Water Resources Research Act Program

Details for Project ID 2020VT249B

Cyanobacteria bloom impacts on fish: ecological and human health considerations

Institute: Vermont
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $10,000 Total Non-Federal Funds: $20,021

Principal Investigators: Jason Stockwell

Abstract: Cyanobacteria cause major problems for freshwater resources both locally and globally. Toxins produced by cyanobacteria (cyanotoxins) remain a primary focus for research and management due to the potential to cause harm to wildlife, pets, and humans. People can be exposed to cyanotoxins directly by drinking water, swimming/recreation, and inhalation, and indirectly through contaminated food. Though cyanobacteria have been around for ~3.5 billion years, scientists have only recently recognized the pervasive impacts that they may have on aquatic ecosystems and people. Limited knowledge exists on how cyanobacteria influence aquatic food webs and negative effects may not be limited to toxins. For instance, we rely on fish as a main dietary source of essential fatty acids (EFA), such as omega-3 and omega-6 fatty acids. However, cyanobacteria are poor producers of these lipid constituents. When the base of the food web primarily comprises cyanobacteria, as is often the case in eutrophic lakes, the results on the transfer of desired (EFA) and undesired (toxins) substances through the food web, and their effects on the health of higher organisms, are not well known. We propose to investigate understudied impacts of cyanobacteria blooms on fish communities by (A) determining the extent to which toxin concentrations in fish are species-dependent, (B) studying how changes in the tissue (muscle, liver) composition of fatty acids are correlated to cyanobacteria (as measured by abundance and biovolume), and (C) examining fatty acids in muscle phospholipid of the fish community in a hypereutrophic lake to determine if EFA deficiency is present. We hypothesize that: (1) toxin concentrations will be highest in omnivorous fish and lowest in carnivorous fish; (2a) the proportion of long chain-essential fatty acids (LC-EFA) in fish will decline as cyanobacteria increase; (2b) planktivorous fish will have lower proportions of total LC-EFA compared to carnivorous fish; and (3) EFA deficiency, if present, will be greatest in planktivorous fish, followed by omnivorous fish and lowest in carnivorous fish. To address our hypotheses, we will examine fish species collected from Shelburne Pond, a hypereutrophic lake with recurrent (toxic) cyanobacteria blooms, located in Shelburne, VT. Representative samples of the fish community in Shelburne Pond were collected on the 15th of August 2019, during the2peak of the cyanobacteria bloom season, to address hypotheses 1 and 3. Two species of fish, yellow perch (Perca flavescens) and golden shiners (Notemigonus crysoleucas), differing in trophic level (carnivorous vs. planktivorous, respectively) were collected monthly in May-October in 2016-2017 and will be used to address hypothesis 2. Water samples for toxins and phytoplankton community composition were collected weekly in 2016-2017 and once in 2019 during the fish community collection. Our proposed project will provide greater insight into how cyanobacteria blooms may impact fish communities in Vermont and will enable us to assess how fish from eutrophic lakes may affect human health. While the issues of cyanobacteria blooms in Vermont and world-wide are a primary concern for drinking water systems and recreational users, the long-term effects of cyanobacteria abundance in freshwater systems are virtually unknown. Due to the difficulty of predicting and preventing blooms, preparing for continued and emerging impacts from cyanobacteria will likely remain a priority for society due to the never-ending need for clean, freshwater for drinking water production, food production, hygiene, and recreation.