Biogeographical Comparison of Nutritional Effects of the Toxic Dinoflagellate Alexandrium Sp. on the Copepod Acartia HudsonicaEPA Grant Number: U915627
Title: Biogeographical Comparison of Nutritional Effects of the Toxic Dinoflagellate Alexandrium Sp. on the Copepod Acartia Hudsonica
Investigators: Colin, Sean P.
Institution: University of Connecticut
EPA Project Officer: Michaud, Jayne
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $80,084
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems
The objective of this research project is to examine the copepod-toxic dinoflagellate interaction in the framework of the latitudinal (and toxicity) gradient represented by the spreading of Alexandrium. It is hypothesized that there may be geographical differences in the effects of local strains of Alexandrium on physiological, population, and behavioral biology of individuals of local strains of dominant copepod species. The following questions will be addressed:
(1) Are the observed geographical differences in the biological processes of the copepods due to toxicity variations in the dinoflagellate strains, to differences among the populations within the copepod species, or to the interaction of the dinoflagellates and copepod strains?
(2) If differences are due to the copepods, are they due to genetic adaptation or physiological acclimation?
To test the hypothesis, the investigator will employ strains of Alexandrium and copepods collected from locations in Canada, Maine, Massachusetts, and Connecticut, and copepods collected additionally from southern New Jersey (location where Alexandrium blooms have not occurred). Copepods from the different sites will be exposed to dinoflagellates from one site, and vice versa. In all the copepod-dinoflagellate combinations, rates of copepod cell ingestion, egg production, egg hatching, individual survival, and behavior will be measured, and differences among combinations will be statistically analyzed. Physiological acclimation by copepods will be examined by comparing copepod rate processes through length of time of exposure to the dinoflagellates. The ability of copepods to adapt to an exposure to toxic Alexandrium will be analyzed using laboratory selection experiments.
Experiments to date have shown that the northern copepod populations (isolated from Canada, Maine, and Massachusetts) exhibit higher ingestion and egg production rates than the southern copepod populations (isolated from Connecticut and New Jersey) when given different concentrations of a toxic Alexandrium strain. No such pattern was observed among the copepod populations when they were given different concentrations of a nontoxic algal food. Through further experimentation, the investigator hopes to demonstrate whether the basis of these differences are due to copepods adapting to the toxins or to an ability to acclimate to the toxins. Additionally, the investigator will examine if the behavioral effects of the toxic dinoflagellate on the different copepod populations exhibit a similar pattern.