Abstract

In the Baltic Sea, the predatory cladoceran Cercopagis pengoi is a non-indigenous species that has potential to compete for mesozooplankton with pelagic zooplanktivorous fish. To understand the extent of diet overlap with these fishes in a coastal area of the northern Baltic proper, we studied the feeding of C. pengoi using stable C-13 and N-15 isotope signatures of the predator and possible prey. Feasible combinations of sources were estimated in two ways: (i) with the IsoSource mixing model, and (ii) temporal-tracking analysis. Further, contribution of different prey was related to ambient zooplankton composition to gauge selectivity. The modelling results indicate that C. pengoi is an opportunistic generalist predator with a positive selection towards older copepodites (CIVVI) of Acartia spp. and Eurytemora affinis, which also have the greatest contribution to its diet. Positive selection towards podonid Cladocera is also likely. In contrast, evidence for extensive feeding on microzooplankton was inconclusive, and bosminids were not found to be an important prey in the zooplankton assemblages studied. As the derived diet of C. pengoi overlaps greatly with that of zooplanktivorous fish, food competition between these zooplanktivores is possible.

Keywords

mixing models; temporal-tracking analysis; selectivity; foodweb interactions; zooplankton

Published in

Journal of Plankton Research
2012, Volume: 34, number: 5, pages: 376-387
Publisher: OXFORD UNIV PRESS

UKÄ Subject classification

Oceanography, Hydrology, Water Resources
Ecology


Publication identifier

DOI: https://doi.org/10.1093/plankt/fbs008

Permanent link to this page (URI)

https://res.slu.se/id/publ/83288