Cryptic regime shift in benthic community structure on shallow reefs in St. John, US Virgin Islands

We evaluated whether long-Term change on fringing reefs (7-9 m depth) around St. John, U Virgin Islands, conformed to the 'coral reef crisis' involvin ongoing collapse of community structure. Annua photoquadrats at 6 sites were used to measur octocoral abundance (by genus) and the cover of scleractinian (by species), macroalgae, crustose corallin algae, algal turf, and bare space. Community structur changed between 1992 and 2014, but did not correspon to large changes in response to pulse disturbances octocoral abundance declined from 1992 t 2002, but increased to 2014, scleractinians remaine uncommon (∼4.5% cover), and macroalgae becam more abundant. Richness and diversity of octocoral and scleractinians increased following 2000, an together defined 2 communities characterized by distinc taxonomic assemblages and temporally segregate to 1992-2001 versus 2002-2014. Smoothe tem poral variation in community structure assessed a generic (Octocorallia) and species (Scleractinia) leve was associated most strongly with rainfall, and to lesser extent with hurricane intensity, thereby underscorin the roles of chronic disturbances in drivin gradual changes in community structure. Together these changes did not conform to the typical cora reef crisis construct, and instead summed to cryp tic regime change that has escaped attention b researchers focused on scleractinians and macroalgae.