One of the predicted consequences of global change will be the rise in frequency and duration of harmful algal blooms. In this study we looked at the effects of domoic acid, a toxin produced by the diatom Pseudo-nitzschia, on the growth and functioning of juvenile mussels (Mytilus edulis). A reduced growth could have an economic impact on shellfish industries. Exposing the mussels for 45 days to realistic concentrations of Pseudo-nitzschia mixed with a commercial shellfish diet in ratios of 27 and 85 %, did not lead to any detectable amounts of DA in the tissues, nor did it have an effect on the respiration, clearance or excretion rate. The major observation was that in the treatments with 85 % Pseudo-nitzschia almost solely pseudo-feces were produced, while in treatments with 27% of Pseudo-nitzschia there were almost no pseudo-feces. This suggest that mussels are actively rejecting Pseudo-nitzschia cells when they are present in high concentrations but not when there is a larger amount of other algae available as a food source. The same results were found for a non-toxic strain meaning that this selective behavior is independent of the concentration of domoic acid. While the production of pseudo-feces reduces the amount of domoic acid taken up by the mussels, it also creates a energetic trade off and could reduce the growth rate of the mussels during a bloom of these harmful algae. |
