Environmental Biology of Fishes

, Volume 78, Issue 1, pp 57–69 | Cite as

Anthropogenic Stressors, Inter-Specific Competition and ENSO Effects on a Mauritian Coral Reef

  • Nicholas A. J. Graham
  • Timothy R. McClanahan
  • Yves Letourneur
  • René Galzin
Original paper


Much of the western Indian Ocean suffered widespread loss of live coral in 1998 and interest is now focussed on the indirect effects of this coral loss on other components of the ecosystem, in particular fishes. However, it is just as important to identify changes in fish assemblages at locations that did not suffer coral mortality to understand local versus regional drivers. We surveyed benthic and fish communities on a reef flat in Mauritius five times between 1994 and 2005. The design allowed for comparison through time, along the coast and between inshore and offshore reef locations. The benthic community demonstrates a clear trend along the coast, likely in response to a dredged water ski lane, but little change through time. Branching Acropora colonies dominate much of the live coral and best explain patterns in the fish assemblage (P < 0.01). Few changes in overall fish species richness through time were identified, and observed changes were within fishery target families rather than species reliant on live coral. Departure from expected levels of taxonomic distinctness suggests degradation in the community associated with the dredged ski lane. Non-metric multi-dimensional scaling of the fish assemblage demonstrates a similar pattern to that seen in the benthos; greater differences along the coast (Global R = 0.34) than through time (Global R = 0.17) and no trend between reef positions. SIMPER analysis identified two species of Stegastes as the main drivers of trends in the MDS plot and the most dominant of these, S. lividus, appears to be reducing species richness of the remaining fish community. The study highlights Mauritius as a regional refugia of thermally-sensitive corals and specialised fish, suggesting a need for careful management.


Climate change Community structure Reef fishes Coral bleaching Mascarene Islands Tourism Stegastes Western Indian Ocean 


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This work was funded by the Leverhulme Trust, Eppley Foundation, the Marine Science for Management Program (MASMA) of the Western Indian Ocean Marine Science Association and the Fisheries Society of the British Isles. Many thanks to Hotel Victoria, in particular Hervé Doboscq for field support. We are grateful to Mehdi Adjeroud, Gilbert Poli, Bernard Salvat, Michel Porcher and Nyawira Muthiga for assistance with field studies. We thank the Mauritius Institute of Oceanography and Director, Dr. Bhikajee, for permission to undertake the work.


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Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Nicholas A. J. Graham
    • 1
  • Timothy R. McClanahan
    • 2
  • Yves Letourneur
    • 3
  • René Galzin
    • 4
  1. 1.School of Marine Science & TechnologyUniversity of NewcastleNewcastle-upon-Tyne,UK
  2. 2.Wildlife Conservation Society, Marine ProgramsBronxUSA
  3. 3.Centre d’Océanologie de Marseille, UMR CNRSUniversité de la MéditerranéeMarseille Cedex 09France
  4. 4.FRE 2935 CNRS-EPHE, Ecosystèmes CoralliensUniversité de PerpignanPerpignan CedexFrance

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