Habitat-specific bioaccumulation of methylmercury in invertebrates of small mid-latitude lakes in North America.
We examined habitat-specific bioaccumulation of methylmercury (MeHg) in aquatic food webs by comparing concentrations in pelagic zooplankton to those in littoral macroinvertebrates from 52 mid-latitude lakes in North America. Invertebrate MeHg concentrations were primarily correlated with water pH, and after controlling for this influence, pelagic zooplankton had significantly higher MeHg concentrations than littoral primary consumers but lower MeHg than littoral secondary consumers. Littoral primary consumers and pelagic zooplankton are two dominant prey for fish, and greater MeHg in zooplankton is likely sufficient to increase bioaccumulation in pelagic feeders. Intensive sampling of 8 lakes indicated that habitat-specific bioaccumulation in invertebrates (of similar trophic level) may result from spatial variation in aqueous MeHg concentration or from more efficient uptake of aqueous MeHg into the pelagic food web. Our findings demonstrate that littoral-pelagic differences in MeHg bioaccumulation are widespread in small mid-latitude lakes.
Groupe de recherche interuniversitaire en limnologie, Département de sciences biologiques, Université de Montréal, Montréal, Québec H3C 3J7, Canada. Electronic address: john.chetelat@ec.gc.ca.
John
J
Chételat
Groupe de recherche interuniversitaire en limnologie, Département de sciences biologiques, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
Marc
M
Amyot
Groupe de recherche interuniversitaire en limnologie, Département de sciences biologiques, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
Edenise
E
Garcia
D000818:Animals; D017753:Ecosystem; D007448:Invertebrates / Q000737:chemistry / Q000378:metabolism*; D008767:Methylmercury Compounds / Q000032:analysis / Q000378:metabolism*; D009656:North America
D008767:Methylmercury Compounds