AN INSTRUMENT FOR THE MONITORING AND COLLECTION OF THE VENTED BURROW FLUIDS OF BENTHIC INFAUNA IN SEDIMENT MICROCOSMS AND ITS APPLICATION TO THE POLYCHAETES HEDISTE-DIVERSICOLOR AND ARENICOLA-MARINA

A device is described which utilizes heated thermistors to detect the venting of irrigation fluids from infaunal burrow orifices in laboratory sediment microcosms. As well as facilitating the description of species-specific irrigation patterns, the device incorporates an adjustable trigger to operate a pump for sampling within the plume of vented fluids resulting from observable irrigation events. Details are given of the sampling of such fluids vented by two estuarine polychaetes, the ragworm Hediste diversicolor (O.F. Müller) (formerly Nereis diversicolor, see Howson, 1987) and the lugworm Arenicola marina (Linnaeus). Chemical analysis of these samples showed that concentrations of dissolved iron, manganese, copper and of phosphate and nitrite were higher than in control samples collected simultaneously from unburrowed sediment. This demonstrated the application of the device in monitoring fluxes of dissolved metal and nutrient species associated with benthic irrigation, and in identifying variations between components indicative of geochemical processes occurring within burrows. © 1990.