African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1047

Full Length Research Paper

Effects of river sediments on coral recruitment, algal abundance benthic community structure on Kenyan coral reefs

Shaaban A. Mwachireya
  • Shaaban A. Mwachireya
  • Kenya Marine and Fisheries Research Institute, P. O. BOX 81651, Mombasa 80100, Kenya.
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Tim R. McClanahan
  • Tim R. McClanahan
  • Wildlife Conservation Society, Marine Programs, Bronx, NY. 10460, USA.
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Brian E. Hartwick
  • Brian E. Hartwick
  • Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6 Canada.
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Isabelle M. Cote
  • Isabelle M. Cote
  • Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6 Canada.
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Lance Lesack
  • Lance Lesack
  • Department of Geography, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6 Canada.
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  •  Received: 12 January 2015
  •  Accepted: 14 July 2015
  •  Published: 30 July 2015

Abstract

The effects of sediment concentration and season on coral recruitment algal abundance and benthic community structure were studied in Kenyan coral reef lagoons to determine their potential influence on coral recovery. Nutrient levels and recruit numbers were higher during the southeast monsoon (SEM) than during the northeast monsoon (NEM) season and in sediment-exposed compared to non-sediment exposed reefs. Mean algal biomass also exhibited the same seasonal trend (except at one site), but was higher in the non-sediment exposed reef compared to the other reefs. Corals in the sediment exposed reef exhibited morphological differences relative to the other reefs: fewer corymbose and plate-like but more branching, massive and solitary forms and increased colony and corallite sizes. However, sediments did not suppress coral recruitment rates. These morphological changes coupled with the interaction between biological and physico-chemical characteristics have important ecological and geological implications: by potentially modifying calcium carbonate production and ameliorating the adverse effects of climate induced stress events, this may minimize coral mortality and enhance reef recovery. 
 
Key words: Algal biomass, coral recruitment, hydrodynamics, coral morphology, seasonality, sediments.