Stable isotope variability of meso‐zooplankton along a gradient of dissolved organic carbon

Abstract

1. The d 13 C and d 15 N signatures of zooplankton vary with dissolved organic carbon (DOC), but inconsistent and limited taxonomic resolution of previous studies have masked differences that may exist among orders, genera or species and are attributable to dietary and ⁄ or habitat differences. Here we investigate differences among the isotopic signatures of five zooplankton taxa (Daphnia, Holopedium, large Calanoida, small Calanoida and Cyclopoida) in Precambrian shield lakes with a sixfold range of DOC concentration. 2. d 13 C signatures of Daphnia, small calanoids and large calanoids became more depleted with increasing lake DOC, whereas Holopedium and cyclopoid d 13 C became enriched with increasing DOC concentration. 3. The variability of d 13 C and d 15 N isotopic signatures among zooplankton groups was reduced in high-DOC, compared to low-DOC lakes, especially for d 13 C. Differences in d 13 C and POM-corrected d 15 N accounted for up to 33.7% and 19.5% of the variance, respectively, among lakes of varying DOC concentration. 4. The narrow range of signatures found in higher DOC lakes suggests that different taxa have similar food sources and ⁄ or habitats. In contrast, the wide range of signatures in low-DOC lakes suggests that different taxa are exploiting different food sources and ⁄ or habitats. Together with the variable trends in zooplankton isotopic signatures along our DOC gradient, these results suggest that food web dynamics within the zooplankton community of temperate lakes will change as climate and lake DOC concentrations change.

Contrasting patterns of allochthony among three major groups of crustacean zooplankton in boreal and temperate lakes

“…Cyclopoids, which tend to be selective raptorial feeders (Barnett et al 2007), had allochthony values (UT cycl ) uncoupled from those of the particulate organic matter (POM) pool (Fig. This interpretation agrees with previous findings of cyclopoids in temperate lakes showing an increasingly terrestrial-like d 13 C signature along a gradient of increasing DOM (Persaud et al 2009). Rather, UT cycl values were positively correlated to water color (Color abs440 ), concentrations of bioavailable dissolved organic matter (BDOM 14d ) and to bacterial production (BP), indicating that the cyclopoids obtained their allochthony from a microbial food chain based on terrestrial-derived DOM (Jansson et al 2007, Berggren et al 2010.…”

Stable carbon isotope signatures of zooplankton in some reservoirs in Korea

“…One eutrophic reservoir, Lake Masan, had a pattern different from the other reservoirs, showing that zooplankton δ 13 C decreased with increasing DOC concentration. With this exception, the results of this study are consistent with results of other studies showing an inverse relationship between zooplankton δ 13 C values and DOC concentrations (France et al 1997, Jones et al 1999, Lennon et al 2006, Persaud et al 2009). In this study, the difference in zooplankton δ…”

The jellification of north temperate lakes

“…Our SEM also suggests that 'less competition' for resources with other herbivorous zooplankton, principally daphniids, is linked to increasing absolute abundances of Holopedium as Ca levels decline. Competition between Holopedium and Daphnia is well documented [6][7][8]14], and a comparison of recent daphniid and Holopedium fecundity supports the competition mechanism. In the regional-scale monitoring survey, the average clutch size of Holopedium was twice that of its most common daphniid competitors (electronic supplementary material, figure S2), suggesting it rspb.royalsocietypublishing.org Proc.…”