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Turbidity increases risk perception but constrains collective behaviour during foraging by fish shoals

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)129-138
Number of pages10
JournalAnimal Behaviour
Early online date18 Sep 2019
DateAccepted/In press - 17 Jul 2019
DateE-pub ahead of print - 18 Sep 2019
DatePublished (current) - 1 Oct 2019


Turbidity reduces the distance that animals can detect food, predators and conspecifics. How turbidity affects decision making in social contexts has rarely been investigated; moreover, it is unknown whether decreased shoaling in turbid water is due to visual constraints (a mechanistic explanation) or a reduced perception of predation risk (an adaptive explanation). Using a V-shaped decision-making arena, we investigated the effect of turbidity on foraging in groups of three-spined sticklebacks, Gasterosteus aculeatus. In turbid conditions, fish took longer to leave a refuge and locate the food in one of the arms and consumed less food once it was found. This increase in risk-averse behaviour was further supported by improved accuracy over repeated trials and a speed–accuracy trade-off only being observed in turbid conditions. Despite evidence of a higher perception of risk in turbid water, the first fish to choose an arm of the maze was more likely to be alone in turbid water; thus, this individual lost the antipredator and decision-making benefits of collective behaviour. This suggests that turbidity acts mechanistically as a visual constraint, shifting decisions away from being made collectively to being made by individuals separated from the group, which could have potential impacts for wild prey populations.

    Research areas

  • antipredator behaviour, collective behaviour, foraging, group decision making, refuge, stickleback



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    Licence: CC BY-NC-ND


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