Abstract:
At elevated concentrations, marine organisms may accumulate metals, which can
potentially cause toxicity. Metal accumulation and toxicity in aquatic organisms has
focused largely on waterborne metal exposure and less research has focused on dietary
metal exposure. In addition to dietary metal exposure, an important emerging class of
contaminants within marine ecosystems is nanoparticles (NPs). This research investigated
the accumulation and effects of dietary metals and NPs in marine invertebrates. Two
seaweed species, Ulva lactuca and Agardhiella subulata, were each concurrently exposed to five metals (Cu, Ni, Pb, Cd, and Zn), and U. lactuca was also exposed to the metal mixture as well as each metal individually for 48 h. The seaweeds were then used as food for the sea hare, Aplysia californica. Body mass of A. californica was measured and metal concentration was quantified in dissected organs. Metal accumulation in the
organs of A. californica varied with different metal species. A. californica demonstrated
significantly reduced body weight by the end of the exposure periods, as compared to
controls. In addition, the diatom, Thalassiosira weissflogii was exposed to ZnO NPs for 7
d and growth, zinc accumulation, and zinc distribution was measured within the algal
cells. The ZnO-exposed diatoms were fed to the copepod, A. tonsa for 7 d and
reproduction and survival were quantified. Zinc accumulation in the algae occurred
dose-dependently over time. Feeding on ZnO-exposed diatoms led to a decrease in
copepod survival and reproduction. These results highlight the significance of dietary
metal exposure in lower trophic levels and support the use of A. californica as a sensitive
bioindicator species of metal pollution in marine systems as well as provide evidence of
trophic transfer of metal contaminants associated with metal oxide NPs within a marine plankton community leading to the reduction in individual demographic performance of
an important coastal marine grazer.