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Effects of brown and turbid water on piscivore-prey fish interactions along a visibility gradient

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Author

Summary, in English

1. Environmental changes such as eutrophication and increasing inputs of humic matter (brownification) may have strong effects on predatorprey interactions in lakes through a reduction in the visual conditions affecting foraging behaviour of visually oriented predators. 2. In this experiment, we studied the effects of visual range (25200 cm) in combination with optically deteriorating treatments (algae, clay or brown humic water) on predatorprey interactions between pike (Esox lucius) and roach (Rutilus rutilus). We measured effects on reaction distance and strike distance for pike and escape distance for roach, when pike individuals were exposed to free-swimming roach as well as to roach held in a glass cylinder. 3. We found that reaction distance decreased with decreasing visual range caused by increasing levels of algae, clay or humic matter. The effect of reaction distance was stronger in turbid water (clay, algae) than in the brown water treatment. 4. Strike distance was neither affected by visual range nor by optical treatment, but we found shorter strike distances when pike attacked roach using visual cues only (roach held in a cylinder) compared to when pike could use multiple senses (free-swimming roach). Escape distance for roach was longer in turbid than in brown water treatments. 5. Changes in environmental drivers, such as eutrophication and brownification, affecting the optical climate should thus have consequences for the strength of predatorprey interactions through changes in piscivore foraging efficiency and prey escape behaviour. This in turn may affect lake ecosystems through higher-order interactions.

Publishing year

2012

Language

English

Pages

1761-1768

Publication/Series

Freshwater Biology

Volume

57

Issue

9

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Ecology

Keywords

  • behaviour
  • escape distance
  • foraging
  • reaction distance
  • visual range

Status

Published

Research group

  • Aquatic Ecology

ISBN/ISSN/Other

  • ISSN: 0046-5070