Abstract
Two species of mussels from two Newfoundland estuaries were analyzed for carbon isotopic compositions of free fatty acids. Gas chromatography and mass spectrometry techniques were used to determine bulk and individual fatty acids. The bulk fatty acid distribution and carbon isotopic composition reveal marine phytoplankton as the dominant dietary source in mussels. Mechanisms of fatty acid incorporation and utilization in mussels are discussed. Such compound-specific isotope analyses illustrate the potential for detailed studies of carbon flow in benthic ecosystems.