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Published in: Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions. Gerace Research Center, San Salvador, Bahamas, 2003.

Abstract

The plight of coral reefs throughout the Caribbean region has been widely reported by reef scientists. A variety of causes has lead to reefal decline, particularly in shallow waters. This study compares the responses of shallow-water reefs in Belize and the Bahamas to outbreaks of white­ band disease (WBD) and traces changes on these reefs to the early 2000s.

Prior to the mid-1980s, reef ridges of the Pelican Cays of Belize were constructed of luxu­ riant stands of Acropora cervicomis. As else­ where, this species suffered massive mortality in mid-1980s owing to WBD, and dead A. cervicor­ nis substrates were quickly colonized by Agaricia tenuifolia. Subsequently, A. tenuifolia on the reef ridges was severely affected by the intense El Nino-Southern Oscillation (ENSO)-related bleaching event of 1998. Our surveys showed that >90% of A. tenuifolia colonies died following bleaching. More recent survey data indicate that sponges are aggressively colonizing the coral sub­ strata.

In the early 1980s, Telephone Pole Reef on San Salvador Island, Bahamas, had numerous thickets of Acropora cervicomis along with large colonies of Montastraea annularis species com­ plex. By the mid-l 980s, virtually all A. cervicor­ nis colonies were dead, presumably from WBD. Following the demise of the A. cervicomis thick­ ets, an increase in Porites porites colonies quickly occurred. P. porites was opportunistic in coloniza­ tion and showed preference for A. cervicomis substrates. By the early 1990s, P. porites was a dominant coral on Telephone Pole Reef, with col­ ony sizes commonly greater than 1 min diameter. Reef surveys in 1998 and 2000 indicated signifi­ cant decline in the health of P. porites, and in early 2002 continued deterioration was noted, with virtually all larger colonies overgrown by fleshy green macroalgae and/or encrusted by coralline algae.

These two examples are similar in that both shallow-water reefs are in rapid transition to domination by non-coral groups that impede set­ tlement of coral larval recruits: sponges in Belize and macro- and coralline algae in the Bahamas.

Depending on how widespread similar transitions may be, the future of shallow-water coral reefs throughout the wider Caribbean is problematic. Turnover events such as these have been de­ scribed as unprecedented for coral reefs, and pa­ leontologists should examine the Cenozoic coral reef record in greater detail to explore these claims.

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