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

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

Research output: Contribution to journalArticlepeer-review

118 Citations (SciVal)

Abstract

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.
Original languageEnglish
Pages (from-to)1042-1048
JournalLimnology and Oceanography
Volume57
Issue number4
DOIs
Publication statusPublished - 2012

Subject classification (UKÄ)

  • Physical Geography

Keywords

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

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