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Predator-prey encounter rates in freshwater piscivores: effects of prey density and water transparency

Author:
  • Håkan Turesson
  • Christer Brönmark
Publishing year: 2007
Language: English
Pages: 281-290
Publication/Series: Oecologia
Volume: 153
Issue: 2
Document type: Journal article
Publisher: Springer

Abstract english

One of the most fundamental components of predator-prey models is encounter rate, modelled as the product of prey density and search efficiency. Encounter rates have, however, rarely been measured in empirical studies. In this study, we used a video system approach to estimate how encounter rates between piscivorous fish that use a sit-and-wait foraging strategy and their prey depend on prey density and environmental factors such as turbidity. We first manipulated prey density in a controlled pool and field enclosure experiments where environmental factors were held constant. In a correlative study of 15 freshwater lakes we then estimated encounter rates in natural habitats and related the results to both prey fish density and environmental factors. We found the expected positive dependence of individual encounter rates on prey density in our pool and enclosure experiments, whereas the relation between school encounter rate and prey density was less clear. In the field survey, encounter rates did not correlate with prey density but instead correlated positively with water transparency. Water transparency decreases with increasing prey density along the productivity gradient and will reduce prey detection distance and thus predator search efficiency. Therefore, visual predator-prey encounter rates do not increase, and may even decrease, with increasing productivity despite increasing prey densities.

Keywords

  • Ecology
  • encounter rate piscivore ambush forager
  • turbidity water colour

Other

Published
  • ISSN: 1432-1939
Christer Brönmark
E-mail: christer [dot] bronmark [at] biol [dot] lu [dot] se

Head of unit

Division aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Professor

Aquatic Ecology

50

Professor

Division aquatic ecology

+46 46 222 37 02

+46 73 081 55 48

E-C125

Sölvegatan 37, Lund

50

Research group

Aquatic Ecology

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Doctoral students and postdocs

PhD students, main supervisor

Jerker Vinterstare

PhD students, assistant supervisor

  • Nan Hu
  • Varpu Pärssinen
  • Yongcui Sha
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