HARMFUL ALGAL BLOOMS OBSERVING SYSTEM PILOT PROJECT

EPA Science Inventory

The HABSOS Pilot Project is being developed through a partnership of federal, state and academic organizations as proof-of-concept for a coastal observing system in the Gulf of Mexico. The goal is to design a HAB data management system and develop the regional communication infra...

Airborne Hyperspectral Sensing of Monitoring Harmful Algal Blooms in the Great Lakes Region: System Calibration and Validation

NASA Technical Reports Server (NTRS)

Lekki, John; Anderson, Robert; Avouris, Dulcinea; Becker, RIchard; Churnside, James; Cline, Michael; Demers, James; Leshkevich, George; Liou, Larry; Luvall, Jeffrey;

Challenges in modelling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

NASA Astrophysics Data System (ADS)

Sedigh Marvasti, S.; Gnanadesikan, A.; Bidokhti, A. A.; Dunne, J. P.; Ghader, S.

2015-07-01

We examine interannual variability of phytoplankton blooms in northwestern Arabian Sea and Gulf of Oman. Satellite data (SeaWIFS ocean color) shows two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. A pronounced anti-correlation between the AVISO sea surface height anomaly (SSHA) and chlorophyll is found during the wintertime bloom. On a regional scale, interannual variability of the wintertime bloom is thus dominated by cyclonic eddies which vary in location from one year to another. These results were compared against the outputs from three different 3-D Earth System models. We show that two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The southern part of the domain is a region with a much sharper thermocline and nutricline relatively close to the surface, in which eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). We suggest that for the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf.

Monitoring of ocean surface algal blooms in coastal and oceanic waters around India.

PubMed

Tholkapiyan, Muniyandi; Shanmugam, Palanisamy; Suresh, T

2014-07-01

The National Aeronautics and Space Administration's (NASA) sensor MODIS-Aqua provides an important tool for reliable observations of the changing ocean surface algal bloom paradigms in coastal and oceanic waters around India. A time series of the MODIS-Aqua-derived OSABI (ocean surface algal bloom index) and its seasonal composite images report new information and comprehensive pictures of these blooms and their evolution stages in a wide variety of events occurred at different times of the years from 2003 to 2011, providing the first large area survey of such phenomena around India. For most of the years, the results show a strong seasonal pattern of surface algal blooms elucidated by certain physical and meteorological conditions. The extent of these blooms reaches a maximum in winter (November-February) and a minimum in summer (June-September), especially in the northern Arabian Sea. Their spatial distribution and retention period are also significantly increased in the recent years. The increased spatial distribution and intensity of these blooms in the northern Arabian Sea in winter are likely caused by enhanced cooling, increased convective mixing, favorable winds, and atmospheric deposition of the mineral aerosols (from surrounding deserts) of the post-southwest monsoon period. The southward Oman coastal current and southwestward winds become apparently responsible for their extension up to the central Arabian Sea. Strong upwelling along this coast further triggers their initiation and growth. Though there is a warming condition associated with increased sea surface height anomalies along the coasts of India and Sri Lanka in winter, surface algal bloom patches are still persistent along these coasts due to northeast monsoonal winds, enhanced precipitation, and subsequent nutrient enrichment in these areas. The occurrence of the surface algal blooms in the northern Bay of Bengal coincides with a region of the well-known Ganges-Brahmaputra Estuarine Frontal (GBEF) system, which increases supply of nutrients in addition to the land-derived inputs triggering surface algal blooms in this region. Low density (initiation stage) of such blooms observed in clear oceanic waters southeast and northeast of Sri Lanka may be caused by the vertical mixing processes (strong monsoonal winds) and the occurrence of Indian Ocean Dipole events. Findings based on the analyses of time series satellite data indicate that the new information on surface algal blooms will have important bearing on regional fisheries, ecosystem and environmental studies, and implications of climate change scenarios.

Solutions Network Formulation Report. Integrating Salinity Measurements from Aquarius into the Harmful Algal Blooms Observing System

NASA Technical Reports Server (NTRS)

Anderson, Daniel; Lewis, David; Hilbert, Kent

2007-01-01

This Candidate Solution suggests the use of Aquarius sea surface salinity measurements to improve the NOAA/NCDDC (National Oceanic and Atmospheric Administration s National Coastal Data Development Center) HABSOS (Harmful Algal Blooms Observing System) DST (decision support tool) by enhancing development and movement forecasts of HAB events as well as potential species identification. In the proposed configuration, recurring salinity measurements from the Aquarius mission would augment HABSOS sea surface temperature and in situ ocean current measurements. Thermohaline circulation observations combined with in situ measurements increase the precision of HAB event movement forecasting. These forecasts allow coastal managers and public health officials to make more accurate and timely warnings to the public and to better direct science teams to event sites for collection and further measurements.

Production of viruses during a spring phytoplankton bloom in the South Pacific Ocean near of New Zealand.

PubMed

Matteson, Audrey R; Loar, Star N; Pickmere, Stuart; DeBruyn, Jennifer M; Ellwood, Michael J; Boyd, Philip W; Hutchins, David A; Wilhelm, Steven W

2012-03-01

Lagrangian studies of virus activity in pelagic environments over extended temporal scales are rare. To address this, viruses and bacteria were examined during the course of a natural phytoplankton bloom in the pelagic South Pacific Ocean east of New Zealand. Daily samples were collected in a mesoscale eddy from year days 263-278 (September 19th-October 4th, 2008). The productive bloom transitioned from a diatom to a pico- and nanoplankton-dominated system, resulting in chlorophyll a concentrations up to 2.43 μg L(-1) . Virus abundances fluctuated c. 10-fold (1.8 × 10(10) -1.3 × 10(11)  L(-1) ) over 16 days. The production rates of virus particles were high compared with those reported in other marine systems, ranging from 1.4 × 10(10) to 2.1 × 10(11)  L(-1)  day(-1) . Our observations suggest viruses contributed significantly to the mortality of bacteria throughout the bloom, with 19-216% of the bacterial standing stock being lysed daily. This mortality released nutrient elements (N, Fe) that likely helped sustain the bloom through the sampling period. Parametric analyses found significant correlations with both biotic (e.g. potential host abundances) and abiotic parameters (e.g. nutrient concentrations, temperature). These observations demonstrate that viruses may be critical in the extended maintenance of regeneration-driven biological production. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Binational collaboration to study Gulf of Mexico's harmful algae

NASA Astrophysics Data System (ADS)

Soto, Inia; Hu, Chuanmin; Steidinger, Karen; Muller-Karger, Frank; Cannizzaro, Jennifer; Wolny, Jennifer; Cerdeira-Estrada, Sergio; Santamaria-del-Angel, Eduardo; Tafoya-del-Angel, Fausto; Alvarez-Torres, Porfirio; Herrera Silveira, Jorge; Allen, Jeanne

2012-01-01

Blooms of the toxic marine dinoflagellate Karenia brevis cause massive fish kills and other public health and economic problems in coastal waters throughout the Gulf of Mexico [Steidinger, 2009]. These harmful algal blooms (HABs) are a gulf-wide problem that require a synoptic observing system for better serving decision-making needs. The major nutrient sources that initiate and maintain these HABs and the possible connectivity of blooms in different locations are important questions being addressed through new collaborations between Mexican and U.S. researchers and government institutions. These efforts were originally organized under the U.S./Mexico binational partnership for the HABs Observing System (HABSOS), led by the U.S. Environmental Protection Agency's Gulf of Mexico Program (EPAGMP) and several agencies in Veracruz, Mexico, since 2006. In 2010 these efforts were expanded to include other Mexican states and institutions with the integrated assessment and management of the Gulf of Mexico Large Marine Ecosystem (GoMLME) program sponsored by the Global Environment Facility (GEF), the United Nations Industrial Development Organization (UNIDO), the Secretaría de Medio Ambiente y Recursos Naturales (SEMARNAT), and the National Oceanic and Atmospheric Administration (NOAA).

Advection of Karenia brevis blooms from the Florida Panhandle towards Mississippi coastal waters.

PubMed

Soto, Inia M; Cambazoglu, Mustafa Kemal; Boyette, Adam D; Broussard, Kristina; Sheehan, Drew; Howden, Stephan D; Shiller, Alan M; Dzwonkowski, Brian; Hode, Laura; Fitzpatrick, Patrick J; Arnone, Robert A; Mickle, Paul F; Cressman, Kimberly

2018-02-01

Harmful Algal Blooms (HABs) of Karenia brevis have been documented along coastal waters of every state bordering the Gulf of Mexico (GoM). Some Gulf Coast locations, such as Florida and Texas, suffer from recurrent intense and spatially large blooms, while others such as Mississippi seem to rarely observe them. The main objective of this work is to understand the dynamics that led to the K. brevis bloom in Mississippi coastal waters in fall 2015. Blooms of K. brevis from the Florida Panhandle region are often advected westward towards the Mississippi-Alabama coast; however there is interannual variability in their presence and intensity in Mississippi coastal waters. The 2015 K. brevis bloom was compared to the 2007 Florida Panhandle K. brevis bloom, which showed a westward advection pattern, but did not intensify along the Mississippi coast. Cell counts and flow cytometry were obtained from the Mississippi Department of Marine Resources, Alabama Department of Public Health, Florida Fish and Wildlife Conservation Commission and The University of Southern Mississippi. Ocean color satellite imagery from the Moderate Resolution Imaging Spectroradiometer onboard the Aqua satellite was used to detect and delineate the blooms in 2007 and 2015. Two different regional applications of NCOM-Navy Coastal Ocean Model (1-km resolution NCOM-GoM/Gulf of Mexico and 6-km resolution NCOM-IASNFS/Intra Americas Sea Nowcast Forecast System) were used to understand the circulation and transport pathways. A Lagrangian particle tracking software was used to track the passive movement of particles released at different locations for both bloom events. Ancillary data (e.g., nutrients, wind, salinity, river discharge) from local buoys, monitoring stations and coincident oceanographic cruises were also included in the analysis. The blooms of K. brevis reached the Mississippi coast both years; however, the bloom in 2007 lasted only a few days and there is no evidence that it entered the Mississippi Sound. Two major differences were observed between both years. First, circulation patterns in 2015 resulting from an intense westward-northwestward that persisted until December allowed for continuous advection, whereas this pattern was not evident in 2007. Second, local river discharge was elevated throughout late fall 2015 while 2007 was below the average. Thus, elevated discharge may have provided sufficient nutrients for bloom intensification. These results illustrate the complex, but important interactions in coastal zones. Further, they emphasize the importance in establishing comprehensive HAB monitoring programs, which facilitate our understanding of nutrient and phytoplankton dynamics, and stress the importance for multi-agency cooperation across state boundaries. Copyright © 2017 Elsevier B.V. All rights reserved.

Tidally driven pore water exchange in offshore intertidal sandbanks: Part I. Field measurements

NASA Astrophysics Data System (ADS)

Gibbes, B.; Robinson, C.; Carey, H.; Li, L.; Lockington, D.

2008-08-01

In recent years blooms of the toxic marine cyanobacteria Lyngbya majuscula have been frequently observed in a system of offshore intertidal sandbanks in Moreton Bay, Australia. Past research suggests that these blooms are linked to the presence of bio-available forms of iron. Using hydraulic and pore water chemistry data collected from a shore normal transect at an offshore bloom site, the role of tidally driven exchange as a potential mechanism for delivery of bio-available iron across the sediment-water interface was examined. Field data revealed a residual pore water flow system in the sandbank, with seawater entering the upper sandbank platform and discharging through the bank edge. Upward flow and elevated near-surface dissolved Fe(II) concentrations (>20 μM Fe(II) at -0.05 m depth) were measured simultaneously in the discharge zones at the sandbank edge. The measured concentrations were more than four times greater than concentrations previously shown to stimulate L. majuscula growth. These results suggest that the tidally driven exchange mechanism might be capable of delivering dissolved Fe(II) to sites within offshore intertidal sandbanks where blooms of L. majuscula have been observed. While the source of the iron was not identified, potential candidates are discussed. These findings have implications for the current conceptual model for L. majuscula blooms in offshore intertidal sandbanks within Moreton Bay. Further investigations are required to fully understand the role of tidally driven exchange in controlling the export of bio-available iron to coastal waters at the field site. In particular there is a need to better assess the link between the pore water flows and the geochemical reactions that might occur along the flow path.

Rainfall-enhanced blooming in typhoon wakes

PubMed Central

Lin, Y.-C.; Oey, L.-Y.

2016-01-01

Strong phytoplankton blooming in tropical-cyclone (TC) wakes over the oligotrophic oceans potentially contributes to long-term changes in global biogeochemical cycles. Yet blooming has traditionally been discussed using anecdotal events and its biophysical mechanics remain poorly understood. Here we identify dominant blooming patterns using 16 years of ocean-color data in the wakes of 141 typhoons in western North Pacific. We observe right-side asymmetric blooming shortly after the storms, attributed previously to sub-mesoscale re-stratification, but thereafter a left-side asymmetry which coincides with the left-side preference in rainfall due to the large-scale wind shear. Biophysical model experiments and observations demonstrate that heavier rainfall freshens the near-surface water, leading to stronger stratification, decreased turbulence and enhanced blooming. Our results suggest that rainfall plays a previously unrecognized, critical role in TC-induced blooming, with potentially important implications for global biogeochemical cycles especially in view of the recent and projected increases in TC-intensity that harbingers stronger mixing and heavier rain under the storm. PMID:27545899

Rainfall-enhanced blooming in typhoon wakes.

PubMed

Lin, Y-C; Oey, L-Y

2016-08-22

Strong phytoplankton blooming in tropical-cyclone (TC) wakes over the oligotrophic oceans potentially contributes to long-term changes in global biogeochemical cycles. Yet blooming has traditionally been discussed using anecdotal events and its biophysical mechanics remain poorly understood. Here we identify dominant blooming patterns using 16 years of ocean-color data in the wakes of 141 typhoons in western North Pacific. We observe right-side asymmetric blooming shortly after the storms, attributed previously to sub-mesoscale re-stratification, but thereafter a left-side asymmetry which coincides with the left-side preference in rainfall due to the large-scale wind shear. Biophysical model experiments and observations demonstrate that heavier rainfall freshens the near-surface water, leading to stronger stratification, decreased turbulence and enhanced blooming. Our results suggest that rainfall plays a previously unrecognized, critical role in TC-induced blooming, with potentially important implications for global biogeochemical cycles especially in view of the recent and projected increases in TC-intensity that harbingers stronger mixing and heavier rain under the storm.

Rainfall-enhanced blooming in typhoon wakes

NASA Astrophysics Data System (ADS)

Lin, Y.-C.; Oey, L.-Y.

2016-08-01

Strong phytoplankton blooming in tropical-cyclone (TC) wakes over the oligotrophic oceans potentially contributes to long-term changes in global biogeochemical cycles. Yet blooming has traditionally been discussed using anecdotal events and its biophysical mechanics remain poorly understood. Here we identify dominant blooming patterns using 16 years of ocean-color data in the wakes of 141 typhoons in western North Pacific. We observe right-side asymmetric blooming shortly after the storms, attributed previously to sub-mesoscale re-stratification, but thereafter a left-side asymmetry which coincides with the left-side preference in rainfall due to the large-scale wind shear. Biophysical model experiments and observations demonstrate that heavier rainfall freshens the near-surface water, leading to stronger stratification, decreased turbulence and enhanced blooming. Our results suggest that rainfall plays a previously unrecognized, critical role in TC-induced blooming, with potentially important implications for global biogeochemical cycles especially in view of the recent and projected increases in TC-intensity that harbingers stronger mixing and heavier rain under the storm.

Rainfall-enhanced blooming in typhoon wakes

NASA Astrophysics Data System (ADS)

Lin, Y.; Oey, L. Y.

2016-12-01

Strong phytoplankton blooming in tropical-cyclone (TC) wakes over the oligotrophic oceans potentially contributes to long-term changes in global biogeochemical cycles. Yet blooming has traditionally been discussed using anecdotal events and its biophysical mechanics remain poorly understood. Here we identify dominant blooming patterns using 16 years of ocean-color data in the wakes of 141 typhoons in western North Pacific. We observe right-side asymmetric blooming shortly after the storms, attributed previously to sub-mesoscale re-stratification, but thereafter a left-side asymmetry which coincides with the left-side preference in rainfall due to the large-scale wind shear. Biophysical model experiments and observations demonstrate that heavier rainfall freshens the near-surface water, leading to stronger stratification, decreased turbulence and enhanced blooming. Our results suggest that rainfall plays a previously unrecognized, critical role in TC-induced blooming, with potentially important implications for global biogeochemical cycles especially in view of the recent and projected increases in TC-intensity that harbingers stronger mixing and heavier rain under the storm.

Mechanisms of inflammation-driven bacterial dysbiosis in the gut

PubMed Central

Zeng, MY; Inohara, N; Nuñez, G

2018-01-01

The gut microbiota has diverse and essential roles in host metabolism, development of the immune system and as resistance to pathogen colonization. Perturbations of the gut microbiota, termed gut dysbiosis, are commonly observed in diseases involving inflammation in the gut, including inflammatory bowel disease, infection, colorectal cancer and food allergies. Importantly, the inflamed microenvironment in the gut is particularly conducive to blooms of Enterobacteriaceae, which acquire fitness benefits while other families of symbiotic bacteria succumb to environmental changes inflicted by inflammation. Here we summarize studies that examined factors in the inflamed gut that contribute to blooms of Enterobacterieaceae, and highlight potential approaches to restrict Enterobacterial blooms in treating diseases that are otherwise complicated by overgrowth of virulent Enterobacterial species in the gut. PMID:27554295

Potential impacts of blooms of the toxic dinoflagellate Karenia brevis on the growth, survival and juvenile recruitment of the non-native green mussel Perna viridis in southeastern United States.

PubMed

McFarland, Katherine; Jean, Fred; Thébault, Julien; Volety, Aswani K

2016-01-01

Red tide blooms formed by Karenia brevis are frequent along the Gulf coast of Florida and it is unclear what tolerance the green mussel Perna viridis, a recently introduced species to coastal waters, has toward these events. Established populations of P. viridis were monitored along the coastal waters of Estero Bay, Florida before, during and following two consecutive red tide blooms to assess the potential effects on growth, survival and juvenile recruitment. Upon onset of the bloom, growth rates fell from 6 to 10 mm month(-1) (March 2011-November 2011) to less than 3 mm month(-1). In the succeeding years, K. brevis blooms were present, and average growth of individually tagged mussels remained below 3 mm month(-1). During growth monitoring the use of calcein as an internal marker was tested with positive staining results and no observed effect on growth or survival. In March 2012, following the first red tide bloom, a population-wide mortality event was observed. Following this event, increased mortality rates were observed with peaks during onset of the bloom in the fall of 2012 and 2013. Juvenile recruitment was also limited during years in which blooms persisted into the spring spawning period suggesting gamete and/or larval sensitivity to K. brevis. Although it cannot be conclusively determined that the cause of reduced growth and survival is due to red tide events, the parallels observed suggest that K. brevis is a factor in the observed changes in population structure. Copyright © 2015 Elsevier Ltd. All rights reserved.

Physical control of interannual variations of the winter chlorophyll bloom in the northern Arabian Sea

NASA Astrophysics Data System (ADS)

Girijakumari Keerthi, Madhavan; Lengaigne, Matthieu; Levy, Marina; Vialard, Jerome; Parvathi, Vallivattathillam; de Boyer Montégut, Clément; Ethé, Christian; Aumont, Olivier; Suresh, Iyyappan; Parambil Akhil, Valiya; Moolayil Muraleedharan, Pillathu

2017-08-01

The northern Arabian Sea hosts a winter chlorophyll bloom, triggered by convective overturning in response to cold and dry northeasterly monsoon winds. Previous studies of interannual variations of this bloom only relied on a couple of years of data and reached no consensus on the associated processes. The current study aims at identifying these processes using both ˜ 10 years of observations (including remotely sensed chlorophyll data and physical parameters derived from Argo data) and a 20-year-long coupled biophysical ocean model simulation. Despite discrepancies in the estimated bloom amplitude, the six different remotely sensed chlorophyll products analysed in this study display a good phase agreement at seasonal and interannual timescales. The model and observations both indicate that the interannual winter bloom fluctuations are strongly tied to interannual mixed layer depth anomalies ( ˜ 0.6 to 0.7 correlation), which are themselves controlled by the net heat flux at the air-sea interface. Our modelling results suggest that the mixed layer depth control of the bloom amplitude ensues from the modulation of nutrient entrainment into the euphotic layer. In contrast, the model and observations both display insignificant correlations between the bloom amplitude and thermocline depth, which precludes a control of the bloom amplitude by daily dilution down to the thermocline depth, as suggested in a previous study.

A comprehensive overview of the spatial and temporal variability of apple bud dormancy release and blooming phenology in Western Europe

NASA Astrophysics Data System (ADS)

Legave, Jean Michel; Blanke, Michael; Christen, Danilo; Giovannini, Daniela; Mathieu, Vincent; Oger, Robert

2013-03-01

In the current context of global warming, an analysis is required of spatially-extensive and long-term blooming data in fruit trees to make up for insufficient information on regional-scale blooming changes and determinisms that are key to the phenological adaptation of these species. We therefore analysed blooming dates over long periods at climate-contrasted sites in Western Europe, focusing mainly on the Golden Delicious apple that is grown worldwide. On average, blooming advances were more pronounced in northern continental (10 days) than in western oceanic (6-7 days) regions, while the shortest advance was found on the Mediterranean coastline. Temporal trends toward blooming phase shortenings were also observed in continental regions. These regional differences in temporal variability across Western Europe resulted in a decrease in spatial variability, i.e. shorter time intervals between blooming dates in contrasted regions (8-10-day decrease for full bloom between Mediterranean and continental regions). Fitted sequential models were used to reproduce phenological changes. Marked trends toward shorter simulated durations of forcing period (bud growth from dormancy release to blooming) and high positive correlations between these durations and observed blooming dates support the notion that blooming advances and shortenings are mainly due to faster satisfaction of the heating requirement. However, trends toward later dormancy releases were also noted in oceanic and Mediterranean regions. This could tend toward blooming delays and explain the shorter advances in these regions despite similar or greater warming. The regional differences in simulated chilling and forcing periods were consistent with the regional differences in temperature increases.

Biogeochemical cycling of permeable sediments in a shelf sea environment: Celtic Sea, a seasonal study.

NASA Astrophysics Data System (ADS)

Reynolds, S.; Klar, J. K.; Kitidis, V. A.; Chapman-Greig, L.; Panton, A.; Thompson, C.; Statham, P. J.; Fones, G. R.

2016-02-01

Shelf seas are globally important in contributing to the biogeochemical cycling of carbon and nutrients. Much of the benthic environment found in shelf seas comprise of relic permeable sands whereby advective pore-water flow processes govern the biogeochemical cycling within these sediments. To further elucidate our understanding of the biogeochemistry of these systems, flow-through reactors were employed during a field campaign as part of the UK led Shelf Sea Biogeochemistry Programme. Three cruises took place in the southern Celtic Sea in 2015 and were timed to sample pre-bloom, post-bloom and late summer conditions. Preliminary data show marked differences with the pre-bloom and late summer flow-through incubations when compared with the post-bloom. Pre-bloom and late summer oxygen consumption rates ranged between 0.18 mmol O2 m-3 d-1 and 0.15 mmol O2 m-3 d-1 respectively. However, post-bloom oxygen consumption rates were almost double at 0.29 mmol O2 m-3 d-1. Differences were also observed in the amount of iron (II) being released with no marked releases from the pre-bloom and late summer but with significant contributions of up to 140 nM during the post-bloom incubation. These initial findings demonstrate the seasonal variability and extent of the biogeochemical cycling of benthic permeable sediments. Additional measurements of inorganic nutrients, dissolved organic carbon and denitrification rates will contribute further to our understanding of sandy sediments in a shelf sea environment and their capacity to act as a carbon and nutrient source or sink.

IOOS: Aiding Aquaculture Industries and Their Harvest with Near Real-Time Data

NASA Astrophysics Data System (ADS)

Kerkering, H.; Shandy Buckley; Jan Newton; Julie Thomas

2011-12-01

West Coast aquaculture accounts for over 3000 jobs and brings in over 117 million in revenue to mostly small coastal communities. Larvae recruitment and growth in these systems are very susceptible to harmful algal blooms (HABs) and acidic waters (low pH). Since 2005, aquaculturists have observed a significant reduction in shellfish larvae production and recruitment. In 2008 and 2009, the Taylor Shellfish Company (Dabob Bay, WA) observed a loss of 80% in their hatchery production. Likewise in 2008, Whiskey Creek Shellfish Company (Netarts Bay, OR) produced only 25% of their normal crop. These businesses and local scientists suspect low pH to be the culprit in the declines. In 2007, the Monterey Abalone Company suffered a 60K loss in their harvest. After contacting local scientists it was determined that the abalone crop died from a harmful algal bloom event. In response, the three West Coast Regional Associations under the U.S. Integrated Ocean Observing System (NANOOS, CeNCOOS and SCCOOS) are working in collaboration with the Ocean Science Trust, Ocean Protection Council, CA Sea Grant, NOAA National Estuarine Research Reserve Program, and the Southern California Coastal Water Research Project to develop an observing and near real-time data delivery network focused on harmful algal blooms, the Harmful Algal Bloom Monitoring Alert Program and on ocean acidification, the California Current Acidification Network. The above organizations have participated in a number of workshops with members of the aquaculture community helping to design the network. It is clear that a spatial and temporal disconnect between the data needs of both groups exists. Aquaculture experts require daily and hourly data streams in the near-shore environment with a high degree of reliability in the data but not necessarily a high degree of accuracy. Conversely, scientists collect highly accurate data in the continental shelf and oceanic environment and model predictions on decadal scales. The networks are being designed to address scientific understanding and uncertainty as well as the management needs of various stakeholder groups. Better communication and delivery of near real time data will assist aquaculture growers to predict when larvae will recruit in the natural system, when and if to relocate crops, and when to pump water in a tanks system. Though an integrated west coast observational network satellite sea surface temperature, HAB tracking systems, ocean acidification buoys, and biological monitoring programs can be pulled together into a cohesive program. A network of scientists and industry stakeholders providing and utilizing a near real time data network saves money and increases efficiency. It is not possible to prevent variability in temperature, nutrients, pH and algal blooms, but increasing understanding will lead to more accurate predictions, and ultimately, better human adaptation to the harmful economic impacts of HABs and ocean acidification.

Bloom termination of the toxic dinoflagellate Alexandrium catenella: Vertical migration behavior, sediment infiltration, and benthic cyst yield.

PubMed

Brosnahan, Michael L; Ralston, David K; Fischer, Alexis D; Solow, Andrew R; Anderson, Donald M

2017-11-01

New resting cyst production is crucial for the survival of many microbial eukaryotes including phytoplankton that cause harmful algal blooms. Production in situ has previously been estimated through sediment trap deployments, but here was instead assessed through estimation of the total number of planktonic cells and new resting cysts produced by a localized, inshore bloom of Alexandrium catenella , a dinoflagellate that is a globally important cause of paralytic shellfish poisoning. Our approach utilizes high frequency, automated water monitoring, weekly observation of new cyst production, and pre- and post-bloom spatial surveys of total resting cyst abundance. Through this approach, new cyst recruitment within the study area was shown to account for at least 10.9% ± 2.6% (SE) of the bloom's decline, ∼ 5× greater than reported from comparable, sediment trap based studies. The observed distribution and timing of new cyst recruitment indicate that: (1) planozygotes, the immediate precursor to cysts in the life cycle, migrate nearer to the water surface than other planktonic stages and (2) encystment occurs after planozygote settlement on bottom sediments. Near surface localization by planozygotes explains the ephemerality of red surface water discoloration by A. catenella blooms, and also enhances the dispersal of new cysts. Following settlement, bioturbation and perhaps active swimming promote sediment infiltration by planozygotes, reducing the extent of cyst redistribution between blooms. The concerted nature of bloom sexual induction, especially in the context of an observed upper limit to A. catenella bloom intensities and heightened susceptibility of planozygotes to the parasite Amoebophrya , is also discussed.

The efficiency of combined coagulant and ballast to remove harmful cyanobacterial blooms in a tropical shallow system.

PubMed

Miranda, Marcela; Noyma, Natália; Pacheco, Felipe S; de Magalhães, Leonardo; Pinto, Ernani; Santos, Suzan; Soares, Maria Fernanda A; Huszar, Vera L; Lürling, Miquel; Marinho, Marcelo M

2017-05-01

We tested the hypothesis that a combination of coagulant and ballast could be efficient for removal of positively buoyant harmful cyanobacteria in shallow tropical waterbodies, and will not promote the release of cyanotoxins. This laboratory study examined the efficacy of coagulants [polyaluminium chloride (PAC) and chitosan (made of shrimp shells)] alone, and combined with ballast (lanthanum modified bentonite, red soil or gravel) to remove the natural populations of cyanobacteria collected from a shallow eutrophic urban reservoir with alternating blooms of Cylindrospermopsis and Microcystis. PAC combined with ballast was effective in settling blooms dominated by Microcystis or Cylindrospermopsis. Contrary to our expectation, chitosan combined with ballast was only effective in settling Cylindrospermopsis-dominated blooms at low pH, whereas at pH≥8 no effective flocculation and settling could be evoked. Chitosan also had a detrimental effect on Cylindrospermopsis causing the release of saxitoxins. In contrast, no detrimental effect on Microcystis was observed and all coagulant-ballast treatments were effective in not only settling the Microcystis dominated bloom, but also lowering dissolved microcystin concentrations. Our data show that the best procedure for biomass reduction also depends on the dominant species. Copyright © 2017 Elsevier B.V. All rights reserved.

Diatom resting spore ecology drives enhanced carbon export from a naturally iron-fertilized bloom in the Southern Ocean

NASA Astrophysics Data System (ADS)

Salter, Ian; Kemp, Alan E. S.; Moore, C. Mark; Lampitt, Richard S.; Wolff, George A.; Holtvoeth, Jens

2012-03-01

Southern Ocean Island systems sustain phytoplankton blooms induced by natural iron fertilization that are important for the uptake of atmospheric carbon dioxide and serve as analogues for past and future climate change. We present data on diatom flux assemblages and the biogeochemical properties of sinking particles to explain the enhanced particulate organic carbon (POC) export fluxes observed in response to natural iron supply in the Crozet Islands region (CROZeX). Moored deep-ocean sediment traps (>2000 m) were located beneath a naturally fertilized island bloom and beneath an adjacent High Nutrient Low Chlorophyll (HNLC) control site. Deep-ocean carbon flux from the naturally-fertilized bloom area was tightly correlated (R = 0.83, n = 12, P < 0.0006) with the resting spore flux of a single island-associated diatom species,Eucampia antarctica var. antarctica. The unusually well preserved state of the Eucampia-associated carbon flux, determined by amino acid studies of organic matter degradation, was likely influenced by their ecology, since diatom resting spores are adapted to settle rapidly out of the surface ocean preserving viable cells. The naturally fertilized bloom enhanced carbon flux and the resulting Si/C and Si/N ratios were 2.0-3.4-fold and 2.2-3.5-fold lower than those measured in the adjacent HNLC control area. The enhanced carbon export and distinctive stoichiometry observed in naturally fertilized systems is therefore largely not attributable to iron relief of open ocean diatoms, but rather to the advection and growth of diatom species characteristic of island systems and the subsequent flux of resting spores. Carbon export estimates from current natural iron fertilization studies therefore represent a highly specific response of the island systems chosen as natural laboratories and may not be appropriate analogues for the larger Southern Ocean response. The broader implications of our results emphasize the role of phytoplankton diversity and ecology and highlight the need for a species-centered approach in order to understand the regulation of biogeochemical fluxes.

The 2008 North Atlantic Spring Bloom Experiment I: Overview and Strategy

NASA Astrophysics Data System (ADS)

D'Asaro, E. A.; Lee, C.; Perry, M.; Fennel, K.; Rehm, E.; Gray, A.; Briggs, N.; Gudmundsson, K.

2008-12-01

The 2008 North Atlantic Spring Bloom Experiment (NAB08) aimed to understand carbon export from this globally important event by combining a new generation of autonomous floats and gliders equipped with a new generation of sensors, and traditional and modern shipboard observational methods. Measurements were made from early April to late June 2008 in a region southeast of Iceland near the JGOFS and MLML sites. Although Sverdrup's classical explanation for the bloom is probably broadly correct, previous observations have revealed a large degree of spatial and temporal variability, often on scales of a few kilometers, which have made detailed tests of Sverdrup's hypothesis difficult. The experiment was designed to continuously sample the bloom and its temporal and spatial 'patchiness' from the pre-bloom, wintertime conditions through the Spring and early Summer. The spatial scales were sampled by 4 Seagliders operating together as a mobile array. Measurements were made in a Lagrangian, water-following coordinate system which minimized the effects of horizontal advection and most clearly separated temporal and spatial scales. The coordinate system was defined by two Lagrangian Floats, one of which was chosen as the center of the Seaglider array. Proper measurement of the bloom by the autonomous vehicles required a robust and redundant array of sensors measuring key physical, chemical and biological variables including temperature, salinity, spectral light, oxygen, multiple optical proxies for carbon (chlorophyll fluorescence, beam-c attenuation and optical backscatter coefficients) and nitrate. Redundant measurements were made whenever possible, with nearly identical sensors on many platforms and multiple sensors measuring similar quantities on the same platform. Such care is clearly necessary, since the current generation of biogeochemical sensor require considerable efforts in calibration and interpretation. The autonomous platforms provided good coverage in space and time, but could not sample the entire range of processes that control the bloom. More detailed measurements and multiple calibrations of the autonomous platforms were made on 4 cruises, particularly a 21-day Knorr cruise in May 2008 that included collaborators from five US and five international institutions. These measurements included nutrients; particulate organic carbon and nitrogen; characterization of plankton composition and physiology by size, imaging, genomics, HPLC pigments, absorption spectra, 14C-primary productivity, and variable fluorescence; particle flux from floating sediment traps; and ADCP and CTD measurements. The experiment clearly demonstrated the ability of autonomous platforms to make biogeochemically relevant measurements of blooms. Its success, however, required intensive shipboard support for sensor calibration and interpretation. Further development of sensor technology, validation protocols, and understanding is clearly required if these measurements are to made routinely and easily.

A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem

NASA Astrophysics Data System (ADS)

Montero, P.; Pérez-Santos, I.; Daneri, G.; Gutiérrez, M. H.; Igor, G.; Seguel, R.; Purdie, D.; Crawford, D. W.

2017-12-01

A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3‧S; 72°43.6‧W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13-58 × 109 cell m-2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6-1.6 g C m-2 d-1) and chlorophyll-a concentration (Chl-a; 70-199.2 mg m-2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter. Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = -0.8, p < 0.05) with a decrease in salinity/temperature and the presence of the Heterocapsa bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter.

Predicting Sargassum blooms in the Caribbean Sea from MODIS observations

NASA Astrophysics Data System (ADS)

Wang, Mengqiu; Hu, Chuanmin

2017-04-01

Recurrent and significant Sargassum beaching events in the Caribbean Sea (CS) have caused serious environmental and economic problems, calling for a long-term prediction capacity of Sargassum blooms. Here we present predictions based on a hindcast of 2000-2016 observations from Moderate Resolution Imaging Spectroradiometer (MODIS), which showed Sargassum abundance in the CS and the Central West Atlantic (CWA), as well as connectivity between the two regions with time lags. This information was used to derive bloom and nonbloom probability matrices for each 1° square in the CS for the months of May-August, predicted from bloom conditions in a hotspot region in the CWA in February. A suite of standard statistical measures were used to gauge the prediction accuracy, among which the user's accuracy and kappa statistics showed high fidelity of the probability maps in predicting both blooms and nonblooms in the eastern CS with several months of lead time, with overall accuracy often exceeding 80%. The bloom probability maps from this hindcast analysis will provide early warnings to better study Sargassum blooms and prepare for beaching events near the study region. This approach may also be extendable to many other regions around the world that face similar challenges and opportunities of macroalgal blooms and beaching events.

Life-history stages of natural bloom populations and the bloom dynamics of a tropical Asian ribotype of Alexandrium minutum.

PubMed

Lau, Winnie Lik Sing; Law, Ing Kuo; Liow, Guat Ru; Hii, Kieng Soon; Usup, Gires; Lim, Po Teen; Leaw, Chui Pin

2017-12-01

In 2015, a remarkably high density bloom of Alexandrium minutum occurred in Sungai Geting, a semi-enclosed lagoon situated in the northeast of Peninsular Malaysia, causing severe discoloration and contaminated the benthic clams (Polymesoda). Plankton and water samples were collected to investigate the mechanisms of bloom development of this toxic species. Analysis of bloom samples using flow cytometry indicated that the bloom was initiated by the process of active excystment, as planomycetes (>4C cells) were observed in the early stage of the bloom. Increase in planozygotes (2C cells) was evident during the middle stage of the bloom, coinciding with an abrupt decrease in salinity and increase of temperature. The bloom was sustained through the combination of binary division of vegetative cells, division of planozygotes, and cyst germination through continuous excystment. Nutrient depletion followed by precipitation subsequently caused the bloom to terminate. This study provides the first continuous record of in situ life-cycle stages of a natural bloom population of A. minutum through a complete bloom cycle. The event has provided a fundamental understanding of the pelagic life-cycle stages of this tropical dinoflagellate, and demonstrated a unique bloom development characteristic shared among toxic Alexandrium species in coastal embayments. Copyright © 2017 Elsevier B.V. All rights reserved.

Cyanobacteria blooms: effects on aquatic ecosystems.

PubMed

Havens, Karl E

2008-01-01

Cyanobacteria become increasingly dominant as concentrations of TP and TN increase during eutrophication of lakes, rivers and estuaries. Temporal dynamics of cyanobacteria blooms are variable--in some systems persistent blooms occur in summer to fall, whereas in other systems blooms are more sporadic. Cyanobacteria blooms have a wide range of possible biological impacts including potential toxic effects on other algae, invertebrates and fish, impacts to plants and benthic algae due to shading, and impacts to food web function as large inedible algae produce a bottleneck to C and energy flow in the plankton food web. In lakes with dense blooms of cyanobacteria, accumulation of organic material in lake sediments and increased bacterial activity also may lead to anoxic conditions that alter the structure of benthic macro-invertebrates. Diffusive internal P loading may increase, and hypolimnetic anoxia may lead to a loss of piscivorous fish that require a summer cold water refuge in temperate lakes. Ecosystem changes associated with frequent blooms may result in delayed response of lakes, rivers and estuaries to external nutrient load reduction. Despite numerous case studies and a vast literature on species-specific responses, community level effects of cyanobacterial blooms are not well understood--in particular the realized impacts of toxins and changes in food web structure/function. These areas require additional research given the prevalence of toxic blooms in the nation's lakes, rivers and coastal waters--systems that provide a wide range of valued ecosystem services.

[Comparison of the botanic morphology and blooming characteristics of four cultivars of rose].

PubMed

Wang, Kang-cai; Tang, Xiao-qing; Sheng, Min-li; Xu, Xiao-lan; Fang, Zhen

2004-05-01

To establish identifying method for further development and utilization by studying botanic morphology and blooming characteristics of four varieties of roses in Jiangsu province. Flower-bud and flower-form were observed by dissection and plant modality and blooming process were investigated. The flower form and plant modality was obviously different among the 4 varieties of roses. The process of differentiation of flower-bud could be divided into five stages: the transformation of nutritive growth cone, the occurrence and development of sepal, formation of petal primordium, formation of pistil and stamen. The blooming process was made up of flower-bud period, display-petal period, initiating blooming period, blooming period, withering period and corresponding biological marks.

Harmful Algal Bloom Hotspots Really Are Hot: A Case Study from Monterey Bay, California

NASA Astrophysics Data System (ADS)

Kudela, R. M.; Anderson, C.; Birch, J. M.; Bowers, H.; Caron, D. A.; Chao, Y.; Doucette, G.; Farrara, J. D.; Gellene, A. G.; Negrey, K.; Howard, M. D.; Ryan, J. P.; Scholin, C. A.; Smith, J.; Sukhatme, G.

2015-12-01

Monterey Bay, California is one of several recognized hotspots for harmful algal blooms along the US west coast, particularly for the toxigenic diatom Pseudo-nitzschia, which produces domoic acid and is responsible for Amnesic Shellfish Poisoning. Historical observations have linked bloom activity to anomalously warm conditions with weak and sporadic upwelling. In particular, blooms appear to be associated with El Niño conditions. Monterey, as with much of the US west coast, experienced unusual warm conditions in spring and summer 2014, leading to multiple ecosystem effects including massive algal blooms, concentration of apex predators nearshore, and unusually high levels of domoic acid. As the warm anomalies continued and strengthened into 2015, Monterey (and much of the west coast) has been experiencing the largest and most toxic algal bloom recorded in the last 15 years, as well as unprecedented coccolithophore blooms associated with warm, nutrient-depleted waters. With the strengthening El Niño conditions developing in summer 2015, it is possible that 2016 will result in a third consecutive year of unusually toxic algal blooms. Using a combination of historical observations, intensive field studies, and predictive models we explore the hypothesis that these warm anomalies lead to shifts in the typical upwelling-dominated food web leading to a collapse of the ecosystem towards the coast, unusual algal blooms, and enhanced trophic transfer of toxins, resulting in magnified negative impacts to wildlife and, potentially, humans.

Characterisation of a major phytoplankton bloom in the River Thames (UK) using flow cytometry and high performance liquid chromatography.

PubMed

Moorhouse, H L; Read, D S; McGowan, S; Wagner, M; Roberts, C; Armstrong, L K; Nicholls, D J E; Wickham, H D; Hutchins, M G; Bowes, M J

2018-05-15

Recent river studies have observed rapid phytoplankton dynamics, driven by diurnal cycling and short-term responses to storm events, highlighting the need to adopt new high-frequency characterisation methods to understand these complex ecological systems. This study utilised two such analytical methods; pigment analysis by high performance liquid chromatography (HPLC) and cell counting by flow cytometry (FCM), alongside traditional chlorophyll spectrophotometry and light microscopy screening, to characterise the major phytoplankton bloom of 2015 in the River Thames, UK. All analytical techniques observed a rapid increase in chlorophyll a concentration and cell abundances from March to early June, caused primarily by a diatom bloom. Light microscopy identified a shift from pennate to centric diatoms during this period. The initial diatom bloom coincided with increased HPLC peridinin concentrations, indicating the presence of dinoflagellates which were likely to be consuming the diatom population. The diatom bloom declined rapidly in early June, coinciding with a storm event. There were low chlorophyll a concentrations (by both HPLC and spectrophotometric methods) throughout July and August, implying low biomass and phytoplankton activity. However, FCM revealed high abundances of pico-chlorophytes and cyanobacteria through July and August, showing that phytoplankton communities remain active and abundant throughout the summer period. In combination, these techniques are able to simultaneously characterise a wider range of phytoplankton groups, with greater certainty, and provide improved understanding of phytoplankton functioning (e.g. production of UV inhibiting pigments by cyanobacteria in response to high light levels) and ecological status (through examination of pigment degradation products). Combined HPLC and FCM analyses offer rapid and cost-effective characterisation of phytoplankton communities at appropriate timescales. This will allow a more-targeted use of light microscopy to capture phytoplankton peaks or to investigate periods of rapid community succession. This will lead to greater system understanding of phytoplankton succession in response to biogeochemical drivers. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Succession of Pelagic Organisms in the Size Range 0·5-200 μm During a Diatom Bloom in Otsuchi Bay, Japan

NASA Astrophysics Data System (ADS)

Tsuda, Atsushi; Sugisaki, Hiroya; Takahashi, Koji; Furuya, Ken

1994-08-01

The succession of pelagic organisms in the approximate size range 0·5-200 μm was investigated during a spring diatom bloom in Otsuchi Bay on the Pacific coast of northern Japan. The diatom bloom lasted 3 weeks in the middle of the period examined. The study period was divided into three phases: pre-bloom, bloom and post-bloom. Mesodinium rubrum, an autotrophic ciliate, was abundant in the pre-bloom phase, when vertical mixing was intense. During the bloom phase, the biomass of organisms other than diatoms themselves and bacteria was depressed. A bacterial peak was observed 4 days after the diatom peak and peaks of nano-autotrophs and -heterotrophs occurred after 14 days. Phototrophic picoplankton showed a biomass peak at the same time as nanoplankton. Grazing on diatoms by the copepod population was shown by the occurrences of faecal pellets and copepod nauplii during and after the bloom phase. These results suggest that production of copepods and bacteria depended only on the diatom bloom directly, and that heterotrophic micro-protista depended on the production of pico- and nano-autotrophs in the post-bloom phase.

Summer diatom blooms in the North Pacific subtropical gyre: 2008-2009.

PubMed

Villareal, Tracy A; Brown, Colbi G; Brzezinski, Mark A; Krause, Jeffrey W; Wilson, Cara

2012-01-01

The summertime North Pacific subtropical gyre has widespread phytoplankton blooms between Hawaii and the subtropical front (∼30°N) that appear as chlorophyll (chl) increases in satellite ocean color data. Nitrogen-fixing diatom symbioses (diatom-diazotroph associations: DDAs) often increase 10(2)-10(3) fold in these blooms and contribute to elevated export flux. In 2008 and 2009, two cruises targeted satellite chlorophyll blooms to examine DDA species abundance, chlorophyll concentration, biogenic silica concentration, and hydrography. Generalized observations that DDA blooms occur when the mixed layer depth is < 70 m are supported, but there is no consistent relationship between mixed layer depth, bloom intensity, or composition; regional blooms between 22-34°N occur within a broader temperature range (21-26°C) than previously reported. In both years, the Hemiaulus-Richelia and Rhizosolenia-Richelia DDAs increased 10(2)-10(3) over background concentrations within satellite-defined bloom features. The two years share a common trend of Hemiaulus dominance of the DDAs and substantial increases in the >10 µm chl a fraction (∼40-90+% of total chl a). Integrated diatom abundance varied 10-fold over <10 km. Biogenic silica concentration tracked diatom abundance, was dominated by the >10 µm size fraction, and increased up to 5-fold in the blooms. The two years differed in the magnitude of the surface chl a increase (2009>2008), the abundance of pennate diatoms within the bloom (2009>2008), and the substantially greater mixed layer depth in 2009. Only the 2009 bloom had sufficient chl a in the >10 µm fraction to produce the observed ocean color chl increase. Blooms had high spatial variability; ocean color images likely average over numerous small events over time and space scales that exceed the individual event scale. Summertime DDA export flux noted at the Hawaii time-series Sta. ALOHA is probably a generalized feature of the eastern N. Pacific north to the subtropical front.

Subtle reproductive impairment through nitric oxide-mediated mechanisms in sea urchins from an area affected by harmful algal blooms

PubMed Central

Migliaccio, Oriana; Castellano, Immacolata; Di Cioccio, Davide; Tedeschi, Gabriella; Negri, Armando; Cirino, Paola; Romano, Giovanna; Zingone, Adriana; Palumbo, Anna

2016-01-01

The health of the sea urchin Paracentrotus lividus, a key species in the Mediterranean Sea, is menaced by several pressures in coastal environments. Here, we aimed at assessing the reproductive ability of apparently healthy P. lividus population in a marine protected area affected by toxic blooms of Ostreospsis cf. ovata. Wide-ranging analyses were performed in animals collected prior to and during the bloom, as well as at several times thereafter, during the reproductive season. Adults showed a low fertilization rate, along with high nitric oxide (NO) levels in the gonads and the nitration of the major yolk protein toposome, which is an important player in sea urchin development. Serious developmental anomalies were observed in the progeny, which persist several months after the bloom. NO levels were high in the different developmental stages, which also showed variations in the transcription of several genes that were found to be directly or indirectly modulated by NO. These results highlight subtle but important reproductive flaws transmitted from the female gonads to the offspring with the NO involvement. Despite a recovery along time after the bloom, insidious damages can be envisaged in the local sea urchin population, with possible reverberation on the whole benthic system. PMID:27192939

Subtle reproductive impairment through nitric oxide-mediated mechanisms in sea urchins from an area affected by harmful algal blooms

NASA Astrophysics Data System (ADS)

Migliaccio, Oriana; Castellano, Immacolata; di Cioccio, Davide; Tedeschi, Gabriella; Negri, Armando; Cirino, Paola; Romano, Giovanna; Zingone, Adriana; Palumbo, Anna

2016-05-01

The health of the sea urchin Paracentrotus lividus, a key species in the Mediterranean Sea, is menaced by several pressures in coastal environments. Here, we aimed at assessing the reproductive ability of apparently healthy P. lividus population in a marine protected area affected by toxic blooms of Ostreospsis cf. ovata. Wide-ranging analyses were performed in animals collected prior to and during the bloom, as well as at several times thereafter, during the reproductive season. Adults showed a low fertilization rate, along with high nitric oxide (NO) levels in the gonads and the nitration of the major yolk protein toposome, which is an important player in sea urchin development. Serious developmental anomalies were observed in the progeny, which persist several months after the bloom. NO levels were high in the different developmental stages, which also showed variations in the transcription of several genes that were found to be directly or indirectly modulated by NO. These results highlight subtle but important reproductive flaws transmitted from the female gonads to the offspring with the NO involvement. Despite a recovery along time after the bloom, insidious damages can be envisaged in the local sea urchin population, with possible reverberation on the whole benthic system.

Physical and Biogeochemical Controls of the Phytoplankton Blooms in North Western Mediterranean Sea: A Multiplatform Approach Over a Complete Annual Cycle (2012-2013 DEWEX Experiment)

NASA Astrophysics Data System (ADS)

Mayot, Nicolas; D'Ortenzio, Fabrizio; Taillandier, Vincent; Prieur, Louis; de Fommervault, Orens Pasqueron; Claustre, Hervé; Bosse, Anthony; Testor, Pierre; Conan, Pascal

2017-12-01

The North Western Mediterranean Sea exhibits recurrent and significant autumnal and spring phytoplankton blooms. The existence of these two blooms coincides with typical temperate dynamics. To determine the potential control of physical and biogeochemical factors on these phytoplankton blooms, data from a multiplatform approach (combining ships, Argo and BGC-Argo floats, and bio-optical gliders) were analyzed in association with satellite observations in 2012-2013. The satellite framework allowed a simultaneous analysis over the whole annual cycle of in situ observations of mixed layer depth, photosynthetical available radiation, particle backscattering, nutrients (nitrate and silicate), and chlorophyll-a concentrations. During the year 2012-2013, satellite ocean color observations, confirmed by in situ data, have revealed the existence of two areas (or bioregions) with comparable autumnal blooms but contrasting spring blooms. In both bioregions, the ratio of the euphotic zone (defined as the isolume 0.415 mol photons m-2 d-1, Z0.415) and the MLD identified the initiation of the autumnal bloom, as well as the maximal annual increase in [Chl-a] in spring. In fact, the autumnal phytoplankton bloom might be initiated by mixing of the summer shallowing deep chlorophyll maximum, while the spring restratification (when Z0.415/MLD ratio became >1) might induce surface phytoplankton production that largely overcomes the losses. Finally, winter deep convection events that took place in one of the bioregions induced higher net accumulation rate of phytoplankton in spring associated with a diatom-dominated phytoplankton community principally. We suggest that very deep winter MLD lead to an increase in surface silicates availability, which favored the development of diatoms.

Blooms and subsurface phytoplankton layers on the Scotian Shelf: Insights from profiling gliders

NASA Astrophysics Data System (ADS)

Ross, Tetjana; Craig, Susanne E.; Comeau, Adam; Davis, Richard; Dever, Mathieu; Beck, Matthew

2017-08-01

Understanding how phytoplankton respond to their physical environment is key to predicting how bloom dynamics might change under future climate change scenarios. Phytoplankton are at the base of most marine food webs and play an important role in drawing CO2 out of the atmosphere. Using nearly 5 years of simultaneous CTD, irradiance, chlorophyll a fluorescence and optical backscattering observations obtained from Slocum glider missions, we observed the subsurface phytoplankton populations across the Scotian Shelf, near Halifax (Nova Scotia, Canada) along with their physical environment. Bloom conditions were observed in each of the 5 springs, with the average chlorophyll in the upper 60 m of water generally exceeding 3 mg m- 3. These blooms occurred when the upper water column stratification was at its lowest, in apparent contradiction of the critical depth hypothesis. A subsurface chlorophyll layer was observed each summer at about 30 m depth, which was below the base of the mixed layer. This subsurface layer lasted 3-4 months and contained, on average, 1/4 of the integrated water column chlorophyll found during the spring bloom. This suggests that a significant portion of the primary productivity over the Scotian Shelf occurs at depths that cannot be observed by satellites-highlighting the importance of including subsurface observations in the monitoring of future changes to primary productivity in the ocean.

Satellite and hydrographic observations of the Bering Sea ‘Green Belt’

NASA Astrophysics Data System (ADS)

Okkonen, Stephen R.; Schmidt, G. M.; Cokelet, E. D.; Stabeno, P. J.

2004-05-01

Green Belt is the aptly named region of high productivity occurring principally along and above the shelf-slope boundary in the Bering Sea. TOPEX altimeter measurements of sea-surface topography, SeaWiFS imagery of chlorophyll a concentration, and shipboard measurements of salinity and fluorescence are used to describe the surface structure of the Green Belt and its relationship to the Bering Slope Current eddy field during the 2000, 2001, and 2002 spring blooms. During spring 2000, high surface chlorophyll a concentrations (>10 mg m -3) were observed within a ˜200-km wide band adjacent to and seaward of the shelf break in the northwest Bering Sea. This high concentration chlorophyll band was associated with an anticyclonic eddy group that propagated along isobaths above the continental slope and entrained chlorophyll from the shelf-slope front. During spring 2001, anticyclonic eddies in the northwest Bering Sea had propagated off-slope prior to the onset of the spring bloom and were too far from the shelf-slope front to entrain frontal chlorophyll during the bloom. A second chlorophyll front associated with the leading edge of the off-slope eddies was observed. Between these two fronts was a region of relatively low chlorophyll a concentration (˜1 mg m -3). The eddy field during the 2002 spring bloom was observed to propagate northwestward adjacent to the shelf-break and entrain chlorophyll from the shelf-slope region in a manner similar to what was observed during the 2000 spring bloom. These observations suggest that eddies are important, if not the principal, agents that cause variability in the distribution of chlorophyll during the spring bloom in the central Bering Sea.

The observed cooling effect of desert blooms based on high-resolution Moderate Resolution Imaging Spectroradiometer products

NASA Astrophysics Data System (ADS)

He, Bin; Huang, Ling; Liu, Junjie; Wang, Haiyan; Lż, Aifeng; Jiang, Weiguo; Chen, Ziyue

2017-05-01

Desert greening through planting or irrigation is a potential approach to mitigate desertification and climate warming, but its influence on regional climate is unclear due to scarcity of observations. "Desert blooms," which are natural phenomena usually associated with the El Niño-Southern Oscillation, regularly occur in the world's driest desert, the Atacama Desert. This sudden conversion of land cover likely has a large impact on regional climate through alteration of local energy budgets and provides a unique opportunity to study the potential climatic and environmental consequences of desert greening. Here we evaluated the land surface effects of blooms in the Atacama Desert using vegetation and climate data acquired from remote sensing. The rapid vegetation growth during blooms led to an increase in evapotranspiration and a decrease in albedo. These two processes caused a 0.31°C ± 0.05°C decrease in daytime land surface temperature. During nighttime, we observed a 0.02°C ± 0.02°C increase in land surface temperature due to enhanced heat capacity associated with blooms. This asymmetric diurnal variation in land surface temperature produced a net decrease in daily land surface temperature of 0.29°C ± 0.07°C. Our observations demonstrate the potential benefits of desert blooms on local climate. Results from this study also provide new evidence for plausible climate consequences expected from local "desert greening" strategies.

Analysis of algal bloom risk with uncertainties in lakes by integrating self-organizing map and fuzzy information theory.

PubMed

Chen, Qiuwen; Rui, Han; Li, Weifeng; Zhang, Yanhui

2014-06-01

Algal blooms are a serious problem in waters, which damage aquatic ecosystems and threaten drinking water safety. However, the outbreak mechanism of algal blooms is very complex with great uncertainty, especially for large water bodies where environmental conditions have obvious variation in both space and time. This study developed an innovative method which integrated a self-organizing map (SOM) and fuzzy information diffusion theory to comprehensively analyze algal bloom risks with uncertainties. The Lake Taihu was taken as study case and the long-term (2004-2010) on-site monitoring data were used. The results showed that algal blooms in Taihu Lake were classified into four categories and exhibited obvious spatial-temporal patterns. The lake was mainly characterized by moderate bloom but had high uncertainty, whereas severe blooms with low uncertainty were observed in the northwest part of the lake. The study gives insight on the spatial-temporal dynamics of algal blooms, and should help government and decision-makers outline policies and practices on bloom monitoring and prevention. The developed method provides a promising approach to estimate algal bloom risks under uncertainties. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of Karenia brevis blooms on the West Florida Shelf using ocean color satellite imagery: implications for bloom maintenance and evolution

NASA Astrophysics Data System (ADS)

Soto, Inia M.; Muller-Karger, Frank E.; Hu, Chuanmin; Wolny, Jennifer

2017-01-01

Satellite ocean color remote sensing techniques, coupled with in situ data, were used to examine the spatial extent and evolution of four Karenia brevis blooms on the West Florida Shelf (WFS) in 2004, 2005, 2006, and 2011. Observations were obtained with the moderate resolution imaging spectroradiometer (MODIS-Aqua). These four blooms were delineated by combining remote-sensing reflectance at 555 nm and normalized fluorescence line height. In 2004 and 2005, the WFS was affected by several hurricanes, including the category 5 storm Hurricane Katrina. These hurricanes led to increased river discharge and vertical mixing which favored bloom intensification and dispersion. No hurricanes passed over the WSF in 2006; however, storms in south Florida may have aided bloom intensification via increased river discharge. In 2011, a bloom appeared off Venice, Florida, where several small creeks discharge. The bloom moved south toward Charlotte Harbor where it intensified and lingered for several months as it received nutrients from riverine discharge and upwelling events. While it is difficult to identify initiation stages of a K. brevis bloom (<˜50,000 cells L-1) using satellite imagery, the techniques used here provide information about bloom evolution (size, duration, and advection) and insight into factors affecting bloom dynamics.

Applications of MODIS Fluorescence Line Height Measurements to Monitor Water Quality Trends and Algal Bloom Activity in Coastal and Estuarine Waters

NASA Astrophysics Data System (ADS)

Fischer, A.; Ryan, J. P.; Moreno-Madriñán, M. J.

2012-12-01

Recent advances in satellite and airborne remote sensing, such as improvements in sensor and algorithm calibrations and atmospheric correction procedures have provided for increased coverage of remote-sensing, ocean color products for coastal regions. In particular, for the Moderate Resolution Imaging Spectrometer (MODIS), calibration updates, improved aerosol retrievals, and new aerosol models have led to improved atmospheric correction algorithms for turbid waters and have improved the retrieval of ocean-color. This has opened the way for studying coastal ocean phenomena and processes at finer spatial scales. Human population growth and changes in coastal management practices have brought about significant changes in the concentrations of organic and inorganic, particulate and dissolved substances entering the coastal ocean. There is increasing concern that these inputs have led to declines in water quality and increases in local concentrations of phytoplankton, which could result in harmful algal blooms. In two case studies we present improved and validated MODIS coastal observations of fluorescence line height (FLH) to: (1) assess trends in water quality for Tampa Bay, Florida; and (2) illustrate seasonal and annual variability of algal bloom activity in Monterey Bay, California, as well as document estuarine/riverine plume induced red tide events. In a comprehensive analysis of long term (2003-2011) in situ monitoring data and imagery from Tampa Bay, we assess the validity of the MODIS FLH product against chlorophyll-a and a suite of water quality parameters taken in a variety of conditions throughout this large, optically complex estuarine system. A systematic analysis of sampling sites throughout the bay illustrates that the correlations between FLH and in situ chlorophyll-a are influenced by water quality parameters of total nitrogen, total phosphorous, turbidity and biological oxygen demand. Sites that correlated well with satellite imagery were in depths greater than seven meters and were located over five kilometers from shore. Satellite FLH estimates show improving water quality from 2003-2007 with a slight decline up through 2011. Dinoflagellate blooms in Monterey Bay, California have recently increased in frequency and intensity. Nine years of MODIS FLH observations are used to describe the annual and seasonal variability of bloom activity within the Bay. Three classes of MODIS algorithms were correlated against in situ chlorophyll measurements. The FLH algorithm provided the most robust estimate of bloom activity. Elevated concentrations of phytoplankton were evident during the months of August-November, a period during which increased occurrences of dinoflagellate blooms have been observed in situ. Seasonal patterns of FLH show the on- and offshore movement of areas of high phytoplankton biomass between oceanographic seasons. Higher concentrations of phytoplankton are also evident in the vicinity of the land-based nutrient sources and outflows, and cyclonic bay-wide circulation transports these nutrients to a northern Bay bloom incubation region. Both of these case studies illustrate the utility of improved MODIS FLH observations in supporting management decisions in coastal and estuarine waters.

Spring Blooms Observed with Biochemical Profiling Floats from a Chemical and Biological Perspective

NASA Astrophysics Data System (ADS)

Plant, J. N.; Johnson, K. S.; Sakamoto, C.; Jannasch, H. W.; Coletti, L. J.; Elrod, V.

2015-12-01

Recently there has been renewed interest in the mechanisms which control the seasonal increases in plankton biomass (spring blooms). Changes in physical and chemical forcing (light, wind, heat and nutrients) may increase the specific growth rate of phytoplankton. These changes may also shift the predator - prey relationships within the food web structure, which can alter the balance between plankton growth and loss rates. Biogeochemical profiling floats provide a means to observe the seasonal evolution of spring blooms from a physical, chemical and biological perspective in near real time. Floats equipped with optical sensors to measure nitrate, oxygen, chlorophyll fluorescence, and optical backscatter now have a presence in many ocean regions including the North Pacific, Subarctic Pacific, North Atlantic, South Atlantic and the Southern Ocean. Data from these regions are used to compare and contrast the evolution of spring blooms. The evolution of the bloom is examined using both chemical (oxygen, nitrate) and biooptical (phytoplankton from chlorophyll fluorescence and particulate organic carbon from optical backscatter) sensors under vastly different environmental conditions.

Responding to Harmful Algal Blooms in Wyoming and on Tribal Lands in EPA Region 8

EPA Pesticide Factsheets

The Harmful Algal Blooms – Special Sampling and Response Actions webpage contains information about Background on Harmful Algae in Surface Waters and What to Do if Your System Has Indicators of an Algal Bloom.

Human Health Effects Associated with Exposure to Toxic Cyanobacteria

EPA Science Inventory

Reports of toxic cyanobacteria blooms are increasing worldwide. Warming and eutrophic surface water systems support the development of blooms. We examine the evidence for adverse human health effects associated with exposure to toxic blooms in drinking water, recreational water a...

Modeling pore corrosion in normally open gold- plated copper connectors.

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

Battaile, Corbett Chandler; Moffat, Harry K.; Sun, Amy Cha-Tien

2008-09-01

The goal of this study is to model the electrical response of gold plated copper electrical contacts exposed to a mixed flowing gas stream consisting of air containing 10 ppb H{sub 2}S at 30 C and a relative humidity of 70%. This environment accelerates the attack normally observed in a light industrial environment (essentially a simplified version of the Battelle Class 2 environment). Corrosion rates were quantified by measuring the corrosion site density, size distribution, and the macroscopic electrical resistance of the aged surface as a function of exposure time. A pore corrosion numerical model was used to predict bothmore » the growth of copper sulfide corrosion product which blooms through defects in the gold layer and the resulting electrical contact resistance of the aged surface. Assumptions about the distribution of defects in the noble metal plating and the mechanism for how corrosion blooms affect electrical contact resistance were needed to complete the numerical model. Comparisons are made to the experimentally observed number density of corrosion sites, the size distribution of corrosion product blooms, and the cumulative probability distribution of the electrical contact resistance. Experimentally, the bloom site density increases as a function of time, whereas the bloom size distribution remains relatively independent of time. These two effects are included in the numerical model by adding a corrosion initiation probability proportional to the surface area along with a probability for bloom-growth extinction proportional to the corrosion product bloom volume. The cumulative probability distribution of electrical resistance becomes skewed as exposure time increases. While the electrical contact resistance increases as a function of time for a fraction of the bloom population, the median value remains relatively unchanged. In order to model this behavior, the resistance calculated for large blooms has been weighted more heavily.« less

A major seasonal phytoplankton bloom in the Madagascar Basin

NASA Astrophysics Data System (ADS)

Longhurst, Alan

2001-11-01

A hitherto-unnoticed phytoplankton bloom, of dimension 3000×1500 km, occupies the Madagascar Basin in late austral summer, being a prominent feature in SeaWiFS images. A first-order interpretation of the bloom mechanism invokes the seasonal deepening of the mixed layer within a strong mesoscale eddy-field and the consequent entrainment of nutrients into the photic zone. Features of the bloom correspond closely and appropriately with features of the eddy-field as observed by TOPEX-POSEIDON sea level anomalies. The bloom failed to develop in 1998, the second year of a two-year ENSO episode, when anomalously weak Southeast Trades will have failed to deepen the mixed layer as in other years.

The Role of Phytoplankton Dynamics in the Seasonal and Interannual Variability of Carbon in the Subpolar North Atlantic - a Modeling Study

NASA Technical Reports Server (NTRS)

Signorini, Sergio; Hakkinen, Sirpa; Gudmundsson, K.; Olsen, A.; Omar, A. M.; Olafsson, J.; Reverdin, G.; Henson, S. A.; McClain, C. R.; Worthen, D. L.

2014-01-01

We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients) are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 µmol kg(sup -1) with a corresponding increase in DIC of up to 16 µmol kg(sup -1). During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 µatm and a reduction of atmospheric CO2 uptake of more than 6 mmolm(sup -2) d(sup -1). On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27 %. Considering the areal extent of the bloom from satellite images within the Irminger and Icelandic Basins, this reduction translates into an annual mean of nearly 1500 tonnes C yr(sup -1).

Controls of primary production in two phytoplankton blooms in the Antarctic Circumpolar Current

NASA Astrophysics Data System (ADS)

Hoppe, C. J. M.; Klaas, C.; Ossebaar, S.; Soppa, M. A.; Cheah, W.; Laglera, L. M.; Santos-Echeandia, J.; Rost, B.; Wolf-Gladrow, D. A.; Bracher, A.; Hoppema, M.; Strass, V.; Trimborn, S.

2017-04-01

The Antarctic Circumpolar Current has a high potential for primary production and carbon sequestration through the biological pump. In the current study, two large-scale blooms observed in 2012 during a cruise with R.V. Polarstern were investigated with respect to phytoplankton standing stocks, primary productivity and nutrient budgets. While net primary productivity was similar in both blooms, chlorophyll a -specific photosynthesis was more efficient in the bloom closer to the island of South Georgia (39 °W, 50 °S) compared to the open ocean bloom further east (12 °W, 51 °S). We did not find evidence for light being the driver of bloom dynamics as chlorophyll standing stocks up to 165 mg m-2 developed despite mixed layers as deep as 90 m. Since the two bloom regions differ in their distance to shelf areas, potential sources of iron vary. Nutrient (nitrate, phosphate, silicate) deficits were similar in both areas despite different bloom ages, but their ratios indicated more pronounced iron limitation at 12 °W compared to 39 °W. While primarily the supply of iron and not the availability of light seemed to control onset and duration of the blooms, higher grazing pressure could have exerted a stronger control toward the declining phase of the blooms.

Spatial and temporal patterns in the seasonal distribution of toxic cyanobacteria in Western Lake Erie from 2002-2014.

PubMed

Wynne, Timothy T; Stumpf, Richard P

2015-05-12

Lake Erie, the world's tenth largest freshwater lake by area, has had recurring blooms of toxic cyanobacteria for the past two decades. These blooms pose potential health risks for recreation, and impact the treatment of drinking water. Understanding the timing and distribution of the blooms may aid in planning by local communities and resources managers. Satellite data provides a means of examining spatial patterns of the blooms. Data sets from MERIS (2002-2012) and MODIS (2012-2014) were analyzed to evaluate bloom patterns and frequencies. The blooms were identified using previously published algorithms to detect cyanobacteria (~25,000 cells mL-1), as well as a variation of these algorithms to account for the saturation of the MODIS ocean color bands. Images were binned into 10-day composites to reduce cloud and mixing artifacts. The 13 years of composites were used to determine frequency of presence of both detectable cyanobacteria and high risk (>100,000 cells mL-1) blooms. The bloom season according to the satellite observations falls within June 1 and October 31. Maps show the pattern of development and areas most commonly impacted during all years (with minor and severe blooms). Frequencies during years with just severe blooms (minor bloom years were not included in the analysis) were examined in the same fashion. With the annual forecasts of bloom severity, these frequency maps can provide public water suppliers and health departments with guidance on the timing of potential risk.

Propagation of high-energy laser beams through the earth's atmosphere II; Proceedings of the Meeting, Los Angeles, CA, Jan. 21-23, 1991

NASA Technical Reports Server (NTRS)

Ulrich, Peter B. (Editor); Wilson, Leroy E. (Editor)

1991-01-01

Consideration is given to turbulence at the inner scale, modeling turbulent transport in laser beam propagation, variable wind direction effects on thermal blooming correction, realistic wind effects on turbulence and thermal blooming compensation, wide bandwidth spectral measurements of atmospheric tilt turbulence, remote alignment of adaptive optical systems with far-field optimization, focusing infrared laser beams on targets in space without using adaptive optics, and a simplex optimization method for adaptive optics system alignment. Consideration is also given to ground-to-space multiline propagation at 1.3 micron, a path integral approach to thermal blooming, functional reconstruction predictions of uplink whole beam Strehl ratios in the presence of thermal blooming, and stability analysis of semidiscrete schemes for thermal blooming computation.

Intraspecific bloom succession in the harmful dinoflagellate Cochlodinium polykrikoides (Dinophyceae) extended the blooming period in Korean coastal waters in 2009.

PubMed

Park, Bum Soo; Kim, Jin Ho; Kim, Joo-Hwan; Baek, Seung Ho; Han, Myung-Soo

2018-01-01

Although there have been extensive studies on dinoflagellate blooms in recent decades, the mechanism that allows the maintenance of blooms over long periods remains uncertain, and studies on genetically differentiated subpopulations may provide insights into this mechanism. In this study, the influence of two genetically distinct subpopulations of the dinoflagellate Cochlodinium polykrikoides, referred to as Group I and IV, on bloom duration in Korean coastal waters (KCW) was examined using a quantitative PCR (qPCR) assay. In this study, a C. polykrikoides bloom occurred over a longer period in 2009 (49 days), whereas the bloom period was shorter in 2010 (35 days). The qPCR results indicate that intraspecific bloom succession between Groups I and IV occurred in 2009, whereas only a single subpopulation (Group I) was responsible for the bloom in 2010. Based on the statistical analysis, the Group I and Group IV blooms occurred under significantly different environmental conditions (p ≤ 0.05) in terms of water temperature, pH, and phosphate concentration, and these subpopulations exhibited significantly different relationships with environmental factors, particularly water temperature (p < 0.01). This variability may allow blooms to continue through intraspecific bloom succession even after environmental conditions change. Southern KCW are affected by outer regions via the Tsushima Warm Current (TWC) every summer. Group IV (≤1108 ± 69 cells L -1 ) was primarily observed along the route of the TWC in summer 2009, when the bloom of this subpopulation occurred in southern KCW. These results suggest that Group IV transported via the TWC may have influenced the bloom dynamics of this subpopulation in summer 2009. Copyright © 2017 Elsevier B.V. All rights reserved.

A Numerical Modeling Study of Mesodinium Bloom Formation and Retention in a River-Dominated Mesotidal Estuary

NASA Astrophysics Data System (ADS)

Spitz, Y. H.; Cervantes, B.

2016-02-01

The Columbia River estuary experiences extensive seasonal red-colored blooms caused by a mixotrophic ciliate of the genus Mesodinium. Although the blooms are non-toxic, they have a significant influence on the levels of nutrients, light and oxygen in the estuary. Mesodinium spp. displays very particular physiology that makes it one of few planktonic species able to thrive in a highly flushed system: a high growth rate due to its ability to photosynthesize using the photosynthetic organelles of its preys, and complex vertical migration patterns. Knowledge of the migration pattern is based on limited observations of Mesodinium behavior in culture and recent in-situ measurements collected in the Columbia River estuary. A more comprehensive understanding is needed of the mechanisms allowing Mesodinium spp. to be retained and experience rapid growth. To this end, we extended the finite element circulation model SELFE to include a 5-component behavioral model that simulates the relationships between nutrients, detritus, Mesodinium spp. and its cryptophyte prey. We then used the model to investigate various migration patterns and growth scenarios to determine their role in the formation and retention of the Mesodinium spp. bloom in the brackish water of the estuary.

Effects of Microcystis on development of early life stage Japanese medaka (Oryzias latipes): Comparative toxicity of natural blooms, cultured Microcystis and microcystin-LR.

PubMed

Saraf, Spencer R; Frenkel, Amy; Harke, Matthew J; Jankowiak, Jennifer G; Gobler, Christopher J; McElroy, Anne E

2018-01-01

Freshwater cyanobacterial harmful algal blooms (CyanoHABs) caused by algae in the genus Microcystis have been increasing in frequency and severity in recent decades. Microcystis blooms threaten aquatic organisms through effects associated with the rapid increase of biomass and the production of the hepatotoxin microcystin (MC) by toxic strains. Among fish, effects of blooms are likely to be more severe for early life stages, and physiological impacts on this life stage could significantly impact recruitment and fish populations. This study explores the effects of Microcystis blooms on the development of fish using the model organism, the Japanese medaka (Oryzias latipes), under realistic exposure conditions. Medaka embryos were exposed to natural blooms collected from New York City (USA) lakes, lab cultures of Microcystis, and MC-LR solutions. Field collected samples were more toxic than lab cultures (even when compared at the same algal density or MC concentration), causing decreased survival, premature time to hatch, reduced body length, yolk sac edema, and decreased heart rate, while lab culture exposures only resulted in bradycardia. Heart rate was the most sensitive endpoint measured, being depressed in embryos exposed to both lab cultures and field collected blooms. Generalized linear model analysis indicated bradycardia was statistically associated with both cell densities of blooms and MC concentrations, while single factor analysis indicated that MC concentrations had a stronger correlation compared to cell densities. However, MC exposure could not fully explain the effects observed, as exposures to MC-LR solutions alone were not able to reduce heart rate as severely as algal exposures. Collectively, these experiments indicate that factors beyond exposure to MC or even isolated Microcystis strains influence heart rate of fish exposed to Microcystis blooms. Enhanced mortality, depressed heart rate, and abnormal development observed in response to environmentally realistic exposures of Microcystis blooms could affect success of fish at both individual or population levels. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of temperature and salinity on the growth of Alexandrium (Dinophyceae) isolates from the Salish Sea

PubMed Central

Bill, Brian D.; Moore, Stephanie K.; Hay, Levi R.; Anderson, Donald M.; Trainer, Vera L.

2016-01-01

Toxin-producing blooms of dinoflagellates in the genus Alexandrium have plagued the inhabitants of the Salish Sea for centuries. Yet the environmental conditions that promote accelerated growth of this organism, a producer of paralytic shellfish toxins, is lacking. This study quantitatively determined the growth response of two Alexandrium isolates to a range of temperatures and salinities, factors that will strongly respond to future climate change scenarios. An empirical equation, derived from observed growth rates describing the temperature and salinity dependence of growth, was used to hindcast bloom risk. Hindcasting was achieved by comparing predicted growth rates, calculated from in situ temperature and salinity data from Quartermaster Harbor, with corresponding Alexandrium cell counts and shellfish toxin data. The greatest bloom risk, defined at μ>0.25 d−1, generally occurred from April through November annually; however, growth rates rarely fell below 0.10 d−1. Except for a few occasions, Alexandrium cells were only observed during the periods of highest bloom risk and paralytic shellfish toxins above the regulatory limit always fell within the periods of predicted bloom occurrence. While acknowledging that Alexandrium growth rates are affected by other abiotic and biotic factors, such as grazing pressure and nutrient availability, the use of this empirical growth function to predict higher risk time frames for blooms and toxic shellfish within the Salish Sea provides the groundwork for a more comprehensive biological model of Alexandrium bloom dynamics in the region and will enhance our ability to forecast blooms in the Salish Sea under future climate change scenarios. PMID:27037588

Selective control of toxic Microcystis water blooms using lysine and malonic acid: an enclosure experiment.

PubMed

Kaya, Kunimitsu; Liu, Yong-Ding; Shen, Yin-Wu; Xiao, Bang-Ding; Sano, Tomoharu

2005-04-01

Three enclosures (10 x 10 x 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially, 10 g/m(2) of lysine was sprayed in Enclosure B, and 10 g/m(2) each of lysine and malonic acid were sprayed together in Enclosure C. Enclosure A remained untreated and was used as a control. The concentrations of lysine, malonic acid, chlorophyll a, and microcystin as well as the cell numbers of phytoplankton such as cyanobacteria, diatom, and euglena were monitored. On day 1 of the treatment, formation of cyanobacterial blooms almost ceased in Enclosures B and C, although Microcystis cells in the control still formed blooms. On day 7 Microcystis cells in Enclosure B that had been treated with lysine started growing again, whereas growth was not observed in Microcystis cells in Enclosure C, which had been treated with lysine and malonic acid. On day 28 the surface of Enclosure B was covered with water chestnut (Trapa spp.) and the Microcystis blooms again increased. In contrast, growth of macrophytes (Myriophllum spicatum and Potamogeton crispus) was observed in Enclosure C; however, no cyanobacterial blooms were observed. Lysine and malonic acid had completely decomposed. The microcystin concentration on day 28 decreased to 25% of the initial value, and the pH shifted from the initial value of 9.2 to 7.8. We concluded that combined treatment with lysine and malonic acid selectively controlled toxic Microcystis water blooms and induced the growth of macrophytes.

Observations of phytoplankton spring bloom onset triggered by a density front in NW Mediterranean

NASA Astrophysics Data System (ADS)

Olita, A.; Sparnocchia, S.; Cusí, S.; Fazioli, L.; Sorgente, R.; Tintoré, J.; Ribotti, A.

2013-09-01

Phytoplankton bloom in NW Mediterranan sea is a seasonal event that mainly occurrs in a limited area (Gulf of Lyon and Provençal basin) where this phenomenon is promoted by a cyclonic circulation, strong wind-driven mixing and subsequent spring restratification. At the southern boundary of this area a density front (North Balearic Front) separating denser waters from the lighter Modified Atlantic Waters reservoir at south is suspected to trigger weaker and earlier (late winter) blooms by (a) enhanced pumping of nutrients into the euphotic layer and (b) promoting an early restratification of the water column (by frontal instabilities). A multisensor glider round trip, equipped with CTD and fluorimeter, crossing the frontal area in February-March 2013, allowed to observe the bloom triggering after the decrease of intense wind-driven turbulent convection and mixing. Satellite imagery supports and confirms in-situ observations. It was shown that frontal activity has a relevant role in the promotion and acceleration of the dynamical restratification, with a consequent biological response in terms of primary production. Restratification is necessary preconditioning factor for bloom triggering in frontal area, net of other involved mechanism promoting the bloom as the enhanced biological pump. So, like for high-latitude fronts (Taylor and Ferrari, 2011a), also for this mid-latitude oligotrophic region front seems to promote new production by dynamically enahnced restratification inhibiting mixing. Finally, we argued that Sverdrup's Critical Depth criterion seems to apply in the northern well-mixed area, where the zeroing of heat fluxes (and related turbulent convection) does not correspond to a prompt onset of the bloom (which appeared 1 month later).

Human health effects associated with exposure to toxic Cyanobacteria – what is the evidence?

EPA Science Inventory

Reports of toxic cyanobacteria blooms are increasing worldwide, as warming water and eutrophic surface water systems support the development of blooms. As awareness of toxic cyanobacteria blooms increases, reports of associated human and animal illnesses have also increased, but ...

Monitoring red tide with satellite imagery and numerical models: a case study in the Arabian Gulf.

PubMed

Zhao, Jun; Ghedira, Hosni

2014-02-15

A red tide event that occurred in August 2008 in the Arabian Gulf was monitored and assessed using satellite observations and numerical models. Satellite observations revealed the bloom extent and evolution from August 2008 to August 2009. Flow patterns of the bloom patch were confirmed by results from a HYCOM model. HYCOM data and satellite-derived sea surface temperature data further suggested that the bloom could have been initiated offshore and advected onshore by bottom Ekman layer. Analysis indicated that nutrient sources supporting the bloom included upwelling, Trichodesmium, and dust deposition while other potential sources of nutrient supply should also be considered. In order to monitor and detect red tide effectively and provide insights into its initiation and maintenance mechanisms, the integration of multiple platforms is required. The case study presented here demonstrated the benefit of combing satellite observations and numerical models for studying red tide outbreaks and dynamics. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Quantification of phytoplankton bloom dynamics by citizen scientists in urban and peri-urban environments.

PubMed

Castilla, Eva Pintado; Cunha, Davi Gasparini Fernandes; Lee, Fred Wang Fat; Loiselle, Steven; Ho, Kin Chung; Hall, Charlotte

2015-11-01

Freshwater ecosystems are severely threatened by urban development and agricultural intensification. Increased occurrence of algal blooms is a main issue, and the identification of local dynamics and drivers is hampered by a lack of field data. In this study, data from 13 cities (250 water bodies) were used to examine the capacity of trained community members to assess elevated phytoplankton densities in urban and peri-urban freshwater ecosystems. Coincident nutrient concentrations and land use observations were used to examine possible drivers of algal blooms. Measurements made by participants showed a good relationship to standard laboratory measurements of phytoplankton density, in particular in pond and lake ecosystems. Links between high phytoplankton density and nutrients (mainly phosphate) were observed. Microscale observations of pollution sources and catchment scale estimates of land cover both influenced the occurrence of algal blooms. The acquisition of environmental data by committed and trained community members represents a major opportunity to support agency monitoring programmes and to complement field campaigns in the study of catchment dynamics.

The Subpolar North Atlantic Spring Bloom - What Did We Learn from the NAB 2008 Autonomous Experiment?

NASA Astrophysics Data System (ADS)

Perry, M. J.

2015-12-01

The subpolar North Atlantic bloom is one of the most remarkable features on the planet, with almost explosive 'greening' of the oceans. Over decades, investigators from countries bordering the North Atlantic have caught snippets of the bloom from research vessels or merchant ships transiting between continents. On 4 April 2008, Eric D'Asaro, Craig Lee, and I began a comprehensive study of the initiation and demise of the spring bloom using 2 types of autonomous platforms - a patch-following Lagrangian mixed-layer float and 4 float-following gliders. The 3 mo autonomous experiment integrated measurements from the float, gliders and ships, observations from satellites, and analyses from models. The diatom-dominated bloom began in mid April when the water column stabilized, not by solar warming, but rather by eddy-driven slumping of horizontal density gradients. The resulting bloom was patchy in both biomass and phytoplankton diversity, despite high, non-limiting concentrations of macronutrients. Magnitudes and relative proportions of net community productivity (NCP; determined from autonomous budgets of O2 and NO3) and net phytoplankton productivity (NPP; computed from ship-based photosynthetic parameters and float-based biomass and light) diverged as the bloom evolved, with higher fractions of particulate organic carbon (POC) consumed within the mixed layer as the bloom aged. Export productivity (EP; derived as the difference between NCP and accumulation rate of POC) was of similar magnitude during the May diatom bloom and the June picophytoplankton bloom. When silicic acid dropped to 1 μM, diatoms aggregated and sank; the deep flux event was dominated by resting spores of Chaetoceros. Although a short-lived event, it was ubiquitously observed by the 4 gliders and ship. An eddy-driven subduction event was likewise observed, indicating transport of otherwise non-sinking POC along isopycnals to depths of > 200 m. These striking export events reinforce the value of a persistent, distributed presence afforded by a network of autonomous platforms to catch and follow key, transient events. NAB 2008 demonstrated the power of autonomous platforms to decipher productivities and carbon fluxes at the patch scale, but left the enticing challenge of how to scale from the patch to the basin for another time.

The Importance of Submesoscale Versus Basin-scale Processes in Driving the Subpolar Spring Phytoplankton Bloom.

NASA Astrophysics Data System (ADS)

Brody, S.; Mahadevan, A.; Lozier, M. S.

2014-12-01

The subpolar spring phytoplankton bloom has important consequences for marine ecosystems and the carbon cycle. The timing of the bloom has been conceived of as a basin-scale event: as the ocean warms, the seasonal mixed layer shoals, restricting phytoplankton to shallower depths and increasing available light to a level at which the bloom can begin. Recent studies have highlighted the importance of localized phenomena in driving the bloom initiation. Specifically, the role of lateral density gradients in generating <10km instabilities in the upper ocean, which then stratify the mixed layer before surface heating begins, has been explored with a process study model and fine-scale observations from a field program to study the North Atlantic spring bloom [1]. However, an alternative hypothesis has recently been validated at both the small scale, using the same observational data [2], and at the basin scale, using remote sensing data [3]. According to this hypothesis, blooms begin when surface heat fluxes weaken, mixing shifts from primarily convectively-driven to primarily wind-driven, and the depth of active mixing in the upper ocean consequently decreases. Here, we compare the importance of the barriers to mixing presented by submesoscale instabilities with the decreases in mixing depth caused by changes in surface forcing in driving the initiation of the spring bloom prior to the onset of surface heating. To make this comparison, we use a Lagrangian framework to track the light history of particles seeded in a high-resolution numerical model that we initialize with various surface forcing scenarios, and with and without lateral density gradients. Because the model parameterizes convection with convective adjustment, we present two methodologies to account for turbulent mixing processes that utilize observations of turbulent vertical mixing from a Lagrangian float. We present conclusions on whether and how submesoscale processes affect bloom initiation under varied surface forcing conditions in the context of whether the timing of the subpolar phytoplankton bloom can be thought of as a basin-scale or submesoscale phenomenon. [1] A. Mahadevan et al.. Science 337, 6090 (2012). [2] Brody, S.R. and Lozier, M.S. (under review, ICES J. Mar. Sci) [3] Brody, S.R. and Lozier, M.S. Geophys. Res. Lett. 41, (2014).

Development and Application of a Low-Volume Flow System for Solution-State in Vivo NMR.

PubMed

Tabatabaei Anaraki, Maryam; Dutta Majumdar, Rudraksha; Wagner, Nicole; Soong, Ronald; Kovacevic, Vera; Reiner, Eric J; Bhavsar, Satyendra P; Ortiz Almirall, Xavier; Lane, Daniel; Simpson, Myrna J; Heumann, Hermann; Schmidt, Sebastian; Simpson, André J

2018-06-18

In vivo nuclear magnetic resonance (NMR) spectroscopy is a particularly powerful technique, since it allows samples to be analyzed in their natural, unaltered state, criteria paramount for living organisms. In this study, a novel continuous low-volume flow system, suitable for in vivo NMR metabolomics studies, is demonstrated. The system allows improved locking, shimming, and water suppression, as well as allowing the use of trace amounts of expensive toxic contaminants or low volumes of precious natural environmental samples as stressors. The use of a double pump design with a sump slurry pump return allows algal food suspensions to be continually supplied without the need for filters, eliminating the possibility of clogging and leaks. Using the flow system, the living organism can be kept alive without stress indefinitely. To evaluate the feasibility and applicability of the flow system, changes in the metabolite profile of 13 C enriched Daphnia magna over a 24-h period are compared when feeding laboratory food vs exposing them to a natural algal bloom sample. Clear metabolic changes are observed over a range of metabolites including carbohydrates, lipids, amino acids, and a nucleotide demonstrating in vivo NMR as a powerful tool to monitor environmental stress. The particular bloom used here was low in microcystins, and the metabolic stress impacts are consistent with the bloom being a poor food source forcing the Daphnia to utilize their own energy reserves.

Locating Noctiluca Miliaris in the Arabian Sea: An Optical Proxy Approach

NASA Technical Reports Server (NTRS)

Thibodeau, Patricia S.; Roesler, Collin S.; Drapeau, Susan L.; Matondkar, S. G. Prabhu; Goes, Joaquim I.; Werdell, P. Jeremy

2014-01-01

Coincident with shifting monsoon weather patterns over India, the phytoplankter Noctiluca miliaris has recently been observed to be dominating phytoplankton blooms in the northeastern Arabian Sea during the winter monsoons. Identifying the exact environmental and/or ecological conditions that favor this species has been hampered by the lack of concurrent environmental and biological observations on time and space scales relevant to ecologic and physiologic processes. We present a bio-optical proxy for N. miliaris measured on highly resolved depth scales coincident with hydrographic observations with the goal to identify conducive hydrographic conditions for the bloom. The proxy is derived from multichannel excitation chlorophyll a fluorescence and is validated with microscopy, pigment composition, and spectral absorption. Phytoplankton populations dominated by either diatoms or other dinoflagellates were additionally discerned. N. miliaris populations in full bloom were identified offshore in low-nutrient and low-N : P ratio surface waters within a narrow temperature and salinity range. These populations transitioned to high-biomass diatom-dominated coastal upwelling populations. A week later, the N. miliaris blooms were observed in declining phase, transitioning to very-low-biomass populations of non-N. miliaris dinoflagellates. There were no clear hydrographic conditions uniquely associated with the N. miliaris populations, although N. miliaris was not found in the upwelling or extremely oligotrophic waters. Taxonomic transitions were not discernible in the spatial structure of the bloom as identified by the ocean color Chl imagery, indicating that in situ observations may be necessary to resolve community structure, particularly for populations below the surface.

Spatial and temporal variability in the nitrogen cyclers of hypereutrophic Lake Taihu.

PubMed

Krausfeldt, Lauren E; Tang, Xiangming; van de Kamp, Jodie; Gao, Guang; Bodrossy, Levente; Boyer, Gregory L; Wilhelm, Steven W

2017-04-01

Harmful cyanobacterial blooms (cyanoHABs) are a major threat to freshwater ecosystems worldwide. Evidence suggests that both nitrogen and phosphorus are important nutrients in the development and proliferation of blooms, yet much less is known about nitrogen cycling dynamics in these systems. To assess the potential nitrogen cycling function of the cyanoHAB community, surface water samples were collected in Lake Tai (Taihu), China over a 5-month bloom event in 2014. The expression of six nitrogen cycling genes (nifH, hzsA, nxrB, nrfA, amoA, nosZ) was surveyed using a targeted microarray with probes designed to provide phylogenetic information. N-Cycling gene expression varied spatially across Taihu, most notably near the mouth of the Dapu River. Expression of nifH was observed across the lake and attributable to both Proteobacteria and Cyanobacteria: Proteobacteria were major contributors to nifH signal near shore. Other N transformations such as anaerobic ammonia oxidation and denitrification were evident in the surface waters as well. Observations in this study highlight the potential importance of heterotrophic bacteria in N-cycling associated with cyanoHABs. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Theoretical analysis for scaling law of thermal blooming based on optical phase deference

NASA Astrophysics Data System (ADS)

Sun, Yunqiang; Huang, Zhilong; Ren, Zebin; Chen, Zhiqiang; Guo, Longde; Xi, Fengjie

2016-10-01

In order to explore the laser propagation influence of thermal blooming effect of pipe flow and to analysis the influencing factors, scaling law theoretical analysis of the thermal blooming effects in pipe flow are carry out in detail based on the optical path difference caused by thermal blooming effects in pipe flow. Firstly, by solving the energy coupling equation of laser beam propagation, the temperature of the flow is obtained, and then the optical path difference caused by the thermal blooming is deduced. Through the analysis of the influence of pipe size, flow field and laser parameters on the optical path difference, energy scaling parameters Ne=nTαLPR2/(ρɛCpπR02) and geometric scaling parameters Nc=νR2/(ɛL) of thermal blooming for the pipe flow are derived. Secondly, for the direct solution method, the energy coupled equations have analytic solutions only for the straight tube with Gauss beam. Considering the limitation of directly solving the coupled equations, the dimensionless analysis method is adopted, the analysis is also based on the change of optical path difference, same scaling parameters for the pipe flow thermal blooming are derived, which makes energy scaling parameters Ne and geometric scaling parameters Nc have good universality. The research results indicate that when the laser power and the laser beam diameter are changed, thermal blooming effects of the pipeline axial flow caused by optical path difference will not change, as long as you keep energy scaling parameters constant. When diameter or length of the pipe changes, just keep the geometric scaling parameters constant, the pipeline axial flow gas thermal blooming effects caused by optical path difference distribution will not change. That is to say, when the pipe size and laser parameters change, if keeping two scaling parameters with constant, the pipeline axial flow thermal blooming effects caused by the optical path difference will not change. Therefore, the energy scaling parameters and the geometric scaling parameters can really describe the gas thermal blooming effect in the axial pipe flow. These conclusions can give a good reference for the construction of the thermal blooming test system of laser system. Contrasted with the thermal blooming scaling parameters of the Bradley-Hermann distortion number ND and Fresnel number NF, which were derived based on the change of far field beam intensity distortion, the scaling parameters of pipe flow thermal blooming deduced from the optical path deference variation are very suitable for the optical system with short laser propagation distance, large Fresnel number and obviously changed optical path deference.

Eddy-driven stratification initiates North Atlantic spring phytoplankton blooms.

PubMed

Mahadevan, Amala; D'Asaro, Eric; Lee, Craig; Perry, Mary Jane

2012-07-06

Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.

Applications of MODIS Fluorescent Line Height Measurements to Monitor Water Quality Trends and Algal Bloom Activity

NASA Technical Reports Server (NTRS)

Fischer, Andrew; Moreno-Mardinan, Max; Ryan, John P.

2012-01-01

Recent advances in satellite and airborne remote sensing, such as improvements in sensor and algorithm calibrations, processing techniques and atmospheric correction procedures have provided for increased coverage of remote-sensing, ocean-color products for coastal regions. In particular, for the Moderate Resolution Imaging Spectrometer (MODIS) sensor calibration updates, improved aerosol retrievals and new aerosol models has led to improved atmospheric correction algorithms for turbid waters and have improved the retrieval of ocean color in coastal waters. This has opened the way for studying ocean phenomena and processes at finer spatial scales, such as the interactions at the land-sea interface, trends in coastal water quality and algal blooms. Human population growth and changes in coastal management practices have brought about significant changes in the concentrations of organic and inorganic, particulate and dissolved substances entering the coastal ocean. There is increasing concern that these inputs have led to declines in water quality and have increase local concentrations of phytoplankton, which cause harmful algal blooms. In two case studies we present MODIS observations of fluorescence line height (FLH) to 1) assess trends in water quality for Tampa Bay, Florida and 2) illustrate seasonal and annual variability of algal bloom activity in Monterey Bay, California as well as document estuarine/riverine plume induced red tide events. In a comprehensive analysis of long term (2003-2011) in situ monitoring data and satellite imagery from Tampa Bay we assess the validity of the MODIS FLH product against chlorophyll-a and a suite of water quality parameters taken in a variety of conditions throughout a large optically complex estuarine system. A systematic analysis of sampling sites throughout the bay is undertaken to understand how the relationship between FLH and in situ chlorophyll-a responds to varying conditions and to develop a near decadal trend in water quality changes. In situ monitoring locations that correlated well with satellite imagery were in depths greater than seven meters and were located over five kilometers from shore. Water quality parameter of total nitrogen, phosphorous, turbidity and biological oxygen demand had high correlations with these sites, as well. Satellite FLH estimates show improving water quality from 2003-2007 with a slight decline up through 2011. Dinoflagellate blooms in Monterey Bay, California (USA) have recently increased in frequency and intensity. Nine years of MODIS FLH observations are used to describe the annual and seasonal variability of bloom activity within the Bay. Three classes of MODIS algorithms were correlated against in situ chlorophyll measurements. The FLH algorithm provided the most robust estimate of bloom activity. Elevated concentrations of phytoplankton were evident during the months of August-November, a period during which increased occurrences of dinoflagellate blooms have been observed in situ. Seasonal patterns of FLH show the on- and offshore movement of areas of high phytoplankton biomass between oceanographic seasons. Higher concentrations of phytoplankton are also evident in the vicinity of the land-based nutrient sources and outflows, and the cyclonic bay-wide circulation can transport these nutrients to the northern Bay bloom incubation region. Both of these case studies illustrate the utility MODIS FLH observations in supporting management decisions in coastal and estuarine waters.

The Blooming Anatomy Tool (BAT): A discipline-specific rubric for utilizing Bloom's taxonomy in the design and evaluation of assessments in the anatomical sciences.

PubMed

Thompson, Andrew R; O'Loughlin, Valerie D

2015-01-01

Bloom's taxonomy is a resource commonly used to assess the cognitive level associated with course assignments and examination questions. Although widely utilized in educational research, Bloom's taxonomy has received limited attention as an analytical tool in the anatomical sciences. Building on previous research, the Blooming Anatomy Tool (BAT) was developed. This rubric provides discipline-specific guidelines to Blooming anatomy multiple-choice questions (MCQs). To test the efficacy of the BAT, a group of volunteers were randomly split up and asked to Bloom a series of anatomy MCQs using either the BAT or a traditional Bloom's reference called Bloom's Learning Objectives (BLO). Both groups utilized each rubric for a different series of MCQs. Examination question categorizations made using each rubric were tested for accuracy and interrater reliability. In addition, previous experience in anatomy and Bloom's taxonomy were considered. Results demonstrated that volunteers using the BAT had consistently higher levels of interrater reliability, but accuracy varied and was similar between rubrics. Neither measure was substantially impacted by experience in Bloom's taxonomy or anatomy. A poststudy survey indicated that volunteers strongly preferred the BAT and felt it was more helpful in categorizing anatomy MCQs than the BLO. These results suggest that the BAT can be useful in educational research in the anatomical sciences to aid in aligning observer judgment on Bloom taxonomic levels and improve consistency, especially when used in conjunction with a norming session prior to data collection. © 2014 American Association of Anatomists.

Phytoplankton bloom dynamics in temperate, turbid, stressed estuaries: a model study

NASA Astrophysics Data System (ADS)

de Swart, Huib E.; Liu, Bo; de Jonge, Victor

2017-04-01

To gain insight into mechanisms underlying phytoplankton bloom dynamics in temperature, turbid estuaries, experiments were conducted with an idealised model that couples physical and biological processes. Results show that the model is capable of producing the main features of the observed blooms in the Ems estuary (Northwest Germany), viz. in the lower reach a spring bloom occur, which is followed by a secondary bloom in autumn. The along-estuary distribution of suspended sediment concentration (SSC) and the along-estuary distance between the nutrient source and the seaward bound of the turbidity zone control both the along-estuary locations and intensities of the blooms. Results of further sensitivity studies reveal that in a shallow, well-mixed estuary, under temporally-constant suspended sediment conditions, the seasonally-varying water temperature has larger impact on the timing of spring blooms than the seasonally-varying incident light intensity. The occurrence of the secondary bloom is caused by the fact that the growth rate of phytoplankton attains a maximum at an optimum water temperature. Bloom intensities are also modulated by the advective processes related to subtidal current because the latter regulates the seaward transport of nutrient from riverine source. Large-scale deepening of navigation channels leads to later spring blooms due to increased mixing depth. Finally, phytoplankton blooms are unlikely to occur in the upper reach due to the elevated SSC and the landward expansion of turbidity zone related to large-scale deepening.

A comprehensive insight into functional profiles of free-living microbial community responses to a toxic Akashiwo sanguinea bloom

NASA Astrophysics Data System (ADS)

Yang, Caiyun; Li, Yi; Zhou, Yanyan; Lei, Xueqian; Zheng, Wei; Tian, Yun; van Nostrand, Joy D.; He, Zhili; Wu, Liyou; Zhou, Jizhong; Zheng, Tianling

2016-10-01

Phytoplankton blooms are a worldwide problem and can greatly affect ecological processes in aquatic systems, but its impacts on the functional potential of microbial communities are limited. In this study, a high-throughput microarray-based technology (GeoChip) was used to profile the functional potential of free-living microbes from the Xiamen Sea Area in response to a 2011 Akashiwo sanguinea bloom. The bloom altered the overall community functional structure. Genes that were significantly (p < 0.05) increased during the bloom included carbon degradation genes and genes involved in nitrogen (N) and/or phosphorus (P) limitation stress. Such significantly changed genes were well explained by chosen environmental factors (COD, nitrite-N, nitrate-N, dissolved inorganic phosphorus, chlorophyll-a and algal density). Overall results suggested that this bloom might enhance the microbial converting of nitrate to N2 and ammonia nitrogen, decrease P removal from seawater, activate the glyoxylate cycle, and reduce infection activity of bacteriophage. This study presents new information on the relationship of algae to other microbes in aquatic systems, and provides new insights into our understanding of ecological impacts of phytoplankton blooms.

Identifying ecological "sweet spots" underlying cyanobacteria functional group dynamics from long-term observations using a statistical machine learning approach

NASA Astrophysics Data System (ADS)

Nelson, N.; Munoz-Carpena, R.; Phlips, E. J.

2017-12-01

Diversity in the eco-physiological adaptations of cyanobacteria genera creates challenges for water managers who are tasked with developing appropriate actions for controlling not only the intensity and frequency of cyanobacteria blooms, but also reducing the potential for blooms of harmful taxa (e.g., toxin producers, N2 fixers). Compounding these challenges, the efficacy of nutrient management strategies (phosphorus-only versus nitrogen-and-phosphorus) for cyanobacteria bloom abatement is the subject of an ongoing debate, which increases uncertainty associated with bloom mitigation decision-making. In this work, we analyze a unique long-term (17-year) dataset composed of monthly observations of cyanobacteria genera abundances, zooplankton abundances, water quality, and flow from Lake George, a bloom-impacted flow-through lake of the St. Johns River (FL, USA). Using the Random Forests machine learning algorithm, an assumption-free ensemble modeling approach, the dataset was evaluated to quantify and characterize relationships between environmental conditions and seven cyanobacteria groupings: five genera (Anabaena, Cylindrospermopsis, Lyngbya, Microcystis, and Oscillatoria) and two functional groups (N2 fixers and non-fixers). Results highlight the selectivity of nitrogen in describing genera and functional group dynamics, and potential for physical effects to limit the efficacy of nutrient management as a mechanism for cyanobacteria bloom mitigation.

Harmful algal bloom smart device application: using image analysis and machine learning techniques for early classification of harmful algal blooms

EPA Science Inventory

The Ecological Stewardship Institute at Northern Kentucky University and the U.S. Environmental Protection Agency are collaborating to optimize a harmful algal bloom detection algorithm that estimates the presence and count of cyanobacteria in freshwater systems by image analysis...

HABSOS INTEGRATED CASE STUDY FOR THE GULF OF MEXICO

EPA Science Inventory

This project is part of a Harmful Algal Bloom Observing System Pilot Project for which the Gulf of Mexico Program is the coordinator. The Program office along with the EPA Gulf Breeze Laboratory will be working with the NOAA National Coastal Data Development Center, the National...

What causes the sporadic phytoplankton bloom southeast of Madagascar?

NASA Astrophysics Data System (ADS)

Uz, B. Mete

2007-09-01

A large, dendritic phytoplankton bloom develops in the austral summer of roughly every other year in the Indian Ocean southeast of Madagascar. It starts in February or March and dissipates by the end of April. It was observed in 1997, 1999, 2000, 2002, and 2004 and was absent in 1998, 2001, 2003, and 2005. A. Longhurst, who described it in 2001, suggested that the bloom is caused by the entrainment of nutrient-rich waters into a deepening mixed layer. At the time the bloom had been seen to fail only once, in 1998, and Longhurst attributed that to reduced entrainment due to low winds during the strong La Niña. Since reanalysis winds are not correlated with the occurrence/failure of the bloom, and since the bloom starts before sea surface temperature (SST) peaks and increased chlorophyll is found with high rather than low SST, entrainment is an unlikely cause. Argo float profiles from 2004 show the bloom within a shallow mixed layer over a very strong pycnocline. This indicates that the bloom is caused not by entrainment of nutrient-rich waters from below, but by another mechanism such as nitrogen fixation by diazotrophs that are retained within a shallow, well-lit layer, or nutrient fluxes due to vertically mobile plankton. This bloom is among the strongest features of interannual variability in the ocean color time series, second only to El Niño-Southern Oscillation (ENSO)-related variability in terms of both the area effected and magnitude of the anomaly. While the mechanisms with which biology responds to the physical changes associated with ENSO are well-known and rather obvious in the strong correlations with physical indicators such as sea surface height or temperature, the occurrence/failure of a strong Madagascar bloom does not have an obvious correlation with any physical parameter. Of the many variables tested, only the landfall of tropical cyclones on the island of Madagascar correlated with the occurrence of the bloom. A hypothesis is presented, without any proof other than that it explains the location, seasonal timing, interannual variability, and observations of temperature and mixed layer depth, on the basis of the premise that runoff from the island alleviates iron limitation of diazotrophs. Definitive determination of the nature of the bloom will probably require in situ sampling.

Real-time monitoring of nutrients in the Changjiang Estuary reveals short-term nutrient-algal bloom dynamics

NASA Astrophysics Data System (ADS)

Wang, Kui; Chen, Jianfang; Ni, Xiaobo; Zeng, Dingyong; Li, Dewang; Jin, Haiyan; Glibert, Patricia M.; Qiu, Wenxian; Huang, Daji

2017-07-01

The Changjiang Estuary is a large-river estuary ecosystem in the East China Sea, and its plume, the Changjiang Diluted Water (CDW), transports a large mass of nutrients (NO3- + NO2-, PO43-, SiO32-) to the shelf sea, leading to substantial eutrophication; the CDW also supports high primary production. However, relationships between nutrient delivery and phytoplankton responses have been difficult to establish, as many nutrient delivery events and algal blooms are episodic, and the CDW may expand or become detached with changing winds. To study the relationship between nutrient delivery events, algal blooms and estuarine metabolism dynamics, a buoy system was deployed in the CDW from 9 September to 10 October 2013, with measurements of chlorophyll a and dissolved nutrients. Day-to-day nutrient increases covaried with salinity decreases, regulated by both the spring-neap tidal cycle and wind events. Several specific nutrient injection periods were detected, each followed by nutrient drawdown and chlorophyll a accumulation (algal blooms). Each algal bloom had its own unique pattern of nutrient uptake based on change in nutrient ratios (ΔN:ΔP; ΔN:ΔSi) and appeared to be dominated by different algal groups. These events occurred under weak wind and stable hydrodynamic conditions. Ecosystem metabolism based on net community production (NCP) showed that the upper estuarine ecosystem was autotrophic when chlorophyll a accumulated, but heterotrophic when wind-induced mixing strengthened, and upwelling brought organic-rich water to the near surface. In spite of several short-lived algal blooms, the average NCPdaily was negative during the observation period, indicating a net source of CO2 to the atmosphere.

Processes governing phytoplankton blooms in estuaries. II: The role of horizontal transport

USGS Publications Warehouse

Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Cloern, J.E.; Thompson, J.K.

1999-01-01

The development and distribution of phytoplankton blooms in estuaries are functions of both local conditions (i.e. the production-loss balance for a water column at a particular spatial location) and large-scale horizontal transport. In this study, the second of a 2-paper series, we use a depth-averaged hydrodynamic-biological model to identify transport-related mechanisms impacting phytoplankton biomass accumulation and distribution on a system level. We chose South San Francisco Bay as a model domain, since its combination of a deep channel surrounded by broad shoals is typical of drowned-river estuaries. Five general mechanisms involving interaction of horizontal transport with variability in local conditions are discussed. Residual (on the order of days to weeks) transport mechanisms affecting bloom development and location include residence time/export, import, and the role of deep channel regions as conduits for mass transport. Interactions occurring on tidal time scales, i.e. on the order of hours) include the phasing of lateral oscillatory tidal flow relative to temporal changes in local net phytoplankton growth rates, as well as lateral sloshing of shoal-derived biomass into deep channel regions during ebb and back into shallow regions during flood tide. Based on these results, we conclude that: (1) while local conditions control whether a bloom is possible, the combination of transport and spatial-temporal variability in local conditions determines if and where a bloom will actually occur; (2) tidal-time-scale physical-biological interactions provide important mechanisms for bloom development and evolution. As a result of both subtidal and tidal-time-scale transport processes, peak biomass may not be observed where local conditions are most favorable to phytoplankton production, and inherently unproductive areas may be regions of high biomass accumulation.

MERIS observations of phytoplankton phenology in the Baltic Sea.

PubMed

Zhang, Daoxi; Lavender, Samantha; Muller, Jan-Peter; Walton, David; Zou, Xi; Shi, Fang

2018-06-13

The historical data from the MEdium Resolution Imaging Spectrometer (MERIS) is an invaluable archive for studying global waters from inland lakes to open oceans. Although the MERIS sensor ceased to operate in April 2012, the data capacities are now re-established through the recently launched Sentinel-3 Ocean and Land Colour Instrument (OLCI). The development of a consistent time series for investigating phytoplankton phenology features is crucial if the potential of MERIS and OLCI data is to be fully exploited for inland water monitoring. This study presents a time series of phytoplankton abundance and bloom spatial extent for the highly eutrophic inland water of the Baltic Sea using the 10-year MERIS archive (2002-2011) and a chlorophyll-a based Summed Positive Peaks (SPP) algorithm. A gradient approach in conjunction with the histogram analysis was used to determine a global threshold from the entire collection of SPP images for identifying phytoplankton blooms. This allows spatio-temporal dynamics of daily bloom coverage, timing, phytoplankton abundance and spatial extent to be investigated for each Baltic basin. Furthermore, a number of meteorological and hydrological variables, including spring excess phosphate, summer sea surface temperature and photosynthetically active radiation, were explored using boosted regression trees and generalised additive models to understand the ecological response of phytoplankton assemblages to environmental perturbations and potential predictor variables of summer blooms. The results indicate that the surface layer excess phosphate available in February and March had paramount importance over all other variables considered in governing summer bloom abundance in the major Baltic basins. This finding allows new insights into the development of early warning systems for summer phytoplankton blooms in the Baltic Sea and elsewhere. Copyright © 2018 Elsevier B.V. All rights reserved.

Abiotic control of phytoplankton blooms in temperate coastal marine ecosystems: A case study in the South Atlantic Ocean.

PubMed

Bermejo, Paula; Helbling, E Walter; Durán-Romero, Cristina; Cabrerizo, Marco J; Villafañe, Virginia E

2018-01-15

Coastal waters of the South Atlantic Ocean (SAO) sustain one of the highest levels of production of the World's ocean, maintained by dense phytoplankton winter blooms that are dominated by large diatoms. These blooms have been associated to calm weather conditions that allow the formation of a shallow and well illuminated upper mixed layer. In Bahía Engaño, a coastal site in Patagonia, Argentina (chosen as a model coastal ecosystem) winter blooms recurrently peaked on June and they were dominated almost entirely by the microplanktonic diatom Odontella aurita. However, during the year 2015, a new wind pattern was observed - with many days of northerly high-speed winds, deviating from the calm winter days observed during a reference period (2001-2014) used for comparison. We determined that this new wind pattern was the most important factor that affected the phytoplankton dynamics, precluding the initiation of a June bloom during 2015 that instead occurred during late winter (August). Furthermore, the 2015 bloom had a higher proportion of nanoplanktonic cells (as compared to the reference period) and it was co-dominated by O. aurita and Thalassiossira spp. Other variables such as nutrient supply and incident solar radiation did not have an important role in limiting and/or initiating the June 2015 bloom, but temperature might have benefited the growth of small cells during August 2015. If these changes in the timing and/or the taxonomic composition of the bloom persist, they may have important consequences for the secondary production and economic services of the coastal SAO. Copyright © 2017 Elsevier B.V. All rights reserved.

Patterns of Genetic Diversity and Co-Existence in Open Ocean Diatoms: the Effects of Water Mass Structure, Selection and Sex

NASA Astrophysics Data System (ADS)

Rynearson, T. A.; Chen, G.

2016-02-01

The open ocean North Atlantic spring bloom influences regional ecology and global biogeochemistry. Diatoms dominate the peak of the bloom and significantly impact productivity and export of organic carbon from the bloom. Despite their key role in a yearly event with global impacts, the genetic diversity and population structure of diatoms that comprise this open ocean bloom are unknown. Here we investigated the population genetics of the diatom Thalassiosira gravida sampled during the 2008 North Atlantic Bloom Experiment using newly-developed microsatellite markers. Here, we show that the genetic diversity of open ocean diatoms is high and that their population structure differs dramatically from coastal diatoms. High levels of genetic diversity were observed across all water samples and did not change during the bloom. Four genetically distinct populations were identified but were not associated with different water masses, depths or time points during the bloom. Instead, all four populations co-existed within samples, spanning different water masses, stages of the bloom and depths of over >300 m. The pattern of genetically distinct, co-existing populations in the open ocean contrasts dramatically with coastal habitats, where distinct populations have not been observed to co-exist at the same time and place. It is likely that populations originate via transport from disparate locations combined with overwintering capacity in the water column or sediments. The pattern of co-existence suggests that the open ocean may serve as a gene pool that harbors different populations that are then available for selection to act upon, which may contribute to the ecological and biogeochemical success of diatoms and influence their long-term evolutionary survival.

High Resolution Time Series of Plankton Communities: From Early Warning of Harmful Blooms to Sentinels of Climate Change

NASA Astrophysics Data System (ADS)

Sosik, H. M.; Campbell, L.; Olson, R. J.

2016-02-01

The combination of ocean observatory infrastructure and automated submersible flow cytometry provides an unprecedented capability for sustained high resolution time series of plankton, including taxa that are harmful or early indicators of ecosystem response to environmental change. On-going time series produced with the FlowCytobot series of instruments document important ways this challenge is already being met for phytoplankton and microzooplankton. FlowCytobot and Imaging FlowCytobot use a combination of laser-based scattering and fluorescence measurements and video imaging of individual particles to enumerate and characterize cells ranging from picocyanobacteria to large chaining-forming diatoms. Over a decade of observations at the Martha's Vineyard Coastal Observatory (MVCO), a cabled facility on the New England Shelf, have been compiled from repeated instrument deployments, typically 6 months or longer in duration. These multi-year high resolution (hourly to daily) time series are providing new insights into dynamics of community structure such as blooms, seasonality, and multi-year trends linked to regional climate-related variables. Similar observations in Texas coastal waters at the Texas Observatory for Algal Succession Time series (TOAST) have repeatedly provided early warning of harmful algal bloom events that threaten human and ecosystem health. As coastal ocean observing systems mature and expand, the continued integration of these type of detailed observations of the plankton will provide unparalleled information about variability and patterns of change at the base of the marine food webs, with direct implications for informed ecosystem-based management.

Intra- and interannual dynamics of dinoflagellate bloom species in the James River, an urban tidal estuary in Virginia, USA

NASA Astrophysics Data System (ADS)

Echevarria, M. A.; Mulholland, M. R.; Filippino, K.; Egerton, T.

2016-02-01

Algal blooms occur throughout the year in the tidal tributaries of Chesapeake Bay. The James River is the largest river in Virginia and third largest tributary of the Bay. Of the nearly 1500 species found in the estuary, two dinoflagellates; Heterocapsa triquetra and Cochlodinium polykrikoides have historically formed large seasonal algal blooms in spring and summer respectively, lasting several weeks to months annually. Additionally, the toxic dinoflagellate Alexandrium monilatum has emerged as an annual late summer bloom producer with increasing abundance in the region over the last nine years. These blooms have occurred in the lower James River, including meso- and polyhaline waters. Presented here are comparisons of the temporal and spatial extent and magnitude of these three dinoflagellate species over a two-year period (2014-2015). In 2014 dinoflagellate abundance was low compared to prior years. In contrast, massive spring and summer blooms occurred in 2015 with extended durations. In 2015, H. triquetra reached a maximum concentration of >84,000 cells/ml, with densities >103 cells/mL observed over a six week period, compared to no visible bloom the year before and a maximum of only 6200 cells/ml. Similarly in 2015, C. polykrikoides reached maximum cell densities of >41,000 cells/ml, with densities >103 cells/mL observed over a seven week period, compared to a maximum the year before of <11,000 cells/ml. A. monilatum reached a maximum of >7,500 cells/ml over a three week period in August 2015, with no bloom recorded in 2014. Multiple environmental parameters likely contributed to the interannual variability in bloom formation and duration. Temperature appeared to be a significant factor, with cooler than average surface water during the summer of 2014. In addition, the effect of prevailing wind patterns, precipitation, salinity, nutrient concentrations and sediment re-suspension were examined.

Macroalgal blooms alter community structure and primary productivity in marine ecosystems.

PubMed

Lyons, Devin A; Arvanitidis, Christos; Blight, Andrew J; Chatzinikolaou, Eva; Guy-Haim, Tamar; Kotta, Jonne; Orav-Kotta, Helen; Queirós, Ana M; Rilov, Gil; Somerfield, Paul J; Crowe, Tasman P

2014-09-01

Eutrophication, coupled with loss of herbivory due to habitat degradation and overharvesting, has increased the frequency and severity of macroalgal blooms worldwide. Macroalgal blooms interfere with human activities in coastal areas, and sometimes necessitate costly algal removal programmes. They also have many detrimental effects on marine and estuarine ecosystems, including induction of hypoxia, release of toxic hydrogen sulphide into the sediments and atmosphere, and the loss of ecologically and economically important species. However, macroalgal blooms can also increase habitat complexity, provide organisms with food and shelter, and reduce other problems associated with eutrophication. These contrasting effects make their overall ecological impacts unclear. We conducted a systematic review and meta-analysis to estimate the overall effects of macroalgal blooms on several key measures of ecosystem structure and functioning in marine ecosystems. We also evaluated some of the ecological and methodological factors that might explain the highly variable effects observed in different studies. Averaged across all studies, macroalgal blooms had negative effects on the abundance and species richness of marine organisms, but blooms by different algal taxa had different consequences, ranging from strong negative to strong positive effects. Blooms' effects on species richness also depended on the habitat where they occurred, with the strongest negative effects seen in sandy or muddy subtidal habitats and in the rocky intertidal. Invertebrate communities also appeared to be particularly sensitive to blooms, suffering reductions in their abundance, species richness, and diversity. The total net primary productivity, gross primary productivity, and respiration of benthic ecosystems were higher during macroalgal blooms, but blooms had negative effects on the productivity and respiration of other organisms. These results suggest that, in addition to their direct social and economic costs, macroalgal blooms have ecological effects that may alter their capacity to deliver important ecosystem services. © 2014 John Wiley & Sons Ltd.

Harmful algal bloom smart device application: using image analysis and machine learning techniques for classification of harmful algal blooms

EPA Science Inventory

Northern Kentucky University and the U.S. EPA Office of Research Development in Cincinnati Agency are collaborating to develop a harmful algal bloom detection algorithm that estimates the presence of cyanobacteria in freshwater systems by image analysis. Green and blue-green alg...

El Niño-related offshore phytoplankton bloom events around the Spratley Islands in the South China Sea

NASA Astrophysics Data System (ADS)

Isoguchi, Osamu; Kawamura, Hiroshi; Ku-Kassim, Ku-Yaacob

2005-11-01

Satellite chlorophyll-a (Chl-a) observations reveal offshore phytoplankton bloom events with high Chl-a (>1 mg m-3) spreading over 300 km off the coasts around the Spratley Islands in the South China Sea (SCS) during the spring of 1998. The bloom entails anomalous wind jet and sea surface temperature (SST) cooling, suggesting that the wind jet-induced mixing and/or offshore upwelling bring about the cooling and the bloom through the supply of nutrient-rich waters into the euphotic zone. The strong wind jet is orographically formed responding to shifts in wind direction over the eastern SCS. The wind shift is connected with the Philippine Sea anomalous anticyclone that is established during El Niño, indicating the El Niño-related offshore bloom. The long-term reanalysis winds over the eastern SCS demonstrates that wind jet formation and associated offshore cooling/bloom are expected to occur in most cases of the subsequent El Niño years.

The origin of the Ulva macroalgal blooms in the Yellow Sea in 2013.

PubMed

Zhang, Jianheng; Huo, Yuanzi; Wu, Hailong; Yu, Kefeng; Kim, Jang Kyun; Yarish, Charles; Qin, Yutao; Liu, Caicai; Xu, Ren; He, Peimin

2014-12-15

Green algal blooms have occurred in the Yellow Sea for seven consecutive years from 2007 to 2013. In this study, satellite image analysis and field shipboard observations indicated that the Ulva blooms in 2013 originated in the Rudong coast. The spatial distribution of Ulva microscopic propagules in the Southern Yellow Sea also supported that the blooms originated in the Rudong coast. In addition, multi-source satellite data were used to evaluate the biomass of green algae on the Pyropia aquaculture rafts. The results showed that approximately 2784 tons of Ulva prolifera were attached to the rafts and possessed the same internal transcribed spacer and 5S rDNA sequence as the dominant species in the 2013 blooms. We conclude that the significant biomass of Ulva species on the Pyropia rafts during the harvesting season in radial tidal sand ridges played an important role in the rapid development of blooms in the Yellow Sea. Copyright © 2014 Elsevier Ltd. All rights reserved.

Applications of satellite ocean color sensors for monitoring and predicting harmful algal blooms

USGS Publications Warehouse

Stumpf, Richard P.

2001-01-01

The new satellite ocean color sensors offer a means of detecting and monitoring algal blooms in the ocean and coastal zone. Beginning with SeaWiFS (Sea Wide Field-of-view Sensor) in September 1997, these sensors provide coverage every 1 to 2 days with 1-km pixel view at nadir. Atmospheric correction algorithms designed for the coastal zone combined with regional chlorophyll algorithms can provide good and reproducible estimates of chlorophyll, providing the means of monitoring various algal blooms. Harmful algal blooms (HABs) caused by Karenia brevis in the Gulf of Mexico are particularly amenable to remote observation. The Gulf of Mexico has relatively clear water and K. brevis, in bloom conditions, tends to produce a major portion of the phytoplankton biomass. A monitoring program has begun in the Gulf of Mexico that integrates field data from state monitoring programs with satellite imagery, providing an improved capability for the monitoring of K. brevis blooms.

A semianalytical MERIS green-red band algorithm for identifying phytoplankton bloom types in the East China Sea

NASA Astrophysics Data System (ADS)

Tao, Bangyi; Mao, Zhihua; Lei, Hui; Pan, Delu; Bai, Yan; Zhu, Qiankun; Zhang, Zhenglong

2017-03-01

A new bio-optical algorithm based on the green and red bands of the Medium Resolution Imaging Spectrometer (MERIS) is developed to differentiate the harmful algal blooms of Prorocentrum donghaiense Lu (P. donghaiense) from diatom blooms in the East China Sea (ECS). Specifically, a novel green-red index (GRI), actually an indicator for a(510) of bloom waters, is retrieved from a semianalytical bio-optical model based on the green and red bands of phytoplankton-absorption and backscattering spectra. In addition, a MERIS-based diatom index (DIMERIS) is derived by adjusting a Moderate Resolution Imaging Spectroradiometer (MODIS) diatom index algorithm to the MERIS bands. Finally, bloom types are effectively differentiated in the feature spaces of the green-red index and DIMERIS. Compared with three previous MERIS-based quasi-analytical algorithm (QAA) algorithms and three existing classification methods, the proposed GRI and classification method have the best discrimination performance when using the MERIS data. Further validations of the algorithm by using several MERIS image series and near-concurrent in situ observations indicate that our algorithm yields the best classification accuracy and thus can be used to reliably detect and classify P. donghaiense and diatom blooms in the ECS. This is the first time that the MERIS data have been used to identify bloom types in the ECS. Our algorithm can also be used for the successor of the MERIS, the Ocean and Land Color Instrument, which will aid the long-term observation of species succession in the ECS.

The Response of the North Atlantic Bloom to NAO Forcing

NASA Technical Reports Server (NTRS)

Mizoguchi, Ken-Ichi; Worthen, Denise L.; Hakkinen, Sirpa; Gregg, Watson W.

2004-01-01

Results from the climatologically forced coupled ice/ocean/biogeochemical model that covers the Arctic and North Atlantic Oceans are presented and compared to the chlorophyll fields of satellite-derived ocean color measurements. Biogeochemical processes in the model are determined from the interactions among four phytoplankton functional groups (diatoms, chlorophytes, cyanobacteria and coccolithophores) and four nutrients (nitrate, ammonium, silicate and dissolved iron). The model simulates the general large-scale pattern in April, May and June, when compared to both satellite-derived and in situ observations. The subpolar North Atlantic was cool in the 1980s and warm in the latter 1990s, corresponding to the CZCS and SeaWiFS satellite observing periods, respectively. The oceanographic conditions during these periods resemble the typical subpolar upper ocean response to the NAO+ and NAO-phases, respectively. Thus, we use the atmospheric forcing composites from the two NAO phases to simulate the variability of the mid-ocean bloom during the satellite observing periods. The model results show that when the subpolar North Atlantic is cool, the NAO+ case, more nutrients are available in early spring than when the North Atlantic is warm, the NAO-case. However, the NAO+ simulation produces a later bloom than the NAO-simulation. This difference in the bloom times is also identified in SeaWiFS and CZCS satellite measurements. In the model results, we can trace the difference to the early diatom bloom due to a warmer upper ocean. The higher nutrient abundance in the NAO+ case did not provide larger total production than in the NAO- case, instead the two cases had a comparable area averaged amplitude. This leads us to conclude that in the subpolar North Atlantic, the timing of the spring phytoplankton bloom depends on surface temperature and the magnitude of the bloom is not significantly impacted by the nutrient abundance.

The role of hydrographic parameters, measured from a ship of opportunity, in bloom formation of Karenia mikimotoi in the English Channel

NASA Astrophysics Data System (ADS)

Hartman, S. E.; Hartman, M. C.; Hydes, D. J.; Smythe-Wright, D.; Gohin, F.; Lazure, P.

2014-12-01

Unusually high chlorophyll values (~ 14 mg Chl m- 3 at 5 m depth), recorded on a ship of opportunity (SOO) in July 2010, indicated the occurrence of a potential Harmful Algal Bloom (HAB) in the Western approaches of the English Channel. This bloom, located at 49.7°N, 3.2°W was observed via complementary datasets. These included data from samples collected for microscopic phytoplankton identification, information from satellite maps to follow geographical bloom development and in situ data to identify hydrographic factors related to bloom initiation. The relationships between chlorophyll-fluorescence, temperature, salinity and wind speed were examined. The intense summer bloom predominantly consisted of the dinoflagellate Karenia mikimotoi and followed an increase in sea surface temperature (to 18.5 °C). A mid-channel bloom of this magnitude along the SOO route was last seen in 2003. In both years the peak biomass was associated with K. mikimotoi blooms, which occurred at the same location and coincided with the least saline, warmest water and lowest wind speeds. This study demonstrates that ships of opportunity are a useful tool to identify and track HAB events through continuous in situ measurements and for the frequent sampling opportunities that they provide.

The antibiotic resistome of free-living and particle-attached bacteria under a reservoir cyanobacterial bloom.

PubMed

Guo, Yunyan; Liu, Min; Liu, Lemian; Liu, Xuan; Chen, Huihuang; Yang, Jun

2018-05-04

In freshwater systems, both antibiotic resistance genes (ARGs) and cyanobacterial blooms attract global public health concern. Cyanobacterial blooms can greatly impact bacterial taxonomic communities, but very little is known about the influence of the blooms on antibiotic resistance functional community. In this study, the ARGs in both free-living (FL) and particle-attached (PA) bacteria under bloom and non-bloom conditions were simultaneously investigated in a subtropical reservoir using high-throughput approaches. In total, 145 ARGs and 9 mobile genetic elements (MGEs) were detected. The most diverse and dominant of which (68.93%) were multidrug resistance genes and efflux pump mechanism. The richness of ARGs in both FL and PA bacteria was significantly lower during the bloom period compared with non-bloom period. The abundance of ARGs in FL bacteria was significantly lower under bloom condition than in the non-bloom period, but the abundance of ARGs in PA bacteria stayed constant. More importantly, the resistant functional community in PA bacteria was more strongly influenced by the cyanobacterial bloom than in the FL bacteria, although >96% ARGs were shared in both FL and PA bacteria or both bloom and non-bloom periods. We also compared the community compositions between taxonomy and function, and found antibiotic resistant communities were highly variable and exhibited lower similarity between bloom and non-bloom periods than seen in the taxonomic composition, with an exception of FL bacteria. Altogether, cyanobacterial blooms appear to have stronger inhibitory effect on ARG abundance in FL bacteria, and stronger influence on antibiotic resistant community composition in PA bacteria. Our results further suggested that both neutral and selective processes interactively affected the ARG composition dynamics of the FL and PA bacteria. However, the antibiotic resistant community of FL bacteria exhibited a higher level of temporal stochasticity following the bloom event than PA bacteria. Therefore, we emphasized the bacterial lifestyles as an important mechanism, giving rise to different responses of antibiotic resistant community to the cyanobacterial bloom. Copyright © 2018 Elsevier Ltd. All rights reserved.

Localization and Tracking of Submerged Phytoplankton Bloom Patches by an Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Godin, M. A.; Ryan, J. P.; Zhang, Y.; Bellingham, J. G.

2012-12-01

Observing plankton in their drifting frame of reference permits effective studies of marine ecology from the perspective of microscopic life itself. By minimizing variation caused simply by advection, observations in a plankton-tracking frame of reference focus measurement capabilities on the processes that influence the life history of populations. Further, the patchy nature of plankton populations motivates use of sensor data in real-time to resolve patch boundaries and adapt observing resources accordingly. We have developed capabilities for population-centric plankton observation and sampling by autonomous underwater vehicles (AUVs). Our focus has been on phytoplankton populations, both because of their ecological significance - as the core of the oceanic food web and yet potentially harmful under certain bloom conditions, as well as the accessibility of their signal to simple optical sensing. During the first field deployment of these capabilities in 2010, we tracked a phytoplankton patch containing toxigenic diatoms and found that their toxicity correlated with exposure to resuspended sediments. However, this first deployment was labor intensive as the AUV drove in a pre-programmed pattern centered around a patch-marking drifter; it required a boat deployment of the patch-marking drifter and required full-time operators to periodically estimate of the position of the patch with respect to the drifter and adjust the AUV path accordingly. In subsequent field experiments during 2011 and 2012, the Tethys-class long-range AUVs ran fully autonomous patch tracking algorithms which detected phytoplankton patches and continually updated estimates of each patch center by driving adaptive patterns through the patch. Iterations of the algorithm were generated to overcome the challenges of tracking advecting and evolving patches while minimizing human involvement in vehicle control. Such fully autonomous monitoring will be necessary to perform long-term in-situ observation of the full growth and decay cycle of bloom patches. Doing so will enhance our understanding of the temporal and spatial dynamics of bloom patches and the observable conditions that lead to bloom formation, ultimately improving our ability to predict the evolution of harmful algal blooms (HABs) and provide warnings for the fishing and tourism industries.

Floating Algae Blooms in the East China Sea

NASA Astrophysics Data System (ADS)

Qi, Lin; Hu, Chuanmin; Wang, Mengqiu; Shang, Shaoling; Wilson, Cara

2017-11-01

A floating algae bloom in the East China Sea was observed in Moderate Resolution Imaging Spectroradiometer (MODIS) imagery in May 2017. Using satellite imagery from MODIS, Visible Infrared Imaging Radiometer Suite, Geostationary Ocean Color Imager, and Ocean Land Imager, and combined with numerical particle tracing experiments and laboratory experiments, we examined the history of this bloom as well as similar blooms in previous years and attempted to trace the bloom source and identify the algae type. Results suggest that one bloom origin is offshore Zhejiang coast where algae slicks have appeared in satellite imagery almost every February-March since 2012. Following the Kuroshio Current and Taiwan Warm Current, these "initial" algae slicks are first transported to the northeast to reach South Korea (Jeju Island) and Japan coastal waters (up to 135°E) by early April 2017, and then transported to the northwest to enter the Yellow Sea by the end of April. The transport pathway covers an area known to be rich in Sargassum horneri, and spectral analysis suggests that most of the algae slicks may contain large amount of S. horneri. The bloom covers a water area of 160,000 km2 with pure algae coverage of 530 km2, which exceeds the size of most Ulva blooms that occur every May-July in the Yellow Sea. While blooms of smaller size also occurred in previous years and especially in 2015, the 2017 bloom is hypothesized to be a result of record-high water temperature, increased light availability, and continuous expansion of Porphyra aquaculture along the East China Sea coast.

Fungal community dynamics during a marine dinoflagellate (Noctiluca scintillans) bloom.

PubMed

Sun, Jing-Yun; Song, Yu; Ma, Zhi-Ping; Zhang, Huai-Jing; Yang, Zhong-Duo; Cai, Zhong-Hua; Zhou, Jin

2017-10-01

Contamination and eutrophication have caused serious ecological events (such as algal bloom) in coastal area. During this ecological process, microbial community structure is critical for algal bloom succession. The diversity and composition of bacteria and archaea communities in algal blooms have been widely investigated; however, those of fungi are poorly understood. To fill this gap, we used pyrosequencing and correlation approaches to assess fungal patterns and associations during a dinoflagellate (Noctiluca scintillans) bloom. Phylum level fungal types were predominated by Ascomycota, Chytridiomycota, Mucoromycotina, and Basidiomycota. At the genus level drastic changes were observed with Hysteropatella, Malassezia and Saitoella dominating during the initial bloom stage, while Malassezia was most abundant (>50%) during onset and peak-bloom stages. Saitoella and Lipomyces gradually became more abundant and, in the decline stage, contributed almost 70% of sequences. In the terminal stage of the bloom, Rozella increased rapidly to a maximum of 50-60%. Fungal population structure was significantly influenced by temperature and substrate (N and P) availability (P < 0.05). Inter-specific network analyses demonstrated that Rozella and Saitoella fungi strongly impacted the ecological trajectory of N. scintillans. The functional prediction show that symbiotrophic fungi was dominated in the onset stage; saprotroph type was the primary member present during the exponential growth period; whereas pathogentroph type fungi enriched in decline phase. Overall, fungal communities and functions correlated significantly with N. scintillans processes, suggesting that they may regulate dinoflagellate bloom fates. Our results will facilitate deeper understanding of the ecological importance of marine fungi and their roles in algal bloom formation and collapse. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatiotemporal Changes of Cyanobacterial Bloom in Large Shallow Eutrophic Lake Taihu, China

PubMed Central

Qin, Boqiang; Yang, Guijun; Ma, Jianrong; Wu, Tingfeng; Li, Wei; Liu, Lizhen; Deng, Jianming; Zhou, Jian

2018-01-01

Lake Taihu is a large shallow eutrophic lake with frequent recurrence of cyanobacterial bloom which has high variable distribution in space and time. Based on the field observations and remote sensing monitoring of cyanobacterial bloom occurrence, in conjunction with laboratory controlled experiments of mixing effects on large colony formation and colonies upward moving velocity measurements, it is found that the small or moderate wind-induced disturbance would increase the colonies size and enable it more easily to overcome the mixing and float to water surface rapidly during post-disturbance. The proposed mechanism of wind induced mixing on cyanobacterial colony enlargement is associated with the presence of the extracellular polysaccharide (EPS) which increased the size and buoyancy of cyanobacteria colonies and promote the colonies aggregate at the water surface to form bloom. Both the vertical movement and horizontal migration of cyanobacterial colonies were controlled by the wind induced hydrodynamics. Because of the high variation of wind and current coupling with the large cyanobacterial colony formation make the bloom occurrence as highly mutable in space and time. This physical factor determining cyanobacterial bloom formation in the large shallow lake differ from the previously documented light-mediated bloom formation dynamics. PMID:29619011

Unexpected winter phytoplankton blooms in the North Atlantic subpolar gyre

NASA Astrophysics Data System (ADS)

Lacour, L.; Ardyna, M.; Stec, K. F.; Claustre, H.; Prieur, L.; Poteau, A.; D'Alcala, M. Ribera; Iudicone, D.

2017-11-01

In mid- and high-latitude oceans, winter surface cooling and strong winds drive turbulent mixing that carries phytoplankton to depths of several hundred metres, well below the sunlit layer. This downward mixing, in combination with low solar radiation, drastically limits phytoplankton growth during the winter, especially that of the diatoms and other species that are involved in seeding the spring bloom. Here we present observational evidence for widespread winter phytoplankton blooms in a large part of the North Atlantic subpolar gyre from autonomous profiling floats equipped with biogeochemical sensors. These blooms were triggered by intermittent restratification of the mixed layer when mixed-layer eddies led to a horizontal transport of lighter water over denser layers. Combining a bio-optical index with complementary chemotaxonomic and modelling approaches, we show that these restratification events increase phytoplankton residence time in the sunlight zone, resulting in greater light interception and the emergence of winter blooms. Restratification also caused a phytoplankton community shift from pico- and nanophytoplankton to phototrophic diatoms. We conclude that transient winter blooms can maintain active diatom populations throughout the winter months, directly seeding the spring bloom and potentially making a significant contribution to over-winter carbon export.

The Role of Silicon Limitation in Phytoplankton Phenology in a Sub-Arctic Fjord System

NASA Astrophysics Data System (ADS)

Dobbins, W.; Krause, J. W.; Agustí, S.; Duarte, C. M.; Schulz, I. K.; Winding, M.; Rowe, K. A.; Sejr, M.

2017-12-01

Bacillariophyceae (diatoms) are a significant driver of the biological pump and thus various chemical cycles in high latitude ecosystems. Diatoms have an obligate silicon requirement that has been established as a growth-limiting factor in a variety of ecosystems, and silicon availability likely plays an important role in the temporal evolution of high latitude phytoplankton blooms. However, no previous work has been done to assess the progression of this limitation across a full bloom cycle in the West Greenlandic Nuup Kangerlua fjord or equivalent systems with rapidly evolving land-sea-ice interfaces. Here we provide experimental evidence that the Nuup Kangerlua spring bloom is both diatom driven and strongly silicon constrained. Chlorophyll concentration and growth rates derived from biogenic silica measurements peaked contemporaneously; indicating diatoms were primary members of the phytoplankton assemblage. Moreover, incubation experiments revealed strong biomass increases in response to silicon additions during the bloom period. This work shows silicon availability may play a significant role in bloom phenology in the Nuup Kangerlua fjord.

Surface layer and bloom dynamics observed with the Prince William Sound Autonomous Profiler

NASA Astrophysics Data System (ADS)

Campbell, R. W.

2016-02-01

As part of a recent long term monitoring effort, deployments of a WETLabs Autonomous Moored Profiler (AMP) began Prince William Sound (PWS) in 2013. The PWS AMP consists of a positively buoyant instrument frame, with a winch and associated electronics that profiles the frame from a park depth (usually 55 m) to the surface by releasing and retrieving a thin UHMWPE tether; it generally conducts a daily cast and measures temperature, salinity, chlorophyll-a fluorescence, turbidity, and oxygen and nitrate concentrations. Upward and downward looking ADCPs are mounted on a float below the profiler, and an in situ plankton imager is in development and will be installed in 2016. Autonomous profilers are a relatively new technology, and early deployments experienced a number of failures from which valuable lessons may be learned. Nevertheless, an unprecedented time series of the seasonal biogeochemical procession in the surface waters coastal Gulf of Alaska was collected in 2014 and 2015. The northern Gulf of Alaska has experienced a widespread warm anomaly since early 2014, and surface layer temperature anomalies in PWS were strongly positive during winter 2014. The spring bloom observed by the profiler began 2-3 weeks earlier than average, with surface nitrate depleted by late April. Although surface temperatures were still above average in 2015, bloom timing was much later, with a short vigorous bloom in late April and a subsurface bloom in late May that coincided with significant nitrate drawdown. As well as the vernal blooms, wind-driven upwelling events lead to several small productivity pulses that were evident in changes in nitrate and oxygen concentrations, and chlorophyll-a fluorescence. As well as providing a mechanistic understanding of surface layer biogeochemistry, high frequency observations such as these put historical observations in context, and provide new insights into the scales of variability in the annual cycles of the surface ocean in the North Pacific.

Warming and Inhibition of Salinization at the Ocean's Surface by Cyanobacteria

NASA Astrophysics Data System (ADS)

Wurl, O.; Bird, K.; Cunliffe, M.; Landing, W. M.; Miller, U.; Mustaffa, N. I. H.; Ribas-Ribas, M.; Witte, C.; Zappa, C. J.

2018-05-01

This paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95°C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22°C) and saltier skin layer (0.19 practical salinity unit) was found in the absence of surface blooms. The results suggest that biologically controlled warming and inhibition of salinization of the ocean's surface occur. Less saline skin layers form during precipitation, but our observations also show that surface blooms of Trichodesmium sp. inhibit evaporation decreasing the salinity at the ocean's surface. This study has important implications in the assessment of precipitation over the ocean using remotely sensed salinity, but also for a better understanding of heat exchange and the hydrologic cycle on a regional scale.

The structure and toxicity of winter cyanobacterial bloom in a eutrophic lake of the temperate zone.

PubMed

Wejnerowski, Łukasz; Rzymski, Piotr; Kokociński, Mikołaj; Meriluoto, Jussi

2018-06-22

Winter cyanobacterial blooms have become increasingly common in eutrophic lakes advocating a need for their monitoring and risk assessment. The present study evaluated the toxicity of a winter cyanobacterial bloom in a eutrophicated freshwater lake located in Western Poland. The bloom was dominated by potentially toxic species: Planktothrix agardhii, Limnothrix redekei, and Aphanizomenon gracile. The toxin analysis revealed the presence of demethylated forms of microcystin-RR and microcystin-LR in ranges of 24.6-28.7 and 6.6-7.6 µg/L, respectively. The toxicity of sampled water was further evaluated in platelet-rich plasma isolated from healthy human subjects using lipid peroxidation and lactate dehydrogenase assays. No significant adverse effects were observed. The present study demonstrates that toxicity of some winter cyanobacterial blooms in the temperate zone, like that in Lubosińskie Lake, may not exhibit significant health risks despite microcystin production.

The phenomenon of bloom development of the invasive potentially toxic dinoflagellate Gonyaulax polygramma in deep water areas of the Caspian Sea

NASA Astrophysics Data System (ADS)

Pautova, L. A.; Kravchishina, M. D.; Silkin, V. A.; Lisitzin, A. P.

2017-06-01

This work presents the first data on the occurrence of the invasive, potentially toxic dinoflagellate Gonyaulax polygramma in the composition of plankton phytocenoses in the Caspian Sea. It was revealed that G. polygramma plays the key role in the quantitative characteristics of summer plankton phytocenoses and its bloom during the summer seasons of 2010 and 2013 was comparable in biomass (15-16 g/m3) to a "red tide." In addition, the correlation between the G. polygramma bloom and the wind upwelling system in the eastern mid-Caspian region was established. For the first time, it is suggested that "bloom" of G. polygramma can also occur in deep-water halistatic areas (Derbent depression), remote from the upwelling system.

Comparative Analysis of Flower Volatiles from Nine Citrus at Three Blooming Stages

PubMed Central

Azam, Muhammad; Song, Min; Fan, Fangjuan; Zhang, Bo; Xu, Yaying; Xu, Changjie; Chen, Kunsong

2013-01-01

Volatiles from flowers at three blooming stages of nine citrus cultivars were analyzed by headspace-solid phase microextraction (HS-SPME)-GC-MS. Up to 110 volatiles were detected, with 42 tentatively identified from citrus flowers for the first time. Highest amounts of volatiles were present in fully opened flowers of most citrus, except for pomelos. All cultivars were characterized by a high percentage of either oxygenated monoterpenes or monoterpene hydrocarbons, and the presence of a high percentage of nitrogen containing compounds was also observed. Flower volatiles varied qualitatively and quantitatively among citrus types during blooming. Limonene was the most abundant flower volatile only in citrons; α-citral and β-citral ranked 2nd and 3rd only for Bergamot, and unopened flowers of Ponkan had a higher amount of linalool and β-pinene while much lower amount of γ-terpinene and p-cymene than Satsuma. Taking the average of all cultivars, linalool and limonene were the top two volatiles for all blooming stages; β-pinene ranked 3rd in unopened flowers, while indole ranked 3rd for half opened and fully opened flower volatiles. As flowers bloomed, methyl anthranilate increased while 2-hexenal and p-cymene decreased. In some cases, a volatile could be high in both unopened and fully opened flowers but low in half opened ones. Through multivariate analysis, the nine citrus cultivars were clustered into three groups, consistent with the three true citrus types. Furthermore, an influence of blooming stages on clustering was observed, especially with hybrids Satsuma and Huyou. Altogether, it was suggested that flower volatiles can be suitable markers for revealing the genetic relationships between citrus cultivars but the same blooming stage needs to be strictly controlled. PMID:24232454

Comparative analysis of flower volatiles from nine citrus at three blooming stages.

PubMed

Azam, Muhammad; Song, Min; Fan, Fangjuan; Zhang, Bo; Xu, Yaying; Xu, Changjie; Chen, Kunsong

2013-11-13

Volatiles from flowers at three blooming stages of nine citrus cultivars were analyzed by headspace-solid phase microextraction (HS-SPME)-GC-MS. Up to 110 volatiles were detected, with 42 tentatively identified from citrus flowers for the first time. Highest amounts of volatiles were present in fully opened flowers of most citrus, except for pomelos. All cultivars were characterized by a high percentage of either oxygenated monoterpenes or monoterpene hydrocarbons, and the presence of a high percentage of nitrogen containing compounds was also observed. Flower volatiles varied qualitatively and quantitatively among citrus types during blooming. Limonene was the most abundant flower volatile only in citrons; α-citral and β-citral ranked 2nd and 3rd only for Bergamot, and unopened flowers of Ponkan had a higher amount of linalool and β-pinene while much lower amount of γ-terpinene and p-cymene than Satsuma. Taking the average of all cultivars, linalool and limonene were the top two volatiles for all blooming stages; β-pinene ranked 3rd in unopened flowers, while indole ranked 3rd for half opened and fully opened flower volatiles. As flowers bloomed, methyl anthranilate increased while 2-hexenal and p-cymene decreased. In some cases, a volatile could be high in both unopened and fully opened flowers but low in half opened ones. Through multivariate analysis, the nine citrus cultivars were clustered into three groups, consistent with the three true citrus types. Furthermore, an influence of blooming stages on clustering was observed, especially with hybrids Satsuma and Huyou. Altogether, it was suggested that flower volatiles can be suitable markers for revealing the genetic relationships between citrus cultivars but the same blooming stage needs to be strictly controlled.

A novel earth observation based ecological indicator for cyanobacterial blooms

NASA Astrophysics Data System (ADS)

Anttila, Saku; Fleming-Lehtinen, Vivi; Attila, Jenni; Junttila, Sofia; Alasalmi, Hanna; Hällfors, Heidi; Kervinen, Mikko; Koponen, Sampsa

2018-02-01

Cyanobacteria form spectacular mass occurrences almost annually in the Baltic Sea. These harmful algal blooms are the most visible consequences of marine eutrophication, driven by a surplus of nutrients from anthropogenic sources and internal processes of the ecosystem. We present a novel Cyanobacterial Bloom Indicator (CyaBI) targeted for the ecosystem assessment of eutrophication in marine areas. The method measures the current cyanobacterial bloom situation (an average condition of recent 5 years) and compares this to the estimated target level for 'good environmental status' (GES). The current status is derived with an index combining indicative bloom event variables. As such we used seasonal information from the duration, volume and severity of algal blooms derived from earth observation (EO) data. The target level for GES was set by using a remote sensing based data set named Fraction with Cyanobacterial Accumulations (FCA; Kahru & Elmgren, 2014) covering years 1979-2014. Here a shift-detection algorithm for time series was applied to detect time-periods in the FCA data where the level of blooms remained low several consecutive years. The average conditions from these time periods were transformed into respective CyaBI target values to represent target level for GES. The indicator is shown to pass the three critical factors set for marine indicator development, namely it measures the current status accurately, the target setting can be scientifically proven and it can be connected to the ecosystem management goal. An advantage of the CyaBI method is that it's not restricted to the data used in the development work, but can be complemented, or fully applied, by using different types of data sources providing information on cyanobacterial accumulations.

Development and Effectiveness Analysis of a Personalized Ubiquitous Multi-Device Certification Tutoring System Based on Bloom's Taxonomy of Educational Objectives

ERIC Educational Resources Information Center

Hwang, Gwo-Haur; Chen, Beyin; Huang, Cin-Wei

2016-01-01

In recent years, with the gradual increase in the importance of professional certificates, improvement in certification tutoring systems has become more important. In this study, we have developed a personalized ubiquitous multi-device certification tutoring system (PUMDCTS) based on "Bloom's Taxonomy of Educational Objectives," and…

Regulation of gene expression by the BLM helicase correlates with the presence of G-quadruplex DNA motifs

PubMed Central

Nguyen, Giang Huong; Tang, Weiliang; Robles, Ana I.; Beyer, Richard P.; Gray, Lucas T.; Welsh, Judith A.; Schetter, Aaron J.; Kumamoto, Kensuke; Wang, Xin Wei; Hickson, Ian D.; Maizels, Nancy; Monnat, Raymond J.; Harris, Curtis C.

2014-01-01

Bloom syndrome is a rare autosomal recessive disorder characterized by genetic instability and cancer predisposition, and caused by mutations in the gene encoding the Bloom syndrome, RecQ helicase-like (BLM) protein. To determine whether altered gene expression might be responsible for pathological features of Bloom syndrome, we analyzed mRNA and microRNA (miRNA) expression in fibroblasts from individuals with Bloom syndrome and in BLM-depleted control fibroblasts. We identified mRNA and miRNA expression differences in Bloom syndrome patient and BLM-depleted cells. Differentially expressed mRNAs are connected with cell proliferation, survival, and molecular mechanisms of cancer, and differentially expressed miRNAs target genes involved in cancer and in immune function. These and additional altered functions or pathways may contribute to the proportional dwarfism, elevated cancer risk, immune dysfunction, and other features observed in Bloom syndrome individuals. BLM binds to G-quadruplex (G4) DNA, and G4 motifs were enriched at transcription start sites (TSS) and especially within first introns (false discovery rate ≤ 0.001) of differentially expressed mRNAs in Bloom syndrome compared with normal cells, suggesting that G-quadruplex structures formed at these motifs are physiologic targets for BLM. These results identify a network of mRNAs and miRNAs that may drive the pathogenesis of Bloom syndrome. PMID:24958861

Regulation of gene expression by the BLM helicase correlates with the presence of G-quadruplex DNA motifs.

PubMed

Nguyen, Giang Huong; Tang, Weiliang; Robles, Ana I; Beyer, Richard P; Gray, Lucas T; Welsh, Judith A; Schetter, Aaron J; Kumamoto, Kensuke; Wang, Xin Wei; Hickson, Ian D; Maizels, Nancy; Monnat, Raymond J; Harris, Curtis C

2014-07-08

Bloom syndrome is a rare autosomal recessive disorder characterized by genetic instability and cancer predisposition, and caused by mutations in the gene encoding the Bloom syndrome, RecQ helicase-like (BLM) protein. To determine whether altered gene expression might be responsible for pathological features of Bloom syndrome, we analyzed mRNA and microRNA (miRNA) expression in fibroblasts from individuals with Bloom syndrome and in BLM-depleted control fibroblasts. We identified mRNA and miRNA expression differences in Bloom syndrome patient and BLM-depleted cells. Differentially expressed mRNAs are connected with cell proliferation, survival, and molecular mechanisms of cancer, and differentially expressed miRNAs target genes involved in cancer and in immune function. These and additional altered functions or pathways may contribute to the proportional dwarfism, elevated cancer risk, immune dysfunction, and other features observed in Bloom syndrome individuals. BLM binds to G-quadruplex (G4) DNA, and G4 motifs were enriched at transcription start sites (TSS) and especially within first introns (false discovery rate ≤ 0.001) of differentially expressed mRNAs in Bloom syndrome compared with normal cells, suggesting that G-quadruplex structures formed at these motifs are physiologic targets for BLM. These results identify a network of mRNAs and miRNAs that may drive the pathogenesis of Bloom syndrome.

Detecting Potential Water Quality Issues by Mapping Trophic Status Using Google Earth Engine

NASA Astrophysics Data System (ADS)

Nguy-Robertson, A. L.; Harvey, K.; Huening, V.; Robinson, H.

2017-12-01

The identification, timing, and spatial distribution of recurrent algal blooms and aquatic vegetation can help water managers and policy makers make better water resource decisions. In many parts of the world there is little monitoring or reporting of water quality due to the required costs and effort to collect and process water samples. We propose to use Google Earth Engine to quickly identify the recurrence of trophic states in global inland water systems. Utilizing Landsat and Sentinel multispectral imagery, inland water quality parameters (i.e. chlorophyll a concentration) can be estimated and waters can be classified by trophic state; oligotrophic, mesotrophic, eutrophic, and hypereutrophic. The recurrence of eutrophic and hypereutrophic observations can highlight potentially problematic locations where algal blooms or aquatic vegetation occur routinely. Eutrophic and hypereutrophic waters commonly include many harmful algal blooms and waters prone to fish die-offs from hypoxia. While these maps may be limited by the accuracy of the algorithms utilized to estimate chlorophyll a; relative comparisons at a local scale can help water managers to focus limited resources.

Host-virus shift of the sphingolipid pathway along an Emiliania huxleyi bloom: survival of the fattest.

PubMed

Pagarete, António; Allen, Michael J; Wilson, William H; Kimmance, Susan A; de Vargas, Colomban

2009-11-01

The interactions between viruses and phytoplankton play a key role in shaping the ecological and evolutionary dynamics of oceanic ecosystems. One of the most fascinating examples of horizontal gene transfer between a eukaryotic host and its virus is a de novo sphingolipid biosynthesis pathway (SBP) found in the genomes of both Emiliania huxleyi and its coccolithovirus EhV-86. Here, we focus on a natural E. huxleyi/coccolithovirus system off the coast of Norway and investigate the dynamics of host and virus homologous gene expression for two of the most important sphingolipid biosynthesis enzymes, serine palmitoyl transferase (SPT) and dihydroceramide desaturase (DCD). Transcriptional dynamics display three defined stages along E. huxleyi bloom formation and decline, with the coccolithovirus transcripts taking over and controlling the SBP in stages 2 and 3. The observed patterns fit the hypothesis according to which viral sphingolipids are involved in the timing and physical processes of virion release from the host cells. This study provides a unique insight into the transcriptional interplay of homologous metabolic pathways between virus and host during temporal progression of oceanic E. huxleyi blooms.

Delaying fat bloom formation in dark chocolate by adding sorbitan monostearate or cocoa butter stearin.

PubMed

Buscato, Monise Helen Masuchi; Hara, Larissa Miho; Bonomi, Élida Castilho; Calligaris, Guilherme de Andrade; Cardoso, Lisandro Pavie; Grimaldi, Renato; Kieckbusch, Theo Guenter

2018-08-01

Two formulations of dark chocolate were developed by adding cocoa butter stearin (CBSt) or sorbitan monostearate (SMS) and compared to a standard formulation in order to investigate fat bloom formation over time. Fat bloom was monitored by Whiteness Index (WI), melting behavior and polymorphism determinations, in bars stored during 90 days at 20 °C and under oscillating temperature between 20 and 32 °C. All samples stored at 20 °C did not develop fat bloom and the required β(V) form was maintained. Under oscillating storage condition, samples with CBSt (6.0%, w/w) and SMS (0.15%, w/w) delayed the surface fat bloom formation by at least 45 and 15 days, respectively, compared to standard chocolate, observed visually and through WI increments. The β(V) to β(VI) polymorphic transition correlated well with the WI, and also with changes in DSC thermograms, confirming the higher effectiveness of specific triacylglycerol (mainly StOSt) in delaying bloom formation. Copyright © 2018 Elsevier Ltd. All rights reserved.

A time-series study of the spring bloom at the Bering Sea ice edge I. Physical processes, chlorophyll and nutrient chemistry

NASA Astrophysics Data System (ADS)

Niebauer, H. J.; Alexander, Vera; Henrichs, Susan M.

1995-12-01

An intense but short-lived phytoplankton bloom develops in the low-salinity melt waters at the edge of the Bering Sea ice as the ice melts and retreats each spring. In spring 1988 we followed the development of this bloom by sampling every 3 h while following a freely drifting drogue in the marginal ice-edge zone for two four-day periods. The first period (29 April-3 May) was at an early stage of the bloom while the second period (10-13 May) was at the peak of the bloom. Early in the bloom, the phytoplankton consumed all the nitrate (˜400 mmoles m -2) initially present in the surface water producing large accumulations of particulate carbon (>1000 mmoles C m -2). By the time of peak chlorophyll concentrations (˜35 mg M -3), nitrate concentrations had been depleted so that the sustained high productivity depended on either recycled or imported nutrients. After this point, there was little net additional accumulation of biomass. From these data plus cruise data from previous years, we find that the Bering Sea ice-edge bloom typically begins in the last week of April and appears to precede blooms in the adjacent ice-free waters by days to weeks. The variability in bloom onset observed over several years is not linked very closely to the large scale climatic variations found in this region, but rather appears to be related to local weather during the end of April and the first part of May, with calm, sunny weather being required to initiate the blooms.

SERVIR: The Regional Visualization and Monitoring System

NASA Technical Reports Server (NTRS)

Irwin, Daniel E.

2010-01-01

This slide presentation reviews the SERVIR program. SERVIR is a partnership between NASA and USAID and three international nodes: Central America, Africa, and the Himalaya region. SERVIR,using satellite observations and ground based observations, is used by decision makers to allow for improved monitoring of air quality, extreme weather, biodiversity, and changes in land cove and has also been used to respond to environmental threats, such as wildfires, floods, landslides, harmful algal blooms, and earthquakes.

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

Herfort, Lydie; Peterson, Tawnya D.; McCue, Lee Ann

For at least a decade, annually recurring blooms of the photosynthetic ciliate, Myrionecta rubra have been observed in the Columbia River estuary in late summer. In an effort to understand the dynamics of these blooms, we investigated the genetic variability of M. rubra and its cryptophyte plastids within three large estuarine blooms formed in consecutive years (2007-2009), and conducted a broader spatial survey along the coasts of Oregon/Washington. Analysis of the ‘18S-28S’ sequences specific for Mesodiniidae uncovered at least 7 variants of M. rubra within the Columbia River coastal margin in spring and summer, but only one of these M.more » rubra variants was implicated in estuary bloom formation. Using a multigene approach, we show that the bloom-forming variant of M. rubra appears to harbor the same cryptophyte chloroplast in recurring blooms. Analyses of chloroplast 16S rRNA, cryptophyte RuBisCO and Photosystem II D2 genes together suggest that the plastid is derived from Teleaulax amphioxeia. Free-living cells of this species and of other cryptophytes were practically absent from the bloom patches in the estuary main channels based on 18S rDNA sequence analyses. The respectively low and high proportions of T. amphioxeia nuclei and chloroplasts signals found in the M. rubra bloom of the Columbia River estuary in successive years supports the notion of a transient association between T. amphioxeia and the bloom-forming M. rubra variant, with loss of cryptophyte nuclei. The genetic variability of M. rubra uncovered here is relevant to the controversy in the literature regarding the cryptophyte /M. rubra association.« less

Molecular insights into a dinoflagellate bloom

PubMed Central

Gong, Weida; Browne, Jamie; Hall, Nathan; Schruth, David; Paerl, Hans; Marchetti, Adrian

2017-01-01

In coastal waters worldwide, an increase in frequency and intensity of algal blooms has been attributed to eutrophication, with further increases predicted because of climate change. Yet, the cellular-level changes that occur in blooming algae remain largely unknown. Comparative metatranscriptomics was used to investigate the underlying molecular mechanisms associated with a dinoflagellate bloom in a eutrophied estuary. Here we show that under bloom conditions, there is increased expression of metabolic pathways indicative of rapidly growing cells, including energy production, carbon metabolism, transporters and synthesis of cellular membrane components. In addition, there is a prominence of highly expressed genes involved in the synthesis of membrane-associated molecules, including those for the production of glycosaminoglycans (GAGs), which may serve roles in nutrient acquisition and/or cell surface adhesion. Biotin and thiamine synthesis genes also increased expression along with several cobalamin biosynthesis-associated genes, suggesting processing of B12 intermediates by dinoflagellates. The patterns in gene expression observed are consistent with bloom-forming dinoflagellates eliciting a cellular response to elevated nutrient demands and to promote interactions with their surrounding bacterial consortia, possibly in an effort to cultivate for enhancement of vitamin and nutrient exchanges and/or direct consumption. Our findings provide potential molecular targets for bloom characterization and management efforts. PMID:27935592

Leads in Arctic pack ice enable early phytoplankton blooms below snow-covered sea ice

PubMed Central

Assmy, Philipp; Fernández-Méndez, Mar; Duarte, Pedro; Meyer, Amelie; Randelhoff, Achim; Mundy, Christopher J.; Olsen, Lasse M.; Kauko, Hanna M.; Bailey, Allison; Chierici, Melissa; Cohen, Lana; Doulgeris, Anthony P.; Ehn, Jens K.; Fransson, Agneta; Gerland, Sebastian; Hop, Haakon; Hudson, Stephen R.; Hughes, Nick; Itkin, Polona; Johnsen, Geir; King, Jennifer A.; Koch, Boris P.; Koenig, Zoe; Kwasniewski, Slawomir; Laney, Samuel R.; Nicolaus, Marcel; Pavlov, Alexey K.; Polashenski, Christopher M.; Provost, Christine; Rösel, Anja; Sandbu, Marthe; Spreen, Gunnar; Smedsrud, Lars H.; Sundfjord, Arild; Taskjelle, Torbjørn; Tatarek, Agnieszka; Wiktor, Jozef; Wagner, Penelope M.; Wold, Anette; Steen, Harald; Granskog, Mats A.

2017-01-01

The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating that satellite-based Arctic annual primary production estimates may be significantly underestimated. Here we present a unique time-series of a phytoplankton spring bloom observed beneath snow-covered Arctic pack ice. The bloom, dominated by the haptophyte algae Phaeocystis pouchetii, caused near depletion of the surface nitrate inventory and a decline in dissolved inorganic carbon by 16 ± 6 g C m−2. Ocean circulation characteristics in the area indicated that the bloom developed in situ despite the snow-covered sea ice. Leads in the dynamic ice cover provided added sunlight necessary to initiate and sustain the bloom. Phytoplankton blooms beneath snow-covered ice might become more common and widespread in the future Arctic Ocean with frequent lead formation due to thinner and more dynamic sea ice despite projected increases in high-Arctic snowfall. This could alter productivity, marine food webs and carbon sequestration in the Arctic Ocean. PMID:28102329

From Research to Operations: Transitioning Noaa's Lake Erie Harmful Algal Bloom Forecast System

NASA Astrophysics Data System (ADS)

Kavanaugh, K. E.; Stumpf, R. P.

2016-02-01

A key priority of NOAA's Harmful Algal Bloom Operational Forecast System (HAB-OFS) is to leverage the Ecological Forecasting Roadmap to systematically transition to operations scientifically mature HAB forecasts in regions of the country where there is a strong user need identified and an operational framework can be supported. While in the demonstration phase, the Lake Erie HAB forecast has proven its utility. Over the next two years, NOAA will be transitioning the Lake Erie HAB forecast to operations with an initial operating capability established in the HAB OFS' operational infrastructure by the 2016 bloom season. Blooms of cyanobacteria are a recurring problem in Lake Erie, and the dominant bloom forming species, Microcystis aeruginosa, produces a toxin called microcystin that is poisonous to humans, livestock and pets. Once the toxins have contaminated the source water used for drinking water, it is costly for public water suppliers to remove them. As part of the Lake Erie HAB forecast demonstration, NOAA has provided information regarding the cyanobacterial blooms in a biweekly Experimental HAB Bulletin, which includes information about the current and forecasted distribution, toxicity, potential for vertical mixing or scum formation, mixing of the water column, and predictions of bloom decline. Coastal resource managers, public water suppliers and public health officials use the Experimental HAB Bulletins to respond to and mitigate the impacts of cyanobacterial blooms. The transition to operations will benefit stakeholders through ensuring that future Lake Erie HAB forecast products are sustained, systematic, reliable, and robust. Once operational, the forecasts will continue to be assessed and improvements will be made based on the results of emerging scientific research. In addition, the lessons learned from the Lake Erie transition will be used to streamline the process for future HAB forecasts presently in development.

Assessment of diel chemical and isotopic techniques to investigate biogeochemical cycles in the upper Klamath River, Oregon, USA

USGS Publications Warehouse

Poulson, S.R.; Sullivan, A.B.

2009-01-01

The upper Klamath River experiences a cyanobacterial algal bloom and poor water quality during the summer. Diel chemical and isotopic techniques have been employed in order to investigate the rates of biogeochemical processes. Four diel measurements of field parameters (temperature, pH, dissolved oxygen concentrations, and alkalinity) and stable isotope compositions (dissolved oxygen-??18O and dissolved inorganic carbon-??13C) have been performed between June 2007 and August 2008. Significant diel variations of pH, dissolved oxygen (DO) concentration, and DO-??18O were observed, due to varying rates of primary productivity vs. respiration vs. gas exchange with air. Diel cycles are generally similar to those previously observed in river systems, although there are also differences compared to previous studies. In large part, these different diel signatures are the result of the low turbulence of the upper Klamath River. Observed changes in the diel signatures vs. sampling date reflect the evolution of the status of the algal bloom over the course of the summer. Results indicate the potential utility of applying diel chemical and stable isotope techniques to investigate the rates of biogeochemical cycles in slow-moving rivers, lakes, and reservoirs, but also illustrate the increased complexity of stable isotope dynamics in these low-turbulence systems compared to well-mixed aquatic systems. ?? 2009 Elsevier B.V.

Harmful algal blooms and climate change: Learning from the past and present to forecast the future

PubMed Central

Wells, Mark L.; Trainer, Vera L.; Smayda, Theodore J.; Karlson, Bengt S.O.; Trick, Charles G.; Kudela, Raphael M.; Ishikawa, Akira; Bernard, Stewart; Wulff, Angela; Anderson, Donald M.; Cochlan, William P.

2015-01-01

Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB “best practices” manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human well-being. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts. PMID:27011761

Harmful algal blooms and climate change: Learning from the past and present to forecast the future.

PubMed

Wells, Mark L; Trainer, Vera L; Smayda, Theodore J; Karlson, Bengt S O; Trick, Charles G; Kudela, Raphael M; Ishikawa, Akira; Bernard, Stewart; Wulff, Angela; Anderson, Donald M; Cochlan, William P

2015-11-01

Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB "best practices" manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human well-being. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts.

Early onset of a microcystin-producing cyanobacterial bloom in an agriculturally-influenced Great Lakes tributary

NASA Astrophysics Data System (ADS)

McKay, Robert Michael L.; Tuttle, Taylor; Reitz, Laura A.; Bullerjahn, George S.; Cody, William R.; McDowell, Adam J.; Davis, Timothy W.

2018-05-01

In late May 2016, a cyanobacterial harmful algal bloom (cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×10 9 cells/L and total microcystins (MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency (EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the cHAB were high initial nutrient loads and an increase of the river temperature from 13°C to 26°C over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin (<0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the cHAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing cHAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.

Improved monitoring of phytoplankton bloom dynamics in a Norwegian fjord by integrating satellite data, pigment analysis, and Ferrybox data with a coastal observation network

NASA Astrophysics Data System (ADS)

Volent, Zsolt; Johnsen, Geir; Hovland, Erlend K.; Folkestad, Are; Olsen, Lasse M.; Tangen, Karl; Sørensen, Kai

2011-01-01

Monitoring of the coastal environment is vitally important as these areas are of economic value and at the same time highly exposed to anthropogenic influence, in addition to variation of environmental variables. In this paper we show how the combination of bio-optical data from satellites, analysis of water samples, and a ship-mounted automatic flow-through sensor system (Ferrybox) can be used to detect and monitor phytoplankton blooms both spatially and temporally. Chlorophyll a (Chl a) data and turbidity from Ferrybox are combined with remotely sensed Chl a and total suspended matter from the MERIS instrument aboard the satellite ENVISAT (ENVIronmental SATellite) European Space Agency. Data from phytoplankton speciation and enumeration obtained by a national coastal observation network consisting of fish farms and the Norwegian Food Safety Authority are supplemented with data on phytoplankton pigments. All the data sets are then integrated in order to describe phytoplankton bloom dynamics in a Norwegian fjord over a growth season, with particular focus on Emiliania huxleyi. The approach represents a case example of how coastal environmental monitoring can be improved with existing instrument platforms. The objectives of the paper is to present the operative phytoplankton monitoring scheme in Norway, and to present an improved model of how such a scheme can be designed for a large part of the world's coastal areas.

A Quantitative Assessment of the Role of the Parasite Amoebophrya in the Termination of Alexandrium fundyense Blooms within a Small Coastal Embayment

PubMed Central

Velo-Suárez, Lourdes; Brosnahan, Michael L.; Anderson, Donald M.; McGillicuddy, Dennis J.

2013-01-01

Parasitic dinoflagellates of the genus Amoebophrya infect free-living dinoflagellates, some of which can cause harmful algal blooms (HABs). High prevalence of Amoebophrya spp. has been linked to the decline of some HABs in marine systems. The objective of this study was to evaluate the impact of Amoebophrya spp. on the dynamics of dinoflagellate blooms in Salt Pond (MA, USA), particularly the harmful species Alexandrium fundyense. The abundance of Amoebophrya life stages was estimated 3–7 days per week through the full duration of an annual A. fundyense bloom using fluorescence in situ hybridization coupled with tyramide signal amplification (FISH- TSA). More than 20 potential hosts were recorded including Dinophysis spp., Protoperidinium spp. and Gonyaulax spp., but the only dinoflagellate cells infected by Amoebophrya spp. during the sampling period were A. fundyense. Maximum A. fundyense concentration co-occurred with an increase of infected hosts, followed by a massive release of Amoebophrya dinospores in the water column. On average, Amoebophrya spp. infected and killed ∼30% of the A. fundyense population per day in the end phase of the bloom. The decline of the host A. fundyense population coincided with a dramatic life-cycle transition from vegetative division to sexual fusion. This transition occurred after maximum infected host concentrations and before peak infection percentages were observed, suggesting that most A. fundyense escaped parasite infection through sexual fusion. The results of this work highlight the importance of high frequency sampling of both parasite and host populations to accurately assess the impact of parasites on natural plankton assemblages. PMID:24324668

Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

NASA Technical Reports Server (NTRS)

Signorini, Sergio R.; Garcia, Virginia M.T.; Piola, Alberto R.; Evangelista, Heitor; McClain, Charles R.; Garcia, Carlos A.E.; Mata, Mauricio M.

2009-01-01

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed.

Proteomic Analysis of Hepatic Tissue of Cyprinus carpio L. Exposed to Cyanobacterial Blooms in Lake Taihu, China

PubMed Central

Jiang, Jinlin; Wang, Xiaorong; Shan, Zhengjun; Yang, Liuyan; Zhou, Junying; Bu, Yuanqin

2014-01-01

With the rapid development of industry and agriculture and associated pollution, the cyanobacterial blooms in Lake Taihu have become a major threat to aquatic wildlife and human health. In this study, the ecotoxicological effects of cyanobacterial blooms on cage-cultured carp (Cyprinus carpio L.) in Meiliang Bay of Lake Taihu were investigated. Microcystins (MCs), major cyanobacterial toxins, have been detected in carp cultured at different experimental sites of Meiliang Bay. We observed that the accumulation of MCs in carp was closely associated with several environmental factors, including temperature, pH value, and density of cyanobacterial blooms. The proteomic profile of carp liver exposed to cyanobacterial blooms was analyzed using two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The toxic effects of cyanobacterial blooms on carp liver were similar to changes caused by MCs. MCs were transported into liver cells and induced the excessive production of reactive oxygen species (ROS). MCs and ROS inhibited protein phosphatase and aldehyde dehydrogenase (ALDH), directly or indirectly resulting in oxidative stress and disruption of the cytoskeleton. These effects further interfered with metabolic pathways in the liver through the regulation of series of related proteins. The results of this study indicated that cyanobacterial blooms pose a major threat to aquatic wildlife in Meiliang Bay in Lake Taihu. These results provided evidence of the molecular mechanisms underlying liver damage in carp exposed to cyanobacterial blooms. PMID:24558380

Temporally dependent pollinator competition and facilitation with mass flowering crops affects yield in co-blooming crops

PubMed Central

Grab, Heather; Blitzer, Eleanor J.; Danforth, Bryan; Loeb, Greg; Poveda, Katja

2017-01-01

One of the greatest challenges in sustainable agricultural production is managing ecosystem services, such as pollination, in ways that maximize crop yields. Most efforts to increase services by wild pollinators focus on management of natural habitats surrounding farms or non-crop habitats within farms. However, mass flowering crops create resource pulses that may be important determinants of pollinator dynamics. Mass bloom attracts pollinators and it is unclear how this affects the pollination and yields of other co-blooming crops. We investigated the effects of mass flowering apple on the pollinator community and yield of co-blooming strawberry on farms spanning a gradient in cover of apple orchards in the landscape. The effect of mass flowering apple on strawberry was dependent on the stage of apple bloom. During early and peak apple bloom, pollinator abundance and yield were reduced in landscapes with high cover of apple orchards. Following peak apple bloom, pollinator abundance was greater on farms with high apple cover and corresponded with increased yields on these farms. Spatial and temporal overlap between mass flowering and co-blooming crops alters the strength and direction of these dynamics and suggests that yields can be optimized by designing agricultural systems that avoid competition while maximizing facilitation. PMID:28345653

UPWELLING EVENT IN THE DRY TORTUGAS DURING MAY 1998

EPA Science Inventory

A major macro-algae bloom was observed during a coral disease survey in May 1998 in the Dry Tortugas and New Grounds region. The significant algal growth was found only on the outer slope of reefs in depths greater than 25'; the algal bloom was not present on shallow reefs. The a...

Are the Satellite-Observed Narrow, Streaky Chlorophyll Filaments Locally Intensified by the Submesoscale Processes?

DTIC Science & Technology

2015-11-05

ecosystem health, as for example, in the development of such events as harmful algae blooms (HABs). All these emphasize the importance of further...ecosystem health, as for example, in the development of such events as harmful algae blooms (HABs). All these emphasize the importance of further

Long-term MODIS observations of cyanobacterial dynamics in Lake Taihu: Responses to nutrient enrichment and meteorological factors

PubMed Central

Shi, Kun; Zhang, Yunlin; Zhou, Yongqiang; Liu, Xiaohan; Zhu, Guangwei; Qin, Boqiang; Gao, Guang

2017-01-01

We developed and validated an empirical model for estimating chlorophyll a concentrations (Chla) in Lake Taihu to generate a long-term Chla and algal bloom area time series from MODIS-Aqua observations for 2003 to 2013. Then, based on the long-term time series data, we quantified the responses of cyanobacterial dynamics to nutrient enrichment and climatic conditions. Chla showed substantial spatial and temporal variability. In addition, the annual mean cyanobacterial surface bloom area exhibited an increasing trend across the entire lake from 2003 to 2013, with the exception of 2006 and 2007. High air temperature and phosphorus levels in the spring can prompt cyanobacterial growth, and low wind speeds and low atmospheric pressure levels favor cyanobacterial surface bloom formation. The sensitivity of cyanobacterial dynamics to climatic conditions was found to vary by region. Our results indicate that temperature is the most important factor controlling Chla inter-annual variability followed by phosphorus and that air pressure is the most important factor controlling cyanobacterial surface bloom formation followed by wind speeds in Lake Taihu. PMID:28074871

A Descriptive Content Analysis of the Extent of Bloom's Taxonomy in the Reading Comprehension Questions of the Course Book Q: Skills for Success 4 Reading and Writing

ERIC Educational Resources Information Center

Ulum, Ömer Gökhan

2016-01-01

Bloom's taxonomy is probably the most commonly used one among the cognitive process models. It is a classification system that emphasizes the procedures starting from remembering the knowledge to more complex cognitive levels like evaluating the knowledge. Firstly, the aim of this study has been to find out to what extent Bloom's taxonomy is…

Significance of Plankton Community Structure and Nutrient Availability for the Control of Dinoflagellate Blooms by Parasites: A Modeling Approach

PubMed Central

Alves-de-Souza, Catharina; Pecqueur, David; Le Floc’h, Emilie; Mas, Sébastien; Roques, Cécile; Mostajir, Behzad; Vidussi, Franscesca; Velo-Suárez, Lourdes; Sourisseau, Marc; Fouilland, Eric; Guillou, Laure

2015-01-01

Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole. PMID:26030411

Enhancement of Chlorophyll Concentration and Growing Harmful Algal Bloom Along the California Coast

NASA Astrophysics Data System (ADS)

Aceves, Joselyn; Singh, Ramesh

2016-07-01

We have carried out detailed analysis of satellite and ground data at different locations, Cal Poly, Goleta, Newport, Santa Monica, and Scripps piers and Monterey, Stearns and Santa Cruz wharfs along the California coast for the period 2008-2015. The sea surface temperature and chlorophyll concentrations derived from satellite data are analyzed together with ground observations of nitrogen, phosphorus, domoic acids and harmful algal blooms. The frequency of harmful algal blooms are found to increase in recent years depending upon the enhancement of chlorophyll concentrations and the discharges along the coast and dynamics of the sea surface temperature. The frequency of harmful algal blooms is higher in the northern California compared to southern California. The anthropogenic activities along the coast have increased which are associated with the forest fires and long range transport of dusts from Asia. The aerosol optical depth derived from satellite data during summer months seems to play an important role in the frequency of harmful algal blooms.

Dynamics of Bacterial and Fungal Communities during the Outbreak and Decline of an Algal Bloom in a Drinking Water Reservoir.

PubMed

Zhang, Haihan; Jia, Jingyu; Chen, Shengnan; Huang, Tinglin; Wang, Yue; Zhao, Zhenfang; Feng, Ji; Hao, Huiyan; Li, Sulin; Ma, Xinxin

2018-02-18

The microbial communities associated with algal blooms play a pivotal role in organic carbon, nitrogen and phosphorus cycling in freshwater ecosystems. However, there have been few studies focused on unveiling the dynamics of bacterial and fungal communities during the outbreak and decline of algal blooms in drinking water reservoirs. To address this issue, the compositions of bacterial and fungal communities were assessed in the Zhoucun drinking water reservoir using 16S rRNA and internal transcribed spacer (ITS) gene Illumina MiSeq sequencing techniques. The results showed the algal bloom was dominated by Synechococcus, Microcystis, and Prochlorothrix. The bloom was characterized by a steady decrease of total phosphorus (TP) from the outbreak to the decline period (p < 0.05) while Fe concentration increased sharply during the decline period (p < 0.05). The highest algal biomass and cell concentrations observed during the bloom were 51.7 mg/L and 1.9×108 cell/L, respectively. The cell concentration was positively correlated with CODMn (r = 0.89, p = 0.02). Illumina Miseq sequencing showed that algal bloom altered the water bacterial and fungal community structure. During the bloom, the dominant bacterial genus were Acinetobacter sp., Limnobacter sp., Synechococcus sp., and Roseomonas sp. The relative size of the fungal community also changed with algal bloom and its composition mainly contained Ascomycota, Basidiomycota and Chytridiomycota. Heat map profiling indicated that algal bloom had a more consistent effect upon fungal communities at genus level. Redundancy analysis (RDA) also demonstrated that the structure of water bacterial communities was significantly correlated to conductivity and ammonia nitrogen. Meanwhile, water temperature, Fe and ammonia nitrogen drive the dynamics of water fungal communities. The results from this work suggested that water bacterial and fungal communities changed significantly during the outbreak and decline of algal bloom in Zhoucun drinking water reservoir. Our study highlights the potential role of microbial diversity as a driving force for the algal bloom and biogeochemical cycling of reservoir ecology.

Dynamics of Bacterial and Fungal Communities during the Outbreak and Decline of an Algal Bloom in a Drinking Water Reservoir

PubMed Central

Zhang, Haihan; Jia, Jingyu; Chen, Shengnan; Huang, Tinglin; Wang, Yue; Zhao, Zhenfang; Feng, Ji; Hao, Huiyan; Li, Sulin; Ma, Xinxin

2018-01-01

The microbial communities associated with algal blooms play a pivotal role in organic carbon, nitrogen and phosphorus cycling in freshwater ecosystems. However, there have been few studies focused on unveiling the dynamics of bacterial and fungal communities during the outbreak and decline of algal blooms in drinking water reservoirs. To address this issue, the compositions of bacterial and fungal communities were assessed in the Zhoucun drinking water reservoir using 16S rRNA and internal transcribed spacer (ITS) gene Illumina MiSeq sequencing techniques. The results showed the algal bloom was dominated by Synechococcus, Microcystis, and Prochlorothrix. The bloom was characterized by a steady decrease of total phosphorus (TP) from the outbreak to the decline period (p < 0.05) while Fe concentration increased sharply during the decline period (p < 0.05). The highest algal biomass and cell concentrations observed during the bloom were 51.7 mg/L and 1.9×108 cell/L, respectively. The cell concentration was positively correlated with CODMn (r = 0.89, p = 0.02). Illumina Miseq sequencing showed that algal bloom altered the water bacterial and fungal community structure. During the bloom, the dominant bacterial genus were Acinetobacter sp., Limnobacter sp., Synechococcus sp., and Roseomonas sp. The relative size of the fungal community also changed with algal bloom and its composition mainly contained Ascomycota, Basidiomycota and Chytridiomycota. Heat map profiling indicated that algal bloom had a more consistent effect upon fungal communities at genus level. Redundancy analysis (RDA) also demonstrated that the structure of water bacterial communities was significantly correlated to conductivity and ammonia nitrogen. Meanwhile, water temperature, Fe and ammonia nitrogen drive the dynamics of water fungal communities. The results from this work suggested that water bacterial and fungal communities changed significantly during the outbreak and decline of algal bloom in Zhoucun drinking water reservoir. Our study highlights the potential role of microbial diversity as a driving force for the algal bloom and biogeochemical cycling of reservoir ecology. PMID:29463021

Quantifying the Adaptive Cycle | Science Inventory | US EPA

EPA Pesticide Factsheets

The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and

Aerial Images and Convolutional Neural Network for Cotton Bloom Detection.

PubMed

Xu, Rui; Li, Changying; Paterson, Andrew H; Jiang, Yu; Sun, Shangpeng; Robertson, Jon S

2017-01-01

Monitoring flower development can provide useful information for production management, estimating yield and selecting specific genotypes of crops. The main goal of this study was to develop a methodology to detect and count cotton flowers, or blooms, using color images acquired by an unmanned aerial system. The aerial images were collected from two test fields in 4 days. A convolutional neural network (CNN) was designed and trained to detect cotton blooms in raw images, and their 3D locations were calculated using the dense point cloud constructed from the aerial images with the structure from motion method. The quality of the dense point cloud was analyzed and plots with poor quality were excluded from data analysis. A constrained clustering algorithm was developed to register the same bloom detected from different images based on the 3D location of the bloom. The accuracy and incompleteness of the dense point cloud were analyzed because they affected the accuracy of the 3D location of the blooms and thus the accuracy of the bloom registration result. The constrained clustering algorithm was validated using simulated data, showing good efficiency and accuracy. The bloom count from the proposed method was comparable with the number counted manually with an error of -4 to 3 blooms for the field with a single plant per plot. However, more plots were underestimated in the field with multiple plants per plot due to hidden blooms that were not captured by the aerial images. The proposed methodology provides a high-throughput method to continuously monitor the flowering progress of cotton.

Abundance of the iron containing biomolecule, heme b, during the progression of a spring phytoplankton bloom in a mesocosm experiment

PubMed Central

Bellworthy, Jessica; Esposito, Mario; Achterberg, Eric P.

2017-01-01

Concentrations of heme b were determined in a mesocosm experiment situated in Gullmar Fjord off Sweden. The mesocosm experiment lasted for ca. one hundred days and was characterised by the growth of a primary nutrient replete and a secondary nutrient deplete phytoplankton bloom. Heme b varied between 40 ± 10 pmol L-1 in the prebloom period up to a maximum of 700 ± 400 pmol L-1 just prior to the time of the primary chlorophyll a maximum. Thereafter, heme b concentrations decreased again to an average of 120 ± 60 pmol L-1. When normalised to total particulate carbon, heme b was most abundant during the initiation of the nutrient replete spring bloom, when ratios reached 52 ± 24 μmol mol-1; ten times higher than values observed both pre and post the primary bloom. Concentrations of heme b correlated with those of chlorophyll a. Nevertheless, differences were observed in the relative concentrations of the two parameters, with heme b concentrations increasing relative to chlorophyll a during the growth of the primary bloom, decreasing over the period of the secondary bloom and increasing again through the latter period of the experiment. Heme b abundance was therefore influenced by nutrient concentrations and also likely by changing community composition. In half of the mesocosms, pCO2 was elevated and maintained at ca.1000 μatm, however we observed no significant differences between heme b in plus or ambient pCO2 mesocosms, either in absolute terms, or relative to total particulate carbon and chlorophyll a. The results obtained in this study contribute to our understanding of the distribution of this significant component of the biogenic iron pool, and provide an iron replete coastal water end member that aids the interpretation of the distributions of heme b in more iron deplete open ocean waters. PMID:28426768

Dynamics of cyanobacterial bloom formation during short-term hydrodynamic fluctuation in a large shallow, eutrophic, and wind-exposed Lake Taihu, China.

PubMed

Wu, Tingfeng; Qin, Boqiang; Zhu, Guangwei; Luo, Liancong; Ding, Yanqing; Bian, Geya

2013-12-01

Short-term hydrodynamic fluctuations caused by extreme weather events are expected to increase worldwide because of global climate change, and such fluctuations can strongly influence cyanobacterial blooms. In this study, the cyanobacterial bloom disappearance and reappearance in Lake Taihu, China, in response to short-term hydrodynamic fluctuations, was investigated by field sampling, long-term ecological records, high-frequency sensors and MODIS satellite images. The horizontal drift caused by the dominant easterly wind during the phytoplankton growth season was mainly responsible for cyanobacterial biomass accumulation in the western and northern regions of the lake and subsequent bloom formation over relatively long time scales. The cyanobacterial bloom changed slowly under calm or gentle wind conditions. In contrast, the short-term bloom events within a day were mainly caused by entrainment and disentrainment of cyanobacterial colonies by wind-induced hydrodynamics. Observation of a westerly event in Lake Taihu revealed that when the 30 min mean wind speed (flow speed) exceeded the threshold value of 6 m/s (5.7 cm/s), cyanobacteria in colonies were entrained by the wind-induced hydrodynamics. Subsequently, the vertical migration of cyanobacterial colonies was controlled by hydrodynamics, resulting in thorough mixing of algal biomass throughout the water depth and the eventual disappearance of surface blooms. Moreover, the intense mixing can also increase the chance for forming larger and more cyanobacterial colonies, namely, aggregation. Subsequently, when the hydrodynamics became weak, the cyanobacterial colonies continuously float upward without effective buoyancy regulation, and cause cyanobacterial bloom explosive expansion after the westerly. Furthermore, the results of this study indicate that the strong wind happening frequently during April and October can be an important cause of the formation and expansion of cyanobacterial blooms in Lake Taihu.

Are cyanobacterial blooms trophic dead ends?

PubMed

Perga, Marie-Elodie; Domaizon, Isabelle; Guillard, Jean; Hamelet, Valérie; Anneville, Orlane

2013-06-01

Cyanobacterial blooms induce significant costs that are expected to increase in the near future. Cyanobacterial resistance to zooplankton grazing is one factor thought to promote bloom events. Yet, numerous studies on zooplankton ability to graze upon cyanobacteria have been producing contradictory results and such a puzzle might arise from the lack of direct observations in situ. Our objective was to track, using fatty acid (FA) and fatty acid stable isotope analyses (FA-SIA), the fate of cyanobacterial organic matter in the food web of a lake subjected to summer blooms of Planktothrix rubescens. A metalimnetic bloom of P. rubescens occurred in Lake Bourget (France) during the study period (May-November 2009). The bloom was especially rich in α-linolenic acid, 18:3(n-3), but none of the considered zooplankton taxa exhibited spiking content in this particular FA. FA-SIA revealed, however, that over a quarter of 18:3(n-3) in small zooplankton (<500 μm) was provided by P. rubescens while large cladocerans (>500 μm) did not benefit from it. P. rubescens 18:3(n-3) could be tracked up to perch (Perca fluviatilis) young of the year (YOY) to which it contributed to ~15 % of total 18:3(n-3). Although transferred with a much lower efficiency than micro-algal organic matter, the P. rubescens bloom supported a significant share of the pelagic secondary production and did not constitute, sensu stricto, a 'trophic dead end'. The cyanobacterial bloom also provided perch YOY with components of high nutritional values at a season when these are critical for their recruitment. This cyanobacterial bloom might thus be regarded as a significant dietary bonus for juvenile fish.

Benthic‐pelagic coupling drives non‐seasonal zooplankton blooms and restructures energy flows in shallow tropical lakes

PubMed Central

Schagerl, Michael; Yasindi, Andrew; Singer, Gabriel; Kaggwa, Mary Nakabungo; Winder, Monika

2016-01-01

Abstract Zooplankton blooms are a frequent phenomenon in tropical systems. However, drivers of bloom formation and the contribution of emerging resting eggs are largely unexplored. We investigated the dynamics and the triggers of rotifer blooms in African soda‐lakes and assessed their impact on other trophic levels. A meta‐analysis of rotifer peak densities including abundances of up to 6 × 105 individuals L−1 demonstrated that rotifer bloom formation was uncoupled from the food environment and the seasonality of climatic conditions. A time series with weekly sampling intervals from Lake Nakuru (Kenya) revealed that intrinsic growth factors (food quality and the physicochemical environment) significantly affected rotifer population fluctuations, but were of minor importance for bloom formation. Instead, rotifer bloom formation was linked to sediment resuspension, a prerequisite for hatching of resting‐eggs. Population growth rates exceed pelagic birth rates and simulations of rotifer dynamics confirmed the quantitative importance of rotifer emergence from the sediment egg‐bank and signifying a decoupling of bloom formation from pelagic reproduction. Rotifer blooms led to a top‐down control of small‐sized algae and facilitated a switch to more grazing‐resistant, filamentous cyanobacteria. This shift in phytoplankton composition cascaded up the food chain and triggered the return of filter‐feeding flamingos. Calculations of consequent changes in the lake's energy budget and export of aquatic primary production to terrestrial ecosystems demonstrated the large potential impact of nonseasonal disturbances on the functioning of shallow tropical lakes. PMID:27587899

Characterizing Effects and Benefits of Beam Defocus on High Energy Laser Performance Under Thermal Blooming and Turbulence Conditions for Air-to-Ground Engagements

DTIC Science & Technology

2008-04-29

Multiple aperture laser systems for thermal blooming environments,” Applied Optics, Vol. 22, No. 21 (1 November 1983), pp. 3366-3370. 42. Siegman ...CHARACTERIZING EFFECTS AND BENEFITS OF BEAM DEFOCUS ON HIGH ENERGY LASER PERFORMANCE UNDER THERMAL BLOOMING AND TURBULENCE CONDITIONS FOR AIR...States Government. AFIT / DS / ENS / 08-05 CHARACTERIZING EFFECTS AND BENEFITS OF BEAM DEFOCUS ON HIGH ENERGY LASER PERFORMANCE UNDER THERMAL

Screening of Various Herbicide Modes of Action for Selective Control of Algae Responsible for Harmful Blooms

DTIC Science & Technology

2009-01-01

that have selective activity against harmful algal blooms (HAB). The U.S. Army Corps of Engineers is responsible for managing numerous large reservoirs...systems, some of the enzyme-inhibiting herbicides may be active against algal species responsible for harmful blooms. The U.S. Army Engineer Research...small-scale flask studies to determine if these new chemistries are active against organisms responsible for HAB and if they show potential for

Origin and fate of particulate and dissolved organic matter in a naturally iron-fertilized region of the Southern Ocean

NASA Astrophysics Data System (ADS)

Tremblay, L.; Caparros, J.; Leblanc, K.; Obernosterer, I.

2014-10-01

Natural iron fertilization of high-nutrient low-chlorophyll (HNLC) waters induces annually occurring spring phytoplankton blooms off Kerguelen Islands (Southern Ocean). To examine the origin and fate of particulate and dissolved organic matter (POM and DOM), D- and L-amino acids (AA) were quantified at bloom and HNLC stations. Total hydrolysable AA accounted for 21-25% of surface particulate organic carbon (%POCAA) at the bloom sites, but for 10% at the HNLC site. A marked decrease in %POCAA with depth was observed at the most productive stations leading to values between 3 and 5% below 300 m depth. AA contributed to only 0.9-4.4% of dissolved organic carbon (%DOCAA) at all stations. The only consistent vertical trend was observed at the most productive station (A3-2) where %DOCAA decreased from ∼2% in the surface waters to 0.9% near 300 m. These AA yields and other markers revealed that POM and DOM were more rapidly altered or mineralized at the bloom sites compared to the HNLC site. Different molecular markers indicated that POM mostly originated from diatoms and bacteria. The estimated average proportion of POM from intact phytoplankton cells in surface waters was 45% at the bloom station A3-2, but 14% at the HNLC site. Estimates based on D-AA yields indicated that ∼15% of POM and ∼30% of DOM was of bacterial origin (cells and cell fragments) at all stations. Surprisingly, the DOM in HNLC waters appeared less altered than the DOM from the bloom, had slightly higher dissolved AA concentrations, and showed no sign of alteration within the water column. Unfavorable conditions for bacterial degradation in HNLC regions can explain these findings. In contrast, large inputs of labile organic molecules and iron, likely stimulate the degradation of organic matter (priming effect) and the production of more recalcitrant DOM (microbial carbon pump) during iron-fertilized blooms.

A 280-Year Long Series of Phenological Observations of Cherry Tree Blossoming Dates for Switzerland

NASA Astrophysics Data System (ADS)

Rutishauser, T.; Luterbacher, J.; Wanner, H.

2003-04-01

Phenology is generally described as the timing of life cycle phases or activities of plants and animals in their temporal occurrence throughout the year (Lieth 1974). Recent studies have shown that meteorological and climatological impacts leave their 'fingerprints' across natural systems in general and strongly influence the seasonal activities of single animal and plant species. During the 20th century, phenological observation networks have been established around the world to document and analyze the influence of the globally changing climate to plants and wildlife. This work presents a first attempt of a unique 280-year long series of phenological observations of cherry tree blossoming dates for the Swiss plateau region. In Switzerland, a nation-wide phenological observation network has been established in 1951 currently documenting 69 phenophases of 26 different plant species. A guidebook seeks to increase objectiveness in the network observations. The observations of the blooming of the cherry tree (prunus avium) were chosen to calculate a mean series for the Swiss plateau region with observations from altitudes ranging between 370 and 860 asl. A total number of 737 observations from 21 stations were used. A linear regression was established between the mean blooming date and altitude in order to correct the data to a reference altitude level. Other ecological parameters were unaccounted for. The selected network data series from 1951 to 2000 was combined and prolonged with observations from various sources back to 1721. These include several historical observation series by farmers, clergymen and teachers, data from various stations collected at the newly established Swiss meteorological network from 1864 to 1873 and the single long series of observations from Liestal starting in 1894. The homogenized time series of observations will be compared with reconstructions of late winter temperatures as well as statistical estimations of blooming time based on long instrumental data from Europe. In addition, the series is one of the few historical phenological records to assess past climate and ecological changes. Lieth, H. (1974). Phenology and Seasonality Modeling. Berlin, Heidelberg, New York, Springer.

Winter atmospheric circulation signature for the timing of the spring bloom of diatoms in the North Sea

NASA Astrophysics Data System (ADS)

Lohmann, Gerrit; Wiltshire, Karen

2015-04-01

Analysing long-term diatom data from the German Bight and observational climate data for the period 1962-2005, we found a close connection of the inter-annual variation of the timing of the spring bloom with the boreal winter atmospheric circulation. We examined the fact that high diatom counts of the spring bloom tended to occur later when the atmospheric circulation was characterized by winter blocking over Scandinavia. The associated pattern in the sea level pressure showed a pressure dipole with two centres located over the Azores and Norway and was tilted compared to the North Atlantic Oscillation. The bloom was earlier when the cyclonic circulation over Scandinavia allowed an increased inflow of Atlantic water into the North Sea which is associated with clearer, more marine water, and warmer conditions. The bloom was later when a more continental atmospheric flow from the east was detected. At Helgoland Roads, it seems that under turbid water conditions (= low light) zooplankton grazing can affect the timing of the phytoplankton bloom negatively. Warmer water temperatures will facilitate this. Under clear water conditions, light will be the main governing factor with regard to the timing of the spring bloom. These different water conditions are shown here to be mainly related to large-scale weather patterns. We found that the mean diatom bloom could be predicted from the sea level pressure one to three months in advance. Using historical pressure data, we derived a proxy for the timing of the spring bloom over the last centuries, showing an increased number of late (proxy-) blooms during the eighteenth century when the climate was considerably colder than today. We argue that these variations are important for the interpretation of inter-annual to centennial variations of biological processes. This is of particular interest when considering future scenarios, as well to considerations on past and future effects on the primary production and food webs.

Tendencies in Coccolithophorid Blooms in Some Marine Environments of the Northern Hemisphere according to the Data of Satellite Observations in 1998-2013

NASA Astrophysics Data System (ADS)

Kondrik, D.; Pozdnyakov, D.; Pettersson, L.

2017-12-01

Based on the method developed for the delineation of E. huxleyi blooms, a new technique is achieved for (1) the automated detection of E. huxleyi blooms among coexisting massive blooms of microalgae species of other phytoplankton groups and (2) quantifying the boom surface of this type of coccolithophores. As a result, according to the data of the Climate Change Initiative Ocean Colour (OC CCI) for 1998-2013, we have obtained multiyear time series of variability in both the incidence of E. huxleyi bloom and its area in the North, Norwegian, Greenland, Barents, and Bering seas. It is found that E. huxleyi blooms propagate within the intra-annual cycle from the studied middle-latitude marine areas towards the northern areas of the Northern Atlantic Ocean (NAO) and the Arctic Ocean (AO) following the pathways of the main Gulfstream and its branches. It is also found that E. huxleyi blooms are formed annually, initially in the vicinity of the British Islands; then they successively emerge in the northward direction following the western coast of the Great Britain, turn over its northern extremity to reach, firstly, the North Sea (in May), the Norwegian Sea, and finally the Greenland Sea (in June). Then they burst out in the Barents Sea, where the typical period of blooming lasts until late August and, in some years, even to mid-September. We determine the patterns of maximal rates and duration of blooms for each of the seas studied in the Atlantic and Arctic Oceans. As for the Bering Sea, the temporal and spatial variability in the growth of E. huxleyi has an irregular pattern: after a period of remarkably high expression of this phenomenon in 1998-2001, there was an abrupt decrease in both the number and, especially, extent of bloom areas.

Does the Sverdrup critical depth model explain bloom dynamics in estuaries?

USGS Publications Warehouse

Lucas, L.V.; Cloern, J.E.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

1998-01-01

In this paper we use numerical models of coupled biological-hydrodynamic processes to search for general principles of bloom regulation in estuarine waters. We address three questions: what are the dynamics of stratification in coastal systems as influenced by variable freshwater input and tidal stirring? How does phytoplankton growth respond to these dynamics? Can the classical Sverdrup Critical Depth Model (SCDM) be used to predict the timing of bloom events in shallow coastal domains such as estuaries? We present results of simulation experiments which assume that vertical transport and net phytoplankton growth rates are horizontally homogeneous. In the present approach the temporally and spatially varying turbulent diffusivities for various stratification scenarios are calculated using a hydrodynamic code that includes the Mellor-Yamada 2.5 turbulence closure model. These diffusivities are then used in a time- and depth-dependent advection-diffusion equation, incorporating sources and sinks, for the phytoplankton biomass. Our modeling results show that, whereas persistent stratification greatly increases the probability of a bloom, semidiurnal periodic stratification does not increase the likelihood of a phytoplankton bloom over that of a constantly unstratified water column. Thus, for phytoplankton blooms, the physical regime of periodic stratification is closer to complete mixing than to persistent stratification. Furthermore, the details of persistent stratification are important: surface layer depth, thickness of the pycnocline, vertical density difference, and tidal current speed all weigh heavily in producing conditions which promote the onset of phytoplankton blooms. Our model results for shallow tidal systems do not conform to the classical concepts of stratification and blooms in deep pelagic systems. First, earlier studies (Riley, 1942, for example) suggest a monotonic increase in surface layer production as the surface layer shallows. Our model results suggest, however, a nonmonotonic relationship between phytoplankton population growth and surface layer depth, which results from a balance between several 'competing' processes, including the interaction of sinking with turbulent mixing and average net growth occurring within the surface layer. Second, we show that the traditional SCDM must be refined for application to energetic shallow systems or for systems in which surface layer mixing is not strong enough to counteract the sinking loss of phytoplankton. This need for refinement arises because of the leakage of phytoplankton from the surface layer by turbulent diffusion and sinking, processes not considered in the classical SCDM. Our model shows that, even for low sinking rates and small turbulent diffusivities, a significant % of the phytoplankton biomass produced in the surface layer can be lost by these processes.

Monitoring Bloom Dynamics of a Common Coastal Bioluminescent Ctenophore

DTIC Science & Technology

2010-09-30

photodiodes. IMPACT/APPLICATIONS More frequent and more rapidly developing jellyfish blooms, especially Mnemiopsis leidyi as well as Harmful Algal...To meet the need for a bioluminescent jellyfish monitoring and forecasting system, predictive models will depend upon dense networks of sensor

Plumes and Blooms: Observations, Analysis and Modeling for SIMBIOS

NASA Technical Reports Server (NTRS)

Maritorena, S.; Siegel, D. A.; Nelson, N. B.

2004-01-01

The goal of the Plumes and Blooms (PnB) project is to develop, validate and apply to imagery state-of-the-art ocean color algorithms for quantifying sediment plumes and phytoplankton blooms for the Case II environment of the Santa Barbara Channel. We conduct monthly to twice-monthly transect observations across the Santa Barbara Channel to develop an algorithm development and product validation data set. A primary goal is the use the PnB field data set to objectively tune semi-analytical models of ocean color for this site and apply them using available satellite imagery (SeaWiFS and MODIS). However, the comparison between PnB field observations and satellite estimates of primary products has been disappointing. We find that field estimates of water-leaving radiance correspond poorly to satellite estimates for both SeaWiFS and MODIS local area coverage imagery. We believe this is due to poor atmospheric correction due to complex mixtures of aerosol types found in these near-coastal regions.

Status, Alert System, and Prediction of Cyanobacterial Bloom in South Korea

PubMed Central

Srivastava, Ankita; Ahn, Chi-Yong; Asthana, Ravi Kumar; Lee, Hyung-Gwan; Oh, Hee-Mock

2015-01-01

Bloom-forming freshwater cyanobacterial genera pose a major ecological problem due to their ability to produce toxins and other bioactive compounds, which can have important implications in illnesses of humans and livestock. Cyanobacteria such as Microcystis, Anabaena, Oscillatoria, Phormidium, and Aphanizomenon species producing microcystins and anatoxin-a have been predominantly documented from most South Korean lakes and reservoirs. With the increase in frequency of such blooms, various monitoring approaches, treatment processes, and prediction models have been developed in due course. In this paper we review the field studies and current knowledge on toxin producing cyanobacterial species and ecological variables that regulate toxin production and bloom formation in major rivers (Han, Geum, Nakdong, and Yeongsan) and reservoirs in South Korea. In addition, development of new, fast, and high-throughput techniques for effective monitoring is also discussed with cyanobacterial bloom advisory practices, current management strategies, and their implications in South Korean freshwater bodies. PMID:25705675

A Multiscale Mapping Assessment of Lake Champlain Cyanobacterial Harmful Algal Blooms

PubMed Central

Torbick, Nathan; Corbiere, Megan

2015-01-01

Lake Champlain has bays undergoing chronic cyanobacterial harmful algal blooms that pose a public health threat. Monitoring and assessment tools need to be developed to support risk decision making and to gain a thorough understanding of bloom scales and intensities. In this research application, Landsat 8 Operational Land Imager (OLI), Rapid Eye, and Proba Compact High Resolution Imaging Spectrometer (CHRIS) images were obtained while a corresponding field campaign collected in situ measurements of water quality. Models including empirical band ratio regressions were applied to map chlorophyll-a and phycocyanin concentrations; all sensors performed well with R2 and root-mean-square error (RMSE) ranging from 0.76 to 0.88 and 0.42 to 1.51, respectively. The outcomes showed spatial patterns across the lake with problematic bays having phycocyanin concentrations >25 µg/L. An alert status metric tuned to the current monitoring protocol was generated using modeled water quality to illustrate how the remote sensing tools can inform a public health monitoring system. Among the sensors utilized in this study, Landsat 8 OLI holds the most promise for providing exposure information across a wide area given the resolutions, systematic observation strategy and free cost. PMID:26389930

Rehabilitating the cyanobacteria - niche partitioning, resource use efficiency and phytoplankton community structure during diazotrophic cyanobacterial blooms.

PubMed

Olli, Kalle; Klais, Riina; Tamminen, Timo

2015-09-01

Blooms of nitrogen-fixing cyanobacteria are recurrent phenomena in marine and freshwater habitats, and their supplying role in aquatic biogeochemical cycles is generally considered vital. The objective of this study was to analyse whether an increasing proportion of nitrogen-fixing cyanobacteria affects (i) the composition of the non-diazotrophic component of ambient phytoplankton communities and (ii) resource use efficiency (RUE; ratio of Chl a to total nutrients) - an important ecosystem function. We hypothesize that diazotrophs increase community P use and decrease N use efficiencies, as new N is brought into the system, relaxing N, and concomitantly aggravating P limitation. We test this by analysing an extensive data set from the Baltic Sea (> 3700 quantitative phytoplankton samples), known to harbour conspicuous and recurrent blooms of Nodularia spumigena and Aphanizomenon sp.System-level phosphorus use efficiency (RUE P ) was positively related to high proportion of diazotrophic cyanobacteria, suggesting aggravation of phosphorus limitation. However, concomitant decrease of nitrogen use efficiency (RUE N ) was not observed. Nodularia spumigena , a dominant diazotroph and a notorious toxin producer, had a significantly stronger relationship with RUE P , compared to the competing non-toxic Aphanizomenon sp., confirming niche differentiation in P acquisition strategies between the major bloom-forming cyanobacterial species in the Baltic Sea. Nodularia occurrences were associated with stronger temperature stratification in more offshore environments, indicating higher reliance on in situ P regeneration.By using constrained and unconstrained ordination, permutational multivariate analysis of variance and local similarity analysis, we show that diazotrophic cyanobacteria explained no more than a few percentage of the ambient phytoplankton community variation. The analyses furthermore yielded rather evenly distributed negative and positive effects on individual co-occurring phytoplankton taxa, with no obvious phylogenetic or functional trait-based patterns. Synthesis . Our study reveals that despite the widely acknowledged noxious impacts of cyanobacterial blooms, the overall effect on phytoplankton community structure is minor. There are no predominantly positive or negative associations with ambient phytoplankton species. Species-specific niche differences in cyanobacterial resource acquisition affect important ecosystem functions, such as biomass production per unit limiting resource.

Potential impact of an exceptional bloom of Karenia mikimotoi on dissolved oxygen levels in waters off western Ireland.

PubMed

O'Boyle, Shane; McDermott, Georgina; Silke, Joe; Cusack, Caroline

2016-03-01

In the summer of 2005 an exceptional bloom of the dinoflagellate Karenia mikimotoi occurred along Ireland's Atlantic seaboard and was associated with the mass mortality of both benthic and pelagic marine life. Oxygen depletion, cellular toxicity and physical smothering, are considered to be the main factors involved in mortality. In this paper we use a theoretical approach based on stoichiometry (the Anderson ratio) and an average K. mikimotoi cellular carbon content of 329pgCcell -1 (n=20) to calculate the carbonaceous and nitrogenous oxygen demand following bloom collapse. The method was validated against measurements of biochemical oxygen demand and K. mikimotoi cell concentration. The estimated potential oxygen utilisation (POU) was in good agreement with field observations across a range of cell concentrations. The magnitude of POU following bloom collapse, with the exception of three coastal areas, was considered insufficient to cause harm to most marine organisms. This indicates that the widespread occurrence of mortality was primarily due to other factors such as cellular toxicity and/or mucilage production, and not oxygen depletion or related phenomena. In Donegal Bay, Kilkieran Bay and inner Dingle Bay, where cell densities were in the order of 10 6 cellsL -1 , estimated POU was sufficient to cause hypoxia. Of the three areas, Donegal Bay is considered to be the most vulnerable due to its hydrographic characteristics (seasonally stratified, weak residual flow) and hypoxic conditions (2.2mgL -1 O 2 ) were directly observed in the Bay post bloom collapse. Here, depending on the time of bloom collapse, depressed DO levels could persist for weeks and continue to have a potentially chronic impact on the Bay. Copyright © 2015 Elsevier B.V. All rights reserved.

Spatiotemporal associations of reservoir nutrient characteristics and the invasive, harmful alga Prymnesium parvum in West Texas

USGS Publications Warehouse

VanLandeghem, Matthew M.; Farooqi, Mukhtar; Southard, Greg M.; Patino, Reynaldo

2015-01-01

Golden alga (Prymnesium parvum) is a harmful alga that has caused ecological and economic harm in freshwater and marine systems worldwide. In inland systems of North America, toxic blooms have nearly eliminated fish populations in some systems. Modifying nutrient profiles through alterations to land or water use may be a viable alternative for golden alga control in reservoirs. The main objective of this study was to improve our understanding of the nutrient dynamics that influence golden alga bloom formation and toxicity in west Texas reservoirs. We examined eight sites in the Upper Colorado River basin, Texas: three impacted reservoirs that have experienced repeated golden alga blooms; two reference reservoirs where golden alga is present but nontoxic; and three confluence sites downstream of the impacted and reference sites. Total, inorganic, and organic nitrogen and phosphorus and their ratios were quantified monthly along with golden alga abundance and ichthyotoxicity between December 2010 and July 2011. Blooms persisted for several months at the impacted sites, which were characterized by high organic nitrogen and low inorganic nitrogen. At impacted sites, abundance was positively associated with inorganic phosphorus and bloom termination coincided with increases in inorganic nitrogen and decreases in inorganic phosphorus in late spring. Management of both inorganic and organic forms of nutrients may create conditions in reservoirs unfavorable to golden alga.

Shallow water processes govern system-wide phytoplankton bloom dynamics: A modeling study

USGS Publications Warehouse

Lucas, L.V.; Koseff, Jeffrey R.; Monismith, Stephen G.; Thompson, J.K.

2009-01-01

A pseudo-two-dimensional numerical model of estuarine phytoplankton growth and consumption, vertical turbulent mixing, and idealized cross-estuary transport was developed and applied to South San Francisco Bay. This estuary has two bathymetrically distinct habitat types (deep channel, shallow shoal) and associated differences in local net rates of phytoplankton growth and consumption, as well as differences in the water column's tendency to stratify. Because many physical and biological time scales relevant to algal population dynamics decrease with decreasing depth, process rates can be especially fast in the shallow water. We used the model to explore the potential significance of hydrodynamic connectivity between a channel and shoal and whether lateral transport can allow physical or biological processes (e.g. stratification, benthic grazing, light attenuation) in one sub-region to control phytoplankton biomass and bloom development in the adjacent sub-region. Model results for South San Francisco Bay suggest that lateral transport from a productive shoal can result in phytoplankton biomass accumulation in an adjacent deep, unproductive channel. The model further suggests that turbidity and benthic grazing in the shoal can control the occurrence of a bloom system-wide; whereas, turbidity, benthic grazing, and vertical density stratification in the channel are likely to only control local bloom occurrence or modify system-wide bloom magnitude. Measurements from a related field program are generally consistent with model-derived conclusions. ?? 2008 Elsevier B.V.

Comparison of cooperative and non-cooperative adaptive optics reference performance for propagation with thermal blooming effects

NASA Astrophysics Data System (ADS)

Edwards, Brian E.; Nitkowski, Arthur; Lawrence, Ryan; Horton, Kasey; Higgs, Charles

2004-10-01

Atmospheric turbulence and laser-induced thermal blooming effects can degrade the beam quality of a high-energy laser (HEL) weapon, and ultimately limit the amount of energy deliverable to a target. Lincoln Laboratory has built a thermal blooming laboratory capable of emulating atmospheric thermal blooming and turbulence effects for tactical HEL systems. The HEL weapon emulation hardware includes an adaptive optics beam delivery system, which utilizes a Shack-Hartman wavefront sensor and a 349 actuator deformable mirror. For this experiment, the laboratory was configured to emulate an engagement scenario consisting of sea skimming target approaching directly toward the HEL weapon at a range of 10km. The weapon utilizes a 1.5m aperture and radiates at a 1.62 micron wavelength. An adaptive optics reference beam was provided as either a point source located at the target (cooperative) or a projected point source reflected from the target (uncooperative). Performance of the adaptive optics system was then compared between reference sources. Results show that, for operating conditions with a thermal blooming distortion number of 75 and weak turbulence (Rytov of 0.02 and D/ro of 3), cooperative beacon AO correction experiences Phase Compensation Instability, resulting in lower performance than a simple, open-loop condition. The uncooperative beacon resulted in slightly better performance than the open-loop condition.

Can We Drink the Water? Data Sharing Lessons From the Great Lakes

NASA Astrophysics Data System (ADS)

Aufdenkampe, A. K.; Paige, K.; Slawecki, T. A.

2017-12-01

The Great Lakes Observing System (GLOS) is one of 11 regional associations of the Integrated Ocean Observing System (IOOS). Over time, GLOS has built a reputation as a trusted data aggregator and resource for managers, policy makers and recreational boaters in the region. This was evidenced best when, in response to the 2014 Lake Erie harmful algal bloom event, local stakeholders including universities, state government, and municipal water managers turned to GLOS as a repository for sharing and finding data. The IOOS Certification process, required under the authority of the Integrated Coastal and Ocean Observation System Act of 2009 (ICOOS Act), further legitimizes these data assembly centers that serve as valuable coordinators of data for their regions.

Can phytoplankton maintain a positive carbon balance in a turbid, freshwater, tidal estuary

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

Cole, J.J.; Caraco, N.F.; Peierls, B.L.

1992-12-01

An analysis of phytoplankton primary production in the tidal freshwater portion of the Hudson River estuary suggests that net primary production is strongly limited by light and mixing regime. In this turbid, well-mixed system, cells spend from 18 to 22 h d[sup [minus]1] below the 1% light level. Autotrophic dark respiration, conservatively estimated at 5% of P[sup b][sub max], is of sufficient magnitude to make positive algal growth impossible over much of the river and much of the year. It is particularly difficult to explain the observed increase in algal biomass during blooms in spring and summer. The authors hypothesizemore » that such blooms can occur only in a small fraction of the river where depth is [approx lt]4 m. 32 refs., 10 figs.« less

Numerical analysis of hybrid adaptive optics system for correcting beacon anisoplanatism and thermal blooming

NASA Astrophysics Data System (ADS)

Belen'kii, Mikhail S.; Rye, Vincent; Runyeon, Hope

2007-09-01

A concept of a Hybrid Wavefront-based Stochastic Parallel Gradient Decent (WSPGD) Adaptive Optics (AO) system for correcting the combined effects of Beacon Anisoplanatism and Thermal Blooming is introduced. This system integrates a conventional phase conjugate (PC) AO system with a WSPGD AO system. It uses on-axis wavefront measurements of a laser return from an extended beacon to generate initial deformable mirror (DM) commands. Since high frequency phase components are removed from the wavefront of a laser return by a low-pass filter effect of an extended beacon, the system also uses off-axis wavefront measurements to provide feedback for a multi-dithering beam control algorithm in order to generate additional DM commands that account for those missing high frequency phase components. Performance of the Hybrid WSPGD AO system was evaluated in simulation using a wave optics code. Numerical analysis was performed for two tactical scenarios that included ranges of L = 2 km and L = 20 km, ratio of aperture diameter to Fried parameter, D/r 0, of up to 15, ratio of beam spot size at the target to isoplanatic angle, θ B/θ 0, of up to 40, and general distortion number characterizing the strength of Thermal Blooming, N d = 50, 75, and 100. A line-of-sight in the corrected beam was stabilized using a target-plane tracker. The simulation results reveal that the Hybrid WSPGD AO system can efficiently correct the effects of Beacon Anisoplanatism and Thermal Blooming, providing improved compensation of Thermal Blooming in the presence of strong turbulence. Simulation results also indicate that the Hybrid WSPGD AO system outperforms a conventional PC AO system, increasing the Strehl ratio by up to 300% in less than 50 iterations. A follow-on laboratory demonstration performed under a separate program confirmed our theoretical predictions.

Alexandrium minutum resting cyst distribution dynamics in a confined site

NASA Astrophysics Data System (ADS)

Anglès, Sílvia; Jordi, Antoni; Garcés, Esther; Basterretxea, Gotzon; Palanques, Albert

2010-02-01

The life cycle of the toxic dinoflagellate Alexandrium minutum consists of an asexual stage, characterized by motile vegetative cells, and a sexual stage, a resting cyst that once formed remains dormant in the sediment. Insight into the factors that determine the distribution and abundance of resting cysts is essential to understanding the dynamics of the vegetative phase. In investigations carried out between January 2005 and January 2008 in Arenys de Mar harbor (northwestern Mediterranean Sea), the spatial and temporal distribution patterns of A. minutum resting cysts and of the sediments were studied during different bloom stages of the vegetative population. Maximum cyst abundance was recorded mainly in the innermost part of the harbor while the lowest abundance always occurred near the harbor entrance, consistent with the distribution of silt-clay sediment fractions. The tendency of cysts in sediments to increase after bloom periods was clearly associated with new cyst formation, while cyst abundance decreased during non-bloom periods. Exceptions to this trend were observed in stations dominated by the deposition of coarse sediments. High correlation between the presence of cysts and clays during non-bloom periods indicates that cysts behave as passive sediment particles and are influenced by the same hydrodynamic processes as clays. In Arenys de Mar, the main physical forcing affecting sediment resuspension is the seiche, which was studied using in situ measurements and numerical models to interpret the observed distribution patterns. During non-bloom periods, cyst losses were smaller when the seiche was more active and at the station where the seiche-induced current was larger. Thus, seiche-forced resuspension appears to reduce cyst losses by reallocating cysts back to the sediment surface such that their burial in the sediment is avoided. The observed vertical profiles of the cysts were consistent with this process.

The 2008 North Atlantic Spring Bloom Experiment II: Autonomous Platforms and Mixed Layer Evolution

NASA Astrophysics Data System (ADS)

Lee, C. M.; D'Asaro, E. A.; Perry, M.; Fennel, K.; Gray, A.; Rehm, E.; Briggs, N.; Sackmann, B. S.; Gudmundsson, K.

2008-12-01

The 2008 North Atlantic Spring Bloom Experiment (NAB08) employed a system of drifting floats, mobile gliders and ship-based measurements to resolve patch-scale physical and biological variability over the 3- month course of an entire bloom. Although both autonomous and ship-based elements were essential to achieving NAB08 goals, the autonomous system provided a novel perspective by employing long-range gliders to repeatedly survey the volume surrounding a drifting Lagrangian float, thus characterizing patch- scale bloom evolution. Integration of physical and biogeochemical sensors (temperature, conductivity, dissolved oxygen, chlorophyll and CDOM fluorescence, light transmission, optical backscatter, spectral light, and nitrate) and development of in situ calibration techniques were required to support this new autonomous approach. Energetic, small-scale eddy activity at the experiment site (southeast of Iceland, near the Joint Global Ocean Flux Study and Marine Light Mixed Layer sites) produced a swift, heterogeneous velocity field that challenged the gliders" operational abilities and drove refinements to the piloting techniques used to maintain float-following surveys. Although intentionally deployed outside of energetic eddies, floats and gliders were rapidly entrained into these features. Floats circulated within eddies near the start and end of the experiment, drifting generally northwest, across the basin, in-between. An eddy sampled late in the deployment provided particularly interesting signatures, with elevated biological signals manifest consistently in one quadrant. As measurements were collected in a parcel-following Lagrangian frame, this suggests energetic small-scale exchange process (such as vertical or lateral mixing) paired with fast-acting biological processes capable of modifying the newly entrained water as it navigates its path around the eddy. Despite this energetic kilometer-scale heterogeneity, broadly distributed platforms appeared to experience similar broad, long-timescale trends. Initial mixed layer depths exceeded 200 m, with gradual shoaling punctuated by periods of rapid, storm-driven deepening. In mid-April, a period of calm weather, rapid restratification and exponentially growing chlorophyll fluorescence marks the bloom's start. Although one-dimensional processes (e.g. diapycnal mixing and solar warming) clearly play important roles in producing the spring bloom, the rate and vertical extent of upper ocean restratification indicate that lateral mixing, perhaps wind- or eddy-driven exchange or the slumping of lateral density contrasts, play a more important role in restratifying the upper ocean. These important trigger events present a severe observational challenge as they take place at small (kilometers) spatial scales, are fully three-dimensional and episodic in time. The NAB08 efforts demonstrate how mobile, autonomous platforms can be exploited to resolve these events and their impact over the course of an entire bloom cycle.

Possible importance of algal toxins in the Salton Sea, California

USGS Publications Warehouse

Reifel, K.M.; McCoy, M.P.; Rocke, T.E.; Tiffany, M.A.; Hurlbert, S.H.; Faulkner, D.J.

2002-01-01

In response to wildlife mortality including unexplained eared grebe (Podiceps nigricollis) die-off events in 1992 and 1994 and other mortality events including large fish kills, a survey was conducted for the presence of algal toxins in the Salton Sea. Goals of this survey were to determine if and when algal toxins are present in the Salton Sea and to describe the phytoplankton composition during those times. A total of 29 samples was collected for toxicity analysis from both nearshore and midlake sites visited biweekly from January to December 1999. Dinoflagellates and diatoms dominated most samples, but some were dominated by a prymnesiophyte (Pleurochrysis pseudoroscoffensis) or a raphidophyte (Chattonella marina). Several types of blooms were observed and sampled. The dinoflagellate Gyrodinium uncatenum formed an extensive, dense (up to 310 000 cells ml−1) and long-lasting bloom during the winter in 1999. A coccolithophorid, Pleurochrysis pseudoroscoffensis, occurred at high densities in surface films and nearshore areas during the spring and summer of 1999. These surface films also contained high densities of one or two other species (an unidentified scrippsielloid, Heterocapsa niei, Chattonella marina). Localized blooms were also observed in the Salton Sea. An unknown small dinoflagellate reached high densities (110 000 cells ml−1) inside Varner Harbor, and an unidentified species of Gymnodinium formed a dense (270 000 cells ml−1) band along part of the southern shoreline during the summer. Three species known to produce toxins in other systems were found. Protoceratium reticulatum (=Gonyaulax grindleyi) and Chattonella marina were found in several samples taken during summer months, and Prorocentrum minimum was found in low densities in several samples. Extracts of most samples, including those containing known toxic species, showed a low level (<10% mortality across all concentrations) of activity in the brine shrimp lethality assay and were not considered toxic. All sample extracts tested in the mouse bioassay showed no activity. One sample extract taken from the bloom of the small dinoflagellate was highly active (100% mortality across all concentrations) in the brine shrimp lethality assay, but the active material could not be isolated. While dense algal blooms are common at the Salton Sea, no evidence gathered in this study suggests that algal toxins are present within phytoplankton cells; however, toxins actively excreted by cells may have been missed. Blooms of phytoplankton likely contribute to wildlife mortality at the Salton Sea. Possible mechanisms including intoxication due to ingestion of feathers in grebes and waterlogging caused by changes in surface tension are discussed.

The physical oceanography of upwelling systems and the development of harmful algal blooms

PubMed Central

Pitcher, G.C.; Figueiras, F.G.; Hickey, B.M.; Moita, M.T.

2011-01-01

The upwelling systems of the eastern boundaries of the world’s oceans are susceptible to harmful algal blooms (HABs) because they are highly productive, nutrient-rich environments, prone to high-biomass blooms. This review identifies those aspects of the physical environment important in the development of HABs in upwelling systems through description and comparison of bloom events in the Benguela, California and Iberia systems. HAB development is dictated by the influence of wind stress on the surface boundary layer through a combination of its influence on surface mixed-layer characteristics and shelf circulation patterns. The timing of HABs is controlled by windstress fluctuations and buoyancy inputs at the seasonal, event and interannual scales. Within this temporal framework, various mesoscale features that interrupt typical upwelling circulation patterns, determine the spatial distribution of HABs. The inner shelf in particular provides a mosaic of shifting habitats, some of which favour HABs. Changes in coastline configuration and orientation, and bottom topography are important in determining the distribution of HABs through their influence on water stratification and retention. A spectrum of coastline configurations, including headlands, capes, peninsulas, Rías, bays and estuaries, representing systems of increasing isolation from the open coast and consequent increasing retention times, are assessed in terms of their vulnerability to HABs. PMID:22053120

Developing Predictive Models for Algal Bloom Occurrence and Identifying Factors Controlling their Occurrence in the Charlotte County and Surroundings

NASA Astrophysics Data System (ADS)

Karki, S.; Sultan, M.; Elkadiri, R.; Chouinard, K.

2017-12-01

Numerous occurrences of harmful algal blooms (Karenia Brevis) were reported from Southwest Florida along the coast of Charlotte County, Florida. We are developing data-driven (remote sensing, field, and meteorological data) models to accomplish the following: (1) identify the factors controlling bloom development, (2) forecast bloom occurrences, and (3) make recommendations for monitoring variables that are found to be most indicative of algal bloom occurrences and for identifying optimum locations for monitoring stations. To accomplish these three tasks we completed/are working on the following steps. Firstly, we developed an automatic system for downloading and processing of ocean color data acquired through MODIS Terra and MODIS Aqua products using SeaDAS ocean color processing software. Examples of extracted variables include: chlorophyll a (OC3M), chlorophyll a Generalized Inherent Optical Property (GIOP), chlorophyll a Garver-Siegel- Maritorena (GSM), sea surface temperature (SST), Secchi disk depth, euphotic depth, turbidity index, wind direction and speed, colored dissolved organic material (CDOM). Secondly we are developing a GIS database and a web-based GIS to host the generated remote sensing-based products in addition to relevant meteorological and field data. Examples of the meteorological and field inputs include: precipitation amount and rates, concentrations of nitrogen, phosphorous, fecal coliform and Dissolved Oxygen (DO). Thirdly, we are constructing and validating a multivariate regression model and an artificial neural network model to simulate past algal bloom occurrences using the compiled archival remote sensing, meteorological, and field data. The validated model will then be used to predict the timing and location of algal bloom occurrences. The developed system, upon completion, could enhance the decision making process, improve the citizen's quality of life, and strengthen the local economy.

Coupled effects of vertical mixing and benthic grazing on phytoplankton populations in shallow, turbid estuaries

USGS Publications Warehouse

Koseff, Jeffrey R.; Holen, Jacqueline K.; Monismith, Stephen G.; Cloern, James E.

1993-01-01

Coastal ocean waters tend to have very different patterns of phytoplankton biomass variability from the open ocean, and the connections between physical variability and phytoplankton bloom dynamics are less well established for these shallow systems. Predictions of biological responses to physical variability in these environments is inherently difficult because the recurrent seasonal patterns of mixing are complicated by aperiodic fluctuations in river discharge and the high-frequency components of tidal variability. We might expect, then, less predictable and more complex bloom dynamics in these shallow coastal systems compared with the open ocean. Given this complex and dynamic physical environment, can we develop a quantitative framework to define the physical regimes necessary for bloom inception, and can we identify the important mechanisms of physical-biological coupling that lead to the initiation and termination of blooms in estuaries and shallow coastal waters? Numerical modeling provides one approach to address these questions. Here we present results of simulation experiments with a refined version of Cloern's (1991) model in which mixing processes are treated more realistically to reflect the dynamic nature of turbulence generation in estuaries. We investigated several simple models for the turbulent mixing coefficient. We found that the addition of diurnal tidal variation to Cloern's model greatly reduces biomass growth indicating that variations of mixing on the time scale of hours are crucial. Furthermore, we found that for conditions representative of South San Francisco Bay, numerical simulations only allowed for bloom development when the water column was stratified and when minimal mixing was prescribed in the upper layer. Stratification, however, itself is not sufficient to ensure that a bloom will develop: minimal wind stirring is a further prerequisite to bloom development in shallow turbid estuaries with abundant populations of benthic suspension feeders.

Assessing Insecticide Hazard to Bumble Bees Foraging on Flowering Weeds in Treated Lawns

PubMed Central

Larson, Jonathan L.; Redmond, Carl T.; Potter, Daniel A.

2013-01-01

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees. PMID:23776667

Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns.

PubMed

Larson, Jonathan L; Redmond, Carl T; Potter, Daniel A

2013-01-01

Maintaining bee-friendly habitats in cities and suburbs can help conserve the vital pollination services of declining bee populations. Despite label precautions not to apply them to blooming plants, neonicotinoids and other residual systemic insecticides may be applied for preventive control of lawn insect pests when spring-flowering weeds are present. Dietary exposure to neonicotinoids adversely affects bees, but the extent of hazard from field usage is controversial. We exposed colonies of the bumble bee Bombus impatiens to turf with blooming white clover that had been treated with clothianidin, a neonicotinoid, or with chlorantraniliprole, the first anthranilic diamide labeled for use on lawns. The sprays were applied at label rate and lightly irrigated. After residues had dried, colonies were confined to forage for six days, and then moved to a non-treated rural site to openly forage and develop. Colonies exposed to clothianidin-treated weedy turf had delayed weight gain and produced no new queens whereas those exposed to chlorantraniliprole-treated plots developed normally compared with controls. Neither bumble bees nor honey bees avoided foraging on treated white clover in open plots. Nectar from clover blooms directly contaminated by spray residues contained 171±44 ppb clothianidin. Notably, neither insecticide adversely impacted bee colonies confined on the treated turf after it had been mown to remove clover blooms present at the time of treatment, and new blooms had formed. Our results validate EPA label precautionary statements not to apply neonicotinoids to blooming nectar-producing plants if bees may visit the treatment area. Whatever systemic hazard through lawn weeds they may pose appears transitory, however, and direct hazard can be mitigated by adhering to label precautions, or if blooms inadvertently are contaminated, by mowing to remove them. Chlorantraniliprole usage on lawns appears non-hazardous to bumble bees.

Climate anomalies generate an exceptional dinoflagellate bloom in San Francisco Bay

USGS Publications Warehouse

Cloern, J.E.; Schraga, T.S.; Lopez, C.B.; Knowles, N.; Grover, Labiosa R.; Dugdale, R.

2005-01-01

We describe a large dinoflagellate bloom, unprecedented in nearly three decades of observation, that developed in San Francisco Bay (SFB) during September 2004. SFB is highly enriched in nutrients but has low summer-autumn algal biomass because wind stress and tidally induced bottom stress produce a well mixed and light-limited pelagic habitat. The bloom coincided with calm winds and record high air temperatures that stratified the water column and suppressed mixing long enough for motile dinoflagellates to grow and accumulate in surface waters. This event-scale climate pattern, produced by an upper-atmosphere high-pressure anomaly off the U.S. west coast, followed a summer of weak coastal upwelling and high dinoflagellate biomass in coastal waters that apparently seeded the SFB bloom. This event suggests that some red tides are responses to changes in local physical dynamics that are driven by large-scale atmospheric processes and operate over both the event scale of biomass growth and the antecedent seasonal scale that shapes the bloom community. Copyright 2005 by the American Geophysical Union.

FerryBox and MERIS Assessment of coastal and shelf sea ecosystems by combining in situ and remotely sensed data

NASA Astrophysics Data System (ADS)

Petersen, W.; Wehde, H.; Krasemann, H.; Colijn, F.; Schroeder, F.

2008-04-01

An automatic measuring system called " FerryBox" was installed in the North Sea on a ferry travelling between Germany (Cuxhaven) and Great Britain (Harwich), enabling online oceanographic and biological measurements such as salinity, temperature, fluorescence, turbidity, oxygen, pH, and nutrient concentrations. Observations made along the ferry transect reveal characteristic phenomena such as high salinity inflow through the Channel into the Southern Bight, algal bloom dynamics and related oxygen and pH changes. Combination of these online observations with remote sensing enhances the spatial resolution of the transect related measurements. Several examples of the synergy between these two measuring strategies are shown, both for large-scale algal blooms in the North Sea as well as for local intense but short-term blooms in the German Bight. Coherence of the data sets can be gained and improved by using water transport models in order to obtain synoptic overviews of the remotely sensed and FerryBox related parameters. Limitations of the currently used algorithms for deriving chlorophyll- a from remote sensing images for coastal and shelf seas (Case-2 water) are discussed, as well as depth related processes which cannot be properly resolved on the basis of water intake at a fixed point. However, in unstratified coastal waters under normal conditions FerryBox data represent average conditions. The importance of future applications of this combination of methods for monitoring of coastal waters is emphasized.

Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean.

PubMed

Alexander, Harriet; Rouco, Mónica; Haley, Sheean T; Wilson, Samuel T; Karl, David M; Dyhrman, Sonya T

2015-11-03

A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited. We used eukaryotic metatranscriptomic techniques to identify the metabolic basis of functional group-specific traits that may drive the shift between net heterotrophy and autotrophy in the oligotrophic ocean. Replicated blooms were simulated by deep seawater (DSW) addition to mimic nutrient loading in the North Pacific Subtropical Gyre, and the transcriptional responses of phytoplankton functional groups were assayed. Responses of the diatom, haptophyte, and dinoflagellate functional groups in simulated blooms were unique, with diatoms and haptophytes significantly (95% confidence) shifting their quantitative metabolic fingerprint from the in situ condition, whereas dinoflagellates showed little response. Significantly differentially abundant genes identified the importance of colimitation by nutrients, metals, and vitamins in eukaryotic phytoplankton metabolism and bloom formation in this system. The variable transcript allocation ratio, used to quantify transcript reallocation following DSW amendment, differed for diatoms and haptophytes, reflecting the long-standing paradigm of phytoplankton r- and K-type growth strategies. Although the underlying metabolic potential of the large eukaryotic phytoplankton was consistently present, the lack of a bloom during the study period suggests a crucial dependence on physical and biogeochemical forcing, which are susceptible to alteration with changing climate.

Functional group-specific traits drive phytoplankton dynamics in the oligotrophic ocean

PubMed Central

Alexander, Harriet; Rouco, Mónica; Haley, Sheean T.; Wilson, Samuel T.; Karl, David M.; Dyhrman, Sonya T.

2015-01-01

A diverse microbial assemblage in the ocean is responsible for nearly half of global primary production. It has been hypothesized and experimentally demonstrated that nutrient loading can stimulate blooms of large eukaryotic phytoplankton in oligotrophic systems. Although central to balancing biogeochemical models, knowledge of the metabolic traits that govern the dynamics of these bloom-forming phytoplankton is limited. We used eukaryotic metatranscriptomic techniques to identify the metabolic basis of functional group-specific traits that may drive the shift between net heterotrophy and autotrophy in the oligotrophic ocean. Replicated blooms were simulated by deep seawater (DSW) addition to mimic nutrient loading in the North Pacific Subtropical Gyre, and the transcriptional responses of phytoplankton functional groups were assayed. Responses of the diatom, haptophyte, and dinoflagellate functional groups in simulated blooms were unique, with diatoms and haptophytes significantly (95% confidence) shifting their quantitative metabolic fingerprint from the in situ condition, whereas dinoflagellates showed little response. Significantly differentially abundant genes identified the importance of colimitation by nutrients, metals, and vitamins in eukaryotic phytoplankton metabolism and bloom formation in this system. The variable transcript allocation ratio, used to quantify transcript reallocation following DSW amendment, differed for diatoms and haptophytes, reflecting the long-standing paradigm of phytoplankton r- and K-type growth strategies. Although the underlying metabolic potential of the large eukaryotic phytoplankton was consistently present, the lack of a bloom during the study period suggests a crucial dependence on physical and biogeochemical forcing, which are susceptible to alteration with changing climate. PMID:26460011

Mortality of sea lions along the central California coast linked to a toxic diatom bloom.

PubMed

Scholin, C A; Gulland, F; Doucette, G J; Benson, S; Busman, M; Chavez, F P; Cordaro, J; DeLong, R; De Vogelaere, A; Harvey, J; Haulena, M; Lefebvre, K; Lipscomb, T; Loscutoff, S; Lowenstine, L J; Marin, R; Miller, P E; McLellan, W A; Moeller, P D; Powell, C L; Rowles, T; Silvagni, P; Silver, M; Spraker, T; Trainer, V; Van Dolah, F M

2000-01-06

Over 400 California sea lions (Zalophus californianus) died and many others displayed signs of neurological dysfunction along the central California coast during May and June 1998. A bloom of Pseudo-nitzschia australis (diatom) was observed in the Monterey Bay region during the same period. This bloom was associated with production of domoic acid (DA), a neurotoxin that was also detected in planktivorous fish, including the northern anchovy (Engraulis mordax), and in sea lion body fluids. These and other concurrent observations demonstrate the trophic transfer of DA resulting in marine mammal mortality. In contrast to fish, blue mussels (Mytilus edulus) collected during the DA outbreak contained no DA or only trace amounts. Such findings reveal that monitoring of mussel toxicity alone does not necessarily provide adequate warning of DA entering the food web at levels sufficient to harm marine wildlife and perhaps humans.

Modelling algae growth and dissolved oxygen in the Seine River downstream the Paris urban area: contribution of high frequency measurements

NASA Astrophysics Data System (ADS)

Vilmin, Lauriane; Escoffier, Nicolas; Groleau, Alexis; Poulin, Michel; Flipo, Nicolas

2014-05-01

Dissolved oxygen is a key variable in the hydro-ecological functioning of river systems. The accurate representation of the different biogeochemical processes affecting algal blooms and dissolved oxygen in the water column in hydro-ecological models is crucial for the use of these models as reliable management tools. This study focuses on the water quality of the Seine River along a 225 km stretch, from Paris to the Seine estuary. The study area is highly urbanized and located downstream France's largest agricultural area, and therefore receives large amounts of nutrients. During the last decades, nutrient inputs have been significantly reduced, especially with the implementation of new sewage water treatment technologies. Even though the frequency and the intensity of observed algal blooms have decreased, blooms were observed in 2011 and 2012. These blooms are generally followed by a period of high organic matter accumulation, leading to high mineralization fluxes and potential oxygen depletion. The hydrodynamics and the water quality of the Seine River are simulated for the 2011-2012 period with the distributed process-based hydro-ecological model ProSe (Even et al., 1998). The simulated chlorophyll a and dissolved oxygen concentrations are compared to high frequency measurements at the Bougival monitoring station (50 km downstream from Paris), which is part of the CarboSeine monitoring network. The high frequency continuous dataset allows calibrating of primary producers' physiological parameters. New growth parameters are defined for the diatom community. The blooms occur at the end of the winter period (march 2011 and march 2012) and the optimal temperature for diatom growth is calibrated at 10°C, based on an analysis of the physiological response of the diatom community. One of the main outcomes of the modelling exercise is that the precise identification of the constituting communities of algal blooms must be achieved prior to the modelling itself. With the new growth parameters and by considering additional communities, as dinoflagellates, in the model, chlorophyll a peak values (over 60 µg/L in 2011 and over 30 in 2012) are accurately simulated. Moreover, the production rate of the communities constituting an algal bloom can be estimated by interpreting the high frequency diel dissolved oxygen curves (Escoffier et al., 2013). The modelled production rate during the 2011 bloom is of the same order of magnitude as the one estimated with this method (0.5 to 2 g/m3/day of oxygen), which validates the representation of photosynthesis in the model. Therefore the simulated oxygen response is also improved. References: Even S., Poulin M., Garnier J., Billen G., Servais P., Chesterikoff A., Coste M., 1998. River ecosystem modelling: Application of the ProSe model to the Seine river (France). Hydrobiologia 373, 27-37. Escoffier N., Bensoussan N., Métivier F., Rocher V., Bernard C., Arnaud D., Vilmin L., Poulin M., Flipo N., Groleau A., 2013. Intergrating large river trophic functioning from real time sensors network measurements. American Society of Limnology and Oceanography Congress. New Orleans, February 2013.

From Rare to Dominant: a Fine-Tuned Soil Bacterial Bloom during Petroleum Hydrocarbon Bioremediation.

PubMed

Fuentes, Sebastián; Barra, Bárbara; Caporaso, J Gregory; Seeger, Michael

2016-02-01

Hydrocarbons are worldwide-distributed pollutants that disturb various ecosystems. The aim of this study was to characterize the short-lapse dynamics of soil microbial communities in response to hydrocarbon pollution and different bioremediation treatments. Replicate diesel-spiked soil microcosms were inoculated with either a defined bacterial consortium or a hydrocarbonoclastic bacterial enrichment and incubated for 12 weeks. The microbial community dynamics was followed weekly in microcosms using Illumina 16S rRNA gene sequencing. Both the bacterial consortium and enrichment enhanced hydrocarbon degradation in diesel-polluted soils. A pronounced and rapid bloom of a native gammaproteobacterium was observed in all diesel-polluted soils. A unique operational taxonomic unit (OTU) related to the Alkanindiges genus represented ∼ 0.1% of the sequences in the original community but surprisingly reached >60% after 6 weeks. Despite this Alkanindiges-related bloom, inoculated strains were maintained in the community and may explain the differences in hydrocarbon degradation. This study shows the detailed dynamics of a soil bacterial bloom in response to hydrocarbon pollution, resembling microbial blooms observed in marine environments. Rare community members presumably act as a reservoir of ecological functions in high-diversity environments, such as soils. This rare-to-dominant bacterial shift illustrates the potential role of a rare biosphere facing drastic environmental disturbances. Additionally, it supports the concept of "conditionally rare taxa," in which rareness is a temporary state conditioned by environmental constraints. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

From Rare to Dominant: a Fine-Tuned Soil Bacterial Bloom during Petroleum Hydrocarbon Bioremediation

PubMed Central

Fuentes, Sebastián; Barra, Bárbara; Caporaso, J. Gregory

2015-01-01

Hydrocarbons are worldwide-distributed pollutants that disturb various ecosystems. The aim of this study was to characterize the short-lapse dynamics of soil microbial communities in response to hydrocarbon pollution and different bioremediation treatments. Replicate diesel-spiked soil microcosms were inoculated with either a defined bacterial consortium or a hydrocarbonoclastic bacterial enrichment and incubated for 12 weeks. The microbial community dynamics was followed weekly in microcosms using Illumina 16S rRNA gene sequencing. Both the bacterial consortium and enrichment enhanced hydrocarbon degradation in diesel-polluted soils. A pronounced and rapid bloom of a native gammaproteobacterium was observed in all diesel-polluted soils. A unique operational taxonomic unit (OTU) related to the Alkanindiges genus represented ∼0.1% of the sequences in the original community but surprisingly reached >60% after 6 weeks. Despite this Alkanindiges-related bloom, inoculated strains were maintained in the community and may explain the differences in hydrocarbon degradation. This study shows the detailed dynamics of a soil bacterial bloom in response to hydrocarbon pollution, resembling microbial blooms observed in marine environments. Rare community members presumably act as a reservoir of ecological functions in high-diversity environments, such as soils. This rare-to-dominant bacterial shift illustrates the potential role of a rare biosphere facing drastic environmental disturbances. Additionally, it supports the concept of “conditionally rare taxa,” in which rareness is a temporary state conditioned by environmental constraints. PMID:26590285

Long-term evaluation of three satellite ocean color algorithms for identifying harmful algal blooms (Karenia brevis) along the west coast of Florida: A matchup assessment

PubMed Central

Carvalho, Gustavo A.; Minnett, Peter J.; Banzon, Viva F.; Baringer, Warner; Heil, Cynthia A.

2011-01-01

We present a simple algorithm to identify Karenia brevis blooms in the Gulf of Mexico along the west coast of Florida in satellite imagery. It is based on an empirical analysis of collocated matchups of satellite and in situ measurements. The results of this Empirical Approach is compared to those of a Bio-optical Technique – taken from the published literature – and the Operational Method currently implemented by the NOAA Harmful Algal Bloom Forecasting System for K. brevis blooms. These three algorithms are evaluated using a multi-year MODIS data set (from July, 2002 to October, 2006) and a long-term in situ database. Matchup pairs, consisting of remotely-sensed ocean color parameters and near-coincident field measurements of K. brevis concentration, are used to assess the accuracy of the algorithms. Fair evaluation of the algorithms was only possible in the central west Florida shelf (i.e. between 25.75°N and 28.25°N) during the boreal Summer and Fall months (i.e. July to December) due to the availability of valid cloud-free matchups. Even though the predictive values of the three algorithms are similar, the statistical measure of success in red tide identification (defined as cell counts in excess of 1.5 × 104 cells L−1) varied considerably (sensitivity—Empirical: 86%; Bio-optical: 77%; Operational: 26%), as did their effectiveness in identifying non-bloom cases (specificity—Empirical: 53%; Bio-optical: 65%; Operational: 84%). As the Operational Method had an elevated frequency of false-negative cases (i.e. presented low accuracy in detecting known red tides), and because of the considerable overlap between the optical characteristics of the red tide and non-bloom population, only the other two algorithms underwent a procedure for further inspecting possible detection improvements. Both optimized versions of the Empirical and Bio-optical algorithms performed similarly, being equally specific and sensitive (~70% for both) and showing low levels of uncertainties (i.e. few cases of false-negatives and false-positives: ~30%)—improved positive predictive values (~60%) were also observed along with good negative predictive values (~80%). PMID:22180667

Hydrodynamic control of microphytoplankton bloom in a coastal sea

NASA Astrophysics Data System (ADS)

Murty, K. Narasimha; Sarma, Nittala S.; Pandi, Sudarsana Rao; Chiranjeevulu, Gundala; Kiran, Rayaprolu; Muralikrishna, R.

2017-08-01

The influence of hydrodynamics on phytoplankton bloom occurrence/formation has not been adequately reported. Here, we document diurnal observations in the tropical Bay of Bengal's mid-western shelf region which reveal microphytoplankton cell density maxima in association with neap tide many times more than what could be accounted for by solar insolation and nutrient levels. When in summer, phytoplankton cells were abundant and the cell density of Guinardia delicatula reached critical value by tide caused zonation, aggregation happened to an intense bloom. Mucilaginous exudates from the alga due to heat and silicate stress likely promoted and stable water column and weak winds left undisturbed, the transient bloom. The phytoplankton aggregates have implication as food resource in the benthic region implying higher fishery potential, in carbon dioxide sequestration (carbon burial) and in efforts towards improving remote sensing algorithms for chlorophyll in the coastal region.

Dispersion/dilution enhances phytoplankton blooms in low-nutrient waters

NASA Astrophysics Data System (ADS)

Lehahn, Yoav; Koren, Ilan; Sharoni, Shlomit; D'Ovidio, Francesco; Vardi, Assaf; Boss, Emmanuel

2017-03-01

Spatial characteristics of phytoplankton blooms often reflect the horizontal transport properties of the oceanic turbulent flow in which they are embedded. Classically, bloom response to horizontal stirring is regarded in terms of generation of patchiness following large-scale bloom initiation. Here, using satellite observations from the North Pacific Subtropical Gyre and a simple ecosystem model, we show that the opposite scenario of turbulence dispersing and diluting fine-scale (~1-100 km) nutrient-enriched water patches has the critical effect of regulating the dynamics of nutrients-phytoplankton-zooplankton ecosystems and enhancing accumulation of photosynthetic biomass in low-nutrient oceanic environments. A key factor in determining ecological and biogeochemical consequences of turbulent stirring is the horizontal dilution rate, which depends on the effective eddy diffusivity and surface area of the enriched patches. Implementation of the notion of horizontal dilution rate explains quantitatively plankton response to turbulence and improves our ability to represent ecological and biogeochemical processes in oligotrophic oceans.

Metal uptake by phytoplankton during a bloom in South San Francisco Bay: Implications for metal cycling in estuaries

USGS Publications Warehouse

Luoma, S.N.; VanGeen, A.; Lee, B.-G.; Cloern, J.E.

1998-01-01

The 1994 spring phytoplankton bloom in South San Francisco Bay caused substantial reductions in concentrations of dissolved Cd, Ni, and Zn, but not Cu. We estimate that the equivalent of ~60% of the total annual input of Cd, Ni, and Zn from local waste-water treatment plants is cycled through the phytoplankton in South Bay. The results suggest that processes that affect phytoplankton bloom frequency or intensity in estuaries (e.g. nutrient enrichment) may also affect metal trapping. The bloom was characterized by hydrographic surveys conducted at weekly intervals for 9 weeks. Metal samples were collected from the water column on three occasions, timed to bracket the period when the bloom was predicted. Factors that might confound observations of biological influences, such as freshwater inputs, were relatively constant during the study. Before the bloom, concentrations of dissolved Cd were 0.81 ?? 0.02 nmol kg-1, Zn concentrations were 19.8 ?? 1.5 nmol kg-1, Ni were 42 ?? 1.4 nmol kg-1, and Cu were 37 ?? 1.4 nmol kg-1. The values are elevated relative to riverine and coastal end-members, reflecting inputs from wastewater and(or) sediments. At the height of the bloom, dissolved Zn, Cd, and Ni were reduced to 19, 50, and 75% of their prebloom concentrations, respectively. Dissolved Cu concentrations increased 20%. The mass of Cd taken up by phytoplankton was similar to the mass of Cd removed from solution if particle settling was considered, and Cd concentrations estimated in phytoplankton were higher than concentrations in suspended particulate material (SPM). Particulate concentrations of Zn and Ni during the bloom appeared to be dominated by the influence of changes in resuspension of Zn- and Ni-rich sediments.

The influence of changes in wind patterns on the areal extension of surface cyanobacterial blooms in a large shallow lake in China.

PubMed

Wu, Tingfeng; Qin, Boqiang; Brookes, Justin D; Shi, Kun; Zhu, Guangwei; Zhu, Mengyuan; Yan, Wenming; Wang, Zhen

2015-06-15

It has been hypothesized that climate change will induce the areal extension of cyanobacterial blooms. However, this hypothesis lacks field-based observation. In the present study both long-term historical data and short-term field measurement were used to identify the importance of changes in wind patterns on the cyanobacterial bloom in Lake Taihu (China), a large, shallow, eutrophic lake located in a subtropical zone. The cyanobacterial bloom mainly composed of Microcystis spp. recurred frequently throughout the year. The regression analysis of multi-year satellite image data extracted by the Floating Algae Index revealed that both the annual mean monthly maximum cyanobacterial bloom area (MMCBA) increased year by year from 2000 to 2011, while the contemporaneous cyanobacterial biomass showed no significant change. However, the correlation analysis shows that MMCBA was negatively correlated with wind speed. Our short-term field measurements indicated that the influence of wind on surface cyanobacterial blooms is that the Chlorophyll-a (Chla) concentration is fully mixing throughout the water column when the wind speed exceed 7 m s(-1). At lower wind speeds, there was vertical stratification of Chla with high surface concentrations and an increase in bloom area. The regression analysis of wind speed indicates that the climate has changed over the last decade. Lake Taihu has become increasingly calm, with the decrease of strong wind frequency between 2000 and 2011, corresponding to the increase in the MMCBA over time. Therefore, we conclude that changes in wind patterns related to climate change have favored the increase of cyanobacterial blooms in Lake Taihu. Copyright © 2015. Published by Elsevier B.V.

Decoupling physical from biological processes to assess the impact of viruses on a mesoscale algal bloom.

PubMed

Lehahn, Yoav; Koren, Ilan; Schatz, Daniella; Frada, Miguel; Sheyn, Uri; Boss, Emmanuel; Efrati, Shai; Rudich, Yinon; Trainic, Miri; Sharoni, Shlomit; Laber, Christian; DiTullio, Giacomo R; Coolen, Marco J L; Martins, Ana Maria; Van Mooy, Benjamin A S; Bidle, Kay D; Vardi, Assaf

2014-09-08

Phytoplankton blooms are ephemeral events of exceptionally high primary productivity that regulate the flux of carbon across marine food webs [1-3]. Quantification of bloom turnover [4] is limited by a fundamental difficulty to decouple between physical and biological processes as observed by ocean color satellite data. This limitation hinders the quantification of bloom demise and its regulation by biological processes [5, 6], which has important consequences on the efficiency of the biological pump of carbon to the deep ocean [7-9]. Here, we address this challenge and quantify algal blooms' turnover using a combination of satellite and in situ data, which allows identification of a relatively stable oceanic patch that is subject to little mixing with its surroundings. Using a newly developed multisatellite Lagrangian diagnostic, we decouple the contributions of physical and biological processes, allowing quantification of a complete life cycle of a mesoscale (∼10-100 km) bloom of coccolithophores in the North Atlantic, from exponential growth to its rapid demise. We estimate the amount of organic carbon produced during the bloom to be in the order of 24,000 tons, of which two-thirds were turned over within 1 week. Complimentary in situ measurements of the same patch area revealed high levels of specific viruses infecting coccolithophore cells, therefore pointing at the importance of viral infection as a possible mortality agent. Application of the newly developed satellite-based approaches opens the way for large-scale quantification of the impact of diverse environmental stresses on the fate of phytoplankton blooms and derived carbon in the ocean. Copyright © 2014 Elsevier Ltd. All rights reserved.

Drivers and effects of Karenia mikimotoi blooms in the western English Channel

NASA Astrophysics Data System (ADS)

Barnes, Morvan K.; Tilstone, Gavin H.; Smyth, Timothy J.; Widdicombe, Claire E.; Gloël, Johanna; Robinson, Carol; Kaiser, Jan; Suggett, David J.

2015-09-01

Naturally occurring red tides and harmful algal blooms (HABs) are of increasing importance in the coastal environment and can have dramatic effects on coastal benthic and epipelagic communities worldwide. Such blooms are often unpredictable, irregular or of short duration, and thus determining the underlying driving factors is problematic. The dinoflagellate Karenia mikimotoi is an HAB, commonly found in the western English Channel and thought to be responsible for occasional mass finfish and benthic mortalities. We analysed a 19-year coastal time series of phytoplankton biomass to examine the seasonality and interannual variability of K. mikimotoi in the western English Channel and determine both the primary environmental drivers of these blooms as well as the effects on phytoplankton productivity and oxygen conditions. We observed high variability in timing and magnitude of K. mikimotoi blooms, with abundances reaching >1000 cells mL-1 at 10 m depth, inducing up to a 12-fold increase in the phytoplankton carbon content of the water column. No long-term trends in the timing or magnitude of K. mikimotoi abundance were evident from the data. Key driving factors were identified as persistent summertime rainfall and the resultant input of low-salinity high-nutrient river water. The largest bloom in 2009 was associated with highest annual primary production and led to considerable oxygen depletion at depth, most likely as a result of enhanced biological breakdown of bloom material; however, this oxygen depletion may not affect zooplankton. Our data suggests that K. mikimotoi blooms are not only a key and consistent feature of western English Channel productivity, but importantly can potentially be predicted from knowledge of rainfall or river discharge.

River flow and ammonium discharge determine spring phytoplankton blooms in an urbanized estuary

NASA Astrophysics Data System (ADS)

Dugdale, Richard; Wilkerson, Frances; Parker, Alexander E.; Marchi, Al; Taberski, Karen

2012-12-01

Nutrient loadings to urbanized estuaries have increased over the past decades in response to population growth and upgrading to secondary sewage treatment. Evidence from the San Francisco Estuary (SFE) indicates that increased ammonium (NH4) loads have resulted in reduced primary production, a counter-intuitive finding; the NH4 paradox. Phytoplankton uptake of nitrate (NO3), the largest pool of dissolved inorganic nitrogen, is necessary for blooms to occur in SFE. The relatively small pool of ambient NH4, by itself insufficient to support a bloom, prevents access to NO3 and bloom development. This has contributed to the current rarity of spring phytoplankton blooms in the northern SFE (Suisun Bay), in spite of high inorganic nutrient concentrations, improved water transparency and seasonally low biomass of bivalve grazers. The lack of blooms has likely contributed to deleterious bottom-up impacts on estuarine fish. This bloom suppression may also occur in other estuaries that receive large amounts of anthropogenic NH4. In 2010 two rare diatom blooms were observed in spring in Suisun Bay (followed by increased abundances of copepods and pelagic fish), and like the prior bloom observed in 2000, chlorophyll accumulated after NH4 concentrations were decreased. In 2010, low NH4 concentrations were apparently due to a combination of reduced NH4 discharge from a wastewater treatment plant and increased river flow. To understand the interactions of river flow, NH4 discharge and bloom initiation, a conceptual model was constructed with three criteria; 1) NH4 loading must not exceed the capacity of the phytoplankton to assimilate the inflow of NH4, 2) the NH4 concentration must be ≤4 μmol L-1 to enable phytoplankton NO3 uptake, 3) the dilution rate of phytoplankton biomass set by river flow must not exceed the phytoplankton growth rate to avoid "washout". These criteria were determined for Suisun Bay; with sufficient irradiance and present day discharge of 15 tons NH4-N d-1at the upstream wastewater treatment plant (WTP). The loading criterion requires phytoplankton NH4 uptake to exceed 1.58 mmol m-2 d-1; the concentration criterion requires river flow >800 m3 s-1 at the WTP for sufficient NH4 dilution and the washout criterion requires river flow at Suisun Bay <1100 m3 s-1. The model and criteria are used to suggest how a reduction in anthropogenic NH4, either by reduced discharge or increased dilution (river flow), could be used as a management tool to restore pre-existing productivity in the SFE and similarly impacted estuaries.

Duelling 'CyanoHABs': unravelling the environmental drivers controlling dominance and succession among diazotrophic and non-N2 -fixing harmful cyanobacteria.

PubMed

Paerl, Hans W; Otten, Timothy G

2016-02-01

Eutrophication often manifests itself by increased frequencies and magnitudes of cyanobacterial harmful algal blooms (CyanoHABs) in freshwater systems. It is generally assumed that nitrogen-fixing cyanobacteria will dominate when nitrogen (N) is limiting and non-N2 fixers dominate when N is present in excess. However, this is rarely observed in temperate lakes, where N2 fixers often bloom when N is replete, and non-fixers (e.g. Microcystis) dominate when N concentrations are lowest. This review integrates observations from previous studies with insights into the environmental factors that select for CyanoHAB groups. This information may be used to predict how nutrient reduction strategies targeting N, phosphorus (P) or both N and P may alter cyanobacterial community composition. One underexplored concern is that as N inputs are reduced, CyanoHABs may switch from non-N2 fixing to diazotrophic taxa, with no net improvement in water quality. However, monitoring and experimental observations indicate that in eutrophic systems, minimizing both N and P loading will lead to the most significant reductions in total phytoplankton biomass without this shift occurring, because successional patterns appear to be strongly driven by physical factors, including temperature, irradiance and hydrology. Notably, water temperature is a primary driver of cyanobacterial community succession, with warming favouring non-diazotrophic taxa. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Control of toxic marine dinoflagellate blooms by serial parasitic killers.

PubMed

Chambouvet, Aurelie; Morin, Pascal; Marie, Dominique; Guillou, Laure

2008-11-21

The marine dinoflagellates commonly responsible for toxic red tides are parasitized by other dinoflagellate species. Using culture-independent environmental ribosomal RNA sequences and fluorescence markers, we identified host-specific infections among several species. Each parasitoid produces 60 to 400 offspring, leading to extraordinarily rapid control of the host's population. During 3 consecutive years of observation in a natural estuary, all dinoflagellates observed were chronically infected, and a given host species was infected by a single genetically distinct parasite year after year. Our observations in natural ecosystems suggest that although bloom-forming dinoflagellates may escape control by grazing organisms, they eventually succumb to parasite attack.

Bio-optical and physical variability in the subarctic North Atlantic Ocean during the spring of 1989

NASA Technical Reports Server (NTRS)

Dickey, T.; Marra, J.; Stramska, M.; Langdon, C.; Granata, T.; Plueddemann, A.; Weller, R.; Yoder, J.

1994-01-01

A unique set of physical, bio-optical, and meteorological observations were made from a mooring located in the open ocean south of Iceland (59 deg 29.5 min N, 20 deg 49.8 min W) from April 13 to June 12 1989. The present measurements are apparently the first to resolve the rapid transition to springtime physical and biological conditions at such a high latitude site. Our data were collected with bio-optical and physical moored systems every few minutes. The abrupt onset of springtime stratification was observed with the mixed layer shoaling from approximately 550 m to approximately 50 m in approximately 5 days. During this period a major phytoplankton bloom occurred with a tenfold increase in near-surface chlorophyll concentration in less than 3 weeks. Our statistical analysis indicates that the velocity shear in the upper layer is driven primarily by local wind stress. Mesoscale variability is also apparent from these and concurrent airborne oceangraphic lidar observations. Our complementary modeling results suggest that the near-surface layer may be reasonably well described by a one-dimensional model and that the spring bloom was initiated during incipient near-surface restratification.

Comparative studies on the ecophysiological differences of two green tide macroalgae under controlled laboratory conditions.

PubMed

Wang, Ying; Wang, You; Zhu, Lin; Zhou, Bin; Tang, Xuexi

2012-01-01

Yellow Sea green tides have occurred in coastal China almost every year from 2007 to 2011. Ulva prolifera (Müller) J. Agardh has been identified as the causative macroalgal species. U. intestinalis, however, has been observed in the bloom areas, co-occurring with U. prolifera, but it has not been found to be causative. The Yellow Sea green tide has shown consistent phases of development that match corresponding environmental changes. U. prolifera, not U. intestinalis, is dominant. Our experimental design was based on these observed phenomena, and the results of our field investigation indicated a close relationship between changes in principal environmental factors (irradiance, temperature, and salinity) and the development of each phase of the bloom. These main environmental factors were simulated to allow estimation and comparison of the physiological responses of U. prolifera and U. intestinalis. Ecophysiological differences were found between these two species. (1) More photosynthetic activity and plasticity were detected in U. prolifera. (2) U. prolifera was found to be more sensitive to dynamic environments, especially harsh and changing environmental conditions. U. intestinalis was found to be more stable, probably due to the higher stress tolerance given by its antioxidant system. (3) Markedly higher nutrient absorption activity was observed in U. prolifera. Comparisons of the ecophysiological traits of these two species in this present study may foster understanding of their natural ecological processes. Specifically, U. prolifera seemed to be more engaged with the ephemeral blooms, while U. intestinalis seemed to be directed toward persistence. This also suggests that the ecological success of U. prolifera may be inextricably linked to its higher capacity for photosynthesis, nutrient absorption, and nutrient assimilation.

Comparative Studies on the Ecophysiological Differences of Two Green Tide Macroalgae under Controlled Laboratory Conditions

PubMed Central

Wang, Ying; Wang, You; Zhu, Lin; Zhou, Bin; Tang, Xuexi

2012-01-01

Yellow Sea green tides have occurred in coastal China almost every year from 2007 to 2011. Ulva prolifera (Müller) J. Agardh has been identified as the causative macroalgal species. U. intestinalis, however, has been observed in the bloom areas, co-occurring with U. prolifera, but it has not been found to be causative. The Yellow Sea green tide has shown consistent phases of development that match corresponding environmental changes. U. prolifera, not U. intestinalis, is dominant. Our experimental design was based on these observed phenomena, and the results of our field investigation indicated a close relationship between changes in principal environmental factors (irradiance, temperature, and salinity) and the development of each phase of the bloom. These main environmental factors were simulated to allow estimation and comparison of the physiological responses of U. prolifera and U. intestinalis. Ecophysiological differences were found between these two species. (1) More photosynthetic activity and plasticity were detected in U. prolifera. (2) U. prolifera was found to be more sensitive to dynamic environments, especially harsh and changing environmental conditions. U. intestinalis was found to be more stable, probably due to the higher stress tolerance given by its antioxidant system. (3) Markedly higher nutrient absorption activity was observed in U. prolifera. Comparisons of the ecophysiological traits of these two species in this present study may foster understanding of their natural ecological processes. Specifically, U. prolifera seemed to be more engaged with the ephemeral blooms, while U. intestinalis seemed to be directed toward persistence. This also suggests that the ecological success of U. prolifera may be inextricably linked to its higher capacity for photosynthesis, nutrient absorption, and nutrient assimilation. PMID:22905087

Cyanobacteria and Algae Blooms: Review of Health and Environmental Data from the Harmful Algal Bloom-Related Illness Surveillance System (HABISS) 2007–2011

PubMed Central

Backer, Lorraine C.; Manassaram-Baptiste, Deana; LePrell, Rebecca; Bolton, Birgit

2015-01-01

Algae and cyanobacteria are present in all aquatic environments. We do not have a good sense of the extent of human and animal exposures to cyanobacteria or their toxins, nor do we understand the public health impacts from acute exposures associated with recreational activities or chronic exposures associated with drinking water. We describe the Harmful Algal Bloom-related Illness Surveillance System (HABISS) and summarize the collected reports describing bloom events and associated adverse human and animal health events. For the period of 2007–2011, Departments of Health and/or Environment from 11 states funded by the National Center for Environmental Health (NCEH), Centers for Disease Control and Prevention contributed reports for 4534 events. For 2007, states contributed 173 reports from historical data. The states participating in the HABISS program built response capacity through targeted public outreach and prevention activities, including supporting routine cyanobacteria monitoring for public recreation waters. During 2007–2010, states used monitoring data to support196 public health advisories or beach closures. The information recorded in HABISS and the application of these data to develop a wide range of public health prevention and response activities indicate that cyanobacteria and algae blooms are an environmental public health issue that needs continuing attention. PMID:25826054

A Submersible Holographic Camera for the Undisturbed Characterization of Optically Relevant Particles in Water (HOLOCAM)

DTIC Science & Technology

2013-09-30

environmental factors that impact toxic algal blooms in the Great Lakes, including their initiation, development, and senescence. The project is...integrated with existing harmful algal bloom monitoring and observational activities through the NOAA Great Lakes Environmental Research Laboratory...holograms showing the orientation of Ditylum chains within a phytoplankton thin layer in East Sound, WA, 2013. IMPACT /APPLICATIONS The HOLOCAM

Phenology and drivers of the winter-spring phytoplankton bloom in the open Black Sea: The application of Sverdrup's hypothesis and its refinements

NASA Astrophysics Data System (ADS)

Mikaelyan, Alexander S.; Chasovnikov, Valeriy K.; Kubryakov, Arseny A.; Stanichny, Sergey V.

2017-02-01

The phenology of the winter-spring phytoplankton bloom in the Black Sea was investigated on the basis of the satellite-derived chlorophyll concentration (Chl) for the recent 18-year period. Data for the 8-day Chl were analysed, together with changes in the nutrient concentration, sea surface temperature (SST), photosynthetically available radiation, wind velocity and duration. Based on Sverdrup's Critical Depth hypothesis and its recent refinements, the Pulsing-Bloom hypothesis was proposed for the highly stratified waters of the Black Sea. This hypothesis relates the biological response to physical forcing and chemical fluxes to the photic zone and predicts the pulsing growth of phytoplankton and different patterns of phytoplankton changes in the upper layer in winter-spring during cold and regular years. The hypothesis was supported by Chl dynamics and several Chl peaks were observed during winter-spring. Normally, the highest Chl occurred in winter and a spring peak was absent, whereas in cold years, a relatively low Chl in winter was followed by a spring bloom. These events were observed only in 15% of cases and the magnitude of the bloom was associated with the intensity of winter convection that was revealed by the negative inter-annual correlation between the March Chl and the February SST. In contrast, the February Chl was positively correlated with the SST. The proposed hypothesis provides an explanation of this phenomenon on the basis of an alternation between the low-turbulence and deep-mixing regimes. This mechanism was confirmed by the positive relationships between Chl and the duration of light wind during the current period and strong wind in the previous period. Inorganic nitrogen was depleted disproportionately during the winter-spring, whereas the phosphate concentration remained relatively high. Following a cold winter, the highest phosphate concentration and extremely low nitrogen-to-phosphorus molar ratios (2) were observed in the upper 25-m layer in late spring. The regular absence of spring blooms might represent one of the consequences of the regional climate change.

Chain response of microbial loop to the decay of a diatom bloom in the East China Sea

NASA Astrophysics Data System (ADS)

Wu, Linnan; Lin, Shiquan; Huang, Lingfeng; Lu, Jiachang; Chen, Wenzhao; Guo, Weidong; Zhang, Wuchang; Xiao, Tian; Sun, Jun

2016-02-01

Algal bloom has been regarded as one of the key causes for the summer hypoxia phenomena in the bottom water adjacent to the Yangtze River estuary in the East China Sea. Although a series of biological processes within microbial loop are involved in the development of oxygen depletion during the bloom decay, little has been known about the dynamics of microorganisms in response to the decaying process of the bloom through trophic interaction context. Here, we report some preliminary results of our observations about the response of microbial loop to the bloom decay, based on the onboard incubation experiments for 10 days during a diatom bloom near the Yangtze River estuary in August, 2011. Light and dark incubations were conducted to simulate the bloom decay inside and below the euphotic layer, respectively. In the first stage of bloom decay (Day 0 to Day 4), rapid response was found in heterotrophic bacteria (HB) and ciliate growth, which was in accordance with the decrease of total Chl a, indicating a "bottom-up" control at the early stage of bloom decay. However, the increase of heterotrophic nanoflagellates (HNF) abundance was rather inconspicuous, suggesting predation pressure on HNF from ciliate or other predator at this stage. In the second stage (Day 4 to Day 8), HB and ciliate decreased rapidly with the increase of HNF, revealing the release of HNF form ciliate predation, which suggested a "top-down" control. In the last stage of our experiment (Day 8 to Day 10), the trophic interactions were more complex, but it also implied a "top-down" control within the microbial loop. Meanwhile, virus had been monitored in the whole process of our incubations. It was found that virus lysed microalgae at the first stage, and lysed HB at the second stage. In addition, the bacterial mortality was principally caused by HNF grazing in the light-sufficient incubations and by viral lysis in the light-insufficient incubations. Our results suggest tight trophic interactions within the microbial loop in the decaying process of the algal bloom, which may assist our understanding of the role of microbial loop in hypoxia formation in coastal waters.

The Evaluation of the Cognitive Learning Process of the Renewed Bloom Taxonomy Using a Web Based Expert System

ERIC Educational Resources Information Center

Goksu, Idris

2016-01-01

The aim of this study is to develop the Web Based Expert System (WBES) which provides analyses and reports based on the cognitive processes of Renewed Bloom Taxonomy (RBT), and to put forward the impact of the supportive education provided in line with these reports, on the academic achievement and mastery learning state of the students. The study…

Refining the Niche of Harmful Dinoflagellates through Intensive Observation of Blooms within a Retentive, Inshore Embayment

NASA Astrophysics Data System (ADS)

Brosnahan, M.; Ralston, D. K.; Jiang, H.; Anderson, D. M.

2016-02-01

Harmful algal bloom dinoflagellates are among the most extensively studied species of marine phytoplankton both in situ and in laboratory settings through the growth and manipulation of cultures. Among many other applications, cultures are commonly used to explore changes in growth and behavioral responses across a broad range of physical and chemical parameters. Our own research group has published an extensive set of laboratory experiments to establish the growth and behavioral responses by the PSP species Alexandrium fundyense to changes in temperature and nutrient availability among other factors. In turn, results from these studies have been the basis of a biological sub-model within spatially explicit, coupled physical-biological models of A. fundyense bloom development in the Gulf of Maine and the Nauset Marsh estuary (Cape Cod, MA). More recently, through integrated observation and modeling of blooms within the Nauset Marsh estuary, our work has indicated that this culture-based approach grossly underestimates the physiological performance of A. fundyense cells in situ. Natural populations of A. fundyense divide faster, swim faster, and are inducted into the sexual phase of their life cycle at much higher rates than has been reported from studies of laboratory cultures. In spite of these flaws, assessments of the Gulf of Maine and Nauset models have demonstrated surprising skill at replicating large-scale patterns observed in field studies of this organism. One explanation may be that current models apply unrealistic grazing rates and other loss processes associated with species-species and cell-cell interactions. In situ observations by automated instruments provide a means to address these deficiencies by providing new ways to evaluate model performance, including comparisons of modeled and observed rates of division and broader consideration of species dynamics within the phytoplankton assemblage.

Can the algicidal material Ca-aminoclay be harmful when applied to a natural ecosystem? An assessment using microcosms.

PubMed

Jung, Seung Won; Yun, Suk Min; Yoo, Jae Won; Zhun, Li; Jang, Pung-Guk; Lim, Dhong-Il; Lee, Young-Chul; Lee, Hyun Uk; Lee, Taek-Kyun; Heo, Jinbee; Lee, Jin Hwan; Han, Myung-Soo

2015-11-15

We assessed the ability of an artificial clay (Ca-aminoclay) to suppress harmful algal bloom species (HABs) such as Cochlodinium polykrikoides and Chattonella marina and investigated the ecological responses in the closed and open microcosm systems. The Ca-aminoclay induced rapidly and selectively cell lysis in the HABs. However, applying Ca-aminoclay could cause adverse impacts in terms of biological and environmental changes. The bacterioplankton abundance increased and then, the abundances of heterotrophic nanoflagellates and ciliates increased rapidly. Extremely poor environmental conditions such as increase in nutrients and development of anoxic conditions were sustained continuously in a closed system, while the environmental conditions in open systems deteriorated before recovering to the initial conditions. We evaluated the potential for the occurrence of a bloom of another phytoplankton after HABs had been controlled using the Ca-aminoclay. The Ca-aminoclay controlled blooms of Chattonella marina in mixed cell cultures containing a Tetraselmis chui. However, T. chui increased over time and then bloomed. Therefore, caution should be taken when considering the direct application of Ca-aminoclay in natural environments even though it offers the rapid removal of HABs. Copyright © 2015 Elsevier B.V. All rights reserved.

Making sense of ocean sensing: the Gulf of Mexico Coastal Ocean Observing System links observations to applications

NASA Astrophysics Data System (ADS)

Simoniello, Christina; Jochens, Ann E.; Howard, Matthew K.; Swaykos, Joseph; Levin, Douglas R.; Stone, Debbi; Kirkpatrick, Barbara; Kobara, Shinichi

2011-06-01

The Gulf of Mexico Coastal Ocean Observing System Regional Association (GCOOS-RA) works to enhance our ability to collect, deliver and use ocean information. The GCOOS-RA Education and Outreach Council works to bring together industry, governments, academia, formal and informal educators, and the public to assess regional needs for coastal ocean information, foster cooperation, and increase utility of the data. Examples of data products in varying stages of development are described, including web pages for recreational boaters and fishermen, novel visualizations of storm surge, public exhibits focused on five Gulf of Mexico Priority Issues defined by the Gulf of Mexico Alliance, a Harmful Algae Bloom warning system, the Basic Observation Buoy project designed to engage citizen scientists in ocean monitoring activities, and the GCOOS Data Portal, instrumental in Deepwater Horizon mitigation efforts.

One Health and Cyanobacteria in Freshwater Systems: Animal Illnesses and Deaths are Sentinel Events for Human Health Risks

EPA Science Inventory

Harmful cyanobacterial blooms have adversely impacted human and animal health for thousands of years. Recently, the health impacts of harmful cyanobacteria blooms are becoming more frequently detected and reported. However, reports of human and animal illnesses or deaths associat...

Alexandrium fundyense cysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms

USGS Publications Warehouse

Anderson, Donald M.; Keafer, Bruce A.; Kleindinst, Judith L.; McGillicuddy, Dennis J.; Martin, Jennifer L.; Norton, Kerry; Pilskaln, Cynthia H.; Smith, Juliette L.; Sherwood, Christopher R.; Butman, Bradford

2014-01-01

Here we document Alexandrium fundyense cyst abundance and distribution patterns over nine years (1997 and 2004–2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with>300 cysts cm−3) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3–4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intense A. fundyense bloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0–1 and the 0–3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e., cysts→blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms→cysts). There are, however, significant positive correlations between 0–3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell abundance (e.g., cumulative shellfish toxicity, duration of detectable toxicity in shellfish, and bloom termination date). These data suggest that it may be possible to use cyst abundance to empirically forecast the geographic extent of the forthcoming bloom and, conversely, to use other metrics from bloom and toxicity events to forecast the size of the subsequent cyst population as the inoculum for the next year's bloom. This is an important step towards understanding the excystment/encystment cycle in A. fundyense bloom dynamics while also augmenting our predictive capability for this HAB-forming species in the GOM.

Winter-summer succession of unicellular eukaryotes in a meso-eutrophic coastal system.

PubMed

Christaki, Urania; Kormas, Konstantinos A; Genitsaris, Savvas; Georges, Clément; Sime-Ngando, Télesphore; Viscogliosi, Eric; Monchy, Sébastien

2014-01-01

The objective of this study was to explore the succession of planktonic unicellular eukaryotes by means of 18S rRNA gene tag pyrosequencing in the eastern English Channel (EEC) during the winter to summer transition. The 59 most representative (>0.1%, representing altogether 95% of total reads), unique operational taxonomic units (OTUs) from all samples belonged to 18 known high-level taxonomic groups and 1 unaffiliated clade. The five most abundant OTUs (69.2% of total reads) belonged to Dinophyceae, Cercozoa, Haptophyceae, marine alveolate group I, and Fungi. Cluster and network analysis between samples distinguished the winter, the pre-bloom, the Phaeocystis globosa bloom and the post-bloom early summer conditions. The OTUs-based network revealed that P. globosa showed a relatively low number of connections-most of them negative-with all other OTUs. Fungi were linked to all major taxonomic groups, except Dinophyceae. Cercozoa mostly co-occurred with the Fungi, the Bacillariophyceae and several of the miscellaneous OTUs. This study provided a more detailed exploration into the planktonic succession pattern of the EEC due to its increased depth of taxonomic sampling over previous efforts based on classical monitoring observations. Data analysis implied that the food web concept in a coastal system based on predator-prey (e.g. grazer-phytoplankton) relationships is just a part of the ecological picture; and those organisms exploiting a variety of strategies, such as saprotrophy and parasitism, are persistent and abundant members of the community.

Variability in bacterial community structure during upwelling in the coastal ocean

USGS Publications Warehouse

Kerkhof, L.J.; Voytek, M.A.; Sherrell, Robert M.; Millie, D.; Schofield, O.

1999-01-01

Over the last 30 years, investigations at the community level of marine bacteria and phytoplankton populations suggest they are tightly coupled. However, traditional oceanographic approaches cannot assess whether associations between specific bacteria and phytoplankton exist. Recently, molecular based approaches have been implemented to characterize specific members of different marine bacterial communities. Yet, few molecular-based studies have examined coastal upwelling situations. This is important since upwelling systems provide a unique opportunity for analyzing the association between specific bacteria and specific phytoplankton in the ocean. It is widely believed that upwelling can lead to changes in phytoplankton populations (blooms). Thus, if specific associations exist, we would expect to observe changes in the bacterial population triggered by the bloom. In this paper, we present preliminary data from coastal waters off New Jersey that confirm a shift in bacterial communities during a 1995 upwelling event recorded at a long-term earth observatory (LEO-15) in the Mid-Atlantic Bight. Using PCR amplification and cloning, specific bacterial 16S ribosomal RNA sequences were found which were present in upwelling samples during a phytoplankton bloom, but were not detected in non-bloom samples (surface seawater, offshore sites or sediment samples) collected at the same time or in the same area. These findings are consistent with the notion of specific associations between bacteria and phytoplankton in the ocean. However, further examination of episodic events, such as coastal upwelling, are needed to confirm the existence of specific associations. Additionally, experiments need to be performed to elucidate the mechanisms leading to the specific linkages between a group of bacteria and a group of phytoplankton.

Rising CO2 Levels Will Intensify Phytoplankton Blooms in Eutrophic and Hypertrophic Lakes

PubMed Central

Verspagen, Jolanda M. H.; Van de Waal, Dedmer B.; Finke, Jan F.; Visser, Petra M.; Van Donk, Ellen; Huisman, Jef

2014-01-01

Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC), pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1) dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2) rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3) above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked intensification of phytoplankton blooms in eutrophic and hypertrophic waters. PMID:25119996

Quantifying the adaptive cycle

USGS Publications Warehouse

Angeler, David G.; Allen, Craig R.; Garmestani, Ahjond S.; Gunderson, Lance H.; Hjerne, Olle; Winder, Monika

2015-01-01

The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

Quantifying the Adaptive Cycle.

PubMed

Angeler, David G; Allen, Craig R; Garmestani, Ahjond S; Gunderson, Lance H; Hjerne, Olle; Winder, Monika

2015-01-01

The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994-2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

Effects of spatial and temporal variability of turbidity on phytoplankton blooms

USGS Publications Warehouse

May, Christine L.; Koseff, Jeffrey R.; Lucas, Lisa; Cloern, James E.; Schoellhamer, David H.

2003-01-01

A central challenge of coastal ecology is sorting out the interacting spatial and temporal components of environmental variability that combine to drive changes in phytoplankton biomass. For 2 decades, we have combined sustained observation and experimentation in South San Francisco Bay (SSFB) with numerical modeling analyses to search for general principles that define phytoplankton population responses to physical dynamics characteristic of shallow, nutrient-rich coastal waters having complex bathymetry and influenced by tides, wind and river flow. This study is the latest contribution where we investigate light-limited phytoplankton growth using a numerical model, by modeling turbidity as a function of suspended sediment concentrations (SSC). The goal was to explore the sensitivity of estuarine phytoplankton dynamics to spatial and temporal variations in turbidity, and to synthesize outcomes of simulation experiments into a new conceptual framework for defining the combinations of physical-biological forcings that promote or preclude development of phytoplankton blooms in coastal ecosystems. The 3 main conclusions of this study are: (1) The timing of the wind with semidiurnal tides and the spring-neap cycle can significantly enhance spring-neap variability in turbidity and phytoplankton biomass; (2) Fetch is a significant factor potentially affecting phytoplankton dynamics by enhancing and/or creating spatial variability in turbidity; and (3) It is possible to parameterize the combined effect of the processes influencing turbidity‹and thus affecting potential phytoplankton bloom development‹with 2 indices for vertical and horizontal clearing of the water column. Our conceptual framework is built around these 2 indices, providing a means to determine under what conditions a phytoplankton bloom can occur, and whether a potential bloom is only locally supported or system-wide in scale. This conceptual framework provides a tool for exploring the inherent light climate attributes of shallow estuarine ecosystems and helps determine susceptibility to the harmful effects of nutrient enrichment.

Detection of a Planktothrix agardhii Bloom in Portuguese Marine Coastal Waters.

PubMed

Churro, Catarina; Azevedo, Joana; Vasconcelos, Vitor; Silva, Alexandra

2017-12-03

Cyanobacteria blooms are frequent in freshwaters and are responsible for water quality deterioration and human intoxication. Although, not a new phenomenon, concern exists on the increasing persistence, scale, and toxicity of these blooms. There is evidence, in recent years, of the transfer of these toxins from inland to marine waters through freshwater outflow. However, the true impact of these blooms in marine habitats has been overlooked. In the present work, we describe the detection of Planktothrix agardhii , which is a common microcystin producer, in the Portuguese marine coastal waters nearby a river outfall in an area used for shellfish harvesting and recreational activities. P. agardhii was first observed in November of 2016 in seawater samples that are in the scope of the national shellfish monitoring system. This occurrence was followed closely between November and December of 2016 by a weekly sampling of mussels and water from the sea pier and adjacent river mouth with salinity ranging from 35 to 3. High cell densities were found in the water from both sea pier and river outfall, reaching concentrations of 4,960,608 cells·L -1 and 6810.3 × 10⁶ cells·L -1 respectively. Cultures were also established with success from the environment and microplate salinity growth assays showed that the isolates grew at salinity 10. HPLC-PDA analysis of total microcystin content in mussel tissue, water biomass, and P. agardhii cultures did not retrieve a positive result. In addition, microcystin related genes were not detected in the water nor cultures. So, the P. agardhii present in the environment was probably a non-toxic strain. This is, to our knowledge, the first report on a P. agardhii bloom reaching the sea and points to the relevance to also monitoring freshwater harmful phytoplankton and related toxins in seafood harvesting and recreational coastal areas, particularly under the influence of river plumes.

Detection of a Planktothrix agardhii Bloom in Portuguese Marine Coastal Waters

PubMed Central

Azevedo, Joana; Vasconcelos, Vitor; Silva, Alexandra

2017-01-01

Cyanobacteria blooms are frequent in freshwaters and are responsible for water quality deterioration and human intoxication. Although, not a new phenomenon, concern exists on the increasing persistence, scale, and toxicity of these blooms. There is evidence, in recent years, of the transfer of these toxins from inland to marine waters through freshwater outflow. However, the true impact of these blooms in marine habitats has been overlooked. In the present work, we describe the detection of Planktothrix agardhii, which is a common microcystin producer, in the Portuguese marine coastal waters nearby a river outfall in an area used for shellfish harvesting and recreational activities. P. agardhii was first observed in November of 2016 in seawater samples that are in the scope of the national shellfish monitoring system. This occurrence was followed closely between November and December of 2016 by a weekly sampling of mussels and water from the sea pier and adjacent river mouth with salinity ranging from 35 to 3. High cell densities were found in the water from both sea pier and river outfall, reaching concentrations of 4,960,608 cells·L−1 and 6810.3 × 106 cells·L−1 respectively. Cultures were also established with success from the environment and microplate salinity growth assays showed that the isolates grew at salinity 10. HPLC-PDA analysis of total microcystin content in mussel tissue, water biomass, and P. agardhii cultures did not retrieve a positive result. In addition, microcystin related genes were not detected in the water nor cultures. So, the P. agardhii present in the environment was probably a non-toxic strain. This is, to our knowledge, the first report on a P. agardhii bloom reaching the sea and points to the relevance to also monitoring freshwater harmful phytoplankton and related toxins in seafood harvesting and recreational coastal areas, particularly under the influence of river plumes. PMID:29207501

Origin and fate of particulate and dissolved organic matter in a naturally iron-fertilized region of the Southern Ocean

NASA Astrophysics Data System (ADS)

Tremblay, L.; Caparros, J.; Leblanc, K.; Obernosterer, I.

2015-01-01

Natural iron fertilization of high-nutrient low-chlorophyll (HNLC) waters induces annually occurring spring phytoplankton blooms off the Kerguelen Islands (Southern Ocean). To examine the origin and fate of particulate and dissolved organic matter (POM and DOM), D- and L-amino acids (AA) were quantified at bloom and HNLC stations. Total hydrolyzable AA accounted for 21-25% of surface particulate organic carbon (%POCAA) at the bloom sites, but for 10% at the HNLC site. A marked decrease in %POCAA with depth was observed at the most productive stations leading to values between 3 and 5% below 300 m depth. AA contributed to only 0.9-4.4% of dissolved organic carbon (%DOCAA) at all stations. The only consistent vertical trend was observed at the most productive station (A3-2) where %DOCAA decreased from ~ 2% in the surface waters to 0.9% near 300 m. These AA yields revealed that POM and DOM were more rapidly altered or mineralized at the bloom sites compared to the HNLC site. Alteration state was also assessed by trends in C / N ratio, %D-AA and degradation index. Different molecular markers indicated that POM mostly originated from diatoms and bacteria. The estimated average proportion of POM from intact phytoplankton cells in surface waters was 45% at the bloom station A3-2, but 14% at the HNLC site. Estimates based on D-AA yields indicated that ~ 15% of POM and ~ 30% of DOM was of bacterial origin (cells and cell fragments) at all stations. Surprisingly, the DOM in HNLC waters appeared less altered than the DOM from the bloom, had slightly higher dissolved AA concentrations, and showed no sign of alteration within the water column. Unfavorable conditions for bacterial degradation in HNLC regions can explain these findings. In contrast, large inputs of labile organic molecules and iron likely stimulate the degradation of organic matter (priming effect) and the production of more recalcitrant DOM (microbial carbon pump) during iron-fertilized blooms.

Surface Water Quality Survey of Northern Indian River Lagoon from Sebastian Inlet to Mosquito Lagoon

NASA Astrophysics Data System (ADS)

Weaver, R. J.; Webb, B. M.

2012-12-01

Following news of an emerging brown tide algal bloom in the northern Indian River Lagoon (IRL), researchers sought to gain insight into the surface water quality in the IRL, as well as the extent of the algae coverage. A Portable SeaKeeper from YSI, mounted to a personal watercraft-based coastal profiling system, autonomously collected and analyzed the surface water. The system operates by recording sample data every 12 seconds while continuously underway at speeds up to and greater than 50 km/hr. The researchers covered a transect that started at Sebastian Inlet and followed a zig-zag path extending up through the Haulover Canal and into the Mosquito Lagoon. The survey path covered 166.7 km, and collected 2248 samples. Along the way stops were made at water quality stations used by the Saint John's River Water Management District, so that the data collected can be incorporated into ongoing monitoring efforts. The system analyzed the surface water for dissolved oxygen, pH, chlorophyll-a, salinity, temperature, turbidity, refined fuels, and CDOM. In the two days following the lagoon survey, the inlets at Port Canaveral and Sebastian were also surveyed for tidal currents and hydrography. The IRL transect survey data recorded evidence of the southern extent of the algae bloom in both chlorophyll-a and pH levels. Visual evidence of the bloom was striking as the water in the northern IRL turned a milk chocolaty brown color. Chlorophyll-a levels in the two inlets suggested bloom activity at these locations; however this bloom was different. This oceanic bloom was a result of a persistent upwelling event along the East Florida shelf, and the color was a paler green-yellow. The near-synoptic nature of the comprehensive lagoon survey, conducted in just over 7 hours, allows researchers to obtain a better understanding of water quality in coastal lagoons. Elevated levels of salinity, temperature, and refined fuels in the northern IRL indicate a low exchange rate and absence of flushing. Coordinated studies of circulation through the Haulover Canal, Ponce Inlet and Sebastian Inlet would aid in understanding the genesis of future bloom events.;

Applicability of Hydrogen Peroxide in Brown Tide Control – Culture and Microcosm Studies

PubMed Central

Randhawa, Varunpreet; Thakkar, Megha; Wei, Liping

2012-01-01

Brown tide algal blooms, caused by the excessive growth of Aureococcus anophagefferens, recur in several northeastern US coastal bays. Direct bloom control could alleviate the ecological and economic damage associated with bloom outbreak. This paper explored the effectiveness and safety of natural chemical biocide hydrogen peroxide (H2O2) for brown tide bloom control. Culture studies showed that H2O2 at 1.6 mg L−1 effectively eradicated high density A. anophagefferens within 24-hr, but caused no significant growth inhibition in the diatoms, prymnesiophytes, green algae and dinoflagellates of >2–3 μm cell sizes among 12 phytoplankton species tested over 1-week observation. When applied to brown tide bloom prone natural seawater in a microcosm study, this treatment effectively removed the developing brown tide bloom, while the rest of phytoplankton assemblage (quantified via HPLC based marker pigment analyses), particularly the diatoms and green algae, experienced only transient suppression then recovered with total chlorophyll a exceeding that in the controls within 72-hr; cyanobacteria was not eradicated but was still reduced about 50% at 72-hr, as compared to the controls. The action of H2O2 against phytoplankton as a function of cell size and cell wall structure, and a realistic scenario of H2O2 application were discussed. PMID:23082223

The frequency and extent of sub-ice phytoplankton blooms in the Arctic Ocean

PubMed Central

Horvat, Christopher; Jones, David Rees; Iams, Sarah; Schroeder, David; Flocco, Daniela; Feltham, Daniel

2017-01-01

In July 2011, the observation of a massive phytoplankton bloom underneath a sea ice–covered region of the Chukchi Sea shifted the scientific consensus that regions of the Arctic Ocean covered by sea ice were inhospitable to photosynthetic life. Although the impact of widespread phytoplankton blooms under sea ice on Arctic Ocean ecology and carbon fixation is potentially marked, the prevalence of these events in the modern Arctic and in the recent past is, to date, unknown. We investigate the timing, frequency, and evolution of these events over the past 30 years. Although sea ice strongly attenuates solar radiation, it has thinned significantly over the past 30 years. The thinner summertime Arctic sea ice is increasingly covered in melt ponds, which permit more light penetration than bare or snow-covered ice. Our model results indicate that the recent thinning of Arctic sea ice is the main cause of a marked increase in the prevalence of light conditions conducive to sub-ice blooms. We find that as little as 20 years ago, the conditions required for sub-ice blooms may have been uncommon, but their frequency has increased to the point that nearly 30% of the ice-covered Arctic Ocean in July permits sub-ice blooms. Recent climate change may have markedly altered the ecology of the Arctic Ocean. PMID:28435859

Water residence time affecting phytoplankton blooms: study case in Ibitinga Reservoir (São Paulo, Brazil) using Landsat/TM images.

PubMed

Londe, L R; Novo, E M L M; Barbosa, C; Araujo, C A S

2016-05-03

Satellite images are an effective tool for the detection of phytoplankton blooms, since they cause striking changes in water color. Bloom intensity can be expressed in terms of chlorophyll-a concentration. Previous studies suggest the use of Landsat TM4/TM3 reflectance ratio to retrieve surface chlorophyll-a concentration from aquatic systems. In this study we assumed that a remote sensing trophic state index can be applied to investigate how changes in HRT along the hydrologic year affect the spatial distribution of the phytoplankton blooms at Ibitinga's reservoir surface. For that, we formulated two objectives: (1) apply a semi-empirical model which uses this reflectance ratio to map chlorophyll-a concentration at Ibitinga reservoir along the 2005 hydrologic year and (2) assess how changes in hydraulic residence time (HRT) affect the spatial distribution of phytoplankton blooms at Ibitinga Reservoir. The study site was chosen because previous studies reported seasonal changes in the reservoir limnology which might be related to the reservoir seasonality and hydrodynamics. Six Landsat/TM images were acquired over Ibitinga reservoir during 2005 and water flow measurements provided by the Brazilian Electric System National Operator - ONS were used to compute the reservoir´s residence time, which varied from 5.37 to 52.39 days during 2005. The HRT in the date of image acquisition was then compared to the distribution of chlorophyll-a in the reservoir. The results showed that the HRT increasing implies the increasing of the reservoir surface occupied by phytoplankton blooms.

Satellite evidence of harmful algal blooms and related oceanographic features in the Bohai Sea during autumn 1998

NASA Astrophysics Data System (ADS)

Tang, Danling; Kawamura, Hiroshi; Oh, Im Sang; Baker, Joe

Harmful algal blooms (HABs) are truly global marine phenomena of increasing significance. Some HAB occurrences are different to observe because of their high spatial and temporal variability and their advection, once formed, by surface currents. A serious HAB occurred in the Bohai Sea during autumn 1998, causing the largest fisheries economic loss. The present study analyzes the formation, distribution, and advection of HAB using satellite SeaWiFS ocean color data and other oceanographic data. The results show that the bloom originated in the western coastal waters of the Bohai Sea in early September, and developed southeastward when sea surface temperature (SST) increased to 25 26 °C. The bloom with a high Chl-a concentration (6.5 mg m-3) in center portion covered an area of 60 × 65 km2. At the end of September, the bloom decayed when SST decreased to 22 23 °C. The HAB may have been initiated by a combination of the river discharge nutrients in the west coastal waters and the increase of SST; afterwards it may have been transported eastward by the local circulation that was enhanced by northwesterly winds in late September and early October.

[Discoloration of microalgal blooms as a bioindicating parameter in the Bahia de Mazatlán, México].

PubMed

Cortés-Altamirano, Roberto; Licea-Durán, Sergio

2004-09-01

In order to verify whether harmful algal blooms increased since 1979, a long-term project for the study of harmful algal blooms in Mazatlán Bay began 25 years ago (1979-2003). Observations were done daily and results indicate five trend types: (I) years without discoloration related to El Niño events; (II) years with days of sudden occurrence of discoloration, related to the release of accumulated energy after El Niño events; (III) years with similar number of discoloration events (days); (IV) years with a progressive decrease of the occurrence (days) of discoloration events; (V) years with gradual increase of discoloration events. The annual mean average of discoloration is of 25.3 days. Ninety-six discoloration events were recorded during year 2000, and represent the highest number of events in the last 25 years. Discoloration events are more common in March (174 days), harmful and toxic blooms included. This indicates continuity in the occurrence of the highest content of microalgae, and therefore, it is concluded that they play an important role for a better understanding of the environmental deterioration undergone by the coastal zone due to an increase of harmful and toxic microalgae blooms.

Dinoflagellate cysts and bloom events at Todos Santos Bay, Baja California, México, 1999 2000

NASA Astrophysics Data System (ADS)

Peña-Manjarrez, José Luis; Helenes, Javier; Gaxiola-Castro, Gilberto; Orellana-Cepeda, Elizabeth

2005-07-01

Forty-two species of dinoflagellate motile cells and 18 species of organic-walled dinoflagellate resting cysts were identified in samples collected at Todos Santos Bay, Baja California, México, from September 1999 to June 2000. These temperate to cool-temperate species belong mainly to the families Gonyaulacaceae and Protoperidiniaceae. Lingulodinium polyedrum (Stein, 1883) Dodge 1989 was the dominant species both in the sediments and water column. During this period we observed planktonic motile cells, temporary cysts with cellulose walls, and resting cysts with resistant dinosporin walls. Two dinoflagellate blooms occurred in the spring to summer of 2000 allowing us to observe the timing of cyst production. The temporary cysts appeared between these blooms and also in the summer, whereas the resting cysts appeared during the preceding fall and winter. Resting cysts appeared in colder conditions, whereas the temporary cysts were produced within a particular thermal window and under nutrient depletion. Resting cysts were concentrated in discrete areas at depths of less than 25 m, and associated with sediments ranging from silt to fine sand. These cysts were abundant in the surface sediments during summer, fall and winter, whereas the motile cells dominated during the spring and summer, when the two L. polyedrum blooms were observed. The abundance of cells in the plankton, comprising motile cells and temporary cysts, appears to be inversely proportional to the concentration of resting cysts of the same species in the surface sediments.

A method for examining temporal changes in cyanobacterial harmful algal bloom spatial extent using satellite remote sensing.

PubMed

Urquhart, Erin A; Schaeffer, Blake A; Stumpf, Richard P; Loftin, Keith A; Werdell, P Jeremy

2017-07-01

Cyanobacterial harmful algal blooms (CyanoHAB) are thought to be increasing globally over the past few decades, but relatively little quantitative information is available about the spatial extent of blooms. Satellite remote sensing provides a potential technology for identifying cyanoHABs in multiple water bodies and across geo-political boundaries. An assessment method was developed using MEdium Resolution Imaging Spectrometer (MERIS) imagery to quantify cyanoHAB surface area extent, transferable to different spatial areas, in Florida, Ohio, and California for the test period of 2008 to 2012. Temporal assessment was used to evaluate changes in satellite resolvable inland waterbodies for each state of interest. To further assess cyanoHAB risk within the states, the World Health Organization's (WHO) recreational guidance level thresholds were used to categorize surface area of cyanoHABs into three risk categories: low, moderate, and high-risk bloom area. Results showed that in Florida, the area of cyanoHABs increased largely due to observed increases in high-risk bloom area. California exhibited a slight decrease in cyanoHAB extent, primarily attributed to decreases in Northern California. In Ohio (excluding Lake Erie), little change in cyanoHAB surface area was observed. This study uses satellite remote sensing to quantify changes in inland cyanoHAB surface area across numerous water bodies within an entire state. The temporal assessment method developed here will be relevant into the future as it is transferable to the Ocean Land Colour Instrument (OLCI) on Sentinel-3A/3B missions. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

A method for examining temporal changes in cyanobacterial harmful algal bloom spatial extent using satellite remote sensing

USGS Publications Warehouse

Urquhart, Erin A.; Schaeffer, Blake A.; Stumpf, Richard P.; Loftin, Keith A.; Werdell, P. Jeremy

2017-01-01

Cyanobacterial harmful algal blooms (CyanoHAB) are thought to be increasing globally over the past few decades, but relatively little quantitative information is available about the spatial extent of blooms. Satellite remote sensing provides a potential technology for identifying cyanoHABs in multiple water bodies and across geo-political boundaries. An assessment method was developed using MEdium Resolution Imaging Spectrometer (MERIS) imagery to quantify cyanoHAB surface area extent, transferable to different spatial areas, in Florida, Ohio, and California for the test period of 2008 to 2012. Temporal assessment was used to evaluate changes in satellite resolvable inland waterbodies for each state of interest. To further assess cyanoHAB risk within the states, the World Health Organization’s (WHO) recreational guidance level thresholds were used to categorize surface area of cyanoHABs into three risk categories: low, moderate, and high-risk bloom area. Results showed that in Florida, the area of cyanoHABs increased largely due to observed increases in high-risk bloom area. California exhibited a slight decrease in cyanoHAB extent, primarily attributed to decreases in Northern California. In Ohio (excluding Lake Erie), little change in cyanoHAB surface area was observed. This study uses satellite remote sensing to quantify changes in inland cyanoHAB surface area across numerous water bodies within an entire state. The temporal assessment method developed here will be relevant into the future as it is transferable to the Ocean Land Colour Instrument (OLCI) on Sentinel-3A/3B missions.

Space station image captures a red tide ciliate bloom at high spectral and spatial resolution.

PubMed

Dierssen, Heidi; McManus, George B; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

2015-12-01

Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (10(6) cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity.

Space station image captures a red tide ciliate bloom at high spectral and spatial resolution

PubMed Central

Dierssen, Heidi; McManus, George B.; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

2015-01-01

Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (106 cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity. PMID:26627232

A method for examining temporal changes in cyanobacterial ...

EPA Pesticide Factsheets

Cyanobacterial harmful algal blooms (CyanoHAB) are thought to be increasing globally over the past few decades, but relatively little quantitative information is available about the spatial extent of blooms. Satellite remote sensing provides a potential technology for identifying cyanoHABs in multiple water bodies and across geo-political boundaries. An assessment method was developed using MEdium Resolution Imaging Spectrometer (MERIS) imagery to quantify cyanoHAB surface area extent, transferable to different spatial areas, in Florida, Ohio, and California for the test period of 2008 to 2012. Temporal assessment was used to evaluate changes in satellite resolvable inland waterbodies for each state of interest. To further assess cyanoHAB risk within the states, the World Health Organization’s (WHO) recreational guidance level thresholds were used to categorize surface area of cyanoHABs into three risk categories: low, moderate, and high-risk bloom area. Results showed that in Florida, the area of cyanoHABs increased largely due to observed increases in high-risk bloom area. California exhibited a slight decrease in cyanoHAB extent, primarily attributed to decreases in Northern California. In Ohio (excluding Lake Erie), little change in cyanoHAB surface area was observed. This study uses satellite remote sensing to quantify changes in inland cyanoHAB surface area across numerous water bodies within an entire state. The temporal assessment method developed here

Exploration of the antioxidant system and photosynthetic system of a marine algicidal Bacillus and its effect on four harmful algal bloom species.

PubMed

Hou, Shaoling; Shu, Wanjiao; Tan, Shuo; Zhao, Ling; Yin, Pinghe

2016-01-01

A novel marine bacterium, strain B1, initially showed 96.4% algicidal activity against Phaeocystis globosa. Under this situation, 3 other harmful algal species (Skeletonema costatum, Heterosigma akashiwo, and Prorocentrum donghaiense) were chosen to study the algicidal effects of strain B1, and the algicidal activities were 91.4%, 90.7%, and 90.6%, respectively. To explore the algicidal mechanism of strain B1 on these 4 harmful algal species, the characteristics of the antioxidant system and photosynthetic system were studied. Sensitivity to strain B1 supernatant, enzyme activity, and gene expression varied with algal species, while the algicidal patterns were similar. Strain B1 supernatant increased malondialdehyde contents; decreased chlorophyll a contents; changed total antioxidant and superoxide dismutase activity; and restrained psbA, psbD, and rbcL genes expression, which eventually resulted in the algal cells death. The algicidal procedure was observed using field emission scanning electron microscopy, which indicated that algal cells were lysed and cellular substances were released. These findings suggested that the antioxidant and photosynthetic system of these 4 algal species was destroyed under strain B1 supernatant stress. This is the first report to explore and compare the mechanism of a marine Bacillus against harmful algal bloom species of covered 4 phyla.

Lake Granbury and Lake Whitney Assessment Initiative Final Scientific/Technical Report Summary

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

Harris, B. L.; Roelke, Daniel; Brooks, Bryan

A team of Texas AgriLife Research, Baylor University and University of Texas at Arlington researchers studied the biology and ecology of Prymnesium parvum (golden algae) in Texas lakes using a three-fold approach that involved system-wide monitoring, experimentation at the microcosm and mesocosm scales, and mathematical modeling. The following are conclusions, to date, regarding this organism's ecology and potential strategies for mitigation of blooms by this organism. In-lake monitoring revealed that golden algae are present throughout the year, even in lakes where blooms do not occur. Compilation of our field monitoring data with data collected by Texas Parks and Wildlife andmore » Brazos River Authority (a period spanning a decade) revealed that inflow and salinity variables affect bloom formations. Thresholds for algae populations vary per lake, likely due to adaptations to local conditions, and also to variations in lake-basin morphometry, especially the presence of coves that may serve as hydraulic storage zones for P. parvum populations. More specifically, our in-lake monitoring showed that the highly toxic bloom that occurred in Lake Granbury in the winter of 2006/2007 was eliminated by increased river inflow events. The bloom was flushed from the system. The lower salinities that resulted contributed to golden algae not blooming in the following years. However, flushing is not an absolute requirement for bloom termination. Laboratory experiments have shown that growth of golden algae can occur at salinities ~1-2 psu but only when temperatures are also low. This helps to explain why blooms are possible during winter months in Texas lakes. Our in-lake experiments in Lake Whitney and Lake Waco, as well as our laboratory experiments, revealed that cyanobacteria, or some other bacteria capable of producing algicides, were able to prevent golden algae from blooming. Identification of this organism is a high priority as it may be a key to managing golden algae blooms. Our numerical modeling results support the idea that cyanobacteria, through allelopathy, control the timing of golden algae blooms in Lake Granbury. The in-lake experiments in Lake Whitney and Lake Waco also revealed that as golden algae blooms develop, there are natural enemies (a species of rotifer, and a virus) that help slow the population growth. Again, better characterization of these organisms is a high priority as it may be key to managing golden algae blooms. Our laboratory and in-lake experiments and field monitoring have shown that nutrient additions will remove toxicity and prevent golden algae from blooming. In fact, other algae displace the golden algae after nutrient additions. Additions of ammonia are particularly effective, even at low doses (much lower than what is employed in fish hatchery ponds). Application of ammonia in limited areas of lakes, such as in coves, should be explored as a management option. The laboratory experiments and field monitoring also show that the potency of toxins produced by P. parvum is greatly reduced when water pH is lower, closer to neutral levels. Application of mild acid to limited areas of lakes (but not to a level where acidic conditions are created), such as in coves, should be explored as a management option. Finally, our field monitoring and mathematical modeling revealed that flushing/dilution at high enough levels could prevent P. parvum from forming blooms and/or terminate existing blooms. This technique could work using deeper waters within a lake to flush the surface waters of limited areas of the same lakes, such as in coves and should be explored as a management option. In this way, water releases from upstream reservoirs would not be necessary and there would be no addition of nutrients in the lake.« less

Report on approaches to predicting probability of cyanobacteria blooms or related indices based on nutrient inputs and other ecosystem attributes in lakes

EPA Science Inventory

Despite a lengthy history of research on cyanobacteria, many important questions about this diverse group of aquatic, photosynthetic “blue-green algae” remain unanswered. For example, how can we more accurately predict cyanobacteria blooms in freshwater systems? Whi...

Remote sensing observations of phytoplankton increases triggered by successive typhoons

NASA Astrophysics Data System (ADS)

Huang, Lei; Zhao, Hui; Pan, Jiayi; Devlin, Adam

2017-12-01

Phytoplankton blooms in the Western North Pacific, triggered by two successive typhoons with different intensities and translation speeds under different pre-existing oceanic conditions, were observed and analyzed using remotely sensed chlorophyll-a (Chl-a), sea surface temperature (SST), and sea surface height anomaly (SSHA) data, as well as typhoon parameters and CTD (conductivity, temperature, and depth) profiles. Typhoon Sinlaku, with relatively weaker intensity and slower translation speed, induced a stronger phytoplankton bloom than Jangmi with stronger intensity and faster translation speed (Chl-a>0.18 mg·m‒3 versus Chl-a<0.15 mg·m‒3) east of Taiwan Island. Translation speed may be one of the important mechanisms that affect phytoplankton blooms in the study area. Pre-existing cyclonic circulations provided a relatively unstable thermodynamic structure for Sinlaku, and therefore cold water with rich nutrients could be brought up easily. The mixed-layer deepening caused by Typhoon Sinlaku, which occurred first, could have triggered an unfavorable condition for the phytoplankton bloom induced by Typhoon Jangmi which followed afterwards. The sea surface temperature cooling by Jangmi was suppressed due to the presence of the thick upper-ocean mixed-layer, which prevented the deeper cold water from being entrained into the upper-ocean mixed layer, leading to a weaker phytoplankton augment. The present study suggests that both wind (including typhoon translation speed and intensity) and pre-existing conditions (e.g., mixed-layer depths, eddies, and nutrients) play important roles in the strong phytoplankton bloom, and are responsible for the stronger phytoplankton bloom after Sinlaku's passage than that after Jangmi's passage. A new typhoon-influencing parameter is introduced that combines the effects of the typhoon forcing (including the typhoon intensity and translation speed) and the oceanic pre-condition. This parameter shows that the forcing effect of Sinlaku was stronger than that of Jangmi.

Sedimentary and atmospheric sources of iron around South Georgia, Southern Ocean: a modelling perspective

NASA Astrophysics Data System (ADS)

Borrione, I.; Aumont, O.; Nielsdóttir, M. C.; Schlitzer, R.

2013-07-01

In high-nutrient low-chlorophyll waters of the western Atlantic sector of the Southern Ocean, an intense phytoplankton bloom is observed annually north of South Georgia, most likely due to an enhanced supply of the limiting micronutrient iron. Shallow sediments and atmospheric dust deposition are believed to be the main iron sources. However, their relative importance is still unclear and in the South Georgia region have yet not been ascertained because iron measurements are very few. In this study, we use austral summer dissolved iron (dFe) data around South Georgia (January and February 2008) with a coupled regional hydrodynamic and biogeochemical model to investigate natural iron fertilization around the island. The biogeochemical component of the model includes an iron cycle, where sediments and dust deposition are the sources of iron to the ocean. The model captures the characteristic flow patterns around South Georgia, hence simulating a large phytoplankton bloom to the north, i.e., downstream, of the island. Modelled dFe concentrations agree well with observations (mean difference and root mean square errors of ~0.02 nM and ~0.81 nM) and form a large plume to the north of the island that extends eastwards for more than 800 km. In agreement with observations, highest dFe concentrations are located along the coast and decrease with distance from the island. Sensitivity tests indicate that most of the iron measured in the main bloom area originates from the coast and the very shallow shelf-sediments (depths < 20 m) while dust deposition plays a minor role, with almost no effects on surface chlorophyll a concentrations. Iron sources such as run-off not represented explicitly in the model, but that likely contribute to the iron plumes observed around South Georgia, are also discussed together with the potential effects their temporal variability may have on the system.

Mastering cognitive development theory in computer science education

NASA Astrophysics Data System (ADS)

Gluga, Richard; Kay, Judy; Lister, Raymond; Simon; Kleitman, Sabina

2013-03-01

To design an effective computer science curriculum, educators require a systematic method of classifying the difficulty level of learning activities and assessment tasks. This is important for curriculum design and implementation and for communication between educators. Different educators must be able to use the method consistently, so that classified activities and assessments are comparable across the subjects of a degree, and, ideally, comparable across institutions. One widespread approach to supporting this is to write learning objects in terms of Bloom's Taxonomy. This, or other such classifications, is likely to be more effective if educators can use them consistently, in the way experts would use them. To this end, we present the design and evaluation of our online interactive web-based tutorial system, which can be configured and used to offer training in different classification schemes. We report on results from three evaluations. First, 17 computer science educators complete a tutorial on using Bloom's Taxonomy to classify programming examination questions. Second, 20 computer science educators complete a Neo-Piagetian tutorial. Third evaluation was a comparison of inter-rater reliability scores of computer science educators classifying programming questions using Bloom's Taxonomy, before and after taking our tutorial. Based on the results from these evaluations, we discuss the effectiveness of our tutorial system design for teaching computer science educators how to systematically and consistently classify programming examination questions. We also discuss the suitability of Bloom's Taxonomy and Neo-Piagetian theory for achieving this goal. The Bloom's and Neo-Piagetian tutorials are made available as a community resource. The contributions of this paper are the following: the tutorial system for learning classification schemes for the purpose of coding the difficulty of computing learning materials; its evaluation; new insights into the consistency that computing educators can achieve using Bloom; and first insights into the use of Neo-Piagetian theory by a group of classifiers.

Causality of an extreme harmful algal bloom in Monterey Bay, California, during the 2014-2016 northeast Pacific warm anomaly

NASA Astrophysics Data System (ADS)

Ryan, J. P.; Kudela, R. M.; Birch, J. M.; Blum, M.; Bowers, H. A.; Chavez, F. P.; Doucette, G. J.; Hayashi, K.; Marin, R.; Mikulski, C. M.; Pennington, J. T.; Scholin, C. A.; Smith, G. J.; Woods, A.; Zhang, Y.

2017-06-01

An ecologically and economically disruptive harmful algal bloom (HAB) affected much of the northeast Pacific margin in 2015, during a prolonged oceanic warm anomaly. Caused by diatoms of the genus Pseudo-nitzschia, this HAB produced the highest particulate concentrations of the biotoxin domoic acid (DA) ever recorded in Monterey Bay, California. Bloom inception followed strong upwelling during the spring transition, which introduced nutrients and eliminated the warm anomaly locally. Subsequently, moderate and intermittent upwelling created favorable conditions for growth and accumulation of HAB biomass, which was dominated by a highly toxigenic species, P. australis. High cellular DA concentrations were associated with available nitrogen for DA synthesis coincident with silicate exhaustion. This nutrient influence resulted from two factors: (1) disproportionate depletion of silicate in upwelling source waters during the warm anomaly, the most severe depletion observed in 24 years, and (2) silicate uptake by the dense diatom bloom.

Subtle biological responses to increased CO2 concentrations by Phaeocystis globosa Scherffel, a harmful algal bloom species

NASA Astrophysics Data System (ADS)

Wang, Yan; Smith, Walker O.; Wang, Xiaodong; Li, Shaoshan

2010-05-01

Recent investigations into the role of carbon dioxide on phytoplankton growth and composition have clearly shown differential effects among species and assemblages, suggesting that increases in oceanic CO2 may play a critical role in structuring lower trophic levels of marine systems in the future. Furthermore, alarming increases in the occurrence of harmful algal blooms (HABs) in coastal waters have been observed, and while not uniform among systems, appear in some manner to be linked to human impacts (eutrophication) on coastal systems. Models of HABs are in their infancy and do not at present include sophisticated biological effects or their environmental controls. Here we show that subtle biological responses occur in the HAB species Phaeocystis globosa Scherffel as a result of CO2 enrichment induced by gentle bubbling. The alga, which has a polymorphic life history involving the formation of both colonies and solitary cells, exhibited altered growth rates of colonial and solitary forms at [CO2] of 750 ppm, as well as increased colony formation. In addition, substantial modifications of elemental and photosynthetic constituents of the cells (C cell-1, N cell-1, potential quantum yield, chl a cell-1) occurred under elevated CO2 concentrations compared to those found at present CO2 levels. In contrast, other individual and population variables (e.g., colony diameter, total chlorophyll concentration, carbon/nitrogen ratio) were unaffected by increased CO2. Our results suggest that predictions of the future impacts of Phaeocystis blooms on coastal ecosystems and local biogeochemistry need to carefully examine the subtle biological responses of this alga in addition to community and ecosystem effects.

Modeling seasonality of ice and ocean carbon production in the Arctic

NASA Astrophysics Data System (ADS)

Jin, M.; Deal, C. M.; Ji, R.

2011-12-01

In the Arctic Ocean, both phytoplankton and sea ice algae are important contributors to the primary production and the arctic food web. Copepod in the arctic regions have developed their feeding habit depending on the timing between the ice algal bloom and the subsequent phytoplankton bloom. A mismatch of the timing due to climate changes could have dramatic consequences on the food web as shown by some regional observations. In this study, a global coupled ice-ocean-ecosystem model was used to assess the seasonality of the ice algal and phytoplankton blooms in the arctic. The ice-ocean ecosystem modules are fully coupled in the physical model POP-CICE (Parallel Ocean Program- Los Alamos Sea Ice Model). The model results are compared with various observations. The modeled ice and ocean carbon production were analyzed by regions and their linkage to the physical environment changes (such as changes of ice concentration and water temperature, and light intensity etc.) between low- and high-ice years.

Evaluation of water quality during successive severe drought years within Microcystis blooms using fish embryo toxicity tests for the San Francisco Estuary, California.

PubMed

Kurobe, Tomofumi; Lehman, Peggy W; Haque, M E; Sedda, Tiziana; Lesmeister, Sarah; Teh, Swee

2018-01-01

In the San Francisco Estuary, California, the largest estuary on the Pacific Coast of North America, the frequency and intensity of drought and associated cyanobacteria blooms are predicted to increase with climate change. To assess the impact of water quality conditions on estuarine fish health during successive severe drought years with Microcystis blooms, we performed fish embryo toxicity testing with Delta Smelt and Medaka. Fish embryos were exposed to filtered ambient water collected from the San Francisco Estuary during the Microcystis bloom season in 2014 and 2015, the third and fourth most severe recorded drought years in California. Medaka embryos incubated in filtered ambient waters exhibited high mortality rates (>77%), which was mainly due to bacterial growth. Medaka mortality data was negatively correlated with chloride, and positively correlated with water temperature, total and dissolved organic carbon, and ambient and net chlorophyll a concentration. Delta Smelt embryo mortality rates were lower (<42%) and no prominent seasonal or geographic trend was observed. There was no significant correlation between the Delta Smelt mortality data and water quality parameters. Aeromonas was the dominant bacteria that adversely affected Medaka. The growth of Aeromonas was suppressed when salinity was greater than or equal to 1psu and resulted in a significant reduction in mortality rate. Bacterial growth test demonstrated that the lysate of Microcystis cells enhanced the growth of Aeromonas. Toxin production by Microcystis is a major environmental concern, however, we conclude that dissolved substances released from Microcystis blooms could result in water quality deterioration by promoting growth of bacteria. Furthermore, a distinctive developmental deformity was observed in Medaka during the toxicity tests; somite formation was inhibited at the same time that cardiogenesis occurred and the functional heart was observed to be beating. The exact cause of the embryonic developmental deformity is still unknown. Copyright © 2017 Elsevier B.V. All rights reserved.

Integrity Verification for SCADA Devices Using Bloom Filters and Deep Packet Inspection

DTIC Science & Technology

2014-03-27

prevent intrusions in smart grids [PK12]. Parthasarathy proposed an anomaly detection based IDS that takes into account system state. In his implementation...Security, 25(7):498–506, 10 2006. [LMV12] O. Linda, M. Manic, and T. Vollmer. Improving cyber-security of smart grid systems via anomaly detection and...6 2012. 114 [PK12] S. Parthasarathy and D. Kundur. Bloom filter based intrusion detection for smart grid SCADA. In Electrical & Computer Engineering

Effects of increasing nitrogen and phosphorus concentrations on phytoplankton community growth and toxicity during Planktothrix blooms in Sandusky Bay, Lake Erie.

PubMed

Davis, Timothy W; Bullerjahn, George S; Tuttle, Taylor; McKay, Robert Michael; Watson, Susan B

2015-06-16

Sandusky Bay experiences annual toxic cyanobacterial blooms dominated by Planktothrix agardhii/suspensa. To further understand the environmental drivers of these events, we evaluated changes in the growth response and toxicity of the Planktothrix-dominated blooms to nutrient amendments with orthophosphate (PO4) and inorganic and organic forms of dissolved nitrogen (N; ammonium (NH4), nitrate (NO3) and urea) over the bloom season (June - October). We complemented these with a metagenomic analysis of the planktonic microbial community. Our results showed that bloom growth and microcystin (MC) concentrations responded more frequently to additions of dissolved N than PO4, and that the dual addition of NH4 + PO4 and Urea + PO4 yielded the highest MC concentrations in 54% of experiments. Metagenomic analysis confirmed that P. agardhii/suspensa was the primary MC producer. The phylogenetic distribution of nifH revealed that both heterocystous cyanobacteria and heterotrophic proteobacteria had the genetic potential for N2 fixation in Sandusky Bay. These results suggest that as best management practices are developed for P reductions in Sandusky Bay, managers must be aware of the negative implications of not managing N loading into this system as N may significantly impact cyanobacterial bloom size and toxicity.

Hyperspectral remote sensing study of harmful algal blooms in the Chesapeake Bay

NASA Astrophysics Data System (ADS)

Nie, Yixiang

Recent development of hyperspectral remote sensing provides capability to identify and classify harmful algal blooms beyond the estimation of chlorophyll concentrations. This study uses hyperspectral data to extract spectral signatures, classify algal blooms, and map the spatial distribution of the algal blooms in the upper Chesapeake Bay. Furthermore, water quality parameters from ground stations have been used together with remote sensing data to provide better understanding of the formation and transformation of the life cycle of harmful algal blooms, and the cause of their outbreaks in the upper Chesapeake Bay. The present results show a strong and significant positive correlation between chlorophyll concentrations and total organic nitrogen concentrations. This relation suggests that total organic nitrogen played an important role in triggering the harmful algal blooms in the upper Chesapeake Bay in this study. This study establishes an integrated approach which combines hyperspectral imaging with multispectral ocean color remote sensing data and traditional water quality monitoring system in the study of harmful algal blooms in small water bodies such as the Chesapeake Bay. Presently, remote sensing is well integrated into the research community, but is less commonly used by resource managers. This dissertation couples remote sensing technologies with specific monitoring programs. The present results will help natural resource managers, local authorities, and the public to utilize an integrated approach in order to better understand, evaluate, preserve, and restore the health of the Chesapeake Bay waters and habitats.

In situ Occurrence, Prevalence and Dynamics of Parvilucifera Parasitoids during Recurrent Blooms of the Toxic Dinoflagellate Alexandrium minutum

PubMed Central

Alacid, Elisabet; Reñé, Albert; Camp, Jordi; Garcés, Esther

2017-01-01

Dinoflagellate blooms are natural phenomena that often occur in coastal areas, which in addition to their large number of nutrient-rich sites are characterized by highly restricted hydrodynamics within bays, marinas, enclosed beaches, and harbors. In these areas, massive proliferations of dinoflagellates have harmful effects on humans and the ecosystem. However, the high cell density reached during blooms make them vulnerable to parasitic infections. Under laboratory conditions parasitoids are able to exterminate an entire host population. In nature, Parvilucifera parasitoids infect the toxic dinoflagellate Alexandrium minutum during bloom conditions but their prevalence and impact remain unexplored. In this study, we evaluated the in situ occurrence, prevalence, and dynamics of Parvilucifera parasitoids during recurrent blooms of A. minutum in a confined site in the NW Mediterranean Sea as well as the contribution of parasitism to bloom termination. Parvilucifera parasitoids were recurrently detected from 2009 to 2013, during seasonal outbreaks of A. minutum. Parasitic infections in surface waters occurred after the abundance of A. minutum reached 104–105 cells L−1, suggesting a density threshold beyond which Parvilucifera transmission is enhanced and the number of infected cells increases. Moreover, host and parasitoid abundances were not in phase. Instead, there was a lag between maximum A. minutum and Parvilucifera densities, indicative of a delayed density-dependent response of the parasitoid to host abundances, similar to the temporal dynamics of predator-prey interactions. The highest parasitoid prevalence was reached after a peak in host abundance and coincided with the decay phase of the bloom, when a maximum of 38% of the A. minutum population was infected. According to our estimates, Parvilucifera infections accounted for 5–18% of the total observed A. minutum mortality, which suggested that the contribution of parasitism to bloom termination is similar to that of other biological factors, such as encystment and grazing. PMID:28912757

Simulation of annual plankton productivity cycle in the Black Sea by a one-dimensional physical-biological model

NASA Astrophysics Data System (ADS)

Oguz, Temel; Ducklow, Hugh; Malanotte-Rizzoli, Paola; Tugrul, Suleyman; Nezlin, Nikolai P.; Unluata, Umit

1996-07-01

The annual cycle of the plankton dynamics in the central Black Sea is studied by a one-dimensional vertically resolved physical-biological upper ocean model, coupled with the Mellor-Yamada level 2.5 turbulence closure scheme. The biological model involves interactions between the inorganic nitrogen (nitrate, ammonium), phytoplankton and herbivorous zooplankton biomasses, and detritus. Given a knowledge of physical forcing, the model simulates main observed seasonal and vertical characteristic features, in particular, formation of the cold intermediate water mass and yearly evolution of the upper layer stratification, the annual cycle of production with the fall and the spring blooms, and the subsurface phytoplankton maximum layer in summer, as well as realistic patterns of particulate organic carbon and nitrogen. The computed seasonal cycles of the chlorophyll and primary production distributions over the euphotic layer compare reasonably well with the data. Initiation of the spring bloom is shown to be critically dependent on the water column stability. It commences as soon as the convective mixing process weakens and before the seasonal stratification of surface waters begins to develop. It is followed by a weaker phytoplankton production at the time of establishment of the seasonal thermocline in April. While summer nutrient concentrations in the mixed layer are low enough to limit production, the layer between the thermocline and the base of the euphotic zone provides sufficient light and nutrient to support subsurface phytoplankton development. The autumn bloom takes place sometime between October and December depending on environmental conditions. In the case of weaker grazing pressure to control the growth rate, the autumn bloom shifts to December-January and emerges as the winter bloom, or, in some cases, is connected with the spring bloom to form one unified continuous bloom structure during the January-March period. These bloom structures are similar to the year-to-year variabilities present in the data.

ERTS-1 observes algal blooms in Lake Erie and Utah Lake

NASA Technical Reports Server (NTRS)

Strong, A. E.

1973-01-01

During late summer when the surface waters of Lake Erie reach their maximum temperature an algal bloom is likely to develop. Such phenomena have been noticed on other shallow lakes using ERTS-1 and characterize eutrophic conditions. The concentration of the algae into long streamers provides additional information on surface circulations. To augment the ERTS-1 MSS data of Lake Erie an aircraft was flown to provide correlative thermal-IR and additional multiband photographs. The algal bloom is highly absorptive in the visible wavelengths but reverses contrast with the surrounding water in the near-IR bands. The absorption of shortwave energy heats the dark brown algal mass, providing a hot surface target for the thermal-IR scanner.

Interannual variability in phytoplankton blooms observed in the northwestern Arabian Sea during the southwest monsoon

NASA Technical Reports Server (NTRS)

Brock, John C.; Mcclain, Charles R.

1992-01-01

Interannual changes in the strength and seasonal evolution of the 1979 through 1982 surface-level southwest monsoon winds are related to variations in the summer phytoplankton bloom of the northwestern Arabian Sea by synthesis of satellite ocean-color remote sensing with analysis of in-situ hydrographic and meteorological data sets. The 1979-1981 southwest monsoon phytoplankton blooms in the northwest Arabian Sea peaked during August-September, extended from the Omani coast to about 6 E, and appeared to lag the development of open-sea upwelling by at least 1 month. In all 3 years the bloom was driven by spatially distinct upward nutrient fluxes to the euphotic zone forced by the physical processes of coastal upwelling and offshore Ekman pumping. Coastal upwelling was evident from May through September, yielded the most extreme concentrations of phytoplankton biomass, and along the Omani coast was limited in its impact on upper ocean biological variability to the continental shelf. Ekman pumping stimulated the development of a broad open-ocean component of the southwest monsoon phytoplankton bloom oceanward of the Omani shelf. Phytoplankton biomass on the Omani continental shelf was increased during both the early and late phases of the 1980 southwest monsoon due to stronger coastal upwelling under the most intense southwesterly winds of the four summers investigated. Diminished coastal upwelling during the early phase of the weak 1982 southwest monsoon resulted in a coastal bloom that reached a mean phytoplankton-pigment concentration that was 28 percent of that seen in 1980. The lack of a strong regional northwestern Arabian Sea bloom in late summer 1982 is attributed to the development of persistent, shallow temperature stratification that rendered Ekman pumping less effective in driving upward nutrient fluxes.

Mycosporine-like amino acids and xanthophyll-cycle pigments favour a massive spring bloom development of the dinoflagellate Prorocentrum minimum in Grande Bay (Argentina), an ozone hole affected area

NASA Astrophysics Data System (ADS)

Carreto, José I.; Carignan, Mario O.; Montoya, Nora G.; Cozzolino, Ezequiel; Akselman, Rut

2018-02-01

In Grande Bay (Southern Patagonian Shelf) in a eutrophic and recirculating area slightly stratified during spring, we observed an intense (up to 1 × 107 cells L- 1) and shallow, quasi mono-specific bloom of the dinoflagellate Prorocentrum minimum. Peridinin was the most abundant carotenoid, but the relative amounts of the xanthophyll cycle carotenoids (diadinoxanthin + diatoxanthin = DT) to light-harvesting pigments were high (DT/Chl a ratio = 0.32 and DT/peridinin ratio = 0.40). Shinorine, usujirene, palythene, mycosporine-serine-glycine methyl ester and palythenic acid were the primary mycosporine-like amino acids (MAAs), followed by mycosporine-glycine, palythine, and porphyra-334. The ΣMAAs/Chl a ratios (up to 27.9 nmol/nmol) were in the upper range reported either in nutrient-replete dinoflagellate cultures or natural populations. We monitored, from space (using satellite ocean colour data), the spatial and temporal bloom variability (from September 22 to October 31, 2005) using an approach to discriminate dinoflagellate from diatom blooms. The results indicated that an intense diatom bloom started in early spring but was rapidly replaced by an intense bloom of the dinoflagellate P. minimum, although the nutrient concentrations were apparently not limiting. The most notorious change in this period was a sharp increase in the levels of solar UVB radiation (UVB index 9.0) as a consequence of the overpass of the polar vortex over this area. We postulated that the synthesis and accumulation of MAAs and xanthophyll pigments, were competitive advantages for the opportunistic red tide dinoflagellate P. minimum over the sensitive diatoms, favouring the development of their surface blooms in this seasonally solar UVB radiation (UVBR) affected area.

MODIS-Aqua detects Noctiluca scintillans and hotspots in the central Arabian Sea.

PubMed

Dwivedi, R; Priyaja, P; Rafeeq, M; Sudhakar, M

2016-01-01

Northern Arabian Sea is considered as an ecologically sensitive area as it experiences a massive upwelling and long-lasting algal bloom, Noctiluca scintillans (green tide) during summer and spring-winter, respectively. Diatom bloom is also found to be co-located with N. scintillans and both have an impact on ecology of the basin. In-house technique of detecting species of these blooms from Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua data was used to generate a time-series of images revealing their spatial distribution. A study of spatial-temporal variability of these blooms using satellite data expressed a cyclic pattern of their spread over a period of 13 years. An average distribution of the blooms for January-March period revealed a peak in 2015 and minimum in 2013. Subsequently, a time-series of phytoplankton species images were generated for these 2 years to study their inter-annual variability and the associated factors. Species images during active phase of the bloom (February) in 2015 indicated development of N. scintillans and diatom in the central Arabian Sea also, up to 12° N. This observation was substantiated with relevant oceanic parameters measured from the ship as well as satellite data and the same is highlight of the paper. While oxygen depletion and release of ammonia associated with N. scintillans are detrimental for waters on the western side; it is relatively less extreme and supports the entire food chain on the eastern side. In view of these contrasting eco-sensitive events, it is a matter of concern to identify biologically active persistent areas, hot spots, in order to study their ecology in detail. An ecological index, persistence of the bloom, was derived from the time-series of species images and it is another highlight of our study.

Growth and Mortality of Coccolithophores during spring in the Celtic Sea

NASA Astrophysics Data System (ADS)

Mayers, K.; Poulton, A. J.; Giering, S. L. C.; Daniels, C. J.; Wells, S. R.; Tarran, G.

2016-02-01

Coccolithophores are an important group of single celled protists which dominate pelagic calcite production, however little is currently known about the mortality rates within this group, or their importance in shelf seas regarding productivity and nutrient recycling. Measurements of coccolithophore calcification and cellular calcite quotas, as well as dilution experiments for microzooplankton grazing rates, were made during a spring cruise (April, 2015) in the Celtic Sea (NW European Shelf) and within an April bloom of Emiliania huxleyi. Calcite production and coccolithophore cell numbers showed a general positive trend throughout the progression of the spring bloom, ranging from 15 - 34µmol C m-3d-1 and 6 - 94 cells ml-1. Cell normalised calcification rates declined from 3 - 0.6 pmol C cell-1d-1 due to a shift from a mixed community to an E. huxleyi dominated one. Within the E. huxleyi bloom we recorded high daily calcite production (6049 µmol C m-3d-1) and cell normalised calcification of 3 pmol C cell-1d-1. This is significantly higher than E. huxleyi dominated sites in the Iceland Basin and more similar to a bloom on the Patagonian Shelf. Within the E. huxleyi bloom, mortality rates were 0.23 d-1 compared with growth rates of 0.29 d-1, meaning 80% of daily calcification was removed by grazers. In this study, coccolithophore mortality rates are presented from the central Celtic Sea throughout spring, and compared with an April E. huxleyi bloom in terms of species composition, trends in calcite production and composition of the phytoplankton community. These observations will potentially elucidate the role grazing plays in the fate of calcium carbonate, bloom formation and community composition.

Diel feeding behavior and ingestion rate in the copepod Calanus finmarchicus in the southern Gulf of Maine during late spring

NASA Astrophysics Data System (ADS)

Durbin, Edward G.; Campbell, Robert G.; Gilman, Sharon L.; Durbin, Ann G.

In situ feeding was measured on late stage Calanus finmarchicus in the southern Gulf of Maine during late spring 1988 and 1989. The region is a spring feeding ground for the planktivorous right whale, Eubalaena glacialis. Measurements in 1988 were made during the declining spring bloom, when phytoplankton showed considerable spatial variability. 1989 observations were made after summer stratification had become established, when phytoplankton biomass was low and dominated by the <7 μm size fraction. In situ ingestion rates of C. finmarchicus reflected these differences in food, and ranged from 30.2% body C day -1 at a spring bloom station to 0.6% body C day -1 after stratification. These values compare with a maximum ingestion rate of 44.3% body C day -1 measured in a shipboard grazing experiment using cultured algae as food, and indicate that C. finmarchicus became food limited in the southern Gulf of Maine after stratification. Calanus finmarchicus diet feeding behavior and diet vertical migration patterns changed during the seasonal progression from spring bloom to summer stratification. Diet feeding rhythms and vertical migration were absent during the bloom, but developed as the bloom declined. During the post-bloom stratified conditions, diet feeding rhythms continued but vertical migration ceased. Most of the C. finmarchicus population remained near the surface, while a small population of nonmigratory individuals resided at depth and appeared to be feeding upon sedimented spring bloom diatoms. At the spring bloom station C. finmarchicus ingested only a small proportion of the phytoplankton standing stock in the > 7 μm size fraction (2.9% day -1), reflecting the high biomass of phytoplankton and the stage composition of the C. finmarchicus population, dominated by early copepodite stages with low biomass. In contrast, at the post-bloom stations in 1989, the dense surface aggregations of C. finmarchicus populations were dominated by late copepodite stages whose total biomass was comparable to that of the phytoplankton, and C. finmarchicus consumed a significantly larger fraction of the > 7 μm phytoplankton standing crop (up to 62.5% day -1.

Spatio-Temporal Interdependence of Bacteria and Phytoplankton during a Baltic Sea Spring Bloom

PubMed Central

Bunse, Carina; Bertos-Fortis, Mireia; Sassenhagen, Ingrid; Sildever, Sirje; Sjöqvist, Conny; Godhe, Anna; Gross, Susanna; Kremp, Anke; Lips, Inga; Lundholm, Nina; Rengefors, Karin; Sefbom, Josefin; Pinhassi, Jarone; Legrand, Catherine

2016-01-01

In temperate systems, phytoplankton spring blooms deplete inorganic nutrients and are major sources of organic matter for the microbial loop. In response to phytoplankton exudates and environmental factors, heterotrophic microbial communities are highly dynamic and change their abundance and composition both on spatial and temporal scales. Yet, most of our understanding about these processes comes from laboratory model organism studies, mesocosm experiments or single temporal transects. Spatial-temporal studies examining interactions of phytoplankton blooms and bacterioplankton community composition and function, though being highly informative, are scarce. In this study, pelagic microbial community dynamics (bacteria and phytoplankton) and environmental variables were monitored during a spring bloom across the Baltic Proper (two cruises between North Germany to Gulf of Finland). To test to what extent bacterioplankton community composition relates to the spring bloom, we used next generation amplicon sequencing of the 16S rRNA gene, phytoplankton diversity analysis based on microscopy counts and population genotyping of the dominating diatom Skeletonema marinoi. Several phytoplankton bloom related and environmental variables were identified to influence bacterial community composition. Members of Bacteroidetes and Alphaproteobacteria dominated the bacterial community composition but the bacterial groups showed no apparent correlation with direct bloom related variables. The less abundant bacterial phyla Actinobacteria, Planctomycetes, and Verrucomicrobia, on the other hand, were strongly associated with phytoplankton biomass, diatom:dinoflagellate ratio, and colored dissolved organic matter (cDOM). Many bacterial operational taxonomic units (OTUs) showed high niche specificities. For example, particular Bacteroidetes OTUs were associated with two distinct genetic clusters of S. marinoi. Our study revealed the complexity of interactions of bacterial taxa with inter- and intraspecific genetic variation in phytoplankton. Overall, our findings imply that biotic and abiotic factors during spring bloom influence bacterial community dynamics in a hierarchical manner. PMID:27148206

Controlling cyanobacterial blooms in hypertrophic Lake Taihu, China: will nitrogen reductions cause replacement of non-N2 fixing by N2 fixing taxa?

PubMed

Paerl, Hans W; Xu, Hai; Hall, Nathan S; Zhu, Guangwei; Qin, Boqiang; Wu, Yali; Rossignol, Karen L; Dong, Linghan; McCarthy, Mark J; Joyner, Alan R

2014-01-01

Excessive anthropogenic nitrogen (N) and phosphorus (P) inputs have caused an alarming increase in harmful cyanobacterial blooms, threatening sustainability of lakes and reservoirs worldwide. Hypertrophic Lake Taihu, China's third largest freshwater lake, typifies this predicament, with toxic blooms of the non-N2 fixing cyanobacteria Microcystis spp. dominating from spring through fall. Previous studies indicate N and P reductions are needed to reduce bloom magnitude and duration. However, N reductions may encourage replacement of non-N2 fixing with N2 fixing cyanobacteria. This potentially counterproductive scenario was evaluated using replicate, large (1000 L), in-lake mesocosms during summer bloom periods. N+P additions led to maximum phytoplankton production. Phosphorus enrichment, which promoted N limitation, resulted in increases in N2 fixing taxa (Anabaena spp.), but it did not lead to significant replacement of non-N2 fixing with N2 fixing cyanobacteria, and N2 fixation rates remained ecologically insignificant. Furthermore, P enrichment failed to increase phytoplankton production relative to controls, indicating that N was the most limiting nutrient throughout this period. We propose that Microcystis spp. and other non-N2 fixing genera can maintain dominance in this shallow, highly turbid, nutrient-enriched lake by outcompeting N2 fixing taxa for existing sources of N and P stored and cycled in the lake. To bring Taihu and other hypertrophic systems below the bloom threshold, both N and P reductions will be needed until the legacy of high N and P loading and sediment nutrient storage in these systems is depleted. At that point, a more exclusive focus on P reductions may be feasible.

Controlling Cyanobacterial Blooms in Hypertrophic Lake Taihu, China: Will Nitrogen Reductions Cause Replacement of Non-N2 Fixing by N2 Fixing Taxa?

PubMed Central

Paerl, Hans W.; Xu, Hai; Hall, Nathan S.; Zhu, Guangwei; Qin, Boqiang; Wu, Yali; Rossignol, Karen L.; Dong, Linghan; McCarthy, Mark J.; Joyner, Alan R.

2014-01-01

Excessive anthropogenic nitrogen (N) and phosphorus (P) inputs have caused an alarming increase in harmful cyanobacterial blooms, threatening sustainability of lakes and reservoirs worldwide. Hypertrophic Lake Taihu, China’s third largest freshwater lake, typifies this predicament, with toxic blooms of the non-N2 fixing cyanobacteria Microcystis spp. dominating from spring through fall. Previous studies indicate N and P reductions are needed to reduce bloom magnitude and duration. However, N reductions may encourage replacement of non-N2 fixing with N2 fixing cyanobacteria. This potentially counterproductive scenario was evaluated using replicate, large (1000 L), in-lake mesocosms during summer bloom periods. N+P additions led to maximum phytoplankton production. Phosphorus enrichment, which promoted N limitation, resulted in increases in N2 fixing taxa (Anabaena spp.), but it did not lead to significant replacement of non-N2 fixing with N2 fixing cyanobacteria, and N2 fixation rates remained ecologically insignificant. Furthermore, P enrichment failed to increase phytoplankton production relative to controls, indicating that N was the most limiting nutrient throughout this period. We propose that Microcystis spp. and other non-N2 fixing genera can maintain dominance in this shallow, highly turbid, nutrient-enriched lake by outcompeting N2 fixing taxa for existing sources of N and P stored and cycled in the lake. To bring Taihu and other hypertrophic systems below the bloom threshold, both N and P reductions will be needed until the legacy of high N and P loading and sediment nutrient storage in these systems is depleted. At that point, a more exclusive focus on P reductions may be feasible. PMID:25405474

UV-induced photochemical heterogeneity of dissolved and attached organic matter associated with cyanobacterial blooms in a eutrophic freshwater lake.

PubMed

Xu, Huacheng; Jiang, Helong

2013-11-01

Cyanobacterial blooms represent a significant ecological and human health problem worldwide. In aquatic environments, cyanobacterial blooms are actually surrounded by dissolved organic matter (DOM) and attached organic matter (AOM) that bind with algal cells. In this study, DOM and AOM fractionated from blooming cyanobacteria in a eutrophic freshwater lake (Lake Taihu, China) were irradiated with a polychromatic UV lamp, and the photochemical heterogeneity was investigated using fluorescence excitation-emission matrix (EEM)-parallel factor (PARAFAC) analysis and synchronous fluorescence (SF)-two dimensional correlation spectroscopy (2DCOS). It was shown that a 6-day UV irradiation caused more pronounced mineralization for DOM than AOM (59.7% vs. 41.9%). The EEM-PARAFAC analysis identified one tyrosine-, one humic-, and two tryptophan-like components in both DOM and AOM, and high component photodegradation rates were observed for DOM versus AOM (k > 0.554 vs. <0.519). Moreover, SF-2DCOS found that the photodegradation of organic matters followed the sequence of tyrosine-like > humic-like > tryptophan-like substances. Humic-like substances promoted the indirect photochemical reactions, and were responsible for the higher photochemical rate for DOM. The lower photodegradation of AOM benefited the integrality of cells in cyanobacterial blooms against the negative impact of UV irradiation. Therefore, the photochemical behavior of organic matter was related to the adaptation of enhanced-duration cyanobacterial blooms in aquatic environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

To bloom or not to bloom: contrasting responses of cyanobacteria to recent heat waves explained by critical thresholds of abiotic drivers.

PubMed

Huber, Veronika; Wagner, Carola; Gerten, Dieter; Adrian, Rita

2012-05-01

Past heat waves are considered harbingers of future climate change. In this study, we have evaluated the effects of two recent Central European summer heat waves (2003 and 2006) on cyanobacterial blooms in a eutrophic, shallow lake. While a bloom of cyanobacteria developed in 2006, consistent with our expectations, cyanobacterial biomass surprisingly remained at a record-low during the entire summer of 2003. Critical thresholds of abiotic drivers extracted from the long-term (1993-2007) data set of the studied lake using classification tree analysis (CTA) proved suitable to explain these observations. We found that cyanobacterial blooms were especially favoured in 2006 because thermal stratification was critically intense (Schmidt stability >44 g cm cm(-2)) and long-lasting (>3 weeks). Our results also suggest that some cyanobacterial species (Anabaena sp.) benefitted directly from the stable water column, whereas other species (Planktothrix sp.) took advantage of stratification-induced internal nutrient loading. In 2003, conditions were less favourable for cyanobacteria due to a spell of lower temperatures and stronger winds in mid-summer; as a result, the identified thresholds of thermal stratification were hardly ever reached. Overall, our study shows that extracting critical thresholds of environmental drivers from long-term records is a promising avenue for predicting ecosystem responses to future climate warming. Specifically, our results emphasize that not average temperature increase but changes in short-term meteorological variability will determine whether cyanobacteria will bloom more often in a warmer world.

Toxicity of harmful cyanobacterial blooms to bream and roach.

PubMed

Trinchet, Isabelle; Cadel-Six, Sabrina; Djediat, Chakib; Marie, Benjamin; Bernard, Cécile; Puiseux-Dao, Simone; Krys, Sophie; Edery, Marc

2013-09-01

Aquatic ecosystems are facing increasing environmental pressures, leading to an increasing frequency of cyanobacterial Harmful Algal Blooms (cHABs) that have emerged as a worldwide concern due to their growing frequency and their potential toxicity to the fauna that threatens the functioning of ecosystems. Cyanobacterial blooms raise concerns due to the fact that several strains produce potent bioactive or toxic secondary metabolites, such as the microcystins (MCs), which are hepatotoxic to vertebrates. These strains of cyanobacteria may be potentially toxic to fish via gastrointestinal ingestion and also by direct absorption of the toxin MC from the water. The purpose of our study was to investigate toxic effects observed in fish taken from several lakes in the Ile-de-France region, where MCs-producing blooms occur. This study comprises histological studies and the measurement of MC concentrations in various organs. The histological findings are similar to those obtained following laboratory exposure of medaka fish to MCs: hepatic lesions predominate and include cell lysis and cell detachment. MC concentrations in the organs revealed that accumulation was particularly high in the digestive tract and the liver, which are known to be classical targets of MCs. In contrast concentrations were very low in the muscles. Differences in the accumulation of MC variants produced by blooms indicate that in order to more precisely evaluate the toxic potential of a specific bloom it is necessary not only to consider the concentration of toxins, but also the variants produced. Copyright © 2013 Elsevier Ltd. All rights reserved.

Designing a New Taxonomy of Educational Objectives. Experts in Assessment.

ERIC Educational Resources Information Center

Marzano, Robert J.

This volume is an attempt to articulate a taxonomy of educational objectives that uses the best available research and theory accumulated since the publication of the taxonomy of educational objectives of B. Bloom and others in 1956. Like Bloom's taxonomy, this taxonomy defines six levels of mental processing: self-system thinking (Level 6);…

Chaos Theory and James Joyce's "ulysses": Leopold Bloom as a Human COMPLEX@SYSTEM^

NASA Astrophysics Data System (ADS)

Mackey, Peter Francis

1995-01-01

These four ideas apply as much to our lives as to the life of Leopold Bloom: (1) A trivial decision can wholly change a life. (2) A chance encounter can dramatically alter life's course. (3) A contingent nexus exists between consciousness and environment. (4) A structure of meaning helps us interpret life's chaos. These ideas also relate to a contemporary science called by some "chaos theory." The connection between Ulysses and chaos theory enhances our understanding of Bloom's day; it also suggests that this novel may be about the real process of life itself. The first chapter explains how Joyce's own essays and comments to friends compel attention to the links between Ulysses and chaos theory. His scientific contemporaries anticipated chaos theory, and their ideas seem to have rubbed off on him. We see this in his sense of trivial things and chance, his modernistic organizational impulses, and the contingent nature of Bloom's experience. The second chapter studies what chaos theory and Joyce's ideas tell us about "Ithaca," the episode which particularly implicates our processes of interpreting this text as well as life itself as we face their chaos. The third chapter examines Bloom's close feel for the aboriginal world, a contingency that clarifies his vulnerability to trivial changes. The fourth chapter studies how Bloom's stream of consciousness unfolds--from his chance encounters with trivial things. Beneath this stream's seeming chaos, Bloom's distinct personality endures, similar to how Joyce's schemas give Ulysses an imbedded, underlying order. The fifth chapter examines how trivial perturbations, such as Lyons' misunderstanding about "Throwaway," produce small crises for Bloom, exacerbating his seeming impotence before his lonely "fate.". The final chapter analyzes Bloom's views that fate and chance dictate his life. His views provide an opportunity to explore the implications chaos theory has for our understanding of free will and determinism. Ultimately, despite ungovernable fate and chance, Bloom asserts his will with Stephen and Molly, proving that he will live on, attempting to create his own destiny, wresting hope from the "chaos" of his experience.

Bacterial succession across seasonal transitions in the coastal waters of the western Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Luria, C.; Rich, J. J.; Amaral-Zettler, L. A.; Ducklow, H. W.

2016-02-01

The marine ecosystem west of the Antarctic Peninsula (WAP) undergoes a dramatic seasonal transition every spring, from almost total darkness to almost continuous sunlight, resulting in a cascade of environmental changes, including the intense phytoplankton blooms that support a highly productive food web. Despite having important implications for the microbial loop and the biological carbon pump, the degree of trophic coupling between phytoplankton and bacteria is unclear. In particular, due to the difficulties inherent in sampling this remote system during the Antarctic winter and spring, little is known about how phytoplankton blooms may or may not drive bacterial seasonal succession. Using 16S rRNA gene amplicon sequencing, we assessed bacterial community composition in 68 samples from 24 dates that spanned the cold, dark winter, spring transitional period, and summer phytoplankton bloom. Our analysis resulted in 15 million sequences and 12,000 Operational Taxonomic Units (OTUs). We found that mid-winter bacterial communities had the highest richness ( 1,800 observed OTUs in rarefied libraries) and a greater abundance of oligotrophic and potentially chemoautolithotrophic taxa. The bacterial community changed only gradually up until the onset of a mid-summer phytoplankton bloom, which coincided with a 100-fold increase in bacterial production, a rapid decline in richness to 700 OTUs, and a shift in community composition toward copiotrophic taxa. This period lasted only a few weeks, at the end of which the bacterial community had largely reverted to its mid-winter state. Our findings provide new evidence of trophic coupling between bacteria and phytoplankton and highlight the importance of higher-resolution time series sampling in order to capture rapid seasonal changes.

Performance modeling of the effects of aperture phase error, turbulence, and thermal blooming on tiled subaperture systems

NASA Astrophysics Data System (ADS)

Leakeas, Charles L.; Capehart, Shay R.; Bartell, Richard J.; Cusumano, Salvatore J.; Whiteley, Matthew R.

2011-06-01

Laser weapon systems comprised of tiled subapertures are rapidly emerging in importance in the directed energy community. Performance models of these laser weapon systems have been developed from numerical simulations of a high fidelity wave-optics code called WaveTrain which is developed by MZA Associates. System characteristics such as mutual coherence, differential jitter, and beam quality rms wavefront error are defined for a focused beam on the target. Engagement scenarios are defined for various platform and target altitudes, speeds, headings, and slant ranges along with the natural wind speed and heading. Inputs to the performance model include platform and target height and velocities, Fried coherence length, Rytov number, isoplanatic angle, thermal blooming distortion number, Greenwood and Tyler frequencies, and atmospheric transmission. The performance model fit is based on power-in-the-bucket (PIB) values against the PIB from the simulation results for the vacuum diffraction-limited spot size as the bucket. The goal is to develop robust performance models for aperture phase error, turbulence, and thermal blooming effects in tiled subaperture systems.

Engineering the IOOS: A Conceptual Design and Conceptual Operations Plan

NASA Astrophysics Data System (ADS)

Lampel, M.; Hood, C.; Kleinert, J.; Morgan, R. A.; Morris, P.

2007-12-01

The Integrated Ocean Observing System is the United States component in a world wide effort to provide global coverage of the world's oceans using the Global Ocean Observing System (GOOS). The US contribution includes systems supporting three major IOOS components: the Observation Subsystem, the Modeling and Analysis Subsystem, and the Data Management and Communications (DMAC) Subsystem. The assets to be used in these subsystems include hundreds of existing satellite sensors, buoy arrays, water level monitoring networks, wave monitoring networks, specialized systems for commerce, such as the Physical Oceanographic Real-Time System (PORTS®), and health and safety monitoring systems such as NOAA's (National Oceanic and Atmospheric Administration) Harmful Algal Bloom Forecasting System for the Gulf of Mexico. Conceptual design addresses the interconnectivity of these systems, while Conceptual Operations provides understanding of the motivators for interconnectivity and a methodology for how useful products are created and distributed. This paper will report on the conceptual design and the concept of operations devleoped by the authors under contract to NOAA.

VIIRS captures phytoplankton vertical migration in the NE Gulf of Mexico.

PubMed

Qi, Lin; Hu, Chuanmin; Barnes, Brian B; Lee, Zhongping

2017-06-01

In summer 2014, a toxic Karenia brevis bloom (red tide) occurred in the NE Gulf of Mexico, during which vertical migration of K. brevis has been observed from glider measurements. The current study shows that satellite observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) can capture changes in surface reflectance and chlorophyll concentration occurring within 2h, which may be attributed this K. brevis vertical migration. The argument is supported by earlier glider measurements in the same bloom, by the dramatic changes in the VIIRS-derived surface chlorophyll, and by the consistency between the short-term reflectance changes and those reported earlier from field-measured K. brevis vertical migration. Estimates using the quasi-analytical algorithm also indicate significant increases in both total absorption coefficient and backscattering coefficient in two hours. The two observations in a day from a single polar-orbiting satellite sensor are thus shown to be able to infer phytoplankton vertical movement within a short timeframe, a phenomenon difficult to capture with other sensors as each sensor can provide at most one observation per day, and cross-sensor inconsistency may make interpretation of merged-sensor data difficult. These findings strongly support geostationary satellite missions to study short-term bloom dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Geomicrobiological perspective on the pattern and causes of the 5-million-year Permo/Triassic biotic crisis

NASA Astrophysics Data System (ADS)

Xie, Shucheng; Wang, Yongbiao

2011-03-01

The pattern and causes of Permo/Triassic biotic crisis were mainly documented by faunal and terrestrial plant records. We reviewed herein the geomicrobiological perspective on this issue based on the reported cyanobacterial record. Two episodic cyanobacterial blooms were observed to couple with carbon isotope excursions and faunal mass extinction at Meishan section, suggestive of the presence of at least two episodic biotic crises across the Permian-Triassic boundary (PTB). The two episodes of cyanobacterial blooms, carbon isotope excursions and faunal mass extinction were, respectively, identified in several sections of the world, inferring the presence of two global changes across the PTB. Close associations among the three records (cyanobacterial bloom, shift in carbon isotope composition, and faunal extinction) were subsequently observed in three intervals in the Early Triassic, the protracted recovery period as previously thought, inferring the occurrence of more episodes of global changes. Spatiotemporal association of cyanobacterial blooms with volcanic materials in South China, and probably in South-east Asia, infers their causal relationship. Volcanism is believed to trigger the biotic crisis in several ways and to cause the close association among microbial blooms, the carbon isotope excursions and faunal mass extinctions in four intervals from the latest Permian to the Early Triassic. The major episodes of the well-known Siberian flood eruption are proposed to be responsible for the extinctions in the Early Triassic, but their synchronicity with the end-Permian extinction awaits more precise dating data to confirm. Geomicrobial records are thus suggestive of a long-term episodic biotic crisis (at least four episodes) lasting from the latest Permian to the end of the Early Triassic, induced by the global volcanic eruptions and sea level changes during Pangea formation.

Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications.

PubMed

Mangoni, Olga; Saggiomo, Vincenzo; Bolinesi, Francesco; Margiotta, Francesca; Budillon, Giorgio; Cotroneo, Yuri; Misic, Cristina; Rivaro, Paola; Saggiomo, Maria

2017-01-01

During the austral summer of 2014, an oceanographic cruise was conducted in the Ross Sea in the framework of the RoME (Ross Sea Mesoscale Experiment) Project. Forty-three hydrological stations were sampled within three different areas: the northern Ross Sea (RoME 1), Terra Nova Bay (RoME 2), and the southern Ross Sea (RoME 3). The ecological and photophysiological characteristics of the phytoplankton were investigated (i.e., size structure, functional groups, PSII maximum quantum efficiency, photoprotective pigments), as related to hydrographic and chemical features. The aim was to identify the mechanisms that modulate phytoplankton blooms, and consequently, the fate of organic materials produced by the blooms. The observed biomass standing stocks were very high (e.g., integrated chlorophyll-a up to 371 mg m-2 in the top 100 m). Large differences in phytoplankton community composition, relative contribution of functional groups and photosynthetic parameters were observed among the three subsystems. The diatoms (in different physiological status) were the dominant taxa in RoME 1 and RoME 3; in RoME 1, a post-bloom phase was identified, whereas in RoME 3, an active phytoplankton bloom occurred. In RoME 2, diatoms co-occurred with Phaeocystis antarctica, but were vertically segregated by the upper mixed layer, with senescent diatoms dominating in the upper layer, and P. antarctica blooming in the deeper layer. The dominance of the phytoplankton micro-fraction over the whole area and the high Chl-a suggested the prevalence of non-grazed large cells, independent of the distribution of the two functional groups. These data emphasise the occurrence of significant temporal changes in the phytoplankton biomass in the Ross Sea during austral summer. The mechanisms that drive such changes and the fate of the carbon production are probably related to the variations in the limiting factors induced by the concurrent hydrological modifications to the Ross Sea, and they remain to be fully clarified. The comparison of conditions observed during summer 2014 and those reported for previous years reveal considerably different ecological assets that might be the result of current climate change. This suggests that further changes can be expected in the future, even at larger oceanic scales.

Phytoplankton blooms during austral summer in the Ross Sea, Antarctica: Driving factors and trophic implications

PubMed Central

Saggiomo, Vincenzo; Bolinesi, Francesco; Margiotta, Francesca; Budillon, Giorgio; Cotroneo, Yuri; Misic, Cristina; Rivaro, Paola; Saggiomo, Maria

2017-01-01

During the austral summer of 2014, an oceanographic cruise was conducted in the Ross Sea in the framework of the RoME (Ross Sea Mesoscale Experiment) Project. Forty-three hydrological stations were sampled within three different areas: the northern Ross Sea (RoME 1), Terra Nova Bay (RoME 2), and the southern Ross Sea (RoME 3). The ecological and photophysiological characteristics of the phytoplankton were investigated (i.e., size structure, functional groups, PSII maximum quantum efficiency, photoprotective pigments), as related to hydrographic and chemical features. The aim was to identify the mechanisms that modulate phytoplankton blooms, and consequently, the fate of organic materials produced by the blooms. The observed biomass standing stocks were very high (e.g., integrated chlorophyll-a up to 371 mg m-2 in the top 100 m). Large differences in phytoplankton community composition, relative contribution of functional groups and photosynthetic parameters were observed among the three subsystems. The diatoms (in different physiological status) were the dominant taxa in RoME 1 and RoME 3; in RoME 1, a post-bloom phase was identified, whereas in RoME 3, an active phytoplankton bloom occurred. In RoME 2, diatoms co-occurred with Phaeocystis antarctica, but were vertically segregated by the upper mixed layer, with senescent diatoms dominating in the upper layer, and P. antarctica blooming in the deeper layer. The dominance of the phytoplankton micro-fraction over the whole area and the high Chl-a suggested the prevalence of non-grazed large cells, independent of the distribution of the two functional groups. These data emphasise the occurrence of significant temporal changes in the phytoplankton biomass in the Ross Sea during austral summer. The mechanisms that drive such changes and the fate of the carbon production are probably related to the variations in the limiting factors induced by the concurrent hydrological modifications to the Ross Sea, and they remain to be fully clarified. The comparison of conditions observed during summer 2014 and those reported for previous years reveal considerably different ecological assets that might be the result of current climate change. This suggests that further changes can be expected in the future, even at larger oceanic scales. PMID:28430813

Spring bloom onset in the Nordic Seas

NASA Astrophysics Data System (ADS)

Mignot, Alexandre; Ferrari, Raffaele; Mork, Kjell Arne

2016-06-01

The North Atlantic spring bloom is a massive annual growth event of marine phytoplankton, tiny free-floating algae that form the base of the ocean's food web and generates a large fraction of the global primary production of organic matter. The conditions that trigger the onset of the spring bloom in the Nordic Seas, at the northern edge of the North Atlantic, are studied using in situ data from six bio-optical floats released north of the Arctic Circle. It is often assumed that spring blooms start as soon as phytoplankton cells daily irradiance is sufficiently abundant that division rates exceed losses. The bio-optical float data instead suggest the tantalizing hypothesis that Nordic Seas blooms start when the photoperiod, the number of daily light hours experienced by phytoplankton, exceeds a critical value, independently of division rates. The photoperiod trigger may have developed at high latitudes where photosynthesis is impossible during polar nights and phytoplankton enters into a dormant stage in winter. While the first accumulation of biomass recorded by the bio-optical floats is consistent with the photoperiod hypothesis, it is possible that some biomass accumulation started before the critical photoperiod but at levels too low to be detected by the fluorometers. More precise observations are needed to test the photoperiod hypothesis.

Climate change impact on growing degree day accumulation values

NASA Astrophysics Data System (ADS)

Bekere, Liga; Sile, Tija; Bethers, Uldis; Sennikovs, Juris

2015-04-01

A well-known and often used method to assess and forecast plant growth cycle is the growing degree day (GDD) method with different formulas used for accumulation calculations. With this method the only factor that affects plant development is temperature. So with climate change and therefore also change in temperature the typical times of plant blooming or harvest can be expected to change. The goal of this study is to assess this change in the Northern Europe region. As an example strawberry bloom and harvest times are used. As the first part of this study it was required to define the current GDD amounts required for strawberry bloom and harvest. It was done using temperature data from the Danish Meteorological Institute's (DMI) NWP model HIRLAM for the years 2010-2012 and general strawberry growth observations in Latvia. This way we acquired an example amount of GDD required for strawberry blooming and harvest. To assess change in the plant growth cycle we used regional climate models (RCM) - Euro-CORDEX. RCM temperature data for both past and future periods was analyzed and bias correction was carried out. Then the GDD calculation methodology was applied on corrected temperature data and results showing change in strawberry growth cycle - bloom and harvest times - in Northern Europe were visualized.

Oil Spills and Dispersants Can Cause the Initiation of Potentially Harmful Dinoflagellate Blooms ("Red Tides").

PubMed

Almeda, Rodrigo; Cosgrove, Sarah; Buskey, Edward J

2018-05-15

After oil spills and dispersant applications the formation of red tides or harmful algal blooms (HABs) has been observed, which can cause additional negative impacts in areas affected by oil spills. However, the link between oil spills and HABs is still unknown. Here, we present experimental evidence that demonstrates a connection between oil spills and HABs. We determined the effects of oil, dispersant-treated oil, and dispersant alone on the structure of natural plankton assemblages in the Northern Gulf of Mexico. In coastal waters, large tintinnids and oligotrich ciliates, major grazers of phytoplankton, were negatively affected by the exposure to oil and dispersant, whereas bloom-forming dinoflagellates ( Prorocentrum texanum, P. triestinum, and Scrippsiella trochoidea) notably increased their concentration. The removal of key grazers due to oil and dispersant disrupts the predator-prey controls ("top-down controls") that normally function in plankton food webs. This disruption of grazing pressure opens a "loophole" that allows certain dinoflagellates with higher tolerance to oil and dispersants than their grazers to grow and form blooms when there are no growth limiting factors (e.g., nutrients). Therefore, oil spills and dispersants can act as disrupters of predator-prey controls in plankton food webs and as indirect inducers of potentially harmful dinoflagellate blooms.

A salp bloom (Tunicata, Thaliacea) along the Apulian coast and in the Otranto Channel between March-May 2013

PubMed Central

Boero, Ferdinando; Belmonte, Genuario; Bracale, Roberta; Fraschetti, Simonetta; Piraino, Stefano; Zampardi, Serena

2013-01-01

Between March-May 2013 a massive Salpa maxima bloom was recorded by a citizen science study along the Ionian and Adriatic coast of the Salento peninsula (Italy). Citizen records were substantiated with field inspections along the coast and during an oceanographic campaign in the Otranto Channel. Salps clogged nets, impairing fishing activities along the coast. Swimmers were scared by the gelatinous appearance of the salps, and thought they were jellyfish. At the end of the bloom the dead bodies of the colonies, that were up to 6-7 m long, were accumulated along the coast and stirred by the waves, forming foams along dozens of kilometers of coast. The bloom also occurred at the Tremiti Islands, north of the Gargano Peninsula. The possible impacts of such events on the  functioning of pelagic systems are discussed. PMID:26594319

A salp bloom (Tunicata, Thaliacea) along the Apulian coast and in the Otranto Channel between March-May 2013.

PubMed

Boero, Ferdinando; Belmonte, Genuario; Bracale, Roberta; Fraschetti, Simonetta; Piraino, Stefano; Zampardi, Serena

2013-01-01

Between March-May 2013 a massive Salpa maxima bloom was recorded by a citizen science study along the Ionian and Adriatic coast of the Salento peninsula (Italy). Citizen records were substantiated with field inspections along the coast and during an oceanographic campaign in the Otranto Channel. Salps clogged nets, impairing fishing activities along the coast. Swimmers were scared by the gelatinous appearance of the salps, and thought they were jellyfish. At the end of the bloom the dead bodies of the colonies, that were up to 6-7 m long, were accumulated along the coast and stirred by the waves, forming foams along dozens of kilometers of coast. The bloom also occurred at the Tremiti Islands, north of the Gargano Peninsula. The possible impacts of such events on the  functioning of pelagic systems are discussed.

Toxic Cyanobacterial Bloom Triggers in Missisquoi Bay, Lake Champlain, as Determined by Next-Generation Sequencing and Quantitative PCR

PubMed Central

Fortin, Nathalie; Munoz-Ramos, Valentina; Bird, David; Lévesque, Benoît; Whyte, Lyle G.; Greer, Charles W.

2015-01-01

Missisquoi Bay (MB) is a temperate eutrophic freshwater lake that frequently experiences toxic Microcystis-dominated cyanobacterial blooms. Non-point sources are responsible for the high concentrations of phosphorus and nitrogen in the bay. This study combined data from environmental parameters, E. coli counts, high-throughput sequencing of 16S rRNA gene amplicons, quantitative PCR (16S rRNA and mcyD genes) and toxin analyses to identify the main bloom-promoting factors. In 2009, nutrient concentrations correlated with E. coli counts, abundance of total cyanobacterial cells, Microcystis 16S rRNA and mcyD genes and intracellular microcystin. Total and dissolved phosphorus also correlated significantly with rainfall. The major cyanobacterial taxa were members of the orders Chroococcales and Nostocales. The genus Microcystis was the main mcyD-carrier and main microcystin producer. Our results suggested that increasing nutrient concentrations and total nitrogen:total phosphorus (TN:TP) ratios approaching 11:1, coupled with an increase in temperature, promoted Microcystis-dominated toxic blooms. Although the importance of nutrient ratios and absolute concentrations on cyanobacterial and Microcystis dynamics have been documented in other laboratories, an optimum TN:TP ratio for Microcystis dominance has not been previously observed in situ. This observation provides further support that nutrient ratios are an important determinant of species composition in natural phytoplankton assemblages. PMID:25984732

Modelling of Peach Tree (Prunus persica) Full Blooming Dates Using APCC MME Seasonal Forecasts

NASA Astrophysics Data System (ADS)

Chun, Jong; Kim, Sung; Lee, Hyojin; Han, Hyun-Hee; Son, In-Chang; Cho, Kyung Hwa

2016-04-01

Due to global warming, recently, bud-burst and flowering dates of fruit crops have become earlier and the abnormal climate increases the variabilities of temperature in spring, suggesting that the risk of frost damage has increased. However, the full blooming date prediction model for peach tree used by the Rural Developmental Administration (RDA) were developed using only one cultivar (Youmyeong) and observations from a station (Suwon). This model might not adequately reflect the characteristics of peach cultivars or local orchards. the objectives of this study were to develops the site-and cultivar-specific blooming date prediction models for major peach cultivation regions and cultivars and presents a framework for applications of the APEC Climate Center Multimodel Ensemble (APCC MME) seasonal datasets.Developmental rate (DVR), and Sequential dormancy models (Chill day, New chill day, and fraction-time models) were used to develop the locally tailored full blooming date prediction models for major peach cultivars. For the development of these models, bud-burst and full blooming dates of peach tree for 5 cultivars (Cheonhong, Youmyeong, Changbangjosaeng, Cheonjoongdo, and Janghowon) were collected from the 6 major peach cultivation sites: Chuncheon, Suwon, Cheongwon, Cheongdo, Naju, and Jinju. For the chill day model, those measures for the entire dataset regardless the location and cultivar were 2.31%, 0.79, and 3.36 day for MAPE, R2, RMSE, respectively. For the new chill day model, those values (2.19%, 0.82, and 3.16 day for MAPE, R2, RMSE, respectively) were slightly better than those of the chill day model. The model results showed that the new chill day model was found slightly highest performance than others. Based on the considerations of the predictability of the statistical downscaling method and the observed periods of the full blooming dates at each site, we determined that the APCC MME seasonal datasets were applied for the new chill day model for the Changbangjosaeng and Youmyeong cultivars at the Suwon site. The values of the goodness-of-fit measures using the selected synthetic daily maximum and minimum temperatures reflecting APCC MME seasonal datasets and selected were worse than those using those collected from the Suwon station. It is concluded that further work was recommended that the predictability of APCC MME seasonal forecasts should be improved to reduce the prediction errors of full blooming dates of peach trees.

Akinetes May Be Representative of Past Nostocalean Blooms: a Case Study of Their Benthic Spatiotemporal Distribution and Potential for Germination in a Eutrophic Lake

PubMed Central

Le Jeune, Anne-Hélène; Colombet, Jonathan; Thouvenot, Antoine; Latour, Delphine

2017-01-01

ABSTRACT Monitoring of water and surface sediment in a French eutrophic lake (Lake Aydat) was carried out over a 2-year period in order to determine whether akinetes in sediment could be representative of the most recent bloom and to estimate their germination potential. Sediment analysis revealed two akinete species, Dolichospermum macrosporum and Dolichospermum flos-aquae, present in the same proportions as observed for the pelagic populations. Moreover, similar spatial patterns observed for vegetative cells in the water column and akinete distributions in the sediment suggest that akinetes in the sediment may be representative of the previous bloom. However, the relationship between akinetes in the sediment and vegetative cells in the water column was not linear, and other factors may interfere. For example, our results highlighted horizontal transport of akinetes during the winter. The benthic overwinter phase did not seem to influence the percentages of intact akinetes, which remained stable at approximately 7% and 60% for D. macrosporum and D. flos-aquae, respectively. These percentages may thus be the result of processes that occurred in the water column. The intact overwintering akinetes showed germination rates of up to 90% after 72 h for D. flos-aquae or 144 h for D. macrosporum. The difference in akinete germination rates between these two species demonstrates different ecological strategies, which serve to expand the window for germination in time and space and thus optimize colonization of the water column by nostocalean cyanobacteria. IMPORTANCE Cyanobacteria have the ability to proliferate and to form blooms. These blooms can then affect the local ecology, health, and economy. The akinete, a resistant cell type that persists in sediment, is an important intermediate phase between previous and future blooms. We monitored the water column and the surface sediment of a French eutrophic lake (Lake Aydat) to investigate the relationship between vegetative cells in the water column and akinetes in the sediment. This study focused on the characterization of spatiotemporal akinete distributions, cellular integrity, and germination potential. Species-specific ecological strategies were highlighted and may partly explain the temporal succession of species in the water column. Akinetes may also be used to understand past nostocalean blooms and to predict future ones. PMID:28970224

Bloom in the Ross Sea

NASA Image and Video Library

2011-01-29

NASA image acquired January 22, 2011 To see a detail of this image go to: www.flickr.com/photos/gsfc/5398237910 Every southern spring and summer, after the Sun has risen into its 24-hour circuit around the skies of Antarctica, the Ross Sea bursts with life. Floating, microscopic plants, known as phytoplankton, soak up the sunlight and the nutrients stirring in the Southern Ocean and grow into prodigious blooms. Those blooms become a great banquet for krill, fish, penguins, whales, and other marine species who carve out a living in the cool waters of the far south. This true-color image captures such a bloom in the Ross Sea on January 22, 2011, as viewed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Bright greens of plant-life have replaced the deep blues of open ocean water. The Ross Sea is a relatively shallow bay in the Antarctic coastline and due south from New Zealand. As the spring weather thaws the sea ice around Antarctica, areas of open water surrounded by ice—polynyas—open up on the continental shelf. In this open water, sunlight provides the fuel and various current systems provide nutrients from deeper waters to form blooms that can stretch 100 to 200 kilometers (60 to 120 miles). These blooms are among the largest in extent and abundance in the world. Scientists have hypothesized that the Modified Circumpolar Deep Water is the engine behind the blooms, stirring up just the right mix of trace metals and minerals from the deep to sustain plankton growth. This month, researchers aboard the U.S. icebreaking ship Nathaniel B. Palmer are cruising in the Ross Sea in search of the signatures of this current system. NASA image courtesy Norman Kuring, Ocean Color Team at NASA Goddard Space Flight Center. Caption by Mike Carlowicz, with information from Hugh Powell, COSEE-NOW. Instrument: Aqua - MODIS Credit: NASA Earth Observatory earthobservatory.nasa.gov/IOTD/view.php?id=48949 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. Follow us on Twitter Join us on Facebook

Bloom in the Ross Sea

NASA Image and Video Library

2017-12-08

NASA image acquired January 22, 2011 Every southern spring and summer, after the Sun has risen into its 24-hour circuit around the skies of Antarctica, the Ross Sea bursts with life. Floating, microscopic plants, known as phytoplankton, soak up the sunlight and the nutrients stirring in the Southern Ocean and grow into prodigious blooms. Those blooms become a great banquet for krill, fish, penguins, whales, and other marine species who carve out a living in the cool waters of the far south. This true-color image captures such a bloom in the Ross Sea on January 22, 2011, as viewed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Bright greens of plant-life have replaced the deep blues of open ocean water. The Ross Sea is a relatively shallow bay in the Antarctic coastline and due south from New Zealand. As the spring weather thaws the sea ice around Antarctica, areas of open water surrounded by ice—polynyas—open up on the continental shelf. In this open water, sunlight provides the fuel and various current systems provide nutrients from deeper waters to form blooms that can stretch 100 to 200 kilometers (60 to 120 miles). These blooms are among the largest in extent and abundance in the world. Scientists have hypothesized that the Modified Circumpolar Deep Water is the engine behind the blooms, stirring up just the right mix of trace metals and minerals from the deep to sustain plankton growth. This month, researchers aboard the U.S. icebreaking ship Nathaniel B. Palmer are cruising in the Ross Sea in search of the signatures of this current system. NASA image courtesy Norman Kuring, Ocean Color Team at NASA Goddard Space Flight Center. Caption by Mike Carlowicz, with information from Hugh Powell, COSEE-NOW. Instrument: Aqua - MODIS Go here to download the full high res file: earthobservatory.nasa.gov/IOTD/view.php?id=48949 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. Follow us on Twitter Like us on Facebook Find us on Instagram

Bloom in the Ross Sea [detail

NASA Image and Video Library

2017-12-08

NASA image acquired January 22, 2011 To view the full image go to: www.flickr.com/photos/gsfc/5397636843 Every southern spring and summer, after the Sun has risen into its 24-hour circuit around the skies of Antarctica, the Ross Sea bursts with life. Floating, microscopic plants, known as phytoplankton, soak up the sunlight and the nutrients stirring in the Southern Ocean and grow into prodigious blooms. Those blooms become a great banquet for krill, fish, penguins, whales, and other marine species who carve out a living in the cool waters of the far south. This true-color image captures such a bloom in the Ross Sea on January 22, 2011, as viewed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Bright greens of plant-life have replaced the deep blues of open ocean water. The Ross Sea is a relatively shallow bay in the Antarctic coastline and due south from New Zealand. As the spring weather thaws the sea ice around Antarctica, areas of open water surrounded by ice—polynyas—open up on the continental shelf. In this open water, sunlight provides the fuel and various current systems provide nutrients from deeper waters to form blooms that can stretch 100 to 200 kilometers (60 to 120 miles). These blooms are among the largest in extent and abundance in the world. Scientists have hypothesized that the Modified Circumpolar Deep Water is the engine behind the blooms, stirring up just the right mix of trace metals and minerals from the deep to sustain plankton growth. This month, researchers aboard the U.S. icebreaking ship Nathaniel B. Palmer are cruising in the Ross Sea in search of the signatures of this current system. NASA image courtesy Norman Kuring, Ocean Color Team at NASA Goddard Space Flight Center. Caption by Mike Carlowicz, with information from Hugh Powell, COSEE-NOW. Instrument: Aqua - MODIS For more info go to: earthobservatory.nasa.gov/IOTD/view.php?id=48949 Credit: NASA Earth Observatory 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. Follow us on Twitter Join us on Facebook

High abundances of cyanomyoviruses in marine ecosystems demonstrate ecological relevance.

PubMed

Matteson, Audrey R; Rowe, Janet M; Ponsero, Alise J; Pimentel, Tiana M; Boyd, Philip W; Wilhelm, Steven W

2013-05-01

The distribution of cyanomyoviruses was estimated using a quantitative PCR (qPCR) approach that targeted the g20 gene as a proxy for phage. Samples were collected spatially during a > 3000 km transect through the Sargasso Sea and temporally during a gyre-constrained phytoplankton bloom within the southern Pacific Ocean. Cyanomyovirus abundances were lower in the Sargasso Sea than in the southern Pacific Ocean, ranging from 2.75 × 10(3) to 5.15 × 10(4) mL(-1) and correlating with the abundance of their potential hosts (Prochlorococcus and Synechococcus). Cyanomyovirus abundance in the southern Pacific Ocean (east of New Zealand) followed Synechococcus host populations in the system: this included a decrease in g20 gene copies (from 4.3 × 10(5) to 9.6 × 10(3) mL(-1) ) following the demise of a Synechococcus bloom. When compared with direct counts of viruses, observations suggest that the cyanomyoviruses comprised 0.5 to >25% of the total virus community. We estimated daily lysis rates of 0.2-46% of the standing stock of Synechococcus in the Pacific Ocean compared with c. < 1.0% in the Sargasso Sea. In total, our observations confirm this family of viruses is abundant in marine systems and that they are an important source of cyanobacterial mortality. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Observations from Space: Marine Ecosystem and Environment Response to Typhoon/ Hurricanes

NASA Astrophysics Data System (ADS)

Tang, Danling; Yi, Sui

Marine ecosystem is sensitive to environmental factors, including typhoon. Typhoon's activities have been strengthening in both intensity and spatial coverage in the past several decades, along with global changes; however, our knowledge about the impact of typhoons upon the marine ecosystem is very scarce. To understand how could typhoon/hurricane impact on marine ecosystem, we have conducted a series studies in the South China Sea, by using Satellite remote sensing and in situ observation data to investigate phytoplankton concentration, sea surface temperature (SST) and related factors before, during, and after typhoon. Results show that typhoon can induce large area of phytoplankton blooms with increases of Chlorophyll a (Chl a) concentrations and decrease of sea surface temperature (SST) about 4 oC. Analysis showed that typhoon can support nutrients to surface phytoplankton by upwelling and vertical mixing, and typhoon rain can also nourish marine phytoplankton. More observations confirmed that typhoon can induce cold eddy, and cold eddy can support eddy-shape phyto-plankton bloom by upwelling. Typhoon can also induce transport of nutrient-rich water from depth and from the coast to offshore regions, nourishing phytoplankton biomass. Comparative study show that slow-moving typhoon induced phytoplankton blooms of higher Chlorophyll-a (Chl-a), the strong typhoon induced phytoplankton blooms of a large area. Therefore, typhoons may have important contribution to the marine primary production. Those studies may help better understand the mechanism of typhoon impacts on marine ecosys-tem, and the role of typhoon in the global environmental changes. The series research were sup-ported by: NSFC (40976091, 40811140533) and GD NSF (8351030101000002); (2) CAS(kzcx2-yw-226 and LYQ200701); (3) The CAS/SAFEA International Partnership Program for Creative Research Teams (KZCX2-YW-T001). References: Tang, DanLing, H Kawamura, P Shi, W Takahashi, T Shimada, F. Sakaida, O Isoguchi, 2005. Seasonal phytoplankton blooms associated with monsoonal influences and coastal environments in the sea areas either side of the Indochina Peninsula. JGR-Bio-geo. VOL. 111, G01010, doi:10.1029/2005JG000050, 2006. Tang, DanLing, H Kawamura, Hai Doan-Nhu, W Takahashi , 2004. Remote sensing oceanography of a harmful algal bloom (HAB) off the coast of southeastern Vietnam. J. of Geophysical Research (Ocean).Vol 109, doi:10.1029/2003JC002045; Tang, DanLing, H Kawamura, TV Dien. MA Lee, 2004. Offshore phytoplankton biomass increase and its oceanographic causes in the South China Sea. Marine Ecology Progress Series, 268: 31-41; Tang, DanLing, H ZHAO, B. Satyanarayana, GM ZHENG, RP. SINGH, JH LV, 2009, Enhancement of Chlorophyll-a in the Northeastern Indian Ocean after the 2004 South Asian Tsunami, Int. J. Remote Sensing doi10.1080/01431160802603778 , Vol.30 (17):4553-4565; Zhao, H., DanLing Tang, and Y. Wang, 2008, Comparison of phyto-plankton blooms triggered by two typhoons with different intensities and translation speeds in the South China SeaMar Ecol Prog Ser, 365, 57-65; Zheng, GM. and DanLing Tang ,2007Off-shore and nearshore chlorophyll increases induced by typhoon winds and subsequent terrestrial rainwater runoff, Mar Ecol Prog Ser, 333, 61-72; H Zhao, DanLing TANG, DX Wang, 2009, Phytoplankton blooms near the Pearl River Estuary induced by Typhoon Nuri, Journal of Geophysical Research -Oceans. 114, C12027; YQ Chen, DanLing Tang, 2010, Cold eddies and eddy-shape phytoplankton blooms induced by tropical cyclone Linfa in the South China Sea. In preparation; XX Yang, DanLing Tang, 2010, Sea Surface Temperature Decreasing in the Northern South China Sea Induced by Typhoon. In preparation.

Cyanobacteria of the 2016 Lake Okeechobee and Okeechobee Waterway harmful algal bloom

USGS Publications Warehouse

Rosen, Barry H.; Davis, Timothy W.; Gobler, Christopher J.; Kramer, Benjamin J.; Loftin, Keith A.

2017-05-31

The Lake Okeechobee and the Okeechobee Waterway (Lake Okeechobee, the St. Lucie Canal and River, and the Caloosahatchee River) experienced an extensive harmful algal bloom within Lake Okeechobee, the St. Lucie Canal and River and the Caloosahatchee River in 2016. In addition to the very visible bloom of the cyanobacterium Microcystis aeruginosa, several other cyanobacteria were present. These other species were less conspicuous; however, they have the potential to produce a variety of cyanotoxins, including anatoxins, cylindrospermopsins, and saxitoxins, in addition to the microcystins commonly associated with Microcystis. Some of these species were found before, during, and 2 weeks after the large Microcystis bloom and could provide a better understanding of bloom dynamics and succession. This report provides photographic documentation and taxonomic assessment of the cyanobacteria present from Lake Okeechobee and the Caloosahatchee River and St. Lucie Canal, with samples collected June 1st from the Caloosahatchee River and Lake Okeechobee and in July from the St. Lucie Canal. The majority of the images were of live organisms, allowing their natural complement of pigmentation to be captured. The report provides a digital image-based taxonomic record of the Lake Okeechobee and the Okeechobee Waterway microscopic flora. It is anticipated that these images will facilitate current and future studies on this system, such as understanding the timing of cyanobacteria blooms and their potential toxin production.

Phytoplankton Bloom in North Sea off Scotland

NASA Technical Reports Server (NTRS)

2008-01-01

The northern and western highlands of Scotland were still winter-brown and even dusted with snow in places, but the waters of the North Sea were blooming with phytoplankton on May 8, 2008, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite passed over the region and captured this image. The tiny, plant-like organisms swirled in the waters off the country's east coast, coloring the shallow coastal waters shades of bright blue and green. Phytoplankton are tiny organisms--many are just a single cell--that use chlorophyll and other pigments to capture light for photosynthesis. Because these pigments absorb sunlight, they change the color of the light reflected from the sea surface back to the satellite. Scientists have used observations of 'ocean color' from satellites for more than 20 years to track worldwide patterns in phytoplankton blooms. Phytoplankton are important to the Earth system for a host of reasons, including their status as the base of the ocean food web. In the North Sea, they are the base of the food web that supports Scotland's commercial fisheries, including monkfish and herring. As photosynthesizers, they also play a crucial role in the carbon cycle, removing carbon dioxide from the atmosphere. Some oceanographers are concerned that rising ocean temperatures will slow phytoplankton growth rates, harming marine ecosystems and causing carbon dioxide to accumulate more rapidly in the atmosphere.

Taxocoenosis of epibenthic dinoflagellates in the coastal waters of the northern Yucatan Peninsula before and after the harmful algal bloom event in 2011-2012.

PubMed

Aguilar-Trujillo, Ana C; Okolodkov, Yuri B; Herrera-Silveira, Jorge A; Merino-Virgilio, Fany Del C; Galicia-García, Citlalli

2017-06-15

Eutrophication causes the major impact in the coastal waters of the state of Yucatan. In general, loss of water quality and biological communities and massive development of toxic microorganisms are some of the consequences of this phenomenon. To reveal changes in species composition and cell abundance of the taxocoenosis of epibenthic dinoflagellates before and after a harmful algal bloom event in the water column that lasted about 150days (August-December 2011) in the Dzilam - San Crisanto area (northern Yucatan Peninsula, southeastern Gulf of Mexico) were the main objectives of the present study. In August 2011 and September 2012, sampling along 20 transects perpendicular to the coastline along the entire northern Yucatan coast, starting from 20 sampling sites from El Cuyo in the east to Celestún in the west, at a distance of 50, 150 and 250m from the coast, was carried out. Physicochemical characteristics measured before and after the bloom were within the ranges previously reported in the study area. Salinity was the most stable characteristic, with mean values of 36.25 and 36.42 in 2011 and 2012, respectively. Phosphates were the only parameter that showed a wide range with higher values before the bloom (0.03-0.54μM/l). A total of 168 macrophyte (seaweeds and seagrasses), sponge and sediment samples (105 in 2011 and 63 in 2012) that included associated microphytobenthos were taken by snorkeling from 0.7 to 5m depth. Six substrate types were distinguished: Chlorophyta, Phaeophyceae, Rhodophyta, Angiospermae (seagrasses), Demospongiae (sponges) and sediment. Chlorophytes dominated the collected samples: 38 samples in 2011 and 23 in 2012. Avrainvillea longicaulis f. laxa predominated before the bloom and Udotea flabellum after it. In total, 25 epibenthic dinoflagellate species from 11 genera were found. The genus Prorocentrum was the most representative in terms of the number of species. The highest total dinoflagellate cell abundances were observed in the sites with different types of macrophytes (up to 2441cells/g substrate wet weight in 2011 and up to 1068cells/g in 2012). The lowest cell densities were observed in the areas with scarce or no macrophytes on sandy seafloor. Before the bloom, Prorocentrum rhathymum (up to 4995cells/g) and P. cf. sipadanensis (up to 5275cells/g) were the most abundant, and after the bloom the latter was dominant (up to 3559cells/g); in 2012, both variety of substrates and dinoflagellate cell abundance diminished. A canonical correspondence analysis revealed significant relationships between the physicochemical variables and epiphytic/benthic dinoflagellate species either before or after the bloom. The pelagic bloom resulted in the loss of substrate for epiphytic dinoflagellates, which caused replacement of the dominant species and a decrease in cell abundance of the whole taxocoenosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distribution of Alexandrium fundyense (Dinophyceae) cysts in Greenland and Iceland, with an emphasis on viability and growth in the Arctic

PubMed Central

Richlen, Mindy L.; Zielinski, Oliver; Holinde, Lars; Tillmann, Urban; Cembella, Allan; Lyu, Yihua; Anderson, Donald M.

2016-01-01

The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts to human health and economies. This study investigated the prevalence of resting cysts of A. fundyense in western Greenland and Iceland to assess the historical presence and magnitude of bloom populations in the region, and to characterize environmental conditions during summer, when bloom development may occur. Analysis of sediments collected from these locations showed that Alexandrium cysts were present at low to moderate densities in most areas surveyed, with highest densities observed in western Iceland. Additionally, laboratory experiments were conducted on clonal cultures established from isolated cysts or vegetative cells from Greenland, Iceland, and the Chukchi Sea (near Alaska) to examine the effects of photoperiod interval and irradiance levels on growth. Growth rates in response to the experimental treatments varied among isolates, but were generally highest under conditions that included both the shortest photoperiod interval (16h:8h light:dark) and higher irradiance levels (~146–366 μmol photons m−2 s−1), followed by growth under an extended photoperiod interval and low irradiance level (~37 μmol photons m−2 s−1). Based on field and laboratory data, we hypothesize that blooms in Greenland are primarily derived from advected Alexandrium populations, as low bottom temperatures and limited light availability would likely preclude in situ bloom development. In contrast, the bays and fjords in Iceland may provide more favorable habitat for germling cell survival and growth, and therefore may support indigenous, self-seeding blooms. PMID:27721528

Vertical migration of Karenia brevis in the northeastern Gulf of Mexico observed from glider measurements.

PubMed

Hu, Chuanmin; Barnes, Brian B; Qi, Lin; Lembke, Chad; English, David

2016-09-01

The toxic marine dinoflagellate, Karenia brevis (the species responsible for most of red tides or harmful algal blooms in the Gulf of Mexico), is known to be able to swim vertically to adapt to the light and nutrient environments, nearly all such observations have been made through controlled experiments using cultures. Here, using continuous 3-dimensional measurements by an ocean glider across a K. brevis bloom in the northeastern Gulf of Mexico between 1 and 8 August 2014, we show the vertical migration behavior of K. brevis. Within the bloom where K. brevis concentration is between 100,000 and 1,000,000cellsL -1 , the stratified water shows a two-layer system with the depth of pycnocline ranging between 14-20m and salinity and temperature in the surface layer being <34.8 and >28°C, respectively. The bottom layer shows the salinity of >36 and temperature of <26°C. The low salinity is apparently due to coastal runoff, as the top layer also shows high amount of colored dissolved organic matter (CDOM). Within the top layer, chlorophyll-a fluorescence shows clear diel changes in the vertical structure, an indication of K. brevis vertical migration at a mean speed of 0.5-1mh -1 . The upward migration appears to start at sunrise at a depth of 8-10m, while the downward migration appears to start at sunset (or when surface light approaches 0) at a depth of ∼2m. These vertical migrations are believed to be a result of the need of K. brevis cells for light and nutrients in a stable, stratified, and CDOM-rich environment. Copyright © 2016 Elsevier B.V. All rights reserved.

An Ephemeral Dinoflagellate Bloom during Summer Season in Nearshore Water of Puri, East Coast of India

NASA Astrophysics Data System (ADS)

Baliarsingh, Sanjiba Kumar; Dwivedi, Rashmin; Lotliker, Aneesh A.; Jayashankar, Reeta; Sahu, Biraja Kumar; Srichandan, Suchismita; Samanta, Alakes; Parida, Chandanlal; Srinivasakumar, Tummala; Sahu, Kali Charan

2018-03-01

The present paper reports on the phenomenon of pinkish-red discoloration of the nearshore water of Puri, Odisha on 12th May 2016. Many local newspapers covered this event, as Puri city is a major tourist and pilgrimage place on the east coast of India. Field observations were carried out in order to provide a scientific basis to the event and to elicit possible causes of this discoloration. Taxonomic analysis of the phytoplankton samples revealed the dominance of red colored dinoflagellate species Gonyaulax polygramma, contributing 90% to total phytoplankton population. The localized concentration of G. polygramma was responsible for the pinkish-red discoloration of nearshore water. The exact factor that lay behind the genesis of this bloom could not be delineated due to the short period of its persistence. But two factors - upwelling and anthropogenic nutrient influx - can be viewed as the main cause for this ephemeral bloom. Non-hypoxic conditions in the coastal water following the ephemeral bloom event indicated no significant risk of ecological deterioration to the ambient medium.

Seasonality and toxin production of Pyrodinium bahamense in a Red Sea lagoon.

PubMed

Banguera-Hinestroza, E; Eikrem, W; Mansour, H; Solberg, I; Cúrdia, J; Holtermann, K; Edvardsen, B; Kaartvedt, S

2016-05-01

Harmful algal blooms of the dinoflagellate Pyrodinium bahamense have caused human and economic losses in the last decades. This study, for the first time, documents a bloom of P. bahamense in the Red Sea. The alga was recurrently present in a semi-enclosed lagoon throughout nearly 2 years of observations. The highest cell densities (10 4 -10 5 cellsL -1 ) were recorded from September to beginning of December at temperatures and salinities of ∼26-32°C and ∼41, respectively. The peak of the bloom was recorded mid-November, before a sharp decrease in cell numbers at the end of December. Minimum concentrations in summer were at ∼10 3 cellsL -1 . A saxitoxin ELISA immunoassay of cultures and water samples confirmed the toxicity of the strain found in the Red Sea. Moreover, a gene expression analysis of the saxitoxin gene domain SxtA4 showed that transcript production peaked at the culmination of the bloom, suggesting a relation between transcript production, sudden cells increment-decline, and environmental factors. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of sweetener combination and storage temperature on physicochemical properties of sucrose free white chocolate.

PubMed

Rodriguez Furlán, Laura T; Baracco, Yanina; Lecot, Javier; Zaritzky, Noemi; Campderrós, Mercedes E

2017-08-15

The influence of a combination of sweeteners (Stevia (St) and sucralose (Su)) and storage temperature on thermal properties, microstructure, water content, texture and Bloom of sucrose free white chocolate was investigated. A strong relationship between the microstructure and the highest percentage of Bloom was observed. The samples with 100%Su and 50%S+50%Su presented microstructures with channels through which solids and fat could more easily spread to the surface, increasing the fat and sugar Bloom formation. However, 50%St+50%Su and 75%St+25%Su samples showed a minimum Bloom formation, probably due to its dense microstructure with no void spaces. The differential scanning calorimetry studies demonstrated that the samples containing 100%St and 75%St+25%Su showed the smallest decrease of melting enthalpy with increasing temperature. Besides, non-isothermal crystallization kinetics was studied by applying Avrami model. The sample 75%St+25%Su presented the highest values of activation energy showing the greatest stability in the temperature range studied (7°C-30°C). Copyright © 2017 Elsevier Ltd. All rights reserved.

Unveiling the transcriptional features associated with coccolithovirus infection of natural Emiliania huxleyi blooms.

PubMed

Pagarete, António; Le Corguillé, Gildas; Tiwari, Bela; Ogata, Hiroyuki; de Vargas, Colomban; Wilson, William H; Allen, Michael J

2011-12-01

Lytic viruses have been implicated in the massive cellular lysis observed during algal blooms, through which they assume a prominent role in oceanic carbon and nutrient flows. Despite their impact on biogeochemical cycling, the transcriptional dynamics of these important oceanic events is still poorly understood. Here, we employ an oligonucleotide microarray to monitor host (Emiliania huxleyi) and virus (coccolithovirus) transcriptomic features during the course of E. huxleyi blooms induced in seawater-based mesocosm enclosures. Host bloom development and subsequent coccolithovirus infection was associated with a major shift in transcriptional profile. In addition to the expected metabolic requirements typically associated with viral infection (amino acid and nucleotide metabolism, as well as transcription- and replication-associated functions), the results strongly suggest that the manipulation of lipid metabolism plays a fundamental role during host-virus interaction. The results herein reveal the scale, so far massively underestimated, of the transcriptional domination that occurs during coccolithovirus infection in the natural environment. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Associations between water physicochemistry and Prymnesium parvum presence, abundance, and toxicity in west Texas reservoirs

USGS Publications Warehouse

VanLandeghem, Matthew M.; Farooqi, Mukhtar; Southard, Greg M.; Patino, Reynaldo

2015-01-01

Toxic blooms of golden alga (Prymnesium parvum) have caused substantial ecological and economic harm in freshwater and marine systems throughout the world. In North America, toxic blooms have impacted freshwater systems including large reservoirs. Management of water chemistry is one proposed option for golden alga control in these systems. The main objective of this study was to assess physicochemical characteristics of water that influence golden alga presence, abundance, and toxicity in the Upper Colorado River basin (UCR) in Texas. The UCR contains reservoirs that have experienced repeated blooms and other reservoirs where golden alga is present but has not been toxic. We quantified golden alga abundance (hemocytometer counts), ichthyotoxicity (bioassay), and water chemistry (surface grab samples) at three impacted reservoirs on the Colorado River; two reference reservoirs on the Concho River; and three sites at the confluence of these rivers. Sampling occurred monthly from January 2010 to July 2011. Impacted sites were characterized by higher specific conductance, calcium and magnesium hardness, and fluoride than reference and confluence sites. At impacted sites, golden alga abundance and toxicity were positively associated with salinity-related variables and blooms peaked at ~10°C and generally did not occur above 20°C. Overall, these findings suggest management of land and water use to reduce hardness or salinity could produce unfavorable conditions for golden alga.

Satellite detection of phytoplankton export from the mid-Atlantic Bight during the 1979 spring bloom

NASA Technical Reports Server (NTRS)

Walsh, J. J.; Dieterle, D. A.; Esaias, W. E.

1986-01-01

Analysis of Coastal Zone Color Scanner (CZCS) imagery confirms shipboard and in situ moored fluorometer observations of resuspension of near-bottom chlorophyll within surface waters (1 to 10 m) by northwesterly wind events in the mid-Atlantic Bight. As much as 8 to 16 micrograms chl/l are found during these wind events from March to May, with a seasonal increase of algal biomass until onset of stratification of the water column. Rapid sinking or downwelling apparently occurs after subsequent wind events, however, such that the predominant surface chlorophyll pattern is approx. 0.5 to 1.5 micrograms/l over the continental shelf during most of the spring bloom. Perhaps half of the chlorophyll increase observed by satellite during a wind resuspension event represents in-situ production during the 4 to 5 day interval, with the remainder attributed to accumulation of algal biomass previously produced and temporarily stored within near-bottom water. Present calculations suggest that about 10% of the primary production of the spring bloom may be exported as ungrazed phytoplankton carbon from mid-Atlantic shelf waters to those of the continental slope.

Episodic subsurface injections in the oligotrophic North Pacific observed from BioArgo

NASA Astrophysics Data System (ADS)

Wilson, C.

2016-12-01

Summer blooms of chlorophyll often develop in the oligotrophic North Pacific Ocean in the region between Hawaii and 30°N. Episodic injections of subsurface nutrients have been hypothesized to fuel these blooms, but the exact mechanism is unknown. Here we examine oxygen data from 13 BioArgo floats deployed near Hawaii between September 2002 to April 2016 to look for evidence of subsurface mixing that could be driving the development of the surface chlorophyll features. Twelve injection events (defined as oxygen values < 2 standard deviations below the mean at 100 m depth) were observed. Nine (75%) of the events happened in winter (Dec-Mar), when surface chl blooms do not generally develop. While most of the events were short-lived (< 5 days), several events lasted a month or two. An event that began in August 2014, and lasted almost 2 months, is examined in detail. The start of the event preceded by a few days the development of a surface increase in chlorophyll in the surrounding area evident from satellite data.

Seasonal resource conditions favor a summertime increase in North Pacific diatom-diazotroph associations.

PubMed

Follett, Christopher L; Dutkiewicz, Stephanie; Karl, David M; Inomura, Keisuke; Follows, Michael J

2018-06-01

In the North Pacific Subtropical Gyre (NPSG), an annual pulse of sinking organic carbon is observed at 4000 m between July and August, driven by large diatoms found in association with nitrogen fixing, heterocystous, cyanobacteria: Diatom-Diazotroph Associations (DDAs). Here we ask what drives the bloom of DDAs and present a simplified trait-based model of subtropical phototroph populations driven by observed, monthly averaged, environmental characteristics. The ratio of resource supply rates favors nitrogen fixation year round. The relative fitness of DDA traits is most competitive in early summer when the mixed layer is shallow, solar irradiance is high, and phosphorus and iron are relatively abundant. Later in the season, as light intensity drops and phosphorus is depleted, the traits of small unicellular diazotrophs become more competitive. The competitive transition happens in August, at the time when the DDA export event occurs. This seasonal dynamic is maintained when embedded in a more complex, global-scale, ecological model, and provides predictions for the extent of the North Pacific DDA bloom. The model provides a parsimonious and testable hypothesis for the stimulation of DDA blooms.

The distribution and life cycle of the dinoflagellate Spatulodinium pseudonoctiluca (Dinophyceae, Noctilucales) in the northeastern English Channel.

PubMed

Gómez, Fernando; Souissi, Sami

2007-03-01

The distribution of Spatulodinium (= Gymnodinium) pseudonoctiluca (Pouchet) J. Cachon & M. Cachon has been investigated for eight years (1998-2005) in the northeastern English Channel, type locality of the species and its immature stages. The species can be found after the spring diatom bloom from late May to October. The highest abundance was found in June 2004 after the Phaeocystis bloom. Exceptionally, the Phaeocystis bloom was absent in 2005 and only several specimens of S. pseudonoctiluca were observed. The immature and mature stages of Spatulodinium nearly always co-occurred. No other kofoidiniaceans such as Kofoidinium or Pomatodinium were observed. The first stages of the development of Spatulodinium can easily confuse with gymnodiniaceans. The transformation of the stage 'D', which has been described as Gymnodinium lebouriae (= G. fulgens) or Gymnodinium conicum (= G. viridis), into the mature stage, is illustrated. The stage 'D' originates from a cluster of pairs of smaller cells joined by an elongate episome. In the boreal Atlantic Ocean, Spatulodinium pseudonoctiluca, a single species whose life stages are often reported as separate species, is especially adapted to a strongly fluctuant environment.

Bioavailability of mineral-bound iron to a snow algae-bacteria co-culture and implications for albedo-altering snow algae blooms.

PubMed

Harrold, Z R; Hausrath, E M; Garcia, A H; Murray, A E; Tschauner, O; Raymond, J; Huang, S

2018-01-26

Snow algae can form large-scale blooms across the snowpack surface and near-surface environments. These pigmented blooms can decrease snow albedo, increase local melt rates, and may impact the global heat budget and water cycle. Yet, underlying causes for the geospatial occurrence of these blooms remain unconstrained. One possible factor contributing to snow algae blooms is the presence of mineral dust as a micronutrient source. We investigated the bioavailability of iron (Fe) -bearing minerals, including forsterite (Fo 90 , Mg 1.8 Fe 0.2 SiO 4 ), goethite, smectite and pyrite as Fe sources for a Chloromonas brevispina - bacteria co-culture through laboratory-based experimentation. Fo 90 was capable of stimulating snow algal growth and increased the algal growth rate in otherwise Fe-depleted co-cultures. Fo 90 -bearing systems also exhibited a decrease in bacteria:algae ratios compared to Fe-depleted conditions, suggesting a shift in microbial community structure. The C. brevispina co-culture also increased the rate of Fo 90 dissolution relative to an abiotic control. Analysis of 16S rRNA genes in the co-culture identified Gammaproteobacteria , Betaprotoeobacteria and Sphingobacteria , all of which are commonly found in snow and ice environments. Archaea were not detected. Collimonas and Pseudomonas , which are known to enhance mineral weathering rates, comprised two of the top eight (> 1 %) OTUs. These data provide unequivocal evidence that mineral dust can support elevated snow algae growth under otherwise Fe-depleted growth conditions, and that snow algae can enhance mineral dissolution under these conditions. IMPORTANCE Fe, a key micronutrient for photosynthetic growth, is necessary to support the formation of high-density snow algae blooms. The laboratory experiments described herein allow for a systematic investigation of snow algae-bacteria-mineral interactions and their ability to mobilize and uptake mineral-bound Fe. Results provide unequivocal and comprehensive evidence that mineral-bound Fe in Fe-bearing Fo 90 was bioavailable to Chloromonas brevispina snow algae within an algae-bacteria co-culture. This evidence includes: 1) an observed increase snow algae density and growth rate; 2) decreased bacteria:algae ratios in Fo 90 -containing cultures relative to cultures grown under similarly Fe-depleted conditions with no mineral-bound Fe present; and 3) increased Fo 90 dissolution rates in the presence of algae-bacteria co-cultures relative to abiotic mineral controls. These results have important implications for the role of mineral dust in supplying micronutrients to the snow microbiome, which may help support dense snow algae blooms capable of lowering snow albedo, and increase snow melt rates on regional, and possibly global, scales. Copyright © 2018 American Society for Microbiology.

Seasonal variability of living benthic foraminifera from the outer continental shelf of the Bay of Biscay

NASA Astrophysics Data System (ADS)

Duchemin, Gérald; Jorissen, Frans J.; Le Loc'h, François; Andrieux-Loyer, Françoise; Hily, Christian; Thouzeau, Gérard

2008-08-01

Living benthic foraminiferal faunas of six stations from the continental shelf of the Bay of Biscay have been investigated during three successive seasons (spring, summer and autumn 2002). For the three investigated stations, bottom water oxygen concentration, oxygen penetration into the sediment and sediment organic carbon contents are all relatively similar. Therefore, we think that the density and the composition of the foraminiferal faunas is mainly controlled by the quantity and quality of organic input resulting from a succession of phytoplankton bloom events, occurring from late February to early September. The earliest blooms are positioned at the shelf break, late spring and early summer blooms occur off Brittany, whereas in late summer and early autumn, only coastal blooms appear, often in the vicinity of river outlets. In spring, the benthic foraminiferal faunas of central (B, C and D) and outer (E) continental shelf stations are characterised by strong dominance in the first area and strong presence in the second area of Nonionella iridea. In fact, station E does not serve as a major depocenter for the remains of phytoplankton blooms. If station E is not considered, the densities of this taxon show a clear gradient from the shelf-break, where the species dominates the assemblages, to the coast, where it attains very low densities. We explain this gradient as a response to the presence, in early spring, of an important phytoplankton bloom, mainly composed of coccolithophorids, over the shelf break. This observation is supported by the maximum particles flux values at stations close to the shelf break (18.5 g m - 2 h - 1 ) and lower values in a station closer to the coast (6.8 g m - 2 h - 1 ). In summer, the faunal density is maximum at station A, relatively close to more varied phytoplancton blooms that occur off Brittany until early June. We suggest that the dominant species, Nonion fabum, Cassidulina carinata and Bolivina ex. gr. dilatata respond to phytodetritus input from these blooms. In autumn, the rich faunas of inner shelf station G are dominated by N. fabum, B. ex. gr. dilatata, Hyalinea balthica and Nonionella turgida. These taxa seem to be correlated with the presence of coastal blooms phenomena, in front of river outlets. They may be favoured by an organic input with a significant contribution of terrestrial, rather low quality organic matter.

Retrospective analysis of associations between water quality and toxic blooms of golden alga (Prymnesium parvum) in Texas reservoirs: Implications for understanding dispersal mechanisms and impacts of climate change

USGS Publications Warehouse

Patino, Reynaldo; Dawson, D.; VanLandeghem, Matthew M.

2014-01-01

Toxic blooms of golden alga (GA, Prymnesium parvum) in Texas typically occur in winter or early spring. In North America, they were first reported in Texas in the 1980s, and a marked range expansion occurred in 2001. Although there is concern about the influence of climate change on the future distribution of GA, factors responsible for past dispersals remain uncertain. To better understand the factors that influence toxic bloom dispersal in reservoirs, this study characterized reservoir water quality associated with toxic GA blooms since 2001, and examined trends in water quality during a 20-year period bracketing the 2001 expansion. Archived data were analyzed for six impacted and six nonimpacted reservoirs from two major Texas basins: Brazos River and Colorado River. Data were simplified for analysis by pooling spatially (across sampling stations) and temporally (winter, December-February) within reservoirs and generating depth-corrected (1 m) monthly values. Classification tree analysis [period of record (POR), 2001-2010] using salinity-associated variables (specific conductance, chloride, sulfate), dissolved oxygen (DO), pH, temperature, total hardness, potassium, nitrate+nitrite, and total phosphorus indicated that salinity best predicts the toxic bloom occurrence. Minimum estimated salinities for toxic bloom formation were 0.59 and 1.02 psu in Brazos and Colorado River reservoirs, respectively. Principal component analysis (POR, 2001-2010) indicated that GA habitat is best defined by higher salinity relative to nonimpacted reservoirs, with winter DO and pH also being slightly higher and winter temperature slightly lower in impacted reservoirs. Trend analysis, however, did not reveal monotonic changes in winter water quality of GA-impacted reservoirs during the 20-year period (1991-2010) bracketing the 2001 dispersal. Therefore, whereas minimum levels of salinity are required for GA establishment and toxic blooms in Texas reservoirs, the lack of trends in water quality suggests that conditions favorable for toxic blooms pre-date the 2001 expansion. These observations are consistent with a climate change-independent scenario of past GA dispersals in Texas reservoirs driven by novel introductions into pre-existing favorable habitat. Reports of latent GA populations in certain nonimpacted reservoirs, however, provide a plausible scenario of future dispersals characterized by prolonged periods between colonization and toxic bloom development and driven by changes in water quality, natural, or anthropogenic.

Complex Synchronization Phenomena in Ecological Systems

NASA Astrophysics Data System (ADS)

Stone, Lewi; Olinky, Ronen; Blasius, Bernd; Huppert, Amit; Cazelles, Bernard

2002-07-01

Ecological and biological systems provide us with many striking examples of synchronization phenomena. Here we discuss a number of intriguing cases and attempt to explain them taking advantage of a modelling framework. One main focus will concern synchronized ecological end epidemiological cycles which have Uniform Phase growth associated with their regular recurrence, and Chaotic Amplitudes - a feature we term UPCA. Examples come from different areas and include decadal cycles of small mammals, recurrent viral epidemics such as childhood infections (eg., measles), and seasonally driven phytoplankton blooms observed in lakes and the oceans. A more detailed theoretical analysis of seasonally synchronized chaotic population cycles is presented.

Enhancement of thermal blooming effect on free space propagation of high power CW laser beam

NASA Astrophysics Data System (ADS)

Kashef, Tamer M.; Mokhtar, Ayman M.; Ghoniemy, Samy A.

2018-02-01

In this paper, we present an enhanced model to predict the effect of thermal blooming and atmospheric turbulence, on high energy laser beams free space propagation. We introduce an implementation technique for the proposed mathematical models describing the effect of thermal blooming and atmospheric turbulence including wind blowing, and how it effect high power laser beam power, far field pattern, phase change effect and beam quality . An investigated model of adaptive optics was introduced to study how to improve the wave front and phase distortion caused by thermal blooming and atmospheric turbulence, the adaptive optics model with Actuator influence spacing 3 cm the that shows observed improvement in the Strehl ratio and in wave front and phase of the beam. These models was implemented using cooperative agents relying on GLAD software package. Without taking in consideration the effect of thermal blooming It was deduced that the beam at the source takes the Gaussian shape with uniform intensity distribution, we found that the beam converge on the required distance 4 km using converging optics, comparing to the laser beam under the effect of thermal blooming the far field pattern shows characteristic secondary blip and "sugar scoop" effect which is characteristic of thermal blooming. It was found that the thermal blooming causes the beam to steer many centimeters and to diverge beyond about 1.8 km than come to a focus at 4 km where the beam assumed to be focused on the required target. We assume that this target is moving at v = (4,-4) m/sec at distance 4 km and the wind is moving at v = (-10,-10) m/sec, it was found that the effect will be strongest when wind and target movement are at the same velocity. GLAD software is used to calculate the attenuation effects of the atmosphere as well as the phase perturbations due to temperature change in the air and effects caused as the beam crosses through the air due to wind and beam steering.

Exploration of the link between Emiliania huxleyi bloom dynamics and aerosol fluxes to the lower Atmosphere

NASA Astrophysics Data System (ADS)

Trainic, M.

2013-12-01

Phytoplankton blooms are responsible for about 50% of the global photosynthesis, thus are a key component of the major nutrient cycles in the ocean. These blooms can be a significant source for flux of volatiles and aerosols, affecting physical chemical processes in the atmosphere. One of the most widely distributed and abundant phytoplankton species in the oceans is the coccolithophore Emiliania huxleyi. In this research, we explore the influence of the different stages of E. huxleyi bloom on the emission of primary aerosols. For this purpose, we conducted a series of controlled lab experiments to measure aerosol emissions during the growth of E. huxleyi. The cultures were grown in a specially designed growth chamber, and the aerosols were generated in a bubbling system. We collected the emitted aerosol particles on filters, and conducted a series of analysis. Scanning electron microscopy (SEM) analysis of the aerosols emitted from E.huxleyi 1216 cultures demonstrate emission of CaCO3 platelets from their exoskeleton into the air, while coccolithophores cells were absent. The results suggest that while healthy coccolithophore cells are too heavy to aerosolize, during cell lysis the coccoliths shed from the coccolithophore cells are emitted into the atmosphere. Therefore, aerosol production during bloom demise may be greater than from healthy E.huxleyi populations. We also investigated the size distribution of the aerosols at various stages of E. huxleyi growth. The presence of calcified cells greatly effects the size distribution of the emitted aerosol population. This work motivated us to explore aerosols emitted during E. huxleyi spring bloom, in a laboratory we constructed onboard the R/V Knorr research vessel, as part of the North Atlantic Virus Infection of Coccolithophore Expedition (June-July 2012). These results have far-reaching implications on the effect of E. huxleyi bloom dynamics on aerosol properties. We not only show that the E. huxleyi calcite shells are emitted as aerosols, but also that aerosol type and therefore chemical composition, microphysical and optical properties depend on the stage of the bloom growth. Unraveling the atmospheric signature of algal bloom dynamics in the ocean will provide novel insights into its ecological and climatic roles.

Toxic Alexandrium blooms in the western Gulf of Maine: The plume advection hypothesis revisited

USGS Publications Warehouse

Anderson, D.M.; Keafer, B.A.; Geyer, W.R.; Signell, R.P.; Loder, T.C.

2005-01-01

The plume advection hypothesis links blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine (GOM) to a buoyant plume derived from river outflows. This hypothesis was examined with cruise and moored-instrument observations in 1993 when levels of paralytic shellfish poisoning (PSP) toxins were high, and in 1994 when toxicity was low. A coupled physical-biological model simulated hydrography and A. fundyense distributions. Initial A. fundyense populations were restricted to low-salinity nearshore waters near Casco Bay, but also occurred in higher salinity waters along the plume boundary. This suggests two sources of cells - those from shallow-water cyst populations and those transported to shore from offshore blooms in the eastern segment of the Maine coastal current (EMCC). Observations confirm the role of the plume in A. fundyense transport and growth. Downwelling-favorable winds in 1993 transported the plume and its cells rapidly alongshore, enhancing toxicity and propagating PSP to the south. In 1994, sustained upwelling moved the plume offshore, resulting in low toxicity in intertidal shellfish. A. fundyense blooms were likely nutrient limited, leading to low growth rates and moderate cell abundances. These observations and mechanisms were reproduced by coupled physical-biological model simulations. The plume advection hypothesis provides a viable explanation for outbreaks of PSP in the western GOM, but should be refined to include two sources for cells that populate the plume and two major pathways for transport: one within the low-salinity plume and another where A. fundyense cells originating in the EMCC are transported along the outer boundary of the plume front with the western segment of the Maine coastal current.

Lack of nitrogen as a causing agent of Cylindrospermopsis raciborskii intermittent blooms in a small tropical reservoir.

PubMed

Figueredo, Cleber C; von Rückert, Gabriela; Cupertino, Arthur; Pontes, Marília A; Fernandes, Luyara A; Ribeiro, Solange G; Maran, Natália R C

2014-03-01

Cylindrospermopsis raciborskii is the focus of many studies due to its toxicity and increasing blooms frequency. The comprehension of the factors that might trigger these blooms is fundamental for the maintenance of good freshwater quality. To better understand the autoecology of C. raciborskii and to identify the factors controlling its dominance, general limnological features were evaluated in Pedalinhos reservoir, Brazil. Samplings were performed monthly between 2011 and 2013. Although C. raciborskii is considered a relatively perennial species in the tropics, it presented an interesting nonunimodal variation, with biovolume varying from 0 to c. 30 mm³ L⁻¹ in short time intervals (< 30 days). These temporal trends allowed the evaluation of the isolated effects of nonclimatic variables. Cylindrospermopsis raciborskii was connected with several variables, but nitrogen was the major determinant of its dynamics. Blooms were observed when dissolved inorganic nitrogen (DIN) was scarce (< 50 μg L⁻¹), mainly in relation to the availability of phosphorus and total-N (DIN : total-P < 3 and DIN : total-N < 0.04). This paper contributes to establish strategies to avoid C. raciborskii blooms, suggesting that a management in P levels would be not sufficient. It is necessary to consider N availability to avoid its dominance in the reservoir. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Influence of the Phytoplankton Community Structure on the Spring and Annual Primary Production in the Northwestern Mediterranean Sea

NASA Astrophysics Data System (ADS)

Mayot, Nicolas; D'Ortenzio, Fabrizio; Uitz, Julia; Gentili, Bernard; Ras, Joséphine; Vellucci, Vincenzo; Golbol, Melek; Antoine, David; Claustre, Hervé

2017-12-01

Satellite ocean color observations revealed that unusually deep convection events in 2005, 2006, 2010, and 2013 led to an increased phytoplankton biomass during the spring bloom over a large area of the northwestern Mediterranean Sea (NWM). Here we investigate the effects of these events on the seasonal phytoplankton community structure, we quantify their influence on primary production, and we discuss the potential biogeochemical impact. For this purpose, we compiled in situ phytoplankton pigment data from five ship surveys performed in the NWM and from monthly cruises at a fixed station in the Ligurian Sea. We derived primary production rates from a light photosynthesis model applied to these in situ data. Our results confirm that the maximum phytoplankton biomass during the spring bloom is larger in years associated with intense deep convection events (+51%). During these enhanced spring blooms, the contribution of diatoms to total phytoplankton biomass increased (+33%), as well as the primary production rate (+115%). The occurrence of a highly productive bloom is also related to an increase in the phytoplankton bloom area (+155%) and in the relative contribution of diatoms to primary production (+63%). Therefore, assuming that deep convection in the NWM could be significantly weakened by future climate changes, substantial decreases in the spring production of organic carbon and of its export to deep waters can be expected.

Effects of Fat Polymorphic Transformation and Nonfat Particle Size Distribution on the Surface Changes of Untempered Model Chocolate, Based on Solid Cocoa Mass.

PubMed

Zhao, Huanhuan; Young, Ashley K; James, Bryony J

2018-04-01

This study aims to understand the bloom process in untempered chocolate by investigating the polymorphic transformation of cocoa butter and changes in chocolate surface. Cocoa mass with varying particle size distributions (PSD) were used to produce untempered model chocolate. Optical microscopy showed that during 25 d of storage, the chocolate surface gradually became honeycombed in appearance with dark spots surrounded by white sandy bloom areas. In conjunction with X-ray diffraction this indicates that the polymorphic transformation of form IV cocoa butter to more stable form V crystals caused the observed surface changes with the most significant changes occurring within 6 d. As bloom developed the surface whiteness increased, but the PSD of nonfat particles showed limited impact on the changes in whiteness. Moreover, scanning electron microscopy showed separated fat crystals on fat-rich dark spots and empty spaces between particles in bloom areas suggesting redistribution of fat in the chocolate matrix. The results reported in this work can facilitate the understanding of fat bloom formation in untempered chocolate with respect to the changes in microstructure and surface appearances. It also contributes to show the details of IV-to-V polymorphic transformation in the fat phase as time went by. © 2018 Institute of Food Technologists®.

Characteristics of picoplankton abundances during a Thalassiosira diporocyclus bloom in the Taiwan Bank in late winter.

PubMed

Jiang, Xin; Li, Jiajun; Ke, Zhixin; Xiang, Chenhui; Tan, Yehui; Huang, Liangmin

2017-04-15

To understand the variations of picoplankton (Prochlorococcus, Synechococcus, picoeukaryotes, and heterotrophic bacteria) abundances during diatom bloom, the distribution of picoplankton in the Taiwan Bank, South China Sea was investigated using flow cytometry during a Thalassiosira diporocyclus bloom in March 2016. The results indicated an abrupt abundance decrease for Prochlorococcus, Synechococcus, and picoeukaryotes within the bloom area while the abundance of heterotrophic bacteria showed no significant difference between the bloom and non-bloom areas. We found two sub-groups of heterotrophic bacteria: high- and low-nucleic acid content (HNA and LNA) bacteria with HNA dominated in the bloom area whereas LNA dominated in the non-bloom area. Among the picoplankton components, HNA represented the highest (61.1%) carbon biomass in the bloom area while picoeukaryotes represented the highest (37.6%) in the non-bloom area. Our findings implied that heterotrophic bacteria, especially HNA, played an essential role during the diatom bloom. Copyright © 2017 Elsevier Ltd. All rights reserved.

A novel single-parameter approach for forecasting algal blooms.

PubMed

Xiao, Xi; He, Junyu; Huang, Haomin; Miller, Todd R; Christakos, George; Reichwaldt, Elke S; Ghadouani, Anas; Lin, Shengpan; Xu, Xinhua; Shi, Jiyan

2017-01-01

Harmful algal blooms frequently occur globally, and forecasting could constitute an essential proactive strategy for bloom control. To decrease the cost of aquatic environmental monitoring and increase the accuracy of bloom forecasting, a novel single-parameter approach combining wavelet analysis with artificial neural networks (WNN) was developed and verified based on daily online monitoring datasets of algal density in the Siling Reservoir, China and Lake Winnebago, U.S.A. Firstly, a detailed modeling process was illustrated using the forecasting of cyanobacterial cell density in the Chinese reservoir as an example. Three WNN models occupying various prediction time intervals were optimized through model training using an early stopped training approach. All models performed well in fitting historical data and predicting the dynamics of cyanobacterial cell density, with the best model predicting cyanobacteria density one-day ahead (r = 0.986 and mean absolute error = 0.103 × 10 4  cells mL -1 ). Secondly, the potential of this novel approach was further confirmed by the precise predictions of algal biomass dynamics measured as chl a in both study sites, demonstrating its high performance in forecasting algal blooms, including cyanobacteria as well as other blooming species. Thirdly, the WNN model was compared to current algal forecasting methods (i.e. artificial neural networks, autoregressive integrated moving average model), and was found to be more accurate. In addition, the application of this novel single-parameter approach is cost effective as it requires only a buoy-mounted fluorescent probe, which is merely a fraction (∼15%) of the cost of a typical auto-monitoring system. As such, the newly developed approach presents a promising and cost-effective tool for the future prediction and management of harmful algal blooms. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bio-optic characterization of Discosphaera tubifer bloom occurs in an overcrowded fishing harbour at Veraval, India.

PubMed

Mandal, Subir Kumar; Patel, Vipul R; Temkar, Ganesh; George, Basil M; Raman, Mini

2015-09-01

Discosphaera tubifer, a coccolithophore has been first time reported as a bloom-forming organism from an over-crowded fishing harbour at Veraval, west coast of India. Physiochemical and optical parameters were measured following standard protocols. Average concentration of inorganic nutrients, such as NO2-N (17.26 ± 2.92 μM), NO3-N (643.80 ± 215.99 μM), PO4-P (74.10 ± 26.52 μM) and SiO3-Si (137.66 ± 25.83 μM) were recorded as very high at Veraval port as compared to other coastal stations i.e., 1.48 ± 0.66, 49.16 ± 13.73, 10.03 ± 5.31 and 96.23 ± 22.74 μM, respectively. The pH and salinity (‰) were observed to be low (7.80 ± 0.15 and 28.00 ± 4.54 ‰) as compared to coastal seawaters (8.34 ± 0.06 and 33.24 ± 2.32 ‰). Scanning electron microscopy (SEM) and spectral signature (absorbance and reflectance) study revealed that the bloom-forming organism was D. tubifer. High-performance liquid chromatography (HPLC) study detected that chlorophyllide-a represent nearly 47.53 % of total pigment composition followed by chlorophyll c2 (27.40 %) and chlorophyll c3 (14.25 %). Four prominent absorption peaks were observed within 350 to 700 nm. The first peak was very wide and ranged from 350 to 530 nm and the rest of the three peaks ranged from 550 to 590, 590 to 650 and 650 to 690 nm, respectively. In case of reflection, three peaks appeared between 550 and 590, 590 and 630 and 630 and 670 nm. Nearly 100 % reflection was observed after 720 nm. The eutrophic condition of the port water along with low salinity and low pH might be the reason for D. tubifer bloom formation. This species-specific spectral signature of the D. tubifer bloom may be helpful for developing algorithm of remote sensing data analysis.

Harmful freshwater algal blooms, with an emphasis on cyanobacteria.

PubMed

Paerl, H W; Fulton, R S; Moisander, P H; Dyble, J

2001-04-04

Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia), toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human) health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria) are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis) and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria) that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia) are capable of fixing atmospheric nitrogen (N2), enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from zooplankton to further up the food chain. Both N2- and non-N2-fixing genera participate in mutualistic and symbiotic associations with microorganisms, higher plants, and animals. These associations appear to be of great benefit to their survival and periodic dominance. In this review, we address the ecological impacts and environmental controls of harmful blooms, with an emphasis on the ecology, physiology, and management of cyanobacterial bloom taxa. Combinations of physical, chemical, and biotic features of natural waters function in a synergistic fashion to determine the sensitivity of water bodies. In waters susceptible to blooms, human activities in water- and airsheds have been linked to the extent and magnitudes of blooms. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on nitrogen (N) and/or phosphorus (P). The types and amount of nutrient input constraints depend on hydrologic, climatic, geographic, and geologic factors, which interact with anthropogenic and natural nutrient input regimes. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long-term control and management of harmful blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by enhanced flushing and artificial mixing (in conjunction with nutrient input constraints) can be particularly effective alternatives. Implications of various management strategies, based on combined ecophysiological and environmental considerations, are discussed.

Granger Test to Determine Causes of Harmful algal Blooms in TaiLake during the Last Decade

NASA Astrophysics Data System (ADS)

Guo, W.; Wu, F.

2016-12-01

Eutrophication-driven harmful cyanobacteria blooms can threaten stability of lake ecosystems. A key to solving this problem is identifying the main cause of algal blooms so that appropriate remediation can be employed. A test of causality was used to analyze data for Meiling Bay in Tai Lake (Ch: Taihu) from 2000 to 2012. After filtration of data by use of the stationary test and the co-integration test, the Granger causality test and impulse response analysis were used to analyze potential bloom causes from physicochemical parameters to chlorophyll-a concentration. Results of stationary tests showed that logarithms of secchi disk depth (lnSD), suspended solids (lnSS), lnNH4-N/NOx-N and pH were determined to be stationary as a function of time and could not be considered to be causal for changes in biomass of phytoplankton observed during that period. Results of co-integration tests indicated existence of long-run co-integrating relationships among natural logarithms of chlorophyll-a (lnChl-a), water temperature (lnWT), total organic carbon (lnTOC) and ratio of nitrogen to phosphorus (lnN/P). The Granger causality test suggested that once thresholds for nutrients such as nitrogen and phosphorus had been reached, WT could increase the likelihood or severities of cyanobacteria blooms. An unidirectional Granger relationship from N/P to Chl-a was established, the result indicated that because concentrations of TN in Meiliang Bay had reached their thresholds, it no longer limited proliferation of cyanobacteria and TP should be controlled to reduce the likelihood of algae blooms. The impulse response analysis implied that lagging effects of water temperature and N/P ratio could influence the variation of Chla concentration at certain lag periods. The results can advance understanding of mechanisms on formation of harmful cyanobacteria blooms.

Using in-situ Glider Data to Improve the Interpretation of Time-Series Data in the San Pedro Channel

NASA Astrophysics Data System (ADS)

Teel, E.; Liu, X.; Seegers, B. N.; Ragan, M. A.; Jones, B. H.; Levine, N. M.

2016-02-01

Oceanic time-series have provided insight into biological, physical, and chemical processes and how these processes change over time. However, time-series data collected near coastal zones have not been used as broadly because of regional features that may prevent extrapolation of local results. Though these sites are inherently more affected by local processes, broadening the application of coastal data is crucial for improved modeling of processes such as total carbon drawdown and the development of oxygen minimum zones. Slocum gliders were deployed off the coast of Los Angeles from February to July of 2013 and 2014 providing high temporal and spatial resolution data of the San Pedro Channel (SPC), which includes the San Pedro Ocean Time Series (SPOT). The data were collapsed onto a standardized grid and primary and secondary characteristics of glider profiles were analyzed by principal component analysis to determine the processes impacting SPC and SPOT. The data fell into four categories: active upwelling, offshore intrusion, subsurface bloom, and surface bloom. Waters across the SPC were most similar to offshore water masses, even during the upwelling season when near-shore blooms are commonly observed. The SPOT site was found to be representative of the SPC 86% of the time, suggesting that the findings from SPOT are applicable for the entire SPC. Subsurface blooms were common in both years with co-located chlorophyll and particle maxima, and results suggested that these subsurface blooms contribute significantly to the local primary production. Satellite estimation of integrated chlorophyll was poor, possibly due to the prevalence of subsurface blooms and shallow optical depths during surface blooms. These results indicate that high resolution in-situ glider deployments can be used to determine the spatial domain of coastal time-series data, allowing for broader application of these datasets and greater integration into modeling efforts.

Co-occurrence of non-toxic (cyanopeptolin) and toxic (microcystin) peptides in a bloom of Microcystis sp. from a Chilean lake.

PubMed

Neumann, U; Campos, V; Cantarero, S; Urrutia, H; Heinze, R; Weckesser, J; Erhard, M

2000-06-01

A cyanobacterial bloom occurring in 1998 in lake Tres Pascualas (Concepción/Chile) was found to be dominated by Microcystis sp. The bloom contained both non-toxic (cyanopeptolin-type) and hepatotoxic (microcystin-type) peptides. Cyanopeptolin structure of the non-toxic peptides (called cyanopeptolin VW-1 and VW-2, respectively) was revealed by matrix assisted laser desorption ionization mass spectrometry (MALDI-TOF-MS) of whole cells, showing dominant molecular ions at m/z = 975 and m/z 995, respectively. On post source decay (PSD), both cyanopeptolins showed fragments deriving from Ahp-Phe-MTyr (3-amino-6-hydroxy-2-piperidone), the characteristic partial structure of cyanopeptolins. The amounts of each of the two cyanopeptolins could only roughly be estimated to be >0.1% of bloom material dry weight. In addition the blooms contained microcystins (20 microg/g bloom dry weight as determined by RP-HPLC, 13 microg/g according to ELISA determination). MALDI-TOF-MS revealed several structural variants of microcystin: MCYST-RR (microcystin with Arg and Arg, indicated by m/z 1,038 and confirmed by PSD revealing a m/z = 135 fragment deriving from the Adda side chain, MCYST-FR (microcystin with Phe and Arg, indicated by m/z = 1,015). The presence of [Asp(3)]-MCYST-LR (microcystin with Leu and Arg, Asp non-methylated, indicated by m/z 981), and [Asp(3)]-MCYST-YR (microcystin with Tyr and Arg, Asp non-methylated, indicated by m/z 1,031) were likely. The relative amounts of the peptides varied between February, April, and May. Whole cell extracts from the bloom material revealed specific enzyme inhibitory activities. The serin-proteases trypsin, plasmin, elastase were inhibited, assumable due to the cyanopeptolins found. Elastase and the cysteine-protease papain were not inhibited, inhibitions of protein kinase and glutathione S-transferase (GST) were low. Strong inhibition was observed with protein-phosphatase-1, likely due to the microcystins present in the samples.

From MERIS To OLCI And Sentinel 2: Harmful Algal Bloom Applications & Modelling In South Africa

NASA Astrophysics Data System (ADS)

Robertson Lain, L.; Bernard, S.; Evers-King, H.; Matthews, M. W.; Smith, M.

2013-12-01

The Sentinel 2 and 3 missions offer new capabilities for Harmful Algal Bloom (HAB) observations in Southern Africa and further afield on the African continent where there is a great need for improved monitoring of water quality: both in freshwater resources where eutrophication is common, and in vulnerable coastal ecosystems. Two well validated algorithms - Equivalent Algal Populations (EAP) & Maximum Peak Height (MPH) - available for operational use on eutrophic waters are described. Spectral remote sensing reflectances (Rrs) and inherent optical properties (IOPs) are characterised via measurement and modelling of phytoplankton assemblages typical of high biomass algal blooms of the Southern Benguela and inland waters of South Africa. Sensitivity to phytoplankton functional types (PFTs) is investigated, with focus on optically significant biological characteristics e.g. particle size distribution and intracellular structure (including vacuoles).

Phytoplankton-Associated Bacterial Community Composition and Succession during Toxic Diatom Bloom and Non-Bloom Events

PubMed Central

Sison-Mangus, Marilou P.; Jiang, Sunny; Kudela, Raphael M.; Mehic, Sanjin

2016-01-01

Pseudo-nitzschia blooms often occur in coastal and open ocean environments, sometimes leading to the production of the neurotoxin domoic acid that can cause severe negative impacts to higher trophic levels. Increasing evidence suggests a close relationship between phytoplankton bloom and bacterial assemblages, however, the microbial composition and succession during a bloom process is unknown. Here, we investigate the bacterial assemblages before, during and after toxic and non-toxic Pseudo-nitzschia blooms to determine the patterns of bacterial succession in a natural bloom setting. Opportunistic sampling of bacterial community profiles were determined weekly at Santa Cruz Municipal Wharf by 454 pyrosequencing and analyzed together with domoic acid levels, phytoplankton community and biomass, nutrients and temperature. We asked if the bacterial communities are similar between bloom and non-bloom events and if domoic acid or the presence of toxic algal species acts as a driving force that can significantly structure phytoplankton-associated bacterial communities. We found that bacterial diversity generally increases when Pseudo-nitzschia numbers decline. Furthermore, bacterial diversity is higher when the low-DA producing P. fraudulenta dominates the algal bloom while bacterial diversity is lower when high-DA producing P. australis dominates the algal bloom, suggesting that the presence of algal toxin can structure bacterial community. We also found bloom-related succession patterns among associated bacterial groups; Gamma-proteobacteria, were dominant during low toxic P. fraudulenta blooms comprising mostly of Vibrio spp., which increased in relative abundance (6–65%) as the bloom progresses. On the other hand, Firmicutes bacteria comprising mostly of Planococcus spp. (12–86%) dominate during high toxic P. australis blooms, with the bacterial assemblage showing the same bloom-related successional patterns in three independent bloom events. Other environmental variables such as nitrate and phosphate and temperature appear to influence some low abundant bacterial groups as well. Our results suggest that phytoplankton-associated bacterial communities are strongly affected not just by phytoplankton bloom in general, but also by the type of algal species that dominates in the natural bloom. PMID:27672385

Weather during bloom affects pollination and yield of highbush blueberry.

PubMed

Tuell, Julianna K; Isaacs, Rufus

2010-06-01

Weather plays an important role in spring-blooming fruit crops due to the combined effects on bee activity, flower opening, pollen germination, and fertilization. To determine the effects of weather on highbush blueberry, Vaccinium corymbosum L., productivity, we monitored bee activity and compared fruit set, weight, and seed number in a field stocked with honey bees, Apis mellifera L., and common eastern bumble bees, Bombus impatiens (Cresson). Flowers were subjected to one of five treatments during bloom: enclosed, open, open during poor weather only, open during good weather only, or open during poor and good weather. Fewer bees of all types were observed foraging and fewer pollen foragers returned to colonies during poor weather than during good weather. There were also changes in foraging community composition: honey bees dominated during good weather, whereas bumble bees dominated during poor weather. Berries from flowers exposed only during poor weather had higher fruit set in 1 yr and higher berry weight in the other year compared with enclosed clusters. In both years, clusters exposed only during good weather had > 5 times as many mature seeds, weighed twice as much, and had double the fruit set of those not exposed. No significant increase over flowers exposed during good weather was observed when clusters were exposed during good and poor weather. Our results are discussed in terms of the role of weather during bloom on the contribution of bees adapted to foraging during cool conditions.

Nutrient and other environmental controls of harmful cyanobacterial blooms along the freshwater-marine continuum.

PubMed

Paerl, Hans

2008-01-01

Nutrient and hydrologic conditions strongly influence harmful planktonic and benthic cyanobacterial bloom (CHAB) dynamics in aquatic ecosystems ranging from streams and lakes to coastal ecosystems. Urbanization, agricultural and industrial development have led to increased nitrogen (N) and phosphorus (P) discharge, which affect CHAB potentials of receiving waters. The amounts, proportions and chemical composition of N and P sources can influence the composition, magnitude and duration of blooms. This, in turn, has ramifications for food web dynamics (toxic or inedible CHABs), nutrient and oxygen cycling and nutrient budgets. Some CHABs are capable of N2 fixation, a process that can influence N availability and budgets. Certain invasive N2 fixing taxa (e.g., Cylindrospermopsis, Lyngbya) also effectively compete for fixed N during spring, N-enriched runoff periods, while they use N2 fixation to supplant their N needs during N-deplete summer months. Control of these taxa is strongly dependent on P supply. However, additional factors, such as molar N:P supply ratios, organic matter availability, light attenuation, freshwater discharge, flushing rates (residence time) and water column stability play interactive roles in determining CHAB composition (i.e. N2 fixing vs. non-N2 fixing taxa) and biomass. Bloom potentials of nutrient-impacted waters are sensitive to water residence (or flushing) time, temperatures (preference for > 15 degrees C), vertical mixing and turbidity. These physical forcing features can control absolute growth rates of bloom taxa. Human activities may affect "bottom up" physical-chemical modulators either directly, by controlling hydrologic, nutrient, sediment and toxic discharges, or indirectly, by influencing climate. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on N and/or P. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long-term control and management of blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by flushing and artificial mixing (along with nutrient input constraints) can be effective alternatives. Blooms that are not readily consumed and transferred up the food web will form a relatively large proportion of sedimented organic matter. This, in turn, will exacerbate sediment oxygen demand, and enhance the potential for oxygen depletion and release of nutrients back to the water column. This scenario is particularly problematic in long-residence time (i.e., months) systems, where blooms may exert a strong positive feedback on future events. Implications of these scenarios and the confounding issues of climatic (hydrologic) variability, including droughts, tropical storms, hurricanes and floods, will be discussed in the context of developing effective CHAB control strategies along the freshwater-marine continuum.

Phytoplankton bloom in the Bay of Biscay

NASA Image and Video Library

2017-12-08

Phytoplankton growth in the Bay of Biscay intensified in early May, 2013, painting the deep blue waters with huge swirls of jewel-tone colors that were brilliantly visible from space. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on May 4, 2013. Each year, typically from March through April, such blooms occur in the Bay of Biscay. By May, however, conditions are not as favorable and the blooms tend to fade, then disappear. This bloom is expanding in early May this year, but will likely begin to diminish soon. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team 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. Follow us on Twitter Like us on Facebook Find us on Instagram

Didymosphenia geminata: Algal blooms in oligotrophic streams and rivers

USGS Publications Warehouse

Sundareshwar, P.V.; Upadhayay, S.; Abessa, M.; Honomichl, S.; Berdanier, B.; Spaulding, S.A.; Sandvik, C.; Trennepohl, A.

2011-01-01

In recent decades, the diatom Didymosphenia geminata has emerged as nuisance species in river systems around the world. This periphytic alga forms large "blooms" in temperate streams, presenting a counterintuitive result: the blooms occur primarily in oligotrophic streams and rivers, where phosphorus (P) availability typically limits primary production. The goal of this study is to examine how high algal biomass is formed under low P conditions. We reveal a biogeochemical process by which D. geminata mats concentrate P from flowing waters. First, the mucopolysaccaride stalks of D. geminata adsorb both iron (Fe) and P. Second, enzymatic and bacterial processes interact with Fe to increase the biological availability of P. We propose that a positive feedback between total stalk biomass and high growth rate is created, which results in abundant P for cell division. The affinity of stalks for Fe in association with iron-phosphorus biogeochemistry suggest a resolution to the paradox of algal blooms in oliogotrophic streams and rivers. Copyright 2011 by the American Geophysical Union.

Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control.

PubMed

Zerrifi, Soukaina El Amrani; El Khalloufi, Fatima; Oudra, Brahim; Vasconcelos, Vitor

2018-02-09

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth.

Allelopathic interactions of linoleic acid and nitric oxide increase the competitive ability of Microcystis aeruginosa.

PubMed

Song, Hao; Lavoie, Michel; Fan, Xiaoji; Tan, Hana; Liu, Guangfu; Xu, Pengfei; Fu, Zhengwei; Paerl, Hans W; Qian, Haifeng

2017-08-01

The frequency and intensity of cyanobacterial blooms are increasing worldwide with major societal and economic costs. Interactions between toxic cyanobacteria and eukaryotic algal competitors can affect toxic bloom formation, but the exact mechanisms of interspecies interactions remain unknown. Using metabolomic and proteomic profiling of co-cultures of the toxic cyanobacterium Microcystis aeruginosa with a green alga as well as of microorganisms collected in a Microcystis spp. bloom in Lake Taihu (China), we disentangle novel interspecies allelopathic interactions. We describe an interspecies molecular network in which M. aeruginosa inhibits growth of Chlorella vulgaris, a model green algal competitor, via the release of linoleic acid. In addition, we demonstrate how M. aeruginosa takes advantage of the cell signaling compound nitric oxide produced by C. vulgaris, which stimulates a positive feedback mechanism of linoleic acid release by M. aeruginosa and its toxicity. Our high-throughput system-biology approach highlights the importance of previously unrecognized allelopathic interactions between a broadly distributed toxic cyanobacterial bloom former and one of its algal competitors.

Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control

PubMed Central

Zerrifi, Soukaina El Amrani; El Khalloufi, Fatima; Oudra, Brahim; Vasconcelos, Vitor

2018-01-01

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth. PMID:29425153

Systems approach modelling of the interactive effects of fisheries, jellyfish and tourism in the Catalan coast

NASA Astrophysics Data System (ADS)

Tomlinson, Benjamin; Maynou, Francesc; Sabatés, Ana; Fuentes, Verónica; Canepa, Antonio; Sastre, Sergio

2018-02-01

Despite the large fluctuation in annual recordings of gelatinous plankton along the Catalan coast in the north western Mediterranean and the lack of long term data sets, there is a general perception that jellyfish abundances are increasing. Local authorities are concerned about the stranding events and arrivals of jellyfish to beaches and believe it could reduce the recreational appeal of the beaches - a valuable ecosystem service for the regional tourist industry. Previous studies also demonstrate the predation of jellyfish (Pelagia noctiluca ephyrae) upon some small pelagic fish larvae (Engraulis encrasicolus). Small pelagics are the principal source of revenue for the local fisheries. A social-ecological model was created in order to capture the effects of changes in abundance of P. noctiluca upon the local fisheries, the tourist industry and the wider economy. The following sub-models were constructed and connected following the systems approach framework methodology: an age-class based fisheries model; a jellyfish population matrix model; a jellyfish stranding model; a study on the impact of jellyfish strandings on beach users; and an economic input-output matrix. Various future scenarios for different abundances of jellyfish blooms were run. The "Expected blooms" scenario is similar to the quantity and size of blooms for 2000-2010. For a hypothetical "No blooms" scenario (standard background level of jellyfish but without any blooms) landings would increase by around 294 tonnes (5.1%) per year (averaged over 10 years) or approximately 0.19 M€ in profits per year (4.5%), and strandings would decrease by 49%. In a "Frequent blooms" scenario, landings would decrease by around 147 tonnes per year (2.5%) and decrease profits by 0.10 M€ per year (2.3%), and strandings would increase by 32%. Given the changes that these scenarios would cause on the regional gross domestic product and employment, this study concludes that the overall impact of either of these scenarios on the economy would not be significant at the regional scale.

Two-decade reconstruction of algal blooms in China's Lake Taihu.

PubMed

Duan, Hongtao; Ma, Ronghua; Xu, Xiaofeng; Kong, Fanxiang; Zhang, Shouxuan; Kong, Weijuan; Hao, Jingyan; Shang, Linlin

2009-05-15

The algal blooming in the inland lakes has become a critically important issue for its impacts not only on local natural and social environments, but also on global human community. However, the occurrences of blooming on larger spatial scale and longer time scale have rarely been studied. As the third largest freshwater lake in China, Lake Taihu has drawn increasing attention from both public and scientific communities concerning its degradation. Using available satellite images, we reconstructed the spatial and temporal patterns of algal blooms in Lake Taihu through the pasttwo decades. The blooming characteristics over the past two decades were examined with the dynamic of initial blooming date being highlighted. The initial blooming dates were gradually becoming later and later from 1987 to 1997. Since 1998, however, the initial blooming date came earlier and earlier year by year, with approximately 11.42 days advancement per year. From 1987 to 2007, the annual duration of algal blooms lengthened year by year, in line with the substantial increases in the occurrences of algal blooms in spring and summer months. The algal blooms usually occur in northern bays and spread to center and south parts of Lake Taihu. The increases in previous winter's mean daily minimum temperature partially contributed to the earlier blooming onset. However, human activities, expressed as total gross domestic product (GDP) and population, outweighed the climatic contribution on the initial blooming date and blooming duration. This study may provide insights for the policy makers who try to curb the algal blooming and improve the water quality of inland freshwater lakes.

Design and Implementation of Harmful Algal Bloom Diagnosis System Based on J2EE Platform

NASA Astrophysics Data System (ADS)

Guo, Chunfeng; Zheng, Haiyong; Ji, Guangrong; Lv, Liang

According to the shortcomings which are time consuming and laborious of the traditional HAB (Harmful Algal Bloom) diagnosis by the experienced experts using microscope, all kinds of methods and technologies to identify HAB emerged such as microscopic images, molecular biology, characteristics of pigments analysis, fluorescence spectra, inherent optical properties, etc. This paper proposes the design and implementation of a web-based diagnosis system integrating the popular methods for HAB identification. This system is designed with J2EE platform based on MVC (Model-View-Controller) model as well as technologies such as JSP, Servlets, EJB and JDBC.

Local nutrient regimes determine site-specific environmental triggers of cyanobacterial and microcystin variability in urban lakes

NASA Astrophysics Data System (ADS)

Sinang, S. C.; Reichwaldt, E. S.; Ghadouani, A.

2014-10-01

Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. In the management of toxic cyanobacteria blooms, understanding the roles of environmental factors is crucial. To date, a range of environmental factors have been proposed as potential triggers for the spatiotemporal variability of cyanobacterial biomass and microcystins in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question if the environmental triggers are site-specific and unique between water bodies. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and cyanotoxins dynamics. Our study suggests that cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, the correlations between phosphorus and iron with cyanobacterial biomass and microcystin variability were not consistent between lakes, thus suggesting a site specificity of these environmental factors. The discrepancies in the correlations could be explained by differences in local nutrient concentration and the cyanobacterial community in the systems. The findings of this study suggest that identification of site-specific environmental factors under unique local conditions is an important strategy to enhance positive outcomes in cyanobacterial bloom control measures.

Viral Impacts on Total Abundance and Clonal Composition of the Harmful Bloom-Forming Phytoplankton Heterosigma akashiwo

PubMed Central

Tarutani, Kenji; Nagasaki, Keizo; Yamaguchi, Mineo

2000-01-01

Recent observations that viruses are very abundant and biologically active components in marine ecosystems suggest that they probably influence various biogeochemical and ecological processes. In this study, the population dynamics of the harmful bloom-forming phytoplankton Heterosigma akashiwo (Raphidophyceae) and the infectious H. akashiwo viruses (HaV) were monitored in Hiroshima Bay, Japan, from May to July 1998. Concurrently, a number of H. akashiwo and HaV clones were isolated, and their virus susceptibilities and host ranges were determined through laboratory cross-reactivity tests. A sudden decrease in cell density of H. akashiwo was accompanied by a drastic increase in the abundance of HaV, suggesting that viruses contributed greatly to the disintegration of the H. akashiwo bloom as mortality agents. Despite the large quantity of infectious HaV, however, a significant proportion of H. akashiwo cells survived after the bloom disintegration. The viral susceptibility of H. akashiwo isolates demonstrated that the majority of these surviving cells were resistant to most of the HaV clones, whereas resistant cells were a minor component during the bloom period. Moreover, these resistant cells were displaced by susceptible cells, presumably due to viral infection. These results demonstrated that the properties of dominant cells within the H. akashiwo population change during the period when a bloom is terminated by viral infection, suggesting that viruses also play an important role in determining the clonal composition and maintaining the clonal diversity of H. akashiwo populations. Therefore, our data indicate that viral infection influences the total abundance and the clonal composition of one host algal species, suggesting that viruses are an important component in quantitatively and qualitatively controlling phytoplankton populations in natural marine environments. PMID:11055943

Friend or Foe: Variability in How Sea Ice Can Both Hinder and Enhance Phytoplankton Blooms Across the Southern Ocean

NASA Astrophysics Data System (ADS)

Rohr, T.

2016-02-01

Globally, a suite of physical and biogeochemical controls govern the structure, size, and timing of seasonal phytoplankton blooms. In the Southern Ocean, the introduction of seasonal sea ice provides an additional constraining factor. From a bottom-up perspective, a reduction in sea ice can both enhance bloom development by permitting greater levels of surface PAR uninhibited by ice and suppress a bloom when reduced fresh melt-water inputs and increased vulnerability to wind stress combine to create deeper mixed layers and decrease depth integrated light availability. Regions along the Western Antarctic Peninsula have already seen a contradictory response to reduced ice cover, with enhanced summertime chlorophyll concentrations in the South, and large declines to the North. This dichotomy is thought to arise from differences in the interannual mean sea ice state, with extensively ice covered regions benefiting from reduced coverage and more sparsely covered regions hindered by further reductions. The questions arises: 1) At what threshold does a reduction in sea ice transition from amplifying blooms to suppressing them? 2) How do additional environmental considerations such as nutrient availability and trophic interactions complicate this transition? Here, we combine remote sensing observations and in-situ data (from PAL LTER) with a hierarchy of 1-D water column and global general circulation (CESM) models to access the variability in how regional differences in mean ice state combine with other environmental forcings to dictate how interannual variability (or long term trends) in ice coverage will affect bloom structure, size and dynamics. In doing so we will gain a better understanding of how predicted changes in sea ice will effect Southern Ocean productivity, which of course will have important consequences in the global carbon cycle and sustainability of healthy marine ecosystems.

Interannual variability in the magnitude and timing of the spring bloom in the Oyashio region

NASA Astrophysics Data System (ADS)

Okamoto, Suguru; Hirawake, Toru; Saitoh, Sei-Ichi

2010-09-01

Inter-annual variability in the magnitude and timing of the spring bloom was investigated for the Oyashio region (40 °-48 °N, 143 °E-152 °E) using 10 years (from 1998 to 2007) of satellite ocean-color data. Geostrophic currents were examined using satellite altimeter data. Early spring blooms (>1.5 mg m -3) occurred in early April 2001 and late March 2002. The 2001 bloom continued for one month. Late blooms occurred from mid-May 1999, early June 2004 and late April 2006, continuing for about 1 month, 8 days and 16 days, respectively. A strong bloom (4.7 mg m -3) also occurred in mid-April 1998; however, it terminated in early May. We classified the Oyashio region based on the pattern of temporal variation of Chl- a concentr ation from March to June. The spatio-temporal variability in Chl- a concentr ation during spring was different among years. The area where Chl- a concentr ation was highest in April was more extensive in 2001, 2002 and 2006 than usual. In 1999, the area where Chl- a concentr ation was highest in May was the widest among the 10 years. Mesoscale eddies and currents with high velocity were frequently observed in the area of high Chl- a concentr ation east of Hokkaido, propagating Coastal Oyashio Water of low salinity and low density into the oceanic region. That strengthened stratification in the surface layer. We suggest that this seaward transfer of coastal water could be one of the important factors for phytoplankton distribution in two ways: (1) horizontal advection of water with high Chl- a concentr ation and (2) enhancement of stratification in the oceanic region.

Are the spring and fall blooms on the Scotian Shelf related to short-term physical events?

NASA Astrophysics Data System (ADS)

Greenan, B. J. W.; Petrie, B. D.; Harrison, W. G.; Oakey, N. S.

2004-03-01

Physical, chemical and biological data from the Scotian Shelf indicate that short-term physical events affect the dynamics of spring and fall blooms. This is based on results from a three-week mooring deployment measuring currents, temperature, salinity and fluorescence in October 2000, combined with biweekly sampling of temperature, salinity, nutrients and chlorophyll throughout the year at this mooring site. A wind-driven upwelling event in mid-October shows temperature, salinity and density iso-surfaces rising by approximately 20 m. During this event, a bloom with peak chlorophyll concentrations of about 2.5 mg m -3 began as nutrients are brought into the upper part of the water column. Gradient Richardson Numbers ( Ri), a proxy for vertical mixing, are estimated for the mooring period in 2 m vertical bins using SeaHorse CTD data and nearby ADCP current measurements. These data indicate that vertical mixing may have played a complementary role to the upwelling in bringing nutrients into the euphotic zone. A trend of decreasing Ri in the ocean mixed layer with increasing surface wind stress is suggested. It appears that this short-term physical event is a primary factor in initiating the fall bloom on the inner Scotian Shelf in 2000. In April of that year, the termination of the spring bloom coincided with a downwelling event suggesting that it played a role in determining the duration of the bloom. SeaWiFS ocean color satellite provided a spatial context for chlorophyll observations, however, the lack of temporal resolution due to poor atmospheric conditions means that these data provide limited information on short-term chlorophyll variability.

[Dynamics of bacterial community during the bloom caused by Skeletonema costatum and Akashiwo sanguinea in Xiamen sea area].

PubMed

Li, Yi; Yang, Caiyun; Li, Dong; Tian, Yun; Zheng, Tianling

2012-10-04

To investigate the dynamics of bacterial community in Xiamen sea during the bloom mainly caused by Skeletonema costatum and Akashiwo sanguine in August 2011. Bacterial community structures of samples from two bloom sites and one non-bloom site were evaluated by PCR-DGGE (Denaturing gradient gel electrophoresis, DGGE). The genetic diversity of bacterial community was analyzed based on the DGGE fingerprint. The correlation between bacterial community and environmental parameters was studied by Canoco. The bacterial community was largely related to pH and N/P during the start-up stage of the bloom; while in the demise stage, it was mostly correlated to salinity and temperature. According to the results of sequence analysis of DGGE dominant bands, Gammaproteobacteria accounted for 47.7% during the bloom and Pseudoalteromonas, Pseudomonas, Alteromonas, Hydrogenophaga, Actibacter and Oleibacter were dominant genus in bacterial community. The Shannon-Weaver diversity index showed that the diversity of bacterial community in bloom site increased firstly and then decreased during this bloom. Hydrogenophaga was dominant in the start-up stage of bloom, while Pseudomonas and Pseudoalteromonas were dominant in the demise stage of bloom. The diversity of attached bacteria and free-living bacteria in bloom sites reached maximum in the same day (the concentration of algae was high) , both of them changed greatly during the bloom while the environment factors which correlated with the two communities were different. It is the first report about dynamics of bacterial community during the bloom caused by several algae together. This work is helpful to understand the dynamics of bacterial community during the bloom, and provides a theoretical basis for bloom's control in the future.

Original opinion: the use of Bloom's Taxonomy to teach and assess the skill of the psychiatric formulation during vocational training.

PubMed

de Beer, Wayne A

2017-10-01

This paper proposes the use of the cognitive domain of Bloom's Taxonomy, an educational classification system, to guide the critical thinking required for the composition of the psychiatric formulation during the various stages of specialist training. Bloom's Taxonomy offers a hierarchical, structured approach to clinical reasoning. Use of this method can assist supervisors and trainees to understand better the concepts of and offer a developmental approach to critical reasoning. Application of the Taxonomy, using cognitive 'action words' (verbs) within each of the levels, can promote increasing sophistication in the construction of the psychiatric formulation. Examples of how the Taxonomy can be adapted to design educational resources are suggested in the article.

Microbial control of diatom bloom dynamics in the open ocean

NASA Astrophysics Data System (ADS)

Boyd, Philip W.; Strzepek, Robert; Chiswell, Steve; Chang, Hoe; DeBruyn, Jennifer M.; Ellwood, Michael; Keenan, Sean; King, Andrew L.; Maas, Elisabeth W.; Nodder, Scott; Sander, Sylvia G.; Sutton, Philip; Twining, Benjamin S.; Wilhelm, Steven W.; Hutchins, David A.

2012-09-01

Diatom blooms play a central role in supporting foodwebs and sequestering biogenic carbon to depth. Oceanic conditions set bloom initiation, whereas both environmental and ecological factors determine bloom magnitude and longevity. Our study reveals another fundamental determinant of bloom dynamics. A diatom spring bloom in offshore New Zealand waters was likely terminated by iron limitation, even though diatoms consumed <1/3 of the mixed-layer dissolved iron inventory. Thus, bloom duration and magnitude were primarily set by competition for dissolved iron between microbes and small phytoplankton versus diatoms. Significantly, such a microbial mode of control probably relies both upon out-competing diatoms for iron (i.e., K-strategy), and having high iron requirements (i.e., r-strategy). Such resource competition for iron has implications for carbon biogeochemistry, as, blooming diatoms fixed three-fold more carbon per unit iron than resident non-blooming microbes. Microbial sequestration of iron has major ramifications for determining the biogeochemical imprint of oceanic diatom blooms.

Earth observations taken by the Expedition Seven crew

NASA Image and Video Library

2003-10-11

ISS007-E-17038 (11 October 2003) --- This view featuring a close-up of the Salton Sea was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). The image provides detail of the structure of the algal bloom. These blooms continue to be a problem for the Salton Sea. They are caused by high concentrations of nutrients, especially nitrogen and phosphorous, which drain into the basin from the agricultural run-off. As the algae die and decompose, oxygen levels in the sea drop, causing fish kills and hazardous condition for other wildlife.

Response of a Bell–Bloom Magnetometer to a Magnetic Field of Arbitrary Direction

PubMed Central

Ding, Zhichao; Yuan, Jie; Long, Xingwu

2018-01-01

The Bell–Bloom magnetometer in response to a magnetic field of arbitrary direction is observed theoretically and experimentally. A theoretical model is built from a macroscopic view to simulate the magnetometer frequency response to an external magnetic field of arbitrary direction. Based on the simulation results, the magnetometer characteristics, including the signal phase and amplitude at resonance, the linewidth, and the magnetometer sensitivity, are analyzed, and the dependencies of these characteristics on the external magnetic field direction are obtained, which are verified by the experiment. PMID:29724059

The Role of Model Complexity in Determining Patterns of Chlorophyll Variability in the Coastal Northwest North Atlantic

NASA Astrophysics Data System (ADS)

Kuhn, A. M.; Fennel, K.; Bianucci, L.

2016-02-01

A key feature of the North Atlantic Ocean's biological dynamics is the annual phytoplankton spring bloom. In the region comprising the continental shelf and adjacent deep ocean of the northwest North Atlantic, we identified two patterns of bloom development: 1) locations with cold temperatures and deep winter mixed layers, where the spring bloom peaks around April and the annual chlorophyll cycle has a large amplitude, and 2) locations with warmer temperatures and shallow winter mixed layers, where the spring bloom peaks earlier in the year, sometimes indiscernible from the fall bloom. These patterns result from a combination of limiting environmental factors and interactions among planktonic groups with different optimal requirements. Simple models that represent the ecosystem with a single phytoplankton (P) and a single zooplankton (Z) group are challenged to reproduce these ecological interactions. Here we investigate the effect that added complexity has on determining spatio-temporal chlorophyll. We compare two ecosystem models, one that contains one P and one Z group, and one with two P and three Z groups. We consider three types of changes in complexity: 1) added dependencies among variables (e.g., temperature dependent rates), 2) modified structural pathways, and 3) added pathways. Subsets of the most sensitive parameters are optimized in each model to replicate observations in the region. For computational efficiency, the parameter optimization is performed using 1D surrogates of a 3D model. We evaluate how model complexity affects model skill, and whether the optimized parameter sets found for each model modify the interpretation of ecosystem functioning. Spatial differences in the parameter sets that best represent different areas hint at the existence of different ecological communities or at physical-biological interactions that are not represented in the simplest model. Our methodology emphasizes the combined use of observations, 1D models to help identifying patterns, and 3D models able to simulate the environment modre realistically, as a means to acquire predictive understanding of the ocean's ecology.

Observing System Forecast Experiments at the DAO

NASA Technical Reports Server (NTRS)

Atlas, Robert

2001-01-01

Since the advent of meteorological satellites in the 1960's, numerous experiments have been conducted in order to evaluate the impact of these and other data on atmospheric analysis and prediction. Such studies have included both OSE'S and OSSE's. The OSE's were conducted to evaluate the impact of specific observations or classes of observations on analyses and forecasts. Such experiments have been performed for selected types of conventional data and for various satellite data sets as they became available. (See for example the 1989 ECMWF/EUMETSAT workshop proceedings on "The use of satellite data in operational numerical weather prediction" and the references contained therein.) The ODYSSEY were conducted to evaluate the potential for future observing systems to improve Numerical Weather Prediction NWP and to plan for the Global Weather Experiment and more recently for EVANS (Atlas et al., 1985a; Arnold and Day, 1986; Hoffman et al., 1990). In addition, OSSE's have been run to evaluate trade-offs in the design of observing systems and observing networks (Atlas and Emmitt, 1991; Rohaly and Krishnamurti, 1993), and to test new methodology for data assimilation (Atlas and Bloom, 1989).

Effects of the Original Versus Revised Bloom's Taxonomy on Lesson Planning Skills: A Turkish Study Among Pre-Service Teachers

NASA Astrophysics Data System (ADS)

Bümen, Nilay T.

2007-07-01

The original taxonomy of educational objectives, developed by Benjamin S.␣Bloom and his associates in the 1950s, was revised several decades later by a group of educationists and cognitive psychologists, who developed a revised taxonomy (RT). This article describes a Turkish study carried out among a group of pre-service teachers in order to compare the influence of the two systems on lesson planning skills. The results confirmed other studies that have indicated a number of advantages of the revised system over the earlier one.

Analysing learning outcomes in an Electrical Engineering curriculum using illustrative verbs derived from Bloom's Taxonomy

NASA Astrophysics Data System (ADS)

Meda, Lawrence; Swart, Arthur James

2018-05-01

Learning outcomes are essential to any curriculum in education, where they need to be clear, observable and measurable. However, some academics structure learning outcomes in a way that does not promote student learning. The purpose of this article is to present the analyses of learning outcomes of an Electrical Engineering curriculum offered at a University of Technology in South Africa, in order to determine if academics are structuring them in a way that enables student learning. A qualitative case study is used where the learning outcomes from 33 study guides are reviewed using illustrative verbs derived from Bloom's Taxonomy. Results indicate that 9% of all the learning outcomes are unclear, 10% are unobservable and 23% are unmeasurable. A key recommendation is to provide regular workshops to assist academics in reviewing their learning outcomes using the illustrative verbs derived from Bloom's Taxonomy, thereby ensuring that their learning outcomes promote student learning.

Seasonal cooling and blooming in tropical oceans

NASA Astrophysics Data System (ADS)

Longhurst, Alan

1993-11-01

The relative importance of tropical pelagic algal blooms in not yet fully appreciated and the way they are induced not well understood. The tropical Atlantic supports pelagic blooms together equivalent to the North Atlantic spring bloom. These blooms are driven by thermocline tilting, curl of wind stress and eddy upwelling as the ocean responds to intensified basin-scale winds in boreal summer. The dimensions of the Pacific Ocean are such that seasonal thermocline tilting does not occur, and nutrient conditions are such that tilting might not induce bloom, in any case. Divergence at the equator is a separate process that strengthens the Atlantic bloom, is more prominent in the eastern Pacific, and in the Indian Ocean induces a bloom only in the western part of the ocean. Where western jet currents are retroflected from the coast off Somalia and Brazil, eddy upwelling induces prominent blooms. In the eastward flow of the northern equatorial countercurrents, positive wind curl stress induces Ekman pumping and the induction of algal blooms aligned with the currents. Some apparent algal bloom, such as that seen frequently in CZCS images westwards from Senegal, must be due to interference from airborne dust.

Phytoplankton bloom off western Iceland

NASA Image and Video Library

2017-12-08

NASA image captured 06/24/2010 at 14 :30 UTC Phytoplankton bloom off western Iceland Satellite: Aqua NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team To learn more about MODIS go to: rapidfire.sci.gsfc.nasa.gov/gallery/?latest NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Potential for dietary exposure to β-N-methylamino-L-alanine and microcystin from a freshwater system.

PubMed

Scott, Laura L; Downing, Simoné; Downing, Tim

2018-06-18

The suggested link between β-N-methylamino-L-alanine (BMAA) and the onset of neurodegenerative diseases and the detection of this cyanotoxin in aquatic organisms has prompted research into the potential human exposure risk associated with sourcing food items from eutrophied water bodies worldwide. The Hartbeespoort Dam reservoir in the North West province of South Africa has persistent cyanobacterial blooms and is used extensively by anglers, many of whom consume their catch. The commercial sale of fish species harvested from this reservoir as part of a recent biomanipulative remediation strategy may pose an additional hazard. BMAA and Microcystins (MC) were detected in fish sourced from this reservoir. BMAA levels of up to 1630 ng g -1 dry weight and MC concentrations of up to 29.44 ng g -1 dry weight were detected in fish sourced during an extensive bloom episode, with a clear correlation between the total amount of BMAA detected in the fish muscle tissue and their relative position in the Hartbeespoort Dam reservoir food web. Interestingly, fish sourced from this reservoir in winter when dense cyanobacterial blooms were lacking contained BMAA levels of up to 3055 ng g -1 dry weight. We also comment on the observed seasonal variations of BMAA levels in phytoplankton and fish sourced from this water body as well as the potential exposure risks associated with harvesting food items from this reservoir. Copyright © 2018 Elsevier Ltd. All rights reserved.

Water Quality Conditions in Upper Klamath and Agency Lakes, Oregon, 2006

USGS Publications Warehouse

Lindenberg, Mary K.; Hoilman, Gene; Wood, Tamara M.

2008-01-01

The U.S. Geological Survey Upper Klamath Lake water quality monitoring program gathered information from multiparameter continuous water quality monitors, physical water samples, dissolved oxygen production and consumption experiments, and meteorological stations during the June-October 2006 field season. The 2006 study area included Agency Lake and all of Upper Klamath Lake. Seasonal patterns in water quality were similar to those observed in 2005, the first year of the monitoring program, and were closely related to bloom dynamics of the cyanobacterium (blue-green alga) Aphanizomenon flos-aquae (AFA) in the two lakes. High dissolved oxygen and pH conditions in both lakes before the bloom declined in July, which coincided with seasonal high temperatures and resulted in seasonal lows in dissolved oxygen and decreased pH. Dissolved oxygen and pH in Upper Klamath and Agency Lakes increased again after the bloom recovered. Seasonal low dissolved oxygen and decreased pH coincided with seasonal highs in ammonia and orthophosphate concentrations. Seasonal maximum daily average temperatures were higher and minimum dissolved oxygen concentrations were lower in 2006 than in 2005. Conditions potentially harmful to fish were influenced by seasonal patterns in bloom dynamics and bathymetry. Potentially harmful low dissolved oxygen and high un-ionized ammonia concentrations occurred mostly at the deepest sites in the Upper Klamath Lake during late July, coincident with a bloom decline. Potentially harmful pH conditions occurred mostly at sites outside the deepest parts of the lake in July and September, coincident with a heavy bloom. Instances of possible gas bubble formation, inferred from dissolved oxygen data, were estimated to occur frequently in shallow areas of Upper Klamath and Agency Lakes simultaneously with potentially harmful pH conditions. Comparison of the data from monitors in nearshore areas and monitors near the surface of the water column in the open waters of Upper Klamath Lake revealed few differences in water quality dynamics. Median daily temperatures were higher in nearshore areas, and dissolved oxygen concentrations were periodically higher as well during periods of high AFA bloom. Differences between the two areas in water quality conditions potentially harmful to fish were not statistically significant (p < 0.05). Chlorophyll a concentrations varied temporally and spatially throughout Upper Klamath Lake. Chlorophyll a concentrations indicated an algal bloom in late June and early July that was followed by an algae bloom decline in late July and early August and a subsequent recovery in mid-August. Sites in the deepest part of the lake, where some of the highest chlorophyll a concentrations were observed, were the same sites where the lowest dissolved oxygen concentrations and the highest un-ionized ammonia concentrations were recorded during the bloom decline, indicating cell senescence. Total phosphorus concentrations limited the initial algal bloom in late June and early July. The rate of net dissolved oxygen production (that is, production in excess of community respiration) and consumption (due to community respiration) in the lake water column as measured in light and dark bottles, respectively, ranged from 2.79 to -2.14 milligrams of oxygen per liter per hour. Net production rate generally correlated positively with chlorophyll a concentration, except episodically at a few sites where high chlorophyll a concentrations resulted in self-shading that inhibited photosynthesis. The depth of photic zone was inversely correlated with chlorophyll a concentration. Calculations of a 24-hour change in dissolved oxygen concentration indicated that oxygen-consuming processes predominated at the deep trench sites and oxygen-producing processes predominated at the shallow sites. In addition, calculations of the 24-hour change in dissolved oxygen indicate that oxygen-consuming processes in the water column di

Seasonal variability of Dinophysis spp. and Protoceratium reticulatum associated to lipophilic shellfish toxins in a strongly stratified Chilean fjord

NASA Astrophysics Data System (ADS)

Alves-de-Souza, Catharina; Varela, Daniel; Contreras, Cristóbal; de La Iglesia, Pablo; Fernández, Pamela; Hipp, Byron; Hernández, Cristina; Riobó, Pilar; Reguera, Beatriz; Franco, José M.; Diogène, Jorge; García, Carlos; Lagos, Néstor

2014-03-01

The fine scale vertical distribution of Dinophysis spp. and Protoceratium reticulatum (potential producers of lipophilic shellfish toxins, LSTs) and its relation with LSTs in shellfish was studied in Reloncaví fjord, a strongly stratified system in Southern Chile. Samples were taken over two years from late spring to early autumn (2007-2008 period) and from early spring to late summer (2008-2009 period). Dinophysis spp., in particular Dinophysis acuminata, were always detected, often forming thin layers in the region of the salinity driven pycnocline, with cell maxima for D. acuminata of 28.5×103 cells L-1 in March 2008 and 17.1×103 cells L-1 in November 2008. During the 2008-2009 sampling period, blooms of D. acuminata co-occurred with high densities of cryptophyceans and the ciliate Mesodinium spp. The highest levels of pectenotoxin-2 (PTX-2; 2.2 ng L-1) were found in the plankton in February 2009, associated with moderate densities of D. acuminata, Dinophysis tripos and Dinophysis subcircularis (0.1-0.6×103 cells L-1). However, only trace levels of PTX-2 were observed in bivalves at that time. Dinophysistoxin (DTX-1 and DTX-3) levels in bivalves and densities of Dinophysis spp. were not well correlated. Low DTX levels in bivalves observed during a major bloom of D. acuminata in March 2008 suggested that there is a large seasonal intraspecific variability in toxin content of Dinophysis spp. driven by changes in population structure associated with distinct LST toxin profiles in Reloncaví fjord during the study period. A heterogeneous vertical distribution was also observed for P. reticulatum, whose presence was restricted to summer months. A bloom of this species of 2.2×103 cells L-1 at 14 m depth in February 2009 was positively correlated with high concentrations of yessotoxins in bivalves (51-496 ng g-1) and plankton samples (3.2 ng L-1). Our results suggest that a review of monitoring strategies for Dinophysis spp. in strongly stratified fjord systems should be carried out. They also indicate that early warning of LST events based on Dinophysis cell numbers are not reliable for seafood control.

Under-Ice Phytoplankton Blooms Inhibited by Spring Convective Mixing in Refreezing Leads

NASA Astrophysics Data System (ADS)

Lowry, Kate E.; Pickart, Robert S.; Selz, Virginia; Mills, Matthew M.; Pacini, Astrid; Lewis, Kate M.; Joy-Warren, Hannah L.; Nobre, Carolina; van Dijken, Gert L.; Grondin, Pierre-Luc; Ferland, Joannie; Arrigo, Kevin R.

2018-01-01

Spring phytoplankton growth in polar marine ecosystems is limited by light availability beneath ice-covered waters, particularly early in the season prior to snowmelt and melt pond formation. Leads of open water increase light transmission to the ice-covered ocean and are sites of air-sea exchange. We explore the role of leads in controlling phytoplankton bloom dynamics within the sea ice zone of the Arctic Ocean. Data are presented from spring measurements in the Chukchi Sea during the Study of Under-ice Blooms In the Chukchi Ecosystem (SUBICE) program in May and June 2014. We observed that fully consolidated sea ice supported modest under-ice blooms, while waters beneath sea ice with leads had significantly lower phytoplankton biomass, despite high nutrient availability. Through an analysis of hydrographic and biological properties, we attribute this counterintuitive finding to springtime convective mixing in refreezing leads of open water. Our results demonstrate that waters beneath loosely consolidated sea ice (84-95% ice concentration) had weak stratification and were frequently mixed below the critical depth (the depth at which depth-integrated production balances depth-integrated respiration). These findings are supported by theoretical model calculations of under-ice light, primary production, and critical depth at varied lead fractions. The model demonstrates that under-ice blooms can form even beneath snow-covered sea ice in the absence of mixing but not in more deeply mixed waters beneath sea ice with refreezing leads. Future estimates of primary production should account for these phytoplankton dynamics in ice-covered waters.

Remote Sensing as a Tool to Track Algal Blooms in the Great Salt Lake, Utah, USA

NASA Astrophysics Data System (ADS)

Bradt, S. R.; Wurtsbaugh, W. A.; Naftz, D.; Moore, T.; Haney, J.

2006-12-01

The Great Salt Lake is a large hypersaline, terminal water body in northern Utah, USA. The lake has both a significant economic importance to the local community as a source of brine shrimp and mineral resources, as well as, an ecological importance to large numbers of migratory waterfowl. Due to nutrient input from sewage treatment plants, sections of the Great Salt Lake are subjected to highly eutrophic conditions. One of the main tributaries, Farmington Bay, experiences massive blooms of cyanobacteria which can reach concentrations in excess of 300 mg l-1 in the bay. Effects of these blooms can be observed stretching into the rest of the lake. The detrimental outcomes of the blooms include unsightly scums, foul odor and the danger of cyanobacterial toxins. While the blooms have an obvious effect on Farmington Bay, it is quite possible that the cyanobacteria impact a much wider area of the lake as currents move eutrophic water masses. Of particular interest is the reaction of brine shrimp to the plumes of cyanobacteria-rich water leaving Farmington Bay. We are employing remote sensing as a tool to map the distribution of algae throughout the lake and produce lake-wide maps of water quality on a regular basis. On-lake reflectance measurements have been coupled with MODIS satellite imagery to produce a time series of maps illustrating changes in algal distribution. The successes and shortcomings of our remote sensing technique will be a central topic of this presentation.

A review of ocean color remote sensing methods and statistical techniques for the detection, mapping and analysis of phytoplankton blooms in coastal and open oceans

NASA Astrophysics Data System (ADS)

Blondeau-Patissier, David; Gower, James F. R.; Dekker, Arnold G.; Phinn, Stuart R.; Brando, Vittorio E.

2014-04-01

The need for more effective environmental monitoring of the open and coastal ocean has recently led to notable advances in satellite ocean color technology and algorithm research. Satellite ocean color sensors' data are widely used for the detection, mapping and monitoring of phytoplankton blooms because earth observation provides a synoptic view of the ocean, both spatially and temporally. Algal blooms are indicators of marine ecosystem health; thus, their monitoring is a key component of effective management of coastal and oceanic resources. Since the late 1970s, a wide variety of operational ocean color satellite sensors and algorithms have been developed. The comprehensive review presented in this article captures the details of the progress and discusses the advantages and limitations of the algorithms used with the multi-spectral ocean color sensors CZCS, SeaWiFS, MODIS and MERIS. Present challenges include overcoming the severe limitation of these algorithms in coastal waters and refining detection limits in various oceanic and coastal environments. To understand the spatio-temporal patterns of algal blooms and their triggering factors, it is essential to consider the possible effects of environmental parameters, such as water temperature, turbidity, solar radiation and bathymetry. Hence, this review will also discuss the use of statistical techniques and additional datasets derived from ecosystem models or other satellite sensors to characterize further the factors triggering or limiting the development of algal blooms in coastal and open ocean waters.

Drivers of phytoplankton dynamics in old Tampa Bay, FL (USA), a subestuary lagging in ecosystem recovery

NASA Astrophysics Data System (ADS)

Corcoran, Alina A.; Wolny, Jennifer; Leone, Erin; Ivey, James; Murasko, Susan

2017-02-01

In the past four decades, consistent and coordinated management actions led to the recovery of Tampa Bay, FL (USA) - an estuary that was declared dead in the 1970s. An exception to this success story is Old Tampa Bay, the northernmost subestuary of the system. Compared to the other bay segments, Old Tampa Bay is characterized by poorer water quality and spring and summer blooms of cyanobacteria, picoplankton, diatoms, and the saxitoxin-producing dinoflagellate Pyrodinium bahamense. Together, these blooms contribute to light attenuation and lagging recovery of seagrass beds. Yet, studies of phytoplankton dynamics within Old Tampa Bay have been limited - both in number and in their spatiotemporal resolution. In this study, we used field sampling and continuous monitoring to (1) characterize temporal and spatial variability in phytoplankton biomass and community composition and (2) identify key drivers of the different phytoplankton blooms in Old Tampa Bay. Overall, temporal variability in phytoplankton biomass (using chlorophyll a as a proxy) and community composition surpassed spatial variability of these parameters. We found a base community of small diatoms and flagellates, as well as certain dinoflagellates, that persisted year round in the system. Seasonally, freshwater runoff stimulated phytoplankton growth, specifically that of chlorophytes, cyanobacteria and other dinoflagellates - consistent with predictions based on ecological theory. On shorter time scales, salinity, visibility, and freshwater inflows were important predictors of phytoplankton biomass. With respect to P. bahamense, environmental drivers including salinity, temperature and dissolved nutrient concentrations explained ∼24% of the variability in cell abundance, indicating missing explanatory parameters in our study for this taxon, such as cyst density and location of cyst beds. Spatially, we found differences in community trajectories across north-south and west-east gradients, with the northernmost sampling station being the most unique in the region. This work contributes to the knowledge of phytoplankton biomass and community composition in Tampa Bay by generating spatially and temporally rich phytoplankton community and environmental data for the Old Tampa Bay subestuary. Moreover, it enhances our understanding of bloom drivers and provides recommendations for ecosystem management. Specifically, our findings support continued nutrient reduction measures as a way to mitigate seasonal blooms of diatoms, cyanobacteria and chlorophytes, but not necessarily blooms of P. bahamense. Prediction and mitigation of P. bahamnese blooms should incorporate first order drivers such as cyst location and abundance.

How physiological and physical processes contribute to the phenology of cyanobacterial blooms in large shallow lakes: A new Euler-Lagrangian coupled model.

PubMed

Feng, Tao; Wang, Chao; Wang, Peifang; Qian, Jin; Wang, Xun

2018-09-01

Cyanobacterial blooms have emerged as one of the most severe ecological problems affecting large and shallow freshwater lakes. To improve our understanding of the factors that influence, and could be used to predict, surface blooms, this study developed a novel Euler-Lagrangian coupled approach combining the Eulerian model with agent-based modelling (ABM). The approach was subsequently verified based on monitoring datasets and MODIS data in a large shallow lake (Lake Taihu, China). The Eulerian model solves the Eulerian variables and physiological parameters, whereas ABM generates the complete life cycle and transport processes of cyanobacterial colonies. This model ensemble performed well in fitting historical data and predicting the dynamics of cyanobacterial biomass, bloom distribution, and area. Based on the calculated physical and physiological characteristics of surface blooms, principal component analysis (PCA) captured the major processes influencing surface bloom formation at different stages (two bloom clusters). Early bloom outbreaks were influenced by physical processes (horizontal transport and vertical turbulence-induced mixing), whereas buoyancy-controlling strategies were essential for mature bloom outbreaks. Canonical correlation analysis (CCA) revealed the combined actions of multiple environment variables on different bloom clusters. The effects of buoyancy-controlling strategies (ISP), vertical turbulence-induced mixing velocity of colony (VMT) and horizontal drift velocity of colony (HDT) were quantitatively compared using scenario simulations in the coupled model. VMT accounted for 52.9% of bloom formations and maintained blooms over long periods, thus demonstrating the importance of wind-induced turbulence in shallow lakes. In comparison, HDT and buoyancy controlling strategies influenced blooms at different stages. In conclusion, the approach developed here presents a promising tool for understanding the processes of onshore/offshore algal blooms formation and subsequent predicting. Copyright © 2018 Elsevier Ltd. All rights reserved.

Climate Variability and Oceanographic Settings Associated with Interannual Variability in the Initiation of Dinophysis acuminata Blooms

PubMed Central

Díaz, Patricio A.; Reguera, Beatriz; Ruiz-Villarreal, Manuel; Pazos, Yolanda; Velo-Suárez, Lourdes; Berger, Henrick; Sourisseau, Marc

2013-01-01

In 2012, there were exceptional blooms of D. acuminata in early spring in what appeared to be a mesoscale event affecting Western Iberia and the Bay of Biscay. The objective of this work was to identify common climatic patterns to explain the observed anomalies in two important aquaculture sites, the Galician Rías Baixas (NW Spain) and Arcachon Bay (SW France). Here, we examine climate variability through physical-biological couplings, Sea Surface Temperature (SST) anomalies and time of initiation of the upwelling season and its intensity over several decades. In 2012, the mesoscale features common to the two sites were positive anomalies in SST and unusual wind patterns. These led to an atypical predominance of upwelling in winter in the Galician Rías, and increased haline stratification associated with a southward advection of the Gironde plume in Arcachon Bay. Both scenarios promoted an early phytoplankton growth season and increased stability that enhanced D. acuminata growth. Therefore, a common climate anomaly caused exceptional blooms of D. acuminata in two distant regions through different triggering mechanisms. These results increase our capability to predict intense diarrhetic shellfish poisoning outbreaks in the early spring from observations in the preceding winter. PMID:23959151

The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms.

PubMed

Dreano, Denis; Raitsos, Dionysios E; Gittings, John; Krokos, George; Hoteit, Ibrahim

2016-01-01

Knowledge on large-scale biological processes in the southern Red Sea is relatively limited, primarily due to the scarce in situ, and satellite-derived chlorophyll-a (Chl-a) datasets. During summer, adverse atmospheric conditions in the southern Red Sea (haze and clouds) have long severely limited the retrieval of satellite ocean colour observations. Recently, a new merged ocean colour product developed by the European Space Agency (ESA)-the Ocean Color Climate Change Initiative (OC-CCI)-has substantially improved the southern Red Sea coverage of Chl-a, allowing the discovery of unexpected intense summer blooms. Here we provide the first detailed description of their spatiotemporal distribution and report the mechanisms regulating them. During summer, the monsoon-driven wind reversal modifies the circulation dynamics at the Bab-el-Mandeb strait, leading to a subsurface influx of colder, fresher, nutrient-rich water from the Indian Ocean. Using satellite observations, model simulation outputs, and in situ datasets, we track the pathway of this intrusion into the extensive shallow areas and coral reef complexes along the basin's shores. We also provide statistical evidence that the subsurface intrusion plays a key role in the development of the southern Red Sea phytoplankton blooms.

Host-Specificity and Dynamics in Bacterial Communities Associated with Bloom-Forming Freshwater Phytoplankton

PubMed Central

Bagatini, Inessa Lacativa; Eiler, Alexander; Bertilsson, Stefan; Klaveness, Dag; Tessarolli, Letícia Piton; Vieira, Armando Augusto Henriques

2014-01-01

Many freshwater phytoplankton species have the potential to form transient nuisance blooms that affect water quality and other aquatic biota. Heterotrophic bacteria can influence such blooms via nutrient regeneration but also via antagonism and other biotic interactions. We studied the composition of bacterial communities associated with three bloom-forming freshwater phytoplankton species, the diatom Aulacoseira granulata and the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii. Experimental cultures incubated with and without lake bacteria were sampled in three different growth phases and bacterial community composition was assessed by 454-Pyrosequencing of 16S rRNA gene amplicons. Betaproteobacteria were dominant in all cultures inoculated with lake bacteria, but decreased during the experiment. In contrast, Alphaproteobacteria, which made up the second most abundant class of bacteria, increased overall during the course of the experiment. Other bacterial classes responded in contrasting ways to the experimental incubations causing significantly different bacterial communities to develop in response to host phytoplankton species, growth phase and between attached and free-living fractions. Differences in bacterial community composition between cyanobacteria and diatom cultures were greater than between the two cyanobacteria. Despite the significance, major differences between phytoplankton cultures were in the proportion of the OTUs rather than in the absence or presence of specific taxa. Different phytoplankton species favoring different bacterial communities may have important consequences for the fate of organic matter in systems where these bloom forming species occur. The dynamics and development of transient blooms may also be affected as bacterial communities seem to influence phytoplankton species growth in contrasting ways. PMID:24465807

Quantifying Cyanobacteria and High Biomass Bloms from Satellite to Support Environmental Management and Public Use of U.S. Lakes and Estuaries

NASA Astrophysics Data System (ADS)

Tomlinson, Michelle C.; Stumpf, Richard P.; Dupuy, Danielle; Wynne, Timothy T.; Briggs, Travis

2015-12-01

Algal blooms of high biomass and cyanobacteria are on the rise, occurring both nationally and internationally. These blooms can foul beaches, clog water intakes, produce toxins that contaminate drinking water, and pose a threat to human and domestic animal health. A quantitative tool can aid in the management needs to respond to these issues. These blooms can affect many lakes within a state management district, pointing to the need for a synoptic and timely assessment. The 300 m Medium Resolution Imaging Spectrometer (MERIS) satellite imagery provided by the European Space Agency from 2002 to 2012 has led to advances in our ability to monitor these systems. Algorithms specific to quantifying high biomass blooms have been developed for use by state managers through a comparison of field radiometry, water quality and cell enumeration measurements, and remotely-sensed satellite data. These algorithms are designed to detect blooms even with atmospheric interference and suspended sediments. Initial evaluations were conducted for Florida lakes and the St. Johns River, Florida, USA and showed that cyanobacteria blooms, especially of Microcystis, can be identified and their biomass can be estimated (as chlorophyll concentration and other metrics). Forecasts and monitoring have been demonstrated for Lake Erie and for Florida. A multi-agency (NASA, EPA, NOAA, and USGS) project, “Cyanobacteria Assessment Network (CyAN)” intends to apply these methods to Sentinel-3 data in near real-time on a U.S. national scale, in order to support state management agencies in protecting public health and the environment.

Investigating the spring bloom initiation and net community production in the Subantarctic Southern Ocean using high-resolution in situ glider data

NASA Astrophysics Data System (ADS)

thomalla, sandy; Racault, Marie-Fanny; Swart, Sebastiaan; Monteiro, Pedro

2014-05-01

Phytoplankton bloom phenology has important consequences for marine ecosystems, fisheries and carbon export to the ocean interior. As such, it is important to examine the drivers of phytoplankton bloom initiation and their sensitivity to inter-annual climate variability and change. In this study we use ~6 months of in-situ high-resolution glider data to investigate the spring bloom initiation in the subantarctic zone (SAZ) of the Southern Ocean by implementing three different methods; a rate of change method, a threshold method and a cumulative sum method. The bloom initiation dates are critically compared to one another and the drivers of discrepancies assessed to inform on the sensitivities of different methods to processes driving the seasonal evolution of phytoplankton biomass in the subantarctic. The bloom initiation dates combined with in situ glider data of chlorophyll, light, and mixed layer depth allow us to resolve both Sverdrup's Critical Depth and Behrenfeld's Disturbance Recovery models through the water column and thus determine the seasonal evolution of net community production and respiration rates and the potential for carbon export. The outputs of the two different models are compared to one another in the context of their sensitivities to water column processes thereby refining their ability to address specific system scale questions. The novelty of this study is that gliders provide an unprecedented dataset to assess the seasonal cycle of phytoplankton biomass throughout the water column at high resolution, thus enhancing our understanding of net community production and export processes at submeso-space and sub-seasonal time scales.

[Effects of outbreak and extinction of algal blooms on the microbial community structure in sediments of Chaohu Lake].

PubMed

Diao, Xiao-jun; Li, Yi-wei; Wang, Shu-guang

2015-01-01

Although impacts of algal bloom on the physicochemical and biological properties of water and sediment in many lakes have been largely studied, less attention is paid to the impact of outbreak and extinction of algal blooms on the microbial community structure in sediment. In this study, outbreak and extinction of algal blooms and their effects on the microbial community structure in sediment of Chaohu Lake were studied by PCR-DGGE method. The results showed that algal blooms formed between May 15 and June 20, sustained from June 20 to September 5, and then went into extinction. In the region without algal blooms, PCR-DGGE analysis showed that microbial species, Shannon-Wiener diversity index and Simpson dominance index changed slightly over time; moreover, the microbial community structure had high similarity during the whole study. Temperature may be the main factor affecting the fluctuation of the microbial community structure in this region. In the region with algal blooms, however, microbial species and Shannon-Wiener diversity index were higher during the formation and extinction of algal blooms and lower in the sustaining blooms stage than those in the region without algal blooms. But the Simpson dominance index showed the opposite trend over time. In addition, the microbial community structure had low similarity during the whole study. The results suggested that outbreak and extinction of algal blooms produced different effects on the microbial community structure and the dominant microbial species, which may be related to the variation of water properties caused by temperature and algal blooms. This study showed that outbreak and extinction of algal blooms caused different effects on microbes in lake sediment, and this is significantly important to deeply evaluate the effects of algal bloom on the aquatic ecosystem of the lake and effectively control algal blooms using sediment microbes.

Blooms of Cochlodinium polykrikoides (Gymnodiniaceae) in the Gulf of California, Mexico.

PubMed

Gárate-Lizárraga, I; López-Cortes, D J; Bustillos-Guzmán, J J; Hernández-Sandoval, F

2004-09-01

Cochlodinium polykrikoides was the species responsible for the discoloration that occurred between September 15th and 27th, 2000 in a shallow coastal lagoon located in the southern part of the Bahia de La Paz, on the west side of the Gulf of California. Blooms of C. polykrikoides were observed four days after two rainy days with a seawater temperature of 29 to 31 degrees C. Nutrient concentration ranges during the bloom were 0.165-0.897 microM NO2+NO3, 0.16-3.25 microM PO4, and 1.0-35.36 microM SiO4. Abundance of C. polykrikoides ranged from 360 x 10(3) to 7.05 x 10(6)/cells l(-1). Biomass expressed in terms of chlorophyll a was high, ranging from 2.7 to 56.8 mg/m3. A typical dinoflagellate pigment profile (chlorophyll a and c, peridinin, diadinoxantin, and beta-carotene) was recorded. In this study, the red tide occurred in front of several fish and shrimp-culture ponds. No PST toxins were found in the samples. However, 180 fish were found dead in the infected fish-pond; the gills were the most affected part. C. polykrikoides is a cyst-forming species that recurs in this area. New blooms were observed in November 2000 and September-November 2001 in the same area. Anthropogenic activities, such as eutrophication caused by water discharge in this shallow lagoon, and nutrient enrichment in the culture ponds, as well as effects from precipitation and wind stress, could have favored the outbreak of this dinoflagellate.

Cyanobacteria as indicators of water quality in Campania coasts, Italy: a monitoring strategy combining remote/proximal sensing and in situ data

NASA Astrophysics Data System (ADS)

Teta, Roberta; Romano, Vincenza; Della Sala, Gerardo; Picchio, Stefano; De Sterlich, Carlo; Mangoni, Alfonso; Di Tullio, Giacomo; Costantino, Valeria; Lega, Massimiliano

2017-02-01

Cyanobacterial blooms (CBs) are generally triggered by eutrophic conditions due to anthropogenic nutrient inputs to local waters (wastewater or contaminated waters). During the bloom, some species produce toxic secondary metabolites (cyanotoxins) that are dangerous for humans and animals. Here, a multidisciplinary strategy for an early detection and constant monitoring is proposed. This strategy combines remote/proximal sensing technology with analytical/biotechnological analyses. To demonstrate the applicability of this strategy, four anthropogenically-impacted sites were selected along the Campania coast of southwestern Italy, in the so called ‘Land of Fires’. The sites were observed using satellite and aircraft images during summer, 2015. Algal community composition was determined using spectrophotometric analysis for the detection of the cyanobacterial pigment phycocyanin (PC). Complementary metagenomic analysis revealed the taxonomic presence of cyanobacteria belonging to genera associated with strong eutrophic conditions. Key elements of this strategy are the combination and integration of applying different methodological approaches such as the parallel and combined use of satellite, aerial and in-situ data, the simplified multispectral image indexing and classification for a truly efficient method in detecting early blooms of cyanobacteria. The effectiveness of the strategy has been validated also by the specific taxa of cyanobacteria found in the examined areas that confirm the assumption that cyanobacterial blooms may serve as useful bioindicators of degraded water quality in coastal ecosystems. To our knowledge this is the first time that the presence of cyanobacteria has been observed in water bodies along the Campania coast.

A multiomics approach to study the microbiome response to phytoplankton blooms.

PubMed

Song, Liyan

2017-06-01

Phytoplankton blooms are predictable features of marine and freshwater habitats. Despite a good knowledge base of the environmental factors controlling blooms, complex interactions between the bacterial and archaeal communities and phytoplankton bloom taxa are only now emerging. Here, the current research on bacterial community's structural and functional response to phytoplankton blooms is reviewed and discussed and further research is proposed. More attention should be paid on structure and function of autotrophic bacteria and archaea during phytoplankton blooms. A multiomics integration approach is needed to investigate bacterial and archaeal communities' diversity, metabolic diversity, and biogeochemical functions of microbial interactions during phytoplankton blooms.

Phytoplankton bloom dynamics in coastal ecosystems: A review with some general lessons from sustained investigation of San Francisco Bay, California

USGS Publications Warehouse

Cloern, James E.

1996-01-01

Phytoplankton blooms are prominent features of biological variability in shallow coastal ecosystems such as estuaries, lagoons, bays, and tidal rivers. Long-term observation and research in San Francisco Bay illustrates some patterns of phytoplankton spatial and temporal variability and the underlying mechanisms of this variability. Blooms are events of rapid production and accumulation of phytoplankton biomass that are usually responses to changing physical forcings originating in the coastal ocean (e.g., tides), the atmosphere (wind), or on the land surface (precipitation and river runoff). These physical forcings have different timescales of variability, so algal blooms can be short-term episodic events, recurrent seasonal phenomena, or rare events associated with exceptional climatic or hydrologic conditions. The biogeochemical role of phytoplankton primary production is to transform and incorporate reactive inorganic elements into organic forms, and these transformations are rapid and lead to measurable geochemical change during blooms. Examples include the depletion of inorganic nutrients (N, P, Si), supersaturation of oxygen and removal of carbon dioxide, shifts in the isotopic composition of reactive elements (C, N), production of climatically active trace gases (methyl bromide, dimethylsulfide), changes in the chemical form and toxicity of trace metals (As, Cd, Ni, Zn), changes in the biochemical composition and reactivity of the suspended particulate matter, and synthesis of organic matter required for the reproduction and growth of heterotrophs, including bacteria, zooplankton, and benthic consumer animals. Some classes of phytoplankton play special roles in the cycling of elements or synthesis of specific organic molecules, but we have only rudimentary understanding of the forces that select for and promote blooms of these species. Mounting evidence suggests that the natural cycles of bloom variability are being altered on a global scale by human activities including the input of toxic contaminants and nutrients, manipulation of river flows, and translocation of species. This hypothesis will be a key component of our effort to understand global change at the land-sea interface. Pursuit of this hypothesis will require creative approaches for distinguishing natural and anthropogenic sources of phytoplankton population variability, as well as recognition that the modes of human disturbance of coastal bloom cycles operate interactively and cannot be studied as isolated processes.

Climate Change and Algal Blooms =

NASA Astrophysics Data System (ADS)

Lin, Shengpan

Algal blooms are new emerging hazards that have had important social impacts in recent years. However, it was not very clear whether future climate change causing warming waters and stronger storm events would exacerbate the algal bloom problem. The goal of this dissertation was to evaluate the sensitivity of algal biomass to climate change in the continental United States. Long-term large-scale observations of algal biomass in inland lakes are challenging, but are necessary to relate climate change to algal blooms. To get observations at this scale, this dissertation applied machine-learning algorithms including boosted regression trees (BRT) in remote sensing of chlorophyll-a with Landsat TM/ETM+. The results show that the BRT algorithm improved model accuracy by 15%, compared to traditional linear regression. The remote sensing model explained 46% of the total variance of the ground-measured chlorophyll- a in the first National Lake Assessment conducted by the US Environmental Protection Agency. That accuracy was ecologically meaningful to study climate change impacts on algal blooms. Moreover, the BRT algorithm for chlorophyll- a would not have systematic bias that is introduced by sediments and colored dissolved organic matter, both of which might change concurrently with climate change and algal blooms. This dissertation shows that the existing atmospheric corrections for Landsat TM/ETM+ imagery might not be good enough to improve the remote sensing of chlorophyll-a in inland lakes. After deriving long-term algal biomass estimates from Landsat TM/ETM+, time series analysis was used to study the relations of climate change and algal biomass in four Missouri reservoirs. The results show that neither temperature nor precipitation was the only factor that controlled temporal variation of algal biomass. Different reservoirs, even different zones within the same reservoir, responded differently to temperature and precipitation changes. These findings were further tested in 1157 lakes across the continental United States. The results show that mean annual algal biomass generally increased with annual temperature. Greater increase was found in lakes with more nutrients. Mean annual algal biomass generally decreased with annual total precipitation. In both the "low" and the "high" greenhouse-gas emission scenarios, mean annual algal biomass in lakes generally increased with climate change, and greater increases are predicted from the high emission scenario.

The western North Atlantic bloom experiment

NASA Astrophysics Data System (ADS)

Harrison, W. G.; Head, E. J. H.; Horne, E. P. W.; Irwin, B.; Li, W. K. W.; Longhurst, A. R.; Paranjape, M. A.; Platt, T.

An investigation of the spring bloom was carried out in the western North Atlantic (40-50°W) as one component of the multi-nation Joint Global Ocean Flux Study (JGOFS) North Atlantic Bloom Experiment (NABE). The cruise track included an extended hydrographic section from 32 to 47°N and process studies at two week-long time-series stations at 40 and 45°N. Biological and chemical data collected along the transect indicated that the time-series stations were located in regions where the spring bloom was well developed; algal biomass was high and surface nutrient concentrations were reduced from maximum wintertime levels. Despite similarities in the vertical structure and magnitude of phytoplankton biomass and productivity, the two stations clearly differed in physical, chemical and other biological characteristics. Detailed depth profiles of the major autotrophic and heterotrophic microplankton groups (bacteria, phytoplankton, microzooplankton) revealed a strong vertical coherence in distribution at both sites, with maximum concentrations in the upper 50 m being typical of the spring bloom. Ultraplankton (< 10 μm) were an important component of the primary producers at 40°N, whereas larger netplankton (diatoms, dinoflagellates) were more important at 45°N. Silicate depletion was clearly evident in surface waters at 45°N, where diatoms were most abundant. Despite the relative importance of diatoms at 45°N, dinoflagellates dominated the biomass of the netplankton at both sites; however, much of this community may have been heterotrophic. Bacterial biomass and production were high at both stations relative to phytoplankton levels, particularly at 45°N, and may have contributed to the unexpectedly high residual ammonium concentrations observed below the chlorophyll maximum layer at both stations. Microzooplankton grazing dominated phytoplankton losses at both stations, with consumption as high as 88% of the daily primary production. Grazing losses to the mesozooplankton, on the other hand, were small (<10%), but mesozooplankton contribution to the vertical flux of organic matter (fecal pellets) was important at 45°N. F-ratios estimated by 15N tracer methods and sediment trap fluxes were similar and suggeste that ˜30% of the daily primary production was lost by direct sedimentation during the observation period. Numerous similarities in bloom characteristics were noted between the western and eastern Atlantic study sites.

Seasonal and interannual variabilities of coccolithophore blooms in the Bay of Biscay and the Celtic Sea observed from a 18-year time-series of non-algal Suspended Particulate Matter images

NASA Astrophysics Data System (ADS)

Perrot, Laurie; Gohin, Francis; Ruiz-Pino, Diana; Lampert, Luis

2016-04-01

Coccolithophores belong to the nano-phytoplankton size-class and produce CaCO3 scales called coccoliths which form the «shell» of the algae cell. Coccoliths are in the size range of a few μm and can also be detached from the cell in the water. This phytoplankton group has an ubiquitous distribution in all oceans but blooms only in some oceanic regions, like the North East Atlantic ocean and the South Western Atlantic (Patagonian Sea). At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis. As the oceans are more and more acidified by anthropogenic CO2 emissions, coccolithophores generally are expected to be negatively affected. However, recent studies have shown an increase in coccolithophore occurrence in the North Atlantic. A poleward expansion of the coccolithophore Emiliana Huxleyi has also been pointed out. By using a simplified fuzzy method applied to a 18-year time series of SeaWiFS (1998-2002) and MODIS (2003-2015) spectral reflectance, we assessed the seasonal and inter-annual variability of coccolithophore blooms in the vicinity of the shelf break in the Bay of Biscay and the Celtic Sea After identification of the coccolith pixels by applying the fuzzy method, the abundance of coccoliths is assessed from a database of non-algal Suspended Particulate Matter (SPM). Although a regular pattern in the phenology of the blooms is observed, starting south in April in Biscay and moving northwards until July in Ireland, there is a high seasonal and interannual variability in the extent of the blooms. Year 2014 shows very low concentrations of detached coccoliths (twice less than average) from space and anomalies point out the maximum level in 2001. Non-algal SPM, derived from a procedure defined for the continental shelf, appears to be well related to the calcite concentration provided by NASA, and correlates better with coccolith than coccosphere in-situ data.

Characterization of oceanic Noctiluca blooms not associated with hypoxia in the Northeastern Arabian Sea.

PubMed

Lotliker, Aneesh A; Baliarsingh, S K; Trainer, Vera L; Wells, Mark L; Wilson, Cara; Udaya Bhaskar, T V S; Samanta, Alakes; Shahimol, S R

2018-04-01

Intense blooms of the heterotrophic dinoflagellate, green Noctiluca scintillans, have been reported annually in the Northern Arabian Sea since the early 2000s. Although not known to produce organic toxins, these blooms are still categorized as a harmful due to their association with massive fish mortalities. Recent work has attributed these blooms to the vertical expansion of the oxygen minimum zone, driven by cultural eutrophication from major coastal cities in western India. As diatoms are preferred prey of green Noctiluca scintillans, more frequent blooms of this mixotroph will likely impact the productivity of important fisheries in the region. The present study uses a satellite algorithm to determine the distribution of both diatom and green Noctiluca blooms in the Northeastern Arabian Sea from 2009 to 2016. The results from shipboard microscopy of phytoplankton community composition were used to validate the satellite estimates. The satellite algorithm showed 76% accuracy for detection of green Noctiluca and 92% for diatoms. Shipboard measurements and data from biogeochemical-Argo floats were used to assess the relationship between oxygen concentrations and green Noctiluca blooms in the Northeastern Arabian Sea. Regardless of the presence of a Noctiluca bloom, the dissolved oxygen in the photic zone was always >70% saturated, with an average oxygen saturation >90%. The variability in the relative abundance of diatoms and green Noctiluca is not correlated with changes in oxygen concentration. These findings provide no evidence that cultural eutrophication has contributed to the decadal scale shifts in plankton composition in the Northeastern Arabian Sea oceanic waters. Conversely, the climatic warming of surface waters would have intensified stratification, thereby reducing net nutrient flux to the photic zone and decreasing silicate to nitrate ratios (Si:N); both factors that could increase the competitive advantage of the mixotroph, green Noctiluca, over diatoms. If so, the decadal-scale trajectory of phytoplankton community composition in the Northeastern Arabian Sea may be a harbinger of future climate-driven change in other productive oceanic systems. Copyright © 2018 Elsevier B.V. All rights reserved.

Monitoring for Harmful Algal Blooms in Influent Waters and Through Treatment on Lake Erie in the 2013 and 2014 Bloom Seasons 

EPA Science Inventory

Monitoring of Harmful Algal Blooms in Influent and Through Drinking Water Treatment Facilities Located on Lake Erie in the 2013 and 2014 Bloom SeasonsToby Sanan, Nicholas Dugan, Darren Lytle, Heath MashHarmful algal blooms (HABs) and their associated toxins are emerging as signif...

Field and laboratory guide to freshwater cyanobacteria harmful algal blooms for Native American and Alaska Native communities

USGS Publications Warehouse

Rosen, Barry H.; St. Amand, Ann

2015-09-14

Cyanobacteria can produce toxins and form harmful algal blooms. The Native American and Alaska Native communities that are dependent on subsistence fishing have an increased risk of exposure to these cyanotoxins. It is important to recognize the presence of an algal bloom in a waterbody and to distinguish a potentially toxic harmful algal bloom from a non-toxic bloom. This guide provides field images that show cyanobacteria blooms, some of which can be toxin producers, as well as other non-toxic algae blooms and floating plants that might be confused with algae. After recognition of a potential toxin-producing cyanobacterial bloom in the field, the type(s) of cyanobacteria present needs to be identified. Species identification, which requires microscopic examination, may help distinguish a toxin-producer from a non-toxin producer. This guide also provides microscopic images of the common cyanobacteria that are known to produce toxins, as well as images of algae that form blooms but do not produce toxins.

Phytoplankton bloom off Newfoundland

NASA Image and Video Library

2017-12-08

NASA image acquired August 9, 2010 Phytoplankton are microscopic organisms that live in watery environments. When conditions are right, phytoplankton undergo explosive population growth, creating blooms visible from space. Such a bloom occurred in the North Atlantic Ocean, off the coast of Newfoundland in early August 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on August 9, 2010. The paisley pattern of peacock blue owes its color to phytoplankton. Phytoplankton thrive at high latitudes, especially in the spring and summer when abundant sunlight spurs photosynthesis, and relatively calm seas allow the tiny organisms to congregate in sunlit waters. Blooms can last for weeks even though an individual phytoplankton lifespan may be just a few days. NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team Click here to see more images from MODIS NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Allelopathic interactions of linoleic acid and nitric oxide increase the competitive ability of Microcystis aeruginosa

PubMed Central

Song, Hao; Lavoie, Michel; Fan, Xiaoji; Tan, Hana; Liu, Guangfu; Xu, Pengfei; Fu, Zhengwei; Paerl, Hans W; Qian, Haifeng

2017-01-01

The frequency and intensity of cyanobacterial blooms are increasing worldwide with major societal and economic costs. Interactions between toxic cyanobacteria and eukaryotic algal competitors can affect toxic bloom formation, but the exact mechanisms of interspecies interactions remain unknown. Using metabolomic and proteomic profiling of co-cultures of the toxic cyanobacterium Microcystis aeruginosa with a green alga as well as of microorganisms collected in a Microcystis spp. bloom in Lake Taihu (China), we disentangle novel interspecies allelopathic interactions. We describe an interspecies molecular network in which M. aeruginosa inhibits growth of Chlorella vulgaris, a model green algal competitor, via the release of linoleic acid. In addition, we demonstrate how M. aeruginosa takes advantage of the cell signaling compound nitric oxide produced by C. vulgaris, which stimulates a positive feedback mechanism of linoleic acid release by M. aeruginosa and its toxicity. Our high-throughput system-biology approach highlights the importance of previously unrecognized allelopathic interactions between a broadly distributed toxic cyanobacterial bloom former and one of its algal competitors. PMID:28398349

Satellite Remote Sensing of Harmful Algal Blooms (HABs) and a Potential Synthesized Framework

PubMed Central

Shen, Li; Xu, Huiping; Guo, Xulin

2012-01-01

Harmful algal blooms (HABs) are severe ecological disasters threatening aquatic systems throughout the World, which necessitate scientific efforts in detecting and monitoring them. Compared with traditional in situ point observations, satellite remote sensing is considered as a promising technique for studying HABs due to its advantages of large-scale, real-time, and long-term monitoring. The present review summarizes the suitability of current satellite data sources and different algorithms for detecting HABs. It also discusses the spatial scale issue of HABs. Based on the major problems identified from previous literature, including the unsystematic understanding of HABs, the insufficient incorporation of satellite remote sensing, and a lack of multiple oceanographic explanations of the mechanisms causing HABs, this review also attempts to provide a comprehensive understanding of the complicated mechanism of HABs impacted by multiple oceanographic factors. A potential synthesized framework can be established by combining multiple accessible satellite remote sensing approaches including visual interpretation, spectra analysis, parameters retrieval and spatial-temporal pattern analysis. This framework aims to lead to a systematic and comprehensive monitoring of HABs based on satellite remote sensing from multiple oceanographic perspectives. PMID:22969372

High abundance and diversity of consumers associated with eutrophic areas in a semi-desert macrotidal coastal ecosystem in Patagonia, Argentina

NASA Astrophysics Data System (ADS)

Martinetto, Paulina; Daleo, Pedro; Escapa, Mauricio; Alberti, Juan; Isacch, Juan Pablo; Fanjul, Eugenia; Botto, Florencia; Piriz, Maria Luz; Ponce, Gabriela; Casas, Graciela; Iribarne, Oscar

2010-07-01

Here we evaluated the response to eutrophication in terms of abundance and diversity of flora and fauna in a semi-desert macrotidal coastal system (San Antonio bay, Patagonia, Argentina, 40° 48' S) where signs of eutrophication (high nutrient concentration, seaweed blooms, high growth rate of macroalgae) have been reported. We compared abundances and species composition of macroalgae, small infaunal and epifaunal invertebrates, and birds associated with tidal channels of the San Antonio Bay subject to contrasting anthropogenic influence. Macroalgae were more abundant and diverse in the channel closer to human activity where nutrient concentrations were also higher. In contrast to what others have observed in eutrophic sites, small invertebrates and birds were also more abundant and diverse in the channel with macroalgal blooms and high nutrient concentration. The large water flushing during the tidal cycle could prevent anoxic or hypoxic events, making the environment suitable for consumers. Thus, this could be a case in which eutrophication supports high densities of consumers by increasing food availability, rather than negatively affecting the survival of organisms.

Temperature-Induced Viral Resistance in Emiliania huxleyi (Prymnesiophyceae)

PubMed Central

Kendrick, B. Jacob; DiTullio, Giacomo R.; Cyronak, Tyler J.; Fulton, James M.; Van Mooy, Benjamin A. S.; Bidle, Kay D.

2014-01-01

Annual Emiliania huxleyi blooms (along with other coccolithophorid species) play important roles in the global carbon and sulfur cycles. E. huxleyi blooms are routinely terminated by large, host-specific dsDNA viruses, (Emiliania huxleyi Viruses; EhVs), making these host-virus interactions a driving force behind their potential impact on global biogeochemical cycles. Given projected increases in sea surface temperature due to climate change, it is imperative to understand the effects of temperature on E. huxleyi’s susceptibility to viral infection and its production of climatically active dimethylated sulfur species (DSS). Here we demonstrate that a 3°C increase in temperature induces EhV-resistant phenotypes in three E. huxleyi strains and that successful virus infection impacts DSS pool sizes. We also examined cellular polar lipids, given their documented roles in regulating host-virus interactions in this system, and propose that alterations to membrane-bound surface receptors are responsible for the observed temperature-induced resistance. Our findings have potential implications for global biogeochemical cycles in a warming climate and for deciphering the particular mechanism(s) by which some E. huxleyi strains exhibit viral resistance. PMID:25405345

Temperature-induced viral resistance in Emiliania huxleyi (Prymnesiophyceae).

PubMed

Kendrick, B Jacob; DiTullio, Giacomo R; Cyronak, Tyler J; Fulton, James M; Van Mooy, Benjamin A S; Bidle, Kay D

2014-01-01

Annual Emiliania huxleyi blooms (along with other coccolithophorid species) play important roles in the global carbon and sulfur cycles. E. huxleyi blooms are routinely terminated by large, host-specific dsDNA viruses, (Emiliania huxleyi Viruses; EhVs), making these host-virus interactions a driving force behind their potential impact on global biogeochemical cycles. Given projected increases in sea surface temperature due to climate change, it is imperative to understand the effects of temperature on E. huxleyi's susceptibility to viral infection and its production of climatically active dimethylated sulfur species (DSS). Here we demonstrate that a 3°C increase in temperature induces EhV-resistant phenotypes in three E. huxleyi strains and that successful virus infection impacts DSS pool sizes. We also examined cellular polar lipids, given their documented roles in regulating host-virus interactions in this system, and propose that alterations to membrane-bound surface receptors are responsible for the observed temperature-induced resistance. Our findings have potential implications for global biogeochemical cycles in a warming climate and for deciphering the particular mechanism(s) by which some E. huxleyi strains exhibit viral resistance.

Changes in N:P stoichiometry influence taxonomic composition and nutritional quality of phytoplankton in the Peruvian upwelling

NASA Astrophysics Data System (ADS)

Hauss, Helena; Franz, Jasmin M. S.; Sommer, Ulrich

2012-10-01

Inorganic dissolved macronutrient (nitrogen, N, and phosphorus, P) supply to surface waters in the eastern tropical South Pacific is influenced by expanding oxygen minimum zones, since N loss occurs due to microbial processes under anoxic conditions while P is increasingly released from the shelf sediments. To investigate the impact of decreasing N:P supply ratios in the Peruvian Upwelling, we conducted nutrient manipulation experiments using a shipboard mesocosm setup with a natural phytoplankton community. In a first experiment, either N or P or no nutrients were added with mesozooplankton present or absent. In a second experiment, initial nutrient concentrations were adjusted to four N:P ratios ranging from 2.5 to 16 using two "high N" and two "high P" levels in combination (i.e., + N, + P, + N and P, no addition). Over six and seven days, respectively, microalgal biomass development as well as nutrient uptake was monitored. Phytoplankton biomass strongly responded to N addition, in both mesozooplankton-grazed and not grazed treatments. The developing diatom bloom in the "high N" exceeded that in the "low N" treatments by a factor of two. No modulation of the total biomass by P-addition was observed, however, species-specific responses were more variable. Notably, some organisms were able to benefit from low N:P fertilization ratios, especially Heterosigma sp. and Phaeocystis globosa which are notorious for forming blooms that are toxic or inadequate for mesozooplankton nutrition. After the decline of the diatom bloom, the relative contribution of unsaturated fatty acid to the lipid content of seston was positively correlated to diatom biomass in the peak bloom, indicating that positive effects of diatom blooms on food quality of the protist community to higher trophic levels remain even after the phytoplankton biomass was incorporated by grazers. Our results indicate an overall N-limitation of the system, especially in the case of dominating diatoms, which were able to immediately utilize the available nitrate (within two days) and develop a biomass maximum within three days of incubation. After the decline of diatom biomass, detection of the cyanobacterial marker pigment aphanizophyll indicated the occurrence of diazotrophs, especially in those enclosures initially provided with high N supply. This was surprising, as diazotrophs are thought to play a role in compensating to some extent the N deficit above OMZs in the succession of phytoplankton after an upwelling event.

Spring and fall bloom evolutions estimated from 8 day composite satellite chlorophyll data in the East/Japan Sea

NASA Astrophysics Data System (ADS)

Kim, B.; Cho, Y.; Kim, S.; Kim, K.

2012-12-01

Bong-Guk Kim1, Yang-Ki Cho1, Sangil Kim2, Kwang-Yul, Kim1 1 School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul, South Korea 2 College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA To understand the ocean carbon cycle, estimating the ocean biomass is necessary and it has been done by various methods. Satellite observation is one of beneficial methods to investigate ocean biomass. Satellite data enable us to monitor chlorophyll-a for wide area with high resolution and frequency. The East/Japan Sea, which called as 'miniature ocean' due to its rapid turnover circulation, is one of the most productive ocean. With the concerning global warming, a number of studies on temporal and spatial distribution of satellite chlorophyll in the East/Japan Sea have been processed. However, most of these studies have used monthly data set which can not resolve detail evolution of chlorophyll-a. In this study, detail evolutions of spring and fall bloom are investigated by the CSEOF (Cyclo-Stationary EOF) analysis of 8-day composite MODIS chlorophyll data from July 2002 to February 2012. For the CSEOF analysis, optimal interpolation (OI) method was applied to fill the blank data which is critical problem in satellite data. Spring bloom started at western Japanese coast on 57th day of the year. And it gradually moves eastern coast of Korean and then moves to northern Primorye coast. Spring bloom spreads entire the East/Japan Sea on 113th day of the year and then, it disappears from the southern East/Japan Sea. Spring bloom ends in the northern East/Japan Sea. In the case of fall bloom, it starts at Korean coast on 265th day of the year, and it moves to the north along the Korean coast by 329th day of the year. After that day, fall bloom ends near the northern coast of Korea on 353rd day of the year.

Cadmium and phosphate variability during algal blooms of the dinoflagellate Lingulodinium polyedrum in Todos Santos Bay, Baja California, Mexico.

PubMed

Gutierrez-Mejia, E; Lares, M L; Huerta-Diaz, M A; Delgadillo-Hinojosa, F

2016-01-15

Dinoflagellate algal blooms (DABs), with Lingulodinium polyedrum as the dominant species, have increased over the past few years in coastal areas off Baja California, Mexico. Vertical and temporal variability of particulate cadmium (Cdp), dissolved Cd (Cdd), PO4(3-) and Cdd/PO4(3-) were investigated during two intense DABs of L. polyedrum that occurred during the fall of 2011 and 2012 in Todos Santos Bay. Results were then, compared with data gathered in the absence of algal blooms during the autumn of 2013. In both algal blooms, L. polyedrum tended to be concentrated near the surface throughout the duration; however, during DAB 2011 the number of cells was twice as abundant ([10.0 ± 8.0] × 10(5) cells L(-1)) as in DAB 2012 ([5.0 ± 4.4] × 10(5) cells L(-1)). During DAB 2011, Cdp increased significantly (up to 1.02 ± 0.99 nmol kg(-1)) and was positively correlated with the cell abundance of L. polyedrum, suggesting that this dinoflagellate is able to assimilate and concentrate Cdd. Likewise, Cdd (up to 0.71 ± 0.17 nM) increased in the days of highest cell abundance, which could be attributed to uptake and subsequent regeneration of Cdd resulting from the remineralization of organic particulate matter produced during the bloom, as well as with the presence of organic ligands secreted by L. polyedrum that could keep Cdd in solution. During DAB 2011, dissolved Cdd/PO4(3-) ratios exhibited high vertical and temporal variability in the upper 5 m of the water column, but remained virtually constant near the bottom, suggesting a depth-dependent decoupling between these two dissolved components during the bloom development. Given the observed differences in the vertical and temporal variability of Cdd, Cdp, and PO4(3-) between these two intense DABs, we propose the existence of an abundance threshold of approximately 10(6) cells L(-1) of L. polyedrum above which Cd and PO4(3-) significantly increased due to remineralization in coastal waters during the bloom development.

Coccolithophorid blooms in the global ocean

NASA Technical Reports Server (NTRS)

Brown, Christopher W.; Yoder, James A.

1994-01-01

The global distribution pattern of coccolithophrid blooms was mapped in order to ascertain the prevalence of these blooms in the world's oceans and to estimate their worldwide production of CaCO3 and dimethyl sulfide (DMS). Mapping was accomplished by classifying pixels of 5-day global composites of coastal zone color scanner imagery into bloom and nonbloom classes using a supervised, multispectral classification scheme. Surface waters with the spectral signature of coccolithophorid blooms annually covered an average of 1.4 x 10(exp 6) sq km in the world oceans from 1979 to 1985, with the subpolar latitudes accounting for 71% of this surface area. Classified blooms were most extensive in the Subartic North Atlantic. Large expanses of the bloom signal were also detected in the North Pacific, on the Argentine shelf and slope, and in numerous lower latitude marginal seas and shelf regions. The greatest spatial extent of classified blooms in subpolar oceanic regions occurred in the months from summer to early autumn, while those in lower latitude marginal seas occurred in midwinter to early spring. Though the classification scheme was effcient in separating bloom and nonbloom classes during test simulations, and biogeographical literature generally confirms the resulting distribution pattern of blooms in the subpolar regions, the cause of the bloom signal is equivocal in some geographic areas, particularly on shelf regions at lower latitudes. Standing stock estimates suggest that the presumed Emiliania huxleyi blooms act as a significant source of calcite carbon and DMS sulfur on a regional scale. On a global scale, however, the satellite-detected coccolithophorid blooms are estimated to play only a minor role in the annual production of these two compounds and their flux from the surface mixed layer.

Ecosystem consequences of cyanobacteria in the northern Baltic Sea.

PubMed

Karjalainen, Miina; Engström-Ost, Jonna; Korpinen, Samuli; Peltonen, Heikki; Pääkkönen, Jari-Pekka; Rönkkönen, Sanna; Suikkanen, Sanna; Viitasalo, Markku

2007-04-01

Cyanobacteria of the Baltic Sea have multiple effects on organisms that influence the food chain dynamics on several trophic levels. Cyanobacteria contain several bioactive compounds, such as alkaloids, peptides, and lipopolysaccharides. A group of nonribosomally produced oligopeptides, namely microcystins and nodularin, are tumor promoters and cause oxidative stress in the affected cells. Zooplankton graze on cyanobacteria, and when ingested, the hepatotoxins (nodularin) decrease the egg production of, for example, copepods. However, the observed effects are very variable, because many crustaceans are tolerant to nodularin and because cyanobacteria may complement the diet of grazers in small amounts. Cyanobacterial toxins are transferred through the food web from one trophic level to another. The transfer rate is relatively low in the pelagic food web, but reduced feeding and growth rates of fish larvae have been observed. In the benthic food web, especially in blue mussels, nodularin concentrations are high, and benthic feeding juvenile flounders have been observed to disappear from bloom areas. In the littoral ecosystem, gammarids have shown increased mortality and weakening of reproductive success under cyanobacterial exposure. In contrast, mysid shrimps seem to be tolerant to cyanobacterial exposure. In fish larvae, detoxication of nodularin poses a metabolic cost that is reflected as decreased growth and condition, which may increase their susceptibility to predation. Cyanobacterial filaments and aggregates also interfere with both hydromechanical and visual feeding of planktivores. The feeding appendages of mysid shrimps may clog, and the filaments interfere with prey detection of pike larvae. On the other hand, a cyanobacterial bloom may provide a refuge for both zooplankton and small fish. As the decaying bloom also provides an ample source of organic carbon and nutrients for the organisms of the microbial loop, the zooplankton species capable of selective feeding may thrive in bloom conditions. Cyanobacteria also compete for nutrients with other primary producers and change the nitrogen (N): phosphorus (P) balance of their environment by their N-fixation. Further, the bioactive compounds of cyanobacteria directly influence other primary producers, favoring cyanobacteria, chlorophytes, dinoflagellates, and nanoflagellates and inhibiting cryptophytes. As the selective grazers also shift the grazing pressure on other species than cyanobacteria, changes in the structure and functioning of the Baltic Sea communities and ecosystems are likely to occur during the cyanobacterial bloom season.

The dynamics of temperature and light on the growth of phytoplankton.

PubMed

Chen, Ming; Fan, Meng; Liu, Rui; Wang, Xiaoyu; Yuan, Xing; Zhu, Huaiping

2015-11-21

Motivated by some lab and field observations of the hump shaped effects of water temperature and light on the growth of phytoplankton, a bottom-up nutrient phytoplankton model, which incorporates the combined effects of temperature and light, is proposed and analyzed to explore the dynamics of phytoplankton bloom. The population growth model reasonably captures such observed dynamics qualitatively. An ecological reproductive index is defined to characterize the growth of the phytoplankton which also allows a comprehensive analysis of the role of temperature and light on the growth and reproductive characteristics of phytoplankton in general. The model provides a framework to study the mechanisms of phytoplankton dynamics in shallow lake and may even be employed to study the controlled phytoplankton bloom. Copyright © 2015 Elsevier Ltd. All rights reserved.

STS-32 Earth observation of the western Coral Sea and the Great Barrier Reef

NASA Technical Reports Server (NTRS)

1990-01-01

STS-32 Earth observation taken onboard Columbia, Orbiter Vehicle (OV) 102, is of the western Coral Sea and the Great Barrier Reef. The scene shows phytoplankton or algal bloom in the northwest Coral Sea. The western Coral Sea and the Great Barrier Reef waters offshore Queensland, Australia are the sites of some of the larger concentrations or 'blooms' of phytoplankton and algae in the open ocean. In the instance illustrated here, the leading edge of a probable concentration of algae or phytoplankton is seen as a light irregular line and sheen between the offshore Great Barrier Reef and the Queensland coast. Previous phytoplankton concentrations in this area have been reported by ships at sea as having formed floating mats as thick as two meters.

Evolution of diffraction and self-diffraction phenomena in thin films of Gelite Bloom/Hibiscus Sabdariffa

NASA Astrophysics Data System (ADS)

Cano-Lara, Miroslava; Severiano-Carrillo, Israel; Trejo-Durán, Mónica; Alvarado-Méndez, Edgar

2017-09-01

In this work, we present a study of non-linear optical response in thin films elaborated with Gelite Bloom and extract of Hibiscus Sabdariffa. Non-linear refraction and absorption effects were studied experimentally (Z-scan technique) and numerically, by considering the transmittance as non-linear absorption and refraction contribution. We observe large phase shifts to far field, and diffraction due to self-phase modulation of the sample. Diffraction and self-diffraction effects were observed as time function. The aim of studying non-linear optical properties in thin films is to eliminate thermal vortex effects that occur in liquids. This is desirable in applications such as non-linear phase contrast, optical limiting, optics switches, etc. Finally, we find good agreement between experimental and theoretical results.

Variable primary producer responses to nutrient and ...

EPA Pesticide Factsheets

Mesocosm experiments have been used to evaluate the impacts of nutrient loading on estuarine plant communities in order to develop nutrient response relationships. Mesocosm eutrophication studies tend to focus on long residence time systems. In the Pacific Northwest, many estuaries have high nutrient loads, short water residence times, seasonal macroalgal blooms, while intertidal seagrass meadows persist under what appear to be largely naturally-derived eutrophic conditions. Using experimental mesocosms, we examined how primary producer communities in rapidly flushed systems respond to a range of temperature (10 and 20 °C) and nutrient loads (ambient, 1.5, 3 and 6 x ambient). Thermal and nutrient loading regimes were maintained for three sets of 3 week-duration experiments during the summer of 2013. Statistical analysis was performed using an information criterion approach to evaluate the best fit model. Green macroalgal (GMA) growth and tissue N increased in response to nutrient loading. Irrespective of nutrient load, GMA at 10 °C remained intercalated among seagrass shoots, but at 20 °C formed floating mats that overtopped seagrass. Outgassing of O2 in combination with photosynthetic O2 production likely induced floating mat formation. No phytoplankton blooms were observed. Zostera japonica leaf biomass and C:N responded to temperature while other metrics exhibited no statistically significant difference. Z. marina growth, wasting disease, and morphological

Isolation by Time During an Arctic Phytoplankton Spring Bloom.

PubMed

Tammilehto, Anna; Watts, Phillip C; Lundholm, Nina

2017-03-01

The arctic phytoplankton spring bloom, which is often diatom-dominated, is a key event that provides the high latitude communities with a fundamental flux of organic carbon. During a bloom, phytoplankton may increase its biomass by orders of magnitude within days. Yet, very little is known about phytoplankton bloom dynamics, including for example how blooming affects genetic composition and diversity of a population. Here, we quantified the genetic composition and temporal changes of the diatom Fragilariopsis cylindrus, which is one of the most important primary producers in the Arctic, during the spring bloom in western Greenland, using 13 novel microsatellite markers developed for this study. We found that genetic differentiation (quantified using sample-specific F ST ) decreased between time points as the bloom progressed, with the most drastic changes in F ST occurring at the start of the bloom; thus the genetic structure of the bloom is characterized by isolation by time. There was little temporal variation in genetic diversity throughout the bloom (mean H E  = 0.57), despite marked fluctuations in F. cylindrus cell concentrations and the temporal change in sample-specific F ST . On the basis of this novel pattern of genetic differentiation, we suggest that blooming behavior may promote genetic diversity of a phytoplankton population. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

A model of phytoplankton blooms.

PubMed

Huppert, Amit; Blasius, Bernd; Stone, Lewi

2002-02-01

A simple model that describes the dynamics of nutrient-driven phytoplankton blooms is presented. Apart from complicated simulation studies, very few models reported in the literature have taken this "bottom-up" approach. Yet, as discussed and justified from a theoretical standpoint, many blooms are strongly controlled by nutrients rather than by higher trophic levels. The analysis identifies an important threshold effect: a bloom will only be triggered when nutrients exceed a certain defined level. This threshold effect should be generic to both natural blooms and most simulation models. Furthermore, predictions are given as to how the peak of the bloom Pmax is determined by initial conditions. A number of counterintuitive results are found. In particular, it is shown that increasing initial nutrient or phytoplankton levels can act to decrease Pmax. Correct predictions require an understanding of such factors as the timing of the bloom and the period of nutrient buildup before the bloom.

On the successful use of a simplified model to simulate the succession of toxic cyanobacteria in a hypereutrophic reservoir with a highly fluctuating water level.

PubMed

Fadel, Ali; Lemaire, Bruno J; Vinçon-Leite, Brigitte; Atoui, Ali; Slim, Kamal; Tassin, Bruno

2017-09-01

Many freshwater bodies worldwide that suffer from harmful algal blooms would benefit for their management from a simple ecological model that requires few field data, e.g. for early warning systems. Beyond a certain degree, adding processes to ecological models can reduce model predictive capabilities. In this work, we assess whether a simple ecological model without nutrients is able to describe the succession of cyanobacterial blooms of different species in a hypereutrophic reservoir and help understand the factors that determine these blooms. In our study site, Karaoun Reservoir, Lebanon, cyanobacteria Aphanizomenon ovalisporum and Microcystis aeruginosa alternatively bloom. A simple configuration of the model DYRESM-CAEDYM was used; both cyanobacteria were simulated, with constant vertical migration velocity for A. ovalisporum, with vertical migration velocity dependent on light for M. aeruginosa and with growth limited by light and temperature and not by nutrients for both species. The model was calibrated on two successive years with contrasted bloom patterns and high variations in water level. It was able to reproduce the measurements; it showed a good performance for the water level (root-mean-square error (RMSE) lower than 1 m, annual variation of 25 m), water temperature profiles (RMSE of 0.22-1.41 °C, range 13-28 °C) and cyanobacteria biomass (RMSE of 1-57 μg Chl a L -1 , range 0-206 μg Chl a L -1 ). The model also helped understand the succession of blooms in both years. The model results suggest that the higher growth rate of M. aeruginosa during favourable temperature and light conditions allowed it to outgrow A. ovalisporum. Our results show that simple model configurations can be sufficient not only for theoretical works when few major processes can be identified but also for operational applications. This approach could be transposed on other hypereutrophic lakes and reservoirs to describe the competition between dominant phytoplankton species, contribute to early warning systems or be used for management scenarios.

Mesozooplankton structure and functioning during the onset of the Kerguelen phytoplankton bloom during the KEOPS2 survey

NASA Astrophysics Data System (ADS)

Carlotti, F.; Jouandet, M.-P.; Nowaczyk, A.; Harmelin-Vivien, M.; Lefèvre, D.; Richard, P.; Zhu, Y.; Zhou, M.

2015-07-01

This paper presents results on the spatial and temporal distribution patterns of mesozooplankton in the naturally fertilized region to the east of the Kerguelen Islands (Southern Ocean) visited at early bloom stage during the KEOPS2 survey (15 October to 20 November 2011). The aim of this study was to compare the zooplankton response in contrasted environments localized over the Kerguelen Plateau in waters of the east shelf and shelf edge and in productive oceanic deep waters characterized by conditions of complex circulation and rapidly changing phytoplankton biomass. The mesozooplankton community responded to the spring bloom earlier on the plateau than in the oceanic waters, where complex mesoscale circulation stimulated initial more or less ephemeral blooms before a broader bloom extension. Taxonomic compositions showed a high degree of similarity across the whole region, and the populations initially responded to spring bloom with a large production of larval forms increasing abundances, without biomass changes. Taxonomic composition and stable isotope ratios of size-fractionated zooplankton indicated the strong domination of herbivores, and the total zooplankton biomass values over the survey presented a significant correlation with the integrated chlorophyll concentrations in the mixed layer. The biomass stocks observed at the beginning of the KEOPS2 cruise were around 1.7 g C m-2 above the plateau and 1.2 g C m-2 in oceanic waters. Zooplankton biomass in oceanic waters remained on average below 2 g C m-2 over the study period, except for one station in the Polar Front zone (F-L), whereas zooplankton biomasses were around 4 g C m-2 on the plateau at the end of the survey. The most remarkable feature during the sampling period was the stronger increase in abundance in the oceanic waters (25 × 103 to 160 × 103 ind m-2) than on the plateau (25 × 103 to 90 × 103 ind m-2). The size structure and taxonomic distribution patterns revealed a cumulative contribution of various larval stages of dominant copepods and euphausiids particularly in the oceanic waters, with clearly identifiable stages of progress during a Lagrangian time series survey. The reproduction and early stage development of dominant species were sustained by mesoscale-related initial ephemeral blooms in oceanic waters, but growth was still food-limited and zooplankton biomass stagnated. In contrast, zooplankton abundance and biomass on the shelf were both in a growing phase, at slightly different rates, due to growth under sub-optimal conditions. Combined with our observations during the KEOPS1 survey (January-February 2005), the present results deliver a consistent understanding of patterns in mesozooplankton abundance and biomass from early spring to summer in the poorly documented oceanic region east of the Kerguelen Islands.

The Blooming Anatomy Tool (BAT): A Discipline-Specific Rubric for Utilizing Bloom's Taxonomy in the Design and Evaluation of Assessments in the Anatomical Sciences

ERIC Educational Resources Information Center

Thompson, Andrew R.; O'Loughlin, Valerie D.

2015-01-01

Bloom's taxonomy is a resource commonly used to assess the cognitive level associated with course assignments and examination questions. Although widely utilized in educational research, Bloom's taxonomy has received limited attention as an analytical tool in the anatomical sciences. Building on previous research, the Blooming Anatomy Tool (BAT)…

Controls on the distribution of fluorescent dissolved organic matter during an under‐ice algal bloom in the western Arctic Ocean

PubMed Central

Weiss, Elliot L.; Schieber, Brian; Greg Mitchell, B.

2017-01-01

Abstract In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self‐organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under‐ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network‐based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic‐like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein‐like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity ~29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3‐protein‐like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under‐ice algal bloom was observed (~40–50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein‐like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic‐like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component. PMID:28989231

Controls on the distribution of fluorescent dissolved organic matter during an under-ice algal bloom in the western Arctic Ocean

NASA Astrophysics Data System (ADS)

Mendoza, Wilson G.; Weiss, Elliot L.; Schieber, Brian; Greg Mitchell, B.

2017-07-01

In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self-organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under-ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network-based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic-like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein-like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity 29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3-protein-like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under-ice algal bloom was observed ( 40-50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein-like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic-like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component.

Controls on the distribution of fluorescent dissolved organic matter during an under-ice algal bloom in the western Arctic Ocean.

PubMed

Mendoza, Wilson G; Weiss, Elliot L; Schieber, Brian; Greg Mitchell, B

2017-07-01

In this study we used fluorescence excitation and emission matrix spectroscopy, hydrographic data, and a self-organizing map (SOM) analysis to assess the spatial distribution of labile and refractory fluorescent dissolved organic matter (FDOM) for the Chukchi and Beaufort Seas at the time of a massive under-ice phytoplankton bloom during early summer 2011. Biogeochemical properties were assessed through decomposition of water property classes and sample classification that employed a SOM neural network-based analysis which classified 10 clusters from 269 samples and 17 variables. The terrestrial, humic-like component FDOM (ArC1, 4.98 ± 1.54 Quinine Sulfate Units (QSU)) and protein-like component FDOM (ArC3, 1.63 ± 0.88 QSU) were found to have elevated fluorescence in the Lower Polar Mixed Layer (LPML) (salinity ~29.56 ± 0.76). In the LPML water mass, the observed contribution of meteoric water fraction was 17%, relative to a 12% contribution from the sea ice melt fraction. The labile ArC3-protein-like component (2.01 ± 1.92 QSU) was also observed to be elevated in the Pacific Winter Waters mass, where the under-ice algal bloom was observed (~40-50 m). We interpreted these relationships to indicate that the accumulation and variable distribution of the protein-like component on the shelf could be influenced directly by sea ice melt, transport, and mixing processes and indirectly by the in situ algal bloom and microbial activity. ArC5, corresponding to what is commonly considered marine humic FDOM, indicated a bimodal distribution with high values in both the freshest and saltiest waters. The association of ArC5 with deep, dense salty water is consistent with this component as refractory humic-like FDOM, whereas our evidence of a terrestrial origin challenges this classic paradigm for this component.

Environmental and biological factors controlling the spring phytoplankton bloom at the Patagonian shelf-break front - Degraded fucoxanthin pigments and the importance of microzooplankton grazing

NASA Astrophysics Data System (ADS)

Carreto, José I.; Montoya, Nora G.; Carignan, Mario O.; Akselman, Rut; Acha, E. Marcelo; Derisio, Carla

2016-08-01

The aim of this study was to investigate the biotic and abiotic factors controlling the spring phytoplankton blooms at the Patagonian shelf-break front (PSBF). Using a CHEMTAX analysis of HPLC pigment data and other methods, the biomass and spatial variability of plankton communities were studied in four sections (39-48°S) across the PSBF during October 2005. Environmental factors and the biomass and composition of plankton communities exhibited a marked spatial heterogeneity. The latitudinal and cross-shelf progression in the timing of the spring bloom initiation and the nutritive properties of the water masses (Subantarctic Shelf Waters and Malvinas Current Waters) seemed to be the key factors. Three plankton regions were distinguished: (a) Outer shelf (OS), (b) Shelf-break front (SBF) and (c) Malvinas Current (MC). At the highly stratified OS region, the post-bloom community showed low-biomasshigh-phytoplankton diversity formed mainly by small cells (haptophytes 30-62%, diatoms 17-49%, chlorophytes 0-34%, and prasinophytes 0-21% of total Chl a). High amounts of degraded fucoxanthin were found associated with the heterotrophic dinoflagellate, Protoperidinium capurroi. Grazing by this microheterotroph on the diatom population seemed to be the most important factor for the spring bloom decay at the OS. A remarkable quasi monospecific bloom (∼90%) of a nanodiatom (Thalassiosira bioculata var. raripora) associated with high Chl a (up to 20 mg m-3) occurred along (∼1000 km) the SBF and in the most northern extension of the MC. In the southern region, the bloom was developed under absent or incipient density stratification, increasing solar irradiance, high nitrate and phosphate availability, and low numbers of phytoplankton grazers. The average mixedlayer PAR irradiance (<2.0 mol quanta PAR m-2 d-1) and Si:N ratios (<0.2) were low, suggesting a diatom population limited by light and under progressive silicate limitation. The more stratified northern region of the SBF showed a later stage of the bloom development, but the large population of diatoms under Si limitation was not in senescence and losses from microzooplankton grazing were minor. The observed high proportion of Chl a below a shallow upper mixed layer (up to 85%) could directly reach the bed, favoring the development of epibenthic communities and the formation of seed diatom banks and organic iron-rich sediments. The upwelling along the SBF provides a large source of macronutrients and probably the dissolved iron needed to sustain the intense diatom bloom, but also diatom resting stages that could act as seeds for the next spring bloom. The macronutrient-rich MC region showed low chlorophyll (Chl a < 0.8 mg m-3) and a highly diverse phytoplankton community, mainly composed of small cells (diatoms 20-70%, haptophytes 20-40%, chlorophytes 2-25%, prasinophytes 2-18%, and cryptophytes 3-12% of total Chl a).

Early Spring Phytoplankton Dynamics in the Western Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Arrigo, Kevin R.; van Dijken, Gert L.; Alderkamp, Anne-Carlijn; Erickson, Zachary K.; Lewis, Kate M.; Lowry, Kate E.; Joy-Warren, Hannah L.; Middag, Rob; Nash-Arrigo, Janice E.; Selz, Virginia; van de Poll, Willem

2017-12-01

The Palmer Long-Term Ecological Research program has sampled waters of the western Antarctic Peninsula (wAP) annually each summer since 1990. However, information about the wAP prior to the peak of the phytoplankton bloom in January is sparse. Here we present results from a spring process cruise that sampled the wAP in the early stages of phytoplankton bloom development in 2014. Sea ice concentrations were high on the shelf relative to nonshelf waters, especially toward the south. Macronutrients were high and nonlimiting to phytoplankton growth in both shelf and nonshelf waters, while dissolved iron concentrations were high only on the shelf. Phytoplankton were in good physiological condition throughout the wAP, although biomass on the shelf was uniformly low, presumably because of heavy sea ice cover. In contrast, an early stage phytoplankton bloom was observed beneath variable sea ice cover just seaward of the shelf break. Chlorophyll a concentrations in the bloom reached 2 mg m-3 within a 100-150 km band between the SBACC and SACCF. The location of the bloom appeared to be controlled by a balance between enhanced vertical mixing at the position of the two fronts and increased stratification due to melting sea ice between them. Unlike summer, when diatoms overwhelmingly dominate the phytoplankton population of the wAP, the haptophyte Phaeocystis antarctica dominated in spring, although diatoms were common. These results suggest that factors controlling phytoplankton abundance and composition change seasonally and may differentially affect phytoplankton populations as environmental conditions within the wAP region continue to change.

Rapid growth and concerted sexual transitions by a bloom of the harmful dinoflagellate Alexandrium fundyense (Dinophyceae)

PubMed Central

Velo‐Suárez, Lourdes; Ralston, David K.; Fox, Sophia E.; Sehein, Taylor R.; Shalapyonok, Alexi; Sosik, Heidi M.; Olson, Robert J.; Anderson, Donald M.

2015-01-01

Abstract Transitions between life cycle stages by the harmful dinoflagellate Alexandrium fundyense are critical for the initiation and termination of its blooms. To quantify these transitions in a single population, an Imaging FlowCytobot (IFCB), was deployed in Salt Pond (Eastham, Massachusetts), a small, tidally flushed kettle pond that hosts near annual, localized A. fundyense blooms. Machine‐based image classifiers differentiating A. fundyense life cycle stages were developed and results were compared to manually corrected IFCB samples, manual microscopy‐based estimates of A. fundyense abundance, previously published data describing prevalence of the parasite Amoebophrya, and a continuous culture of A. fundyense infected with Amoebophrya. In Salt Pond, a development phase of sustained vegetative division lasted approximately 3 weeks and was followed by a rapid and near complete conversion to small, gamete cells. The gametic period (∼3 d) coincided with a spike in the frequency of fusing gametes (up to 5% of A. fundyense images) and was followed by a zygotic phase (∼4 d) during which cell sizes returned to their normal range but cell division and diel vertical migration ceased. Cell division during bloom development was strongly phased, enabling estimation of daily rates of division, which were more than twice those predicted from batch cultures grown at similar temperatures in replete medium. Data from the Salt Pond deployment provide the first continuous record of an A. fundyense population through its complete bloom cycle and demonstrate growth and sexual induction rates much higher than are typically observed in culture. PMID:27667858

Effect of algal blooms on retention of N, Si and P in Europe's largest coastal lagoon

NASA Astrophysics Data System (ADS)

Vybernaite-Lubiene, I.; Zilius, M.; Giordani, G.; Petkuviene, J.; Vaiciute, D.; Bukaveckas, P. A.; Bartoli, M.

2017-07-01

Nutrient fluxes from land to sea are regulated by climatic factors governing hydrologic loading rates (e.g., storm events, snowmelt) and by internal processes within estuaries that affect nutrient transformation and retention. We compared monthly input and output fluxes of N, Si, and P at the entrance and exit of the hypereutrophic Curonian Lagoon to better understand how seasonal changes in the stoichiometry of nutrient inputs and the occurrence of algal blooms affected nutrient retention within the lagoon. Nutrient ratios were indicative of increasing Si and N limitation during the growing season, and these were associated with a shift from a diatom-based to a cyanobacteria dominated phytoplankton community. The estuary was a net sink for dissolved nutrients, but we observed large interannual difference in the overall retention of N and P. The occurrence of a large cyanobacteria bloom in 2012 was associated with increased export of particulate matter to the Baltic Sea resulting in a net surplus of P export. Bloom conditions mobilized P from sediments and resulted in a shift from net retention to net export for the lagoon. The findings of our study illustrate how changes in nutrient loading ratios influence phytoplankton community composition, which in turn alters the source-sink status of the estuary.

Dynamic autoinoculation and the microbial ecology of a deep water hydrocarbon irruption

PubMed Central

Valentine, David L.; Mezić, Igor; Maćešić, Senka; Črnjarić-Žic, Nelida; Ivić, Stefan; Hogan, Patrick J.; Fonoberov, Vladimir A.; Loire, Sophie

2012-01-01

The irruption of gas and oil into the Gulf of Mexico during the Deepwater Horizon event fed a deep sea bacterial bloom that consumed hydrocarbons in the affected waters, formed a regional oxygen anomaly, and altered the microbiology of the region. In this work, we develop a coupled physical–metabolic model to assess the impact of mixing processes on these deep ocean bacterial communities and their capacity for hydrocarbon and oxygen use. We find that observed biodegradation patterns are well-described by exponential growth of bacteria from seed populations present at low abundance and that current oscillation and mixing processes played a critical role in distributing hydrocarbons and associated bacterial blooms within the northeast Gulf of Mexico. Mixing processes also accelerated hydrocarbon degradation through an autoinoculation effect, where water masses, in which the hydrocarbon irruption had caused blooms, later returned to the spill site with hydrocarbon-degrading bacteria persisting at elevated abundance. Interestingly, although the initial irruption of hydrocarbons fed successive blooms of different bacterial types, subsequent irruptions promoted consistency in the structure of the bacterial community. These results highlight an impact of mixing and circulation processes on biodegradation activity of bacteria during the Deepwater Horizon event and suggest an important role for mixing processes in the microbial ecology of deep ocean environments. PMID:22233808

Spatial distributions of polyunsaturated aldehydes and their biogeochemical implications in the Pearl River Estuary and the adjacent northern South China Sea

NASA Astrophysics Data System (ADS)

Wu, Zhengchao; Li, Qian P.

2016-09-01

This study reports the first comprehensive exploration of the spatial patterns of dissolved and particulate polyunsaturated aldehydes (PUAs), their physical and biological controlling factors, and their potential biogeochemical influences in the Pearl River Estuary (PRE) of the northern South China Sea (NSCS). High levels of total particulate PUAs (0-41 nM) and dissolved PUAs (0.10-0.37 nM) were observed with substantial spatial variation during an intense summer phytoplankton bloom outside the PRE mouth. We found the particulate PUAs strongly correlated with temperature within the high chlorophyll bloom, while showing a generally positive correlation with chlorophyll-a for the entire region. Additionally, the Si/N ratio significantly correlated with the particulate PUAs along the estuary suggesting the important role of silica on PUA production in this region. The dissolved PUAs counterparts exhibited a positive correlation with chlorophyll-a within the high chlorophyll bloom, but a negatively one with temperature outside, reflecting the essential bio-physical coupling effects on the dissolved PUAs distributions in the ocean. Biogeochemical implications of PUAs on the coastal ecosystem include not only the deleterious restriction of high PUAs-producing diatom bloom on copepod population, but also the profound influence of particulate PUAs on the microbial cycling of organic carbon in the NSCS.

Numerical Modeling of the Effects of Nutrient-rich Coastal-water Input on the Phytoplankton in the Gulf of California

NASA Astrophysics Data System (ADS)

Bermudez, A.; Rivas, D.

2015-12-01

Phytoplankton bloom dynamics depends on the interactions of favorable physical, chemical, and biotic conditions, particularly on the available nutrients that enhance phytoplankton growth, like nitrogen. Costal and estuarine environments are heavily influenced by exogenous sources of nitrogen; the anthropogenic inputs include urban and rural wastewater coming from agricultural activities (i.e., fertilizers and animal waste). In response, new production is often enhanced, leading eutrophication and phytoplankton blooms, including harmful taxa. These events have become more frequent, and with it the interest to evaluate their effects on marine ecosystems and the impact on human health. In the Gulf of California the harmful algal blooms (HABs) had affected aquaculture, fisheries, and even tourism, thereby it is important to generate information about biological and physical factors that can influence their appearance. A numerical model is a tool that may bring key information about the origin and distribution of phytoplankton blooms. Herein the analysis is based on a three-dimensional, hydrodynamical numerical model, coupled to a Nitrogen-Phytoplankton-Zooplankton-Detritus (NPZD) model. Several numerical simulations using different forcing and scenarios are carried out in order to evaluate the processes that influence the phytoplankton growth. These numerical results are compared to available observations. Thus, the main environmental factors triggering the generation of HABs can be identified.

Aircraft remote sensing of phytoplankton spatial patterns during the 1989 Joint Global Ocean Flux Study (JGOFS) North Atlantic bloom experiment

NASA Technical Reports Server (NTRS)

Yoder, James A.; Hoge, Frank E.

1991-01-01

Mesoscale phytoplankton chlorophyll variability near the Joint Global Ocean Flux study sites along the 20 W meridian at 34 N, 47 N, and 59 N is discussed. The NASA P-3 aircraft and the Airborne Oceanographic Lidar (AOL) system provides remote sensing support for the North Atlantic Bloom Experiment. The principal instrument of the AOL system is the blue-green laser that stimulates fluorescence from photoplankton chlorophyll, the principal photosynthetic pigment. Other instruments on the NASA P-3 aircraft include up- and down-looking spectrometers, PRT-5 for infrared measurements to determine sea surface temperature, and a system to deploy and record AXBTs to measure subsurface temperature structure.

Zooplankton diel vertical migration and contribution to deep active carbon flux in the NW Mediterranean

NASA Astrophysics Data System (ADS)

Isla, Alejandro; Scharek, Renate; Latasa, Mikel

2015-03-01

The diel vertical migration (DVM) of zooplankton contributes to the biological pump transporting material from surface to deep waters. We examined the DVM of the zooplankton community in different size fractions (53-200 μm, 200-500 μm, 500-1000 μm, 1000-2000 μm and > 2000 μm) during three cruises carried out in the open NW Mediterranean Sea. We assessed their metabolic rates from empirical published relationships and estimated the active fluxes of dissolved carbon to the mesopelagic zone driven by migrant zooplankton. Within the predominantly oligotrophic Mediterranean Sea, the NW region is one of the most productive ones, with a seasonal cycle characterized by a prominent spring bloom. The study area was visited at three different phases of the seasonal cycle: during the spring bloom, the post-bloom, and strongly stratified oligotrophic conditions. We found seasonal differences in DVM, less evident during the bloom. Changes in DVM intensity were related to the composition of the zooplanktonic assemblage, which also varied between cruises. Euphausiids appeared as the most active migrants in all seasons, and their life cycle conditioned the observed pattern. Immature stages, which are unable to perform large diel vertical movements, dominated during the bloom, in contrast to the higher relative importance of migrating adults in the other two sampling periods. The amount of dissolved carbon exported was determined by the migrant zooplankton biomass, being highest during the post-bloom (2.2 mmol C respired m- 2 d- 1, and up to 3.1 mmol C exported m- 2 d- 1 when DOC release estimations are added). The active transport by diel migrants represented a substantial contribution to total carbon export to deep waters, especially under stratified oligotrophic conditions, revealing the importance of zooplankton in the biological pump operating in the study area.

Arsenic, barium, germanium, tin, dimethylsulfide and nutrient biogeochemistry in Charlotte Harbor, Florida, a phosphorus-enriched estuary

NASA Astrophysics Data System (ADS)

Froelich, P. N.; Kaul, L. W.; Byrd, J. T.; Andreae, M. O.; Roe, K. K.

1985-03-01

Concentrations of dissolved nutrients (NO 3, PO 4, Si), germanium species, arsenic species, tin, barium, dimethylsulfide and related parameters were measured along the salinity gradient in Charlotte Harbor. Phosphate enrichment from the phosphate industry on the Peace River promotes a productive diatom bloom near the river mouth where NO 3 and Si are completely consumed. Inorganic germanium is completely depleted in this bloom by uptake into biogenic opal. The Ge/Si ratio taken up by diatoms is about 0·7 × 10 -6, the same as that provided by the river flux, confirming that siliceous organisms incorporate germanium as an accidental trace replacement for silica. Monomethylgermanium and dimethylgermanium concentrations are undetectable in the Peace River, and increase linearly with increasing salinity to the seawater end of the bay, suggesting that these organogermanium species behave conservatively in estuaries, and are neither produced nor consumed during estuarine biogenic opal formation or dissolution. Inorganic arsenic displays slight removal in the bloom. Monomethylarsenic is produced both in the bloom and in mid-estuary, while dimethylarsenic is conservative in the bloom but produced in mid-estuary. The total production of methylarsenicals within the bay approximately balances the removal of inorganic arsenic, suggesting that most biological arsenic uptake in the estuary is biomethylated and released to the water column. Dimethylsulfide increases with increasing salinity in the estuary and shows evidence of removal, probably both by degassing and by microbial consumption. An input of DMS is observed in the central estuary. The behavior of total dissolvable tin shows no biological activity in the bloom or in mid-estuary, but does display a low-salinity input signal that parallels dissolved organic material, perhaps suggesting an association between tin and DOM. Barium displays dramatic input behavior at mid-salinities, probably due to slow release from clays deposited in the harbor after catastrophic phosphate slime spills into the Peace River.

Export of a Winter Shelf Phytoplankton Bloom at the Shelf Margin of Long Bay (South Atlantic Bight, USA)

NASA Astrophysics Data System (ADS)

Nelson, J.; Seim, H.; Edwards, C. R.; Lockhart, S.; Moore, T.; Robertson, C. Y.; Amft, J.

2016-02-01

A winter 2012 field study off Long Bay (seaward of Myrtle Beach, South Carolina) investigated exchange processes along the shelf margin. Topics addressed included mechanisms of nutrient input (upper slope to outer shelf), phytoplankton blooms and community characteristics (mid-to-outer shelf), and possible export of shelf bloom material (transport to and across the shelf break to the upper slope). Observations utilized three moorings (mid-shelf, shelf break, upper slope), two gliders and ship operations (repeat cruises with profiling, water sampling and towed body surveys) along with satellite SST and ocean color imagery and near-by NOAA buoy records. Here we focus on the late January to early February period, when a mid-shelf bloom of Phaeocystis globosa (which forms large gelatinous colonies) was transported to the shelf break. The presence of Phaeocystis colonies resulted in strong spiking in chlorophyll (chl) fluorescence profiles. A partitioning approach was adapted to estimate chl in colonies (spikes) and small forms (baseline signal) and to account for an apparent difference in measured in vivo fluorescence per unit chl (lower in colonies). Up to 40-50% of chl in the bloom (surface to bottom on the mid-shelf) was estimated to be in the colonies. In late January, there a pronounced seaward slumping of relatively dense mid-shelf water along the bottom under warmer surface water derived from the inshore edge of a broad jet of Gulf Stream water flowing southwestward along the upper slope. We describe the evolution of this event and the conditions which set up this mechanism for episodic near-bed transport of fresh bloom material produced on the shelf to the upper slope off Long Bay. Down-slope transport may have been enhanced in this case by the high phytoplankton biomass in gelatinous colonies, which appeared to be settling in the water column on the shelf prior to the transport event.

Effects of changes in climate variability and extremes on the exceedance of critical algal bloom thresholds

NASA Astrophysics Data System (ADS)

Hecht, J. S.; Zia, A.; Beckage, B.; Winter, J.; Schroth, A. W.; Bomblies, A.; Clemins, P. J.; Rizzo, D. M.

2017-12-01

Identifying critical thresholds associated with algal blooms in freshwater lakes is important for avoiding persistent eutrophic conditions and their undesirable ecological, recreational and drinking water impacts. Recent Integrated Assessment Model (IAM) and Bayesian network studies have demonstrated that future climatic changes could increase the duration and intensity of these blooms. Yet, few studies have systematically examined the sensitivity of algal blooms to projected changes in precipitation and temperature variability and extremes at storm-event to seasonal timescales. We employ an IAM, which couples downscaled Global Climate Model (GCM) output with hydrologic and water quality models, to examine the sensitivity of algal blooms in Lake Champlain's shallow Missisquoi Bay to potential future climate changes. We first identify a set of statistically downscaled GCMs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) that reproduce recent historical daily temperature and precipitation observations well in the Lake Champlain basin. Then, we identify plausible covarying changes in the (i) mean and variance of seasonal precipitation and temperature distributions and (ii) frequency and magnitude of individual storm events. We assess the response of water quality indicators (e.g. chlorophyll a concentrations, Trophic State Index) and societal impacts to sequences of daily meteorological series generated from distributions that account for these covarying changes. We also discuss strategies for examining the sensitivity of bloom impacts to different weather sequences generated from a single set of precipitation and temperature distributions with a limited number of computationally intensive IAM simulations. We then evaluate the implications of modeling these changes in climate variability and extreme precipitation events for nutrient management. Finally, we consider the generalizability of our findings for water bodies with different physical and climatic characteristics and address the extent to which climate-driven alterations to terrestrial hydrologic processes, such as evapotranspiration and soil moisture storage, mediate changes to lake water quality.

Solutions Network Formulation Report. NASA's Potential Contributions in Remote Quorum Sensing and the Management of Harmful Algal Blooms

NASA Technical Reports Server (NTRS)

Fletcher, Rose; Knowlton, Kelly; Ryan, Robert E.

2007-01-01

This candidate solution proposes to use the night-imaging capabilities of the HSTC from SAC-C and of the HSC from SAC-D/Aquarius to detect bioluminescent events associated with HABs (harmful algal blooms). Once detected, this information could be fed to the NOAA CSCOR (Center for Sponsored Coastal Ocean Research) Harmful Algal Bloom Event Response Program, which acts quickly to fund the mobilization of research teams and to engage local agencies in a response. The HSC/HSTC data can serve as input to the HABSOS decision support system to provide information on location, extent, and duration of HAB events. Society will benefit from improved protection of the health of humans beings, aquatic ecosystems, and coastal economies. This work supports coastal management, public health, and homeland security applications.

Impacts of sea ice retreat, thinning, and melt-pond proliferation on the summer phytoplankton bloom in the Chukchi Sea, Arctic Ocean

NASA Astrophysics Data System (ADS)

Palmer, Molly A.; Saenz, Benjamin T.; Arrigo, Kevin R.

2014-07-01

In 2011, a massive phytoplankton bloom was observed in the Chukchi Sea under first-year sea ice (FYI), an environment in which primary productivity (PP) has historically been low. In this paper, we use a 1-D biological model of the Chukchi shelf ecosystem, in conjunction with in situ chemical and physiological data, to better understand the conditions that facilitated the development of such an unprecedented bloom. In addition, to assess the effects of changing Arctic environmental conditions on net PP (NPP), we perform model runs with varying sea ice and snow thickness, timing of melt, melt ponds, and biological parameters. Results from model runs with conditions similar to 2011 indicate that first-year ice (FYI) with at least 10% melt pond coverage transmits sufficient light to support the growth of shade-adapted Arctic phytoplankton. Increasing pond fraction by 20% enhanced peak under-ice NPP by 26% and produced rates more comparable to those measured during the 2011 bloom, but there was no effect of further increasing pond fraction. One of the important consequences of large under-ice blooms is that they consume a substantial fraction of surface nutrients such that NPP is greatly diminished in the marginal ice zone (MIZ) following ice retreat, where NPP has historically been the highest. In contrast, in model runs with <10% ponds, no under-ice bloom formed, and although peak MIZ NPP increased by 18-30%, this did not result in higher total annual NPP. This suggests that under-ice blooms contribute importantly to total annual NPP. Indeed, in all runs exhibiting under-ice blooms, total annual NPP was higher than in runs with the majority of NPP based in open water. Consistent with this, in model runs where ice melted one month earlier, peak under-ice NPP decreased 30%, and annual NPP was lower as well. The only exception was the case with no sea ice in the region: a weak bloom in early May was followed by low but sustained NPP throughout the entire growth season (almost all of which occurred in deep, subsurface layers), resulting in higher total annual NPP than in cases with sea ice present. Our results also show that both ultraviolet radiation and zooplankton grazers reduce peak open water NPP but have little impact on under-ice NPP, which has important implications for the relative proportion of NPP concentrated in pelagic vs. benthic food webs. Finally, the shift in the relative amount of NPP occurring in under-ice vs. open-water environments may affect total ecosystem productivity.

The green impact: bacterioplankton response toward a phytoplankton spring bloom in the southern North Sea assessed by comparative metagenomic and metatranscriptomic approaches

PubMed Central

Wemheuer, Bernd; Wemheuer, Franziska; Hollensteiner, Jacqueline; Meyer, Frauke-Dorothee; Voget, Sonja; Daniel, Rolf

2015-01-01

Phytoplankton blooms exhibit a severe impact on bacterioplankton communities as they change nutrient availabilities and other environmental factors. In the current study, the response of a bacterioplankton community to a Phaeocystis globosa spring bloom was investigated in the southern North Sea. For this purpose, water samples were taken inside and reference samples outside of an algal spring bloom. Structural changes of the bacterioplankton community were assessed by amplicon-based analysis of 16S rRNA genes and transcripts generated from environmental DNA and RNA, respectively. Several marine groups responded to bloom presence. The abundance of the Roseobacter RCA cluster and the SAR92 clade significantly increased in bloom presence in the total and active fraction of the bacterial community. Functional changes were investigated by direct sequencing of environmental DNA and mRNA. The corresponding datasets comprised more than 500 million sequences across all samples. Metatranscriptomic data sets were mapped on representative genomes of abundant marine groups present in the samples and on assembled metagenomic and metatranscriptomic datasets. Differences in gene expression profiles between non-bloom and bloom samples were recorded. The genome-wide gene expression level of Planktomarina temperata, an abundant member of the Roseobacter RCA cluster, was higher inside the bloom. Genes that were differently expressed included transposases, which showed increased expression levels inside the bloom. This might contribute to the adaptation of this organism toward environmental stresses through genome reorganization. In addition, several genes affiliated to the SAR92 clade were significantly upregulated inside the bloom including genes encoding for proteins involved in isoleucine and leucine incorporation. Obtained results provide novel insights into compositional and functional variations of marine bacterioplankton communities as response to a phytoplankton bloom. PMID:26322028

Linking phytoplankton and bacterioplankton community dynamics to iron-binding ligand production in a microcosm experiment

NASA Astrophysics Data System (ADS)

Hogle, S. L.; Bundy, R.; Barbeau, K.

2016-02-01

Several significant lines of evidence implicate heterotrophic bacterioplankton as agents of iron cycling and sources of iron-binding ligands in seawater, but direct and mechanistic linkages have mostly remained elusive. Currently, it is unknown how microbial community composition varies during the course of biogenic particle remineralization and how shifts in community structure are related to sources and sinks of Fe-binding ligands. In order to simulate the rise, decline, and ultimate remineralization of a phytoplankton bloom, we followed the production of different classes of Fe-binding ligands as measured by electrochemical techniques, Fe concentrations, and macronutrient concentrations in a series of iron-amended whole seawater incubations over a period of six days during a California Current Ecosystem Long Term Ecological Research (CCE-LTER) process cruise. At the termination of the experiment phytoplankton communities were similar across iron treatments, but high iron conditions generated greater phytoplankton biomass and increased nutrient drawdown suggesting that phytoplankton communities were in different phases of bloom development. Strikingly, L1 ligands akin to siderophores in binding strength were only observed in high iron treatments implicating phytoplankton bloom phase as an important control. Using high-throughput 16S rRNA gene surveys, we observed that the abundance of transiently dominant copiotroph bacteria were strongly correlated with L1 concentrations. However, incubations with similar L1 concentrations and binding strengths produced distinct copiotroph community profiles dominated by a few strains. We suggest that phytoplankton bloom maturity influences algal-associated heterotrophic community succession, and that L1 production is either directly or indirectly tied to the appearance and eventual dominance of rarely abundant copiotroph bacterial strains.

Spatial and temporal variation of net community production and its regulating factors in the Amundsen Sea, Antarctica

NASA Astrophysics Data System (ADS)

Hahm, Doshik; Rhee, Tae Siek; Kim, Hae-Cheol; Park, Jisoo; Kim, Young-Nam; Shin, Hyoung Chul; Lee, SangHoon

2014-05-01

We observed ΔO2/Ar in the surface waters of the Amundsen Sea, Antarctica, during the austral summers in 2011 and 2012 to investigate the variability of net community production (NCP). Corresponding to the typical peak phytoplankton bloom period, the ΔO2/Ar of the Amundsen Sea Polynya (ASP) reached 30% in early January 2011 and had a strong positive correlation with the sea surface temperature (SST) and chlorophyll-a (Chl-a). In contrast, ΔO2/Ar decreased to -10% in the sea ice zone (SIZ), which was likely associated with either net O2 consumption in the unlit area or the entrainment of deep water containing low dissolved oxygen. Near the terminal stage of the phytoplankton bloom in late February 2012, we observed the same contrasting ΔO2/Ar features between the ASP and SIZ. However, the ΔO2/Ar in the ASP was not >10%, which corresponded with the overall reduction in Chl-a, solar radiation, and SST compared with the corresponding values in 2011. The average net community production in the ASP was 119 ± 79 mmol O2 m-2 d-1 in January 2011, and 23 ± 14 mmol O2 m-2 d-1 in February 2012. The strong correlations of NCP with SST and mixed layer depth (MLD) indicate that the ASP phytoplankton bloom is likely initiated by a combination of increased light availability and SST in early summer. Low SST and variable fluorescence to maximum florescence ratio (Fv/Fm) in February indicate that decreased solar radiation and Fe availability are likely responsible for the phytoplankton bloom demise.

Earth Observation taken during the Expedition 36 mission

NASA Image and Video Library

2013-08-24

ISS036-E-035635 (24 Aug. 2013) --- Plankton bloom and Lake Ontario are featured in this image photographed by an Expedition 36 crew member on the International Space Station. This photograph highlights a late summer plankton bloom visible throughout much of Lake Ontario (one of the Great Lakes, together with Michigan, Superior, Erie, and Huron). Cyanobacteria, or blue-green algae, can reach such large concentrations that they color the water to such an extent that the change is visible from orbit. Harmful algal blooms, or HABs, have been observed in all of the Great Lakes – particularly Lake Erie - and are associated with a variety of causative factors including changes in precipitation; drought; invasive species (quagga, zebra mussels, Asian carp); nutrient loading from runoff and sewage (nitrogen and phosphorus); and warmer average temperatures. In addition to reduced water quality and human health concerns, algal blooms can also lead to hypoxia (reduction of oxygen in the bottom waters) that kills large numbers of fish and other aquatic life. Lake Ontario, like the other Great Lakes Erie, Huron, and Superior is roughly divided between the USA and Canada. The USA side of Lake Ontario has its shoreline along the state of New York, while its Canadian shoreline lies within the province of Ontario. The city of Kingston, Ontario, is visible near the Saint Lawrence River outflow from the lake. Several other landscape features of New York State are visible in the image, including the Finger Lakes region to the west of Syracuse, NY (upper left). To the northeast of Syracuse, the dark wooded slopes of the Adirondack Mountains are visible at lower right. Patchy white cloud cover obscures much of the land surface to the west of Lake Ontario.

Current-oriented swimming by jellyfish and its role in bloom maintenance.

PubMed

Fossette, Sabrina; Gleiss, Adrian Christopher; Chalumeau, Julien; Bastian, Thomas; Armstrong, Claire Denise; Vandenabeele, Sylvie; Karpytchev, Mikhail; Hays, Graeme Clive

2015-02-02

Cross-flows (winds or currents) affect animal movements [1-3]. Animals can temporarily be carried off course or permanently carried away from their preferred habitat by drift depending on their own traveling speed in relation to that of the flow [1]. Animals able to only weakly fly or swim will be the most impacted (e.g., [4]). To circumvent this problem, animals must be able to detect the effects of flow on their movements and respond to it [1, 2]. Here, we show that a weakly swimming organism, the jellyfish Rhizostoma octopus, can orientate its movements with respect to currents and that this behavior is key to the maintenance of blooms and essential to reduce the probability of stranding. We combined in situ observations with first-time deployment of accelerometers on free-ranging jellyfish and simulated the behavior observed in wild jellyfish within a high-resolution hydrodynamic model. Our results show that jellyfish can actively swim countercurrent in response to current drift, leading to significant life-history benefits, i.e., increased chance of survival and facilitated bloom formation. Current-oriented swimming may be achieved by jellyfish either directly detecting current shear across their body surface [5] or indirectly assessing drift direction using other cues (e.g., magnetic, infrasound). Our coupled behavioral-hydrodynamic model provides new evidence that current-oriented swimming contributes to jellyfish being able to form aggregations of hundreds to millions of individuals for up to several months, which may have substantial ecosystem and socioeconomic consequences [6, 7]. It also contributes to improve predictions of jellyfish blooms' magnitude and movements in coastal waters. Copyright © 2015 Elsevier Ltd. All rights reserved.

Annual cycles of phytoplankton biomass in the subarctic Atlantic and Pacific Ocean

NASA Astrophysics Data System (ADS)

Westberry, Toby K.; Schultz, Patrick; Behrenfeld, Michael J.; Dunne, John P.; Hiscock, Michael R.; Maritorena, Stephane; Sarmiento, Jorge L.; Siegel, David A.

2016-02-01

High-latitude phytoplankton blooms support productive fisheries and play an important role in oceanic uptake of atmospheric carbon dioxide. In the subarctic North Atlantic Ocean, blooms are a recurrent feature each year, while in the eastern subarctic Pacific only small changes in chlorophyll (Chl) are seen over the annual cycle. Here we show that when evaluated using phytoplankton carbon biomass (Cphyto) rather than Chl, an annual bloom in the North Pacific is evident and can even rival blooms observed in the North Atlantic. The annual increase in subarctic Pacific phytoplankton biomass is not readily observed in the Chl record because it is paralleled by light- and nutrient-driven decreases in cellular pigment levels (Cphyto:Chl). Specifically, photoacclimation and iron stress effects on Cphyto:Chl oppose the biomass increase, leading to only modest changes in bulk Chl. The magnitude of the photoacclimation effect is quantified using descriptors of the near-surface light environment and a photophysiological model. Iron stress effects are diagnosed from satellite chlorophyll fluorescence data. Lastly, we show that biomass accumulation in the Pacific is slower than that in the Atlantic but is closely tied to similar levels of seasonal nutrient uptake in both basins. Annual cycles of satellite-derived Chl and Cphyto are reproduced by in situ autonomous profiling floats. These results contradict the long-standing paradigm that environmental conditions prevent phytoplankton accumulation in the subarctic Northeast Pacific and suggest a greater seasonal decoupling between phytoplankton growth and losses than traditionally implied. Further, our results highlight the role of physiological processes in shaping bulk properties, such as Chl, and their interpretation in studies of ocean ecosystem dynamics and climate change.

Exposure-driven macroalgal phase shift following catastrophic disturbance on coral reefs

NASA Astrophysics Data System (ADS)

Roff, George; Chollett, Iliana; Doropoulos, Christopher; Golbuu, Yimnang; Steneck, Robert S.; Isechal, Adelle L.; van Woesik, Robert; Mumby, Peter J.

2015-09-01

Environmental conditions play an important role in post-disturbance dynamics of ecosystems by modulating recovery of surviving communities and influencing patterns of succession. Here, we document the effects of wave exposure following a catastrophic disturbance on coral reefs in driving a phase shift to macroalgal dominance. In December 2012, a Category 5 super typhoon (`Typhoon Bopha') passed 50 km to the south of Palau (Micronesia), causing a major loss of reef corals. Immediately post-disturbance, a rapid and extensive phase shift of the macroalgae Liagora sp. (Rhodophyta) was observed at sites exposed to chronic wave exposure. To quantify the influence of biotic and abiotic drivers in modulating the extent of post-disturbance Liagora blooms, we compared benthic substrates and herbivore assemblages at sites surveyed pre- and post-disturbance across a gradient of wave exposure. Relative changes in herbivore biomass and coral cover before and after disturbance did not significantly predict the extent of Liagora cover, indicating that changes in herbivore biomass or reductions in grazing pressure were not directly responsible for driving the Liagora blooms. By contrast, the degree of wave exposure experienced at sites post-disturbance explained >90 % of model variance ( p < 0.001, R 2 = 0.69), in that Liagora was absent at low exposure sites, while most extensive blooms were observed at highly exposed sites. At regional scales, spatial maps of wave exposure accurately predicted the presence of Liagora at impacted sites throughout the Palau archipelago (>150 km distance), highlighting the predictive capacity of wave exposure as an explanatory variable and the deterministic nature of post-disturbance macroalgal blooms. Understanding how physical conditions modulate recovery of ecosystems after disturbance allows insight into post-disturbance dynamics and succession of communities, ultimately allowing management strategies to prioritise restoration efforts in regions that are most effective.

Physical and Biological Drivers of Biogeochemical Tracers Within the Seasonal Sea Ice Zone of the Southern Ocean From Profiling Floats

NASA Astrophysics Data System (ADS)

Briggs, Ellen M.; Martz, Todd R.; Talley, Lynne D.; Mazloff, Matthew R.; Johnson, Kenneth S.

2018-02-01

Here we present initial findings from nine profiling floats equipped with pH, O2, NO3-, and other biogeochemical sensors that were deployed in the seasonal ice zone (SIZ) of the Southern Ocean in 2014 and 2015 through the Southern Ocean Carbon and Climate Observations and Modelling (SOCCOM) project. A large springtime phytoplankton bloom was observed that coincided with sea ice melt for all nine floats. We argue this bloom results from a shoaling of the mixed layer depth, increased vertical stability, and enhanced nutrient and light availability as the sea ice melts. This interpretation is supported by the absence of a springtime bloom when one of the floats left the SIZ in the second year of observations. During the sea ice covered period, net heterotrophic conditions were observed. The rate of uptake of O2 and release of dissolved inorganic carbon (derived from pH and estimated total alkalinity) and NO3- is reminiscent of biological respiration and is nearly Redfieldian for the nine floats. A simple model of mixed layer physics was developed to separate the physical and biological components of the signal in pH and O2 over one annual cycle for a float in the Ross Sea SIZ. The resulting annual net community production suggests that seasonal respiration during the ice covered period of the year nearly balances the production in the euphotic layer of up to 5 mol C m-2 during the ice free period leading to a net of near zero carbon exported to depth for this one float.

Blooms of cyanobacteria on the potomac river.

PubMed

Krogmann, D W; Butalla, R; Sprinkle, J

1986-03-01

Blooms of cyanobacteria have appeared on the Potomac River near Washington, DC in years of drought and low river volume. The location of the bloom may be related to tidal activity. In 1983, the bloom of Microcystis aeruginosa used ammonia as its nitrogen source and contained low levels of toxic peptides. Cells collected from this bloom proved to be homogeneous and were an excellent source material for the isolation of proteins involved in photosynthesis.

Dynamic modelling of five different phytoplankton groups in the River Thames (UK)

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Whitehead, Paul; Bowes, Michael; Read, Daniel; Dadson, Simon

2015-04-01

Phytoplankton play a vital role in fluvial ecosystems, being a major producer of organic carbon, a food source for primary consumers and a relevant source of oxygen for many low-gradient rivers, but also a producer of potentially harmful toxins (e.g. cyanobacteria). For these reasons, the forecast and prevention of algal blooms is fundamental for the safe management of river systems. In this study, we developed a new process-based phytoplankton model for operational management and forecast of algal and cyanobacteria blooms subject to environmental change. The model is based on a mass-balance and it reproduces phytoplankton growth and death, taking into account the controlling effect played by water temperature, solar radiation, self-shading and dissolved phosphorus and silicon concentrations. The model was implemented in five reaches of the River Thames (UK) with a daily time step over a period of three years, and its results were compared to a novel dataset of cytometric data which includes community cell abundance of chlorophytes, diatoms, cyanobacteria, microcystis-like cyanobacteria and picoalgae. The model results were satisfactory in terms of fitting the observed data. A Multi-Objective General Sensitivity Analysis was also carried out in order to quantify model sensitivity to its parameters. It showed that the most influential parameters are phytoplankton growth and death rates, while phosphorus concentration showed little influence on phytoplankton growth, due to the high levels of phosphorus in the River Thames. The model was demonstrated to be a reliable tool to be used in algal bloom forecasting and management.

A pilot project to detect and forecast harmful algal blooms in the northern Gulf of Mexico.

PubMed

Fisher, William S; Malone, Thomas C; Giattina, James D

2003-01-01

More timely access to data and information on the initiation, evolution and effects of harmful algal blooms can reduce adverse impacts on valued natural resources and human health. To achieve this in the northern Gulf of Mexico, a pilot project was initiated to develop a user-driven, end-to-end (measurements to applications) observing system. A key strategy of the project is to coordinate existing state, federal and academic programs at an unprecedented level of collaboration and partnership. Resource managers charged with protection of public health and aquatic resources require immediate notice of algal events and a forecast of when, where and what adverse effects will likely occur. Further, managers require integrated analyses and interpretations, rather than raw data, to make effective decisions. Consequently, a functional observing system must collect and transform diverse measurements into usable forecasts. Data needed to support development of forecasts will include such properties as sea surface temperature, winds, currents and waves; precipitation and freshwater flows with related discharges of sediment and nutrients; salinity, dissolved oxygen, and chlorophyll concentrations (in vivo fluorescence); and remotely-sensed spatial images of sea surface chlorophyll concentrations. These data will be provided via a mixture of discrete and autonomous in situ sensing with near real-time data telemetry, and remote sensing from space (SeaWiFS), aircraft (hyperspectral imagery) or land (high-frequency radar). With calibration across these platforms, the project will ultimately provide a 4-dimensional visualization of harmful algae events in a time frame suitable to resource managers.

Cell death in a harmful algal bloom causing species Alexandrium tamarense upon an algicidal bacterium induction.

PubMed

Zhang, Huajun; Lv, Jinglin; Peng, Yun; Zhang, Su; An, Xinli; Xu, Hong; Zhang, Jun; Tian, Yun; Zheng, Wei; Zheng, Tianling

2014-09-01

Harmful algal blooms occur throughout the world, destroying aquatic ecosystems and threatening human health. The culture supernatant of the marine algicidal bacteria DHQ25 was able to lysis dinoflagellate Alexandrium tamarense. Loss of photosynthetic pigments, accompanied by a decline in Photosystem II (PSII) photochemical efficiency (Fv/Fm), in A. tamarense was detected under bacterial supernatant stress. Transmission electron microscope analysis showed obvious morphological modifications of chloroplast dismantling as a part of the algicidal process. The PSII electron transport chain was seriously blocked, with its reaction center damaged. This damage was detected in a relative transcriptional level of psbA and psbD genes, which encode the D1 and D2 proteins in the PSII reaction center. And the block in the electron transport chain of PSII might generate excessive reactive oxygen species (ROS) which could destroy the membrane system and pigment synthesis and activated enzymic antioxidant systems including superoxide dismutase (SOD) and catalase (CAT). This study indicated that marine bacteria with indirect algicidal activity played an important role in the changes of photosynthetic process in a harmful algal bloom species.

The Openness That Closes: Allan Bloom and the Contemporary University.

ERIC Educational Resources Information Center

Orwin, Clifford; Forbes, H. D.

1991-01-01

Discusses the contemporary university in Canada, focusing on Allan Bloom's "The Closing of the American Mind" which analyzes problems in today's education. The paper calls Bloom's book an unrivaled diagnosis of the impasse of the university, and it examines Bloom's relativistic principles. (SM)

Trophic linkage of a temperate intertidal macrobenthic food web under opportunistic macroalgal blooms: A stable isotope approach.

PubMed

Park, Hyun Je; Han, Eunah; Lee, Young-Jae; Kang, Chang-Keun

2016-10-15

The effects of blooms of opportunistic green macroalgae, Ulva prolifera, on the trophic structure of the macrobenthic food web in a temperate intertidal zone on the western coast of Korea were evaluated using carbon and nitrogen stable isotopes. Biomasses of Ulva and microphytobenthos (MPB) increased significantly at the macroalgae-bloom and the non-bloom sites, respectively, from March to September 2011. The δ(13)C values of most the consumers were arrayed between those of MPB and Ulva at both sites, and differed according to feeding strategies at the macroalgae-bloom site. Seasonally increasing magnitudes in δ(13)C and δ(15)N values of consumers were much steeper at the macroalgae-bloom site than at the non-bloom site. Our findings provide evidence that blooming green macroalgae play a significant role as a basal resource supporting the intertidal macrobenthic food web and their significance varies with feeding strategies of consumers as well as the resource availability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microcystin in cyanobacterial blooms in a Chilean lake.

PubMed

Campos, V; Cantarero, S; Urrutia, H; Heinze, R; Wirsing, B; Neumann, U; Weckesser, J

1999-05-01

Cyanobacterial blooms dominated by Microcystis sp. occurred in lake Rocuant ("marisma", near Concepción/Chile) in February 1995 and 1996. In the bloom samples collected in both years the hepatotoxin microcystin was detected by RP-HPLC in both samples and in the sample of 1995 also by a toxicity assay using primary rat hepatocytes. In the bloom of 1995, the microcystin content of the dry bloom biomass was determined to be 130 micrograms/g on the basis of the RP-HPLC peak area and 800 micrograms/g on the basis of the rat hepatotoxicity assay, respectively. In the bloom of 1996, RP-HPLC analysis revealed a microcystin content of 8.13 micrograms/g bloom material dry weight. In this year no hepatotoxicity was measured using a concentration range up to 0.8 mg (d. w.) of bloom material per ml in the rat hepatotoxicity assay. This is the first report on the detection of microcystins in Chilean water bodies.

Influence of nutrient fluxes on phytoplankton community and harmful algal blooms along the coastal waters of southeastern Arabian Sea

NASA Astrophysics Data System (ADS)

Kumar, P. Sathish; Kumaraswami, M.; Rao, G. Durga; Ezhilarasan, P.; Sivasankar, R.; Rao, V. Ranga; Ramu, K.

2018-06-01

The seasonal variation in phytoplankton composition as well as the influencing factors on phytoplankton community were examined for the coastal waters of Kochi, southeastern Arabian Sea during 2015. The elevated flux of total nitrogen (TN) and silica (Si) during the summer monsoon (SM) induced the harmful algal blooms (HABs) of Scrippsiella trochoidea (11.9 × 105 cells L-1) and Karenia mikimotoi (6 × 105 cells L-1) near the inlets of Kochi estuary. Blooms of S. trochoidea were recorded for the first time in the Indian waters. The satellite data of chlorophyll-a showed the significant correlation with insitu observations of phytoplankton abundance and provided a better understanding of the spatio-temporal distribution. The canonical correspondence analysis indicates that the increased TN and Si fluxes and lower temperature induced the HABs during the SM. The reduction in the load of N and Si in the coastal waters of southeastern Arabian Sea is essential for controlling the HABs.

Siderophores: The special ingredient to cyanobacterial blooms

NASA Astrophysics Data System (ADS)

Du, Xue; Creed, Irena; Trick, Charles

2013-04-01

Freshwater lakes provide a number of significant ecological services including clean drinking water, habitat for aquatic biota, and economic benefits. The provision of these ecological services, as well as the health of these aquatic systems, is threatened by the excessive growth of algae, specifically, cyanobacteria. Historically, blooms have been linked to eutrophication but recent occurrences indicate that there are less dramatic changes that induce these blooms. Iron is an essential micronutrient required for specific essential metabolic pathways; however, the amount of biologically available iron in naturally occurring lake ranges from saturation to much lower than cell transport affinities. To assist in the modulation of iron availabilities, cyanobacteria in culture produce low molecular weight compounds that function in an iron binding and acquisition system; nevertheless, this has yet to be confirmed in naturally occurring lakes. This project explored the relationship of P, N and in particular, Fe, in the promotion of cyanobacteria harmful algal blooms in 30 natural freshwater lakes located in and around the Elk Island National Park, Alberta. It is hypothesized that cyanobacteria produce and utilize iron chelators called siderophores in low Fe and nitrogen (N) conditions, creating a competitive advantage over other algae in freshwater lakes. Lakes were selected to represent a range of iron availability to explore the nutrient composition of lakes that propagated cyanobacteria harmful algal blooms (cHABs) compared to lakes that did not. Lake water was analyzed for nutrients, microbial composition, siderophore concentration, and toxin concentration. Modifications were made to optimize the Czaky and Arnow tests for hydroxamate- and catecholate-type siderophores, respectively, for field conditions. Preliminary results indicate the presence of iron-binding ligands (0.11-2.34 mg/L) in freshwater lakes characterized by widely ranging Fe regimes (0.04-2.74 mg/L). Furthermore, the concentration of iron-binding ligands was found to have a positive correlation to presence of cyanobacteria concentration, indicating a potential relationship between Fe, siderophores, and cyanobacteria. This project works to improve the understanding of freshwater cyanobacteria growth dynamics by investigating the physiological and biochemical processes leading to cHABs. The importance of this project lies in the understanding of elementary nutrient requirements in all algae and how cyanobacteria are able to access low concentration pools and subsequently bloom over other algal species. Investigating the nutrient regimes that stimulate siderophore production and the subsequent production of potentially toxic cyanobacteria blooms is important for lake management and preservation, specifically in the eutrophic and hypereutrophic freshwater lakes of Alberta.

The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms

PubMed Central

Dreano, Denis; Raitsos, Dionysios E.; Gittings, John; Krokos, George; Hoteit, Ibrahim

2016-01-01

Knowledge on large-scale biological processes in the southern Red Sea is relatively limited, primarily due to the scarce in situ, and satellite-derived chlorophyll-a (Chl-a) datasets. During summer, adverse atmospheric conditions in the southern Red Sea (haze and clouds) have long severely limited the retrieval of satellite ocean colour observations. Recently, a new merged ocean colour product developed by the European Space Agency (ESA)—the Ocean Color Climate Change Initiative (OC-CCI)—has substantially improved the southern Red Sea coverage of Chl-a, allowing the discovery of unexpected intense summer blooms. Here we provide the first detailed description of their spatiotemporal distribution and report the mechanisms regulating them. During summer, the monsoon-driven wind reversal modifies the circulation dynamics at the Bab-el-Mandeb strait, leading to a subsurface influx of colder, fresher, nutrient-rich water from the Indian Ocean. Using satellite observations, model simulation outputs, and in situ datasets, we track the pathway of this intrusion into the extensive shallow areas and coral reef complexes along the basin’s shores. We also provide statistical evidence that the subsurface intrusion plays a key role in the development of the southern Red Sea phytoplankton blooms. PMID:28006006

Effects of the phenylurea herbicide diuron on natural riverine microbial communities in an experimental study.

PubMed

Pesce, Stéphane; Fajon, Céline; Bardot, Corinne; Bonnemoy, Frédérique; Portelli, Christophe; Bohatier, Jacques

2006-07-20

The effects of the phenylurea herbicide diuron (10 microgl(-1)) on natural riverine microbial communities were investigated using a three-week laboratory microcosm study. During the first six days, a latency period was observed both in the algal and the bacterial communities despite favorable abiotic conditions and independently of diuron exposure. From the second week, an intense algal bloom (chlorophyll a concentrations and cell abundances) was observed in the uncontaminated microcosms but not in the treated microcosms. The bloom stimulated the bacterial community and led to an increase in heterotrophic bacterial production ([3H]thymidine incorporation), activity (CTC reduction) and cell abundance. In parallel, shifts in bacterial community composition were recorded by polymerase chain reaction (PCR)-temporal temperature gradient gel electrophoresis (TTGE) analysis, whereas no major variation was detected using the fluorescent in situ hybridization (FISH) method. In the treated microcosms, the diuron acted not by damaging the initial communities but by inhibiting the algal bloom and indirectly maintaining constant bacterial conditions throughout the experiment. These inhibitory effects, which were recorded in terms of abundance, activity and diversity, suggest that exposure to diuron can decrease the recovery capacities of microbial communities and delay the resumption of an efficient microbial food web despite favorable environmental conditions.

High-resolution dynamics of the spring bloom in the Gulf of Finland of the Baltic Sea

NASA Astrophysics Data System (ADS)

Lips, Inga; Rünk, Nelli; Kikas, Villu; Meerits, Aet; Lips, Urmas

2014-01-01

During the period from March to the end of May in 2009 and 2010, intensive measurements and sampling were undertaken in the Gulf of Finland. The compiled results indicate a high variability of the phytoplankton distribution both temporally and spatially. The spring bloom dynamics and heterogeneity was influenced by physical forcing, such as prevailing circulation in the surface layer and the development of stratification, including the upward and downward movement of the seasonal thermocline. The estimated ratio of nitrogen to phosphorus consumption during the growth phase of the spring bloom was close to the Redfield ratio during both springs. The maximum phytoplankton carbon biomass was observed after the depletion of inorganic nitrogen from the surface layer, which coincides with the transition in the community dominance from diatoms to dinoflagellates. Diatoms exhibited a short, well-defined period of high biomass, and we argue that measurements with low temporal resolution can overlook this period of diatom dominance in the Gulf of Finland. The observed dominance of dinoflagellates (Peridiniella catenata and the Scrippsiella/Biecheleria complex) and the ciliate Myrionecta rubra might have a substantial biogeochemical impact because these species increase the retention time of newly produced material in the nutrient-limited surface layer in late spring.

Vulnerability of coastal ecosystems to changes in harmful algal bloom distribution in response to climate change: projections based on model analysis.

PubMed

Glibert, Patricia M; Icarus Allen, J; Artioli, Yuri; Beusen, Arthur; Bouwman, Lex; Harle, James; Holmes, Robert; Holt, Jason

2014-12-01

Harmful algal blooms (HABs), those proliferations of algae that can cause fish kills, contaminate seafood with toxins, form unsightly scums, or detrimentally alter ecosystem function have been increasing in frequency, magnitude, and duration worldwide. Here, using a global modeling approach, we show, for three regions of the globe, the potential effects of nutrient loading and climate change for two HAB genera, pelagic Prorocentrum and Karenia, each with differing physiological characteristics for growth. The projections (end of century, 2090-2100) are based on climate change resulting from the A1B scenario of the Intergovernmental Panel on Climate Change Institut Pierre Simon Laplace Climate Model (IPCC, IPSL-CM4), applied in a coupled oceanographic-biogeochemical model, combined with a suite of assumed physiological 'rules' for genera-specific bloom development. Based on these models, an expansion in area and/or number of months annually conducive to development of these HABs along the NW European Shelf-Baltic Sea system and NE Asia was projected for both HAB genera, but no expansion (Prorocentrum spp.), or actual contraction in area and months conducive for blooms (Karenia spp.), was projected in the SE Asian domain. The implications of these projections, especially for Northern Europe, are shifts in vulnerability of coastal systems to HAB events, increased regional HAB impacts to aquaculture, increased risks to human health and ecosystems, and economic consequences of these events due to losses to fisheries and ecosystem services. © 2014 John Wiley & Sons Ltd.

Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon

USGS Publications Warehouse

Kuwabara, James S.; Topping, Brent R.; Carter, James L.; Carlson, Rick A; Parchaso, Francis; Fend, Steven V.; Stauffer-Olsen, Natalie; Manning, Andrew J.; Land, Jennie M.

2016-09-30

Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invertebrates, and physical groundwater-surface water interactions) were not integrated into existing management models for UKL. Up until 2013, all of the benthic-flux studies generally had been limited spatially to a number of sites in the northern part of UKL and limited temporally to 2–3 samplings per year. All of the benthic invertebrate studies also had been limited to the northern part of the lake; however, intensive temporal (weekly) studies had previously been completed independent of benthic-flux studies. Therefore, knowledge of both the spatial and temporal variability in benthic flux and benthic invertebrate distributions for the entire lake was lacking. To address these limitations, we completed a lakewide spatial study during 2013 and a coordinated temporal study with weekly sampling of benthic flux and benthic invertebrates during 2014. Field design of the spatially focused study in 2013 involved 21 sites sampled three times as the summer cyanobacterial bloom developed (that is, May 23, June 13, and July 3, 2013). Results of the 27-week, temporally focused study of one site in 2014 were summarized and partitioned into three periods (referred to herein as pre-bloom, bloom and post-bloom periods), each period involving 9 weeks of profiler deployments, water column and benthic sampling. Partitioning of the pre-bloom, bloom, and post-bloom periods were based on water-column chlorophyll concentrations and involved the following date intervals, respectively: April 15 through June 10, June 17 through August 13, and August 20 through October 16, 2014. To examine dissolved-solute (0.2-micrometer [μm] filtered) benthic flux, sets of nonmetallic pore-water profilers (U.S. Patent 8,051,727 B1) were deployed. In 2013, the deployment of profilers at 21 UKL sites occurred at the beginning of the annual cyanobacterial bloom of Aphanizomenon flos–aquae (AFA), in the middle of the bloom period, and at the peak of the bloom. Coordinated benthic invertebrate collections also were made. Based on results from 2013, weekly deployments of profilers and collection of benthic invertebrate samples from late spring to early autumn were used to estimate temporal trends in solute flux and benthic invertebrate densities. Estimates of nutrient efflux by benthic invertebrates were determined in the spring and autumn from 2011 through 2013 and three times (spring, summer, and autumn) in 2015. This work extends UKL studies that began in 2006 to quantify the importance of benthic solute sources in the lake. In 2015, piezometers and thermistor sets were deployed to quantify potential groundwater exchange with the lake water column. Analysis of the 2013 soluble reactive phosphorus (SRP) benthic flux indicated no effect of location (lake region), habitat, or sampling period, and the average lakewide flux values were consistent with earlier studies that had been confined to the northern region of UKL and adjacent wetlands. The 2014 study therefore focused on estimating temporal trends at a site within Ball Bay. During both 2013 and 2014 field studies, fluxes of macronutrients (soluble reactive phosphorus (SRP) and ammonia) and micronutrients (iron [Fe] and manganese [Mn]) were consistently positive and increased prior to the initial AFA bloom, varied or lagged with water-column chlorophyll during the summer bloom period, then decreased after the cyanobacterial blooms, only to rebound toward pre-bloom conditions in the final weeks of sampling. These four solutes exhibited benthic loads greater than maximum riverine loads estimated during the spring and early summers of 2013 and 2014. However, consistently detectable concentrations for all four solutes provide no evidence that they consistently serve as the limiting nutrient for primary production in the lake. In contrast to the four solutes (SRP, ammonia, Fe, and Mn), benthic fluxes of dissolved arsenic (As) were both negative and positive (that is, the lakebed currently serves as both a source and a sink for dissolved As, depending on season). In a further contrast with SRP, ammonia, dissolved Fe, and Mn, dissolved-As riverine loads to UKL were of similar magnitude to benthic loads. A negative relationship between dissolved-As flux and water-column As over the 2014 temporal study provides a potential advantage for the management of water-quality in contrast to solutes, like SRP or ammonia, with consistently positive flux. The mean total benthic invertebrate density during 2013 was 12,610 individuals per square meter (n=63). Although benthic invertebrate density did not change over the study period, it was higher in littoral habitats than open-lake or trench habitats and higher in the northern region compared to the central or southern regions of UKL. Mean total benthic invertebrate density during 2014 was 19,726 individuals m−2 (n=27). Density during the pre-bloom and bloom periods of April 15 to August 13, 2014 (the first two thirds of the 2014 sampling period), were similar to 2013. However, benthic invertebrate density more than doubled during the latter one-third of the study, that is, the post-bloom period between August 20 to October 16, 2014. Oligochaeta, Chironomidae and Hirudinea represented well over 90 percent of the benthic fauna; Oligochaeta were twice as abundant as Chironomidae or Hirudinea, the latter two of which were similar in density. Benthic invertebrates may enhance dissolved-nutrient (or toxicant) transport across the sediment-water interface by (1) modifying diffusion-layer thicknesses and permeability through bioturbation, (2) enhancing advective flow across the interface through bioirrigation, and (3) excreting or expelling dissolved or particulate solutes directly into the overlying water column (Boudreau and Jorgensen, 2001). We evaluated SRP efflux via excretion for approximately 15 different major taxa in UKL. Once these measures were scaled, it was evident that benthic invertebrates potentially contribute approximately 1.5 times the amount of SRP to the water column of Upper Klamath Lake as diffusive SRP flux alone, measured in profiler deployments. Sets of piezometers and temperature loggers were deployed in UKL to obtain estimates of vertical advective solute flux. The pressure transducer installations, within the piezometers, did not perform as designed, rendering the head gradient data unreliable. However, in terms of future research, this field work did demonstrate the feasibility of collecting vertical gradient data with piezometer deployments. Advective flux estimates herein are based solely on heat-flow modeling based on temperature data from four lake sites, without use of transducer data. Given the magnitudes (both positive or negative) of the heat-transfer fluxes for SRP, relative to diffusive-flux and macroinvertebrate efflux measurements (all positive but spanning the same orders of magnitude), further examination of solute advective flux is recommended as a potential transport process to integrate into existing water-quality (for example, Total Maximum Daily Load [TMDL]) models. As a complement to the biogeochemical focus of this study, initial analyses of suspended-particle (floc) characteristics and settling velocities from the water column were derived near the surface and lakebed at two UKL sites. To better understand changing particle characteristics during the AFA-bloom period, suspended particles were examined in 2015 using a LabSFLOC (LF), which is a Laboratory Spectral Flocculation Characteristics version of an In-Situ Settling Velocity instrument (INSSEV-LF). Particle characteristics and settling velocities were analyzed from the water column near the surface (sample dp_10) and lakebed (sample dp_90) at two lake sites (open-lake site ML and littoral site LS01). The term “floc” refers herein to suspended particles that may aggregate or disaggregate to change in size, composition, and settling velocity. During pre-bloom (May) conditions, where maximum suspended particulate matter concentration (SPMC) was 140 milligrams per liter (mg L−1) was now observed at site LS01 in close proximity to the bed, where Dmean peaked at 305 μm, and the corresponding Wsmean was 3.9 millimeters per second (mm s−1). The high near-bed SPMC (828 mg L−1) experienced during post-bloom October 2015 at LS01 formed a benthic nepheloid layer (BNL) above the lake’s bed. Numerous low density, fast settling macrofloc-sized organic aggregates (D >160 μm) were observed (some up to 1 mm in size) near bed at LS01 both during the bloom and post-bloom conditions; many of these flocs displayed fibrous organic structures. In terms of mass settling fluxes, the post-bloom BNL produced a total MSF of 4,139 milligrams per square meter per second (mg m−2 s−1) (92.1 percent of MSF credited to the macrofloc-sized organic aggregates/cyanobacterial colonies); that was nearly three times the corresponding near-bed settling flux observed during the July 2015 bloom and 360 times greater than the pre-bloom conditions from May 2015 (98.8 percent and 14 percent of MSF credited to the macrofloc-sized fractions for those respective months). Such changes in the near-bed settling flux demonstrate the highly significant seasonal effects that the AFA bloom has on the floc depositional fluxes in UKL and highlights the importance of seasonal monitoring of these conditions in order to correctly parameterize the wide range in depositional characteristics and floc properties measured throughout UKL. Collectively, floc populations observed within UKL demonstrated a wide range in settling velocity (Ws) for a given particle size, D. Similarly, a given settling velocity was not associated with a specific particle size. This variability in particle characteristics and properties indicates the influence of varying floc effective density and its effect on mass and mass settling fluxes (MSF). The use of instruments, such as the INSSEV-LF, enables measuring the variability of settling velocity and its relation to particle density and size.

Blooms of Cyanobacteria on the Potomac River 1

PubMed Central

Krogmann, David W.; Butalla, Ruth; Sprinkle, James

1986-01-01

Blooms of cyanobacteria have appeared on the Potomac River near Washington, DC in years of drought and low river volume. The location of the bloom may be related to tidal activity. In 1983, the bloom of Microcystis aeruginosa used ammonia as its nitrogen source and contained low levels of toxic peptides. Cells collected from this bloom proved to be homogeneous and were an excellent source material for the isolation of proteins involved in photosynthesis. PMID:16664682

Bloom's Taxonomy: Improving Assessment and Teaching-Learning Process

ERIC Educational Resources Information Center

Chandio, Muhammad Tufail; Pandhiani, Saima Murtaza; Iqbal, Rabia

2016-01-01

This research study critically analyzes the scope and contribution of Bloom's Taxonomy in both assessment and teaching-learning process. Bloom's Taxonomy consists of six stages, namely; remembering, understanding, applying, analyzing, evaluating and creating and moves from lower degree to the higher degree. The study applies Bloom's Taxonomy to…

New Zealand risk management approach for toxic cyanobacteria in drinking water.

PubMed

Kouzminov, Alexander; Ruck, John; Wood, Susanna A

2007-06-01

Cyanobacterial blooms are common seasonal phenomena occurring worldwide in fresh, estuarine and coastal waters, including those used for drinking-water supplies, recreation and stock watering. In New Zealand, the frequency of blooms and their geographic spread is likely to grow with increasing eutrophication and global climate change. The New Zealand Ministry of Health has recently developed national criteria for assessing and managing the risk of toxic cyanobacteria in drinking-water supplies. This paper investigates a cyanobacterial bloom incident in the summer 2002/03 in the Waikato River and hydro lakes, which are a major drinking-water supply for Hamilton City and many other smaller towns along the river. The procedures invoked by the Hamilton City Council and other authorities to deal with this bloom event are considered in terms of the best practice of the day and compared with the Drinking-Water Standards for New Zealand 2005. The presence of cyanobacteria has significant economic effects because of increases in water supply treatment costs or the need to use an alternative source, and there are also social effects from the disruption of recreational use of water bodies and loss of confidence in the quality of reticulated, treated water supplies. Notional evaluation of economic cost of monitoring regimes and control, based on the Waikato River cyanobacterial bloom incident, is also given. The multi-barrier and process-control risk management approach, reliant on good vertical communication systems between central and local government, is an advanced approach useful for any country that regularly experiences cyanobacterial problems.

Pyrosequencing reveals benthic bacteria changes responsing to heavy deposition of Microcystis scum in lab — searching bacteria for bloom control

NASA Astrophysics Data System (ADS)

Tang, Yali; Cheng, Dongmei; Guan, Baohua; Zhang, Xiufeng; Liu, Zhengwen; Liu, Zejun

2017-05-01

Bacteria capable of degrading cyanobacteria Microcystis are crucial for determining the ecological consequences of Microcystis blooms in freshwater lakes. Scum derived from Microcystis blooms tends to accumulate in bays of large lakes and then sink to the sediments where it is finally consumed by benthic bacteria. Understanding the response of benthic bacterial communities to massive Microcystis deposition events may help identify the bacteria best suited to Microcystis hydrolyzation and even bloom control. For that purpose, an experimental system was set up in which intact sediment cores were incubated in the laboratory with normal and heavy deposits of Microcystis detritus. Pyrosequencing was performed in order to describe a phylogenetic inventory of bacterial communities in samples taken at 0-1, 1-2 and 2-3 cm depths in incubated sediments and in original untreated sediment. A hierarchical cluster tree was constructed expose differences between sediments. Similarity percentage calculations were also performed to identify the bacterial species contributing to variation. The results of this study suggest that: (1) deposition of Microcystis scums exerts a strong effect on the bacterial community composition in the surface (0-1 cm) and sub-surface (1-2 cm) sediment layers; (2) bacterial community responses to Microcystis detritus deposition vary across vertical gradients. A list of bacteria with potential roles in Microcystis degradation was compiled. These findings may inform the development of future measures for Microcystis bloom control in lakes.

Phytoplankton bloom in the Bay of Biscay

NASA Image and Video Library

2017-12-08

Springtime in the Bay of Biscay, off the coast of France, as in most places, is a season of abundant growth. On April 20, 2013, the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this true-color image of the dynamic growth of a springtime phytoplankton bloom. The swirling colors indicate the presence of vast numbers of phytoplankton – tiny plant-like microorganisms that live in both fresh and salt water. Although these organisms live year-round in the Bay of Biscay, it is only when conditions are right that explosive blooms occur. In spring, the lengthening sunlight, the increased nutrient load swept into the Bay from ocean currents and from snowmelt carried by freshwater rivers, combined with warming waters create the perfect conditions to spur phytoplankton in to tremendous growth. The result is a swirling, multi-hued discoloration that can be easily seen from space. Each year, typically from March through April, such blooms occur in the Bay of Biscay. By May, however, conditions are not as favorable and the blooms fade, then disappear. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team 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. Follow us on Twitter Like us on Facebook Find us on Instagram

Advancing Access to New Technology for Sustained High Resolution Observations of Plankton: From Bloom Dynamics to Climate Change

NASA Astrophysics Data System (ADS)

Sosik, H. M.; Olson, R. J.

2012-12-01

The combination of ocean observatory infrastructure and automated submersible flow cytometry can provide unprecedented capability for sustained high resolution time series of plankton, including taxa that are harmful or early indicators of ecosystem response to environmental change. Over the past decade, we have developed the FlowCytobot series of instruments that exemplify this capability. FlowCytobot and Imaging FlowCytobot use a combination of laser-based scattering and fluorescence measurements and video imaging of individual particles to enumerate and characterize cells ranging from picocyanobacteria to large chaining-forming diatoms. The process of developing these complex instruments was streamlined by access to the Martha's Vineyard Coastal Observatory (MVCO), a cabled facility on the New England Shelf, where real time two-way communications and access to shore power expedited cycles of instrument evaluation and design refinement. Repeated deployments at MVCO, typically 6 months in duration, have produced multi-year high resolution (hourly to daily) time series that are providing new insights into dynamics of community structure such as blooms, seasonality, and possibly even trends linked to regional climate change. The high temporal resolution observations of single cell properties make it possible not only to characterize taxonomic composition and size structure, but also to quantify taxon-specific growth rates. To meet the challenge of broadening access to this enabling technology, we have taken a two-step approach. First, we are partnering with a few scientific collaborators interested in using the instruments in different environments and to address different applications, notably the detection and characterization of harmful algal bloom events. Collaboration at this stage ensured that these first users outside the developers' lab had access to technical know-how required for successful outcomes; it also provided additional feedback that could be incorporated into more robust and user-friendly design. In the second and most recent stage, we have partnered with McLane Research Laboratories, Inc., a commercial vendor licensed to produce and market Imaging FlowCytobot. This stage of the development process has involved interactions between the scientific developers and company engineers, emphasizing joint construction of a pre-commercial prototype. A first run of commercially available units is anticipated to begin in the coming months paving the way for an expanding set of sustained high resolution plankton observations in conjunction with existing and emerging ocean observing systems.

Bioaccumulation of microcystin congeners in soil-plant system and human health risk assessment: A field study from Lake Taihu region of China.

PubMed

Cao, Qing; Steinman, Alan D; Wan, Xiang; Xie, Liqiang

2018-05-02

A 120-day field study was carried out near Lake Taihu to evaluate the bioaccumulation of microcystin (MC) congeners in a soil-plant system, as well as to assess human health risk when consuming edible plants irrigated with MCs-contaminated water. Natural cyanobacteria bloom-containing lake water (lake water) and half-diluted natural cyanobacteria bloom-containing lake water with tap water (half-lake water) were used to irrigate lettuce and rice. An additional treatment involving fertilization with a cyanobacteria bloom was applied just to the lettuce experiment. MCs in soils, roots, leaves and grains (rice) were detected. In the soil-lettuce system, the three MC congeners in soils fertilized with a cyanobacteria bloom were not detected. The highest concentrations of MCs detected in soils, lettuce roots and leaves were 24.8 (MC-LR 10.1, MC-RR 10.5, MC-YR 4.2) μg kg -1 , 424 (MC-LR 168, MC-RR 194, MC-YR 61.5) μg kg -1 and 183 (MC-LR 78.0, MC-RR 76.8, MC-YR 28.1) μg kg -1 , respectively, in the lake water treatment. In the soil-rice system, the highest concentration of MCs was accumulated in roots 1504 (MC-LR 634, MC-RR 573, MC-YR 297) μg kg -1 , in the lake water treatment. However, the concentration of MCs that accumulated in grains was extremely low with a total MCs concentration of 5.2 (MC-LR 2.1, MC-RR 2.0, MC-YR 1.1) μg kg -1 in the lake water treatment. According to the estimated daily intake (EDI) value, fertilizing with an appropriate amount (0.2% or less, w/w, dry weight (DW)) of a cyanobacteria bloom, as well as consuming rice irrigated with lake water would not pose a threat to human health. However, the EDI values for both adults and children reached tolerable daily intake (TDI) value, assuming they consumed lettuce irrigated with lake water. Results obtained from the growth and yield indicators suggest that MCs bioaccumulation in edible plants is not necessarily coupled with phytotoxic effects. Copyright © 2018. Published by Elsevier Ltd.

On the "hidden" phytoplankton blooms on Australia's southern shelves

NASA Astrophysics Data System (ADS)

Kämpf, Jochen; Kavi, Ankit

2017-02-01

Phytoplankton blooms on Australia's southern shelves are revisited using satellite-derived monthly data of chlorophyll a concentrations for the period 2003-2015. It is known that the region hosts a seasonal coastal upwelling system that develops in austral summer (January-March) with chlorophyll a concentrations of >2 mg/m3. While this summer upwelling is spatially limited to a few hot spots, here we show that widespread phytoplankton blooms of moderate ( 1 mg/m3) chlorophyll a concentrations develop during autumn and early winter on most of Australia's extensive southern shelves—from the vast shelves of the Great Australian Bight (GAB) in the west to Bass Strait in the east. This surprising finding disproves the widespread belief that shelf waters of the GAB are generally oligotrophic and may explain the relatively high abundance of both forage fish (sardines) and upper trophic-level predators (e.g., tuna and whales) in the region.

Harmful algal bloom smart device application: using image analysis and machine learning techniques for early classification of harmful algal blooms (SETAC presentation)

EPA Science Inventory

Reports of toxic cyanobacterial blooms, also known as Harmful Algal Blooms (HABS) have increased drastically in recent years. HABS impact human health from causing mild allergies to liver damage and death. The Ecological Stewardship Institute (ESI) at Northern Kentucky Universi...

Hydrogen cyanamide on citrus: preliminary data on phytotoxicity and influence on flush in potted and field trees

USDA-ARS?s Scientific Manuscript database

Bloom in individual citrus trees typically continues for more than a month in south Florida, with even greater bloom duration within most orchard blocks because of variation in bloom timing between trees. Prolonged bloom contributes to variable fruit maturity as harvest approaches and increases seve...

Trichodesmium blooms and warm-core ocean surface features in the Arabian Sea and the Bay of Bengal.

PubMed

Jyothibabu, R; Karnan, C; Jagadeesan, L; Arunpandi, N; Pandiarajan, R S; Muraleedharan, K R; Balachandran, K K

2017-08-15

Trichodesmium is a bloom-forming, diazotrophic, non-heterocystous cyanobacteria widely distributed in the warmer oceans, and their bloom is considered a 'biological indication' of stratification and nitrogen limitation in the ocean surface layer. In the first part of this paper, based on the retrospective analyses of the ocean surface mesoscale features associated with 59 Trichodesmium bloom incidences recorded in the past, 32 from the Arabian Sea and the Bay of Bengal, and 27 from the rest of the world, we have showed that warm-core features have an inducing effect on bloom formation. In the second part, we have considered the environmental preferences of Trichodesmium bloom based on laboratory and field studies across the globe, and proposed a view about how warm-core features could provide an inducing pre-requisite condition for the bloom formation in the Arabian Sea and the Bay of Bengal. Proposed that the subsurface waters of warm-core features maintain more likely chances for the conducive nutrient and light conditions required for the triggering of the blooms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Variations of morphology and photosynthetic performances of Ulva prolifera during the whole green tide blooming process in the Yellow Sea.

PubMed

Zhang, Jian Heng; Huo, Yuan Zi; Zhang, Zheng Long; Yu, Ke Feng; He, Qing; Zhang, Lin Hui; Yang, Li Li; Xu, Ren; He, Pei Min

2013-12-01

Since 2007, the world's largest macroalgal blooms have occurred along the coastal area of the Yellow Sea for 6 consecutive years. In 2012, shipboard surveying and satellite remote sensing were used to monitor the whole blooming process. The blooms originated in Rudong sea area of the South Yellow Sea where bloom patches were of dark green and filamentous thalli were the dominant morphology. The scale of the blooms reached its peak size in Rizhao sea area of the North Yellow Sea, and decreased promptly and became insignificant in Qingdao coast where the blooms turned yellow, mostly with air sac blades. Meanwhile, vegetative cells of the green tide algae changed into cytocysts gradually from which germ cells were released as the blooms drifted northward. Additionally, chlorophyll contents and fluorescence activity of free-floating thalli in the North Yellow Sea were both significantly lower than that in the South Yellow Sea. Those studies presented here contributed to increasing our understanding about how the green tide declined gradually in the North Yellow Sea. Copyright © 2013 Elsevier Ltd. All rights reserved.

A strong summer phytoplankton bloom southeast of Vietnam in 2007, a transitional year from El Niño to La Niña.

PubMed

Zhao, Hui; Zhao, Jian; Sun, Xingli; Chen, Fajin; Han, Guoqi

2018-01-01

Summer upwelling occurs frequently off the southeast Vietnam coast in the western South China Sea (SCS), where summer phytoplankton blooms generally appear during June-August. In this study, we investigate inter-annual variation of Ekman pumping and offshore transport, and its modulation on summer blooms southeast of Vietnam. The results indicate that there are low intensities of summer blooms in El Niño years, under higher sea surface temperatures (SST) and weaker winds. However, a different pattern of monthly chlorophyll a (Chl-a) blooms occurred in summer of 2007, a transitional stage from El Niño to La Niña, with weak (strong) wind and high (low) SST before (after) early July. There is a weak phytoplankton bloom before July 2007 and a strong phytoplankton bloom after July 2007. The abrupt change in the wind intensity may enhance the upwelling associated with Ekman pumping and offshore Ekman transport, bringing more high-nutrient water into the upper layer from the subsurface, and thus leading to an evident Chl-a bloom in the region.

Prevention of Cyanobacterial Blooms Using Nanosilica: A Biomineralization-Inspired Strategy.

PubMed

Xiong, Wei; Tang, Yiming; Shao, Changyu; Zhao, Yueqi; Jin, Biao; Huang, Tingting; Miao, Ya'nan; Shu, Lei; Ma, Weimin; Xu, Xurong; Tang, Ruikang

2017-11-07

Cyanobacterial blooms represent a significant threat to global water resources because blooming cyanobacteria deplete oxygen and release cyanotoxins, which cause the mass death of aquatic organisms. In nature, a large biomass volume of cyanobacteria is a precondition for a bloom, and the cyanobacteria buoyancy is a key parameter for inducing the dense accumulation of cells on the water surface. Therefore, blooms will likely be curtailed if buoyancy is inhibited. Inspired by diatoms with naturally generated silica shells, we found that silica nanoparticles can be spontaneously incorporated onto cyanobacteria in the presence of poly(diallyldimethylammonium chloride), a cationic polyelectrolyte that can simulate biosilicification proteins. The resulting cyanobacteria-SiO 2 complexes can remain sedimentary in water. This strategy significantly inhibited the photoautotrophic growth of the cyanobacteria and decreased their biomass accumulation, which could effectively suppress harmful bloom events. Consequently, several of the adverse consequences of cyanobacteria blooms in water bodies, including oxygen consumption and microcystin release, were significantly alleviated. Based on the above results, we propose that the silica nanoparticle treatment has the potential for use as an efficient strategy for preventing cyanobacteria blooms.

Factors controlling the spatio-temporal distribution of the 2009 Chattonella antiqua bloom in the Yatsushiro Sea, Japan

NASA Astrophysics Data System (ADS)

Aoki, Kazuhiro; Onitsuka, Goh; Shimizu, Manabu; Kuroda, Hiroshi; Matsuyama, Yukihiko; Kimoto, Katsunori; Matsuo, Hitoshi; Kitadai, Yuuki; Sakurada, Kiyonari; Nishi, Hiromi; Tahara, Yoshio

2012-12-01

A harmful bloom due to the raphidophycean flagellate, Chattonella antiqua, was found in the Yatsushiro Sea, western Kyushu, Japan, from the end of July to the beginning of August 2009. The bloom resulted in enormous economic damage to cultured finfish production in aquaculture farms concentrated in the southwestern area. To investigate the factors controlling the spatio-temporal distribution of the bloom, data analysis and numerical simulations were conducted using field monitoring data and a three-dimensional hydrodynamic model coupled to a Lagrangian particle-tracking model. Results of the monitoring data analysis showed that the initial development of the C. antiqua bloom occurred in Kusuura Bay and the northeastern area near the mouth of the Kuma River, and subsequently the bloom expanded rapidly to the whole area. The simulation results indicated that the source region of the widespread bloom was not Kusuura Bay but the northeastern area. The southwestward evolution of the bloom was primarily controlled by the passive transport due to the surface residual current driven by fresh water discharge from the Kuma River and northeasterly winds. On the favorable conditions of river discharge and wind, the massive bloom of C. antiqua that formed in the northeastern area was quickly transported southwestward within a few days.

The timing and the magnitude of spring phytoplankton blooms and their relationship with physical forcing in the central Yellow Sea in 2009

NASA Astrophysics Data System (ADS)

Zhou, Feng; Xuan, Jiliang; Huang, Daji; Liu, Chenggang; Sun, Jun

2013-12-01

The development of phytoplankton bloom and its association with physical forcing is examined through an interdisciplinary field-work conducted in the vicinity of the central trough of the southern Yellow Sea during March-April 2009, with the aid of a surface Lagrangian drifter deployed at the bloom site. Bloom patches were detected using an empirical value and two of them were traced by the drifter for a period of several days respectively. Both of them appears as thin-layer subsurface chlorophyll a maximum (SCM) throughout the tracing, although their dominant phytoplankton species are not identical at all. The magnitude as well as the onset of these two blooms is different from each other, but both found to be relevant to local oceanic and meteorological conditions. Both of them demonstrate that the changes in the stability of hydrographical structure, especially at layers around the SCM, take a substantial role in triggering or terminating the blooming processes. Those changes in meteorological conditions, like wind speed and directions, solar radiation, are short and cause daily or synoptic scale variations in phytoplankton concentrations, but the frequency of northerly wind events predating the bloom season has a positive effect on the occurrence of spring blooms. The horizontal advection is another contributing factor indicated by the drifter which accounts for the bloom extinction at the station B20. In addition, due to the weak orbital horizontal movement, the bloom above the central trough persists longer and larger.

Climate variability and Dinophysis acuta blooms in an upwelling system.

PubMed

Díaz, Patricio A; Ruiz-Villarreal, Manuel; Pazos, Yolanda; Moita, Teresa; Reguera, Beatriz

2016-03-01

Dinophysis acuta is a frequent seasonal lipophilic toxin producer in European Atlantic coastal waters associated with thermal stratification. In the Galician Rías, populations of D. acuta with their epicentre located off Aveiro (northern Portugal), typically co-occur with and follow those of Dinophysis acuminata during the upwelling transition (early autumn) as a result of longshore transport. During hotter than average summers, D. acuta blooms also occur in August in the Rías, when they replace D. acuminata. Here we examined a 30-year (1985-2014) time series of D. acuta from samples collected by the same method in the Galician Rías. Our main objective was to identify patterns of distribution and their relation with climate variability, and to explain the exceptional summer blooms of D. acuta in 1989-1990. A dome-shaped relationship was found between summer upwelling intensity and D. acuta blooms; cell maxima were associated with conditions where the balance between upwelling intensity and heating, leading to deepened thermoclines, combined with tidal phase (3 days after neap tides) created windows of opportunity for this species. The application of a generalized additive model based on biological (D. acuta inoculum) and environmental predictors (Cumulative June-August upwelling CUI JJA , average June-August SST JJA and tidal range) explained more than 70% of the deviance for the exceptional summer blooms of D. acuta, through a combination of moderate (35,000-50,000m 3 s -1 km -1 ) summer upwelling (CUI JJA ), thermal stratification (SST JJA >17°C) and moderate tidal range (∼2.5m), provided D. acuta cells (inoculum) were present in July. There was no evidence of increasing trends in D. acuta bloom frequency/intensity nor a clear relationship with NAO or other long-term climatic cycles. Instead, the exceptional summer blooms of 1989-1990 appeared linked to extreme hydroclimatic anomalies (high positive anomalies in SST and NAO index), which affected most of the European Atlantic coast. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Contributions of meteorology to the phenology of cyanobacterial blooms: implications for future climate change.

PubMed

Zhang, Min; Duan, Hongtao; Shi, Xiaoli; Yu, Yang; Kong, Fanxiang

2012-02-01

Cyanobacterial blooms are often a result of eutrophication. Recently, however, their expansion has also been found to be associated with changes in climate. To elucidate the effects of climatic variables on the expansion of cyanobacterial blooms in Taihu, China, we analyzed the relationships between climatic variables and bloom events which were retrieved by satellite images. We then assessed the contribution of each climate variable to the phenology of blooms using multiple regression models. Our study demonstrates that retrieving ecological information from satellite images is meritorious for large-scale and long-term ecological research in freshwater ecosystems. Our results show that the phenological changes of blooms at an inter-annual scale are strongly linked to climate in Taihu during the past 23 yr. Cyanobacterial blooms occur earlier and last longer with the increase of temperature, sunshine hours, and global radiation and the decrease of wind speed. Furthermore, the duration increases when the daily averages of maximum, mean, and minimum temperature each exceed 20.3 °C, 16.7 °C, and 13.7 °C, respectively. Among these factors, sunshine hours and wind speed are the primary contributors to the onset of the blooms, explaining 84.6% of their variability over the past 23 yr. These factors are also good predictors of the variability in the duration of annual blooms and determined 58.9% of the variability in this parameter. Our results indicate that when nutrients are in sufficiently high quantities to sustain the formation of cyanobacterial blooms, climatic variables become crucial in predicting cyanobacterial bloom events. Climate changes should be considered when we evaluate how much the amount of nutrients should be reduced in Taihu for lake management. Copyright © 2011 Elsevier Ltd. All rights reserved.

The Genetic Diversity of Mesodinium and Associated Cryptophytes

PubMed Central

Johnson, Matthew D.; Beaudoin, David J.; Laza-Martinez, Aitor; Dyhrman, Sonya T.; Fensin, Elizabeth; Lin, Senjie; Merculief, Aaron; Nagai, Satoshi; Pompeu, Mayza; Setälä, Outi; Stoecker, Diane K.

2016-01-01

Ciliates from the genus Mesodinium are globally distributed in marine and freshwater ecosystems and may possess either heterotrophic or mixotrophic nutritional modes. Members of the Mesodinium major/rubrum species complex photosynthesize by sequestering and maintaining organelles from cryptophyte prey, and under certain conditions form periodic or recurrent blooms (= red tides). Here, we present an analysis of the genetic diversity of Mesodinium and cryptophyte populations from 10 environmental samples (eight globally dispersed habitats including five Mesodinium blooms), using group-specific primers for Mesodinium partial 18S, ITS, and partial 28S rRNA genes as well as cryptophyte large subunit RuBisCO genes (rbcL). In addition, 22 new cryptophyte and four new M. rubrum cultures were used to extract DNA and sequence rbcL and 18S-ITS-28S genes, respectively, in order to provide a stronger phylogenetic context for our environmental sequences. Bloom samples were analyzed from coastal Brazil, Chile, two Northeastern locations in the United States, and the Pribilof Islands within the Bering Sea. Additionally, samples were also analyzed from the Baltic and Barents Seas and coastal California under non-bloom conditions. Most blooms were dominated by a single Mesodinium genotype, with coastal Brazil and Chile blooms composed of M. major and the Eastern USA blooms dominated by M. rubrum variant B. Sequences from all four blooms were dominated by Teleaulax amphioxeia-like cryptophytes. Non-bloom communities revealed more diverse assemblages of Mesodinium spp., including heterotrophic species and the mixotrophic Mesodinium chamaeleon. Similarly, cryptophyte diversity was also higher in non-bloom samples. Our results confirm that Mesodinium blooms may be caused by M. major, as well as multiple variants of M. rubrum, and further implicate T. amphioxeia as the key cryptophyte species linked to these phenomena in temperate and subtropical regions. PMID:28066344

The Genetic Diversity of Mesodinium and Associated Cryptophytes.

PubMed

Johnson, Matthew D; Beaudoin, David J; Laza-Martinez, Aitor; Dyhrman, Sonya T; Fensin, Elizabeth; Lin, Senjie; Merculief, Aaron; Nagai, Satoshi; Pompeu, Mayza; Setälä, Outi; Stoecker, Diane K

2016-01-01

Ciliates from the genus Mesodinium are globally distributed in marine and freshwater ecosystems and may possess either heterotrophic or mixotrophic nutritional modes. Members of the Mesodinium major/rubrum species complex photosynthesize by sequestering and maintaining organelles from cryptophyte prey, and under certain conditions form periodic or recurrent blooms (= red tides). Here, we present an analysis of the genetic diversity of Mesodinium and cryptophyte populations from 10 environmental samples (eight globally dispersed habitats including five Mesodinium blooms), using group-specific primers for Mesodinium partial 18S, ITS, and partial 28S rRNA genes as well as cryptophyte large subunit RuBisCO genes ( rbcL ). In addition, 22 new cryptophyte and four new M. rubrum cultures were used to extract DNA and sequence rbcL and 18S-ITS-28S genes, respectively, in order to provide a stronger phylogenetic context for our environmental sequences. Bloom samples were analyzed from coastal Brazil, Chile, two Northeastern locations in the United States, and the Pribilof Islands within the Bering Sea. Additionally, samples were also analyzed from the Baltic and Barents Seas and coastal California under non-bloom conditions. Most blooms were dominated by a single Mesodinium genotype, with coastal Brazil and Chile blooms composed of M. major and the Eastern USA blooms dominated by M. rubrum variant B. Sequences from all four blooms were dominated by Teleaulax amphioxeia -like cryptophytes. Non-bloom communities revealed more diverse assemblages of Mesodinium spp., including heterotrophic species and the mixotrophic Mesodinium chamaeleon . Similarly, cryptophyte diversity was also higher in non-bloom samples. Our results confirm that Mesodinium blooms may be caused by M. major , as well as multiple variants of M. rubrum , and further implicate T. amphioxeia as the key cryptophyte species linked to these phenomena in temperate and subtropical regions.

Spring and fall phytoplankton blooms in a productive subarctic ecosystem, the eastern Bering Sea, during 1995-2011

NASA Astrophysics Data System (ADS)

Sigler, Michael F.; Stabeno, Phyllis J.; Eisner, Lisa B.; Napp, Jeffrey M.; Mueter, Franz J.

2014-11-01

The timing and magnitude of phytoplankton blooms in subarctic ecosystems often strongly influence the amount of energy that is transferred through subsequent trophic pathways. In the eastern Bering Sea, spring bloom timing has been linked to ice retreat timing and production of zooplankton and fish. A large part of the eastern Bering Sea shelf (~500 km wide) is ice-covered during winter and spring. Four oceanographic moorings have been deployed along the 70-m depth contour of the eastern Bering Sea shelf with the southern location occupied annually since 1995, the two northern locations since 2004 and the remaining location since 2001. Chlorophyll a fluorescence data from the four moorings provide 37 realizations of a spring bloom and 33 realizations of a fall bloom. We found that in the eastern Bering Sea: if ice was present after mid-March, spring bloom timing was related to ice retreat timing (p<0.001, df=1, 24); if ice was absent or retreated before mid-March, a spring bloom usually occurred in May or early June (average day 148, SE=3.5, n=11). A fall bloom also commonly occurred, usually in late September (average day 274, SE=4.2, n=33), and its timing was not significantly related to the timing of storms (p=0.88, df=1, 27) or fall water column overturn (p=0.49, df=1, 27). The magnitudes of the spring and fall blooms were correlated (p=0.011, df=28). The interval between the spring and fall blooms varied between four to six months depending on year and location. We present a hypothesis to explain how the large crustacean zooplankton taxa Calanus spp. likely respond to variation in the interval between blooms (spring to fall and fall to spring).

The Forest, Part 3: Year-Round Observations

ERIC Educational Resources Information Center

Johnson, Elfriede Nemetz

1973-01-01

Many experiments can be conducted in spring and early summer when many of the flowering plants must hurriedly bloom before the leafage of the trees and bushes takes most of the needed sunlight away. (DF)

An overview of cyanobacterial bloom occurrences and research in Africa over the last decade.

PubMed

Ndlela, L L; Oberholster, P J; Van Wyk, J H; Cheng, P H

2016-12-01

Cyanobacterial blooms are a current cause for concern globally, with vital water sources experiencing frequent and increasingly toxic blooms in the past decade. These increases are resultant of both anthropogenic and natural factors, with climate change being the central concern. Of the more affected parts of the world, Africa has been considered particularly vulnerable due to its historical predisposition and lag in social economic development. This review collectively assesses the available information on cyanobacterial blooms in Africa as well as any visible trends associated with reported occurrences over the last decade. Of the 54 countries in Africa, only 21 have notable research information in the area of cyanobacterial blooms within the last decade, although there is substantial reason to attribute these blooms as some of the major water quality threats in Africa collectively. The collected information suggests that civil wars, disease outbreaks and inadequate infrastructure are at the core of Africa's delayed advancement. This is even more so in the area of cyanobacteria related research, with 11 out of 21 countries having recorded toxicity and physicochemical parameters related to cyanobacterial blooms. Compared to the rest of the continent, peripheral countries are at the forefront of research related to cyanobacteria, with countries such as Angola having sufficient rainfall, but poor water quality with limited information on bloom occurrences. An assessment of the reported blooms found nitrogen concentrations to be higher in the water column of more toxic blooms, validating recent global studies and indicating that phosphorous is not the only factor to be monitored in bloom mitigation. Blooms occurred at low TN: TP ratios and at temperatures above 12°C. Nitrogen was linked to toxicity and temperature also had a positive effect on bloom occurrence and toxicity. Microcystis was the most ubiquitous of the cyanobacterial strains reported in Africa and the one most frequently toxic. Cylindrospermopsis was reported more in the dry, north and western parts of the continent countries as opposed to the rest of the continent, whilst Anabaena was more frequent on the south eastern regions. In light of the entire continent, the inadequacy in reported blooms and advances in this area of research require critical intervention and action. Copyright © 2016 Elsevier B.V. All rights reserved.

Observation of the Central Part of the Beta-Pictoris Disk with an Anti-Blooming CCD

NASA Astrophysics Data System (ADS)

Lecavelier Des Etangs, A.; Perrin, G.; Ferlet, R.; Vidal Madjar, A.; Colas, F.; Buil, C.; Sevre, F.; Arlot, J. E.; Beust, H.; Lagrange Henri, A. M.; Lecacheux, J.; Deleuil, M.; Gry, C.

1993-07-01

β Pictoris (A5V) possesses a circumstellar disk of gas and dust which is oriented edge-on to Earth. Possibly a planet may be indirectly responsible for spectroscopic events, presently interpreted as the signature of the vaporisation of comet-like bodies when grazing the star, and may have cleared up dust particles in the inner zone. Previous coronographic studies coupled with IRAS and ground based IR observations also seem to indicate that the inner regions of the disk may be possibly dust free. We have extended the coronographic studies closer to the star in order to directly observe this zone, through a different observational technique based on the use of an anti- blooming CCD. These new observations, recorded at La Silla (Chile), revealed the structure of the disk down to two arcsec from the star (30 AU from the star). A different nature of dust particles seems to be present in the inner regions of the disk, in possible relation with a planetary formation process. Also an inverted asymmetry is observed in the inner region of the disk when compared to the outer one, a structure possibly related to a non homogeneous distribution of the dust within the disk.

Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA

NASA Astrophysics Data System (ADS)

Weisend, R.; Morton, P. L.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Phytoplankton in oligotrophic marine deserts depend on remote sources to supply trace nutrients. To examine these sources, marine particulate matter samples from the central North Pacific (Station ALOHA) were collected during the July-August 2012 HOE-DYLAN cruises and analyzed for a suite of trace (e.g., Fe, Mn) and major (e.g. Al, P) elements. Daily surface SPM samples were examined for evidence of atmospheric deposition and biological uptake, while five vertical profiles were examined for evidence of surface vertical export and subsurface horizontal transport from nearby sources (e.g., margin sediments, hydrothermal plumes). Maxima in surface particulate P (a biological tracer) corresponded with a diatom bloom, and surprisingly also coincided with maxima in particulate Al (typically a tracer for lithogenic inputs). The surface particulate Al distributions likely result from the adsorption of dissolved Al onto diatom silica frustules, not from atmospheric dust deposition. In addition, a subsurface maximum in particulate Al and P was observed four days later at 75m, possibly resulting from vertical export of the surface diatom bloom. The distributions of other bioactive trace elements (e.g. Cd, Co, Cu) will be presented in the context of the diatom bloom and other biological, chemical and physical features. A second, complementary poster is also being presented which examines the cycling of trace elements in lithogenic particles (Morton et al., "Trace Element Cycling in Lithogenic Particles at Station ALOHA").

Privacy-Preserving Distributed Information Sharing

DTIC Science & Technology

2006-07-01

80 B.2.4 Analysis for Bloom Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 B.3 Details of One...be chosen by slightly adjusting the analysis given in the proof of Theorem 26. 59 Using Bloom Filters. Bloom filters provide a compact probabilistic...representation of set membership [6]. Instead of using T filters, we can use a combined Bloom filter. This achieves the same asymptotic communication

Rapid establishment of the CO2 sink associated with Kerguelen's bloom observed during the KEOPS2/OISO20 cruise

NASA Astrophysics Data System (ADS)

Lo Monaco, C.; Metzl, N.; D'Ovidio, F.; Llort, J.; Ridame, C.

2014-12-01

Iron and light are the main factors limiting the biological pump of CO2 in the Southern Ocean. Iron fertilization experiments have demonstrated the potential for increased uptake of atmospheric CO2, but little is known about the evolution of fertilized environnements. This paper presents observations collected in one of the largest phytoplankton bloom of the Southern Ocean sustained by iron originating from the Kerguelen Plateau. We first complement previous studies by investigating the mechanisms that control air-sea CO2 fluxes over and downstream of the Kerguelen Plateau at the onset of the bloom based on measurements obtained in October-November 2011. These new observations show the rapid establishment of a strong CO2 sink in waters fertilized with iron as soon as vertical mixing is reduced. The magnitude of the CO2 sink was closely related to chlorophyll a and iron concentrations. Because iron concentration strongly depends on the distance from the iron source and the mode of delivery, we identified lateral advection as the main mechanism controlling air-sea CO2 fluxes downtream the Kerguelen Plateau during the growing season. In the southern part of the bloom, situated over the Plateau (iron source), the CO2 sink was stronger and spatially more homogeneous than in the plume offshore. However, we also witnessed a substantial reduction in the uptake of atmospheric CO2 over the Plateau following a strong winds event. Next, we used all the data available in this region in order to draw the seasonal evolution of air-sea CO2 fluxes. The CO2 sink is rapidly reduced during the course of the growing season, which we attribute to iron and silicic acid depletion. South of the Polar Front, where nutrients depletion is delayed, we suggest that the amplitude and duration of the CO2 sink is mainly controlled by vertical mixing. The impact of iron fertilization on air-sea CO2 fluxes is revealed by comparing the uptake of CO2 integrated over the productive season in the bloom, between 1 and 1.5 mol C m-2 yr-1, and in the iron-poor HNLC waters, where we found a typical value of 0.4 mol C m-2 yr-1. Extrapolating our results to the ice-free Southern Ocean (~50-60° S) suggests that iron fertilization of the whole area would increase the contemporay oceanic uptake of CO2 by less than 0.1 Pg C yr-1, i.e., less than 1% of the current anthropogenic CO2 emissions.

Seasonal Progression and Interannual Variability of Nutrient and Chlorophyll-a Distributions in the Northern Gulf of Alaska, 1998-2010

NASA Astrophysics Data System (ADS)

Trahanovsky, K.; Whitledge, T. E.

2016-02-01

We examined nutrient and chlorophyll-a (chl) concentrations from bottle samples collected from 0-50 m depth in the Northern Gulf of Alaska along the Seward Line transect on 56 cruises from 1998-2010. We computed monthly average concentrations of macronutrients (N, P, and Si) and chlorophyll-a by depth at four major stations along the transect to describe the regular seasonal progression of the nutricline and typical water column distributions of chlorophyll-a in this seasonally productive, downwelling coastal zone. The across-shelf transect displayed two different patterns of seasonal progression clearly associated with the Alaska Coastal Current (ACC) and Alaskan Stream (AS) current systems. The annual cycle of nutrient drawdown and replenishment is remarkably consistent from year to year within each system and is well correlated with chl measurements. The spring bloom begins earlier and nutrient depletion is sustained longer in the near-shore ACC then in the AS system centered over the shelf break. Chlorophyll-a concentrations frequently peak at 10-20m depth in both systems during July through October, as nutrients remain depleted in the top 10m. Subsurface nutrients (20 - 50 m depth) begin to recover between July and August and then experience a secondary drawdown between August and October, consistent with higher chl levels observed during the fall bloom. Interannual variability in the progression of the nutricline and the relative contribution of subsurface chl to total chl is presented. Physical data demonstrate increasing stratification in this region due to climate change; the implications for nutrient dynamics and primary production are discussed.

Successful integration efforts in water quality from the integrated Ocean Observing System Regional Associations and the National Water Quality Monitoring Network

USGS Publications Warehouse

Ragsdale, R.; Vowinkel, E.; Porter, D.; Hamilton, P.; Morrison, R.; Kohut, J.; Connell, B.; Kelsey, H.; Trowbridge, P.

2011-01-01

The Integrated Ocean Observing System (IOOS??) Regional Associations and Interagency Partners hosted a water quality workshop in January 2010 to discuss issues of nutrient enrichment and dissolved oxygen depletion (hypoxia), harmful algal blooms (HABs), and beach water quality. In 2007, the National Water Quality Monitoring Council piloted demonstration projects as part of the National Water Quality Monitoring Network (Network) for U.S. Coastal Waters and their Tributaries in three IOOS Regional Associations, and these projects are ongoing. Examples of integrated science-based solutions to water quality issues of major concern from the IOOS regions and Network demonstration projects are explored in this article. These examples illustrate instances where management decisions have benefited from decision-support tools that make use of interoperable data. Gaps, challenges, and outcomes are identified, and a proposal is made for future work toward a multiregional water quality project for beach water quality.

Harmful Algal Bloom Webinar

EPA Pesticide Factsheets

The problem is complex. Excessive nitrogen and phosphorous levels can cause harmful algal blooms. Different algal/cyanobacteria strains bloom under different conditions. Different strains produce different toxins at varying amounts.

Bacterial community transcription patterns during a marine phytoplankton bloom.

PubMed

Rinta-Kanto, Johanna M; Sun, Shulei; Sharma, Shalabh; Kiene, Ronald P; Moran, Mary Ann

2012-01-01

Bacterioplankton consume a large proportion of photosynthetically fixed carbon in the ocean and control its biogeochemical fate. We used an experimental metatranscriptomics approach to compare bacterial activities that route energy and nutrients during a phytoplankton bloom compared with non-bloom conditions. mRNAs were sequenced from duplicate bloom and control microcosms 1 day after a phytoplankton biomass peak, and transcript copies per litre of seawater were calculated using an internal mRNA standard. Transcriptome analysis revealed a potential novel mechanism for enhanced efficiency during carbon-limited growth, mediated through membrane-bound pyrophosphatases [V-type H(+)-translocating; hppA]; bloom bacterioplankton participated less in this metabolic energy scavenging than non-bloom bacterioplankton, with possible implications for differences in growth yields on organic substrates. Bloom bacterioplankton transcribed more copies of genes predicted to increase cell surface adhesiveness, mediated by changes in bacterial signalling molecules related to biofilm formation and motility; these may be important in microbial aggregate formation. Bloom bacterioplankton also transcribed more copies of genes for organic acid utilization, suggesting an increased importance of this compound class in the bioreactive organic matter released during phytoplankton blooms. Transcription patterns were surprisingly faithful within a taxon regardless of treatment, suggesting that phylogeny broadly predicts the ecological roles of bacterial groups across 'boom' and 'bust' environmental backgrounds. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

A drinking water crisis in Lake Taihu, China: linkage to climatic variability and lake management.

PubMed

Qin, Boqiang; Zhu, Guangwei; Gao, Guang; Zhang, Yunlin; Li, Wei; Paerl, Hans W; Carmichael, Wayne W

2010-01-01

In late May, 2007, a drinking water crisis took place in Wuxi, Jiangsu Province, China, following a massive bloom of the toxin producing cyanobacteria Microcystis spp. in Lake Taihu, China's third largest freshwater lake. Taihu was the city's sole water supply, leaving approximately two million people without drinking water for at least a week. This cyanobacterial bloom event began two months earlier than previously documented for Microcystis blooms in Taihu. This was attributed to an unusually warm spring. The prevailing wind direction during this period caused the bloom to accumulate at the shoreline near the intake of the water plant. Water was diverted from the nearby Yangtze River in an effort to flush the lake of the bloom. However, this management action was counterproductive, because it produced a current which transported the bloom into the intake, exacerbating the drinking water contamination problem. The severity of this microcystin toxin containing bloom and the ensuing drinking water crisis were attributable to excessive nutrient enrichment; however, a multi-annual warming trend extended the bloom period and amplified its severity, and this was made worse by unanticipated negative impacts of water management. Long-term management must therefore consider both the human and climatic factors controlling these blooms and their impacts on water supply in this and other large lakes threatened by accelerating eutrophication.

Predicting potentially toxigenic Pseudo-nitzschia blooms in the Chesapeake Bay

USGS Publications Warehouse

Anderson, C.R.; Sapiano, M.R.P.; Prasad, M.B.K.; Long, W.; Tango, P.J.; Brown, C.W.; Murtugudde, R.

2010-01-01

Harmful algal blooms are now recognized as a significant threat to the Chesapeake Bay as they can severely compromise the economic viability of important recreational and commercial fisheries in the largest estuary of the United States. This study describes the development of empirical models for the potentially domoic acid-producing Pseudo-nitzschia species complex present in the Bay, developed from a 22-year time series of cell abundance and concurrent measurements of hydrographic and chemical properties. Using a logistic Generalized Linear Model (GLM) approach, model parameters and performance were compared over a range of Pseudo-nitzschia bloom thresholds relevant to toxin production by different species. Small-threshold blooms (???10cellsmL-1) are explained by time of year, location, and variability in surface values of phosphate, temperature, nitrate plus nitrite, and freshwater discharge. Medium- (100cellsmL-1) to large- threshold (1000cellsmL-1) blooms are further explained by salinity, silicic acid, dissolved organic carbon, and light attenuation (Secchi) depth. These predictors are similar to other models for Pseudo-nitzschia blooms on the west coast, suggesting commonalities across ecosystems. Hindcasts of bloom probabilities at a 19% bloom prediction point yield a Heidke Skill Score of -53%, a Probability of Detection ~75%, a False Alarm Ratio of ~52%, and a Probability of False Detection ~9%. The implication of possible future changes in Baywide nutrient stoichiometry on Pseudo-nitzschia blooms is discussed. ?? 2010 Elsevier B.V.

The correlation between Prorocentrum donghaiense blooms and the Taiwan warm current in the East China Sea - evidence for the "Pelagic Seed Bank" hypothesis.

PubMed

Dai, Xinfeng; Lu, Douding; Guan, Weibing; Xia, Ping; Wang, Hongxia; He, Piaoxia; Zhang, Dongsheng

2013-01-01

During the last two decades, large-scale high biomass algal blooms of the dinoflagellate Prorocentrum donghaiense Lu have occurred frequently in the East China Sea (ECS). The role of increasing nutrient concentrations in driving those blooms is well-established, but the source population that initiates them is poorly understood. We hypothesized that the front of Taiwan Warm Current (TWC) may serve as a 'seed bank' that initiates P. donghaiense blooms in the ECS, as the physiochemical conditions in the TWC are suitable for the growth of P. donghaiense. In order to test this hypothesis, two surveys at different spatio-temporal scales were conducted in 2010 and 2011. We found a strong correlation in space and time between the abundance of P. donghaiense and the TWC. The spatial extent of the P. donghaiense bloom coincided with the TWC front in both 2010 and 2011. During the early development of the blooms, P. donghaiense concentration was highest at the TWC front, and then the bloom mass shifted inshore over the course of our 2011 survey. The TWC also moved inshore, albeit after the appearance of P. donghaiense. Overall, these results support our hypothesis that P. donghaiense blooms develop from the population at the TWC front in the ECS, suggesting the role of the ocean current front as a seed bank to dinoflagellate blooms.

Application of Multispectral and Hyperspectral Remote Sensing For Detection of Freshwater Harmful Algal Blooms

NASA Astrophysics Data System (ADS)

Kudela, R. M.; Accorsi, E.; Austerberry, D.; Palacios, S. L.

2013-12-01

Freshwater Cyanobacterial Harmful algal blooms (CHABs) represent a pressing and apparently increasing threat to both human and environmental health. In California, toxin producing blooms of several species, including Aphanizomenon, Microcystis, Lyngbya, and Anabaena are common; toxins from these blooms have been linked to impaired drinking water, domestic and wild animal deaths, and increasing evidence for toxin transfer to coastal marine environments, including the death of several California sea otters, a threatened marine species. California scientists and managers are under increasing pressure to identify and mitigate these potentially toxic blooms, but point-source measurements and grab samples have been less than effective. There is increasing awareness that these toxic events are both spatially widespread and ephememeral, leading to the need for better monitoring methods applicable to large spatial and temporal scales. Based on monitoring in several California water bodies, it appears that Aphanizomenon blooms frequently precede dangerous levels of toxins from Microcystis. We are exploring new detection methods for identifying CHABs and potentially distinguishing between blooms of the harmful cyanobacteria Aphanizomenon and Microcystis using remote sensing reflectance from a variety of airborne and satellite sensors. We suggest that Aphanizomenon blooms could potentially be used as an early warning of more highly toxic subsequent blooms, and that these methods, combined with better toxin monitoring, can lead to improved understanding and prediction of CHABs by pinpointing problematic watersheds.

A Preliminary Bloom's Taxonomy Assessment of End-of-Chapter Problems in Business School Textbooks

ERIC Educational Resources Information Center

Marshall, Jennings B.; Carson, Charles M.

2008-01-01

This article examines textbook problems used in a sampling of some of the most common core courses found in schools of business to ascertain what level of learning, as defined by Bloom's Taxonomy, is required to provide a correct answer. A set of working definitions based on Bloom's Taxonomy (Bloom & Krathwohl, 1956) was developed for the six…

3. GENERAL VIEW OF REMAINS OF 40" BLOOMING MILL; THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. GENERAL VIEW OF REMAINS OF 40" BLOOMING MILL; THE ENGINE ROOM CONTAINING THE MESTA-CORLISS STEAM ENGINE, IS LOCATED AT THE FAR END OF THE MILL AS SEEN TO THE FAR RIGHT (THE BUILDING WITH THE SHED ROOF). - Republic Iron & Steel Company, Youngstown Works, Blooming Mill & Blooming Mill Engines, North of Poland Avenue, Youngstown, Mahoning County, OH

A strong summer phytoplankton bloom southeast of Vietnam in 2007, a transitional year from El Niño to La Niña

PubMed Central

Chen, Fajin; Han, Guoqi

2018-01-01

Summer upwelling occurs frequently off the southeast Vietnam coast in the western South China Sea (SCS), where summer phytoplankton blooms generally appear during June-August. In this study, we investigate inter-annual variation of Ekman pumping and offshore transport, and its modulation on summer blooms southeast of Vietnam. The results indicate that there are low intensities of summer blooms in El Niño years, under higher sea surface temperatures (SST) and weaker winds. However, a different pattern of monthly chlorophyll a (Chl-a) blooms occurred in summer of 2007, a transitional stage from El Niño to La Niña, with weak (strong) wind and high (low) SST before (after) early July. There is a weak phytoplankton bloom before July 2007 and a strong phytoplankton bloom after July 2007. The abrupt change in the wind intensity may enhance the upwelling associated with Ekman pumping and offshore Ekman transport, bringing more high-nutrient water into the upper layer from the subsurface, and thus leading to an evident Chl-a bloom in the region. PMID:29342148

Development and Application of an Acoustic System for Harmful Algal Blooms (HABs, Red Tide) Detection using an Ultrasonic Digital Sensor

NASA Astrophysics Data System (ADS)

Kim, Hansoo; Kang, Donhyug; Jung, Seung Won

2018-03-01

The overgrowth of phytoplankton leads to negative effects such as harmful algal blooms (HABs, also called red tides) in marine environments. The HAB species Cochlodinium polykrikoides ( C. polykrikoides) appears frequently in Korea during summer. In this study, we developed a real-time acoustic detection and remote-control system to detect red tides using an ultrasonic digital sensor. In the laboratory, the acoustic signals increased as the number of cells increased. At the same time, for field application, we deployed the system near the southern coast of Korea, where red tides frequently occurred in summer seasons 2013-2015. The system developed here detected red tides in situ, with a good correlation between the acoustic signals and C. polykrikoides populations. These results suggest that it may be useful for early detection of red tides.

Mesoscale Eddies Control the Timing of Spring Phytoplankton Blooms: A Case Study in the Japan Sea

NASA Astrophysics Data System (ADS)

Maúre, E. R.; Ishizaka, J.; Sukigara, C.; Mino, Y.; Aiki, H.; Matsuno, T.; Tomita, H.; Goes, J. I.; Gomes, H. R.

2017-11-01

Satellite Chlorophyll a (CHL) data were used to investigate the influence of mesoscale anticyclonic eddies (AEs) and cyclonic eddies (CEs) on the timing of spring phytoplankton bloom initiation around the Yamato Basin (133-139°E and 35-39.5°N) in the Japan Sea, for the period 2002-2011. The results showed significant differences between AEs and CEs in the timing and initiation mechanism of the spring phytoplankton bloom. Blooms were initiated earlier in CEs which were characterized by shallow mixed-layer depths (< 100 m). The early blooming preceded the end of winter cooling (i.e., while net heat flux (Q0) is still negative) and is initiated by the increased average light within the shallow mixed-layer depth. Conversely, blooms appeared in the AEs despite deeper mixed-layer depth (> 100 m) but close to the commencement of positive Q0. This suggests that the relaxation of turbulent mixing is crucial for the bloom initiation in AEs.

Mowing mitigates bioactivity of neonicotinoid insecticides in nectar of flowering lawn weeds and turfgrass guttation.

PubMed

Larson, Jonathan L; Redmond, Carl T; Potter, Daniel A

2015-01-01

Systemic neonicotinoid insecticides are used to control turfgrass insect pests. The authors tested their transference into nectar of flowering lawn weeds or grass guttation droplets, which, if high enough, could be hazardous to bees or other insects that feed on such exudates. The authors applied imidacloprid or clothianidin to turf with white clover, followed by irrigation, and used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze residues in clover blooms that were directly sprayed during application or that formed after the first mowing. Imidacloprid residues in guttation fluid from field-grown creeping bentgrass were assessed similarly. The authors used Orius insidiosus, a small anthrocorid bug that is sensitive to dietary neonicotinoids, as a bioindicator of the exudates' toxicity. Nectar from directly sprayed clover blooms contained 5493 ng/g to 6588 ng/g imidacloprid or 2882 ng/g to 2992 ng/g clothianidin and was acutely toxic to Orius. Residues were 99.4% to 99.8% lower in nectar of blooms formed after mowing, and nontoxic to Orius. Imidacloprid residues in turfgrass guttation averaged 88 ng/g at 1 wk after treatment, causing some intoxication of Orius, but declined to 23 ng/g within 3 wk. Systemic transference of neonicotinoids into white clover nectar and creeping bentgrass guttation appears relatively low and transitory. The hazard to nontarget insects via nectar of flowering weeds in treated lawns can be mitigated by adhering to label precautions and mowing to remove blooms if they are inadvertently sprayed. © 2014 SETAC.

Areas contributing ground water to the Peconic Estuary, and ground-water budgets for the north and south forks and Shelter Island, eastern Suffolk County, New York

USGS Publications Warehouse

Schubert, C.E.

1998-01-01

The Peconic Estuary, at the eastern end of Long Island, has been plagued by a recurrent algal bloom, locally referred to as ?Brown Tide,? that has caused the severe decline of local marine resources. Although the factors that trigger Brown Tide blooms remain uncertain, groundwater discharge has previously been shown to affect surface-water quality in the western part of the estuary. A U.S. Geological Survey groundwater- flow model of the main body of Long Island indicates that a total of about 7.5 x 106 ft3/d (cubic feet per day) of freshwater discharges to the western part of the estuary, but the model does not include the ground-water flow systems on the North and South Forks and Shelter Island, which contribute significant amounts of freshwater to the central and eastern parts of the estuary. The need for information on freshwater discharge to the entire estuary prompted the U.S. Geological Survey to evaluate ground-water discharge from the North and South Forks and Shelter Island. Source areas that contribute ground water to the Peconic Estuary were delineated, and groundwater budgets for these areas were developed, to evaluate the distribution and magnitude of ground-water discharge to the central and eastern parts of the estuary. Contributing-area boundaries that were delineated coincide with the hydraulic boundaries of the fresh ground-water-flow systems of the North and South Forks and Shelter Island; these boundaries are of two types? external (saltwater bodies) and internal (groundwater divides). Hydrologic components that were evaluated include recharge from precipitation, public-supply withdrawal and return flow, and agricultural withdrawal. Values for each of these components were calculated or estimated for the individual freshwater flow subsystems that form each ground-water-budget area, then summed to obtain the total discharge of fresh ground water to tidewater. Ground-water discharge to the Peconic Estuary is about 3.8 x 106 ft3/d from the North Fork, 11 x 106 ft3/d from the South Fork, and 1.7 x 106 ft3/d from Shelter Island. The total contribution to the estuary from these areas is about 16 x 106 ft3/d?roughly twice the total contribution from the main body of Long Island. In contrast to the freshwater contribution from the main body of Long Island, which is concentrated near the head of the estuary, the contributions from the North and South Forks and Shelter Island are distributed along the east-west length of the estuary. Changes in water-table altitude and the resulting changes in total discharge to the Peconic Estuary were estimated from the relative changes in annual mean water level at observation wells. The 1985-95 interval included 7 years (1985-88, 1991- 92, 1995) of generally below-average water-table altitudes that presumably caused similar decreases in ground-water discharge to the estuary; intense Brown Tide blooms coincided with six of these years (1985-88, 1991, 1995), and localized blooms coincided with the remaining year (1992). Watertable altitudes in the remaining 4 years of the 1985-95 interval (1989-90, 1993-94) were nearly average or above average, and presumably produced comparably near-average or increased amounts of ground-water discharge to the estuary; none of these years saw any widespread Brown Tide blooms. Fluctuations in the amounts of ground-water discharge to the estuary appear to affect the occurrence of Brown Tide blooms, although the factors that trigger the blooms have not been determined.

Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress.

PubMed

Walsh, Catherine J; Butawan, Matthew; Yordy, Jennifer; Ball, Ray; Flewelling, Leanne; de Wit, Martine; Bonde, Robert K

2015-04-01

The health of many Florida manatees (Trichechus manatus latirostris) is adversely affected by exposure to blooms of the toxic dinoflagellate, Karenia brevis. K. brevis blooms are common in manatee habitats of Florida's southwestern coast and produce a group of cyclic polyether toxins collectively referred to as red tide toxins, or brevetoxins. Although a large number of manatees exposed to significant levels of red tide toxins die, several manatees are rescued from sublethal exposure and are successfully treated and returned to the wild. Sublethal brevetoxin exposure may potentially impact the manatee immune system. Lymphocyte proliferative responses and a suite of immune function parameters in the plasma were used to evaluate effects of brevetoxin exposure on health of manatees rescued from natural exposure to red tide toxins in their habitat. Blood samples were collected from rescued manatees at Lowry Park Zoo in Tampa, FL and from healthy, unexposed manatees in Crystal River, FL. Peripheral blood leukocytes (PBL) isolated from whole blood were stimulated with T-cell mitogens, ConA and PHA. A suite of plasma parameters, including plasma protein electrophoresis profiles, lysozyme activity, superoxide dismutase (SOD) activity, and reactive oxygen/nitrogen (ROS/RNS) species, was also used to assess manatee health. Significant decreases (p<0.05) in lymphocyte proliferation were observed in ConA and PHA stimulated lymphocytes from rescued animals compared to non-exposed animals. Significant correlations were observed between oxidative stress markers (SOD, ROS/RNS) and plasma brevetoxin concentrations. Sublethal exposure to brevetoxins in the wild impacts some immune function components, and thus, overall health, in the Florida manatee. Copyright © 2015 Elsevier B.V. All rights reserved.

Why related bacterial species bloom simultaneously in the gut: principles underlying the 'Like will to like' concept.

PubMed

Winter, Sebastian E; Bäumler, Andreas J

2014-02-01

The large intestine is host to a complex ecological community composed predominantly of obligate anaerobic bacteria belonging to the classes Bacteroidia and Clostridia. This community confers benefits through its metabolic activities and host interactions. However, a microbial imbalance (dysbiosis) characterized by a decreased abundance of Clostridia and a bloom of facultative anaerobic Proteobacteria is commonly observed during inflammation in the large bowel. Here we review recent insights into the principles that favour simultaneous increases in the abundance of closely related species belonging to the Proteobacteria during inflammation, which provides important clues for the rational design of strategies to treat dysbiosis. © 2013 John Wiley & Sons Ltd.

Phytoplankton bloom in the North Atlantic Ocean

NASA Image and Video Library

2017-12-08

On July 23, 2013 the deep blue waters of the central North Atlantic Ocean provided a background for a spectacular bloom of phytoplankton. The Moderate Resolution Imaging Spectroradiometer (MODIS) captured this true-color image of the event at 16:25 UTC (12:25 p.m. EDT) that same day. Phytoplankton are tiny single-celled photosynthetic organisms that live suspended in a watery environment. They are primary producers in the ocean, forming the base of the marine food chain, and, like terrestrial plants, take up carbon dioxide, make carbohydrates from energy from light, and release oxygen. Phytoplankton live in the ocean year round, but are usually not visible. When light, nutrients and water temperature are just right, however, a colony can explode into growth, creating huge blooms that stain the ocean for miles. While each organism lives only a short time, the high reproductive means that a bloom can last for days or weeks. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team 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. Follow us on Twitter Like us on Facebook Find us on Instagram

Mitigating Harmful Cyanobacterial Blooms in a Human- and Climatically-Impacted World

PubMed Central

Paerl, Hans W.

2014-01-01

Bloom-forming harmful cyanobacteria (CyanoHABs) are harmful from environmental, ecological and human health perspectives by outcompeting beneficial phytoplankton, creating low oxygen conditions (hypoxia, anoxia), and by producing cyanotoxins. Cyanobacterial genera exhibit optimal growth rates and bloom potentials at relatively high water temperatures; hence, global warming plays a key role in their expansion and persistence. CyanoHABs are regulated by synergistic effects of nutrient (nitrogen:N and phosphorus:P) supplies, light, temperature, vertical stratification, water residence times, and biotic interactions. In most instances, nutrient control strategies should focus on reducing both N and P inputs. Strategies based on physical, chemical (nutrient) and biological manipulations can be effective in reducing CyanoHABs; however, these strategies are largely confined to relatively small systems, and some are prone to ecological and environmental drawbacks, including enhancing release of cyanotoxins, disruption of planktonic and benthic communities and fisheries habitat. All strategies should consider and be adaptive to climatic variability and change in order to be effective for long-term control of CyanoHABs. Rising temperatures and greater hydrologic variability will increase growth rates and alter critical nutrient thresholds for CyanoHAB development; thus, nutrient reductions for bloom control may need to be more aggressively pursued in response to climatic changes globally. PMID:25517134

Roles of Ferrous and Sulfide Ions in the Fromation of Algae—Induced Black Bloom in Hyper Eutrophic Freshwater Lakes in China

NASA Astrophysics Data System (ADS)

Shen, Q.; Gao, Q.; Yu, C.; Zhang, L.; Wang, Z.

2016-12-01

Water column hypoxia is one of the most serious threats from eutrophication to large water bodies. In the past several years, black bloom phenomenon has become a serious ecosystem disaster in some important severe eutrophic lakes in China, which caused not only environment degradation but also drinking water crisis. Black color and offensive odour of the water column are two notorious sensory features. High Fe2+ and ΣH2S (ΣS2-=S2-+HS-+H2S) were typical characteristics of the black bloom water. Analysis of the black substances of the black bloom water using X-ray photoelectron spectroscopy indicated that abundant FeS were included in these particulates. The black color of the black bloom water could be attributed to the formation of FeS in the anoxic/anaerobic water column. Field investigation and laboratory incubation experiment indicated that the formation of black bloom was closely related to the Fe2+ and ΣH2S in surface sediments. The Fe2+ concentration in surface sediment pore water was high and showed a release tendency from the sediment water interface to the overlying water during the formation of black bloom, while the similar trend was found in ΣH2S production at sediment water micro-interface. Both Fe2+ and ΣS2- affected by oxic and redox conditions, respectively, contributed to the formation of black bloom significantly. However, ΣS2- was found to be the limiting factor directly controlling the outbreak of black bloom. Analysis of microbioal community diversity demonstrated that sulfate reducing bacteria (SRB) were abundant in the surface sediment of black bloom, which strongly influenced the production and accumulation of ΣH2S and drove the formation of black bloom.

Brevetoxins, like ciguatoxins, are potent ichthyotoxic neurotoxins that accumulate in fish✩

PubMed Central

Naar, Jerome P.; Flewelling, Leanne J.; Lenzi, Allison; Abbott, Jay P.; Granholm, April; Jacocks, Henry M.; Gannon, Damon; Henry, Michael; Pierce, Richard; Baden, Daniel G.; Wolny, Jennifer; Landsberg, Jan H.

2009-01-01

Brevetoxins and ciguatoxins are closely related potent marine neurotoxins. Although ciguatoxins accumulate in fish to levels that are dangerous for human consumption, live fish have not been considered as potential sources of brevetoxin exposure in humans. Here we show that, analogous to ciguatoxins, brevetoxins can accumulate in live fish by dietary transfer. We experimentally identify two pathways leading to brevetoxin-contaminated omnivorous and planktivorous fish. Fish fed with toxic shellfish and Karenia brevis cultures remained healthy and accumulated high brevetoxin levels in their tissues (up to 2675 ng g−1 in viscera and 1540 ng g−1 in muscle). Repeated collections of fish from St. Joseph Bay in the Florida panhandle reveal that accumulation of brevetoxins in healthy fish occurs in the wild. We observed that levels of brevetoxins in the muscle of fish at all trophic levels rise significantly, but not to dangerous levels, during a K. brevis bloom. Concentrations were highest in fish liver and stomach contents, and increased during and immediately following the bloom. The persistence of brevetoxins in the fish food web was followed for 1 year after the K. brevis bloom. PMID:17675204

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

Bishop, James K.B.; Wood, Todd

Three Carbon Explorer (CE) floats profiling to kilometer depths in the Southern Ocean tracked dawn-dusk variations of mixing/stratification, particulate organic carbon (POC), and light scattering and sedimentation at 100, 250, and 800 m continuously from January 2002 to April 2003. Data were analyzed in conjunction with contemporaneous satellite winds and chlorophyll and derived subsurface light fields. The CE deployed at 66{sup o}S 172{sup o}W operated in the ice edge zone in absence of light. Two CEs deployed at 55{sup o}S 172{sup o}W recorded wintertime mixing to {approx}400 m, yet observed very different bloom dynamics and sedimentation the following spring. Fourmore » hypotheses are explored. The strongest is that shallow transient stratification of the deep winter mixed layer to shallower than photosynthetic critical depth occurred more frequently in the non-bloom/higher sedimentation case. The lower particle export to 800 m under the bloom was hypothesized to be due to higher interception of sinking carbon by a relatively starved over wintering zooplankton population. In the Southern Ocean surface phytoplankton biomass may counter indicate particle flux at kilometer depths.« less

Nitrogen Fixed By Cyanobacteria Is Utilized By Deposit-Feeders

PubMed Central

Karlson, Agnes M. L.; Gorokhova, Elena; Elmgren, Ragnar

2014-01-01

Benthic communities below the photic zone depend for food on allochthonous organic matter derived from seasonal phytoplankton blooms. In the Baltic Sea, the spring diatom bloom is considered the most important input of organic matter, whereas the contribution of the summer bloom dominated by diazotrophic cyanobacteria is less understood. The possible increase in cyanobacteria blooms as a consequence of eutrophication and climate change calls for evaluation of cyanobacteria effects on benthic community functioning and productivity. Here, we examine utilization of cyanobacterial nitrogen by deposit-feeding benthic macrofauna following a cyanobacteria bloom at three stations during two consecutive years and link these changes to isotopic niche and variations in body condition (assayed as C:N ratio) of the animals. Since nitrogen-fixing cyanobacteria have δ15N close to -2‰, we expected the δ15N in the deposit-feeders to decrease after the bloom if their assimilation of cyanobacteria-derived nitrogen was substantial. We also expected the settled cyanobacteria with their associated microheterotrophic community and relatively high nitrogen content to increase the isotopic niche area, trophic diversity and dietary divergence between individuals (estimated as the nearest neighbour distance) in the benthic fauna after the bloom. The three surface-feeding species (Monoporeia affinis, Macoma balthica and Marenzelleria arctia) showed significantly lower δ15N values after the bloom, while the sub-surface feeder Pontoporeia femorata did not. The effect of the bloom on isotopic niche varied greatly between stations; populations which increased niche area after the bloom had better body condition than populations with reduced niche, regardless of species. Thus, cyanobacterial nitrogen is efficiently integrated into the benthic food webs in the Baltic, with likely consequences for their functioning, secondary production, transfer efficiency, trophic interactions, and intra- and interspecific competition. PMID:25105967

Seasonality of North Atlantic phytoplankton from space: impact of environmental forcing on a changing phenology (1998-2012).

PubMed

González Taboada, Fernando; Anadón, Ricardo

2014-03-01

Seasonal pulses of phytoplankton drive seasonal cycles of carbon fixation and particle sedimentation, and might condition recruitment success in many exploited species. Taking advantage of long-term series of remotely sensed chlorophyll a (1998-2012), we analyzed changes in phytoplankton seasonality in the North Atlantic Ocean. Phytoplankton phenology was analyzed based on a probabilistic characterization of bloom incidence. This approach allowed us to detect changes in the prevalence of different seasonal cycles and, at the same time, to estimate bloom timing and magnitude taking into account uncertainty in bloom detection. Deviations between different sensors stressed the importance of a prolonged overlap between successive missions to ensure a correct assessment of phenological changes, as well as the advantage of semi-analytical chlorophyll algorithms over empirical ones to reduce biases. Earlier and more intense blooms were detected in the subpolar Atlantic, while advanced blooms of less magnitude were common in the Subtropical gyre. In the temperate North Atlantic, spring blooms advanced their timing and decreased in magnitude, whereas fall blooms delayed and increased their intensity. At the same time, the prevalence of locations with a single autumn/winter bloom or with a bimodal seasonal cycle increased, in consonance with a poleward expansion of subtropical conditions. Changes in bloom timing and magnitude presented a clear signature of environmental factors, especially wind forcing, although changes on incident photosynthetically active radiation and sea surface temperature were also important depending on latitude. Trends in bloom magnitude matched changes in mean chlorophyll a during the study period, suggesting that seasonal peaks drive long-term trends in chlorophyll a concentration. Our results link changes in North Atlantic climate with recent trends in the phenology of phytoplankton, suggesting an intensification of these impacts in the near future. © 2013 John Wiley & Sons Ltd.

Nitrogen fixed by cyanobacteria is utilized by deposit-feeders.

PubMed

Karlson, Agnes M L; Gorokhova, Elena; Elmgren, Ragnar

2014-01-01

Benthic communities below the photic zone depend for food on allochthonous organic matter derived from seasonal phytoplankton blooms. In the Baltic Sea, the spring diatom bloom is considered the most important input of organic matter, whereas the contribution of the summer bloom dominated by diazotrophic cyanobacteria is less understood. The possible increase in cyanobacteria blooms as a consequence of eutrophication and climate change calls for evaluation of cyanobacteria effects on benthic community functioning and productivity. Here, we examine utilization of cyanobacterial nitrogen by deposit-feeding benthic macrofauna following a cyanobacteria bloom at three stations during two consecutive years and link these changes to isotopic niche and variations in body condition (assayed as C:N ratio) of the animals. Since nitrogen-fixing cyanobacteria have δ(15)N close to -2‰, we expected the δ(15)N in the deposit-feeders to decrease after the bloom if their assimilation of cyanobacteria-derived nitrogen was substantial. We also expected the settled cyanobacteria with their associated microheterotrophic community and relatively high nitrogen content to increase the isotopic niche area, trophic diversity and dietary divergence between individuals (estimated as the nearest neighbour distance) in the benthic fauna after the bloom. The three surface-feeding species (Monoporeia affinis, Macoma balthica and Marenzelleria arctia) showed significantly lower δ(15)N values after the bloom, while the sub-surface feeder Pontoporeia femorata did not. The effect of the bloom on isotopic niche varied greatly between stations; populations which increased niche area after the bloom had better body condition than populations with reduced niche, regardless of species. Thus, cyanobacterial nitrogen is efficiently integrated into the benthic food webs in the Baltic, with likely consequences for their functioning, secondary production, transfer efficiency, trophic interactions, and intra- and interspecific competition.

Blooming reduces the antioxidant capacity of dark chocolate in rats without lowering its capacity to improve lipid profiles.

PubMed

Shadwell, Naomi; Villalobos, Fatima; Kern, Mark; Hong, Mee Young

2013-05-01

Dark chocolate contains high levels of antioxidants which are linked to a reduced risk of cardiovascular disease. Chocolate blooming occurs after exposure to high temperatures. Although bloomed chocolate is safe for human consumption, it is not known whether or not the biological function of bloomed chocolate is affected. We hypothesized that bloomed chocolate would reduce the antioxidant potential and lipid-lowering properties of chocolate through altered expression of related genes. Thirty Sprague-Dawley rats were divided into 3 groups and fed either the control (CON), regular dark chocolate (RDC), or bloomed dark chocolate (BDC) diet. After 3 weeks, serum lipid levels and antioxidant capacity were measured. Hepatic expression of key genes was determined by real time polymerase chain reaction (PCR). Sensory characteristics of bloomed versus regular chocolate were assessed in 28 semi-trained panelists. Rats fed RDC exhibited greater serum antioxidant capacities compared to the CON (P < .05). Antioxidant levels of BDC were not different from RDC or CON. Both RDC and BDC lowered TG compared to CON (P < .05). The rats fed RDC had higher high-density lipoprotein levels compared to the CON (P < .05). In rats given RDC, fatty acid synthase gene expression was down-regulated and low-density lipoprotein receptor transcription was up-regulated (P < .05). Sensory panelists preferred the appearance and surface smoothness of the regular chocolate compared to bloomed chocolate (P < .001). Although blooming blunted the robust antioxidant response produced by regular dark chocolate, these results suggest that bloomed dark chocolate yields similarly beneficial effects on most blood lipid parameters or biomarkers. However, regular dark chocolate may be more beneficial for the improvement of antioxidant status and modulation of gene expression involved in lipid metabolism and promoted greater sensory ratings. Copyright © 2013 Elsevier Inc. All rights reserved.

Significance of the Autumn Bloom within the Seasonal Cycle of Primary Production in a Temperate Continental Shelf Sea

NASA Astrophysics Data System (ADS)

Wihsgott, Juliane U.; Sharples, Jonathan; Hopkins, Joanne; Woodward, Malcolm; Greenwood, Naomi; Sivyer, Dave; Hull, Tom

2017-04-01

Autumnal phytoplankton blooms are considered characteristic features of the seasonal cycle of primary productivity in most temperate and subpolar oceans. While observations of their occurrence and strength have been documented extensively, their significance within the seasonal cycle of primary production is not well quantified. Our aim is to establish the role the autumn bloom plays within the seasonal cycle and estimate its contribution to the annual primary production of a temperate continental shelf. In particular, we will illustrate that the autumn bloom has the potential to be as productive as the well-studied summer sub-surface chlorophyll maximum (SCM) and the capacity to significantly contribute to the drawdown of atmospheric CO2. We do this by combining long-term, high resolution observations of water column structure, meteorological forcing, nitrate and chlorophyll fluorescence over the entire seasonal cycle observed in a temperate shelf sea. We present a new series of continuous measurements spanning 17 months (March 2014 - July 2015), which were collected in a temperate shelf sea on the North West European Shelf. A long-term mooring array recorded full depth vertical density structure, dynamics and meteorological data as well as surface chlorophyll fluorescence biomass and inorganic nutrient data over a full seasonal cycle at a station 120 km north-east from the continental shelf break. Eight process cruises supplied additional full depth profiles of chlorophyll fluorescence biomass and macronutrients. The breakdown of stratification in 2014 commenced in early October due to increased winds compared to summer months, and a predominantly negative net heat flux (the ocean lost heat to the overlying atmosphere). Vertical mixing in autumn not only transformed the vertical density structure but also the vertical structure of chlorophyll biomass and surface nutrients. The SCM became eroded and instead a vertically homogeneous profile of chlorophyll biomass established itself above the pycnocline. This increased mixing also led to replenishment of surface nutrients and drove enhanced growth, which was almost 4 times stronger than observed during the summer months: We find an increase in depth integrated chlorophyll biomass of ˜50 mg m-2 in autumn 2014 compared to values of ˜20 mg m-2 during the summers of 2014 and 2015.

7 CFR 51.1356 - Pears grown from late blooms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Pears for Canning Definitions § 51.1356 Pears grown from late blooms. Pears grown from late blooms. Such pears often have excessively long stems...

7 CFR 51.1356 - Pears grown from late blooms.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Pears for Canning Definitions § 51.1356 Pears grown from late blooms. Pears grown from late blooms. Such pears often have excessively long stems...

Predicting potentially toxigenic Pseudo-nitzschia blooms in the Chesapeake Bay

NASA Astrophysics Data System (ADS)

Anderson, Clarissa R.; Sapiano, Mathew R. P.; Prasad, M. Bala Krishna; Long, Wen; Tango, Peter J.; Brown, Christopher W.; Murtugudde, Raghu

2010-11-01

Harmful algal blooms are now recognized as a significant threat to the Chesapeake Bay as they can severely compromise the economic viability of important recreational and commercial fisheries in the largest estuary of the United States. This study describes the development of empirical models for the potentially domoic acid-producing Pseudo-nitzschia species complex present in the Bay, developed from a 22-year time series of cell abundance and concurrent measurements of hydrographic and chemical properties. Using a logistic Generalized Linear Model (GLM) approach, model parameters and performance were compared over a range of Pseudo-nitzschia bloom thresholds relevant to toxin production by different species. Small-threshold blooms (≥10 cells mL -1) are explained by time of year, location, and variability in surface values of phosphate, temperature, nitrate plus nitrite, and freshwater discharge. Medium- (100 cells mL -1) to large- threshold (1000 cells mL -1) blooms are further explained by salinity, silicic acid, dissolved organic carbon, and light attenuation (Secchi) depth. These predictors are similar to other models for Pseudo-nitzschia blooms on the west coast, suggesting commonalities across ecosystems. Hindcasts of bloom probabilities at a 19% bloom prediction point yield a Heidke Skill Score of ~53%, a Probability of Detection ˜ 75%, a False Alarm Ratio of ˜ 52%, and a Probability of False Detection ˜9%. The implication of possible future changes in Baywide nutrient stoichiometry on Pseudo-nitzschia blooms is discussed.

The costs of respiratory illnesses arising from Florida gulf coast Karenia brevis blooms.

PubMed

Hoagland, Porter; Jin, Di; Polansky, Lara Y; Kirkpatrick, Barbara; Kirkpatrick, Gary; Fleming, Lora E; Reich, Andrew; Watkins, Sharon M; Ullmann, Steven G; Backer, Lorraine C

2009-08-01

Algal blooms of Karenia brevis, a harmful marine algae, occur almost annually off the west coast of Florida. At high concentrations, K. brevis blooms can cause harm through the release of potent toxins, known as brevetoxins, to the atmosphere. Epidemiologic studies suggest that aerosolized brevetoxins are linked to respiratory illnesses in humans. We hypothesized a relationship between K. brevis blooms and respiratory illness visits to hospital emergency departments (EDs) while controlling for environmental factors, disease, and tourism. We sought to use this relationship to estimate the costs of illness associated with aerosolized brevetoxins. We developed a statistical exposure-response model to express hypotheses about the relationship between respiratory illnesses and bloom events. We estimated the model with data on ED visits, K. brevis cell densities, and measures of pollen, pollutants, respiratory disease, and intra-annual population changes. We found that lagged K. brevis cell counts, low air temperatures, influenza outbreaks, high pollen counts, and tourist visits helped explain the number of respiratory-specific ED diagnoses. The capitalized estimated marginal costs of illness for ED respiratory illnesses associated with K. brevis blooms in Sarasota County, Florida, alone ranged from $0.5 to $4 million, depending on bloom severity. Blooms of K. brevis lead to significant economic impacts. The costs of illness of ED visits are a conservative estimate of the total economic impacts. It will become increasingly necessary to understand the scale of the economic losses associated with K. brevis blooms to make rational choices about appropriate mitigation.

Detection of Coccolithophore Blooms in Ocean Color Satellite Imagery: a Generalized Approach for Use with Multiple Sensors

NASA Technical Reports Server (NTRS)

Moore, Timothy; Dowell, Mark; Franz, Bryan A.

2012-01-01

A generalized coccolithophore bloom classifier has been developed for use with ocean color imagery. The bloom classifier was developed using extracted satellite reflectance data from SeaWiFS images screened by the default bloom detection mask. In the current application, we extend the optical water type (OWT) classification scheme by adding a new coccolithophore bloom class formed from these extracted reflectances. Based on an in situ coccolithophore data set from the North Atlantic, the detection levels with the new scheme were between 1,500 and 1,800 coccolithophore cellsmL and 43,000 and 78,000 lithsmL. The detected bloom area using the OWT method was an average of 1.75 times greater than the default bloom detector based on a collection of SeaWiFS 1 km imagery. The versatility of the scheme is shown with SeaWiFS, MODIS Aqua, CZCS and MERIS imagery at the 1 km scale. The OWT scheme was applied to the daily global SeaWiFS imagery mission data set (years 19972010). Based on our results, average annual coccolithophore bloom area was more than two times greater in the southern hemisphere compared to the northern hemi- sphere with values of 2.00 106 km2 and 0.75 106 km2, respectively. The new algorithm detects larger bloom areas in the Southern Ocean compared to the default algorithm, and our revised global annual average of 2.75106 km2 is dominated by contributions from the Southern Ocean.

Effect of climate change and mollusc invasion on eutrophication and algae blooms in the lagoon ecosystems of the Baltic Sea

NASA Astrophysics Data System (ADS)

Aleksandrov, Sergei; Gorbunova, Julia; Rudinskaya, Lilia

2015-04-01

Coastal lagoons are most vulnerable to impacts of natural environmental and anthropogenic factors. The Curonian Lagoon and Vistula Lagoon are the largest coastal lagoons of the Baltic Sea, relating to the most highly productive water bodies of Europe. The Curonian Lagoon is choke mostly freshwater lagoon, while the Vistula Lagoon is restricted brackish water lagoon. In the last decades the nutrients loading changes, warming trend and biological invasions are observed. The researches (chlorophyll, primary production, nutrients, phytoplankton, benthos, etc) were carried out monthly since 1991 to 2014. The database includes 1600 stations in the Curonian Lagoon, 1650 stations in the Vistula Lagoon. Eutrophication and algae blooms are most important problems. Multiple reductions of nutrients loading from the watershed area in 1990s did not result in considerable improvement of the ecological situation in the lagoons. The Curonian Lagoon may be characterized as hypertrophic water body with "poor" water quality. Climate change in 1990s-2000s combined with other factors (freshwater, slow-flow exchange, high nutrients concentrations) creates conditions for Cyanobacteria "hyperblooms". Hyperbloom of Cyanophyta (average for the growing season Chl > 100 μg/l) were observed during 4 years in 1990s and 7 years in 2000s. The summer water temperature is the key environmental factor determining the seasonal and long-term variability of the primary production and algae blooms. Mean annual primary production in 2010-2014 (600 gC·m-2·year-1) is considerable higher, than in the middle of 1970s (300 gC·m-2·year-1). The local climate warming in the Baltic region caused ongoing eutrophication and harmful algae blooms in the Curonian Lagoon despite of significant reduction of nutrients loading in 1990s-2000s. Harmful algal blooms in July-October (chlorophyll to 700-3400 μg/l) result in deterioration of the water chemical parameters, death of fish in the coastal zone and pollution with toxins, symptoms of exposure are observed at different trophic levels (zooplankton, fish). "Hyperblooms" of Cyanobacteria is the most dangerous for coastal towns (Polessk, Zelenogradsk) and tourist resorts (UNESCO National Park "Curonian Spit"). Also, unfavorable effects of eutrophication have been observed in restricted Vistula Lagoon. Mean annual temperature increased by 1.4°С for 40 years, and water warming combined with other factors created conditions for phytoplankton "hyperblooms" (70-80 μg Chl/l) in 1995-2010. Mean annual primary production in 2000s (430 gC·m-2·year-1) is considerable higher, than in the middle of 1970s (300 gC·m-2·year-1). The climate warming was cause ongoing eutrophication and harmful algal blooms in summer in 1990-2010 despite of significant reduction of nutrients loading in the lagoon. After the invasion of the North American filter-feeding bivalve Rangia cuneata the benthic biomass increased by 8 times (360 g/m2), and chlorophyll decreased by 3.5 times (10 μg/l) in 2011. Water quality is significantly improved from "poor" to "satisfactory" level in 2011-2014, e.g., transparency increased by 2 times. The phytoplankton assimilation numbers increased to maximum (300-400 mgC·mgChl-1·day-1), which are discover in aquatic ecosystems, and primary production remained at previous level. Therefore mollusc invasion improved water quality, but Vistula lagoon ecosystem remained at eutrophic-hypertrophic level. This allowed the function to other trophic groups (zooplankton, fish) at a stable long-term level.

An Efficient Index Dissemination in Unstructured Peer-to-Peer Networks

NASA Astrophysics Data System (ADS)

Takahashi, Yusuke; Izumi, Taisuke; Kakugawa, Hirotsugu; Masuzawa, Toshimitsu

Using Bloom filters is one of the most popular and efficient lookup methods in P2P networks. A Bloom filter is a representation of data item indices, which achieves small memory requirement by allowing one-sided errors (false positive). In the lookup scheme besed on the Bloom filter, each peer disseminates a Bloom filter representing indices of the data items it owns in advance. Using the information of disseminated Bloom filters as a clue, each query can find a short path to its destination. In this paper, we propose an efficient extension of the Bloom filter, called a Deterministic Decay Bloom Filter (DDBF) and an index dissemination method based on it. While the index dissemination based on a standard Bloom filter suffers performance degradation by containing information of too many data items when its dissemination radius is large, the DDBF can circumvent such degradation by limiting information according to the distance between the filter holder and the items holders, i. e., a DDBF contains less information for faraway items and more information for nearby items. Interestingly, the construction of DDBFs requires no extra cost above that of standard filters. We also show by simulation that our method can achieve better lookup performance than existing ones.

Intravascular optical coherence tomography light scattering artifacts: merry-go-rounding, blooming, and ghost struts

PubMed Central

Mancuso, J. Jacob; Halaney, David L.; Elahi, Sahar; Ho, Derek; Wang, Tianyi; Ouyang, Yongjian; Dijkstra, Jouke; Milner, Thomas E.; Feldman, Marc D.

2014-01-01

Abstract. We sought to elucidate the mechanisms underlying two common intravascular optical coherence tomography (IV-OCT) artifacts that occur when imaging metallic stents: “merry-go-rounding” (MGR), which is an increase in strut arc length (SAL), and “blooming,” which is an increase in the strut reflection thickness (blooming thickness). Due to uncontrollable variables that occur in vivo, we performed an in vitro assessment of MGR and blooming in stented vessel phantoms. Using Xience V and Driver stents, we examined the effects of catheter offset, intimal strut coverage, and residual blood on SAL and blooming thickness in IV-OCT images. Catheter offset and strut coverage both caused minor MGR, while the greatest MGR effect resulted from light scattering by residual blood in the vessel lumen, with 1% hematocrit (Hct) causing a more than fourfold increase in SAL compared with saline (p<0.001). Residual blood also resulted in blooming, with blooming thickness more than doubling when imaged in 0.5% Hct compared with saline (p<0.001). We demonstrate that a previously undescribed mechanism, light scattering by residual blood in the imaging field, is the predominant cause of MGR. Light scattering also results in blooming, and a newly described artifact, three-dimensional-MGR, which results in “ghost struts” in B-scans. PMID:25545341

Development of Phaeocystis globosa blooms in the upwelling waters of the South Central coast of Viet Nam

NASA Astrophysics Data System (ADS)

Hai, Doan-Nhu; Lam, Nguyen-Ngoc; Dippner, Joachim W.

2010-11-01

Blooms of haptophyte algae in the south central coastal waters of Viet Nam often occur in association with upwelling phenomenon during the southwest (SW) monsoon. Depending on the magnitude of the blooms, damage to aquaculture farms may occur. Based on two years of data on biology, oceanography, and marine chemistry, the present study suggests a conceptual model of the growth of the haptophyte Phaeocystis globosa. At the beginning of the bloom, low temperature and abundant nutrient supply, especially nitrate from rain and upwelling, favour bloom development. Diatoms utilize available nitrate and phosphate; subsequently, higher ammonium concentration allows P. globosa to grow faster than the diatoms. At the end of the Phaeocystis bloom, free cells may become available as food for a heterotrophic dinoflagellate species, Noctiluca scintillans. During and after the phytoplankton bloom, remineralization by bacteria reduces dissolved oxygen to a very low concentration at depth, and favors growth of nitrate-reducing bacteria.A Lagrangian Harmful Algal Bloom (HAB) model, driven by a circulation model of the area, realistically simulates the transport of microalgae in surface waters during strong and weak SW monsoon periods, suggesting that it may be a good tool for early warning of HABs in Vietnamese coastal waters.

7 CFR 51.1356 - Pears grown from late blooms.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS) United States Standards for Pears for Canning Definitions § 51.1356 Pears grown from late blooms. Pears grown from late blooms. Such pears often have excessively long stems (commonly termed “rat tails...

7 CFR 51.1356 - Pears grown from late blooms.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS) United States Standards for Pears for Canning Definitions § 51.1356 Pears grown from late blooms. Pears grown from late blooms. Such pears often have excessively long stems (commonly termed “rat tails...

7 CFR 51.1356 - Pears grown from late blooms.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS) United States Standards for Pears for Canning Definitions § 51.1356 Pears grown from late blooms. Pears grown from late blooms. Such pears often have excessively long stems (commonly termed “rat tails...

Mitigating Toxic Planktonic Cyanobacterial Blooms in Aquatic Ecosystems Facing Increasing Anthropogenic and Climatic Pressures

PubMed Central

2018-01-01

Toxic planktonic cyanobacterial blooms are a pressing environmental and human health problem. Blooms are expanding globally and threatening sustainability of our aquatic resources. Anthropogenic nutrient enrichment and hydrological modifications, including water diversions and reservoir construction, are major drivers of bloom expansion. Climatic change, i.e., warming, more extreme rainfall events, and droughts, act synergistically with human drivers to exacerbate the problem. Bloom mitigation steps, which are the focus of this review, must consider these dynamic interactive factors in order to be successful in the short- and long-term. Furthermore, these steps must be applicable along the freshwater to marine continuum connecting streams, lakes, rivers, estuarine, and coastal waters. There is an array of physical, chemical, and biological approaches, including flushing, mixing, dredging, application of algaecides, precipitating phosphorus, and selective grazing, that may arrest and reduce bloom intensities in the short-term. However, to ensure long term, sustainable success, targeting reductions of both nitrogen and phosphorus inputs should accompany these approaches along the continuum. Lastly, these strategies should accommodate climatic variability and change, which will likely modulate and alter nutrient-bloom thresholds. PMID:29419777

Algicidal bacteria in the sea and their impact on algal blooms.

PubMed

Mayali, Xavier; Azam, Farooq

2004-01-01

Over the past two decades, many reports have revealed the existence of bacteria capable of killing phytoplankton. These algicidal bacteria sometimes increase in abundance concurrently with the decline of algal blooms, suggesting that they may affect algal bloom dynamics. Here, we synthesize the existing knowledge on algicidal bacteria interactions with marine eukaryotic microalgae. We discuss the effectiveness of the current methods to characterize the algicidal phenotype in an ecosystem context. We briefly consider the literature on the phylogenetic identification of algicidal bacteria, their interaction with their algal prey, the characterization of algicidal molecules, and the enumeration of algicidal bacteria during algal blooms. We conclude that, due to limitations of current methods, the evidence for algicidal bacteria causing algal bloom decline is circumstantial. New methods and an ecosystem approach are needed to test hypotheses on the impact of algicidal bacteria in algal bloom dynamics. This will require enlarging the scope of inquiry from its current focus on the potential utility of algicidal bacteria in the control of harmful algal blooms. We suggest conceptualizing bacterial algicidy within the general problem of bacterial regulation of algal community structure in the ocean.

Identification of genetically and oceanographically distinct blooms of jellyfish

PubMed Central

Lee, Patricia L. M.; Dawson, Michael N; Neill, Simon P.; Robins, Peter E.; Houghton, Jonathan D. R.; Doyle, Thomas K.; Hays, Graeme C.

2013-01-01

Reports of nuisance jellyfish blooms have increased worldwide during the last half-century, but the possible causes remain unclear. A persistent difficulty lies in identifying whether blooms occur owing to local or regional processes. This issue can be resolved, in part, by establishing the geographical scales of connectivity among locations, which may be addressed using genetic analyses and oceanographic modelling. We used landscape genetics and Lagrangian modelling of oceanographic dispersal to explore patterns of connectivity in the scyphozoan jellyfish Rhizostoma octopus, which occurs en masse at locations in the Irish Sea and northeastern Atlantic. We found significant genetic structure distinguishing three populations, with both consistencies and inconsistencies with prevailing physical oceanographic patterns. Our analyses identify locations where blooms occur in apparently geographically isolated populations, locations where blooms may be the source or result of migrants, and a location where blooms do not occur consistently and jellyfish are mostly immigrant. Our interdisciplinary approach thus provides a means to ascertain the geographical origins of jellyfish in outbreaks, which may have wide utility as increased international efforts investigate jellyfish blooms. PMID:23287405

Comparison of the efficacy of MODIS and MERIS data for detecting cyanobacterial blooms in the southern Caspian Sea.

PubMed

Moradi, Masoud

2014-10-15

Medium Resolution Imaging Spectrometer (MERIS) data, Moderate Resolution Imaging Spectroradiometer (MODIS) data, and hydro-biological measurements were used to detect two very severe blooms in the southern Caspian Sea in 2005 and 2010. The MERIS Cyanobacteria Index (CIMERIS) was more reliable for detecting cyanobacterial blooms. The CIMERIS and MODIS cyanobacteria indices (CIMODIS) were compared in an effort to find a reliable method for detecting future blooms, as MERIS data were not available after April 2012. The CIMODIS had a linear relationship with and similar spatial patterns to the CIMERIS. On the CIMODIS images, extremely high biomass cyanobacteria patches were masked. A comparison of classified in situ data with the CIMODIS and Floating Algal Index (FAI) from four images of a severe bloom event in 2005 showed that the FAI is a reliable index for bloom detection over extremely dense patches. The corrected CIMODIS, the MODIS FAI and in situ data are adequate tools for cyanobacterial bloom monitoring in the southern Caspian Sea. Copyright © 2014 Elsevier Ltd. All rights reserved.

A cold phase of the East Pacific triggers new phytoplankton blooms in San Francisco Bay.

PubMed

Cloern, James E; Jassby, Alan D; Thompson, Janet K; Hieb, Kathryn A

2007-11-20

Ecological observations sustained over decades often reveal abrupt changes in biological communities that signal altered ecosystem states. We report a large shift in the biological communities of San Francisco Bay, first detected as increasing phytoplankton biomass and occurrences of new seasonal blooms that began in 1999. This phytoplankton increase is paradoxical because it occurred in an era of decreasing wastewater nutrient inputs and reduced nitrogen and phosphorus concentrations, contrary to the guiding paradigm that algal biomass in estuaries increases in proportion to nutrient inputs from their watersheds. Coincidental changes included sharp declines in the abundance of bivalve mollusks, the key phytoplankton consumers in this estuary, and record high abundances of several bivalve predators: Bay shrimp, English sole, and Dungeness crab. The phytoplankton increase is consistent with a trophic cascade resulting from heightened predation on bivalves and suppression of their filtration control on phytoplankton growth. These community changes in San Francisco Bay across three trophic levels followed a state change in the California Current System characterized by increased upwelling intensity, amplified primary production, and strengthened southerly flows. These diagnostic features of the East Pacific "cold phase" lead to strong recruitment and immigration of juvenile flatfish and crustaceans into estuaries where they feed and develop. This study, built from three decades of observation, reveals a previously unrecognized mechanism of ocean-estuary connectivity. Interdecadal oceanic regime changes can propagate into estuaries, altering their community structure and efficiency of transforming land-derived nutrients into algal biomass.

Water-quality data from Upper Klamath and Agency Lakes, Oregon, 2009-10

USGS Publications Warehouse

Eldridge, D. Blake; Caldwell Eldridge, Sara L.; Schenk, Liam N.; Tanner, Dwight Q.; Wood, Tamara M.

2012-01-01

The U.S. Geological Survey Upper Klamath Lake water-quality monitoring program collected data from multiparameter continuous water-quality monitors, weekly water-quality samples, and meteorological stations during 2009 and 2010 from May through November each year. The results of these measurements and sample analyses, as well as quality-control data for the water-quality samples, are presented in this report for 14 sites on Upper Klamath Lake and 2 sites on Agency Lake. These 2 years of data demonstrate a contrast in the seasonal bloom of the dominant cyanobacterium, Aphanizomenon flos-aquae, that can be related to differences in the measured water quality and meteorological variables. Some of the significant findings from 2009 and 2010 are listed below. * Both 2009 and 2010 were characterized by two cyanobacteria blooms, but the blooms differed in timing and intensity. The first bloom in 2009 peaked in late June and at higher chlorophyll a concentrations at most sites than the first bloom in 2010, which peaked in mid-July. A major decline in the first 2009 bloom occurred in late July and was followed by a second bloom that peaked at most sites in mid-August and persisted through September. The decline of the weaker first bloom in 2010 occurred in early August and was followed by a more substantial second bloom that peaked between late August and early September at most sites. * Dissolved oxygen minima associated with bloom declines occurred approximately 2 weeks earlier in 2009 (mid-July) than in 2010 (early August). pH maxima associated with rapid bloom growth occurred in late June and again in mid-August in 2009 and in mid-July and late August in 2010. * In both years, the maxima for total phosphorus and total nitrogen concentrations coincided with the chlorophyll a maximum. The maxima for dissolved nutrient concentrations (orthophosphate, ammonia, and nitrite plus nitrate) coincided with the declines of the first blooms. * Total particulate carbon, total particulate nitrogen, and total particulate phosphorus concentrations were measured in 2009 only. The ratios of carbon to phosphorus and nitrogen to phosphorus in particulates were the highest of the entire season during the rapid growth phase of the first bloom and were the lowest of the season during the decline of the first bloom. These ratios increased with the onset of the second bloom in that year, but to a lesser degree. * Meteorological data show that 2009 was warmer (particularly in June and July), less windy, and more humid early in the season than 2010. The difference in water temperatures reflected the difference in air temperatures in that the lakes were warmer in 2009 than in 2010 starting in early May, when the sensors were deployed, through most of June. Water temperature peaked at a higher value in 2009, and there were more clear days in June 2009 than in June 2010.