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Prevalence (% affected corals)

4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Bleach DSD

WS

YBD

Cabb

Cdel

Cliona Damsel

FB

Fig. 56. Stressors affecting reef building corals. The categories included bleaching (Bleach; colonies that were pale, mottled or completely bleached), diseases [dark spots disease (DSD), white plague (WS), yellow band disease (YBD)], Coral eating snails (Cabb); sponge overgrowth by Cliona delitrix (Cdel) or the brown Cliona (Cliona), Stegastes planifrons algal lawns (damsel), and fish bites (FB). Data are pooled for all species.

B. Algae and herbivory Most reefs around the Caribbean have seen a dramatic increase in the cover and biomass of fleshy macroalgae. This began after the die-off of Diadema in 1982-1983, and proliferated over the last two decades as coral cover declined. In many cases, this has been at the expense of corals, through direct competition and overgrowth and by reducing substrate quality and inhibiting recruitment. On Pedro Bank, there was relatively little turf algae, moderate cover of CCA, and only moderate cover of fleshy macroalgae and calcareous macroalgae. At all sites, macroalgal cover was greater than coral cover. However, in eight of the 19 sites (PB-03, 04, 06, 07, 09, 14, 15, 20) macroalgal cover was relatively low (<15% cover). Most algae occurred at the bases of boulders and coral heads and around the margins of corals, and open substrates were largely devoid of fleshy macroalgae. Six of these sites also had a high biomass of herbivorous fish. Nevertheless, there was no significant relationship between herbivore biomass and algal biomass (R2 =0.0004, p=0.79), as other sites with high algal cover also had high biomass of herbivores. It is important to note that, although the biomass of herbivores was fairly high, the size of these fish was unusually small (most < 15 cm) and large excavators were rare. Due to their small size, and their feeding behavior (most were browsers and scrapers) is seems that they would be unlikely to consume substantial amounts of macroalgae. Furthermore, Diadema were extremely rare, occurring only at the two sites with the highest macroalgal biomass overall.  

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Profile for Khaled bin Sultan Living Oceans Foundation

Global Reef Expedition Final Report: Jamaica  

In March of 2012, scientists on the Global Reef Expedition set out to assess the community structure, health, and resilience of corals and c...

Global Reef Expedition Final Report: Jamaica  

In March of 2012, scientists on the Global Reef Expedition set out to assess the community structure, health, and resilience of corals and c...

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