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Coral bleaching and habitat effects on colonisation of reef fish assemblages: an experimental study
Stockholm University, Faculty of Science, Department of Zoology.
Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Systems Ecology.
Stockholm University, Faculty of Science, Department of Zoology.
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2011 (English)In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 94, no 1, 16-23 p.Article in journal (Refereed) Published
Abstract [en]

Degradation and mortality of corals is increasing worldwide and is expected to have significant effects on coral reef fish; hence studies on these effects are essential. In the present study, a field experiment was set up within Mafia Island Marine Park in Tanzania (East Africa) to examine the effects of bleaching and habitat structure on colonisation of coral reef fish assemblages. Live and bleached staghorn coral Acropora formosa was transplanted onto plots in a site dominated by sand and rubble, and the experimental design comprised of three treatments: live coral, bleached coral and eroded coral rubble. There was an immediate increase (within 24 h) in fish abundance and diversity in the two treatments with standing corals. Overall, live and bleached coral plots showed similar effects, but differed from the eroded coral plots which had a much lower abundance and diversity of fish. In general, fish species diversity changed with time over the study period while fish abundance did not. Multivariate analyses showed that while there were differences in fish assemblage structure between standing corals and the eroded coral treatment, there was neither a difference between live and bleached coral treatments nor any temporal effects on fish assemblage structure. Our findings suggest that physical structure and complexity of habitat have stronger effects on colonisation of reef fish assemblages than changes in coral health (such as bleaching) which do not affect coral structure. This may have important implications for appropriate coral reef management.

Place, publisher, year, edition, pages
2011. Vol. 94, no 1, 16-23 p.
Keyword [en]
coral reefs, fish communities, habitat degradation, disturbance, field experiment, resilience
National Category
Zoology Ecology
Research subject
Animal Ecology
URN: urn:nbn:se:su:diva-25796DOI: 10.1016/j.ecss.2011.04.012ISI: 000294150400002OAI: diva2:200532
Available from: 2009-03-05 Created: 2009-02-25 Last updated: 2012-01-17Bibliographically approved
In thesis
1. Habitat structure, degradation and management effects on coral reef fish communities
Open this publication in new window or tab >>Habitat structure, degradation and management effects on coral reef fish communities
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Coral reefs are among the most diverse and productive ecosystems on earth, and are critical to the survival of tropical marine ecosystems and sustenance of local human populations. However, coral reefs are quite vulnerable to disturbances, both natural and anthropogenic. This thesis looks at how coral reef communities have responded to climactic disturbances, particularly the 1997-98 El Niño Southern Oscillation (ENSO) and subsequent coral bleaching and mortality that affected much of the Indian Ocean, including the coastal waters of Tanzania, where the study was conducted. In particular, it investigates the effects of coral bleaching, habitat degradation and reef spatial arrangement on reef fish assemblages.

Habitat structural complexity and spatial arrangement of reefs had an effect on reef fish communities. Fish communities showed patterns in distribution among habitats and between patch and continuous reefs. Fishes preferred live to bleached/dead or eroded coral, but trophic groups reacted differently to patch and continuous reefs. There were slight changes in fish abundance and significant changes in fish diversity on experimental, bleached branching Acropora coral plots over a period of one year. While fish abundance on one site increased shortly after a bleaching event, 6 years later fish abundance had decreased significantly. Conversely, coral reef communities in northern Tanzania had changed little over an 8-year period, with minor changes associated with the 1997-98 ENSO and the presence or absence of fisheries management. The coral reefs in the region were found to show high variability in community structure and responses of associated fish and invertebrate communities.

The findings of this thesis indicate the importance of habitat structure and spatial arrangement of reefs, the detrimental effects of coral bleaching, and the possibility that some reefs and some (generalist) reef fish taxa may exhibit resilience to climate change.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2011. 46 p.
fish assemblages, climate change, coral degradation, Indian Ocean, patch reefs, coral bleaching, resilience
National Category
Ecology Zoology
Research subject
Animal Ecology
urn:nbn:se:su:diva-62187 (URN)978-91-7447-360-5 (ISBN)
Public defence
2011-10-07, Ahlmannsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Available from: 2011-09-15 Created: 2011-09-12 Last updated: 2011-09-13Bibliographically approved

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Yahya, Saleh A. S.Gullström, MartinÖhman, Marcus C.Andersson, Mathias H.
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