Role of filter-feeding in the nutritional biology of a deep-sea mussel with methanotrophic symbionts

The ability of an undescribed deep-sea hydrocarbon-seep mussel which contains endosymbiotic methanotrophic bacteria to clear, ingest, and assimilate radiolabeled bacteria (Vibrio pelagicus andEscherichia coli) and algae (Dunaliella tertiolecta) was compared with that of the bay musselMytilus edulis. The seep mussel, collected in August 1987 from the Louisana Slope in the Gulf of Mexico, was slower to clear bacteria and algae thanM. edulis. The ingestion and assimilation of filtered bacteria and algae was established from the presence of radiolabel in mussel tissues and feces. The seep mussel was somewhat less efficient in assimilating radiolabeled components from bacteria and algae thanM. edulis. The dietary carbon maintenance-requirement of the seep mussel could potentially be met at environmental concentrations of greater than 10⁶ bacteria ml^–1. At lower concentrations of particulate organic matter, filter-feeding could be an important source of nitrogen and essential nutrients not supplied by the endosymbionts.