A cross‐system meta‐analysis reveals coupled predation effects on prey biomass and diversity |
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| Authors: | Izumi Katano Hideyuki Doi Britas Klemens Eriksson Helmut Hillebrand |
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| Affiliation: | 1. Inst. for Chemistry and Biology of the Marine Environment, Carl‐von‐Ossietzky Univ. Oldenburg, Wilhelmshaven, Germany;2. School of Human Science and Environment, Univ. of Hyogo, 1‐1‐12 Shinzaike‐Honcho, Himeji, Japan;3. Graduate School of Simulation Studies, Univ. of Hyogo, 7‐1‐28 Minatojima Minami‐machi, Chuo‐ku, Kobe, Japan;4. Dept of Marine Benthic Ecology and Evolution, Groningen Inst. for Evolutionary Life Sciences, Univ. of Groningen, AG Groningen, the Netherlands |
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| Abstract: | Predator diversity and abundance are under strong human pressure in all types of ecosystems. Whereas predator potentially control standing biomass and species interactions in food webs, their effects on prey biomass and especially prey biodiversity have not yet been systematically quantified. Here, we test the effects of predation in a cross‐system meta‐analysis of prey diversity and biomass responses to local manipulation of predator presence. We found 291 predator removal experiments from 87 studies assessing both diversity and biomass responses. Across ecosystem types, predator presence significantly decreased both biomass and diversity of prey across ecosystems. Predation effects were highly similar between ecosystem types, whereas previous studies had shown that herbivory or decomposition effects differed fundamentally between terrestrial and aquatic systems based on different stoichiometry of plant material. Such stoichiometric differences between systems are unlikely for carnivorous predators, where effect sizes on species richness strongly correlated to effect sizes on biomass. However, the negative predation effect on prey biomass was ameliorated significantly with increasing prey richness and increasing species richness of the manipulated predator assemblage. Moreover, with increasing richness of the predator assemblage present, the overall negative effects of predation on prey richness switched to positive effects. Our meta‐analysis revealed strong general relationships between predator diversity, prey diversity and the interaction strength between trophic levels in terms of biomass. This study indicates that anthropogenic changes in predator abundance and diversity will potentially have strong effects on trophic interactions across ecosystems. Synthesis The past centuries we have experienced a dramatic loss of top–predator abundance and diversity in most types of ecosystems. To understand the direct consequences of predator loss on a global scale, we quantitatively summarized experiments testing predation effects on prey communities in a cross‐system meta‐analysis. Across ecosystem types, predator presence significantly decreased both biomass and diversity of prey, and predation effects were highly similar. However, with increasing predator richness, the overall negative effects of predation on prey richness switched to positive ones. Anthropogenic changes in predator communities will potentially have strong effects on prey diversity, biomass, and trophic interactions across ecosystems. |
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