ICP-MS Analysis of Round Goby (Neogobius melanostomus) Otoliths and Sediments from Four Sites in Erie County, PA

Abstract:

The round goby (Neogobius melanostomus) is a non-native fish that has received much attention.  Otoliths (calcified structures of the inner ear) accumulate metals that fish are exposed to in their environment and tend to retain those elements once they are deposited.  Sediment studies on Presque Isle Bay (PIB) have identified metals that exceed sediment quality guidelines. Barium (Ba) is of particular interest because it behaves chemically like calcium and is readily incorporated into otoliths.  Recent work in our lab revealed relatively high concentrations of Ba in the otoliths of round gobies, compared to two other species.  We attribute this difference to the bottom-dwelling goby accumulating Ba through absorption and diet.  This study is designed to better understand how Ba and other metals accumulate in gobies by assessing metal concentrations in goby otoliths and sediments. We hypothesize that concentrations of Ba and other metals in otoliths correlate with those in sediments. Gobies were collected in the summer of 2021 from four sites in Erie County: open water of PIB, South Pier of the shipping channel, Fairview Gravel Pit, and Lake LeBoeuf.  Otoliths were removed, rinsed, dried, and weighed prior to dissolving in nitric acid and diluting.  Elemental analysis of otoliths was done by ICP-MS at Penn State Behrend.  Concentrations of Barium and other alkaline earth metals (Ca and Mg) were compared across sites using one-way analysis of variance (ANOVA) and two-tail pairwise t-tests. We analyzed otoliths of 64 gobies. [Ba] was highly correlated in left and right otoliths as well as in replicate samples. Alkaline earth metals varied among gobies from the four sites.  On average, gobies from the Fairview Gravel Pit had significantly higher [Ba] and Ba:Ca values than gobies from the other three sites. Ongoing work involves quantifying metals in sediments.  Samples were collected from each of the four sites in the fall of 2021.  Sediments have been dried and sieved.  Those with a grain size smaller than 180 μm have been retained for further analysis.  Metal digestion following US EPA method SW846 3005A and ICP-MS analysis are being conducted.  Results will be presented, and we predict that alkaline earth metal concentrations in the sediments will correlate with those from the otoliths.