Ishikawa Prefectural University
The lipids and fatty acids of two coastal clams, Meretrix lamarckii and Ruditapes
philippinarum, and a seep clam, Mesolinga soliditesta, were examined to assess their lipid physiology and trophic relationship with their diets. The major polyunsaturated fatty acids (PUFAs) in the Mer. lamarckii and R. philippinarum lipids consisted of various n-3 and n-6 long-chain (LC) PUFAs, while those in Mes. soliditesta muscle and viscera included various n-4 family PUFAs with limited kinds of n-3 and n-6 PUFAs. These _ndings indicate that, like other common shallow-water clams ingest phytoplanktonic n-3 and n-6 LC-PUFAs, whereas Mes. soliditesta utilizes limited kinds of n-3 and n-6 LC-PUFAs. In contrast to the other two bivalves species, Mes. soliditesta yielded various n-4 and n-7 PUFAs, which were assimilated from the chemosynthetic symbionts. The high diversity of PUFAs contained in the Mes. soliditesta lipids suggests that this species mixotrophically utilized both photo-synthetic products and vent chemosynthetic nutrition derived from geothermal energy.
keywords:deep sea,bivalve,chemosynthetic bacteria,symbiose