Document Type

Conference Proceeding

Publication Date


Publication Title

Proceedings of the Colloquium on Global Aspects of Coral Reefs: Health, Hazards and History


Two coral patch reefs on the leeward shelf of San Salvador Island have been studied with surveys in 1983-84 and 1992 to monitor their ecological health and short-term change. Snapshot Reef covers an area of 50 x 50m and is dominated by Montastrea annularis. The reef was mapped in detail to show the position and size of its coral heads and 64 of these heads were studied in detail. To describe the reef, measurements were made of the height of each head, percent live coral coverage, the dominant coral species, total number of coral species present, M. annularis morphotypes presents, and the relative occurrence of algae, sponges, octocorals, and dead coral surface. Several types of statistical analyses were performed, indicating a direct relationship between height and number of coral species and also between relative abundance of octocorals and number of coral species. An inverse relationship was observed between relative abundance of algae and amount of bare coral surface. There was a strong correlation between height in 1992 and a combination of percent living coral and number of coral species. An average increase in size of the coral heads of 13 cm from 1984 to 1992 was determined, and there were significant change in the percentage of live coral on the heads. The overall picture is one of a reef in at least a steady state condition. There also is a strong correlation between coral head height in 1992 and a combination of the number of coral species and relative abundance of algae. This relationship may provide a useful means of predicting the future "health" of a given coral head.

The nearby Telephone Pole Reef has been studied by comparisons of transects and photographs made i 1983 and 1992, and they reveal that significant recent change has occurred. In 1983, this reef consisted largely of M. annularis heads with dense thickets of Acropora cervicornis in its outer parts. Today the M. annularis heads remain seemingly unchanged, but virtually all of the A. cervicornis has died and collapsed to form layers that now are being covered by rapidly growing heads of Porites porites. These surveys have established a baseline for monitoring of the health and short-term change on both of these reefs in the future.


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