Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modeling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator–prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator–predator interference effects.
Bibliographical noteFunding Information:
This article is dedicated to Prof. Olaf L.F. Weyl, who passed away suddenly on the 14 November 2020. He provided immense support for work on ephemeral wetlands in Southern Africa, and other freshwaters. RNC is funded through a Postdoctoral Research Fellowship from the Alexander von Humboldt Foundation. TD acknowledges funding from the National Research Foundation (Grant No. 117700). This study received funding from the Department for the Economy, Northern Ireland. We thank Rhodes University for the provision of laboratory facilities. We acknowledge the use of infrastructure and equipment provided by the South African Institute for Aquatic Biodiversity (SAIAB) Research Platform and the funding channeled through the National Research Foundation—SAIAB Institutional Support system. This study was partly funded by the National Research Foundation—South African Research Chairs Initiative of the Department of Science and Innovation (Inland Fisheries and Freshwater Ecology, Grant No. 110507).
© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
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- functional response
- multiple predator effects
- temporary pond
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Nature and Landscape Conservation