Abstract:
Ecological monitoring is an essential precursor when developing comprehensive management plans for marine protected areas and their surrounding habitats. In small island nations that lack historical baseline datasets, ongoing monitoring programmes, and associated threat assessments, paper park scenarios are common, with marine protected areas usually existing under little or no effective management. This is often due to limited resources and other constraints. To address this, a ranking tool was developed and analysed that assigned a relative health index (RHI) value to each study site, using ten, five and three ecological variables, and compared with best professional judgement (BPJ) scores. These methods were evaluated against a full suite of ecological variables to assess RHI or BPJ result validity. Although a close relationship was found between the ten variable model and BPJ, it was concluded that neither correctly predicted overall ecosystem health due to conflicting variables and the inherently complex nature of coral reef ecosystems. Results using five non-conflicting variables gave the closest match to conclusions drawn when looking at ecosystem function as a whole. The five variables used for this model were: coral percentage cover; macroalgae percentage cover; total fish species count; total fish abundance count; and commercially/ecologically important fish size. It was concluded that the five variable version of the RHI tool was effective at ranking overall ecological health of a study site, and that these ranks could be used to produce habitat health gradient maps. In the absence of a full suite of ecological data, these maps will allow informed management decisions to be made when designating conservation areas and protection levels, and when combined with BPJ rapid assessments will allow fast and reliable quantitative surveys to be conducted. If resources allow, it is not recommended that the RHI tool should replace full ecological monitoring as this information is essential when forming a robust baseline for future temporal change analysis. In the case of Anguilla, due to potential regional stressors effecting nutrient levels and other water quality variables, it is suggested that sites with the highest RHI rank should be afforded the highest level of protection. This will serve to preserve relic populations and potentially allow local mitigation measures to maintain these populations until a time when regional stressors begin to be effectively addressed by multinational/international policy agreements.
