Habitat-speciﬁc bioaccumulation of methylmercury in invertebrates of small
mid-latitude lakes in North America
, Marc Amyot, Edenise Garcia
Groupe de recherche interuniversitaire en limnologie, Département de sciences biologiques, Université de Montréal, Montréal, Québec H3C 3J7, Canada
Methylmercury levels in dominant invertebrate prey for ﬁsh differ between littoral and pelagic habitats within a lake.
Received 21 April 2010
Received in revised form
3 September 2010
Accepted 23 September 2010
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 littoralepelagic differences in MeHg bio-
accumulation are widespread in small mid-latitude lakes.
Ó 2010 Elsevier Ltd. All rights reserved.
The habitat where a ﬁsh feeds in a lake can affect the amount of
mercury that accumulates in its body. Speciﬁcally, pelagic-feeding
ﬁsh tend to have higher body burdens of mercury for their trophic
position than ﬁsh that feed in the littoral zone (Ethier et al., 2008;
Gorski et al., 2003; Power et al., 2002; Stewart et al., 2008),
although this pattern is not always observed (Chumchal and
Hambright, 2009). Differences between ﬁsh species in their
mercury burdens can reﬂect the inﬂuence of habitat use; for
example, whiteﬁsh (Coregonus clupeaformis) and white sucker
(Catostomus commersoni) that commonly feed on benthic inverte-
brates can have lower mercury burdens than zooplanktivores such
as cisco (Coregonus artedi) in the same water body (Strange et al.,
1991; Tremblay, 1999). Among-lake variation in the mercury
burden of predatory species such as northern pike (Esox lucius) may
also be related to their consumption of either planktivorous or
benthivorous ﬁsh (Gorski et al., 2003).
Most evidence for the inﬂuence of habitat-speciﬁc feeding on
mercury bioaccumulation is based on correlations between ﬁsh
mercury levels and their carbon stable isotope ratios (e.g., Gorski
et al., 2003; Power et al., 2002), and it is unclear what factors are
driving these patterns. Variation in methylmercury (MeHg)
concentrations of prey or differences in bioenergetic budgets (e.g.,
feeding rates, assimilation efﬁciencies of mercury, speciﬁc growth
rates, and growth efﬁciency) can all lead to such differences (Trudel
and Rasmussen, 2006). This paper will address the contribution of
prey MeHg concentrations to the habitat-speciﬁc pattern by
comparing two dominant types of invertebrates consumed by ﬁsh:
zooplankton in the pelagic zone and macroinvertebrates in the
littoral zone (Vander Zanden and Vadeboncoeur, 2002).
MeHg bioaccumulation in aquatic invertebrates is controlled by
their trophic level (Cremona et al., 2008) as well as environmental
factors that affect the supply of MeHg to food webs, namely inor-
ganic mercury loading (Harris et al., 2007), pH (Watras et al., 1998),
and dissolved organic carbon (DOC) (Rennie et al., 2005). Acidic
waters increase the bioavailability of inorganic mercury (Kelly et al.,
) and stimulate bacterial production of MeHg (Miskimmin
al., 1992). DOC forms strong complexes with MeHg and can
alter its bioavailability for uptake in food webs (Gorski et al., 2008;
Pickhardt and Fisher, 2007). DOC is also an important vector for
watershed transport of mercury to lakes from terrestrial and
wetland sources (Garcia and Carignan, 1999; St. Louis et al., 1996).
Lake productivity can inﬂuence MeHg bioaccumulation in aquatic
invertebrates through growth dilution processes. As phytoplankton
production increases, the mercury concentration per algal cell
E-mail address: firstname.lastname@example.org (J. Chételat).
Present address: Environment Canada, National Wildlife Research Centre,
Carleton University, Ottawa, Ontario K1A 0H3, Canada.
Present address: The Nature Conservancy, Cuiabá e MT CEP 78050-400, Brazil.
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0269-7491/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
Environmental Pollution 159 (2011) 10e17