TY - JOUR

T1 - Stable isotope analysis provides fresh insights into dietary separation between Chironomus anthracinus and C. plumosus

AU - Kelly, Andrew

AU - Jones, Roger

AU - Grey, Jonathan

PY - 2004

Y1 - 2004

N2 - We used stable isotope analysis to investigate dietary differences between 2 sympatric species of tubicolous chironomid larvae, Chironomus plumosus and C. anthracinus, from the profundal sediments of 6 eutrophic lakes in the UK and Germany. We found striking variation between lakes in both δ13C (−29.8 to −56.3‰) and δ15N (−7.8 to 14.7‰) in the 2 chironomid species. Moreover, C. plumosus was consistently depleted in both 13C and 15N relative to C. anthracinus. Our data support previous reports of interspecific dietary variations between the 2 species, which suggest niche separation partly on the basis of diet. However, reported differences in the feeding modes of the 2 species could not explain the extreme 13C- and 15N-depletion observed in chironomid larvae from several of the lakes. We suggest that the low δ13C signatures result from the ingestion of methanotrophic bacteria and subsequent incorporation of biogenic methane-derived C. Further, the chironomid larvae enhance methanotrophic activity via bioturbation of the surrounding sediment. Significant isotope differences between the 2 species may result from their variable tube morphologies or physiology.

AB - We used stable isotope analysis to investigate dietary differences between 2 sympatric species of tubicolous chironomid larvae, Chironomus plumosus and C. anthracinus, from the profundal sediments of 6 eutrophic lakes in the UK and Germany. We found striking variation between lakes in both δ13C (−29.8 to −56.3‰) and δ15N (−7.8 to 14.7‰) in the 2 chironomid species. Moreover, C. plumosus was consistently depleted in both 13C and 15N relative to C. anthracinus. Our data support previous reports of interspecific dietary variations between the 2 species, which suggest niche separation partly on the basis of diet. However, reported differences in the feeding modes of the 2 species could not explain the extreme 13C- and 15N-depletion observed in chironomid larvae from several of the lakes. We suggest that the low δ13C signatures result from the ingestion of methanotrophic bacteria and subsequent incorporation of biogenic methane-derived C. Further, the chironomid larvae enhance methanotrophic activity via bioturbation of the surrounding sediment. Significant isotope differences between the 2 species may result from their variable tube morphologies or physiology.

KW - stable isotopes

KW - chironomid larvae

KW - interspecific variation

KW - methane

KW - bacteria

KW - lakes

U2 - 10.1899/0887-3593(2004)023<0287:SIAPFI>2.0.CO;2

DO - 10.1899/0887-3593(2004)023<0287:SIAPFI>2.0.CO;2

M3 - Journal article

VL - 23

SP - 287

EP - 296

JO - Journal of the North American Benthological Society

JF - Journal of the North American Benthological Society

SN - 0887-3593

IS - 2

ER -