Effects of fish predation on density and size spectra of prey fish communities in lakes

Mehner, Thomas; Keeling, Caroline; Emmrich, Matthias; Holmgren, Kerstin; Argillier, Christine; Volta, Pietro; Winfield, Ian J. ORCID: https://orcid.org/0000-0001-9296-5114; Brucet, Sandra. 2016 Effects of fish predation on density and size spectra of prey fish communities in lakes [in special issue: Size-based approaches in aquatic ecology and fisheries science: a symposium in honour of Rob Peters] Canadian Journal of Fisheries and Aquatic Sciences, 73 (4). 506-518. 10.1139/cjfas-2015-0034

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Abstract/Summary

Planktivorous and benthivorous fish have been documented to influence the density and size structure of their prey communities in lakes. We hypothesized that piscivorous fish modify their prey fish communities in the same way and sought to find evidence for such predation effects from a comparison across 356 lakes located in nine European ecoregions. We categorized individual fish as being either piscivore, non-piscivore or prey of piscivores, depending on species and individual size. We calculated piscivore, non-piscivore and piscivore prey densities, respectively, and fit linear abundance size spectra (SS) on lake-specific piscivore, non-piscivore and piscivore prey size distributions. Multiple linear regressions were calculated to quantify the effect of piscivore density and SS slopes on non-piscivore and piscivore prey densities and SS slopes, by accounting for potentially confounding factors arising from lake morphometry, productivity and local air temperature. Piscivore density correlated positively with piscivore prey density, but was uncorrelated to density of non-piscivores. Across a subset of 76 lakes for which SS slopes of piscivores were statistically significant, SS slopes of piscivores were uncorrelated with SS slopes of either non-piscivores or piscivore prey. However, densities of piscivores, non-piscivores or piscivore prey were a significant negative predictor of SS slopes of the respective groups. Our analyses suggest that direct predation effects by piscivorous fish on density and size structure of prey fish communities are weak in European lakes, likely caused by low predator-prey size ratios and the resulting size refuges for prey fish. In contrast, competition may substantially contribute to between-lake variability in fish density and size.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1139/cjfas-2015-0034
UKCEH and CEH Sections/Science Areas:	Parr
ISSN:	0706-652X
Funders/Sponsors:	European Commission
Additional Keywords:	abundance size spectra, predator-prey interaction, across-lake comparison
NORA Subject Terms:	Ecology and Environment
Date made live:	10 Nov 2015 14:05 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/506354

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