Rates of sediment sulphide oxidation by the bivalve mollusc Thyasira sarsi

Abstract

Several bivalve molluscs, including species of Thyasira (family Thyasiridae), use symbiotic sulphur-oxidising bacteria to exploit sulphides in reducing sediments are able to oxidise the insoluble sulphides as well as dissolved sulphide. The behaviour of these bivalves was observed in narrow glass vessels. Rates of sulphide oxidation by Thyasira sarsi (Philippi) were determined in a mesocosm, using specimens and sediment from Oslofjord. The rate of oxidation of reduced sulphur attributable to T. sarsi, 8.7 mmol d -1 m -2 , was close to the rate of sulphide formation in the same sediment, 8.2 mmol d -1 m -2 . This suggests that sulphate reduction rates control density in T. sarsi populations. The activities of T. sarsi and other lucinaceans can re-oxidise reducing and polluted sediments, allowing colonisation by sulphide-intolerant benthic animals.