BACTERIAL NUTRITION OF GREAT SCALLOP LARVAE

Bacterial nutrition of great scallop, Pecten maximus, larvae was inves tigated using the radioactive tracer technique. The bacterial labellin g was studied initially to obtain a high and stable specific radioacti vity (C-14) Of bacterial cells. A higher bacterial specific C-14 activ ity was obtained when the tracer (amino acid) was introduced in the cu lture medium at the beginning of the exponential growth phase. After a 12 h labelling period in a rich nutritive medium, the bacteria were d epurated in seawater for 5 h (chase) to prevent further C-14 excretion and then added to larval rearing vessels. The larval labelling was fo llowed for 12 h and then larvae were placed in new vessels without rad ioactive bacteria. The depuration of larvae was followed for 3 days. D ata obtained on ingestion and assimilation efficiency show that bivalv e larvae are able to ingest and digest bacteria.