The effects of Water Temperature on Oyster Feeding Rates
Domoic acid (DA) is a neurotoxin produced by certain diatom species that are a source of food for filter-feeding mollusks. Although DA does not harm mollusks, it can cause Amnesic Shellfish Poisoning (ASP) in humans. In the spring of 2002, high concentrations of a cold-water diatom, Pseudo-nitzschia seriata, resulted in unacceptable levels of DA (greater than 20 µg DA/g) in mussels. This outbreak, distinctive as it occurred in spring instead of Autumn and was detected not only in PEI, but also in NB, Quebec and NS. The unexpected results were the basis for a widespread and lengthy harvest closure directed at most shellfish species, including the American oyster.
The generalized nature of the closure was questioned, given evidence that the update and depuration of biotoxins can differ markedly from one shellfish species to another. The objective of this project will test two hypothesis:
- Cultivated oysters and mussels begin feeding at a similar temperature in the spring;
- In oysters exposed to low temperatures, feeding rates (as defined by the amount of organic matter absorbed by 1.0 g of tissue over a 24h period) is uncorrelated to animal size.
The results may provide a scientific basis for developing the approach for managing shellfish closures by species in Atlantic Canada. This concept aims at optimizing both harvest opportunities and DA monitoring efforts.
2004 - 2006
Atlantic: Gulf of Maine, Scotian Shelf
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