Effectiveness of marine managed areas of central and southern Belize: Spatial variations in major community processes and the implications for local management success

Can reef decline be averted through local management effects? I initiated a Marine Protected Area monitoring project in five MPA's in Belize to examine the effects of management on ecological processes for each reef system. Dedicated sub-studies were conducted to examine spatial and/or management effects on fish biomass, herbivory, coral population structure, and coral disease. Only one of the three MPA's with active no-take zones showed significant enhancement of commercial fish biomass, even with use of a new and successful method to increase statistical power and removes habitat bias by employing non-target fish biomass as a covariate in the analysis. Parrotfishes directly decreased abundance of frondose fleshy macroalgae and indirectly increased coverage of crustose coralline algae, and possibly also the prostrate fleshy alga Lobophora variegata. There were significant differences in coral recruit density and species composition across study areas, with high recruitment in areas of large adult populations. Anticipated effects of substratum quality and herbivore assemblage on recruitment were upheld within individual study areas but not across study areas, suggesting that large-scale variation in recruitment are more likely due to local differences in larval supply or early post-settlement mortality. For coral diseases, I analyzed the incidence of multiple, diverse coral health conditions across study areas and conclude that there was a general increase in coral health proceeding north along the barrier reef system. I postulate that this pattern is due to spatial variation in water quality linked to anthropogenic activities in adjacent watersheds, causing increased physiological stress to corals and making them more susceptible to health problems. I conclude by synthesizing herbivory, coral recruitment, and coral health processes across the study areas, placing these into a general conceptual model of reef trajectory. This helps to explain spatial variation in the potential for local management of anthropogenic stress to slow or reverse the current trajectory of reef decline.