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The Reef Systems Of Tela And Utila

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Despite their proximity, the reef systems of Tela and Utila differed dramatically in D. antillarum population sizes, indicating that the population in Tela had recovered significantly post-mortality compared to Utila, where the population was still being supressed. D. antillarum in Utila also had a notably smaller average test size compared to Tela, likely due to a larger juvenile urchin population. Juveniles are less effective at grazing down algae populations and display significantly greater preference over the genera of algae they consume. In areas highly populated by juveniles, this would allow domination of certain fleshy brown genera such as Dictyota whilst species of the Caulerpa genus are grazed to a more regular coverage (Rivera and Turner, 2009). On Tela, individuals were more likely to reach maturity and grow larger; implying that on Utila there was a presence of ecological barriers limiting survival to maturity, which were not present on Tela. The rate of herbivory in each area highlights the importance of D. antillarum as a keystone species, as the Utilan reef showed clear signs of deterioration in health due to the dominance of fleshy-brown macroalgae (48.6%) and low coverage of scleractinian coral (19.4%) compared to Tela. The Tela reef showed a 68.3% dominance of scleractinian coral and significantly lower fleshy brow macro-algae coverage at 13.7%. This was particularly notable for a region with an average reported coral cover of <10% (Gardner et al., 2003).
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