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Mangrove fish: a comparison of community structure between forested and cleared habitats

Huxham, M; Kimani, E; Augley, J

Authors

E Kimani

J Augley



Abstract

The fish communities of mangrove and cleared sites were investigated in Gazi Bay, Kenya. Five forested sites were compared with paired sites that had been cleared of mangroves by human activity. Forested sites included plantations and natural stands of Sonneratia alba and natural Rhizophora mucronata stands. Two methods of stake netting were used to take quantitative samples; method one used a single 100-m-long, 18-mm mesh net, method two used paired 24-m-long, 1-mm mesh nets—samples were taken during seven different months in 2002. Mean abundances of fish found in mangrove and cleared sites, respectively, were 0.004 m−2 and 0.014 m−2 (method 1) and 0.21 m−2 and 0.25 m−2 (method 2). Thirty species were sampled, 12 of which were found exclusively in mangrove habitats and 10 of which were limited to cleared sites. The most abundant species in mangrove plots was Atherina afra (although it was only found in two, large catches); the most abundant in cleared plots was Gerres oyena (found frequently). Mean abundance (using data pooled for all sites) was significantly higher in cleared, compared with forested, sites, and multivariate analysis showed significantly different community structures in the two habitat types. There was large variation in catch rates between dates and sites, with one forested site recording no catches at all. These results do not support the predator refuge hypothesis (which predicts higher abundance of juvenile fish inside mangroves). The low abundance of fish recorded in the mangrove sites may have been due to site-specific factors determining fish abundance within mangrove forests, to the sampling techniques used or to relatively high turbidities at these sites.

Citation

Huxham, M., Kimani, E., & Augley, J. (2004). Mangrove fish: a comparison of community structure between forested and cleared habitats. Estuarine, Coastal and Shelf Science, 60(4), 637-647. https://doi.org/10.1016/j.ecss.2004.03.003

Journal Article Type Article
Acceptance Date Mar 18, 2004
Online Publication Date May 18, 2004
Publication Date 2004-08
Deposit Date Jul 10, 2008
Journal Estuarine, Coastal and Shelf Science
Print ISSN 0272-7714
Electronic ISSN 0272-7714
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 60
Issue 4
Pages 637-647
DOI https://doi.org/10.1016/j.ecss.2004.03.003
Keywords Mangrove; Clearing; Fish species; Fish abundance; Cleared coastlines; Forested coastlines; Stake net; East Africa; Predator refuge hypothesis; Contrary evidence;
Public URL http://researchrepository.napier.ac.uk/id/eprint/1702
Publisher URL http://dx.doi.org/10.1016/j.ecss.2004.03.003