Early Signs & Determinants of Biotoxins (Microcystins) in LakesEPA Grant Number: R827407
Title: Early Signs & Determinants of Biotoxins (Microcystins) in Lakes
Investigators: Sasner, John J. , Haney, James F. , Ikawa, Miyoshi
Institution: University of New Hampshire - Main Campus
EPA Project Officer: Hiscock, Michael
Project Period: August 16, 1999 through August 15, 2000 (Extended to February 15, 2001)
Project Amount: $149,941
RFA: Futures: Detecting the Early Signals (1999) RFA Text | Recipients Lists
Research Category: Water , Sustainability , Land and Waste Management , Ecosystems , Ecological Indicators/Assessment/Restoration
Toxic cyanobacteria (aka blue-green algae) of the genus microcystis produce potent liver toxins called microcystins that impact the water use by animals, including humans. Blooms of Microcystis are increasing in frequency and intensity on a worldwide basis. Preliminary evidence indicates that problems of toxic Microcystis may also exist in relatively clean lakes with low nutrient concentrations. The life history of Microcystis includes an overwintering phase of cells or colonies in bottom sediments followed by a rise via gas vacuoles into the water column during the warmer summer months. Cyanobacteria may compete favorably, and dominate in non-eutrophic lakes by utilizing both benthic nutrients and deep light penetration that shallow eutrophic or transparent meso-oligotrophic lakes may provide.
The proposal aims to test the hypothesis that the benthic community can be seeded to detect early signs of Microcystis and the presence of microcystin toxins. To test this hypothesis, the study will examine 25 lakes representing a range of morphometric and trophic conditions. In each lake we will examine the epibenthic populations and toxicity of cyanobacteria as indicators of the "seed" for summer plankton populations. Benthic and planktonic populations will be examined during the spring and late summer. Measurements will also be taken of the underwater light, nutrients (N, Total N, nitrate, and total P) and physical/chemical conditions (temperature, turbidity, specific conductance, pH, redox potential and dissolved oxygen) of the water column as well as in the surface sediments (incl. organic content). Microcystin concentrations will be determined using a new sensitive ELISA method.
Information from this study will be used to characterize lakes according to their potential to form blooms of toxigenic Microcystis based on their nutrient concentrations in the lake water and sediments, as well as water transparency and their basin morphometry. The results of our study and the existing statewide database will allow for a preliminary assessment of the environmental risk of microcystin toxin in New Hampshire lakes and identify lakes with the greatest and least likelihood of having microcystin toxin problems. Another goal of our study is to develop methodology in the laboratory and in the field (e.g., epibenthic sampling) that could eventually be incorporated into lake water quality monitoring programs.
Improvement in Risk Assessment: If successful, this study will provide information on the factors regulating cyanobacteria toxins in nature. The research could also benefit the water supply industry and regulatory agencies. If trophic status and the appearance of blue-green algal surface scums are not the only indicators of cyanobacteria toxins in lakes, then we will have shown that an additional approach to monitoring programs is urgently needed. This would impact federal and state agencies involved in assessing and regulating water quality for drinking and recreational purposes. Also regional monitoring programs, such as EPA's EMAP, should find our results useful in predicting the extent of potential problems with biotoxins.