Altered complementary feeding strategies of the consumers and via passive selectivity

N. Aberle (1) , A. M. Malzahn (1) , J. Grey (2) , H. Hillebrand (3) , K. H. Wiltshire (1)

1 Biologische Anstalt Helgoland
2 School of Biological and Chemical Sciences
3 Carl-von-Ossietzky Universität Oldenburg, ICBM Terramare

This study aimed to identify differences in selectivity, foraging behaviour and complementary feeding of two benthic consumers (the isopod and the snail ) using traditional cell counting as an indicator for algal biomass reduction and stable isotope labelling to detect differences in assimilation and digestion. We hypothesized that even when active feeding preferences of food components are not apparent, passive selectivity via mechanisms such as food assimilation and digestion can be of relevance. Algal biomass was reduced to a similar degree by the grazers independently from grazer and prey combinations without any indication for an active choice of food components. However, the isotope labelling approach indicated that passive selectivity can alter complementary feeding strategies, as we detected shifts in feeding preferences in relation to food quantity and competition. Thus, stable isotope labelling of food components opens up new perspectives in community ecology, allowing assessment of such complex mechanisms as passive selectivity, complementary feeding and competition.

Mots clés: Benthic microalgae; Isotope fractionation; Resource partitioning; Microphytobenthos; Stable isotope enrichment

N. Aberle, A. M. Malzahn, J. Grey, H. Hillebrand, K. H. Wiltshire. Altered complementary feeding strategies of the consumers and via passive selectivity. Helgoland Marine Research, 2009, 63 (3), pp.189-197. ⟨10.1007/s10152-009-0148-9⟩. ⟨hal-00535187⟩