Grantee Research Project Results
Physiological and Behavioral Effects of Nutrient Limitation on the Toxic Dinoflagellate Alexandrium tamarense
EPA Grant Number: U915038Title: Physiological and Behavioral Effects of Nutrient Limitation on the Toxic Dinoflagellate Alexandrium tamarense
Investigators: Poulton, Nicole J.
Institution: Woods Hole Oceanographic Institution
EPA Project Officer: Lee, Sonja
Project Period: January 1, 1996 through January 1, 1999
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Fellowship - Marine Biology , Academic Fellowships , Biology/Life Sciences
Objective:
The objective of this research project is to determine the major environmental and nutritional controls of the toxic dinoflagellate, Alexandrium tamarense, in the Gulf of Maine (Casco Bay). Specifically, the study will examine what are the environmental cues, nutritional and/or temporal, that regulate longevity and termination of naturally occurring populations.
Approach:
Objective 1. Method development to determine Alexandrium nutrient physiology: Alexandrium tamarense cultures will be established from the Casco Bay region along the Southern Maine coast by isolating live cysts from surface sediment samples. Using these isolates, mating types will be identified and crossed to identify two or more sexually compatible strains. Immunological methods for the detection and isolation of Alexandrium from laboratory and field samples will be evaluated on cultures and field populations. Objective 2. Identification and determination of physiological indicators of nutrient stress: Using thermally stratified laboratory water columns (mesocosms) and semi-continuous cultures, Alexandrium isolates from the Casco Bay region will be grown to characterize the effects of nutrition on physiological state, biochemical composition, and vertical migration behavior. A range of nutrient regimes will be used, and chemical composition will be assayed to identify "indicators" of nutrient limitation. Chemical analyses will include particulate C and N, carbohydrate, protein, and toxin composition. Complementary research will be conducted exploring the effects of different nutrient regimes on cell physiology when sexually compatible mating types are present using the mesocosms. Field studies also will also be conducted using these species-specific methods to discern what environmental factors control the development and decline of Alexandrium blooms in Casco Bay, Maine.