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Aquatic Microbial Ecology

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AME 12:85-93 (1997)  -  doi:10.3354/ame012085

Productivity and heterotrophy influences on zooplankton delta13C in northern temperate lakes

France RL, del Giorgio PA, Westcott KA

Although a range of over 30o/oo in stable carbon isotope ratios has been recorded for freshwater plankton, no extensive synoptic survey has been undertaken to examine whether any environmental or ecophysiological determinants of delta13C exist. Here we reanalyze existing literature data on the seasonal variation in plankton delta13C from eutrophic lakes, and collect new data on mid-summer zooplankton delta13C from 52 Canadian Shield lakes, to demonstrate that plankton become enriched in 13C relative to 12C under conditions of high productivity and low pCO2. Low zooplankton delta13C signatures in humic/dystrophic lakes of high DOC (dissolved organic carbon) concentration and colour, and in clearwater lakes with high rates of epilimnetic respiration and hypolimnetic metabolism, suggest that the 13C-depletion observed in oligotrophic lakes is probably due to heterotrophic activity.

Zooplankton delta13C · Lake productivity · Heterotrophy

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