Total Mercury Concentrations in Lakes and Fish of Western Maryland, USA

The purpose of this study was to quantify total mercury concentrations in three species of fish in three lakes of western Maryland: Piney Creek reservoir, Deep Creek Lake, and Lake Habeeb. We measured total mercury concentrations in water from each lake and muscle tissue from 119 fish collected in fall 2000: 15 largemouth bass (Micropterus salmoides), 15 yellow perch (Perca flavescens), and 15 bluegill (Lepomis macrochirus) from the Piney Creek reservoir; 15 largemouth bass, 15 yellow perch, and 14 bluegill from Deep Creek Lake; and 15 largemouth bass and 15 bluegill from Lake Habeeb. Average total mercury concentrations (± SD) in surface waters were 0.96 ± 0.03 ng L−1 for the Piney Creek reservoir, 0.56 ± 0.07 ng L−1 for Deep Creek Lake, and 0.40 ± 0.05 ng L−1 for Lake Habeeb. These water quality differences were sometimes reflected in the total mercury concentration in fish muscle tissue. Total mercury concentrations in bluegill (0.05 ± 0.02 μg g−1) and largemouth bass (0.10 ± 0.03 μg g−1) from Lake Habeeb were significantly (p < 0.001) lower than the total mercury concentrations in bluegill and largemouth bass from the Piney Creek reservoir (bluegill: 0.13 ± 0.04 μg g−1 and largemouth bass: 0.37 ± 0.18 μg g−1) and Deep Creek Lake (bluegill: 0.11 ± 0.04 μg g−1 and largemouth bass: 0.30 ± 0.09 μg g−1). Yellow perch from the Piney Creek reservoir had significantly higher total mercury concentrations than yellow perch from Deep Creek Lake (0.20 ± 0.08 μg g−1 versus 0.13 ± 0.04 μg g−1). In contrast, total mercury concentrations in largemouth bass from the Piney Creek reservoir and Deep Creek Lake were not significantly different. With the exception of largemouth bass from Lake Habeeb and yellow perch from Deep Creek Lake, there were relatively strong (r2 > 0.39–0.79) log-log relationships between the size (weight and length) of the fish and total mercury concentrations in muscle tissue. The largest largemouth bass (> 800 g and > 38 cm) from both Deep Creek Lake and the Piney Creek reservoir had total mercury concentrations that exceeded the consumption advisory of 0.5 μg g−1 that is used by many states and Canada. In contrast, total mercury concentrations in largemouth bass from Lake Habeeb did not exceed this consumption advisory. Our results suggest that fish consumption advisories are needed for largemouth bass in the Piney Creek reservoir and Deep Creek Lake.