolved oxygen. Spatial distributions of these parameters were examined to determine the geographical co-occurrence of degraded benthic communities and environmental stressors. In Lake Pontchartrain, for example, 85% of the variation in the benthic index was associated with decreased levels of dissolved oxygen, and increased concentrations of PCBs, alkanes, copper, tin, and zinc in the sediments.« less

A Reverse Taxonomic Approach to Assess Macrofaunal Distribution Patterns in Abyssal Pacific Polymetallic Nodule Fields

PubMed Central

Janssen, Annika; Kaiser, Stefanie; Meißner, Karin; Brenke, Nils; Menot, Lenaick; Martínez Arbizu, Pedro

2015-01-01

Heightened interest in the exploitation of deep seafloor minerals is raising questions on the consequences for the resident fauna. Assessing species ranges and determination of processes underlying current species distributions are prerequisites to conservation planning and predicting faunal responses to changing environmental conditions. The abyssal central Pacific nodule belt, located between the Clarion and Clipperton Fracture Zones (CCZ), is an area prospected for mining of polymetallic nodules. We examined variations in genetic diversity and broad-scale connectivity of isopods and polychaetes across the CCZ. Faunal assemblages were studied from two mining claims (the eastern German and French license areas) located 1300 km apart and influenced by different productivity regimes. Using a reverse taxonomy approach based on DNA barcoding, we tested to what extent distance and large-scale changes in environmental parameters lead to differentiation in two macrofaunal taxa exhibiting different functions and life-history patterns. A fragment of the mitochondrial gene Cytochrome Oxidase Subunit 1 (COI) was analyzed. At a 97% threshold the molecular operational taxonomic units (MOTUs) corresponded well to morphological species. Molecular analyses indicated high local and regional diversity mostly because of large numbers of singletons in the samples. Consequently, variation in composition of genotypic clusters between sites was exceedingly large partly due to paucity of deep-sea sampling and faunal patchiness. A higher proportion of wide-ranging species in polychaetes was contrasted with mostly restricted distributions in isopods. Remarkably, several cryptic lineages appeared to be sympatric and occurred in taxa with putatively good dispersal abilities, whereas some brooding lineages revealed broad distributions across the CCZ. Geographic distance could explain variation in faunal connectivity between regions and sites to some extent, while assumed dispersal capabilities were not as important. PMID:25671322

Changes in deep-sea carbonate-hosted microbial communities associated with high and low methane flux

NASA Astrophysics Data System (ADS)

Case, D. H.; Steele, J. A.; Chadwick, G.; Mendoza, G. F.; Levin, L. A.; Orphan, V. J.

2012-12-01

Methane seeps on continental shelves are rich in authigenic carbonates built of methane-derived carbon. These authigenic carbonates are home to micro- and macroscopic communities whose compositions are thus far poorly constrained but are known to broadly depend on local methane flux. The formation of authigenic carbonates is itself a result of microbial metabolic activity, as associations of anaerobic methane oxidizing archaea (ANME) and sulfate reducing bacteria (SRB) in the sediment subsurface increase both dissolved inorganic carbon (DIC) and alkalinity in pore waters. This 1:1 increase in DIC and alkalinity promotes the precipitation of authigenic carbonates. In this study, we performed in situ manipulations to test the response of micro- and macrofaunal communities to a change in methane flux. Methane-derived authigenic carbonates from two locations at Hydrate Ridge, OR, USA (depth range 595-604 mbsl), were transplanted from "active" cold seep sites (high methane flux) to "inactive" background sites (low methane flux), and vise versa, for one year. Community diversity surveys using T-RFLP and 16S rRNA clone libraries revealed how both bacterial and archaeal assemblages respond to this change in local environment, specifically demonstrating reproducible shifts in different ANME groups (ANME-1 vs. ANME-2). Animal assemblage composition also shifted during transplantation; gastropod representation increased (relative to control rocks) when substrates were moved from inactive to active sites and polychaete, crustacean and echinoderm representation increased when substrates were moved from active to inactive sites. Combined with organic and inorganic carbon δ13C measurements and mineralogy, this unique in situ experiment demonstrates that authigenic carbonates are viable habitats, hosting microbial and macrofaunal communities capable of responding to changes in external environment over relatively short time periods.

Integrating Ecosystem Engineering and Food Web Ecology: Testing the Effect of Biogenic Reefs on the Food Web of a Soft-Bottom Intertidal Area

PubMed Central

De Smet, Bart; Fournier, Jérôme; De Troch, Marleen; Vincx, Magda; Vanaverbeke, Jan

2015-01-01

The potential of ecosystem engineers to modify the structure and dynamics of food webs has recently been hypothesised from a conceptual point of view. Empirical data on the integration of ecosystem engineers and food webs is however largely lacking. This paper investigates the hypothesised link based on a field sampling approach of intertidal biogenic aggregations created by the ecosystem engineer Lanice conchilega (Polychaeta, Terebellidae). The aggregations are known to have a considerable impact on the physical and biogeochemical characteristics of their environment and subsequently on the abundance and biomass of primary food sources and the macrofaunal (i.e. the macro-, hyper- and epibenthos) community. Therefore, we hypothesise that L. conchilega aggregations affect the structure, stability and isotopic niche of the consumer assemblage of a soft-bottom intertidal food web. Primary food sources and the bentho-pelagic consumer assemblage of a L. conchilega aggregation and a control area were sampled on two soft-bottom intertidal areas along the French coast and analysed for their stable isotopes. Despite the structural impacts of the ecosystem engineer on the associated macrofaunal community, the presence of L. conchilega aggregations only has a minor effect on the food web structure of soft-bottom intertidal areas. The isotopic niche width of the consumer communities of the L. conchilega aggregations and control areas are highly similar, implying that consumer taxa do not shift their diet when feeding in a L. conchilega aggregation. Besides, species packing and hence trophic redundancy were not affected, pointing to an unaltered stability of the food web in the presence of L. conchilega. PMID:26496349

An Anatomical Description of a Miniaturized Acorn Worm (Hemichordata, Enteropneusta) with Asexual Reproduction by Paratomy

PubMed Central

Worsaae, Katrine; Sterrer, Wolfgang; Kaul-Strehlow, Sabrina; Hay-Schmidt, Anders; Giribet, Gonzalo

2012-01-01

The interstitial environment of marine sandy bottoms is a nutrient-rich, sheltered habitat whilst at the same time also often a turbulent, space-limited, and ecologically challenging environment dominated by meiofauna. The interstitial fauna is one of the most diverse on earth and accommodates miniaturized representatives from many macrofaunal groups as well as several exclusively meiofaunal phyla. The colonization process of this environment, with the restrictions imposed by limited space and low Reynolds numbers, has selected for great morphological and behavioral changes as well as new life history strategies. Here we describe a new enteropneust species inhabiting the interstices among sand grains in shallow tropical waters of the West Atlantic. With a maximum body length of 0.6 mm, it is the first microscopic adult enteropneust known, a group otherwise ranging from 2 cm to 250 cm in adult size. Asexual reproduction by paratomy has been observed in this new species, a reproductive mode not previously reported among enteropneusts. Morphologically, Meioglossus psammophilus gen. et sp. nov. shows closest resemblance to an early juvenile stage of the acorn worm family Harrimaniidae, a result congruent with its phylogenetic placement based on molecular data. Its position, clearly nested within the larger macrofaunal hemichordates, suggests that this represents an extreme case of miniaturization. The evolutionary pathway to this simple or juvenile appearance, as chiefly demonstrated by its small size, dense ciliation, and single pair of gill pores, may be explained by progenesis. The finding of M. psammophilus gen. et sp. nov. underscores the notion that meiofauna may constitute a rich source of undiscovered metazoan diversity, possibly disguised as juveniles of other species. PMID:23144898

Utilization of shallow-water seagrass detritus by Carribbean deep-sea macrofauna: δ 13C evidence

NASA Astrophysics Data System (ADS)

Suchanek, Thomas H.; Williams, Susan L.; Ogden, John C.; Hubbard, Dennis K.; Gill, Ivan P.

1985-02-01

Three dives were made using the DSRV Alvin in the deep-sea basin north of St. Croix, Virgin Islands. Detrital seagrasses and macrofaunal distributions at 2455 to 3950 m depth were assessed quantitatively. Counts of the manatee grass Syringodium filiforme ( ca. 5 to 100 blades m -2) contrasted sharply with those of the turtle grass Thalassia testudinum ( ca. 0.1 to 2.0 blades m -2), reflecting an abundance proportional to previously reported export rates of the same species from Tague Bay, a nearby shallow source lagoon. Of the macrofaunal consumers that could potentially utilize this detrital nutrient source, three species of holothurians ( Mesothuria verrilli, Psychropotes semperiana, and Benthodytes linqua) and two species of sea urchins ( Hygrosoma petersi and Salencidaris profundi) were collected and/or observed. Gut content analyses revealed that all three holothurians deposit-feed on sediment and at least one species of sea urchin ( H. petersi) feeds almost exclusively on Syringodium. Carbon: nitrogen analyses of naturally occurring abyssal Thalassia detritus showed very low nitrogen content (0.21% N) and a high C:N ratio (214.8), thus yielding a loo nutritional value. Fresh Thalassia blades held in a litter bag experiment (by R. D. Turner) at 3950 m changed little in nitrogen content and C:N ratio after four years. A comparison was made of the stable carbon isotope ratios of 13C: 12C for abyssal seagrass detritus and other potential carbon sources with those for tissues from the holothurian and urchin consumers. The results indicate that a significant proportion of the nutrition of both groups is derived from detrital seagrasses either by direct consumption (sea urchins) or indirectly by deposit-feeding on sediments enriched by decomposed seagrasses (holothurians).

Influence of large woody debris on stream insect communities and benthic detritus

Treesearch

A. Dennis Lemly; Robert H. Hilderbrand

2000-01-01

We examined the extent to which benthic detritus loadings and the functional feeding group structure of stream insect communities respond to channel modifications produced by experimental addition of large woody debris (LWD, entire logs) to Stony Creek, VA. Benthic detritus loadings per sample did not change after LWD additions, but large increases in pool habitats...

Quantifying benthic nitrogen fluxes in Puget Sound, Washington: a review of available data

USGS Publications Warehouse

Sheibley, Richard W.; Paulson, Anthony J.

2014-01-01

Understanding benthic fluxes is important for understanding the fate of materials that settle to the Puget Sound, Washington, seafloor, as well as the impact these fluxes have on the chemical composition and biogeochemical cycles of marine waters. Existing approaches used to measure benthic nitrogen flux in Puget Sound and elsewhere were reviewed and summarized, and factors for considering each approach were evaluated. Factors for selecting an appropriate approach for gathering information about benthic flux include: availability of resources, objectives of projects, and determination of which processes each approach measures. An extensive search of literature was undertaken to summarize known benthic nitrogen fluxes in Puget Sound. A total of 138 individual flux chamber measurements and 38 sets of diffusive fluxes were compiled for this study. Of the diffusive fluxes, 35 new datasets were located, and new flux calculations are presented in this report. About 65 new diffusive flux calculations are provided across all nitrogen species (nitrate, NO3-; nitrite, NO2-; ammonium, NH4+). Data analysis of this newly compiled benthic flux dataset showed that fluxes beneath deep (greater than 50 meters) water tended to be lower than those beneath shallow (less than 50 meters) water. Additionally, variability in flux at the shallow depths was greater, possibly indicating a more dynamic interaction between the benthic and pelagic environments. The overall range of bottom temperatures from studies in the Puget Sound area were small (5–16 degrees Celsius), and only NH4+ flux showed any pattern with temperature. For NH4+, flux values and variability increased at greater than about 12 degrees Celsius. Collection of additional study site metadata about environmental factors (bottom temperature, depth, sediment porosity, sediment type, and sediment organic matter) will help with development of a broader regional understanding benthic nitrogen flux in the Puget Sound.

An Evaluation of Deep-Sea Benthic Megafaunal Communities in the Northern Gulf of Mexico Using Industrial ROVS and Video Imagery

NASA Astrophysics Data System (ADS)

Sharuga, S. M.; Benfield, M. C.

2016-02-01

The Deepwater Horizon oil spill in 2010 created a need for more thorough studies of deep-sea benthic biota, especially in soft-sediment areas of the Northern Gulf of Mexico (GoM). These benthic environments are increasingly vulnerable as demand and exploitation of resources in these areas grow. A 15°, 250 m long radial transect survey design was developed for use with industrial remotely operated vehicles (ROVs) to quantify benthic megafaunal communities in the vicinity of the MC252 well. Further, a customized database system was developed to explore natural and anthropogenic factors potentially responsible for influencing benthic megafaunal characteristics in this area. Biotic and abiotic characteristics were extracted from ROV videos collected one year after the Deepwater Horizon spill at seven study sites ranging from 2-39 km away from MC252, and located at depths from 850-1500 m. Seafloor environments differed amongst the sites, with differences found to be related to location and depth. Benthic megafauna in ten taxonomic categories were evaluated in order to compare benthic community characteristics, including density and diversity. Overall, community composition was found to be primarily related to depth and, to a lesser degree, site location. Results from this study suggest that depth, location, and the abiotic environment (ex. seafloor features, including anthropogenic disturbance) play important roles in the abundances and diversity of deep-sea benthic megafauna in the Northern GoM and should be considered when conducting environmental studies. This study demonstrates the utility of industrial-based deep-sea imaging platforms as a readily accessible option for collecting valuable information on deep-sea environments. These platforms exhibit excellent potential for use in determining baseline data and evaluating ecosystem changes and/or recovery.

Relationship between sedimentation rates and benthic impact on Maërl beds derived from fish farming in the Mediterranean.

PubMed

Sanz-Lázaro, Carlos; Belando, María Dolores; Marín-Guirao, Lázaro; Navarrete-Mier, Francisco; Marín, Arnaldo

2011-02-01

The aim of this work was to study the dispersion of particulate wastes derived from marine fish farming and correlate the data with the impact on the seabed. Carbon and nutrients were correlated with the physico-chemical parameters of the sediment and the benthic community structure. The sedimentation rates in the benthic system were 1.09, 0.09 and 0.13 g m⁻² day⁻¹ for particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP), respectively. TP was a reliable parameter for establishing the spatial extent of the fish farm particulate wastes. Fish farming was seen to influence not only physico-chemical and biological parameters but also the functioning of the ecosystem from a trophic point of view, particularly affecting the grazers and the balance among the trophic groups. POC, PON and TP sedimentation dynamics reflected the physico-chemical status of the sediment along the distance gradient studied, while their impact on the benthic community extended further. Therefore, the level of fish farm impact on the benthic community might be underestimated if it is assessed by merely taking into account data obtained from waste dispersion rates. The benthic habitat beneath the fish farm, Maërl bed, was seen to be very sensitive to aquaculture impact compared with other unvegetated benthic habitats, with an estimated POC-carrying capacity to maintain current diversity of 0.087 g C m⁻² day⁻¹ (only 36% greater than the basal POC input). Environmental protection agencies should define different aquaculture waste load thresholds for different benthic communities affected by finfish farming, according to their particular degree of sensitivity, in order to maintain natural ecosystem functions. © 2010 Elsevier Ltd. All rights reserved.

Benthic algal production across lake size gradients: interactions among morphometry, nutrients, and light.

PubMed

Vadeboncoeur, Yvonne; Peterson, Garry; Vander Zanden, M Jake; Kalff, Jacob

2008-09-01

Attached algae play a minor role in conceptual and empirical models of lake ecosystem function but paradoxically form the energetic base of food webs that support a wide variety of fishes. To explore the apparent mismatch between perceived limits on contributions of periphyton to whole-lake primary production and its importance to consumers, we modeled the contribution of periphyton to whole-ecosystem primary production across lake size, shape, and nutrient gradients. The distribution of available benthic habitat for periphyton is influenced by the ratio of mean depth to maximum depth (DR = z/ z(max)). We modeled total phytoplankton production from water-column nutrient availability, z, and light. Periphyton production was a function of light-saturated photosynthesis (BPmax) and light availability at depth. The model demonstrated that depth ratio (DR) and light attenuation strongly determined the maximum possible contribution of benthic algae to lake production, and the benthic proportion of whole-lake primary production (BPf) declined with increasing nutrients. Shallow lakes (z < or =5 m) were insensitive to DR and were dominated by either benthic or pelagic primary productivity depending on trophic status. Moderately deep oligotrophic lakes had substantial contributions by benthic primary productivity at low depth ratios and when maximum benthic photosynthesis was moderate or high. Extremely large, deep lakes always had low fractional contributions of benthic primary production. An analysis of the world's largest lakes showed that the shapes of natural lakes shift increasingly toward lower depth ratios with increasing depth, maximizing the potential importance of littoral primary production in large-lake food webs. The repeatedly demonstrated importance of periphyton to lake food webs may reflect the combination of low depth ratios and high light penetration characteristic of large, oligotrophic lakes that in turn lead to substantial contributions of periphyton to autochthonous production.

Effects of pulp mill effluent on benthic assemblages in mesocosms along the Saint John River, Canada.

PubMed

Culp, Joseph M; Cash, Kevin J; Glozier, Nancy E; Brua, Robert B

2003-12-01

We used mesocosms to examine the impact of different concentrations of pulp mill effluent (PME) on structural and functional endpoints of a benthic assemblage in the Saint John River (NB, Canada) during 1999 and 2000. Previous studies on this effluent's effects produced conflicting results, with field surveys suggesting a pattern of mild nutrient enrichment, while laboratory toxicity tests linked effluent exposure to moderate contaminant effects. Experimental treatments included three concentrations of sulfite pulp mill effluent (0, 5, 10% v/v PME). Endpoints for the assessment included algal biomass and taxonomic composition, benthic invertebrate abundance and composition, and insect emergence. Low concentrations of PME increased periphyton biomass and caused changes in community structure within the diatom-dominated community. Pulp mill effluent addition had little effect on several structural endpoints measured for benthic invertebrates, including abundance and taxonomic richness, but significantly changed community composition. For both periphyton and benthic invertebrates, community composition endpoints were more sensitive indicators of PME exposure. Insect emergence was a highly relevant functional endpoint. When benthic and emerged insects were combined, total abundance increased with PME addition. Results from two trophic levels, which provided multiple lines of evidence, indicated that the main impact of these PME concentrations is nutrient enrichment rather than effluent toxicity. Our findings also suggest that benthic invertebrate and periphyton assemblages, algal biomass production, and insect emergence are sensitive response measures. Future studies may confirm this observation. The consideration of both functional and structural endpoints at different trophic levels can greatly improve our understanding the effects of discharges to rivers. Such an understanding could not have been obtained using standard assessment techniques and illustrates the value of mesocosms and the benthic community assemblage approach in environmental assessment.

Species Composition and Habitat Associations of Benthic Algal Assemblages in Headwater Streams of the Sierra Nevada, California

Treesearch

Larry R. Brown; Jason T. May; Carolyn T. Hunsaker

2008-01-01

Despite their trophic importance and potential importance as bioindicators of stream condition, benthic algae have not been well studied in California. In particular there are few studies from small streams in the Sierra Nevada. The objective of this study was to determine the standing crop of chlorophyll-a and benthic algal species assemblages...

Fisheries Resource Utilization of an Estuarine Borrow Pit in Mobile Bay, Alabama

DTIC Science & Technology

2014-07-01

sampling indicated that both holes supported impoverished benthic assemblages comprised largely of opportunistic, disturbance- adapted infauna. Species...impoverished benthic assemblages comprised largely of opportunistic, disturbance- adapted infauna. The structure of the benthic communities differed...Total % AN Total % BN Gastropod - - - - - - 1 0.3 1 0.07 Total Animals 600 - 20 - 467 - 380 - 1467 - Average. # Animals 120 - 4 - 156 - 126

Benthic meiofauna responses to five forest harvest methods

Treesearch

Freese Smith; Arthur V. Brown; Misty Pope; Jerry L. Michael

2001-01-01

Benthic meiofauna were collected from the pools of minute (0 order) streams in the Ouachita National Forest, Arkansas during March 21-23, 1996 to see if benthic communities responded to forest harvest methods in a similar manner as plankton communities collected two years prior. The study streams and their watersheds (2-6 ha) were located in 14-16 ha forest stands that...

Long-term benthic monitoring studies in the freshwater portion of the Potomac River - first annual report. Volume 2. Tables and figures. Report for September 1982-December 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vannote, R.L.; Sweeney, B.W.

1985-02-28

The report summarizes the results of the first year of a long-term study of the benthic macroinvertebrate fauna of the freshwater portion of the Potomac River extending from Dam No. 5 near Williamsport, Maryland downstream to Seneca Pool near Seneca, Maryland. The primary objective of the study was to evaluate long-term trends in the distribution, abundance, and biomass of benthic macroinvertebrates and identify factors controlling the benthic populations, with particular emphasis on factors associated with existing power plant effluents within the study area.

In Situ and Ex Situ Estimates of Benthic Silica Fluxes in NGOM Shelf Sediments

NASA Astrophysics Data System (ADS)

Ebner, B. C.; Ghaisas, N. A.; Maiti, K.

2017-12-01

Biogenic silica (bSi), plays an important role in regulating primary productivity of diatoms in coastal and shelf ecosystems fed by major rivers. In the Northern Gulf of Mexico (NGOM), loading of nitrogen (N) and phosphorous (P) have increased compared to a decline in silicic acid in the Mississippi River (MR). Continued decreasing in silicic acid concentration could lead to limited diatom growth and production, therefore, it is important understand the role of benthic fluxes in providing silica to the overlying water column. The benthic flux of Si from shelf sediments can thus represent an important source of Si to be utilized by diatoms. Sediment core incubations and benthic chamber deployments were conducted at 5 sites in the Mississippi river plume with varying salinities during periods of high river discharge (May 2017), low river discharge (August 2016) and peak in hypoxia (July 2017). Preliminary data indicates large spatial and temporal variability in benthic silica fluxes ranging between 1.1 to 5.9 mmol/m2/d. This large variability in benthic silica flux is probably related to the seasonal changes in river discharge, primary production, community composition and sediment biogeochemistry in the region.

Differentiating responses to contaminants from responses to other environmental factors for benthic biota in freshwater ecosystems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Day, K.E.; Reynoldson, T.B.; Rosenberg, D.M.

1995-12-31

Many ecological risk assessments (ERAS) of lakes, rivers and streams compare measurements of benthic community structure in specific areas of contamination to similar measurements in reference or ``clean`` areas as a basis for determining impact. However, despite numerous studies documenting alterations of benthic communities as a result of stress, the success of correctly assessing the ``health`` or degradation of these communities depends on how well responses to contamination can be discriminated from responses to other environmental factors. It is important in the ERA process to adequately describe benthic communities and to determine how natural environmental factors (e.g., substrate particle sizemore » and texture, organic content, water quality, pH, seston, etc.) may be driving benthic community structure. This knowledge is particularly important when reference areas are distant from stressed areas. This presentation will provide an overview of the environmental factors that are important in structuring natural benthic communities in rivers and lakes and discuss approaches that may be useful in differentiating between natural variability and anthropogenic stress in ERA. Several case studies from the Laurentian Great Lakes and the Fraser River watershed in British Columbia will be discussed.« less

Regional benthic δ18O stacks with radiocarbon age models show Termination I onset differences of up to 4,000 years

NASA Astrophysics Data System (ADS)

Stern, J.; Lisiecki, L. E.

2013-12-01

The assumption of globally synchronous benthic foraminiferal δ18O changes is central to the development of global stacks (averages) and many other types of paleoclimate studies. However, a few well-dated individual benthic δ18O records have suggested the possibility of regional differences in the timing of Termination I (e.g., Skinner and Shackleton, 2005; Waelbroeck et al., 2011). These previous studies often used single core locations to describe vast areas of the ocean, so it has remained unclear whether the observed diachroneities are truly regional in scale or merely local. Here, we bridge the gap between global benthic δ18O stacks and individual records by presenting eight regional benthic δ18O stacks from 252 cores with age models based on a total of 776 planktonic foraminiferal radiocarbon dates from 61 of those cores. The earliest termination onset (beginning of deglacial benthic δ18O decrease) occurs in the intermediate South Atlantic stack at 18.5 kyr BP, shortly after the initial deglacial melting of Northern Hemisphere ice sheets. The latest termination onset occurs in the deep Indian stack at 14.5 kyr BP, coeval with the Bølling-Allerød warming. We find synchronous termination onsets at 17.5 kyr BP in the intermediate North Atlantic, deep North Atlantic, and deep South Atlantic, contrary to Waelbroeck et al. (2011). The deglacial benthic δ18O decrease in the deep Pacific lagged that of the deep Atlantic by an average of 1000 yr, with a maximum lag of ~1700 yr during the middle of the termination. The intermediate Pacific termination onset at 16.5 kyr BP happens 1000 yr after the deep Pacific termination onset at 17.5 kyr BP. The stacks extend beyond Termination I to ~40 kyr BP, allowing us to clarify and update certain aspects of millennial-scale benthic δ18O chronostratigraphy surrounding Heinrich events 2-3 and the transition into the Last Glacial Maximum. Our radiocarbon-dated regional benthic δ18O stacks demonstrate some of the limitations of benthic δ18O correlations while providing valuable regional-scale age models and constraints on water mass property and ocean circulation changes over the last ~40 kyr.

Harnessing the self-harvesting capability of benthic cyanobacteria for use in benthic photobioreactors

PubMed Central

2011-01-01

Benthic species of algae and cyanobacteria (i.e., those that grow on surfaces), may provide potential advantages over planktonic species for some commercial-scale biotechnological applications. A multitude of different designs of photobioreactor (PBR) are available for growing planktonic species but to date there has been little research on PBR for benthic algae or cyanobacteria. One notable advantage of some benthic cyanobacterial species is that during their growth cycle they become positively buoyant, detach from the growth surface and form floating mats. This 'self-harvesting' capability could be advantageous in commercial PBRs as it would greatly reduce dewatering costs. In this study we compared the growth rates and efficiency of 'self-harvesting' among three species of benthic cyanobacteria; Phormidium autumnale; Phormidium murrayi and Planktothrix sp.. Phormidium autumnale produced the greatest biomass and formed cohesive mats once detached. Using this strain and an optimised MLA media, a variety of geometries of benthic PBRs (bPBRs) were trialed. The geometry and composition of growth surface had a marked effect on cyanobacterial growth. The highest biomass was achieved in a bPBR comprising of a vertical polyethylene bag with loops of silicone tubing to provide additional growth surfaces. The productivity achieved in this bPBR was a similar order of magnitude as planktonic species, with the additional advantage that towards the end of the exponential phase the bulk of the biomass detached forming a dense mat at the surface of the medium. PMID:21906375

Reorganization of a marine trophic network along an inshore-offshore gradient due to stronger pelagic-benthic coupling in coastal areas

NASA Astrophysics Data System (ADS)

Kopp, Dorothée; Lefebvre, Sébastien; Cachera, Marie; Villanueva, Maria Ching; Ernande, Bruno

2015-01-01

Recent theoretical considerations have highlighted the importance of the pelagic-benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore-offshore gradient due to weakening of the pelagic-benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ13C and δ15N) to determine their trophic position. First, hierarchical clustering on δ13C and δ15N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers' diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore-offshore gradient. It showed stronger pelagic-benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers' δ13C and δ15N with depth. It detected a significant decrease in δ13C variance and a significant increase in δ15N variance as depth increases. A theoretical two-source mixing model showed that an inshore-offshore decrease in the pelagic-benthic coupling was a sufficient condition to produce the δ13C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore-offshore one should be accounted for to better understand marine food webs dynamics.

Benthic Habitat Mapping by Combining Lyzenga’s Optical Model and Relative Water Depth Model in Lintea Island, Southeast Sulawesi

NASA Astrophysics Data System (ADS)

Hafizt, M.; Manessa, M. D. M.; Adi, N. S.; Prayudha, B.

2017-12-01

Benthic habitat mapping using satellite data is one challenging task for practitioners and academician as benthic objects are covered by light-attenuating water column obscuring object discrimination. One common method to reduce this water-column effect is by using depth-invariant index (DII) image. However, the application of the correction in shallow coastal areas is challenging as a dark object such as seagrass could have a very low pixel value, preventing its reliable identification and classification. This limitation can be solved by specifically applying a classification process to areas with different water depth levels. The water depth level can be extracted from satellite imagery using Relative Water Depth Index (RWDI). This study proposed a new approach to improve the mapping accuracy, particularly for benthic dark objects by combining the DII of Lyzenga’s water column correction method and the RWDI of Stumpt’s method. This research was conducted in Lintea Island which has a high variation of benthic cover using Sentinel-2A imagery. To assess the effectiveness of the proposed new approach for benthic habitat mapping two different classification procedures are implemented. The first procedure is the commonly applied method in benthic habitat mapping where DII image is used as input data to all coastal area for image classification process regardless of depth variation. The second procedure is the proposed new approach where its initial step begins with the separation of the study area into shallow and deep waters using the RWDI image. Shallow area was then classified using the sunglint-corrected image as input data and the deep area was classified using DII image as input data. The final classification maps of those two areas were merged as a single benthic habitat map. A confusion matrix was then applied to evaluate the mapping accuracy of the final map. The result shows that the new proposed mapping approach can be used to map all benthic objects in all depth ranges and shows a better accuracy compared to that of classification map produced using only with DII.

Cross-channel variability in benthic habitat

USGS Publications Warehouse

Vayssieres, Marc; Peterson, Heather

2003-01-01

The Interagency Ecological Program’s Environmental Monitoring Program (EMP) has monitored benthic invertebrates since the mid-1970s. A recent review of the EMP found that the spatial study design of the benthos monitoring element was in need of a thorough reexamination through intense special studies and extensive historic data analyses. This article reports the results of preliminary analyses of historical EMP data focusing on cross-channel variability. Specific questions are: (1) do benthic habitats and community assemblages vary between positions across a river channel? (2) Are benthic samples taken at a single channel position sufficiently representative of benthos assemblages across the channel to characterize long term changes in the benthos community of a particular section of a river?

Benthic status of near-shore fishing grounds in the central Philippines and associated seahorse densities.

PubMed

Marcus, J E; Samoilys, M A; Meeuwig, J J; Villongco, Z A D; Vincent, A C J

2007-09-01

Benthic status of 28 near-shore, artisanal, coral reef fishing grounds in the central Philippines was assessed (2000-2002) together with surveys of the seahorse, Hippocampus comes. Our measures of benthic quality and seahorse densities reveal some of the most degraded coral reefs in the world. Abiotic structure dominated the fishing grounds: 69% of the benthos comprised rubble (32%), sand/silt (28%) and dead coral (9%). Predominant biotic structure included live coral (12%) and Sargassum (11%). Rubble cover increased with increasing distance from municipal enforcement centers and coincided with substantial blast fishing in this region of the Philippines. Over 2 years, we measured a significant decrease in benthic 'heterogeneity' and a 16% increase in rubble cover. Poor benthic quality was concomitant with extremely low seahorse densities (524 fish per km(2)). Spatial management, such as marine reserves, may help to minimize habitat damage and to rebuild depleted populations of seahorses and other reef fauna.

Seasonal variation of benthic macro invertebrates from Tons River of Garhwal Himalaya Uttarakhand.

PubMed

Negi, R K; Mamgain, Sheetal

2013-11-15

Present investigation was carried out to assess the seasonal variation of benthic macro-invertebrates from the Tons river, a tributary of Yamuna River in Garhwal Himalaya, Uttrakhand during December, 2007 to November, 2009. The seasonal benthic diversity was correlated with various physic-chemical parameters which documented that the macrobenthic diversity is mostly regulated by the dissolved oxygen in the water while temperature and free CO2 were found to be inversely correlated with the benthic fauna. Maximum diversity of benthos was reported at the upstream site ('H' 0.204) during the winter season while it was recorded minimum during the rainy season at all the sites. Maximum diversity is reported during the winter season at all the sites. The benthic fauna is represented by three phylum, 4 classes and 10 orders with Insecta emerging as the most dominant class. Maximum genera were reported from midstream site as it acts as ecotone between upstream and downstream.

Macroecological drivers of archaea and bacteria in benthic deep-sea ecosystems

PubMed Central

Danovaro, Roberto; Molari, Massimiliano; Corinaldesi, Cinzia; Dell’Anno, Antonio

2016-01-01

Bacteria and archaea dominate the biomass of benthic deep-sea ecosystems at all latitudes, playing a crucial role in global biogeochemical cycles, but their macroscale patterns and macroecological drivers are still largely unknown. We show the results of the most extensive field study conducted so far to investigate patterns and drivers of the distribution and structure of benthic prokaryote assemblages from 228 samples collected at latitudes comprising 34°N to 79°N, and from ca. 400- to 5570-m depth. We provide evidence that, in deep-sea ecosystems, benthic bacterial and archaeal abundances significantly increase from middle to high latitudes, with patterns more pronounced for archaea, and particularly for Marine Group I Thaumarchaeota. Our results also reveal that different microbial components show varying sensitivities to changes in temperature conditions and food supply. We conclude that climate change will primarily affect deep-sea benthic archaea, with important consequences on global biogeochemical cycles, particularly at high latitudes. PMID:27386507

Diel Variability in Seawater pH Relates to Calcification and Benthic Community Structure on Coral Reefs

PubMed Central

Martz, Todd R.; Brainard, Russell E.

2012-01-01

Community structure and assembly are determined in part by environmental heterogeneity. While reef-building corals respond negatively to warming (i.e. bleaching events) and ocean acidification (OA), the extent of present-day natural variability in pH on shallow reefs and ecological consequences for benthic assemblages is unknown. We documented high resolution temporal patterns in temperature and pH from three reefs in the central Pacific and examined how these data relate to community development and net accretion rates of early successional benthic organisms. These reefs experienced substantial diel fluctuations in temperature (0.78°C) and pH (>0.2) similar to the magnitude of ‘warming’ and ‘acidification’ expected over the next century. Where daily pH within the benthic boundary layer failed to exceed pelagic climatological seasonal lows, net accretion was slower and fleshy, non-calcifying benthic organisms dominated space. Thus, key aspects of coral reef ecosystem structure and function are presently related to natural diurnal variability in pH. PMID:22952785

Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

DTIC Science & Technology

2011-09-30

bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen. OBJECTIVES The next...reflectivity. We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. After...Graduate School of Oceanography / University of Rhode Island (GSO/URI) to identify the benthic microalgae in the samples. Following the untimely death of

Lake whitefish and lake herring population structure and niche in ten south-central Ontario lakes

USGS Publications Warehouse

Carl, Leon M.; McGuiness, Fiona

2006-01-01

This study compares simple fish communities of ten oligotrophic lakes in south-central Ontario. Species densities and population size structure vary significantly among these lake communities depending on fish species present beyond the littoral zone. Lake whitefish are fewer and larger in the presence of lake herring than in their absence. Diet analysis indicates that lake whitefish shift from feeding on both plankton and benthic prey when lake herring are absent to a primarily benthic feeding niche in the presence of lake herring. When benthic round whitefish are present, lake whitefish size and density decline and they move lower in the lake compared to round whitefish. Burbot are also fewer and larger in lakes with lake herring than in lakes without herring. Burbot, in turn, appear to influence the population structure of benthic coregonine species. Lower densities of benthic lake whitefish and round whitefish are found in lakes containing large benthic burbot than in lakes with either small burbot or where burbot are absent. Predation on the pelagic larvae of burbot and lake whitefish by planktivorous lake herring alters the size and age structure of these populations. As life history theory predicts, those species with poor larval survival appear to adopt a bet-hedging life history strategy of long-lived individuals as a reproductive reserve.

Impacts of trout predation on fitness of sympatric sticklebacks and their hybrids.

PubMed Central

Vamosi, Steven M; Schluter, Dolph

2002-01-01

Predation may be a significant factor in the divergence of sympatric species although its role has been largely overlooked. This study examines the consequences of predation on the fitness of a pair of lacustrine stickleback species (Gasterosteus aculeatus complex) and their F(1) hybrids. Benthic sticklebacks are found in the littoral zone of lakes associated with vegetation and bare sediments, whereas limnetic sticklebacks spend most of their lives in the pelagic zone. The cutthroat trout (Oncorhynchus clarki) is a major predator of sticklebacks and the only other fish species native to lakes containing both benthic and limnetic species. In pond experiments we found that the addition of these predators primarily impacted the survival of limnetics. By contrast, benthic survival was unaffected by trout addition. The result was that relative survival of benthics and limnetics was reversed in the presence of trout. The presence of trout had no effect on the rank order of parent species growth rates, with benthics always growing faster than limnetics. F(1) hybrids survived poorly relative to benthics and limnetics and their growth rates were intermediate regardless of treatment. The results implicate predation by trout in the divergence of the species but not through increased vulnerability of F(1) hybrids. PMID:12028775

HABITAT-SPECIFIC FORAGING AND SEX DETERMINE MERCURY CONCENTRATIONS IN SYMPATRIC BENTHIC AND LIMNETIC ECOTYPES OF THE THREESPINE STICKLEBACK

PubMed Central

Willacker, James J.; Von Hippel, Frank A.; Ackerly, Kerri L.; O’Hara, Todd M.

2013-01-01

Mercury (Hg) is a widespread environmental contaminant known for the neurotoxicity of its methylated forms, especially monomethylmercury, which bioaccumulates and biomagnifies in aquatic food webs. Mercury bioaccumulation and biomagnification rates are known to vary among species utilizing different food webs (benthic vs limnetic) within and between systems. The authors assessed whether carbon and nitrogen stable isotope values and total Hg (THg) concentrations differed between sympatric benthic and limnetic ecotypes and sexes of threespine stickleback fish (Gasterosteus aculeatus) from Benka Lake, Alaska, USA. The mean THg concentration in the limnetic ecotype was significantly higher (26 mg/kg dry wt, 16.1%) than that of the benthic ecotype. Trophic position and benthic carbon percentage utilized were both important determinants of THg concentration; however, the 2 variables were of approximately equal importance in females, whereas trophic position clearly explained more of the variance than benthic carbon percentage in males. Additionally, strong sex effects (45 mg/kg dry wt, 29.4%) were observed in both ecotypes, with female fish having lower THg concentrations than males. These results indicate that trophic ecology and sex are both important determinants of Hg contamination even within a single species and lake and likely play a role in governing Hg concentrations in higher trophic levels. PMID:23456641

Ecological health monitoring of the Mekong River by using benthic algae in 2003-2004

NASA Astrophysics Data System (ADS)

Kunpradid, T.

2005-05-01

The monitoring of ecological health of the Mekong River by using benthic algae was carried out from 2003 - 2004. Thirty sampling sites along the Mekong River and its tributaries were selected in Laos, Thailand, Cambodia and Veitnam. In this investigation, the distribution of some species of benthic algae in different environments revealed that there was a significant relationship in the presence of them to the water quality, and these species could be used as a potential biomonitor of water quality in the Mekong River. One hundred and eighty six species of benthic diatoms and 46 species of macroalgae were found. Some dominant species of benthic algae could be used as biomonitors to assess water quality. Hydrodictyon recticulatum and Microspora floccosa and indicated clean-moderate water quality; Audouinella cylindrica, Cladophora glomerata, Achnanthes inflate and Cymbella turgidula indicated moderate water quality; Stigeoclonium flagelliforum, Aulacoseira granulata and Cymbella tumida indicated moderate-polluted water quality and Caloglossa leprieurii, Gomphonema parvulum and Nitzschia clausii indicated polluted water quality. The ecological health assessment of the Mekong River by using the species of benthic algae as biomonitors reveled that in the upstream and tributaries revealed moderate water quality. In contrast, some sites in the lower Mekong showed moderate-polluted to polluted water quality.

Biodiversity on the Rocks: Macrofauna Inhabiting Authigenic Carbonate at Costa Rica Methane Seeps

PubMed Central

Levin, Lisa A.; Mendoza, Guillermo F.; Grupe, Benjamin M.; Gonzalez, Jennifer P.; Jellison, Brittany; Rouse, Greg; Thurber, Andrew R.; Waren, Anders

2015-01-01

Carbonate communities: The activity of anaerobic methane oxidizing microbes facilitates precipitation of vast quantities of authigenic carbonate at methane seeps. Here we demonstrate the significant role of carbonate rocks in promoting diversity by providing unique habitat and food resources for macrofaunal assemblages at seeps on the Costa Rica margin (400–1850 m). The attendant fauna is surprisingly similar to that in rocky intertidal shores, with numerous grazing gastropods (limpets and snails) as dominant taxa. However, the community feeds upon seep-associated microbes. Macrofaunal density, composition, and diversity on carbonates vary as a function of seepage activity, biogenic habitat and location. The macrofaunal community of carbonates at non-seeping (inactive) sites is strongly related to the hydrography (depth, temperature, O2) of overlying water, whereas the fauna at sites of active seepage is not. Densities are highest on active rocks from tubeworm bushes and mussel beds, particularly at the Mound 12 location (1000 m). Species diversity is higher on rocks exposed to active seepage, with multiple species of gastropods and polychaetes dominant, while crustaceans, cnidarians, and ophiuroids were better represented on rocks at inactive sites. Macro-infauna (larger than 0.3 mm) from tube cores taken in nearby seep sediments at comparable depths exhibited densities similar to those on carbonate rocks, but had lower diversity and different taxonomic composition. Seep sediments had higher densities of ampharetid, dorvilleid, hesionid, cirratulid and lacydoniid polychaetes, whereas carbonates had more gastropods, as well as syllid, chrysopetalid and polynoid polychaetes. Stable isotope signatures and metrics: The stable isotope signatures of carbonates were heterogeneous, as were the food sources and nutrition used by the animals. Carbonate δ13Cinorg values (mean = -26.98‰) ranged from -53.3‰ to +10.0‰, and were significantly heavier than carbonate δ13Corg (mean = -33.83‰), which ranged from -74.4‰ to -20.6‰. Invertebrates on carbonates had average δ13C (per rock) = -31.0‰ (range -18.5‰ to -46.5‰) and δ15N = 5.7‰ (range -4.5‰ to +13.4‰). Average δ13C values did not differ between active and inactive sites; carbonate fauna from both settings depend on chemosynthesis-based nutrition. Community metrics reflecting trophic diversity (SEAc, total Hull Area, ranges of δ13C and δ15N) and species packing (mean distance to centroid, nearest neighbor distance) also did not vary as a function of seepage activity or site. However, distinct isotopic signatures were observed among related, co-occurring species of gastropods and polychaetes, reflecting intense microbial resource partitioning. Overall, the substrate and nutritional heterogeneity introduced by authigenic seep carbonates act to promote diverse, uniquely adapted assemblages, even after seepage ceases. The macrofauna in these ecosystems remain largely overlooked in most surveys, but are major contributors to biodiversity of chemosynthetic ecosystems and the deep sea in general. PMID:26158723

Global assessment of benthic nepheloid layers and linkage with upper ocean dynamics

NASA Astrophysics Data System (ADS)

Gardner, Wilford D.; Richardson, Mary Jo; Mishonov, Alexey V.

2018-01-01

Global maps of the maximum bottom concentration, thickness, and integrated particle mass in benthic nepheloid layers are published here to support collaborations to understand deep ocean sediment dynamics, linkage with upper ocean dynamics, and assessing the potential for scavenging of adsorption-prone elements near the deep ocean seafloor. Mapping the intensity of benthic particle concentrations from natural oceanic processes also provides a baseline that will aid in quantifying the industrial impact of current and future deep-sea mining. Benthic nepheloid layers have been mapped using 6,392 full-depth profiles made during 64 cruises using our transmissometers mounted on CTDs in multiple national/international programs including WOCE, SAVE, JGOFS, CLIVAR-Repeat Hydrography, and GO-SHIP during the last four decades. Intense benthic nepheloid layers are found in areas where eddy kinetic energy in overlying waters, mean kinetic energy 50 m above bottom (mab), and energy dissipation in the bottom boundary layer are near the highest values in the ocean. Areas of intense benthic nepheloid layers include the Western North Atlantic, Argentine Basin in the South Atlantic, parts of the Southern Ocean and areas around South Africa. Benthic nepheloid layers are weak or absent in most of the Pacific, Indian, and Atlantic basins away from continental margins. High surface eddy kinetic energy is associated with the Kuroshio Current east of Japan. Data south of the Kuroshio show weak nepheloid layers, but no transmissometer data exist beneath the Kuroshio, a deficiency that should be remedied to increase understanding of eddy dynamics in un-sampled and under-sampled oceanic areas.

DNA extraction from benthic Cyanobacteria: comparative assessment and optimization.

PubMed

Gaget, V; Keulen, A; Lau, M; Monis, P; Brookes, J D

2017-01-01

Benthic Cyanobacteria produce toxic and odorous compounds similar to their planktonic counterparts, challenging the quality of drinking water supplies. The biofilm that benthic algae and other micro-organisms produce is a complex and protective matrix. Monitoring to determine the abundance and identification of Cyanobacteria, therefore, relies on molecular techniques, with the choice of DNA isolation technique critical. This study investigated which DNA extraction method is optimal for DNA recovery in order to guarantee the best DNA yield for PCR-based analysis of benthic Cyanobacteria. The conventional phenol-chloroform extraction method was compared with five commercial kits, with the addition of chemical and physical cell-lysis steps also trialled. The efficacy of the various methods was evaluated by measuring the quantity and quality of DNA by UV spectrophotometry and by quantitative PCR (qPCR) using Cyanobacteria-specific primers. The yield and quality of DNA retrieved with the commercial kits was significantly higher than that of DNA obtained with the phenol-chloroform protocol. Kits including a physical cell-lysis step, such as the MO BIO Power Soil and Biofilm kits, were the most efficient for DNA isolation from benthic Cyanobacteria. These commercial kits allow greater recovery and the elimination of dangerous chemicals for DNA extraction, making them the method of choice for the isolation of DNA from benthic mats. They also facilitate the extraction of DNA from benthic Cyanobacteria, which can help to improve the characterization of Cyanobacteria in environmental studies using qPCRs or population composition analysis using next-generation sequencing. © 2016 The Society for Applied Microbiology.

Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

NASA Astrophysics Data System (ADS)

Manasa, M.; Saraswat, Rajeev; Nigam, Rajiv

2016-04-01

Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, a few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold, hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinated foraminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperature and salinity. We conclude that the factors associated with freshwater influx affect the distribution of benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used to reconstruct past monsoon intensity from the Bay of Bengal.

Benthic Light Availability Improves Predictions of Riverine Primary Production

NASA Astrophysics Data System (ADS)

Kirk, L.; Cohen, M. J.

2017-12-01

Light is a fundamental control on photosynthesis, and often the only control strongly correlated with gross primary production (GPP) in streams and rivers; yet it has received far less attention than nutrients. Because benthic light is difficult to measure in situ, surrogates such as open sky irradiance are often used. Several studies have now refined methods to quantify canopy and water column attenuation of open sky light in order to estimate the amount of light that actually reaches the benthos. Given the additional effort that measuring benthic light requires, we should ask if benthic light always improves our predictions of GPP compared to just open sky irradiance. We use long-term, high-resolution dissolved oxygen, turbidity, dissolved organic matter (fDOM), and irradiance data from streams and rivers in north-central Florida, US across gradients of size and color to build statistical models of benthic light that predict GPP. Preliminary results on a large, clear river show only modest model improvements over open sky irradiance, even in heavily canopied reaches with pulses of tannic water. However, in another spring-fed river with greater connectivity to adjacent wetlands - and hence larger, more frequent pulses of tannic water - the model improved dramatically with the inclusion of fDOM (model R2 improved from 0.28 to 0.68). River shade modeling efforts also suggest that knowing benthic light will greatly enhance our ability to predict GPP in narrower, forested streams flowing in particular directions. Our objective is to outline conditions where an assessment of benthic light conditions would be necessary for riverine metabolism studies or management strategies.

Incorporating benthic community changes into hydrochemical-based projections of coral reef calcium carbonate production under ocean acidification

NASA Astrophysics Data System (ADS)

Shaw, Emily C.; Hamylton, Sarah M.; Phinn, Stuart R.

2016-06-01

The existence of coral reefs is dependent on the production and maintenance of calcium carbonate (CaCO3) framework that is produced through calcification. The net production of CaCO3 will likely decline in the future, from both declining net calcification rates (decreasing calcification and increasing dissolution) and shifts in benthic community composition from calcifying organisms to non-calcifying organisms. Here, we present a framework for hydrochemical studies that allows both declining net calcification rates and changes in benthic community composition to be incorporated into projections of coral reef CaCO3 production. The framework involves upscaling net calcification rates for each benthic community type using mapped proportional cover of the benthic communities. This upscaling process was applied to the reef flats at One Tree and Lady Elliot reefs (Great Barrier Reef) and Shiraho Reef (Okinawa), and compared to existing data. Future CaCO3 budgets were projected for Lady Elliot Reef, predicting a decline of 53 % from the present value by end-century (800 ppm CO2) without any changes to benthic community composition. A further 5.7 % decline in net CaCO3 production is expected for each 10 % decline in calcifier cover, and net dissolution is predicted by end-century if calcifier cover drops below 18 % of the present extent. These results show the combined negative effect of both declining net calcification rates and changing benthic community composition on reefs and the importance of considering both processes for determining future reef CaCO3 production.

Rates of total oxygen uptake of sediments and benthic nutrient fluxes measured using an in situ autonomous benthic chamber in the sediment of the slope off the southwestern part of Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Lee, Jae Seong; An, Sung-Uk; Park, Young-Gyu; Kim, Eunsoo; Kim, Dongseon; Kwon, Jung No; Kang, Dong-Jin; Noh, Jae-Hoon

2015-09-01

We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) Belc II and Belp II. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m-2 d-1 and 3.77 mmol m-2 d-1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment-water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge-slope-basin system in the East Sea.

Rates of total oxygen uptake of sediments and benthic nutrient fluxes measured by an in situ autonomous benthic chamber in the sediment of the slope off the southwestern part of Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Lee, J. S.; An, S. U.; Park, Y. G.; Kim, E.; Kim, D.; Kwon, J. N.; Kang, D. J.; Noh, J. H.

2016-02-01

We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) BelcII and BelpII. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m-2 d-1 and 3.77 mmol m-2 d-1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment-water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge- slope-basin system in the East Sea.

An evaluation of benthic community measures using laboratory-derived sediment effect concentrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dwyer, F.J.; Canfield, T.J.; Ingersoll, C.G.

1995-12-31

Sediment effect concentrations (SECs) are contaminant sediment concentrations which are frequently associated with sediment toxicity. Recently, a number of different SECs have been calculated from laboratory toxicity tests with field collected sediments using Chironomus tentans, Chironomus riparius, and Hyalella azteca. Toxicity endpoints included (depending upon species) lethality, growth and sexual maturation. The authors selected the Effect Range Median (ERM) calculated for 28-d Hyalella azteca as an SEC for evaluating six different benthic community measures as indicators of contaminated sediment. The benthic measures included: taxa richness, chironomid genera richness, percent chironomid deformity, chironomid biotic index, ratio of chironomids/oligochaetes, and oligochaete bioticmore » index. Benthic measures were obtained for 31 stations from the Great Lakes and 13 stations from Milltown Reservoir and Clark Fork River, MT. Each benthic measure was ranked from 1 to 100 and individual ranks and various combinations of ranks were plotted against the ratio of chemical concentration at the site/ERM calculated for that chemical (similar to a toxic unit approach) and the sum of the ERM ratios (sum of toxic units). Preliminary analysis indicates that, in general, benthic measures varied widely in relatively uncontaminated stations, confounding any underlying relationship that may have existed. The absence of chironomids, in areas with suitable habitat, seems to be indicative of grossly contaminated stations, but not an endpoint useful for discriminating stations with contaminant concentrations closer to the SEC. The usefulness of benthic measures as diagnostic tools for contaminated sediments and potential ways to improve these measures will be discussed.« less

Benthic marine calcifiers coexist with CaCO3-undersaturated seawater worldwide

NASA Astrophysics Data System (ADS)

Lebrato, M.; Andersson, A. J.; Ries, J. B.; Aronson, R. B.; Lamare, M. D.; Koeve, W.; Oschlies, A.; Iglesias-Rodriguez, M. D.; Thatje, S.; Amsler, M.; Vos, S. C.; Jones, D. O. B.; Ruhl, H. A.; Gates, A. R.; McClintock, J. B.

2016-07-01

Ocean acidification and decreasing seawater saturation state with respect to calcium carbonate (CaCO3) minerals have raised concerns about the consequences to marine organisms that build CaCO3 structures. A large proportion of benthic marine calcifiers incorporate Mg2+ into their skeletons (Mg-calcite), which, in general, reduces mineral stability. The relative vulnerability of some marine calcifiers to ocean acidification appears linked to the relative solubility of their shell or skeletal mineralogy, although some organisms have sophisticated mechanisms for constructing and maintaining their CaCO3 structures causing deviation from this dependence. Nevertheless, few studies consider seawater saturation state with respect to the actual Mg-calcite mineralogy (ΩMg-x) of a species when evaluating the effect of ocean acidification on that species. Here, a global dataset of skeletal mole % MgCO3 of benthic calcifiers and in situ environmental conditions spanning a depth range of 0 m (subtidal/neritic) to 5600 m (abyssal) was assembled to calculate in situ ΩMg-x. This analysis shows that 24% of the studied benthic calcifiers currently experience seawater mineral undersaturation (ΩMg-x < 1). As a result of ongoing anthropogenic ocean acidification over the next 200 to 3000 years, the predicted decrease in seawater mineral saturation will expose approximately 57% of all studied benthic calcifying species to seawater undersaturation. These observations reveal a surprisingly high proportion of benthic marine calcifiers exposed to seawater that is undersaturated with respect to their skeletal mineralogy, underscoring the importance of using species-specific seawater mineral saturation states when investigating the impact of CO2-induced ocean acidification on benthic marine calcification.

Growth, physiochemical and antioxidant responses of overwintering benthic cyanobacteria to hydrogen peroxide.

PubMed

Chen, Chao; Yang, Zhen; Kong, Fanxiang; Zhang, Min; Yu, Yang; Shi, Xiaoli

2016-12-01

The recruitment of overwintering benthic cyanobacteria from the sediment surface is important for the development of cyanobacterial blooms during warm spring seasons. Thus, controlling the growth of cyanobacteria at the benthic stage to inhibit their recruitment is vital to control or delay the formation of summer blooms. In this study, overwintering benthic cyanobacteria were exposed to ascending hydrogen peroxide (H 2 O 2 ) concentrations (0, 1, 5, and 20 mg/L) in a simulated overwintering environment. Photosynthetic pigments, physiochemical features, and antioxidant responses were evaluated to determine the inhibitory effects of H 2 O 2 on the growth of benthic cyanobacteria and to identify the potential mechanisms thereof. These H 2 O 2 -treated cyanobacteria were then collected through filtration and transferred to an optimum environment to evaluate their recovery capacity. The results showed that chlorophyll a and phycocyanin contents, photosynthetic yield, and esterase activity decreased significantly in H 2 O 2 treated groups compared to the control. The activities of superoxide dismutase (SOD) and catalase (CAT) in benthic cyanobacteria were inhibited after 72 h exposure to H 2 O 2 , while the malondialdehyde (MDA) contents were stimulated at the same time. These results indicate that H 2 O 2 can inhibit the growth of benthic cyanobacteria, and H 2 O 2 -induced oxidative damage might be one of the mechanisms involved. The recovery experiment showed that the impairment of benthic cyanobacteria was temporary at a low dose of 1 mg/L H 2 O 2 , but permanent damage was induced when H 2 O 2 concentrations were increased to 5 and 20 mg/L. Overall, our results highlight that H 2 O 2 is a potential cyanobacteria inhibitor and can be used to decreasing the biomass of overwintering cyanobacteria, and could further control the intensity of cyanobacteria during the growth seasons. Copyright © 2016. Published by Elsevier Ltd.

Seafloor Mapping and Benthic Habitats off Assateague Island National Seashore: can we Resolve any Effects of Superstorm Sandy?

NASA Astrophysics Data System (ADS)

Miller, D.; Trembanis, A. C.; Kennedy, E.; Rusch, H.; Rothermel, E.

2016-02-01

The National Park Service has partnered with faculty and students at the University of Delaware to map the length of Assateague Island and sample benthic communities there for two purposes: (1) to provide a complete inventory of benthic habitats and their biota, and (2) to determine if any changes from a pre-storm survey can be ascribed to Superstorm Sandy in 2012. During the 2014 and 2015 field seasons over 75 km2 of high-resolution ( 50 cm/pixel) side-scan sonar and collocated bathymetry were collected with a surface vessel mounted bathy side-scan sonar (EdgeTech 6205), spanning the shore from depths of less than 2 m out to a distance of approximately 1 nautical mile and depths of 10-12 m. Furthermore, we have resampled using standard methodology (modified Young grab and 0.5-mm sieve) a subset of the previously sampled benthic stations that represent all sediment classes identified in prior studies. Additionally, we have obtained novel data with our ROV and AUV assets, including finer scale bottom video and multibeam bathymetry, at specifically chosen locations in order to enhance understanding of the benthic habitat and bottom type changes. In addition to providing a habitat and faunal inventory for resource management purposes, we will compare our side scan and benthic survey data to the pre-storm 2011 data products with comparable coverage. To date we have found that ArcGIS and ENVI sediment classifications agree well with those from the 2011 study, but spatially we note more areas of finer sediments and less of gravel. As was expected, 2014 benthic assemblages differ significantly among sediment classes (PRIMER ANOSIM), and sediment class is the best predictor of the benthic community (PERMANOVA+ distance-based RDA). Our goal here is to use consistent analytical approaches to characterize changes that occur over season and inter-annual time scales. This is a critical step toward attributing sediment, habitat and biological changes to Superstorm Sandy.

Benthic N2 fixation in coral reefs and the potential effects of human-induced environmental change

PubMed Central

Cardini, Ulisse; Bednarz, Vanessa N; Foster, Rachel A; Wild, Christian

2014-01-01

Tropical coral reefs are among the most productive and diverse ecosystems, despite being surrounded by ocean waters where nutrients are in short supply. Benthic dinitrogen (N2) fixation is a significant internal source of “new” nitrogen (N) in reef ecosystems, but related information appears to be sparse. Here, we review the current state (and gaps) of knowledge on N2 fixation associated with coral reef organisms and their ecosystems. By summarizing the existing literature, we show that benthic N2 fixation is an omnipresent process in tropical reef environments. Highest N2 fixation rates are detected in reef-associated cyanobacterial mats and sea grass meadows, clearly showing the significance of these functional groups, if present, to the input of new N in reef ecosystems. Nonetheless, key benthic organisms such as hard corals also importantly contribute to benthic N2 fixation in the reef. Given the usually high coral coverage of healthy reef systems, these results indicate that benthic symbiotic associations may be more important than previously thought. In fact, mutualisms between carbon (C) and N2 fixers have likely evolved that may enable reef communities to mitigate N limitation. We then explore the potential effects of the increasing human interferences on the process of benthic reef N2 fixation via changes in diazotrophic populations, enzymatic activities, or availability of benthic substrates favorable to these microorganisms. Current knowledge indicates positive effects of ocean acidification, warming, and deoxygenation and negative effects of increased ultraviolet radiation on the amount of N fixed in coral reefs. Eutrophication may either boost or suppress N2 fixation, depending on the nutrient becoming limiting. As N2 fixation appears to play a fundamental role in nutrient-limited reef ecosystems, these assumptions need to be expanded and confirmed by future research efforts addressing the knowledge gaps identified in this review. PMID:24967086

Benthic foraminiferal response to environmental changes across Cenomanian/Turonian boundary (OAE2) in the northeastern Tethys, Kopet-Dagh basin

NASA Astrophysics Data System (ADS)

Kalanat, Behnaz; Vahidinia, Mohammad; Vaziri-Moghaddam, Hossein; Mahmudy-Gharaie, Mohamad Hosein; Kumon, Fujio

2017-10-01

In order to evaluate Oceanic Anoxic Event 2 (OAE2) at the Cenomanian-Turonian boundary and its effects on benthic foraminifera, the Taherabad stratigraphic section in the east of Kopet-Dagh basin was studied for pattern of changes in benthic foraminiferal communities. Total Organic Carbon (TOC) concentration at the Taherabad section shows that black shale was not deposited in this succession but TOC increases up to 0.68 wt% in the three intervals of Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica Zones. Also, Total Nitrogen (TN) values were measured in our study succession. High TOC/TN ratios (up to 18) occur in the intervals of TOC enrichment. Foraminiferal assemblages, TOC, TOC/TN and Detrital Index (DI, an index for detrital input) changes in the study section allowed us to divided study section into 4 intervals. Interval A and C are associated with low abundance and diversity of benthic assemblages coeval with lack of planktic foraminifera. Benthic assemblages are strongly dominated by shallow and deep infaunal agglutinated foraminifera including Lagenammina, Saccammina, Reophax and Tritaxia. The foraminiferal composition associated with higher TOC, TOC/TN and DI suggest an influx of fresh water to the basin in the warm-wet periods, which diminished hospitable conditions for planktic foraminifera and probably enhanced land-derived organic matter and/or primary productivity. The hyposaline cap led to development of salinity-stratified water and induce bottom water oxygen depletion. By contrast, the assemblages found in the interval B and D are more diverse and contain high abundance of planktic and calcareous benthic foraminifera. Common benthic taxa in these parts are praebuliminids, lenticulinids, gavelinellids and Valvulineria. These assemblages associated with lower TOC, TOC/TN and DI indicate decreased detrital input and more normal marine condition resulted in improved ventilation of sea-floor, which is favorable for planktic and benthic taxa.

Ecological risk assessment for residual coal fly ash at Watts Bar Reservoir, Tennessee: Limited alteration of riverine-reservoir benthic invertebrate community following dredging of ash-contaminated sediment.

PubMed

Buys, David J; Stojak, Amber R; Stiteler, William; Baker, Tyler F

2015-01-01

Benthic invertebrate communities were assessed after the December 2008 release of approximately 4.1 million m(3) coal fly ash from a disposal dredge cell at the Tennessee Valley Authority (TVA) Kingston Fossil Plant on Watts Bar Reservoir in Roane County, Tennessee, USA. Released ash filled the adjacent embayments and the main channel of the Emory River, migrating into reaches of the Emory, Clinch, and Tennessee Rivers. Dredging was completed in summer 2010, and the benthic community sampling was conducted in December 2010. This study is part of a series that supported an Ecological Risk Assessment for the Kingston site. Benthic invertebrate communities were sampled at transects spread across approximately 20 miles of river that includes both riverine and reservoirlike conditions. Community composition was assessed on a grab sample and transect basis across multiple cross-channel transects to gain an understanding of the response of the benthic community to a fly ash release of this magnitude. This assessment used invertebrate community metrics, similarity analysis, geospatial statistics, and correlations with sediment chemistry and habitat. The community composition was reflective of a reservoir system, with dominant taxa being insect larva, bivalves, and aquatic worms. Most community metric results were similar for ash-impacted areas and upstream reference areas. Variation in the benthic community was correlated more with habitat than with sediment chemistry or residual ash. Other studies have reported that a benthic community can take several years to a decade to recover from ash or ash-related constituents. Although released ash undoubtedly had some initial impacts on the benthic community in this study, the severity of these effects appears to be limited to the initial smothering of the organisms followed by a rapid response and the initial start of recovery postdredging. © 2014 SETAC.

Effects of flow regime on benthic algae and macroinvertebrates - A comparison between regulated and unregulated rivers.

PubMed

Schneider, Susanne C; Petrin, Zlatko

2017-02-01

Natural fluctuations in flow are important for maintaining the ecological integrity of riverine ecosystems. However, the flow regime of many rivers has been modified. We assessed the impact of water chemistry, habitat and streamflow characteristics on macroinvertebrates and benthic algae, comparing 20 regulated with 20 unregulated sites. Flow regime, calculated from daily averaged discharge over the five years preceding sampling, was generally more stable at regulated sites, with higher relative discharges in winter, lower relative discharges in spring and smaller differences between upper and lower percentiles. However, no consistent differences in benthic algal or macroinvertebrate structural and functional traits occurred between regulated and unregulated sites. When regulated and unregulated sites were pooled, overall flow regime, calculated as principal components of discharge characteristics over the five years preceding sampling, affected macroinvertebrate species assemblages, but not indices used for ecosystem status assessment or functional feeding groups. This indicates that, while species identity shifted with changing flow regime, the exchanged taxa had similar feeding habits. In contrast to macroinvertebrates, overall flow regime did not affect benthic algae. Our results indicate that overall flow regime affected the species pool of macroinvertebrates from which recolonization after extreme events may occur, but not of benthic algae. When individual components of flow regime were analyzed separately, high June (i.e. three months before sampling) flow maxima were associated with low benthic algal taxon richness, presumably due to scouring. Macroinvertebrate taxon richness decreased with lower relative minimum discharges, presumably due to temporary drying of parts of the riverbed. However, recolonization after such extreme events presumably is fast. Generally, macroinvertebrate and benthic algal assemblages were more closely related to water physico-chemical than to hydrological variables. Our results suggest that macroinvertebrate and benthic algal indices commonly used for ecological status assessment are applicable also in regulated rivers. Copyright © 2016 Elsevier B.V. All rights reserved.

"Recent" macrofossil remains from the Lomonosov Ridge, central Arctic Ocean

NASA Astrophysics Data System (ADS)

Le Duc, Cynthia; de Vernal, Anne; Archambault, Philippe; Brice, Camille; Roberge, Philippe

2016-04-01

The examination of surface sediment samples collected from 17 sites along the Lomonosov Ridge at water depths ranging from 737 to 3339 meters during Polarstern Expedition PS87 in 2014 (Stein, 2015), indicates a rich biogenic content almost exclusively dominated by calcareous remains. Amongst biogenic remains, microfossils (planktic and benthic foraminifers, pteropods, ostracods, etc.) dominate but millimetric to centrimetric macrofossils occurred frequently at the surface of the sediment. The macrofossil remains consist of a large variety of taxa, including gastropods, bivalvia, polychaete tubes, scaphopods, echinoderm plates and spines, and fish otoliths. Among the Bivalvia, the most abundant taxa are Portlandia arctica, Hyalopecten frigidus, Cuspidaria glacilis, Policordia densicostata, Bathyarca spp., and Yoldiella spp. Whereas a few specimens are well preserved and apparently pristine, most mollusk shells displayed extensive alteration features. Moreover, most shells were covered by millimeter scale tubes of the serpulid polychaete Spirorbis sp. suggesting transport from low intertidal or subtidal zone. Both the ecological affinity and known geographic distribution of identified bivalvia as named above support the hypothesis of transportation rather than local development. In addition to mollusk shells, more than a hundred fish otoliths were recovered in surface sediments. The otoliths mostly belong to the Gadidae family. Most of them are well preserved and without serpulid tubes attached to their surface, suggesting a local/regional origin, unlike the shell remains. Although recovered at the surface, the macrofaunal assemblages of the Lomonosov Ridge do not necessarily represent the "modern" environments as they may result from reworking and because their occurrence at the surface of the sediment may also be due to winnowing of finer particles. Although the shells were not dated, we suspect that their actual ages may range from modern to several thousands of years as suggested by the radiocarbon dating of the upper centimeter of the sediment in PS87/030-2 (7792 ± 59 14C years BP), PS87/055-1 (3897 ± 41 14C years BP), and PS87/099-4 (1421 ± 66 14C years BP). Reference Stein, R. (Ed.), 2015. The Expedition PS87 of the Research Vessel Polarstern to the Arctic Ocean in 2014, Reports on Polar and Marine Research 688, Bremerhaven, Alfred Wegener Institute for Polar and Marine Research, 273 pp (http://epic.awi.de/37728/1/BzPM_0688_2015.pdf).

Physical and Biological Effects on Tide Flat Sediment Stability and Strength - Phase 2

DTIC Science & Technology

2011-09-30

forcings, such as insolation, rainfall, benthic microalgae and seagrass (Zostera japonica) abundance, these variations did not always result in...m2 in the winter to a high of >3000 shoots/m2 in late summer. (B) Is chlorophyll a content in mg/g dry sediment (a proxy for benthic microalgae ...Another area of insight regarding physical/biological interactions involves the impact of microphytobenthos (MPB) or benthic microalgae on the

Abrupt Changes in Bottom Water Benthic Foraminiferal Assemblages during Heinrich Events 1-4

NASA Astrophysics Data System (ADS)

Lazar, K.; Rashid, H.; Vermooten, M.; Mingqiu, D.

2017-12-01

The extent to which Heinrich iceberg-rafting events modify bottom water ecology resulting in changes in benthic foraminifera is poorly known. Here, we report centennial to millennial scale changes in the benthic foraminiferal assemblages from sediment core Pa96018-06 (47.75oN; 46.21oW). It was collected on the northern slope of the Flemish Pass of southern Labrador Sea and is bathed by Labrador Sea Water, one of the major components of the meridional overturning circulation of the Atlantic. Benthic foraminiferal assemblages were determined and numerous species identified. X-ray fluorescence (XRF) on the bulk sediments and iceberg-rafted detritus (IRD) in addition to oxygen isotopes on polar planktonic foraminiferal Neogloboquadrina pachyderma (sinistral) were used to identify the detrital carbonate-rich Heinrich iceberg-rafting events 1 to 4. Changes in the total numbers of Elphidium excavatum subsp. clavatum typically mirror changes in the total benthic population, yet the percentage of E. e. clavatum as part of the total sample increases through time. E. e. clavatum comprises approximately 60% of the benthic assemblage in H4, and steadily increases to 80% of the assemblage in H1 and H2. Total benthic foraminiferal numbers increase at the onset of each Heinrich event, with the two largest peaks in the entire record characterizing H2 and H3. In addition, the fine-scale feature in H1 suggests an initial decrease in the % E. e. clavatum (and total benthics) which then increased to 85% of the assemblage during the latter part of H1. Our data suggest that harsh living conditions prevailed during the initial phases of Heinrich events when the availability of meltwater and the deposition of fine-grained carbonate sediments were dominant. However, it appears that the ecology was favorable for E. e. clavatum during the latter phase of Heinrich events when the deposition of fine-grained sediments dissipated and the supply of meltwater was limited. These latter stages, especially of H2 and H3, suggest a unique and extreme environment in which E. e. clavatum flourished while many other foraminifers were unable to recover. Typical of extreme cold-water, low-salinity environments, E. e. clavatum is likely a useful benthic foraminifer for tracking extreme iceberg-rafting events as preserved in the sedimentary record.

Neogene paleoceanographic events recorded in an active-margin setting: Humboldt basin, California

USGS Publications Warehouse

McCrory, P.A.

1990-01-01

Recognition of North Pacific paleoceanographic events in the marginal Humboldt (Eel River) basin of northern California enables correlation of stratigraphic sections and development of a chronostratigraphy. Paleoclimatically related coiling shifts in Neogloboquadrina pachyderma (Ehrenberg) and benthic foraminiferal datums form the basis of the chronostratigraphy. Benthic foraminiferal datums are defined by the occurrence of selected benthic species and abundance maxima of benthic biofacies. The compiled chronostratigraphy is used to refine reconstructions of the depositional history of Humboldt basin. Paleoceanographic events, recognized by the distribution of benthic foraminiferal biofacies, are used to infer paleoceanographic history along the northeastern Pacific margin. The similarity in coiling curves of N. pachyderma from the marine sequence at DSDP Site 173 and the coastal Centerville Beach section of Humboldt basin and at other independently dated sites along the northeastern Pacific margin demonstrates that matching records of climatic oscillations is a reliable method of correlating marine sequences. Benthic fauna from the Centerville Beach section vary in phase with climatically related coiling shifts in N. pachyderma. In particular these data show an increase in displaced neritic fauna during inferred warm intervals and resurgence of deeper bathyal fauna during inferred cool events. Similar data are observed from the inland Eel River section, demonstrating that benthic foraminiferal trends recognized at Centerville Beach can be identified elsewhere in Humboldt basin. This in-phase benthic response to climatic fluctuations probably results from changes in vertical depth range of many benthic species in response to paleoclimatically related vertical changes in water-mass position. Depositional histories reconstructed for two key sites in southern Humboldt basin indicate low rates of sediment accumulation during early basin filling with hemipelagic sediments. Initiation of turbidite sedimentation in the early Pliocene resulted in a sharp increase in rate of sediment accumulation. This increase in rate of sediment accumulation is partially a response to tectonic uplift in the northern Coast Ranges and may be an effect of realignment of motion between the Pacific and North American plates at about this time. The inland site shoaled more rapidly during turbidite sedimentation as a result of a higher rate of sediment accumulation. The rate of sediment accumulation increased again at this site in the late Pliocene during deposition of shelf and nearshore facies. The Eel River region subsided concurrent with deposition of these shallow-water deposits. ?? 1990.

Widespread kelp-derived carbon in pelagic and benthic nearshore fishes

USGS Publications Warehouse

von Biela, Vanessa R.; Newsome, Seth D.; Bodkin, James L.; Kruse, Gordon H.; Zimmerman, Christian E.

2016-01-01

Kelp forests provide habitat for diverse and abundant fish assemblages, but the extent to which kelp provides a source of energy to fish and other predators is unclear. To examine the use of kelp-derived energy by fishes we estimated the contribution of kelp- and phytoplankton-derived carbon using carbon (δ13C) and nitrogen (δ15N) isotopes measured in muscle tissue. Benthic-foraging kelp greenling (Hexagrammos decagrammus) and pelagic-foraging black rockfish (Sebastes melanops) were collected at eight sites spanning ∼35 to 60°N from the California Current (upwelling) to Alaska Coastal Current (downwelling) in the northeast Pacific Ocean. Muscle δ13C values were expected to be higher for fish tissue primarily derived from kelp, a benthic macroalgae, and lower for tissue primarily derived from phytoplankton, pelagic microalgae. Muscle δ13C values were higher in benthic-feeding kelp greenling than in pelagic-feeding black rockfish at seven of eight sites, indicating more kelp-derived carbon in greenling as expected. Estimates of kelp carbon contributions ranged from 36 to 89% in kelp greenling and 32 to 65% in black rockfish using carbon isotope mixing models. Isotopic evidence suggests that these two nearshore fishes routinely derive energy from kelp and phytoplankton, across coastal upwelling and downwelling systems. Thus, the foraging mode of nearshore predators has a small influence on their ultimate energy source as energy produced by benthic macroalgae and pelagic microalgae were incorporated in fish tissue regardless of feeding mode and suggest strong and widespread benthic-pelagic coupling. Widespread kelp contributions to benthic- and pelagic-feeding fishes suggests that kelp energy provides a benefit to nearshore fishes and highlights the potential for kelp and fish production to be linked.

Herbivorous snails can increase water clarity by stimulating growth of benthic algae.

PubMed

Zhang, Xiufeng; Taylor, William D; Rudstam, Lars G

2017-11-01

Eutrophication in shallow lakes is characterized by a switch from benthic to pelagic dominance of primary productivity that leads to turbid water, while benthification is characterized by a shift in primary production from the pelagic zone to the benthos associated with clear water. A 12-week mesocosm experiment tested the hypothesis that the herbivorous snail Bellamya aeruginosa stimulates the growth of pelagic algae through grazing on benthic algae and through accelerating nutrient release from sediment. A tube-microcosm experiment using 32 P-PO 4 as a tracer tested the effects of the snails on the release of sediment phosphorus (P). The mesocosm experiment recorded greater total nitrogen (TN) concentrations and a higher ratio of TN:TP in the overlying water, and a higher light intensity and biomass of benthic algae as measured by chlorophyll a (Chl a) in the snail treatment than in the control. Concentrations of total phosphorus (TP), total suspended solids (TSSs), and inorganic suspended solids (ISSs) in the overlying water were lower in the snail treatment than in the control, though no significant difference in Chl a of pelagic algae between the snail treatment and control was observed. In the microcosm experiment, 32 P activity in the overlying water was higher in the snail treatment than in the control, indicating that snails accelerated P release from the sediment. Our interpretation of these results is that snails enhanced growth of benthic algae and thereby improved water clarity despite grazing on the benthic algae and enhancing P release from the sediment. The rehabilitation of native snail populations may therefore enhance the recovery of eutrophic shallow lakes to a clear water state by stimulating growth of benthic algae.

Benthic foraminifera as indicators of pollution in high latitude marine environments

NASA Astrophysics Data System (ADS)

Dijkstra, N.; Junttila, J.; Husum, K.; Carroll, J.; Klitgaard-Kristensen, D.; Hald, M.

2012-04-01

An increasing number of studies demonstrate the potential of benthic foraminifera to characterize ecological status. However, the use of benthic foraminifera as bio-indicators has previously not been tested in high latitudes. This research contributes to the development of foraminifera as a bio-monitoring technique for the Arctic region, as industrial activities in this region will increase in the coming years. Surface sediments (0-1 cm) from sites close to gas fields in the SW Barents Sea were studied. In addition, to elucidate the range from less to very affected, surface sediments from the harbor of the town of Hammerfest (70° N) were studied. At least 300 living benthic foraminifera from the size fraction 100 µm-1 mm were counted and identified at species level. Pollution levels (heavy metals and persistent organic pollutants) and sediment properties (grainsize and TOC) were also analyzed. Pollution levels at the sea floor in the SW Barents Sea are of background to good level (level I-II) according to the definitions by the Water Framework Directorate (WFD). Benthic foraminiferal assemblages are influenced by natural environmental parameters such as water mass properties, water depth, nutrient availability, bottom current strength, and grain size. Surface sediments from the Hammerfest harbor are of moderate environmental status (WFD level II-III) based on heavy metal concentrations and of bad environmental status (WFD IV-V) based on persistent organic pollutant concentrations. Opportunistic benthic foraminifera are dominating the assemblages. The most polluted areas in the harbor are barren for foraminifera or have high amounts of deformed shells. In both environments the foraminiferal diversity of the samples, does not correspond to expected environmental status based on the pollution levels of the sediments. Environmental status classes, based on benthic foraminifera instead of macrofauna, would allow rapid analyses of the environmental impact of pollution.

Thirty-Three Years of Ocean Benthic Warming Along the U.S. Northeast Continental Shelf and Slope: Patterns, Drivers, and Ecological Consequences

NASA Astrophysics Data System (ADS)

Kavanaugh, Maria T.; Rheuban, Jennie E.; Luis, Kelly M. A.; Doney, Scott C.

2017-12-01

The U.S. Northeast Continental Shelf is experiencing rapid warming, with potentially profound consequences to marine ecosystems. While satellites document multiple scales of spatial and temporal variability on the surface, our understanding of the status, trends, and drivers of the benthic environmental change remains limited. We interpolated sparse benthic temperature data along the New England Shelf and upper Slope using a seasonally dynamic, regionally specific multiple linear regression model that merged in situ and remote sensing data. The statistical model predicted nearly 90% of the variability of the data, resulting in a synoptic time series spanning over three decades from 1982 to 2014. Benthic temperatures increased throughout the domain, including in the Gulf of Maine. Rates of benthic warming ranged from 0.1 to 0.4°C per decade, with fastest rates occurring in shallow, nearshore regions and on Georges Bank, the latter exceeding rates observed in the surface. Rates of benthic warming were up to 1.6 times faster in winter than the rest of the year in many regions, with important implications for disease occurrence and energetics of overwintering species. Drivers of warming varied over the domain. In southern New England and the mid-Atlantic shallow Shelf regions, benthic warming was tightly coupled to changes in SST, whereas both regional and basin-scale changes in ocean circulation affect temperatures in the Gulf of Maine, the Continental Shelf, and Georges Banks. These results highlight data gaps, the current feasibility of prediction from remotely sensed variables, and the need for improved understanding on how climate may affect seasonally specific ecological processes.

Temporal and spatial assessment of water quality, physical habitat, and benthic communities in an impaired agricultural stream in California's San Joaquin Valley.

PubMed

Hall, Lenwood W; Killen, William D

2005-01-01

The goal of this study was to characterize and discuss the relationships among water quality, physical habitat, and benthic community data collected annually over a three-year period (2000--2002) in an impaired agricultural stream (Orestimba Creek) in California's San Joaquin River watershed. Conductivity, pH, and turbidity were the most important water quality conditions influencing the various benthic metrics. Significantly higher flow conditions and lower dissolved oxygen values were reported in Orestimba Creek in 2001; increased turbidity conditions were reported in 2002. Channel alteration, riparian buffer, sediment deposition, and channel flow were the most important physical habitat metrics influencing the various benthic metrics. Higher total physical habitat scores were reported in 2001 when compared with 2002. The most dominant benthic taxa collected during all three years of sampling were oligochaetes and chironomids. Oligochaetes are found in stressful environments while chironomids can be either sensitive or tolerant to environmental stressors depending on the species. Populations of both daphnids and the exotic clam Corbicula were reported to increase over time. Both of these taxa are generally tolerant to most types of environmental degradation. The exception is that daphnids are highly sensitive to organophosphate insecticides. The % filterers increased over time, which suggests an increase in environmental disturbance. The % collectors decreased from 2000 to 2002, which suggests an improvement in environmental conditions. The presence of approximately 100 taxa in Orestimba Creek during each of the three years of sampling implies that benthic communities in this stream are fairly diverse, considering their ephemeral environment, but without a clear definition of benthic community expectations based on established referenc conditions it is unknown if this water body is actually impaired.

Thirty-Three Years of Ocean Benthic Warming Along the U.S. Northeast Continental Shelf and Slope: Patterns, Drivers, and Ecological Consequences.

PubMed

Kavanaugh, Maria T; Rheuban, Jennie E; Luis, Kelly M A; Doney, Scott C

2017-12-01

The U.S. Northeast Continental Shelf is experiencing rapid warming, with potentially profound consequences to marine ecosystems. While satellites document multiple scales of spatial and temporal variability on the surface, our understanding of the status, trends, and drivers of the benthic environmental change remains limited. We interpolated sparse benthic temperature data along the New England Shelf and upper Slope using a seasonally dynamic, regionally specific multiple linear regression model that merged in situ and remote sensing data. The statistical model predicted nearly 90% of the variability of the data, resulting in a synoptic time series spanning over three decades from 1982 to 2014. Benthic temperatures increased throughout the domain, including in the Gulf of Maine. Rates of benthic warming ranged from 0.1 to 0.4°C per decade, with fastest rates occurring in shallow, nearshore regions and on Georges Bank, the latter exceeding rates observed in the surface. Rates of benthic warming were up to 1.6 times faster in winter than the rest of the year in many regions, with important implications for disease occurrence and energetics of overwintering species. Drivers of warming varied over the domain. In southern New England and the mid-Atlantic shallow Shelf regions, benthic warming was tightly coupled to changes in SST, whereas both regional and basin-scale changes in ocean circulation affect temperatures in the Gulf of Maine, the Continental Shelf, and Georges Banks. These results highlight data gaps, the current feasibility of prediction from remotely sensed variables, and the need for improved understanding on how climate may affect seasonally specific ecological processes.

Relations between benthic community structure and metals concentrations in aquatic macroinvertebrates: Clark Fork River, Montana

USGS Publications Warehouse

1995-01-01

We sampled macroinvertebrate communities at six sites on the upper Clark Fork River, Montana, to determine relations between macroinvertebrate community structure and metals in invertebrates and the best benthic community metrics to use for ranking sites based on the relative severity of the effects of metals. Concentrations (μg/g) of six metals in invertebrates were determined: Al (range = 591–4193), As (2.7–34.1), Cd (0.13–8.38), Cu (26–1382), Pb (0.54–67.1), and Zn (212–1665). Concentrations of As, Cd, Cu, Pb, and total metals were significantly correlated with at least one benthic metric. Copper (r = 0.88–0.94) and total metals (r = 0.90–0.97) provided the most highly significant correlations. Based on longitudinal site comparisons of metals in invertebrates, benthic community structure, and differences between proportionally scaled ranks, five benthic metrics provided the best indicators of relative impact: taxa richness, Ephemeroptera-Plecoptera-Trichoptera (EPT) richness, chironomid richness, percentage of the most dominant taxon, and density. The two sites with the highest accumulations of invertebrate metals also demonstrated the greatest relative degree of impact based on these parameters. The most meaningful combinations of metrics indicate that the benthic community at the most upstream site is being severely impacted by metals. Two sites demonstrated little or no negative impact, and three sites demonstrated low or moderate levels of negative impacts, which may be due to a combination of metals and other factors such as organic enrichment. We recommend that benthic community structure and metals in invertebrates collected from riffle habitats be used to determine relative impacts in metals-contaminated river systems, owing to their close relation to metal availability and transfer to higher trophic levels.

The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world.

PubMed

Griffiths, Jennifer R; Kadin, Martina; Nascimento, Francisco J A; Tamelander, Tobias; Törnroos, Anna; Bonaglia, Stefano; Bonsdorff, Erik; Brüchert, Volker; Gårdmark, Anna; Järnström, Marie; Kotta, Jonne; Lindegren, Martin; Nordström, Marie C; Norkko, Alf; Olsson, Jens; Weigel, Benjamin; Žydelis, Ramunas; Blenckner, Thorsten; Niiranen, Susa; Winder, Monika

2017-06-01

Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Louisiana waterthrush and benthic macroinvertebrate response to shale gas development

USGS Publications Warehouse

Wood, Petra; Frantz, Mack W.; Becker, Douglas A.

2016-01-01

Because shale gas development is occurring over large landscapes and consequently is affecting many headwater streams, an understanding of its effects on headwater-stream faunal communities is needed. We examined effects of shale gas development (well pads and associated infrastructure) on Louisiana waterthrush Parkesia motacilla and benthic macroinvertebrate communities in 12 West Virginia headwater streams in 2011. Streams were classed as impacted (n = 6) or unimpacted (n = 6) by shale gas development. We quantified waterthrush demography (nest success, clutch size, number of fledglings, territory density), a waterthrush Habitat Suitability Index, a Rapid Bioassessment Protocol habitat index, and benthic macroinvertebrate metrics including a genus-level stream-quality index for each stream. We compared each benthic metric between impacted and unimpacted streams with a Student's t-test that incorporated adjustments for normalizing data. Impacted streams had lower genus-level stream-quality index scores; lower overall and Ephemeroptera, Plecoptera, and Trichoptera richness; fewer intolerant taxa, more tolerant taxa, and greater density of 0–3-mm individuals (P ≤ 0.10). We then used Pearson correlation to relate waterthrush metrics to benthic metrics across the 12 streams. Territory density (no. of territories/km of stream) was greater on streams with higher genus-level stream-quality index scores; greater density of all taxa and Ephemeroptera, Plecoptera, and Trichoptera taxa; and greater biomass. Clutch size was greater on streams with higher genus-level stream-quality index scores. Nest survival analyses (n = 43 nests) completed with Program MARK suggested minimal influence of benthic metrics compared with nest stage and Habitat Suitability Index score. Although our study spanned only one season, our results suggest that shale gas development affected waterthrush and benthic communities in the headwater streams we studied. Thus, these ecological effects of shale gas development warrant closer examination.

Benthic fluxes of oxygen and inorganic nutrients in the archipelago of Gulf of Finland, Baltic Sea - Effects of sediment resuspension measured in situ

NASA Astrophysics Data System (ADS)

Niemistö, Juha; Kononets, Mikhail; Ekeroth, Nils; Tallberg, Petra; Tengberg, Anders; Hall, Per O. J.

2018-05-01

Benthic fluxes of oxygen and dissolved inorganic nutrients; phosphate (DIP), ammonium (NH4), nitrate + nitrite (NOx), and silicate (DSi); and the effects of resuspension on these were studied in situ with the Göteborg benthic landers in the Gulf of Finland archipelago, Baltic Sea. The benthic fluxes were examined at two shallow stations at depths of 7 m and 20 m in May and August 2014. Resuspension altered benthic fluxes of oxygen and nutrients in most of the experiments in August, but not in May, which was mainly due to weaker resuspension treatments in spring. Additionally, the benthic nutrient regeneration rates were higher and redox conditions lower in August when the water was warmer. In August, resuspension increased the benthic oxygen uptake by 33-35%, which was, in addition to stronger resuspension treatment, attributed to higher amounts of dissolved reduced substances in the sediment pore water in comparison to conditions in May. Adsorption onto newly formed iron oxyhydroxides could explain the uptake of DIP by the sediment at the 20 m station and the lowering of the DSi efflux by 31% at the 7 m station during resuspension in August. In addition, resuspension promoted nitrification, as indicated by increased NOx fluxes at both stations (by 30% and 27% at the 7 m and 20 m station, respectively) and a lowered NH4 flux (by 48%) at the 7 m station. Predicted increases in the magnitude and frequency of resuspension will thus markedly affect the transport of phosphorus and silicon and the cycling of nitrogen in the shallow areas of the Gulf of Finland.

Widespread kelp-derived carbon in pelagic and benthic nearshore fishes suggested by stable isotope analysis

NASA Astrophysics Data System (ADS)

von Biela, Vanessa R.; Newsome, Seth D.; Bodkin, James L.; Kruse, Gordon H.; Zimmerman, Christian E.

2016-11-01

Kelp forests provide habitat for diverse and abundant fish assemblages, but the extent to which kelp provides a source of energy to fish and other predators is unclear. To examine the use of kelp-derived energy by fishes we estimated the contribution of kelp- and phytoplankton-derived carbon using carbon (δ13C) and nitrogen (δ15N) isotopes measured in muscle tissue. Benthic-foraging kelp greenling (Hexagrammos decagrammus) and pelagic-foraging black rockfish (Sebastes melanops) were collected at eight sites spanning ∼35 to 60°N from the California Current (upwelling) to Alaska Coastal Current (downwelling) in the northeast Pacific Ocean. Muscle δ13C values were expected to be higher for fish tissue primarily derived from kelp, a benthic macroalgae, and lower for tissue primarily derived from phytoplankton, pelagic microalgae. Muscle δ13C values were higher in benthic-feeding kelp greenling than in pelagic-feeding black rockfish at seven of eight sites, indicating more kelp-derived carbon in greenling as expected. Estimates of kelp carbon contributions ranged from 36 to 89% in kelp greenling and 32 to 65% in black rockfish using carbon isotope mixing models. Isotopic evidence suggests that these two nearshore fishes routinely derive energy from kelp and phytoplankton, across coastal upwelling and downwelling systems. Thus, the foraging mode of nearshore predators has a small influence on their ultimate energy source as energy produced by benthic macroalgae and pelagic microalgae were incorporated in fish tissue regardless of feeding mode and suggest strong and widespread benthic-pelagic coupling. Widespread kelp contributions to benthic- and pelagic-feeding fishes suggests that kelp energy provides a benefit to nearshore fishes and highlights the potential for kelp and fish production to be linked.

Effect of settled diatom‐aggregates on benthic nitrogen cycling

PubMed Central

Thamdrup, Bo; Stief, Peter; Glud, Ronnie N.

2017-01-01

Abstract The marine sediment hosts a mosaic of microhabitats. Recently it has been demonstrated that the settlement of phycodetrital aggregates can induce local changes in the benthic O2 distribution due to confined enrichment of organic material and alteration of the diffusional transport. Here, we show how this microscale O2 shift substantially affects benthic nitrogen cycling. In sediment incubations, the settlement of diatom‐aggregates markedly enhanced benthic O2 and NO3− consumption and stimulated NO2− and NH4+ production. Oxygen microprofiles revealed the rapid development of anoxic niches within and underneath the aggregates. During 120 h following the settling of the aggregates, denitrification of NO3− from the overlying water increased from 13.5 μmol m−2 h−1 to 24.3 μmol m−2 h−1, as quantified by 15N enrichment experiment. Simultaneously, N2 production from coupled nitrification‐denitrification decreased from 33.4 μmol m−2 h−1 to 25.9 μmol m−2 h−1, probably due to temporary inhibition of the benthic nitrifying community. The two effects were of similar magnitude and left the total N2 production almost unaltered. At the aggregate surface, nitrification was, conversely, very efficient in oxidizing NH4+ liberated by mineralization of the aggregates. The produced NO3− was preferentially released into the overlying water and only a minor fraction contributed to denitrification activity. Overall, our data indicate that the abrupt change in O2 microdistribution caused by aggregates stimulates denitrification of NO3− from the overlying water, and loosens the coupling between benthic nitrification and denitrification both in time and space. The study contributes to expanding the conceptual and quantitative understanding of how nitrogen cycling is regulated in dynamic benthic environments. PMID:29456269

Benthic Foraminifera, Food in the Deep Sea, and Limits to Bentho-Pelagic Coupling

NASA Astrophysics Data System (ADS)

Thomas, E.; Boscolo-Galazzo, F.; Arreguin-Rodrigu, G. J.; Ortiz, S.; Alegret, L.

2015-12-01

The deep-sea is the largest habitat on Earth, contains highly diverse biota, but is very little known. Many of its abundant benthic biota (e.g., nematodes) are not preserved in the fossil record. Calcareous and agglutinated benthic foraminifera (unicellular eukaryotes, Rhizaria; efficient dispersers) and ostracodes (Animalia, Crustacea; non-efficient dispersers) are the most common organisms providing a fossil record of deep-sea environments. Very little food is supplied to the deep-sea, because organic matter produced by photosynthesis is largely degraded before it arrives at the seafloor. Only a few % of organic matter is carried to the ocean bottom by 'marine snow', with its particle size and behavior in the water column controlled by surface ecosystem structure, including type of dominant primary producers (diatoms, cyanobacteria). Food supply and its seasonality are generally seen as the dominant control on benthic assemblages (combined with oxygenation), providing bentho-pelagic coupling between primary and benthic productivity. Benthic foraminiferal assemblages (composition and density) thus are used widely to estimate past productivity, especially during episodes of global climate change, ocean acidification, and mass extinction of primary producers. We show that some environmental circumstances may result in interrupting bentho-pelagic coupling, e.g. through lateral supply of organic matter along continental margins (adding more refractory organic matter), through trophic focusing and/or fine particle winnowing on seamounts (giving an advantage to suspension feeders), and through carbonate undersaturation (giving advantage to infaunal over epifaunal calcifyers). In addition, increased remineralization of organic matter combined with increased metabolic rates may cause assemblages to reflect more oligotrophic conditions at stable primary productivity during periods of global warming. As a result, benthic foraminiferal accumulation rates must be carefully evaluated before use as proxies for primary productivity.

Tidal variability in benthic silicic acid fluxes and microphytobenthos uptake in intertidal sediment

NASA Astrophysics Data System (ADS)

Leynaert, Aude; Longphuirt, Sorcha Ní; An, Soonmo; Lim, Jae-Hyun; Claquin, Pascal; Grall, Jacques; Kwon, Bong Oh; Koh, Chul Hwan

2011-11-01

Silicic acid (DSi) benthic fluxes play a major role in the benthic-pelagic coupling of coastal ecosystems. They can sustain microphytobenthos (MPB) development at the water-sediment interface and support pelagic diatoms when river DSi inputs decrease. DSi benthic fluxes have been studied at the seasonal scale but little is known about their dial variations. This study measured the amplitude of such variations in an intertidal area over an entire tidal cycle by following the alteration of DSi pore water concentrations at regular intervals over the flood/ebb period. Furthermore we independently estimated the potential DSi uptake by benthic diatoms and compared it to the variations of DSi pore water concentrations and fluxes. The microphytobenthos DSi demand was estimated from primary production measurements on cells extracted from the sediment. There were large changes in DSi pore water concentration and a prominent effect of tidal pumping: the DSi flushed out from the sediment at rising tide, occurs in a very short period of time, but plays a far more important role in fueling the ecosystem (800 μmol-Si m -2 d -1), than diffusive fluxes occurring throughout the rest of the tidal cycle (2 μmol-Si m -2 d -1). This process is not, to our knowledge, currently considered when describing the DSi cycling of intertidal sediments. Moreover, there was a large potential MPB requirement for DSi (812 μmol-Si m -2 d -1), similar to the advective flow periodically pumped by the incoming tide, and largely exceeded benthic diffusive fluxes. However, this DSi uptake by benthic diatoms is almost undetectable given the variation of DSi concentration profiles within the sediment.

Aquatic Nutrient Simulation Modules (NSMs) Developed for Hydrologic and Hydraulic Models

DTIC Science & Technology

2016-02-01

effect of temperature on algal growth unitless FOxpi oxygen attenuation for algal respiration unitless FOxb oxygen attenuation for benthic algal... effect of temperature below T0p on benthic algal growth 0C-2 ktb2 effect of temperature above T0p on benthic algal growth 0C-2 ka(T) oxygen ...Si Silica SOD Sediment Oxygen Demand SO4 TEMP Sulfate Water Temperature Simulation Module TN Total Nitrogen TP Total Phosphorous TIC Total

Benthic Ecology from Space: Optics and Net Primary Production in Seagrass and Benthic Algae Across the Great Bahama Bank

DTIC Science & Technology

2010-01-01

prevailing benthic habitat was mapped as sediment with little to no microalgal biofilm. Moderate to dense sea- grass meadows of Thalassia testudinum were...dense seagrass meadows of Thalassia testudinum were the dominant primary producers and contributed over 80% of NPP in the region. If the vast majority of...density of the seagrasses Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass) were estimated

The functional-morphological adaptive strategy of digestive organs of decapodiform cephalopods

PubMed Central

OMURA, Ayano; ENDO, Hideki

2015-01-01

The digestive organs in decapodiform cephalopod species morphologically vary by individual lifestyle. We examined the following six species of adult decapodiformes cephalopods representing different habitats: Todarodes pacificus, Loligo bleekeri, Loligo edulis, Watasenia scintillans (pelagic), Sepia lycidas and Euprymna morsei (benthic). L. bleekeri and L. edulis possess a bursiform cecal sac connected to the cecum. Pelagic species have a single digestive gland smaller than in benthic species. T. pacificus has an oval digestive gland larger than that of L. bleekeri and L. edulis, which possess withered-looking and smaller digestive glands. In contrast, the digestive glands in benthic species are paired. S. lycidas and E. morsei have well-developed and larger digestive glands than those of the pelagic species. Well-developed digestive duct appendages are found in benthic species. In qualification of the mass of digestive organs, pelagic species have smaller stomachs, digestive glands and digestive ducts’ appendages than benthic species. Because pelagic species need to swim, they may possess smaller stomachs and larger cecums for more rapid digestion. A smaller digestive gland may have the advantage of reducing the body weight in pelagic species for rapid swimming. In contrast, since benthic species require a longer time for digestion than pelagic species, they compact more food in their stomachs and absorb nutrients via more organs, such as the digestive grand and digestive duct appendages, in addition to cecum. PMID:26369293

Naturally Ocurring Polyphosphate-accumulating Bacteria in Benthic Biofilms

NASA Astrophysics Data System (ADS)

Locke, N. A.; Saia, S. M.; Walter, M. T.; Carrick, H. J.; Buda, A. R.; Regan, J. M.

2014-12-01

Polyphosphate accumulating organisms (PAOs), known to store excess phosphorus (P) as polyphosphate (poly-P), influence P transport in the environment. Enhanced biological phosphorus removal (EBPR) from wastewater has long served as a basis to study bacterial PAOs, yet little research has genetically identified similar organisms in natural settings. Aerobic/anaerobic cycles, used to select for PAOs in EBPR, can result from changing environmental conditions such as night/day cycles for benthic biofilms. Benthic biofilms from eight Pennsylvanian streams were studied for naturally-occurring bacterial PAOs similar to those typically found in EBPR systems. PAOs were confirmed in the benthic biofilms by a characteristic yellow fluorescent emission from DAPI staining. Cells containing yellow fluorescence were separated from the rest of the sample using a flow cytometer, resulting in a physically enriched culture of PAOs from the benthic biofilms. Amplicon-based metagenomic sequencing will reveal the phylogeny of bacteria responsible for poly-P accumulation in these benthic biofilms. Sequencing data will be used to develop fluorescent in-situ hybridization (FISH) probes, and hybridizations will be performed on DAPI-stained cells to confirm poly-P accumulation by targeted phylotypes. Identifying PAOs in natural settings is a critical step towards studying environments that support high concentrations of PAOs, serving as significant factors in the P cycle. PAOs can then be connected to P transport models to help understand and mitigate P pollution in agricultural watersheds.

Benthic cyanobacteria: A source of cylindrospermopsin and microcystin in Australian drinking water reservoirs.

PubMed

Gaget, Virginie; Humpage, Andrew R; Huang, Qiong; Monis, Paul; Brookes, Justin D

2017-11-01

Cyanobacteria represent a health hazard worldwide due to their production of a range of highly potent toxins in diverse aquatic environments. While planktonic species have been the subject of many investigations in terms of risk assessment, little is known about benthic forms and their impact on water quality or human and animal health. This study aimed to purify isolates from environmental benthic biofilms sampled from three different drinking water reservoirs and to assess their toxin production by using the following methods: Enzyme-Linked Immunosorbent Assay (ELISA), High-Performance Liquid Chromatography (HPLC), Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) and quantitative PCR (qPCR). Microscopic observation of the isolates allowed the identification of various filamentous cyanobacterial genera: Anabaena (benthic form), Calothrix and Nostoc from the Nostocales and Geitlerinema, Leptolyngbya, Limnothrix, Lyngbya, Oxynema, Phormidium and Pseudanabaena representing non-heterocystous filamentous cyanobacteria. The Phormidium ambiguum strain AWQC-PHO021 was found to produce 739 ng/mg of dry weight (d/w) of cylindrospermopsin and 107 ng/mg (d/w) of deoxy-cylindrospermopsin. The Nostoc linckia strain AWQC-NOS001 produced 400 ng/mg (d/w) of a microcystin analogue. This is the first report of hepatotoxin production by benthic cyanobacteria in temperate Australian drinking water reservoirs. These findings indicate that water quality monitoring programs need to consider benthic cyanobacteria as a potential source of toxins. Copyright © 2017 Elsevier Ltd. All rights reserved.

The functional-morphological adaptive strategy of digestive organs of decapodiform cephalopods.

PubMed

Omura, Ayano; Endo, Hideki

2016-01-01

The digestive organs in decapodiform cephalopod species morphologically vary by individual lifestyle. We examined the following six species of adult decapodiformes cephalopods representing different habitats: Todarodes pacificus, Loligo bleekeri, Loligo edulis, Watasenia scintillans (pelagic), Sepia lycidas and Euprymna morsei (benthic). L. bleekeri and L. edulis possess a bursiform cecal sac connected to the cecum. Pelagic species have a single digestive gland smaller than in benthic species. T. pacificus has an oval digestive gland larger than that of L. bleekeri and L. edulis, which possess withered-looking and smaller digestive glands. In contrast, the digestive glands in benthic species are paired. S. lycidas and E. morsei have well-developed and larger digestive glands than those of the pelagic species. Well-developed digestive duct appendages are found in benthic species. In qualification of the mass of digestive organs, pelagic species have smaller stomachs, digestive glands and digestive ducts' appendages than benthic species. Because pelagic species need to swim, they may possess smaller stomachs and larger cecums for more rapid digestion. A smaller digestive gland may have the advantage of reducing the body weight in pelagic species for rapid swimming. In contrast, since benthic species require a longer time for digestion than pelagic species, they compact more food in their stomachs and absorb nutrients via more organs, such as the digestive grand and digestive duct appendages, in addition to cecum.

Evaluating ecosystem-based management options: Effects of trawling in Torres Strait, Australia

NASA Astrophysics Data System (ADS)

Ellis, Nick; Pantus, Francis; Welna, Andrzej; Butler, Alan

2008-09-01

A suite of management options for a prawn trawl fishery in Torres Strait, Australia was assessed for impacts on the benthic fauna using a dynamic management strategy evaluation approach. The specification of the management options was gained through consultation with stakeholders. Data for the model was drawn from several sources: the fleet data from fishery logbooks and satellite vessel monitoring systems, benthic depletion rates from trawl-down experiments, benthic recovery rates from post-experiment recovery monitoring studies, and benthic distribution from large-scale benthic surveys. Although there were large uncertainties in the resulting indicators, robust measures relevant to management were obtained by taking ratios relative to the status quo. The management control with the biggest effect was total effort; reducing trawl effort always led to increases in benthic faunal density of up to 10%. Spatial closures had a smaller benefit of up to 2%. The effect of closing a set of buffer zones around reefs to trawling was indistinguishable from the status quo option. Closing a larger area, however, was largely beneficial especially for sea cucumbers. When the spatial distributions of fauna prior to fishing were accounted for, fauna with distributions positively correlated with effort improved relative to those negatively correlated. The reduction in prawn catch under effort reduction scenarios could be ameliorated by introducing temporal closures over the full-moon period.

Benthic algae compensate for phytoplankton losses in large aquatic ecosystems.

PubMed

Brothers, Soren; Vadeboncoeur, Yvonne; Sibley, Paul

2016-12-01

Anthropogenic activities can induce major trophic shifts in aquatic systems, yet we have an incomplete understanding of the implication of such shifts on ecosystem function and on primary production (PP) in particular. In recent decades, phytoplankton biomass and production in the Laurentian Great Lakes have declined in response to reduced nutrient concentrations and invasive mussels. However, the increases in water clarity associated with declines in phytoplankton may have positive effects on benthic PP at the ecosystem scale. Have these lakes experienced oligotrophication (a reduction of algal production), or simply a shift in autotrophic structure with no net decline in PP? Benthic contributions to ecosystem PP are rarely measured in large aquatic systems, but our calculations based on productivity rates from the Great Lakes indicate that a significant proportion (up to one half, in Lake Huron) of their whole-lake production may be benthic. The large declines (5-45%) in phytoplankton production in the Great Lakes from the 1970s to 2000s may be substantially compensated by benthic PP, which increased by up to 190%. Thus, the autotrophic productive capacity of large aquatic ecosystems may be relatively resilient to shifts in trophic status, due to a redirection of production to the near-shore benthic zone, and large lakes may exhibit shifts in autotrophic structure analogous to the regime shifts seen in shallow lakes. © 2016 John Wiley & Sons Ltd.

Structure of Benthic Communities along the Taiwan Latitudinal Gradient

PubMed Central

De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

2016-01-01

The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

Water-quality parameters and benthic algal communities at selected streams in Minnesota, August 2000 - Study design, methods and data

USGS Publications Warehouse

Lee, K.E.

2002-01-01

This report describes the study design, sampling methods, and summarizes the physical, chemical, and benthic algal data for a component of the multiagency study that was designed to document diurnal water-quality measurements (specific conductance, pH, water temperature, and dissolved oxygen), benthic algal community composition and chlorophyll-a content, and primary productivity at 12 stream sites on 6 streams in Minnesota during August 2000. Specific conductance, pH, water temperature, dissolved oxygen concentrations and percent dissolved oxygen saturation measurements were made with submersible data recorders at 30 minute intervals for a period of 3-6 days during August 2000. Benthic algae collected from wood and rock substrate were identified and enumerated. Biovolume (volume of algal cells per unit area), density (number of cells per unit area), and chlorophyll-a content from benthic algae were determined. These data can be used as part of the multiagency study to develop an understanding of the relations among nutrient concentrations, algal abundance, algal community composition, and primary production and respiration processes in rivers of differing ecoregions in Minnesota.

Feasibility of remote sensing benthic microalgae

NASA Technical Reports Server (NTRS)

Zingmark, R. G.

1979-01-01

Results of data analyses from multispectral scanning data are presented. The data was collected in July 1977 for concentration of chlorophyll in benthic microalgae (mainly diatoms) on an estuary mudflat.

A Serpentinite-Hosted Ecosystem: The Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Kelley, Deborah S.; Karson, Jeffrey A.; Früh-Green, Gretchen L.; Yoerger, Dana R.; Shank, Timothy M.; Butterfield, David A.; Hayes, John M.; Schrenk, Matthew O.; Olson, Eric J.; Proskurowski, Giora; Jakuba, Mike; Bradley, Al; Larson, Ben; Ludwig, Kristin; Glickson, Deborah; Buckman, Kate; Bradley, Alexander S.; Brazelton, William J.; Roe, Kevin; Elend, Mitch J.; Delacour, Adélie; Bernasconi, Stefano M.; Lilley, Marvin D.; Baross, John A.; Summons, Roger E.; Sylva, Sean P.

2005-03-01

The serpentinite-hosted Lost City hydrothermal field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater and upper mantle peridotite produce methane- and hydrogen-rich fluids, with temperatures ranging from <40° to 90°C at pH 9 to 11, and carbonate chimneys 30 to 60 meters tall. A low diversity of microorganisms related to methane-cycling Archaea thrive in the warm porous interiors of the edifices. Macrofaunal communities show a degree of species diversity at least as high as that of black smoker vent sites along the Mid-Atlantic Ridge, but they lack the high biomasses of chemosynthetic organisms that are typical of volcanically driven systems.

Antifouling leaching technique for optical lenses

USGS Publications Warehouse

Strahle, William J.; Perez, C. L.; Martini, Marinna A.

1994-01-01

The effectiveness of optical lenses deployed in water less than 100 m deep is significantly reduced by biofouling caused by the settlement of macrofauna, such as barnacles, hydroids, and tunicates. However, machineable porous plastic rings can be used to dispense antifoulant into the water in front of the lens to retard macrofaunal growth without obstructing the light path. Unlike coatings which can degrade the optical performance, antifouling rings do not interfere with the instrument optics. The authors have designed plastic, reusable cup-like antifouling rings to slip over the optical lenses of a transmissometer. These rings have been used for several deployments on shallow moorings in Massachusetts Bay, MA and have increased the time before fouling degrades optical characteristics

Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

NASA Astrophysics Data System (ADS)

Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

2016-04-01

The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates were measured on sandy (permeable) and silty (diffusive) sediments, whereas significant differences of microbial O2 uptake were observed indeed between permeable and diffusive sediments. Nevertheless, when considering the multitude of different methods, we found that benthic respiration over the season seemed to be governed mainly by settling of fresh organic matter during calm periods and its rapid turnover in a region where strong tidal and wind-forced currents distribute suspended particles over large areas. Summer pelagic respiration rates were an order of magnitude higher then benthic rates, and account for 88-93% of total respiration, which represents 79-98% of pelagic primary production. Our measurements of benthic respiration account for 7-12% of the total in the German Bight, which is lower compared to earlier studies. Strong tidal and wind-forced currents along with the lack of complex three-dimensional biogenic structures seem to prevent settling of suspended matter and foster resuspension, thereby supporting pelagic turnover processes. Hence, we assume that benthic turnover might have been higher before systematic bottom trawling destroyed the bottom hydrobiological regime. Today, due to the strong current regime in the German Bight, the pelagic system appears to be a largely closed system of production and respiration, with comparably little for export to the benthic system due to absence of biogenic structures. References Callaway R, Engelhard GH, Dann J, Cotter J, Rumohr H (2007) One century of North Sea epibenthos and fishing: comparison between 1902-1912, 1982-1985 and 2000. Marine Ecology Progress Series 346, 27-43. Christiansen S (2009) Towards good environmental status - A network of marine protected areas for the North Sea. In: Lutter S (ed) WWF Germany, Fankfurt/Main Emeis K-C, van Beusekom J, Callies U, Ebinghaus R, Kannen A, Kraus G, Kröncke I, Lenhart H, Lorkowski I, Matthias V, Möllmann C, Pätsch J, Scharfe M, Thomas H, Weisse R, Zorita E (2015) The North Sea -A shelf sea in the Anthropocene. Journal of Marine Systems 141:18-33 Heip CHR, Goosen NK, Herman PMJ, Kromkamp J, Middelburg JJ, Soetaerd K (1995) Production and consumption of biological particles in temperate tidal estuaries. Oceanography and Marine Biology: an Annual Review 33:1-149 Kröncke I (2011) Changes in Dogger Bank macrofauna communities in the 20th century caused by fishing and climate. Estuarine, Coastal and Shelf Sciences 94 (3): 234-245. Neumann H, Diekmann R, Kröncke I (2016) The influence of habitat characteristics and fishing effort on functional composition of epifauna in the south-eastern North Sea. Estuarine, Coastal and Shelf Sciences 169: 182-194. Olsen OT (1883) The Piscatorial Atlas of the North Sea, English and St. George's Channels. Taylor and Francis, London Reiss H, Greenstreet S, Sieben K, Ehrich S, Piet G, Quirijns F, Robinson F, Wolff W, Kröncke I (2009) Effects of fishing disturbance on benthic communities and secondary production within an intensively fished area. Marine Ecology Progress Series 394:201-213

Benthic Resources Assessment Technique Evaluation of Disposal Sites in Puget Sound and Adjacent Waters,

DTIC Science & Technology

1986-12-01

of potential impacts to demersal fish feeding habitat. sites. 2. One aspect of benthic habitat quality is the relative amount of trophic support that...a given benthic habitat provides demersal bottom- feeding fishes. Analytical procedures have been developed at the U.S. Army Engineer Waterways...suspend the larger material and to allow fine sands, silts and clays to pass through the screens. Residual material was 2 I! Ii placeL a cloth bags that

Add-on conservation benefits of marine territorial user rights fishery policies in central Chile.

PubMed

Gelcich, Stefan; Godoy, Natalio; Prado, Luis; Castilla, Juan Carlos

2008-01-01

To combine the rational use of marine benthic resources and economic development of small-scale fishers, Chile passed legislation in 1991 establishing a comanagement policy that grants exclusive territorial user rights for fisheries (TURFs) to artisanal fisher organizations in well-defined inshore coastal areas, known as Management and Exploitation Areas for Benthic Resources (MEABRs). In general the policy has been proclaimed a management and economic success because benthic resource abundances have increased inside MEABRs in comparison with open-access areas. However, there is a lack of studies assessing the impact of this management policy on nontargeted subtidal species and community assemblages and the policy's implications for biodiversity and conservation. This study starts to fill this gap and links the allocation of TURFs for benthic resources with add-on conservation benefits for species that are not directly linked with the fishery policy. Comparative subtidal surveys inside vs. outside MEABRs were used to assess the effects of three MEABRs on managed targeted benthic species, biodiversity (species richness), and community assemblages in central Chile. Surveys focused exclusively on subtidal kelp forest habitats dominated by Lessonia trabeculata, spanning 4-12 m in depth and with similar levels of habitat complexity. The study comprised: (1) quantification of kelp forest complexity, (2) understory survey of sessile species, (3) quantification of conspicuous benthic macroinvertebrates, including those under management, and (4) quantification of reef-fish species inside the kelp habitat. Results showed population enhancement of target-managed invertebrates inside MEABRs. Moreover, reef-fish species were significantly more diverse and abundant inside MEABRs, and community assemblages of nontarget benthic invertebrates and reef fish were significantly different inside vs. outside MEABRs. The comanagement of inshore benthic resources in Chile, through MEABRs aims for the sustainability of invertebrate and algae stocks. However, our study shows that this management tool, which in practice restricts access to the entire management area, provides important conservation add-on effects for species that are not the focus of the management policies. Therefore, in Chile, the hundreds of already established MEABRs could represent an important ancillary network, which complements the biodiversity objectives of fully protected areas such as no-take marine protected areas or others.

Comparison of Adjective vs. Benthic Sources of Nutrients to a Former Salt Pond under Restoration

NASA Astrophysics Data System (ADS)

Topping, B.; Kuwabara, J. S.; Garrett, K.; Takekawa, J.; Piotter, S.; Parchaso, F.

2013-12-01

With the implementation of the South Bay Restoration Program in 2008, water quality in the Alviso Salt Ponds, California, has been monitored to document the effects of changing hydrologic connections among the ponds and the adjacent pond, slough and estuary. In 2010 and 2012, pore-water profilers (U.S. Patent 8,051,727 B1) were deployed in Pond A3W, a former salt pond just north of Moffett Federal Airfield that mixes hydrologically through culverts and weirs with Guadalupe Slough and neighboring ponds, to assess the magnitude of diffusive benthic flux, generated primarily by remobilization of surface-reactive solutes in bed sediment accumulated over annual to decadal time scales. The study, focusing on macronutrient sources that may stimulate harmful algal blooms, revealed that orthophosphate, ammonia, and silica benthic flux were consistently positive (out of the sediment) in both 2010 and 2012, while nitrate and nitrite fluxes were negligible. Because tidal height can affect the size and direction of flow, a diurnal study of nutrient advective flux into and out of the pond was measured during neap and spring tides. These advective fluxes (kg/yr) were compared to benthic flux estimates for the pond extrapolated over the 2.27 (km2) pond surface. Benthic flux of inorganic nitrogen species, averaged over all sites and dates, was about 80,000 + 48,000 kilograms per year (kg/yr), well above the adjective flux range of -50 to 1,500 kg/yr. By contrast, the average benthic flux of orthophosphate was about 12,000 + 4,400 kg/yr, well below the advective flux range of 21,500 to 30,000 kg/yr. Benthic flux estimates determined by porewater gradients do not include enhancement processes such as bioturbation, bioirrigation, wind resuspension, and potential groundwater inflows. However, they provide a conservative measure and can be an effective management screening tool. These results indicate that benthic transport may be an important source of biologically reactive solutes for both nutrients and toxicants, an important consideration during restoration since there are trophic transfer implications.

Lake Ontario benthic prey fish assessment, 2015

USGS Publications Warehouse

Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

2016-01-01

Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single juvenile Bloater Coregonus hoyi, was captured during the spring bottom trawl survey at 95m (312 ft) near Oswego, NY. This native, deep-water prey fish, last captured in Lake Ontario survey trawls in 1983, is part of an international, collaborative coregonid restoration effort in the Great Lakes.

Response of Benthic Microalgae to Phosphorus Inputs in Grand Bay National Estuarine Research Reserve

NASA Astrophysics Data System (ADS)

Sleek, J.; Caffrey, J. M.; Baine, G. C., II; Capps, R.

2016-12-01

Benthic microalgae are an important, but often understudied component of shallow, photic estuaries in the Gulf of Mexico. Grand Bay National Estuarine Research Reserve (GBNERR) is located in a small and relatively pristine estuary in the northern Gulf of Mexico. Freshwater input into the estuary is primarily local runoff from bayous and tidal creeks, including Bayou Cumbest, Bayou Heron, and Bangs Lake. Nutrient loading to Grand Bay is relatively small, with ambient nutrient concentrations often below detection. However, several events in 2005, 2012, 2013, and 2014 due to breaches in a containment levee from a gypsum stack have led to high phosphate levels near Bangs Lake. GBNERR staff assembled a phosphate working group to investigate scientific questions related to these phosphate loadings. This working group includes members from GBNERR, regional universities, marine labs, and Mississippi Department of Environmental Quality. In marine ecosystems, nitrogen availability normally limits growth of phytoplankton and previous research has shown this to be the case in Grand Bay. However, little is known about benthic microalgae in Grand Bay and what their response is to these phosphorus inputs. Between 2013 and 2015, summer concentrations of water column and benthic chlorophyll a were positively correlated, with the highest concentrations occurring in Bangs Lake. Benthic chlorophyll was also positively correlated with the percent surface irradiance reaching the bottom. Bottom light levels range from 3 to 36% surface irradiance. This along with experiments that showed no enhancement of growth of benthic microalgae following addition of nutrients (ammonium, phosphate or both) suggest that benthic microalgae are predominantly light limited rather than nutrient limited. Preliminary nitrogen fixation measurements suggest that nitrogen fixation was positively correlated with extractable phosphate concentrations. Thus, enhanced sediment nitrogen fixation and excess phosphate from the fertilizer plant runoff in this high light environment may enhance benthic microalgal production. The results of this research are part of the larger effort by the phosphate working group to understand the impact of repeated phosphate impacts. These results will provide information needed to help manage the reserve.

Application of an eddy correlation system for the estimation of oxygen benthic fluxes in coastal permeable sediments impacted by submarine groundwater discharge

NASA Astrophysics Data System (ADS)

Donis, D.; Janssen, F.; Böttcher, M.; McGinnis, D.; Holtappels, M.; Wenzhöfer, F.

2012-04-01

Measurements of solute exchange across the sediment-water interface are crucial for marine environment monitoring. This interface has fundamental filter functions for the mass exchange between the seafloor and the water column. Being a non-invasive technique, the eddy correlation method, is probably the most accurate measurement for benthic fluxes. It does not interfere with local hydrodynamics and integrates over large areas, showing considerable advantages compared to traditional methods, i.e., microprofiles and benthic chambers. One of the most important exchange processes across the sediment-water interface is flux of oxygen, which is a predominant control factor for the biogeochemical activity in the sediment, carbon processing and the composition of benthic communities. The eddy correlation method performs simultaneous recordings of vertical velocities and oxygen concentrations at a specific distance to the seafloor and is becoming a standard method for resolving dissolved oxygen fluxes in aquatic systems. However, data treatment and interpretation, especially in shallow environments, is still challenging. One major concern in eddy correlation studies of coastal environments is how to consider surface wave motions that can dominate the turbulence range and that may bias flux calculations. A critical part of the data treatment thus is the removal of wave biases from the vertical velocity component, by separating the wave frequency oscillations (due to a tilted or miss-aligned sensor) from those containing meaningful flux contributions. Here we present in situ benthic oxygen exchange rates as determined by an eddy correlation system (ECS) and simultaneously deployed stirred benthic chambers. The study was carried out in a coastal ecosystem of the southern Baltic Sea that was impacted by low salinity groundwater discharge (Hel peninsula, Poland). Oxygen fluxes determined with ECS compared well with results from benthic chambers. Flux data and seepage rates are discussed in the context of groundwater and their importance for benthic biogeochemical processes in shallow sandy sediments. This work was supported by 7th framework EU ITN-project SENSEnet and BONUS+ project AMBER.

A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers.

PubMed

Li, Fengqing; Sundermann, Andrea; Stoll, Stefan; Haase, Peter

2016-11-01

Dispersal capacity plays a fundamental role in the riverine benthic invertebrate colonization of new habitats that emerges following flash floods or restoration. However, an appropriate measure of dispersal capacity for benthic invertebrates is still lacking. The dispersal of benthic invertebrates occurs mainly during the aquatic (larval) and aerial (adult) life stages, and the dispersal of each stage can be further subdivided into active and passive modes. Based on these four possible dispersal modes, we first developed a metric (which is very similar to the well-known and widely used saprobic index) to estimate the dispersal capacity for 802 benthic invertebrate taxa by incorporating a weight for each mode. Second, we tested this metric using benthic invertebrate community data from a) 23 large restored river sites with substantial improvements of river bottom habitats dating back 1 to 10years, b) 23 unrestored sites very close to the restored sites, and c) 298 adjacent surrounding sites (mean±standard deviation: 13.0±9.5 per site) within a distance of up to 5km for each restored site in the low mountain and lowland areas of Germany. We hypothesize that our metric will reflect the temporal succession process of benthic invertebrate communities colonizing the restored sites, whereas no temporal changes are expected in the unrestored and surrounding sites. By applying our metric to these three river treatment categories, we found that the average dispersal capacity of benthic invertebrate communities in the restored sites significantly decreased in the early years following restoration, whereas there were no changes in either the unrestored or the surrounding sites. After all taxa had been divided into quartiles representing weak to strong dispersers, this pattern became even more obvious; strong dispersers colonized the restored sites during the first year after restoration and then significantly decreased over time, whereas weak dispersers continued to increase. The successful application of our metric to river restoration might be promising in further applications of this metric, for example, in analyzing metacommunity structure or community's recovery from extreme events such as floods, droughts or catastrophic pollution episodes. Copyright © 2016 Elsevier B.V. All rights reserved.

A review of benthic faunal surveys in San Francisco Bay

USGS Publications Warehouse

Nichols, Frederic H.

1973-01-01

During the past 60 years, considerable effort has been expended in studies of the relations of the biotic community and physicochemical characteristics of San Francisco Bay water. In very recent years these studies have emphasized the relations between the 'state of health' of bottom-living invertebrates (the benthos) and the levels of pollutants in the bay. Benthic organisms, generally sessile, are unable to escape deleterious environmental changes, and they reflect these changes in alterations of normal species composition of assemblages and species abundance. Data that expands understanding of these relations in urbanized areas such as San Francisco Bay are critical. Because of the implications of such data in control of water quality, the U.S. Geological Survey undertook a review of the results and major conclusions of San Francisco Bay benthic surveys. The size and species composition of faunal assemblages are largely controlled by the salinity of the water, the texture of the bottom sediments, and locally by wastes discharged into the bay. Efforts to describe the structure and function of benthic communities of the bay and to quantify the effects of waste discharge on them have been hampered by inconsistent and often faulty sampling methodology and species identification. Studies made show a lack of information on the normal life processes of the organisms concerned. The diversity index (a mathematical expression of the number of kinds of organisms present at a location), commonly used to describe the 'health' of the benthic community, has been employed without regard for the need for standardizing methodology and species identifications or for understanding natural biological processes that affect such mathematical indices. There are few reliable quantitative data on the distribution of benthic organisms in San Francisco Bay with which future assessments of the 'health' of the benthic community might be compared. Methods for study of the benthos must be standardized, identifications of species verified by trained taxonomists, and new field and laboratory studies undertaken before we can expect to obtain an accurate description of the benthic fauna and its relations with the environment.

[Monthly changes in the benthic macro-invertebrate community structure in the habitats of Phragmites australis marsh in the Dongtan wetland of the Yangtze River estuary, China].

PubMed

Zhang, Heng; Ye, Jin Yu; Liang, Xiao Li; Zhu, Xiao Jing; Jin, Shao Fei; Chen, Yuan Ge; Zhang, Jia Rui; Dai, Yang

2017-04-18

Based on the data of the benthic macro-invertebrates community in the Phragmites australis marsh in the Dongtan Wetland of the Yangtze River estuary collected from May 2015 to April 2016, we evaluated the monthly variations in the species composition, biodiversity and community structure of the benthic macro-invertebrates. The results showed that the average height and degree of coverage for P. australis increased monthly from March to August, and then deceased from September. The density and aboveground biomass (dry mass, g) of P. australis peaked in July. A total of twenty species (including 2 species only identified to genus level and 2 species identified to family level) were found in the survey periods, including 11 Gastropoda, 5 Malacostraca, 2 Insecta and 2 Polychaeta. Three snail species (Assiminea latericea, Assiminea violacea and Cerithideopsis largillierti) dominated the benthic communities in terms of numerical abundance. The number of epifauna species was the most (11 species), followed by 5 burrowing species and 4 infauna species. There were significant monthly variations in the density and biomass of the macro-invertebrates. The density and biomass of benthic community reached the maximum in August. The Margalef's species richness index (D) and Shannon index (H) showed significant differences monthly, but Pielou's index (J) except in November. Three macro-zoobenthic assemblages were identified with the 42% similarity level. The non-Metric Multidimensional scaling plot indicates that the benthic community in May, October and November was distinct compared to that in the other months. The present study suggested the density of the benthic macro-invertebrates community in the P. australis marshes was somewhat correlated with water temperature, underground biomass and salinity. But those correlation were not significant (P>0.05). Because of the continuous impact of anthropogenic activities, the biodiversity of the benthic macro-invertebrate community has been decreasing for several years. More attention should be paid to the habitat value of the P. australis marshes in the future.

Benthic oxygen consumption on continental shelves off eastern Canada

NASA Astrophysics Data System (ADS)

Grant, Jonathan; Emerson, Craig W.; Hargrave, Barry T.; Shortle, Jeannette L.

1991-08-01

The consumption of phytoplankton production by the benthos is an important component of organic carbon budgets for continental shelves. Sediment texture is a major factor regulating benthic processes because fine sediment areas are sites of enhanced deposition from the water column, resulting in increased organic content, bacterial biomass and community metabolism. Although continental shelves at mid- to high latitudes consist primarily of coarse relict sediments ( PIPER, Continental Shelf Research, 11, 1013-1035), shelf regions of boreal and subarctic eastern Canada contain large areas of silt and clay sediments ( FADER, Continental Shelf Research, 11, 1123-1153). We collated estimates of benthic oxygen consumption in coarse (<20% silt-clay, <0.5% organic matter) and fine sediments (20% silt-clay, 0.5% organic matter) for northwest Atlantic continental shelves including new data for Georges Bank, the Scotian Shelf, the Grand Banks of Newfoundland and Labrador Shelf. Estimates were applied to the areal distribution of sediment type on these shelves to obtain a general relationship between sediment texture and benthic carbon consumption. Mean benthic oxygen demand was 2.7 times greater in fine sediment than in coarse sediment, when normalized to mean annual temperature. In terms of carbon equivalents, shelf regions with minimal fine sediment (Georges Bank, the Grand Banks of Newfoundland-northeast Newfoundland) consumed only 5-8% of annual primary production. Benthos of the Gulf of Maine (100% fine sediment) and the Scotian Shelf (35% fine sediment) utilized 16-19% of primary production. Although 32% of the Labrador Shelf area contained fine sediments, benthic consumption of pelagic production (8%) was apparently limited by low mean annual temperature (2°C). These results indicate that incorporation of sediment-specific oxygen uptake into shelf carbon budgets may increase estimates of benthic consumption by 50%. Furthermore, respiration and production by large macrofauna allow an even greater proportion of primary production to enter benthic pathways. Fine sediment areas (shelf basins or "depocenters") are postulated to be sites of enhanced biological activity which must be considered in the modelling of shelf carbon budgets and the role of the benthos in demersal fisheries.

Response of Benthic Microalgae to Phosphorus Inputs in Grand Bay National Estuarine Research Reserve

NASA Astrophysics Data System (ADS)

Sleek, J.; Caffrey, J. M.; Baine, G. C., II; Capps, R.

2016-02-01

Benthic microalgae are an important, but often understudied component of shallow, photic estuaries in the Gulf of Mexico. Grand Bay National Estuarine Research Reserve (GBNERR) is located in a small and relatively pristine estuary in the northern Gulf of Mexico. Freshwater input into the estuary is primarily local runoff from bayous and tidal creeks, including Bayou Cumbest, Bayou Heron, and Bangs Lake. Nutrient loading to Grand Bay is relatively small, with ambient nutrient concentrations often below detection. However, several events in 2005, 2012, 2013, and 2014 due to breaches in a containment levee from a gypsum stack have led to high phosphate levels near Bangs Lake. GBNERR staff assembled a phosphate working group to investigate scientific questions related to these phosphate loadings. This working group includes members from GBNERR, regional universities, marine labs, and Mississippi Department of Environmental Quality. In marine ecosystems, nitrogen availability normally limits growth of phytoplankton and previous research has shown this to be the case in Grand Bay. However, little is known about benthic microalgae in Grand Bay and what their response is to these phosphorus inputs. Between 2013 and 2015, summer concentrations of water column and benthic chlorophyll a were positively correlated, with the highest concentrations occurring in Bangs Lake. Benthic chlorophyll was also positively correlated with the percent surface irradiance reaching the bottom. Bottom light levels range from 3 to 36% surface irradiance. This along with experiments that showed no enhancement of growth of benthic microalgae following addition of nutrients (ammonium, phosphate or both) suggest that benthic microalgae are predominantly light limited rather than nutrient limited. Preliminary nitrogen fixation measurements suggest that nitrogen fixation was positively correlated with extractable phosphate concentrations. Thus, enhanced sediment nitrogen fixation and excess phosphate from the fertilizer plant runoff in this high light environment may enhance benthic microalgal production. The results of this research are part of the larger effort by the phosphate working group to understand the impact of repeated phosphate impacts. These results will provide information needed to help manage the reserve.

The biogeochemistry of Arabian Sea surficial sediments: A review of recent studies

NASA Astrophysics Data System (ADS)

Cowie, Greg

2005-05-01

The Arabian Sea’s unusual features have drawn attention from oceanographers and other scientists since the late 1800s. Water-column processes, including the seasonally reversing monsoon-driven circulation and the associated upwelling and productivity, as well as a basin-wide, mid-water layer of intense oxygen depletion have been the foci of many studies. However, the importance of benthic processes in the Arabian Sea has also been recognized. Both the abyssal region and the continental margins have been sites of major studies focused on the biology and geochemistry of surficial sediments and key biogeochemical processes that occur across the benthic boundary layer, especially in the last decade. A summary of benthic studies carried out up to the 1990s is followed by descriptions and syntheses of biological and geochemical studies conducted since that time. The results highlight that the benthic system of the Arabian Sea is highly dynamic, with evidence of strong benthic-pelagic coupling displayed as a cross-basin trophic gradient and in benthic response to seasonal variability in productivity and C flux. Benthic biogeochemical processes, especially on the upper slope and within the oxygen minimum zone, including denitrification, phosphogenesis, and fluxes of trace metals, nutrients and dissolved organic matter, may be of global significance but remain poorly quantified. Sedimentary organic matter distributions across the Arabian Sea have served to fuel an ongoing debate over the controlling environmental factors. Recent studies have illustrated that factors including the supply of reactive organic matter, oxygen exposure, digestion and mixing by the benthos, sorptive preservation, and sediment dilution, winnowing and down-slope transport, all interact in a complex fashion and with varied impact to determine distributions of sedimentary organic matter across the different margins of this basin. Notable features include the facts that it is only at the core of the oxygen minimum zone on the Indian and Pakistan margins where laminated sediments occur and oxygen concentrations appear to fall below the threshold required for macrobenthos, and that sulfate reduction is surprisingly suppressed when compared to rates observed on other upwelling margins with oxygen minimum zones. The review is completed by suggestions for future benthic research in the Arabian Sea.

Microplastics in the benthic invertebrates from the coastal waters of Kochi, Southeastern Arabian Sea.

PubMed

Naidu, S A; Ranga Rao, V; Ramu, K

2018-01-05

This study examined microplastic particles present in the benthic invertebrates Sternaspis scutata, Magelona cinta (deposit feeders) and Tellina sp. (suspension feeder) from the surface sediments of off-Kochi, southwest coast of India. The microplastic particles and thread-like fibres detected in these organisms were identified to be polystyrene by using DXR Raman microscope. Examination of the microplastic particle in Sternaspis scutata by epifluorescent microscopy showed fragmentation marks on the surface suggesting that the microplastic particle was degraded/weathered in nature. The study provides preliminary evidence of the presence of microplastics in benthic fauna from the coastal waters of India. However, further studies are required to understand the sources, distribution, fate and toxicity of the different types of microplastics in benthic invertebrates in order to identify any potential threats to higher trophic level organisms.

Clinch River remedial investigation task 9 -- benthic macroinvertebrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, E.M. Jr.

1994-08-01

This report summarizes the results of Task 9 of the TVA/Department of Energy (DOE) Interagency Agreement supporting DOE`s Clinch River Remedial Investigation. Species lists and densities (numbers/m{sup 2}) of benthic macroinvertebrates sampled at 16 sites in the Clinch River and Poplar Creek embayments of upper Watts Bar Reservoir near Oak Ridge, Tennessee, in March, 1994, are presented and briefly discussed. Data are also analyzed to assess and compare quality of benthic communities at each site, according to methods developed for TVA`s Reservoir Vital Signs Monitoring Program. Results of this study will be incorporated with other program tasks in a comprehensivemore » report prepared by Oak Ridge National Laboratory in 1995, which will, in part, assess the effect of sediment contaminants on benthic macroinvertebrate communities in Watts Bar Reservoir.« less

Middle Miocene benthic foraminifera from the Al Khums area, northwestern Libya

NASA Astrophysics Data System (ADS)

El Baz, Sherif M.; Al Furjany, Ahmed

2018-02-01

The present study deals with the benthic foraminifera from three sections cropping out in the Al Khums area, northwestern Libya. Lithostratigraphically, these outcrops belong to the Al Khums Formation, which is locally subdivided into two informal members: An Naggazah and Ras Al Mannubiyah. Detailed investigation of the foraminiferal content led to the recognition of 27 species belonging to 16 genera and 13 families. The absence of index planktonic foraminifera does not enable the recognition of any planktonic biozone within the Al Khums Formation. The presence of the larger benthic foraminifera Borelis melo melo enables the assignment of a Middle Miocene age to this rock unit. The studied sections characterized by the common occurrence of benthic foraminiferal species living in a shallow neritic environment. This conclusion is corroborated by the co-occurrence of large oysters, corals and algae.

Influence of sea squirt (Halocynthia roretzi) aquaculture on benthic-pelagic coupling in coastal waters: A study of the South Sea in Korea

NASA Astrophysics Data System (ADS)

Lee, Jae Seong; Kim, Sung-Han; Kim, Yong-Tae; Hong, Sok Jin; Han, Jeong Hee; Hyun, Jung-Ho; Shin, Kyung-Hoon

2012-03-01

The influence of sea squirt aquaculture on benthic-pelagic coupling was evaluated in semi-enclosed Korean coastal waters with an in situ benthic chamber and results show for the first time that suspended sea squirt cultures play an important role in benthic-pelagic coupling in the coastal zone. Measurements of primary production, vertical particulate fluxes, and benthic fluxes were made at two stations, a sea squirt (Halocynthia roretzi) farm (SSF) and an area of organic-matter-enriched sediment in Jinhae Bay. The vertical material fluxes of organic carbon, nitrogen, and biogenic silicate (BSi) were significantly higher at SSF than in Jinhae Bay, indicating massive biodeposits in the surface sediments at SSF. The organic carbon oxidation rates (Cox) were estimated after correction for CaCO3 dissolution. The average Cox at SSF (204 mmol C m-2 d-1) was significantly higher than that in the organic-enriched Jinhae Bay sediment (77 mmol C m-2 d-1). The organic carbon burial fluxes were determined using vertical profiles of organic carbon of up to 30 cm and the sedimentation rate calculated from the excess 210Pb distribution. At both stations, ˜95% of the settled organic carbon was oxidized and only ˜5% was buried in the deep sediment layer. The benthic fluxes of dissolved inorganic nitrogen and phosphate at SSF were 2-12 times higher than in Jinhae Bay, corresponding to 85%, and 270%, respectively, of the requirements for primary production.

Late cretaceous foraminifera, paleoenvironments, and paleoceanography of the rosario formation, San Antonio del Mar, Baja California, Mexico

USGS Publications Warehouse

Maestas, Y.; MacLeod, K.G.; Douglas, R.; Self-Trail, J.; Ward, P.D.

2003-01-01

The 315 m of Rosario Formation exposed at the San Antonio del Mar (SADM) section (Baja California, Mexico) contains moderately-to-well preserved benthic and planktic foraminifera, calcareous nannofossils, and molluscs. Nannofossils suggest most of the SADM section was deposited within a narrow interval of the late Campanian (CC21-CC22), whereas foraminifera and molluscs suggest a younger maximum age (younger than the Globotruncana ventricosa Zone) and allow deposition over a longer interval of time. Planktic foraminifera at SADM represent common Tethyan taxa. They are largely restricted to the lower and middle portions of the section and comprise 0-???40% of foraminiferal assemblages. Stable isotopic analyses of Rugoglobigerina rugosa yield ??18OV-PDB values from -2.27%, to -2.82%, corresponding to salinity-corrected paleotemperature estimates of 26-30??C for the Late Cretaceous eastern Pacific. These estimates are as warm as modern tropical temperatures and are similar to tropical paleotemperature estimates from ??18O analyses of exceptionally preserved Maastrichtian samples; however, they are considerably warmer than most tropical Campanian-Maastrichtian estimates. Benthic foraminifera indicate outer shelf paleodepths with a slight increase in depth or decrease in benthic oxygen levels in the upper parts of the interval studied. The change in the benthic assemblage corresponds to an ???1??? positive shift in benthic ??O18, suggesting a relationship between benthic assemblages and an inferred increase in the local intensity of upwelling.

Invasive Mussels Alter the Littoral Food Web of a Large Lake: Stable Isotopes Reveal Drastic Shifts in Sources and Flow of Energy

PubMed Central

Ozersky, Ted; Evans, David O.; Barton, David R.

2012-01-01

We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid) and recent (postdreissenid) samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production. PMID:23284673

Widespread anatoxin-a detection in benthic cyanobacterial mats throughout a river network

PubMed Central

Kudela, Raphael M.; Power, Mary E.

2018-01-01

Benthic algae fuel summer food webs in many sunlit rivers, and are hotspots for primary and secondary production and biogeochemical cycling. Concerningly, riverine benthic algal assemblages can become dominated by toxic cyanobacteria, threatening water quality and public health. In the Eel River in Northern California, over a dozen dog deaths have been attributed to cyanotoxin poisonings since 2000. During the summers of 2013–2015, we documented spatial and temporal patterns of cyanotoxin concentrations in the watershed, showing widespread distribution of anatoxin-a in benthic cyanobacterial mats. Solid phase adsorption toxin tracking (SPATT) samplers were deployed weekly to record dissolved microcystin and anatoxin-a levels at 10 sites throughout the watershed, and 187 Anabaena-dominated or Phormidium-dominated cyanobacterial mat samples were collected from 27 locations to measure intracellular anatoxin-a (ATX) and microcystins (MCY). Anatoxin-a levels were higher than microcystin for both SPATT (mean MCY = 0.8 and ATX = 4.8 ng g resin-1 day-1) and cyanobacterial mat samples (mean MCY = 0.074 and ATX = 1.89 μg g-1 DW). Of the benthic mats sampled, 58.9% had detectable anatoxin-a (max = 70.93 μg g-1 DW), while 37.6% had detectable microcystins (max = 2.29 μg g-1 DW). SPATT cyanotoxin levels peaked in mid-summer in warm mainstem reaches of the watershed. This is one of the first documentations of widespread anatoxin-a occurrence in benthic cyanobacterial mats in a North American watershed. PMID:29775481

Castaways can't be choosers - Homogenization of rafting assemblages on floating seaweeds

NASA Astrophysics Data System (ADS)

Gutow, Lars; Beermann, Jan; Buschbaum, Christian; Rivadeneira, Marcelo M.; Thiel, Martin

2015-01-01

After detachment from benthic habitats, the epibiont assemblages on floating seaweeds undergo substantial changes, but little is known regarding whether succession varies among different seaweed species. Given that floating algae may represent a limiting habitat in many regions, rafting organisms may be unselective and colonize any available seaweed patch at the sea surface. This process may homogenize rafting assemblages on different seaweed species, which our study examined by comparing the assemblages on benthic and floating individuals of the fucoid seaweeds Fucus vesiculosus and Sargassum muticum in the northern Wadden Sea (North Sea). Species richness was about twice as high on S. muticum as on F. vesiculosus, both on benthic and floating individuals. In both seaweed species benthic samples were more diverse than floating samples. However, the species composition differed significantly only between benthic thalli, but not between floating thalli of the two seaweed species. Separate analyses of sessile and mobile epibionts showed that the homogenization of rafting assemblages was mainly caused by mobile species. Among these, grazing isopods from the genus Idotea reached extraordinarily high densities on the floating samples from the northern Wadden Sea, suggesting that the availability of seaweed rafts was indeed limiting. Enhanced break-up of algal rafts associated with intense feeding by abundant herbivores might force rafters to recolonize benthic habitats. These colonization processes may enhance successful dispersal of rafting organisms and thereby contribute to population connectivity between sink populations in the Wadden Sea and source populations from up-current regions.

Streamflow characteristics and benthic invertebrate assemblages in streams across the western United States

USGS Publications Warehouse

Brasher, Anne M.D.; Konrad, Chris P.; May, Jason T.; Edmiston, C. Scott; Close, Rebecca N.

2010-01-01

Hydrographic characteristics of streamflow, such as high-flow pulses, base flow (background discharge between floods), extreme low flows, and floods, significantly influence aquatic organisms. Streamflow can be described in terms of magnitude, timing, duration, frequency, and variation (hydrologic regime). These characteristics have broad effects on ecosystem productivity, habitat structure, and ultimately on resident fish, invertebrate, and algae communities. Increasing human use of limited water resources has modified hydrologic regimes worldwide. Identifying the most ecologically significant hydrographic characteristics would facilitate the development of water-management strategies.Benthic invertebrates include insects, mollusks (snails and clams), worms, and crustaceans (shrimp) that live on the streambed. Invertebrates play an important role in the food web, consuming other invertebrates and algae and being consumed by fish and birds. Hydrologic alteration associated with land and water use can change the natural hydrologic regime and may affect benthic invertebrate assemblage composition and structure through changes in density of invertebrates or taxa richness (number of different species).This study examined associations between the hydrologic regime and characteristics of benthic invertebrate assemblages across the western United States and developed tools to identify streamflow characteristics that are likely to affect benthic invertebrate assemblages.

Particle Mass in Deep-Water Benthic Nepheloid Layers: a Global Synthesis

NASA Astrophysics Data System (ADS)

Mishonov, A. V.; Gardner, W. D.; Richardson, M. J.

2016-12-01

The mass of particles in benthic nepheloid layers in the deep ocean is mapped using profiles of beam attenuation coefficient obtained with transmissometers interfaced with CTDs during WOCE, SAVE, JGOFS, CLIVAR-Repeat Hydrography, and other programs during the last four decades using data from over 8000 profiles from >70 cruises. We map the maximum concentration of particle mass near the seafloor and integrate the particle mass throughout the benthic nepheloid layer. In the Atlantic Ocean particle mass is greater in areas where eddy kinetic energy is high in overlying waters. Areas of high bottom particle concentrations and integrated benthic nepheloid layer particle loads include the western North Atlantic beneath the Gulf Stream meanders and eddies, Argentine Basin, parts of the Southern Ocean and areas around South Africa. Particle concentrations are low in most of the Pacific and tropical and subtropical Atlantic away from margins. This synthesis is useful for GEOTRACES and other global programs where knowing particle distribution is critical for understanding trace metal absorption, sediment-water exchange and near-bottom processes. Additionally, our synthesis provides baseline data to identify where mining of metal-rich nodules and metal sulfides on the seafloor may impact the benthic environment.

Potential impact of global climate change on benthic deep-sea microbes.

PubMed

Danovaro, Roberto; Corinaldesi, Cinzia; Dell'Anno, Antonio; Rastelli, Eugenio

2017-12-15

Benthic deep-sea environments are the largest ecosystem on Earth, covering ∼65% of the Earth surface. Microbes inhabiting this huge biome at all water depths represent the most abundant biological components and a relevant portion of the biomass of the biosphere, and play a crucial role in global biogeochemical cycles. Increasing evidence suggests that global climate changes are affecting also deep-sea ecosystems, both directly (causing shifts in bottom-water temperature, oxygen concentration and pH) and indirectly (through changes in surface oceans' productivity and in the consequent export of organic matter to the seafloor). However, the responses of the benthic deep-sea biota to such shifts remain largely unknown. This applies particularly to deep-sea microbes, which include bacteria, archaea, microeukaryotes and their viruses. Understanding the potential impacts of global change on the benthic deep-sea microbial assemblages and the consequences on the functioning of the ocean interior is a priority to better forecast the potential consequences at global scale. Here we explore the potential changes in the benthic deep-sea microbiology expected in the coming decades using case studies on specific systems used as test models. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Relating remotely sensed optical variability to marine benthic biodiversity.

PubMed

Herkül, Kristjan; Kotta, Jonne; Kutser, Tiit; Vahtmäe, Ele

2013-01-01

Biodiversity is important in maintaining ecosystem viability, and the availability of adequate biodiversity data is a prerequisite for the sustainable management of natural resources. As such, there is a clear need to map biodiversity at high spatial resolutions across large areas. Airborne and spaceborne optical remote sensing is a potential tool to provide such biodiversity data. The spectral variation hypothesis (SVH) predicts a positive correlation between spectral variability (SV) of a remotely sensed image and biodiversity. The SVH has only been tested on a few terrestrial plant communities. Our study is the first attempt to apply the SVH in the marine environment using hyperspectral imagery recorded by Compact Airborne Spectrographic Imager (CASI). All coverage-based diversity measures of benthic macrophytes and invertebrates showed low but statistically significant positive correlations with SV whereas the relationship between biomass-based diversity measures and SV were weak or lacking. The observed relationships did not vary with spatial scale. SV had the highest independent effect among predictor variables in the statistical models of coverage-derived total benthic species richness and Shannon index. Thus, the relevance of SVH in marine benthic habitats was proved and this forms a prerequisite for the future use of SV in benthic biodiversity assessments.

Effects of a crude oil spill on the benthic invertebrate community in the Gasconade River, Missouri

USGS Publications Warehouse

Poulton, Barry C.; Finger, Susan E.; Humphrey, S.A.

1997-01-01

Effects of a 3.3-million–L crude oil spill on the benthic macroinvertebrate community of the Gasconade River, a large river in Missouri, were evaluated by comparing several macroinvertebrate community indices in riffle and backwater habitats above and below the spill. Concentrations of total petroleum hydrocarbons (TPH) in sediments decreased dramatically in riffle habitats within 6 months of the spill, but elevated hydrocarbon levels (TPH = 80–270 μg/g) were still present in backwater habitats at the end of the study. Correspondingly, riffle macroinvertebrate communities recovered rapidly, but overall benthic diversity continued to be reduced in backwater areas until the end of the study 18 months after the spill. In addition, statistical analysis of benthic functional feeding groups revealed that both scrapers and shredders were reduced in backwater habitats below the oil spill. Decreased abundance of shredders and scrapers in these habitats is likely caused by oil contamination of aquatic sediments and associated organic matter required by these groups for food and substrate. Results of this study suggest that the persistence of oil in backwater habitats has a negative effect on the benthic community in large rivers.

Benthic Carbon Mineralization in Hadal Trenches: Insights From In Situ Determination of Benthic Oxygen Consumption

NASA Astrophysics Data System (ADS)

Luo, Min; Glud, Ronnie N.; Pan, Binbin; Wenzhöfer, Frank; Xu, Yunping; Lin, Gang; Chen, Duofu

2018-03-01

Hadal trenches have been proposed as depocenters of organic material and hot spots for organic matter mineralization. In this study, we for the first time quantified the total benthic O2 uptake in hadal trenches using in situ chamber incubations. Three trenches in the tropical Pacific were targeted and exhibited relatively high diagenetic activity given the great water depths, that is, the Mariana Trench (2.0 × 102 μmol O2 m-2 d-1, 10,853 m), the Mussau Trench (2.7 ± 0.1 × 102 μmol O2 m-2 d-1, 7,011 m), and the New Britain Trench (6.0 ± 0.1 × 102 μmol O2 m-2 d-1, 8,225 m). Combined with the analyses of total organic carbon and δ13C of total organic carbon in the sediments and previously published in situ O2 microprofiles from hadal settings, we suggest that hadal benthic carbon mineralization partly is governed by the surface production and also is linked to the distance from land. Therefore, we highlight that terrestrial organic matter can be of importance in sustaining benthic communities in some hadal settings.

Marine benthic habitat mapping of the West Arm, Glacier Bay National Park and Preserve, Alaska

USGS Publications Warehouse

Hodson, Timothy O.; Cochrane, Guy R.; Powell, Ross D.

2013-01-01

Seafloor geology and potential benthic habitats were mapped in West Arm, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, groundtruthed observations, and geological interpretations. The West Arm of Glacier Bay is a recently deglaciated fjord system under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the recently developed Coastal and Marine Ecological Classification Standard (CMECS) by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Due to the high flux of glacially sourced fines, mud is the dominant substrate within the West Arm. Water-column characteristics are addressed using a combination of CTD and circulation model results. We also present sediment accumulation data derived from differential bathymetry. These data show the West Arm is divided into two contrasting environments: a dynamic upper fjord and a relatively static lower fjord. The results of these analyses serve as a test of the CMECS classification scheme and as a baseline for ongoing and future mapping efforts and correlations between seafloor substrate, benthic habitats, and glacimarine processes.

Contrasting effects of ecosystem engineering by the cordgrass Spartina maritima and the sandprawn Callianassa kraussi in a marine-dominated lagoon

NASA Astrophysics Data System (ADS)

Pillay, D.; Branch, G. M.; Dawson, J.; Henry, D.

2011-01-01

Ecosystem engineering by plants and animals significantly influences community structure and the physico-chemical characteristics of marine habitats. In this paper we document the contrasting effects of ecosystem engineering by the cordgrass Spartina maritima and the burrowing sandprawn Callianassa kraussi on physico-chemical characteristics, microflora, macrofaunal community structure and morphological attributes in the high shore intertidal sandflats of Langebaan Lagoon, a marine-dominated system on the west coast of South Africa. Comparisons were made at six sites in the lagoon within Spartina and Callianassa beds, and in a "bare zone" of sandflat between these two habitats that lacks both sandprawns and cordgrass. Sediments in Spartina habitats were consolidated by the root-shoot systems of the cordgrass, leading to low sediment penetrability, while sediments in beds of C. kraussi were more penetrable, primarily due to the destabilising effects of sandprawn bioturbation. Sediments in the "bare zone" had intermediate to low values of penetrability. Sediment organic content was lowest in bare zones and greatest in Spartina beds, while sediment chl- a levels were greatest on bare sand, but were progressively reduced in the Spartina and Callianassa beds. These differences among habitats induced by ecosystem engineering in turn affected the macrofauna. Community structure was different between all three habitats sampled, with species richness being surprisingly greater in Callianassa beds than either the bare zone or Spartina beds. In general, the binding of surface sediments by the root systems of Spartina favoured rigid-bodied, surface-dwelling and tube-building species, while the destabilising effect of bioturbation by C. kraussi favoured burrowing species. The contrasting effects of these ecosystem engineers suggest that they play important roles in increasing habitat heterogeneity. Importantly, the role of bioturbation by C. kraussi in enhancing macrofaunal richness was unexpected. By loosening sediments, reducing anoxia and enhancing organic content, C. kraussi may engineer these high shore habitats to ameliorate environmental stresses or increase food availability.

BENTHIC MACROFAUNA-HABITAT ASSOCIATIONS IN WILLAPA BAY, WASHINGTON, USA

EPA Science Inventory

Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1...

Evaluation of dredged material proposed for ocean disposal from Bronx River Project Area, New York

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruendell, B.D.; Gardiner, W.W.; Antrim, L.D.

1996-12-01

The objective of the Bronx River project was to evaluate proposed dredged material from the Bronx River project area in Bronx, New York, to determine its suitability for unconfined ocean disposal at the Mud Dump Site. Bronx River was one of five waterways that the US Army Corps of Engineers-New York District (USAGE-NYD) requested the Battelle Marine Sciences Laboratory (MSL) to sample and to evaluate for dredging and disposal. Sediment samples were submitted for physical and chemical analyses, chemical analyses of dredging site water and elutriate, benthic and water-column acute toxicity tests, and bioaccumulation studies. Fifteen individual sediment core samplesmore » collected from the Bronx River project area were analyzed for grain size, moisture content, and total organic carbon (TOC). One composite sediment sample, representing the entire reach of the area proposed for dredging, was analyzed for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congeners, polynuclear aromatic hydrocarbons (PAH), and 1,4- dichlorobenzene. Dredging site water and elutriate water, which was prepared from the suspended-particulate phase (SPP) of the Bronx River sediment composite, were analyzed for metals, pesticides, and PCBS.« less

Bacterial production in the water column of small streams highly depends on terrestrial dissolved organic carbon

NASA Astrophysics Data System (ADS)

Graeber, Daniel; Poulsen, Jane R.; Rasmussen, Jes J.; Kronvang, Brian; Zak, Dominik; Kamjunke, Norbert

2016-04-01

In the recent years it has become clear that the largest part of the terrestrial dissolved organic carbon (DOC) pool is removed on the way from the land to the ocean. Yet it is still unclear, where in the freshwater systems terrestrial DOC is actually taken up, and for streams DOC uptake was assumed to happen mostly at the stream bottom (benthic zone). However, a recent monitoring study implies that water column but not benthic bacteria are strongly affected by the amount and composition of DOM entering streams from the terrestrial zone. We conducted an experiment to compare the reaction of the bacterial production and heterotrophic uptake in the water column and the benthic zone to a standardized source of terrestrial DOC (leaf leachate from Beech litter). In detail, we sampled gravel and water from eight streams with a gradient in stream size and land use. For each stream four different treatments were incubated at 16°C for three days and each stream: filtered stream water with gravel stones (representing benthic zone bacteria) or unfiltered stream water (representing water column bacteria), both either with (n = 5) or, without (n = 3) leaf leachate. We found that the bacterial uptake of leaf litter DOC was higher for the benthic zone likely due to the higher bacterial production compared to the water column. In contrast, the bacterial production per amount of leaf leachate DOC taken up was significantly higher for the bacteria in the water column than for those in the benthic zone. This clearly indicates a higher growth efficiency with the leaf leachate DOC for the bacteria in the water column than in the benthic zone. We found a high variability for the growth efficiency in the water column, which was best explained by a negative correlation of the DOC demand with stream width (R² = 0.86, linear correlation of log-transformed data). This was not the case for the benthic zone bacteria (R² = 0.02). This implies that water column bacteria in very small streams are more dependent on terrestrial DOC sources for their growth than those in larger streams. Based on this experiment and literature data we hypothesize that: I) The response of the bacterial production to terrestrial DOC in the water column is stronger than for the benthic zone and is decreasing with increasing stream size, likely due to the increase of autochthonous DOC production within the stream. II) Independent of stream size there is only a small reaction to terrestrial DOC for the bacterial production in the benthic zone, either due to internal DOC production or a stronger dependency on particulate organic carbon. We propose that this terrestrial DOC dependency concept is generally applicable, however, its potential underlying mechanisms and concept predictions need to be tested further for other stream and river ecosystems.

Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages

USGS Publications Warehouse

Quist, Michael C.; Schultz, Randall D.

2014-01-01

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002–2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence–absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

Effects of water removal on a Hawaiian stream ecosystem

USGS Publications Warehouse

Kinzie, R. A.; Chong, C.; Devrell, J.; Lindstrom, D.; Wolff, R.

2006-01-01

A 3-year study of Wainiha River on Kaua'i, Hawai'i, was carried out to determine the impact that water removal had on key stream ecosystem parameters and functions. The study area included a diversion dam for a hydroelectric plant that removes water at an elevation of 213 m and returns it to the stream about 6 km downstream at an elevation of 30 m. There were two high-elevation sites, one with undiverted flow and one with reduced flow, and two low-elevation sites, one with reduced flow and one with full flow restored. Monthly samples were taken of instream and riparian invertebrates and plants. When samples from similar elevations were compared, dewatered sites had lower concentrations of benthic photosynthetic pigments than full-flow sites, and benthic ash-free dry mass (AFDM) was higher at the two low-elevation sites regardless of flow. Benthic chlorophyll a (chl a) and AFDM were higher in summer months than in the winter. Benthic invertebrate abundance was highest at the full-flow, low-elevation site and benthic invertebrate biomass was highest at the full-flow, high-elevation site. Season had only marginal effects on abundance and biomass of benthic invertebrates. Diversity of benthic invertebrates was higher at the more-downstream sites. Abundance of drifting invertebrates was highest at the site above the diversion dam and generally higher in winter than in summer months. Biomass of drifting invertebrates was also highest at the above-dam site but there was little seasonal difference. Almost all parameters measured were lowest at the site just downstream of the diversion dam. The biotic parameters responded only weakly to flows that had occurred up to 1 month before the measurements were made. Flow, elevation, and season interact in complex ways that impact ecosystem parameters and functions, but water diversion can override all these environmental factors. ?? 2006 by University of Hawai'i Press All rights reserved.

A 22,000 year record of changing redox conditions from the Peruvian Oxygen Minimum Zone (OMZ): benthic foraminifera approach

NASA Astrophysics Data System (ADS)

Erdem, Z.; Schönfeld, J.; Glock, N.

2015-12-01

Benthic foraminifera have been used as proxies for the prevailing conditions at the sediment-water interface. Their distribution patterns are thought to facilitate reconstruction of past environmental conditions. Variations of bottom water oxygenation can be traced by the downcore distribution of benthic foraminifera and some of their morphological characters. Being one of the strongest and most pronounced OMZs in today's world oceans, the Peruvian OMZ is a key area to study such variations in relation with changing climate. Spatial changes or an extension of the OMZ through time and space are investigated using sediment cores from the lower OMZ boundary. We focus on time intervals Late Holocene, Early Holocene, Bølling Allerød, Heinrich-Stadial 1 and Last Glacial Maximum (LGM) to investigate changes in bottom-water oxygen and redox conditions. The recent distributions of benthic foraminiferal assemblages provide background data for an interpretation of the past conditions. Living benthic foraminiferal faunas from the Peruvian margin are structured with the prevailing bottom-water oxygen concentrations today (Mallon et al., 2012). Downcore distribution of benthic foraminiferal assemblages showed fluctuations in the abundance of the indicator species depicting variations and a decreasing trend in bottom water oxygen conditions since the LGM. In addition, changes in bottom-water oxygen and nitrate concentrations are reconstructed for the same time intervals by the pore density in tests of Planulina limbata and Bolivina spissa (Glock et al., 2011), respectively. The pore densities also indicate a trend of higher oxygen and nitrate concentrations in the LGM compared to the Holocene. Combination of both proxies provide information on past bottom-water conditions and changes of oxygen concentrations for the Peruvian margin. Glock et al., 2011: Environmental influences on the pore density of Bolivina spissa (Cushman), Journal of Foraminiferal Research, v. 41, no. 1, p. 22-32. Mallon et al., 2012: The response of benthic foraminifera to low-oxygen conditions of the Peruvian oxygen minimum zone, in ANOXIA, pp.305-322.

Benthic primary producers are key to sustain the Wadden Sea food web: stable carbon isotope analysis at landscape scale.

PubMed

Christianen, M J A; Middelburg, J J; Holthuijsen, S J; Jouta, J; Compton, T J; van der Heide, T; Piersma, T; Sinninghe Damsté, J S; van der Veer, H W; Schouten, S; Olff, H

2017-06-01

Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the landscape scale is often unclear, as many studies lack good taxonomic and spatial resolution across large areas. Here, using stable carbon isotopes, we report on the primary carbon sources for consumers and their spatial variability across one of the world's largest intertidal ecosystems (Dutch Wadden Sea; 1460 km 2 intertidal surface area), at an exceptionally high taxonomic (178 species) and spatial resolution (9,165 samples from 839 locations). The absence of overlap in δ 13 C values between consumers and terrestrial organic matter suggests that benthic and pelagic producers dominate carbon input into this food web. In combination with the consistent enrichment of benthic primary producers (δ 13 C -16.3‰) relative to pelagic primary producers (δ 13 C -18.8) across the landscape, this allowed the use of a two-food-source isotope-mixing model. This spatially resolved modelling revealed that benthic primary producers (microphytobenthos) are the most important energy source for the majority of consumers at higher trophic levels (worms, molluscs, crustaceans, fish, and birds), and thus to the whole food web. In addition, we found large spatial heterogeneity in the δ 13 C values of benthic primary producers (δ 13 C -19.2 to -11.5‰) and primary consumers (δ 13 C -25.5 to -9.9‰), emphasizing the need for spatially explicit sampling of benthic and pelagic primary producers in coastal ecosystems. Our findings have important implications for our understanding of the functioning of ecological networks and for the management of coastal ecosystems. © 2017 by the Ecological Society of America.

Effects of Management Legacies on Stream Fish and Aquatic Benthic Macroinvertebrate Assemblages

NASA Astrophysics Data System (ADS)

Quist, Michael C.; Schultz, Randall D.

2014-09-01

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

Understanding the effects of predictability, duration, and spatial pattern of drying on benthic invertebrate assemblages in two contrasting intermittent streams

PubMed Central

von Schiller, Daniel; Barberá, Gonzalo G.; Díaz, Angela M.; Arce, Maria Isabel; del Campo, Rubén; Tockner, Klement

2018-01-01

In the present study, we examined the effects of different drying conditions on the composition, structure and function of benthic invertebrate assemblages. We approached this objective by comparing invertebrate assemblages in perennial and intermittent sites along two intermittent Mediterranean streams with contrasting predictability, duration, and spatial patterns of drying: Fuirosos (high predictability, short duration, downstream drying pattern) and Rogativa (low predictability, long duration, patchy drying pattern). Specifically, we quantified the contribution of individual taxa to those differences, the degree of nestedness, and shifts in the composition, structure and function of benthic invertebrate assemblages along flow intermittence gradients. We observed greater effects of drying on the benthic invertebrate composition in Fuirosos than in Rogativa, resulting in a higher dissimilarity of assemblages between perennial and intermittent sites, as well as a lower degree of nestedness. Furthermore, a higher number of biotic metrics related to richness, abundance and biological traits were significantly different between perennial and intermittent sites in Fuirosos, despite a shorter dry period compared to Rogativa. At the same time, slightly different responses were detected during post-drying (autumn) than pre-drying (spring) conditions in this stream. In Rogativa, shifts in benthic invertebrate assemblages along increasing gradients of flow intermittence were found for three metrics (Ephemeroptera, Plecoptera and Trichoptera (EPT) and Odonata, Coleoptera and Heteroptera (OCH) abundances and aerial active dispersal. Furthermore, we demonstrated that combined gradients of dry period duration and distance to nearest perennial reach can generate complex, and different, responses of benthic invertebrate assemblages, depending on the flow intermittence metric. Our study advances the notion that special attention should be paid to the predictability, duration and spatial patterns of drying in intermittent streams in order to disentangle the effects of drying on benthic invertebrate assemblages, in particular in areas subject to high spatial heterogeneity and temporal variability in drying conditions. PMID:29590140

Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages.

PubMed

Quist, Michael C; Schultz, Randall D

2014-09-01

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

Fish stomach contents in benthic macroinvertebrate assemblage assessments.

PubMed

Tupinambás, T H; Pompeu, P S; Gandini, C V; Hughes, R M; Callisto, M

2015-01-01

The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle) in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil). We sampled sediments through use of a Petersen dredge (total of 216 grabs) and used gill nets to sample fish (total of 36 samples). We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus). Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity). This is especially true for studies that only sample fish assemblages to evaluate aquatic ecosystem impacts. Therefore, this approach can be useful to amplify assessments of human impacts, and to incorporate additional bioindicators.

Multiscale patterns in the diversity and organization of benthic intertidal fauna among French Atlantic estuaries

NASA Astrophysics Data System (ADS)

Blanchet, Hugues; Gouillieux, Benoît; Alizier, Sandrine; Amouroux, Jean-Michel; Bachelet, Guy; Barillé, Anne-Laure; Dauvin, Jean-Claude; de Montaudouin, Xavier; Derolez, Valérie; Desroy, Nicolas; Grall, Jacques; Grémare, Antoine; Hacquebart, Pascal; Jourde, Jérôme; Labrune, Céline; Lavesque, Nicolas; Meirland, Alain; Nebout, Thiebaut; Olivier, Frédéric; Pelaprat, Corine; Ruellet, Thierry; Sauriau, Pierre-Guy; Thorin, Sébastien

2014-07-01

Based on a parallel sampling conducted during autumn 2008, a comparative study of the intertidal benthic macrofauna among 10 estuarine systems located along the Channel and Atlantic coasts of France was performed in order to assess the level of fauna similarity among these sites and to identify possible environmental factors involved in the observed pattern at both large (among sites) and smaller (benthic assemblages) scales. More precisely this study focused on unraveling the observed pattern of intertidal benthic fauna composition and diversity observed at among-site scale by exploring both biotic and abiotic factors acting at the among- and within-site scales. Results showed a limited level of similarity at the among-site level in terms of intertidal benthic fauna composition and diversity. The observed pattern did not fit with existing transitional water classification methods based on fish or benthic assemblages developed in the frame of the European Water Framework Directive (WFD). More particularly, the coastal plain estuaries displayed higher among-site similarity compared to ria systems. These coastal plain estuaries were characterized by higher influence of river discharge, lower communication with the ocean and high suspended particulate matter levels. On the other hand, the ria-type systems were more dissimilar and different from the coastal plain estuaries. The level of similarity among estuaries was mainly linked to the relative extent of the intertidal "Scrobicularia plana-Cerastoderma edule" and "Tellina tenuis" or "Venus" communities as a possible consequence of salinity regime, suspended matter concentrations and fine particles supply with consequences on the trophic functioning, structure and organization of benthic fauna. Despite biogeographical patterns, the results also suggest that, in the context of the WFD, these estuaries should only be compared on the basis of the most common intertidal habitat occurring throughout all estuarine systems and that the EUNIS biotope classification might be used for this purpose. In addition, an original inverse relation between γ-diversity and area was shown; however, its relevance might be questioned.

BENTHIC MACROFAUNA-HABITAT RELATIONSHIPS IN WILLAPA BAY, WA

EPA Science Inventory

Benthic macrofauna-habitat relationships were determined estuary-wide in Willapa Bay, WA for four intertidal habitats ((1) eelgrass, Zostera marina, (2) Atlantic cordgrass, Spartina alterniflora, (3) ghost shrimp, Neotrypaea californiensis, (4) mud shrimp, Upogebia pugettensis) i...

EPA'S BENTHIC HABITAT DATA FOR YAQUINA ESTUARY

EPA Science Inventory

Scientists at EPA's National Health and Environmental Effects Research Laboratory, Western Ecology Division (WED) have been studying seafloor (benthic) habitats in Yaquina estuary for several years. Those studies were conducted as parts of several research projects, including: e...

Variation of telencephalon morphology of the threespine stickleback (Gasterosteus aculeatus) in relation to inferred ecology.

PubMed

Park, Peter J; Bell, M A

2010-06-01

We tested the hypothesis that increased telencephalon size has evolved in threespine stickleback fish (Gasterosteus aculeatus) from structurally complex habitats using field-caught samples from one sea-run (ancestral) and 18 ecologically diverse freshwater (descendant) populations. Freshwater habitats ranged from shallow, structurally complex lakes with benthic-foraging stickleback (benthics), to deeper, structurally simple lakes in which stickleback depend more heavily on plankton for prey (generalists). Contrary to our expectations, benthics had smaller telencephala than generalists, but the shape of the telencephalon of the sea-run and benthic populations were more convex laterally. Convex telencephalon shape may indicate enlargement of the dorsolateral region, which is homologous with the tetrapod hippocampus. Telencephalon morphology is also sexually dimorphic, with larger, less convex telencephala in males. Freshwater stickleback from structurally complex habitats have retained the ancestral telencephalon morphology, but populations that feed more in open habitats on plankton have evolved larger, laterally concave telencephala.

A mathematical model of algae growth in a pelagic-benthic coupled shallow aquatic ecosystem.

PubMed

Zhang, Jimin; Shi, Junping; Chang, Xiaoyuan

2018-04-01

A coupled system of ordinary differential equations and partial differential equations is proposed to describe the interaction of pelagic algae, benthic algae and one essential nutrient in an oligotrophic shallow aquatic ecosystem with ample supply of light. The existence and uniqueness of non-negative steady states are completely determined for all possible parameter range, and these results characterize sharp threshold conditions for the regime shift from extinction to coexistence of pelagic and benthic algae. The influence of environmental parameters on algal biomass density is also considered, which is an important indicator of algal blooms. Our studies suggest that the nutrient recycling from loss of algal biomass may be an important factor in the algal blooms process; and the presence of benthic algae may limit the pelagic algal biomass density as they consume common resources even if the sediment nutrient level is high.

Application of TSL Underwater Robots (AUV) for Investigation of Benthic Ecosystems and Quantification of Benthic Invertebrate Reserves

NASA Astrophysics Data System (ADS)

Golikov, S. Yu; Dulepov, V. I.; Maiorov, I. S.

2017-11-01

The issues on the application of autonomous underwater vehicles for assessing the abundance, biomass, distribution and reserves of invertebrates in the marine benthic ecosystems and on the environmental monitoring are discussed. An example of the application of methodology to assess some of the quantitative characteristics of macrobenthos is provided based upon using the information obtained from the TSL AUV in the Peter the Great Gulf (the Sea of Japan) in the Bay of Paris and the Eastern Bosphorus Strait within the area of the bridge leading to the Russian island. For the quantitative determination of the benthic invertebrate reserves, the values of biomass density of specific species are determined. Based on the data of direct measurements and weightings, the equations of weight dependencies on the size of animals are estimated according to the studied species that are well described by the power law dependence.

Vertical distribution of living ostracods in deep-sea sediments, North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Jöst, Anna B.; Yasuhara, Moriaki; Okahashi, Hisayo; Ostmann, Alexandra; Arbizu, Pedro Martínez; Brix, Saskia

2017-04-01

The depth distribution of living specimens of deep-sea benthic ostracods (small crustaceans with calcareous shells that are preserved as microfossils) in sediments is poorly understood, despite the importance of this aspect of basic ostracod biology for paleoecologic and paleoceanographic interpretations. Here, we investigated living benthic ostracod specimens from deep-sea multiple core samples, to reveal their depths distributions within sediment cores. The results showed shallow distribution and low population density of living deep-sea benthic ostracods (which are mostly composed of Podocopa). The living specimens are concentrated in the top 1 cm of the sediment, hence deep-sea benthic ostracods are either epifauna or shallow infauna. This observation is consistent with the information from shallow-water species. We also confirmed shallow infaunal (0.5-2 cm) and very shallow infaunal (0-1 cm) habitats of the deep-sea ostracod genera Krithe and Argilloecia, respectively.

Methods for collecting benthic invertebrate samples as part of the National Water-Quality Assessment Program

USGS Publications Warehouse

Cuffney, Thomas F.; Gurtz, Martin E.; Meador, Michael R.

1993-01-01

Benthic invertebrate communities are evaluated as part of the ecological survey component of the U.S. Geological Survey's National Water-Quality Assessment Program. These biological data are collected along with physical and chemical data to assess water-quality conditions and to develop an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. The objectives of benthic invertebrate community characterizations are to (1) develop for each site a list of tax a within the associated stream reach and (2) determine the structure of benthic invertebrate communities within selected habitats of that reach. A nationally consistent approach is used to achieve these objectives. This approach provides guidance on site, reach, and habitat selection and methods and equipment for qualitative multihabitat sampling and semi-quantitative single habitat sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data within and among study units.

Benthic and Plankton Foraminifers in Hydrothermally Active Zones of the Mid-Atlantic Ridge (MAR)

NASA Astrophysics Data System (ADS)

Khusid, T. A.; Os'kina, N. S.; Lukashina, N. P.; Gablina, I. F.; Libina, N. V.; Matul, A. G.

2018-01-01

Comparison of benthic foraminiferal assemblages from the core obtained within the Peterburgskoe ore field (Mid-Atlantic Ridge) and from the core taken five kilometers away from the ore field revealed evident differences in their composition, in the appearance of their shells, and also in the benthic-plankton species ratio. It was noted that the foraminiferal assemblage from the ore-bearing sediments of the Petersburg field was characterized by a higher relative content of benthic species and a large number of chemically altered and broken shells. The first occurrence of the species Osangularia umbonifera, which is able to exist in lowoxygen and CaCO3-undersaturated bottom waters at the boundary of biogenic sediments surrounding the ore field and in the ore-bearing sediments, was established. In the core section sampled beyond the ore field, the composition of foraminiferal assemblages differs insignificantly from typical oceanic ones.

Swept Away: Resuspension of Bacterial Mats Regulates Benthic-Pelagic Exchange of Sulfur

NASA Astrophysics Data System (ADS)

Grant, Jonathan; Bathmann, Ulrich V.

1987-06-01

Filaments and extracellular material from colorless sulfur bacteria (Beggiatoa spp.) form extensive white sulfur mats on surface sediments of coastal, oceanic, and even deep-sea environments. These chemoautotrophic bacteria oxidize soluble reduced sulfur compounds and deposit elemental sulfur, enriching the sulfur content of surface sediment fivefold over that of deeper sediments. Laboratory flume experiments with Beggiatoa mats from an intertidal sandflat (Nova Scotia) demonstrated that even slight erosion of sediment causes a flux of 160 millimoles of sulfur per square meter per hour, two orders of magnitude greater than the flux produced by sulfur transformations involving either sulfate reduction or sulfide oxidation by benthic bacteria. These experiments indicate that resuspension of sulfur bacterial mats by waves and currents is a rapid mechanism by which sediment sulfur is recycled to the water column. Benthic communities thus lose an important storage intermediate for reduced sulfur as well as a high-quality bacterial food source for benthic grazers.

Benthic plastic debris in marine and fresh water environments.

PubMed

Corcoran, Patricia L

2015-08-01

This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

Benthic foraminifera show some resilience to ocean acidification in the northern Gulf of California, Mexico.

PubMed

Pettit, L R; Hart, M B; Medina-Sánchez, A N; Smart, C W; Rodolfo-Metalpa, R; Hall-Spencer, J M; Prol-Ledesma, R M

2013-08-30

Extensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74-207m water depth. Living (rose Bengal stained) benthic foraminifera included Nonionella basispinata, Epistominella bradyana and Bulimina marginata. Studies on foraminifera at CO2 vents in the Mediterranean and off Papua New Guinea have shown dramatic long-term effects of acidified seawater. We found living calcareous benthic foraminifera in low pH conditions in the northern Gulf of California, although there was an impoverished species assemblage and evidence of post-mortem test dissolution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Expanded record of Quaternary oceanographic change: Amerasian Arctic Ocean

USGS Publications Warehouse

Ishman, S.E.; Polyak, L.V.; Poore, R.Z.

1996-01-01

Four sediment cores collected from the Northwind and Mendeleyev ridges, Arctic Ocean, from 1089 m to 1909 m water depth, provide an oceanographic record extending back into the Matuyama reversed polarity chron. Benthic foraminiferal analyses show four prominent assemblage zones: Bolivina arctica, Cassidulina teretis, Bulimina aculeata, and Oridorsalis tener from the upper Matuyama reversed polarity chronozone through the Brunhes normal polarity chronozone. These assemblage zones represent depth-dependent benthic foraminiferal biofacies changes associated with oceanographic events that occurred in the Amerasian basin at ??? 780 and 300 ka, and indicate oceanographic influence from the North Atlantic. Recognition of these benthic assemblage zones in Arctic cores from the Alpha Ridge indicates that the benthic foraminiferal zonations in intermediate to deep water (>1000 m) Arctic cores may be more useful than preexisting lithostratigraphic zonations and should provide important information pertaining to the Quaternary paleoceanographic evolution of the Arctic Ocean.

Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon

USGS Publications Warehouse

Kuwabara, James S.; Topping, Brent R.; Carter, James L.; Carlson, Rick A; Parchaso, Francis; Fend, Steven V.; Stauffer-Olsen, Natalie; Manning, Andrew J.; Land, Jennie M.

2016-09-30

Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invertebrates, and physical groundwater-surface water interactions) were not integrated into existing management models for UKL. Up until 2013, all of the benthic-flux studies generally had been limited spatially to a number of sites in the northern part of UKL and limited temporally to 2–3 samplings per year. All of the benthic invertebrate studies also had been limited to the northern part of the lake; however, intensive temporal (weekly) studies had previously been completed independent of benthic-flux studies. Therefore, knowledge of both the spatial and temporal variability in benthic flux and benthic invertebrate distributions for the entire lake was lacking. To address these limitations, we completed a lakewide spatial study during 2013 and a coordinated temporal study with weekly sampling of benthic flux and benthic invertebrates during 2014. Field design of the spatially focused study in 2013 involved 21 sites sampled three times as the summer cyanobacterial bloom developed (that is, May 23, June 13, and July 3, 2013). Results of the 27-week, temporally focused study of one site in 2014 were summarized and partitioned into three periods (referred to herein as pre-bloom, bloom and post-bloom periods), each period involving 9 weeks of profiler deployments, water column and benthic sampling. Partitioning of the pre-bloom, bloom, and post-bloom periods were based on water-column chlorophyll concentrations and involved the following date intervals, respectively: April 15 through June 10, June 17 through August 13, and August 20 through October 16, 2014. To examine dissolved-solute (0.2-micrometer [μm] filtered) benthic flux, sets of nonmetallic pore-water profilers (U.S. Patent 8,051,727 B1) were deployed. In 2013, the deployment of profilers at 21 UKL sites occurred at the beginning of the annual cyanobacterial bloom of Aphanizomenon flos–aquae (AFA), in the middle of the bloom period, and at the peak of the bloom. Coordinated benthic invertebrate collections also were made. Based on results from 2013, weekly deployments of profilers and collection of benthic invertebrate samples from late spring to early autumn were used to estimate temporal trends in solute flux and benthic invertebrate densities. Estimates of nutrient efflux by benthic invertebrates were determined in the spring and autumn from 2011 through 2013 and three times (spring, summer, and autumn) in 2015. This work extends UKL studies that began in 2006 to quantify the importance of benthic solute sources in the lake. In 2015, piezometers and thermistor sets were deployed to quantify potential groundwater exchange with the lake water column. Analysis of the 2013 soluble reactive phosphorus (SRP) benthic flux indicated no effect of location (lake region), habitat, or sampling period, and the average lakewide flux values were consistent with earlier studies that had been confined to the northern region of UKL and adjacent wetlands. The 2014 study therefore focused on estimating temporal trends at a site within Ball Bay. During both 2013 and 2014 field studies, fluxes of macronutrients (soluble reactive phosphorus (SRP) and ammonia) and micronutrients (iron [Fe] and manganese [Mn]) were consistently positive and increased prior to the initial AFA bloom, varied or lagged with water-column chlorophyll during the summer bloom period, then decreased after the cyanobacterial blooms, only to rebound toward pre-bloom conditions in the final weeks of sampling. These four solutes exhibited benthic loads greater than maximum riverine loads estimated during the spring and early summers of 2013 and 2014. However, consistently detectable concentrations for all four solutes provide no evidence that they consistently serve as the limiting nutrient for primary production in the lake. In contrast to the four solutes (SRP, ammonia, Fe, and Mn), benthic fluxes of dissolved arsenic (As) were both negative and positive (that is, the lakebed currently serves as both a source and a sink for dissolved As, depending on season). In a further contrast with SRP, ammonia, dissolved Fe, and Mn, dissolved-As riverine loads to UKL were of similar magnitude to benthic loads. A negative relationship between dissolved-As flux and water-column As over the 2014 temporal study provides a potential advantage for the management of water-quality in contrast to solutes, like SRP or ammonia, with consistently positive flux. The mean total benthic invertebrate density during 2013 was 12,610 individuals per square meter (n=63). Although benthic invertebrate density did not change over the study period, it was higher in littoral habitats than open-lake or trench habitats and higher in the northern region compared to the central or southern regions of UKL. Mean total benthic invertebrate density during 2014 was 19,726 individuals m−2 (n=27). Density during the pre-bloom and bloom periods of April 15 to August 13, 2014 (the first two thirds of the 2014 sampling period), were similar to 2013. However, benthic invertebrate density more than doubled during the latter one-third of the study, that is, the post-bloom period between August 20 to October 16, 2014. Oligochaeta, Chironomidae and Hirudinea represented well over 90 percent of the benthic fauna; Oligochaeta were twice as abundant as Chironomidae or Hirudinea, the latter two of which were similar in density. Benthic invertebrates may enhance dissolved-nutrient (or toxicant) transport across the sediment-water interface by (1) modifying diffusion-layer thicknesses and permeability through bioturbation, (2) enhancing advective flow across the interface through bioirrigation, and (3) excreting or expelling dissolved or particulate solutes directly into the overlying water column (Boudreau and Jorgensen, 2001). We evaluated SRP efflux via excretion for approximately 15 different major taxa in UKL. Once these measures were scaled, it was evident that benthic invertebrates potentially contribute approximately 1.5 times the amount of SRP to the water column of Upper Klamath Lake as diffusive SRP flux alone, measured in profiler deployments. Sets of piezometers and temperature loggers were deployed in UKL to obtain estimates of vertical advective solute flux. The pressure transducer installations, within the piezometers, did not perform as designed, rendering the head gradient data unreliable. However, in terms of future research, this field work did demonstrate the feasibility of collecting vertical gradient data with piezometer deployments. Advective flux estimates herein are based solely on heat-flow modeling based on temperature data from four lake sites, without use of transducer data. Given the magnitudes (both positive or negative) of the heat-transfer fluxes for SRP, relative to diffusive-flux and macroinvertebrate efflux measurements (all positive but spanning the same orders of magnitude), further examination of solute advective flux is recommended as a potential transport process to integrate into existing water-quality (for example, Total Maximum Daily Load [TMDL]) models. As a complement to the biogeochemical focus of this study, initial analyses of suspended-particle (floc) characteristics and settling velocities from the water column were derived near the surface and lakebed at two UKL sites. To better understand changing particle characteristics during the AFA-bloom period, suspended particles were examined in 2015 using a LabSFLOC (LF), which is a Laboratory Spectral Flocculation Characteristics version of an In-Situ Settling Velocity instrument (INSSEV-LF). Particle characteristics and settling velocities were analyzed from the water column near the surface (sample dp_10) and lakebed (sample dp_90) at two lake sites (open-lake site ML and littoral site LS01). The term “floc” refers herein to suspended particles that may aggregate or disaggregate to change in size, composition, and settling velocity. During pre-bloom (May) conditions, where maximum suspended particulate matter concentration (SPMC) was 140 milligrams per liter (mg L−1) was now observed at site LS01 in close proximity to the bed, where Dmean peaked at 305 μm, and the corresponding Wsmean was 3.9 millimeters per second (mm s−1). The high near-bed SPMC (828 mg L−1) experienced during post-bloom October 2015 at LS01 formed a benthic nepheloid layer (BNL) above the lake’s bed. Numerous low density, fast settling macrofloc-sized organic aggregates (D >160 μm) were observed (some up to 1 mm in size) near bed at LS01 both during the bloom and post-bloom conditions; many of these flocs displayed fibrous organic structures. In terms of mass settling fluxes, the post-bloom BNL produced a total MSF of 4,139 milligrams per square meter per second (mg m−2 s−1) (92.1 percent of MSF credited to the macrofloc-sized organic aggregates/cyanobacterial colonies); that was nearly three times the corresponding near-bed settling flux observed during the July 2015 bloom and 360 times greater than the pre-bloom conditions from May 2015 (98.8 percent and 14 percent of MSF credited to the macrofloc-sized fractions for those respective months). Such changes in the near-bed settling flux demonstrate the highly significant seasonal effects that the AFA bloom has on the floc depositional fluxes in UKL and highlights the importance of seasonal monitoring of these conditions in order to correctly parameterize the wide range in depositional characteristics and floc properties measured throughout UKL. Collectively, floc populations observed within UKL demonstrated a wide range in settling velocity (Ws) for a given particle size, D. Similarly, a given settling velocity was not associated with a specific particle size. This variability in particle characteristics and properties indicates the influence of varying floc effective density and its effect on mass and mass settling fluxes (MSF). The use of instruments, such as the INSSEV-LF, enables measuring the variability of settling velocity and its relation to particle density and size.

Exploring late Miocene climate stability: constraining background variability using high-resolution benthic δ18O and δ13C records from Site U1338

NASA Astrophysics Data System (ADS)

Drury, A.; John, C. M.; Lee, G.; Shevenell, A.

2012-12-01

The late Miocene (11.61 - 5.33 Ma) was one of the more stable climatic periods of the Cenozoic. Superimposed on this stable background climate, a number of threshold events occurred, including the late Miocene Carbon Isotope Shift (CIS, 7.6-6.6 Ma) and the Messinian Salinity Crisis (MSC, 5.96-5.33 Ma). The goal of our study is to constrain the background climate cyclicity during the late Miocene. A better knowledge of the background cyclicity in the Earth's climate system is required to advance understanding of, and to successfully model, climate variability. Improving understanding of how changes in background climate variability affect important parameters and fluxes, such as ice volume and the carbon pump, is crucial for explaining the occurrence of threshold events such as the CIS and MSC during an otherwise climatically stable period. The study site is located in the Eastern Equatorial Pacific (IODP Site U1338, Expedition 321). U1338 was chosen, as the equatorial Pacific is an important component of the global climate system, representing half of the total tropical ocean and a quarter of the global ocean. We present δ18O and δ13C records from 3.5 to 8.5 Ma using the benthic foraminiferal species Cibicidoides mundulus, with a resolution of 3-4 kyr, which resolves all Milankovitch scale cycles. We present a revised shipboard age model, generated from new biostratigraphic age constraints based on planktic foraminiferal datums. Benthic δ18O records at IODP Site U1338 reflect the stable nature of the late Miocene climate accurately, with long-term trends showing low-amplitude (0.2‰) variations. Superimposed on this are higher-amplitude short-term fluctuations (0.3-0.4‰). Deep-sea benthic foraminferal δ18O records both temperature and the δ18O composition of global deep seawater (δ18Odsw). δ18Odsw largely reflects glacio-eustatic change. Our benthic δ18O implies that long-term trends in ice volume were minimal during the late Miocene. However, the short-term variations imply that some significant sea level fluctuations occurred. The benthic δ13C long-term trend varies by ~0.75‰. The late Miocene CIS is visible as a ~1.25‰ excursion. Short-term fluctuations in δ13C record are slightly lower amplitude (~0.50‰). Preliminary spectral analysis highlights the strength of the eccentricity forcing (400 and 100-kyr cycles) in both the δ18O and δ13C records. The 41-kyr obliquity cycles are also visible in the δ18O records. The benthic δ13C records are combined with preliminary low-resolution δ13C records measured on the planktic foraminiferal species Globigerinoides sacculifer from the same samples. Co-varying benthic-planktic δ13C is driven by changes in the ocean reservoir δ13C, whereas con/diverging benthic-planktic δ13C is related to changes in surface productivity. This initial comparison may shed some light on the forcing of the CIS, and the implications for late Miocene climate. Future work will combine benthic δ18O with independent temperature proxies, such as Mg/Ca and clumped isotopes, to isolate the δ18Odsw signal and make more robust inferences about the background cryosphere dynamics during this time. We will also increase the resolution of the planktic foraminiferal records to enable comparison of the dominant forcing in the benthic and planktic records.

Mass extinctions in the deep sea

NASA Technical Reports Server (NTRS)

Thomas, E.

1988-01-01

The character of mass extinctions can be assessed by studying extinction patterns of organisms, the fabric of the extinction, and assessing the environmental niche and mode of life of survivors. Deep-sea benthic foraminifera have been listed as little affected by the Cretaceous-Tertiary (K-T) mass extinction, but very few quantitative data are available. New data on deep-sea Late Maestrichtian-Eocene benthic foraminifera from Maud Rise (Antractica) indicate that about 10 percent of the species living at depths of 2000 to 2500 m had last appearances within 1 my of the Cretaceous-Tertiary (K-T) boundary, versus about 25 percent of species at 1000 to 1500 m. Many survivors from the Cretaceous became extinct in a period of global deep-sea benthic foraminiferal extinction at the end of the Paleocene, a time otherwise marked by very few extinctions. Preliminary conclusions suggest that the deep oceanic environment is essentially decoupled from the shallow marine and terrestrial environment, and that even major disturbances of one of these will not greatly affect the other. This gives deep-sea benthic faunas a good opportunity to recolonize shallow environments from greater depths and vice versa after massive extinctions. The decoupling means that data on deep-sea benthic boundary was caused by the environmental effects of asteriod impact or excessive volcanism. The benthic foraminiferal data strongly suggest, however, that the environmental results were strongest at the Earth's surface, and that there was no major disturbance of the deep ocean; this pattern might result both from excessive volcanism and from an impact on land.

Benthic invertebrates and periphyton in the Elwha river basin: Current conditions and predicted response to dam removal

USGS Publications Warehouse

Morley, S.A.; Duda, J.J.; Coe, H.J.; Kloehn, K.K.; McHenry, M.L.

2008-01-01

The impending removal of two dams on the Elwha River in Washington State offers a unique opportunity to study ecosystem restoration at a watershed scale. We examine how periphyton and benthic invertebrate assemblages vary across regulated and unregulated sections of the Elwha River and across different habitat types, and establish baseline data for tracking future changes following dam removal. We collected multiple years of data on physical habitat, water chemistry, periphyton, and benthic invertebrates from 52 sites on the Elwha River and a reference section on the Quinault River, a neighboring basin. We found that substrate in regulated river sections was coarser and less heterogeneous in size than in unregulated sections, and summer water temperature and specific conductivity higher. Periphyton biomass was also consistently higher in regulated than unregulated sections. Benthic invertebrate assemblage structure at sites above both dams was distinct from sites between and below the dams, due in large part to dominance of mayfly taxa compared to higher relative abundance of midges and non-insect taxa at downstream sites. Following dam removal, we anticipate that both periphyton and benthic invertebrate abundance and diversity will temporarily decrease between and below dams as a result of sediment released from behind the reservoirs. Over the long-term, increased floodplain heterogeneity and recolonization by anadromous fish will alter benthic invertebrate and periphyton assemblages via increases in niche diversity and inputs of marine-derived nutrients. The extended timeline predicted for Elwha River recovery and the complexities of forecasting ecological response highlights the need for more long-term assessments of dam removal and river restoration practices.

Baseline ecological risk assessment of the Calcasieu Estuary, Louisiana: 3. An evaluation of the risks to benthic invertebrates associated with exposure to contaminated sediments

USGS Publications Warehouse

MacDonald, Donald D.; Ingersoll, Christopher G.; Kemble, Nile E.; Smorong, Dawn E.; Sinclair, Jesse A.; Lindskoog, Rebekka; Gaston, Gary; Sanger, Denise; Carr, R. Scott; Biedenbach, James; Gouguet, Ron; Kern, John; Shortelle, Ann; Field, L. Jay; Meyer, John

2011-01-01

The sediments in the Calcasieu Estuary are contaminated with a wide variety of chemicals of potential concern (COPCs), including heavy metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalates, chlorinated benzenes, and polychlorinated dibenzo-p-dioxins and dibenzofurans. The sources of these COPCs include both point and non-point source discharges. As part of a baseline ecological risk assessment, the risks to benthic invertebrates posed by exposure to sediment-associated COPCs were assessed using five lines of evidence, including whole-sediment chemistry, pore-water chemistry, whole-sediment toxicity, pore-water toxicity, and benthic invertebrate community structure. The results of this assessment indicated that exposure to whole sediments and/or pore water from the Calcasieu Estuary generally posed low risks to benthic invertebrate communities (i.e., risks were classified as low for 68% of the sampling locations investigated). However, incremental risks to benthic invertebrates (i.e., compared with those associated with exposure to conditions in reference areas) were indicated for 32% of the sampling locations within the estuary. Of the three areas of concern (AOCs) investigated, the risks to benthic invertebrates were highest in the Bayou d'Inde AOC; risks were generally lower in the Upper Calcasieu River AOC and Middle Calcasieu River AOC. The areas showing the highest risks to sediment-dwelling organisms were generally located in the vicinity of point source discharges of COPCs. These results provided risk managers with the information required to make decisions regarding the need for remedial actions at the site.

Prospective Environmental Risk Assessment for Sediment-Bound Organic Chemicals: A Proposal for Tiered Effect Assessment.

PubMed

Diepens, Noël J; Koelmans, Albert A; Baveco, Hans; van den Brink, Paul J; van den Heuvel-Greve, Martine J; Brock, Theo C M

A broadly accepted framework for prospective environmental risk assessment (ERA) of sediment-bound organic chemicals is currently lacking. Such a framework requires clear protection goals, evidence-based concepts that link exposure to effects and a transparent tiered-effect assessment. In this paper, we provide a tiered prospective sediment ERA procedure for organic chemicals in sediment, with a focus on the applicable European regulations and the underlying data requirements. Using the ecosystem services concept, we derived specific protection goals for ecosystem service providing units: microorganisms, benthic algae, sediment-rooted macrophytes, benthic invertebrates and benthic vertebrates. Triggers for sediment toxicity testing are discussed.We recommend a tiered approach (Tier 0 through Tier 3). Tier-0 is a cost-effective screening based on chronic water-exposure toxicity data for pelagic species and equilibrium partitioning. Tier-1 is based on spiked sediment laboratory toxicity tests with standard benthic test species and standardised test methods. If comparable chronic toxicity data for both standard and additional benthic test species are available, the Species Sensitivity Distribution (SSD) approach is a more viable Tier-2 option than the geometric mean approach. This paper includes criteria for accepting results of sediment-spiked single species toxicity tests in prospective ERA, and for the application of the SSD approach. We propose micro/mesocosm experiments with spiked sediment, to study colonisation success by benthic organisms, as a Tier-3 option. Ecological effect models can be used to supplement the experimental tiers. A strategy for unifying information from various tiers by experimental work and exposure-and effect modelling is provided.

Benthic community structure on coral reefs exposed to intensive recreational snorkeling.

PubMed

Renfro, Bobbie; Chadwick, Nanette E

2017-01-01

Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1-3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1) in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling.

Resource utilisation by deep-sea megabenthos in the Canadian High Arctic (Baffin Bay and Parry Channel)

NASA Astrophysics Data System (ADS)

Bourgeois, Solveig; Witte, Ursula; Harrison, Ailish M.; Makela, Anni; Kazanidis, Georgios; Archambault, Philippe

2016-04-01

Ongoing climate change in the Arctic is causing drastic alteration of the Arctic marine ecosystem functioning, such as shifts in patterns of primary production, and modifying the present tight pelagic-benthic coupling. Subsequently benthic communities, which rely upon organic matter produced in the top layers of the Ocean, will also be affected by these changes. The benthic megafaunal communities play a significant role in ecological processes and ecosystem functioning (i.e. organic matter recycling, bioturbation, food source for the higher trophic levels…). Yet, information is scarce regarding the main food sources for dominant benthic organisms, and therefore the impact of the ongoing changes is difficult to assess. The goal of this study is to investigate the preferential feeding of different carbon sources by megabenthic organisms in the Canadian High Arctic and to identify environmental drivers which explain the observed trends. In summer 2013, benthic megafauna was collected at 9 stations spread along latitudinal (58 to 81°N) and longitudinal (62 to 114°W) transects in the Baffin Bay and Parry Channel, respectively. Carbon and nitrogen bulk stable isotope analyses (δ13C and δ15N) were performed on several species divided into groups according to their feeding type. This study highlights distinct trends in δ13C values of benthic organisms suggesting the importance of both phytoplankton and ice algae as carbon sources for megafauna in the Canadian High Arctic. The importance of physical and biological parameters as drivers of food web structure will be furthermore discussed.

Impacts of exotic mangrove forests and mangrove deforestation on carbon remineralization and ecosystem functioning in marine sediments

USGS Publications Warehouse

Sweetman, A.K.; Middelburg, J.J.; Berle, A.M.; Bernardino, A.F.; Schander, C.; Demopoulos, A.W.J.; Smith, C.R.

2010-01-01

To evaluate how mangrove invasion and removal can modify benthic carbon cycling processes and ecosystem functioning, we used stable-isotopically labelled algae as a deliberate tracer to quantify benthic respiration and C-flow through macrofauna and bacteria in sediments collected from (1) an invasive mangrove forest, (2) deforested mangrove sites 2 and 6 years after removal of above-sediment mangrove biomass, and (3) two mangrove-free, control sites in the Hawaiian coastal zone. Sediment oxygen consumption (SOC) rates were significantly greater in the mangrove and mangrove removal site experiments than in controls and were significantly correlated with total benthic (macrofauna and bacteria) biomass and sedimentary mangrove biomass (SMB). Bacteria dominated short-term C-processing of added microalgal-C and benthic biomass in sediments from the invasive mangrove forest habitat. In contrast, macrofauna were the most important agents in the short-term processing of microalgal-C in sediments from the mangrove removal and control sites. Mean faunal abundance and short term C-uptake rates in sediments from both removal sites were significantly higher than in control cores, which collectively suggest that community structure and short-term C-cycling dynamics in habitats where mangroves have been cleared can remain fundamentally different from un-invaded mudflat sediments for at least 6-yrs following above-sediment mangrove removal. In summary, invasion by mangroves can lead to large shifts in benthic ecosystem function, with sediment metabolism, benthic community structure and short-term C-remineralization dynamics being affected for years following invader removal. ?? 2010 Author(s).

Cross-habitat effects shape the ecosystem consequences of co-invasion by a pelagic and a benthic consumer.

PubMed

Fryxell, David C; Diluzio, Amber R; Friedman, Maya A; Menge, Nicklaus A; Palkovacs, Eric P

2016-10-01

Invasive species can have major impacts on ecosystems, yet little work has addressed the combined effects of multiple invaders that exploit different habitats. Two common invaders in aquatic systems are pelagic fishes and crayfishes. Pelagic-oriented fish effects are typically strong on the pelagic food web, whereas crayfish effects are strong on the benthic food web. Thus, co-invasion may generate strong ecological responses in both habitats. We tested the effects of co-invasion on experimental pond ecosystems using two widespread invasive species, one pelagic (western mosquitofish) and one benthic (red swamp crayfish). As expected, mosquitofish had strong effects on the pelagic food web, reducing the abundance of Daphnia and causing a strong trophic cascade (increase in phytoplankton). Crayfish had strong effects on the benthic food web, reducing the abundance of benthic filamentous algae. Yet, we also found evidence for important cross-habitat effects. Mosquitofish treatments reduced the biomass of benthic filamentous algae, and crayfish treatments increased Daphnia and phytoplankton abundance. Combined effects of mosquitofish and crayfish were primarily positively or negatively additive, and completely offsetting for some responses, including gross primary production (GPP). Though co-invasion did not affect GPP, it strongly shifted primary production from the benthos into the water column. Effects on snail abundance revealed an interaction; snail abundance decreased only in the presence of both invaders. These results suggest that cross-habitat effects of co-invaders may lead to a variety of ecological outcomes; some of which may be unpredictable based on an understanding of each invader alone.

Benthic community structure on coral reefs exposed to intensive recreational snorkeling

PubMed Central

Renfro, Bobbie

2017-01-01

Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1–3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1) in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling. PMID:28873449

The offshore benthic fish community

USGS Publications Warehouse

Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

2014-01-01

The offshore benthic fish community will be composed of self-sustaining native fishes characterized by lake trout as the top predator, a population expansion of lake whitefish from northeastern waters to other areas of the lake, and rehabilitated native prey fishes.

Relationship Between Nutrient Enrichment and Benthic Function: Local Effects and Spatial Patterns

EPA Science Inventory

Eutrophication-induced changes to benthic structure and function are problems of enormous ecological and economic significance. Understanding the relationships between nutrient enrichment and effects, modifying factors such as localized transport time, and symptoms of eutrophica...

WASP7 BENTHIC ALGAE - MODEL THEORY AND USER'S GUIDE

EPA Science Inventory

The standard WASP7 eutrophication module includes nitrogen and phosphorus cycling, dissolved oxygen-organic matter interactions, and phytoplankton kinetics. In many shallow streams and rivers, however, the attached algae (benthic algae, or periphyton, attached to submerged substr...

SAMPLING LARGE RIVERS FOR ALGAE, BENTHIC MACROINVERTEBRATES AND FISH

EPA Science Inventory

Multiple projects are currently underway to increase our understanding of the effects of different sampling methods and designs used for the biological assessment and monitoring of large (boatable) rivers. Studies include methods used to assess fish, benthic macroinvertebrates, ...

Spatial Variation in the Invertebrate Macrobenthos of Three Large Missouri River Reservoirs

EPA Science Inventory

Benthic macroinvertebrates assemblages are useful indicators of ecological condition for aquatic systems. This study was conducted to characterize benthic communities of three large reservoirs on the Missouri River. The information collected on abundance, distribution and varia...

Elders Point East Marsh Island Restoration Monitoring Data Analysis

DTIC Science & Technology

2017-09-21

Figure 13. Average biomass comparison between fertilizer treatment and non- fertilizer treatment at Elders East...25 ERDC/EL CR-17-1 vi Table 5. Count of benthic organisms ...31 Table 6. Benthic Community Indices: True Taxa Richness, Total Organism Count

LARGE RIVER ASSESSMENT METHODS FOR BENTHIC MACROINVERTEBRATES AND FISH

EPA Science Inventory

Multiple projects are currently underway to increase our understanding of the varying results of different sampling methods and designs used for the biological assessment and monitoring of large (boatable) rivers. Studies include methods used to assess fish, benthic macroinverte...

ENVIRONMENTAL INFLUENCES ON BENTHIC COMMUNITY STRUCTURE IN A GREAT LAKES EMBAYMENT

EPA Science Inventory

An Intensified Environmental Monitoring and Assessment Program (EMAP) sampling grid in the St. Louis River estuary of western Lake Superior was used toassess the relationship between surficial sediment characteristics and benthic community structure. Ninety sites within two habit...

Benthic Species Richness of U.S. Pacific Estuaries

EPA Science Inventory

Understanding the spatial distribution of biodiversity is of paramount importance due to the potential consequences of its loss on human welfare. We demonstrate that biodiversity of soft-bottomed estuarine benthic organisms can be predicted with relatively high accuracy at multi...

Comparisons of Sediment Test Volumes for Freshwater Solid Phase Sediment Toxicity Tests

EPA Science Inventory

Laboratory tests with benthic macroinvertebrates are commonly used to assess the potential toxicity of contaminated sediments, and detailed standard test procedures have been developed for various species. For freshwater, two benthic organisms, Hyalella azteca and Chironomus dil...

Biogeography of Nearshore Subtidal Invertebrates in the Gulf of Maine

EPA Science Inventory

The biogeography of nearshore benthic invertebrates in the Gulf of Maine was studied to compare recent data with historical biogeographic studies, define physical-chemical factors affecting species distributions, and provide information needed to calibrate benthic indices of envi...

BENTHIC MACROFAUNA AND HABITAT RELATIONSHIPS IN TILLAMOOK BAY

EPA Science Inventory

Tillamook Bay is subject to natural and man-made stressors, such as increased nutrients and sediments, which can alter its habitats and, thereby, impact its productivity and ecological resources. The benthic macrofauna are small, sediment-dwelling invertebrates which have strong...

The effect of temperature on size and development in three species of benthic copepod.

PubMed

Abdullahi, B A; Laybourn-Parry, Johanna

1985-09-01

The effect of temperature on the size and development times of three benthic cyclopoid copepods, Acanthocyclops viridis, A. vernalis and Macrocyclops albidus were investigated within the normal environmental temperature range (5°C-20°C). Adult weight decreased as temperature increased. All three species complete their development at 5°C and development times at all temperatures are presented as curvilinear logarithmic temperature functions. The duration of development decreases as temperature rises. The results are compared with those reported else-where for benthic and planktonic species and the ecological implications are discussed.

Fish, benthic macroinvertebrate, and stream habitat data from the Houston-Galveston Area Council service area, Texas, 1997-98

USGS Publications Warehouse

Moring, J. Bruce; Rosendale, John C.; Ansley, Stephen P.; Brown, Dexter W.

1998-01-01

The U.S. Geological Survey collected fish, benthic macroinvertebrate, and stream habitat data at sampling sites in the Houston-Galveston Area Council service area, a 15-county area with a population of about 4.3 million people. The data were collected for a 1997?98 study in cooperation with the Houston-Galveston Area Council to provide data for the Texas Clean Rivers Program for watersheds near Houston, Texas. Fish community and stream habitat data were collected at all 56 sites selected, and benthic macroinvertebrate data were collected at 39 of the sites.

Influence of item distribution pattern and abundance on efficiency of benthic core sampling

USGS Publications Warehouse

Behney, Adam C.; O'Shaughnessy, Ryan; Eichholz, Michael W.; Stafford, Joshua D.

2014-01-01

ore sampling is a commonly used method to estimate benthic item density, but little information exists about factors influencing the accuracy and time-efficiency of this method. We simulated core sampling in a Geographic Information System framework by generating points (benthic items) and polygons (core samplers) to assess how sample size (number of core samples), core sampler size (cm2), distribution of benthic items, and item density affected the bias and precision of estimates of density, the detection probability of items, and the time-costs. When items were distributed randomly versus clumped, bias decreased and precision increased with increasing sample size and increased slightly with increasing core sampler size. Bias and precision were only affected by benthic item density at very low values (500–1,000 items/m2). Detection probability (the probability of capturing ≥ 1 item in a core sample if it is available for sampling) was substantially greater when items were distributed randomly as opposed to clumped. Taking more small diameter core samples was always more time-efficient than taking fewer large diameter samples. We are unable to present a single, optimal sample size, but provide information for researchers and managers to derive optimal sample sizes dependent on their research goals and environmental conditions.

Tracing the incorporation of carbon into benthic foraminiferal calcite following the Deepwater Horizon event.

PubMed

Schwing, Patrick T; Chanton, Jeffrey P; Romero, Isabel C; Hollander, David J; Goddard, Ethan A; Brooks, Gregg R; Larson, Rebekka A

2018-06-01

Following the Deepwater Horizon (DWH) event in 2010, hydrocarbons were deposited on the continental slope in the northeastern Gulf of Mexico through marine oil snow sedimentation and flocculent accumulation (MOSSFA). The objective of this study was to test the hypothesis that benthic foraminiferal δ 13 C would record this depositional event. From December 2010 to August 2014, a time-series of sediment cores was collected at two impacted sites and one control site in the northeastern Gulf of Mexico. Short-lived radioisotopes ( 210 Pb and 234 Th) were employed to establish the pre-DWH, DWH, and post-DWH intervals. Benthic foraminifera (Cibicidoides spp. and Uvigerina spp.) were isolated from these intervals for δ 13 C measurement. A modest (0.2-0.4‰), but persistent δ 13 C depletion in the DWH intervals of impacted sites was observed over a two-year period. This difference was significantly beyond the pre-DWH (background) variability and demonstrated that benthic foraminiferal calcite recorded the depositional event. The longevity of the depletion in the δ 13 C record suggested that benthic foraminifera may have recorded the change in organic matter caused by MOSSFA from 2010 to 2012. These findings have implications for assessing the subsurface spatial distribution of the DWH MOSSFA event. Copyright © 2018 Elsevier Ltd. All rights reserved.

Admiralty Bay Benthos Diversity—A census of a complex polar ecosystem

NASA Astrophysics Data System (ADS)

Siciński, Jacek; Jażdżewski, Krzysztof; Broyer, Claude De; Presler, Piotr; Ligowski, Ryszard; Nonato, Edmundo F.; Corbisier, Thais N.; Petti, Monica A. V.; Brito, Tania A. S.; Lavrado, Helena P.; BŁażewicz-Paszkowycz, Magdalena; Pabis, Krzysztof; Jażdżewska, Anna; Campos, Lucia S.

2011-03-01

A thorough census of Admiralty Bay benthic biodiversity was completed through the synthesis of data, acquired from more than 30 years of observations. Most of the available records arise from successive Polish and Brazilian Antarctic expeditions organized since 1977 and 1982, respectively, but also include new data from joint collecting efforts during the International Polar Year (2007-2009). Geological and hydrological characteristics of Admiralty Bay and a comprehensive species checklist with detailed data on the distribution and nature of the benthic communities are provided. Approximately 1300 species of benthic organisms (excluding bacteria, fungi and parasites) were recorded from the bay's entire depth range (0-500 m). Generalized classifications and the descriptions of soft-bottom and hard-bottom invertebrate communities are presented. A time-series analysis showed seasonal and interannual changes in the shallow benthic communities, likely to be related to ice formation and ice melt within the bay. As one of the best studied regions in the maritime Antarctic Admiralty Bay represents a legacy site, where continued, systematically integrated data sampling can evaluate the effects of climate change on marine life. Both high species richness and high assemblage diversity of the Admiralty Bay shelf benthic community have been documented against the background of habitat heterogeneity.

Neogene biostratigraphy and paleoenvironments of Enewetak Atoll, equatorial Pacific Ocean

USGS Publications Warehouse

Cronin, T. M.; Bybell, L.M.; Brouwers, E.M.; Gibson, T.G.; Margerum, R.; Poore, R.Z.

1991-01-01

Micropaleontologic analyses of Neogene sediments from Enewetak Atoll, Marshall Islands, provide data on the age of lagoonal deposits, stratigraphic disconformities and the paleoenvironmental and subsidence history of the atoll. Benthic foraminifers, planktic foraminifers, calcareous nannofossils and ostracodes were studied from six boreholes, the deepest penetrating 1605 feet below the lagoon floor into upper Oligocene strata. The Oligocene-Miocene boundary occurs at about 1200 ft below the lagoon floor. The early and middle Miocene is characterized by brief periods of deposition and numerous hiatuses. Ostracodes and benthic foraminifers indicate a shallow-marine reefal environment with occasional brackish water conditions. Upper Miocene and lower Pliocene deposits placed in calcareous nannofossil Zones NN9-15 and in planktic foraminifer Zones N16-19 contain species-rich benthic microfaunas which indicate alternating reefal and brackish water mangrove environments. The upper Pliocene contains at least two major depositional hiatuses that coincide with a major faunal turnover in benthic foraminiferal and ostracode assemblages. The Quaternary is characterized by benthic microfaunas similar to those of modern atoll lagoons and is punctuated by at least 11 disconformities which signify periods of low sea level. Atoll subsidence rates during the last 10 Ma averaged 30 to 40 m/m.y. ?? 1991 Elsevier Science Publishers B.V. All rights reserved.

Anchor ice and benthic disturbance in shallow Antarctic waters: interspecific variation in initiation and propagation of ice crystals.

PubMed

Denny, Mark; Dorgan, Kelly M; Evangelista, Dennis; Hettinger, Annaliese; Leichter, James; Ruder, Warren C; Tuval, Idan

2011-10-01

Sea ice typically forms at the ocean's surface, but given a source of supercooled water, an unusual form of ice--anchor ice--can grow on objects in the water column or at the seafloor. For several decades, ecologists have considered anchor ice to be an important agent of disturbance in the shallow-water benthic communities of McMurdo Sound, Antarctica, and potentially elsewhere in polar seas. Divers have documented anchor ice in the McMurdo communities, and its presence coincides with reduced abundance of the sponge Homaxinella balfourensis, which provides habitat for a diverse assemblage of benthic organisms. However, the mechanism of this disturbance has not been explored. Here we show interspecific differences in anchor-ice formation and propagation characteristics for Antarctic benthic organisms. The sponges H. balfourensis and Suberites caminatus show increased incidence of formation and accelerated spread of ice crystals compared to urchins and sea stars. Anchor ice also forms readily on sediments, from which it can grow and adhere to organisms. Our results are consistent with, and provide a potential first step toward, an explanation for disturbance patterns observed in shallow polar benthic communities. Interspecific differences in ice formation raise questions about how surface tissue characteristics such as surface area, rugosity, and mucus coating affect ice formation on invertebrates.

Differences in composition of shallow-water marine benthic communities associated with two ophiolitic rock substrata

NASA Astrophysics Data System (ADS)

Bavestrello, Giorgio; Bo, Marzia; Betti, Federico; Canessa, Martina; Gaggero, Laura; Rindi, Fabio; Cattaneo-Vietti, Riccardo

2018-01-01

On marine rocky shores, several physical, chemical and biological processes operate to maintain the benthic assemblages' heterogeneity, but among the abiotic factors, the composition and texture of the rocky substrata have been only sporadically considered. However, biomineralogical studies have demonstrated an unsuspected ability of the benthic organisms to interact at different levels with rocky substrata. Therefore, the mineralogy of the substratum can affect the structure of benthic communities. To evaluate this hypothesis, the macrobenthic assemblages developed on two different ophiolitic rocks (serpentinites and metagabbros) in contact at a restricted stretch of the western Ligurian Riviera (western Mediterranean Sea), with identical environmental and climatic conditions, were analysed. Samplings were carried out at four bathymetric levels (+1m, 0m, -1m, and -3m respect to the mean sea level) and the analysis of the data evidenced differences in terms of species distribution and percent coverage. Algal communities growing on metagabbros were poorer in species richness and showed a much simpler structure when compared to the assemblages occurring on the serpentinites. The most widely distributed animal organism, the barnacle Chthamalus stellatus, was dominant on serpentinites, and virtually absent on metagabbros. Our results suggest a complex pattern of interactions between lithology and benthic organisms operating through processes of inhibition/facilitation related to the mineral properties of the substratum.

Characterizing the variability of benthic foraminifera in the northeastern Gulf of Mexico following the Deepwater Horizon event (2010-2012).

PubMed

Schwing, P T; O'Malley, B J; Romero, I C; Martínez-Colón, M; Hastings, D W; Glabach, M A; Hladky, E M; Greco, A; Hollander, D J

2017-01-01

Following the Deepwater Horizon (DWH) event in 2010 subsurface hydrocarbon intrusions (1000-1300 m) and an order of magnitude increase in flocculent hydrocarbon deposition caused increased concentrations of hydrocarbons in continental slope sediments. This study sought to characterize the variability [density, Fisher's alpha (S), equitability (E), Shannon (H)] of benthic foraminifera following the DWH event. A series of sediment cores were collected at two sites in the northeastern Gulf of Mexico from 2010 to 2012. At each site, three cores were utilized for benthic faunal analysis, organic geochemistry, and redox metal chemistry, respectively. The surface intervals (∼0-10 mm) of the sedimentary records collected in December 2010 at DSH08 and February 2011 at PCB06 were characterized by significant decreases in foraminiferal density, S, E, and H, relative to the down-core intervals as well as previous surveys. Non-metric multidimensional scaling (nMDS) analysis suggested that a 3-fold increase in polycyclic aromatic hydrocarbon (PAH) concentration in the surface interval, relative to the down-core interval, was the environmental driver of benthic foraminiferal variability. These records suggested that the benthic foraminiferal recovery time, following an event such as the DWH, was on the order of 1-2 years.

Predicting stress in benthic communities of southeastern U.S. estuaries in relation to chemical contamination of sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyland, J.L.; Dolah, R.F. van; Snoots, T.R.

1999-11-01

Matching data on sediment contaminants (metals, PAHs, PCBs) and macroinfaunal community structure from 231 subtidal stations in southeastern US estuaries were used to develop a framework for evaluating risks of benthic impacts from multiple-contaminant exposure. Sediment contamination was expressed as the mean ratio of individual contaminant concentrations relative to corresponding sediment quality guidelines, that is, to effects range-median (ERM) values, probable effects level (PEL) values, or an aggregate of the two. The probability of a degraded benthos was relatively low in samples with mean ERM quotients {le}0.020, PEL quotients {le}0.035, or combined ERM/PEL quotients {le}0.024. Only 5% of stations withinmore » these ranges had degraded benthic assemblages, while 95% had healthy assemblages. A higher probability of benthic impacts was observed in samples with mean ERM quotients >0.058, PEL quotients >0.096, or ERM/PEL quotients >0.077. Seventy-three to 78% of stations with values in these upper ranges had degraded benthic assemblages, while 22 to 27% had healthy assemblages. Only four stations (three with degraded, one with healthy assemblages) had mean ERM or PEL quotients >1.0, which is the beginning of the range associated with a high probability of mortality in short-term laboratory toxicity tests using amphipods.« less

Benthic macroinvertebrates in lake ecological assessment: A review of methods, intercalibration and practical recommendations.

PubMed

Poikane, Sandra; Johnson, Richard K; Sandin, Leonard; Schartau, Ann Kristin; Solimini, Angelo G; Urbanič, Gorazd; Arbačiauskas, Kęstutis; Aroviita, Jukka; Gabriels, Wim; Miler, Oliver; Pusch, Martin T; Timm, Henn; Böhmer, Jürgen

2016-02-01

Legislation in Europe has been adopted to determine and improve the ecological integrity of inland and coastal waters. Assessment is based on four biotic groups, including benthic macroinvertebrate communities. For lakes, benthic invertebrates have been recognized as one of the most difficult organism groups to use in ecological assessment, and hitherto their use in ecological assessment has been limited. In this study, we review and intercalibrate 13 benthic invertebrate-based tools across Europe. These assessment tools address different human impacts: acidification (3 methods), eutrophication (3 methods), morphological alterations (2 methods), and a combination of the last two (5 methods). For intercalibration, the methods were grouped into four intercalibration groups, according to the habitat sampled and putative pressure. Boundaries of the 'good ecological status' were compared and harmonized using direct or indirect comparison approaches. To enable indirect comparison of the methods, three common pressure indices and two common biological multimetric indices were developed for larger geographical areas. Additionally, we identified the best-performing methods based on their responsiveness to different human impacts. Based on these experiences, we provide practical recommendations for the development and harmonization of benthic invertebrate assessment methods in lakes and similar habitats. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Gray whale distribution relative to benthic invertebrate biomass and abundance: Northeastern Chukchi Sea 2009-2012

NASA Astrophysics Data System (ADS)

Brower, Amelia A.; Ferguson, Megan C.; Schonberg, Susan V.; Jewett, Stephen C.; Clarke, Janet T.

2017-10-01

The shallow continental shelf waters of the Bering and Chukchi seas are the northernmost foraging grounds of North Pacific gray whales (Eschrichtius robustus). Benthic amphipods are considered the primary prey of gray whales in these waters, although no comprehensive quantitative analysis has been performed to support this assumption. Gray whale relative abundance, distribution, and behavior in the northeastern Chukchi Sea (69°-72°N, 155-169°W) were documented during aerial surveys in June-October 2009-2012. Concurrently, vessel-based benthic infaunal sampling was conducted in the area in July-August 2009-10, September 2011, and August 2012. Gray whales were seen in the study area each month that surveys were conducted, with the majority of whales feeding. Statistical analyses confirm that the highest densities of feeding gray whales were associated with high benthic amphipod abundance, primarily within 70 km of shore from Point Barrow to Icy Cape, in water <50 m deep. Conversely, gray whales were not seen in 40-km×40-km cells containing benthic sampling stations with 85 m-2 or fewer amphipods. Continuing broad-scale aerial surveys in the Chukchi Sea and prey sampling near feeding gray whales will be an important means to monitor and document ongoing and predicted ecosystem changes.

Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

USGS Publications Warehouse

Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

2013-01-01

Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

Variability in Lotic Communities in Three Contrasting Stream Environments in the Santa Ana River Basin, California, 1999-2001

USGS Publications Warehouse

Burton, Carmen A.

2008-01-01

Biotic communities and environmental conditions can be highly variable between natural ecosystems. The variability of natural assemblages should be considered in the interpretation of any ecological study when samples are either spatially or temporally distributed. Little is known about biotic variability in the Santa Ana River Basin. In this report, the lotic community and habitat assessment data from ecological studies done as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program are used for a preliminary assessment of variability in the Santa Ana Basin. Habitat was assessed, and benthic algae, benthic macroinvertebrate, and fish samples were collected at four sites during 1999-2001. Three of these sites were sampled all three years. One of these sites is located in the San Bernardino Mountains, and the other two sites are located in the alluvial basin. Analysis of variance determined that the three sites with multiyear data were significantly different for 41 benthic algae metrics and 65 macroinvertebrate metrics and fish communities. Coefficients of variation (CVs) were calculated for the habitat measurements, metrics of benthic algae, and macroinvertebrate data as measures of variability. Annual variability of habitat data was generally greater at the mountain site than at the basin sites. The mountain site had higher CVs for water temperature, depth, velocity, canopy angle, streambed substrate, and most water-quality variables. In general, CVs of most benthic algae metrics calculated from the richest-targeted habitat (RTH) samples were greater at the mountain site. In contrast, CVs of most benthic algae metrics calculated from depositional-targeted habitat (DTH) samples were lower at the mountain site. In general, CVs of macroinvertebrate metrics calculated from qualitative multihabitat (QMH) samples were lower at the mountain site. In contrast, CVs of many metrics calculated from RTH samples were greater at the mountain site than at one of the basin sites. Fish communities were more variable at the basin sites because more species were present at these sites. Annual variability of benthic algae metrics was related to annual variability in habitat variables. The CVs of benthic algae metrics related to the most CVs of habitat variables included QMH taxon richness, the RTH percentage richness, RTH abundance of tolerant taxa, RTH percentage richness of halophilic diatoms, RTH percentage abundance of sestonic diatoms, DTH percentage richness of nitrogen heterotrophic diatoms, and DTH pollution tolerance index. The CVs of macroinvertebrate metrics related to the most CVs of habitat variables included the RTH trichoptera, RTH EPT, RTH scraper richness, RTH nonchironomid dipteran abundance (in percent), and RTH EPA (U.S. Environmental Protection Agency) tolerance, which is based on abundance. Many of the CVs of habitat variables related to CVs of macroinvertebrate metrics were the same habitat variables that were related to the CVs of benthic algae metrics. On the basis of these results, annual variability may have a role in the relationship of benthic algae and macroinvertebrates assemblages with habitat and water quality in the Santa Ana Basin. This report provides valuable baseline data on the variability of biological communities in the Santa Ana Basin.

DEVELOPMENT OF A STREAM BENTHIC MACROINVERTEBRATE INTEGRITY INDEX (SBMII) FOR WADEABLE STREAMS IN THE MID-ATLANTIC HIGHLANDS REGION

EPA Science Inventory

The Stream Benthic Macroinvertebrate Integrity Index (SBMII), a multimetric biotic index for assessing biological conditions of wadeable streams, was developed using seven macroinvertebrate metrics (Ephemeroptera richness, Plecoptera richness, Trichoptera richness, Collector-Filt...

BENTHIC MACROFAUNA-HABITAT RELATIONSHIPS IN TWO PACIFIC NORTHWEST ESTUARIES

EPA Science Inventory

Habitat-based ecological risk assessments rely, in part, on estimates of the ecological value of the habitats at risk. As part of a larger programmatic effort to estimate estuarine habitat values, we determined benthic macrofauna-habitat relationships for 8 intertidal habitats i...

Biogeographical Patterns of Marine Benthic Invertebrates Along the Atlantic Coast of the Northeastern USA

EPA Science Inventory

Aim Examine the biogeography of marine benthic invertebrates of the Atlantic coast of the northeastern USA, compare the results to historical biogeographic studies, define physical-chemical factors affecting species distributions, and provide biogeographic information needed to ...

RELATIONSHIP BETWEEN METABOLISM AND BIOACCUMULATION OF BENZO[A]PYRENE IN BENTHIC INVERTEBRATES

EPA Science Inventory

The potential influence of polycyclic aromatic hydrocarbon (PAH) metabolism on bioaccumulation is well accepted, but rarely has been examined in many species of benthic invertebrates that commonly are found in contaminated sediments, or used in bioaccumulation or toxicity tests. ...

Effects of heavy metals pollution on benthic foraminifera assemblage: the Gulf of Gabes, Tunisia

NASA Astrophysics Data System (ADS)

Ayadi, Najla; Zghal, Ihsen; Bouzid, Jalel; Abdennaceur Ouali, Jamel

2014-05-01

Benthic foraminifera are amongst the most abundant protists found in huge marine and brackish water habitat. During the last few decades, many researches had been focused on using benthic foraminifera as bioindicators of marine pollution caused by industrial, domestic and agricultural waste, oil or heavy metal contamination. The aim of this research is to investigate heavy metals pollution in superficial sediments in two industrial locations at the Gulf of Gabes and to examine the reaction of benthic foraminifera towards metallic concentration. The Gulf of Gabes, located on the eastern coast of Tunisia, is regarded as an extremely vital zone and considered as one of the most important area for fishing in the country. During last years, the coastal area of this region had known an important demographic and industrial development, leading to the presence of uncontrolled discharge. Fifteen superficial sediment samples were collected along the coastline of Skhira and Ghannouch- Gabes. They have been analyzed for Al, Cd, Cr, Cu, Pb, and Zn concentrations as well as for the species composition of benthic foraminifera. Results show three levels of metallic contamination with high concentration of cadmium and zinc. Thirty five benthic foraminifera species were identified. Ammonia parkinsoniana, Ammonia beccarii, Peneroplis planatus, Triloculina trigonula and Adelosina longirostraare are the most abundant and common species. Increasing pollution results in a lower species diversity as well as population density, with the presence of a barren zone, and more frequent abnormal specimens. A complementary statistical analysis (PCA/FA and matrix correlation) shows that heavy metals are resulting from the same anthropogenic source and negative correlation between faunal parameters (density and diversity) and pollutants concentrations.

Global reductions in seafloor biomass in response to climate change.

PubMed

Jones, Daniel O B; Yool, Andrew; Wei, Chih-Lin; Henson, Stephanie A; Ruhl, Henry A; Watson, Reg A; Gehlen, Marion

2014-06-01

Seafloor organisms are vital for healthy marine ecosystems, contributing to elemental cycling, benthic remineralization, and ultimately sequestration of carbon. Deep-sea life is primarily reliant on the export flux of particulate organic carbon from the surface ocean for food, but most ocean biogeochemistry models predict global decreases in export flux resulting from 21st century anthropogenically induced warming. Here we show that decadal-to-century scale changes in carbon export associated with climate change lead to an estimated 5.2% decrease in future (2091-2100) global open ocean benthic biomass under RCP8.5 (reduction of 5.2 Mt C) compared with contemporary conditions (2006-2015). Our projections use multi-model mean export flux estimates from eight fully coupled earth system models, which contributed to the Coupled Model Intercomparison Project Phase 5, that have been forced by high and low representative concentration pathways (RCP8.5 and 4.5, respectively). These export flux estimates are used in conjunction with published empirical relationships to predict changes in benthic biomass. The polar oceans and some upwelling areas may experience increases in benthic biomass, but most other regions show decreases, with up to 38% reductions in parts of the northeast Atlantic. Our analysis projects a future ocean with smaller sized infaunal benthos, potentially reducing energy transfer rates though benthic multicellular food webs. More than 80% of potential deep-water biodiversity hotspots known around the world, including canyons, seamounts, and cold-water coral reefs, are projected to experience negative changes in biomass. These major reductions in biomass may lead to widespread change in benthic ecosystems and the functions and services they provide. © 2013 The Authors Global Change Biology Published by John Wiley & Sons Ltd.

Late Glacial-Holocene record of benthic foraminiferal morphogroups from the eastern Arabian Sea OMZ: Paleoenvironmental implications

NASA Astrophysics Data System (ADS)

Verma, K.; Bharti, S. K.; Singh, A. D.

2018-03-01

The Arabian Sea is characterized today by a well-developed and perennial oxygen minimum zone (OMZ) at mid-water depths. The Indian margin where the OMZ impinges provides sediment records ideal to study past changes in the OMZ intensity and its vertical extent in response to the changes of monsoon-driven primary productivity and intermediate water ventilation. Benthic foraminifera, depending upon their adaptation capabilities to variation in sea floor environment and microhabitat preferences, develop various functional morphologies that can be potentially used in paleoenvironmental reconstruction. In this study, we analysed benthic foraminiferal morphogroups in assemblage records of the last 30 ka in a sediment core collected from the lower OMZ of the Indian margin (off Goa). In total, nine morphogroups within two broadly classified epifaunal and infaunal microhabitat categories are identified. The abundance of morphogroups varies significantly during the late Glacial, Deglacial and Holocene. It appears that monsoon wind driven organic matter flux, and water column ventilation governing the OMZ intensity and sea-bottom oxygen condition, have profound influence on structuring the benthic foraminiferal morphogroups. We found a few morphogroups showing major changes in their abundances during the periods corresponding to the northern hemisphere climatic events. Benthic foraminifera with planoconvex tests are abundant during the cold Heinrich events, when the sea bottom was oxygenated due to a better ventilated, weak OMZ; whereas, those having tapered/cylindrical tests dominate during the last glacial maximum and the Holocene between 5 and 8 ka BP, when the OMZ was intensified and poorly ventilated, leading to oxygen-depleted benthic environment. Characteristically, increased abundance of taxa with milioline tests during the Heinrich 1 further suggests enhanced ventilation attributed probably to the influence of oxygen-rich Antarctic Intermediate Water (AAIW).

Changes in dissolved organic material determine exposure of stream benthic communities to UV-B radiation and heavy metals: Implications for climate change

USGS Publications Warehouse

Clements, W.H.; Brooks, M.L.; Kashian, D.R.; Zuellig, R.E.

2008-01-01

Changes in regional climate in the Rocky Mountains over the next 100 years are expected to have significant effects on biogeochemical cycles and hydrological processes. In particular, decreased discharge and lower stream depth during summer when ultraviolet radiation (UVR) is the highest combined with greater photo-oxidation of dissolved organic materials (DOM) will significantly increase exposure of benthic communities to UVR. Communities in many Rocky Mountain streams are simultaneously exposed to elevated metals from abandoned mines, the toxicity and bioavailability of which are also determined by DOM. We integrated field surveys of 19 streams (21 sites) along a gradient of metal contamination with microcosm and field experiments conducted in Colorado, USA, and New Zealand to investigate the influence of DOM on bioavailability of heavy metals and exposure of benthic communities to UVR. Spatial and seasonal variation in DOM were closely related to stream discharge and significantly influenced heavy metal uptake in benthic organisms. Qualitative and quantitative changes in DOM resulting from exposure to sunlight increased UV-B (290-320nm) penetration and toxicity of heavy metals. Results of microcosm experiments showed that benthic communities from a metal-polluted stream were tolerant of metals, but were more sensitive to UV-B than communities from a reference stream. We speculate that the greater sensitivity of these communities to UV-B resulted from costs associated with metal tolerance. Exclusion of UVR from 12 separate Colorado streams and from outdoor stream microcosms in New Zealand increased the abundance of benthic organisms (mayflies, stoneflies, and caddisflies) by 18% and 54%, respectively. Our findings demonstrate the importance of considering changes in regional climate and UV-B exposure when assessing the effects of local anthropogenic stressors. ?? Journal compilation ?? 2008 Blackwell Publishing.

Assessment of stream quality using biological indices at selected sites in the Schuylkill River basin, Chester County, Pennsylvania, 1981-97

USGS Publications Warehouse

Reif, Andrew G.

2002-01-01

IntroductionIn 1970, the Chester County Water Resources Authority (Pennsylvania) and the U.S. Geological Survey (USGS) established a long-term water-quality network with the goal of assessing the quality of streams in the county and understanding stream changes in response to urbanization using benthic-macroinvertebrate data. This database represents one of the longest continuous water-quality data sets in the country. Benthic macroinvertebrates are aquatic insects, such as mayflies, caddisflies, riffle beetles, and midges, and other invertebrates that live on the stream bottom. Benthic macroinvertebrates are useful in evaluating stream quality because their habitat preferences and low motility cause them to be affected directly by substances that enter the aquatic system. By evaluating the diversity and community structure of benthic-macroinvertebrate populations, a determination of stream quality can be made.Between 1981 and 1997, the network consisted of 43 sites in 5 major basins in Chester County—Delaware, Schuylkill, Brandywine, Big Elk and Octoraro, and Red and White Clay. Benthic-macroinvertebrate, water-chemistry, and habitat data were collected each year in October or November during base-flow conditions. Using these data, Reif evaluated the overall water-quality condition of Chester County streams. This Fact Sheet summarizes the key findings from Reif for streams in the Schuylkill River Basin. These streams include Pigeon Creek (site 10), Stony Run (site 6), French Creek (sites 12-16), Pickering Creek (sites 1-5), Little Valley Creek (site 49), and Valley Creek (site 50). This summary includes an analysis of stream conditions based on benthic-macroinvertebrate samples and an analysis of trends in stream conditions for the 17-year study period.

Deep ocean ventilation in the Central Fram Strait during the past 35 kyr

NASA Astrophysics Data System (ADS)

Ezat, M.; Rasmussen, T. L.; Skinner, L.; Zamelczyk, K.

2017-12-01

Ocean ventilation in the Arctic Mediterranean via transformation of northward inflowing warm Atlantic surface water into cold deep water affects regional climate, large-scale atmospheric circulation and carbon storage in the deep ocean. Radiocarbon dating of benthic foraminifera has been used to suggest a near-cessation of Arctic Ocean ventilation during the Last Glacial Maximum. During the last deglaciation episodic surges of this Arctic `aged' glacial deep water into the Nordic Seas and the subpolar North Atlantic Ocean may have occurred (Thornalley et al., 2011, 2015; Science). A recent study from the SE Norwegian Sea and the Iceland Basin has revealed large radiocarbon age differences between different benthic foraminiferal species during the last deglaciation (Ezat et al., 2017; Paleoceanography), which arguments for a re-evaluation of previous bottom-water radiocarbon ventilation age reconstructions from the region. Here, we present new species-specific benthic and planktic foraminiferal radiocarbon dates from the central Fram Strait and the SE Norwegian Sea for the past 35 kyr. Several lines of evidence in this new dataset demonstrate that the previously suggested `extreme aging' of >6000 14C years in the Arctic Mediterranean is most likely erroneous. In addition, benthic-planktic age offsets in the deep central Fram Strait display a remarkable decrease from 1300-2300 14C years in late Marine Isotope Stage (MIS) 3 to 0-500 14C year in MIS 2, which correlates with a decrease in benthic d13C and reduction in the benthic-planktic d18O gradient. We are in the process of compiling/screening published ventilation age reconstructions from the Arctic Mediterranean and the subpolar North Atlantic in the light of our new results in order to establish a basin-scale evolution of ocean ventilation since late MIS 3 in this region.

REINFORCEMENT OF STICKLEBACK MATE PREFERENCES: SYMPATRY BREEDS CONTEMPT.

PubMed

Rundle, Howard D; Schluter, Dolph

1998-02-01

Detailed studies of reproductive isolation and how it varies among populations can provide valuable insight into the mechanisms of speciation. Here we investigate how the strength of premating isolation varies between sympatric and allopatric populations of threespine sticklebacks to test a prediction of the hypothesis of reinforcement: that interspecific mate discrimination should be stronger in sympatry than in allopatry. In conducting such tests, it is important to control for ecological character displacement between sympatric species because ecological character divergence may strengthen prezygotic isolation as a by-product. We control for ecological character displacement by comparing mate preferences of females from a sympatric population (benthics) with mate preferences of females from two allopatric populations that most closely resemble the sympatric benthic females in ecology and morphology. No-choice mating trials indicate that sympatric benthic females mate less readily with heterospecific (limnetic) than conspecific (benthic) males, whereas two different populations of allopatric females resembling benthics show no such discrimination. These differences demonstrate reproductive character displacement of benthic female mate choice. Previous studies have established that hybridization between sympatric species occurred in the past in the wild and that hybrid offspring have lower fitness than either parental species, thus providing conditions under which natural selection would favor individuals that do not hybridize. Results are therefore consistent with the hypothesis that female mate preferences have evolved as a response to reduced hybrid fitness (reinforcement), although direct effects of sympatry or a biased extinction process could also produce the pattern. Males of the other sympatric species (limnetics) showed a preference for smaller females, in contrast to the inferred ancestral preference for larger females, suggesting reproductive character displacement of limnetic male mate preferences as well. © 1998 The Society for the Study of Evolution.

Benthic metabolism over the emersion - immersion alternation in sands colonized by the invasive Manila clam Ruditapes philippinarum

NASA Astrophysics Data System (ADS)

Migné, Aline; Trigui, Rima Jihane; Davoult, Dominique; Desroy, Nicolas

2018-01-01

The effect of an invasive infaunal suspension-feeding bivalve, the Manila clam Ruditapes philippinarum, on benthic inorganic carbon and nutrient fluxes was examined through in situ incubations. Measurements were performed in spring and summer on a tidal sandflat of the Rance estuary (south part of the Western English Channel) colonized by the Manila clam after its deliberate introduction in the 1990's. Benthic inorganic carbon fluxes were measured using light and dark benthic chambers both at emersion and immersion. Benthic nutrient fluxes were measured using dark benthic chambers at immersion. Inorganic carbon (IC) and ammonium sediment release under darkness at immersion reached 5.60 mmol m-2 h-1 and 441 μmol m-2 h-1 respectively for a clam density of 291 ind m-2. The sediment IC-release under darkness was lower during emersion than during immersion, probably due to the reduced activity of infauna at low tide. Under ambient light, a sediment IC-uptake was systematically measured at emersion, indicating a net autotrophy under the condition of measurements (125 < surface PAR < 1670 μmol m-2 s-1), while either sediment IC-uptake or release was measured at immersion according to light variation (20 < underwater PAR < 990 μmol m-2 s-1). The highest gross community primary production, calculated from highest IC-fluxes at light (i.e. net community production) and highest IC-fluxes at dark (i.e. community respiration), was similar at emersion and immersion and reached 6.2 mmolC m-2 h-1. These results suggest that the metabolic activity of the invasive Manila clam Ruditapes philippinarum contributes to increase inorganic C and ammonium sediment release. These regenerated nutrients may support microphytobenthic production which appeared particularly high on this intertidal sand flat.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunter, C.; Simpson, J.; Kovats, Z.

Sediments from Soda Creek were evaluated using the Sediment Quality Triad as part of investigations being conducted at the Monsanto Company plant in Soda Springs, Idaho. Information collected by an ecological assessment included metal concentrations (arsenic, cadmium, copper, molybdenum, nickel, selenium, silver, and vanadium), benthic fauna community structure, and sediment toxicity. The collected sediments were composed of sandy-silt sized particles, with 2.4% to 9.1% organic carbon. Metal concentrations at sample stations were elevated relative to sediments collected from reference stations. For example, average cadmium concentrations ranged from 13 to 48 mg/kg at sample stations and 0.72 to 3.2 mg/kg atmore » reference stations; selenium concentrations ranged from 4.7 to 91 mg/kg at sample stations and 0.82 to 2.7 mg/kg at reference stations. Soda Creek has a relatively low flow gradient and the benthic fauna at both reference and sample stations was dominated by oligochaete worms and chironomid midge larvae. Taxonomic richness at individual sites ranged from 4.3 to 6.7 and 6 to 10.3 at reference and sample sites, respectively. There was no significant evidence of toxicity at any location sampled. Cluster analysis showed that the benthic community structure of many of the sample stations could not be distinguished from the reference stations. Canonical correlation analysis showed there was a significant relationship between benthic fauna and metal concentration, but there was not a consistent difference between sample and reference stations. For Soda Creek, local phenomena were more significant to benthic community structure than large-scale patterns of metal accumulation. Using the Triad approach, the authors concluded there has been no adverse effect of metal concentrations on the benthic community of Soda Creek.« less

Possible energetic linkage between primary production and deep-sea benthic archaea: insight from biogeochemical lipidomics

NASA Astrophysics Data System (ADS)

Takano, Yoshinori; Ohkouchi, Naohiko

2013-04-01

Marine archaea have been recognized as a cosmopolitan player for global carbon and nitrogen cycles in the water column and sub-seafloor environments. Recent molecular evidence based on lipids and DNA suggests that uncultured benthic archaea dominate biomass in marine sediment, implying past primary production is a crucial factor for their presently ongoing heterotrophy (e.g., 1-4). Focusing on benthic archaeal heterotrophic processes in deep-sea sediment, we preliminarily traced 13C-signature in archaeal lipids to determine de novo and salvage pathway by in situ 13C-experiment. On the basis of the differential 13C-uptake, we suggest that benthic archaea recycles sedimentary relic membrane lipids to minimize the energy expenditure during 405 days (5). The 16S rRNA and quantitative PCR analysis indicated a community shift in the composition of the benthic archaeal community (e.g., Marine Group I, Marine Benthic Group, Miscellaneous Crenarchaeotic Group). In bacteria and eukarya, it is commonly recognized that free fatty acids are incorporated into cells and converted to acyl-CoA, which are eventually incorporated into membrane lipids as a salvage pathway (cf. 6). Considering the suggestion of salvage pathway in archaeal membrane synthesis (7,8), we discuss archaeal heterotrophic processes in terms of possible biogeochemical lipidomics. Reference [1] Biddle et al., (2006) PNAS, 103, 3846-3851. [2] Lipp et al., (2008) Nature, 454, 991-994. [3] Kallmeyer et al., (2012) PNAS, doi: 10.1073/pnas.1203849109 [4] Hinrichs and Inagaki, (2012) Science, 338, 204-205. [5] Takano et al., (2010) Nature Geosci., 3, 858-861. [6] Silbert et al., (1968) J Bacteriol., 95, 1658-1665. [7] Poulter et al., (1988) JACS, 110, 2620-2624. [8] Ohnuma et al., (1996) J Biochem., 119, 541-547.

Benthic-Pelagic Coupling: Effects on Nematode Communities along Southern European Continental Margins

PubMed Central

Pape, Ellen; Jones, Daniel O. B.; Manini, Elena; Bezerra, Tania Nara; Vanreusel, Ann

2013-01-01

Along a west-to-east axis spanning the Galicia Bank region (Iberian margin) and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m). Nematode standing stock (abundance and biomass) and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude) governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter). Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes. PMID:23565176

Microbial interactions in marine water amended by eroded benthic biofilm: A case study from an intertidal mudflat

NASA Astrophysics Data System (ADS)

Montanié, Hélène; Ory, Pascaline; Orvain, Francis; Delmas, Daniel; Dupuy, Christine; Hartmann, Hans J.

2014-09-01

In shallow macrotidal ecosystems with large intertidal mudflats, the sediment-water coupling plays a crucial role in structuring the pelagic microbial food web functioning, since inorganic and organic matter and microbial components (viruses and microbes) of the microphytobenthic biofilm can be suspended toward the water column. Two experimental bioassays were conducted in March and July 2008 to investigate the importance of biofilm input for the pelagic microbial and viral loops. Pelagic inocula (< 0.6 μ- and < 10 μ filtrates) were diluted either with < 30 kDa-ultrafiltered seawater or with this ultrafiltrate enriched with the respective size-fractionated benthic biofilm or with < 30 kDa-benthic compounds (BC). The kinetics of heterotrophic nanoflagellates (HNF), bacteria and viruses were assessed together with bacterial and viral genomic fingerprints, bacterial enzymatic activities and viral life strategies. The experimental design allowed us to evaluate the effect of BC modulated by those of benthic size-fractionated microorganisms (virus + bacteria, + HNF). BC presented (1) in March, a positive effect on viruses and bacteria weakened by pelagic HNF. Benthic microorganisms consolidated this negative effect and sustained the viral production together with a relatively diverse and uneven bacterial assemblage structure; (2) in July, no direct impact on viruses but a positive effect on bacteria modulated by HNF, which indirectly enhanced viral multiplication. Both effects were intensified by benthic microorganisms and bacterial assemblage structure became more even. HNF indirectly profited from BC more in March than in July. The microbial loop would be stimulated by biofilm during periods of high resources (March) and the viral loop during periods of depleted resources (July).

[Effects of cascading hydropower dams operation on the structure and distribution pattern of benthic macroinvertebrate assemblages in Manwan Reservoir, Southwest China].

PubMed

Li, Jin Peng; Dong, Shi Kui; Peng, Ming Chun; Wu, Xuan; Zhou, Fang; Yu, Yin

2017-12-01

Benthic macroinvertebrate assemblages are one of the biological groups in aquatic ecosystem most sensitive to the habitat change and degradation, and can be a biological indicator for the aquatic ecosystem change and succession in cascading hydropower dam reservoir. The middle and lower reaches of the Lancang River are key spot for international biodiversity conservation and ecological studies on the effects of cascading hydropower dam exploitation. In this study, the reservoir of Manwan hydropower dam, the first dam in Lancang-Mekong river main stream, was selected as the study site. The benthic macroinvertebrate assemblages were sampled in 2011 and 2016 respectively. Meanwhile, the survey data before impounding (natural river, 1996) and early stage of single dam (1997) were collected to conduct the overall analysis for structure, distribution pattern and evolution of benthic macroinvertebrate assemblages. The results showed that the dominant biological group was gradually changed from the Oligochaeta and Insecta to the Mollusca. Along the longitudinal gradient, the density and biomass of the benthic macroinvertebrate assemblages were remarkably increased in reservoir, especially in the lacustrine zone. As for the functional feeding group, the predator and gatherer-collector changed into filter-collector predominantly in lacustrine zone. With the cascading dams operation, the biotic index indicated that the water quality of reservoir in 2016 was better than in 2011. The evolution of benthic macroinvertebrate assemblages in the Manwan Reservoir was related to the operation of Xiaowan dam in the upper reach, the hydrological regime and siltation in the reservoir, and would continue with dynamic changes with the operation of the cascading hydropower dam.

Assessing sediments from Upper Mississippi River navigational pools using a benthic invertebrate community evaluation and the sediment quality triad approach

USGS Publications Warehouse

Canfield, T.J.; Brunson, E.L.; Dwyer, F.J.; Ingersoll, C.G.; Kemble, N.E.

1998-01-01

Benthic invertebrate samples were collected from 23 pools in the Upper Mississippi River (UMR) and from one station in the Saint Croix River (SCR) as part of a study to assess the effects of the extensive flooding of 1993 on sediment contamination in the UMR system. Sediment contaminants of concern included both organic and inorganic compounds. Oligochaetes and chironomids constituted over 80% of the total abundance in samples from 14 of 23 pools in the UMR and SCR samples. Fingernail clams comprised a large portion of the community in three of 23 UMR pools and exceeded abundances of 1,000/m2 in five of 23 pools. Total abundance ranged from 250/m2 in samples from pool 1 to 22,389/m2 in samples from pool 19. Abundance values are comparable with levels previously reported in the literature for the UMR. Overall frequency of chironomid mouthpart deformities was 3% (range 0-13%), which is comparable to reported incidence of deformities in uncontaminated sediments previously evaluated. Sediment contamination was generally low in the UMR pools and the SCR site. Correlations between benthic measures and sediment chemistry and other abiotic parameters exhibited few significant or strong correlations. The sediment quality triad (Triad) approach was used to evaluate data from laboratory toxicity tests, sediment chemistry, and benthic community analyses; it showed that 88% of the samples were not scored as impacted based on sediment toxicity, chemistry, and benthic measures. Benthic invertebrate distributions and community structure within the UMR in the samples evaluated in the present study were most likely controlled by factors independent of contaminant concentrations in the sediments.

Benthic Primary Production Budget of a Caribbean Reef Lagoon (Puerto Morelos, Mexico)

PubMed Central

Naumann, Malik S.; Jantzen, Carin; Haas, Andreas F.; Iglesias-Prieto, Roberto; Wild, Christian

2013-01-01

High photosynthetic benthic primary production (P) represents a key ecosystem service provided by tropical coral reef systems. However, benthic P budgets of specific ecosystem compartments such as macrophyte-dominated reef lagoons are still scarce. To address this, we quantified individual and lagoon-wide net (Pn) and gross (Pg) primary production by all dominant functional groups of benthic primary producers in a typical macrophyte-dominated Caribbean reef lagoon near Puerto Morelos (Mexico) via measurement of O2 fluxes in incubation experiments. The photosynthetically active 3D lagoon surface area was quantified using conversion factors to allow extrapolation to lagoon-wide P budgets. Findings revealed that lagoon 2D benthic cover was primarily composed of sand-associated microphytobenthos (40%), seagrasses (29%) and macroalgae (27%), while seagrasses dominated the lagoon 3D surface area (84%). Individual Pg was highest for macroalgae and scleractinian corals (87 and 86 mmol O2 m−2 specimen area d−1, respectively), however seagrasses contributed highest (59%) to the lagoon-wide Pg. Macroalgae exhibited highest individual Pn rates, but seagrasses generated the largest fraction (51%) of lagoon-wide Pn. Individual R was highest for scleractinian corals and macroalgae, whereas seagrasses again provided the major lagoon-wide share (68%). These findings characterise the investigated lagoon as a net autotrophic coral reef ecosystem compartment revealing similar P compared to other macrophyte-dominated coastal environments such as seagrass meadows and macroalgae beds. Further, high lagoon-wide P (Pg: 488 and Pn: 181 mmol O2 m−2 lagoon area d−1) and overall Pg:R (1.6) indicate substantial benthic excess production within the Puerto Morelos reef lagoon and suggest the export of newly synthesised organic matter to surrounding ecosystems. PMID:24367570

Benthic response to the sedimentation of particulate organic matter at the BIOTRANS station, 47°N, 20°W

NASA Astrophysics Data System (ADS)

Pfannkuche, O.

The benthic response to the sedimentation of particulate organic matter (POM) was investigated during 1985-1990 at 47°N, 20°W (BIOTRANS station). The first noticeable annual sedimentation of phytodetritus, as indicated by chlorophyll a concentrations in the sediment, occurred as early as late April-early May. Maximum amounts were found in June-July. Two different sedimentation pulses to the sea bed are described that demonstrate interannual variation: the occurrence of salp faecal pellets early in the year 1988 and the massive fall out of a plankton bloom in summer 1986, which deposited approximately 15 mmol C m -2. The benthic reaction to POM pulses was quite diverse. The mega-, macro- and meiobenthos showed no change in biomass, whereas bacterial biomass doubled between March and July. This corresponds to a seasonal maximum of total adenylate biomass. The relative abundance of Foraminifera among the meiobenthos increased during the summer. Benthic activity (ATP, ratio ATP/ETSA), as well as in situ sediment community oxygen consumption rates (SCOC), showed distinct seasonal maxima in July-August of 0.75 mmol C m -2 day -1. Based on SCOC and the carbon demand for growth, a benthic carbon consumption of 0.94 mmol C m -2 day -1 was estimated. This represents about 1.1% of spring bloom primary production and 9.6% of the export flux beneath the 150 m layer, measured during the North Atlantic Bloom Experiment. Bacteria and protozoans colonizing the epibenthic phytodetrital layer were responsible for 60-80% of the seasonal increase in SCOC. The strong reaction of the smaller benthic size groups (bacteria, protozoans) to POM pulses stresses their particular importance for sediment-water interface flux rates.

Gap Analysis of Benthic Mapping at Three National Parks: Assateague Island National Seashore, Channel Islands National Park, and Sleeping Bear Dunes National Lakeshore

USGS Publications Warehouse

Rose, Kathryn V.; Nayegandhi, Amar; Moses, Christopher S.; Beavers, Rebecca; Lavoie, Dawn; Brock, John C.

2012-01-01

The National Park Service (NPS) Inventory and Monitoring (I&M) Program initiated a benthic habitat mapping program in ocean and coastal parks in 2008-2009 in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. With more than 80 ocean and Great Lakes parks encompassing approximately 2.5 million acres of submerged territory and approximately 12,000 miles of coastline (Curdts, 2011), this Servicewide Benthic Mapping Program (SBMP) is essential. This report presents an initial gap analysis of three pilot parks under the SBMP: Assateague Island National Seashore (ASIS), Channel Islands National Park (CHIS), and Sleeping Bear Dunes National Lakeshore (SLBE) (fig. 1). The recommended SBMP protocols include servicewide standards (for example, gap analysis, minimum accuracy, final products) as well as standards that can be adapted to fit network and park unit needs (for example, minimum mapping unit, mapping priorities). The SBMP requires the inventory and mapping of critical components of coastal and marine ecosystems: bathymetry, geoforms, surface geology, and biotic cover. In order for a park unit benthic inventory to be considered complete, maps of bathymetry and other key components must be combined into a final report (Moses and others, 2010). By this standard, none of the three pilot parks are mapped (inventoried) to completion with respect to submerged resources. After compiling the existing benthic datasets for these parks, this report has concluded that CHIS, with 49 percent of its submerged area mapped, has the most complete benthic inventory of the three. The ASIS submerged inventory is 41 percent complete, and SLBE is 17.5 percent complete.