Original paper
Food niches of cyclopoid copepods in eutrophic Plußsee determined by stable isotope analysis
Santer, Barbara; Sommerwerk, Nike; Grey, Jonathan
Archiv für Hydrobiologie Volume 167 Number 1-4 (2006), p. 301 - 316
59 references
published: Oct 5, 2006
DOI: 10.1127/0003-9136/2006/0167-0301
ArtNo. ESP141016770019, Price: 29.00 €
Abstract
Feeding studies have suggested interspecific differences in the food sources and trophic position of cyclopoid copepod species. We measured δ13 C and δ15 N of five sympatric cyclopoid copepod species and of bulk POM from a eutrophic lake over a one-year period, to determine if stable isotope derived-data from the field supported the hypotheses from feeding studies. Cyclops abyssorum and C. vicinus differed significantly in δ15 N but not in δ13 C, inferring assimilation from similar carbon sources but differentiation in their trophic position. Cyclops abyssorum δ15 N typically was 1–2‰ higher than C. vicinus, suggesting a more predatory feeding mode compared to its congener. The summer species Mesocyclops leuckarti, Thermocyclops oithonoides and Diacyclops bicuspidatus exhibited considerable differences in δ13 C. The lower δ13 C of the hypolimnetic D. bicuspidatus compared to the two epilimnetic species indicates a food niche differentiation by vertical separation. All copepod δ13 C and δ15 N signatures showed seasonal fluctuations, with low values in winter and high values in summer. The δ13 C of seston was generally higher than copepod δ13 C. We regard selective feeding from the bulk POM, spatial separation of feeding and assimilation of 13 C depleted food sources responsible for this phenomenon.
Keywords
δ13 C • δ15 N • trophic position • competition • plankton