Decadal coral community reassembly on an African fringing reef
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Changes in the cover of the dominant hard coral taxa were studied on seven Kenyan back reefs over 20 yr. All factors of time, taxa, site, and their interactions were statistically significant and the 1998 temperature anomaly caused the greatest community changes. The 1998 disturbance changes reflected a classic coral succession, which included partial or little mortality and persistence of stress tolerant (massive and submassive growth forms) and early colonization by weedy taxa (pocilloporids). Nevertheless, competitive taxa had high and full mortality and the expected dominance of acroporids was inhibited even ~13 yr after the disturbance. So, while total hard coral cover displayed the expected logistic recovery where maximum cover was reached <10 yr after the disturbance, the poor recovery of competitive dominants resulted in less than expected coral cover. A number of stress-resistant and weedy taxa (poritids, agaricidae, faviids, and pocilloporids) are expected to dominate the composition of these reefs in the future. Nevertheless, three submassive faviids and branching Porites began to decline toward the end of the time series, indicating further stress after 1998. Increased algal cover and other unstudied factors, including milder warming, may explain these changes. The patterns of change on this continental fringing reef differ from recovery of more remote, offshore islands. This probably reflects low acroporid dominance and recruitment limitations associated with greater anthropogenic influences of high sea urchin grazing and terrestrial runoff.
KeywordsCommunity change Climate adaption Ecological succession El Niño Species replacement
This work was supported by the Wildlife Conservation Society and supported by a number of organizations, including the Pew Charitable Trust, Tiffany Foundation, and the Western Indian Ocean Marine Science for Management Program. Clearance to do research in Kenya was provided by Kenya’s Office of Science and Technology and in the parks by Kenya Wildlife Services. Many people assisted with the monitoring including R. Arthur, E. Darling, C. Hicks, R. Kiambo, A. T. Kamukuru, B. Kaunda-Arara, J. Kawaka, R. Machaku, H. Machano Ali, S. Mangi, J. Maina, J. Mariara, R. Moothien-Pillay, J. Mutere, N. A. Muthiga, S. Mwacheriya, J. Ndagala, J. Omukoto, and M. J. Rodrigues.
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