Multivariate analysis of reef community structure in the Belize barrier reef complex

The Belize barrier reef complex includes approximately 250 km of barrier re ef and three off-shelf atolls up to 40 kin cast of the barrier reef. Multiv ariate analysis techniques are being tested for their ability to discrimina te patterns of geographical zonation in reef community structure. A stratif ied, haphazard video-based monitoring scheme has been established at 17 win dward fore-reef sites. This preliminary community classification and ordina tion provides a baseline description of reef communities and indicates a si gnificant difference (1) between atoll versus barrier reef sites, and (2) b etween southern, northern and central barrier reef sites, despite a relativ ely high degree of similarity. Two pairs of sites indicate there are signif icant differences in community structure between 'impacted' and 'non-impact ed' sites. In addition, the key taxa responsible for these differences (bas ed on the Bray-Curtis similarity matrix) were identified and include Agaric ia tenuifolia and macro algae. Most previous studies have examined stony co ral species in such analyses, Because non-coral biota are normally the majo r community components on Caribbean reefs, they should be included in multi variate analyses of reef communities. Reanalysis of these data using either major benthic substrate categories or only stony coral species produces le ss discriminating results and illustrates the importance of using a communi ty approach with as much taxonomic detail as possible. Understanding the un derlying similarities and differences in biological communities throughout this large reef area is the first step towards the goal of linking these pa tterns to environmental and management-linked influences.