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Extramural Research

The Impact of Nutrients, Zooplankton, and Temperature on Growth of, and Toxin Production by, Cyanobacteria Blooms in the Upper Reaches of Chesapeake Bay

EPA Grant Number: R833220
Title: The Impact of Nutrients, Zooplankton, and Temperature on Growth of, and Toxin Production by, Cyanobacteria Blooms in the Upper Reaches of Chesapeake Bay
Investigators: Gobler, Christopher
Current Investigators: Gobler, Christopher , Coyne, Kathryn J. , Dawson, Celia
Institution: SUNY at Stony Brook
Current Institution: SUNY at Stony Brook , Maryland Department of Natural Resources
EPA Project Officer: Sergeant, Anne
Project Period: March 28, 2007 through March 27, 2010
Project Amount: $449,947
RFA: Ecology and Oceanography of Harmful Algal Blooms (2006)
Research Category: Aquatic Ecosystems


The frequency and intensity of toxic cyanobacteria blooms has increased in recent decades, causing a plethora of acute, chronic and fatal illnesses in animals and humans. A clear understanding of factors promoting bloom growth and toxicity has remained elusive, partly because blooms are comprised of toxic and non-toxic strains of the same species which cannot be resolved microscopically. An additional confounding aspect of toxic cyanobacteria ecology is that the presence of toxic strains does not necessarily indicate toxins are being actively synthesized by a bloom. While research of toxic cyanobacteria blooms in the Great Lakes has intensified in recent years, blooms in the upper reaches of US estuaries have been largely ignored, despite the severity of these events. For example, recent blooms in the upper reaches of Chesapeake Bay have covered over 50 km and have had Microcystis cell densities (106 ml-1) and toxin levels (> 650 µg microcystin L-1) which exceed levels documented anywhere in the US. The objectives of this project are to elucidate the role of nutrients, zooplankton grazing, and climatic warming on the growth and toxicity of cyanobacteria blooms in the upper reaches of Chesapeake Bay. We will utilize quantitative polymerase chain reactions (QPCR) to establish the spatial and temporal dynamics of toxic and non-toxic strains of cyanobacteria and will use reverse transcriptase QPCR to quantify changes in microcystin synthetase gene expression. We will place the dynamics of these populations and gene expression in the context of physiochemical water column characteristics (e.g. nutrients, T), phytoplankton and zooplankton community structure, and cyanotoxin concentrations. We will conduct experiments to examine the individual and combined effects of nutrients and temperature on the growth of, and toxin production by, cyanobacteria. In addition, we will concurrently examine the ability of wild and cultured micro- and mesozooplankton to graze on toxic and non-toxic strains of cyanobacteria. Finally, we will determine the extent to which current models which forecast total Microcystis densities in the Potomac River can be used to predict densities of toxic Microcystis cells and cyanotoxins in this system. Thus, this project will provide managers with both an enhanced forecast of blooms in this system and information needed to formulate bloom management and prevention strategies. Our results will additionally determine how trophic interactions (zooplankton grazing) may be altered by toxic cyanobacteria blooms and how nutrient loading may affect such alterations.

Publications and Presentations:

Publications have been submitted on this project: View all 1 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

Microcystis, microcystin, cyanobacteria, harmful algae, toxicity, plankton, phytoplankton, estuarine research, bloom dynamics, environmental indicators, nutrients, zooplankton, climate change, toxics, ecology, blooms, toxins, PCR, toxic and non-toxic strains,, RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Oceanography, algal blooms, Environmental Monitoring, Ecology and Ecosystems, marine ecosystem, bloom dynamics, HAB ecology, water quality, algal bloom detection

Progress and Final Reports:
2007 Progress Report
2008 Progress Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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