SREL Reprint #3419

Relationships of mercury concentrations across tissue types, muscle regions and fins for two shark species

Jason R. O'Bryhim1,2, Douglas H. Adams3, Julia L.Y. Spaet4,5, Gary Mills1, and Stacey L. Lance1

1Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, United States
2Department of Environmental Science and Policy, George Mason University,
Fairfax, VA 22030, United States
3Florida Fish & Wildlife Conservation Commission, Fish & Wildlife Research Institute,
Melbourne, FL 32901, United States
4Red Sea Research Center, Division of Biological and Environmental Science and Engineering,
King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
5Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK

Abstract: Mercury (Hg) exposure poses a threat to both fish and human health. Sharks are known to bioaccumulate Hg, however, little is known regarding how Hg is distributed between different tissue groups (e.g. muscle regions, organs). Here we evaluated total mercury (THg) concentrations from eight muscle regions, four fins (first dorsal, left and right pectorals, caudal-from both the inner core and trailing margin of each fin), and five internal organs (liver, kidney, spleen, heart, epigonal organ) from two different shark species, bonnethead (Sphyrna tiburo) and silky shark (Carcharhinus falciformis) to determine the relationships of THg concentrations between and within tissue groups. Total Hg concentrations were highest in the eight muscle regions with no significant differences in THg concentrations between the different muscle regions and muscle types (red and white). Results from tissue collected from any muscle region would be representative of all muscle sample locations. Total Hg concentrations were lowest in samples taken from the fin inner core of the first dorsal, pectoral, and caudal (lower lobe) fins. Mercury concentrations for samples taken from the trailing margin of the dorsal, pectoral, and caudal fins (upper and lower lobe) were also not significantly different from each other for both species. Significant relationships were found between THg concentrations in dorsal axial muscle tissue and the fin inner core, liver, kidney, spleen and heart for both species as well as the THg concentrations between the dorsal fin trailing margin and the heart for the silky shark and all other sampled tissue types for the bonnethead shark. Our results suggest that biopsy sampling of dorsal muscle can provide data that can effectively estimate THg concentrations in specific organs without using more invasive, or lethal methods.

Keywords: non-invasive techniques, shark health, human health, total mercury

SREL Reprint #3419

O'Bryhim, J. R., D. H. Adams, J. L.Y. Spaet, G. L. Mills, and S. L. Lance. 2017. Relationships of mercury concentrations across tissue types, muscle regions and fins for two shark species. Environmental Pollution 223(2017): 323-333.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).