Metal Accumulation From Dietary Exposure in the Sea Urchin, Strongylocentrotus droebachiensis

Metal contamination is a common problem in aquatic environments and may result in metal bioaccumulation and toxicity in aquatic biota. Recent studies have reported the significance of dietary metal accumulation in aquatic food chains, particularly in species of lower trophic levels. This research investigated the accumulation and effects of dietary metals in a macroinvertebrate. The seaweed species Ulva lactuca and Enteromorpha prolifera were concurrently exposed to five metals (copper, nickel, lead, cadmium, and zinc) and then individually fed to the green sea urchin Strongylocentrotus droebachiensis for a period of 2 weeks. Body mass, test length, total length, and coelomic fluid ion concentration and osmolality were measured. The sea urchins were also dissected and their organs (esophagus, stomach, intestine, gonads, and rectum) digested and analyzed for metals. The results demonstrated that metal accumulation and distribution varied between seaweed species and among metals. In general, there were greater concentrations of metals within the sea urchins fed E. prolifera compared with those fed U. lactuca. All of the metals accumulated within at least one organ of S. droebachiensis, with Cu being most significant. These results indicate that E. prolifera may accumulate metals in a more bioavailable form than within U. lactuca, which could impact the grazer. In this study, no significant differences in body length, growth, or coelomic fluid ion concentration and osmolality were detected between the control and metal-exposed sea urchins after the 2-week testing period. This research presents new data concerning metal accumulation in a marine herbivore after dietary metal exposure.