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Predator-prey interactions in aquatic environments

Johannesen, Asa (2013) Predator-prey interactions in aquatic environments. PhD thesis, University of Leeds.

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In the first half of this thesis, I have focused on predator ability to locate prey using olfaction and how prey aggregation and turbulence affect prey detection. In chapter 2 I investigate the ability of three spined sticklebacks to compensate for loss of visual cues by using olfaction and find that they can use olfactory cues but that these most likely help the fish detect prey rather than locate prey. In chapter 3 I explore the effect of prey aggregation as an anti-predator strategy when avoiding an olfactory predator and find that aggregated prey survive longer than do dispersed prey. In order to further investigate why this may be, I carried out an experiment using Gammarus pulex as the predator where I recorded search time as a function of prey group size. I found that similarly to detection distance, search time relates to the square root of the number of prey. Finally, I investigate the effect that turbulence in flowing water may have on prey group detection using three spined sticklebacks in a y-maze. I find that risk of detection increases with prey group size but that turbulence lowers this risk. This may mean that there are thresholds below which size prey groups can benefit from turbulence as a ‘sensory refuge’ thus avoiding predators. In the second part of my thesis I focus on the interactions between a cleaner fish and a parasite in an aquaculture setting focusing on whether said fish is useful as a cleaner in industry. I carry out experiments to investigate the use of lumpfish as salmon cleaners in terms of cleaning efficiency and behaviour. I find that while some lumpfish do clean salmon, the required circumstances are still unknown and that further work including selective breeding, personality and effects of tanks is necessary.

Item Type: Thesis (PhD)
ISBN: 978-0-85731-956-2
Academic Units: The University of Leeds > Faculty of Biological Sciences (Leeds)
Identification Number/EthosID: uk.bl.ethos.631386
Depositing User: Ethos Import
Date Deposited: 15 Dec 2014 09:48
Last Modified: 06 Oct 2016 14:42
URI: http://etheses.whiterose.ac.uk/id/eprint/7556

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