Zinc and Cadmium Transport by the Vertically Migrating Opossum Shrimp, <i>Mysis relicta</i>

Abstract

Mysis feeding on sediments ingested 2–4 times more zinc and 8 times more cadmium than mysids feeding on zooplankton. Mysids feeding on sediments egested 3–5 times more zinc and 5–7 times more cadmium than those feeding on zooplankton. Concentrations of zinc and cadmium were 5–24 times higher in the faecal pellets than in the food. There was little difference in the amount of zinc and cadmium transported upward or downward per mysid. However, 3–4 times more zinc and 4–7 times more cadmium were concentrated and recycled by Mysis at the sediments than in the water column. On a population basis, mysids transported 5 μg Zn and 0.008 μg Cd∙m −3 ∙night −1 into the water column and 9 μg Zn and 0.020 μg Cd∙m −2 ∙d −1 to the sediments. It was suggested that mysids and their particulate products (faecal pellets, exuviae) may play an important role in the transport and recycling of cadmium and zinc to other members of the food web.