National Coral Reef Monitoring Program: Benthic cover derived from analysis of images collected during stratified random surveys (StRS) of the Hawaiian Archipelago

The benthic cover data in this collection result from the analysis of images produced by benthic photo-quadrat surveys. These surveys were conducted along transects at stratified random sites across the Hawaiian Archipelago as a part of the ongoing National Coral Reef Monitoring Program (NCRMP). Benthic cover data and the associated images are both included in this collection.

A stratified random sampling (StRS) design was employed to survey the coral reef ecosystems throughout the region. 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 assigned within strata. Sites were surveyed using photo-quadrats along transects. The imagery were then analyzed to produce estimates of relative abundance (percent cover), frequency of occurrence, benthic community taxonomic composition, and relative generic richness.

Benthic habitat imagery were quantitatively analyzed using Coral Point Count with Excel extensions (CPCe; Kohler and Gill, 2006) software from 2010 to 2014 and a web-based annotation tool called CoralNet (Beijbom et al. 2015) starting in 2015. In general, images were analyzed to produce three functional group levels of benthic cover: Tier 1 (e.g., hard coral, soft coral, macroalgae, turf algae, etc.), Tier 2 (e.g., Hard Coral = massive, branching, foliose, encrusting, etc.; Macroalgae = upright macroalgae, encrusting macroalgae, bluegreen macroalgae, and Halimeda, etc.), and Tier 3 (e.g., Hard Coral = Astreopora sp, Favia sp, Pocillopora, etc.; Macroalgae = Caulerpa sp, Dictyosphaeria sp, Padina sp, etc.).