Science.gov

Sample records for rocky intertidal shore

  1. Microhabitat use by two rocky shore gastropods in an intertidal sandy substrate with rocky fragments.

    PubMed

    Turra, A; Denadai, M R

    2006-02-01

    Sandy beaches in some areas of the São Sebastião Channel in southeastern Brazil have unremittingly undergone a variety of impacts, including the deposition of rock fragments in the intertidal region. Consequently, these environments support a rich fauna comprising both sandy beach and rocky shore organisms. Two rocky shore gastropods, Tegula viridula and Morula nodulosa, are particularly abundant in such environments. An evaluation of the use of microhabitats by these two species revealed that they occupy the available microhabitats in different proportions and the presence of one species is associated with the absence of the other. Morula nodulosa is randomly dispersed, occupying mostly areas with rock fragments covered with sediment and branching brown algae. Tegula viridula shows a clumped dispersion associated with the patchiness of the microhabitats used: the presence of encrusting green algae and absence of sediment and branching brown algae covering the rocks. These findings suggest T. viridula has a lower tolerance than M. nodulosa to sand inundation of the rocky fragments, a stochastic event common to the environment in question.

  2. Abundance of biofilm on intertidal rocky shores: can trampling by humans be a negative influence?

    PubMed

    Leite, Lucas G; Ciotti, Áurea M; Christofoletti, Ronaldo A

    2012-08-01

    Trampling by human visitors to rocky shores is a known stressor on macroorganisms. However, the effects of trampling on rocky intertidal biofilm, a complex association of microorganisms of ecological importance in coastal communities, have not been quantified. We evaluated the impact of trampling frequency and intensity on total biomass of epilithic microalgae on intertidal rocky shores in the southeast of Brazil. There was a trend of increase in the variability of biomass of biofilm in function of intensity of trampling, but no significant effects emerged among trampling treatments. The low influence of trampling on biofilm might be a result of the small dimensions of the organisms coupled with their natural resilience and roughness of the substrate; the former preventing the removal of biofilm layers by shoes and facilitating their quick recovery. Our results provide insights for management and conservation of coastal ecosystems revealing a weaker impact of trampling on biofilm than that reported on macroorganisms. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Regulation of intertidal food webs by avian predators on New England rocky shores.

    PubMed

    Ellis, Julie C; Shulman, Myra J; Wood, Megan; Witman, Jon D; Lozyniak, Sara

    2007-04-01

    Although there is a large body of research on food webs in rocky intertidal communities, most of the emphasis has been on the marine benthic components. Effects of avian predation on highly mobile predators such as crabs, remains practically unstudied in rocky shore ecosystems. The crab, Cancer borealis, is an important component of the diet of gulls (Larus marinus, L. argentatus) at the Isles of Shoals, Maine, USA. C. borealis prey include the predatory gastropod Nucella lapillus L., the herbivore Littorina littorea, and mussels Mytilus edulis L. We hypothesized that gulls reduce abundance of C. borealis in the low intertidal and shallow subtidal, thereby allowing C. borealis prey to persist in high numbers. A study of crab tidal migration showed that C. borealis density nearly doubled at high tide compared to low tide; thus, crabs from a large subtidal source population migrate into the intertidal zone during high tides and either emigrate or are removed by gulls during low tides. Results from a small-scale (1 m2) predator caging experiment in the low intertidal zone indicated that enclosed crabs significantly reduced L. littorea abundance when protected from gull predation. In a much larger-scale gull exclusion experiment, densities of C. borealis increased significantly during low and high tides in exclosures relative to the controls. C. borealis density was inversely correlated with changes in the abundance of two mesopredators Carcinus maenas and Nucella lapillus, and with the space-occupier M. edulis. There was a similar negative correlation between abundance of C. borealis and the change in abundance of the herbivore L. littorea, but the trend was not significant. Mortality of tethered L. littorea was associated with C. borealis density across sites. However, preferred algae did not change in response to L. littorea density during the experiment. Thus, we found suggestive, but not conclusive, evidence for a three-level cascade involving gulls, crabs, and L

  4. Patterns of Spatial Variation of Assemblages Associated with Intertidal Rocky Shores: A Global Perspective

    PubMed Central

    Cruz-Motta, Juan José; Miloslavich, Patricia; Palomo, Gabriela; Iken, Katrin; Konar, Brenda; Pohle, Gerhard; Trott, Tom; Benedetti-Cecchi, Lisandro; Herrera, César; Hernández, Alejandra; Sardi, Adriana; Bueno, Andrea; Castillo, Julio; Klein, Eduardo; Guerra-Castro, Edlin; Gobin, Judith; Gómez, Diana Isabel; Riosmena-Rodríguez, Rafael; Mead, Angela; Bigatti, Gregorio; Knowlton, Ann; Shirayama, Yoshihisa

    2010-01-01

    Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses. PMID:21179546

  5. Patterns of spatial variation of assemblages associated with intertidal rocky shores: a global perspective.

    PubMed

    Cruz-Motta, Juan José; Miloslavich, Patricia; Palomo, Gabriela; Iken, Katrin; Konar, Brenda; Pohle, Gerhard; Trott, Tom; Benedetti-Cecchi, Lisandro; Herrera, César; Hernández, Alejandra; Sardi, Adriana; Bueno, Andrea; Castillo, Julio; Klein, Eduardo; Guerra-Castro, Edlin; Gobin, Judith; Gómez, Diana Isabel; Riosmena-Rodríguez, Rafael; Mead, Angela; Bigatti, Gregorio; Knowlton, Ann; Shirayama, Yoshihisa

    2010-12-16

    Assemblages associated with intertidal rocky shores were examined for large scale distribution patterns with specific emphasis on identifying latitudinal trends of species richness and taxonomic distinctiveness. Seventy-two sites distributed around the globe were evaluated following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). There were no clear patterns of standardized estimators of species richness along latitudinal gradients or among Large Marine Ecosystems (LMEs); however, a strong latitudinal gradient in taxonomic composition (i.e., proportion of different taxonomic groups in a given sample) was observed. Environmental variables related to natural influences were strongly related to the distribution patterns of the assemblages on the LME scale, particularly photoperiod, sea surface temperature (SST) and rainfall. In contrast, no environmental variables directly associated with human influences (with the exception of the inorganic pollution index) were related to assemblage patterns among LMEs. Correlations of the natural assemblages with either latitudinal gradients or environmental variables were equally strong suggesting that neither neutral models nor models based solely on environmental variables sufficiently explain spatial variation of these assemblages at a global scale. Despite the data shortcomings in this study (e.g., unbalanced sample distribution), we show the importance of generating biological global databases for the use in large-scale diversity comparisons of rocky intertidal assemblages to stimulate continued sampling and analyses.

  6. Regional scale estimation of carbon fluxes from long-term monitoring of intertidal exposed rocky shore communities

    NASA Astrophysics Data System (ADS)

    Tagliarolo, Morgana; Grall, Jacques; Chauvaud, Laurent; Clavier, Jacques

    2015-09-01

    The observed increase in the atmospheric concentration of carbon dioxide due to anthropogenic emissions is predicted to lead to significant changes in climate. Recent studies highlight the importance of identifying the role of marine coastal communities in carbon exchanges. Our objective was to couple macrozoobenthos abundance data from long-term monitoring with species metabolism rates to contribute to the estimation of CO2 fluxes from an intertidal exposed rocky shore community at a regional scale. The carbon fluxes due to respiration and calcification were calculated both during emersion and immersion, and the effect of temperature variation on carbon emissions was then predicted. Spatial and temporal natural variations of carbon fluxes were investigated and the contribution of exposed intertidal rocky shore communities to regional carbon emissions was calculated. The method was used to calculate the carbon budget allowed to account for the natural spatial variability of the community composition and carbon emissions. Mean annual calculated CO2 emission was 14.3 mol C m- 2 yr- 2, and the annual regional CO2 flux was estimated at 2978 t C yr- 1. Simulations showed that the potential feedback of a rise in temperature of 1 °C would lead to an increase of 4-7% in carbon emissions for this type of community. The results give a first quantification of intertidal exposed rocky shore carbon emissions that could be considered in evaluating further the global CO2 budget.

  7. Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil.

    PubMed

    Breves, André; Széchy, Maria Teresa M DE; Lavrado, Helena P; Junqueira, Andrea O R

    2017-01-01

    The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes.

  8. Invasion of a rocky intertidal shore by the tunicate Pyura praeputialis in the Bay of Antofagasta, Chile.

    PubMed

    Castilla, Juan Carlos; Guiñez, Ricardo; Caro, Andrés U; Ortiz, Verónica

    2004-06-08

    Invasion by marine nonindigenous species (NIS) is a spread phenomenon. The tunicate Pyura praeputialis shows pronounced disjoint geographical distribution: along thousands of kilometers in wave-swept headlands on the southeastern coast of Australia, from where it appears to have originated, and exclusively along 60-70 km inside the Bay of Antofagasta, Chile. mtDNA sequences suggested that the species invaded this rocky shore recently. We used field manipulations and juvenile P. praeputialis transplant techniques to test hypotheses regarding the capacity of the tunicate to survive and grow at different sites and tidal heights inside and outside Antofagasta, and its competitive performance for primary space (inside the Bay) against the native mussel Perumytilus purpuratus. We conclude that survival and growth of P. praeputialis showed no significant differences among sites inside and outside the Bay, and suggest that the restrictive distribution of the species in Chile is caused by a specific oceanographic retention mechanism and/or its brief larval dispersal. We demonstrated that, inside the Bay, P. praeputialis outcompetes Perumytilus from the Mid-Low intertidal, constraining Perumytilus to the Upper Mid-Intertidal, modifying the local pattern of intertidal zonation. We show that predation on P. praeputialis juveniles by starfish and snails constitutes a regulatory mechanism for the setting of its low intertidal limit. Major ecological impacts caused by NIS invasions to rocky shores by aggressive primary space users may result in negative aspects, but also may contribute to biodiversity enhancement. We call attention to the need for increment manipulations and testing of ecological hypotheses regarding marine NIS.

  9. Invasion of a rocky intertidal shore by the tunicate Pyura praeputialis in the Bay of Antofagasta, Chile

    PubMed Central

    Castilla, Juan Carlos; Guiñez, Ricardo; Caro, Andrés U.; Ortiz, Verónica

    2004-01-01

    Invasion by marine nonindigenous species (NIS) is a spread phenomenon. The tunicate Pyura praeputialis shows pronounced disjoint geographical distribution: along thousands of kilometers in wave-swept headlands on the southeastern coast of Australia, from where it appears to have originated, and exclusively along 60–70 km inside the Bay of Antofagasta, Chile. mtDNA sequences suggested that the species invaded this rocky shore recently. We used field manipulations and juvenile P. praeputialis transplant techniques to test hypotheses regarding the capacity of the tunicate to survive and grow at different sites and tidal heights inside and outside Antofagasta, and its competitive performance for primary space (inside the Bay) against the native mussel Perumytilus purpuratus. We conclude that survival and growth of P. praeputialis showed no significant differences among sites inside and outside the Bay, and suggest that the restrictive distribution of the species in Chile is caused by a specific oceanographic retention mechanism and/or its brief larval dispersal. We demonstrated that, inside the Bay, P. praeputialis outcompetes Perumytilus from the Mid–Low intertidal, constraining Perumytilus to the Upper Mid-Intertidal, modifying the local pattern of intertidal zonation. We show that predation on P. praeputialis juveniles by starfish and snails constitutes a regulatory mechanism for the setting of its low intertidal limit. Major ecological impacts caused by NIS invasions to rocky shores by aggressive primary space users may result in negative aspects, but also may contribute to biodiversity enhancement. We call attention to the need for increment manipulations and testing of ecological hypotheses regarding marine NIS. PMID:15118086

  10. Ecological convergence in a rocky intertidal shore metacommunity despite high spatial variability in recruitment regimes

    PubMed Central

    Caro, Andrés U.; Navarrete, Sergio A.; Castilla, Juan Carlos

    2010-01-01

    In open ecological systems, community structure can be determined by physically modulated processes such as the arrival of individuals from a regional pool and by local biological interactions. There is debate centering on whether niche differentiation and local interactions among species are necessary to explain macroscopic community patterns or whether the patterns can be generated by the neutral interplay of dispersal and stochastic demography among ecologically identical species. Here we evaluate how much of the observed spatial variation within a rocky intertidal metacommunity along 800 km of coastline can be explained by drift in the structure of recruits across 15 local sites. Our results show that large spatial changes in recruitment do not explain the observed spatial variation in adult local structure and that, in comparison with the large drift in structure of recruits, local adult communities converged to a common, although not unique, structure across the region. Although there is no unique adult community structure in the entire region, the observed variation represents only a small subset of the possible structures that would be expected from passive recruitment drift. Thus, in this diverse system our results do not support the idea that rocky intertidal metacommunities are structured by neutral mechanisms. PMID:20937867

  11. Seasonal patterns and recruitment dynamics of green tide-forming Ulva species along the intertidal rocky shores of the southern coast of Korea

    NASA Astrophysics Data System (ADS)

    Park, Sang Rul

    2014-12-01

    The abundance of two Ulva species in unmanipulated and artificial plots was investigated to better understand the ecological aspects of green tides on the intertidal rocky shore of the southern coast of Korea from July 1998 to January 2001. Artificial substrates were made on ceramic tiles (200 cm2) using a mixture of cement and rock and were set up on the rocky substrate in the lower intertidal zone using a hammer and anchor bolts. These settling plates were replaced every 1-2 months. Two Ulva species were recruited continuously for 3-4 months each year. U. pertusa was recruited during summer-autumn, whereas U. linza was recruited during winter-early spring or spring-early summer. However, U. pertusa dominated in the monitoring plots compared with the experimental period, with the exception of 2 months (February and March 2000). These results indicated that U. pertusa may be the main contributor to green tides along the intertidal rocky shores. The two Ulva species showed a positive relationship between density and biomass. This suggests that the physical removal of Ulva masses should be conducted during the early growing season. I hope this study provides valuable information for determining management policies for green tides on intertidal rocky shores.

  12. Climate and recruitment of rocky shore intertidal invertebrates in the eastern North Atlantic.

    PubMed

    Broitman, Bernardo R; Mieszkowska, Nova; Helmuth, Brian; Blanchette, Carol A

    2008-11-01

    Studies of the impacts of climate and climate change on biological systems often attempt to correlate ecological responses with basin-scale indices such as the North Atlantic Oscillation (NAO). However, such correlations, while useful for detecting long-term trends, are unable to provide a mechanism linking the physical environment and ecological processes. Here we evaluate the effects of the NAO on recruitment variability of rocky intertidal invertebrates in the North Atlantic examining two possible climate-related pathways. Using a highly conservative test we interpret associations with the NAO integrated over a season (three months) as an indicator of atmospheric effects on newly settled recruits (NAO3), and the effects of the NAO integrated over six months (NAO6) as an indicator of changes in ocean circulation affecting patterns of larval transport. Through an extensive literature survey we found 13 time series, restricted to southwest Ireland and Britain and comprising five species, that could be used for statistical analysis. Significant correlations with NAO3, our proxy for atmospheric effects, were observed in the south-central domain of our study region (southwest Ireland and south England). Significant correlations with NAO6, the proxy for ocean circulation effects, were detected on southwest Ireland. The associations were detected for three (two barnacles and a topshell) at two sites. These results suggest that the NAO can have effects on the recruitment of intertidal invertebrates through different pathways linked to climate and be distributed heterogeneously in space. Based on previous evidence and the sign and geographic location of significant correlations, we suggest that winter NAO effects are likely to occur as a result of effects on the survival of early life stages settling during spring or through changes in phenology. Our results argue that a combination of modeling and synthesis can be used to generate hypotheses regarding the effects of

  13. Context-dependent functional dispersion across similar ranges of trait space covered by intertidal rocky shore communities.

    PubMed

    Valdivia, Nelson; Segovia-Rivera, Viviana; Fica, Eliseo; Bonta, César C; Aguilera, Moisés A; Broitman, Bernardo R

    2017-03-01

    Functional diversity is intimately linked with community assembly processes, but its large-scale patterns of variation are often not well understood. Here, we investigated the spatiotemporal changes in multiple trait dimensions ("trait space") along vertical intertidal environmental stress gradients and across a landscape scale. We predicted that the range of the trait space covered by local assemblages (i.e., functional richness) and the dispersion in trait abundances (i.e., functional dispersion) should increase from high- to low-intertidal elevations, due to the decreasing influence of environmental filtering. The abundance of macrobenthic algae and invertebrates was estimated at four rocky shores spanning ca. 200 km of the coast over a 36-month period. Functional richness and dispersion were contrasted against matrix-swap models to remove any confounding effect of species richness on functional diversity. Random-slope models showed that functional richness and dispersion significantly increased from high- to low-intertidal heights, demonstrating that under harsh environmental conditions, the assemblages comprised similar abundances of functionally similar species (i.e., trait convergence), while that under milder conditions, the assemblages encompassed differing abundances of functionally dissimilar species (i.e., trait divergence). According to the Akaike information criteria, the relationship between local environmental stress and functional richness was persistent across sites and sampling times, while functional dispersion varied significantly. Environmental filtering therefore has persistent effects on the range of trait space covered by these assemblages, but context-dependent effects on the abundances of trait combinations within such range. Our results further suggest that natural and/or anthropogenic factors might have significant effects on the relative abundance of functional traits, despite that no trait addition or extinction is detected.

  14. The study of vertical zonation on rocky intertidal shores--a historical perspective.

    PubMed

    Benson, Keith R

    2002-08-01

    Intertidal zonation, observed from earliest studies of the marine littoral zone, was first studied in the U.S. by ecologists with a botanical orientation. Using the physiological methods favored by Cowles, Clements, and Shelford, these early studies sought causal and deterministic explanations. By the 1930s, the limitations of these studies became apparent and ecologists returned to more descriptive approaches. With the creation of year round research laboratories on the west coast, ecologists soon shed the botanical orientation and began to adopt more stochastic and non-deterministic approaches to intertidal ecology, approaches that still characterize the research tradition.

  15. Food web of the intertidal rocky shore of the west Portuguese coast - Determined by stable isotope analysis.

    PubMed

    Vinagre, Catarina; Mendonça, Vanessa; Narciso, Luís; Madeira, Carolina

    2015-09-01

    The characterization of food web structure, energy pathways and trophic linkages is essential for the understanding of ecosystem functioning. Isotopic analysis was performed on food web components of the rocky intertidal ecosystem in four sites along the Portuguese west coast. The aim was to 1) determine the general food web structure, 2) estimate the trophic level of the dominant organisms and 3) track the incorporation of organic carbon of different origins in the diet of the top consumers. In this food web, fish are top consumers, followed by shrimp. Anemones and gastropods are intermediate consumers, while bivalves and zooplankton are primary consumers. Macroalgae Bifurcaria bifurcata, Ulva lactuca, Fucus vesiculosus, Codium sp. and phytoplankton are the dominant producers. Two energy pathways were identified, pelagic and benthic. Reliance on the benthic energy pathway was high for many of the consumers but not as high as previously observed in subtidal coastal food webs. The maximum TL was 3.3, which is indicative of a relatively short food web. It is argued that the diet of top consumers relies directly on low levels of the food web to a considerable extent, instead of on intermediate levels, which shortens the trophic length of the food web.

  16. Spatial variability in community composition on a granite breakwater versus natural rocky shores: lack of microhabitats suppresses intertidal biodiversity.

    PubMed

    Aguilera, Moisés A; Broitman, Bernardo R; Thiel, Martin

    2014-10-15

    Strong differences have been observed between the assemblages on artificial reefs and on natural hard-bottom habitats worldwide, but little is known about the mechanisms that cause contrasting biodiversity patterns. We examined the influence of spatial attributes in relation to both biogenic and topographic microhabitats, in the distribution and composition of intertidal species on both artificial and natural reefs. We found higher small-scale spatial heterogeneity on the natural reef compared with the study breakwater. Species richness and diversity were associated with a higher availability of crevices, rock pools and mussels in natural habitats. Spatial distribution of certain grazers corresponded well with the spatial structure of microhabitats. In contrast, the lack of microhabitats on the breakwater resulted in the absence of several grazers reflected in lower species richness. Biogenic and topographic microhabitats can have interactive effects providing niche opportunities for multiple species, explaining differences in species diversity between artificial versus natural reefs.

  17. Effects of recreational activities on Patagonian rocky shores.

    PubMed

    Mendez, María M; Livore, Juan P; Calcagno, Javier A; Bigatti, Gregorio

    2017-09-01

    Recreational activities can be an important source of anthropogenic disturbance in intertidal benthic assemblages. On rocky shores, activities such as trampling, snorkeling and the handling of organisms may have a negative effect on benthic communities by modifying the abundance and distribution of key species. Here, we describe and quantify impacts due to recreational activities on benthic communities on a Patagonian rocky shore by investigating their resilience to two types of human disturbance: vehicle traffic and human trampling. To evaluate the effects of these activities, we carried out an observational study and assessed post-disturbance assemblage recovery. The rocky shores is most intensively visited during summer, and marked differences in the distribution and abundance of benthic species among disturbed and control plots were found after this season. The benthic community on the high intertidal was weakly impacted by disturbance generated due to vehicle traffic in summer (one vehicle on a single occasion, pulse disturbance); which did not affect the cover of dominant species. This suggests that the high intertidal community would be resistant to the passage of one vehicle on a single occasion. The effects of continuous trampling (press disturbance) were drastic and the community of the mid intertidal level did not recover before the next recreational season. Mid intertidal communities exposed to press disturbances require more than one tourist season of human inactivity to recover from anthropogenic effects, suggesting that resilience mechanisms in this community operate at broad timescales. Our findings highlight the need to establish and implement management actions that contemplate the nature of the disturbance and intertidal level to minimize habitat degradation due to human recreational activities. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Polychaetes and oligochaetes associated with intertidal rocky shores in a semi-enclosed industrial and urban embayment, with the description of two new species

    NASA Astrophysics Data System (ADS)

    Parapar, Julio; Martínez-Ansemil, Enrique; Caramelo, Carlos; Collado, Rut; Schmelz, Rüdiger

    2009-12-01

    The species composition and relative abundance of the annelid benthic macrofauna (Polychaeta and Oligochaeta) inhabiting the rocky intertidal zone of the ria of Ferrol (Galicia, NW Spain) were studied during field collections, from 2000 to 2002. A total of 14,619 specimens (11,585 polychaetes belonging to 76 species and 24 families and 3,034 oligochaetes belonging to 18 species and two families) were collected from 98 quantitative samples taken from 13 sampling sites. The general spatial distribution of the annelid fauna reflects an increase of the diversity from the inner to the outer part of the ria. The general patterns found in the annelid composition suggest that the assemblages were dominated by oligochaetes in the inner sheltered sampling sites and polychaetes in the outer more exposed sites. Several faunistical and taxonomical remarks on selected species are presented. Two new species of oligochaetes are described: Coralliodrilus artabrensis sp. n. and Pirodrilus fungithecatus sp. n. (Naididae, Phallodrilinae). A new biological index, based on the oligochaete/polychaete ratio (O/P), is proposed as tool to evaluate environmental quality and to monitor future changes in the environment.

  19. The influence of coastal upwelling on the functional structure of rocky intertidal communities.

    PubMed

    Bosman, A L; Hockey, P A R; Siegfried, W R

    1987-05-01

    Relationships between organisms at all trophic levels are influenced by the primary productivity of the ecosystem, and factors which enhance rates of primary production may modify trophic relationships and community structure. Nutrient enrichment of intertidal and nearshore waters leads to enhanced production by intertidal algae, and it was hypothesized that where rocky shores are washed by nutrient-rich upwelled waters, the intertidal communities should show a characteristic functional structure, based on the effects of enhanced primary production. Study sites were chosen on rocky shores in southern Africa, central Chile and the Canary Islands, in areas with and without coastal upwelling, and mid-shore community structure at these sites was analysed in terms of the abundance of certain functional guilds of organisms.It was found that algal cover and the biomass of herbivorous limpets supported per unit area on rocky shores were significantly greater in regions of coastal upwelling than in regions where upwelling did not occur. Ground cover by sessile filter-feeding organisms was significantly greater on shores in non-upwelled areas. However, correspondence analysis showed no functional aspect of intertidal community structure that was characteristic of coasts washed by upwelled waters. Primary reasons for this are probably the large variations in the nature of nutrient enrichment that accompanies upwelling, and in the nutrient status of non-upwelled areas. Other factors are man's exploitation of intertidal organisms and differences in the genetic origins of the intertidal species involved.

  20. Causes and consequences of thermal tolerance limits in rocky intertidal porcelain crabs, genus petrolisthes.

    PubMed

    Stillman, Jonathon H

    2002-08-01

    Vertical zonation of intertidal organisms, from the shallow subtidal to the supralittoral zones, is a ubiquitous feature of temperate and tropical rocky shores. Organisms that live higher on the shore experience larger daily and seasonal fluctuations in microhabitat conditions, due to their greater exposure to terrestrial conditions during emersion. Comparative analyses of the adaptive linkage between physiological tolerance limits and vertical distribution are the most powerful when the study species are closely related and occur in discrete vertical zones throughout the intertidal range. Here, I summarize work on the physiological tolerance limits of rocky intertidal zone porcelain crab species of the genus Petrolisthes to emersion-related heat stress. In the eastern Pacific, Petrolisthes species live throughout temperate and tropical regions, and are found in discrete vertical intertidal zones in each region. Whole organism thermal tolerance limits of Petrolisthes species, and thermal limits of heart and nerve function reflect microhabitat conditions. Species living higher in the intertidal zone are more eurythermal than low-intertidal congeners, tropical species have the highest thermal limits, and the differences in thermal tolerance between low- and high-intertidal species is greatest for temperate crabs. Acclimation of thermal limits of high-intertidal species is restricted as compared to low-intertidal species. Thus, because thermal limits of high-intertidal species are near current habitat temperature maxima, global warming could most strongly impact intertidal species.

  1. Field Trip to a Rocky Shore.

    ERIC Educational Resources Information Center

    Maine Univ., Orono. Cooperative Extension Service.

    Field trip activities designed for use on Maine's coast are provided, with brief definitions of the major physical zones to be found in this area. An introduction to the study of zonation of plants and animals living on the rocky shore is presented along with a list of the materials needed and the procedures to be followed when making a study of…

  2. Field Trip to a Rocky Shore.

    ERIC Educational Resources Information Center

    Maine Univ., Orono. Cooperative Extension Service.

    Field trip activities designed for use on Maine's coast are provided, with brief definitions of the major physical zones to be found in this area. An introduction to the study of zonation of plants and animals living on the rocky shore is presented along with a list of the materials needed and the procedures to be followed when making a study of…

  3. Visitor impact on rocky shore communities of Qeshm Island, the Persian Gulf, Iran.

    PubMed

    Pour, Fatemeh Aghajan; Shokri, Mohammad Reza; Abtahi, Behrooz

    2013-02-01

    The influence of visitors on macroinvertebrates of rocky intertidal shores was investigated in southern coasts of the Qeshm Island, the Persian Gulf, Iran. Qeshm Island located at the Strait of Hormuz, with an area of 1,491 km(2), is the largest island in the region. This island consists of a number of important natural habitat types including creeks, mangroves, corals, and sandy, muddy, and rocky shores that accommodate diverse marine flora and fauna communities. Two rocky shores were selected at the touristic beaches being visited regularly, and further two control locations selected at pristine shores. Intertidal macroinvertebrates were collected from six microhabitats including rock platforms, cobbles, boulders, crevices, sea walls, and rock pools during two different periods representing high and low tourist seasons. Species richness, density, and assemblage structure in heavily visited shores were compared with that of control locations. Striped barnacles (Balanus amphitrite) were present on platforms of all locations, thus the changes in their size were used as the obvious contrast associated with visitor's impact. A total of 70 macroinvertebrate species from 11 phyla were recorded. Significant differences were detected in taxonomic richness, density, and assemblage structure of macroinvertebrates between heavily visited and pristine shores, suggesting that macroinvertebrates were adversely affected by visitors' impact at heavily visited shores. The test of changes in species richness, density, and assemblage structure from high to low seasons yielded mixed results. The significant changes in density and assemblage structure from high to low seasons were only observed in one heavily visited shore. A significant reduction in size of striped barnacles was observed only in one heavily visited shore. The opportunistic or fugitive species (e.g., small macroalgae and barnacles) were dominant macroinvertebrates on heavily visited shores indicating early succession

  4. Distribution patterns of the peracarid crustaceans associated with the alga Corallina elongata along the intertidal rocky shores of the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Izquierdo, D.; Guerra-García, J. M.

    2011-06-01

    Spatial patterns of intertidal peracarids, associated with the alga Corallina elongata, were studied along the whole Iberian Peninsula. A total of 28,215 specimens were collected, comprising 78 different species (57 amphipods, 16 isopods, 4 tanaids and 1 cumacean), most of them with Atlantic-Mediterranean distribution (60%) and only 9% of Mediterranean endemics. Gammarids were dominant in abundance and number of species, representing more than 70% of the total peracarids. The most common species collected during the present study were the caprellid Caprella penantis, the gammarids Hyale schmidti, Hyale stebbingi, Jassa cf. falcata and Stenothoe monoculoides, the isopod Ischyromene lacazei and the tanaid Tanais dulongii. Caprellids and tanaidaceans presented their highest populations in the stations of the Strait of Gibraltar, whereas isopods were more abundant in Atlantic stations. Univariate analyses did not reflected differences in number of species, abundance and Shannon-Weaver diversity between Mediterranean and Atlantic. However, cluster analyses and Whittaker index, as measure of ß-diversity, showed a different species composition between Mediterranean and Atlantic and a replacement of species along the coast, especially at the Strait of Gibraltar. The turnover mainly affected species of the same genera, probably related with sympatric speciation. CCA and BIO-ENV analyses showed high correlations between environmental measures (especially conductivity) and peracarid distribution. Mediterranean species tolerated higher values of conductivity and temperature, while Atlantic species were associated with stations characterized by higher oxygen concentrations.

  5. Whole-Community Facilitation Regulates Biodiversity on Patagonian Rocky Shores

    PubMed Central

    Silliman, Brian R.; Bertness, Mark D.; Altieri, Andrew H.; Griffin, John N.; Bazterrica, M. Cielo; Hidalgo, Fernando J.; Crain, Caitlin M.; Reyna, Maria V.

    2011-01-01

    Background Understanding the factors that generate and maintain biodiversity is a central goal in ecology. While positive species interactions (i.e., facilitation) have historically been underemphasized in ecological research, they are increasingly recognized as playing important roles in the evolution and maintenance of biodiversity. Dominant habitat-forming species (foundation species) buffer environmental conditions and can therefore facilitate myriad associated species. Theory predicts that facilitation will be the dominant community-structuring force under harsh environmental conditions, where organisms depend on shelter for survival and predation is diminished. Wind-swept, arid Patagonian rocky shores are one of the most desiccating intertidal rocky shores ever studied, providing an opportunity to test this theory and elucidate the context-dependency of facilitation. Methodology/Principal Findings Surveys across 2100 km of southern Argentinean coastline and experimental manipulations both supported theoretical predictions, with 43 out of 46 species in the animal assemblage obligated to living within the matrices of mussels for protection from potentially lethal desiccation stress and predators having no detectable impact on diversity. Conclusions/Significance These results provide the first experimental support of long-standing theoretical predictions and reveal that in extreme climates, maintenance of whole-community diversity can be maintained by positive interactions that ameliorate physical stress. These findings have important conservation implications and emphasize that preserving foundation species should be a priority in remediating the biodiversity consequences of global climate change. PMID:22022356

  6. Effects of human trampling on a rocky shore fauna on the Sao Paulo coast, southeastern Brazil.

    PubMed

    Ferreira, M N; Rosso, S

    2009-11-01

    Increased tourist activity in coastal regions demands management strategies to reduce impacts on rocky shores. The highly populated coastal areas in southeastern Brazil are an example of degradation caused by development of industry and tourism. Among different shore impacts, trampling has been intensively studied, and may represent a significant source of stress for intertidal fauna. A randomised blocks design was applied to experimentally study the effects of two different trampling intensities on richness, diversity, density and biomass of the rocky shore fauna of Obuseiro beach, Guarujá, southeastern Brazil. Blocks were distributed in two portions of the intertidal zone, dominated respectively by Chthamalus bisinuatus (Cirripedia) and Isognomon bicolor (Bivalvia). Blocks were trampled over three months, simulating the vacation period in Brazil and were monitored for the following nine months. Results indicate that Chthamalus bisinuatus is vulnerable to trampling impacts. Richness, diversity and turn-over index tended to be higher in trampled plots four months after trampling ceased. In general, results agree with previous trampling studies, suggesting that even low intensities of trampling may cause some impact on intertidal communities. Management strategies should include isolation of sensitive areas, construction of boardwalks, visitor education and monitoring programmes. In Brazil, additional data obtained from experimental studies are necessary in order to achieve a better understanding of trampling impacts on rocky shore communities.

  7. Rocky intertidal zonation pattern in Antofagasta, chile: invasive species and shellfish gathering.

    PubMed

    Castilla, Juan Carlos; Manríquez, Patricio H; Delgado, Alejandro; Ortiz, Verónica; Jara, María Elisa; Varas, Manuel

    2014-01-01

    Biological invasions affecting rocky intertidal zonation patterns, yield information on species interactions. In the Bay of Antofagasta, northern Chile, the non-indigenous tunicate Pyura praeputialis, originally from Australia, has invaded (in the past century or so) and monopolized a major portion of the mid-intertidal rocky shore, displacing upshore the native mussel Perumytilus purpuratus. In Antofagasta the tunicate is subjected to intensive exploitation. Monitoring protocols show that in the past 10 years Antofagasta's tunicate population has experienced a drastic decline, affecting the intertidal zonation pattern. A 12.5 km of coastline, on the southern eastern shore of the Bay of Antofagasta, was studied. Eight sites were systematically (1993-1994) or sporadically (2003-2014) monitored for the seaward-shoreward expansion or reduction of the tunicate Pyura praeputialis, and native mussel and barnacle bands. A notable reduction in the mid-intertidal band of P. praeputialis and a seaward expansion of the mussel, Perumytilus purpuratus, and barnacle bands was observed. We suggest that the major cause for the decline in the tunicate is due to its intensive exploitation by rocky shore Pyura-gathers. The rate of extraction of tunicates by professional Pyura-gathers ranged between 256-740 tunicates hour-(1). Between 2009-2014 the density of professional Pyura-gather ranged between 0.5-4.5 km(-1) per low tide. Hence, 10 professional Pyura-gathers working 1 h for 10 low tides per month, during 6 months, will remove between 307-888 m(2) of tunicates. A drastic decline in tunicate recruitment was observed and several P. praeputialis ecosystems services have been lost. In Antofagasta, the continuous and intensive intertidal gathering of the invasive tunicate Pyura praeputialis, has caused a drastic reduction of its population modifying the zonation pattern. Thereby, native mussel Perumytilus purpuratus has regained its ecological center in the intertidal zone. We

  8. The subtidal morphology of microtidal shore platforms and its implication for wave dynamics on rocky coasts

    NASA Astrophysics Data System (ADS)

    Kennedy, David M.

    2016-09-01

    The subtidal portions of shore platforms are important geomorphic features as they can modify deep-water wave energy before it impacts the intertidal platform edge. In this study an integrated marine and terrestrial aerial LiDAR dataset is used to analyse the morphology of the subtidal portion of shore platforms. Semi-horizontal intertidal platforms on an 85 km along stretch of microtidal, open-ocean, rocky coast in Victoria, Australia are investigated and described quantitatively. Three distinct types of subtidal morphology occur; (i) a steep cliff with a mean slope of 8-18°, (ii) a gently sloping ramp with a mean slope of < 3°, and (iii) a subtidal terrace/reef. It is inferred that the type of subtidal morphology present on a platform will determine the relative impact of marine and subaerial processes in the intertidal and supratidal zones.

  9. Differences in Intertidal Microbial Assemblages on Urban Structures and Natural Rocky Reef

    PubMed Central

    Tan, Elisa L.-Y.; Mayer-Pinto, Mariana; Johnston, Emma L.; Dafforn, Katherine A.

    2015-01-01

    Global seascapes are increasingly modified to support high levels of human activity in the coastal zone. Modifications include the addition of defense structures and boating infrastructure, such as seawalls and marinas that replace natural habitats. Artificial structures support different macrofaunal communities to those found on natural rocky shores; however, little is known about differences in microbial community structure or function in urban seascapes. Understanding how artificial constructions in marine environments influence microbial communities is important as these assemblages contribute to many basic ecological processes. In this study, the bacterial communities of intertidal biofilms were compared between artificial structures (seawalls) and natural habitats (rocky shores) within Sydney Harbour. Plots were cleared on each type of habitat at eight locations. After 3 weeks the newly formed biofilm was sampled and the 16S rRNA gene sequenced using the Illumina Miseq platform. To account for differences in orientation and substrate material between seawalls and rocky shores that might have influenced our survey, we also deployed recruitment blocks next to the habitats at all locations for 3 weeks and then sampled and sequenced their microbial communities. Intertidal bacterial community structure sampled from plots differed between seawalls and rocky shores, but when substrate material, age and orientation were kept constant (with recruitment blocks) then bacterial communities were similar in composition and structure among habitats. This suggests that changes in bacterial communities on seawalls are not related to environmental differences between locations, but may be related to other intrinsic factors that differ between the habitats such as orientation, complexity, or predation. This is one of the first comparisons of intertidal microbial communities on natural and artificial surfaces and illustrates substantial ecological differences with potential

  10. Differences in Intertidal Microbial Assemblages on Urban Structures and Natural Rocky Reef.

    PubMed

    Tan, Elisa L-Y; Mayer-Pinto, Mariana; Johnston, Emma L; Dafforn, Katherine A

    2015-01-01

    Global seascapes are increasingly modified to support high levels of human activity in the coastal zone. Modifications include the addition of defense structures and boating infrastructure, such as seawalls and marinas that replace natural habitats. Artificial structures support different macrofaunal communities to those found on natural rocky shores; however, little is known about differences in microbial community structure or function in urban seascapes. Understanding how artificial constructions in marine environments influence microbial communities is important as these assemblages contribute to many basic ecological processes. In this study, the bacterial communities of intertidal biofilms were compared between artificial structures (seawalls) and natural habitats (rocky shores) within Sydney Harbour. Plots were cleared on each type of habitat at eight locations. After 3 weeks the newly formed biofilm was sampled and the 16S rRNA gene sequenced using the Illumina Miseq platform. To account for differences in orientation and substrate material between seawalls and rocky shores that might have influenced our survey, we also deployed recruitment blocks next to the habitats at all locations for 3 weeks and then sampled and sequenced their microbial communities. Intertidal bacterial community structure sampled from plots differed between seawalls and rocky shores, but when substrate material, age and orientation were kept constant (with recruitment blocks) then bacterial communities were similar in composition and structure among habitats. This suggests that changes in bacterial communities on seawalls are not related to environmental differences between locations, but may be related to other intrinsic factors that differ between the habitats such as orientation, complexity, or predation. This is one of the first comparisons of intertidal microbial communities on natural and artificial surfaces and illustrates substantial ecological differences with potential

  11. Restoring rocky intertidal communities: Lessons from a benthic macroalgal ecosystem engineer.

    PubMed

    Bellgrove, Alecia; McKenzie, Prudence F; Cameron, Hayley; Pocklington, Jacqueline B

    2017-04-15

    As coastal population growth increases globally, effective waste management practices are required to protect biodiversity. Water authorities are under increasing pressure to reduce the impact of sewage effluent discharged into the coastal environment and restore disturbed ecosystems. We review the role of benthic macroalgae as ecosystem engineers and focus particularly on the temperate Australasian fucoid Hormosira banksii as a case study for rocky intertidal restoration efforts. Research focussing on the roles of ecosystem engineers is lagging behind restoration research of ecosystem engineers. As such, management decisions are being made without a sound understanding of the ecology of ecosystem engineers. For successful restoration of rocky intertidal shores it is important that we assess the thresholds of engineering traits (discussed herein) and the environmental conditions under which they are important.

  12. Physiological ecology of rocky intertidal organisms: a synergy of concepts.

    PubMed

    Tomanek, Lars; Helmuth, Brian

    2002-08-01

    The rocky intertidal zone is among the most physically harsh environments on earth. Marine invertebrates and algae living in this habitat are alternatively pounded by waves and exposed to thermal extremes during low tide periods (Denny and Wethey, 2001). Additionally, they must deal with strong selective pressures related to predation and competition for space (Connell, 1961). As a result, the steep physical gradient and spatially condensed community has made the rocky intertidal zone an ideal "natural laboratory" to study the coupled role of physical and biological factors in determining the abundance and distribution of organisms in nature (Connell, 1961; Paine, 1966, 1994).

  13. Grazing effects of the periwinkle Echinolittorina peruviana at a central Peruvian high rocky intertidal

    NASA Astrophysics Data System (ADS)

    Hidalgo, Fernando J.; Firstater, Fausto N.; Fanjul, Eugenia; Bazterrica, M. Cielo; Lomovasky, Betina J.; Tarazona, Juan; Iribarne, Oscar O.

    2008-03-01

    Echinolittorina peruviana is the most common gastropod in the high intertidal zone of Peru, representing more than 80% of the individuals present at that zone. Experimental removal of snails was used to evaluate their effects on (a) abundance of epilithic biofilm, (b) barnacle recruitment, and (c) abundance of macroalgae under “normal” conditions of the El Niño Southern Oscillation (ENSO). Experiments were carried out from October 2005 to April 2007 at two intertidal levels of a semi-protected rocky shore of central Peru. Results demonstrated that E. peruviana is able to control biofilm abundance and barnacle recruitment at both heights investigated, with marked effects in the lower zone. Erect macroalgae ( Ulva spp. and Gelidium spp.) were less affected by grazing; but negative effects were observed on macroalgal crusts. Season and physical stress seem to play a more important role in the abundance of macroalgae in the high intertidal. Our results are similar to those reported elsewhere for high shore littorinids and represent baseline data to understand how the role of intertidal consumers will vary under the cold (La Niña) and warm (El Niño) phases of ENSO on these shores.

  14. Computing Risk to West Coast Intertidal Rocky Habitat due to ...

    EPA Pesticide Factsheets

    Compared to marshes, little information is available on the potential for rocky intertidal habitats to migrate upward in response to sea level rise (SLR). To address this gap, we utilized topobathy LiDAR digital elevation models (DEMs) downloaded from NOAA’s Digital Coast GIS data repository to estimate percent change in the area of rocky intertidal habitat in 10 cm increments with eustatic sea level rise. The analysis was conducted at the scale of the four Marine Ecoregions of the World (MEOW) ecoregions located along the continental west coast of the United States (CONUS). Environmental Sensitivity Index (ESI) map data were used to identify rocky shoreline. Such stretches of shoreline were extracted for each of the four ecoregions and buffered by 100 m to include the intertidal and evaluate the potential area for upland habitat migration. All available LiDAR topobathy DEMs from Digital Coast were extracted using the resulting polygons and two rasters were synthesized from the results, a 10 cm increment zone raster and a non-planimetric surface area raster for zonal summation. Current rocky intertidal non-planimetric surface areas for each ecoregion were computed between Mean Higher High Water (MHHW) and Mean Lower Low Water (MLLW) levels established from published datum sheets for tidal stations central to each MEOW ecoregion. Percent change in non-planimetric surface area for the same relative ranges were calculated in 10 cm incremental steps of eustatic S

  15. Computing Risk to West Coast Intertidal Rocky Habitat due to ...

    EPA Pesticide Factsheets

    Compared to marshes, little information is available on the potential for rocky intertidal habitats to migrate upward in response to sea level rise (SLR). To address this gap, we utilized topobathy LiDAR digital elevation models (DEMs) downloaded from NOAA’s Digital Coast GIS data repository to estimate percent change in the area of rocky intertidal habitat in 10 cm increments with eustatic sea level rise. The analysis was conducted at the scale of the four Marine Ecoregions of the World (MEOW) ecoregions located along the continental west coast of the United States (CONUS). Environmental Sensitivity Index (ESI) map data were used to identify rocky shoreline. Such stretches of shoreline were extracted for each of the four ecoregions and buffered by 100 m to include the intertidal and evaluate the potential area for upland habitat migration. All available LiDAR topobathy DEMs from Digital Coast were extracted using the resulting polygons and two rasters were synthesized from the results, a 10 cm increment zone raster and a non-planimetric surface area raster for zonal summation. Current rocky intertidal non-planimetric surface areas for each ecoregion were computed between Mean Higher High Water (MHHW) and Mean Lower Low Water (MLLW) levels established from published datum sheets for tidal stations central to each MEOW ecoregion. Percent change in non-planimetric surface area for the same relative ranges were calculated in 10 cm incremental steps of eustatic S

  16. Biofilm: A crucial factor affecting the settlement of seaweed on intertidal rocky surfaces

    NASA Astrophysics Data System (ADS)

    Park, Sang Rul; Kang, Yun Hee; Choi, Chang Geun

    2011-01-01

    We hypothesized that the presence of biofilm accelerated the settlement of dominant seaweed species and maintained high levels of species richness by regulating the blooming of particular species on an intertidal rocky shore. The coverage and species richness of macroalgae on sterile and cleared substrates (225 cm 2) were measured to investigate the effects of biofilm on the settlement of macroalgae in intertidal zones at Noryang, Songmoon, and Sangnam in Gawngyang Bay on the southern coast of the Korean peninsula. Green algae coverage on cleared substrates was significantly higher than that on sterile substrates at both Noryang and Songmoon during the study period. This suggests that the presence of biofilm enhances the settlement of green algae by providing various habitat structures and, consequently, may lead to serious 'green tide' events. However, the coverage of algae other than green algae and algal species richness on cleared substrates remained high at Sangnam during the experimental period. Biofilm facilitated the settlement of macroalgae and inhibited the blooming of specific algae by inducing inter-specific space competition. Therefore, biofilm plays an important role on seaweed assemblages on intertidal rocky shores by accelerating the settlement of seaweed.

  17. Rocky Intertidal Zonation Pattern in Antofagasta, Chile: Invasive Species and Shellfish Gathering

    PubMed Central

    Castilla, Juan Carlos; Manríquez, Patricio H.; Delgado, Alejandro; Ortiz, Verónica; Jara, María Elisa; Varas, Manuel

    2014-01-01

    Background Biological invasions affecting rocky intertidal zonation patterns, yield information on species interactions. In the Bay of Antofagasta, northern Chile, the non-indigenous tunicate Pyura praeputialis, originally from Australia, has invaded (in the past century or so) and monopolized a major portion of the mid-intertidal rocky shore, displacing upshore the native mussel Perumytilus purpuratus. In Antofagasta the tunicate is subjected to intensive exploitation. Monitoring protocols show that in the past 10 years Antofagasta's tunicate population has experienced a drastic decline, affecting the intertidal zonation pattern. Methodology/Principal Findings A 12.5 km of coastline, on the southern eastern shore of the Bay of Antofagasta, was studied. Eight sites were systematically (1993–1994) or sporadically (2003–2014) monitored for the seaward-shoreward expansion or reduction of the tunicate Pyura praeputialis, and native mussel and barnacle bands. A notable reduction in the mid-intertidal band of P. praeputialis and a seaward expansion of the mussel, Perumytilus purpuratus, and barnacle bands was observed. We suggest that the major cause for the decline in the tunicate is due to its intensive exploitation by rocky shore Pyura-gathers. The rate of extraction of tunicates by professional Pyura-gathers ranged between 256–740 tunicates hour−1. Between 2009–2014 the density of professional Pyura-gather ranged between 0.5–4.5 km−1 per low tide. Hence, 10 professional Pyura-gathers working 1 h for 10 low tides per month, during 6 months, will remove between 307–888 m2 of tunicates. A drastic decline in tunicate recruitment was observed and several P. praeputialis ecosystems services have been lost. Conclusion and Significance In Antofagasta, the continuous and intensive intertidal gathering of the invasive tunicate Pyura praeputialis, has caused a drastic reduction of its population modifying the zonation pattern. Thereby, native mussel Perumytilus

  18. Causations of phylogeographic barrier of some rocky shore species along the Chinese coastline.

    PubMed

    Wang, Jie; Tsang, Ling Ming; Dong, Yun-Wei

    2015-06-15

    Substrate, ocean current and freshwater discharge are recognized as important factors that control the larval dispersal and recruitment of intertidal species. Life history traits of individual species will determine the differential responses to these physical factors, and hence resulting in contrasting phylogeography across the same biogeographic barrier. To determine how these factors affect genetic structure of rocky shore species along the China coast, a comparative phylogeographic study of four intertidal and subtidal species was conducted using mitochondrial and nuclear DNA by combining new sequences from Siphonaria japonica with previously published sequences from three species (Cellana toreuma, Sargassum horneri and Atrina pectinata). Analysis of molecular variance and pairwise ΦST revealed significant genetic differences between the Yellow Sea (YS) and the other two marginal seas (East China Sea, ECS and South China Sea, SCS) for rocky-shore species (S. japonica, C. toreuma, S. horneri), but not for muddy-shore species Atrina pectinata. Demographic history analysis proved that the population size of all these four species were persistent though the Last Glacial Maximum (LGM, ~20 ka BP). Migration analysis revealed that gene flow differentiated northward and southward migration for these four species. However, the inferred direction of gene flow using alternatively mitochondrial or nuclear markers was contradictory in S. japonica. It is concluded that there is a phylogeographical break at the Yangtze River estuary for the rocky shore species and the causation of the barrier is mainly due to the unsuitable substratum and freshwater discharge. All four intertidal and subtidal species appear to have persisted through the LGM in China, indicating the lower impact of LGM on intertidal and subtidal species than generally anticipated. The imbalanced gene flow between YS and ESCS groups for these four species could be explained by historical refugia. The

  19. Food and feeding ecology of purple sandpipers Calidris maritima on rocky intertidal habitats (Helgoland, German Bight)

    NASA Astrophysics Data System (ADS)

    Dierschke, Volker

    On the island of Helgoland (German Bight) Purple Sandpipers Calidris maritima feed mainly in the intertidal of piers and rocky shores. The main prey species are Littorina saxatilis and Mytilus edulis, complemented by crustaceans, polychaetes, other molluscs and green algae. Beach habitats are used as alternative feeding sites during storms. Feeding sites seem to be selected according to rates of assimilated energy intake. The most profitable habitat (wrack beds on the high-tide line with kelp-fly larvae, 16.8 W) is used after arrival in October but is not available during winter. Because of high intake rates in rocky habitats (13.1 W on piers, 5.5 W on mussel beds), which allow short daily feeding times, and available alternative feeding sites during storms, Purple Sandpipers do not need to carry fat reserves in winter like other waders wintering in central and Western Europe. This, and the ever accessible food supply of epibenthic macrofauna on rocky shores, may enable Purple Sandpipers to winter further north than other wader species.

  20. Fidelity of rocky intertidal mollusks in subtidal death assemblages to their counterpart life assemblages: a case study in San Salvador Island, Bahamas.

    NASA Astrophysics Data System (ADS)

    García-Ramos, Diego A.

    2016-04-01

    Rocky shores preserved in the geological record were rarely reported until a couple of decades ago. Even today, most of the literature focuses on bioerosional features in these high-energy environments due to their higher fossilization potential relative to shell material. Hard parts of taxa adapted to intertidal rocky shores may be preserved as allochthonous material in death assemblages (DAs) formed in adjacent shallow subtidal habitats due to lateral mixing. To test if life assemblages (LAs) of rocky intertidal mollusks (RIM) are faithfully recorded in shallow subtidal DAs, two ~30 m long transects across a proximal-distal gradient were studied on San Salvador Island, Bahamas. These transects encompass a proximal ripple field which grades into a facies dominated by green algae, and a distal ripple field. A total of 22 bulk samples, representing 155 liters of sediment, were wet-sieved with a 2-mm mesh. The samples yielded 528 RIM shells representing 15 species. Unexpectedly, abundance and compositional similarity of RIM shells to counterpart LAs sharply peaks along a belt of lag deposits of coarse sands fringing proximal ripple fields, in transition to green algae communities. These results suggest that, although a substantial transport of intertidal shells takes place in shallow subtidal environments, the signal is diluted in background sediment composition even in close proximity to the shore (30 m), and significant concentrations (loosely packed) of RIM shells in subtidal DAs might be used as a proxy to pinpoint past rocky intertidal environments.

  1. Does life history predict past and current connectivity for rocky intertidal invertebrates across a marine biogeographic barrier?

    PubMed

    Ayre, D J; Minchinton, T E; Perrin, C

    2009-05-01

    The southeast Australian coast potentially includes a complex biogeographic barrier, largely lacking exposed rocky shore that may limit the dispersal of rocky intertidal taxa and contribute to the maintenance of two biogeographic regions. Surprisingly, within the 300-km barrier region, several species considered exposed rocky shore specialists occurred within sheltered sites. We analysed COI sequence variation for 10 rocky intertidal invertebrate species, with a range of life histories, to test the hypotheses that larval type and habitat specificity are strong predictors of gene flow between biogeographic regions. Our data revealed that the southeast corner of Australia includes a strong barrier to gene flow for six of eight species with planktonic larvae, and a coalescence analysis of sequence differentiation (IM model) suggests that a barrier has existed since the Pleistocene. In contrast, two direct developers were not affected by the barrier. Our comparative approach and data from earlier studies (reviewed here) do not support the hypothesis that larval type predicts gene flow across this barrier, instead we found that the ability to utilize sheltered habitat provides a clearer explanation of the phylogeographic break. Indeed, the species that displayed little or no evidence of a phylogeographic break across the barrier each displayed unexpectedly relaxed habitat specificity.

  2. Seasonal variation in utilization of biogenic microhabitats by littorinid snails on tropical rocky shores.

    PubMed

    Cartwright, Stephen R; Williams, Gray A

    2012-01-01

    Mobile species may actively seek refuge from stressful conditions in biogenic habitats on rocky shores. In Hong Kong, the upper intertidal zone is extremely stressful, especially in summer when organisms are emersed for long periods in hot desiccating conditions. As a result, many species migrate downshore between winter and summer to reduce these stressful conditions. The littorinids Echinolittorina malaccana and E. vidua, for example, are found on open rock surfaces high on the shore in winter but the majority migrate downshore in summer to the same tidal height as a common barnacle, Tetraclita japonica. In the laboratory, where environmental conditions could be controlled to approximate those occurring on the shore, we tested whether the downshore migration allowed littorinids to select barnacles as biogenic habitats to reduce stress and if this behaviour varied between seasons. In summer, littorinids demonstrated a strong active preference for the barnacles, which was not observed in the cool winter conditions, when animals were found on open rock surfaces even when barnacles were present. Littorinids, therefore, only actively select biogenic habitats during the summer in Hong Kong when they migrate downshore, suggesting that such habitats may play an important, temporal, role in mitigating environmental stress on tropical shores.

  3. Patterns of benthic assemblages invaded and non-invaded by Grateloupia turuturu across rocky intertidal habitats

    NASA Astrophysics Data System (ADS)

    Freitas, Cristiano; Araújo, Rita; Bertocci, Iacopo

    2016-09-01

    Intertidal benthic assemblages invaded and non-invaded by the introduced Asian red alga Grateloupia turuturu were compared at a rocky shore along the NW coast of Portugal. The structure of whole assemblages, the total richness of taxa and the abundance of individual taxa were examined as response variables in two different habitats (rock pools and emergent rock), two shore levels (low and mid intertidal) and two dates of sampling (June 2013 and June 2014). Invaded and non-invaded assemblages differed consistently across habitats and shore levels. Such differences were driven by 13 (with the green alga genus Ulva, the red alga Chondrus crispus and the mussel Mytilus galloprovincialis driving the total dissimilarity) out of the total 37 taxa identified. Individual taxa revealed idiosyncratic patterns, in several cases (C. crispus, M. galloprovincialis, articulated coralline algae of the genus Corallina and the crustose sporophyte of the red alga Mastocarpus stellatus) there were differences in the abundance of a taxon between invaded and non-invaded assemblages varying with levels of some other experimental factors. The total number of taxa was higher in invaded compared to non-invaded assemblages for each combination of habitat and shore level. Patterns of invasion by G. turuturu along the Portuguese continental coast were recently described in terms of its temporal and spatial distribution, but never examined in terms of differences between invaded and non-invaded assemblages. Such information is very limited for other geographic areas where this species is recorded out of its native range of distribution. Therefore, the present study provides a new contribution to the understanding of modifications of native assemblages associated with the invasion of G. turuturu, opening avenues of research aimed at specifically examining the factors and processes likely responsible for the invasion dynamics and success of this species.

  4. Human influences on trophic cascades along rocky shores

    USGS Publications Warehouse

    Lindberg, D.R.; Estes, J.A.; Warheit, K.I.

    1998-01-01

    A three-trophic-level interaction among American Black Oystercatchers (Haematopus bachmani), limpets (Lottia spp.), and erect fleshy algae in rocky intertidal communities of central and southern California was documented via manipulative and 'natural' experiments. Removal of the territorial limpet (Lottia gigantea) initially caused large increases in the percent cover of erect fleshy algae, followed by a more gradual increase in density of small limpets (Lottia spp.) and a decline in algal cover. Algal cover increased following the removal of small limpets at the sites from which L. gigantea had been removed earlier, thus demonstrating that the large and small limpets had similar inhibitory effects on plant populations. A comparison of sites with and without oyster-catchers showed that L. gigantea occupied substrate inclinations in proportion to their availability at sites where oystercatchers were rare, whereas the distribution of L. gigantea was skewed toward vertically inclined substrates where oystercatchers were common. Survival rates of limpets translocated to horizontal and vertical substrates were similar in sites lacking oystercatcher predation, but were much lower on horizontal substrates where oystercatchers were common. Our results are consistent with those from several prior studies in demonstrating that shorelines frequented by humans typically lack oystercatchers. Humans also exploit L. gigantea and reduce populations to low densities of small individuals. These findings may explain why the midlittoral zone of rocky intertidal communities in western North America are so often dominated by high population densities of small limpets.

  5. Biogeographical Boundaries, Functional Group Structure and Diversity of Rocky Shore Communities along the Argentinean Coast

    PubMed Central

    Wieters, Evie A.; McQuaid, Christopher; Palomo, Gabriela; Pappalardo, Paula; Navarrete, Sergio A.

    2012-01-01

    We investigate the extent to which functional structure and spatial variability of intertidal communities coincide with major biogeographical boundaries, areas where extensive compositional changes in the biota are observed over a limited geographic extension. We then investigate whether spatial variation in the biomass of functional groups, over geographic (10′s km) and local (10′s m) scales, could be associated to species diversity within and among these groups. Functional community structure expressed as abundance (density, cover and biomass) and composition of major functional groups was quantified through field surveys at 20 rocky intertidal shores spanning six degrees of latitude along the southwest Atlantic coast of Argentina and extending across the boundaries between the Argentinean and Magellanic Provinces. Patterns of abundance of individual functional groups were not uniformly matched with biogeographical regions. Only ephemeral algae showed an abrupt geographical discontinuity coincident with changes in biogeographic boundaries, and this was limited to the mid intertidal zone. We identified 3–4 main ‘groups’ of sites in terms of the total and relative abundance of the major functional groups, but these did not coincide with biogeographical boundaries, nor did they follow latitudinal arrangement. Thus, processes that determine the functional structure of these intertidal communities are insensitive to biogeographical boundaries. Over both geographical and local spatial scales, and for most functional groups and tidal levels, increases in species richness within the functional group was significantly associated to increased total biomass and reduced spatial variability of the group. These results suggest that species belonging to the same functional group are sufficiently uncorrelated over space (i.e. metres and site-to-site ) to stabilize patterns of biomass variability and, in this manner, provide a buffer, or “insurance”, against spatial

  6. Biogeographical boundaries, functional group structure and diversity of Rocky Shore communities along the Argentinean coast.

    PubMed

    Wieters, Evie A; McQuaid, Christopher; Palomo, Gabriela; Pappalardo, Paula; Navarrete, Sergio A

    2012-01-01

    We investigate the extent to which functional structure and spatial variability of intertidal communities coincide with major biogeographical boundaries, areas where extensive compositional changes in the biota are observed over a limited geographic extension. We then investigate whether spatial variation in the biomass of functional groups, over geographic (10's km) and local (10's m) scales, could be associated to species diversity within and among these groups. Functional community structure expressed as abundance (density, cover and biomass) and composition of major functional groups was quantified through field surveys at 20 rocky intertidal shores spanning six degrees of latitude along the southwest Atlantic coast of Argentina and extending across the boundaries between the Argentinean and Magellanic Provinces. Patterns of abundance of individual functional groups were not uniformly matched with biogeographical regions. Only ephemeral algae showed an abrupt geographical discontinuity coincident with changes in biogeographic boundaries, and this was limited to the mid intertidal zone. We identified 3-4 main 'groups' of sites in terms of the total and relative abundance of the major functional groups, but these did not coincide with biogeographical boundaries, nor did they follow latitudinal arrangement. Thus, processes that determine the functional structure of these intertidal communities are insensitive to biogeographical boundaries. Over both geographical and local spatial scales, and for most functional groups and tidal levels, increases in species richness within the functional group was significantly associated to increased total biomass and reduced spatial variability of the group. These results suggest that species belonging to the same functional group are sufficiently uncorrelated over space (i.e. metres and site-to-site ) to stabilize patterns of biomass variability and, in this manner, provide a buffer, or "insurance", against spatial variability

  7. Large-Scale Spatial Distribution Patterns of Gastropod Assemblages in Rocky Shores

    PubMed Central

    Miloslavich, Patricia; Cruz-Motta, Juan José; Klein, Eduardo; Iken, Katrin; Weinberger, Vanessa; Konar, Brenda; Trott, Tom; Pohle, Gerhard; Bigatti, Gregorio; Benedetti-Cecchi, Lisandro; Shirayama, Yoshihisa; Mead, Angela; Palomo, Gabriela; Ortiz, Manuel; Gobin, Judith; Sardi, Adriana; Díaz, Juan Manuel; Knowlton, Ann; Wong, Melisa; Peralta, Ana C.

    2013-01-01

    Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1) describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2) identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3) identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME) following the NaGISA (Natural Geography in Shore Areas) standard protocol (www.nagisa.coml.org). A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2%) appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs) followed by the Trochidae and the Columbellidae (6 LMEs). In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska). No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05). Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages. PMID

  8. Large-scale spatial distribution patterns of gastropod assemblages in rocky shores.

    PubMed

    Miloslavich, Patricia; Cruz-Motta, Juan José; Klein, Eduardo; Iken, Katrin; Weinberger, Vanessa; Konar, Brenda; Trott, Tom; Pohle, Gerhard; Bigatti, Gregorio; Benedetti-Cecchi, Lisandro; Shirayama, Yoshihisa; Mead, Angela; Palomo, Gabriela; Ortiz, Manuel; Gobin, Judith; Sardi, Adriana; Díaz, Juan Manuel; Knowlton, Ann; Wong, Melisa; Peralta, Ana C

    2013-01-01

    Gastropod assemblages from nearshore rocky habitats were studied over large spatial scales to (1) describe broad-scale patterns in assemblage composition, including patterns by feeding modes, (2) identify latitudinal pattern of biodiversity, i.e., richness and abundance of gastropods and/or regional hotspots, and (3) identify potential environmental and anthropogenic drivers of these assemblages. Gastropods were sampled from 45 sites distributed within 12 Large Marine Ecosystem regions (LME) following the NaGISA (Natural Geography in Shore Areas) standard protocol (www.nagisa.coml.org). A total of 393 gastropod taxa from 87 families were collected. Eight of these families (9.2%) appeared in four or more different LMEs. Among these, the Littorinidae was the most widely distributed (8 LMEs) followed by the Trochidae and the Columbellidae (6 LMEs). In all regions, assemblages were dominated by few species, the most diverse and abundant of which were herbivores. No latitudinal gradients were evident in relation to species richness or densities among sampling sites. Highest diversity was found in the Mediterranean and in the Gulf of Alaska, while highest densities were found at different latitudes and represented by few species within one genus (e.g. Afrolittorina in the Agulhas Current, Littorina in the Scotian Shelf, and Lacuna in the Gulf of Alaska). No significant correlation was found between species composition and environmental variables (r≤0.355, p>0.05). Contributing variables to this low correlation included invasive species, inorganic pollution, SST anomalies, and chlorophyll-a anomalies. Despite data limitations in this study which restrict conclusions in a global context, this work represents the first effort to sample gastropod biodiversity on rocky shores using a standardized protocol across a wide scale. Our results will generate more work to build global databases allowing for large-scale diversity comparisons of rocky intertidal assemblages.

  9. Are seagrass beds indicators of anthropogenic nutrient stress in the rocky intertidal?

    PubMed

    Honig, Susanna E; Mahoney, Brenna; Glanz, Jess S; Hughes, Brent B

    2017-01-15

    It is well established that anthropogenic nutrient inputs harm estuarine seagrasses, but the influence of nutrients in rocky intertidal ecosystems is less clear. In this study, we investigated the effect of anthropogenic nutrient loading on Phyllospadix spp., a rocky intertidal seagrass, at local and regional scales. At sites along California, Washington, and Oregon, we demonstrated a significant, negative correlation of urban development and Phyllospadix bed thickness. These results were echoed locally along an urban gradient on the central California coast, where Phyllospadix shoot δ(15)N was negatively associated with Phyllospadix bed thickness, and experimentally, where nutrient additions in mesocosms reduced Phyllospadix shoot formation and increased epiphytic cover on Phyllospadix shoots. These findings provide evidence that coastal development can threaten rocky intertidal seagrasses through increased epiphytism. Considering that seagrasses provide vital ecosystem services, mitigating eutrophication and other factors associated with development in the rocky intertidal coastal zone should be a management priority. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Initial effects of a moderate-sized oil spill on benthic assemblage structure of a subtropical rocky shore

    NASA Astrophysics Data System (ADS)

    Stevens, Tim; Boden, Anna; Arthur, James Michael; Schlacher, Thomas Alfred; Rissik, David; Atkinson, Sally

    2012-08-01

    The environmental impacts of very large oil spills are well documented across a range of settings. However, there is a dearth of information about the immediate effects, and post-spill trajectories, of small to moderate (<1000 t) oil spills on intertidal biota. The published studies are from very different environments, and are contradictory in terms of the severity of initial impacts. This study reports on the effects of a 270 t spill of bunker fuel oil on 11 March 2009, approximately 13 km east of Cape Moreton, eastern Australia. We examined the initial effects of this moderate sized spill on the rocky shore biota of Cape Moreton, and quantified the trajectory of oil removal and change in assemblage structure over the next 5 months. Compared to adjacent reference sites, the initial effects were very marked, especially on the upper shore. Oiling was heavier and more persistent on the upper shore than the mid-shore, and biological effects were more pronounced higher in the intertidal. At both levels, however, there was little evidence of recovery up to 5 months after oiling, and visible oil residues were still apparent. The effect size was larger than previously reported for spills of this magnitude, comparable to that of larger spills, although over a smaller stretch of coastline.

  11. Coastal oceanography sets the pace of rocky intertidal community dynamics.

    PubMed

    Menge, B A; Lubchenco, J; Bracken, M E S; Chan, F; Foley, M M; Freidenburg, T L; Gaines, S D; Hudson, G; Krenz, C; Leslie, H; Menge, D N L; Russell, R; Webster, M S

    2003-10-14

    The structure of ecological communities reflects a tension among forces that alter populations. Marine ecologists previously emphasized control by locally operating forces (predation, competition, and disturbance), but newer studies suggest that inputs from large-scale oceanographically modulated subsidies (nutrients, particulates, and propagules) can strongly influence community structure and dynamics. On New Zealand rocky shores, the magnitude of such subsidies differs profoundly between contrasting oceanographic regimes. Community structure, and particularly the pace of community dynamics, differ dramatically between intermittent upwelling regimes compared with relatively persistent down-welling regimes. We suggest that subsidy rates are a key determinant of the intensity of species interactions, and thus of structure in marine systems, and perhaps also nonmarine communities.

  12. Colonisation processes and the role of coralline algae in rocky shore community dynamics

    NASA Astrophysics Data System (ADS)

    Asnaghi, Valentina; Thrush, Simon F.; Hewitt, Judi E.; Mangialajo, Luisa; Cattaneo-Vietti, Riccardo; Chiantore, Mariachiara

    2015-01-01

    Recovery from disturbance is an important attribute of community dynamics. Temperate rocky shores will experience increases in both the type and intensity of impacts under future expected global change. To gauge the community response to these potential changes in the disturbance regime it is important to assess space occupancy and the temporal dynamics of key species over the recovery process. We experimentally disturbed replicated 1 m2 plots in the lower intertidal at 5 sites along the Ligurian rocky coast (North-western Mediterranean) and assessed early succession processes over 18 months. To identify colonisation processes and role of key species in affecting species richness on recovery trajectories, we monitored species composition at the cm-scale along fixed transects within the plots. Our results highlighted the role of a limited number of taxa in driving the recovery of species richness across sites, despite site variation in community composition. Settlement of new propagules and overgrowth were the principal pathway of space occupancy. We detected an important role for coralline algae, particularly the articulated Corallina elongata, in promoting the colonisation of a diverse range of colonists. The present study highlights the important role played by calcifying coralline macroalgae as substrate providers for later colonists, favouring recovery of biodiversity after disturbance. This pivotal role may be compromised in a future scenario of elevated cumulative disturbance, where ocean acidification will likely depress the role of coralline algae in recovery, leading to a general loss in biodiversity and community complexity.

  13. [Temporal comparison of the composition and zonation of rocky intertidal organisms at Cocos Island National Park, Pacific, Costa Rica].

    PubMed

    Sibaja-Cordero, Jeffrey A; Cortés, Jorge

    2010-12-01

    Several biological and physical factors change the rocky shore communities. The desiccation time and the tolerance of the intertidal species produce the vertical zonation. In many studies around the world, a temporal change in this zonation is presented.In Costa Rica, only studies that include temporal trends were carried out in Punta Mala and Montezuma, Pacific coast in 80's. The rocky intertidal of the Cocos Island National Park, Costa Rica were surveyed photographically. The Chatham bay was sampled in three expeditions (January 2007, October 2007 and April 2008). Photos corresponding to 25x25cm quadrats were taken with the goal to determine diversity and composition differences in rocky shore organisms between sampling dates. The Wafer bay was sampled in January and October 2007. The intertidal of Chatham consists of basaltic rock, while Wafer has basaltic and ignimbrite boulders. The main difference between sites were the higher algae cover (erect-frondose forms) and number of organism bands at Chatham bay. Temporal change was not found in the total cover of sessile fauna and autotrophs. The barnacle Tetraclita stalactifera, that occurs above the algal fringe (lower intertidal), was the invertebrate with the highest coverage. The mobile fauna biodiversity presented no significant trend between sampled months. However, the identity of species, their cover and their abundance showed a moderate temporal change. In October 2007, when the sea surface temperature was 23 degrees C the infralittoral zone had an increase in green algae cover. The red algae (crust and erect-frondose forms) were dominant in January and April. The pulmonate limpet, Siphonaria gigas and a bacterial biofilm at mid littoral showed a negative association. The snails of the high littoral and the supralittoral zone showed a temporal change in their abundance, but with contrasting patterns between sites. The temporal variation in the assemblages increased from the supralittoral to the

  14. Predation intensity in a rocky intertidal community : Relation between predator foraging activity and environmental harshness.

    PubMed

    Menge, Bruce A

    1978-01-01

    Knowledge of predation intensity and how and why it varies among communities appears to be a key to understanding of community regulation. Along the rocky shores of New England, predation intensity in the mid intertidal zone appears to be low with exposure to severe wave shock, low desiccation stress, and a sparse cover of canopy algae, and high at areas protected from waves, with high desiccation potential and a dense cover of algae. As a result, predators at exposed headlands have no controlling influence on community structure, while at protected sites, they exert a strong and controlling effect on community structure.Experimental-observational studies of the effects of wave shock and desiccation on survival, foraging range and activity of the primary predator in this community (Thais lapillus) indicate that: (1) wave shock is a continuous and actual source of mortality at exposed sites but is relatively unimportant at protected sites; (2) mortality rates from desiccation at protected sites are potentially high and greater than at exposed sites; however, (3) actual desiccation stress is greatly reduced at protected sites by a dense algal canopy; (4) mortality from desiccation is greater in the higher mid intertidal than in the lower mid intertidal. Comparisons of activity patterns of Thais from April through November (these snails are usually active from May to early October) at an exposed and a protected site suggest snails at the former site restrict their active feeding to crevices while those at the latter site forage throughout the habitat. Field experiments support this hypothesis. Hence, differences in predator effectiveness at exposed and protected communities are probably due in part to the influence of wave shock. Exposed areas receive frequent severe wave shock in all seasons, even summer. Thus, the risk of being swept off the shore for snails foraging away from the shelter of a crevice at such areas is apparently great and exerts a strong selective

  15. Temporal variation in the diversity and cover of sessile species in rocky intertidal communities affected by copper mine tailings in northern Chile.

    PubMed

    Fariña, J M; Castilla, J C

    2001-07-01

    Several coastal rocky shores in the northern Chile have been affected by the discharges of copper mine tailings. In spite of this, the temporal and spatial variation on the diversity and composition of their intertidal benthic communities has scarcely been studied. The objectives of the present study were to analyse and to compare quantitatively the temporal variation on the diversity, cover and composition of sessile species in rocky intertidal benthic communities of the northern Chilean coast, in relation to the presence of copper mine tailings. The results show that the drastic reduction on the sessile species diversity and the monopolization of the substrate exerted by the green algae Enteromorpha compressa, are common and permanent features of the intertidal rocky shores affected by copper mine tailings. Such spatial (between sites) and temporal (seasonal) variation of these changes has been associated with the relative concentrations of trace metals and inorganic particles of the mining wastes. Our results suggest that the mechanical effects of resuspended and settling tailings are a more likely cause.

  16. Predicting multi-scale relationships between geomorphology and bedrock geology of the rocky intertidal in Central and Northern California

    NASA Astrophysics Data System (ADS)

    Wheeler, A.; Aiello, I. W.

    2014-12-01

    Substratum geology is fundamental in shaping rocky shore morphology. Specific lithologies have various responses to wave action, tectonic features (e.g. fractures, faults) and sedimentary structures (e.g. bedding), creating distinctive weathering profiles. Along with local oceanography and climate forcing, different rock substrata create coastal morphologies that can vary distinctly between scales, ranging from mm to km. Despite the complexity of the system, qualitative observations show coastal areas with similar rock types share similar geomorphologies. Thus, a statistic relationship between geomorphology (expressed for instance by surface parameter rugosity) and geology can be envisaged. There are multiple benefits of finding such a relationship, as rocky intertidal geomorphology can be an important determinant in which organisms can settle, grow, and survive in near shore communities: allowing the prediction of geomorphologic parameters determining coastal ecology solely based on substratum geology, a crucial aspect in guiding the selection of marine protected areas. This study presents preliminary results of multi-scale geospatial surveys (cm to tens of meters) of rocky intertidal outcrops from Central to Northern California using a Terrestrial Laser Scanner. The outcrops investigated are representative of the most common igneous and sedimentary rocks in California (granitoids, conglomerates, sandstones, mudstones) and metamorphic units. The statistical analysis of the survey data support the hypothesis that surface properties can change significantly with changing scale, each rock type having distinct surface characteristics which are similar to comparable lithologies exposed at different locations. These scale dependent variations are controlled by different lithologic and structural characteristics of the outcrop in question. Our data also suggests lithologic variability within a rock unit could be a very significant factor in controlling changes in

  17. Contribution of environmental and spatial processes to rocky intertidal metacommunity structure

    NASA Astrophysics Data System (ADS)

    Okuda, Takehiro; Noda, Takashi; Yamamoto, Tomoko; Hori, Masakazu; Nakaoka, Masahiro

    2010-07-01

    It has been debated whether the community structure of an open system is more dependent on environmental processes associated with niche explanations, or on spatial processes related to dispersal. Their relative importance may differ among taxonomic groups with properties of the community such as ecological characteristics (e.g., dispersal ability and life history) and habitat type. We examined the relative importance of environmental and spatial processes on community structure for three taxonomic groups with different ecological characteristics (macroalgae, sessile invertebrates, and mobile molluscs) in rocky intertidal shores of Sanriku Coast, Japan. To evaluate the relative contribution of the two processes in determining community structure, we conducted variation partitioning to reveal the degree of variation of community structure (i.e., β-diversity) explained by environmental heterogeneity and spatial arrangement of local communities. The results of our analyses indicated that β-diversity was significantly explained by both environmental factors (macroalgae, 29.3% of community variation: sessile animal, 40.7%: mobile molluscs, 16.7%) and spatial factors (macroalgae, 19.9%: sessile animal, 3.6%: mobile molluscs, 6.6%) in all taxonomic groups. These results imply that although some taxonomic groups live in the same ecosystem, share common resources, and interact with each other, the mechanisms determining their community structure change depending on ecological characteristics such as dispersal ability and life history.

  18. Community effects following the deletion of a habitat-forming alga from rocky marine shores.

    PubMed

    Lilley, Stacie A; Schiel, David R

    2006-07-01

    Habitat-forming species increase spatial complexity and alter local environmental conditions, often facilitating a diversified assemblage of plants and animals. Removal of dominant species, therefore, can potentially lead to pronounced changes in diversity and community structure through a series of negative and positive interactions involving several components of the community. Here we test community responses to the deletion of the dominant, canopy-forming alga Hormosira banksii from the mid-intertidal zone of wave-protected rocky shores in southern New Zealand. This species was removed in winter (July) from three 3x3-m areas at each of two platforms (Kaikoura and Moeraki) on the east coast of the South Island. Initially, 59 taxa occurred in stands, but there were only four algal species with greater than 5% cover and three mobile invertebrate species with more than five individuals per 0.25 m(2). By 6 months after Hormosira removal, most fucoid and coralline algae had burned off, and there were blooms of ephemeral algae in the removal plots, but almost no change within controls. After 2 years, diversity declined by 44% relative to controls at Kaikoura and 36% at Moeraki, and the amount of bare space had increased by tenfold at Kaikoura and twofold at Moeraki. Few sessile or mobile invertebrates were present. Recruitment of Hormosira occurred after 14 months in the removal plots. At this time, a "press" disturbance was initiated into one half of each removal plot to test the effects of continued removal of Hormosira on diversity. Similar "end-points" of the control and "press" removal plots were not reached after 2 years, and even after Hormosira recruitment into the original "pulse" experiment there was little recovery of the community. In this mid-intertidal system with considerable thermal stress, and perhaps in others with few perennial species, diversity and community structure can critically depend on positive associations with a single dominant species.

  19. Dynamics of Late Cretaceous rocky shores (Rosario Formation) from Baja California, Mexico

    SciTech Connect

    Lescinsky, H.L. ); Ledesma-Vazquez, J. ); Johnson, M.E. )

    1991-04-01

    Two rocky-shore deposits are described at localities of Late Cretaceous age in Baja California, Mexico. The main locality, at Las Minas, is characterized by a carbonate matrix containing clasts derived from an underlying andesite flow. Basal boulders give way up section to smaller cobbles and silt, indicating a transgression. The biotas from the sites include encrusting forms (coralline algae, bryozoans, serpulids, ostreids, spondylids), pholadid bivalve borings, and several nestling and mobile taxa. The well exposed boulder zone contains clusters of nestling pectinids preserved in growth position. This is the first such observation from an ancient rocky shore. Echinoids also lived within the relatively stable boulder interstices. Rocky-shore biotas of Late Cretaceous age from around the world contain many elements in common, including large encrusting oysters, spondylids, serpulids, rhynconellid brachiopods, and echinoids. Other groups common to rocky shores today are found at only some Cretaceous localities (e.g., barnacles, trochid and cerithiid gastropods, limpets, chitons). More archaic taxa, such as crinoids and large inarticulate brachiopods, are rarely represented at the known Cretaceous localities. Reconstructions of the biotas of ancient rocky shores offer a new avenue for the study of evolution on hard substrates. As the number and quality of described rocky-shore localities increases, it will be possible to put into a broader context evolutionary trends derived strictly from hard-grounds or other hard-substrate types.

  20. Impacts of Climate-Change-Driven Sea Level Rise on Intertidal Rocky Reef Habitats Will Be Variable and Site Specific

    PubMed Central

    Thorner, Jaqueline; Kumar, Lalit; Smith, Stephen D. A.

    2014-01-01

    Intertidal rocky reefs are complex and rich ecosystems that are vulnerable to even the smallest fluctuations in sea level. We modelled habitat loss associated with sea level rise for intertidal rocky reefs using GIS, high-resolution digital imagery, and LIDAR technology at fine-scale resolution (0.1 m per pixel). We used projected sea levels of +0.3 m, +0.5 m and +1.0 m above current Mean Low Tide Level (0.4 m). Habitat loss and changes were analysed for each scenario for five headlands in the Solitary Islands Marine Park (SIMP), Australia. The results indicate that changes to habitat extent will be variable across different shores and will not necessarily result in net loss of area for some habitats. In addition, habitat modification will not follow a regular pattern over the projected sea levels. Two of the headlands included in the study currently have the maximum level of protection within the SIMP. However, these headlands are likely to lose much of the habitat known to support biodiverse assemblages and may not continue to be suitable sanctuaries into the future. The fine-scale approach taken in this study thus provides a protocol not only for modelling habitat modification but also for future proofing conservation measures under a scenario of changing sea levels. PMID:24465915

  1. Impacts of climate-change-driven sea level rise on intertidal rocky reef habitats will be variable and site specific.

    PubMed

    Thorner, Jaqueline; Kumar, Lalit; Smith, Stephen D A

    2014-01-01

    Intertidal rocky reefs are complex and rich ecosystems that are vulnerable to even the smallest fluctuations in sea level. We modelled habitat loss associated with sea level rise for intertidal rocky reefs using GIS, high-resolution digital imagery, and LIDAR technology at fine-scale resolution (0.1 m per pixel). We used projected sea levels of +0.3 m, +0.5 m and +1.0 m above current Mean Low Tide Level (0.4 m). Habitat loss and changes were analysed for each scenario for five headlands in the Solitary Islands Marine Park (SIMP), Australia. The results indicate that changes to habitat extent will be variable across different shores and will not necessarily result in net loss of area for some habitats. In addition, habitat modification will not follow a regular pattern over the projected sea levels. Two of the headlands included in the study currently have the maximum level of protection within the SIMP. However, these headlands are likely to lose much of the habitat known to support biodiverse assemblages and may not continue to be suitable sanctuaries into the future. The fine-scale approach taken in this study thus provides a protocol not only for modelling habitat modification but also for future proofing conservation measures under a scenario of changing sea levels.

  2. Patterns of Mass Mortality among Rocky Shore Invertebrates across 100 km of Northeastern Pacific Coastline

    PubMed Central

    Jurgens, Laura J.; Rogers-Bennett, Laura; Raimondi, Peter T.; Schiebelhut, Lauren M.; Dawson, Michael N.; Grosberg, Richard K.; Gaylord, Brian

    2015-01-01

    Mass mortalities in natural populations, particularly those that leave few survivors over large spatial areas, may cause long-term ecological perturbations. Yet mass mortalities may remain undocumented or poorly described due to challenges in responding rapidly to unforeseen events, scarcity of baseline data, and difficulties in quantifying rare or patchily distributed species, especially in remote or marine systems. Better chronicling the geographic pattern and intensity of mass mortalities is especially critical in the face of global changes predicted to alter regional disturbance regimes. Here, we couple replicated post-mortality surveys with preceding long-term surveys and historical data to describe a rapid and severe mass mortality of rocky shore invertebrates along the north-central California coast of the northeastern Pacific Ocean. In late August 2011, formerly abundant intertidal populations of the purple sea urchin (Strongylocentrotus purpuratus, a well-known ecosystem engineer), and the predatory six-armed sea star (Leptasterias sp.) were functionally extirpated from ~100 km of coastline. Other invertebrates, including the gumboot chiton (Cryptochiton stelleri) the ochre sea star (Pisaster ochraceus), and subtidal populations of purple sea urchins also exhibited elevated mortality. The pattern and extent of mortality suggest the potential for long-term population, community, and ecosystem consequences, recovery from which may depend on the different dispersal abilities of the affected species. PMID:26039349

  3. Patterns of Mass Mortality among Rocky Shore Invertebrates across 100 km of Northeastern Pacific Coastline.

    PubMed

    Jurgens, Laura J; Rogers-Bennett, Laura; Raimondi, Peter T; Schiebelhut, Lauren M; Dawson, Michael N; Grosberg, Richard K; Gaylord, Brian

    2015-01-01

    Mass mortalities in natural populations, particularly those that leave few survivors over large spatial areas, may cause long-term ecological perturbations. Yet mass mortalities may remain undocumented or poorly described due to challenges in responding rapidly to unforeseen events, scarcity of baseline data, and difficulties in quantifying rare or patchily distributed species, especially in remote or marine systems. Better chronicling the geographic pattern and intensity of mass mortalities is especially critical in the face of global changes predicted to alter regional disturbance regimes. Here, we couple replicated post-mortality surveys with preceding long-term surveys and historical data to describe a rapid and severe mass mortality of rocky shore invertebrates along the north-central California coast of the northeastern Pacific Ocean. In late August 2011, formerly abundant intertidal populations of the purple sea urchin (Strongylocentrotus purpuratus, a well-known ecosystem engineer), and the predatory six-armed sea star (Leptasterias sp.) were functionally extirpated from ~100 km of coastline. Other invertebrates, including the gumboot chiton (Cryptochiton stelleri) the ochre sea star (Pisaster ochraceus), and subtidal populations of purple sea urchins also exhibited elevated mortality. The pattern and extent of mortality suggest the potential for long-term population, community, and ecosystem consequences, recovery from which may depend on the different dispersal abilities of the affected species.

  4. Development of monitoring protocols to detect change in rocky intertidal communities of Glacier Bay National Park and Preserve

    USGS Publications Warehouse

    Irvine, Gail V.

    2010-01-01

    Glacier Bay National Park and Preserve in southeastern Alaska includes extensive coastlines representing a major proportion of all coastlines held by the National Park Service. The marine plants and invertebrates that occupy intertidal shores form highly productive communities that are ecologically important to a number of vertebrate and invertebrate consumers and that are vulnerable to human disturbances. To better understand these communities and their sensitivity, it is important to obtain information on species abundances over space and time. During field studies from 1997 to 2001, I investigated probability-based rocky intertidal monitoring designs that allow inference of results to similar habitat within the bay and that reduce bias. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope less than or equal to 30 degrees was rare. This finding illustrated the value of probability-based surveys and led to a shift in the target habitat type to more mixed rocky habitat with steeper slopes. Subsequently, I investigated different sampling methods and strategies for their relative power to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles -Balanomorpha, the mussel Mytilus trossulus and the rockweed Fucus distichus subsp. evanescens. I found that lower-intensity sampling of 25 randomly selected sites (= coarse-grained sampling) provided a greater ability to detect changes in the abundances of these taxa than did more intensive sampling of 6 sites (= fine-grained sampling). Because of its greater power, the coarse-grained sampling scheme was adopted in subsequent years. This report provides detailed analyses of the 4 years of data and evaluates the relative effect of different sampling attributes and management-set parameters on the ability of the sampling to detect changes in the abundances of these taxa. The intent was to provide managers with information

  5. Ecology of a key ecosystem engineer on hard coastal infrastructure and natural rocky shores.

    PubMed

    Martins, Gustavo M; Neto, Ana I; Cacabelos, Eva

    2016-02-01

    The numbers of hard coastal artificial structures is increasing worldwide and there is now cumulative evidence that they support assemblages that are less diverse than natural shores. Here we investigated patterns of distribution and demography of the native barnacle Chthamalus stellatus on hard coastal structures and on natural rocky shores. Barnacles were 35% less abundant on hard structures regardless of substratum type (concrete or basalt). On a subset of sites we found that temporal population stability, growth and mortality were similar on natural rocky shores and hard structures. In contrast, barnacles were significantly larger and recruited more onto natural rocky shores. These results emphasise the important role of recruitment in determining the abundance of a key space occupier on hard coastal structures. Experimental work building on these results may generate insights that can be used as guidelines for the management of urbanised coastal areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Community composition of the rocky intertidal at Helgoland (German Bight, North Sea)

    NASA Astrophysics Data System (ADS)

    Reichert, Katharina; Buchholz, Friedrich; Giménez, Luis

    2008-12-01

    At the rocky island of Helgoland (North Sea), the distribution and abundances of intertidal communities were assessed and the effects of wave exposure and tidal height on the spatial distribution patterns of the communities were evaluated. Macroalgae and invertebrates were sampled quantitatively along line transects in three intertidal locations, a semi-exposed, an exposed and a sheltered one. The semi-exposed location was characterised by (1) Ulva spp. at the high intertidal ( Ulva-community), (2) mussels and periwinkles at the mid intertidal ( Mytilus-community) and (3) Corallina officinalis and mainly the large brown alga Fucus serratus at the low intertidal ( Fucus-community). The exposed location encompassed the mid and low intertidal; at both zones the Fucus-community occurred. The sheltered location was characterised by (1) barnacles ( Balanus-community) and (2) bryozoans, hydrozoans and mainly the large brown alga Ascophyllum nodosum ( Ascophyllum-community). At the semi-exposed, but not at the exposed location the communities changed with the intertidal position. A relationship between wave exposure and the occurrence of specific communities was shown for the sheltered location; in contrast, communities of the semi-exposed and the exposed location appear to be little influenced by wave exposure directly. The community concept and the potential causes of distribution patterns of the defined communities are discussed and suggestions for a future monitoring are given. Variations in the communities at different spatial scales speak in favour of a multiple scale sampling design to monitor changes in the intertidal communities at Helgoland.

  7. Temporal and spatial morphological variations along a cross-shore intertidal profile, Jiangsu, China

    NASA Astrophysics Data System (ADS)

    Gong, Zheng; Jin, Chuang; Zhang, Changkuan; Zhou, Zeng; Zhang, Qian; Li, Huan

    2017-07-01

    Fifteen monthly field surveys were conducted from September 2012 to November 2013 at ten representative stations along a cross-shore profile, covering the entire tidal flat. Results indicate that tidal currents significantly affect bed level variations over bare flats, while subsurface processes (e.g., soil subsidence and expansion) are likely to play an important role in changing the bed level of the upper intertidal flat where salt marshes are present. The cross-shore profile shows a clear double-convex shape, and different geomorphic zones display distinctive variation. Above the mean high water level (MHWL), the bed level is generally stable. The region around the MHWL, where the upper convex point is present, is a location of high sedimentation due to the weaker hydrodynamic conditions and the settling and scour lag effects, it keeps growing with the increase of inundation frequency. A concave point occurs in the middle part of the intertidal flat, showing considerable erosion. Near the mean low water level (MLWL), the lower convex point is elevated due to the long-shore tidal current and associated sediment transport (the flood dominated transport during summer exceeds the ebb dominated transport during winter, hence the net effect favors sedimentation). Further seawards, the area below the MLWL is strongly eroded. The cross-shore profile follows a ;stable-accretional-erosional-accretional-erosional; sequence. Overall, the measurements indicate that the interplay among vegetation, hydrodynamics and sediment transport is critical in shaping the cross-shore morphology of the intertidal flats along the Jiangsu coast of China.

  8. Critical thermal maxima of common rocky intertidal fish and shrimps — A preliminary assessment

    NASA Astrophysics Data System (ADS)

    Vinagre, Catarina; Dias, Marta; Roma, Joana; Silva, Ana; Madeira, Diana; Diniz, Mário S.

    2013-08-01

    Rocky shore ecosystems are considered sentinels of climate warming because they are in close contact with the atmosphere and their shallow waters present low thermal inertia. Concerns on the vulnerability of rocky shore species subject to climate warming make the investigation of their thermal tolerance an urgent topic. The aim of this study was to determine the upper thermal limits of species that are common in tidal pools of rocky shore ecosystems of the Northeast Atlantic. The method used was the Critical Thermal Maximum (CTMax), which allowed the ranking of species in terms of their upper thermal limits as follows: Coryphoblennius galerita (32.0 °C), Palaemon serratus (33.0 °C), Gobius paganellus (33.1 °C), Palaemon elegans (33.4 °C), Lipophrys pholis (33.9 °C) and Paralipophrys trigloides (35.0 °C). Intraspecific variability was always lower than 2%.

  9. Structure of macroalgal communities on tropical rocky shores inside and outside a marine protected area.

    PubMed

    Portugal, Adriana Brizon; Carvalho, Fabrício Lopes; Soares, Marcelo de Oliveira; Horta, Paulo Antunes; de Castro Nunes, José Marcos

    2017-09-01

    The structure of marine macroalgal communities and morpho-functional groups were investigated in a poorly characterized region on the Tropical Southwestern Atlantic coast, Brazil. The survey was conducted at six rocky shores located on the mainland and on coastal islands distributed inside a marine protected area (MPA) and outside the MPA (near a densely populated area). We hypothesized that tropical rocky shores inside the MPA and islands have higher species richness, diversity, and evenness of marine macroalgae. Results confirmed that species richness, diversity and evenness were significantly higher inside the MPA than in rocky shores outside the MPA. Only species richness was higher on islands than on the mainland. The results suggest that human impacts could lead to a competitive advantage and dominance in the articulated calcareous morphotype, resulting in community differences and lower benthic biodiversity in tropical ecosystems near urbanized sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Introduced rats indirectly change marine rocky intertidal communities from algae- to invertebrate-dominated.

    PubMed

    Kurle, Carolyn M; Croll, Donald A; Tershy, Bernie R

    2008-03-11

    It is widely recognized that trophic interactions structure ecological communities, but their effects are usually only demonstrated on a small scale. As a result, landscape-level documentations of trophic cascades that alter entire communities are scarce. Islands invaded by animals provide natural experiment opportunities both to measure general trophic effects across large spatial scales and to determine the trophic roles of invasive species within native ecosystems. Studies addressing the trophic interactions of invasive species most often focus on their direct effects. To investigate both the presence of a landscape-level trophic cascade and the direct and indirect effects of an invasive species, we examined the impacts of Norway rats (Rattus norvegicus) introduced to the Aleutian Islands on marine bird densities and marine rocky intertidal community structures through surveys conducted on invaded and rat-free islands throughout the entire 1,900-km archipelago. Densities of birds that forage in the intertidal were higher on islands without rats. Marine intertidal invertebrates were more abundant on islands with rats, whereas fleshy algal cover was reduced. Our results demonstrate that invasive rats directly reduce bird densities through predation and significantly affect invertebrate and marine algal abundance in the rocky intertidal indirectly via a cross-community trophic cascade, unexpectedly changing the intertidal community structure from an algae- to an invertebrate-dominated system.

  11. Introduced rats indirectly change marine rocky intertidal communities from algae- to invertebrate-dominated

    PubMed Central

    Kurle, Carolyn M.; Croll, Donald A.; Tershy, Bernie R.

    2008-01-01

    It is widely recognized that trophic interactions structure ecological communities, but their effects are usually only demonstrated on a small scale. As a result, landscape-level documentations of trophic cascades that alter entire communities are scarce. Islands invaded by animals provide natural experiment opportunities both to measure general trophic effects across large spatial scales and to determine the trophic roles of invasive species within native ecosystems. Studies addressing the trophic interactions of invasive species most often focus on their direct effects. To investigate both the presence of a landscape-level trophic cascade and the direct and indirect effects of an invasive species, we examined the impacts of Norway rats (Rattus norvegicus) introduced to the Aleutian Islands on marine bird densities and marine rocky intertidal community structures through surveys conducted on invaded and rat-free islands throughout the entire 1,900-km archipelago. Densities of birds that forage in the intertidal were higher on islands without rats. Marine intertidal invertebrates were more abundant on islands with rats, whereas fleshy algal cover was reduced. Our results demonstrate that invasive rats directly reduce bird densities through predation and significantly affect invertebrate and marine algal abundance in the rocky intertidal indirectly via a cross-community trophic cascade, unexpectedly changing the intertidal community structure from an algae- to an invertebrate-dominated system. PMID:18308929

  12. Enhancement of habitat heterogeneity and species richness on rocky shores inundated by sand.

    PubMed

    McQuaid, Christopher D; Dower, Katherine M

    1990-08-01

    Many rocky shores are subject to periodic inundation by sand, which is often thought to reduce species richness by eliminating organisms intolerant of sand scour or sand smothering. However, regular disturbance (e.g. inundation) should promote richness by preventing the development of low diversity climax communities. A study of faunal richness on 10 regularly inundated shores showed that inundation does promote richness, but by increasing habitat heterogeneity. Some species are excluded from parts of the shore by sand, but because of the patchiness of sand deposits they are rarely excluded from the entire shore. Other species are found only on rocks associated with sand, while typically sandy shore animals occur in the sand deposits themselves. Total richness (281 species) was greater than for local noninundated shores and sandy beaches combined.

  13. Stoichiometric Mismatch between Consumers and Resources Mediates the Growth of Rocky Intertidal Suspension Feeders

    PubMed Central

    Bracken, Matthew E. S.

    2017-01-01

    The concept of ecological stoichiometry—the balancing of elemental ratios in ecological interactions—has transformed our thinking about processes in natural systems. Here, this perspective is applied to rocky shore ecosystems to explore the consequences of variation in internal nutrient ratios across two trophic levels. Specifically, I measured the internal concentrations of carbon (C) and nitrogen (N) in mussels (Mytilus spp.) and particulate organic matter (POM) to evaluate the effects of stoichiometric mismatch—the difference in the carbon-to-nitrogen ratio (C:N) between a consumer and its resources—on mussel growth at sites on the coasts of Oregon, USA, and the South Island of New Zealand. As POM quality (i.e., Chl a, a proxy for phytoplankton availability in the POM) increased, C:N of the POM declined, but C:N of mussels increased. This resulted in a greater mismatch in C:N between mussels and their food source at low Chl a. Mussel growth across sites was positively associated with Chl a, particulate organic carbon (POC), and particulate organic nitrogen (PON) but negatively associated with stoichiometric mismatch. Overall, as the elemental ratios of consumers became more different from those of their resources, growth declined, likely due to the energetic cost associated with processing lower quality food. Furthermore, the effect of food quantity on growth depended on stoichiometric mismatch. In New Zealand, where mismatch was high—i.e., consumer C:N differed substantially from resource C:N—consumer growth was strongly affected by resource quantity (Chl a or POC). However, in Oregon, where mismatch was low, the relationship between resource quantity and growth was considerably weaker. This interaction between resource quantity and mismatch was not apparent for PON, which is consistent with variation in PON underlying variation in POM C:N and highlights the role of N in limiting growth. Previous research has neglected the importance of ecological

  14. An Examination of Body Temperature for the Rocky Intertidal Mussel species, Mytilus californianus, Using Remotely Sensed Satellite Observations

    NASA Astrophysics Data System (ADS)

    Price, J.; Liff, H.; Lakshmi, V.

    2012-12-01

    Temperature is considered to be one of the most important physical factors in determining organismal distribution and physiological performance of species in rocky intertidal ecosystems, especially the growth and survival of mussels. However, little is known about the spatial and temporal patterns of temperature in intertidal ecosystems or how those patterns affect intertidal mussel species because of limitations in data collection. We collected in situ temperature at Strawberry Hill, Oregon USA using mussel loggers embedded among the intertidal mussel species, Mytilus californianus. Remotely sensed surface temperatures were used in conjunction with in situ weather and ocean data to determine if remotely sensed surface temperatures can be used as a predictor for changes in the body temperature of a rocky intertidal mussel species. The data used in this study was collected between January 2003 and December 2010. The mussel logger temperatures were compared to in situ weather data collected from a local weather station, ocean data collected from a NOAA buoy, and remotely sensed surface temperatures collected from NASA's sun-synchronous Moderate Resolution Imaging Spectroradiometer aboard the Earth Observing System Aqua and EOS Terra satellites. Daily surface temperatures were collected from four pixel locations which included two sea surface temperature (SST) locations and two land surface temperature (LST) locations. One of the land pixels was chosen to represent the intertidal surface temperature (IST) because it was located within the intertidal zone. As expected, all surface temperatures collected via satellite were significantly correlated to each other and the associated in situ temperatures. Examination of temperatures from the off-shore NOAA buoy and the weather station provide evidence that remotely sensed temperatures were similar to in situ temperature data and explain more variability in mussel logger temperatures than the in situ temperatures. Our

  15. Onshore-offshore morpho-structural pattern of coastal rocky shore in SW Brittany (France): polyphased generation of rocky, shore and exhumed platforms.

    NASA Astrophysics Data System (ADS)

    Raimbault, Celine; Duperret, Anne; Le Gall, Bernard; Wyns, Robert; Regard, Vincent; Authemayou, Christine; Molliex, Stephane

    2017-04-01

    A large granitic submarine and shore platform has been mapped in Western Brittany on 580 km2 surfaces with the aid of several high-resolution (<1 m) aerial and marine surveys: topographic and bathymetric LiDAR using Litto3D project (SHOM, IGN, IFREMER) mixed with marine interferometric echosounding sonar (R/V Haliotis) and low depth multibeam echosondeur with high resolution seismic reflection profiles (R/V Thalia). The structural and geomorphological study of this rocky platform allows understanding its formation on time scale between Paleocene to Quaternary. The marine rocky platform is composed of: (1) a tidal part (shore platform) with a very slight seaward mean slope and a maximal width of about 800 m, (2) a > 5 km-wide and weakly dipping subtidal part, labelled the rocky platform, (3) a rocky external part with varying mean slopes, rocky reefs and sedimentary deposits, corresponding to the continental shelf. The coastal continental domain is characterized by a low elevated (<10 m-high) and severely eroded area, ranging in width between 200 m to about 4 km, and referred to as marine terrace. Its continentward transition with granitic outcrops coincides with a 10 m-high scarp, assumed to represent a paleo-shoreline, hence allowing regarding the marine terrace as a presently exhumed paleo-shore platform. In order to estimate the timing of the denudation process recorded by the rocky platform during Quaternary, 10Be cosmogenic nucleides analyses were performed on submarine and offshore granitic samples. On the basis of 10Be contents, the conceptual evolutionary model applied to the rocky platform implies a polyphased history controlled by continental granitic weathering and high-stand sea level marine erosion. The present-day coastal morphology may be explained by the action of two highstand sea levels since mid-Pleistocene at least, favoring successive eustatic purges of previously weathered granitic rocks. Exposure ages deduced from 10Be content may be

  16. Phylogeography of Supralittoral Rocky Intertidal Ligia Isopods in the Pacific Region from Central California to Central Mexico

    PubMed Central

    Hurtado, Luis A.; Mateos, Mariana; Santamaria, Carlos A.

    2010-01-01

    Background Ligia isopods are widely distributed in the Pacific rocky intertidal shores from central California to central Mexico, including the Gulf of California. Yet, their biological characteristics restrict them to complete their life cycles in a very narrow range of the rocky intertidal supralittoral. Herein, we examine phylogeographic patterns of Ligia isopods from 122 localities between central California and central Mexico. We expect to find high levels of allopatric diversity. In addition, we expect the phylogeographic patterns to show signatures of past vicariant events that occurred in this geologically dynamic region. Methodology/Principal Findings We sequenced two mitochondrial genes (Cytochrome Oxidase I and 16S ribosomal DNA). We conducted Maximum Likelihood and Bayesian phylogenetic analyses. We found many divergent clades that, in general, group according to geography. Some of the most striking features of the Ligia phylogeographic pattern include: (1) deep mid-peninsular phylogeographic breaks on the Pacific and Gulf sides of Baja peninsula; (2) within the Gulf lineages, the northern peninsula is most closely related to the northern mainland, while the southern peninsula is most closely related to the central-southern mainland; and, (3) the southernmost portion of the peninsula (Cape Region) is most closely related to the southernmost portion of mainland. Conclusions/Significance Our results shed light on the phylogenetic relationships of Ligia populations in the study area. This study probably represents the finest-scale phylogeographic examination for any organism to date in this region. Presence of highly divergent lineages suggests multiple Ligia species exist in this region. The phylogeographic patterns of Ligia in the Gulf of California and Baja peninsula are incongruent with a widely accepted vicariant scenario among phylogeographers, but consistent with aspects of alternative geological hypotheses and phylo- and biogeographic patterns of

  17. Shore height and differentials between macrobenthic assemblages in vegetated and unvegetated areas of an intertidal sandflat

    NASA Astrophysics Data System (ADS)

    Barnes, R. S. K.; Barnes, M. K. S.

    2012-06-01

    Intertidal macrobenthic faunal assemblages of a dual seagrass/callianassid-structured sandflat system were investigated in subtropical Moreton Bay, Queensland. Consistently across all 20 stations, the gastropod-dominated seagrass supported greater abundance (2.5×) and species richness (2×) than the amphipod-dominated sandflat. There was no evidence of along-shore or up-shore variation in the overall assemblage properties such as total abundance, species richness or diversity within either habitat type, except for variation in sandflat abundance between sites. But seagrass and sandflat assemblages both varied significantly in composition from site to site, and seagrass assemblage composition also varied with shore height. Shore height and site, however, only accounted for ≤41% of total variation. The two faunal assemblages showed a Bray-Curtis dissimilarity of 97.7% and within-habitat similarities of <20%. There was no consistency in distribution of greater diversity, dominance or evenness. No differential between any assemblage features in adjacent sandflat and seagrass samples changed with shore height, supporting hypotheses that such differentials are not maintained by predation. Macrofaunal species richness and diversity were closely coupled within sandflat stations but were uncoupled within seagrass ones, questioning the value of diversity as a comparative measure.

  18. Catastrophic decline of a top carnivore in the gulf of california rocky intertidal zone.

    PubMed

    Dungan, M L; Miller, T E; Thomson, D A

    1982-05-28

    The predatory sun star, Heliaster kubiniji, once the commonest rocky intertidal asteroid of the Gulf of California, has been rare throughout this region since summer 1978 when a devastating disease outbreak occurred. This unprecedented phenomenon and several other exceptional ecological events in marine communities of the northeastern Pacific appear to be linked to large-scale climatic changes that occurred during 1977 and 1978. Implications of the decline in Heliaster kubiniji are discussed.

  19. Influence of static habitat attributes on local and regional Rocky intertidal community structure

    USGS Publications Warehouse

    Konar, B.; Iken, K.; Coletti, H.; Monson, Daniel H.; Weitzman, Ben P.

    2016-01-01

    Rocky intertidal communities are structured by local environmental drivers, which can be dynamic, fluctuating on various temporal scales, or static and not greatly varying across years. We examined the role of six static drivers (distance to freshwater, tidewater glacial presence, wave exposure, fetch, beach slope, and substrate composition) on intertidal community structure across the northern Gulf of Alaska. We hypothesized that community structure is less similar at the local scale compared with the regional scale, coinciding with static drivers being less similar on smaller than larger scales. We also hypothesized that static attributes mainly drive local biological community structure. For this, we surveyed five to six sites in each of the six regions in the mid and low intertidal strata. Across regions, static attributes were not consistently different and only small clusters of sites had similar attributes. Additionally, intertidal communities were less similar on the site compared with the region level. These results suggest that these biological communities are not strongly influenced by the local static attributes measured in this study. An alternative explanation is that static attributes among our regions are not different enough to influence the biological communities. This lack of evidence for a strong static driver may be a result of our site selection, which targeted rocky sheltered communities. This suggests that this habitat may be ideal to examine the influence of dynamic drivers. We recommend that future analyses of dynamic attributes may best be performed after analyses have demonstrated that sites do not differ in static attributes.

  20. Trophic control of production in a rocky intertidal community.

    PubMed

    Paine, Robert T

    2002-04-26

    In the low intertidal zone at Tatoosh Island, Washington, United States, minimal estimates of primary production can vary from 0 to an average of 86 kilograms of wet mass per square meter per year when the grazing assemblage is manipulated. Highly productive annual kelps (Laminariales) replace less productive perennial species when macroscopic grazers are reduced or absent, resulting in monodominant assemblages of Alaria marginata. Experiments were repeated in seven consecutive years. Increased species richness makes no significant additional contribution to annual production. Rather, a competitively superior species is favored when its enemies are reduced, suggesting that terrestrial perspectives on the role of biodiversity that are developed without considering consumers may not be general.

  1. Evolutionary dynamics in the southwest Indian ocean marine biodiversity hotspot: a perspective from the rocky shore gastropod genus Nerita.

    PubMed

    Postaire, Bautisse; Bruggemann, J Henrich; Magalon, Hélène; Faure, Baptiste

    2014-01-01

    The Southwest Indian Ocean (SWIO) is a striking marine biodiversity hotspot. Coral reefs in this region host a high proportion of endemics compared to total species richness and they are particularly threatened by human activities. The island archipelagos with their diverse marine habitats constitute a natural laboratory for studying diversification processes. Rocky shores in the SWIO region have remained understudied. This habitat presents a high diversity of molluscs, in particular gastropods. To explore the role of climatic and geological factors in lineage diversification within the genus Nerita, we constructed a new phylogeny with an associated chronogram from two mitochondrial genes [cytochrome oxidase sub-unit 1 and 16S rRNA], combining previously published and new data from eight species sampled throughout the region. All species from the SWIO originated less than 20 Ma ago, their closest extant relatives living in the Indo-Australian Archipelago (IAA). Furthermore, the SWIO clades within species with Indo-Pacific distribution ranges are quite recent, less than 5 Ma. These results suggest that the regional diversification of Nerita is closely linked to tectonic events in the SWIO region. The Reunion mantle plume head reached Earth's surface 67 Ma and has been stable and active since then, generating island archipelagos, some of which are partly below sea level today. Since the Miocene, sea-level fluctuations have intermittently created new rocky shore habitats. These represent ephemeral stepping-stones, which have likely facilitated repeated colonization by intertidal gastropods, like Nerita populations from the IAA, leading to allopatric speciation. This highlights the importance of taking into account past climatic and geological factors when studying diversification of highly dispersive tropical marine species. It also underlines the unique history of the marine biodiversity of the SWIO region.

  2. Evolutionary Dynamics in the Southwest Indian Ocean Marine Biodiversity Hotspot: A Perspective from the Rocky Shore Gastropod Genus Nerita

    PubMed Central

    Postaire, Bautisse; Bruggemann, J. Henrich; Magalon, Hélène; Faure, Baptiste

    2014-01-01

    The Southwest Indian Ocean (SWIO) is a striking marine biodiversity hotspot. Coral reefs in this region host a high proportion of endemics compared to total species richness and they are particularly threatened by human activities. The island archipelagos with their diverse marine habitats constitute a natural laboratory for studying diversification processes. Rocky shores in the SWIO region have remained understudied. This habitat presents a high diversity of molluscs, in particular gastropods. To explore the role of climatic and geological factors in lineage diversification within the genus Nerita, we constructed a new phylogeny with an associated chronogram from two mitochondrial genes [cytochrome oxidase sub-unit 1 and 16S rRNA], combining previously published and new data from eight species sampled throughout the region. All species from the SWIO originated less than 20 Ma ago, their closest extant relatives living in the Indo-Australian Archipelago (IAA). Furthermore, the SWIO clades within species with Indo-Pacific distribution ranges are quite recent, less than 5 Ma. These results suggest that the regional diversification of Nerita is closely linked to tectonic events in the SWIO region. The Reunion mantle plume head reached Earth’s surface 67 Ma and has been stable and active since then, generating island archipelagos, some of which are partly below sea level today. Since the Miocene, sea-level fluctuations have intermittently created new rocky shore habitats. These represent ephemeral stepping-stones, which have likely facilitated repeated colonization by intertidal gastropods, like Nerita populations from the IAA, leading to allopatric speciation. This highlights the importance of taking into account past climatic and geological factors when studying diversification of highly dispersive tropical marine species. It also underlines the unique history of the marine biodiversity of the SWIO region. PMID:24736639

  3. Substrate size mediates thermal stress in the rocky intertidal.

    PubMed

    Gedan, Keryn B; Bernhardt, Joanna; Bertness, Mark D; Leslie, Heather M

    2011-03-01

    Variation in physical factors, such as slope, orientation, and wind exposure, shapes thermal conditions. Variation in substrate size is common in many habitats, but its thermal consequences for organisms are not well characterized. Larger substrates should remain more thermally stable and act as thermal refuges for associated organisms during short, thermally stressful periods such as midday temperature peaks or tidal exposure. In observations and a transplant and thermal integration experiment, we found that larger rock substrates stayed cooler and facilitated greater survival of the barnacle Semibalanus balanoides in the high intertidal relative to small substrates during the hot summer months in southern New England, USA. However, in thermally benign northern New England, rock substrate size had no effect on barnacle distributions, indicating that the thermal effects of substrate size are mediated by regional climate.

  4. Physiological community ecology: variation in metabolic activity of ecologically important rocky intertidal invertebrates along environmental gradients.

    PubMed

    Dahlhoff, Elizabeth P; Stillman, Jonathon H; Menge, Bruce A

    2002-08-01

    Rocky intertidal invertebrates live in heterogeneous habitats characterized by steep gradients in wave activity, tidal flux, temperature, food quality and food availability. These environmental factors impact metabolic activity via changes in energy input and stress-induced alteration of energetic demands. For keystone species, small environmentally induced shifts in metabolic activity may lead to disproportionately large impacts on community structure via changes in growth or survival of these key species. Here we use biochemical indicators to assess how natural differences in wave exposure, temperature and food availability may affect metabolic activity of mussels, barnacles, whelks and sea stars living at rocky intertidal sites with different physical and oceanographic characteristics. We show that oxygen consumption rate is correlated with the activity of key metabolic enzymes (e.g., citrate synthase and malate dehydrogenase) for some intertidal species, and concentrations of these enzymes in certain tissues are lower for starved individuals than for those that are well fed. We also show that the ratio of RNA to DNA (an index of protein synthetic capacity) is highly variable in nature and correlates with short-term changes in food availability. We also observed striking patterns in enzyme activity and RNA/DNA in nature, which are related to differences in rocky intertidal community structure. Differences among species and habitats are most pronounced in summer and are linked to high nearshore productivity at sites favored by suspension feeders and to exposure to stressful low-tide air temperatures in areas of low wave splash. These studies illustrate the great promise of using biochemical indicators to test ecological models, which predict changes in community structure along environmental gradients. Our results also suggest that biochemical indices must be carefully validated with laboratory studies, so that the indicator selected is likely to respond to the

  5. The effect of life-history variation on the population size structure of a rocky intertidal snail ( Littorina sitkana)

    NASA Astrophysics Data System (ADS)

    Rochette, Rémy; Dunmall, Karen; Dill, Lawrence M.

    2003-03-01

    On wave-sheltered shores of the northeastern Pacific, the population size structure of Littorina sitkana varies with intertidal height, as larger snails are mostly found only in the upper intertidal. This pattern has been attributed to high predation rates by crabs (and perhaps fish) on large snails inhabiting low-intertidal areas; i.e., large snails are presumed to be rare there simply because predators kill them. In this study we investigate the hypothesis that predation contributes to the shore-level size gradient displayed by L. sitkana by selecting for (or inducing) earlier sexual maturation and reduced somatic growth in low-shore snails relative to high-shore individuals. In the first part of our study, we carried out laboratory dissections, field experiments (mark-release-recapture and caging), and field surveys on a wave-protected shore in Bamfield Inlet, Barkley Sound (British Columbia, Canada). The principal results were: (1) adult survivorship was greater at higher, than at lower, intertidal level, (2) snails displayed a preference for their shore level of origin, (3) immature adults from the high intertidal displayed greater rates of somatic growth relative to immature adults from the low intertidal, and (4) low-shore snails matured at a smaller size than high-shore individuals. In the second part of the study, a large-scale survey showed intra-specific variation in size at sexual maturity (point 4 above) to be relatively consistent over time (winter of 1999 and 2001 for snails from our main study site) and space (13 different sites in winter 2001), although the magnitude of these differences varied greatly from shore to shore. Our results indicate that L. sitkana individuals inhabiting upper and lower parts of their intertidal range allocate resources differently to somatic and gonadal growth, an intra-specific difference that is best interpreted as a response to spatial and size-dependent variation in predation pressure. Taken together, results of

  6. Air-sea CO2 fluxes in the near-shore and intertidal zones influenced by the California Current

    NASA Astrophysics Data System (ADS)

    Reimer, Janet J.; Vargas, Rodrigo; Smith, Stephen V.; Lara-Lara, Ruben; Gaxiola-Castro, Gilberto; Martín Hernández-Ayón, J.; Castro, Angel; Escoto-Rodriguez, Martin; Martínez-Osuna, Juan

    2013-10-01

    The study of air-sea CO2 fluxes (FCO2) in the coastal region is needed to better understand the processes that influence the direction and magnitude of FCO2 and to constrain the global carbon budget. We implemented a 1 year (January through December 2009) paired study to measure FCO2 in the intertidal zone (the coastline to 1.6 km offshore) and the near-shore (˜3 km offshore) off the north-western coast of Baja California (Mexico); a region influenced by year-round upwelling. FCO2 was determined in the intertidal zone via eddy covariance; while in the near-shore using mooring buoy sensors then calculated with the bulk method. The near-shore region was a weak annual net source of CO2 to the atmosphere (0.043 mol CO2 m-2 y-1); where 91% of the outgassed FCO2 was contributed during the upwelling season. Sea surface temperature (SST) and ΔpCO2 (from upwelling) showed the strongest relationship with FCO2 in the near-shore, suggesting the importance of meso-scale processes (upwelling). FCO2 in the intertidal zone were up to four orders of magnitude higher than FCO2 in the near-shore. Wind speed showed the strongest relationship with FCO2 in the intertidal zone, suggesting the relevance of micro-scale processes. Results show that there are substantial spatial and temporal differences in FCO2 between the near-shore and intertidal zone; likely a result of heterogeneity. We suggest that detailed spatial and temporal measurements are needed across the coastal oceans and continental margins to better understand the mechanisms which control FCO2, as well as reduce uncertainties and constrain regional and global ocean carbon balances.

  7. Sampling design for long-term regional trends in marine rocky intertidal communities.

    PubMed

    Irvine, Gail V; Shelly, Alice

    2013-08-01

    Probability-based designs reduce bias and allow inference of results to the pool of sites from which they were chosen. We developed and tested probability-based designs for monitoring marine rocky intertidal assemblages at Glacier Bay National Park and Preserve (GLBA), Alaska. A multilevel design was used that varied in scale and inference. The levels included aerial surveys, extensive sampling of 25 sites, and more intensive sampling of 6 sites. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope ≤30° was rare. This unexpected finding illustrated one value of probability-based surveys and led to a shift in the target habitat type to include steeper, more mixed rocky habitat. Subsequently, we evaluated the statistical power of different sampling methods and sampling strategies to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles Balanomorpha, the mussel Mytilus trossulus, and the rockweed Fucus distichus subsp. evanescens. There was greatest power to detect trends in Mytilus and lesser power for barnacles and Fucus. Because of its greater power, the extensive, coarse-grained sampling scheme was adopted in subsequent years over the intensive, fine-grained scheme. The sampling attributes that had the largest effects on power included sampling of "vertical" line transects (vs. horizontal line transects or quadrats) and increasing the number of sites. We also evaluated the power of several management-set parameters. Given equal sampling effort, sampling more sites fewer times had greater power. The information gained through intertidal monitoring is likely to be useful in assessing changes due to climate, including ocean acidification; invasive species; trampling effects; and oil spills.

  8. Sampling design for long-term regional trends in marine rocky intertidal communities

    USGS Publications Warehouse

    Irvine, Gail V.; Shelley, Alice

    2013-01-01

    Probability-based designs reduce bias and allow inference of results to the pool of sites from which they were chosen. We developed and tested probability-based designs for monitoring marine rocky intertidal assemblages at Glacier Bay National Park and Preserve (GLBA), Alaska. A multilevel design was used that varied in scale and inference. The levels included aerial surveys, extensive sampling of 25 sites, and more intensive sampling of 6 sites. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope ≤30° was rare. This unexpected finding illustrated one value of probability-based surveys and led to a shift in the target habitat type to include steeper, more mixed rocky habitat. Subsequently, we evaluated the statistical power of different sampling methods and sampling strategies to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles Balanomorpha, the mussel Mytilus trossulus, and the rockweed Fucus distichus subsp. evanescens. There was greatest power to detect trends in Mytilus and lesser power for barnacles and Fucus. Because of its greater power, the extensive, coarse-grained sampling scheme was adopted in subsequent years over the intensive, fine-grained scheme. The sampling attributes that had the largest effects on power included sampling of “vertical” line transects (vs. horizontal line transects or quadrats) and increasing the number of sites. We also evaluated the power of several management-set parameters. Given equal sampling effort, sampling more sites fewer times had greater power. The information gained through intertidal monitoring is likely to be useful in assessing changes due to climate, including ocean acidification; invasive species; trampling effects; and oil spills.

  9. Climate change impact on seaweed meadow distribution in the North Atlantic rocky intertidal.

    PubMed

    Jueterbock, Alexander; Tyberghein, Lennert; Verbruggen, Heroen; Coyer, James A; Olsen, Jeanine L; Hoarau, Galice

    2013-05-01

    The North-Atlantic has warmed faster than all other ocean basins and climate change scenarios predict sea surface temperature isotherms to shift up to 600 km northwards by the end of the 21st century. The pole-ward shift has already begun for many temperate seaweed species that are important intertidal foundation species. We asked the question: Where will climate change have the greatest impact on three foundational, macroalgal species that occur along North-Atlantic shores: Fucus serratus, Fucus vesiculosus, and Ascophyllum nodosum? To predict distributional changes of these key species under three IPCC (Intergovernmental Panel on Climate Change) climate change scenarios (A2, A1B, and B1) over the coming two centuries, we generated Ecological Niche Models with the program MAXENT. Model predictions suggest that these three species will shift northwards as an assemblage or "unit" and that phytogeographic changes will be most pronounced in the southern Arctic and the southern temperate provinces. Our models predict that Arctic shores in Canada, Greenland, and Spitsbergen will become suitable for all three species by 2100. Shores south of 45° North will become unsuitable for at least two of the three focal species on both the Northwest- and Northeast-Atlantic coasts by 2200. If these foundational species are unable to adapt to the rising temperatures, they will lose their centers of genetic diversity and their loss will trigger an unpredictable shift in the North-Atlantic intertidal ecosystem.

  10. Climate change impact on seaweed meadow distribution in the North Atlantic rocky intertidal

    PubMed Central

    Jueterbock, Alexander; Tyberghein, Lennert; Verbruggen, Heroen; Coyer, James A; Olsen, Jeanine L; Hoarau, Galice

    2013-01-01

    The North-Atlantic has warmed faster than all other ocean basins and climate change scenarios predict sea surface temperature isotherms to shift up to 600 km northwards by the end of the 21st century. The pole-ward shift has already begun for many temperate seaweed species that are important intertidal foundation species. We asked the question: Where will climate change have the greatest impact on three foundational, macroalgal species that occur along North-Atlantic shores: Fucus serratus, Fucus vesiculosus, and Ascophyllum nodosum? To predict distributional changes of these key species under three IPCC (Intergovernmental Panel on Climate Change) climate change scenarios (A2, A1B, and B1) over the coming two centuries, we generated Ecological Niche Models with the program MAXENT. Model predictions suggest that these three species will shift northwards as an assemblage or “unit” and that phytogeographic changes will be most pronounced in the southern Arctic and the southern temperate provinces. Our models predict that Arctic shores in Canada, Greenland, and Spitsbergen will become suitable for all three species by 2100. Shores south of 45° North will become unsuitable for at least two of the three focal species on both the Northwest- and Northeast-Atlantic coasts by 2200. If these foundational species are unable to adapt to the rising temperatures, they will lose their centers of genetic diversity and their loss will trigger an unpredictable shift in the North-Atlantic intertidal ecosystem. PMID:23762521

  11. Study of the rocky Intertidal communities of central and northern California: Years 3 and 4. Volume 1 of 5

    SciTech Connect

    Hardin, D.

    1990-08-01

    The study objectives are to describe seasonal and successional variation in rocky Intertidal community structure; determine the response of rocky Intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Experimental treatments include clearing three plots in spring 1985 and three plots in fall 1985. Data from the program will be correlated with oil toxicity data and other studies to provide indications of the long term effects of an oil spill on rocky Intertidal communities. The report is volume 1 of a 5 volume set.

  12. Study of the rocky Intertidal communities of central and northern California: Years 3 and 4. Volume 5 of 5

    SciTech Connect

    Hardin, D.

    1990-08-01

    The study objectives are to describe seasonal and successional variation in rocky Intertidal community structure; determine the response of rocky Intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Experimental treatments include clearing three plots in spring 1985 and three plots in fall 1985. Data from the program will be correlated with oil toxicity data and other studies to provide indications of the long term effects of an oil spill on rocky Intertidal communities. The report is volume 5 of a 5 volume set.

  13. Study of the rocky Intertidal communities of central and northern California: Years 3 and 4. Volume 3 of 5

    SciTech Connect

    Hardin, D.

    1990-08-01

    The study objectives are to describe seasonal and successional variation in rocky Intertidal community structure; determine the response of rocky Intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Experimental treatments include clearing three plots in spring 1985 and three plots in fall 1985. Data from the program will be correlated with oil toxicity data and other studies to provide indications of the long term effects of an oil spill on rocky Intertidal communities. The report is volume 3 of a 5 volume set.

  14. Study of the rocky Intertidal communities of central and northern California: Years 3 and 4. Volume 2 of 5

    SciTech Connect

    Hardin, D.

    1990-08-01

    The study objectives are to describe seasonal and successional variation in rocky Intertidal community structure; determine the response of rocky Intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Experimental treatments include clearing three plots in spring 1985 and three plots in fall 1985. Data from the program will be correlated with oil toxicity data and other studies to provide indications of the long term effects of an oil spill on rocky Intertidal communities. The report is volume 2 of a 5 volume set.

  15. Study of the rocky Intertidal communities of central and northern California: Years 3 and 4. Volume 4 of 5

    SciTech Connect

    Hardin, D.

    1990-08-01

    The study objectives are to describe seasonal and successional variation in rocky Intertidal community structure; determine the response of rocky Intertidal communities to natural and human-induced disturbances and correlate these responses with successional, seasonal, and latitudinal variation; and correlate life history information and oil toxicity data with data from this and other relevant studies. The Year III and IV report is for the third (1987) and fourth (1988) years of a five-year field experimental study investigating two biological assemblages, the Mytilus assemblage and the Endocladia/Mastocarpus papillatus assemblage, that are being studied at six sites along the California coast. Experimental treatments include clearing three plots in spring 1985 and three plots in fall 1985. Data from the program will be correlated with oil toxicity data and other studies to provide indications of the long term effects of an oil spill on rocky Intertidal communities. The report is volume 4 of a 5 volume set.

  16. Regional-scale analysis of subtidal rocky shore community

    NASA Astrophysics Data System (ADS)

    Derrien-Courtel, Sandrine; Le Gal, Aodren; Grall, Jacques

    2013-12-01

    The French monitoring network, REseau BENThique (REBENT), was launched by the Ministry of the Environment in 2003 following the 1999 Erika oil spill. REBENT aimed to acquire baseline knowledge of coastal benthic habitat distributions with a special focus on biological diversity. This study analyzed data from 38 subtidal rocky reef sites collected by a single diving team of marine biologists along the coast of Brittany from 2004 to 2010. At each site, the depth limits of the algal belts were determined between 0 and -40 m Chart Datum (CD); the flora and fauna compositions and abundances were sampled at -3 and -8 m CD. A total of 364 taxa (156 flora and 208 fauna), belonging to 12 phyla, were identified. The results showed that the depth limit and density of kelp beds increased as water turbidity decreased; moreover, several changes in community structure could be related to water turbidity and temperature. Thus, northern and southern Brittany showed strong differences in diversity and structure of the dominant kelp species ( Laminaria hyperborea and Saccorhiza polyschides). The results from this kelp habitat composition survey (dominant kelp species and indicator species) provided important information for local pressure assessments, like increases in turbidity. The data also provided a reference that could be useful for detecting changes in coastal water temperatures due to global warming.

  17. Benthic-pelagic links and rocky intertidal communities: bottom-up effects on top-down control?

    PubMed

    Menge, B A; Daley, B A; Wheeler, P A; Dahlhoff, E; Sanford, E; Strub, P T

    1997-12-23

    Insight into the dependence of benthic communities on biological and physical processes in nearshore pelagic environments, long considered a "black box," has eluded ecologists. In rocky intertidal communities at Oregon coastal sites 80 km apart, differences in abundance of sessile invertebrates, herbivores, carnivores, and macrophytes in the low zone were not readily explained by local scale differences in hydrodynamic or physical conditions (wave forces, surge flow, or air temperature during low tide). Field experiments employing predator and herbivore manipulations and prey transplants suggested top-down (predation, grazing) processes varied positively with bottom-up processes (growth of filter-feeders, prey recruitment), but the basis for these differences was unknown. Shore-based sampling revealed that between-site differences were associated with nearshore oceanographic conditions, including phytoplankton concentration and productivity, particulates, and water temperature during upwelling. Further, samples taken at 19 sites along 380 km of coastline suggested that the differences documented between two sites reflect broader scale gradients of phytoplankton concentration. Among several alternative explanations, a coastal hydrodynamics hypothesis, reflecting mesoscale (tens to hundreds of kilometers) variation in the interaction between offshore currents and winds and continental shelf bathymetry, was inferred to be the primary underlying cause. Satellite imagery and offshore chlorophyll-a samples are consistent with the postulated mechanism. Our results suggest that benthic community dynamics can be coupled to pelagic ecosystems by both trophic and transport linkages.

  18. Intertidal benthic macrofauna of rare rocky fragments in the Amazon region.

    PubMed

    Morais, Gisele Cavalcante; Lee, James Tony

    2014-03-01

    Rock fragment fields are important habitat for biodiversity maintenance in coastal regions, particularly when located in protected areas dominated by soft sediments. Researches in this habitat have received surprisingly little attention on the Amazon Coast, despite rock fragments provide refuges, nursery grounds and food sources for a variety of benthic species. The present survey describes the mobile macroinvertebrate species composition and richness of the intertidal rocky fragments in Areuá Island within the "Mãe Grande de Curuçá" Marine Extractive Reserve (RESEX) on the Brazilian Amazon Coast. Samples were collected during the dry (August and November 2009) and rainy seasons (March and May 2010) on the upper and lower intertidal zone, using a 625cm2 quadrat. At each season and intertidal zone, macroinvertebrate samples were collected along four transects (20m each) parallel to the waterline, and within each transect two quadrats were randomly sampled. Macroinvertebrates were identified, density determined, and biomass values obtained to characterize benthic diversity from the rocky fragments. The Jackknife procedure was used to estimate species richness from different intertidal zones during the dry and rainy seasons. Macrofaunal community comprised 85 taxa, with 17 "unique" taxa, 40 taxa were common to both intertidal zones and seasons, and 23 taxa have been recorded for the first time on the Brazilian Amazon Coast. Species richness was estimated at 106 +/- 9.7 taxa and results suggest that sampling effort was representative. Polychaeta was the most dominant in species number, followed by Malacostraca and Gastropoda. Regarding frequency of occurrence, Crustacean species Dynamenella tropica, Parhyale sp. and Petrolisthes armatus were the most frequent representing >75% of frequency of occurrence and 39 taxa were least frequent representing <5% of frequency of occurrence. Occurrence of crustaceans and polychaetes were particularly noteworthy in all

  19. The role of macrobiota in structuring microbial communities along rocky shores

    DOE PAGES

    Pfister, Catherine A.; Gilbert, Jack A.; Gibbons, Sean M.

    2014-10-16

    Rocky shore microbial diversity presents an excellent system to test for microbial habitat specificity or generality, enabling us to decipher how common macrobiota shape microbial community structure. At two coastal locations in the northeast Pacific Ocean, we show that microbial composition was significantly different between inert surfaces, the biogenic surfaces that included rocky shore animals and an alga, and the water column plankton. While all sampled entities had a core of common OTUs, rare OTUs drove differences among biotic and abiotic substrates. For the mussel Mytilus californianus, the shell surface harbored greater alpha diversity compared to internal tissues of themore » gill and siphon. Strikingly, a 7-year experimental removal of this mussel from tidepools did not significantly alter the microbial community structure of microbes associated with inert surfaces when compared with unmanipulated tidepools. However, bacterial taxa associated with nitrate reduction had greater relative abundance with mussels present, suggesting an impact of increased animal-derived nitrogen on a subset of microbial metabolism. Because the presence of mussels did not affect the structure and diversity of the microbial community on adjacent inert substrates, microbes in this rocky shore environment may be predominantly affected through direct physical association with macrobiota.« less

  20. Habitat Discontinuities Separate Genetically Divergent Populations of a Rocky Shore Marine Fish

    PubMed Central

    Knutsen, Halvor; Jorde, Per Erik

    2016-01-01

    Habitat fragmentation has been suggested to be responsible for major genetic differentiations in a range of marine organisms. In this study, we combined genetic data and environmental information to unravel the relative role of geography and habitat heterogeneity on patterns of genetic population structure of corkwing wrasse (Symphodus melops), a rocky shore species at the northern limit of its distribution range in Scandinavia. Our results revealed a major genetic break separating populations inhabiting the western and southern coasts of Norway. This genetic break coincides with the longest stretch of sand in the whole study area, suggesting habitat fragmentation as a major driver of genetic differentiation of this obligate rocky shore benthic fish in Scandinavia. The complex fjords systems extending along the western coast of Norway appeared responsible for further regional genetic structuring. Our findings indicate that habitat discontinuities may lead to significant genetic fragmentation over short geographical distances, even for marine species with a pelagic larval phase, as for this rocky shore fish. PMID:27706178

  1. The role of macrobiota in structuring microbial communities along rocky shores

    SciTech Connect

    Pfister, Catherine A.; Gilbert, Jack A.; Gibbons, Sean M.

    2014-10-16

    Rocky shore microbial diversity presents an excellent system to test for microbial habitat specificity or generality, enabling us to decipher how common macrobiota shape microbial community structure. At two coastal locations in the northeast Pacific Ocean, we show that microbial composition was significantly different between inert surfaces, the biogenic surfaces that included rocky shore animals and an alga, and the water column plankton. While all sampled entities had a core of common OTUs, rare OTUs drove differences among biotic and abiotic substrates. For the mussel Mytilus californianus, the shell surface harbored greater alpha diversity compared to internal tissues of the gill and siphon. Strikingly, a 7-year experimental removal of this mussel from tidepools did not significantly alter the microbial community structure of microbes associated with inert surfaces when compared with unmanipulated tidepools. However, bacterial taxa associated with nitrate reduction had greater relative abundance with mussels present, suggesting an impact of increased animal-derived nitrogen on a subset of microbial metabolism. Because the presence of mussels did not affect the structure and diversity of the microbial community on adjacent inert substrates, microbes in this rocky shore environment may be predominantly affected through direct physical association with macrobiota.

  2. Habitat-associations of turban snails on intertidal and subtidal rocky reefs.

    PubMed

    Smoothey, Amy F

    2013-01-01

    Patchiness of habitat has important influences on distributions and abundances of organisms. Given the increasing threat of loss and alteration of habitats due to pressures associated with humans, there is a need for ecologists to understand species' requirements for habitat and to predict changes to taxa under various future environmental conditions. This study tested hypotheses about the generality of patterns described for one species of marine intertidal turban snail for a different, yet closely-related species in subtidal habitats along the coast of New South Wales, Australia. These two closely-related species live in similar habitats, yet under quite different conditions, which provided an opportunity to investigate how similar types of habitats influence patterns of distribution, abundance and size-structure in intertidal versus subtidal environments. For each species, there were similar associations between biogenically structured habitat and densities. The intertidal species, Turbo undulates, were more abundant, with greater proportions of small individuals in habitats formed by the canopy-forming alga, Hormosira banksii, the solitary ascidian, Pyura stolonifera or the turfing red alga, Corallina officinalis compared to simple habitat (bare rock). Similarly, more Turbo torquatus were found in biogenically structured subtidal habitat, i.e. canopy-forming algae, Ecklonia radiata, mixed algal communities ('fringe'), or turfing red algae (Corallina officinalis and Amphiroa aniceps) than where habitat is simple (barrens). Small T. torquatus were more abundant in areas of turf and 'fringe', while large snails were more abundant in areas of kelp and barrens. These patterns were found at each location sampled (i.e. eight intertidal and two subtidal rocky reefs) and at all times of sampling, across each environment. This study highlighted the consistent influence of biogenically structured habitats on the distribution, abundance and size-structure of intertidal and

  3. Habitat-Associations of Turban Snails on Intertidal and Subtidal Rocky Reefs

    PubMed Central

    Smoothey, Amy F.

    2013-01-01

    Patchiness of habitat has important influences on distributions and abundances of organisms. Given the increasing threat of loss and alteration of habitats due to pressures associated with humans, there is a need for ecologists to understand species' requirements for habitat and to predict changes to taxa under various future environmental conditions. This study tested hypotheses about the generality of patterns described for one species of marine intertidal turban snail for a different, yet closely-related species in subtidal habitats along the coast of New South Wales, Australia. These two closely-related species live in similar habitats, yet under quite different conditions, which provided an opportunity to investigate how similar types of habitats influence patterns of distribution, abundance and size-structure in intertidal versus subtidal environments. For each species, there were similar associations between biogenically structured habitat and densities. The intertidal species, Turbo undulates, were more abundant, with greater proportions of small individuals in habitats formed by the canopy-forming alga, Hormosira banksii, the solitary ascidian, Pyura stolonifera or the turfing red alga, Corallina officinalis compared to simple habitat (bare rock). Similarly, more Turbo torquatus were found in biogenically structured subtidal habitat, i.e. canopy-forming algae, Ecklonia radiata, mixed algal communities (‘fringe’), or turfing red algae (Corallina officinalis and Amphiroa aniceps) than where habitat is simple (barrens). Small T. torquatus were more abundant in areas of turf and ‘fringe’, while large snails were more abundant in areas of kelp and barrens. These patterns were found at each location sampled (i.e. eight intertidal and two subtidal rocky reefs) and at all times of sampling, across each environment. This study highlighted the consistent influence of biogenically structured habitats on the distribution, abundance and size-structure of

  4. Upstream petroleum degradation of mangroves and intertidal shores: the Niger Delta experience.

    PubMed

    Osuji, Leo C; Erondu, Ebere S; Ogali, Regina E

    2010-01-01

    This article was inspired by a field reconnaissance survey of outcrops along the Nembe-Brass axis of the petroliferous Niger Delta. It reviews various tradeoffs of the impact of upstream petroleum (seismic and production) operations on the mangrove ecosystems in that region, the largest in Sub-Saharan Africa. Mangroves and intertidal shores are considered critical to the economic well-being of this region owing to the people's dual occupation in fishing and farming. The mangrove ecosystem provides a nutrient medium, which serves as a nursery and spawning ground for many fish species and other biota. Oil and gas activities might destroy these spawn areas, causing reduction in resource output and community pressure. Devegetation of the mangrove forest as a result of seismic delineation leaves the fragile soil exposed, unprotected, and susceptible to erosion. Again, loss of vegetation might discourage the natural role of plants in air purification (CO(2) utilization and O(2) production). The release of nutrients (organic N(2), NH(3), and NO$\\rm{{_{3};{-}}}$) and polyaromatic hydrocarbons (PAHs) to the environment, with the attendant increase in microbial load, increases biochemical O(2) demand (BOD) and depletes dissolved O(2) (DO) in H(2)O to a level that is beyond the tolerance limit of organisms. This anoxic situation leads to asphyxiation and subsequent fish kill in affected areas. In order of increasing vulnerability, the mangroves and intertidal shores of the Niger Delta fall under categories 8 to 10 on the environmental sensitivity index (ESI) scale, which predisposes the areas to serious long-term effects and clean-up complexity. Thus, there is need to monitor mangrove systems and shoreline changes in the areas of considerable seismic and production activities, especially in the coastal Niger Delta, where pipeline corrosion due to salt intrusion into the swampy environment and 'unsighted fingers' of sabotage have increased the prevalence of oil spills.

  5. Up, Down, and All Around: Scale-Dependent Spatial Variation in Rocky-Shore Communities of Fildes Peninsula, King George Island, Antarctica

    PubMed Central

    Valdivia, Nelson; Díaz, María J.; Holtheuer, Jorge; Garrido, Ignacio; Huovinen, Pirjo; Gómez, Iván

    2014-01-01

    Understanding the variation of biodiversity along environmental gradients and multiple spatial scales is relevant for theoretical and management purposes. Hereby, we analysed the spatial variability in diversity and structure of intertidal and subtidal macrobenthic Antarctic communities along vertical environmental stress gradients and across multiple horizontal spatial scales. Since biotic interactions and local topographic features are likely major factors for coastal assemblages, we tested the hypothesis that fine-scale processes influence the effects of the vertical environmental stress gradients on the macrobenthic diversity and structure. We used nested sampling designs in the intertidal and subtidal habitats, including horizontal spatial scales ranging from few centimetres to 1000s of metres along the rocky shore of Fildes Peninsula, King George Island. In both intertidal and subtidal habitats, univariate and multivariate analyses showed a marked vertical zonation in taxon richness and community structure. These patterns depended on the horizontal spatial scale of observation, as all analyses showed a significant interaction between height (or depth) and the finer spatial scale analysed. Variance and pseudo-variance components supported our prediction for taxon richness, community structure, and the abundance of dominant species such as the filamentous green alga Urospora penicilliformis (intertidal), the herbivore Nacella concinna (intertidal), the large kelp-like Himantothallus grandifolius (subtidal), and the red crustose red alga Lithothamnion spp. (subtidal). We suggest that in coastal ecosystems strongly governed by physical factors, fine-scale processes (e.g. biotic interactions and refugia availability) are still relevant for the structuring and maintenance of the local communities. The spatial patterns found in this study serve as a necessary benchmark to understand the dynamics and adaptation of natural assemblages in response to observed and

  6. Testing the relative contribution of positive and negative interactions in rocky intertidal communities

    SciTech Connect

    Bertness, M.D.; Leonard, G.H.; Levine, J.M.; Schmidt, P.R.; Ingraham, A.O.

    1999-12-01

    In contrast to many other biotic forces, such as competition and predation, the role played by habitat modification by plants and sessile animals in natural communities has not been given the experimental attention it deserves. To test the hypothesis that habitat modification by seaweed canopies can have direct positive effects on rocky intertidal communities, the authors quantified habitat amelioration by Ascophyllum nodosum canopies and its consequences on understory organisms in the Gulf of Maine, USA. At the upper and lower elevational borders of the algal canopy, the authors examined the recruitment, growth, and survivorship of common benthic organisms in canopy removal, and shaded canopy removal plots intended to mimic canopy habitat modifications. The algal canopy greatly reduced potential physical stresses, particularly at high tidal heights. Maximum daily rock temperatures were 5--10 C lower and evaporative water loss was in order of magnitude less under the canopy than in canopy removal plots. The response of understory organisms to canopy removal, however, was species specific and somewhat idiosyncratic. Nonetheless, in general, at the high intertidal border of the canopy the recruitment, growth, and survival of understory organisms were enhanced by the canopy, whereas at the low intertidal border canopy effects were negative or neutral. nearly half of the interactions the authors studied were positive in the high zone.

  7. Trophic ecology of the supralittoral rocky shore (Roscoff, France): A dual stable isotope (δ 13C, δ 15N) and experimental approach

    NASA Astrophysics Data System (ADS)

    Laurand, Sandrine; Riera, Pascal

    2006-07-01

    The present study investigates the trophic transfers on the upper littoral rocky shore (i.e. the supralittoral zone together with the upper midlittoral and adlittoral) of northern Brittany. The population mainly consists of four invertebrate species: the littorinids Littorina saxatilis and Melarhaphe neritoides, the isopod Ligia oceanica and the insect Petrobius maritimus. The utilisation of food sources available to these grazers was examined in a laboratory microcosm feeding experiment and a field study using stable isotopes (δ 13C, δ 15N). The results indicated that although Ligia oceanica preferentially occurs in the supralittoral zone, its trophic subsidies originate mostly from the adlittoral and lower intertidal zones. The stable isotope data also suggested that adlittoral terrestrial organic material may be the major food source of Petrobius maritimus. δ 15N of Littorina saxatilis indicated a highly variable diet consisting of supralittoral lichens, midlittoral macroalgae and other food sources (e.g. microalgae). Both feeding experiments and stable isotope data show that only Melarhaphe neritoides has a clearly identifiable diet based on a mixture of lichens, mostly Verrucaria maura and Caloplaca marina, as estimated by an isotopic mixing model. Hence, the food web of this intertidal zone appears largely based on trophic subsidies from other habitats (i.e. upper and lower intertidal zones).

  8. Surfzone hydrodynamics as a key determinant of spatial variation in rocky intertidal communities.

    PubMed

    Morgan, Steven G; Shanks, Alan L; Fujimura, Atsushi G; Reniers, Ad J H M; MacMahan, Jamie; Griesemer, Chris D; Jarvis, Marley; Brown, Jenna

    2016-10-12

    Larvae of intertidal species develop at sea and must return to adult habitats to replenish populations. Similarly, nutrients, detritus and plankton provide important subsidies spurring growth and reproduction of macroalgae and filter-feeding invertebrates that form the foundation of intertidal communities. Together, these factors determine the density and intensity of interactions among community members. We hypothesized that spatial variation in surfzone hydrodynamics affects the delivery of plankton subsidies. We compared entire zooplankton communities inside and outside the surf zone daily while monitoring physical conditions for one month each at two shores with different surfzone characteristics. Opposite cross-shore distributions of larvae and other zooplankters occurred at the two sites: zooplankton was much more abundant inside the mildly sloping dissipative surf zone (DSZ) with rip currents and was more abundant outside the steep reflective surf zone (RSZ). Biophysical numerical simulations demonstrated that zooplankters were concentrated in rip channels of the DSZ and were mostly unable to enter the RSZ, indicating the hydrodynamic processes behind the observed spatial variation of zooplankters in the surf zone. Differences in the concentration of larvae and other zooplankters between the inner shelf and surf zone may be an underappreciated, key determinant of spatial variation in inshore communities. © 2016 The Author(s).

  9. Rocky-shore communities as indicators of water quality: a case study in the Northwestern Mediterranean.

    PubMed

    Pinedo, Susana; García, María; Satta, Maria Paola; de Torres, Mariona; Ballesteros, Enric

    2007-01-01

    The collection of 152 samples from the upper sublittoral zone along the rocky coasts of Catalonia (Northwestern Mediterranean) was carried out in 1999 in order to test the suitability of littoral communities to be used as indicators of water quality in the frame of the European Water Framework Directive. Detrended correspondence analysis were performed to distinguish between different communities and to relate communities composition to water quality. Samples collected in reference sites were included in the analysis. Mediterranean rocky shore communities situated in the upper sublittoral zone can be used as indicators of the water quality: there is a gradient from high to bad status that comprises from dense Cystoseira mediterranea forests to green algae dominated communities. The geographical patterns in the distribution of these communities show that the best areas are situated in the Northern coast, where tourism is the main economic resource of the area, and the worst area is situated close to the metropolitan zone of Barcelona with high population and industrial development. Thus, Mediterranean sublittoral rocky shore communities are useful indicators of water quality and multivariate analysis are a suitable statistical tool for the assessment of the ecological status.

  10. Computing Risk to West Coast Intertidal Rocky Habitat due to Sea Level Rise using LiDAR Topobathy

    EPA Science Inventory

    Compared to marshes, little information is available on the potential for rocky intertidal habitats to migrate upward in response to sea level rise (SLR). To address this gap, we utilized topobathy LiDAR digital elevation models (DEMs) downloaded from NOAA’s Digital Coast G...

  11. Computing Risk to West Coast Intertidal Rocky Habitat due to Sea Level Rise using LiDAR Topobathy

    EPA Science Inventory

    Compared to marshes, little information is available on the potential for rocky intertidal habitats to migrate upward in response to sea level rise (SLR). To address this gap, we utilized topobathy LiDAR digital elevation models (DEMs) downloaded from NOAA’s Digital Coast G...

  12. [Diversity, abundance and distribution of benthic macrofauna on rocky shores from North Sucre State, Venezuela].

    PubMed

    Fernandez, Johanna; Jiménez, Mayré; Allen, Thays

    2014-09-01

    The rocky intertidal zone is among the most extreme physical environments on Earth. Organisms living in this area are constantly stricken by physico-chemical and biological factors. Due to the ecological importance of these areas, we studied the diversity, abundance and distribution of the rocky coastline benthic macrofauna, from the North coast of Sucre State, Venezuela. We performed bimonthly samplings from November 2008 to September 2009. The collection of biological material in the littoral zone (supra, mid and infralittoral) was done manually with a grid of 0.25m2. Organisms were preserved in 10% formalin for later identification and analysis (ecological parameters and Kruskal-Wallis test to the abundance and diversity). We found a total 19,020 organisms (86 spp.), in 8 phyla, 45 families and 47 genera. Mollusks were the most abundant and diverse (58 spp.), followed by arthropods (12 spp.), annelids (7 spp.), echinoderms (5 spp.), and the less represented cnidarians, sipunculids, nemertinids and urochordates (1 sp.). The zonation found coincided with the universal scheme of zonation. The towns of Rio Boca and Rio Caribe presented the highest values of ecological parameters, and the lowest were found in Playa Grande. Statistical significant differences were found in the abundance and diversity of macrofauna among the three zones. The little information on the composition and distribution of macrobenthic rocky coastline, prevents a better comparison, however the results contribute to the knowledge of the marine biodiversity in this region.

  13. Life in the maelstrom: The biomechanics of wave-swept rocky shores.

    PubMed

    Denny, M W

    1987-03-01

    Nowhere on earth is water motion more violent than in the surf zone of rocky shores, and the hydrodynamic stresses imposed on plants and animals by wave-induced flows far exceed any in terrestrial or oceanic environments. Despite the harshness of the physical environment, wave-swept habitats support persistent, diverse communities. Knowledge of the physical mechanisms by which water motion affects plants and animals and of the ways in which they cope with their environment is essential for understanding the community ecology of these turbulent habitats. Copyright © 1987. Published by Elsevier Ltd.

  14. Microhabitats, thermal heterogeneity, and patterns of physiological stress in the rocky intertidal zone.

    PubMed

    Helmuth, B S; Hofmann, G E

    2001-12-01

    Thermal stress has been considered to be among the most important determinants of organismal distribution in the rocky intertidal zone. Yet our understanding of how body temperatures experienced under field conditions vary in space and time, and of how these temperatures translate into physiological performance, is still rudimentary. We continuously monitored temperatures at a site in central California for a period of two years, using loggers designed to mimic the thermal characteristics of mussels, Mytilus californianus. Model mussel temperatures were recorded on both a horizontal and a vertical, north-facing microsite, and in an adjacent tidepool. We periodically measured levels of heat shock proteins (Hsp70), a measure of thermal stress, from mussels at each microsite. Mussel temperatures were consistently higher on the horizontal surface than on the vertical surface, and differences in body temperature between these sites were reflected in the amount of Hsp70. Seasonal peaks in extreme high temperatures ("acute" high temperatures) did not always coincide with peaks in average daily maxima ("chronic" high temperatures), suggesting that the time history of body temperature may be an important factor in determining levels of thermal stress. Temporal patterns in body temperature during low tide were decoupled from patterns in water temperature, suggesting that water temperature is an ineffective metric of thermal stress for intertidal organisms. This study demonstrates that spatial and temporal variability in thermal stress can be highly complex, and "snapshot" sampling of temperature and biochemical indices may not always be a reliable method for defining thermal stress at a site.

  15. The role of cross-shore tidal dynamics in controlling intertidal sediment exchange in mangroves in Cù Lao Dung, Vietnam

    NASA Astrophysics Data System (ADS)

    Bryan, Karin R.; Nardin, William; Mullarney, Julia C.; Fagherazzi, Sergio

    2017-09-01

    Mangroves are halophytic plants common in tropical and sub-tropical environments. Their roots and pneumatophores strongly affect intertidal hydrodynamics and related sediment transport. Here, we investigate the role tree and root structures may play in altering tidal currents and the effect of these currents on the development of intertidal landscapes in mangrove-dominated environments. We use a one-dimensional Delft3D model, forced using typical intertidal slopes and vegetation characteristics from two sites with contrasting slope on Cù Lao Dung within the Mekong Delta in Vietnam, to examine the vegetation controls on tidal currents and suspended sediment transport as the tides propagate into the forest. Model results show that vegetation characteristics at the seaward fringe determine the shape of the cross-shore bottom profile, with sparse vegetation leading to profiles that are close to linear, whereas with dense vegetation resulting in a convex intertidal topography. Examples showing different profile developments are provided from a variety of published studies, ranging from linear profiles in sandier sites, and distinctive convex profiles in muddier sites. As expected, profile differences in the model are caused by increased dissipation due to enhanced drag caused by vegetation; however, the reduction of flow shoreward in sparsely vegetated or non-vegetated cases was similar, indicating that shallowing of the profile and slope effects play a dominant role in dissipation. Here, tidal velocities are measured in the field using transects of Acoustic Doppler Current Profilers, and confirm that cross-shore tidal currents diminish quickly as they move over the fringe of the forest; they then stay fairly consistent within the outer few 100 m of the forest, indicating that the fringing environment is likely a region of deposition. An understanding of how vegetation controls the development of topography is critical to predicting the resilience of these sensitive

  16. Patterns of variation of intertidal species of commercial interest in the Parque Litoral Norte (north Portugal) MPA: comparison with three reference shores.

    PubMed

    Bertocci, Iacopo; Dominguez, Rula; Freitas, Cristiano; Sousa-Pinto, Isabel

    2012-06-01

    Marine Protected Areas (MPAs) are world-wide established with the aim of conserving biodiversity and preventing overexploitation of marine organisms. Evaluating the effectiveness of MPAs is needed in order to support and implement their management, but it is complicated by the large natural variability in space and time of distribution and abundance of natural populations. Here, we tested the hypothesis that patterns of total abundance and size-frequency distribution of two intensively harvested intertidal species (the sea urchin Paracentrotus lividus and the mussel Mytilus galloprovincialis) differed between a protected and three reference shores along the rocky coast of north Portugal. Response variables were in terms of mean values and measures of variance at different spatial scales (from centimetres to metres) and over time (along a period of about 12 months). A further comparison involved the estimation of the reproductive potential of sea urchins, quantified as variations of Gonad Index (GI = gonad dry weight/body dry weight × 100) at the scale of shore. Results did not generally support a predictable direct effect of protection, as the total abundance and the abundance of larger individuals of both species and GI did not differ between the MPA and reference shores. However, a considerable temporal and spatial variability at smaller scales was detected for several response variables. Such findings have implications for management of MPAs, highlighting the need for sampling designs properly replicated in space and time, in order to examine their effectiveness, and for considering spatial and temporal heterogeneity of target populations and driving processes as a criterion for their implementation and design.

  17. Downwearing rates on shore platforms and rocky coast evolution- bioerosion contribute

    NASA Astrophysics Data System (ADS)

    Moura, Delminda; Gabriel, Selma; Ramos Pereira, Ana; Neves, Mário; Trindade, Jorge; Gamito, Sofia; Santos, Rui; Mafalda Tavares, Ana; Berecibar, Estibaliz; Luísa Martins, Ana

    2010-05-01

    Carbonate rocks are extremely vulnerable to biochemical weathering and, consequently carbonate shores are morphologically complex. Living organisms on hard substrates develop specialized strategies to construct its domicile, to dislodge and to compete by space and food with other species. Those strategies include mechanical and chemical processes, among them, substrate boring, etching, cementation and dissolution (e.g.,Trudgill, 1988; Andrews and Williams, 2000; Bromley and Heinberg, 2006). Shore platforms represent available areas to be biocolonized and, the role of biochemical processes have been emphasizes as important mechanisms on platform genesis (e.g., Stephenson and Kirk, 2000). The current work aims to quantify the role of biological activity in carbonate rocky coast evolution at the centre Algarve (south Portugal). In this area, cliffs expose Miocene carbonate rocks composed by calcarenites and carbonate siltstones. Two coastal sectors with different exposure to waves were monitored: (i) Galé, a well exposed sector to dominant waves from SW and, (ii) Olhos de Água in a sheltered position exposing softer rocks than in Galé. Shore platforms survey and cross-shore topography profiles were done by using a Differential Global Position System (DGPS). Macroalgae and macrozoobenthos colonizing shore platform in both sites (Galé and Olhos de Água) were sampled and identified and, density and species richness was quantified. Three stations in Galé and two more in Olhos de Água where chosen to downwearing measurements. Each station was divided in two half portions: (i) control area, (ii) area to be monitored. In the later one, rock was maintained bared by monthly adding H2O2 to kill organisms. Downwearing rates on bare rock were measured by using a Transverse Microerosion Meter (TMEM) along sixteen months. The control area was measured at the begin of the experience and after sixteen months during which was naturally biocolonized. In addition, density of

  18. The equilibrium cross-shore amplitude of lithologically diverse rocky coastlines

    NASA Astrophysics Data System (ADS)

    Limber, P. W.; Murray, A.

    2011-12-01

    What controls the cross-shore amplitude of rocky coastlines, especially when rock strength varies alongshore? From a bird's-eye view, some rocky coastlines consist of large-amplitude headlands, while others are nearly straight (zero amplitude). Rock strength, or resistance to wave erosion, is a primary control on coastline amplitude: stronger rocks can extend seaward to form headlands, and weaker rocks can retreat landward to form embayments. Previous hypotheses of coastline evolution have proposed that wave energy is focused on headlands and dissipated in neighboring embayments because of wave refraction, and that headlands and bays can eventually reach a stable cross-shore amplitude. However, no quantitative model has been proposed, and it remains unclear 1) how, and if, lithologically-diverse coastlines can reach an equilibrium cross-shore amplitude, and 2) what physical processes control that amplitude. Instead of wave refraction, as discussed above, we propose that internal sediment dynamics control coastline amplitude. As sea cliffs erode and retreat, beach sediment is produced. Beach sediment then controls the frequency and efficacy of wave attack on the sea cliff, and as beach width grows, it acts as a protective cover and reduces sea cliff retreat rates. If we assume that alongshore sediment transport sweeps beach sediment into embayments, forming pocket beaches, and that erosion-resistant headlands remain sediment-free (a key assumption), then pocket beach width can grow and reduce sea cliff retreat rates in embayments. Eventually, the cliff retreat rates in embayments, which consist of weaker lithology, become equal to headland retreat rates, and the coastline can reach an equilibrium amplitude. But, what scales the equilibrium amplitude? If rocky coastline amplitude changes, so does coastline length. If coastline length changes, then so does the alongshore extent of erodible sea cliffs and the total sediment yield from sea cliff erosion. For example, if

  19. Animal diversity in Baltic rocky shore macroalgae: can Cladophora glomerata compensate for lost Fucus vesiculosus?

    NASA Astrophysics Data System (ADS)

    Kraufvelin, Patrik; Salovius, Sonja

    2004-10-01

    The substitution of canopy-forming perennial algae by annual filamentous algae is a common phenomenon on eutrophicated rocky shores with potential consequences for marine biodiversity. In the upper littoral of the northern Baltic Sea, this process is exemplified by decreased occurrence of the brown alga Fucus vesiculosus and increased amounts of filamentous algae (e.g. Cladophora glomerata and Pilayella littoralis). In this study, macrofauna communities of F. vesiculosus and C. glomerata during summer have been compared and the effects on littoral macroinvertebrates of a total or partial replacement of F. vesiculosus by C. glomerata have been estimated. The animal abundance and biomass were higher in C. glomerata than in corresponding amounts of F. vesiculosus (g dwt). Similar results were also obtained when animal abundance and biomass were extrapolated to algal cover per m 2 rocky substrate in the study area. Margalef's species richness was, on the other hand, higher in F. vesiculosus, whereas the Shannon-Wiener diversity was the same. The results indicate that C. glomerata maintains a high diversity of macroinvertebrates in the upper littoral zone of the northern Baltic Sea during summer. A possible substitution of F. vesiculosus by C. glomerata does not immediately affect macroinvertebrate diversity negatively in the littoral zone, although, it is difficult to assess the full consequences due to lack of comparable algal data at wider temporal and spatial scales.

  20. Assessing the role of coastal characteristics in erosional process of rocky shores by boulder quarrying.

    NASA Astrophysics Data System (ADS)

    Causon Deguara, Joanna; Gauci, Ritienne

    2017-04-01

    Rocky coasts are considered as relatively stable coastlines, subject to erosional processes that change the landscape over long periods of time. Block quarrying is one such process, occurring when hydraulic pressure from wave impact dislodges boulders from within the outcropping bedrock. These dislodged boulders can be either deposited inland or dragged seaward by further wave action. This process can be evidenced from boulder deposits on the coast, as well as sockets and detachment scarps that are identified at the shoreline and in the backshore. This study seeks to identify the role of attributes such as aspect, geological structure and water depth have on erosion of rocky coasts through boulder quarrying processes. This is being done through observation of coastline morphology and an analysis of boulder accumulations and erosional features identified on a 3km stretch of rocky shore. The study area is situated on the SE coast of the Island of Malta (Central Mediterranean). The coastline being analysed generally trends NW - SE and consists of a series of limestone beds that dip slightly towards the NE. The boulder deposits observed along the site vary in size, quantity and position with respect to the shoreline. Whilst some areas exhibit large boulder accumulations, other areas are distinguished by the complete absence of such deposits. Taking into consideration the wave climate, the variable size, quantity and distribution of boulder accumulations observed along the site may indicate that geological structure and aspect play an important role in boulder dislodgment by wave action. Key words: rock coast, boulder quarrying, erosional process, Malta

  1. Trophic niche partitioning of littoral fish species from the rocky intertidal of Helgoland, Germany

    NASA Astrophysics Data System (ADS)

    Hielscher, N. N.; Malzahn, A. M.; Diekmann, R.; Aberle, N.

    2015-12-01

    During a 3-year field study, interspecific and interannual differences in the trophic ecology of littoral fish species were investigated in the rocky intertidal of Helgoland island (North Sea). We investigated trophic niche partitioning of common coexisting littoral fish species based on a multi-tracer approach using stable isotope and fatty acids in order to show differences and similarities in resource use and feeding modes. The results of the dual-tracer approach showed clear trophic niche partitioning of the five target fish species, the goldsinny wrasse Ctenolabrus rupestris, the sand goby Pomatoschistus minutus, the painted goby Pomatoschistus pictus, the short-spined sea scorpion Myoxocephalus scorpius and the long-spined sea scorpion Taurulus bubalis. Both stable isotopes and fatty acids showed distinct differences in the trophic ecology of the studied fish species. However, the combined use of the two techniques added an additional resolution on the interannual scale. The sand goby P. minutus showed the largest trophic plasticity with a pronounced variability between years. The present data analysis provides valuable information on trophic niche partitioning of fish species in the littoral zones of Helgoland and on complex benthic food webs in general.

  2. Developing a Greater Understanding of Rocky Intertidal Ecosystems using NASA Earth Observations

    NASA Astrophysics Data System (ADS)

    Price, J.; Lakshmi, V.; Menge, B. A.

    2015-12-01

    Rocky intertidal ecosystems along the pacific north coast are sensitive to the changing climate because they are strongly affected by anthropogenic, biotic, and abiotic processes. While there are several methods to measure, monitor, and model different properties and functions of these important ecosystems, many of those methods are spatially and temporally limited. Utilizing remotely sensed satellite observations in conjunction with in situ observations can offer a greater understanding of the spatial variation of certain biotic and abiotic properties. The purpose of this research was to utilize NASA Earth Observations and in situ observations to better understand the temporal and spatial variation of several ecosystems properties (i.e. sea surface temperature (SST), chlorophyll-a concentration (chl-a), and oceanic surface currents), to predict physiological responses (i.e. body temperature and body growth) of the ecosystem engineer, the California mussel (Mytilus californianus). Using decision trees and other modeling methods, we determined important predictor variables for mussel growth. Furthermore, while remotely sensed satellite observations were not able to capture the fine scale resolution of many of the variables, they were able to explain the spatial variation much better than the in situ observations. Satellite observations coupled with in situ observations further enhanced our understanding of the temporal and spatial variation in biological and physical processes along the pacific north coast.

  3. Reddened seascapes: experimentally induced shifts in 1/f spectra of spatial variability in rocky intertidal assemblages.

    PubMed

    Tamburello, Laura; Bulleri, Fabio; Bertocci, Iacopo; Maggi, Elena; Benedetti-Cecchi, Lisandro

    2013-05-01

    Ecological tests of 1/f-noise models have advanced our understanding of how environmental fluctuations affect population abundance and species distributions. Most empirical studies have been conducted under controlled laboratory conditions and have focused on individual drivers. We present the results of a four-year field experiment in which canopy presence/absence and the availability of primary space were manipulated as red-noise and white-noise spatial processes, respectively, to evaluate their separate and compounded effects on algal turf distribution in a rocky intertidal community. Algal turfs closely tracked spatial variation in canopy distribution, displaying a reddened spectrum of spatial variation. Surprisingly, white-noise clearings also induced a red-shift in turf distribution, a pattern that was related to a nonlinear relation between gap size and turf colonization. The two disturbances interacted antagonistically, dampening the red-shift of turf distribution. Our results provide evidence of experimentally induced shifts in the spectrum of a spatial variable under natural environmental conditions.

  4. δ 13C and δ 15N biogeographic trends in rocky intertidal communities along the coast of South Africa: Evidence of strong environmental signatures

    NASA Astrophysics Data System (ADS)

    Hill, Jaclyn M.; McQuaid, Christopher D.

    2008-11-01

    Ecosystem dynamics driven by top-down controls have been well documented in rocky intertidal communities, while the effects of bottom-up influences are comparatively poorly understood. We hypothesized that large-scale signatures of the physical environment may be identifiable along the South African coastline as it is subject to two very different current systems (Benguela and Agulhas Currents) that profoundly influence primary production and thus both food type and availability. Through stable isotope analysis, we examined biogeographic patterns in multiple trophic levels at four sites along a 1400-km stretch of South African coastline and investigated the dietary role of macroalgal-derived organic carbon in rocky intertidal communities. The general positioning of trophic groups was comparable across all sites, with animals from the same trophic levels grouping together and with a δ 15N fractionation of 1-2‰ between levels. The species found at all sites demonstrated east-west δ 15N enrichment, presumably reflecting a biogeographic shift in nitrogen sources linked to upwelling on the west coast. Filter-feeders gave particularly clear results. Using discriminant analysis, mussels could be categorized into four geographic groups based on carbon and nitrogen signatures: east coast, southeast coast, south-west coast and west coast. Barnacles and polychaetes showed similar geographic groupings to mussels, but with shifts in actual values (1‰ depletion in δ 13C and 3‰ enrichment in δ 15N relative to mussels). This suggests that fractionation varies between species within a trophic level. IsoSource models showed that Ulva sp. made large contributions to the diets of two microalgal grazers ( Siphonaria capensis and Scutellastra granularis) and this dietary dependence increased when moving from west to east coast, along the shoreline. Additionally, IsoSource models determined that relative to phytoplankton, macroalgae accounted for upwards of 60% of suspended

  5. Latitudinal gradients in species richness in assemblages of sessile animals in rocky intertidal zone: mechanisms determining scale-dependent variability.

    PubMed

    Okuda, Takehiro; Noda, Takashi; Yamamoto, Tomoko; Hori, Masakazu; Nakaoka, Masahiro

    2009-03-01

    1. Although latitudinal gradients in species richness within a region are observed in a range of taxa and habitats, little is known about variability in its scale dependence or causal processes. The scale-dependent variability of latitudinal gradients in species richness can be affected by latitudinal differences in (i) the regional relative abundance distribution, and (ii) the degree of aggregated distribution (i.e., intraspecific aggregation and interspecific segregation; henceforth, the degree of aggregation) reflecting differences in ecological processes among regions, which are not mutually exclusive. 2. In rocky intertidal sessile animal assemblages along Japan's Pacific coast (between 31 degrees N and 43 degrees N), scale-dependent variability of the latitudinal gradient in species richness and its causal mechanisms were examined by explicitly incorporating three hierarchical spatial scales into the monitoring design: plots (50 x 100 cm), shores (78 to 235 m), and regions (16.7 to 42.5 km). 3. To evaluate latitudinal differences in the degree of aggregation, the degree of intraspecific aggregation at each spatial scale in each region was examined using the standardized Morishita index. Furthermore, the observed species richness was compared with the species richness expected by random sampling from the regional species pool using randomization tests. 4. Latitudinal gradients in species richness were observed at all spatial scales, but the gradients became steadily more moderate with decreasing spatial scale. The slope of the relative abundance distribution decreased with decreasing latitude. 5. Tests of an index of intraspecific aggregation and randomization tests indicated that although species richness at smaller scales differed significantly from species richness expected based on a random distribution, the degree of aggregation did not vary with latitude. Although some ecological processes (possibly species sorting) may have played a role in determining

  6. Mesoscale variation of mechanisms contributing to stability in rocky shore communities.

    PubMed

    Valdivia, Nelson; González, Andrés E; Manzur, Tatiana; Broitman, Bernardo R

    2013-01-01

    Environmental fluctuations can generate asynchronous species' fluctuations and community stability, due to compensatory dynamics of species with different environmental tolerances. We tested this hypothesis in intertidal hard-bottom communities of north-central Chile, where a persistent upwelling centre maintains a mosaic in sea surface temperatures (SST) over 10s of kilometres along the shore. Coastal upwelling implies colder and temporally more stable SST relative to downstream sites. Uni- and multivariate analyses of multiyear timeseries of SST and species abundances showed more asynchronous fluctuations and higher stability in sites characterised by warmer and more variable SST. Nevertheless, these effects were weakened after including data obtained in sites affected by less persistent upwelling centres. Further, dominant species were more stable in sites exposed to high SST variability. The strength of other processes that can influence community stability, chiefly statistical averaging and overyielding, did not vary significantly between SST regimes. Our results provide observational evidence supporting the idea that exogenously driven compensatory dynamics and the stabilising effects of dominant species can determine the stability of ecosystems facing environmental fluctuations.

  7. Mesoscale Variation of Mechanisms Contributing to Stability in Rocky Shore Communities

    PubMed Central

    Valdivia, Nelson; González, Andrés E.; Manzur, Tatiana; Broitman, Bernardo R.

    2013-01-01

    Environmental fluctuations can generate asynchronous species’ fluctuations and community stability, due to compensatory dynamics of species with different environmental tolerances. We tested this hypothesis in intertidal hard-bottom communities of north-central Chile, where a persistent upwelling centre maintains a mosaic in sea surface temperatures (SST) over 10s of kilometres along the shore. Coastal upwelling implies colder and temporally more stable SST relative to downstream sites. Uni- and multivariate analyses of multiyear timeseries of SST and species abundances showed more asynchronous fluctuations and higher stability in sites characterised by warmer and more variable SST. Nevertheless, these effects were weakened after including data obtained in sites affected by less persistent upwelling centres. Further, dominant species were more stable in sites exposed to high SST variability. The strength of other processes that can influence community stability, chiefly statistical averaging and overyielding, did not vary significantly between SST regimes. Our results provide observational evidence supporting the idea that exogenously driven compensatory dynamics and the stabilising effects of dominant species can determine the stability of ecosystems facing environmental fluctuations. PMID:23326592

  8. Recovery of a subtropical rocky shore is not yet complete, four years after a moderate sized oil spill.

    PubMed

    Finlayson, Kimberly; Stevens, Tim; Arthur, James Michael; Rissik, David

    2015-04-15

    Little is known about the recovery trajectory from small to moderate spills (<1000 t), particularly in the sub-tropics. On 11 March 2009 the MV Pacific Adventurer spilt 270 t of bunker fuel oil 13 km off Moreton Island, Australia, impacting wetlands, sandy beaches and rocky shores. This study examines the recovery of the rocky shore community four years after the spill. Results indicate that recovery on Moreton Island is taking longer than the 3-4 years suggested by the literature. The upper shore is recovering faster than the mid shore and is nearly recovered while the mid shore is still in the recovery process. These results indicate that small to moderate sized spills can have environmental impacts on par with much larger spills and emphasizes the need for a clear definition of a recovery endpoint. Long term studies are required to gain a full understanding of trajectories of recovery after oil spill impacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. The use of macroalgal species richness and composition on intertidal rocky seashores in the assessment of ecological quality under the European Water Framework Directive.

    PubMed

    Wells, Emma; Wilkinson, Martin; Wood, Paul; Scanlan, Clare

    2007-01-01

    The EC Water Framework Directive (WFD) suggests using abundance and species composition of intertidal seaweed communities for ecological quality classification of rocky seashores. There are two difficulties with this. According to WFD all sensitive species should be present on a shore. There is no accepted list of sensitive seaweed species and those which may be sensitive in one location may not be so in another. Second, natural successions can result in very large abundance changes of common species, e.g. from almost completely fucoid-dominated shores to almost totally barnacle-dominated shores, without any change in ecological quality. Studies have shown that numerical species richness, not the list of actual species present, is broadly constant in the absence of disturbance. The ephemeral species, possibly the sensitive members of the community, change regularly in such a way as to conserve species richness. It is proposed that species richness on a defined length of shore be used as a criterion of ecological quality. A database of species found on over 300 shores in the British Isles, under strictly controlled sampling conditions, has given ranges of values of species richness to be expected and has allowed for variations in these values due to sub-habitat variability, wave exposure and turbidity to be factored in. A major problem in applying such a tool is the lack of expertise of many workers in critical identification of seaweed species. A reduced species list has been extracted from the database using species commonly present and identifiable with reasonable certainty. A numerical index of ecological quality is proposed based on scores for various aspects of the physical nature of the habitat combined with a score for species richness which may be based on the reduced species list. The scoring system also uses further aspects of community structure, such as ecological status groups and the proportions of rhodophyta, chlorophyta and opportunist species. For

  10. Components of predation intensity in the low zone of the New England rocky intertidal region.

    PubMed

    Menge, Bruce A

    1983-05-01

    Predation intensity often increases along local gradients of decreasing environmental rigor. Assuming factors such as productivity and heterogeneity do not change along such gradients, potential factors responsible for this pattern include: (1) increased effectiveness per individual predator, (2) increased numbers of individual predators, (3) increased numbers of predator species of the same general morphological attributes, and (4) increased numbers of predator species of different general morphological attributes. I term these factors the components of predation intensity.In relatively protected low rocky intertidal regions of northern New England, community structure depends in part on the foraging activities of up to six species (three general types) of predators (Lubchenco and Menge 1978). These include three species of crab, two species of seastars, and one thaidid gastropod. This predator guild prevents mussel and barnacle populations from outcompeting Chondrus crispus. This red alga dominates space when predators are present, but is outcompeted by mussels when predators are excluded.Prey consumption rates (mg per predator individual per hr or mg g(-1) hr(-1)) in field experiments indicate that the rank from most to least effective predator type is crabs, seastars, and the gastropod. Statistically significant variations occur between predator types (largest differences), species of a given type, and individuals of a species (smallest differences). Estimates of the relative contribution of each species to total predation intensity in the low zone at several sites indicate that each predator species is a major predator at one or more sites. Thus, if one predator species in this guild becomes scarce, the other predators may increase their effects and reduce variation in the total predation intensity exerted by the guild. Comparisons with other systems suggest that increased diversity of types of foraging characteristics in predatory guilds is an important

  11. From Space to the Rocky Intertidal: Measuring the Body Temperature of the Intertidal Mussel Species, Mytilus californianus using NASA MODIS Surface Temperatures

    NASA Astrophysics Data System (ADS)

    Price, J.; Lakshmi, V.; Menge, B. A.

    2014-12-01

    The California mussel, Mytilus californianus, is an ecologically important species in the rocky intertidal ecosystems of the U.S. Pacific coast. During low tides, times of emersion, Mytilus californianus is exposed to aerial conditions and its body temperature can vary drastically depending on the amount of solar radiation they experience. Thermal stress from high temperatures during emersion sometimes can lead to mortality of individuals. Conversely, during high tides, times of submersion, body temperatures depend on the temperature of the water that surrounds them. This study used remotely sensed surface temperature observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Earth Observing System (EOS) Aqua and Terra to predict the body temperatures of Mytilus californianus. Mussel body temperatures were provided by the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) and de-tided. This technique divided the mussel body temperatures into times of emersion and times of submersion. During times of emersion, mussel body temperatures were compared to remotely sensed land surface temperatures (LST) and in-situ air temperatures. During times of submersion, mussel body temperatures were compared to remotely sensed sea surface temperatures (SST) and in-situ water temperatures. To identify spatial variation in temperatures, eight different study sites ranging in latitude along the coast of Oregon were analyzed. Additionally, to better understand the temporal variation in temperatures, fourteen years (2000-2013) were analyzed for each study site. Sea surface temperature collected during the Aqua overpass and Terra overpass were strongly correlated with mussel body temperatures but varied by study site. Our results show that remotely sensed temperature could predict average daily mussel temperature within 1°C on average during times of submersion. Being able to use remotely sensed surface temperatures to predict the body

  12. Bioconstruction, bioerosion and disturbance on tropical coasts: coral reefs and rocky limestone shores

    NASA Astrophysics Data System (ADS)

    Spencer, Tom; Viles, Heather

    2002-11-01

    The ecology of tropical carbonate coasts, including coral reefs and rocky limestone shores, is susceptible to disturbance that may have linked effects on geomorphology. Biogeomorphology, which considers the interrelations between biological and geomorphological processes, is particularly well-suited toward the understanding of such carbonate systems. Field observations and experimentation on tropical and temperate coasts by both biologists and geomorphologists, and the development of ecological theory, have come to stress the importance not of stable, successional littoral communities but rather of nonequilibrial, multistate systems. These ideas now need to be incorporated into improved models of coastal dynamics. Case studies from the Central Pacific, the Caribbean and the western Indian Ocean illustrate the interactions between external environmental variability and internal biological processes. These studies show how changing the balance between bioconstructional and bioerosional processes can interrupt a system's development and, in some cases, shift carbonate-based systems between healthy and degradational states. A better understanding of the spatial and temporal complexities present in carbonate coastal and shallow marine environments is an important precursor to effective coastal zone management on these prevalent tropical shorelines.

  13. Trophic cascades in rocky shore tide pools: distinguishing lethal and nonlethal effects.

    PubMed

    Trussell, Geoffrey C; Ewanchuk, Patrick J; Bertness, Mark D; Silliman, Brian R

    2004-05-01

    The effects of predators on the density of their prey can have positive indirect effects on the abundance of the prey's resource via a trophic cascade. This concept has strongly influenced contemporary views of how communities are structured. However, predators also can transmit indirect effects by inducing changes in prey traits. We show that the mere presence of predator risk cues can initiate a trophic cascade in rocky shore tide pools. In large (mean surface area =9 m2), natural tide pools, we manipulated crab density and their foraging ability to examine the relative importance of lethal (density-mediated) and non-lethal (trait-mediated) predator effects to algal community development. We found that perceived predation risk reduced snail density as much as the direct predation treatment, showing that green crab predation was not an important factor regulating local snail density. Instead, snail emigration away from resident crabs appears to be the most important factor regulating local snail density. As a result, the abundance of ephemeral green algae was similar in the predation risk and direct predation treatments, suggesting that the consumption of snails by crabs plays a minimal role in mediating the trophic cascade. Increased attention to trait-mediated effects that are transmitted by predator-induced changes in prey behavior may change our view of how predators exert their strong influence on community structure.

  14. MidMedPol: Polychaetes from midlittoral rocky shores in Greece and Italy (Mediterranean Sea).

    PubMed

    Keklikoglou, Kleoniki; Faulwetter, Sarah; Chatzigeorgiou, Giorgos; Badalamenti, Fabio; Kitsos, Militiadis Spyridon; Arvanitidis, Christos

    2013-01-01

    This paper describes a dataset of polychaetes (Annelida) from 14 midlittoral rocky shore sampling sites in Greece and Italy (Mediterranean Sea). The dataset combines the outcome of four different projects studying the hard substrate midlittoral zone in the Mediterranean between 1984 and 2009. Samples were collected by scraping and collecting the organisms from a framed area. The maximal sampling depth was 1.5 m. In total, 123 polychaete species were recorded, five of which are new records for the respective biogeographic sectors of the Mediterranean. The dataset contains 788 occurrence records, fully annotated with all required metadata. These data contribute to the knowledge of a previously very understudied regional habitat, since at present, comprehensive lists of the midlittoral communities in the Mediterranean are provided through only a few, paper-based, studies. This dataset is one of the first electronic data compilations of the Mediterranean midlittoral zone communities and certainly the most comprehensive of its kind, contributing 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. It is accessible at http://ipt.vliz.be/resource.do?r=mediterraneanpolychaetaintertidal.

  15. MidMedPol: Polychaetes from midlittoral rocky shores in Greece and Italy (Mediterranean Sea)

    PubMed Central

    2013-01-01

    Abstract This paper describes a dataset of polychaetes (Annelida) from 14 midlittoral rocky shore sampling sites in Greece and Italy (Mediterranean Sea). The dataset combines the outcome of four different projects studying the hard substrate midlittoral zone in the Mediterranean between 1984 and 2009. Samples were collected by scraping and collecting the organisms from a framed area. The maximal sampling depth was 1.5 m. In total, 123 polychaete species were recorded, five of which are new records for the respective biogeographic sectors of the Mediterranean. The dataset contains 788 occurrence records, fully annotated with all required metadata. These data contribute to the knowledge of a previously very understudied regional habitat, since at present, comprehensive lists of the midlittoral communities in the Mediterranean are provided through only a few, paper-based, studies. This dataset is one of the first electronic data compilations of the Mediterranean midlittoral zone communities and certainly the most comprehensive of its kind, contributing 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. It is accessible at http://ipt.vliz.be/resource.do?r=mediterraneanpolychaetaintertidal. PMID:24723761

  16. Wastewater nitrogen and trace metal uptake by biota on a high-energy rocky shore detected using stable isotopes.

    PubMed

    Oakes, Joanne M; Eyre, Bradley D

    2015-11-15

    On high-energy rocky shores receiving treated wastewater, impacts are difficult to distinguish against a highly variable background and are localised due to rapid dilution. We demonstrate that nitrogen stable isotope values (δ(15)N) of rocky shore biota are highly sensitive to wastewater inputs. For macroalgae (Ulva lactuca and Endarachne binghamiae), grazing snails (Bembicium nanum and Nerita atramentosa), and predatory snails (Morula marginalba), δ(15)N was enriched near a wastewater outfall and declined with distance, returning to background levels within 290m. Any of these species therefore indicates the extent of influence of wastewater, allowing identification of an appropriate scale for studies of ecosystem impacts. For M. marginalba, significant regressions between δ(15)N and tissue copper, manganese, and zinc concentrations indicate a possible wastewater source for these metals. This suggests that δ(15)N is a proxy for exposure to wastewater contaminants, and may help to attribute variations in rocky shore communities to wastewater impacts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Predators on rocky shores in the northern Atlantic: Can the results of local experiments be generalized on a geographical scale?

    NASA Astrophysics Data System (ADS)

    Ingólfsson, Agnar

    2009-07-01

    Experimental manipulations of invertebrate prey and predators on rocky shores have been done by many authors. In the northern Atlantic the predators involved are usually the green crab Carcinus maenas and/or the dogwhelk Nucella lapillus, and the prey species studied are acorn barnacles (balanid Cirripedia), mussels ( Mytilus spp.) and winkles ( Littorina spp.). Usually the predators are found to have a regulating "top-down" effect on the prey species. In Iceland the acorn barnacle Semibalanus balanoides, the blue mussel Mytilus edulis and the flat periwinkle Littorina obtusata (including to some extent Littorina mariae) are found on rocky shores all around Iceland in what would seem to be near-optimal physical conditions. The predators Carcinus maenas and Nucella lapillus, on the other hand, are relatively southern species that do not thrive on the colder coasts of Iceland. Thus general surveys of different coasts of Iceland would seem to offer opportunities to see whether the results of local experiments can be discerned on a geographical scale (hundreds of km). The roughly 4900 km of the rocky coastline in Iceland was in this study subdivided into four regions, I-IV, according to the commonness or presence of the two predators. With the hope of reducing compounding factors the surveys were confined to sheltered or semi-sheltered fucoid shores, which were further divided into Ascophyllum (more sheltered) and Fucus vesiculosus (less sheltered) shores. Estuaries or other low-salinity environments were avoided. The study was based on 761 stations distributed around the rocky coastline on these two types of shores. The results for barnacles and mussels, being generally more abundant in regions were predators were scarce or absent, and being less common in Ascophyllum than F. vesiculosus shores in contrast to the predatory dogwelks, were in large measure in accord with predictions from experiments indicating "top-down" regulation. The results for the periwinkles

  18. Complexity of early and middle successional stages in a rocky intertidal surfgrass community.

    PubMed

    Turner, Teresa

    1983-10-01

    A variety of simple models have been proposed to describe ecological succession (e.g., Connell and Slatyer 1977), but these models do not address some agents that may increase complexity. To determine the complexity of a natural sequence, four null hypotheses were tested: (1) seasonality of growth, recruitment, and mortality does not influence succession; (2) the interspecific interactions that produce successional change are the same throughout the sequence; (3) consumers have no influence on succession, and (4) small scale spatial variation in establishment and mortality does not occur. These hypotheses were tested in a low zone rocky intertidal community normally dominated by the surfgrass Phyllospadix scouleri on the Oregon coast.Succession experiments initiated in different seasons and an herbivore exclusion experiment falsified each of these hypotheses. At two sites (Boiler Bay and Squaw Island) experimental plots that were cleared in the spring were first colonized by Ulva sp., but those cleared in other seasons were first colonized by Phaeostrophion irregulare. Ulva appears adapted to colonize space made available by winter storms, whereas Phaeostrophion takes advantage of space made available by sand movement in the fall. Another seasonal pattern was the sharp decline in total algal cover in the fall, when wave action increased. At Squaw Island, the presence of Phaeostrophion established in fall and winter significantly inhibited the summer establishment of Ulva, though Ulva occupied some space epiphytically. In contrast, at Boiler Bay, a different, stronger type of interspecific interaction occurred: Phaeostrophion totally inhibited the establishment of filamentous diatoms. The cover of Ulva in the summer was also influenced by herbivores, but Ulva cover declined in the fall in both herbivore exclusions and controls, suggesting that herbivores were not solely responsible for its replacement. Local variation was demonstrated, because after three years of

  19. Effects of productivity, consumers, competitors, and El Nino events on food chain patterns in a rocky intertidal community

    SciTech Connect

    Wootton, J.T.; Pfister, C.A.; Paine, R.T.

    1996-11-06

    We experimentally manipulated nutrient input to a rocky intertidal community, using nutrient-diffusing flowerpots, to determine (i) whether nutrients limited intertidal productivity, (ii) how a large-scale oceanographic disturbance (an El Nino event) affected patterns of nutrient limitation, (iii) the relative impacts of molluscan grazers and nutrient limitation, and (iv) if responses to experimental nutrient addition among trophic levels were more consistent with prey-dependent or ratio-dependent food chain models. Nutrients measurably increased the abundance of micrograzers (amphipods and chironomid larvae), but not algal biomass, during the summer of an El Nino years and during the autumn of an El Nino year. Adding nutrients did not affect food chain stability as assessed by temporal variation in algal biomass and micrograzer abundance. Large molluscan grazers caused large reductions in micrograzers and smaller reductions in algae, indicating consistent consumer effects. The results demonstrate that in this intertidal community, nutrient limitation can occur under conditions of nutrient stress, that top-down grazing effects are typically stronger than bottom-up nutrient effects, and that prey-dependent models are more appropriate than ratio-dependent models. 40 refs., 1 fig., 1 tab.

  20. Speciation and diversity on tropical rocky shores: a global phylogeny of snails of the genus Echinolittorina.

    PubMed

    Williams, S T; Reid, D G

    2004-10-01

    A phylogenetic approach to the origin and maintenance of species diversity ideally requires the sampling of all species within a clade, confirmation that they are evolutionarily distinct entities, and knowledge of their geographical distributions. In the marine tropics such studies have mostly been of fish and reef-associated organisms, usually with high dispersal. In contrast, snails of the genus Echinolittorina (Littorinidae) are restricted to rocky shores, have a four-week pelagic development (and recorded dispersal up to 1400 km), and show different evolutionary patterns. We present a complete molecular phylogeny of Echinolittorina, derived from Bayesian analysis of sequences from nuclear 28S rRNA and mitochondrial 12S rRNA and COI genes (nodal support indicated by posterior probabilities, maximum likelihood, and neighbor-joining bootstrap). This consists of 59 evolutionarily significant units (ESUs), including all 50 known taxonomic species. The 26 ESUs found in the Indo-West Pacific region form a single clade, whereas the eastern Pacific and Atlantic species are basal. The earliest fossil occurred in the Tethys during the middle Eocene and we suggest that the Indo-West Pacific clade has been isolated since closure of the Tethyan seaway in the early Miocene. The geographical distributions of all species (based on more than 3700 locality records) appear to be circumscribed by barriers of low temperature, unsuitable sedimentary habitat, stretches of open water exceeding about 1400 km, and differences in oceanographic conditions on the continuum between oceanic and continental. The geographical ranges of sister species show little or no overlap, indicating that the speciation mode is predominantly allopatric. Furthermore, range expansion following speciation appears to have been limited, because a high degree of allopatry is maintained through three to five branching points of the phylogeny. This may be explained by infrequent long-distance colonization, habitat

  1. Seabed morphology along the rocky shore of the Barlavento Coast, southern Portuguese continental shelf

    NASA Astrophysics Data System (ADS)

    Correia, Ricardo; Lavoie, Caroline; Pinheiro, Luis; Magalhães, Vitor; Moura, Delminda; Bennazzouz, Omar; Sena, Clara; Silva, Paulo; Gabriel, Selma; Horta, João; Abreu, Tiago; Mota, António

    2014-05-01

    The coastal area between Galé and Olhos de Água, in the southernmost coast of the Algarve (Portugal) is characterized by shore platforms and sandy beaches where the carbonate rocky cliffs are undergoing a dramatic recession (Marques, 2008; Nunes et al., 2009). Such crenulated coast plays an important morphological control on alongshore drift. In order to understand the sedimentation patterns in this area and characterize the seabed morphology and subsurface geology, a detailed sidescan sonar (100 and 400 kHz) and high-resolution seismic (Chirp Sonar, 05-12 kHz) survey was carried out, complemented with sediment sampling, along the rocky shore of the Barlavento Coast, southern Portuguese continental shelf, in the scope of the EROS project. The acquired data concentrate in two main areas: Olhos de Água and Galé. The sidescan sonar data were processed and analyzed using the integrated Triton perspective software and the mosaics were gridded at a cell size of 0.5 m. 27 seabed sediment grab samples were used to ground-truth the sidescan mosaics and produce a semi-quantitative seabed classification map. The seismic data were processed using the SPW and RadExPro softwares. Preliminary results show that the seafloor of the area Galé (2.25 km2) is characterized by: (1) a field of ripples that occurs on the flat portions and in the deeper part of the study area between 10 and 18 m depth; these ripples are symmetric, 3-400 m long and have wavelengths up to 2.5 m; most of the ripples can be classified as straight or sinuous in phase, and they are generally sub-parallel to the slope with a NW-SE trending; (2) bedrock outcrops that are present from the coastline until 12 m water depth; and (3) anthropogenic features associated to small scale fishing activities, observed at the border between fine sand with high concentration of shells and low concentration. In the Olhos de Água area (3.1 km2) the seafloor is generally characterized by (1) asymmetrical E-W trending

  2. One solution for two challenges: the lizard Microlophus atacamensis avoids overheating by foraging in intertidal shores.

    PubMed

    Sepúlveda, Maritza; Sabat, Pablo; Porter, Warren P; Fariña, José Miguel

    2014-01-01

    In lizards, one of the most important behavioral mechanisms to cope with spatial and temporal variations in thermal resources observed is activity time. The longer a lizard can maintain activity, the more time it has to forage and reach larger adult body size. We studied the behavioral adjustments to different climatic regimens on daily and seasonal scales in three natural populations of the lizard Microlophus atacamensis along a latitudinal temperature and rainfall gradient. We also used Niche Mapper to determinate the amount of thermally suitable time for activity for this species. Abundance and daily activity patterns varied greatly over the year for the three populations. In summer and spring, the daily activity times were greater, and were reduced in fall and winter seasons. In summer, when stressful heat loads should prohibit activity over a midday gap, lizards did not show bimodal patterns of activity. Instead, they move to the cooler intertidal habitat. Abundance and thermal quality in the southernmost coolest site was lower, and the potential annual activity time decreases with latitude. Contrary to expectations, lizards from this locality showed the largest body sizes possibly due to diet and/or time to sexual maturation. Our results indicate that the intertidal habitat is a key factor that influences daily and seasonal activity of M. atacamensis lizards. While this habitat is not climatically optimal for lizards, it allows them to behaviorally extend their activity window and gain access to food in the intertidal areas.

  3. One Solution for Two Challenges: The Lizard Microlophus atacamensis Avoids Overheating by Foraging in Intertidal Shores

    PubMed Central

    Sepúlveda, Maritza; Sabat, Pablo; Porter, Warren P.; Fariña, José Miguel

    2014-01-01

    In lizards, one of the most important behavioral mechanisms to cope with spatial and temporal variations in thermal resources observed is activity time. The longer a lizard can maintain activity, the more time it has to forage and reach larger adult body size. We studied the behavioral adjustments to different climatic regimens on daily and seasonal scales in three natural populations of the lizard Microlophus atacamensis along a latitudinal temperature and rainfall gradient. We also used Niche Mapper to determinate the amount of thermally suitable time for activity for this species. Abundance and daily activity patterns varied greatly over the year for the three populations. In summer and spring, the daily activity times were greater, and were reduced in fall and winter seasons. In summer, when stressful heat loads should prohibit activity over a midday gap, lizards did not show bimodal patterns of activity. Instead, they move to the cooler intertidal habitat. Abundance and thermal quality in the southernmost coolest site was lower, and the potential annual activity time decreases with latitude. Contrary to expectations, lizards from this locality showed the largest body sizes possibly due to diet and/or time to sexual maturation. Our results indicate that the intertidal habitat is a key factor that influences daily and seasonal activity of M. atacamensis lizards. While this habitat is not climatically optimal for lizards, it allows them to behaviorally extend their activity window and gain access to food in the intertidal areas. PMID:24839969

  4. A Novel Approach to Mapping Intertidal Areas Using Shore-Based X-band Marine Radar

    NASA Astrophysics Data System (ADS)

    Bird, Cai; Bell, Paul

    2014-05-01

    Monitoring the morphology of coastal zones in response to high energy weather events and changing patterns of erosion and deposition over time is vital in enabling effective decision-making at the coast. Common methods of mapping intertidal bathymetry currently include vessel-based sonar and airborne LiDAR surveys, which are expensive and thus not routinely collected on a continuous basis. Marine radar is a ubiquitous technology in the marine industry and many ports operate a system to guide ships into port, this work aims to utilise this already existing infrastructure to determine bathymetry over large intertidal areas, currently up to 4 km from the radar. Standard X-band navigational radar has been used in the marine industry to measure hydrodynamics and derive bathymetry using empirical techniques for several decades. Methods of depth mapping thus far have relied on the electromagnetic backscattering from wind-roughened water surface, which allows a radar to gather sea surface image data but requires the waves to be clearly defined. The work presented here does not rely on identifying and measuring these spatial wave features, which increases the robustness of the method. Image data collected by a 9.4Ghz Kelvin Hughes radar from a weather station on Hilbre Island at the mouth of the River Dee estuary, UK were used in the development of this method. Image intensity at each pixel is a function of returned electromagnetic energy, which in turn can be related to the roughness of the sea surface. Images collected over time periods of 30 minutes show general patterns of wave breaking and mark the advance and retreat of the waterline in accordance with the tidal cycle and intertidal morphology. Each pixel value can be extracted from these mean images and analysed over the course of several days, giving a fluctuating time series of pixel intensity, the gradient of which gives a series of pulses representing transitions between wet and dry at each location. A tidal

  5. Biological interactions and their role in community structure in the rocky intertidal of Helgoland (German Bight, North Sea)

    NASA Astrophysics Data System (ADS)

    Janke, Klaus

    1990-06-01

    Over 3 successive seasonal cycles (April 1986 to October 1988), field experiments were established within 3 intertidal levels in the sheltered rocky intertidal of Helgoland (North Sea, German Bight). Competitors for space ( Mytilus edulis, macroalgae), herbivores ( Littorina spp.) and predators ( Carcinus maenas) were either excluded from areas (0.25 m2) covered by undisturbed communities or enclosed at natural densities on areas that were cleared before of animals and plants. All the experimental fields (each 0.25 m2) were covered by cages with 4 mm gauze at the sides and a plexiglas top. The results of the experiments in the upper intertidal (occupied by Littorina spp. and Enteromorpha) showed that a natural density of herbivores could not prevent algal settlement and had only little influence on algal growth. Instead abiotic factors (storms, algae washed ashore) decreased the stock of the green algae. Experiments in the mid intertidal, dominated by Mytilus (50% cover), Fucus spp. (20%) and grazing L. littorea (100 ind. m-2) showed that community structure was directly changed both by grazing periwinkles and by competition for space between mussels and macroalgae. Whenever Littorina was excluded, the canopy of Fucus spp. increased continuously and reached total cover within two years. In addition to the increase of Fucus spp., the rock surface and the mussel shells were overgrown by Ulva pseudocurvata, which covered the experimental fields during parts of the summer in the absence of herbivores. As soon as perennial species (fucoids) covered most of the experimental areas, the seasonal growth of Ulva decreased drastically. Presence and growth of macroalgae were also controlled by serious competition for space with mussels. Established Mytilus prevented the growth of all perennial and ephemeral algae on the rocks. However, the shells of the mussels provided free space for a new settlement of Fucus and Ulva. In the lower intertidal (dominated by total algal cover

  6. Realistic changes in seaweed biodiversity affect multiple ecosystem functions on a rocky shore.

    PubMed

    Bracken, Matthew E S; Williams, Susan L

    2013-09-01

    Given current threats to biodiversity, understanding the effects of diversity changes on the functions and services associated with intact ecosystems is of paramount importance. However, limited realism in most biodiversity studies makes it difficult to link the large and growing body of evidence for important functional consequences of biodiversity change to real-world losses of biodiversity. Here, we explored two methods of incorporating realism into biodiversity research: (1) the use of two-, five-, and eight-species assemblages that mimicked those that we observed in surveys of seaweed biodiversity patterns on a northern California (USA) rocky shore and the explicit comparison of those assemblages to random assemblages compiled from the same local species pool; and (2) the measurement of two fundamental ecosystem functions, nitrate uptake and photosynthesis, both of which contribute to growth of primary producers. Specifically, we measured nitrate uptake rates of seaweed assemblages as a function of initial nitrate concentrations and photosynthetic rates as a function of irradiance levels for both realistic and random assemblages of seaweeds. We only observed changes in ecosystem functioning along a richness gradient for realistic assemblages, and both maximum nitrate uptake rates (V(max)) and photosynthetic light use efficiency values (alpha(p) = P(max)/I(K)) were higher in realistic assemblages than in random assemblages. Furthermore, the parameter affected by changes in richness depended on the function being measured. Both V(max) and alpha(p) declined with increasing richness in nonrandom assemblages due to a combination of species identity effects (for V(max) and overyielding effects (for both V(max) and alpha(p)). In contrast, neither nitrate uptake efficiency values (alpha(N) = V(max)/K(s)), nor maximum photosynthetic rates (Pmax) changed along the gradient in seaweed species richness. Furthermore, overyielding was only evident in realistic assemblages

  7. Spatial and temporal patterns of subtidal and intertidal crabs excursions

    NASA Astrophysics Data System (ADS)

    Silva, A. C. F.; Boaventura, D. M.; Thompson, R. C.; Hawkins, S. J.

    2014-01-01

    Highly mobile predators such as fish and crabs are known to migrate from the subtidal zone to forage in the intertidal zone at high-tide. The extent and variation of these habitat linking movements along the vertical shore gradient have not been examined before for several species simultaneously, hence not accounting for species interactions. Here, the foraging excursions of Carcinus maenas (L.), Necora puber (Linnaeus, 1767) and Cancer pagurus (Linnaeus, 1758) were assessed in a one-year mark-recapture study on two replicated rocky shores in southwest U.K. A comparison between the abundance of individuals present on the shore at high-tide with those present in refuges exposed at low-tide indicated considerable intertidal migration by all species, showing strong linkage between subtidal and intertidal habitats. Estimates of population size based on recapture of marked individuals indicated that an average of ~ 4000 individuals combined for the three crab species, can be present on the shore during one tidal cycle. There was also a high fidelity of individuals and species to particular shore levels. Underlying mechanisms for these spatial patterns such as prey availability and agonistic interactions are discussed. Survival rates were estimated using the Cormack-Jolly-Seber model from multi-recapture analysis and found to be considerably high with a minimum of 30% for all species. Growth rates were found to vary intraspecifically with size and between seasons. Understanding the temporal and spatial variations in predation pressure by crabs on rocky shores is dependent on knowing who, when and how many of these commercially important crab species depend on intertidal foraging. Previous studies have shown that the diet of these species is strongly based on intertidal prey including key species such as limpets; hence intertidal crab migration could be associated with considerable impacts on intertidal assemblages.

  8. Systematic Analysis of Rocky Shore Morphology along 700km of Coastline Using LiDAR-derived DEMs

    NASA Astrophysics Data System (ADS)

    Matsumoto, H.; Dickson, M. E.; Masselink, G.

    2016-12-01

    Rock shore platforms occur along much of the world's coast and have a long history of study; however, uncertainty remains concerning the relative importance of various formative controls in different settings (e.g. wave erosion, weathering, tidal range, rock resistance, inheritance). Ambiguity is often attributed to intrinsic natural variability and the lack of preserved evidence on eroding rocky shores, but it could also be argued that previous studies are limited in scale, focusing on a small number of local sites, which restricts the potential for insights from broad, regional analyses. Here we describe a method, using LiDAR-derived digital elevation models (DEMs), for analysing shore platform morphology over an unprecedentedly wide area in which there are large variations in environmental conditions. The new method semi-automatically extracts shore platform profiles and systematically conducts morphometric analysis. We apply the method to 700 km of coast in the SW UK that is exposed to (i) highly energetic swell waves to local wind waves, (ii) macro to mega tidal ranges, and (iii) highly resistant igneous rocks to moderately hard sedimentary rocks. Computer programs are developed to estimate mean sea level, mean spring tidal range, wave height, and rock strength along the coastline. Filtering routines automatically select and remove profiles that are unsuitable for analysis. The large data-set of remaining profiles supports broad and systematic investigation of possible controls on platform morphology. Results, as expected, show wide scatter, because many formative controls are in play, but several trends exist that are generally consistent with relationships that have been inferred from local site studies. This paper will describe correlation analysis on platform morphology in relation to environmental conditions and also present a multi-variable empirical model derived from multi linear regression analysis. Interesting matches exist between platform gradients

  9. Systematic analysis of rocky shore platform morphology at large spatial scale using LiDAR-derived digital elevation models

    NASA Astrophysics Data System (ADS)

    Matsumoto, Hironori; Dickson, Mark E.; Masselink, Gerd

    2017-06-01

    Much of the existing research on rocky shore platforms describes results from carefully selected field sites, or comparisons between a relatively small number of selected sites. Here we describe a method to systematically analyse rocky shore morphology over a large area using LiDAR-derived digital elevation models. The method was applied to 700 km of coastline in southwest England; a region where there is considerable variation in wave climate and lithological settings, and a large alongshore variation in tidal range. Across-shore profiles were automatically extracted at 50 m intervals around the coast where information was available from the Coastal Channel Observatory coastal classification. Routines were developed to automatically remove non-platform profiles. The remaining 612 shore platform profiles were then subject to automated morphometric analyses, and correlation analysis in respect to three possible environmental controls: wave height, mean spring tidal range and rock strength. As expected, considerable scatter exists in the correlation analysis because only very coarse estimates of rock strength and wave height were applied, whereas variability in factors such as these can locally be the most important control on shoreline morphology. In view of this, it is somewhat surprising that overall consistency was found between previous published findings and the results from the systematic, automated analysis of LiDAR data: platform gradient increases as rock strength and tidal range increase, but decreases as wave height increases; platform width increases as wave height and tidal range increase, but decreases as rock strength increases. Previous studies have predicted shore platform gradient using tidal range alone. A multi-regression analysis of LiDAR data confirms that tidal range is the strongest predictor, but a new multi-factor empirical model considering tidal range, wave height, and rock strength yields better predictions of shore platform gradient

  10. The effect of intertidal ice in the shore platform evolution. Results from South Shetland Islands (Antarctica).

    NASA Astrophysics Data System (ADS)

    Neves, Mario; Vieira, Gonçalo; Ramos, Miguel; Batista, Vanessa

    2010-05-01

    The genesis and the evolution of shore platforms on sub-polar regions, in areas sheltered from wave action, has been mainly imputed to ice erosion caused by the movement of floating ice forced by tide levels variation. Nevertheless, this process has never been accurately studied. This research aims to clearly identify shore platforms that evolve by floating ice erosion process and assess the downwearing rate of those platforms. To achieve this purpose, we used a TMEM (Traversing Micro-Erosion Meter), which is one of the few field equipments that can supply very precise (accuracy of 0.001 mm) erosion data of rock surfaces for periods of one month to several years. Two experimental areas were chosen in Deception and Livingston islands (South Shetland Group - Maritime Antarctica) at places where sea wave's action is meaningless. Deception Island is an active shield volcano with 109 km2 located between latitudes 62° 54' - 63° 01' S and longitudes 60° 29' - 60° 45' W. This island has a horseshoe shape that almost totally encloses a 7-10 km in diameter bay known as Port Foster with a narrow (500m wide) and thin (less than 20m deep) connection to the open sea. A TMEM station was installed in 30 January 2007, at 1.3m above chart data, in the inner part of the bay, near Punta Murature. Cut in the Pendulum Cove Formation, mainly composed of tuff cone and maar deposits, locally the shore platform shows a well consolidated stratified lapilli tuffs with abundant accessory clasts forming an almost flat, but very irregular in the detail, rock surface. Livingstone Island has 845 km2 and is located between latitudes 62° 27' - 62°48' S and longitudes 59° 45' - 61° 15' W, around 25 km north of Deception Island. A TMEM station was installed in the NW sector of the Hurd Peninsula in 5 February 2007 at Punta Polaca, at 1.4m above chart datum, on a very smooth rock surface with an inclination of 5.5°, cut in quartzites of the Miers Bluff formation. The 2008 campaign achieved the

  11. Climate-driven interactions among rocky intertidal organisms caught between a rock and a hot place.

    PubMed

    Bertness, Mark D; Leonard, George H; Levine, Jonathan M; Bruno, John F

    1999-08-01

    To explore how climate may affect the structure of natural communities, we quantified the role of thermal stress in setting the high intertidal borders of the acorn barnacle, Semibalanus balanoides. At sites north and south of Cape Cod, a major faunal and thermal boundary on the east coast of North America, we examined the interacting effects of thermal stress and recruit density on individual survivorship. At hotter southern sites, particularly in bays, high intertidal barnacle survivorship was enhanced by experimental shading or by neighbors which ameliorate heat and desiccation stresses. In contrast, at cooler northern bay and coastal sites, neither shading nor group benefits increased barnacle survival, and mortality patterns were driven primarily by predators with largely boreal distributions. Our field results, like recent laboratory microcosm studies, suggest that predicting even simple community responses to climate change may be more complex than is currently appreciated.

  12. [Secondary productivity of macrobenthos in rocky intertidal zone of Yushan Islands, Zhejiang Province].

    PubMed

    Jiao, Hai-feng; Shi, Hui-xiong; You, Zhong-jie; Lou, Zhi-jun; Liu, Hong-dan; Jin, Xin-fei

    2011-08-01

    In order to understand the current status of macrobenthos in intertidal zone of Yushan Islands, macrobenthos samples were collected from 5 sections in the intertidal zone in four seasons from March 2009 to January 2010, with the density, biomass, secondary productivity, and P/B value of the macrobenthos investigated by using Brey's empirical formula. The mean density of the marobenthos was 1419.5 ind x m(-2), mean biomass in ash free dry mass (AFDM) was 565.53 g x m(-2), mean annual secondary productivity was 285.58 g x m(-2) x a(-1) (AFDM), and mean annual P/B value was 0.51. The secondary productivity was mainly affected by mollusca and gastropda, with five critical species Septifer virgatus, Modiolus modiolus, Serpulorbis imbricata, Tetraclita japonica, and T. squamosa contributed 84.0% of the total. The P/B value in the study area was lower than that in other sea areas, showing that the generation turnover rate of the macrobenthos in the intertidal zone of Yushan Islands was slower, and the community structure was more stable.

  13. Ocean Acidification and Increased Temperature Have Both Positive and Negative Effects on Early Ontogenetic Traits of a Rocky Shore Keystone Predator Species

    PubMed Central

    Manríquez, Patricio H.; Jara, María Elisa; Seguel, Mylene E.; Torres, Rodrigo; Alarcon, Emilio; Lee, Matthew R.

    2016-01-01

    The combined effect of ocean acidification and warming is expected to have significant effects on several traits of marine organisms. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal habitats of southern Chile (39°S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits. The individuals were exposed long-term (5.8 months) to contrasting pCO2 (ca. 500 and 1400 μatm) and temperature (15 and 19°C) levels. After this period we compared body growth traits, dislodgement resistance, predator-escape response, self-righting and metabolic rates. With respect to these traits there was no evidence of a synergistic interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15°C. High pCO2 levels also had a negative effect on the predator-escape response. Conversely, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour. We conclude that climate change might produce in C. concholepas positive and negative effects in physiology and behaviour. In fact, some of the behavioural responses might be a consequence of physiological effects, such as changes in chemosensory capacity (e.g. predator-escape response) or secretion of adhesive mucous (e.g. dislodgement resistance). Moreover, we conclude that positive behavioural responses may assist in the adaptation

  14. Ocean Acidification and Increased Temperature Have Both Positive and Negative Effects on Early Ontogenetic Traits of a Rocky Shore Keystone Predator Species.

    PubMed

    Manríquez, Patricio H; Jara, María Elisa; Seguel, Mylene E; Torres, Rodrigo; Alarcon, Emilio; Lee, Matthew R

    2016-01-01

    The combined effect of ocean acidification and warming is expected to have significant effects on several traits of marine organisms. The gastropod Concholepas concholepas is a rocky shore keystone predator characteristic of the south-eastern Pacific coast of South America and an important natural resource exploited by small-scale artisanal fishermen along the coast of Chile and Peru. In this study, we used small juveniles of C. concholepas collected from the rocky intertidal habitats of southern Chile (39 °S) to evaluate under laboratory conditions the potential consequences of projected near-future levels of ocean acidification and warming for important early ontogenetic traits. The individuals were exposed long-term (5.8 months) to contrasting pCO2 (ca. 500 and 1400 μatm) and temperature (15 and 19 °C) levels. After this period we compared body growth traits, dislodgement resistance, predator-escape response, self-righting and metabolic rates. With respect to these traits there was no evidence of a synergistic interaction between pCO2 and temperature. Shell growth was negatively affected by high pCO2 levels only at 15 °C. High pCO2 levels also had a negative effect on the predator-escape response. Conversely, dislodgement resistance and self-righting were positively affected by high pCO2 levels at both temperatures. High tenacity and fast self-righting would reduce predation risk in nature and might compensate for the negative effects of high pCO2 levels on other important defensive traits such as shell size and escape behaviour. We conclude that climate change might produce in C. concholepas positive and negative effects in physiology and behaviour. In fact, some of the behavioural responses might be a consequence of physiological effects, such as changes in chemosensory capacity (e.g. predator-escape response) or secretion of adhesive mucous (e.g. dislodgement resistance). Moreover, we conclude that positive behavioural responses may assist in the

  15. Composition and activity of beta-Proteobacteria ammonia-oxidizing communities associated with intertidal rocky biofilms and sediments of the Douro River estuary, Portugal.

    PubMed

    Magalhães, C; Bano, N; Wiebe, W J; Hollibaugh, J T; Bordalo, A A

    2007-10-01

    To characterize the phylogenetic composition of ammonia-oxidizing bacteria (AOB) of the beta-subclass of the class Proteobacteria in intertidal sediment and rocky biofilms of the Douro estuary, and evaluate relationships with environmental variables and N-biogeochemistry. Cluster analysis of denaturing gradient gel electrophoresis profiles showed differences in beta-Proteobacteria AOB assemblage composition between rocky biofilms and sediments. All sequences obtained from intertidal rocky biofilm sites exhibited phylogenetic affinity to Nitrosomonas sp. lineages, whereas a majority of the sequences from the sediment sites were most similar to marine Nitrosospira cluster 1. Hierarchical cluster analysis based on environmental variables identified two main groups of samples. The first contained samples from rocky biofilm sites characterized by high concentrations of NO2- and NH4+, and high organic matter and chlorophyll a content. The second group contained all of the sediment samples; these sites were characterized by lower values for the variables above. In addition, rocky biofilm sites exhibited higher nitrification rates. Intersite differences in environmental and/or physical conditions led to the selection of different populations of beta-Proteobacteria AOB, supporting different magnitudes of N-cycling regimes. This study represents an important step in establishing the influence of environmental factors on the distribution of beta-Proteobacteria AOB with possible consequences for N-biogeochemistry.

  16. Optimal diets in complex environments: feeding strategies of two herbivorous fishes from a temperate rocky intertidal zone.

    PubMed

    Horn, M H

    1983-06-01

    The seasonal diets of Cebidichthys violaceus and Xiphister mucosus, two herbivorous fishes from the complex, multifood environment of the central California rocky intertidal zone, were partially consistent with three predictions of optimal diet models based on energy maximization: 1) The prediction that at high food densities a forager should concentrate solely on the energetically most valuable items was incompletely met by these two fish species. C. violaceus and X. mucosus increased their consumption of energy-rich annual macrophytes during periods (summer and fall) of high food abundance, but nevertheless continued to take a mixed diet. 2) The prediction that abundance of lower-valued foods does not determine their inclusion in the diet was largely upheld by the feeding habits of these two intertidal fishes. The probability of an item being consumed apparently depends upon its abundance as well as its chemical composition. 3) The prediction that foragers will generalize as food abundance declines was largely met by the two fishes since their diets broadened considerably during periods (e.g. winter) of reduced food supply. Furthermore, diets of the two species converged during periods of high food abundance and diverged during months of low food abundance. Whether this seasonal pattern of overlap was due to interspecific competition or other factors is unknown. This study, in agreement with other recent investigations, indicates that optimal diet models cannot be based solely on energy maximization but should also include nutrient constraints in order to more accurately predict the seasonally fluctuating mixed diets of these fishes and other generalist herbivores.

  17. Sea Otters Homogenize Mussel Beds and Reduce Habitat Provisioning in a Rocky Intertidal Ecosystem

    PubMed Central

    Singh, Gerald G.; Markel, Russell W.; Martone, Rebecca G.; Salomon, Anne K.; Harley, Christopher D. G.; Chan, Kai M. A.

    2013-01-01

    Sea otters (Enhydra lutris) are keystone predators that consume a variety of benthic invertebrates, including the intertidal mussel, Mytilus californianus. By virtue of their competitive dominance, large size, and longevity, M. californianus are ecosystem engineers that form structurally complex beds that provide habitat for diverse invertebrate communities. We investigated whether otters affect mussel bed characteristics (i.e. mussel length distributions, mussel bed depth, and biomass) and associated community structure (i.e. biomass, alpha and beta diversity) by comparing four regions that varied in their histories of sea otter occupancy on the west coast of British Columbia and northern Washington. Mussel bed depth and average mussel lengths were 1.5 times lower in regions occupied by otters for >20 years than those occupied for <5 yrs. Diversity of mussel bed associated communities did not differ between regions; however, the total biomass of species associated with mussel beds was more than three-times higher where sea otters were absent. We examined alternative explanations for differences in mussel bed community structure, including among-region variation in oceanographic conditions and abundance of the predatory sea star Pisaster ochraceus. We cannot discount multiple drivers shaping mussel beds, but our findings indicate the sea otters are an important one. We conclude that, similar to their effects on subtidal benthic invertebrates, sea otters reduce the size distributions of intertidal mussels and, thereby, habitat available to support associated communities. Our study indicates that by reducing populations of habitat-providing intertidal mussels, sea otters may have substantial indirect effects on associated communities. PMID:23717697

  18. Sea otters homogenize mussel beds and reduce habitat provisioning in a rocky intertidal ecosystem.

    PubMed

    Singh, Gerald G; Markel, Russell W; Martone, Rebecca G; Salomon, Anne K; Harley, Christopher D G; Chan, Kai M A

    2013-01-01

    Sea otters (Enhydra lutris) are keystone predators that consume a variety of benthic invertebrates, including the intertidal mussel, Mytilus californianus. By virtue of their competitive dominance, large size, and longevity, M. californianus are ecosystem engineers that form structurally complex beds that provide habitat for diverse invertebrate communities. We investigated whether otters affect mussel bed characteristics (i.e. mussel length distributions, mussel bed depth, and biomass) and associated community structure (i.e. biomass, alpha and beta diversity) by comparing four regions that varied in their histories of sea otter occupancy on the west coast of British Columbia and northern Washington. Mussel bed depth and average mussel lengths were 1.5 times lower in regions occupied by otters for >20 years than those occupied for <5 yrs. Diversity of mussel bed associated communities did not differ between regions; however, the total biomass of species associated with mussel beds was more than three-times higher where sea otters were absent. We examined alternative explanations for differences in mussel bed community structure, including among-region variation in oceanographic conditions and abundance of the predatory sea star Pisaster ochraceus. We cannot discount multiple drivers shaping mussel beds, but our findings indicate the sea otters are an important one. We conclude that, similar to their effects on subtidal benthic invertebrates, sea otters reduce the size distributions of intertidal mussels and, thereby, habitat available to support associated communities. Our study indicates that by reducing populations of habitat-providing intertidal mussels, sea otters may have substantial indirect effects on associated communities.

  19. Non-Linear Interactions between Consumers and Flow Determine the Probability of Plant Community Dominance on Maine Rocky Shores

    PubMed Central

    Silliman, Brian R.; McCoy, Michael W.; Trussell, Geoffrey C.; Crain, Caitlin M.; Ewanchuk, Patrick J.; Bertness, Mark D.

    2013-01-01

    Although consumers can strongly influence community recovery from disturbance, few studies have explored the effects of consumer identity and density and how they may vary across abiotic gradients. On rocky shores in Maine, recent experiments suggest that recovery of plant- or animal- dominated community states is governed by rates of water movement and consumer pressure. To further elucidate the mechanisms of consumer control, we examined the species-specific and density-dependent effects of rocky shore consumers (crabs and snails) on community recovery under both high (mussel dominated) and low flow (plant dominated) conditions. By partitioning the direct impacts of predators (crabs) and grazers (snails) on community recovery across a flow gradient, we found that grazers, but not predators, are likely the primary agent of consumer control and that their impact is highly non-linear. Manipulating snail densities revealed that herbivorous and bull-dozing snails (Littorina littorea) alone can control recovery of high and low flow communities. After ∼1.5 years of recovery, snail density explained a significant amount of the variation in macroalgal coverage at low flow sites and also mussel recovery at high flow sites. These density-dependent grazer effects were were both non-linear and flow-dependent, with low abundance thresholds needed to suppress plant community recovery, and much higher levels needed to control mussel bed development. Our study suggests that consumer density and identity are key in regulating both plant and animal community recovery and that physical conditions can determine the functional forms of these consumer effects. PMID:23940510

  20. Current patterns of macroalgal diversity and biomass in northern hemisphere rocky shores.

    PubMed

    Konar, Brenda; Iken, Katrin; Cruz-Motta, Juan José; Benedetti-Cecchi, Lisandro; Knowlton, Ann; Pohle, Gerhard; Miloslavich, Patricia; Edwards, Matt; Trott, Thomas; Kimani, Edward; Riosmena-Rodriguez, Rafael; Wong, Melisa; Jenkins, Stuart; Silva, Angelica; Pinto, Isabel Sousa; Shirayama, Yoshihisa

    2010-10-07

    Latitudinal gradients in species abundance and diversity have been postulated for nearshore taxa but few analyses have been done over sufficiently broad geographic scales incorporating various nearshore depth strata to empirically test these gradients. Typically, gradients are based on literature reviews and species lists and have focused on alpha diversity across the entire nearshore zone. No studies have used a standardized protocol in the field to examine species density among sites across a large spatial scale while also focusing on particular depth strata. The present research used field collected samples in the northern hemisphere to explore the relationships between macroalgal species density and biomass along intertidal heights and subtidal depths and latitude. Results indicated no overall correlations between either estimates of species density or biomass with latitude, although the highest numbers of both were found at mid-latitudes. However, when strata were examined separately, significant positive correlations were found for both species numbers and biomass at particular strata, namely the intertidal ones. While the data presented in this paper have some limitations, we show that latitudinal macroalgal trends in species density and biomass do exist for some strata in the northern hemisphere with more taxa and biomass at higher latitudes.

  1. Floating mucus aggregates derived from benthic microorganisms on rocky intertidal reefs: Potential as food sources for benthic animals

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Tsuchiya, M.

    2011-09-01

    Mucus films, flocs or foams consisting of fine sand, algae and detritus frequently occur in the surface waters of rocky intertidal reef flats during incoming tide. These masses are referred to as mucus aggregates. We examined the developmental process of mucus aggregates and their abundance, distribution, migration and trophic composition. The trophic composition of mucus aggregates was then compared to those of sediments to evaluate their potential nutritional value for benthic animals. The organic matter content, chlorophyll a concentration, microalgal density and bacteria-derived fatty acid contents of mucus aggregates were higher than those observed in sediment, suggesting that mucus aggregates contain not only high levels of organic matter but also dense concentrations of microalgae and bacteria; therefore, mucus aggregates may serve as a qualitatively more energetic food source for benthic fauna compared to sediments. Benthic diatoms were the most abundant organisms in mucus aggregates. Large numbers of diatoms were trapped in fine mineral particles and mucilage-like strings, suggesting that a portion of the mucus is secreted by these benthic microalgae. Mucus aggregate accounted for only 0.01-3.9% of the daily feeding requirements of the dominant detritivore, Ophiocoma scolopendrina (Echinodermata: Ophiuroidea) over the entire sampling area. In contrast, for the species population on the back reef, where mucus aggregates ultimately accumulate, mucus aggregates provided from 0.4 to 113.3% of food for this species. These results suggest that mucus aggregate availability varies spatiotemporally and that they do not always provide adequate food sources for O. scolopendrina populations.

  2. Response of a rocky intertidal ecosystem engineer and community dominant to climate change.

    PubMed

    Menge, Bruce A; Chan, Francis; Lubchenco, Jane

    2008-02-01

    To evaluate how climate change might impact a competitively dominant ecological engineer, we analysed the growth response of the mussel Mytilus californianus to climate patterns [El Niño-Southern Oscillation, Pacific Decadal Oscillation (PDO)]. Mussels grew faster during warmer climatic events. Growth was initially faster on a more productive cape compared to a less productive cape. Growth rates at the two capes merged in 2002, coincidentally with a several year-long shift from warm to cool PDO conditions. To determine the mechanism underlying this response, we examined growth responses to intertidal sea and air temperatures, phytoplankton, sea level and tide height. Together, water temperature (32%) and food (12.5%) explained 44.5% of the variance in mussel growth; contributions of other factors were not significant. In turn, water temperature and food respond to climate-driven variation in upwelling and other, unknown factors. Understanding responses of ecosystem engineers to climate change will require knowing direct thermal effects and indirect effects of factors altered by temperature change.

  3. Current status and multidecadal biogeographical changes in rocky intertidal algal assemblages: The northern Spanish coast

    NASA Astrophysics Data System (ADS)

    Fernández, C.

    2016-03-01

    The biogeographic border between the Eastern and the Atlantic subregions of the Lusitanian Province situated on the west coast of Asturias (N. of Spain) has moved westwards in recent years. A comparative study, consisting in a resurvey of 20 shores sampled in 1977, covering 200 km showed a large-scale change affecting the mid and low eulittoral. Cold-temperate canopy species such as kelps (Laminaria hyperborea, Laminaria. ochroleuca and Saccorhiza polyschides), fucoids (Fucus serratus, Fucus vesiculosus and Himanthalia elongata) and Chondrus crispus have almost disappeared and replaced by warm-temperate species such as Cystoseira baccata, Cystoseira tamariscifolia, Bifurcaria bifurcata and coralline algae (Ellisolandia elongata, Lithophyllum incrustans and Mesophyllum lichenoides). The loss of canopy-species can have consequences for the assemblage, especially in the case of fucoid-dominated assemblages.

  4. Genetic Structure Among 50 Species of the Northeastern Pacific Rocky Intertidal Community

    PubMed Central

    Kelly, Ryan P.; Palumbi, Stephen R.

    2010-01-01

    Comparing many species' population genetic patterns across the same seascape can identify species with different levels of structure, and suggest hypotheses about the processes that cause such variation for species in the same ecosystem. This comparative approach helps focus on geographic barriers and selective or demographic processes that define genetic connectivity on an ecosystem scale, the understanding of which is particularly important for large-scale management efforts. Moreover, a multispecies dataset has great statistical advantages over single-species studies, lending explanatory power in an effort to uncover the mechanisms driving population structure. Here, we analyze a 50-species dataset of Pacific nearshore invertebrates with the aim of discovering the most influential structuring factors along the Pacific coast of North America. We collected cytochrome c oxidase I (COI) mtDNA data from populations of 34 species of marine invertebrates sampled coarsely at four coastal locations in California, Oregon, and Alaska, and added published data from 16 additional species. All nine species with non-pelagic development have strong genetic structure. For the 41 species with pelagic development, 13 show significant genetic differentiation, nine of which show striking FST levels of 0.1–0.6. Finer scale geographic investigations show unexpected regional patterns of genetic change near Cape Mendocino in northern California for five of the six species tested. The region between Oregon and Alaska is a second focus of intraspecific genetic change, showing differentiation in half the species tested. Across regions, strong genetic subdivision occurs more often than expected in mid-to-high intertidal species, a result that may reflect reduced gene flow due to natural selection along coastal environmental gradients. Finally, the results highlight the importance of making primary research accessible to policymakers, as unexpected barriers to marine dispersal break the

  5. Genetic structure among 50 species of the northeastern Pacific rocky intertidal community.

    PubMed

    Kelly, Ryan P; Palumbi, Stephen R

    2010-01-07

    Comparing many species' population genetic patterns across the same seascape can identify species with different levels of structure, and suggest hypotheses about the processes that cause such variation for species in the same ecosystem. This comparative approach helps focus on geographic barriers and selective or demographic processes that define genetic connectivity on an ecosystem scale, the understanding of which is particularly important for large-scale management efforts. Moreover, a multispecies dataset has great statistical advantages over single-species studies, lending explanatory power in an effort to uncover the mechanisms driving population structure. Here, we analyze a 50-species dataset of Pacific nearshore invertebrates with the aim of discovering the most influential structuring factors along the Pacific coast of North America. We collected cytochrome c oxidase I (COI) mtDNA data from populations of 34 species of marine invertebrates sampled coarsely at four coastal locations in California, Oregon, and Alaska, and added published data from 16 additional species. All nine species with non-pelagic development have strong genetic structure. For the 41 species with pelagic development, 13 show significant genetic differentiation, nine of which show striking FST levels of 0.1-0.6. Finer scale geographic investigations show unexpected regional patterns of genetic change near Cape Mendocino in northern California for five of the six species tested. The region between Oregon and Alaska is a second focus of intraspecific genetic change, showing differentiation in half the species tested. Across regions, strong genetic subdivision occurs more often than expected in mid-to-high intertidal species, a result that may reflect reduced gene flow due to natural selection along coastal environmental gradients. Finally, the results highlight the importance of making primary research accessible to policymakers, as unexpected barriers to marine dispersal break the

  6. Competition and habitat suitability: small-scale segregation underpins large-scale coexistence of key species on temperate rocky shores.

    PubMed

    Firth, Louise Bridget; Crowe, Tasman P

    2010-01-01

    Identifying the mechanisms that underpin species richness is one of the central issues of community ecology. On rocky shores in north-western Europe, two key limpet species coexist on the mid- and low shore but are segregated at small scales with respect to habitat. Shortterm and long-term experiments were done to test whether habitat suitability or habitat-specific competition drives the small-scale segregation of these species and therefore underpins their coexistence at larger spatial scales. In a controlled short-term experiment, Patella vulgata was transplanted onto open rock and into pools that either contained Patella ulyssiponensis and/or their mucus or from which P. ulyssiponensis and/or their mucus had been removed. After 2 days, P. vulgata remained in all experimental plots in similar numbers irrespective of treatment indicating that there was no negative response to P. ulyssiponensis, mucus or the pool habitat. In a long-term experiment, cage enclosures containing both species were set up in pools and on open rock over a 6-month period. P. vulgata grew equally well on both open rock and in pools but suffered higher mortality in pools. P. ulyssiponensis showed lower growth rate and higher mortality on open rock than in pools. P. ulyssiponensis exhibited increased growth in higher intraspecific densities on open rock and reduced growth in higher intraspecific densities in pools, indicating some degree of intraspecific facilitation on open rock and intraspecific competition in pools. There was no evidence of interspecific competition either in the short term or in the long term. Results revealed that habitat suitability was the mechanism causing segregation of these species at smaller spatial scales enabling them to coexist at larger spatial scales. Conflicting results in the short-term and long-term experiments highlight the importance of considering the correct temporal extent for experimental tests of hypotheses.

  7. Tracer experiment and model evidence for macrofaunal shaping of microbial nitrogen functions along rocky shores

    NASA Astrophysics Data System (ADS)

    Pfister, Catherine A.; Altabet, Mark A.; Pather, Santhiska; Dwyer, Greg

    2016-06-01

    Seawater microbes as well as those associated with macrobiota are increasingly recognized as a key feature affecting nutrient cycling. Tidepools are ideal natural mesocosms to test macrofauna and microbe interactions, and we quantified rates of microbial nitrogen processing using tracer enrichment of ammonium (15NNH4) or nitrate (15NNO3) when tidepools were isolated from the ocean during low intertidal periods. Experiments were conducted during both day and night as well as in control tidepools and those from which mussels had been removed, allowing us to determine the role of both mussels and daylight in microbial nitrogen processing. We paired time series observations of 15N enrichment in NH4+, NO2- and NO3- with a differential equation model to quantify multiple, simultaneous nitrogen transformations. Mussel presence and daylight increased remineralization and photosynthetic nitrogen uptake. When we compared ammonium gain or loss that was attributed to any tidepool microbes vs. photosynthetic uptake, microbes accounted for 32 % of this ammonium flux on average. Microbial transformations averaged 61 % of total nitrate use; thus, microbial activity was almost 3 times that of photosynthetic nitrate uptake. Because it accounted for processes that diluted our tracer, our differential equation model assigned higher rates of nitrogen processing compared to prior source-product models. Our in situ experiments showed that animals alone elevate microbial nitrogen transformations by 2 orders of magnitude, suggesting that coastal macrobiota are key players in complex microbial nitrogen transformations.

  8. Long-term changes in rocky intertidal macrobenthos during the five years after the Hebei Spirit oil spill, Taean, Korea

    NASA Astrophysics Data System (ADS)

    Jung, Yun-Hwan; Park, Henug-Sik; Yoon, Kon-Tak; Kim, Hyung-June; Shim, Won-Joon

    2017-03-01

    The Hebei Spirit oil spill reached the west coast of Taean County, Korea, on December 7, 2007. At that time, this was the largest oil spill that had occurred in the country. The incident devastated local marine ecosystems. In this study, we examined changes in these ecosystems and the recovery pattern on impacted rocky shores. Macrobenthos monitoring of polluted and control sites was performed seasonally from January 2008 through October 2013. At polluted sites, ecological indices increased gradually from 2009, thereby providing evidence of recovery. However, the mean density of macrobenthos was still less than 50% of the level at the control site, indicating that the ecological status of the polluted sites has still not recovered to that which prevailed before the oil spill. Although densities of the most dominant species were higher in the control site than in polluted sites, the densities of Lottia spp. and Odostomia aomori were higher in polluted sites. These two taxa were found in lower numbers at the control site, where they were out-competed by Chthamalus challengeri. Nonmetric multidimensional scaling ordination divided the macrobenthic community structure into three clusters according to differences in the abundance of dominant species over the 6 years after the oil spill. An ANOSIM test detected significant differences between the polluted and control sites. Consistent long-term differences indicate that complete recovery had not occurred during the duration of our study.

  9. Long-term changes in rocky intertidal macrobenthos during the five years after the Hebei Spirit oil spill, Taean, Korea

    NASA Astrophysics Data System (ADS)

    Jung, Yun-Hwan; Park, Henug-Sik; Yoon, Kon-Tak; Kim, Hyung-June; Shim, Won-Joon

    2017-02-01

    The Hebei Spirit oil spill reached the west coast of Taean County, Korea, on December 7, 2007. At that time, this was the largest oil spill that had occurred in the country. The incident devastated local marine ecosystems. In this study, we examined changes in these ecosystems and the recovery pattern on impacted rocky shores. Macrobenthos monitoring of polluted and control sites was performed seasonally from January 2008 through October 2013. At polluted sites, ecological indices increased gradually from 2009, thereby providing evidence of recovery. However, the mean density of macrobenthos was still less than 50% of the level at the control site, indicating that the ecological status of the polluted sites has still not recovered to that which prevailed before the oil spill. Although densities of the most dominant species were higher in the control site than in polluted sites, the densities of Lottia spp. and Odostomia aomori were higher in polluted sites. These two taxa were found in lower numbers at the control site, where they were out-competed by Chthamalus challengeri. Nonmetric multidimensional scaling ordination divided the macrobenthic community structure into three clusters according to differences in the abundance of dominant species over the 6 years after the oil spill. An ANOSIM test detected significant differences between the polluted and control sites. Consistent long-term differences indicate that complete recovery had not occurred during the duration of our study.

  10. Abundance of Petrolisthes armatus (Crustacea: Porcellanidae) on a tropical estuarine intertidal rocky beach, Gulf of Nicoya estuary, Costa Rica.

    PubMed

    Díaz-Ferguson, E; Vargas-Zamora, J A

    2001-12-01

    Population of the porcellanid crab Petrolisthes armatus was studied on a rocky intertidal beach located at the Punta Morales peninsula in the mid upper Gulf of Nicoya estuary, Pacific coast of Costa Rica, from December 1997 to November 1998 (14 dates). Horizontal plankton tows (280 micron mesh net) were also made to verify the presence of P. armatus larvae. Crabs were collected every 3 m along three 18 m long transects, at two sites on the beach, by placing a bottomless bucket fringed with canvas to prevent the organisms from escaping under the rim. A total of 15,382 P. armatus were collected. Only 146 (0.95%) crabs had a carapace length longer than 10 mm, and 8995 (58.5%) were in the size range of 2 to 4.5 mm. The remaining crabs 6241 (40.5%) were in the size range of 4.6 to 10 mm. Male and female P. armatus were represented by 2777 and 3518 individuals respectively, with a sex ratio of 1:1.26. Ovigerous females were found at all dates and included 2937 individuals (83% of females). Plankton tows yielded only 73 larvae of P. armatus (Zoea 1), with a density of 1.2 larvae/m3. No statistically significant seasonal trends in the population of this species were detected. P. armatus appears to reproduce continuously the year around in Punta Morales, and some peaks of abundance were present during the dry and rainy seasons. These trends are similar to trends reported for other crustacean species in the Gulf of Nicoya.

  11. Historical and recent processes shaping the geographic range of a rocky intertidal gastropod: phylogeography, ecology, and habitat availability.

    PubMed

    Fenberg, Phillip B; Posbic, Karine; Hellberg, Michael E

    2014-08-01

    Factors shaping the geographic range of a species can be identified when phylogeographic patterns are combined with data on contemporary and historical geographic distribution, range-wide abundance, habitat/food availability, and through comparisons with codistributed taxa. Here, we evaluate range dynamism and phylogeography of the rocky intertidal gastropod Mexacanthina lugubris lugubris across its geographic range - the Pacific coast of the Baja peninsula and southern California. We sequenced mitochondrial DNA (CO1) from ten populations and compliment these data with museum records, habitat availability and range-wide field surveys of the distribution and abundance of M. l. lugubris and its primary prey (the barnacle Chthamalus fissus). The geographic range of M. l. lugubris can be characterized by three different events in its history: an old sundering in the mid-peninsular region of Baja (∼ 417,000 years ago) and more recent northern range expansion and southern range contraction. The mid-peninsular break is shared with many terrestrial and marine species, although M. l. lugubris represents the first mollusc to show it. This common break is often attributed to a hypothesized ancient seaway bisecting the peninsula, but for M. l. lugubris it may result from large habitat gaps in the southern clade. Northern clade populations, particularly near the historical northern limit (prior to the 1970s), have high local abundances and reside in a region with plentiful food and habitat - which makes its northern range conducive to expansion. The observed southern range contraction may result from the opposite scenario, with little food or habitat nearby. Our study highlights the importance of taking an integrative approach to understanding the processes that shape the geographic range of a species via combining range-wide phylogeography data with temporal geographic distributions and spatial patterns of habitat/food availability.

  12. Historical and recent processes shaping the geographic range of a rocky intertidal gastropod: phylogeography, ecology, and habitat availability

    PubMed Central

    Fenberg, Phillip B; Posbic, Karine; Hellberg, Michael E

    2014-01-01

    Factors shaping the geographic range of a species can be identified when phylogeographic patterns are combined with data on contemporary and historical geographic distribution, range-wide abundance, habitat/food availability, and through comparisons with codistributed taxa. Here, we evaluate range dynamism and phylogeography of the rocky intertidal gastropod Mexacanthina lugubris lugubris across its geographic range – the Pacific coast of the Baja peninsula and southern California. We sequenced mitochondrial DNA (CO1) from ten populations and compliment these data with museum records, habitat availability and range-wide field surveys of the distribution and abundance of M. l. lugubris and its primary prey (the barnacle Chthamalus fissus). The geographic range of M. l. lugubris can be characterized by three different events in its history: an old sundering in the mid-peninsular region of Baja (∼ 417,000 years ago) and more recent northern range expansion and southern range contraction. The mid-peninsular break is shared with many terrestrial and marine species, although M. l. lugubris represents the first mollusc to show it. This common break is often attributed to a hypothesized ancient seaway bisecting the peninsula, but for M. l. lugubris it may result from large habitat gaps in the southern clade. Northern clade populations, particularly near the historical northern limit (prior to the 1970s), have high local abundances and reside in a region with plentiful food and habitat – which makes its northern range conducive to expansion. The observed southern range contraction may result from the opposite scenario, with little food or habitat nearby. Our study highlights the importance of taking an integrative approach to understanding the processes that shape the geographic range of a species via combining range-wide phylogeography data with temporal geographic distributions and spatial patterns of habitat/food availability. PMID:25473477

  13. Diversity, heterogeneity and consumer pressure in a tropical rocky intertidal community.

    PubMed

    Menge, Bruce A; Lubchenco, Jane; Ashkenas, Linda R

    1985-02-01

    Previous studies indicated that at Taboguilla Island (Gulf of Panama), persistence of many intertidal organisms depended on holes and crevices in the rock as refuges from both vertebrate (fishes) and invertebrate (crabs, gastropods, chitons) consumers. Here, we evaluate the influences of substratum heterogeneity and consumers on patterns of diversity of sessile organisms in this habitat. Local substratum topography is highly variable, ranging from smooth to irregular surfaces. Algal crusts typically dominate all low zone rock surfaces, and most other sessile spegies (invertebrates and foliose algae) occur in holes and crevices. Number (S) and diversity (H') of sessile species is lower on homogeneous surfaces than on heterogeneous surfaces. Rate of increase in S with area sampled is positively correlated with substratum heterogeneity; number of species sampled per transect at a homogeneous site would be about 10 vs 30 to 60 on a heterogeneous site. Large fishes and crabs forage intensively over both substratum types, but cannot enter holes and crevices to eat prey. Gastropods, chitons, limpets, and small crabs feed on both substrata but vary in abundance from hole to hole. Prey mortality is thus intense and constant on open surfaces, but variable in space and time in holes and crevices. When consumers are excluded from the general rock surface, algal crusts are settled upon and overgrown by foliose algae, hydrozoans, and sessile invertebrates, particularly bivalves. Both S and H' first increase, as sessile species invade and become more abundant, and then decrease as the rock oyster Chama echinata begins to outcompete other species and dominate primary space. Hence, consumers normally keep local diversity low by removing most sessile prey from open surfaces.In these experiments, a consumer pressure gradient was established by removing 0, 1, 2, 3, and all of 4 distinct groups of consumers. As predicted by the intermediate disturbance hypothesis, lowest diversity

  14. Two new species of Tardigrada (Eutardigrada: Ramazzottiidae, Macrobiotidae) from the supralittoral zone of the Atlantic Iberian Peninsula rocky shores.

    PubMed

    Fontoura, Paulo; Rubal, Marcos; Veiga, Puri

    2017-05-10

    Two new species of Eutardigrada were found in supralittoral lichens, growing on rocky shores at two localities of the Western Atlantic coast of the Iberian Peninsula. Ramazzottius littoreus sp. nov., found in San Cibrao (North of Spain), has the dorsal cuticle sculptured with small tubercles and claws with accessory points similar to R. oberhaeuseri. It can be distinguished from all the other known Ramazzottius species with the same type of cuticular sculpture by the dotted egg shell and the peculiar reticulation visible at the bulbous base of egg processes. Macrobiotus halophilus sp. nov., found in Cascais (Centre of Portugal), belongs to the Macrobiotus hufelandi group. The slightly wrinkled egg shell and egg processes in the shape of inverted chalice with dentate distal disc, identifies it as a member of the Macrobiotus persimilis subgroup. The new dioecious species differs from the six other species of the M. persimilis subgroup by a unique combination of some characters (small and very sparse circular cuticular pores, granulation on legs I-III and dentate lunules on legs IV), by measurements of some structures (claws and buccal apparatus), and by the number, dimension and shape of egg processes.

  15. Mussel attachment on rocky shores: the effect of flow on byssus production.

    PubMed

    Carrington, Emily; Moeser, Gretchen M; Thompson, Sean B; Coutts, Laura C; Craig, Carrie A

    2008-12-01

    Mussels rely on a strong byssal attachment to persist in a range of habitats with differing rates of water flow. Recent studies, however, suggest that the ability of one mussel species to sense and respond adaptively to the flow in its environment is limited under even modest flow conditions because the process of byssal thread formation is disrupted. This study extends these findings to four mussel species, Mytilus trossulus, M. galloprovincialis, M. californianus, and Modiolus modiolus. Collectively, the response of byssal thread formation decreased with rates of flow above ∼25 cm/s and the critical flow threshold was estimated to be <50 cm/s. How can mussels persist on shores where flow is an order of magnitude higher? Using a combination of techniques for measuring flow, velocity profiles were obtained above and within mussel aggregations in the laboratory and in the field. Flow was greatly reduced within mussel aggregations, ranging from 0.1% to 10% of free-stream velocity. These results suggest one key to the success of mussels in habitats with high rates of flow is the ability to form aggregations that ameliorate flows to a level that is conducive to byssal thread formation.

  16. Prey selection and foraging period of the predaceous rocky intertidal snail, Acanthina punctulata.

    PubMed

    Menge, Jane Lubchenco

    1974-12-01

    The diet and foraging period of the neogastropod Acanthina punctulata were investigated in order to test various aspects of recent optimal foraging strategy models. This intertidal snail is an actively searching predator which preys on snails and barnacles by boring a hole in the shell and rasping out the flesh. Unlike many gastropod predators, Acanthina drill its gastropod prey at a very specific location on the columella, the thickest portion of the shell. Acanthina's foraging period can be interpreted as a compromise between maximizing the energy obtained by feeding and minimizing risk of mortality from exposure to wave action. That foraging period minimizing risk of being dislodged by waves appears to be during low tide when the predators can be in shallow pools. However, prey cannot be captured and consumed during one low tide. Thus Acanthina must be exposed during some high tides, and its strategy appears to be to restrict movement while exposed. Thus search is not initiated during high tide, but drilling and prey consumption are continued during that time. A snail not drilling or consuming prey seeks the protection of crevices or large anemones during high tide. A model is presented to indicate the relative amounts of risk and net energy for Acanthina at successive low and high tides. Predictions from the model, e.g., minimizing search time to avoid being exposed for an additional high tide and no movement during high tide are supported by field data. Acanthina commences foraging at the beginning of low tide, searches initially for preferred prey, but if unsuccessful, settles for a less preferred prey and begins drilling this prey before the end of low tide. Drilling and ingestion of prey occur during the following high and sometimes low tides. These "handling times" take 95% of the total foraging time in the field, while search time takes only 5% (pursuit time is negligible). Drilling alone accounts for 48-70% of the total drilling and eating time. In the

  17. Eocene upper shoreface facies from the Circum-Rhodope belt, NE Greece: sedimentological evidence for an ancient rocky shore environment

    NASA Astrophysics Data System (ADS)

    Chatalov, Atanas; Ivanova, Daria; Bonev, Nikolay

    2013-04-01

    The studied Middle to Upper Eocene sequence (ca.60 m) is located in western part of the large Tertiary Thrace Basin. The crudely stratified rocks consist of granuly to cobbly gravel and calcareous matrix. The former originated solely from the underlying Lower Cretaceous Aliki Limestone. The matrix includes various bioclasts plus sand-sized lithics derived from the same limestones. The broken and abraded skeletal debris belong to the heterozoan association and testify to non-tropical environment with normal marine salinity and good bottom oxygenation. The monomict gravel implies a local source of clastics close to the marine depositional basin. The bulk of extrabasinal material was produced through erosion of a rocky shore during a transgressive phase as is revealed by the present-day proximity of Aliki Limestone exposures, unconformity boundary with the overlying Eocene rocks, variable thickness and limited surface occurrence of the clastic-carbonate sequence. The extraclasts were deposited within the upper shoreface zone which is proved by their poor sorting and good roundness, absence of imbrication and disc-shaped fragments, local occurrence of matrix-supported fabric, and presence of abundant fossil debris. The Eocene transgression flooded a cliffed coast consisting of Lower Cretaceous limestones. The uneven bottom profile of the shoreface zone predetermined the formation of a wave ravinement surface (e.g. Cattaneo and Steel, 2003). The ravinement occurred through coastal erosion and wave abrasion as the shoreface shifted landward along with the rising sea level and shoreline retreat. The generated extraclasts were continuously reworked by wave motion and finally deposited as a mixture with shallow water bioclasts (also strongly reworked). The formation of a thick transgressive sequence was favoured by the interplay of several major factors as a persistent balance between sediment supply and accommodation development is inferred. The lack of vertical

  18. Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach

    NASA Astrophysics Data System (ADS)

    Sarà, G.; de Pirro, M.; Romano, C.; Rumolo, P.; Sprovieri, M.; Mazzola, A.

    2007-12-01

    Stable isotopes were used to examine the origin of organic matter in Icelandic Ascophyllum-based habitats, the role of different organic matters in filling intertidal food webs and the food preferences of the most abundant suspension feeders, grazers and predators. We selected three intertidal sites on the SW coast of Iceland where we sampled in early September 2004, organic matter sources (POM, SOM and most abundant primary producers, A. nodosum and F. vesciculosus) and the most abundant macrofauna species (barnacles, mussels, gastropods, sponge and crabs). Even though the primary production ( Ascophyllum-based) was the same at the three study sites, the isotopic composition of common-among-sites organisms varied due to local differences in the origin of available POM and SOM and in food web structures.

  19. Plant-animal diversity relationships in a rocky intertidal system depend on invertebrate body size and algal cover.

    PubMed

    Best, Rebecca J; Chaudoin, Ambre L; Bracken, Matthew E S; Graham, Michael H; Stachowicz, John J

    2014-05-01

    Considerable research has examined the influence of herbivores on the maintenance of plant diversity, but fewer studies have examined the reciprocal effect of plant diversity on the animals that use the plant community for food and shelter, particularly in marine systems. Several mechanisms could underlie such effects. Animal diversity and abundance could be increased by complementary use of different plants by different animals, or by an indirect effect of plant diversity on plant production that results in more total plant biomass in high plant-diversity communities. Alternatively, plant species identity could play a dominant role leading to sampling effects or no effect of diversity at all. We conducted a six-year field manipulation of the richness of rocky shore seaweeds in northern California and measured the effects of algal richness and identity on the invertebrate community, from meiofauna to macrofauna. We found that diverse algal communities hosted more species of both large and small invertebrates than the average algal monoculture but that the mechanisms underlying this pattern differed substantially for organisms of different size. More species of macrofauna occurred in the polycultures than in any of the monocultures, likely due to the greater total cover of algae produced in polycultures. Rare and common macrofaunal taxa responded to host plant species richness in opposite ways, with more occurrences of rare taxa and lower abundance of very common taxa in the polycultures. In contrast, meiofaunal richness in polycultures was no different than that of monocultures of finely branched species, leading to strong effects of algal identity. Our findings are similar to those from terrestrial systems in that the effects of plant diversity we observed were most related to the greater amount of habitat in polycultures as a result of overyielding in algal biomass. However, our findings differ from those in terrestrial systems in that the primary mechanisms for

  20. Daily stress protein (hsp70) cycle in chitons (Acanthopleura granulata Gmelin, 1791) which inhabit the rocky intertidal shoreline in a tropical ecosystem.

    PubMed

    Schill, Ralph O; Gayle, Peter M H; Köhler, Heinz R

    2002-03-01

    Stress protein (heat shock protein, hsp70) response is involved in protecting organisms from the detrimental effects of environmental stressors, such as radiation and high temperatures. Tropical chitons can briefly tolerate high temperatures. However, they minimize the effects of elevated temperature during daylight hours and periods of tidal air exposure by remaining in rocky intertidal microhabitats along the shoreline of tropical waters. To study the natural variability of the hsp70 level, individuals of the polyplacophoran species Acanthopleura granulata Gmelin, 1791 were sampled every 4 h on two days in spring of 1999. Hsp70 levels were separately measured in the supernatant of the intestinal tract and foot muscle homogenates with a standardized immunoassay. The hsp70 level in the intestinal tract was highest in the early morning, decreased during the mid-morning hours and dropped to a comparatively low level in the afternoon, before increasing again during the night. The stress protein level in the foot muscle followed the daily air temperature curve with a time delay of a few hours, reaching the highest level in the afternoon and the lowest level in the early morning. The stress protein response can be interpreted as a sign of heat tolerance development and may play a role in allowing A. granulata to tolerate the temperature variability typical of its intertidal habitat.

  1. Structure and diversity of intertidal benthic diatom assemblages in contrasting shores: a case study from the Tagus estuary(1).

    PubMed

    Ribeiro, Lourenço; Brotas, Vanda; Rincé, Yves; Jesus, Bruno

    2013-04-01

    The structure of intertidal benthic diatoms assemblages in the Tagus estuary was investigated during a 2-year survey, carried out in six stations with different sediment texture. Nonparametric multivariate analyses were used to characterize spatial and temporal patterns of the assemblages and to link them to the measured environmental variables. In addition, diversity and other features related to community physiognomy, such as size-class or life-form distributions, were used to describe the diatom assemblages. A total of 183 diatom taxa were identified during cell counts and their biovolume was determined. Differences between stations (analysis of similarity (ANOSIM), R = 0.932) were more evident than temporal patterns (R = 0.308) and mud content alone was the environmental variable most correlated to the biotic data (BEST, ρ = 0.863). Mudflat stations were typically colonized by low diversity diatom assemblages (H' ~ 1.9), mainly composed of medium-sized motile epipelic species (250-1,000 μm(3) ), that showed species-specific seasonal blooms (e.g., Navicula gregaria Donkin). Sandy stations had more complex and diverse diatom assemblages (H' ~ 3.2). They were mostly composed by a large set of minute epipsammic species (<250 μm(3) ) that, generally, did not show temporal patterns. The structure of intertidal diatom assemblages was largely defined by the interplay between epipelon and epipsammon, and its diversity was explained within the framework of the Intermediate Disturbance Hypothesis. However, the spatial distribution of epipelic and epipsammic life-forms showed that the definition of both functional groups should not be over-simplified.

  2. Can crabs kill like a keystone predator? A field-test of the effects of crab predation on mussel mortality on a northeast Pacific rocky shore

    PubMed Central

    Hull, Wesley W.

    2017-01-01

    Predation can strongly influence community structure and ecosystem function, so the loss of key predators can have dramatic ecological consequences, unless other predatory species in the system are capable of playing similar ecological roles. In light of the recent outbreak of sea star wasting disease (SSWD) and subsequent depletion of west coast sea star populations, including those of the keystone predator Pisaster ochraceus, we examined whether large mobile crabs could play a role as predators on mussels (Mytilus californianus) on a rocky shore in Northern California. Using a combination of sea star removal and predator exclusion cages we found that mussel mortality was 43–294 times greater in uncaged treatments versus caged treatments. Mortality on uncaged mussels at low tidal elevations was due to predation by large mobile crabs (Cancer productus and Romaleon antennarium); confirmed by the presence of mussel shell fragments and documented attacks on wax snail replicas. Laboratory feeding assays indicated that crabs, on a per unit biomass basis, can consume almost twenty-five times as many mussels per day than sea stars, which together with the results of our field experiment, suggest that large predatory crabs could play an important role in maintaining ecosystem function through their predation on mussels on rocky shores where P. ochraceus are rare, absent, or have been depleted by SSWD. PMID:28837597

  3. Investigations on the feeding habits of the rocky-shore mite Hyadesia fusca (Acari: Astigmata: Hyadesiidae): diet range, food preference, food quality, and the implications for distribution patterns

    NASA Astrophysics Data System (ADS)

    Bücking, Jens

    1998-06-01

    Within the food web of estuarine and marine rocky shore ecosystems phytophagous mites of terrestrial and marine origin constitute an important part as grazers on algae and as a food source for certain arthropods, especially zoophagous mites. This investigation deals with the feeding biology of Hyadesia fusca taking as an example a population located on an artificial rocky shore of the middle Weser estuary in Northern Germany. The species is characterized by a broad diet range; in feeding experiments diatoms, lichens, detritus as well as blue, red and green algae were accepted. Even analyses of faecal pellets produced by field specimen suggest a non-specific feeding habit. However, the influence of certain diets on mortality, offspring number and rearing success showed that the food quality differs significantly. The most suitable food, the Ulvaceae Blidingia, was clearly preferred in a series of pairwise choice tests. These findings correlate with the vertical zonation of the field population i.e.: higher population densities in the vegetation zone dominated by Blidingia. It can be concluded that in addition to abiotic factors food supply could play an important role for distribution patterns of phytophagous mites.

  4. A comparative study on intertidal faunal biodiversity of selected beaches of Mumbai coast.

    PubMed

    Datta, S N; Chakraborty, S K; Jaiswar, A K; Ziauddin, G

    2010-11-01

    Comparative study has been done to examine the biodiversity and ecological status of the intertidal region of Tata Institute of Fundamental Research (TIFR), Bandstand and National Centre for Performing Arts (NCPA) rocky beaches in Mumbai, West coast of India. A total of 50 species of intertidal organisms were recorded from these shores. Shannon and Simpson's diversity index, Margalefs richness index and Pielou's evenness index indicated different level of ecological state of the shore in different months. Dendrograms and 2-D non metric MDS ordination from Bray-Curtis similarity matrix of occurrence of intertidal organisms from these sites showed highest similarity and combination pattern of occurrence between Nerita oryzarum and Planaxis sulcatus in TIFR and Bandstand shore. Nerita oryzarum and Tactarius malaccanus at NCPA shore. Abundance/biomass comparison (ABC) method of determining level of disturbance also pointed towards the polluted status of these shores. Study concludes that though these beaches are highly disturbed due to anthropogenic activities, they still support a rich intertidal biodiversity which need immediate attention for protection and conservation.

  5. Assessing a quick monitoring method using rocky intertidal communities as a bioindicator: a multivariate approach in Algeciras Bay.

    PubMed

    Guerra-García, J M; Maestre, M J; González, A R; García-Gómez, J C

    2006-05-01

    A multivariate approach was used to test the value of intertidal communities as a bioindicator of environmental conditions at Algeciras Bay, southern Spain. The study area is located in the Strait of Gibraltar and it is subjected to a variety of anthropic impacts. Eight localities (5 inside and 3 outside the bay) were selected, and four transects were undertaken in each locality to characterise the fauna and flora. The spatial distribution of the intertidal species reflected the physico-chemical conditions of Algeciras Bay. The stations located outside the bay, characterised by high hydrodynamism and dissolved oxygen and low sedimentation and turbidity, had a higher diversity and species richness than the inner stations. According to the BIO-ENV procedure and CCA, water turbidity was the factor which best correlated with the intertidal assemblages. SIMPER showed that the molluscs Chtamalus stellatus, Mytilus cf edulis, Littorina neritoides and Balanus perforatus, and the algae Gelidium pusillum, Corallina elongata, Asparagopsis armata, Colpomenia sinuosa and Fucus spiralis were the species that most contributed to the dissimilarity between internal and external sites. The present study, based on the spatial distribution of intertidal taxa, yielded similar results to those previously obtained in the area with costly physico-chemical analysis based on complex matrices of subtidal epifaunal communities. Consequently, the intertidal sampling method proposed in this study is presented here as a quick, effective alternative strategy, and can be useful in environmental monitoring programs, since these communities are easily accessible and amenable to sample, and the sessile nature of the majority of the species makes future, long-term monitoring relatively simple.

  6. Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake.

    PubMed

    Sepúlveda, Roger D; Valdivia, Nelson

    2016-01-01

    Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a "control" area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. "negative" uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after-earthquake tsunami

  7. Localised Effects of a Mega-Disturbance: Spatiotemporal Responses of Intertidal Sandy Shore Communities to the 2010 Chilean Earthquake

    PubMed Central

    Sepúlveda, Roger D.; Valdivia, Nelson

    2016-01-01

    Determining the effects of unpredictable disturbances on dynamic ecological systems is challenged by the paucity of appropriate temporal and spatial coverage of data. On 27 February 2010, an 8.8 Mw mega-earthquake and tsunami struck central Chile and caused coastal land-level changes, massive damage to coastal infrastructure, and widespread mortality of coastal organisms. Wave-exposed sandy beaches showed significant changes of species abundances from before to after the earthquake, but the highly dynamic biotic and abiotic conditions of these habitats make difficult to draw clear-cut conclusions from these patterns. Here, we analysed a beyond-BACI (Before-After Control-Impact) sampling design to test whether the effects of the Maule earthquake on sandy-shore species diversity, abundance, and structure were heterogeneous along the shore. Invertebrate species abundances were quantified before (i.e. February 2010) and after (i.e. March 2010, September 2010, and March 2011) the earthquake at three sandy shores randomly located within the earthquake rupture area and three sites within a “control” area located >400 km southward from epicentre. Immediately after the earthquake took place, the three sites located in the rupture area showed anomalous beach-profile uplifts that did not comply with the erosion (i.e. “negative” uplifts) that regularly occurs during late summer in the region. Species richness, abundance, and community structure significantly varied from before to after the strike, but these patterns of change varied among sites within both areas. Only the site with the strongest and persistent beach-profile uplift within the rupture area showed significant concomitant changes in species richness and community structure; after 13 months, this community showed a similar multivariate structure to the before-disturbance state. This site, in particular, was located in the section of the rupture area that received most of the impact of the after

  8. Comparing quality of estuarine and nearshore intertidal habitats for Carcinus maenas

    NASA Astrophysics Data System (ADS)

    Amaral, Valter; Cabral, Henrique N.; Jenkins, Stuart; Hawkins, Stephen; Paula, José

    2009-06-01

    Estuarine and nearshore marine areas are vital habitats for several fish and benthic invertebrates. The shore crab Carcinus maenas (Crustacea: Brachyura: Portunidae) inhabits a variety of coastal, estuarine and lagoon habitats. At low tide, habitat structural complexity may be most important for crabs in the intertidal, providing refuge from predation and desiccation. The quality of different vegetated and nonvegetated estuarine and rocky shore habitats in SW Portugal and SW England was evaluated for intertidal C. maenas populations. We estimated population density, size-structure, and potential growth (RNA/DNA ratios) to investigate habitat quality. Vegetated estuarine habitats supported higher crab densities, than nonvegetated estuarine and rocky shore habitats. Investigation of population size-structure revealed that all habitats seem important recruitment and nursery areas although estuarine habitats in SW Portugal appeared to support higher densities of new recruits than equivalent habitats in SW England. Significant variation was found in RNA/DNA ratios among habitats. Ratios were highest in the rocky shore suggesting a high quality habitat where growth potential is high. We speculate that competition from other top-predators ( Pachygrapsus spp.) rather than low habitat quality may limit the occurrence of C. maenas in intertidal rocky shore habitats in SW Portugal. In estuarine environments RNA/DNA ratios were significantly higher in the vegetated than in the nonvegetated estuarine habitats in SW Portugal but not in SW England, suggesting geographic differences in the extent to which highly structure habitats represent high quality. Our results challenge the current paradigm that structured habitats are necessarily those of higher quality for C. maenas.

  9. The influence of desiccation and predation on vertical size gradients in populations of the gastropod Oxystele variegata (Anton) on an exposed rocky shore.

    PubMed

    McQuaid, C D

    1982-04-01

    Oxystele variegata (Anton.) exhibits a vertical size gradient contrary to the model proposed by Vermeij (1972) for low/mid intertidal species, as shell size increases in an upshore direction. Settlement occurs in the lowest zones and juveniles are restricted to the lower shore by conditions of desiccation higher up the beach. Juveniles suffer rapid water loss due to a relatively large opercular surface area and circumference and have a much lower resistance to water loss than adults. This leads to high mortality under conditions of low humidities, and juveniles caged at the top of the balanoid zone, where adults normally occur, die within a few days. As animals increase in size their resistance to desiccation rises allowing them to migrate upshore. This is a response to high rates of predation by the whelk Burnupena delalandii in the lower balanoid zone. Predation is so intense as to override the advantages of higher food availability which lead to a greater body weight for adults protected by cages on the lower shore.

  10. Planktonic Subsidies to Surf-Zone and Intertidal Communities.

    PubMed

    Morgan, Steven G; Shanks, Alan L; MacMahan, Jamie H; Reniers, Ad J H M; Feddersen, Falk

    2017-08-28

    Plankton are transported onshore, providing subsidies of food and new recruits to surf-zone and intertidal communities. The transport of plankton to the surf zone is influenced by wind, wave, and tidal forcing, and whether they enter the surf zone depends on alongshore variation in surf-zone hydrodynamics caused by the interaction of breaking waves with coastal morphology. Areas with gently sloping shores and wide surf zones typically have orders-of-magnitude-higher concentrations of plankton in the surf zone and dense larval settlement in intertidal communities because of the presence of bathymetric rip currents, which are absent in areas with steep shores and narrow surf zones. These striking differences in subsidies have profound consequences; areas with greater subsidies support more productive surf-zone communities and possibly more productive rocky intertidal communities. Recognition of the importance of spatial subsidies for rocky community dynamics has recently advanced ecological theory, and incorporating surf-zone hydrodynamics would be an especially fruitful line of investigation. Expected final online publication date for the Annual Review of Marine Science Volume 10 is January 3, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  11. Trophic ecology of the rocky shore community associated with the Ascophyllum nodosum zone (Roscoff, France): A δ 13C vs δ 15N investigation

    NASA Astrophysics Data System (ADS)

    Riera, Pascal; Escaravage, Carole; Leroux, Cédric

    2009-01-01

    This study aimed to characterize the structure and functioning of the benthic food web associated with the Ascophyllum nodosum zone of the rocky shore of Roscoff by using δ 13C and δ 15N. Several characteristics of the trophic ecology of the invertebrates associated with this mid-littoral habitat and which belong to different functional groups (e.g., grazers, filter-feeders, predators and omnivores) were highlighted. In particular, the filter feeder species (including mostly sponges) used macroalgae-derived organic matter as a substantial food requirement. The results also pointed out an important stable isotopes variability for strict coexisting primary consumers which: (1) is directly related to the high δ 15N range of the food sources; (2) makes it impossible to establish a unique trophic level scale based on δ 15N values, as previously done in coastal environments; and (3) points out the existence of major co-occurring trophic pathways which characterise the Ascophyllum nodosum habitat.

  12. Effects of sediment discharge from Namibian diamond mines on intertidal and subtidal rocky-reef communities and the rock lobster Jasus lalandii

    NASA Astrophysics Data System (ADS)

    Pulfrich, Andrea; Branch, George M.

    2014-10-01

    Extensive terrestrial diamond mining occurs on the southern coast of Namibia, and at Elizabeth Bay near Lüderitz sediment tailings totalling about 2 million tons.yr-1, have been discharged onto the beach. We report here on monitoring spanning 2004-2012 to assess (1) the impacts of increased tailings discharges following an expansion of the mine in 2005, and (2) recovery after discharges halted in 2009. Sampling covered three levels of wave exposure, and compared impacted sites with comparable unmined reference sites. Benthic communities were quantified on both intertidal and subtidal reefs, and kelp densities and rock-lobster abundances, lengths and sex ratios on subtidal reefs. Prior to intensification of mining, deposition of tailings significantly influenced intertidal communities only at sheltered localities where wave action was insufficient to disperse them. Following the mine expansion, effects spread to both semi-exposed and exposed sites. After mining was suspended, recovery of the biota was limited, even three years later. Reductions of intertidal diversity and grazers, proliferation of macroalgae, and increased dominance by filter feeders were recorded at the impacted sites and were persistent, but the affects of wave exposure on community composition generally exceeded those of mining discharges. On subtidal reefs, tailings deposition reduced predators and grazers, increased filter feeders and ephemeral green algae, and decreased all other algae, possibly driven by light reduction due to plumes of suspended fine sediments. Increased discharges post-2005 also substantially influenced bathymetry, wave and current regimes, transforming 2 km of previously wave-exposed rocky coastline into a semi-exposed sandy beach. Tailings discharge appeared to influence community composition in four ways: (1) inundation and blanketing; (2) increased suspended particulate materials; (3) indirect top-down ripple effects, and (4) light reduction. Throughout the period 2004

  13. Does the abundance of girellids and kyphosids correlate with cover of the palatable green algae, Ulva spp.? A test on temperate rocky intertidal reefs.

    PubMed

    Ferguson, A M; Harvey, E S; Rees, M J; Knott, N A

    2015-01-01

    This study assessed whether the abundance of girellids and kyphosids was related to cover of the palatable green algae, Ulva australis and Ulva compressa, on rocky intertidal reefs in Jervis Bay, New South Wales, Australia. No relationship was found between Ulva spp. cover and abundance of Girella tricuspidata, Girella elevata and Kyphosus sydneyanus during a period of relatively low Ulva spp. cover (i.e. February 2011 to March 2011), but during a period of significantly higher Ulva spp. cover (i.e. October 2011 to November 2011) there was a strong correlation between Ulva spp. cover and G. tricuspidata abundance. Spatial analysis indicated that the abundance of G. tricuspidata was consistent across time, suggesting G. tricuspidata were not moving between reefs in response to variation in Ulva spp. cover between periods but rather that large schools of G. tricuspidata resided on reefs that had relatively higher Ulva spp. cover at certain times of the year. © 2014 The Fisheries Society of the British Isles.

  14. A new species of Hemipera Nicoll, 1913 (Digenea: Derogenidae) from fishes of the intertidal rocky zone of Chile.

    PubMed

    Díaz, Pablo E; Muñoz, Gabriela; George-Nascimento, Mario

    2016-09-01

    A new species, Hemipera cribbi sp. nov., is described. This trematode was found in three intertidal fish species: Scartichthys viridis (Valenciennes) (Blenniidae), Gobiesox marmoratus Jenyns (Gobiesocidae) and Myxodes viridis Valenciennes (Clinidae) from the central and southern coast of Chile. Of 233 individuals of S. viridis from the central coast examined, 19 were infected. From the southern coast, nine individuals of S. viridis (one infected), five individuals of G. marmoratus (four infected), and 16 individuals of M. viridis (one fish infected) were examined. Hemipera cribbi sp. nov. is distinguished from the five other congeneric species mainly in the body size, being the smallest and narrowest species in the genus, reaching five times longer than wide. This is the first species of the genus described for the South Pacific Ocean off South America. ITS2 rDNA sequences of Hemipera cribbi sp. nov. from each host and locality were identified.

  15. Kite aerial photography for low-cost, ultra-high spatial resolution multi-spectral mapping of intertidal landscapes.

    PubMed

    Bryson, Mitch; Johnson-Roberson, Matthew; Murphy, Richard J; Bongiorno, Daniel

    2013-01-01

    Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time that could complement field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at limited spatial and temporal resolutions and relatively high costs for small-scale environmental science and ecologically-focussed studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric/mapping procedure that was developed for constructing high-resolution, three-dimensional, multi-spectral terrain models of intertidal rocky shores. The processing procedure uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine imagery at visible and near-infrared wavelengths and topographic information at sub-centimeter resolutions over an intertidal shoreline 200 m long, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rocky shore at Jervis Bay, New South Wales, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales.

  16. Kite Aerial Photography for Low-Cost, Ultra-high Spatial Resolution Multi-Spectral Mapping of Intertidal Landscapes

    PubMed Central

    Bryson, Mitch; Johnson-Roberson, Matthew; Murphy, Richard J.; Bongiorno, Daniel

    2013-01-01

    Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time that could complement field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at limited spatial and temporal resolutions and relatively high costs for small-scale environmental science and ecologically-focussed studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric/mapping procedure that was developed for constructing high-resolution, three-dimensional, multi-spectral terrain models of intertidal rocky shores. The processing procedure uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine imagery at visible and near-infrared wavelengths and topographic information at sub-centimeter resolutions over an intertidal shoreline 200 m long, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rocky shore at Jervis Bay, New South Wales, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales. PMID:24069206

  17. Summertime community structure of intertidal macrobenthos in Changdao Archipelago, Shandong Province, China

    NASA Astrophysics Data System (ADS)

    Wang, Xiaochen; Li, Xinzheng; Li, Baoquan; Wang, Hongfa

    2009-09-01

    The community structure of intertidal macrobenthos in Changdao Archipelago (north of Shandong Peninsula, between Bohai Bay and the northern Yellow Sea) was examined based on samples collected from 14 stations in five transects in June 2007. Three stations corresponding to high, medium and low tidal areas were set up for each transect. A total of 68 macrobenthic species were found in the research region, most of which belonged to Mollusca and Crustacea. The average abundance and biomass of the macrobenthos was 1 383 ind./m2 and 372.41 g/m2, respectively. The use of an arbitrary similarity level of 20% resulted in identification of five groups among the 14 stations in the research region. There were remarkable differences in the biomass, abundance and Shannon-Wiener diversity index of the different sediments. Specifically, the order of biomass was rocky shores > gravel > mud-sand > coarse sand > stiff mud, while the order of abundance was rocky shores > coarse sand > mud-sand > gravel > stiff mud, and that of the diversity index was mud-sand > gravel > stiff mud > rocky shores > coarse sand. The above results revealed that the sediment type was the most important factor affecting the structure of the macrobenthic community of the intertidal zone.

  18. Trophic structure and diversity in rocky intertidal upwelling ecosystems: A comparison of community patterns across California, Chile, South Africa and New Zealand

    NASA Astrophysics Data System (ADS)

    Blanchette, C. A.; Wieters, E. A.; Broitman, B. R.; Kinlan, B. P.; Schiel, D. R.

    2009-12-01

    The Benguela, California, and Humboldt represent three of the major eastern boundary upwelling ecosystems in the world. Upwelling ecosystems are highly productive, and this productivity forms the base of the food chain, potentially leading to ecosystems similar in trophic structure and diversity among upwelling regions. Here we compare the biological and trophic structure of rocky intertidal communities in each of these major upwelling regions. Our comparison includes a fourth region, New Zealand, which spans a similar latitudinal range, and experiences intermittent upwelling. The influence of oceanographic conditions on these communities was evaluated by using the long-term mean and standard deviation of satellite-based sea surface temperature (SST). Large differences emerged in the taxonomic richness in each of these systems, with California as the most and the Humboldt as the least taxonomically rich. Across all regions, richness tended to decrease progressively from lower trophic levels (macrophytes) to higher trophic levels (carnivores), and richness was inversely correlated with the proportion of variance in SST contained in the seasonal cycle, suggesting that strongly seasonal, predictable environments are relatively low in diversity. The functional and trophic structures were remarkably similar across these four regions of the world. Macrophytes were slightly dominant over filter-feeders in terms of space occupancy in all regions except the Benguela. Densities of herbivorous grazers were greatest in California and Benguela and far outnumbered carnivore densities in all regions. Despite some similarities, the overall structure of the communities from these regions differed significantly supporting the hypothesis that the biological and ecological consequences of similar physical forcing mechanisms (e.g. upwelling) are likely to be context-dependent.

  19. Parasitism, community structure and biodiversity in intertidal ecosystems.

    PubMed

    Mouritsen, K N; Poulin, R

    2002-01-01

    There is mounting evidence that parasites can influence the composition and structure of natural animal communities. In spite of this, it is difficult to assess just how important parasitism is for community structure because very few studies have been designed specifically to address the role of parasites at the community level, no doubt because it is difficult to manipulate the abundance of parasites in field experiments. Here, we bring together a large amount of published information on parasitism in intertidal communities to highlight the potential influence of parasites on the structure and biodiversity of these communities. We first review the impact of metazoan parasites on the survival, reproduction, growth and behaviour of intertidal invertebrates, from both rocky shores and soft-sediment flats. Published evidence suggests that the impact of parasites on individuals is often severe, though their effects at the population level are dependent on prevalence and intensity of infection. We then put this information together in a discussion of the impact of parasitism at the community level. We emphasize two ways in which parasites can modify the structure of intertidal communities. First, the direct impact of parasites on the abundance of key host species can decrease the importance of these hosts in competition or predator-prey interactions with other species. Second, the indirect effects of parasites on the behaviour of their hosts, e.g. burrowing ability or spatial distribution within the intertidal zone, can cause changes to various features of the habitat for other intertidal species, leading to their greater settlement success or to their local disappearance. Our synthesis allows specific predictions to be made regarding the potential impact of parasites in certain intertidal systems, and suggests that parasites must be included in future community studies and food web models of intertidal ecosystems.

  20. Human exclusion from rocky shores in a mediterranean marine protected area (MPA): an opportunity to investigate the effects of trampling.

    PubMed

    Casu, Daniela; Ceccherelli, Giulia; Curini-Galletti, Marco; Castelli, Alberto

    2006-07-01

    The effect of human trampling on the abundance of small invertebrates inhabiting rocky shallow bottoms was studied at Asinara Island MPA. To this aim we have conducted two experiments. The first was a quantitative study and tested the hypothesis that small invertebrates are more abundant at no-entry locations than at the location visited by tourists through time (before, during and after tourist season). The second was a manipulative experiment and tested the hypothesis that the abundance of small invertebrates is indirectly related to experimental trampling intensities. The effect due to tourist visitation was not highlighted on overall assemblages, suggesting that present seasonal tourist load at the MPA does not cause a significantly negative effect on the zoobenthic community studied. Although tourists exhibited trampling activity at the visited location, none of taxa examined showed a significant lower abundance during and strictly after the end of seasonal tourism peak in the visited location, rather than at control locations. However, results obtained with the second experiment suggested that the effects of different experimental trampling intensities on small invertebrates were variable among taxa. The experimental trampling caused immediate declines in the density of tanaids, nematodes, acari, bivalves, gammarids, echinoderms, isopods, and harpacticoids. For some of these taxa a recovery in abundance was observed within one month. This kind of data may offer important information to estimate the number of visitors compatible with the sensitivity of zoobenthic assemblages, and may substantially contribute to appropriate MPA management.

  1. Rhythms of gene expression in a fluctuating intertidal environment.

    PubMed

    Gracey, Andrew Y; Chaney, Maxine L; Boomhower, Judson P; Tyburczy, William R; Connor, Kwasi; Somero, George N

    2008-10-14

    The physiological strategies that enable organisms to thrive in habitats where environmental factors vary dramatically on a daily basis are poorly understood. One of the most variable and unpredictable habitats on earth is the marine rocky intertidal zone located at the boundary between the terrestrial and marine environments. Mussels dominate rocky intertidal habitats throughout the world and, being sessile, endure wide variations in temperature, salinity, oxygen, and food availability due to diurnal, tidal, and climatic cycles. Analysis of gene-expression changes in the California ribbed mussel (Mytilus californianus) at different phases in the tidal cycle reveals that intertidal mussels exist in at least four distinct physiological states, corresponding to a metabolism and respiration phase, a cell-division phase, and two stress-response signatures linked to moderate and severe heat-stress events. The metabolism and cell-division phases appear to be functionally linked and are anticorrelated in time. The magnitudes and timings of these states varied by vertical position on the shore and appear to be driven by microhabitat conditions. The results provide new insights into the strategies that allow life to flourish in fluctuating environments and demonstrate the importance of time course data collected from field animals in situ in understanding organism-environment interactions.

  2. Patterns of association between algae, fishes and grey herons Ardea cinerea in the rocky littoral zone of a Scottish sea loch

    NASA Astrophysics Data System (ADS)

    Carss, D. N.; Elston, D. A.

    2003-10-01

    The distribution of dominant algae, Fucus vesiculosus and Ascophyllum nodosum, the associated fish community, and the spatial and temporal distributions of the main piscivorous predator, the grey heron Ardea cinerea, were studied on the rocky intertidal zone of Loch Etive, a sea loch on the Scottish west coast. Fucus- and Ascophyllum-dominated shores were not distributed randomly around the shore: the latter was especially common along the more sheltered shores and bays and on the finer substratum types. Coverage and frond length of Ascophyllum were greater than for Fucus. Fourteen fish species were caught in the intertidal zone. Numerically, the catch was dominated by four species caught in Fucus- and Ascophyllum-dominated habitats in both winter and summer: Spinachia spinachia, Pholis gunnellus, Taurulus bubalis and Zoarces viviparus. A higher species richness and fish abundance were recorded on Ascophyllum shores than on Fucus ones in both seasons. On Loch Etive, grey herons foraged exclusively in the intertidal zone usually as solitary, well-spaced individuals. The models suggest the number of foraging birds tended to increase with increasing total algal area (i.e. the two dominant species plus Fucus serratus) and with area of Ascophyllum and decreased with increasing area of Fucus and distance from the breeding colony. Adult grey herons showed a preference for foraging in Ascophyllum habitat and first-years showed no preference, suggesting that Ascophyllum-dominated areas are optimal foraging habitats for coastal-living grey herons. One section of shore was particularly important in establishing these habitat relationships: an Ascophyllum-dominated section with the largest intertidal area and where the highest number of foraging adults but no first-years were recorded. Future conservation and management considerations for the rocky intertidal zone should include associated fish communities and their predators, for which this habitat, and Ascophyllum

  3. Breeding biology and microhabitat utilization of the intertidal isopod Idotea granulosa Rathke, in the Irish Sea

    NASA Astrophysics Data System (ADS)

    Salemaa, Heikki

    1986-03-01

    The life history and distribution of the intertidal isopod Idotea granulosa were investigated at five rocky shore biotopes in the Isle of Man. I. granulosa breeds throughout the year in the Irish Sea. The breeding activity is highest in the early summer after the sexual maturation of the overwintered animals. At that period about 4% of the females were infested by Clypeoniscus sp. (Isopoda) which destroys the brood. A small proportion of the juveniles released in the early summer mature and breed in the autumn. In the winter Idotea populations consisted of juveniles, immature adults and old individuals which produce another brood. These large sized animals die off before the summer. Consequently, the age and size of the breeding I. granulosa fluctuates seasonally. The number of eggs is linearly related to the female length. The fecundity is highest in the spring and lowest in the autumn in all female size classes. I. granulosa inhabits an array of structurally different intertidal algae including the filamentous Cladophora rupestris, understory turfs Gigartina stellata, Laurencia pinnatifida and Corallina officinalis and the fucoids Fucus serratus and Ascophyllum nodosum. The distribution pattern of I. granulosa in examined intertidal communities is modified by the physiognomy of the algal microhabitats, by seasonal and spatial variation in wave agitation and by the breeding cycle of the population itself. Both the life history characteristics and distribution patterns are explained as adaptations to the spatially and temporally heterogeneous intertidal shores.

  4. Effects of the Exxon Valdez oil spill on migrant shorebirds using rocky intertidal habitats of Prince William Sound, Alaska, during spring, 1989. Exxon Valdez oil spill state/federal natural resource damage assessment final report

    SciTech Connect

    Martin, P.D.

    1993-12-01

    A minimum of a few 10,000`s of surfbirds (Aphriza virgata) and black turnstones (Arenaria melanocephala) used rocky intertidal habitats of southwestern Prince William sound in spring 1989. Virtually all the shorebirds were found using shorelines, primarily on northern Montague Island, subjectively classified in the field as lightly oiled or unoiled. Surfbirds and black turnstones preyed mainly on herring eggs, blue mussels, and barnacles. Samples of these prey items from oiled areas contained petroleum-derived hydrocarbons, as did at some of the samples from the relatively clean portions of Montague Island. The results of chemical analysis of a small sample of shorebird liver tissues provided only limited support for the hypothesis that shorebirds had ingested significant quantities of petroleum-derived hydrocarbons. Surfbirds and black turnstones probably escaped significant population impacts as a result of the EVOs because shorelines which received heavy use by these species were largely spared contamination.

  5. Morphological features and processes in the central Algarve rocky coast (South Portugal)

    NASA Astrophysics Data System (ADS)

    Moura, D.; Albardeiro, L.; Veiga-Pires, C.; Boski, T.; Tigano, E.

    2006-11-01

    Morphological features along the Algarve rocky coast, South Portugal, are identified and described, with an emphasis on shore platforms and notches. The contributions of processes, such as wave attack, chemical weathering and bioerosion, to sculpting the shore platforms are discussed. The preferential localization of shore platforms on sites exposed to waves, and the lack of significant chemical weathering, point to wave erosion as the first-order factor in platform formation, whilst bioerosion/bioprotection, lithology and geological structure determine platform morphological variations. In addition, platforms above the present intertidal zone appear to have a polygenetic evolution, being inherited from former sea-level highstands and currently undergoing chemical weathering. The occurrence of notch features is independent of the degree of exposure to waves, but they mostly occur where the substratum is sand. Hydrostatic pressure appears to be an important factor in the formation of marine caves in the more sheltered sites.

  6. Life on Our Shore

    ERIC Educational Resources Information Center

    Scott, Graham; Grassam, Matthew; Scott, Lisa

    2011-01-01

    St. Martin's Church of England Primary School in Scarborough, North Yorkshire, enjoys a unique location, being approximately 10 minutes walk from a rocky shore and a similar distance from the University of Hull (Scarborough Campus) and its Centre for Environmental and Marine Sciences. A grant provided by the Royal Society (under their Education…

  7. Life on Our Shore

    ERIC Educational Resources Information Center

    Scott, Graham; Grassam, Matthew; Scott, Lisa

    2011-01-01

    St. Martin's Church of England Primary School in Scarborough, North Yorkshire, enjoys a unique location, being approximately 10 minutes walk from a rocky shore and a similar distance from the University of Hull (Scarborough Campus) and its Centre for Environmental and Marine Sciences. A grant provided by the Royal Society (under their Education…

  8. Impacts of the Jessica oil spill on intertidal and shallow subtidal plants and animals.

    PubMed

    Edgar, Graham J; Kerrison, Linda; Shepherd, Scoresby A; Veronica Toral-Granda, M

    2003-01-01

    Densities of fishes, invertebrates and plants at rocky intertidal and shallow subtidal sites were censused 1-2 days prior to the Jessica oil spill and compared with information obtained for the same sites one month after the spill, both for sites impacted by oil and unaffected reference sites. While the availability of pre-spill data made this analysis one of the most powerful to date for testing impacts of oil on shoreline environments, no clear changes attributable to oiling could be identified. Discharged oil appeared to cause very little impact in the intertidal and shallow subtidal zones, with such impacts lying within the range of natural spatial and temporal variation at sites investigated. Factors considered to minimize impact in Galápagos included paucity of fully sheltered shores in spill path, moderate wave action, warm temperature, high levels of sunlight, and mixing of bunker oil with diesel.

  9. Parasite communities of a fish assemblage from the intertidal rocky zone of central Chile: similarity and host specificity between temporal and resident fish.

    PubMed

    Muñoz, G; Cortés, Y

    2009-09-01

    The different species of a fish assemblage can, to some extent, be similar in terms of their parasite communities, which can be associated with certain ecological host traits. This study compared the parasite community descriptors between temporal and resident fish species composing an intertidal assemblage from central Chile. Host specificity and similarity indices of parasite communities among the fish species were also considered. A total of 1097 fish representing 14 species were collected during spring and summer of 2 consecutive years. A total spectrum of 40 parasite species was found, of which copepods and trematodes were the commonest. Congeneric fish species had the highest similarities in their parasite communities. Based on a cluster analysis, using only some fish species, no group was distinguished using abundance or prevalence of parasites, because 50% of parasite species had high host specificity and only few of them were shared among fish species. Adult parasites showed high host specificity and were found mainly in resident intertidal fish, whereas the temporal fish had parasites with different degrees of specificity. Consequently, resident intertidal fish were characterized by their own parasite species, meaning that their transmissions might be restricted to the intertidal zone.

  10. An environmental stress model correctly predicts unimodal trends in overall species richness and diversity along intertidal elevation gradients

    NASA Astrophysics Data System (ADS)

    Zwerschke, Nadescha; Bollen, Merle; Molis, Markus; Scrosati, Ricardo A.

    2013-12-01

    Environmental stress is a major factor structuring communities. An environmental stress model (ESM) predicts that overall species richness and diversity should follow a unimodal trend along the full stress gradient along which assemblages from a regional biota can occur (not to be confused with the intermediate disturbance hypothesis, which makes predictions only for basal species along an intermediate-to-high stress range). Past studies could only provide partial support for ESM predictions because of the limited stress range surveyed or a low sampling resolution. In this study, we measured overall species richness and diversity (considering all seaweeds and invertebrates) along the intertidal elevation gradient on two wave-sheltered rocky shores from Helgoland Island, on the NE Atlantic coast. In intertidal habitats, tides cause a pronounced gradient of increasing stress from low to high elevations. We surveyed up to nine contiguous elevation zones between the lowest intertidal elevation (low stress) and the high intertidal boundary (high stress). Nonlinear regression analyses revealed that overall species richness and diversity followed unimodal trends across elevations on the two studied shores. Therefore, our study suggests that the ESM might constitute a useful tool to predict local richness and diversity as a function of environmental stress. Performing tests on other systems (marine as well as terrestrial) should help to refine the model.

  11. Heavy metal in water and aquatic organisms from different intertidal ecosystems, Persian Gulf.

    PubMed

    Rahmanpour, Shirin; Ghorghani, Nasrin Farzaneh; Lotfi Ashtiyani, Seyede Masoumeh

    2014-09-01

    Intertidal ecosystems are being damaged by anthropogenic activities, particularly in the developing countries. In this study, the load of heavy metals was determined in water, fish, shrimp, and crab collected from four intertidal ecosystems, including coral reef, rocky shore, mangrove forest, and muddy habitat along the Persian Gulf coasts. Generally, the sequence of metal accumulation in the water of coral reef and mangrove forest was Ni > Pb > V > Cd > As > Hg, whereas in muddy habitats and rocky shores, the sequence was Ni > Pb > V > Cd > Hg > As and Ni > V > Pb > As > Hg > Cd, respectively. Water of the coral reef had the highest level of Ni (97.44 μg l(-1)), Pb (3.92 μg l(-1)), V (10.42 μg l(-1)), Cd (3.92 μg l(-1)), As (1.87 μg l(-1)), and Hg (0.74 μg l(-1)). For the most part, the highest concentrations of the studied metals were found in the liver and the gills of Johnius belangerii and the hepatopancreas of Portunus pelagicus and Metapenaus affinis collected from the coral reef ecosystem.

  12. The intertidal Fortuyniidae (Acari: Oribatida): new species, morphological diversity, ecology and biogeography.

    PubMed

    Pfingstl, Tobias

    2015-05-18

    Three new fortuyniid species, Fortuynia longiseta sp. nov., F. maledivensis sp. nov. and Alismobates pseudoreticulatus sp. nov., were found in littoral environments of the Maldives and Singapore and are described based on adult and juvenile morphology. A key is given to all Alismobates and Fortuynia species. The genus Fortuynia shows a homogeneous morphology and this is supposed to be a result of a limited habitat preference shown in this genus. Nearly all species only occur on rocky intertidal shores, except for F. rotunda dwelling in mangrove habitats and F. smiti found in riverine environments. Fortuynia smiti was now also found in a typical littoral habitat in Singapore and hence the remarkably broad ecological range of this species is discussed. The records of further fortuyniid species in the Indo-Pacific affirm that this taxon may be continuously distributed along shores of this geographic region.

  13. Increasing sea surface temperature and range shifts of intertidal gastropods along the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Rubal, Marcos; Veiga, Puri; Cacabelos, Eva; Moreira, Juan; Sousa-Pinto, Isabel

    2013-03-01

    There are well-documented changes in abundance and geographical range of intertidal invertebrates related to climate change at north Europe. However, the effect of sea surface warming on intertidal invertebrates has been poorly studied at lower latitudes. Here we analyze potential changes in the abundance patterns and distribution range of rocky intertidal gastropods related to climate change along the Iberian Peninsula. To achieve this aim, the spatial distribution and range of sub-tropical, warm- and cold-water species of intertidal gastropods was explored by a fully hierarchical sampling design considering four different spatial scales, i.e. from region (100 s of km apart) to quadrats (ms apart). Variability on their patterns of abundance was explored by analysis of variance, changes on their distribution ranges were detected by comparing with previous records and their relationship with sea water temperature was explored by rank correlation analyses. Mean values of sea surface temperature along the Iberian coast, between 1949 and 2010, were obtained from in situ data compiled for three different grid squares: south Portugal, north Portugal, and Galicia. Lusitanian species did not show significant correlation with sea water temperature or changes on their distributional range or abundance, along the temperature gradient considered. The sub-tropical species Siphonaria pectinata has, however, increased its distribution range while boreal cold-water species showed the opposite pattern. The latter was more evident for Littorina littorea that was almost absent from the studied rocky shores of the Iberian Peninsula. Sub-tropical and boreal species showed significant but opposite correlation with sea water temperature. We hypothesized that the energetic cost of frequent exposures to sub-lethal temperatures might be responsible for these shifts. Therefore, intertidal gastropods at the Atlantic Iberian Peninsula coast are responding to the effect of global warming as it

  14. Wave energy and intertidal productivity.

    PubMed

    Leigh, E G; Paine, R T; Quinn, J F; Suchanek, T H

    1987-03-01

    In the northeastern Pacific, intertidal zones of the most wave-beaten shores receive more energy from breaking waves than from the sun. Despite severe mortality from winter storms, communities at some wave-beaten sites produce an extraordinary quantity of dry matter per unit area of shore per year. At wave-beaten sites of Tatoosh Island, WA, sea palms, Postelsia palmaeformis, can produce > 10 kg of dry matter, or 1.5 x 10(8) J, per m(2) in a good year. Extraordinarily productive organisms such as Postelsia are restricted to wave-beaten sites. Intertidal organisms cannot transform wave energy into chemical energy, as photosynthetic plants transform solar energy, nor can intertidal organisms "harness" wave energy. Nonetheless, wave energy enhances the productivity of intertidal organisms. On exposed shores, waves increase the capacity of resident algae to acquire nutrients and use sunlight, augment the competitive ability of productive organisms, and protect intertidal residents by knocking away their enemies or preventing them from feeding.

  15. Wave energy and intertidal productivity

    SciTech Connect

    Leigh, E.G. Jr.; Paine, R.T.; Quinn, J.F.; Suchanek, T.H.

    1987-03-01

    In the northern Pacific, intertidal zones of the most wave-beaten shores receive more energy from breaking waves than from the sun. Despite severe mortality from winter storms, communities at some wave-beaten sites produce an extraordinary quantity of dry matter per unit area of shore per year. At wave-beaten sites of Tatoosh Island, WA, sea palms, Postelsia palmaeformis, can produce > 10 kg of dry matter, or 1.5 x 10/sup 8/ J, per m/sup 2/ in a good year. Extraordinarily productive organisms such as Postelsia are restricted to wave-beaten sites. Intertidal organisms cannot transform wave energy into chemical energy, as photosynthetic plants transform solar energy, nor can intertidal organisms harness wave energy. Nonetheless, wave energy enhances the productivity of intertidal organisms. On exposed shores, waves increase the capacity of resident algae to acquire nutrients and use sunlight, augment the competitive ability of productive organism, and protect intertidal residents by knocking away their enemies or preventing them from feeding.

  16. Wave energy and intertidal productivity

    PubMed Central

    Leigh, Egbert G.; Paine, Robert T.; Quinn, James F.; Suchanek, Thomas H.

    1987-01-01

    In the northeastern Pacific, intertidal zones of the most wave-beaten shores receive more energy from breaking waves than from the sun. Despite severe mortality from winter storms, communities at some wave-beaten sites produce an extraordinary quantity of dry matter per unit area of shore per year. At wave-beaten sites of Tatoosh Island, WA, sea palms, Postelsia palmaeformis, can produce > 10 kg of dry matter, or 1.5 × 108 J, per m2 in a good year. Extraordinarily productive organisms such as Postelsia are restricted to wave-beaten sites. Intertidal organisms cannot transform wave energy into chemical energy, as photosynthetic plants transform solar energy, nor can intertidal organisms “harness” wave energy. Nonetheless, wave energy enhances the productivity of intertidal organisms. On exposed shores, waves increase the capacity of resident algae to acquire nutrients and use sunlight, augment the competitive ability of productive organisms, and protect intertidal residents by knocking away their enemies or preventing them from feeding. PMID:16593813

  17. Low-Cost Ultra-High Spatial and Temporal Resolution Mapping of Intertidal Rock Platforms

    NASA Astrophysics Data System (ADS)

    Bryson, M.; Johnson-Roberson, M.; Murphy, R.

    2012-07-01

    Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time which could compliment field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at relatively course, sub-meter resolutions or with limited temporal resolutions and relatively high costs for small-scale environmental science and ecology studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric pipeline that was developed for constructing highresolution, 3D, photo-realistic terrain models of intertidal rocky shores. The processing pipeline uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine colour and topographic information at sub-centimeter resolutions over an area of approximately 100m, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rock platform at Cape Banks, Sydney, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales.

  18. Intertidal coarse woody debris: A spatial subsidy as shelter or feeding habitat for gastropods?

    NASA Astrophysics Data System (ADS)

    Storry, Kristin A.; Weldrick, Christine K.; Mews, Malte; Zimmer, Martin; Jelinski, Dennis E.

    2006-01-01

    Coarse woody debris (CWD) in the intertidal region of rocky shores serves as a potential source of nutrients as well as habitat or refugia from predation, ecologically linking the adjacent marine and terrestrial habitats. In a series of field and laboratory experiments, the affinity of slow-moving motile intertidal gastropods to CWD either as food source or as shelter that increases habitat complexity was tested. In intertidal pools, CWD did not increase colonization by Littorina spp., while it did so in supratidal pools. Habitat complexity, brought about by algal cover and barnacles, was apparently sufficient in intertidal pools without woody debris, while the increase in habitat complexity by CWD increased the attractiveness of supratidal pools with little natural complexity to Littorina spp. Overall, however, comparison of pools containing woody debris and those containing artificial shelter provided evidence for CWD, and/or its biofilm, serving as food source rather than refugium per se. Similarly, Tegula funebralis chose CWD as food source rather than as shelter as indicated by comparison of autoclaved and unmanipulated woody debris. Further, both unfed and fed snails from a site where CWD was present significantly preferred CWD over macroalgae. Among snails from a site without woody debris, fed individuals showed no preference, while unfed snails significantly preferred macroalgae. From this, experience appears to be a factor that mediates the role of CWD. Overall, however, CWD appears to provide supplementary food to snails in the inter- and supratidal zone.

  19. Precisely proportioned: intertidal barnacles alter penis form to suit coastal wave action

    PubMed Central

    Neufeld, Christopher J; Palmer, A. Richard

    2008-01-01

    For their size, barnacles possess the longest penis of any animal (up to eight times their body length). However, as one of few sessile animals to copulate, they face a trade-off between reaching more mates and controlling ever-longer penises in turbulent flow. We observed that penises of an intertidal barnacle (Balanus glandula) from wave-exposed shores were shorter than, stouter than, and more than twice as massive for their length as, those from nearby protected bays. In addition, penis shape variation was tightly correlated with maximum velocity of breaking waves, and, on all shores, larger barnacles had disproportionately stouter penises. Finally, field experiments confirmed that most of this variation was due to phenotypic plasticity: barnacles transplanted to a wave-exposed outer coast produced dramatically shorter and wider penises than counterparts moved to a protected harbour. Owing to the probable trade-off between penis length and ability to function in flow, and owing to the ever-changing wave conditions on rocky shores, intertidal barnacles appear to have acquired the capacity to change the size and shape of their penises to suit local hydrodynamic conditions. This dramatic plasticity in genital form is a valuable reminder that factors other than the usual drivers of genital diversification—female choice, sexual conflict and male–male competition—can influence genital form. PMID:18252665

  20. Precisely proportioned: intertidal barnacles alter penis form to suit coastal wave action.

    PubMed

    Neufeld, Christopher J; Palmer, A Richard

    2008-05-07

    For their size, barnacles possess the longest penis of any animal (up to eight times their body length). However, as one of few sessile animals to copulate, they face a trade-off between reaching more mates and controlling ever-longer penises in turbulent flow. We observed that penises of an intertidal barnacle (Balanus glandula) from wave-exposed shores were shorter than, stouter than, and more than twice as massive for their length as, those from nearby protected bays. In addition, penis shape variation was tightly correlated with maximum velocity of breaking waves, and, on all shores, larger barnacles had disproportionately stouter penises. Finally, field experiments confirmed that most of this variation was due to phenotypic plasticity: barnacles transplanted to a wave-exposed outer coast produced dramatically shorter and wider penises than counterparts moved to a protected harbour. Owing to the probable trade-off between penis length and ability to function in flow, and owing to the ever-changing wave conditions on rocky shores, intertidal barnacles appear to have acquired the capacity to change the size and shape of their penises to suit local hydrodynamic conditions. This dramatic plasticity in genital form is a valuable reminder that factors other than the usual drivers of genital diversification--female choice, sexual conflict and male-male competition--can influence genital form.

  1. Along the Coast & Close to Shore.

    ERIC Educational Resources Information Center

    NatureScope, 1988

    1988-01-01

    Considers the characteristics of beaches, rocky shores, coral reefs, and kelp forests. Discusses plants and animals that live in these habitats. Activities include life between the tides, reef buddies, sea forests, seaside adventure, and four copycat pages. (RT)

  2. Along the Coast & Close to Shore.

    ERIC Educational Resources Information Center

    NatureScope, 1988

    1988-01-01

    Considers the characteristics of beaches, rocky shores, coral reefs, and kelp forests. Discusses plants and animals that live in these habitats. Activities include life between the tides, reef buddies, sea forests, seaside adventure, and four copycat pages. (RT)

  3. Scale of temperature variability in the maritime Antarctic intertidal zone

    NASA Astrophysics Data System (ADS)

    Kuklinski, Piotr; Balazy, Piotr

    2014-01-01

    The Antarctic Peninsula is currently considered as one of the fastest changing regions on Earth yet temperature variability in some of its environments and habitats is not well-documented. Given the increased glacier retreat, summer melts, sea level rise and ozone losses the intertidal zone is likely to be one of the most rapidly altering of environments but also one of the least investigated in polar waters. This study aims to quantify summer temperature variability in some habitats of the intertidal zone at King George Island. Three transects were selected across tidal flat. Four temperature loggers were deployed at each of them from extreme low water spring tide level to extreme high water spring tide level between 07.12.2010 and 18.03.2011. All the loggers were deployed at the rocky substratum. The temperature range across the study tidal flat was between - 2.26 °C and + 21.18 °C. The average (summer) temperature obtained from 12 loggers varied from + 1.89 to + 3.26 °C. In all the three transects average temperature increased with tidal height. Much higher temperature variability was recorded at higher than at lower tide locations. Differences in temperature between the three study transects existed. Results obtained from the studied tidal flat show that several factors combined altogether, including: water movement by tidal forces, wave action, air temperature, sun light intensity, shore lithology and the presence of ice and snow in the area, seem to influence its temperature.

  4. Variation in Community Structure across Vertical Intertidal Stress Gradients: How Does It Compare with Horizontal Variation at Different Scales?

    PubMed Central

    Valdivia, Nelson; Scrosati, Ricardo A.; Molis, Markus; Knox, Amanda S.

    2011-01-01

    In rocky intertidal habitats, the pronounced increase in environmental stress from low to high elevations greatly affects community structure, that is, the combined measure of species identity and their relative abundance. Recent studies have shown that ecological variation also occurs along the coastline at a variety of spatial scales. Little is known, however, on how vertical variation compares with horizontal variation measured at increasing spatial scales (in terms of sampling interval). Because broad-scale processes can generate geographical patterns in community structure, we tested the hypothesis that vertical ecological variation is higher than fine-scale horizontal variation but lower than broad-scale horizontal variation. To test this prediction, we compared the variation in community structure across intertidal elevations on rocky shores of Helgoland Island with independent estimates of horizontal variation measured at the scale of patches (quadrats separated by 10s of cm), sites (quadrats separated by a few m), and shores (quadrats separated by 100s to 1000s of m). The multivariate analyses done on community structure supported our prediction. Specifically, vertical variation was significantly higher than patch- and site-scale horizontal variation but lower than shore-scale horizontal variation. Similar patterns were found for the variation in abundance of foundation taxa such as Fucus spp. and Mastocarpus stellatus, suggesting that the effects of these canopy-forming algae, known to function as ecosystem engineers, may explain part of the observed variability in community structure. Our findings suggest that broad-scale processes affecting species performance increase ecological variability relative to the pervasive fine-scale patchiness already described for marine coasts and the well known variation caused by vertical stress gradients. Our results also indicate that experimental research aiming to understand community structure on marine shores

  5. Substrate use and selection in sympatric intertidal hermit crab species.

    PubMed

    Turra, A; Denadai, M R

    2002-02-01

    Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus) coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud) in allopatric (single species) and sympatric (three species) treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence) of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

  6. Assessing environmental health using ecological indices for soft bottom in sewage-affected rocky shores: The case of the largest seaside resort of SW Atlantic.

    PubMed

    Garaffo, G V; Jaubet, M L; Becherucci, M E; Elías, R

    2017-02-15

    Efficient ecological indices can reflect the differences between impacted and nonimpacted sites, leading to significant variations at the contamination spatial scale. Here, we evaluated the spatial-temporal variability of 3 ecological indices (AMBI, M-AMBI, and BENTIX) in response to the distinct levels of sewage contamination. The indices were evaluated in two different ways: including Brachidontes rodriguezii (IBR) and excluding B. rodriguezii (EBR). The fact that mussel beds create a secondary infaunal habitat allows us to test these indices for soft bottoms in areas with rocky bottoms. The effectiveness and the level of agreement of these indices were increased when they were calculated with EBR. BENTIX and M-AMBI produced under- and overestimations of the ecological status of the studied sites. AMBI (EBR) seems to be better suited for environmental quality assessment in the study area. This index reduces the processing time of samples; thus, the AMBI (EBR) index could be used as a robust management tool for monitoring programs in areas with hard substrate.

  7. The population structure of two sympatric hermit-crab species on a subtidal rocky shore of an island in southeastern Brazil.

    PubMed

    Lima, Daniel J M; Cobo, Valter J; De Aquino, Mariana A B; Fransozo, Adilson

    2014-12-01

    The main goal of this investigation was to characterize the population structure and shell occupancy of two sympatric hermit-crab species, Pagurus brevidactylus and Paguristes tortugae. The study was undertaken at Couves Island on the southeastern coast of Brazil, from March 2010 through February 2011, on subtidal rocky bottoms. Specimens were collected by SCUBA diving sessions. A total of 195 individuals of P. brevidactylus and 132 of P. tortugae were examined. Both populations showed unimodal size-frequency distributions, which were non-normal for P. brevidactylus and normal for P. tortugae. The median size of P. brevidactylus was significantly smaller than P. tortugae; in both species, males were significantly larger than females. For both, juveniles and ovigerous females were recorded in all size classes and in almost the entire sampling period. No significant departures from the 1:1 sex ratio were detected, although some size classes were skewed. Overlaps in shell occupation were recorded. Pagurus brevidactylus and P. tortugae showed similar population features; they reached sexual maturity at small sizes, and the nearly year-round presence of young and ovigerous females suggests continuous reproduction. These inter-specific interactions involving resource partitioning suggest a regulatory process that is probably part of the equilibrium strategy of these populations.

  8. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature.

    PubMed

    Seabra, Rui; Wethey, David S; Santos, António M; Gomes, Filipa; Lima, Fernando P

    2016-10-01

    As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores.

  9. [Diversity patterns in intertidal communities of three southern islands of Changshan archipelago].

    PubMed

    Zhuang, Shuhong; Chen, Lixue; Wang, Zunqing

    2003-05-01

    The diversity pattern of intertidal communities in 3 southern islands of Changshan archipelago were studied. The results showed that the community appearance and structure in rocky intertidal zones of 3 islands were regimented by dominant species Chthamalus challengeri, Ostrea spp., macro-algae and Littorina brevicula, while in gravel intertidal zones of Southern Changshan and Daheishan regimented by Chthamalus challengeri, Littorina brevicula, Ostrea spp., and in Northern Changshan, by Chthamalus challengeri, macro-algae and Gaetice depressus. There existed no obvious difference in community structures of rocky intertidal zones among 3 islands, which was demonstrated by the similarity in first 5 dominant species and their dominance ranks in the community. However, a significant difference was achieved in gravel intertidal communities, in which, the dominant species in the community at Northern Changshan differed greatly from that of others. The community diversity in R, J, D(B), D(IV), H(B), and H(IV), in rocky intertidal communities among 3 islands showed a great coincidence, Northern Changshan > Southern Changshan > Daheishan, however, little coincident results were found among gravel intertidal communities. It was found that there existed a higher community diversity in gravel intertidal communities at Daheishan and Southern Changshan than at Northern Changshan where existed the highest species evenness. The community diversity was generally higher in gravel intertidal communities than in rocky intertidal ones. The variation in community compositions, structures and diversities were resulted mainly from topographical heterogeneities, substratum heterogeneities, hydrodynamics, water eutrophication and human disturbance in intertidal zones.

  10. Self-organization of intertidal snails facilitates evolution of aggregation behavior.

    PubMed

    Stafford, Richard; Davies, Mark S; Williams, Gray A

    2008-01-01

    Many intertidal snails form aggregations during emersion to minimize desiccation stress. Here we investigate possible mechanisms for the evolution of such behavior. Two behavioral traits (following of mucus trails, and crevice occupation), which both provide selective advantages to individuals that possess the traits over individuals that do not, result in self-organization of aggregations in crevices in the rock surface. We suggest that the existence of self-organizing aggregations provides a mechanism by which aggregation behavior can evolve. The inclusion of an explicitly coded third behavior, aggregation, in a simulated population produces patterns statistically similar to those found on real rocky shores. Allowing these three behaviors to evolve using an evolutionary algorithm, however, results in aggregation behavior being selected against on shores with high crevice density. The inclusion of broadcast spawning dispersal mechanisms in the simulation, however, results in aggregation behavior evolving as predicted on shores with both high crevice density and low crevice density (evolving in crevices first, and then both in crevices and on flat rock), indicating the importance of environmental interactions in understanding evolutionary processes. We propose that self-organization can be an important factor in the evolution of group behaviors.

  11. Increase in density of genetically diverse invasive Asian shore crab (Hemigrapsus sanguineus) populations in the Gulf of Maine

    PubMed Central

    Williams, Larissa M.

    2017-01-01

    Hemigrapsus sanguineus, the Asian shore crab, has rapidly replaced Carcinus maenas, the green crab, as the most abundant crab on rocky shores in the northwest Atlantic since its introduction to the United States (USA) in 1988. The northern edge of this progressing invasion is the Gulf of Maine, where Asian shore crabs are only abundant in the south. We compared H. sanguineus population densities to those from published 2005 surveys and quantified genetic variation using the cytochrome c oxidase subunit I gene. We found that the range of H. sanguineus had extended northward since 2005, that population density had increased substantially (at least 10-fold at all sites), and that Asian shore crabs had become the dominant intertidal crab species in New Hampshire and southern Maine. Despite the significant increase in population density of H. sanguineus, populations only increased by a factor of 14 in Maine compared to 70 in southern New England, possibly due to cooler temperatures in the Gulf of Maine. Genetically, populations were predominantly composed of a single haplotype of Japanese, Korean, or Taiwanese origin, although an additional seven haplotypes were found. Six of these haplotypes were of Asian origin, while two are newly described. Large increases in population sizes of genetically diverse individuals in Maine will likely have a large ecological impact, causing a reduction in populations of mussels, barnacles, snails, and other crabs, similar to what has occurred at southern sites with large populations of this invasive crab species. PMID:28919836

  12. Increase in density of genetically diverse invasive Asian shore crab (Hemigrapsus sanguineus) populations in the Gulf of Maine.

    PubMed

    Lord, Joshua P; Williams, Larissa M

    2017-04-01

    Hemigrapsus sanguineus, the Asian shore crab, has rapidly replaced Carcinus maenas, the green crab, as the most abundant crab on rocky shores in the northwest Atlantic since its introduction to the United States (USA) in 1988. The northern edge of this progressing invasion is the Gulf of Maine, where Asian shore crabs are only abundant in the south. We compared H. sanguineus population densities to those from published 2005 surveys and quantified genetic variation using the cytochrome c oxidase subunit I gene. We found that the range of H. sanguineus had extended northward since 2005, that population density had increased substantially (at least 10-fold at all sites), and that Asian shore crabs had become the dominant intertidal crab species in New Hampshire and southern Maine. Despite the significant increase in population density of H. sanguineus, populations only increased by a factor of 14 in Maine compared to 70 in southern New England, possibly due to cooler temperatures in the Gulf of Maine. Genetically, populations were predominantly composed of a single haplotype of Japanese, Korean, or Taiwanese origin, although an additional seven haplotypes were found. Six of these haplotypes were of Asian origin, while two are newly described. Large increases in population sizes of genetically diverse individuals in Maine will likely have a large ecological impact, causing a reduction in populations of mussels, barnacles, snails, and other crabs, similar to what has occurred at southern sites with large populations of this invasive crab species.

  13. Estimating coseismic coastal uplift with an intertidal mussel: calibration for the 2010 Maule Chile earthquake (Mw = 8.8)

    NASA Astrophysics Data System (ADS)

    Melnick, Daniel; Cisternas, Marco; Moreno, Marcos; Norambuena, Ricardo

    2012-05-01

    Coseismic coastal uplift has been quantified using sessile intertidal organisms after several great earthquakes following FitzRoy's pioneer measurements in 1835. A dense survey of such markers may complement space geodetic data to obtain an accurate distribution of fault slip and earthquake segmentation. However, uplift estimates based on diverse intertidal organisms tend to differ, because of few methodological and comparative studies. Here, we calibrate and estimate coastal uplift in the southern segment of the 2010 Maule, Chile earthquake (Mw = 8.8) using >1100 post-earthquake elevation measurements of the sessile mussel Perumytilus purpuratus. This mussel is the predominant competitor for rocky shores all along the Pacific coast of South America, where it forms fringes or belts distinctively in the middle intertidal zone. These belts are centered at mean sea level and their width should equal one third of the tidal range. We measured belt widths close to this value at 40% of the sites, but overall widths are highly variable due to the unevenness in belt tops; belt bases, in turn, are rather regular. Belt top unevenness apparently results from locally-enhanced wave splash, whereas belt base evenness is controlled by predation. According to our measurements made beyond the earthquake rupture, the belt base is at the bottom of the middle intertidal zone, and thus we propose to estimate coastal uplift using the belt base mean elevation plus one sixth of the tidal range to reach mean sea level. Within errors our estimates agree with GPS displacements but differ from other methods. Comparisons of joint inversions for megathrust slip suggest combining space geodetic data with estimates from intertidal organisms may locally increase the detail of slip distributions.

  14. Heat-shock protein 70 (Hsp70) as a biochemical stress indicator: an experimental field test in two congeneric intertidal gastropods (genus: Tegula).

    PubMed

    Tomanek, Lars; Sanford, Eric

    2003-12-01

    Although previous studies have demonstrated that heat-shock protein 70 (Hsp70) can be induced by environmental stress, little is known about natural variation in this response over short time scales. We examined how Hsp70 levels varied over days to weeks in two intertidal snail species of the genus Tegula: Sampling was conducted both under naturally changing environmental conditions and in different vertical zones on a rocky shore. The subtidal to low-intertidal T. brunnea was transplanted into shaded and unshaded mid-intertidal cages to assess temporal variation in Hsps under conditions of increased stress. For comparison, the low to mid-intertidal T. funebralis was transplanted into mid-intertidal cages, within this species' natural zone of occurrence. Snails were sampled every 3 to 4 days for one month, and endogenous levels of two Hsp70-kDa family members (Hsp72 and Hsp74) were quantified using solid-phase immunochemistry. Following periods of midday low tides, levels of Hsps increased greatly in transplanted T. brunnea but not in T. funebralis. Levels of Hsps increased less in T. brunnea transplanted to shaded cages than to unshaded cages, suggesting that prolonged emersion and reduction in feeding time per se are factors that are only mildly stressful. Upregulated levels of Hsps returned to base levels within days. In unmanipulated snails collected from their natural zones, Hsp levels showed little change with thermal variation, indicating that these species did not experience thermally stressful conditions during this study. However, under common conditions in the mid-intertidal zone, Hsp70 levels reflected the different thermal sensitivities of the physiological systems of these two species.

  15. Seascape-dependent subtidal-intertidal trophic linkages.

    PubMed

    Rilov, Gil; Schiel, David R

    2006-03-01

    In this study, we test in southern New Zealand a conceptual model of food web linkage that is seascape dependent, which can explain some of the variability in rocky shore community structure among sites and coasts. Using a comparative-experimental approach at local and distant sites we demonstrate that mobile subtidal predators (fish and crabs) can exert strong predation pressure on small mussels in the low tidal zone, but only in sites where the seascape includes subtidal reefs. On intertidal benches with adjacent subtidal reefs (+SR), 60-100% of small (5-15 mm) transplanted mussels were removed within a day from experimental tiles on the low shore when unprotected from predation, compared to fully caged controls that had approximately 100% survival over several months. In partial cages that exclude fish but not crabs, survivorship was intermediate. In contrast, on benches without subtidal reefs (-SR) 40-100% of mussels survived for months, even if unprotected. This difference is expressed in lower cover (0-60%) of mussels on rocks at +SR benches compared to -SR benches (70-99%). The central to northern west coast of the South Island is composed mostly of -SR benches, and predation on small mussels there was low and similar to the -SR benches on the east coast, whereas the +SR benches on the east coast had much greater predation. This contrasts to other studies in New Zealand that examined only predation on larger mussels by seastars and concluded that predation is strong on the west coast and weak on the east coast. Excluding large predators from low-shore areas with new recruits for a year in one +SR site showed longer-term predation effects on their abundance and cover. Short-term sampling at the east coast sites showed that mussel settlement was greater in -SR compared to +SR sites, providing some evidence that seascapes may also affect settlement. Overall, predation depended on the local seascape and ultimately affected community structure via suppression of

  16. Life on Rocky Shores. Grades K-6.

    ERIC Educational Resources Information Center

    New England Aquarium, Boston, MA.

    Activities in the ecology of New England's tidepools are provided in this field trip guide for elementary school teachers. Resources, curriculum materials, and services are identified that are available through the New England Aquarium's Department of Education. This packet contains: (1) pre-trip activities (offering a vocabulary list,…

  17. Life on Rocky Shores. Grades K-6.

    ERIC Educational Resources Information Center

    New England Aquarium, Boston, MA.

    Activities in the ecology of New England's tidepools are provided in this field trip guide for elementary school teachers. Resources, curriculum materials, and services are identified that are available through the New England Aquarium's Department of Education. This packet contains: (1) pre-trip activities (offering a vocabulary list,…

  18. Thermal stress and predation risk trigger distinct transcriptomic responses in the intertidal snail Nucella lapillus.

    PubMed

    Chu, Nathaniel D; Miller, Luke P; Kaluziak, Stefan T; Trussell, Geoffrey C; Vollmer, Steven V

    2014-12-01

    Thermal stress and predation risk have profound effects on rocky shore organisms, triggering changes in their feeding behaviour, morphology and metabolism. Studies of thermal stress have shown that underpinning such changes in several intertidal species are specific shifts in gene and protein expression (e.g. upregulation of heat-shock proteins). But relatively few studies have examined genetic responses to predation risk. Here, we use next-generation RNA sequencing (RNA-seq) to examine the transcriptomic (mRNA) response of the snail Nucella lapillus to thermal stress and predation risk. We found that like other intertidal species, N. lapillus displays a pronounced genetic response to thermal stress by upregulating many heat-shock proteins and other molecular chaperones. In contrast, the presence of a crab predator (Carcinus maenas) triggered few significant changes in gene expression in our experiment, and this response showed no significant overlap with the snail's response to thermal stress. These different gene expression profiles suggest that thermal stress and predation risk could pose distinct and potentially additive challenges for N. lapillus and that genetic responses to biotic stresses such as predation risk might be more complex and less uniform across species than genetic responses to abiotic stresses such as thermal stress. © 2014 John Wiley & Sons Ltd.

  19. Exposure to solar radiation drives organismal vulnerability to climate: Evidence from an intertidal limpet.

    PubMed

    Chapperon, Coraline; Volkenborn, Nils; Clavier, Jacques; Séité, Sarah; Seabra, Rui; Lima, Fernando P

    2016-04-01

    Understanding the physiological abilities of organisms to cope with heat stress is critical for predictions of species' distributions in response to climate change. We investigated physiological responses (respiration and heart beat rate) of the ectotherm limpet Patella vulgata to heat stress events during emersion and the role of seasonal and microclimatic acclimatization for individual thermal tolerance limits. Individuals were collected from 5 microhabitats characterized by different exposure to solar radiation in the high intertidal zone of a semi-exposed rocky shore in winter and summer of 2014. Upper thermal tolerance limits (heat coma temperatures - HCTs, and heart rate Arrhenius break temperatures - ABTs) were determined for individuals from each microhabitat in both seasons under laboratory conditions. While we found a clear seasonal acclimatization, i.e., higher HCTs and ABTs in summer than in winter, we did not find evidence for microhabitat-specific responses that would suggest microclimatic acclimatization. However, operative limpet temperatures derived from in-situ temperature measurements suggest that individuals from sun exposed microhabitats have a much narrower thermal safety margins than those from less exposed surfaces or within crevices. Microhabitat specific thermal safety margins caused by high thermal heterogeneity at small spatial scales and the lack of short term acclimatization will likely shape small scale distribution patterns of intertidal species in response to the predicted increase in the frequency and intensity of heat waves.

  20. First evidence of biogenic habitat from tubeworms providing a near-absolute habitat requirement for high-intertidal Ulva macroalgae.

    PubMed

    Liversage, Kiran

    2017-01-01

    Disturbances in ecological systems can cause new resources to become available and can free the resources held by strongly competitive species. In intertidal boulder fields, wave-action causes disturbance by overturning boulders and freeing space for re-colonisation. In this study, mensurative experiments showed that boulder disturbance may also cause new biogenic-habitat resources to become available, if pre-disturbance boulders originally had tubeworm encrustations on their undersides. On the high-shore of a South Australian rocky coast, a small proportion of boulders had extensive encrustations of serpulid and spirorbid worm-tubes on their uppersides, and were likely to have recently been overturned, as spirorbid tubeworms are almost always only underneath boulders while living. Ulva macroalgae was absent from all boulders, except those with worm-tubes, where up to 61% Ulva cover was observed. Many boulders with tubes did not, however, have much algae, and this was likely caused by grazing. While limpets were seldom observed attached to tube encrustations, snails such as Nerita atramentosa and Bembicium nanum were equally abundant on and off tubes. N. atramentosa was likely the main grazer, as its densities were negatively correlated with Ulva cover. The mechanism causing association of Ulva and worm-tubes is unknown, but may be related to retention of moisture or algal spores within the complex topography of the tubes. Alternatively, some tubes may still have been living and providing nutrients for Ulva from excretory products. This study takes the first step towards understanding a very distinct habitat requirement which allows an important alga to persist in the hostile environment of the rocky-intertidal high shore.

  1. Detecting human mitigation intervention: effects of sewage treatment upgrade on rocky macrofaunal assemblages.

    PubMed

    Bustamante, María; Bevilacqua, Stanislao; Tajadura, Javier; Terlizzi, Antonio; Saiz-Salinas, José Ignacio

    2012-09-01

    The effectiveness of secondary vs primary treatments of wastewaters in mitigating the effects of sewage discharge on the multivariate structure and diversity of rocky invertebrate assemblages was assessed over a nine-year period through a beyond-BACI experimental design. Assemblages from different tidal levels (i.e. mid-shore, low-shore, 3 m and 8 m subtidal) were sampled at the impact location (I) and three control locations (Cs) at a hierarchy of spatial scales. The improvement in water treatment significantly changed the structure, diversity and cover of low intertidal assemblages. Faunal cover at 8 m subtidal increased significantly after the treatment upgrade at I. The secondary treatment also affected patterns of spatial heterogeneity between I and Cs for mid-shore and 3 m subtidal assemblages. This study demonstrates that powerful experimental designs combined with univariate and multivariate analytical approaches are fundamental in distinguishing the subtle effects of human impact from those of natural processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Trophic relationships on a fucoid shore in south-western Iceland as revealed by stable isotope analyses, laboratory experiments, field observations and gut analyses

    NASA Astrophysics Data System (ADS)

    Steinarsdóttir, M. B.; Ingólfsson, A.; Ólafsson, E.

    2009-04-01

    Rocky shores in the North Atlantic are known for their zonation patterns of both algae and animals, which can be expected to greatly affect food availability to consumers at different height levels on the shore. We tested the hypothesis that consumers would feed on the most abundant suitable food source in their surroundings. In total 36 species/taxa of common primary producers and consumers were sampled for stable isotope analyses from a sheltered fucoid shore at Hvassahraun in south-western Iceland. A selection of these species was also collected seasonally and from different height levels. Feeding experiments, field observations and gut analyses were also conducted. Our results were in good overall agreement with pre-existing knowledge of trophic relationships in the rocky intertidal. Consumers often appeared to be assimilating carbon and nitrogen from the most common diet in their immediate surroundings. The predator Nucella lapillus was thus feeding on different prey at different height levels in accordance with different densities of prey species. When tested in the laboratory, individuals taken from low on the shore would ignore the gastropod Littorina obtusata, uncommon at that height level, even when starved, while individuals from mid-shore readily ate the gastropod. This indicated that some kind of learned behaviour was involved. There were, however, important exceptions, most noteworthy the relatively small contribution to herbivores, both slow moving (the gastropod L. obtusata) and fast moving (the isopod Idotea granulosa and the amphipod Gammarus obtusatus) of the dominant alga at this site, Ascophyllum nodosum. The recent colonizer Fucus serratus seemed to be favoured. Selective feeding was indicated both by isotope signatures as well as by results of feeding experiments. Seasonal migrations of both slow and fast moving species could partly explain patterns observed.

  3. Fish in offshore kelp forests affect recruitment to intertidal barnacle populations.

    PubMed

    Gaines, S D; Roughgarden, J

    1987-01-23

    Kelp forests along the coast of central California harbor juvenile rockfish that prey on the larvae of invertebrates from the rocky intertidal zone. This predation reduces recruitment to barnacle populations to 1/50 of the level in the absence of fish. The dynamics of the intertidal community are thus strongly coupled to the dynamics of the offshore kelp community.

  4. Biomarkers of PAH exposure in an intertidal fish species from Prince William Sound, Alaska: 2004-2005.

    PubMed

    Huggett, Robert J; Neff, Jerry M; Stegeman, John J; Woodin, Bruce; Parker, Keith R; Brown, John S

    2006-10-15

    Polycyclic aromatic hydrocarbon (PAH) exposure biomarkers were measured in high cockscomb prickleback (Anoplarchus purpurescens) fish collected from both previously oiled and unoiled shore in Prince William Sound (PWS), Alaska, to test the hypothesis that fish living in the nearshore environment of the sound were no longer being exposed to PAH from the Exxon Valdez oil spill. Pricklebacks spend their entire lives in the intertidal zone of rocky shores with short-term movements during feeding and breeding restricted to an area of about 15 meters in diameter. Fish were assayed for the PAH exposure biomarkers, bile fluorescent aromatic compounds (FAC), and liver ethoxyresorufin O-deethylase (EROD) activity (a measure of cytochrome P450 1A (CYP1A) monooxygenase activity). Bile FAC concentrations and EROD activities were low and not significantly different in fish from previously oiled and unoiled sites. The similar low EROD activity and bile FAC concentrations in fish from oiled and unoiled shores, supports the hypothesis that these low-level biomarker responses were not caused by exposure of the fish to residues of the spilled oil.

  5. Interspecific comparison of hydrodynamic performance and structural properties among intertidal macroalgae.

    PubMed

    Boller, Michael L; Carrington, Emily

    2007-06-01

    Macroalgae use flexibility and reconfiguration, i.e. the alteration of shape, size and orientation as water velocity increases, to reduce the hydrodynamic forces imposed in the wave-swept rocky intertidal zone. Quantifying the effects of flexibility on hydrodynamic performance is difficult, however, because the mechanisms of reconfiguration vary with water velocity and the relationship between algal solid mechanics and hydrodynamic performance is poorly understood. In this study, the hydrodynamic performance, morphology and solid mechanics of 10 rocky shore macroalgal species were quantified to evaluate the influences of flexibility and morphology on reconfiguration. Hydrodynamic performance was measured in a flume by direct measurement of changes in size and shape during reconfiguration across a wide range of velocities, material stiffness was quantified with standard materials testing, and structural properties were calculated from material and morphological data. Hydrodynamic parameters varied significantly among species, indicating variation in the magnitude of reconfiguration and the velocities required for full reconfiguration. Structural properties also varied among species, and were correlated with hydrodynamic performance in some instances. The relationship between hydrodynamic and structural properties is velocity dependent, such that flexibility influences different aspects of reconfiguration at low and high velocities. Groups are identifiable among species based on hydrodynamic and structural properties, suggesting that these properties are useful for addressing functional-form hypotheses and the effects of hydrodynamic disturbance on macroalgal communities.

  6. Physiological, cellular and biochemical thermal stress response of intertidal shrimps with different vertical distributions: Palaemon elegans and Palaemon serratus.

    PubMed

    Madeira, Diana; Mendonça, Vanessa; Dias, Marta; Roma, Joana; Costa, Pedro M; Larguinho, Miguel; Vinagre, Catarina; Diniz, Mário S

    2015-05-01

    The ability to cope with high temperature variations is a critical factor in intertidal communities. Two species of intertidal rocky shore shrimps (Palaemon sp.) with different vertical distributions were collected from the Portuguese coast in order to test if they were differentially sensitive to thermal stress. Three distinct levels of biological organization (organismal, biochemical, and cellular) were surveyed. The shrimp were exposed to a constant rate of temperature increase of 1°C x h(-1), starting at 20°C until reaching the CTMax (critical thermal maximum). During heat stress, two biomarkers of protein damage were quantified in the muscle via enzyme-linked immunosorbent assays: heat shock proteins HSP70 (hsp70/hsc70) and total ubiquitin. Muscle histopathological alterations caused by temperature were also evaluated. CTMax values were not significantly different between the congeners (P. elegans 33.4 ± 0.5 °C; P. serratus 33.0 ± 0.5 °C). Biomarker levels did not increase along the temperature trial, but P. elegans (higher intertidal) showed higher amounts of HSP70 and total ubiquitin than P. serratus (lower intertidal). HSP70 and total ubiquitin levels showed a positive significant correlation in both species, suggesting that their association is important in thermal tolerance. Histopathological observations of muscle tissue in P. serratus showed no gross alterations due to temperature but did show localized atrophy of muscle fibers at CTMax. In P. elegans, alterations occurred at a larger scale, showing multiple foci of atrophic muscular fascicles caused by necrotic or autolytic processes. In conclusion, Palaemon congeners displayed different responses to stress at a cellular level, with P. elegans having greater biomarker levels and histopathological alterations.

  7. Ecologically informed engineering reduces loss of intertidal biodiversity on artificial shorelines.

    PubMed

    Browne, Mark A; Chapman, M Gee

    2011-10-01

    Worldwide responses to urbanization, expanding populations and climatic change mean biodiverse habitats are replaced with expensive, but necessary infrastructure. Coastal cities support vast expanses of buildings and roads along the coast or on "reclaimed" land, leading to "armouring" of shorelines with walls, revetments and offshore structures to reduce erosion and flooding. Currently infrastructure is designed to meet engineering and financial criteria, without considering its value as habitat, despite artificial shorelines causing loss of intertidal species and altering ecological natural processes that sustain natural biodiversity. Most research on ameliorating these impacts focus on soft-sediment habitats and larger flora (e.g., restoring marshes, encouraging plants to grow on walls). In response to needs for greater collaboration between ecologists and engineers to create infrastructure to better support biodiversity, we show how such collaborations lead to small-scale and inexpensive ecologically informed engineering which reduces loss of species of algae and animals from rocky shores replaced by walls. Adding experimental novel habitats to walls mimicking rock-pools (e.g., cavities, attaching flowerpots) increased numbers of species by 110% within months, in particular mobile animals most affected by replacing natural shores with walls. These advances provide new insights about melding engineering and ecological knowledge to sustain biodiversity in cities.

  8. Trophic structure of two intertidal Fucus spp. communities along a vertical gradient: Similarity and seasonal stability evidenced with δ13C and δ15N

    NASA Astrophysics Data System (ADS)

    Bordeyne, François; Davoult, Dominique; Migné, Aline; Bertaud du Chazaud, Euriell; Leroux, Cédric; Riera, Pascal

    2017-02-01

    Intertidal communities dominated by canopy-forming macroalgae typically exhibit some differences in their specific composition that are related to their location along the emersion gradient of rocky shores. Tidal level is also expected to affect resource availability for both primary producers and consumers, potentially leading to divergence in the trophic structure of these communities. Furthermore, in temperate areas, the alternation of seasons has usually a large influence on the primary production and on life-history traits of numerous species, which may induce some changes in the food webs of intertidal communities. Thus, this study aimed to investigate the trophic structure of two intertidal communities located at different tidal levels, over several seasons. Focusing on the dominant species of primary producers and consumers, the food webs of the Fucus vesiculosus Linnaeus and Fucus serratus Linnaeus communities were studied during four successive seasons, using an isotopic (δ13C and δ15N) approach. Due to the diversity of primary producers and consumers living in these two communities, food webs were relatively complex and composed of several trophic pathways. These food webs remained rather conserved over the successive seasons, even though some variability in isotopic signature and in diet has been highlighted for several species. Finally, despite their location at different tidal levels, the two Fucus spp. communities exhibited nearly the same trophic structure, with common consumer species displaying similar isotopic signature in both of them.

  9. Impacts of the Nakhodka heavy-oil spill on an intertidal ecosystem: an approach to impact evaluation using geographical information system.

    PubMed

    Teruhisa, Komatsu; Masahiro, Nakaoka; Hiroshi, Kawai; Tomoko, Yamamoto; Kouichi, Ohwada

    2003-01-01

    A major heavy-oil spill from the Russian tanker Nakhodka occurred in the Sea of Japan on 2 January 1997. We investigated the impacts of this spill on a rocky intertidal ecosystem along the southern coast of the Sea of Japan. We selected Imago-Ura Cove as our study site to observe temporal changes along the oiled shore, because minimal cleaning effort was made in this area. Field surveys were conducted every autumn and spring from 1997 to 2000. We measured coverage by macroalgae in 1 x 1-m(2) quadrats and counted the animals in 5 x 5-m(2) quadrats along the intertidal zone. Changes in the ecosystem caused by the oil spill were analyzed by applying a geographical information system (GIS) to the Sea of Japan for the first time. The GIS showed that following the accident there were heavily oiled areas in sheltered regions, but these decreased over the three years. It also showed that coverage by macroalgae and the number of animals increased, although some species of algae with microscopic sporophyte generations, and some populations of perennial shellfish, remained stable or decreased during the study period. GIS was able to trace temporal changes in intertidal communities resulting from the impacts of heavy oil on flora and fauna at a spatial scale of 10-100 m. GIS is thus a practical tool for visualizing, analyzing, and monitoring changes in an ecosystem polluted by oil, taking into account topographic differences along the coastline.

  10. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Soave, K.; Saltzman, J.; Begley, H.; Bassett, H.; Hester, M.; Mann, L.; Scott, J.; Ulrich, T.

    2003-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999. In cooperation with the Farallones Marine Sanctuary Association, goals include: 1) To monitor the rocky intertidal habitat and develop a baseline database of density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; and 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary. Student volunteers complete an intensive 22 hour training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students conduct four baseline monitoring surveys three times per year (fall, winter, and late spring) to identify and count key invertebrate and algae species. During 2000-2002, the density of black turban snails, Tegula funebralis, is lowest in the high intertidal zones in winter yet has little seasonal variability in the mid intertidal zones. Most algae species had consistently higher percent cover in the northern transects than the more accessible southern transects. To test the reliability of the student counts, replicate counts of all species were performed. Replicate counts for invertebrate species within the same quadrat along the permanent transects revealed a very small amount of variability, giving us confidence that our monitoring program can provide reliable data. Student volunteers helped to design and install a rocky intertidal information kiosk to greet visitors at the entrance of Duxbury Reef. The kiosk includes pictures and natural history information on key intertidal species as well as tidepooling etiquette. Students lead an annual celebration at Duxbury Reef and lead intertidal walks for

  11. Feeding behaviour of an intertidal snail: Does past environmental stress affect predator choices and prey vulnerability?

    NASA Astrophysics Data System (ADS)

    Gestoso, Ignacio; Arenas, Francisco; Olabarria, Celia

    2015-03-01

    Predation is one of the most important factors in determining structure and dynamics of communities on intertidal rocky shores. Such regulatory role may be of special relevance in novel communities resulting from biological invasions. Non-indigenous species frequently escape natural predators that limit their distribution and abundance in the native range. However, biological interactions also can limit the establishment and spread of non-native populations. There is a growing concern that climate change might affect predator-prey interactions exacerbating the ecological impacts of non-indigenous species. However, mechanisms underlying such interactions are poorly understood in marine ecosystems. Here, we explored if past environmental stress, i.e., increasing temperature and decreasing pH, could affect the vulnerability of two mussel prey, the native Mytilus galloprovincialis and the non-indigenous Xenostrobus securis, to predation by the native dogwhelk Nucella lapillus. In addition, we evaluated the consequences on the feeding behaviour of N. lapillus. First, we exposed monospecific assemblages of each mussel species to combined experimental conditions of increasing temperature and decreasing pH in mesocosms for 3 weeks. Then assemblages were placed on a rocky shore and were enclosed in cages with dogwhelks where they remained for 3 weeks. Despite the lack of preference, consumption was much greater on the native than on the invasive mussels, which barely were consumed by dogwhelks. However, this trend was diverted when temperature increased. Thus, under a coastal warming scenario shifts in dogwhelks feeding behaviour may help to contain invader's populations, especially in estuarine areas where these predators are abundant.

  12. Phylogeography and historical ecology of the North Atlantic intertidal.

    PubMed

    Wares, J P; Cunningham, C W

    2001-12-01

    Recent glaciation covered the full extent of rocky intertidal habitat along the coasts of New England and the Canadian Maritimes. To test whether this glaciation in fact caused wholesale extinction of obligate rocky intertidal invertebrates, and thus required a recolonization from Europe, we compared American and European populations using allelic diversity and techniques adapted from coalescent theory. Mitochondrial DNA sequences were collected from amphi-Atlantic populations of three cold-temperate obligate rocky intertidal species (a barnacle, Semibalanus balanoides, and two gastropods, Nucella lapillus and Littorina obtusata) and three cold-temperate habitat generalist species (a seastar, Asterias rubens; a mussel, Mytilus edulis, and an isopod, Idotea balthica). For many of these species we were able to estimate the lineage-specific mutation rate based on trans-Arctic divergences between Pacific and Atlantic taxa. These data indicate that some obligate rocky intertidal taxa have colonized New England from European populations. However, the patterns of persistence in North America indicate that other life-history traits, including mech anisms of dispersal, may be more important for surviving dramatic environmental and climatic change.

  13. Comparative study on the fauna composition of intertidal invertebrates between natural and artificial substrata in the northeastern coast of Jeju Island

    NASA Astrophysics Data System (ADS)

    Cha, Jae-Hoon; Kim, Kwang-Bae; Song, Ji-Na; Kim, In-Soo; Seo, Jeong-Bin; Kwoun, Chul-Hwi

    2013-12-01

    This study was carried out to learn about differences in the sessile macrobenthic fauna communities between the artificial and natural habitats. There were some differences in terms of species composition and dominant species and community structure between two habitat types. The dominant species include Pollicipes mitella and Granuilittorina exigua in natural rocky intertidal zones; Monodonta labio confusa, Ligia exotica, Tetraclita japonica in the artificial rocky intertidal zones. Among all the species, L. exotica and T. japonica occurred only in the artificial rocky intertidal zone. The results of cluster analysis and nMDS analysis showed a distinct difference in community structure between artificial and natural rocky intertidal zones. The fauna in the natural rocky intertidal zones were similar to each other and the fauna in the artificial rocky intertidal zones were divided depending on the slope of the substratum. In the case of a sloping tetrapod, M. labio confusa and P. mitella were dominant, but at the vertical artificial seawall, Cellana nigrolineata, L. exotica T. japonica were dominant. The analysis of the species presented in natural and artificial rocky intertidal areas showed the exclusive presence of 10 species on natural rocks and 12 species on artificial rocks. The species in the natural rocky intertidal area included mobile gastropods and cnidarians (i.e. rock anemones), and the species in the artificial rocky intertidal area mostly included non-mobile attached animals. The artificial novel structure seems to contribute to increasing the heterogeneity of habitats for marine invertebrate species and an increase the species diversity in rocky coastal areas.

  14. Variation in thermal stress response in two populations of the brown seaweed, Fucus distichus, from the Arctic and subarctic intertidal

    PubMed Central

    Smolina, Irina; Kollias, Spyros; Jueterbock, Alexander; Coyer, James A.; Hoarau, Galice

    2016-01-01

    It is unclear whether intertidal organisms are ‘preadapted’ to cope with the increase of temperature and temperature variability or if they are currently at their thermal tolerance limits. To address the dichotomy, we focused on an important ecosystem engineer of the Arctic intertidal rocky shores, the seaweed Fucus distichus and investigated thermal stress responses of two populations from different temperature regimes (Svalbard and Kirkenes, Norway). Thermal stress responses at 20°C, 24°C and 28°C were assessed by measuring photosynthetic performance and expression of heat shock protein (HSP) genes (shsp, hsp90 and hsp70). We detected population-specific responses between the two populations of F. distichus, as the Svalbard population revealed a smaller decrease in photosynthesis performance but a greater activation of molecular defence mechanisms (indicated by a wider repertoire of HSP genes and their stronger upregulation) compared with the Kirkenes population. Although the temperatures used in our study exceed temperatures encountered by F. distichus at the study sites, we believe response to these temperatures may serve as a proxy for the species’ potential to respond to climate-related stresses. PMID:26909170

  15. The effect of a species-specific avoidance response to predatory starfish on the intertidal distribution of two gastropods.

    PubMed

    Phillips, David W

    1976-06-01

    The gastropodsAcmaea (Collisella) limatula andAcmaea (Notoacmea) scutum respond to water flowing over certain predatory starfish (i.e. to the scent of the starfish) by moving rapidly up a submerged, vertical surface. These limpets respond with upward movement to the scent ofPisaster ochraceus, Pisaster giganteus, Pycnopodia helianthoides, andLeptasterias aequalis. All of these starfish are predators on molluscs and at least occasionally inhabit the intertidal. In contrast, the limpets respond weakly or not at all to the scent ofPatiria miniata andPisaster brevispinus. Patiria is an omnivorous scavenger, andP. brevispinus is predaceous but strictly subtidal when it occurs on rocky shores. For the starfish tested, then, the limpets only give avoidance responses to starfish species naturally encountered as predators.The avoidance response ofA. limatula andA. scutum to predatory stafish can also be demonstrated in the field. When onePisaster ochraceus is placed beneath a population of limpets in the intertidal and confined so that contacts between the starfish and limpets are impossible, the limpet population is displaced significantly upward after one tidal cycle. In addition, the closer the limpets are to the starfish, the greater is their upward displacement.

  16. Variation in thermal stress response in two populations of the brown seaweed, Fucus distichus, from the Arctic and subarctic intertidal.

    PubMed

    Smolina, Irina; Kollias, Spyros; Jueterbock, Alexander; Coyer, James A; Hoarau, Galice

    2016-01-01

    It is unclear whether intertidal organisms are 'preadapted' to cope with the increase of temperature and temperature variability or if they are currently at their thermal tolerance limits. To address the dichotomy, we focused on an important ecosystem engineer of the Arctic intertidal rocky shores, the seaweed Fucus distichus and investigated thermal stress responses of two populations from different temperature regimes (Svalbard and Kirkenes, Norway). Thermal stress responses at 20°C, 24°C and 28°C were assessed by measuring photosynthetic performance and expression of heat shock protein (HSP) genes (shsp, hsp90 and hsp70). We detected population-specific responses between the two populations of F. distichus, as the Svalbard population revealed a smaller decrease in photosynthesis performance but a greater activation of molecular defence mechanisms (indicated by a wider repertoire of HSP genes and their stronger upregulation) compared with the Kirkenes population. Although the temperatures used in our study exceed temperatures encountered by F. distichus at the study sites, we believe response to these temperatures may serve as a proxy for the species' potential to respond to climate-related stresses.

  17. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Soave, K.; Saltzman, J.; Scott, J.; Harris, S.; Miles, E.; Neill, M.; Bergmann, S.; Storm, E.; Verkozen, A.; Steiger, R.; Lefebvre, M.

    2004-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; and 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary. Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students conduct two baseline monitoring surveys three times per year (fall, winter, and late spring) to identify and count key invertebrate and algae species. During four seasons of monitoring (2000-2004), the density of black turban snails, Tegula funebralis, showed very low density in the high intertidal zone the winter of 2000-2001 with very little seasonal variability in the remainder of its range and throughout the period monitored. Most algae species had consistently higher densities in the northern (A) transects than the more accessible southern (B) transects. To test the reliability of the student counts, replicate counts of all species were performed. Replicate counts for invertebrate species within the same quadrat along the permanent transects revealed a very small amount of variability, giving us confidence that our monitoring program can provide reliable data. Student volunteers helped to design and install a rocky intertidal information kiosk to greet visitors at the entrance of Duxbury Reef. The kiosk includes pictures and natural history information on key

  18. Erosion of rocky carbonate coastlines: Andros Island, Bahamas

    SciTech Connect

    Donn, T.F.; Boardman, M.R.

    1985-01-01

    Erosion of rocky carbonate coastlines has been monitored at intertidal and supratidal locations on Andros Island, Bahamas. The monitoring method involves periodic direct measurement of over 1000 points on a 0.25 square meter surface of rock. Comparisons are made between initial surface morphology and subsequent surface morphologies in order to measure rates and patterns of erosion. Rates of intertidal erosion vary from 2.5 meters/1000 years to 5.0 meters/1000 years, with an average of 3.1 meters/1000 years. The lack of wave action, combined with an absence of bioeroding organisms such as gastropods, chitons, sponges, worms and barnacles, which exist in the intertidal zone, causes the supratidal rate of erosion to be much lower than the rate of intertidal erosion. Degradation of rocky coastlines results in island retreat as well as the production of a large amount of sediment which is deposited in adjacent lagoons. Much of the sediment produced by bioerosion of these peloidal limestones exists as fecal pellets and sponge chips which are calcite. The erosion of rocky intertidal escarpments creates terraces and notches which lie near low-tide level. The width of the intertidal terraces of Andros Island aids our understanding of the duration of the most recent stillstand of sea level. Terraces and notches at other elevations indicate former stillstands.

  19. Intertidal sea stars (Pisaster ochraceus) alter body shape in response to wave action.

    PubMed

    Hayne, Kurtis J R; Palmer, A Richard

    2013-05-01

    Sea stars are some of the largest mobile animals able to live in the harsh flow environment of wave-exposed, rocky intertidal shores. In addition, some species, such as the northeastern Pacific Pisaster ochraceus, are ecologically significant predators in a broad range of environments, from sheltered lagoons to the most wave-exposed shorelines. How they function and survive under such an extreme range of wave exposures remains a puzzle. Here we examine the ability of P. ochraceus to alter body form in response to variation in flow conditions. We found that sea stars in wave-exposed sites had narrower arms and were lighter per unit arm length than those from sheltered sites. Body form was tightly correlated with maximum velocity of breaking waves across four sites and also varied over time. In addition, field transplant experiments showed that these differences in shape were due primarily to phenotypic plasticity. Sea stars transplanted from a sheltered site to a more wave-exposed site became lighter per unit arm length, and developed narrower arms, after 3 months. The tight correlation between water flow and morphology suggests that wave force must be a significant selective factor acting on body shape. On exposed shores, narrower arms probably reduce both lift and drag in breaking waves. On protected shores, fatter arms may provide more thermal inertia to resist overheating, or more body volume for gametes. Such plastic changes in body shape represent a unique method by which sea stars adapt to spatial, seasonal and possibly short-term variation in flow conditions.

  20. Differential response of benthic macrofauna to the formation of novel oyster reefs ( Crassostrea gigas, Thunberg) on soft and rocky substrate in the intertidal of the Bay of Brest, France

    NASA Astrophysics Data System (ADS)

    Lejart, Morgane; Hily, Christian

    2011-01-01

    When the Pacific oyster ( Crassostrea gigas, Thunberg) was introduced into France for aquaculture in the mid-sixties, it was initially confined to the sites where it was farmed. Subsequent global warming most likely facilitated the establishment of wild populations throughout the French coastline. This phenomenon of spread has become so great that oyster reefs have recently appeared in sheltered estuaries, on both soft and hard substrate. The present study examined two such sites in the Bay of Brest, Brittany. It is the first to investigate the impacts of this new substrate on the biocoenosis of uncolonised intertidal habitats in France. Increased species richness and abundance of intertidal macrofauna were observed in the presence of oyster reefs on both, mud (4 and 20 fold respectively) and rock (5 fold for both). The dominance of suspension feeders in mud changed to carnivores in reefs and their underlying sediment. Calculation of biotic coefficients (BC) of the soft-bottom fauna revealed only a slight organic enrichment, and the organic and silt composition in the sediment beneath oyster reefs were not significantly different from that on bare sites. On rock, the dominance of grazers remained unchanged between bare rock and oyster reef, while reef on rock was also characterised by deposit and detritic feeders. C. gigas is suspected to cause a homogenisation of coastal habitats with an impoverishment of overall quality but we detected only 11 common species between reefs on mud (60 species) and those on rock (55 species).

  1. Rapid changes in the physical properties of rock and concrete during intertidal exposure; implications for weathering and engineering durability

    NASA Astrophysics Data System (ADS)

    Coombes, Martin A.; Naylor, Larissa A.; Feal-Pérez, Alejandra

    2010-05-01

    Water absorption is an important parameter affecting the susceptibility of rocky shore substrates and construction materials to wetting-drying, salt weathering and dissolution processes exposed in the intertidal zone. Strength is also an important determinant of durability and resistance to erosion processes such as abrasion. Here we examine changes in the water absorption properties and strength of representative materials used in the construction of coastal defences after 8 months exposure in the intertidal zone. Blocks of Portland limestone, Cornish granite and marine concrete were attached to shore platforms in Cornwall, UK, at Mean Tide Level. After 8 months exposure, Water Absorption Capacity (WAC) was determined (in both fresh water and synthetic seawater) for exposed and control samples, and strength was measured using Point Load and Equotip surface hardness tests. Differences between exposed and control samples were examined with ANOVA, using material type (3 levels; limestone, granite and concrete) and treatment (2 levels; control and field exposed) as fixed factors. There were significant differences in the WAC of field exposed materials compared to unexposed controls after 8 months (p = 0.02). Post-hoc Student Newman Kuels (SNK) tests also revealed significant material x treatment combinations in both fresh and synthetic seawater (p < 0.01). Field exposed concrete had lower water absorption compared to controls (p < 0.05), which was associated with the development of a surface bio-chemical crust (observed using SEM) and an increase in surface hardness (Equotip test, Student's t-test p = 0.05). In contrast, WAC of limestone in fresh and synthetic seawater was higher for exposed samples compared to controls, but was only significant in fresh water (p = 0.05). SEM examination suggests that extensive borehole erosion of exposed limestone probably explains these differences. Surface hardness of exposed limestone was lower than controls, which may also be

  2. Seasonal variations in the water quality, diversity and population ecology of intertidal macrofauna at an industrially influenced coast.

    PubMed

    Vaghela, A; Bhadja, P; Ramoliya, J; Patel, N; Kundu, R

    2010-01-01

    Present communication reports the physico-chemical and biological quality of seawater and status of benthos of a highly industrialized shore of the north-western coastline of India. The coastal area considered for the present study, encircled by a variety of industries, was divided into two sampling sites and monitored for two consecutive years. Results of the water quality suggest that the obtained values of the physical and chemical parameters of seawater were comparable with data reported earlier. However, data obtained in the biological parameters of the seawater showed a declining trend. Results of the intertidal macrofaunal diversity studies revealed that the muddy upper littoral zones were represented by few species of coelenterata, porifera, arthropoda and mollusca. In the rocky-muddy middle littoral zones, gastropods, stars fishes, corallites, crabs, polychetes and tubeworms were present, whereas, predominantly rocky lower littoral zones were comparatively rich in macrofaunal diversity with small patches of coral colonies. However, when the results obtained in the present study was compared with that of earlier reported data, it was clear that the macrofaunal diversity indeed declined considerably over the years. This may be due to habitat destruction and habitat alteration in the coastline caused by increased anthropogenic activities in the area. Seasonal variations in the population density and abundance were observed in most of the faunal groups except in sessile corals and sponges. This may be due to local migration of the faunal groups towards deeper regions of the Gulf, as supported by the analysis of similarity, to avoid influx of freshwater during monsoon, and high temperature during summer and post monsoon seasons. The overall assessment of different parameters of this study revealed that though the physico- chemical characteristics of the seawater did not varied much from the earlier reported status, the biological characteristics of the seawater

  3. Shifts in intertidal zonation and refuge use by prey after mass mortalities of two predators.

    PubMed

    Gravem, Sarah A; Morgan, Steven G

    2017-04-01

    Recent mass mortalities of two predatory sea star species provided an unprecedented opportunity to test the effect of predators on rocky intertidal prey. Mass mortalities provide insight that manipulative experiments cannot because they alter ecosystems on a larger scale, for longer time periods, and remove both organisms and their cues from the environment. We examined shifts in population size structure, vertical zonation, and use of emersed refuge habitats outside tidepools by the abundant herbivorous black turban snail Tegula funebralis, both before and after the successive mortalities of two predatory sea stars. The small cryptic predator Leptasterias spp. suffered a localized but extreme mortality event in November 2010, followed by two mass mortalities of the keystone predator Pisaster ochraceus in August 2011 and autumn 2013. After the local extinction of Leptasterias, the population size of Tegula more than doubled. Also, since Leptasterias primarily inhabited only mid to low intertidal tidepools at this site, small and medium sized snails (which are preferred by Leptasterias) shifted lower in the intertidal and into tidepools after the mortality of Leptasterias. After the mortality of Pisaster in August 2011, large snails did not shift lower in the intertidal zone despite being preferred by Pisaster. Small and medium sized snails became denser in the higher zone and outside tidepools, which was not likely due to Pisaster mortality. Previous studies concluded that Pisaster maintained vertical size gradients of snails, but our data implicate the overlooked predator Leptasterias as the primary cause. This natural experiment indicated that (1) predators exert top-down control over prey population sizes and lower limits, (2) vertical zonation of prey are dynamic and controlled in part by prey behavior, and (3) predators exert the strongest effects on more vulnerable individuals, which typically inhabit stressful habitats higher on the shore or outside

  4. Sustainable Seas Intertidal Monitoring Project at Duxbury Reef

    NASA Astrophysics Data System (ADS)

    Soave, K. S.; Dean, A.; Gusman, V.; McCracken, K.; Solli, S.; Storm, E.; Placeholder, P.

    2007-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students conduct two baseline-monitoring surveys three times per year (fall, winter, and late spring) to identify and count key invertebrate and algae species. Seasonal abundance of the algae species Mastocarpus and Fucus revealed lower populations in the spring monitoring events. Turban snails, Tegula funebralis, also showed dramatic population variation with respect to tidal zone. One of our project goals is to monitor this area long enough to obtain trends and to begin to connect these patterns to contributing factors (specific weather events, anthropogenic impacts, etc). Replicate counts of all species are regularly performed. Replicate counts for invertebrate and algae species within the same quadrat along the permanent transects revealed a very small amount of variability, giving us confidence that our monitoring program is providing

  5. Morphological and molecular evidence on the existence of a single estuarine and rocky intertidal acanthocephalan species of Profilicollis Meyer, 1931 (Acanthocephala: Polymorphidae) along the Atlantic and Pacific coasts of southern South America.

    PubMed

    Rodríguez, Sara M; Diaz, Julia I; D'Elía, Guillermo

    2017-03-23

    Profilicollis chasmagnathi Holcman-Spector, Mañé-Garzón & Dei-Cas, 1977 (Acanthocephala: Polymorphidae) has been reported to parasitise different grapsid species as intermediate hosts along the South Atlantic shores, i.e. Cyrtograpsus angulatus (Dana) and Neohelice granulata (Dana) in Uruguay and Cyrtograpsus altimanus (Rathbun) in Argentina. Larvae of a similar acanthocephalan described as Profilicollis antarcticus Zdzitowiecki, 1985 were recorded in the crab Hemigrapsus crenulatus (Milne-Edwards) from an estuarine habitat on the Southeast Pacific shore in Chile. Earlier studies have questioned the specific assignation of the Chilean estuarine populations of Profilicollis Meyer, 1931. The aim of this study was to re-examine the identification of these acanthocephalans by means of morphological and molecular analyses of cystacanths of Profilicollis spp. gathered from C. angulatus, N. granulata, C. altimanus and H. crenulatus. Our analyses showed that a single species of Profilicollis, P. chasmagnathi, parasitises these four crab species. The assessment of specimens from the South Shetlands Islands, the type-locality of P. antarcticus, is needed before formally proposing that P. antarcticus is a junior subjective synonym of P. chasmagnathi.

  6. Isotopic shift for defining habitat exploitation by the Antarctic limpet Nacella concinna from rocky coastal habitats (Marian Cove, King George Island)

    NASA Astrophysics Data System (ADS)

    Choy, Eun Jung; Park, Hyun; Kim, Jeong-Hoon; Ahn, In-Young; Kang, Chang-Keun

    2011-05-01

    δ 13C and δ 15N of the Antarctic limpet Nacella concinna tissues and their potential food sources were used to determine their dietary origins and their movements between diverse habitats of intertidal and subtidal rocky shores and tide pools of Marian Cove, King George Island, Antarctica in the austral summer. δ 13C and δ 15N of the organic matter sources of epilithic microalgae, macroalgae and suspended particulate organic matter (SPOM) were readily distinguishable to discern their relative contribution to the limpet diets, with the most depleted values being found in SPOM and the most enriched in macroalgae. The limpets exhibited a spatial trend in distribution due to their seasonal migration, with smaller individuals in the subtidal zone compared with larger ones on the intertidal sites. The limpet isotopes had relatively broad ranges of δ 13C and δ 15N (-26.6 to -12.8‰ and 2.6-7.1‰, respectively), suggesting a dietary shift between habitats as well as size classes. The stable isotope ratios for each habitat seem likely to reflect the differing availabilities of the three potential food sources. Isotope mixing model results indicate a spatial shift in dietary mixture between habitats as well as limpet size classes. Epilithic microalgae and phytoplankton made great contributions to the diet of the subtidal limpets. Together with epilithic microalgae, macroalgae were significant contributors to the intertidal limpets where macroalgae were abundant. A higher contribution of macroalgae to the limpet diets was found in the tide pools. In contrast, while phytoplankton was an important food source for the limpet spat, a great dietary dependence on epilithic microalgae was found in the small-size limpets from the lower intertidal zone. Our results suggest that limpet grazing can determine microalgal and/or macroalgal abundance and coverage on the Antarctic rocky-shore ecosystem, and trophic structure of benthic food web can change along environmental

  7. Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community.

    PubMed

    Aguilera, Moisés A; Valdivia, Nelson; Broitman, Bernardo R

    2015-01-01

    There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S), the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape.

  8. Herbivore-Alga Interaction Strength Influences Spatial Heterogeneity in a Kelp-Dominated Intertidal Community

    PubMed Central

    Aguilera, Moisés A.; Valdivia, Nelson; Broitman, Bernardo R.

    2015-01-01

    There is a general consensus that marine herbivores can affect algal species composition and abundance, but little empirical work exists on the role of herbivores as modifiers of the spatial structure of resource assemblages. Here, we test the consumption/bulldozing effects of the molluscan grazer Enoplochiton niger and its influence on the spatial structure of a low intertidal community dominated by the bull kelp Durvillaea antarctica and the kelp Lessonia spicata. Through field experiments conducted at a rocky intertidal shore in north-central Chile (~30°-32°S), the edge of the grazer and algae geographic distributions, we estimated the strength and variability of consumptive effects of the grazer on different functional group of algae. We also used data from abundance field surveys to evaluate spatial co-occurrence patterns of the study species. Exclusion-enclosure experiments showed that E. niger maintained primary space available by preventing algal colonization, even of large brown algae species. The grazing activity of E. niger also reduced spatial heterogeneity of the ephemeral algal species, increasing bare space availability and variability through time in similar ways to those observed for the collective effect with other grazers. Overall, our result suggests that E. niger can be considered an important modifier of the spatial structure of the large brown algae-dominated community. Effects of E. niger on resource variability seem to be directly related to its foraging patterns, large body size, and population densities, which are all relevant factors for management and conservation of the large brown algae community. Our study thus highlights the importance of considering functional roles and identity of generalist consumers on spatial structure of the entire landscape. PMID:26360294

  9. Interactions between wave action and grazing control the distribution of intertidal macroalgae.

    PubMed

    Jonsson, Per R; Granhag, Lena; Moschella, Paula S; Aberg, Per; Hawkins, Stephen J; Thompson, Richard C

    2006-05-01

    Canopy-forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave-induced forces and grazing for the recruitment and survival of the canopy-forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long-term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7-8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or prune Fucus spp. larger than approximately 10 cm, while dislodgment was highly unlikely on the landward side for all sizes. Experimental transplantation of Fucus spp. supported the biomechanical analysis but also suggested that mechanical abrasion may further limit survival in wave-exposed locations. Experimental removal of the limpet Patella vulgata, which was the principal grazer at this site, resulted in recruitment of Fucus spp. on the seaward side. We present a model of limpet grazing that indicates that limpet densities >5-20 individuals/m2 provide a proximate mechanism preventing establishment of Fucus spp., whereas wave action >2 m/s reduces persistence through dislodgment and battering. In a conceptual model we further propose that recruitment and survival of juvenile Fucus spp. are controlled indirectly by wave exposure through higher limpet densities at exposed locations. This model predicts that climate change, and in particular an increased frequency of storm events in the northeast Atlantic, will restrict fucoids to more sheltered locations.

  10. Facing the Heat: Does Desiccation and Thermal Stress Explain Patterns of Orientation in an Intertidal Invertebrate?

    PubMed

    Fraser, Clarissa M L; Seebacher, Frank; Lathlean, Justin; Coleman, Ross A

    2016-01-01

    A key challenge for ecologists is to quantify, explain and predict the ecology and behaviour of animals from knowledge of their basic physiology. Compared to our knowledge of many other types of distribution and behaviour, and how these are linked to individual function, we have a poor level of understanding of the causal basis for orientation behaviours. Most explanations for patterns of animal orientation assume that animals will modify their exposure to environmental factors by altering their orientation. We used a keystone grazer on rocky shores, the limpet Cellana tramoserica, to test this idea. Manipulative experiments were done to evaluate whether orientation during emersion affected limpet desiccation or body temperature. Body temperature was determined from infrared thermography, a technique that minimises disturbance to the test organism. No causal relationships were found between orientation and (i) level of desiccation and (ii) their body temperature. These results add to the growing knowledge that responses to desiccation and thermal stress may be less important in modifying the behaviour of intertidal organisms than previously supposed and that thermoregulation does not always reflect patterns of animal orientation. Much of what we understand about orientation comes from studies of animals able to modify orientation over very short time scales. Our data suggests that for animals whose location is less flexible, orientation decisions may have less to do with responses to environmental factors and more to do with structural habitat properties or intrinsic individual attributes. Therefore we suggest future studies into processes affecting orientation must include organisms with differing levels of behavioural plasticity.

  11. Heavy-tailed distributions in the intermittent motion behaviour of the intertidal gastropod Littorina littorea

    NASA Astrophysics Data System (ADS)

    Seuront, Laurent; Duponchel, Anne-Charlotte; Chapperon, Coraline

    2007-11-01

    The two-dimensional motion behaviour of the common intertidal gastropod Littorina littorea is investigated as a function of the immersion time from three sampling sites on an exposed rocky shore. A total of 90 individuals have been individually marked and tracked over 14 consecutive daylight low tide. Successive displacements show very intermittent behaviour, with a few localised large displacements over a wide range of small displacements. We show that successive displacements are described by flight length l d heavy-tailed distributions with P(ld)∼ld-μ. The very low values of the exponent μ ( μ≈2.22, 2.43 and 2.67) indicate that L. littorea flights fall into the category of super-diffusive processes. These exponents were significantly higher than the special value μ≈2 analytically and theoretically predicted to be the most advantageous in optimising long-term encounter statistics, especially for low-prey-density scenario. As natural selection should favour flexible behaviour, leading to different optimum searching statistics, under different conditions, our results support the idea that the differences in food concentration and distribution encountered at the different sites by L. littorea led to different heavy-tailed distributions observed for the most extreme displacements.

  12. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Broad, C.; Soave, K.; Ericson, W.; Raabe, B.; Glazer, R.; Ahuatzi, A.; Pereira, M.; Rainsford, A.

    2013-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within two permanent 100 m2 areas, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will once again compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis, Anthopluera elegantissima and Fucus spp. We will continue to closely monitor algal population densities in within our site in light of the November 2007 San Francisco Bay oil spill that leaked heavy bunker fuel into intertidal habitats around the SF Bay. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef

  13. Impact of the Phaeocystis globosa spring bloom on the intertidal benthic compartment in the eastern English Channel: a synthesis.

    PubMed

    Spilmont, Nicolas; Denis, Lionel; Artigas, Luis Felipe; Caloin, Frédéric; Courcot, Lucie; Créach, Anne; Desroy, Nicolas; Gevaert, François; Hacquebart, Pascal; Hubas, Cédric; Janquin, Marie-Andrée; Lemoine, Yves; Luczak, Christophe; Migné, Aline; Rauch, Mathieu; Davoult, Dominique

    2009-01-01

    From 1999 to 2005, studies carried out in the frame of regional and national French programs aimed to determine whether the Phaeocystis globosa bloom affected the intertidal benthic communities of the French coast of the eastern English Channel in terms of composition and/or functioning. Study sites were chosen to cover most of the typical shore types encountered on this coast (a rocky shore, an exposed sandy beach and a small estuary). Both the presence of active Phaeocystis cells and their degradation product (foam) did have a significant impact on the studied shores. The primary production and growth rates of the kelp Saccharina latissima decreased during the bloom because of a shortage of light and nutrient for the macroalgae. On sandy sediments, the benthic metabolism (community respiration and community primary production), as well as the nitrification rate, were enhanced during foam deposits, in relation with the presence of bacteria and active pelagic cells within the decaying colonies. In estuarine sediments, the most impressive impact was the formation of a crust at the sediment surface due to drying foam. This led to anoxic conditions in the surface sediment and resulted in a high mortality among the benthic community. Some organisms also tended to migrate upward and were then directly accessible to the higher trophic level represented by birds. Phaeocystis then created a shortcut in the estuarine trophic network. Most of these modifications lasted shortly and all the systems considered came back to their regular properties and activities a few weeks after the end of the bloom, except for the most impacted estuarine area.

  14. Sustainable Seas Student Intertidal Monitoring Project, Duxbury Reef, Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Prescutti, K.; Ball, O.; Chang, E.; Darakananda, K.; Jessup, K.; Poutian, J.; Schwalbe, H.; Storm, E.

    2008-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program and Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B), and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will analyze the population densities of aggregating anemones, Anthopleura elegantissima, for seasonal abundance variations as well as long-term population trends. We will also follow the seasonal and long-term population fluctuations of red algal turf, Endocladia muricata and Gelidium coulteri, and black turban snails, Tegula funebralis. Comparing populations of turf algae and the herbivorous black turban snails gathered before and after the November 7, 2007 San Francisco Bay oil spill shows very little impact on the Duxbury Reef intertidal inhabitants. Future analyses will

  15. Intergametophytic selfing and microgeographic genetic structure shape populations of the intertidal red seaweed Chondrus crispus.

    PubMed

    Krueger-Hadfield, S A; Roze, D; Mauger, S; Valero, M

    2013-06-01

    Understanding how abiotic factors influence the spatial distribution of genetic variation provides insight into microevolutionary processes. The intertidal seascape is characterized by highly heterogeneous habitats which probably influence the partitioning of genetic variation at very small scales. The effects of tidal height on genetic variation in both the haploid (gametophytes) and diploid (tetrasporophytes) stages of the red alga Chondrus crispus were studied. Fronds were sampled every 25 cm within a 5 m × 5 m grid and along a 90-m transect at two shore heights (high and low) in one intertidal site in France. The multilocus genotype of 799 fronds was determined (Nhaploid  = 586; Ndiploid  = 213) using eight microsatellite loci to test the following hypotheses: (i) high and low shore fronds belong to genetically differentiated populations, (ii) gene flow is restricted within the high shore habitat due to tidal-influenced isolation and (iii) significant FIS values are driven by life history characteristics. Pairwise FST estimates between high and low shore levels supported the hypothesis that high and low shore fronds were genetically differentiated. The high shore was characterized by the occurrence of within-shore genetic differentiation, reduced genetic diversity and increased levels of intergametophytic selfing, suggesting it is a marginal environment. These results suggest at fine scales within the intertidal seascape the same mechanisms as those over the species' distributional range are at work with core and marginal population dynamics.

  16. Response of benthic macrofauna to an oil pollution: Lessons from the “Prestige” oil spill on the rocky shore of Guéthary (south of the Bay of Biscay, France)

    NASA Astrophysics Data System (ADS)

    Castège, Iker; Milon, Emilie; Pautrizel, Françoise

    2014-08-01

    The benthic community on the rocky foreshore of Guéthary (France) has been monitored since 2002. The standardized and quantitative monitoring method counts 20 geographically referenced quadrats spread on three littoral zones: upper mediolittoral, lower mediolittoral and infralittoral zones. The setting up of this monitoring occurred when the “Prestige” sunk close to the Finistere Cape in Galicia (Spain). The oil slick following the shipwreck impacted the Guéthary foreshore in early 2003. After the “Prestige” oil spill, the taxonomic richness decreased in the studied area with a loss of 16 species - from 57 in 2002 (before the shipwreck) to 41 species in 2004. Two or 3 years later, taxonomic richness increased to a level observed prior to the oil spill. Along the years, temporal variations in community structure of benthic macrofauna are revealed by detailed analysis. Some polluo-sensitive species disappeared after 2002 and have not reappeared yet (e.g.: Hymeniacidon perlevis). Some others reappeared two or three years after the spill or even later (e.g.: Amphipholis squamata, Botryllus schlosseri, Calliostoma zizyphinum, Echinus esculentus, etc.). Noteworthy changes were found in 2004 driven by the sudden increase in abundance of grazers. The following years, these abundances went back to a stable level. The benthic community seemed to recover almost 5 years later, although a new composition of macrofauna populations was observed. In overall aspect, the complexity of the benthic ecosystem response to oil spills confirms the need of regularly updated baselines to assess the impact of pollutions and more generally to maintain marine biodiversity.

  17. Wave transformation on a sub-horizontal shore platform, Tatapouri, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Ogawa, H.; Dickson, M. E.; Kench, P. S.

    2011-09-01

    Waves are generally considered to be an important control on shore platform evolution but there have been very few detailed studies of wave dynamics on rocky coasts. This study provides a detailed description of wave transformation processes across a shore platform near Gisborne, New Zealand. A field experiment was conducted on an intertidal, 250 m-wide platform that is characterised by a sharp seaward edge. Mean platform elevation is 0.7 m below mean sea-level (MSL) and platform gradient is 0.3°. Four nearly equally spaced pressure gauges were deployed over a 24-h period during fair-weather swell conditions characterised by a mean wave height of 0.4-0.5 m and wave period of 7 s. Wave energy at the seaward edge of the platform was dominated by incident swell waves with peak frequency at 0.09 Hz. At all tidal stages waves broke at the seaward edge of the platform, but changing tidal stage exerted a strong control on the rate of wave energy attenuation across the platform. The relative importance of waves at wind-wave frequencies increased in the centre of the platform as the tidal stage and water level increased, whereas infragravity waves became dominant toward the cliff toe. Three different hydrodynamic zones were distinguished across the shore platform; (i) a breaker zone close to the seaward edge; (ii) a propagation/shoaling zone in the central region of the platform; and (iii) a zone of energy dissipation across the inner part of the platform. The spatial dimensions of the three zones varied with changing tidal stage, enabling different wave processes to operate across different parts of the platform at different times. The experiment showed that wave-height attenuation is strongly controlled by tidal stage, ranging between 93% attenuation of wave height during the initial flooding stage to 44% attenuation at high tide. Wave height was found to be depth-limited, with the ratios of Hmax and Hm0 to water depth calculated as 0.7 and 0.4, respectively. The

  18. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Yang, G.; Solli, E.; Dattels, C.; Wallace, K.; Boesel, A.; Steiger, C.; Buie, A.

    2010-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B) and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef ecosystem, in particular, the high intertidal zone which experiences the greatest amount of human impacts.

  19. From grazing marks to collapsed cliffs - intertidal bioerosion on all scales

    NASA Astrophysics Data System (ADS)

    Kázmér, Miklós; Taboroši, Danko; Hsieh, Meng-Long; Shafeea Leman, Mohd; Aziz Ali, Che; Roslan Mohamed, Kamal; Choowong, Montri

    2014-05-01

    Rocky shores - particularly in limestone areas of tropical, subtropical, and some temperate regions - are subject to intense bioerosion. Detailed field studies along the Gulf of Siam and the Andaman coast of Thailand, Langkawi Islands of Malaysia, southern Java and Bali in Indonesia, Palau Islands, and Okinawa revealed the presence of rich populations of bioeroding organisms in the intertidal zone. Molluscs capable of damaging rock (the chiton Acanthopleura, limpets, and whelks) leave grazing traces as they feed on bacterial and algal biofilms and chasmolithic and endolithic microorganisms. Boring sponges (Entobia), bivalves (Gastrochaenolites and others), boring sipunculid worms (Caulostrepsis), and sea urchins (Echinometra) drill deeper to hide from predators beneath the rock surface. Individually, members of these taxa leave marks ranging from sub-millimetre to the metre scale, but collectively, their erosion creates marine notches, several-metres-deep features extending between low and high tide marks. When cliffs overhanging these notches collapse, landscape-scale scars are left behind. The various bioeroders display a clear vertical zonation between low and high tide. These are dictated by environmental stress, food availability, competition, and predation. Typical inhabitants of present-day zones include - from top to bottom - littorinid snails, patellid limpets, chitons, boring bivalves, and boring sea urchins. Each organism leaves a characteristic mark in the bedrock. Trace fossils found in the 'wrong place' - either too high or too low compared to the present-day occurrence of the animals - suggest changes in relative sea level. Similarly, sea level changes are suggested by the presence of compound markings produced through overprinting by organisms that live in different ecological zones. Preservation and obliteration of traces depends on the rates of sea level change and coastal denudation. Morphology of bioerosional markings and their vertical zonation

  20. Intertidal oysters reach their physiological limit in a future high-CO2 world.

    PubMed

    Scanes, Elliot; Parker, Laura M; O'Connor, Wayne A; Stapp, Laura S; Ross, Pauline M

    2017-03-01

    Sessile marine molluscs living in the intertidal zone experience periods of internal acidosis when exposed to air (emersion) during low tide. Relative to other marine organisms, molluscs have been identified as vulnerable to future ocean acidification; however, paradoxically it has also been shown that molluscs exposed to high CO2 environments are more resilient compared with those molluscs naive to CO2 exposure. Two competing hypotheses were tested using a novel experimental design incorporating tidal simulations to predict the future intertidal limit of oysters in a high-CO2 world; either high-shore oysters will be more tolerant of elevated PCO2 because of their regular acidosis, or elevated PCO2  will cause high-shore oysters to reach their limit. Sydney rock oysters, Saccostrea glomerata, were collected from the high-intertidal and subtidal areas of the shore and exposed in an orthogonal design to either an intertidal or a subtidal treatment at ambient or elevated PCO2 , and physiological variables were measured. The combined treatment of tidal emersion and elevated PCO2  interacted synergistically to reduce the haemolymph pH (pHe) of oysters, and increase the PCO2  in the haemolymph (Pe,CO2 ) and standard metabolic rate. Oysters in the intertidal treatment also had lower condition and growth. Oysters showed a high degree of plasticity, and little evidence was found that intertidal oysters were more resilient than subtidal oysters. It is concluded that in a high-CO2 world the upper vertical limit of oyster distribution on the shore may be reduced. These results suggest that previous studies on intertidal organisms that lacked tidal simulations may have underestimated the effects of elevated PCO2.

  1. Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota.

    PubMed

    Jaramillo, Eduardo; Melnick, Daniel; Baez, Juan Carlos; Montecino, Henry; Lagos, Nelson A; Acuña, Emilio; Manzano, Mario; Camus, Patricio A

    2017-01-01

    The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30'S) to between 30 and 50 cm at Pisagua (19°30'S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50'S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species-dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre-instrumental earthquakes.

  2. Cool barnacles: Do common biogenic structures enhance or retard rates of deterioration of intertidal rocks and concrete?

    PubMed

    Coombes, Martin A; Viles, Heather A; Naylor, Larissa A; La Marca, Emanuela Claudia

    2017-02-15

    Sedentary and mobile organisms grow profusely on hard substrates within the coastal zone and contribute to the deterioration of coastal engineering structures and the geomorphic evolution of rocky shores by both enhancing and retarding weathering and erosion. There is a lack of quantitative evidence for the direction and magnitude of these effects. This study assesses the influence of globally-abundant intertidal organisms, barnacles, by measuring the response of limestone, granite and marine-grade concrete colonised with varying percentage covers of Chthamalus spp. under simulated, temperate intertidal conditions. Temperature regimes at 5 and 10mm below the surface of each material demonstrated a consistent and statistically significant negative relationship between barnacle abundance and indicators of thermal breakdown. With a 95% cover of barnacles, subsurface peak temperatures were reduced by 1.59°C for limestone, 5.54°C for concrete and 5.97°C for granite in comparison to no barnacle cover. The amplitudes of short-term (15-30min) thermal fluctuations conducive to breakdown via 'fatigue' effects were also buffered by 0.70°C in limestone, 1.50°C in concrete and 1.63°C in granite. Furthermore, concentrations of potentially damaging salt ions were consistently lower under barnacles in limestone and concrete. These results indicate that barnacles do not enhance, but likely reduce rates of mechanical breakdown on rock and concrete by buffering near-surface thermal cycling and reducing salt ion ingress. In these ways, we highlight the potential role of barnacles as agents of bioprotection. These findings support growing international efforts to enhance the ecological value of hard coastal structures by facilitating their colonisation (where appropriate) through design interventions.

  3. Biogeochemistry of Intertidal Sediments

    NASA Astrophysics Data System (ADS)

    Jickells, T. D.; Rae, J. E.

    2005-07-01

    This authoritative volume includes contributions from a wide range of researchers of intertidal sediments. Individual chapters explore the underlying biogeochemical processes controlling the behavior of carbon, the nutrients nitrogen and phosphorus, and contaminants such as toxic organics, trace metals and artificial radionuclides in intertidal environments. The biogeochemistry of these environments is critical to understanding their ecology and management. Each of the chapters includes a comprehensive review and the results of recent research. The contributors are active researchers in this diverse and ecologically important field. This text is mainly for researchers and managers working with intertidal sediments, but it will also serve as a valuable senior undergraduate and graduate reference text in environmental chemistry, environmental science, earth science, and oceanography.

  4. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Rainsford, A.; Soave, K.; Gerraty, F.; Jung, G.; Quirke-Shattuck, M.; Kudler, J.; Hatfield, J.; Emunah, M.; Dean, A. F.

    2014-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Each fall student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within two permanent 200 m2 areas, in fall, winter, and late spring. Using data from the previous years, we will compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis, Anthopluera elegantissima, Cladophora sp. and Fucus sp.. Future analyses and investigations will include intertidal abiotic factors (including water temperature, pH and human foot-traffic) to enhance insights into the Duxbury Reef ecosystem, in particular, the high and mid-intertidal zones experiencing the greatest amount of human impacts.

  5. A history of intertidal flat area in south San Francisco Bay, California: 1858 to 2005

    USGS Publications Warehouse

    Jaffe, Bruce; Foxgrover, Amy

    2006-01-01

    A key question in salt pond restoration in South San Francisco Bay is whether sediment sinks created by opening ponds will result in the loss of intertidal flats. Analyses of a series of bathymetric surveys of South San Francisco Bay made from 1858 to 2005 reveal changes in intertidal flat area in both space and time that can be used to better understand the pre-restoration system. This analysis also documents baseline conditions of intertidal flats that may be altered by restoration efforts. From 1858 to 2005, intertidal flat area decreased by about 25% from 69.2 +6.4/-7.6 km2 to 51.2 +4.8/-5.8 km2. Intertidal flats in the north tended to decrease in area during the period of this study whereas those south of Dumbarton Bridge were either stable or increased in area. From 1983 to 2005, intertidal flats south of Dumbarton Bridge increased from 17.6 +1.7/-2.5 km2 to 24.2 +1.0/-1.8 km2. Intertidal flats along the east shore of the bay tended to be more erosional and decreased in area while those along the west shore of the bay did not significantly change in area. Loss of intertidal flats occurred intermittently along the eastern shore of the bay north of the Dumbarton Bridge. There was little or no loss from 1931 to 1956 and from 1983 to 2005. Predictions of future change in intertidal flat area that do not account for this spatial and temporal variability are not likely to be accurate. The causes of the spatial and temporal variability in intertidal flat area in South San Francisco Bay are not fully understood, but appear related to energy available to erode sediments, sediment redistribution from north to south in the bay, and sediment available to deposit on the flats. Improved understanding of sediment input to South San Francisco Bay, especially from Central Bay, how it is likely to change in the future, the redistribution of sediment within the bay, and ultimately its effect on intertidal flat area would aid in the management of restoration of South San

  6. Predation on barnacles of intertidal and subtidal mussel beds in the Wadden Sea

    NASA Astrophysics Data System (ADS)

    Buschbaum, Christian

    2002-04-01

    Balanids are the numerically dominant epibionts on mussel beds in the Wadden Sea. Near the island of Sylt (German Bight, North Sea), Semibalanus balanoides dominated intertidally and Balanus crenatus subtidally. Field experiments were conducted to test the effects of predation on the density of barnacle recruits. Subtidally, predator exclusion resulted in significantly increased abundances of B. crenatus, while predator exclusion had no significant effects on the density of S. balanoides intertidally. It is suggested that recruitment of B. crenatus to subtidal mussel beds is strongly affected by adult shore crabs ( Carcinus maenas) and juvenile starfish ( Asterias rubens), whereas recruits of S. balanoides in the intertidal zone are mainly influenced by grazing and bulldozing of the very abundant periwinkle Littorina littorea, which is rare subtidally. Thus, not only do the barnacle species differ between intertidal and subtidal mussel beds, but the biotic control factors do so as well.

  7. Intertidal population genetic dynamics at a microgeographic seascape scale.

    PubMed

    Hu, Zi-Min

    2013-06-01

    The intertidal community is among the most physically harsh niches on earth, with highly heterogeneous environmental and biological factors that impose strong habitat selection on population abundance, genetic connectivity and ecological adaptation of organisms in nature. However, most genetic studies to date have concentrated on the influence of basin-wide or regional marine environments (e.g. habitat discontinuities, oceanic currents and fronts, and geographic barriers) on spatiotemporal distribution and composition of intertidal invertebrates having planktonic stages or long-distance dispersal capability. Little is known about sessile marine organisms (e.g. seaweeds) in the context of topographic tidal gradients and reproductive traits at the microgeographic scale. In this issue of Molecular Ecology, Krueger-Hadfield et al. () implemented an elaborate sampling strategy with red seaweed (Chondrus crispus) from a 90-m transect stand near Roscoff and comprehensively detected genome-scale genetic differentiation and biases in ploidy level. This study not only revealed that tidal height resulted in genetic differentiation between high- and low-shore stands and restricted the genetic exchange within the high-shore habitat, but also demonstrated that intergametophytic nonrandom fertilization in C. crispus can cause significant deviation from Hardy-Weinberg equilibrium. Such new genetic insights highlight the importance of microgeographic genetic dynamics and life history characteristics for better understanding the evolutionary processes of speciation and diversification of intertidal marine organisms.

  8. Effects of tidal amplitude on intertidal resource availability and dispersal pressure in prehistoric human coastal populations: the Mediterranean Atlantic transition

    NASA Astrophysics Data System (ADS)

    Fa, Darren Andrew

    2008-11-01

    In this paper I argue that there is a growing body of evidence supporting an increasingly central position of coastal environments in human evolution and dispersals, rather than as merely peripheral habitats. Eustatic fluctuations during glacial cycles have meant that most prehistoric coastlines are now underwater, and lack of evidence to date of a close relationship between people and the coast can be most plausibly ascribed to the limited studies so far on submerged sites. Coastal environments provide high diversity in food resources, consisting of multiple ecotones in close proximity, which reduces the need to forage widely. One of the richest and most easily exploited coastal resources by human populations living on the coast are molluscs from marine rocky intertidal communities, which recent evidence has highlighted as important as far back as the Middle Palaeolithic. However, the density of these resources is limited by a number of factors, and this varies geographically. One of the main large-scale factors limiting rocky intertidal mollusc densities is tidal amplitude, beyond which smaller-scale local factors such as exposure to wave action and shore aspect, further affect species distributions. The area around the Strait of Gibraltar is used as a case study of an area, which is affected by large variations in tidal amplitudes thus allowing for quantitative comparisons between taxonomically and climatically similar regions. Shorelines along the Mediterranean coast, with reduced tidal amplitudes, exhibit compressed zonations and harbour fewer macro-mollusc individuals, with the reverse being the case along the Atlantic coast, which has significantly larger tides. Data from Middle and Upper Palaeolithic sites along the Strait are used to establish harvested species and present-day data are used to model the potential distributions and associated variables such as calorific returns of key food species. An optimal foraging model is used to explore the effects of

  9. The importance of predation and competition in organizing the intertidal epifaunal communities of Barnegat Inlet, New Jersey.

    PubMed

    Peterson, Charles H

    1979-01-01

    predation prevents monopolization of mid and low intertidal space by the apparent competitive dominant, Mytilus. Predation appears to be a direct cause of the relatively great temporal and spatial heterogeneity in the mid and low intertidal of these pilings.Thus, although the Barnegat Inlet intertidal system appears to follow closely the patterns of community organization described for several other rocky intertidal coastlines, this organizational pattern is noteworthy because it is repeated here in a far more seasonal environment and with a new cast of interacting competitors and predators. That crabs play an important role as predators is novel for North America, but only perhaps because all previous North American studies have ignored the rocky intertidal zones of quiet, estuarine waters where in Europe predatory crabs are known to be extremely significant.

  10. Rocky Mountain spotted fever

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/000654.htm Rocky Mountain spotted fever To use the sharing features on this page, please enable JavaScript. Rocky Mountain spotted fever is a disease caused by a ...

  11. Relationships between an invasive crab, habitat availability and intertidal community structure at biogeographic scales.

    PubMed

    Gribben, Paul E; Simpson, Michael; Wright, Jeffrey T

    2015-09-01

    At local scales, habitat availability influences interactions between native and invasive species. Habitat availability may also predict patterns in native communities and invasive species at biogeographic scales when both native and invasive species have specific habitat requirements. The New Zealand porcelain crab, Petrolisthes elongatus, has invaded intertidal rocky shores around Tasmania, Australia, where it is found in high densities (>1800 m(2)) under rocks. A hierarchical sampling approach was used to investigate 1) the relationship between habitat availability (rock cover) and the biomass and abundance of P. elongatus, and 2) the relationship between P. elongatus biomass and native communities at local and regional scales. Invertebrate communities and habitat availability were sampled at multiple sites in the north and south regions of Tasmania. P. elongatus biomass and abundance were positively correlated with rock cover and patterns were consistent at the biogeographic scale (between regions). P. elongatus biomass was positively correlated with native species richness, biomass and abundance highlighting their co-dependence on rock cover. However, multivariate analyses indicated a different native community structure with increasing P. elongatus biomass. Flat, strongly adhering gastropods (chitons and limpets) were positively correlated with P. elongatus biomass, whereas mobile gastropods and crabs were negatively correlated with P. elongatus biomass. Despite local scale variation, there were clear consistent relationships between habitat-availability and the biomass of P. elongatus, and between native communities and the biomass of P. elongatus suggesting that the relationships between native and invasive species may be predictable at large spatial scales. Moreover, the strong relationships between P. elongatus biomass and changes in native community structure suggest a greater understanding of its impact is needed so that appropriate

  12. Facing the Heat: Does Desiccation and Thermal Stress Explain Patterns of Orientation in an Intertidal Invertebrate?

    PubMed Central

    Fraser, Clarissa M. L.; Seebacher, Frank; Lathlean, Justin; Coleman, Ross A.

    2016-01-01

    A key challenge for ecologists is to quantify, explain and predict the ecology and behaviour of animals from knowledge of their basic physiology. Compared to our knowledge of many other types of distribution and behaviour, and how these are linked to individual function, we have a poor level of understanding of the causal basis for orientation behaviours. Most explanations for patterns of animal orientation assume that animals will modify their exposure to environmental factors by altering their orientation. We used a keystone grazer on rocky shores, the limpet Cellana tramoserica, to test this idea. Manipulative experiments were done to evaluate whether orientation during emersion affected limpet desiccation or body temperature. Body temperature was determined from infrared thermography, a technique that minimises disturbance to the test organism. No causal relationships were found between orientation and (i) level of desiccation and (ii) their body temperature. These results add to the growing knowledge that responses to desiccation and thermal stress may be less important in modifying the behaviour of intertidal organisms than previously supposed and that thermoregulation does not always reflect patterns of animal orientation. Much of what we understand about orientation comes from studies of animals able to modify orientation over very short time scales. Our data suggests that for animals whose location is less flexible, orientation decisions may have less to do with responses to environmental factors and more to do with structural habitat properties or intrinsic individual attributes. Therefore we suggest future studies into processes affecting orientation must include organisms with differing levels of behavioural plasticity. PMID:26959815

  13. Genetic structuring across marine biogeographic boundaries in rocky shore invertebrates.

    PubMed

    Villamor, Adriana; Costantini, Federica; Abbiati, Marco

    2014-01-01

    Biogeography investigates spatial patterns of species distribution. Discontinuities in species distribution are identified as boundaries between biogeographic areas. Do these boundaries affect genetic connectivity? To address this question, a multifactorial hierarchical sampling design, across three of the major marine biogeographic boundaries in the central Mediterranean Sea (Ligurian-Tyrrhenian, Tyrrhenian-Ionian and Ionian-Adriatic) was carried out. Mitochondrial COI sequence polymorphism of seven species of Mediterranean benthic invertebrates was analysed. Two species showed significant genetic structure across the Tyrrhenian-Ionian boundary, as well as two other species across the Ionian Sea, a previously unknown phylogeographic barrier. The hypothesized barrier in the Ligurian-Tyrrhenian cannot be detected in the genetic structure of the investigated species. Connectivity patterns across species at distances up to 800 km apart confirmed that estimates of pelagic larval dispersal were poor predictors of the genetic structure. The detected genetic discontinuities seem more related to the effect of past historical events, though maintained by present day oceanographic processes. Multivariate statistical tools were used to test the consistency of the patterns across species, providing a conceptual framework for across-species barrier locations and strengths. Additional sequences retrieved from public databases supported our findings. Heterogeneity of phylogeographic patterns shown by the 7 investigated species is relevant to the understanding of the genetic diversity, and carry implications for conservation biology.

  14. Genetic Structuring across Marine Biogeographic Boundaries in Rocky Shore Invertebrates

    PubMed Central

    Villamor, Adriana; Costantini, Federica; Abbiati, Marco

    2014-01-01

    Biogeography investigates spatial patterns of species distribution. Discontinuities in species distribution are identified as boundaries between biogeographic areas. Do these boundaries affect genetic connectivity? To address this question, a multifactorial hierarchical sampling design, across three of the major marine biogeographic boundaries in the central Mediterranean Sea (Ligurian-Tyrrhenian, Tyrrhenian-Ionian and Ionian-Adriatic) was carried out. Mitochondrial COI sequence polymorphism of seven species of Mediterranean benthic invertebrates was analysed. Two species showed significant genetic structure across the Tyrrhenian-Ionian boundary, as well as two other species across the Ionian Sea, a previously unknown phylogeographic barrier. The hypothesized barrier in the Ligurian-Tyrrhenian cannot be detected in the genetic structure of the investigated species. Connectivity patterns across species at distances up to 800 km apart confirmed that estimates of pelagic larval dispersal were poor predictors of the genetic structure. The detected genetic discontinuities seem more related to the effect of past historical events, though maintained by present day oceanographic processes. Multivariate statistical tools were used to test the consistency of the patterns across species, providing a conceptual framework for across-species barrier locations and strengths. Additional sequences retrieved from public databases supported our findings. Heterogeneity of phylogeographic patterns shown by the 7 investigated species is relevant to the understanding of the genetic diversity, and carry implications for conservation biology. PMID:24983738

  15. Coastal Upwelling Drives Intertidal Assemblage Structure and Trophic Ecology

    PubMed Central

    Reddin, Carl J.; Docmac, Felipe; O’Connor, Nessa E.; Bothwell, John H.; Harrod, Chris

    2015-01-01

    Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecology across eighteen shores varying in their proximity to two coastal upwelling centres, in a hierarchical sampling design (spatial scales of >1 and >10 km). The influence of coastal upwelling on intertidal communities was confirmed by the stable isotope values (δ13C and δ15N) of consumers, including a dominant suspension feeder, grazers, and their putative resources of POM, epilithic biofilm, and macroalgae. We highlight the utility of muscle δ15N from the suspension feeding mussel, Perumytilus purpuratus, as a proxy for upwelling, supported by satellite data and previous studies. Where possible, we used corrections for broader-scale trends, spatial autocorrelation, ontogenetic dietary shifts and spatial baseline isotopic variation prior to analysis. Our results showed macroalgal assemblage composition, and benthic consumer assemblage structure, varied significantly with the intertidal influence of coastal upwelling, especially contrasting bays and coastal headlands. Coastal topography also separated differences in consumer resource use. This suggested that coastal upwelling, itself driven by coastline topography, influences intertidal communities by advecting nearshore phytoplankton populations offshore and cooling coastal water temperatures. We recommend the isotopic values of benthic organisms, specifically long-lived suspension feeders, as in situ alternatives to offshore measurements of upwelling influence. PMID:26214806

  16. Coastal Upwelling Drives Intertidal Assemblage Structure and Trophic Ecology.

    PubMed

    Reddin, Carl J; Docmac, Felipe; O'Connor, Nessa E; Bothwell, John H; Harrod, Chris

    2015-01-01

    Similar environmental driving forces can produce similarity among geographically distant ecosystems. Coastal oceanic upwelling, for example, has been associated with elevated biomass and abundance patterns of certain functional groups, e.g., corticated macroalgae. In the upwelling system of Northern Chile, we examined measures of intertidal macrobenthic composition, structure and trophic ecology across eighteen shores varying in their proximity to two coastal upwelling centres, in a hierarchical sampling design (spatial scales of >1 and >10 km). The influence of coastal upwelling on intertidal communities was confirmed by the stable isotope values (δ13C and δ15N) of consumers, including a dominant suspension feeder, grazers, and their putative resources of POM, epilithic biofilm, and macroalgae. We highlight the utility of muscle δ15N from the suspension feeding mussel, Perumytilus purpuratus, as a proxy for upwelling, supported by satellite data and previous studies. Where possible, we used corrections for broader-scale trends, spatial autocorrelation, ontogenetic dietary shifts and spatial baseline isotopic variation prior to analysis. Our results showed macroalgal assemblage composition, and benthic consumer assemblage structure, varied significantly with the intertidal influence of coastal upwelling, especially contrasting bays and coastal headlands. Coastal topography also separated differences in consumer resource use. This suggested that coastal upwelling, itself driven by coastline topography, influences intertidal communities by advecting nearshore phytoplankton populations offshore and cooling coastal water temperatures. We recommend the isotopic values of benthic organisms, specifically long-lived suspension feeders, as in situ alternatives to offshore measurements of upwelling influence.

  17. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Weigel, S.; Redman, K.; Darakananda, D.; Fuller, C.; Gusman, V.; Hirschfeld, Z.; Kornfeld, H.; Picchi, K.

    2006-12-01

    The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal ecology, interpretation and monitoring techniques, and history of the sanctuary. Students conduct two baseline-monitoring surveys three times per year (fall, winter, and late spring) to identify and count key invertebrate and algae species. During six seasons of monitoring (2000-2006), the density of black turban snails, Tegula funebralis, showed seasonal abundance variation with respect to tidal zonation. Most algae species had consistently lower densities in the more accessible northern (A) transects than the southern (B) transects. To test the reliability of the student counts, replicate counts of all species are always performed. Replicate counts for invertebrate and algae species within the same quadrat along the permanent transects revealed a very small amount of variability, giving us confidence that our monitoring program is providing reliable data.

  18. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA (Invited)

    NASA Astrophysics Data System (ADS)

    Soave, K.; Dean, A.; Darakananda, K.; Ball, O.; Butti, C.; Yang, G.; Vetter, M.; Grimaldi, Z.

    2009-12-01

    Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA Kathy Soave, Amy Dean, Olivia Ball, Karin Darakananda, Matt Vetter, Grant Yang, Charlotte Butti, Zoe Grimaldi The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of the project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects (A and B) and using randomly determined points within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will analyze the population densities, seasonal abundance and long-term population trends of key algal and invertebrate species. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef ecosystem, in particular, the high intertidal zone which experiences the greatest amount of human

  19. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Buie, A.; Soave, K.; Dean, A.; Salmi, I.; Tillapaugh, J.; Broad, C.; Raabe, B.; Ericson, W.

    2012-12-01

    Kathy Soave, Amy Dean, Andrew Buie, Isabella Salmi, Joey Tillapaugh, Cory Broad, Brooke Raabe, Whitney Ericson The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within two permanent 100 m2 areas, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will once again compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis, Anthopluera elegantissima and Fucus spp.. We will continue to closely monitor algal population densities in within our site in light of the November 2007 San Francisco Bay oil spill that leaked heavy bunker fuel into intertidal habitats around the SF Bay. Future analyses and investigations will include intertidal abiotic

  20. Standing infragravity waves over an alongshore irregular rocky bathymetry

    NASA Astrophysics Data System (ADS)

    Winter, G.; Lowe, R. J.; Symonds, G.; Hansen, J. E.; van Dongeren, A. R.

    2017-06-01

    Rocky reef coastlines typically feature highly variable and often abrupt cross-shore and alongshore changes in bathymetry. The effects of this irregular rocky bathymetry on the dynamics of infragravity waves are largely unknown. Most models of infragravity wave dynamics have been developed and validated on smooth alongshore-uniform bathymetries, which may break down over these highly variable bathymetries. A 2 week field experiment was conducted on a rocky reef-fringed beach to investigate how the variable bathymetry affects the spatial and temporal variability of infragravity waves. The height of short (sea-swell) waves decreased over the shallow reef due to breaking, whereas the height of infragravity waves increased toward the shoreline. Both during a storm event (Hm0 = 2.3 m) and under moderate wave conditions (Hm0 = 1.0-1.8 m), the infragravity waves formed a persistent cross-shore standing wave pattern along the entire shoreline, despite the irregular bathymetry. In addition, the alongshore components of infragravity waves refracted by the presence of the nearshore reef were observed to propagate in opposite directions up and down the coast resulting in a local alongshore standing wave pattern. Thus, the presence of highly variable nearshore bathymetry, which commonly occurs along rocky reef coastlines, may produce both cross-shore and alongshore standing wave patterns.

  1. Does differential particulate food supply explain the presence of mussels in Wellington Harbour (New Zealand) and their absence on neighbouring Cook Strait shores?

    NASA Astrophysics Data System (ADS)

    Helson, Jeremy G.; Pledger, Shirley; Gardner, Jonathan P. A.

    2007-03-01

    Rocky intertidal reef communities in Wellington Harbour, New Zealand, are dominated by mussels (the ribbed mussel Aulacomya maoriana, the blue mussel Mytilus galloprovincialis, and the greenshell mussel Perna canaliculus). Only a few kilometres away, outside the Harbour on exposed Cook Strait shores, these mussels are absent. We tested the hypothesis of bottom-up food limitation as the explanation for this distributional difference. The water column at three Harbour sites and five Cook Strait coastal sites was sampled over an 18-month period for temperature, salinity, dissolved oxygen, total particulate matter (TPM), particulate organic matter (POM), percent organic matter (PCOM), chlorophyll a (Chl a), particle counts (number of particles mL -1 in the range 2.5-63 μm), percent carbon, percent nitrogen, and C:N ratio. Mean values of PCOM and Chl a were significantly higher ( p < 0.05) in the Harbour than in Cook Strait. On two separate occasions mussels were transferred from Wellington Harbour to the Island Bay Marine Laboratory (IBML on Cook Strait) and sampled at regular intervals to permit the determination of body condition index (CI) and mortality rate to measure their response to the coastal seston regime. On both occasions monthly CI values of all three species held at IBML decreased significantly when compared with monthly CI values of mussels collected from Harbour sites. Mortality rates at IBML exhibited consistent taxon-specific responses ( P. canaliculus > M. galloprovincialis > A. maoriana). We interpret these field-based and laboratory-based findings as providing support for the hypothesis that multi-species mussel distributions and hence intertidal community structure at Cook Strait sites are regulated at least in part by particulate food supply.

  2. Between tide and wave marks: a unifying model of physical zonation on littoral shores.

    PubMed

    Bird, Christopher E; Franklin, Erik C; Smith, Celia M; Toonen, Robert J

    2013-01-01

    The effects of tides on littoral marine habitats are so ubiquitous that shorelines are commonly described as 'intertidal', whereas waves are considered a secondary factor that simply modifies the intertidal habitat. However mean significant wave height exceeds tidal range at many locations worldwide. Here we construct a simple sinusoidal model of coastal water level based on both tidal range and wave height. From the patterns of emergence and submergence predicted by the model, we derive four vertical shoreline benchmarks which bracket up to three novel, spatially distinct, and physically defined zones. The (1) emergent tidal zone is characterized by tidally driven emergence in air; the (2) wave zone is characterized by constant (not periodic) wave wash; and the (3) submergent tidal zone is characterized by tidally driven submergence. The decoupling of tidally driven emergence and submergence made possible by wave action is a critical prediction of the model. On wave-dominated shores (wave height ≫ tidal range), all three zones are predicted to exist separately, but on tide-dominated shores (tidal range ≫ wave height) the wave zone is absent and the emergent and submergent tidal zones overlap substantially, forming the traditional "intertidal zone". We conclude by incorporating time and space in the model to illustrate variability in the physical conditions and zonation on littoral shores. The wave:tide physical zonation model is a unifying framework that can facilitate our understanding of physical conditions on littoral shores whether tropical or temperate, marine or lentic.

  3. Glacial and Intertidal Ecology: A Study Guide for the Third Grade. Alaska Sea Week Curriculum Series. Draft.

    ERIC Educational Resources Information Center

    Hopson, Dan; And Others

    Two marine science units comprise this manual for teachers of elementary school students. Unit 1, "Shore Communities," involves mapping exercises and other investigations of the ecology of the intertidal zone. Unit 2, "The Glacier," focuses on glacial geology and the relationship of glaciers to the marine environment. Each unit…

  4. Bounty of intertidal zones

    SciTech Connect

    Not Available

    1987-04-01

    A surf-pounded shore might seem an inhospitable place, but it may actually be biologically more productive than a tropical forest. Energy carried in the waves far exceeds that delivered by the sun, and seems to account for the thriving marine communities found along some shores. The most productive (in dry weight) kelp and mussel communities, receive the most wave power. Even though the organisms cannot absorb or otherwise directly use the energy, the waves apparently serve to wash away sea urchins and other predators as well as competing organisms. They also keep fresh nutrient-laden water flowing around the kelp and allow more-efficient use of sunlight by marine plants.

  5. Climate Change and Intertidal Wetlands

    PubMed Central

    Ross, Pauline M.; Adam, Paul

    2013-01-01

    Intertidal wetlands are recognised for the provision of a range of valued ecosystem services. The two major categories of intertidal wetlands discussed in this contribution are saltmarshes and mangrove forests. Intertidal wetlands are under threat from a range of anthropogenic causes, some site-specific, others acting globally. Globally acting factors include climate change and its driving cause—the increasing atmospheric concentrations of greenhouse gases. One direct consequence of climate change will be global sea level rise due to thermal expansion of the oceans, and, in the longer term, the melting of ice caps and glaciers. The relative sea level rise experienced at any one locality will be affected by a range of factors, as will the response of intertidal wetlands to the change in sea level. If relative sea level is rising and sedimentation within intertidal wetlands does not keep pace, then there will be loss of intertidal wetlands from the seaward edge, with survival of the ecosystems only possible if they can retreat inland. When retreat is not possible, the wetland area will decline in response to the “squeeze” experienced. Any changes to intertidal wetland vegetation, as a consequence of climate change, will have flow on effects to biota, while changes to biota will affect intertidal vegetation. Wetland biota may respond to climate change by shifting in distribution and abundance landward, evolving or becoming extinct. In addition, impacts from ocean acidification and warming are predicted to affect the fertilisation, larval development, growth and survival of intertidal wetland biota including macroinvertebrates, such as molluscs and crabs, and vertebrates such as fish and potentially birds. The capacity of organisms to move and adapt will depend on their life history characteristics, phenotypic plasticity, genetic variability, inheritability of adaptive characteristics, and the predicted rates of environmental change. PMID:24832670

  6. Climate change and intertidal wetlands.

    PubMed

    Ross, Pauline M; Adam, Paul

    2013-03-19

    Intertidal wetlands are recognised for the provision of a range of valued ecosystem services. The two major categories of intertidal wetlands discussed in this contribution are saltmarshes and mangrove forests. Intertidal wetlands are under threat from a range of anthropogenic causes, some site-specific, others acting globally. Globally acting factors include climate change and its driving cause-the increasing atmospheric concentrations of greenhouse gases. One direct consequence of climate change will be global sea level rise due to thermal expansion of the oceans, and, in the longer term, the melting of ice caps and glaciers. The relative sea level rise experienced at any one locality will be affected by a range of factors, as will the response of intertidal wetlands to the change in sea level. If relative sea level is rising and sedimentation within intertidal wetlands does not keep pace, then there will be loss of intertidal wetlands from the seaward edge, with survival of the ecosystems only possible if they can retreat inland. When retreat is not possible, the wetland area will decline in response to the "squeeze" experienced. Any changes to intertidal wetland vegetation, as a consequence of climate change, will have flow on effects to biota, while changes to biota will affect intertidal vegetation. Wetland biota may respond to climate change by shifting in distribution and abundance landward, evolving or becoming extinct. In addition, impacts from ocean acidification and warming are predicted to affect the fertilisation, larval development, growth and survival of intertidal wetland biota including macroinvertebrates, such as molluscs and crabs, and vertebrates such as fish and potentially birds. The capacity of organisms to move and adapt will depend on their life history characteristics, phenotypic plasticity, genetic variability, inheritability of adaptive characteristics, and the predicted rates of environmental change.

  7. Markov chain analysis of succession in a rocky subtidal community.

    PubMed

    Hill, M Forrest; Witman, Jon D; Caswell, Hal

    2004-08-01

    We present a Markov chain model of succession in a rocky subtidal community based on a long-term (1986-1994) study of subtidal invertebrates (14 species) at Ammen Rock Pinnacle in the Gulf of Maine. The model describes successional processes (disturbance, colonization, species persistence, and replacement), the equilibrium (stationary) community, and the rate of convergence. We described successional dynamics by species turnover rates, recurrence times, and the entropy of the transition matrix. We used perturbation analysis to quantify the response of diversity to successional rates and species removals. The equilibrium community was dominated by an encrusting sponge (Hymedesmia) and a bryozoan (Crisia eburnea). The equilibrium structure explained 98% of the variance in observed species frequencies. Dominant species have low probabilities of disturbance and high rates of colonization and persistence. On average, species turn over every 3.4 years. Recurrence times varied among species (7-268 years); rare species had the longest recurrence times. The community converged to equilibrium quickly (9.5 years), as measured by Dobrushin's coefficient of ergodicity. The largest changes in evenness would result from removal of the dominant sponge Hymedesmia. Subdominant species appear to increase evenness by slowing the dominance of Hymedesmia. Comparison of the subtidal community with intertidal and coral reef communities revealed that disturbance rates are an order of magnitude higher in coral reef than in rocky intertidal and subtidal communities. Colonization rates and turnover times, however, are lowest and longest in coral reefs, highest and shortest in intertidal communities, and intermediate in subtidal communities.

  8. Mortality, behavior and the effects of predators on the intertidal distribution of littorinid gastropods.

    PubMed

    Rochette; Dill

    2000-10-25

    Predators can affect the vertical distribution of mobile intertidal invertebrates in two ways: they can (1) cause greater mortality of prey at certain intertidal levels, and (2) induce prey to seek safer intertidal areas. In this study, we investigate whether low-intertidal and subtidal predators affect the intertidal distribution of two congeneric species of small herbivorous gastropods of northeastern Pacific shores, Littorina sitkana Philippi 1846, and L. scutulata Gould 1849. In particular, we tested the hypothesis that predators affect the distribution of these snails by inducing them to seek higher and safer intertidal areas. On a wave-sheltered shore in Barkley Sound, British Columbia, L. sitkana and L. scutulata were both killed by predatory crabs (e.g., Cancer productus) more frequently when tethered near the lower limit of their intertidal distribution ( approximately 1 m) than when tethered where they were most common ( approximately 2.5 m), suggesting that high mortality rates are partly responsible for the lower-limit of these snails' intertidal distribution. However, two field mark-recapture experiments indicated that the snails' behavioral response to predation risk also influences their distribution. In the first experiment, snails from the 2.5-m level (low risk) transplanted to the 1.0-m level (high risk) displayed a strong and consistent tendency to move shoreward, especially L. sitkana, some traveling 10-15 m in 2-3 days to regain their original level. These shoreward movements were especially precise in the northern part of the study area, where predation rates on tethered snails were greatest. Furthermore, larger more vulnerable snails were more strongly oriented shoreward than smaller individuals, indicating that antipredator behavior might also contribute to intertidal size gradients in these species. In the second mark-recapture experiment, we manipulated predation risk using small cages and found that snails exposed to the odors of C

  9. Differential recolonization of Atlantic intertidal habitats after disturbance reveals potential bottom-up community regulation

    PubMed Central

    Petzold, Willy; Scrosati, Ricardo A.

    2014-01-01

    In the spring of 2014, abundant sea ice that drifted out of the Gulf of St. Lawrence caused extensive disturbance in rocky intertidal habitats on the northern Atlantic coast of mainland Nova Scotia, Canada. To monitor recovery of intertidal communities, we surveyed two wave-exposed locations in the early summer of 2014. Barnacle recruitment and the abundance of predatory dogwhelks were low at one location (Tor Bay Provincial Park) but more than 20 times higher at the other location (Whitehead). Satellite data indicated that the abundance of coastal phytoplankton (the main food source for barnacle larvae) was consistently higher at Whitehead just before the barnacle recruitment season, when barnacle larvae were in the water column. These observations suggest bottom-up forcing of intertidal communities. The underlying mechanisms and their intensity along the NW Atlantic coast could be investigated through studies done at local and regional scales. PMID:26213609

  10. Pyropia plicata sp. nov. (Bangiales, Rhodophyta): naming a common intertidal alga from New Zealand

    PubMed Central

    Nelson, Wendy A.

    2013-01-01

    Abstract A commonly found red alga of the upper intertidal zone of New Zealand rocky coasts is described for the first time as Pyropia plicata sp. nov. This species has been incorrectly known as Porphyra columbina Mont. (now Pyropia columbina (Mont.) W.A.Nelson) for many years. Pyropia plicata is widespread and common, and it is readily distinguished from other species of bladed Bangiales in New Zealand by its distinctive morphology, with pleated blades attached by a central rhizoidal holdfast. PMID:23794933

  11. Pyropia plicata sp. nov. (Bangiales, Rhodophyta): naming a common intertidal alga from New Zealand.

    PubMed

    Nelson, Wendy A

    2013-01-01

    A commonly found red alga of the upper intertidal zone of New Zealand rocky coasts is described for the first time as Pyropia plicata sp. nov. This species has been incorrectly known as Porphyra columbina Mont. (now Pyropia columbina (Mont.) W.A.Nelson) for many years. Pyropia plicata is widespread and common, and it is readily distinguished from other species of bladed Bangiales in New Zealand by its distinctive morphology, with pleated blades attached by a central rhizoidal holdfast.

  12. Sustainable Seas Student Intertidal Monitoring Project at Duxbury Reef in Bolinas, CA

    NASA Astrophysics Data System (ADS)

    Boesel, A.; Soave, K.; Dean, A.; Grimaldi, Z.; Buie, A.; Dattels, C.; Steiger, C.; Wallace, K.; Salmi, I.; Tillapaugh, J.

    2011-12-01

    Kathy Soave, Amy Dean, Alexa Boesel, Andrew Buie, Celia Dattels, Zoe Grimaldi, Isabella Salmi, Cameryn Steiger, Joey Tillapaugh, Kathleen Wallace The Sustainable Seas Student Monitoring Project at the Branson School in Ross, CA has monitored Duxbury Reef in Bolinas, CA since 1999, in cooperation with the Farallones Marine Sanctuary Association and the Gulf of Farallones National Marine Sanctuary. Goals of this student-run project include: 1) To monitor the rocky intertidal habitat and develop a baseline database of invertebrates and algal density and abundance; 2) To contribute to the conservation of the rocky intertidal habitat through education of students and visitors about intertidal species and the requirements for maintaining a healthy, diverse intertidal ecosystem; 3) To increase stewardship in the Gulf of the Farallones National Marine Sanctuary; and 4) To contribute abundance and population data on key algae and invertebrate species to the national database, LiMPETS (Long Term Monitoring Program & Experiential Training for Students). Student volunteers complete an intensive training course on the natural history of intertidal invertebrates and algae, identification of key species, rocky intertidal monitoring techniques, and history of the sanctuary. Students identify and count key invertebrate and algae species along two permanent transects and, using randomly determined points, within a permanent 100 m2 area, three times per year (fall, winter, and late spring). Using the data collected since 2004, we will once again compare population densities, seasonal abundance and long-term population trends of key algal and invertebrate species, including Tegula funebralis and Anthopluera elegantissima. Future analyses and investigations will include intertidal abiotic factors (including water temperature and human foot-traffic) to enhance insights into the workings of the Duxbury Reef ecosystem, in particular, the high and mid-intertidal zones experiencing the

  13. An Examination of Intertidal Temperatures Through Remotely Sensed Satellite Observations

    NASA Astrophysics Data System (ADS)

    Lakshmi, V.

    2010-12-01

    MODIS Aqua and Terra satellites produce both land surface temperatures and sea surface temperatures using calibrated algorithms. In this study, the land surface temperatures were retrieved during clear-sky (non-cloudy) conditions at a 1 km2 resolution (overpass time at 10:30 am) whereas the sea surface temperatures are also retrieved during clear-sky conditions at approximately 4 km resolution (overpass time at 1:30 pm). The purpose of this research was to examine remotely sensed sea surface (SST), intertidal (IST), and land surface temperatures (LST), in conjunction with observed in situ mussel body temperatures, as well as associated weather and tidal data. In Strawberry Hill, Oregon, it was determined that intertidal surface temperatures are similar to but distinctly different from land surface temperatures although influenced by sea surface temperatures. The air temperature and differential heating throughout the day, as well as location in relation to the shore, can greatly influence the remotely sensed surface temperatures. Therefore, remotely sensed satellite data is a very useful tool in examining intertidal temperatures for regional climatic changes over long time periods and may eventually help researchers forecast expected climate changes and help determine associated biological implications.

  14. Hyperspectral derivatives analysis for intertidal habitat mapping

    NASA Astrophysics Data System (ADS)

    Oppelt, N.; Schulze, F.; Bartsch, I.

    2012-09-01

    Analysis of coastal marine algae communities enables an estimation of the state of coastal marine environments and provides evidence for environmental changes. Hyperspectral remote sensing provides a tool for mapping macroalgal habitats if the algal communities are spectrally resolvable. We tested the performance of a new approach for determining the distribution of macroalgae communities in the rocky intertidal zone of Helgoland (Germany) using airborne hyperspectral (AISAeagle) data. This new approach calculates the slopes in wavelength regions between specific pigment absorption features and does not rely on absolute reflectance values. The first order derivatives of these wavelength regions form slope bands, which are then classified using a k-Means approach. The new derivatives approach proved to be a time effective possibility for identifying the dominating macroalgae species with sufficient accuracy (Cohan's kappa = 0.70). The method was tested on another AISA data set and turned out to be as a robust (Cohan's kappa = 0.77) and easy-to-use approach for delineating dominant algae communities or habitats, which can be adapted easily to different data sets.

  15. Diurnal changes of photosynthetic quantum yield in the intertidal macroalga Sargassum thunbergii under simulated tidal emersion conditions

    NASA Astrophysics Data System (ADS)

    Yu, Yong Qiang; Zhang, Quan Sheng; Tang, Yong Zheng; Li, Xue Meng; Liu, Hong Liang; Li, Li Xia

    2013-07-01

    results may explain the distribution pattern of this species in natural habitats, where it is generally restricted to tide pools in the intertidal zone of wave-swept rocky shores which could provide shelter from desiccation stress during low tide.

  16. Calibrating coseismic coastal land-level changes during the 2014 Iquique (Mw=8.2) earthquake (northern Chile) with leveling, GPS and intertidal biota

    PubMed Central

    Melnick, Daniel; Baez, Juan Carlos; Montecino, Henry; Lagos, Nelson A.; Acuña, Emilio; Manzano, Mario; Camus, Patricio A.

    2017-01-01

    The April 1st 2014 Iquique earthquake (MW 8.1) occurred along the northern Chile margin where the Nazca plate is subducted below the South American continent. The last great megathrust earthquake here, in 1877 of Mw ~8.8 opened a seismic gap, which was only partly closed by the 2014 earthquake. Prior to the earthquake in 2013, and shortly after it we compared data from leveled benchmarks, deployed campaign GPS instruments, continuous GPS stations and estimated sea levels using the upper vertical level of rocky shore benthic organisms including algae, barnacles, and mussels. Land-level changes estimated from mean elevations of benchmarks indicate subsidence along a ~100-km stretch of coast, ranging from 3 to 9 cm at Corazones (18°30’S) to between 30 and 50 cm at Pisagua (19°30’S). About 15 cm of uplift was measured along the southern part of the rupture at Chanabaya (20°50’S). Land-level changes obtained from benchmarks and campaign GPS were similar at most sites (mean difference 3.7±3.2 cm). Higher differences however, were found between benchmarks and continuous GPS (mean difference 8.5±3.6 cm), possibly because sites were not collocated and separated by several kilometers. Subsidence estimated from the upper limits of intertidal fauna at Pisagua ranged between 40 to 60 cm, in general agreement with benchmarks and GPS. At Chanavaya, the magnitude and sense of displacement of the upper marine limit was variable across species, possibly due to species—dependent differences in ecology. Among the studied species, measurements on lithothamnioid calcareous algae most closely matched those made with benchmarks and GPS. When properly calibrated, rocky shore benthic species may be used to accurately measure land-level changes along coasts affected by subduction earthquakes. Our calibration of those methods will improve their accuracy when applied to coasts lacking pre-earthquake data and in estimating deformation during pre–instrumental earthquakes. PMID

  17. Mutagenic assessment of Prestige fuel oil spilled on the shore and submitted to field trials of bioremediation.

    PubMed

    Sueiro, Rosa Ana; Garrido, Manuel Joaquín; Araujo, Manuel

    2011-11-01

    The mutagenicy of the slightly weathered fuel oil from the Prestige oil spill and the effects of different bioremediation products (nutrients and/or microorganisms and biodiesel) on the potential mutagenic activity of this heavy fuel oil spilled on the shore were evaluated for a period of 1 year using the Ames Salmonella assay with strains TA98, TA100, TA1535 and TA1537 in the absence and presence of exogenous metabolic activation (S9 fraction from rat liver). The in situ bioremediation experiment was performed using tiles located in the supra-littoral and intertidal zones of a beach seriously affected by the fuel oil spill. The results obtained showed the mutagenic activity of the slightly weathered fuel oil extracts at the beginning of the experiment in strain TA98 that persisted for more than 150 days in both the untreated control and treated tiles independently of the zone of the beach considered. However, after 360 days neither the control nor the treated tiles in the intertidal zone showed mutagenic activity and a weak positive response in strain TA98 was detected for the control fuel oil extracts from supra-littoral tiles. The application of biodiesel to accelerate the biodegradation of this type of fuel oil may constitute a further genotoxic hazard to the environment, since the mutagenic response achieved from the biodiesel-fuel oil mixture in the first samplings (days 0 and 30) was more potent than that obtained from the control tiles. The mutagenic activity was detected along the study with S. typhimurium TA98 in both the presence and absence of S9 microsomal fraction, but the addition of S9 fraction in the assay always increased the number of revertants induced. In general, these findings suggest that the bioremediation strategies used were not effective in eliminating the genotoxic hazard associated with this heavy fuel oil attached to rocky substrate since they did not achieve a decrease in the mutagenic response with respect to the untreated control

  18. Immediate Ecological Impacts of the 2011 Tohoku Earthquake Tsunami on Intertidal Flat Communities

    PubMed Central

    Urabe, Jotaro; Suzuki, Takao; Nishita, Tatsuki; Makino, Wataru

    2013-01-01

    Following the Great East Japan Earthquake in 2011, a large tsunami developed and struck the Pacific coast of eastern Japan. To assess the immediate impacts of the tsunami on coastal communities, changes in taxon composition and richness of macrobenthic animals before and after the tsunami were examined at nine intertidal flats in Sendai Bay and the Sanriku Ria coast. The results showed that 30–80% of taxa indigenously inhabiting intertidal flats disappeared after the tsunami. Among animal types, endobenthic and sessile epibenthic animals were more vulnerable to the tsunami than mobile epibenthic animals like shore crabs and snails. For all the intertidal flats examined, animals that were originally dwellers in lower tidal zones and not recorded before the tsunami were also found right after the tsunami, indicating that the tsunami not only took away many benthic taxa from the intertidal flats but also brought in some taxa from elsewhere. However, overall changes in taxon community composition were greater for intertidal flats that experienced larger inundation heights. These results showed that the ecological impacts of the tsunami were proportional to the physical impacts as gauged by wave height and that mobile epibenthic animals were less vulnerable to the tsunami. PMID:23650529

  19. Immediate ecological impacts of the 2011 Tohoku earthquake tsunami on intertidal flat communities.

    PubMed

    Urabe, Jotaro; Suzuki, Takao; Nishita, Tatsuki; Makino, Wataru

    2013-01-01

    Following the Great East Japan Earthquake in 2011, a large tsunami developed and struck the Pacific coast of eastern Japan. To assess the immediate impacts of the tsunami on coastal communities, changes in taxon composition and richness of macrobenthic animals before and after the tsunami were examined at nine intertidal flats in Sendai Bay and the Sanriku Ria coast. The results showed that 30-80% of taxa indigenously inhabiting intertidal flats disappeared after the tsunami. Among animal types, endobenthic and sessile epibenthic animals were more vulnerable to the tsunami than mobile epibenthic animals like shore crabs and snails. For all the intertidal flats examined, animals that were originally dwellers in lower tidal zones and not recorded before the tsunami were also found right after the tsunami, indicating that the tsunami not only took away many benthic taxa from the intertidal flats but also brought in some taxa from elsewhere. However, overall changes in taxon community composition were greater for intertidal flats that experienced larger inundation heights. These results showed that the ecological impacts of the tsunami were proportional to the physical impacts as gauged by wave height and that mobile epibenthic animals were less vulnerable to the tsunami.

  20. Cosmogenic nuclides application on French Mediterranean shore platform development

    NASA Astrophysics Data System (ADS)

    Giuliano, Jérémy; Lebourg, Thomas; Godard, Vincent; Dewez, Thomas; Braucher, Régis; Bourlès, Didier; Marçot, Nathalie

    2014-05-01

    Rocky shorelines are among the most common elements of the world's littoral zone, and the potential effects of rising sea level on the ever increasing populations require a better understanding of their dynamics. The sinuosity and heterogeneity of the shoreline morphology at large and intermediate wavelengths (1-100 km) results from their constant evolution under the combined influence of marine and continental forcings. This macro-scale organization is the expression of the action of elementary erosion processes acting at shorter wavelengths (<1 km) which lead to the development of shore platforms by landward retreat of cliff edges. Modern analytical techniques (laser-scaning, micro-erosion meters, aerial surveys) constitute appropriate methods to identify and quantify processes of cliff retreat to 1-100 yrs time-scales. But over this time frame, shore platform development appears imperceptible. Precise knowledge of long-term erosion rates are needed to understand rocky shore evolution, and develop quantitative modeling of platform development. Rocky coasts constitute a Quaternary sea level evolution archive that is partly preserved and progressively destroyed. One major challenges is to determine the degree to which coast morphologies are (i) contemporary, (ii) or ancient features inherited, (iii) or partly inherited from Quaternary interglacial stages. In order to fill the lack of long term coast morphodynamic data, we use cosmogenic nuclides (36Cl) to study abrasion surfaces carved in carbonates lithologies along the French Mediterranean coast, in a microtidal environment (Côte Bleue, West of Marseille). 36Cl concentration heritage influences strongly our interpretations in terms of age and denudation of the surfaces. We propose to constrain heritage in sampling oldest relic marine surfaces at 10m of altitude, and along recent cliff scarp. 36Cl concentrations show that the lowest platforms near sea level are contemporary and the highest ones (8-14 m above sea

  1. Recruitment of shore crabs Carcinus maenas on tidal flats: Mussel clumps as an important refuge for juveniles

    NASA Astrophysics Data System (ADS)

    Thiel, M.; Dernedde, T.

    1994-06-01

    During the late summer and early fall, juvenile shore crabs ( Carcinus maenas L.) occurred in high abundances in mussel clumps scattered on tidal flats of the Wadden Sea. Abundances were much lower on bare tidal flats without mussel clumps and decreased substantially from July to November, whereas numbers in mussel clumps remained high. Large crabs left the tidal flats in early fall, whereas juveniles undertook tidal migrations only in the late fall. In March very few shore crabs were found in the intertidal area. The size of juvenile shore crabs living between mussels did not increase significantly during fall. On the bare tidal flats surrounding the mussels, a size increase was observed. Mussel beds and mussel clumps serve as a spatial refuge for the early benthic phases of juvenile shore crabs. Between mussels they can hide effectively from their epibenthic predators. Juvenile shore crabs do not leave the intertidal area and the mussel habitats before their major predators have left the area. Mussel clumps scattered over the tidal flats may be a critical refuge for juvenile shore crabs settling on tidal flats. Intensified efforts in mussel culturing in the European Wadden Sea during recent decades may have caused an increased abundance of mussel clumps on tidal flats, thus enhancing habitat availability for some mussel-clump inhabitants.

  2. Characterising the microbiome of Corallina officinalis, a dominant calcified intertidal red alga.

    PubMed

    Brodie, Juliet; Williamson, Christopher; Barker, Gary L; Walker, Rachel H; Briscoe, Andrew; Yallop, Marian

    2016-08-01

    The living prokaryotic microbiome of the calcified geniculate (articulated) red alga, Corallina officinalis from the intertidal seashore is characterised for the first time based on the V6 hypervariable region of 16S rRNA. Results revealed an extraordinary diversity of bacteria associated with the microbiome. Thirty-five prokaryotic phyla were recovered, of which Proteobacteria, Cyanobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, Acidobacteria, Verrucomicrobia, Firmicutes and Chloroflexi made up the core microbiome. Unclassified sequences made up 25% of sequences, suggesting insufficient sampling of the world's oceans/macroalgae. The greatest diversity in the microbiome was on the upper shore, followed by the lower shore then the middle shore, although the microbiome community composition did not vary between shore levels. The C. officinalis core microbiome was broadly similar in composition to those reported in the literature for crustose coralline algae (CCAs) and free-living rhodoliths. Differences in relative abundance of the phyla between the different types of calcified macroalgal species may relate to the intertidal versus subtidal habit of the taxa and functionality of the microbiome components. The results indicate that much work is needed to identify prokaryotic taxa, and to determine the nature of the relationship of the bacteria with the calcified host spatially, temporally and functionally. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Shoring pumping station excavation

    SciTech Connect

    Glover, J.B.; Reardon, D.J. )

    1991-11-01

    The city of San Mateo, Calif., operates three 12- to 50-year old wastewater pumping stations on a 24-m (80-ft) wide lot located in a residential area near San Francisco Bay. Because the aging stations have difficulty pumping peak 2.19-m{sup 3}/s (50-mgd) wet-weather flows and have structural and maintenance problems, a new 2.62-m{sup 3}/s (60-mgd) station was proposed - the Dale Avenue Pumping Station - to replace the existing ones. To prevent potential damage to adjacent homes, the new station was originally conceived as a circular caisson type; however, a geotechnical investigation recommended against this type of structure because the stiff soils could make sinking the structure difficult. This prompted an investigation of possible shoring methods for the proposed structure. Several shoring systems were investigated, including steel sheeting, soldier beams and lagging, tieback systems, open excavation, and others; however, each had disadvantages that prevented its use. Because these conventional techniques were unacceptable, attention was turned to using deep soil mixing (DSM) to create a diaphragm wall around the area to be excavated before constructing the pumping station. Although this method has been used extensively in Japan since 1983, the Dale Avenue Pumping Station would be the technology's first US application. The technology's anticipated advantages were its impermeability, its fast and efficient installation that did not require tiebacks under existing homes, its adaptability to subsurface conditions ranging from soft ground to stiff clay to gravels, and its lack of pile-driving requirements that would cause high vibration levels during installation.

  4. Louis Shores: Defining Educational Librarianship.

    ERIC Educational Resources Information Center

    Shiflett, Lee

    Louis Shores (1904-1981) was one of the undisputed intellectual leaders of librarianship in the 1960s. By that time, Shores had already established a national reputation in the field of reference work and had become prominent in education for librarianship. His lifelong commitment to his profession centered around his intense belief in the power…

  5. SSRL Emergency Response Shore Tool

    NASA Technical Reports Server (NTRS)

    Mah, Robert W.; Papasin, Richard; McIntosh, Dawn M.; Denham, Douglas; Jorgensen, Charles; Betts, Bradley J.; Del Mundo, Rommel

    2006-01-01

    The SSRL Emergency Response Shore Tool (wherein SSRL signifies Smart Systems Research Laboratory ) is a computer program within a system of communication and mobile-computing software and hardware being developed to increase the situational awareness of first responders at building collapses. This program is intended for use mainly in planning and constructing shores to stabilize partially collapsed structures. The program consists of client and server components, runs in the Windows operating system on commercial off-the-shelf portable computers, and can utilize such additional hardware as digital cameras and Global Positioning System devices. A first responder can enter directly, into a portable computer running this program, the dimensions of a required shore. The shore dimensions, plus an optional digital photograph of the shore site, can then be uploaded via a wireless network to a server. Once on the server, the shore report is time-stamped and made available on similarly equipped portable computers carried by other first responders, including shore wood cutters and an incident commander. The staff in a command center can use the shore reports and photographs to monitor progress and to consult with structural engineers to assess whether a building is in imminent danger of further collapse.

  6. Between tide and wave marks: a unifying model of physical zonation on littoral shores

    PubMed Central

    Bird, Christopher E.; Franklin, Erik C.; Smith, Celia M.

    2013-01-01

    The effects of tides on littoral marine habitats are so ubiquitous that shorelines are commonly described as ‘intertidal’, whereas waves are considered a secondary factor that simply modifies the intertidal habitat. However mean significant wave height exceeds tidal range at many locations worldwide. Here we construct a simple sinusoidal model of coastal water level based on both tidal range and wave height. From the patterns of emergence and submergence predicted by the model, we derive four vertical shoreline benchmarks which bracket up to three novel, spatially distinct, and physically defined zones. The (1) emergent tidal zone is characterized by tidally driven emergence in air; the (2) wave zone is characterized by constant (not periodic) wave wash; and the (3) submergent tidal zone is characterized by tidally driven submergence. The decoupling of tidally driven emergence and submergence made possible by wave action is a critical prediction of the model. On wave-dominated shores (wave height ≫ tidal range), all three zones are predicted to exist separately, but on tide-dominated shores (tidal range ≫ wave height) the wave zone is absent and the emergent and submergent tidal zones overlap substantially, forming the traditional “intertidal zone”. We conclude by incorporating time and space in the model to illustrate variability in the physical conditions and zonation on littoral shores. The wave:tide physical zonation model is a unifying framework that can facilitate our understanding of physical conditions on littoral shores whether tropical or temperate, marine or lentic. PMID:24109544

  7. Larval settlement rate: a leading determinant of structure in an ecological community of the marine intertidal zone

    SciTech Connect

    Gaines, S.; Roughgarden, J.

    1985-06-01

    Field studies demonstrate that the population structure of the barnacle Balanus glandula differs between locations of high and low larval settlement rate. These observations, together with results from a model for the demography of an open, space-limited population, suggest that the settlement rate may be a more important determinant of rocky intertidal community structure than is presently realized. At the low-settlement location mortality of barnacles is independent of the area occupied by barnacles. At the high-settlement location mortality is cover-dependent due to increased predation by starfish on areas of high barnacle cover. In both locations the cover-independent component of mortality does not vary with age during the first 60 weeks. Generalizations that the highest species diversity in a rocky intertidal community is found at locations of intermediate disturbance, and that competition causes zonation between species of the barnacle genera Balanus and Chthamalus, seem to apply only to locations with high-settlement rates.

  8. UV radiation impacts body weight, oxygen consumption, and shelter selection in the intertidal vertebrate Girella laevifrons.

    PubMed

    Pulgar, José; Waldisperg, Melany; Galbán-Malagón, Cristóbal; Maturana, Diego; Pulgar, Victor M; Aldana, Marcela

    2017-02-01

    The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to ozone layer depletion, and this fact represents an opportunity to evaluate the physiological and behavioral responses of animals to this global-scale stressor. The transitory fish Girella laevifrons inhabits pools in the upper intertidal zone, which is characterized by exposure to a wide range of stressors, including UV radiation. We documented the field magnitude and the impact of UV radiation on oxygen consumption, body mass variations, and shelter (rocky and algae) selection by G. laevifrons. UV-exposed animals showed increased oxygen consumption, slower body weight increase, and active rocky shelter selection. Control fish showed increased body weight and no evident shelter selection. The results indicated that UV exposure affects fish energetic balance and habitat selection to favor greater protection against radiation. Increased UV exposure in transitory intertidal animals at levels observed in upper intertidal pools may alter the residency time of fish before leaving for the subtidal zone. Therefore, UV-induced energetic changes may determine animal performance and ontogenetic physiological itineraries, whereas shelter quality might determine habitat use. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Ecological consequences of coseismic uplift on the intertidal kelp belts of Lessonia nigrescens in central Chile

    NASA Astrophysics Data System (ADS)

    Castilla, J. C.; Oliva, D.

    1990-07-01

    Coseismic uplift from the Chilean earthquake of 3 March 1985 caused changes in the biomass and vertical zonation of rocky intertidal organisms at four sites along 150 km of the central Chilean coast. The 11-60 cm uplift caused widespread mortality mainly of the dominant intertidal kelp Lessonia nigrescens, reducing its biomass in the upper part of its pre-earthquake range and altering the vertical zonation. The L. nigrescens belt shrank from the top by about 0·5-1 m within 1 year of the shock, then expanded downward by about 1 m. An important part of the primary space liberated at the pre-earthquake upper border of Lessonia was invaded by the barnacles Chthamalus scabrosus and Jehlius cirratus. None of the foregoing changes occurred at two control sites located outside the shock area. The ecological effects of these recurrent sudden and drastic environmental processes on rocky intertidal communities include the liberation of primary space, enhancement of mosaic areas and modification of the vertical zonation of competitively dominant organisms.

  10. The Rocky Mountain Trench

    NASA Image and Video Library

    2017-09-27

    Acquisition Date: February 2004 The high reflectance of clouds compared to the surrounding land, coupled with the low sun elevation when this image was acquired, causes low clouds to appear red as they fill a portion of the Rocky Mountain Trench. Running parallel with the peaks of the Canadian Rockies and ranging from 2 to 10 miles (3 to 16 kilometers) wide and about 900 miles (1,448 kilometers) long, the Trench aligns with the Fraser River and makes its way past Mount Robson, the highest peak in the Canadian Rockies at 12,972 feet (3,954 meters). Mount Robson is near the center of this image. Credit: NASA/GSFC/Landsat/USGS To learn more about Landsat and to see the orginal high res file go to: landsat.usgs.gov/gallery_view.php?category=greenflag&...

  11. A geographic comparison of the resting site fidelity behaviour in an intertidal limpet: Correlation with biological and physical factors

    NASA Astrophysics Data System (ADS)

    Nuñez, Jesús D.; Ocampo, Emiliano H.; Cledón, Maximiliano

    2014-05-01

    Many organisms vary their behaviour in response to environmental change. In stressful habitats motile organisms often exhibit behavioural patterns that are consistent with stress-minimizing strategies. In the present study we analysed the proportions of individuals with strong site fidelity and distances travelled by “unfaithful” individuals from their home scar at different temporal and spatial scales in the intertidal gastropod Siphonaria lessoni. We also assessed the behavioural response of S. lessoni to biological pressures such as conspecific population density and food availability (assessed by measures of chlorophyll a). The experiments were carried out in the arid climate of Patagonia on the rocky intertidal of Las Grutas (LG), and in the humid climate of The Pampas on the rocky intertidal of Mar del Plata (MDP) Argentina. At each site, shells of five hundred animals were marked with epoxy paint. Movement was measured as distance to a reference point after periods of one, five and ten days. Our results showed a positive relationship between food availability, site fidelity and distance to home scar for almost all observation days, but no relationship between population density and behavioural variables. Limpets in LG were more “faithful” than in MDP. Unfaithful limpets had the same mean displacement for all days and seasons except for Spring day-1 where MDP was higher than in LG and in Autumn day-10 where MDP was smaller than LG. The present results thus show differential response behaviour in intertidal limpets probably driven by the environmental conditions in which they live.

  12. Community Regulation: The Relative Importance of Recruitment and Predation Intensity of an Intertidal Community Dominant in a Seascape Context

    PubMed Central

    Rilov, Gil; Schiel, David R.

    2011-01-01

    Predicting the strength and context-dependency of species interactions across multiple scales is a core area in ecology. This is especially challenging in the marine environment, where populations of most predators and prey are generally open, because of their pelagic larval phase, and recruitment of both is highly variable. In this study we use a comparative-experimental approach on small and large spatial scales to test the relationship between predation intensity and prey recruitment and their relative importance in shaping populations of a dominant rocky intertidal space occupier, mussels, in the context of seascape (availability of nearby subtidal reef habitat). Predation intensity on transplanted mussels was tested inside and outside cages and recruitment was measured with standard larval settlement collectors. We found that on intertidal rocky benches with contiguous subtidal reefs in New Zealand, mussel larval recruitment is usually low but predation on recruits by subtidal consumers (fish, crabs) is intense during high tide. On nearby intertidal rocky benches with adjacent sandy subtidal habitats, larval recruitment is usually greater but subtidal predators are typically rare and predation is weaker. Multiple regression analysis showed that predation intensity accounts for most of the variability in the abundance of adult mussels compared to recruitment. This seascape-dependent, predation-recruitment relationship could scale up to explain regional community variability. We argue that community ecology models should include seascape context-dependency and its effects on recruitment and species interactions for better predictions of coastal community dynamics and structure. PMID:21887351

  13. Linking macrobenthic communities structure and zonation patterns on sandy shores: Mapping tool toward management and conservation perspectives in Northern France

    NASA Astrophysics Data System (ADS)

    Rolet, Céline; Spilmont, Nicolas; Dewarumez, Jean-Marie; Luczak, Christophe

    2015-05-01

    In a context of intensifying anthropogenic pressures on sandy shores, the mapping of benthic habitat appears as an essential first step and a fundamental baseline for marine spatial planning, ecosystem-based management and conservation efforts of soft-sediment intertidal areas. Mapping allows representing intertidal habitats that are basically characterised by abiotic (e.g sediments, exposure to waves…) and biotic factors such as macrobenthic communities. Macrobenthic communities are known to show zonation patterns across sandy beaches and many studies highlighted the existence of three biological zones. We tested this general model of a tripartite biological division of the shore at a geographical scale of policy, conservation and management decisions (i.e. Northern France coastline), using multivariate analyses combined with the Direct Field Observation (DFO) method. From the upper to the lower shores, the majority of the beaches exhibited three macrobenthic communities confirming the existence of the tripartite biological division of the shore. Nevertheless, in some cases, two or four zones were found: (1) two zones when the drying zone located on the upper shore was replaced by littoral rock or engineering constructions and (2) four zones on beaches and estuaries where a muddy-sand community occurred from the drift line to the mid shore. The correspondence between this zonation pattern of macrobenthic communities and the EUNIS habitat classification was investigated and the results were mapped to provide a reference state of intertidal soft-sediment beaches and estuaries. Our results showed evidence of the applicability of this EUNIS typology for the beaches and estuaries at a regional scale (Northern France coastline) with a macroecological approach. In order to fulfil the requirements of the European Directives (WFD and MFSD), this mapping appears as a practical tool for any functional study on these coastal ecosystems, for the monitoring of anthropogenic

  14. Rocky Mountain Spotted Fever.

    PubMed

    Phillips, Jennan

    2017-01-01

    The tick-borne disease Rocky Mountain spotted fever (RMSF) can have deadly outcomes unless treated appropriately, yet nonspecific flu-like symptoms complicate diagnosis. Occupational health nurses must have a high index of suspicion with symptomatic workers and recognize that recent recreational or occupational activities with potential tick exposure may suggest RMSF.

  15. Historians' Rocky Job Market

    ERIC Educational Resources Information Center

    Grafton, Anthony; Townsend, Robert B.

    2008-01-01

    In this article, the authors discuss how the historians' job market is perennially rocky. The history profession had its "golden age" in the 1950s and early 1960s when a generation born in the demographic trench of the Depression entered the market just as the first of the baby boomers began to swell college enrollments. But that moment was…

  16. Rocky Mountain Riparian Digest

    Treesearch

    Deborah M. Finch

    2008-01-01

    The Rocky Mountain Riparian Digest presents the many facets of riparian research at the station. Included are articles about protecting the riparian habitat, the social and economic values of riparian environments, watershed restoration, remote sensing tools, and getting kids interested in the science.

  17. Historians' Rocky Job Market

    ERIC Educational Resources Information Center

    Grafton, Anthony; Townsend, Robert B.

    2008-01-01

    In this article, the authors discuss how the historians' job market is perennially rocky. The history profession had its "golden age" in the 1950s and early 1960s when a generation born in the demographic trench of the Depression entered the market just as the first of the baby boomers began to swell college enrollments. But that moment was…

  18. Nitrate uptake varies with tide height and nutrient availability in the intertidal seaweed Fucus vesiculosus.

    PubMed

    Benes, Kylla M; Bracken, Matthew E S

    2016-10-01

    Intertidal seaweeds must cope with a suite of stressors imposed by aerial exposure at low tide, including nutrient limitation due to emersion. Seaweeds can access nutrients only when submerged, so individuals living higher compared to lower on the shore may have adaptations allowing them to acquire sufficient amounts of nutrients to survive and maintain growth. Using a combination of observations and experiments, we aimed to identify intraspecific variation in nitrate uptake rates across the intertidal distribution of F. vesiculosus, as well as test for acclimation in response to a change in tide height. We replicated our study at sites spanning nearly the entire Gulf of Maine coastline, to examine how local environmental variability may alter intraspecific variation in nitrate uptake. We found that average nitrate uptake rates were ~18% higher in upper compared to lower intertidal Fucus vesiculosus. Furthermore, we found evidence for both acclimation and adaptation to tide height during a transplant experiment. F. vesiculosus transplanted from the lower to the upper intertidal zone was characterized by increased nitrate uptake, but individuals transplanted from the upper to the lower intertidal zone retained high uptake rates. Our observations differed among Gulf of Maine regions and among time points of our study. Importantly, these differences may reflect associations between nitrate uptake rates and abiotic environmental conditions and seaweed nutrient status. Our study highlights the importance of long-term variation in ambient nutrient supply in driving intraspecific variation of seaweeds across the intertidal gradient and local and seasonal variation in ambient nutrient levels in mediating intraspecific differences.

  19. No estuarine intertidal bathymetry? No worries! Estimating intertidal depth contours from readily available GIS data

    EPA Science Inventory

    The importance of littoral elevation to the distribution of intertidal species has long been a cornerstone of estuarine ecology and its historical importance to navigation cannot be understated. However, historically, intertidal elevation measurements have been sparse likely due ...

  20. No estuarine intertidal bathymetry? No worries! Estimating intertidal depth contours from readily available GIS data

    EPA Science Inventory

    The importance of littoral elevation to the distribution of intertidal species has long been a cornerstone of estuarine ecology and its historical importance to navigation cannot be understated. However, historically, intertidal elevation measurements have been sparse likely due ...

  1. The Variety of Shore Birds

    ERIC Educational Resources Information Center

    Varza, Dennis

    1977-01-01

    The types of habitats that exist along the ocean shore and the various types of birds inhabiting them are detailed. Topics discussed include shorebird feeding habits and methods, nesting patterns, and seasonal migration. (BT)

  2. The Variety of Shore Birds

    ERIC Educational Resources Information Center

    Varza, Dennis

    1977-01-01

    The types of habitats that exist along the ocean shore and the various types of birds inhabiting them are detailed. Topics discussed include shorebird feeding habits and methods, nesting patterns, and seasonal migration. (BT)

  3. High-resolution onshore-offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France

    NASA Astrophysics Data System (ADS)

    Duperret, Anne; Raimbault, Céline; Le Gall, Bernard; Authemayou, Christine; van Vliet-Lanoë, Brigitte; Regard, Vincent; Dromelet, Elsa; Vandycke, Sara

    2016-07-01

    Modern shore platforms developed on rocky coasts are key areas for understanding coastal erosion processes during the Holocene. This contribution offers a detailed picture of two contrasted shore-platform systems, based on new high-resolution shallow-water bathymetry, further coupled with aerial LiDAR topography. Merged land-sea digital elevation models were achieved on two distinct types of rocky coasts along the eastern English Channel in France (Picardy and Upper-Normandy: PUN) and in a NE Atlantic area (SW Brittany: SWB) in NW France. About the PUN case, submarine steps, identified as paleo-shorelines, parallel the actual coastline. Coastal erosive processes appear to be continuous and regular through time, since mid-Holocene at least. In SWB, there is a discrepancy between contemporary coastline orientation and a continuous step extending from inland to offshore, identified as a paleo-shoreline. This illustrates a polyphased and inherited shore platform edification, mainly controlled by tectonic processes.

  4. Intertidal biofilm distribution underpins differential tide-following behavior of two sandpiper species (Calidris mauri and Calidris alpina) during northward migration

    NASA Astrophysics Data System (ADS)

    Jiménez, Ariam; Elner, Robert W.; Favaro, Corinna; Rickards, Karen; Ydenberg, Ronald C.

    2015-03-01

    The discovery that some shorebird species graze heavily on biofilm adds importance to elucidating coastal processes controlling biofilm, as well as impetus to better understand patterns of shorebird use of intertidal flats. Western sandpipers (Calidris mauri) and dunlin (Calidris alpina) stopover in the hundreds of thousands on the Fraser River estuary, British Columbia, Canada, during northward migration to breeding areas. Western sandpipers show greater modification of tongue and bill morphology for biofilm feeding than dunlin, and their diet includes more biofilm. Therefore, we hypothesized that these congeners differentially use the intertidal area. A tide following index (TFI) was used to describe their distributions in the upper intertidal during ebbing tides. Also, we assessed sediment grain size, biofilm (= microphytobenthic or MPB) biomass and invertebrate abundance. Foraging dunlin closely followed the ebbing tide line, exploiting the upper intertidal only as the tide retreated through this area. In contrast, western sandpipers were less prone to follow the tide, and spent more time in the upper intertidal. Microphytobenthic biomass and sediment water content were highest in the upper intertidal, indicating greater biofilm availability for shorebirds in the first 350 m from shore. Invertebrate density did not differ between sections of the upper intertidal. Overall, western sandpiper behaviour and distribution more closely matched MPB biofilm availability than invertebrate availability. Conservation of sandpipers should consider physical processes, such as tides and currents, which maintain the availability of biofilm, a critical food source during global migration.

  5. Biological impacts of oil pollution and cleaning in the intertidal zone of exposed sandy beaches: Preliminary study of the “Prestige” oil spill

    NASA Astrophysics Data System (ADS)

    de la Huz, R.; Lastra, M.; Junoy, J.; Castellanos, C.; Viéitez, J. M.

    2005-10-01

    On 13th September 2002, the oil tanker "Prestige" sunk off the Galician coast, causing one of the most important oil spills in history, which affected the entire coastline, particularly the exposed rocky shores and sandy beaches. Seventeen exposed sandy beaches were analysed along the Galician coast, in May 2003, and results were compared with previous data for September 1995 and 1996. The intertidal areas of the beaches were sampled in four tidal zones along the beach profile: swash, resurgence, retention and dry sand. Six cores of 0.05 m 2 were taken at each level and washed through a 1 mm mesh. Sediment samples were collected at each level for sediment analysis. The species were grouped into six main taxonomic groups: polychaetes, molluscs, marine crustaceans, semi-terrestrial crustaceans, insects and others. The total number of species was calculated in each group before and after the oil spill. The disturbance effect on each tidal level was determined. A decrease in the species richness was generally observed in all the studied beaches, although this decrease was not homogeneous in all the taxonomic groups. Polychaetes, insects, semi-terrestrial crustaceans and others lost species in all cases, while marine crustaceans did not show this tendency, losing species in some cases and gaining in others. The most affected beaches lost up to 66.7% of the total species richness after the oil spill. The most disturbed levels were swash, losing most of the polychaetes, and dry sand, with decrease in insects and semi-terrestrial crustaceans in many cases. Dry sand level received a high amount of oil and was more affected by grooming and cleaning activities where fuel and polluted material were removed, including algal wrack that is used by the supratidal macrofauna as food and shelter.

  6. Composition dynamics of epilithic intertidal bacterial communities exposed to high copper levels.

    PubMed

    De la Iglesia, Rodrigo; Valenzuela-Heredia, Daniel; Andrade, Santiago; Correa, Juan; González, Bernardo

    2012-03-01

    Copper has a dual role for organisms, both as micronutrient and toxic element. Copper mining activities have an enormous ecological impact because of the extraction process and the consequent release of copper-containing waste materials to the environment. In northern Chile, mainly in the Chañaral coastal area, this phenomenon is clearly evident. The released waste material has caused a strong modification of the area, and copper enrichment of beaches and rocky shores has provoked a decrease in the richness and diversity of many species of macroorganisms. However, the effects that copper enrichment has on microbial (e.g. bacterial epilithic) communities associated with the rocky shore environment are poorly understood. Using a culture-independent molecular approach, field sampling and laboratory microcosm experiments, we determined the effects of copper enrichment on bacterial communities inhabiting the rocky shore environment. Field samples showed a strong effect of copper on the structure of the natural bacterial epilithic communities, and microcosm experiments demonstrated rapid changes in bacterial community when copper is added, and reversibility of this effect within 48 h after copper is removed. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  7. Decomposition patterns in terrestrial and intertidal habitats on Oahu Island and Coconut Island, Hawaii.

    PubMed

    Davis, J B; Goff, M L

    2000-07-01

    Decomposition studies were conducted at two sites on the Island of Oahu, Hawaii, to compare patterns of decomposition and arthropod invasion in intertidal and adjacent terrestrial habitats. The animal model used was the domestic pig. One site was on Coconut Island in Kaneohe Bay on the northeast side of Oahu, and the second was conducted in an anchialine pool located at Barber's Point Naval Air Station on the southwest shore of Oahu. At both sites, the terrestrial animal decomposed in a manner similar to what has been observed in previous studies in terrestrial habitats on the island of Oahu. Rate of biomass depletion was slower in both intertidal studies, and decomposition was primarily due to tide and wave activity and bacterial decomposition. No permanent colonization of carcasses by insects was seen for the intertidal carcass at Coconut Island. At the anchialine pool at Barber's Point Naval Air Station, Diptera larvae were responsible for biomass removal until the carcass was reduced below the water line and, from that point on, bacterial action was the means of decomposition. Marine and terrestrial scavengers were present at both sites although their impact on decomposition was negligible. Five stages of decomposition were recognized for the intertidal sites: fresh, buoyant/floating, deterioration/disintegration, buoyant remains, and scattered skeletal.

  8. 46 CFR 169.686 - Shore power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Shore power. 169.686 Section 169.686 Shipping COAST... Gross Tons § 169.686 Shore power. If a shore power connection is provided it must meet the following requirements: (a) A shore power connection box or receptacle and a cable connecting this box or receptacle...

  9. 46 CFR 169.686 - Shore power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Shore power. 169.686 Section 169.686 Shipping COAST... Gross Tons § 169.686 Shore power. If a shore power connection is provided it must meet the following requirements: (a) A shore power connection box or receptacle and a cable connecting this box or receptacle...

  10. 46 CFR 169.686 - Shore power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Shore power. 169.686 Section 169.686 Shipping COAST... Gross Tons § 169.686 Shore power. If a shore power connection is provided it must meet the following requirements: (a) A shore power connection box or receptacle and a cable connecting this box or receptacle...

  11. 46 CFR 169.686 - Shore power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Shore power. 169.686 Section 169.686 Shipping COAST... Gross Tons § 169.686 Shore power. If a shore power connection is provided it must meet the following requirements: (a) A shore power connection box or receptacle and a cable connecting this box or receptacle...

  12. 46 CFR 169.686 - Shore power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Shore power. 169.686 Section 169.686 Shipping COAST... Gross Tons § 169.686 Shore power. If a shore power connection is provided it must meet the following requirements: (a) A shore power connection box or receptacle and a cable connecting this box or receptacle...

  13. Freezing resistance in intertidal invertebrates.

    PubMed

    Murphy, D J

    1983-01-01

    Intertidal invertebrates survive exposures to temperatures as low as -20 degrees C by tolerating the presence of tissue ice. This resistance to freezing is influenced by such factors as the time and temperature of exposure, the rate of cooling during tissue ice formation, the temperature and salinity of the seawater to which the animals have adapted, and the oxygen content of tissues. Freezing injury appears to result primarily from extracellular ice formation, although for certain smaller invertebrates that cool at rates exceeding 0.4 degrees C min-1 during tissue ice formation, intracellular ice formation may be the cause of freezing injury. Extracellular ice formation is a dehydration stress, and injury resulting from extracellular ice appears to involve membrane damage resulting from the loss of a critical amount of cellular water. Physiological mechanisms that lower the temperatures at which extracellular ice causes injury are dependent on factors that either (a) "bind" a certain fraction of intracellular water and thus reduce the amount of water lost during freezing, or (b) increase the resistance of cells to greater quantities of tissue ice. Certain structural components and glycoproteins have been isolated from an intertidal mollusk that can impede or prevent the formation of ice. However, a quantitative relationship between these components and freezing resistance has not been established. The resistance to greater quantities of tissue ice appears to be associated with low levels of tissue oxygen and with anaerobic metabolism. A rise in blood calcium concentration following a shift from aerobic to anaerobic metabolism can account for part of the increased resistance of an intertidal mollusk to greater quantities of tissue ice, while membrane changes and factors that reduce the toxic effects of oxygen may also be involved. The possibility that oxygen is associated with injury resulting from extracellular ice formation in intertidal invertebrates deserves

  14. Subsurface Intertidal Microbes: A Cryptic Source Of Organic Carbon For Beach Ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.; Giver, Lorraine J.; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    Some freshwater, marine or hotspring beaches have no visible source of primary production, yet beneath the surface is an interstitial photosynthetic microbial community. To assess the significance of this source of organic carbon, we measured in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle. Gross fixation for a transect (99 x 1 m) perpendicular to the shore was approx. 4041 mg C fixed/ day, or approx. 41 mg C fixed/ sq m day. In contrast, an adjacent well-established cyanobacterial (Lyngbya) mat was approx. 12 x as productive (approx. 490 mg C fixed/sq m day). Thus, subsurface sand mats may be an overlooked, yet important, endogenous source of organic carbon for intertidal ecosystems, as well as a sink in the global carbon cycle.

  15. Subsurface Intertidal Microbes: A Cryptic Source Of Organic Carbon For Beach Ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.; Giver, Lorraine J.; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    Some freshwater, marine or hotspring beaches have no visible source of primary production, yet beneath the surface is an interstitial photosynthetic microbial community. To assess the significance of this source of organic carbon, we measured in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle. Gross fixation for a transect (99 x 1 m) perpendicular to the shore was approx. 4041 mg C fixed/ day, or approx. 41 mg C fixed/ sq m day. In contrast, an adjacent well-established cyanobacterial (Lyngbya) mat was approx. 12 x as productive (approx. 490 mg C fixed/sq m day). Thus, subsurface sand mats may be an overlooked, yet important, endogenous source of organic carbon for intertidal ecosystems, as well as a sink in the global carbon cycle.

  16. Preference versus performance: body temperature of the intertidal snail Chlorostoma funebralis.

    PubMed

    Tepler, Sarah; Mach, Katharine; Denny, Mark

    2011-04-01

    Evolutionary theory predicts that, in variable environments, it is advantageous for ectothermic organisms to prefer a body temperature slightly below the physiological optimum. This theory works well for many terrestrial organisms but has not been tested for animals inhabiting the hypervariable physical environment of intertidal shores. In laboratory experiments, we allowed the intertidal snail Chlorostoma funebralis to position itself on a temperature gradient, then measured its thermal preference and determined an index of how its performance varied with temperature. Snails performed a biased random walk along the temperature gradient, which, contrary to expectations, caused them to aggregate where body temperature was 15 to 17 °C below their temperature of optimum performance and near the species' lower thermal limit. This "cold-biased" behavioral response may guide snails to refuges in shaded cracks and crevices, but potentially precludes C. funebralis from taking full advantage of its physiological capabilities.

  17. Trematodes indicate animal biodiversity in the Chilean intertidal and Lake Tanganyika.

    PubMed

    Hechinger, Ryan F; Lafferty, Kevin D; Kuris, Armand M

    2008-08-01

    Trematode communities in populations of estuarine snails can reflect surrounding animal diversity, abundance, and trophic interactions. We know less about the potential for trematodes to serve as bioindicators in other habitats. Here, we reanalyze data from 2 published studies concerning trematodes, 1 in the Chilean rocky intertidal zone and the other from the East African rift lake, Lake Tanganyika. Our analyses indicate that trematodes are more common in protected areas and that in both habitats they are directly and positively related to surrounding host abundance. This further supports the notion that trematodes in first intermediate hosts can serve as bioindicators of the condition of free-living animal communities in diverse ecosystems.

  18. Engineering novel habitats on urban infrastructure to increase intertidal biodiversity.

    PubMed

    Chapman, M G; Blockley, D J

    2009-09-01

    Urbanization replaces natural shorelines with built infrastructure, seriously impacting species living on these "new" shores. Understanding the ecology of developed shorelines and reducing the consequences of urban development to fauna and flora cannot advance by simply documenting changes to diversity. It needs a robust experimental programme to develop ways in which biodiversity can be sustained in urbanized environments. There have, however, been few such experiments despite wholesale changes to shorelines in urbanized areas. Seawalls--the most extensive artificial infrastructure--are generally featureless, vertical habitats that support reduced levels of local biodiversity. Here, a mimic of an important habitat on natural rocky shores (rock-pools) was experimentally added to a seawall and its impact on diversity assessed. The mimics created shaded vertical substratum and pools that retained water during low tide. These novel habitats increased diversity of foliose algae and sessile and mobile animals, especially higher on the shore. Many species that are generally confined to lowshore levels, expanded their distribution over a greater tidal range. In fact, there were more species in the constructed pools than in natural pools of similar size on nearby shores. There was less effect on the abundances of mobile animals, which may be due to the limited time available for recruitment, or because these structures did not provide appropriate habitat. With increasing anthropogenic intrusion into natural areas and concomitant loss of species, it is essential to learn how to build urban infrastructure that can maintain or enhance biodiversity while meeting societal and engineering criteria. Success requires melding engineering skills and ecological understanding. This paper demonstrates one cost-effective way of addressing this important issue for urban infrastructure affecting nearshore habitats.

  19. Rocky Mountain spotted fever.

    PubMed

    Lacz, N L; Schwartz, R A; Kapila, R

    2006-04-01

    Rocky Mountain spotted fever (RMSF) is an unusual but important dermatological condition to identify without hesitation. The classic triad of headache, fever, and a rash that begins on the extremities and travels proximally to involve the trunk is found in a majority of patients. The cutaneous centripetal pattern is a result of cell to cell migration by the causative organism Rickettsia rickettsii. Such individuals should receive prompt antimicrobial therapy and supportive care to avoid serious and potentially fatal complications.

  20. Rocky Mountain spotted fever.

    PubMed

    Kamper, C A; Chessman, K H; Phelps, S J

    1988-02-01

    The epidemiology, pathogenesis, clinical features, and treatment of Rocky Mountain spotted fever are reviewed. Rocky Mountain spotted fever is a severe infection caused by Rickettsia rickettsii transmitted to man by various species of ticks. High-incidence areas exist in the southeast and south central United States. Only 60-70% of patients with the disease report a history of tick bite or exposure to tick-infested areas. The disease is initially characterized by fever, headache, gastrointestinal complaints, myalgia, and a generalized rash. In several days generalized vasculitis may lead to periorbital edema and nonpitting edema of the face and extremities. Central nervous system involvement is common. Because signs and symptoms associated with the disease are nonspecific, the diagnosis is often delayed or missed. Traditionally diagnostic confirmation relied on serologic testing, but an indirect fluorescent antibody assay will soon be commercially available. Rocky Mountain spotted fever is usually treated with the rickettsiostatic agents chloramphenicol or tetracycline, but few comparative data on these agents in patients with the disease are available. For patients who cannot tolerate oral medications, intravenous chloramphenicol sodium succinate is the preferred treatment; chloramphenicol is also the drug of choice for children less than eight years of age. Otherwise, oral tetracycline hydrochloride is the drug of choice. Antibiotic therapy should be continued for 7-10 days or until the patient is afebrile for two to five days. All cases of Rocky Mountain spotted fever must be reported to the Centers for Disease Control. The best ways to decrease the morbidity and mortality of the disease are to increase awareness of its signs and symptoms and to prevent exposure to ticks.

  1. Modeling the role of weathering in shore platform development

    NASA Astrophysics Data System (ADS)

    Trenhaile, Alan S.

    2008-02-01

    A mathematical, wave-erosional model was modified to study the additional effect of weathering by wetting and drying and salt weathering on the development of shore platforms in macro- to mesotidal environments. Model rates of downwearing by these processes, at different tidal elevations, were based on data obtained from a series of laboratory experiments on sandstones from eastern Canada. Backwearing by mechanical wave erosion was calculated using basic wave equations. There were several types of run which were designed to determine the effect of: weathering and the production of fine-grained sediment; the periodic accumulation of debris on weathering in the upper intertidal zone; and weathering in reducing rock resistance and facilitating wave quarrying. The results implied that, compared to mechanical wave erosion, the direct effect of weathering and fine-grained sediment production makes only a small contribution to the long-term development of shore platforms. The relationship between cliff-foot debris occurrence and platform development and morphology was inconsistent because of the negative feedback relationship between erosion rates, surface gradients, and rates of wave attenuation. The model suggested that weathering can play an important, indirect role in assisting wave quarrying of joint blocks and other rock fragments.

  2. The Heat-Shock Response: Its Variation, Regulation and Ecological Importance in Intertidal Gastropods (genus Tegula).

    PubMed

    Tomanek, Lars

    2002-08-01

    The enhanced synthesis of heat-shock proteins (hsps), called the heat-shock (or stress) response, is activated when environmental stress denatures proteins. Hsp synthesis is activated at the upper temperatures of an organism's thermal range and is therefore thought to be critical for enhancing thermal tolerance limits in ectothermic animals. Here I show that the two temperate sister species T. brunnea and T. montereyi that occupy the subtidal and low-intertidal zone differ from the low- to mid-intertidal T. funebralis (and the subtropical mid-intertidal T. rugosa) in (i) heat tolerance, (ii) the onset temperature of their main hsp, hsp70 (70 kDa), (iii) the temperature of maximal hsp70 synthesis, (iv) the upper temperature of hsp synthesis, and (v) the recovery from a thermal stress typical for the mid-intertidal zone. A regulatory model in which hsps themselves regulate their own transcription and synthesis through a negative autoregulatory feedback mechanism can explain acclimation-induced but not interspecific variation in the onset temperature of hsp70 synthesis. Transplanting species across their vertical distribution limits showed that interspecific differences in the stress response are likely to prevent species occurring lower from inhabiting sites higher in the rocky intertidal zone. Endogenous levels of a hsp of a molecular mass of 72 kDa, hsp72, changed little with heat stress in a species' native thermal environment. The results therefore confirm the importance of interspecific differences in the stress response for setting limits to an organism's thermal environment. However, the role of hsps as short-term indicators of sublethal heat stress within a species' native thermal environment may be limited without a better understanding of their functional and regulatory characteristics.

  3. Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae), a parasite of the intertidal bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae) on the Oregon coast

    PubMed Central

    2012-01-01

    Background It is rare to find terrestrial nematode lineages parasitizing arthropods inhabiting the intertidal or littoral zone of the oceans. During an ecological study along the Oregon dunes, an allantonematid nematode (Tylenchomorpha: Allantonematidae) was discovered parasitizing the intertidal shore bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae). This shore bug is adapted to an intertidal environment and can survive short periods of submergence during high tides. The present study describes the nematode parasite and discusses aspects of its development, ecology and evolution. Methods Adults and last instar nymphs of S. laticollis (Hemiptera: Saldidae) were collected from the high intertidal zone among clumps of Juncus L. (Juncaceae) plants at Waldport, Oregon on October 3, 2011. The bugs were dissected in 1% saline solution and the nematodes killed in 1% Ringers solution and immediately fixed in 5% formalin (at 20°C). Third stage juveniles removed from infected hosts were maintained in 1% saline solution until they matured to the adult stage, molted and mated. Results Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae) is described from last instar nymphs and adults of the intertidal bug, Saldula laticollis on the Oregon coast. The new genus can be distinguished from other genera in the Allantonematidae by a stylet lacking basal knobs in both sexes, an excretory pore located behind the nerve ring, ribbed spicules, a gubernaculum, the absence of a bursa and the elongate-tubular shape of the ovoviviparous parasitic females. Studies of the organogenesis of Halophilanema showed development to third stage juveniles in the uterus of parasitic females. Maturation to the free-living adults and mating occurred in the environment. The incidence of infection of S. laticollis ranged from 0% to 85% depending on the microhabitat in the intertidal zone. Conclusions Based on the habitat and morphological characters, it is proposed that Halophilanema

  4. Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae), a parasite of the intertidal bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae) on the Oregon coast.

    PubMed

    Poinar, George O

    2012-02-01

    It is rare to find terrestrial nematode lineages parasitizing arthropods inhabiting the intertidal or littoral zone of the oceans. During an ecological study along the Oregon dunes, an allantonematid nematode (Tylenchomorpha: Allantonematidae) was discovered parasitizing the intertidal shore bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae). This shore bug is adapted to an intertidal environment and can survive short periods of submergence during high tides. The present study describes the nematode parasite and discusses aspects of its development, ecology and evolution. Adults and last instar nymphs of S. laticollis (Hemiptera: Saldidae) were collected from the high intertidal zone among clumps of Juncus L. (Juncaceae) plants at Waldport, Oregon on October 3, 2011. The bugs were dissected in 1% saline solution and the nematodes killed in 1% Ringers solution and immediately fixed in 5% formalin (at 20°C). Third stage juveniles removed from infected hosts were maintained in 1% saline solution until they matured to the adult stage, molted and mated. Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae) is described from last instar nymphs and adults of the intertidal bug, Saldula laticollis on the Oregon coast. The new genus can be distinguished from other genera in the Allantonematidae by a stylet lacking basal knobs in both sexes, an excretory pore located behind the nerve ring, ribbed spicules, a gubernaculum, the absence of a bursa and the elongate-tubular shape of the ovoviviparous parasitic females. Studies of the organogenesis of Halophilanema showed development to third stage juveniles in the uterus of parasitic females. Maturation to the free-living adults and mating occurred in the environment. The incidence of infection of S. laticollis ranged from 0% to 85% depending on the microhabitat in the intertidal zone. Based on the habitat and morphological characters, it is proposed that Halophilanema adapted a parasitic existence fairly

  5. Modeling rocky coastline evolution and equilibrium

    NASA Astrophysics Data System (ADS)

    Limber, P. W.; Murray, A. B.

    2010-12-01

    headland and sediment-filled bay sequence could persist in the absence of heterogeneous lithology, 2) headland spacing was not autogenic and was a function of the initial coastline shape, and 3) that the proportion of the equilibrium coastline that consisted of headlands (and bays) was analytically predictable and depended on sea cliff height and composition as well as rates of beach erosion and bare-rock sea cliff retreat. In the present contribution we include fluvial sediment sources, alongshore and cross-shore variations in sea cliff height (which, in turn, vary cliff sediment supply in time and space), lithologic heterogeneities, and submarine canyons that extend into the nearshore zone and intercept alongshore sediment transport (similar to the California coastline). These modifications alter the style of rocky coastline evolution and the final equilibrium coastline configuration. We compare numerical and analytical model results to real landscapes, focusing on the California coastline. Overall, we seek to establish simple relationships between physical parameters (sea cliff characteristics, sediment sources and sinks, and wave climate) that can be used to explain why some coastlines exhibit rocky headlands, and how extensive the headlands are (relative to beach-covered stretches).

  6. [Rocky Mountain spotted fever].

    PubMed

    Reinauer, K M; Jaschonek, K; Kusch, G; Heizmann, W R; Döller, P C; Jenss, H

    1990-01-12

    After returning from a holiday in the USA a 24-year-old man fell ill with diarrhoea, high fever and marked rash including the palms of the hands and soles of the feet. When a history of a tick bite in the USA was elicited, a rickettsial infection was suspected. Treatment with doxycycline, 100 mg twice daily, was instituted finally and the fever slowly resolved. The patient became completely well again within four weeks. Serological tests confirmed the diagnosis of Rocky Mountain spotted fever.

  7. Louis Shores and Library History.

    ERIC Educational Resources Information Center

    Shiflett, Lee

    2000-01-01

    Presents a history of the American Library History Round Table of the American Library Association (ALA) and describes the role of Louis Shores in its proceedings. Discusses library history, the position of the Round Table within the ALA, and disseminating research in library history. (LRW)

  8. On Sandy Shores. Teacher's Guide.

    ERIC Educational Resources Information Center

    Strang, Craig; And Others

    The activities in this guide (for grades 2-4) transport students to the sandy shore, one of the most fascinating ecosystems on the planet. At this ecological juncture a multiplicity of life forms find ways to survive, thrive, and interact with each other. Using a wide variety of learning formats, students explore and deepen their understanding of…

  9. On Sandy Shores. Teacher's Guide.

    ERIC Educational Resources Information Center

    Strang, Craig; And Others

    The activities in this guide (for grades 2-4) transport students to the sandy shore, one of the most fascinating ecosystems on the planet. At this ecological juncture a multiplicity of life forms find ways to survive, thrive, and interact with each other. Using a wide variety of learning formats, students explore and deepen their understanding of…

  10. Rainfall Erosion of Intertidal Wetlands

    NASA Astrophysics Data System (ADS)

    Torres, R.

    2007-05-01

    A poorly quantified and mechanistically overlooked material cycling process in estuarine landscapes is rainfall- driven erosion of intertidal salt marsh and mudflat surfaces. During low tide rainsplash erosion and runoff may entrain carbon-rich sediment that, due to high cohesion, ordinarily is not mobilized by tidal currents and shallow water waves (e.g., a deachment limited landscape). Consequently, low tide rainfall may affect tidal creek network structure, creek network extension and nutrient cycling. Field manipulations and passive observations show that low tide rainfall events preferentially entrain highly nutritious intramarsh particulate matter, and in some cases with high concentrations of adsorbed metals. Once mobilized, the subtle topographic variations of the salt marsh landscape route runoff and the suspended load to intertidal creeks, and the subtidal water column. Hence low tide rainfall-runoff processes may enhance the cycling of, for example, benthic microalgae and their products, a primary carbon source for estuarine food webs. Once in the subtidal zone the material may be exported to the coastal ocean or it may be redeposited on the marsh surface with the next high tide, depending on tidal phase. Taken together these observations reveal one facet of salt marsh interactions between landscape structure- biological processes-physical processes.

  11. 46 CFR 183.390 - Shore power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.390 Shore power. A vessel with an electrical system operating at more than 50 volts, which is provided with a means to connect to shore...

  12. Modeling Sediment Bypassing around Rocky Headlands

    NASA Astrophysics Data System (ADS)

    George, D. A.; Largier, J. L.; Pasternack, G. B.; Erikson, L. H.; Storlazzi, C. D.; Barnard, P.

    2016-12-01

    Sediment bypassing rocky headlands remains understudied despite the importance of characterizing littoral processes and sediment budgets for erosion abatement, climate change adaptation, and beach management. This study was developed to identify controlling factors on and the mechanisms supporting sediment bypassing. Sediment flux around four idealized rocky headlands was investigated using the hydrodynamic model Delft3D and spectral wave model SWAN. The experimental design involved 120 simulations to explore the influence of headland morphology, substrate composition, sediment grain size, and oceanographic forcing. Headlands represented sizes and shapes found in natural settings, grain sizes ranged from fine to medium sand, and substrates from sandy beds to offshore bedrock reefs. The oceanography included a constructed representative tide, an alongshore background current, and four wave conditions derived from observational records in the eastern Pacific Ocean. A bypassing ratio was developed for alongshore flux between upstream and downstream cross-shore transects to determine the degree of blockage by a headland. Results showed that northwesterly oblique large waves (Hs = 7 m, Tp = 16 s) generated the most flux around headlands, whereas directly incident waves blocked flux across a headland apex. The headland shape heavily influenced the sediment fate by changing the relative angle between the shoreline and the incident waves. The bypassing ratio characterized each headland's capacity to allow alongshore flux under different wave conditions. All headlands may allow flux, although larger ones block sediment more effectively, promoting their ability to be littoral cell boundaries compared to smaller headlands. The controlling factors on sediment bypassing were determined to be wave angle, shape and size of the headland, and sediment grain size. This novel numerical modeling study advances headland modeling from the generic realm to broadly applicable classes of

  13. 46 CFR 183.390 - Shore power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.390 Shore power. A vessel with an electrical system operating at more than 50 volts, which is provided with a means to connect to shore power... that shore power and the vessel's power sources may not be operated simultaneously....

  14. 46 CFR 129.390 - Shore power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Shore power. 129.390 Section 129.390 Shipping COAST... Power Sources and Distribution Systems § 129.390 Shore power. Each vessel that has an electrical system operating at more than 50 volts and has provisions for receiving shore power must meet the requirements...

  15. 46 CFR 129.390 - Shore power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Shore power. 129.390 Section 129.390 Shipping COAST... Power Sources and Distribution Systems § 129.390 Shore power. Each vessel that has an electrical system operating at more than 50 volts and has provisions for receiving shore power must meet the requirements...

  16. 46 CFR 183.390 - Shore power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Shore power. 183.390 Section 183.390 Shipping COAST...) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.390 Shore power. A vessel with an electrical system operating at more than 50 volts, which is provided with a means to connect to shore...

  17. 46 CFR 183.390 - Shore power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Shore power. 183.390 Section 183.390 Shipping COAST...) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.390 Shore power. A vessel with an electrical system operating at more than 50 volts, which is provided with a means to connect to shore...

  18. 46 CFR 129.390 - Shore power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Shore power. 129.390 Section 129.390 Shipping COAST... Power Sources and Distribution Systems § 129.390 Shore power. Each vessel that has an electrical system operating at more than 50 volts and has provisions for receiving shore power must meet the requirements...

  19. 46 CFR 183.390 - Shore power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Shore power. 183.390 Section 183.390 Shipping COAST...) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.390 Shore power. A vessel with an electrical system operating at more than 50 volts, which is provided with a means to connect to shore...

  20. Morphodynamics of intertidal bars near a seawall on a macrotidal beach, Wissant Bay, northern France

    NASA Astrophysics Data System (ADS)

    Sedrati, M.; Anthony, E.

    2009-04-01

    Several studies on beaches with intertidal bar-trough (ridge-and-runnel) systems in settings with relatively large tidal ranges (> 3 m) have focused on cross-shore bar mobility; however a few recent studies have drawn attention to the potential role of longshore transport induced by a mix of wave-tide and wind-forced longshore currents in the morphodynamics of the bars and troughs. The aim of this paper is to briefly highlight the relationship between wind-forced currents on the shallow intertidal zone and rapid intertidal bar-trough morphological response on a macrotidal beach. Fieldwork was conduced on Wissant beach, Wissant Bay, northern France, from 7 to 23 March, 2006. During the experiment, the beach (oriented NE-SW) exhibited three intertidal bar-trough systems and the upper bar was directly attached to a seawall. Seven digital elevation models (DEMs) were generated from high-resolution topographic surveys. Hydrodynamic measurements were obtained from five currentmeters (2 S4 and 3 ADCP) deployed on the bars crests and on the upper beach trough. Wave characteristics were obtained from the measured time series by spectral analysis using Fast Fourier Transforms. Wind speed and direction on the beach were measured using a portable weather station. The mean wind speed and directions averaged every three hours highlight closely-spaced high-energy events during the experiment, with long phases of significant lateral wind stress (NE to ENE). The measured waves and currents showed rapid and strong response to both the changes in wind speed and direction. Longshore currents measured during the experiment on the upper intertidal bar-trough system showed a clear SW flow pattern in response to NE to ENE wind approach directions while the currents in the lower intertidal zone flowed northeastward during the flood, following the coastline, and southwestward during the ebb in response to the tidal current modulation. Strong longshore migration of the upper intertidal bar

  1. Morphological and molecular analyses of larval trematodes in the intertidal bivalve Perumytilus purpuratus from central Chile.

    PubMed

    Muñoz, G; López, Z; Cárdenas, L

    2013-09-01

    The bivalve Perumytilus purpuratus is a common species that is widely distributed throughout rocky intertidal zones in Chile. This bivalve is the first intermediate host for three trematode species: one bucephalid (an undetermined species) and two fellodistomids (Proctoeces lintoni and one undetermined species). A few studies based on morphological comparisons, experimental infection and molecular analyses have been performed to ascertain the taxon (at least at the family level) to which these trematodes belong; yet, there remains no clarification about the specific identity of these trematodes. Therefore, in this study, we compared the V4 region nucleotide sequences of the 18S rRNA of these three sporocyst species, classified as morphotypes, found in P. purpuratus and nine adult trematode species from intertidal fishes that are likely definitive hosts for these parasites. The sequences from two of the sporocyst morphotypes matched with adult trematodes from the intertidal fish: type 1 sporocyst was similar to Prosorhynchoides carvajali (Bucephalidae), with a mean genetic divergence of 0.78%, and type 2 sporocyst was similar to Proctoeces sp. (but not P. lintoni), with 0% genetic divergence. The third species (type 3 sporocyst) was classified to the family Fellodistomidae; however, the sequence from this species differed greatly from the three other fellodistomid species documented in the marine fish of Chile and from other fellodistomids in public databases. Moreover, this morphotype has a particular cercarial morphology that greatly differs from other fellodistomid species described thus far. Therefore, this intriguing trematode remains a mystery.

  2. High-resolution analysis of metabolic cycles in the intertidal mussel Mytilus californianus.

    PubMed

    Connor, Kwasi M; Gracey, Andrew Y

    2012-01-01

    Inhabitants of the marine rocky intertidal live in an environment that alternates between aquatic and terrestrial due to the rise and fall of the tide. The tide creates a cyclical availability of oxygen with animals having access to oxygenated water during episodes of submergence, while access to oxygen is restricted during aerial emergence. Here we performed liquid chromatography and gas chromatography-mass spectrometry enabled metabolomic profiling of gill samples isolated from the California ribbed mussel, Mytilus californianus, to investigate how metabolism is orchestrated in this variable environment. We created a simulated intertidal environment in which mussels were acclimated to alternating high and low tides of 6 h duration, and samples were taken every 2 h for 72 h to capture reproducible changes in metabolite levels over six high and six low tides. We quantified 169 named metabolites of which 24 metabolites cycled significantly with a 12-h period that was linked to the tidal cycle. These data confirmed the presence of alternating phases of fermentation and aerobic metabolism and highlight a role for carnitine-conjugated metabolites during the anaerobic phase of this cycle. Mussels at low tide accumulated eight carnitine-conjugated metabolites, arising from the degradation of fatty acids, branched-chain amino acids, and mitochondrial β-oxidation end products. The data also implicate sphingosine as a potential signaling molecule during aerial emergence. These findings identify new levels of metabolic control whose role in intertidal adaptation remains to be elucidated.

  3. Giant intertidal hardground polygons of the southern Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Lokier, S. W.; Steuber, T.

    2009-04-01

    This study presents a model for the formation of very large-scale intertidal hardground polygons identified along the southern shore of the Arabian Gulf. These large scale sedimentological features have diameters in excess of 150 m and, although easily visible on aerial and satellite imagery, are difficult to distinguish on the ground. Initial identification was made on the coastline of Abu Dhabi but subsequent investigations have revealed these giant polygons to be common features along much of the southern shoreline of the Arabian Gulf. A quantitative analysis of the polygons was undertaken with integrated field, petrographic and geochemical analysis techniques employed to establish a model for their initial formation and subsequent development. Within this framework we also consider the preservation potential of these features and the limitations for their identification in ancient sedimentological sequences. This study has found that polygon formation takes place through displacive carbonate cementation of carbonate sand below a thin (3 to 5 cm) cover of unconsolidated carbonate sediment. Geochemical analysis of the carbonate cements reveals an oxygen isotopic composition that is consistent with precipitation from evaporated seawater. The uppermost portion of the cemented zone is a relatively poorly consolidated layer that grades downward into an 8 to 14 cm thick, well-cemented bioclastic grainstone. Ongoing cement precipitation results in the outward expansion of polygons, this, in turn, results in uplift, fracturing, and overthrusting at polygon borders. Three distinct categories of polygon border are identified in this study - tepee, gap and overlap borders. Tepee and gap borders were found to be rare in these settings, accounting for less than 3% of all border area. Tepees were found to be transient features in the relatively high-energy setting of the intertidal zone, being destroyed during high-energy events, such as storms, or collapsing due to a lack of

  4. Rocky Mountain spotted fever.

    PubMed

    Dantas-Torres, Filipe

    2007-11-01

    Rocky Mountain spotted fever (RMSF) is a life-threatening disease caused by Rickettsia rickettsii, an obligately intracellular bacterium that is spread to human beings by ticks. More than a century after its first clinical description, this disease is still among the most virulent human infections identified, being potentially fatal even in previously healthy young people. The diagnosis of RMSF is based on the patient's history and a physical examination, and often presents a dilemma for clinicians because of the non-specific presentation of the disease in its early course. Early empirical treatment is essential to prevent severe complications or a fatal outcome, and treatment should be initiated even in unconfirmed cases. Because there is no vaccine available against RMSF, avoidance of tick-infested areas is still the best way to prevent the infection.

  5. The bioaccumulation of polynuclear aromatic hydrocarbons by benthic invertebrates in an intertidal marsh

    SciTech Connect

    Maruya, K.A.; Risebrough, R.W.; Horne, A.J.

    1997-06-01

    Biota-sediment accumulation factors (BSAF; concentration in organism lipid/concentration in sediment on an organic carbon basis) of polyaromatic hydrocarbons varied with season and along an intertidal gradient in a coastal marsh in San Francisco Bay. The BSAFs were lowest during the local rainy season. During the dry season, BSAFs were lowest in the high intertidal zone closest to shore. Significant differences among species groups were also observed; BSAFs were lowest in polychaetes and highest in the Asian clam (Potamocorbula amurensis), varying over almost three orders of magnitude. The BSAFs decreased with increasing percent fines in the sediments and with PAH concentrations on an organic carbon basis. The authors suggest that a determining variable is the content of highly aromatic soot particles, which increases during periods of surface runoff and which is expected in the dry season to be highest in the high intertidal zone where these finer particles preferentially accumulate. Correlations of BSAFs with the ratio of the logarithm of the activity coefficients in porewaters to those in sediments were generally stronger than with log K{sub ow}, indicating a limitation of octanol as a surrogate for sediment organic carbon or organism lipid. These observations qualify but also strengthen the concept of equilibrium partitioning as the determining factor in bioaccumulation by benthic organisms of nonpolar organic compounds for sediments; the assumption that organic carbon can be considered in generic terms without allowance for aromaticity and probably other factors as well, must, however, be reconsidered.

  6. Rocky Mountain Snow

    NASA Image and Video Library

    2017-09-27

    NASA image acquired December 19, 2012 In time for the 2012 winter solstice, a storm dropped snow over most of the Rocky Mountains in the United States. On December 20, the National Weather Service reported snow depths exceeding 100 centimeters (39 inches) in some places—the result of the recent snowfall plus accumulation from earlier storms. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this natural-color image on December 19, 2012. Clouds had mostly cleared from the region, though some cloud cover lingered over parts of the Pacific Northwest and Colorado. Showing more distinct contours than the clouds, the snow cover stretched across the Rocky Mountains and the surrounding region, from Idaho to Arizona and from California to Colorado. Snowfall did not stop in Colorado, as the storm continued moving eastward across the Midwest. By December 20, 2012, a combination of heavy snow and strong winds had closed schools, iced roads, and delayed flights, complicating plans for holiday travelers. Though troublesome for travel, the snow brought much-needed moisture; multiple cities had set new records for consecutive days without measurable snow, CBS news reported. As of December 18, the U.S. Drought Monitor stated that a substantial portion of the continental United States continued to suffer from drought, and “exceptional” drought conditions extended from South Dakota to southern Texas. NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response. Caption by Michon Scott. Instrument: Aqua - MODIS To read more go to: earthobservatory.nasa.gov/IOTD/view.php?id=80035 Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission

  7. Hot, Rocky World Artist Concept

    NASA Image and Video Library

    2015-07-30

    This artist's rendition shows one possible appearance for the planet HD 219134b, the nearest confirmed rocky exoplanet found to date outside our solar system. The planet is 1.6 times the size of Earth, and whips around its star in just three days. Scientists predict that the scorching-hot planet -- known to be rocky through measurements of its mass and size -- would have a rocky, partially molten surface with geological activity, including possibly volcanoes. http://photojournal.jpl.nasa.gov/catalog/PIA19833

  8. 75 FR 30052 - Nomans Land Island National Wildlife Refuge, Town of Chilmark, MA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-28

    ... provides diverse habitats that include intertidal, freshwater wetland, grassland and shrubland habitats... concern. We would continue to maintain the 15 acres of herbaceous upland and 100 acres of intertidal beach... marine intertidal beach and rocky shore habitats to benefit marine mammals and nesting and...

  9. Rocky Mountain Arsenal NPDES Permit

    EPA Pesticide Factsheets

    Under NPDES permit CO-0035009, the U.S. Department of Interior's Fish and Wildlife Service is authorized to discharge from the Rocky Mountain Arsenal recycled water pipeline to Lower Derby Lake in Adams County, Colo.

  10. Macroscale patterns in body size of intertidal crustaceans provide insights on climate change effects.

    PubMed

    Jaramillo, Eduardo; Dugan, Jenifer E; Hubbard, David M; Contreras, Heraldo; Duarte, Cristian; Acuña, Emilio; Schoeman, David S

    2017-01-01

    Predicting responses of coastal ecosystems to altered sea surface temperatures (SST) associated with global climate change, requires knowledge of demographic responses of individual species. Body size is an excellent metric because it scales strongly with growth and fecundity for many ectotherms. These attributes can underpin demographic as well as community and ecosystem level processes, providing valuable insights for responses of vulnerable coastal ecosystems to changing climate. We investigated contemporary macroscale patterns in body size among widely distributed crustaceans that comprise the majority of intertidal abundance and biomass of sandy beach ecosystems of the eastern Pacific coasts of Chile and California, USA. We focused on ecologically important species representing different tidal zones, trophic guilds and developmental modes, including a high-shore macroalga-consuming talitrid amphipod (Orchestoidea tuberculata), two mid-shore scavenging cirolanid isopods (Excirolana braziliensis and E. hirsuticauda), and a low-shore suspension-feeding hippid crab (Emerita analoga) with an amphitropical distribution. Significant latitudinal patterns in body sizes were observed for all species in Chile (21° - 42°S), with similar but steeper patterns in Emerita analoga, in California (32°- 41°N). Sea surface temperature was a strong predictor of body size (-4% to -35% °C-1) in all species. Beach characteristics were subsidiary predictors of body size. Alterations in ocean temperatures of even a few degrees associated with global climate change are likely to affect body sizes of important intertidal ectotherms, with consequences for population demography, life history, community structure, trophic interactions, food-webs, and indirect effects such as ecosystem function. The consistency of results for body size and temperature across species with different life histories, feeding modes, ecological roles, and microhabitats inhabiting a single widespread coastal

  11. Macroscale patterns in body size of intertidal crustaceans provide insights on climate change effects

    PubMed Central

    Dugan, Jenifer E.; Hubbard, David M.; Contreras, Heraldo; Duarte, Cristian; Acuña, Emilio; Schoeman, David S.

    2017-01-01

    Predicting responses of coastal ecosystems to altered sea surface temperatures (SST) associated with global climate change, requires knowledge of demographic responses of individual species. Body size is an excellent metric because it scales strongly with growth and fecundity for many ectotherms. These attributes can underpin demographic as well as community and ecosystem level processes, providing valuable insights for responses of vulnerable coastal ecosystems to changing climate. We investigated contemporary macroscale patterns in body size among widely distributed crustaceans that comprise the majority of intertidal abundance and biomass of sandy beach ecosystems of the eastern Pacific coasts of Chile and California, USA. We focused on ecologically important species representing different tidal zones, trophic guilds and developmental modes, including a high-shore macroalga-consuming talitrid amphipod (Orchestoidea tuberculata), two mid-shore scavenging cirolanid isopods (Excirolana braziliensis and E. hirsuticauda), and a low-shore suspension-feeding hippid crab (Emerita analoga) with an amphitropical distribution. Significant latitudinal patterns in body sizes were observed for all species in Chile (21° - 42°S), with similar but steeper patterns in Emerita analoga, in California (32°- 41°N). Sea surface temperature was a strong predictor of body size (-4% to -35% °C-1) in all species. Beach characteristics were subsidiary predictors of body size. Alterations in ocean temperatures of even a few degrees associated with global climate change are likely to affect body sizes of important intertidal ectotherms, with consequences for population demography, life history, community structure, trophic interactions, food-webs, and indirect effects such as ecosystem function. The consistency of results for body size and temperature across species with different life histories, feeding modes, ecological roles, and microhabitats inhabiting a single widespread coastal

  12. Rocky Martian Plain

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The rocky Martian plain surrounding Viking 2 is seen in high resolution in this 85-degree panorama sweeping from north at the left to east at right during the Martian afternoon on September 5. Large blocks litter the surface. Some are porous, sponge-like rocks like the one at the left edge (size estimate: 1 1/2 to 2 feet); others are dense and fine-grained, such as the very bright rounded block (1 to 1 1/2 feet across) toward lower right. Pebbled surface between the rocks is covered in places by small drifts of very fine material similar to drifts seen at the Viking 1 landing site some 4600 miles to the southwest. The fine-grained material is banked up behind some rocks, but wind tails seen by Viking 1 are not well-developed here. On the right horizon, flat-topped ridges or hills are illuminated by the afternoon sun. Slope of the horizon is due to the 8-degree tilt of the spacecraft.

  13. Rocky Martian Plain

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The rocky Martian plain surrounding Viking 2 is seen in high resolution in this 85-degree panorama sweeping from north at the left to east at right during the Martian afternoon on September 5. Large blocks litter the surface. Some are porous, sponge-like rocks like the one at the left edge (size estimate: 1 1/2 to 2 feet); others are dense and fine-grained, such as the very bright rounded block (1 to 1 1/2 feet across) toward lower right. Pebbled surface between the rocks is covered in places by small drifts of very fine material similar to drifts seen at the Viking 1 landing site some 4600 miles to the southwest. The fine-grained material is banked up behind some rocks, but wind tails seen by Viking 1 are not well-developed here. On the right horizon, flat-topped ridges or hills are illuminated by the afternoon sun. Slope of the horizon is due to the 8-degree tilt of the spacecraft.

  14. Drought in the Rockies

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image shows the difference between the amount of vegetation in July 2000 and the average July vegetation for North America. Of particular interest are the dry conditions in the western United States. This spring and summer the Rocky Mountains have been relatively dry, and the brown regions stretching from the Canadian to the Mexican border, indicate the effect on the regions' forests. Western Montana and eastern Idaho are particularly parched, and appear darker brown. The dry conditions have contributed to this year's devastating fire season, during which millions of acres have burned in the west. Scientists find that during the growing season, land plants can be used to measure drought. Healthy, thriving plants reflect and absorb visible and near-infrared light differently than plants under stress. These variations in reflectance and absorption can be measured by satellites to produce maps of healthy and stressed vegetation. This image shows Normalized Difference Vegetation Index (NDVI) anomaly, which indicates where vegetation growth was above average (green pixels), below average (brown pixels), or normal (white pixels). For more images and information about measuring vegetation and drought from space visit: Drought and Vegetation Monitoring. Image courtesy NASA Goddard Space Flight Center Biospheric Sciences Branch, based on data from NOAA.

  15. Drought in the Rockies

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image shows the difference between the amount of vegetation in July 2000 and the average July vegetation for North America. Of particular interest are the dry conditions in the western United States. This spring and summer the Rocky Mountains have been relatively dry, and the brown regions stretching from the Canadian to the Mexican border, indicate the effect on the regions' forests. Western Montana and eastern Idaho are particularly parched, and appear darker brown. The dry conditions have contributed to this year's devastating fire season, during which millions of acres have burned in the west. Scientists find that during the growing season, land plants can be used to measure drought. Healthy, thriving plants reflect and absorb visible and near-infrared light differently than plants under stress. These variations in reflectance and absorption can be measured by satellites to produce maps of healthy and stressed vegetation. This image shows Normalized Difference Vegetation Index (NDVI) anomaly, which indicates where vegetation growth was above average (green pixels), below average (brown pixels), or normal (white pixels). For more images and information about measuring vegetation and drought from space visit: Drought and Vegetation Monitoring. Image courtesy NASA Goddard Space Flight Center Biospheric Sciences Branch, based on data from NOAA.

  16. Rocky road in the Rockies: Challenges to biodiversity

    USGS Publications Warehouse

    Tomback, Diana F.; Kendall, Katherine C.

    2002-01-01

    To people worldwide, the Rocky Mountains of the United States and Canada represent a last bastion of nature in its purest and rawest form-unspoiled forests teeming with elk and deer stalked by mountain lions and grizzly bears; bald eagles nesting near lakes and rivers; fat, feisty native trout in rushing mountain streams; and dazzling arrays of wildflowers in lush meadows. In fact, the total biodiversity of the Rocky Mountains is considerable, with relatively high diversity in birds, mammals, butterflies, reptiles, and conifers (Ricketts et al. 1999) and with geographic variation in the flora and fauna of alpine, forest, foothill, and adjacent shortgrass prairie and shrub communities over more than 20 degrees of latitude and more than 10' of longitude. Although the biodiversity of most North American regions has declined because of anthropogenic influences, the perception remains that the biodiversity of the Rocky Mountains is intact. This view exists in part because the Rocky Mountains are remote from urban centers, in part because so much of the land comprises protected areas such as national parks and wilderness areas, and in part because of wishful thinking-that nothing bad could happen to the biodiversity that is so much a part of the history, national self-image, legends, nature films, and movies of the United States and Canada. Despite modern technology and the homogenization and globalization of their cities and towns, at heart North Americans still regard their land as the New World, with pristine nature and untamed landscapes epitomized by the Rockies. The reality is that the biodiversity of the Rocky Mountains has not been free of anthropogenic influences since the West was settled in the 1800s, and in fact it was altered by Native Americans for centuries prior to settlement. A number of escalating problems and consequences of management choices are currently changing Rocky Mountain ecological communities at a dizzying pace. In Order to maintain some

  17. Adaptive Traits Are Maintained on Steep Selective Gradients despite Gene Flow and Hybridization in the Intertidal Zone

    PubMed Central

    Canovas, Fernando; Ferreira Costa, Joana; Serrão, Ester A.; Pearson, Gareth A.

    2011-01-01

    Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong gradients may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure gradients despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along vertical exposure gradients in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia) population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal) was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective vertical distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure gradients acts to maintain

  18. Adaptive traits are maintained on steep selective gradients despite gene flow and hybridization in the intertidal zone.

    PubMed

    Zardi, Gerardo I; Nicastro, Katy R; Canovas, Fernando; Costa, Joana Ferreira; Serrão, Ester A; Pearson, Gareth A

    2011-01-01

    Gene flow among hybridizing species with incomplete reproductive barriers blurs species boundaries, while selection under heterogeneous local ecological conditions or along strong gradients may counteract this tendency. Congeneric, externally-fertilizing fucoid brown algae occur as distinct morphotypes along intertidal exposure gradients despite gene flow. Combining analyses of genetic and phenotypic traits, we investigate the potential for physiological resilience to emersion stressors to act as an isolating mechanism in the face of gene flow. Along vertical exposure gradients in the intertidal zone of Northern Portugal and Northwest France, the mid-low shore species Fucus vesiculosus, the upper shore species Fucus spiralis, and an intermediate distinctive morphotype of F. spiralis var. platycarpus were morphologically characterized. Two diagnostic microsatellite loci recovered 3 genetic clusters consistent with prior morphological assignment. Phylogenetic analysis based on single nucleotide polymorphisms in 14 protein coding regions unambiguously resolved 3 clades; sympatric F. vesiculosus, F. spiralis, and the allopatric (in southern Iberia) population of F. spiralis var. platycarpus. In contrast, the sympatric F. spiralis var. platycarpus (from Northern Portugal) was distributed across the 3 clades, strongly suggesting hybridization/introgression with both other entities. Common garden experiments showed that physiological resilience following exposure to desiccation/heat stress differed significantly between the 3 sympatric genetic taxa; consistent with their respective vertical distribution on steep environmental clines in exposure time. Phylogenetic analyses indicate that F. spiralis var. platycarpus is a distinct entity in allopatry, but that extensive gene flow occurs with both higher and lower shore species in sympatry. Experimental results suggest that strong selection on physiological traits across steep intertidal exposure gradients acts to maintain

  19. Ship2Shore Marine Educators

    NASA Astrophysics Data System (ADS)

    Ewing, N. R.; Sen, G.; Doehler, S.

    2012-12-01

    The Ocean Networks Canada (ONC) Observatory, comprised of VENUS and NEPTUNE Canada (NC) cabled networks, supports transformative coastal to deep ocean research and enables real-time interactive experiments. Engaging students, educators and the public is critical to increasing the global awareness of our integral relationship with the ocean. One way to accomplish this is to encourage educators to incorporate marine science concepts into their lesson plans. ONC's new initiative, Ship2Shore Marine Educators (S2SME), enables educators to learn first hand about marine science and technology by going to sea on a maintenance/research cruise. While at sea Marine Educators (ME) participate in technology deployments, assist with water and core sampling, write daily blogs, produce short video updates, develop learning resources and conduct presentations to students on shore via video conferencing. MEs participating in the last NC cruise -"Wiring the Abyss 2012" - were fascinated with being a part of science in the real world. They had an experience of a lifetime and anticipate incorporating what they have learned into their lessons during the upcoming semester. Outreach between the MEs and ONC communication staff aboard the ship resulted in nearly 7,000 unique visitors to the "Wiring the Abyss 2012'' cruise website. Live ROPOS video feeds (~ 9,000 views), highlight videos (436 views/day), daily blogs (~1200 views) and stunning images (~391 views/day) were among the top rated pages. Visitors from 10 countries tuned in to "Wiring the Abyss 2012" and experienced the Pacific's deep sea! One of the best experiences for the MEs was connecting with students and teachers on shore via video conferencing. Roughly 300 students in BC and USA received a live connection from approximately 200km off the west coast. Students were most fascinated by a demo involving compressed Styrofoam cups, showing the intensity of pressure at the bottom of the sea. Successes: A positive working

  20. Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season

    PubMed Central

    Warwick-Evans, Victoria C.; Atkinson, Philip W.; Robinson, Leonie A.; Green, Jonathan A.

    2016-01-01

    During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney’s coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney’s seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making. PMID:27031616

  1. Predictive Modelling to Identify Near-Shore, Fine-Scale Seabird Distributions during the Breeding Season.

    PubMed

    Warwick-Evans, Victoria C; Atkinson, Philip W; Robinson, Leonie A; Green, Jonathan A

    2016-01-01

    During the breeding season seabirds are constrained to coastal areas and are restricted in their movements, spending much of their time in near-shore waters either loafing or foraging. However, in using these areas they may be threatened by anthropogenic activities such as fishing, watersports and coastal developments including marine renewable energy installations. Although many studies describe large scale interactions between seabirds and the environment, the drivers behind near-shore, fine-scale distributions are not well understood. For example, Alderney is an important breeding ground for many species of seabird and has a diversity of human uses of the marine environment, thus providing an ideal location to investigate the near-shore fine-scale interactions between seabirds and the environment. We used vantage point observations of seabird distribution, collected during the 2013 breeding season in order to identify and quantify some of the environmental variables affecting the near-shore, fine-scale distribution of seabirds in Alderney's coastal waters. We validate the models with observation data collected in 2014 and show that water depth, distance to the intertidal zone, and distance to the nearest seabird nest are key predictors in the distribution of Alderney's seabirds. AUC values for each species suggest that these models perform well, although the model for shags performed better than those for auks and gulls. While further unexplained underlying localised variation in the environmental conditions will undoubtedly effect the fine-scale distribution of seabirds in near-shore waters we demonstrate the potential of this approach in marine planning and decision making.

  2. Microbial biofilms in intertidal systems: an overview

    NASA Astrophysics Data System (ADS)

    Decho, Alan W.

    2000-07-01

    Intertidal marine systems are highly dynamic systems which are characterized by periodic fluctuations in environmental parameters. Microbial processes play critical roles in the remineralization of nutrients and primary production in intertidal systems. Many of the geochemical and biological processes which are mediated by microorganisms occur within microenvironments which can be measured over micrometer spatial scales. These processes are localized by cells within a matrix of extracellular polymeric secretions (EPS), collectively called a "microbial biofilm". Recent examinations of intertidal systems by a range of investigators using new approaches show an abundance of biofilm communities. The purpose of this overview is to examine recent information concerning the roles of microbial biofilms in intertidal systems. The microbial biofilm is a common adaptation of natural bacteria and other microorganisms. In the fluctuating environments of intertidal systems, biofilms form protective microenvironments and may structure a range of microbial processes. The EPS matrix of biofilm forms sticky coatings on individual sediment particles and detrital surfaces, which act as a stabilizing anchor to buffer cells and their extracellular processes during the frequent physical stresses (e.g., changes in salinity and temperature, UV irradiation, dessication). EPS is an operational definition designed to encompass a range of large microbially-secreted molecules having widely varying physical and chemical properties, and a range of biological roles. Examinations of EPS using Raman and Fourier-transform infared spectroscopy, and atomic-force microscopy suggest that some EPS gels possess physical and chemical properties which may hasten the development of sharp geochemical gradients, and contribute a protective effect to cells. Biofilm polymers act as a sorptive sponge which binds and concentrates organic molecules and ions close to cells. Concurrently, the EPS appear to localize

  3. Estimating variation in surface emissivities of intertidal macroalgae using an infrared thermometer and the effects on temperature measurements.

    PubMed

    Van Alstyne, Kathryn L; Olson, Theresa K

    2014-01-01

    Accurate measurements of surface temperatures with an infrared (IR) thermometer require input of the emissivities of the surfaces being measured; however, few determinations of the emissivities of intertidal organisms' surfaces have been made. Emissivities of intertidal macroalgae were measured to determine whether algal species, measurement angle, hydration, and layering affected them. Emissivities were similar and averaged 0.94 among 11 of 13 species. The species with lower and more variable emissivities (Chondracanthus exasperatus and Desmarestia viridis) differed in morphology from the other species, which were relatively flat thin blades with little surface texture. Measurement angle caused emissivities to decrease significantly in Mazzaella splendens but not in three other species. Hydration and layering of Ulva lactuca also had no effect. At 22 °C, measured temperatures were within 1 °C of actual temperatures when thermometer emissivity settings ranged from 0.75 to 1.00. When emissivities were set lower than actual values, measured temperatures were lower than actual temperatures at 15 °C and higher than actual temperatures at 60 °C. When the IR thermometer was used to measure surface temperatures of nine species of intertidal algae immediately before they were inundated by the incoming tide, temperatures were higher in mid intertidal than low intertidal individuals and higher on a sunnier day than an overcast day. Temperatures of U. lactuca increased with increasing height on the shore, but temperatures of Ulvaria obscura did not. Temperatures were also higher in Fucus distichus blades than receptacles, and lower in U. lactuca and M. splendens occurring in the lower layers of stacks of algae.

  4. 46 CFR 120.390 - Shore power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Shore power. 120.390 Section 120.390 Shipping COAST... PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 120.390 Shore power. A vessel with an electrical system operating at...

  5. 46 CFR 129.390 - Shore power.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Power Sources and Distribution Systems § 129.390 Shore power. Each vessel that has an electrical system operating at more than 50 volts and has provisions for receiving shore power must meet the requirements of...'s switchboard simultaneously, except in cases where system devices permit safe momentary...

  6. 46 CFR 120.390 - Shore power.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Shore power. 120.390 Section 120.390 Shipping COAST... PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 120.390 Shore power. A vessel with an electrical system operating at...

  7. 46 CFR 120.390 - Shore power.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Shore power. 120.390 Section 120.390 Shipping COAST... PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 120.390 Shore power. A vessel with an electrical system operating at...

  8. 46 CFR 120.390 - Shore power.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Shore power. 120.390 Section 120.390 Shipping COAST... PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 120.390 Shore power. A vessel with an electrical system operating at...

  9. 46 CFR 120.390 - Shore power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Shore power. 120.390 Section 120.390 Shipping COAST... PASSENGERS OR WITH OVERNIGHT ACCOMMODATIONS FOR MORE THAN 49 PASSENGERS ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 120.390 Shore power. A vessel with an electrical system operating at...

  10. 46 CFR 129.390 - Shore power.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Shore power. 129.390 Section 129.390 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.390 Shore power. Each vessel that has an electrical...

  11. The Rocky Planet Survey

    NASA Astrophysics Data System (ADS)

    Fischer, Debra

    In direct support of the NASA Origins program, we propose the Rocky Planet Survey, a high cadence exoplanet search of sixty late G and K dwarf stars using the CHIRON spectrometer, which we built and commissioned at CTIO. CHIRON operates in two high- resolution modes (R=90,000 and R=120,000) and has a demonstrated precision of better than 1 m s-1. We are contributing 200 nights of telescope time for the next three years, for the excellent phase coverage needed to carry out this work. We have developed simulation software to optimize scheduling of observations to suppress aliases and quickly extract dynamical signals. Our science objectives are to (1) provide a statistical assessment of planet occurrence as a function of decreasing mass in the range of parameter space 3 < Msini < 30 MEARTH for orbital periods up to 50 days, (2) to determine the fraction of low mass planets in multi-planet architectures, and (3) detect planets with Msini < 3 MEARTH in orbital periods shorter than ~20 days. In addition to the science objectives, we intend to push the frontiers of extreme precision Doppler measurements to keep the U.S. competitive with the next generation of European Doppler spectroscopy (ESPRESSO on the VLT). Our team has significant expertise in optical design, fiber coupling, raw extraction, barycentric velocity corrections, and Doppler analysis. The proposed work includes a new optimal extraction algorithm, with the optical designers and software engineers working together on the 2-D PSF description needed for a proper row-by-row extraction and calibration. We will also develop and test upgrades to the barycentric correction code and improvements in the Doppler code that take advantage of stability in the dispersion solution, afforded by a new vacuum-enclosed grating upgrade (scheduled for November 2011). We will test use of emission wavelength calibrations to extend the iodine (absorption) wavelength calibration that we currently use to prepare for eventual use of

  12. 27 CFR 9.43 - Rocky Knob.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rocky Knob. 9.43 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.43 Rocky Knob. (a) Name. The name of the viticultural area described in this section is “Rocky Knob.” (b) Approved maps...

  13. 27 CFR 9.43 - Rocky Knob.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Rocky Knob. 9.43 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.43 Rocky Knob. (a) Name. The name of the viticultural area described in this section is “Rocky Knob.” (b) Approved maps...

  14. 27 CFR 9.43 - Rocky Knob.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Rocky Knob. 9.43 Section 9... TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.43 Rocky Knob. (a) Name. The name of the viticultural area described in this section is “Rocky Knob.” (b) Approved maps...

  15. 27 CFR 9.43 - Rocky Knob.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Rocky Knob. 9.43 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.43 Rocky Knob. (a) Name. The name of the viticultural area described in this section is “Rocky Knob.” (b) Approved maps...

  16. 27 CFR 9.43 - Rocky Knob.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Rocky Knob. 9.43 Section 9... TREASURY ALCOHOL AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.43 Rocky Knob. (a) Name. The name of the viticultural area described in this section is “Rocky Knob.” (b) Approved maps...

  17. Linking Intertidal and Subtidal Food Webs: Consumer-Mediated Transport of Intertidal Benthic Microalgal Carbon.

    PubMed

    Kang, Chang-Keun; Park, Hyun Je; Choy, Eun Jung; Choi, Kwang-Sik; Hwang, Kangseok; Kim, Jong-Bin

    2015-01-01

    We examined stable carbon and nitrogen isotope ratios for a large variety of consumers in intertidal and subtidal habitats, and their potential primary food sources [i.e., microphytobenthos (MPB), phytoplankton, and Phragmites australis] in a coastal bay system, Yeoja Bay of Korea, to test the hypothesis that the transfer of intertidal MPB-derived organic carbon to the subtidal food web can be mediated by motile consumers. Compared to a narrow δ13C range (-18 to -16‰) of offshore consumers, a broad δ13C range (-18 to -12‰) of both intertidal and subtidal consumers indicated that 13C-enriched sources of organic matter are an important trophic source to coastal consumers. In the intertidal areas, δ13C of most consumers overlapped with or was 13C-enriched relative to MPB. Despite the scarcity of MPB in the subtidal, highly motile consumers in subtidal habitat had nearly identical δ13C range with many intertidal foragers (including crustaceans and fish), overlapping with the range of MPB. In contrast, δ13C values of many sedentary benthic invertebrates in the subtidal areas were similar to those of offshore consumers and more 13C-depleted than motile foragers, indicating high dependence on phytoplankton-derived carbon. The isotopic mixing model calculation confirms that the majority of motile consumers and also some of subtidal sedentary ones depend on intertidal MPB for more than a half of their tissue carbon. Finally, although further quantitative estimates are needed, these results suggest that direct foraging by motile consumers on intertidal areas, and thereby biological transport of MPB-derived organic carbon to the subtidal areas, may provide important trophic connection between intertidal production and the nearshore shallow subtidal food webs.

  18. Linking Intertidal and Subtidal Food Webs: Consumer-Mediated Transport of Intertidal Benthic Microalgal Carbon

    PubMed Central

    Kang, Chang-Keun; Park, Hyun Je; Choy, Eun Jung; Choi, Kwang-Sik; Hwang, Kangseok; Kim, Jong-Bin

    2015-01-01

    We examined stable carbon and nitrogen isotope ratios for a large variety of consumers in intertidal and subtidal habitats, and their potential primary food sources [i.e., microphytobenthos (MPB), phytoplankton, and Phragmites australis] in a coastal bay system, Yeoja Bay of Korea, to test the hypothesis that the transfer of intertidal MPB-derived organic carbon to the subtidal food web can be mediated by motile consumers. Compared to a narrow δ13C range (−18 to −16‰) of offshore consumers, a broad δ13C range (−18 to −12‰) of both intertidal and subtidal consumers indicated that 13C-enriched sources of organic matter are an important trophic source to coastal consumers. In the intertidal areas, δ13C of most consumers overlapped with or was 13C-enriched relative to MPB. Despite the scarcity of MPB in the subtidal, highly motile consumers in subtidal habitat had nearly identical δ13C range with many intertidal foragers (including crustaceans and fish), overlapping with the range of MPB. In contrast, δ13C values of many sedentary benthic invertebrates in the subtidal areas were similar to those of offshore consumers and more 13C-depleted than motile foragers, indicating high dependence on phytoplankton-derived carbon. The isotopic mixing model calculation confirms that the majority of motile consumers and also some of subtidal sedentary ones depend on intertidal MPB for more than a half of their tissue carbon. Finally, although further quantitative estimates are needed, these results suggest that direct foraging by motile consumers on intertidal areas, and thereby biological transport of MPB-derived organic carbon to the subtidal areas, may provide important trophic connection between intertidal production and the nearshore shallow subtidal food webs. PMID:26448137

  19. Trematodes indicate animal biodiversity in the chilean intertidal and Lake Tanganyika

    USGS Publications Warehouse

    Hechinger, R.F.; Lafferty, K.D.; Kuris, A.M.

    2008-01-01

    Trematode communities in populations of estuarine snails can reflect surrounding animal diversity, abundance, and trophic interactions. We know less about the potential for trematodes to serve as bioindicators in other habitats. Here, we reanalyze data from 2 published studies concerning trematodes, 1 in the Chilean rocky intertidal zone and the other from the East African rift lake, Lake Tanganyika. Our analyses indicate that trematodes are more common in protected areas and that in both habitats they are directly and positively related to surrounding host abundance. This further supports the notion that trematodes in first intermediate hosts can serve as bioindicators of the condition of free-living animal communities in diverse ecosystems. ?? American Society of Parasitologists 2008.

  20. Oxidative stress tolerance in intertidal red seaweed Hypnea musciformis (Wulfen) in relation to environmental components.

    PubMed

    Maharana, Dusmant; Das, Priya Brata; Verlecar, Xivanand N; Pise, Navnath M; Gauns, Manguesh

    2015-12-01

    Oxidative stress parameters in relation to temperature and other factors have been analysed in Hypnea musciformis, the red seaweed from Anjuna beach, Goa, with an aim to understand its susceptibility to the changing seasons. The results indicate that elevated temperature, sunshine and dessication during peak summer in May enhanced the activity of lipid peroxide, hydrogen peroxide and antioxidants such as catalase, glutathione and ascorbic acid. Statistical tests using multivariate analysis of variance and correlation analysis showed that oxidative stress and antioxidants maintain significant relation with temperature, salinity, sunshine and pH at an individual or interactive level. The dissolved nitrates, phosphates and biological oxygen demand in ambient waters and the trace metals in seaweeds maintained sufficiently low values to provide any indication that could exert contaminant oxidative stress responses. The present field studies suggest that elevated antioxidant content in H. musciformis offer sufficient relief to sustain against harsh environmental stresses for its colonization in the rocky intertidal zone.

  1. The vertical distribution and abundance of gastropods and bivalves from rocky beaches of Cuastecomate Bay, Jalisco, México.

    PubMed

    Esqueda, M C; Ríos-Jara, E; Michel-Morfín, J E; Landa-Jaime, V

    2000-12-01

    The vertical distribution and abundance of conspicuous gastropod and bivalve species were studied at five rocky beaches in Cuastecomate Bay, Jalisco. Sampling was done from September, 1993 through March, 1994 with 0.75 m2 quadrants placed along replicate transect lines (10 m long) in the supralittoral and mesolittoral (upper, middle and lower intertidal) zones. A total of 6,643 mollusks were collected. Gastropods dominated the samples (6,272 individuals, 44 species); the bivalves were less abundant and diverse (371 individuals, five species). Seventeen species comprised 89.8% of all individuals collected. The gastropods Nodilittorina aspera and Nerita scabricosta were the most abundant with 637.8 and 71.43 individuals/m2, respectively. The most abundant bivalves were Brachidontes adamsianus and Chloromytilus palliopunctatus with 60.7 and 61.3 individuals/m2 respectively. The abundance of gastropods decreased from the supralittoral to the lower tidal zones while the number of species increased in the same direction. The number of species of bivalves also increased from the supralittoral to the lower intertidal zone; the abundance of individuals was higher at the middle intertidal zone. Affinities between groups of species among sampling stations were identified by computing Pearson's correlation coefficient using abundance values (ind./m2) and Jaccard's dissimilarity index using species presence or absence in the lower intertidal zone. Affinity among stations was not dependent upon their vicinity but on the high dominance of few species, the occurrence of many secondary species and beach characteristics.

  2. Large-Scale Spatial Distribution Patterns of Echinoderms in Nearshore Rocky Habitats

    PubMed Central

    Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

    2010-01-01

    This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1–5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m2 quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m−2. In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m2 quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m−2. Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a

  3. Large-scale spatial distribution patterns of echinoderms in nearshore rocky habitats.

    PubMed

    Iken, Katrin; Konar, Brenda; Benedetti-Cecchi, Lisandro; Cruz-Motta, Juan José; Knowlton, Ann; Pohle, Gerhard; Mead, Angela; Miloslavich, Patricia; Wong, Melisa; Trott, Thomas; Mieszkowska, Nova; Riosmena-Rodriguez, Rafael; Airoldi, Laura; Kimani, Edward; Shirayama, Yoshihisa; Fraschetti, Simonetta; Ortiz-Touzet, Manuel; Silva, Angelica

    2010-11-05

    This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m(2) quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m(-2). In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m(2) quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m(-2). Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by

  4. Moving beyond linear food chains: trait-mediated indirect interactions in a rocky intertidal food web.

    PubMed

    Trussell, Geoffrey C; Matassa, Catherine M; Ewanchuk, Patrick J

    2017-03-29

    In simple, linear food chains, top predators can have positive indirect effects on basal resources by causing changes in the traits (e.g. behaviour, feeding rates) of intermediate consumers. Although less is known about trait-mediated indirect interactions (TMIIs) in more complex food webs, it has been suggested that such complexity dampens trophic cascades. We examined TMIIs between a predatory crab (Carcinus maenas) and two ecologically important basal resources, fucoid algae (Ascophyllum nodosum) and barnacles (Semibalanus balanoides), which are consumed by herbivorous (Littorina littorea) and carnivorous (Nucella lapillus) snails, respectively. Because crab predation risk suppresses snail feeding rates, we hypothesized that crabs would also shape direct and indirect interactions among the multiple consumers and resources. We found that the magnitude of TMIIs between the crab and each resource depended on the suite of intermediate consumers present in the food web. Carnivorous snails (Nucella) transmitted TMIIs between crabs and barnacles. However, crab-algae TMIIs were transmitted by both herbivorous (Littorina) and carnivorous (Nucella) snails, and these TMIIs were additive. By causing Nucella to consume fewer barnacles, crab predation risk allowed fucoids that had settled on or between barnacles to remain in the community. Hence, positive interactions between barnacles and algae caused crab-algae TMIIs to be strongest when both consumers were present. Studies of TMIIs in more realistic, reticulate food webs will be necessary for a more complete understanding of how predation risk shapes community dynamics. © 2017 The Author(s).

  5. Rocky Mountain spotted fever, Colombia.

    PubMed

    Hidalgo, Marylin; Orejuela, Leonora; Fuya, Patricia; Carrillo, Pilar; Hernandez, Jorge; Parra, Edgar; Keng, Colette; Small, Melissa; Olano, Juan P; Bouyer, Donald; Castaneda, Elizabeth; Walker, David; Valbuena, Gustavo

    2007-07-01

    We investigated 2 fatal cases of Rocky Mountain spotted fever that occurred in 2003 and 2004 near the same locality in Colombia where the disease was first reported in the 1930s. A retrospective serosurvey of febrile patients showed that > 21% of the serum samples had antibodies aaainst spotted fever group rickettsiae.

  6. Rocky Mountain spotted fever, Panama.

    PubMed

    Estripeaut, Dora; Aramburú, María Gabriela; Sáez-Llorens, Xavier; Thompson, Herbert A; Dasch, Gregory A; Paddock, Christopher D; Zaki, Sherif; Eremeeva, Marina E

    2007-11-01

    We describe a fatal pediatric case of Rocky Mountain spotted fever in Panama, the first, to our knowledge, since the 1950s. Diagnosis was established by immunohistochemistry, PCR, and isolation of Rickettsia rickettsii from postmortem tissues. Molecular typing demonstrated strong relatedness of the isolate to strains of R. rickettsii from Central and South America.

  7. Rocky Mountain Spotted Fever, Colombia

    PubMed Central

    Hidalgo, Marylin; Orejuela, Leonora; Fuya, Patricia; Carrillo, Pilar; Hernandez, Jorge; Parra, Edgar; Keng, Colette; Small, Melissa; Olano, Juan P.; Bouyer, Donald; Castaneda, Elizabeth; Walker, David

    2007-01-01

    We investigated 2 fatal cases of Rocky Mountain spotted fever that occurred in 2003 and 2004 near the same locality in Colombia where the disease was first reported in the 1930s. A retrospective serosurvey of febrile patients showed that >21% of the serum samples had antibodies against spotted fever group rickettsiae. PMID:18214179

  8. Rocky Mountain Spotted Fever, Panama

    PubMed Central

    Estripeaut, Dora; Aramburú, María Gabriela; Sáez-Llorens, Xavier; Thompson, Herbert A.; Dasch, Gregory A.; Paddock, Christopher D.; Zaki, Sherif

    2007-01-01

    We describe a fatal pediatric case of Rocky Mountain spotted fever in Panama, the first, to our knowledge, since the 1950s. Diagnosis was established by immunohistochemistry, PCR, and isolation of Rickettsia rickettsii from postmortem tissues. Molecular typing demonstrated strong relatedness of the isolate to strains of R. rickettsii from Central and South America. PMID:18217566

  9. The effect of Holocene changes in relative sea level on the morphology of rocky coasts

    NASA Astrophysics Data System (ADS)

    Trenhaile, Alan S.

    2010-01-01

    A mathematical wave and weathering model was used to study the effect of Holocene changes in relative sea level (RSL) on rock coast development. Model runs were made for fast- and slow-eroding coasts in macro- and mesotidal environments using Holocene RSL records from Sweden, northeastern USA, southwestern Britain, central Japan, western Africa, and southern Australia. A further series of otherwise identical runs were made with constant sea level. Changes in RSL determined the amount of time that marine processes have operated within the modern intertidal zone, and rates of wave attenuation and erosion continue to be influenced by subtidal morphology that developed in most areas when RSL was rising to its present level. The model suggested that although tidal range is also important, Holocene RSL changes promoted subhorizontal platform development in Australasia and over much of the Southern Hemisphere, and sloping platforms over much of the Northern Hemisphere. Shore platforms may have been partly inherited from earlier periods in the Holocene, when RSL was similar to today's. Nevertheless, most platforms continue to be eroded at all tidal levels. Where geological and wave conditions are less favourable, erosion in the lower intertidal zone has essentially terminated in areas where RSL rose to its present position, whereas erosion only occurs today in the lower intertidal zone in places where RSL rose to above its present level in the middle Holocene.

  10. Distinct patterns of water and osmolyte control between intertidal (Bunodosoma caissarum) and subtidal (Anemonia sargassensis) sea anemones.

    PubMed

    Amado, Enelise M; Vidolin, Denilton; Freire, Carolina A; Souza, Marta M

    2011-04-01

    Anemones are frequently found in rocky intertidal coasts. As they have highly permeable body surfaces, exposure to the air or to salinity variations inside tidal pools can represent intense osmotic and ionic challenges. The intertidal Bunodosoma caissarum has been compared with the subtidal Anemonia sargassensis concerning their response to air exposure or salinity changes. B. caissarum maintains tissue hydration through mucus production and dome-shape formation when challenged with air exposure or extreme salinities (fresh water or hypersaline seawater, 45 psu) for 1-2h. Upon exposure to mild osmotic shocks for 6h (hyposmotic: 25 psu, or hyperosmotic: 37 psu), B. caissarum was able to maintain its coelenteron fluid (CF) osmolality stable, but only in 25 psu. A. sargassensis CF osmolality followed the external medium in both salinities. Isolated cells of the pedal disc of B. caissarum showed full capacity for calcium-dependent regulatory volume decrease (RVD) upon 20% hyposmotic shock, at least partially involving the release of KCl via K(+)-Cl(-) cotransport, and also of organic osmolytes. Aquaporins (HgCl(2)-inhibited) likely participate in this process. Cells of A. sargassensis showed partial RVD, after 20 min. Cells from both species were not capable of regulatory volume increase upon hyperosmotic shock (20%). Whole organism and cellular mechanisms allow B. caissarum to live in the challenging intertidal habitat, frequently facing air exposure and seawater dilution. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Hidden in the mangrove forest: the cryptic intertidal mite Carinozetes mangrovi sp. nov. (Acari, Oribatida, Selenoribatidae).

    PubMed

    Pfingstl, Tobias; Lienhard, Andrea; Jagersbacher-Baumann, Julia

    2014-08-01

    The small archipelago of Bermuda is a geologically young landmass in the Western Atlantic Ocean and recently turned out to be inhabited by a number of intertidal oribatid mites. One newly described species, Carinozetes bermudensis, showed an unusual vast range of habitats like sandy beaches, rocky substrate and mangroves. In the present study, 13 Bermudian populations of C. bermudensis were analysed to verify species integrity of specimens from different microhabitats. A morphometric analysis of 17 continuous variables as well as a molecular genetic investigation of the mitochondrial cytochrome oxidase subunit I revealed the existence of a new species Carinozetes mangrovi sp. nov., inhabiting exclusively intertidal algae growing on mangrove roots. Although both species are morphologically nearly identical, the configuration of the genus-specific ventral carinae represents a clear diagnostic character. The high genetic divergence of approximately 12 % of the cytochrome oxidase subunit I gene sequence between C. bermudensis and C. mangrovi sp. nov. suggests that these two species diverged before the emergence of the Bermuda islands. Accordingly, both of them are older than the geologically young archipelago of Bermuda.

  12. Effects of predation by sea ducks on clam abundance in soft-bottom intertidal habitats

    USGS Publications Warehouse

    Lewis, Tyler; Esler, Daniel N.; Boyd, W. Sean

    2007-01-01

    Recent studies have documented strong, top-down predation effects of sea ducks on mussel populations in rocky intertidal communities. However, the impact of these gregarious predators in soft-bottom communities has been largely unexplored. We evaluated effects of predation by wintering surf scoters Melanitta perspicillata and white-winged scoters M. fusca on clam populations in soft-bottom intertidal habitats of the Strait of Georgia, British Columbia. Specifically, we documented spatial and temporal variation in clam density (clams m–2), scoter diet composition, and the consequences of scoter predation on clam abundance. Of the 3 most numerous clams, Manila clams Venerupis philippinarum and varnish clams Nuttallia obscurata were the primary prey items of both scoter species, while clams of the genus Macoma were rarely consumed by scoters. Between scoter arrival in the fall and departure in the spring, Manila clams decreased in density at most sample sites, while varnish clam densities did not change or declined slightly. Our estimates of numbers of clams consumed by scoters accounted for most of the observed declines in combined abundance of Manila and varnish clams, despite the presence of numerous other vertebrate and invertebrate species known to consume clams. For Macoma spp., we detected an over-winter increase in density, presumably due to growth of clams too small to be retained by our sieve (<5 mm) during fall sampling, in addition to the lack of predation pressure by scoters. These results illustrate the strong predation potential of scoters in soft-bottom intertidal habitats, as well as their potentially important role in shaping community structure.

  13. The Rocky Shore. A Learning Experience for Coastal and Oceanic Awareness Studies, No. 225. [Project COAST].

    ERIC Educational Resources Information Center

    Delaware Univ., Newark. Coll. of Education.

    This unit is designed to be used by students in biology classes in secondary schools. Emphasized in the unit are coastal life zones, plants and animals that live in these areas, and factors influencing the lives of the organisms. Included in the unit are evaluation materials, instructional objectives, student background information, masters for…

  14. Reconnaissance of intertidal and subtidal zones of Back Island, Behm Canal, Southeast Alaska

    SciTech Connect

    Strand, J.A.; Young, J.S.

    1986-09-01

    A diver reconnaissance of the intertidal and subtidal zones of Back Island, Southeast Alaska, was performed May 20-22, 1986. The specific objectives were to catalog potentially vulnerable shellfish, other invertebrates, and plant resources, and to identify potential herring spawning sites. This effort was designed to supplement the existing ecological data base for Back Island that would be used during the National Environmental Policy Act (NEPA) documentation process. A NEPA document will be prepared that describes the site environment and assesses impacts from the proposed construction and operation of the Southeast Alaska Acoustic Measurement Facility (SEAFAC). Nine diver transects were established around Back Island. Particular attention was devoted to proposed locations for the pier and float facilities and range-operations and shore-power cable run-ups.

  15. Wave energy dissipation by intertidal sand waves on a mixed-sediment Beach

    USGS Publications Warehouse

    Adams, P.; Ruggiero, P.

    2006-01-01

    Within the surf zone, the energy expended by wave breaking is strongly influenced by nearshore bathymetry, which is often linked to the character and abundance of local sediments. Based upon a continuous, two year record of Argus Beach Monitoring System (ABMS) data on the north shore of Kachemak Bay in southcentral Alaska, we model the enhancement of wave energy dissipation by the presence of intertidal sand waves. Comparison of model results from simulations in the presence and absence of sand waves illustrates that these ephemeral morphological features can offer significant protection to the backing beach and sea cliff through two mechanisms: (1) by moving the locus of wave breaking seaward and (2) by increasing energy expenditure associated with the turbulence of wave breaking. Copyright ASCE 2006.

  16. Effects of laughing gull and shorebird predation on the intertidal fauna at Cape May, New Jersey

    NASA Astrophysics Data System (ADS)

    Botton, M. L.

    1984-02-01

    The intertidal flats of the Cape May, New Jersey shore of Delaware Bay are populated by large numbers of laughing gulls and migrating shorebirds during the spring and early summer. Exclusion of birds from a shallow slough and a sand bar had only minor effects on the infaunal benthic invertebrate assemblage at either site. The Cape May beaches provide a rich source of food in the form of horseshoe crab ( Limulus polyphemus) eggs; foraging on this item may be more profitable than probing the sediment for infauna. Gemma gemma, a small, thick-shelled bivalve, composed over 98% of the benthic infauna at both sites in 1980, and this species may be resistant to predation by certain shorebirds, as suggested by Schneider (1978).

  17. Microplastic fibers in the intertidal ecosystem surrounding Halifax Harbor, Nova Scotia.

    PubMed

    Mathalon, Alysse; Hill, Paul

    2014-04-15

    Humans continue to increase the use and disposal of plastics by producing over 240 million tonnes per year, polluting the oceans with persistent waste. The majority of plastic in the oceans are microplastics (<5 mm). In this study, the contamination of microplastic fibers was quantified in sediments from the intertidal zones of one exposed beach and two protected beaches along Nova Scotia's Eastern Shore. From the two protected beaches, polychaete worm fecal casts and live blue mussels (Mytilus edulis) were analyzed for microplastic content. Store-bought mussels from an aquaculture site were also analyzed. The average microplastic abundance observed from 10 g sediment subsamples was between 20 and 80 fibers, with higher concentrations at the high tide line from the exposed beach and at the low tide line from the protected beaches. Microplastic concentrations from polychaete fecal casts resembled concentrations quantified from low tide sediments. In two separate mussel analyses, significantly more microplastics were enumerated in farmed mussels compared to wild ones.

  18. Controls on the distribution of cosmogenic 10Be across shore platforms

    NASA Astrophysics Data System (ADS)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.

    2017-01-01

    Quantifying rates of erosion on cliffed coasts across a range of timescales is vital for understanding the drivers and processes of coastal change and for assessing risks posed by future cliff retreat. Historical records cover at best the last 150 years; cosmogenic isotopes, such as 10Be could allow us to look further into the past to assess coastal change on millennial timescales. Cosmogenic isotopes accumulate in situ near the Earth surface and have been used extensively to quantify erosion rates, burial dates and surface exposure ages in terrestrial landscapes over the last 3 decades. More recently, applications in rocky coast settings have quantified the timing of mass wasting events, determined long-term averaged rates of cliff retreat and revealed the exposure history of shore platforms. In this contribution, we develop and explore a numerical model for the accumulation of 10Be on eroding shore platforms. In a series of numerical experiments, we investigated the influence of topographic and water shielding, dynamic platform erosion processes, the presence and variation in beach cover, and heterogeneous distribution of erosion on the distribution of 10Be across shore platforms. Results demonstrate that, taking into account relative sea level change and tides, the concentration of 10Be is sensitive to rates of cliff retreat. Factors such as topographic shielding and beach cover act to reduce 10Be concentrations on the platform and may result in overestimation of cliff retreat rates if not accounted for. The shape of the distribution of 10Be across a shore platform can potentially reveal whether cliff retreat rates are declining or accelerating through time. Measurement of 10Be in shore platforms has great potential to allow us to quantify long-term rates of cliff retreat and platform erosion.

  19. Retro-action model for the erosion of rocky coasts

    NASA Astrophysics Data System (ADS)

    Sapoval, B.; Baldassarri, A.

    2009-12-01

    Rocky coasts are estimated to represent 75% of the world’s shorelines [1]. We discuss various situations where the formation of rocky coast morphology could be attributed to the retro-action of the coast morphology on the erosive power of the see. In the case of rocky coasts, erosion can spontaneously create irregular seashores. But, in turn, the geometrical irregularity participates to the damping of sea-waves, decreasing the average wave amplitude and erosive power. There may then exist a mutual self-stabilization of the waves amplitude together with the irregular morphology of the coast. A simple model of such stabilization is discussed. It leads, through a complex dynamics of the earth-sea interface, to the spontaneous appearance of an irregular sea-shore. The final coast morphology is found to depend on the morphology/damping coupling of the coast and on the possible existence of built-in correlations within the coast lithologic properties. This is illustrated in the figure. In the limit case where the morphology/damping coupling is weak and when the earth lithology distribution exhibit only short range correlations, the process spontaneously build fractal morphologies with a dimension close to 4/3 [2]. It is shown that this dimension refers to the dimension of the so-called accessible perimeter in gradient percolation. However, even rugged but non-fractal sea-coasts morphology may emerge for strong damping or during the erosion process. When the distributions of the lithologies exhibit long range correlations, a variety of complex morphologies are obtained which mimics observed coastline complexity, well beyond simple fractality. On a somewhat different perspective, the design of breakwaters is suggested to be improved by using global irregular geometry with features sizes of the order of the wave-length of the sea oscillations. [1] R. A. Davis, Jr, D. M. Fitzgerald, Beaches and Coasts,(Blackwell, Oxford 2004). [2] B. Sapoval, A. Baldassarri, A. Gabrielli

  20. Site fidelity, size, and morphology may differ by tidal position for an intertidal fish, Bathygobius cocosensis (Perciformes-Gobiidae), in Eastern Australia

    PubMed Central

    Malard, Lucie A.; McGuigan, Katrina

    2016-01-01

    The intertidal zone is a transitional environment that undergoes daily environmental fluctuations as tides rise and fall. Relatively few fish species are adapted to endure the physiological pressures of this environment. This study focused on Bathygobius cocosensis (Gobiidae), a common intertidal fish in New South Wales, Australia. We investigated whether shore height impacted site fidelity, survival probability, fish size, and morphological traits with respect to tidal height. Mark-recapture methods were used over a five month period to determine if individuals in high shore pools had greater site fidelity; fish in high tide pools were more than twice as likely to be recaptured in their original pool than fish from low tide pools. High pool individuals were, on average, smaller with larger eyes and longer snouts relative to their size as compared to low pool individuals. We discuss several mechanisms that could cause the observed pattern in morphological variation. Ultimately, this study suggests that within species behaviour and morphology differ by tidal position for an intertidal fish. PMID:27547568

  1. Site fidelity, size, and morphology may differ by tidal position for an intertidal fish, Bathygobius cocosensis (Perciformes-Gobiidae), in Eastern Australia.

    PubMed

    Malard, Lucie A; McGuigan, Katrina; Riginos, Cynthia

    2016-01-01

    The intertidal zone is a transitional environment that undergoes daily environmental fluctuations as tides rise and fall. Relatively few fish species are adapted to endure the physiological pressures of this environment. This study focused on Bathygobius cocosensis (Gobiidae), a common intertidal fish in New South Wales, Australia. We investigated whether shore height impacted site fidelity, survival probability, fish size, and morphological traits with respect to tidal height. Mark-recapture methods were used over a five month period to determine if individuals in high shore pools had greater site fidelity; fish in high tide pools were more than twice as likely to be recaptured in their original pool than fish from low tide pools. High pool individuals were, on average, smaller with larger eyes and longer snouts relative to their size as compared to low pool individuals. We discuss several mechanisms that could cause the observed pattern in morphological variation. Ultimately, this study suggests that within species behaviour and morphology differ by tidal position for an intertidal fish.

  2. Frequency domain electromagnetic induction survey in the intertidal zone: Limitations of low-induction-number and depth of exploration

    NASA Astrophysics Data System (ADS)

    Delefortrie, Samuël; Saey, Timothy; Van De Vijver, Ellen; De Smedt, Philippe; Missiaen, Tine; Demerre, Ine; Van Meirvenne, Marc

    2014-01-01

    Subsurface investigation in the Belgian intertidal zone is severely complicated due to high heterogeneity and tides. Near-surface geophysical techniques can offer assistance since they allow fast surveying and collection of high spatial density data and frequency domain electromagnetic induction (EMI) was chosen for archaeological prospection on the Belgian shore. However, in the intertidal zone the effects of extreme salinity compromise validity of low-induction-number (LIN) approximated EMI data. In this paper, the effects of incursion of seawater on multi-receiver EMI data are investigated by means of survey results, field observations, cone penetration tests and in-situ electrical conductivity measurements. The consequences of LIN approximation breakdown were researched. Reduced depth of investigation of the quadrature-phase (Qu) response and a complex interpretation of the in-phase response were confirmed. Nonetheless, a high signal-to-noise ratio of the Qu response and viable data with regard to shallow subsurface investigation were also evidenced, allowing subsurface investigation in the intertidal zone.

  3. Survival of hatchery-reared lake trout stocked near shore and off shore in Lake Ontario

    USGS Publications Warehouse

    Elrod, Joseph H.

    1997-01-01

    Establishing a stock of mature, hatchery-reared fish is necessary to restore a self-sustaining population of lake trout Salvelinus namaycush in Lake Ontario. Stocking fish off shore rather than near shore to reduce predation on these fish by large lake trout or piscivorous birds may enhance survival of hatchery-reared fish and accelerate establishment of a population of adults. Results of an earlier study did not support routinely stocking fish off shore by helicopter in Lake Ontario, but stresses associated with helicopter stocking suggested another method of transporting fish off shore might enhance survival. I conducted this study to determine whether stocking lake trout off shore by barge would enhance first-year survival. Two lots of yearling lake trout were stocked at each of four locations in Lake Ontario in May 1992. One lot was stocked from shore, and an identical lot was transported by barge 3.4–10.4 km off shore of nearshore locations and stocked in water 46–52 m deep. Fish were recovered during trawl, gillnet, and creel surveys in 1992–1996. First-year survival of lake trout stocked off shore tended to be better than that of fish stocked near shore. Predation by double-crested cormorantsPhalacrocorax auritus likely affected survival of fish stocked near shore at two locations, 7 and 37 km, respectively, from a nesting colony of 5,443 pairs of double-crested cormorants. Predation by large lake trout remains a viable hypothesis, which explains, at least partially, lower survival of lake trout stocked near shore at two other locations. Stocking lake trout off shore of traditional nearshore stocking sites likely will enhance first-year survival of hatchery-reared fish and promote accumulation of an adult population, especially for those occassions where nearshore stocking locations are near nesting colonies of double-crested cormorants.

  4. Cross-Shore Exchange on Natural Beaches

    DTIC Science & Technology

    2014-09-01

    words) The cross-shore exchange of material is examined on beaches of varying morphology and hydrodynamics. On a dissipative, rip-channeled beach...cross-shore exchange of material is examined on beaches of varying morphology and hydrodynamics. On a dissipative, rip-channeled beach in Monterey...Onshore and offshore exchange occurs by various processes, depending on beach morphology , beach slope, wave conditions, and resulting current patterns

  5. Shore Shapers: Introducing children and the general public to biogeomorphological processes and geodiversity

    NASA Astrophysics Data System (ADS)

    Naylor, Larissa; Coombes, Martin; Sewell, Jack; White, Anissia

    2014-05-01

    Coastal processes shape the coast into a variety of eye-catching and enticing landforms that attract people to marvel at, relax and enjoy coastal geomorphology. Field guides to explain these processes (and the geodiversity that results) to the general public and children are few and far between. In contrast, there is a relative wealth of resources and organised activities introducing people to coastal wildlife, especially on rocky shores. These biological resources typically focus on the biology and climatic controls on their distribution, rather than how the biology interacts with its physical habitat. As an outcome of two recent rock coast biogeomorphology projects (www.biogeomorph.org/coastal/coastaldefencedbiodiversity and www.biogeomorph.org/coastal/bioprotection ), we produced the first known guide to understanding how biogeomorphological processes help create coastal landforms. The 'Shore Shapers' guide (www.biogeomorph.org/coastal/shoreshapers) is designed to: a) bring biotic-geomorphic interactions to life and b) introduce some of the geomorphological and geological controls on biogeomorphic processes and landform development. The guide provides scientific information in an accessible and interactive way - to help sustain children's interest and extend their learning. We tested a draft version of our guide with children, the general public and volunteers on rocky shore rambles using social science techniques and of 74 respondents, 75.6% were more interested in understanding how rock pools (i.e. coastal landforms) develop after seeing the guide. Respondents' opinions about key bioprotective species also changed as a result of seeing the guide - 58% of people found barnacles unattractive before they saw the guide whilst 36% of respondents were more interested in barnacles after seeing the guide. These results demonstrate that there is considerable interest in more educational materials on coastal biogeomorphology and geodiversity.

  6. Vertical distribution of rocky subtidal assemblages along the exposed coast of north-central Chile

    NASA Astrophysics Data System (ADS)

    Stotz, Wolfgang B.; Aburto, Jaime; Caillaux, Luis M.; González, Sergio A.

    2016-01-01

    Through a systematic study of a stretch of coast in north central Chile, the variety and vertical zonation patterns of the rocky subtidal communities are described, thereby revising apparent uniformity and lack of vertical zonation of the rocky subtidal of southeastern Pacific shores previously reported in the literature. Over the 600 km of coast studied, the following pattern of depth-zonation is described: an upper fringe (lower part of the sublittoral fringe) characterized by barren grounds dominated by calcareous encrusting algae and the sea urchin Tetrapygus niger; an intermediate fringe (upper Infralittoral sub-zone) characterized either by deep barren grounds similar to the former, or kelp beds of Lessonia trabeculata, or an assemblage of suspension feeding organisms, as the big barnacle Austromegabalanus psittacus and/or the tunicate Pyura chilensis; and a deep fringe (Circalittoral sub-zone) dominated by small encrusting or mobile invertebrates. This basic vertical zonation pattern of the shallow rocky subtidal communities seems to be common to most of the temperate coasts of the world. The analysis, first of the occurrence of the general zonation pattern and second of the species composition within the assemblages corresponding to each sub-zone, offers a useful framework for the assessment of the eventual impacts and changes within the shallow rocky subtidal habitat, for example within environmental monitoring programs.

  7. Managing Rocky Mountain spotted fever.

    PubMed

    Minniear, Timothy D; Buckingham, Steven C

    2009-11-01

    Rocky Mountain spotted fever is caused by the tick-borne bacterium Rickettsia rickettsii. Symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. The disease is prevalent in most of the USA, especially during warmer months. The trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. Other signature symptoms include headache and abdominal pain. The antibiotic therapy of choice for R. rickettsii infection is doxycycline. Preventive measures for Rocky Mountain spotted fever and other tick-borne diseases include: wearing long-sleeved, light colored clothing; checking for tick attachment and removing attached ticks promptly; applying topical insect repellent; and treating clothing with permethrin.

  8. Evaluation of the biological role in the shore platform evolution. Development of specific methodology and first results.

    NASA Astrophysics Data System (ADS)

    Neves, Mario; Ramos-Pereira, Ana; Moura, Delminda; Trindade, Jorge; Gusmão, Francisca; Viegas, José; Santana, Paulo

    2010-05-01

    The formation and the evolution of shore platforms are dependent on several physical, chemical and biological processes. The weight of each of these processes is changeable not only from coast to coast but also within each shore platform. It depends on geographical, geomorphological, climatic and wave climate factors. In the lower intertidal zone of many rock coasts of the world, the biological cover of the surface is extremely high. This almost permanent wrap points out to a very strong biological influence on the downwearing rates and the erosive rhythm of these strips of the shore platforms. Yet, although there are several studies on the erosive ability of the individuals of each species that are found here, analyzed separately, research on the interactions among species with erosive and protective role in the present evolution of shore platforms are rare. The goal of the BISHOP Project - Bioprotection and bioerosion on shore platforms in the Algarve and Estremadura (Portugal South and West Coast) - is precisely to evaluate the bioprotective and bioerosive role of the communities of macro-organisms in the evolution of shore platforms cut in different type of rocks and in assorted environments. With that purpose, it was necessary to develop specific methodology. To quantify the downwearing of the shore platform, we used a TMEM (Traversing Micro-Erosion Meter) with an accuracy of 0,005mm, and capable of measuring 255 points in a 117 cm2 area. Four experimental places were chosen: two at calcarenite shore platforms of the Portuguese south coast, in a coastal zone exposed to the south and sheltered from the waves; and two in the Portuguese Estremadura, facing west on a well exposed coast to the North Atlantic energetic waves, on shore platforms cut in marly limestone. At each place, two pairs of monitoring areas were installed. For each pair, the same methodology was used. At the beginning, it was necessary to completely clean the biological cover of the two areas

  9. Coastal saltmarsh managed realignment drives rapid breach inlet and external creek evolution, Freiston Shore (UK)

    NASA Astrophysics Data System (ADS)

    Friess, Daniel A.; Möller, Iris; Spencer, Thomas; Smith, Geoffrey M.; Thomson, Andrew G.; Hill, Ross A.

    2014-03-01

    The creation of saltmarsh through the managed realignment of sea defences, implemented in NW Europe as a sustainable coastal defence option, represents a substantial hydrodynamic perturbation to the local coastal system. The impact of a significantly increased tidal prism on hydromorphological features was investigated at Freiston Shore, Lincolnshire UK. Local tidal conditions and inadequate drainage at this realignment trial contributed to significant channel erosion due to the establishment of water surface slopes and pooling between the newly realigned site and the adjacent intertidal zone. Very high spatial resolution aerial photography and blimp photography were used to monitor inlet evolution from breaching in August 2002 to March 2008, showing a highly non-linear response with breach channels increasing in width by up to 960% within 2.5 months. Airborne laser scanning/LiDAR and terrestrial laser scanning quantified breach channel volume increases, showing a similar pattern. Breach channel evolution did not follow established tidal prism-channel width/cross-sectional area relationships that are often used to guide realignment design. Pre- and post-breach rates of external creek morphology change between 1999 and 2006 were also quantified, with intertidal creeks attached to the breach channels increasing significantly after realignment in both width and depth. This study highlights the physical processes affected by managed realignment, and the importance of understanding the causes of complex water surface slopes at multiple scales.

  10. Geological control on the morphology of estuarine shore platforms: Middle Harbour, Sydney, Australia

    NASA Astrophysics Data System (ADS)

    Kennedy, D. M.

    2010-01-01

    Middle Harbour, Sydney, Australia is a microtidal environment formed in resistant Triassic quartzose sandstone (mean N-type Schmidt Hammer rebound value of 37 ± 6). Wave energy is dominated by deep-water ocean swell which is dissipated rapidly as it propagates through the estuary mouth and is absent 1.5 km upstream. The small fetch of the harbour also means locally-generated wind waves are insignificant, generally < 1 m. Shore platforms occur in locations where deep-water waves can impact the bedrock and here surfaces up to 60 m wide are formed. They occur to an elevation of 3.5 m above mean sea level and are characterised by a vertical seaward cliff at least 1 m high, often > 2 m in the most exposed locations. All the platforms are semi-horizontal and appear to occur where a joint or bedding plane is coincident with intertidal elevations, although there is little correspondence with a particular tidal limit, with surfaces occurring at all levels between MLWS and MHWS. Several horizontal surfaces are found above the limit of modern tides and those at c. 1.5 and 2.1 m levels are likely to result from higher sea levels. Lithological structure and rock resistance therefore appear to be the primary determinants of platform morphology, with the most distinct development occurring where these planes are coincident with the intertidal zones where most erosion occurs. Some morphological inheritance from previous higher sea levels may also be found within the estuary.