Evaluation of Different Phytoplankton for Supporting Development of Zebra Mussel Larvae ( Dreissena polymorpha): The Importance of Size and Polyunsaturated Fatty Acid Content

Abstract

A marine alga and variety of freshwater algae of known polyunsaturated fatty acid (PUFA) composition were evaluated in the laboratory for their ability to promote development of Dreissena polymorpha from egg through settling and metamorphosis. The three species of algae which promoted development—the marine and the freshwater strain of Chlorella minutissima and the cryptophyte Rhodomonas minuta—were all rich in long-chain (≥ 18 C) n-3 PUFAs, including some 20:5 or 22:6 PUFAs. Dreissena's need for long-chain n-3 PUFAs is consistent with the needs of marine bivalves and freshwater zooplankton. Larval growth rate on the freshwater strain of C. minutissima was about the same as that for R. minuta, but much faster than that for the marine strain of C. minutissima. Mean ages at settling for larvae fed the freshwater C. minutissima were 15 d at 26°C, 17 d at 24°C, and 22 d at 22° C Low survival rates reported for the larvae in nature may be related to low concentrations of long-chain n-3 PUFAs in blue-green and some green algae that dominate eutrophic lakes in summer.