title: Bioaccumulation and biomagnification of mercury and methylmercury in four sympatric coastal sharks in a protected subtropical lagoon.
abstract: Mercury bioaccumulation is frequently observed in marine ecosystems, often with stronger effects at higher trophic levels. We compared total mercury (THg) and methylmercury (MeHg) from muscle with length, comparative isotopic niche, and diet (via δ13C and δ15N) among four sympatric coastal sharks in Florida Bay (USA): blacknose, blacktip, bull, and lemon. Mercury in blacknose and blacktip sharks increased significantly with size, whereas bull and lemon sharks had a high variance in mercury relative to size. Both δ13C and δ15N were consistent with general resource use and trophic position relationships across all species. A significant relationship was observed between δ13C and mercury in blacktip sharks, suggesting an ontogenetic shift isotopic niche, possibly a dietary change. Multiple regression showed that δ13C and δ15N were the strongest factors regarding mercury bioaccumulation in individuals across all species. Additional research is recommended to resolve the mechanisms that determine mercury biomagnification in individual shark species.
authors.affiliation: Nova Southeastern University, Halmos College of Natural Sciences and Oceanography, 5000 N. Ocean Dr., Dania Beach, FL 33004, USA; University of Miami, Rosenstiel School for Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Matulik
authors.affiliation: Nova Southeastern University, Halmos College of Natural Sciences and Oceanography, 5000 N. Ocean Dr., Dania Beach, FL 33004, USA. Electronic address: kerstett@nova.edu.
authors.forename: David W
authors.initials: DW
authors.lastname: Kerstetter
authors.affiliation: University of Miami, Rosenstiel School for Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
authors.forename: Neil
authors.initials: N
authors.lastname: Hammerschlag
authors.affiliation: Biodiversity Research Institute, 276 Canco Rd., Portland, ME 04103, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Divoll
authors.affiliation: Department of Earth & Environmental Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
authors.forename: Chad R
authors.initials: CR
authors.lastname: Hammerschmidt
authors.affiliation: Biodiversity Research Institute, 276 Canco Rd., Portland, ME 04103, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Evers
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D005431:Florida; D020387:Food Chain; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis; D012754:Sharks; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D008767:Methylmercury Compounds; D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Apex predators; Florida Bay; Mercury; Sharks; Stable isotopes; Trophic transfer