Data from: Nonadditive effects of consumption in an intertidal macroinvertebrate community are independent of food availability but driven by complementarity effects

Suboptimal environmental conditions are ubiquitous in nature and commonly drive the outcome of biological interactions in community processes. Despite the importance of biological interactions for community processes, knowledge on how species interactions are affected by a limiting resource, e.g. low food availability, remains limited. Here, we tested whether variation in food supply causes non-additive consumption patterns, using the macroinvertebrate community of intertidal sandy beaches as a model system. We quantified isotopically labelled diatom consumption by three macroinvertebrate species (Bathyporeia pilosa, Haustorius arenarius and Scolelepis squamata) kept in mesocosms in either monoculture or a 3-species community at a range of diatom densities. Our results show that B. pilosa was the most successful competitor in terms of consumption at both high and low diatom density, while H. arenarius and especially S. squamata consumed less in a community than in their respective monocultures. Non-additive effects on consumption in this macroinvertebrate community were present and larger than mere additive effects, and similar across diatom densities. The underlying species interactions, however, did change with diatom density. Complementarity effects related to niche-partitioning were the main driver of the net diversity effect on consumption, with a slightly increasing contribution of selection effects related to competition) with decreasing diatom density. For the first time we showed that non-additive effects of consumption are independent of food availability in a macroinvertebrate community. This suggests that in communities with functionally different, and thus complementary, species, non-additive effects can arise even when food availability is low. Hence, at a range of environmental conditions, species interactions hold important potential to alter ecosystem functioning.,exp_2a_13C_15N_harvest_and_t0_macroinvertebratesSee first tab for informationexp_2a_biomass_t0_macroinvertebratesSee first tab for informationexp_2a_survival_and_biomass_harvest_macroinvertebratesSee first tab for informationexp_2b_13C_15N_part1_harvest_and_t0_macroinvertebratesSee first tab for informationexp_2b_13C_15N_part2_harvest_macroinvertebratesexp_2b_survival_and_biomass_harvest_macroinvertebratesSee first tab for informationexp_2b_biomass_t0_macroinvertebratesSee first tab for information,