CHARACTERIZATION OF CORAL COMMUNITIES AT WAKE ATOLL IN THE REMOTE CENTRAL PACIFIC OCEAN

Abstract

Little published or unpublished information exists concerning the benthic community structure or coral fauna at Wake Atoll in the Central Pacific. Here, we apply multivariate statistical analyses to data acquired in 2005 from several complementary survey methods that operate at different scales of spatial and taxonomic resolution to characterize the coral communities in the fore-reef habitat, which is further stratified by geographic sector and depth zone. Both broad-scale towed-diver surveys and site-specific photoquadrat surveys revealed high dissimilarity in overall benthic composition between the northeast and southwest sectors. Coral cover in the northeast sector is more than 2.5 times greater than in the southwest sector; encrusting and massive growth forms dominate in the northeast sector while encrusting and digitate growth forms dominate in the southwest sector.  Coral cover and colony abundances are less dominated by a few key genera in the northeast than in the southwest sector, though the genera Montipora, Pocillopora , and Favia are the most numerically abundant taxa in both sectors. Octocorals account for more than 25% of the total coral cover in the northeast sector but less than 5% of the total coral cover in the southwest sector. The deep northeast stratum showed among the highest diversity of growth forms as well as the highest total coral cover, octocoral cover, and coralline algal cover. We provide a list of 101 anthozoan and hydrozoan corals observed at Wake Atoll during survey activities since the year 1979. Five scleractinian species at Wake are on the IUCN Red List of Threatened Species™. The 80 taxa with well-established species names contain components from the Mariana Islands, northern Marshall Islands, and Hawaiian Islands, but show the closest resemblance to the Mariana Islands. Our spatially widespread surveys that generate independent metrics of benthic cover and coral abundance collectively provide the most comprehensive description of coral communities at Wake Atoll produced to date and also provide an important record by which to monitor the response of this community to changing ocean conditions.