Domoic Acid Kinetics and Trophic Transfer in Shellfish: An Integrated Laboratory and Estuarine Mesocosm StudyEPA Grant Number: R831703
Title: Domoic Acid Kinetics and Trophic Transfer in Shellfish: An Integrated Laboratory and Estuarine Mesocosm Study
Investigators: Schultz, Irvin R. , Skillman, Ann D. , Woodruff, Dana
Institution: Battelle Memorial Institute, Pacific Northwest Division
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 2005 through December 31, 2007 (Extended to December 31, 2008)
Project Amount: $449,735
RFA: Ecology and Oceanography of Harmful Algal Blooms (2004) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecosystems , Water
We hypothesize that physiologically based pharmacokinetic models mathematically analogous to the type developed in vertebrates can be adapted for marine invertebrates based on the known physiology of decapod crustaceans and bivalve mollusks. These models will be used to predict the uptake and disposition of the marine algal toxin domoic acid in Dungeness crabs (Cancer magister), Pacific razor clams (Siliqua patula) and blue mussels (Mytilus edulis). Validation of individual kinetic model predictions and trophic transfer of domoic acid will be achieved through a combination of focused laboratory experiments and the use of large-scale estuarine mesocosms containing razor clams and Dungeness crabs.
We have successfully applied recent improvements in analytical detection of domoic acid to study the excretion of the toxin in shellfish after intravascular injection and repetitive hemolymph removal. This technique will be used in conjunction with controlled laboratory feeding studies to develop a detailed data set on the uptake, tissue distribution and elimination of domoic acid in shellfish. Physiologically based kinetic models will be developed and specifically parameterized for crabs and bivalves using a combination of recently published and experimentally determined values for the cardiovascular and gastrointestinal / digestive systems of shellfish. Validation of model predictions will initially be performed from indoor laboratory studies and then from the results of a large scale estuarine mesocosm containing razor clams and crabs. In the mesocosm study, 500 clams verified to contain domoic acid will be collected from contaminated Washington State coastal sites. The clams will be added to the mesocosm along with adult Dungeness crabs (previously unexposed to domoic acid), which will feed on the clams. Individual clams and crabs will be repetitively monitored for hemolymph concentrations during the study. Crabs will also be intravascularly injected with 15N-labeled domoic acid to allow simultaneous determination of elimination and uptake of domoic acid.
The validated models of domoic acid kinetics in shellfish will provide researchers and risk assessors a useful tool for exploration of mechanisms controlling selective retention of domoic acid by certain shellfish and allow more accurate predictions of depuration times to below permissible limits. When used in conjunction with forecasting models of Pseudo-Nitzschia blooms, the predicted levels of domoic acid in shellfish can be better estimated along with the potential economic consequences of recreational and commercial shellfish closures.