Mercury Concentrations in Marine Micronekton with Habitat Depth and Distance from Shore in Southern California

Mercury (Hg) is a neurotoxicant that bioaccumulates to harmful concentrations in high-trophic level animals. Micronekton (mid-trophic organisms between 2-20 cm) are important prey for high-trophic organisms. Hg and drivers affecting Hg bioavailability to micronekton are understudied despite the roles of these mid-trophic taxa in directly exposing high-trophic levels to Hg. For a 9-week research project, we examined how total mercury concentration ([THg]) in micronekton from Southern California varies between crustaceans and fishes, muscle tissue and whole body, habitat depth, and shore station (a proxy for surface productivity). In October 2023, specimens were collected using a 10m2 Multiple Opening/Closing Net and Environmental Sensing System. In the lab, specimens were dissected into muscle tissue and carcass to estimate whole body [THg], and analyzed for [THg] with a Nippon MA-3000 Direct Mercury Analyzer. [THg] did not differ between crustaceans and fishes. Whole body and muscle [THg] varied but were highly correlated within each species, so muscle [THg] can be used to estimate whole body [THg]. [THg] in crustaceans increased with habitat depth but did not increase in fishes, which may be explained by differences in ages or diets of fishes analyzed. [THg] in specimens collected at the offshore station were higher than at the nearshore station for all species examined, but differences between stations were not significant. This research expands our understanding of how Hg in micronekton varies with environmental conditions, affecting Hg exposure to high-trophic levels.

Presentation Preference: Poster

Primary Presenter: Alyssa Raynor, University of South Carolina (raynoralyssa2@gmail.com)

Authors:

Alyssa Raynor, University of South Carolina  (abraynor@email.sc.edu)

Rachel Chen, Integrative Oceanography Division, Scripps Institution of Oceanography at University of California San Diego  (rsc011@ucsd.edu)

Amina Schartup, Geosciences Research Division, Scripps Institution of Oceanography at University of California San Diego  (aschartup@ucsd.edu)

C. Anela Choy, Integrative Oceanography Division, Scripps Institution of Oceanography at University of California San Diego  (anela@ucsd.edu)