Cascading effects from predator removal depend on resource availability in a benthic food web |
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Authors: | Katrin Sieben Anneke D Rippen Britas Klemens Eriksson |
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Institution: | (1) Department of Marine Benthic Ecology and Evolution, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 11103, 9700 CC Groningen, The Netherlands |
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Abstract: | We tested joint effects of predator loss and increased resource availability on the grazers’ trophic level and the propagation
of trophic interactions in a benthic food web by excluding larger predatory fish from cages and manipulating nutrients in
the coastal zone of the Baltic Sea. The combination of nutrient enrichment and excluding larger predators induced an increase
in medium-sized predatory fish (three-spined stickleback). The meso-predator fish in turn did not change the total abundance
of the invertebrate herbivores, but did cause a substantial shift in their community composition towards the dominance of
gastropods by reducing amphipods by 40–60%, while gastropods were left unchanged. The shift in grazer composition generated
a 23 times higher producer biomass, but only under nutrient enrichment. Our results show that top-predator declines can substantially
shift the species composition at the grazers’ level, but that cascading effects on producers by a trophic cascade strongly
depend on resource availability. |
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Keywords: | |
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