Confusion effects in a turbid environment

Dobbinson, Khia Emily

Biological sciences
September 2015

Thesis or dissertation

© 2015 Khia Emily Dobbinson. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

The structure of many ecosystems is shaped by the interactions between predators and their prey. A particular challenge to the attack success of predators is presented by the grouping strategies of prey. Predator confusion is characterised by inability to ‘lock on’ to and successfully target a particular individual, reducing the number of successful attacks. Prey groups that are particularly large or dense can overburden the sensory system of the predator, resulting in the ‘confusion effect’. While the confusion effect is well characterised in clear water systems, there is a paucity of research looking at predator confusion in turbid environments. Turbidity is a natural feature of aquatic ecosystems, however it is increasingly driven by human activity. Exposure to turbid environments can change the way fish feed, shoal and reproduce in addition to altering predator-prey interactions. While no convincing evidence of low levels of turbidity altering behavioural manifestations of the confusion effect were found, there was evidence of confusion in groups that were denser, but not necessarily those that were larger. Our findings suggest that density, rather than number, is the major driver behind the confusion effect and it is highly likely (but subject to further testing) that the space a prey group takes up (area) contributes to predator confusion.

School of Biological, Biomedical and Environmental Sciences, The University of Hull
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