Abstract

In 2010, coral reefs across the Caribbean suffered from a mass coral bleaching event. This study evaluates the recovery of scleractinian coral communities across three major reef systems in Tobago that differ in their exposure to sediment deposition as a result of different adjacent land use practices. At two sites of each of the three reef systems assessments were done on 1) adult colony population structure, in 2010, 2011 and 2013 to analyse temporal changes among coral populations, 2) density and composition of coral juveniles (< 5 cm in size) to characterise the levels of successful sexual recruitment, 3) sediment accumulation rates and composition to understand its potential impact on each reef. The study found that three years after the bleaching event, most of the adult coral population distributions became more positively skewed, due to an increase in smaller size colonies. By 2013, Siderastrea siderea and Agaricia spp population distributions differed significantly and their mean size had significantly declined among most reef sites. Juveniles were found in low density (5.41 ± 6.31/m2), especially at sites nearest to urban developed land, and were dominated by brooding genera; broadcasting genera like Montastrea and Diploria, which predominate in the assessed adult community, were rare. Sedimentation rates were below < 5 mg/cm2/day at all sites but one, and sediment grain size distribution profiles differed per reef system. Overall, we found that large size colonies are declining among most taxa and that Tobago‘s coral reefs are not relying on sexual reproduction for post-disturbance recovery.

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