Size-dependent microhabitat use and intraspecific competition in Cottus gobio


Davey, A.J.H., Hawkins, S.J., Turner, G.F. and Doncaster, C.P. (2005) Size-dependent microhabitat use and intraspecific competition in Cottus gobio. Journal of Fish Biology, 67, (2), 428-443. (doi:10.1111/j.0022-1112.2005.00736.x).

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Description/Abstract

An electrofishing survey of daytime shelter microhabitat use of bullhead Cottus gobio in a southern English chalk stream revealed positive selection for moderate water velocity, vegetation cover and coarse substrata. Water depth, other forms of cover, shade and substratum embeddedness had no significant influence on the distribution of fish. Microhabitat use was size-dependent, with patches occupied by adult fish containing coarser substrata and less blanket weed (Cladophora algae) than those occupied by smaller juvenile conspecifics. Differences in substratum use between size-classes were less pronounced in parts of the stream shaded by the tree canopy. In laboratory tanks stocked at low fish density, both juveniles and adults favoured use of cobbles over pebbles. The response of fish to increased conspecific density was size-dependent; juveniles reduced use of the coarse substratum whereas adults maintained their predominance in this habitat. An apparently greater shift by juveniles when in the presence of adults was significant at a alpha = 0.10 only, as was an apparent reduction in interactions between size-classes under low light intensity. The displacement of small juvenile fish from the preferred cobble substratum is consistent with the hypothesis that intraspecific competition contributes to the size-related microhabitat shift observed in the field. Although there was a tendency for the strength of competition to be reduced at low light levels, the mechanism by which tree canopy cover affects microhabitat use remains uncertain.

Item Type: Article
ISSNs: 0022-1112 (print)
Related URLs:
Keywords: body size, density-dependence, interference, intraspecific competition, microhabitat shift, stream fish
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QL Zoology
S Agriculture > SH Aquaculture. Fisheries. Angling
Divisions: University Structure - Pre August 2011 > School of Biological Sciences
University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 35573
Date Deposited: 19 May 2006
Last Modified: 27 Mar 2014 18:22
URI: http://eprints.soton.ac.uk/id/eprint/35573

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