Uptake, accumulation and excretion by Corophium volutator (Crustacea: Amphipoda) of zinc, cadmium and cobalt added to sewage sludge

Zinc, cadmium and cobalt associated with digested sewage sludge are available to the benthic deposit-feeding amphipod Corophium volutator (Pallas). Accumulation by the amphipod of radioactively labelled metals adsorbed onto a 5% sludge-sediment mixture increased with time of exposure up to 15 days, but irregularly so as pulses of labelled metal were excreted into faecal pellets. The three labelled metals were accumulated and excreted apparently almost synchronously by individual amphipods, although great variability between different individuals was found. This intraspecific variability could not be attributed to differences between male and female amphipods. Net accumulation of labelled metals from the sludge increased with increased labelled metal concentration in the sludge, but not with time beyond an initial period of 15-30 days. It is proposed that the metal excretion patterns might reflect the breakdown of epithelial cells of the ventral caeca following a cell cycle, releasing accumulated stores of detoxified metals into the gut lumen and out of the body through faeces. (C) 1998 Academic Press.