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Terrestrial organic matter support of lake food webs : evidence from lake metabolism and stable hydrogen isotopes of consumers

På svenska

Author

  • Jan Karlsson
  • Martin Berggren
  • Jenny Ask
  • Pär Byström
  • Anders Jonsson
  • Hjalmar Laudon
  • Mats Jansson

Summary, in English

We quantified the utilization of terrestrial organic matter (OM) in the food web of a humic lake by analyzing the metabolism and the consumers' stable isotopic (C, H, N) composition in benthic and pelagic habitats. Terrestrial OM inputs (3 g C m(-2) d(-1)) to the lake greatly exceeded autochthonous OM production (3 mg C m(-2) d(-1)) in the lake. Heterotrophic bacterial growth (19 mg C m(-2) d(-1)) and community respiration (115 mg C m(-2) d(-1)) were high relative to algal photosynthesis and were predominantly (> 85%) supported by terrestrial OM in both habitats. Consequently, terrestrial OM fueled most (85%) of the total production at the base of the lake's food web (i.e., the sum of primary and bacterial production). Despite the uncertainties of quantitatively estimating resource use based on stable isotopes, terrestrial OM clearly also supported around half the zooplankton (47%), macrozoobenthos (63%), and fish (57%) biomass. These results indicate that, although rates of terrestrial OM inputs were around three orders of magnitude greater than that of autochthonous OM production, the use of the two resources by higher trophic levels was roughly equal. The disproportionally low reliance on terrestrial OM at higher trophic levels, compared with its high rates of input and high support of basic biomass production in the lake, suggests that autochthonous resources could not be completely replaced by terrestrial resources and indicates an upper limit to terrestrial support of lake food webs.

Publishing year

2012

Language

English

Pages

1042-1048

Publication/Series

Limnology and Oceanography

Volume

57

Issue

4

Document type

Journal article

Publisher

ASLO

Topic

  • Physical Geography

Keywords

  • NORTHERN SWEDEN
  • ALLOCHTHONOUS CARBON
  • BACTERIAL PRODUCTION
  • SECONDARY PRODUCTION
  • AQUATIC CONSUMERS
  • C-13 ADDITION
  • BOREAL LAKES
  • HUMIC LAKES
  • PHYTOPLANKTON
  • ZOOPLANKTON

Status

Published

ISBN/ISSN/Other

  • ISSN: 1939-5590