Recent dynamics on turbid-water corals reefs following the 2010 mass bleaching event in Tobago

Abstract

We detail the benthic compositon of the turbid-water coral reefs of Tobago in 2016 and examine the influence of mass coral bleaching and hydro-geomorphic setting (sheltereted vs. wave-exposed) on benthic community dynamics against the 2007 baseline. In the current assessment mean hard coral cover was 14.83% ± 0.85, which ranged from 2% to 37% with few sites exceeding 20%. Mean macroalgal cover was low (6.04% ± 0.61) with most sites experiencing less than 8% macroalgal cover. Differences in benthic cover between sheltered and wave-exposed settings were mainly driven by contrasts in proportions of sponge, macroalgae and Orbicella faveolata corals. Linear mixed-effects modelling suggests stability in hard coral cover and decline in macroalgal cover across sites against the 2007 baseline. Significant spatio-temporal interactions were observed for soft coral and CTB (crustose coralline algae, turf algae and bare substrate). Overall, hard coral cover appears to have declined at some sites and macroalgal cover to have increased at other, but there is no evidence of widespread regime shift. While the hydro-geomorphic setting had a significant but weak effect (R > 0.3) on observed spatial and temporal patterns, our findings suggest that sheltered settings were less predisposed to macroalgal overgrowth compared to wave-exposed areas. In the era of climate change, targeted management should focus on strategies that mitigate macroalgal overgrowth, promote hard coral stability (or resilience) while preventing further loss.