Analysis of carbon and nitrogen stable isotopes has allowed freshwater ecologists to examine lake food webs in increasing detail. Many such studies have highlighted the existence of separate within-lake pelagic and benthic-littoral food webs but are typically conducted on large (> 10 km2) lakes, whereas the majority of lakes are actually relatively small. We used stable isotope analysis (Î´13C & Î´15N) to examine trophic interactions between fish and their prey in PluÃ?see, as an example of a small, stratifying lake, and to determine whether separate pelagic/benthic-littoral food webs could be distinguished in such systems. Our results indicate that the PluÃ?see food web was complicated, and due to extensive intra-annual isotopic variation in zooplankton (e.g. cladoceran Î´13C annual range = 25.6â?°), it may be impossible to definitively assign consumers from small, eutrophic stratified lakes to pelagic or benthic-littoral food webs. We present evidence that some components of the PluÃ?see food web (large bream) may be subsidised by carbon of methanogenic origin.
ASJC Scopus subject areas
- Aquatic Science