Comparative accumulation of cobalt by three crustaceans: a decapod, an amphipod and a barnacle

Abstract

This study investigates the comparative accumulation of the essential heavy metal cobalt from solution under standardised physico-chemical conditions by three different littoral crustaceans - the caridean decapod Palaemon elegans Rathke (Malacostraca: Eucarida: Decapoda), the amphipod Echinogammarus pirloti (Sexton and Spooner) (Malacostraca: Peracarida: Amphipoda) and the barnacle Elminius modestus Darwin (Cirripedia: Thoracica). All three crustaceans showed linear net accumulation of cobalt from solution over a wide range of dissolved radioactively labelled Co concentrations, with no significant excretion of accumulated Co during the time period of the experiments. Thus in all three species the newly accumulated labelled Co concentration was equivalent to the increase in concentration of total body Co. The apparent ability of decapod crustaceans to regulate the body concentrations of the essential metals copper and zinc is therefore not extended to all essential trace metals. There are interspecific differences in rates of Co uptake, being lowest in the decapod and similar in the amphipod and barnacle. Calculations of a molar index of metal uptake show that cobalt is taken up at a lower rate than cadmium which in turn is taken up more slowly than zinc in all three crustaceans.