Benthic Images from Stratified Random Site (StRS) Surveys in the Main Hawaiian Islands During the 2019 Bleaching Event

Data provided in his dataset are benthic habitat imagery that result from benthic photo-quadrat surveys conducted along transects at stratified random sites surveyed across the Main Hawaiian Islands during the 2019 bleaching event. The data were collected by the NOAA Ecosystem Sciences Division (ESD) during a multi-institutional effort by the Hawaii Coral Bleaching Collaborative (HCBC) to build a comprehensive dataset of the spatial extent and severity of bleaching in the Hawaiian Archipelago during the peak of the forecasted 2019 coral bleaching event. These photo-quadrat surveys were conducted during shore-based missions and at each site, rapid visual assessments were also conducted to provide information on live coral cover and the percentage and average severity that was bleached, as well as taxa-specific metrics (live cover and the percentage and severity that was bleached).

A stratified random sampling (StRS) design was employed to select random sites. The survey domain encompassed the majority of the mapped area of reef and hard bottom habitats in the 0-30 m depth range. The stratification scheme included island, reef zone, and depth in all regions, as well as habitat structure type in the Main Hawaiian Islands. Sampling effort was allocated based on strata area and sites were randomly located within strata. Sites were surveyed using photo-quadrats along transects to collect benthic imagery to ultimately produce estimates of relative abundance (percent cover), frequency of occurrence, benthic community taxonomic composition and relative generic richness.

The StRS design effectively reduces estimate variance through stratification using environmental covariates and by sampling more sites rather than sampling more transects at a site. Therefore, site-level estimates and site to site comparisons should be used with caution.

The benthic images can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.