24 February, 2000
09:00-10:35 Session IIIa Dynamics of Coastal Ecosystem
The effects of anthropogenic disturbance on reproduction and recruitment of corals
Robert H. Richmond and Sarah Leota
Marine Laboratory, University of Guam, UOG Station Mangilao
Guam 96923, U.S.A.
Coral reefs persist over time through the dual processes of reproduction and recruitment. The majority of reef building corals spawn their gametes into the water column, where larval development and dispersal occur. Fertilization usually depends on out-crossing among individuals, and hence, is affected by population density. Subsequently, competent larvae must find appropriate substrata upon which to settle and metamorphose. Studies of mass-spawning scleractinian corals have identified chemically sensitive links responsible for successful reproduction and recruitment of corals. These include reproductive synchronization among conspecifics, egg-sperm interactions, embryological development, metamorphic induction and acquisition of symbiotic algae. Coastal pollution from runoff has been demonstrated to result in reproductive failure in corals through inhibition of fertilization and subsequent development of planula larvae. Certain chemicals including an organophosphate pesticide and a petroleum by-product have been found to inhibit recruitment of coral larvae. During the past five years, elevated sea water temperatures associated with changes in global climate patterns have been observed to cause outright mortality of corals over large areas. The ability of these coral reefs to recover is greatly affected by ambient water quality, substratum quality and densities of corals within populations capable of producing larvae that may recruit to a given site. The synergisms of large scale (global) disturbances coupled with reductions in localize water and substratum quality indicate efforts at coral reef protection must be made at both the international and local levels to be effective.
