The clam (Chamelea gallina): evaluation of the effects of solids suspended in seawater on bivalve molluscs

Abstract

The study was designed to evaluate the effects of solids in suspension in seawater on clams (Chamelea gallina). The aim was to investigate the possible correlation between the widespread deaths of clams in the coastal waters of the central and northern Adriatic in the last five years and increased concentrations of solids in suspension. The research involved conducting 96-hour tests on clams farmed in aquariums containing filtered seawater. The tests were preceded by a 7-day adaptation stage to allow the molluscs to acclimatise. During this period, the clams were fed on unicellular seaweed (Dunaliella tertiolecta). The molluscs were exposed to particles of solids in suspension consisting of pools of silica gel (SiO2) granules of various sizes, similar to those constituting silt, whose presence and suspension in the sea considerably increase after heavy rain and heavy seas. The study established that the number of deaths caused by solids suspended in seawater at the concentrations used in the tests was not statistically significant.