Observations on the interaction of zinc and cadmium uptake rates in crustaceans (amphipods and crabs) from coastal sites in UK and France differentially enriched with trace metals

This paper presents results on the possible interaction of zinc and cadmium uptake rates in crustaceans. Zn and Cd uptake rates were measured in amphi pods (Orchestia gammarellus) and crabs (Carcinus maenas and Pachygrapsus ma rmoratus) from five coastal sites in Britain and France subjected to differ ent degrees of trace metal enrichment. The presence or absence of 100 mu g l(-1) of one metal (1.53 mu M l(-1) Zn, 0.89 mu M l(-1) Cd) had an inconsis tent effect on the rate of uptake of the other metal by O. gammarellus. The presence or absence of 50 mu g l(-1) of either zinc (0.76 mu M l(-1)) or c admium (0.45 mu M l(-1)) had no effect on the rate of uptake of the other m etal by C. maenas (from Millport, Scotland). Zinc and cadmium uptake rates were correlated in individual amphipods and crabs of both species from the five sites. These correlations indicate that zinc and cadmium might share c ommon routes of uptake from solution by crustaceans, but the metals do not consistently interact competitively or synergistically at the exposure conc entrations investigated. Regression coefficients of the relationship betwee n zinc and cadmium uptake rates in amphipods and crabs showed occasional. b ut inconsistent, differences between sites and over time. All three crustac eans take up zinc from solution at a higher rate than cadmium for the same total dissolved metal molar concentration, but at a lower rate than cadmium per free metal ion molar concentration. (C) 2000 Elsevier Science B.V. All rights reserved.