A contribution to the knowledge of bivalve Corbula gibba (Olivi, 1792) behaviour, oxygen consumption and anaerobic metabolism

Background and Purpose: The bivalve Corbula gibber (Olivi,1792) (Corbulidae, Bivalvia) inhabits various benthic communities, including communities in some polluted areas. Therefore Corbula has been proclaimed as a species of wide ecological distribution and an indicator species of environmental instability Benthic moss mortality in the north ern Adriatic Sea in 1989 was caused by lack of oxygen near the bottom layer Corbula: and several oxygen resistant macrobenthic species survived. In this paper we considered the results of Corbula respiration and behaviour studies in order to better understand its survival mechanisms in extreme oxygen conditions. Material and Methods: At first the number of boreholes on Corbula. shells done by naticid gastropods was inspected. Then, burrowing behaviour was controlled in several laboratory experiments. Finally Corbula oxygen consumption was measured by "closed bottle" respirometer under normoxic and hypoxic conditions and lactate concentration accumulated in tissue after the certain period of anoxia. Results and Conclusion: The laboratory experiments showed that Corbula moved on the sediment surface before burrowing and that once burrowed individuals often changed their position in the sediment. It was also established that burrowing and moving processes depended on illumination (light/dark) and not on diurnal rhythm (day/ night) because movements and burrowing occured during the night time and also during the day time, but in the dark. In the laboratory anoxic conditions Corbula switched to anaerobic metabolism, by an increase in tissue lactate concentration. After their return to normoxic conditions Corbula increased oxygen consumption for certain period of time to break down the accumulated anaerobic metabolites.