Comparison of Mercury Concentrations in Fishes and Shellfishes from Matagorda Bay and San Antonio Bay, Texas




McInerney, Liam

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Mercury (Hg) is a toxic nonessential trace element that bioaccumulates in marine organisms and biomagnifies in marine food webs. Mercury exposure to humans is predominantly in the form of methylmercury (MeHg) in seafood and chronic exposure can result in deleterious health effects. Matagorda Bay and San Antonio Bay have several important commercial and recreational fisheries, yet little is known about the Hg concentrations in fish and shellfish in these two bays. This study investigated the variability in Hg concentrations among species within each bay and for each species, how Hg concentrations varied between the two bays; the relationship between Hg concentration and body length for each species in both bays; for fish, determined the percentage of each species that exceeded the adverse biological effects threshold level (0.5 µg/g wet weight); and determined the percentage of each fish and shellfish species that exceed state and federal Hg advisory levels. The Hg concentration in seven fish species [red drum (Sciaenops ocellatus), black drum (Pogonias cromis), spotted seatrout (Cynoscion nebulosus), southern flounder (Paralichthys lethostigma), hardhead catfish (Ariopsis felis), striped mullet (Mugil cephalus) and Atlantic croaker (Micropogonias undulatus)] and three shellfish species [eastern oyster (Crassostrea virginica), blue crab (Callinectes sapidus), and white shrimp (Litopenaeus setiferus) collected close to Matagorda in Matagorda Bay and Seadrift in San Antonio Bay was measured using a Direct Mercury Analyzer (DMA-80). Mercury concentrations varied among species in both bays. Hardhead catfish had the greatest mean Hg concentration in both bays, whereas striped mullet had the lowest. There was a positive relationship between Hg concentration and body length in six species from Matagorda (red drum, spotted seatrout, southern flounder, Atlantic croaker, hardhead catfish, and white shrimp) and six species from Seadrift (black drum, spotted seatrout, Atlantic croaker, hardhead catfish, and white shrimp). Hardhead catfish and black drum had individuals exceeding the adverse biological effect threshold level and Hg advisory levels for human consumption. Results from this study indicate that apart from black drum above the maximum landing size and hardhead catfish, fish and shellfish from both bays are low in Hg making them a good seafood choice to reduce dietary exposure to Hg through seafood consumption.



mercury, Texas


McInerney, L. (2023). Comparison of mercury concentrations in fishes and shellfishes from Matagorda Bay and San Antonio Bay, Texas (Unpublished thesis). Texas State University, San Marcos, Texas.


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