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Carbon transfer in herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer

We compared carbon budgets between a herbivore-dominated and a microbial loop-dominated food web and examined the implications of food web structure for fish production. We used the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was domin...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2010-01, Vol.398, p.93-107
Main Authors: De Laender, Frederik, Van Oevelen, Dick, Soetaert, Karline, Middelburg, Jack J.
Format: Article
Language:English
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Summary:We compared carbon budgets between a herbivore-dominated and a microbial loop-dominated food web and examined the implications of food web structure for fish production. We used the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was dominated by the herbivorous web, the diet of protozoa consisted of similar amounts of bacteria and phytoplankton. Copepods showed no clear preference for protozoa. CodGadus morhua, a predatory fish preying on copepods and on copepod-feeding capelinMallotus villosusin spring, moderately depended on the microbial loop in spring, as only 20 to 60% of its food passed through the microbial loop. In summer, when the food web was dominated by the microbial loop, protozoa ingested 4 times more bacteria than phytoplankton and protozoa formed 80 to 90% of the copepod diet. Because of this strong link between the microbial loop and copepods (the young cod’s main prey item) young cod (60% of its food passed through the microbial loop in summer. Adult cod (≤3 yr) relied far less on the microbial loop than young cod as it preyed on strictly herbivorous krill in summer. Food web efficiency for fish production was comparable between seasons (~5 × 10–4) and 2 times higher in summer (5 × 10–2) than in spring for copepod production.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps08335