Title

Disturbance ecology of the Caribbean coral Acropora palmata

Date of Award

1997

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Marine Biology and Fisheries

First Committee Member

Mark A. Harwell, Committee Chair

Abstract

Physical disturbance is an integral part of the life history of corals such as Acropora palmata that are found in the exposed areas of reefs. Elkhorn coral has evolved characteristics that enable this species to survive and even benefit from periodic fragmentation under certain conditions. Here, I document the effects of physical disturbance caused by storms at different scales ranging from individual elkhorn colonies to whole populations.Elkhorn populations are very susceptible to physical disturbance, and the survivorship and propagation of this species is closely tied to its recovery capabilities after storms. Several benefits of fragmentation and asexual recruitment were determined here for A. palmata: high propagation and colonization potential, high competitive advantage, increase in abundance, and year-round reproduction. However, significant costs were also associated with this process: tissue loss, decreased growth rates, increased susceptibility, and loss of sexual reproduction. The long-term effects of fragmentation on A. palmata populations will depend on the balance between these benefits and costs.The stage-based simulation model developed for elkhorn coral performed well under different disturbance scenarios, providing a useful tool to predict the outcome of storms on elkhorn populations. The model showed that when sexual recruitment is limited, storm fragmentation followed by fragment survivorship and growth may be the only mechanism available for A. palmata to propagate and increase in abundance.Storm frequency can also affect elkhorn coral survivorship. When storms occur at 15-year intervals, a slow increase in the abundance of colonies can take place. When storm frequency increases to 5 years, the abundance of colonies can increase five-fold after 10 storms. In contrast, as storm frequency increases further (one storm every 2 years) there can be a steady decline in the abundance of colonies.Lastly, the changes in live coral cover and reef topographical complexity caused by intense storms can also affect the diverse fauna associated with elkhorn coral. A reduction in topographical complexity can result in a decrease in the abundance and diversity of reef fishes, and the loss of coral cover can affect the abundance and distribution of coral-associated macro-invertebrates.

Keywords

Biology, Ecology; Biology, Oceanography

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9824523