1-Centre for Environmental and Marine Studies (CESAM) and Department of Biology, 3University of Aveiro, Portugal 4
2-Environmental Group, Institute of Aquaculture, University of Stirling, United Kingdom 5Heavy metals accumulated by aquatic crustaceans in environmental studies are 7 normally investigated using the whole body burden, with little regard paid to uptake in 8 different tissues, to potential gender of life stage differences, or to the influence of 9 nutrition on the test organism. This is likely to give erroneous conclusions for a dose-10 response relationship within the toxicity test and potentially lead to wrong conclusions 11 for the ecological risks of metals where species may have higher sensitivities with 12 gender and life stage than indicated or that functionally metals may be sequestered 13 into parts of the body so are not bioavailable. This could lead to under-estimation or 14 over-estimation of the toxicity of metals, respectively, inaccuracy of metal budget 15 calculations and evaluation of trophic transfers of metals. This study evaluated the 16 influences of life stage, gender, and a priori nutritional state in the uptake of the 17 metals Zinc (an essential micro-nutrient; Zn) and Cadmium (a non-essential element; 18 Cd) in the amphipod Echinogammarus marinus. The study showed that life stage, and 19 nutritional stage did significantly influence the uptake and bioaccumulation for both 20 * Corresponding Author. Rua dos Santos Mártires, 8, Apartamento 32, 3810-171 Aveiro, Portugal. Fax: +351 234 372 587; e-mail: rpastorinho@ua.pt metals, but only Cd showed differential uptake and bioaccumulation with gender. In 21 addition, it was concluded that there was a significant uptake and accumulation of 22 both metals within the exoskeleton of the amphipods, which though adding to the full 23 body burden would add little to toxicity through lack of bioavailability. These results 24showed that care should be taken when interpreting results from tests normally 25 preformed on such test organisms. 26 27