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Differences in feeding behaviour among C hironomus species revealed by measurements of sulphur stable isotopes and cadmium in larvae
Author(s) -
Proulx Isabelle,
Hare Landis
Publication year - 2014
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/fwb.12247
Subject(s) - water column , biology , anoxic waters , sympatric speciation , stable isotope ratio , ecology , chemocline , larva , cadmium , isotopes of nitrogen , environmental chemistry , chemistry , physics , organic chemistry , quantum mechanics
SummaryWe set out to determine the feeding behaviours of 15 C hironomus species collected from 16 boreal forest lakes by measuring cadmium (Cd) and stable isotopes of carbon (C), nitrogen (N) and sulphur (S) in larvae. Measurements of S stable isotopes and Cd discriminated between C hironomus species that feed mainly on oxic particles from those that feed mainly on anoxic particles. Our results suggest that C . dilutus , C . entis , C . plumosus and C . staegeri feed mainly on oxic particles (in the water column, in sediment or both), whereas C . anthracinus , C . bifurcatus , C . cucini , C . decorus ‐group sp. 2, C . harpi , C . nr. atroviridis (sp. 2i), C . ochreatus , C . spp. NAI ‐ NAIII and C . ‘tigris’ feed mainly on anoxic sediments. In our study lakes, larval C isotopic signatures were relatively high, which suggests that they feed little on methanotrophic bacteria. Although larval C and N signatures differed between some sympatric C hironomus species, these differences were not consistent among lakes. The absence of a trend among lakes suggests that lake‐specific factors determine larval C and N signatures. Differences in feeding habits and Cd concentrations among sympatric (cohabiting) C hironomus species suggest that pooling them in ecological, palaeolimnological or ecotoxicological studies could obscure trends in nature, thereby limiting their use as monitors of climate change or pollution.