Project Summary for 2006-10A: Recruitment dynamics of gorgonian corals: Baseline recruitment and the effects of macro algal cover.
At sites throughout the Caribbean and on many Florida Keys coral reefs, gorgonians have become the numerically most abundant macro-invertebrate. Despite their abundance there is a paucity of information on the ecology and dynamics of gorgonians and it is unknown whether gorgonians have been adversely affected by the processes that have degraded reefs in Florida and throughout the Caribbean basin. Given their abundance on Florida Keys reefs and hardgrounds it is crucial to develop an understanding of the processes controlling gorgonian abundance and in particular to understand how gorgonians are affected by the massive increase in macroalgal cover that has occurred on many reefs. Recruitment, the settlement and survival of larvae, is a particularly crucial and sensitive step in these organisms' life cycle and a study of the recruitment rates of gorgonians can provide an index of the continued success of gorgonians on Florida Keys reefs and a harbinger of future change in gorgonian communities.
Given the traits of their larvae, gorgonian recruits should be sensitive to many of the same conditions that affect hard coral recruits, yet declines of gorgonians have not been reported. In the proposed research I will determine gorgonian recruitment rates and examine the interaction between gorgonian recruitment and survival and macroalgal cover. The research will be conducted at forereef sites at 8 and 18m depth on Pickels Reef in the Florida Keys. The sites will overlap and make use of quadrats that have been monitored for scleractinian recruitment and survival since 2002. The questions to be addressed are:
At each site a series of .5x.5m quadrats will be established which will either be left as controls or from which all macroalgae will be removed. In one set of quadrats all recruits will be removed and their identity determined with DNA markers which will be developed as part of the research. Recruits will be left in place in the other quadrats and their survival in the two treatments will be monitored. Gorgonian recruitment in quadrats that have been monitored for scleractinian settlement will be estimated from archived images of those quadrats.
The data will provide a measure of recruitment and the potential of the populations to sustain themselves, whether gorgonian recruitment is adversely affected by macroalgal cover and whether gorgonian recruitment has covaried with scleractinian recruitment. These data are crucial to understanding the status of gorgonians, the likelihood of their continued survival on Florida coral reefs, and their potential response to any amelioration of conditions on Florida coral reefs.
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