Assimilation of carbon from a rotifer by the mussels Mytilus edulis and Perna viridis: a potential food-web link

Abstract

We tested the hypothesis that mesozooplankton is a potential food source for 2 marine mussels; the temperate blue mussel Mytilus edulis and the tropical and subtropical green mussel Perna viridis. We fed the rotifer Brachionus plicatilis to each mussel species at 3 rotifer densities (0.1, 0.5, and 1.0 ind. ml -1 ) and found that each mussel species could significantly reduce the abundance of rotifers. We also labeled rotifers by feeding them 14 C-labeled phytoplankton. The labeled rotifers were fed to mussels at densities of 0.1, 0.2, 0.5, and 1.0 individuals ml -1 , and the assimilation effi- ciencies were generally higher at higher rotifer densities (59 to 73% for M. edulis and 37 to 73% for P. viridis). After standardization for mass and metabolic requirements, we calculated that rotifers make significant contributions to the mussels' energy budgets, which provides quantitative evidence for a potential trophic link between mesozooplankton and marine benthic bivalves. This study demonstrates that mesozooplankton could have an important role in the transformation of energy between benthic and pelagic systems in coastal areas. Dense populations of bivalves could exert a strong top-down effect on planktonic food webs.