You are here:
Mercury contamination and bioaccumulation trends in sunfish (Lepomis spp.) from southern Rhode Island
Citation:
Lotti, B., D. Taylor, M. Hedgespeth, AND M. Cantwell. Mercury contamination and bioaccumulation trends in sunfish (Lepomis spp.) from southern Rhode Island. 2022 RI Summer Undergraduate Research Symposium (RI-SURS), Kingston, RI, July 29, 2022.
Impact/Purpose:
Mercury is a widespread pollutant that poses a risk to human health, and exposure occurs by eating contaminated fish. This study examined the mercury content of three commonly eaten sunfish species, including the bluegill, redbreast, and pumpkinseed. Fish were collected from the Pawcatuck River and Kedniker Island Pond (Grills Preserve, Bradford, RI) in June 2022, and their filet tissue were measured for mercury content. The mercury content of sunfish did not differ among the three species, and all species had higher mercury levels at larger body sizes. The rate at which mercury accumulated in the filet tissue (i.e., bioaccumulation) did not differ between the bluegill and redbreast sunfish. The similar mercury content and bioaccumulation rates among sunfish is attributed to their comparable ecological roles in the environment, e.g., habitat use and diet. Finally, only 11% of the adult sunfish analyzed in this study had mercury concentrations above the U.S. EPA threshold level. Therefore, eating sunfish from the study area poses low mercury-related risk to human health.
Description:
Mercury (Hg) is a widespread environmental contaminant that may pose a risk to human health, with human exposure occurring mainly through fish consumption. This study examined Hg concentrations and bioaccumulation trends in commonly consumed freshwater sunfish, including the bluegill (Lepomis macrochirus), redbreast (L. auritus), and pumpkinseed (L. gibbosus). Sunfish were collected from the Pawcatuck River and Kedniker Island Pond (Grills Preserve, Bradford, RI) in June 2022 using an electrofisher and rod & reel. Dorsal muscle tissue was excised from each individual and measured for total Hg content (ppm dry weight) using atomic-absorption spectrometry, after which results were analyzed relative to fish species, body size (mm total length), and estimated age (years). Mean Hg concentrations did not differ among sunfish species (mean ± SD: Bluegill = 0.83 ± 0.37, n = 26; Redbreast = 0.92 ± 0.27, n = 11; Pumpkinseed = 0.88 ± 0.36, n = 9), and all sunfish experienced increased Hg levels at larger body sizes. Moreover, there was no significant difference in Hg bioaccumulation rates, i.e., Hg-age relationships, between bluegill and redbreast sunfish. The absence of inter-specific differences in sunfish Hg content and bioaccumulation rates is attributed to the similar life history characteristics and trophic ecology among species. From a human health perspective, 11% of the adult sunfish analyzed in this study had Hg concentrations exceeding the U.S. EPA threshold level of 1.36 ppm dry weight. Therefore, only very frequent consumption of sunfish from the study area (> 1 meal/week) are anticipated to pose a risk to human health regarding mercury.
