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The effects of turbidity and complex habitats on the feeding of a galaxiid fish are clear and simple


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Stuart-Smith, RD, Stuart-Smith, JF, White, RWG and Barmuta, LA 2007 , 'The effects of turbidity and complex habitats on the feeding of a galaxiid fish are clear and simple' , Marine and Freshwater Research, vol. 58, No. 5 , pp. 429-435 , doi: 10.1071/MF06240.

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The habitat used by animals plays an important role in their interactions with predators and prey. By using
complex habitats such as areas of dense macrophyte cover in response to elevated predation risk, small fishes may reduce
their foraging success. Because the threat of predation by introduced brown trout increases the use of complex habitats
by the threatened Galaxias auratus (Johnston), we experimentally examined its foraging in different habitats to estimate
indirect impacts of brown trout presence. The lakes in which G. auratus lives have recently become more turbid, so
the experiment was also conducted under different turbidity levels. Laboratory feeding trials in which planktonic and
epibenthic prey were simultaneously offered to G. auratus in the presence or absence of artificial macrophytes and at
three turbidity levels (0, 50 and 100 NTU) revealed that its overall foraging success was unaffected by habitat complexity;
however, in trials with artificial macrophytes, G. auratus consumed a greater proportion of planktonic prey than in the
absence of artificial macrophytes. Neither overall foraging success nor prey selection by G. auratus was affected by high
turbidity, indicating that water clarity does not appear to directly negatively impact its feeding. The switch in prey types
would probably not be detrimental to G. auratus in the long term, and thus it appears that there is no substantial feeding
cost associated with its increased use of complex habitats. It could, however, affect lower trophic levels in the lakes to
which it is endemic.

Item Type: Article
Authors/Creators:Stuart-Smith, RD and Stuart-Smith, JF and White, RWG and Barmuta, LA
Keywords: artificial macrophytes, complex habitats, G. auratus, prey switching.
Journal or Publication Title: Marine and Freshwater Research
ISSN: 1323-1650
DOI / ID Number: 10.1071/MF06240
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