Coral Bleaching & Recovery Observations using Structure-from-Motion (SfM) Models from Main Hawaiian Islands Fixed Sites Surveyed from 2019 to 2021

Coral adult demographic data described in this dataset are derived from the GIS analysis of benthic photomosaic imagery. This data includes coral species identification, bleaching extent and severity, colony diameter, perimeter, and planar size. The source imagery was collected using a Structure from Motion (SfM) approach during in-water surveys conducted by divers and is documented and described separately. The data was collected by the NOAA Pacific Islands Fisheries Science Center (PIFSC) Ecosystem Sciences Division (ESD; formerly the Coral Reef Ecosystem Division) and [on Hawaii Island] in partnership with State of Hawaii Department of Land and Natural Resources (DLNR), Division of Aquatic Resources (DAR) during the 2019 bleaching event in the Main Hawaiian Islands, and in subsequent years (2020, 2021) to assess recovery. The SfM surveys were conducted at fixed sites ranging in depth from 18-52'. Sites were photographed using underwater cameras for later processing using one of two SfM approaches: using a spiral swim pattern (where divers take images continuously in a circular pattern covering a circle of 12m diameter), or within a defined box where divers swam back and forth to cover a 10 x 10m area. The photographs were processed using Agisoft Metashape software to generate orthomosaic images that were analyzed in ArcGIS for adult coral colony demographic metrics. Data was collected for each site within at least 10 randomly generated 0.49m2 quadrats. Additional quadrats were analyzed if necessary until the sample sizes per species of interest were met. If a species had very low density at a given site (< 10 patches recorded within the first 10 quadrats), it was dropped from further observations. However, the data for these patches remains in the raw data in order to provide presence/absence data. Therefore, data should be carefully analyzed to ensure accurate species density calculations are done. Two datasets are provided: an annotations file which provides coral demographic information of 6 target species at 12 fixed sites across 3 years, as well as a site metadata file which describes the site and surveys which were used to generate models for which annotation data was derived.

Six species were assessed: Montipora capitata (MCAP), Montipora patula (MPAT), Porites lichen (PLIC), Porites lobata (PLOB), Porites lutea (PLUT), and Pocillopora meandrina (PMEA). Annotations included coral species identification, maximum diameter measurement, planar area measurement, morphology, and, for sites surveyed in 2019, bleaching extent and bleaching severity. Each coral was annotated at the patch level, and patches composing individual colonies, also known as genets, were assigned a unique genet ID number. The same coral patches were tracked over each time point, unless mortality of a coral patch occurred.

Note an update in methodology: The data was collected in two stages. During the first stage of data collection that was completed in 2021, for each coral patch, (>= 5cm in diameter), maximum diameter, ID (to lowest taxonomic level), morphology, bleaching extent (% of the patch with reduced pigmentation), and bleaching severity (1-3 from least to most severe) were recorded. In 2023 the methodology was updated for the second stage of data collection; the updated dataset includes measures of planar area and a "genet" (colony) identification column. The 2023 dataset was also collected following an update to the model process methodology (see Lineage). Users should refer to the most updated dataset published in 2023.