Transfer of metal detoxification along marine food chains

Abstract

It has been observed previously that the digestive gland of the carnivorous gastropod mollusc, Murex trunculus, does not accumulate metals which occur in high concentration in the digestive gland of its prey, the detritus-feeding gastropod, Cerithium vulgatum. It is proposed that mechanisms of metal detoxification which operate in C. vulgatum render metals biologically unavailable to M. trunculus. In the present work, this scheme is tested by feeding tissues containing detoxified metals from a gastropod, bivalve and barnacle to carnivorous gastropods. Metals in the prey are accumulated in insoluble granules in the digestive gland of the gastropod, kidney of the bivalve and gut connective tissue of the barnacle. These tissues are fed to the carnivores and the granules pass through the entire length of the gut. They are egested as clean preparations within the faecal pellets and they still contain the metals introduced by the tissues of the prey. This transfer of detoxification between species indicates that the food chain progression of material can result in the reduction of the bioavailability of metals. The observations are recorded by scanning electron microscopy and X-ray microanalysis.