DOI: 10.25921/vptp-p636
title: Benthic Cover Derived from Analysis of Benthic Images Collected from the NOAA R/V Manta in the Flower Garden Banks National Marine Sanctuary from 2022-08-25 to 2022-09-02 (NCEI Accession 0290327)

description: Transects were run alongside NCRMP’s LPI transects at grid-based stratified random sites on the EFGB and WFGB coral caps. The transect sites were chosen by NCRMP using their Spatial Framework Protocols (NOAA NCCOS, 2018). The selection design ensures proportional allocation of survey sites based on hard bottom habitat types (low relief and high relief) and geography (EFGB and WFGB) up to a maximum depth of 30 m. Details of the sample frame protocol, methods, and definitions of the specific habitat types can be found in the Spatial Framework Protocols (NOAA NCCOS, 2018).

Mean percent benthic cover from random transect images were analyzed using Coral Point Count (CPCe) version 4.1 with a 510-point overlay randomly distributed among all images within a transect (30 spatially random points per image) (Aronson et al. 1994; Kohler and Gill 2006). Organisms positioned beneath each random point were identified to the lowest possible taxonomic level, and cover was categorized into seven groups: 1) coral, 2) sponges (including encrusting sponges), 3) CCA, 4) macroalgae (algae longer than approximately 3 mm and thick algal turfs covering underlying substrate), 5) colonizable substrate (including fine turf algae, rubble, and bare rock) (Aronson and Precht 2000; Aronson et al. 2005), 6) sand, and 7) an “other” category (biotic components such as sea urchins, ascidians, fish, serpulids, and unknown species). Additional features (photostation tags, tape measures, scientific equipment) and points with no data (shadows) were excluded from the analysis. Points on corals that could not be differentiated because of camera angle or camera distortion were labeled as “unidentified coral.” Coral colonies that could not be identified to the species level were labeled as their genus. Point count analysis was applied on photos within a transect and mean percent cover for all groups was determined by averaging all transects. Results are presented as mean percent cover ± standard error (SE).

Incidences of coral bleaching, paling, concentrated and isolated fish biting, and mortality were also recorded as “notes” in CPCe, providing additional data for each random point. Any point that landed on a portion of coral that was white in color was characterized as “bleached.” Any point that landed on coral that was pale relative to what is considered “normal” for the species was characterized as “paling” (AGRRA 2012). If the colony displayed some bleaching or paling, but the point landed on a healthy area of the organism, the point was “healthy” and no bleaching or paling was noted in CPCe. To classify fish biting, any point that landed where fish biting occurred on a coral head more than once was classified as concentrated fish biting, and any point where there was only one occurrence of fish biting was classified as isolated fish biting. Mortality included any point on recently dead coral (exposed bare skeleton) with little to no algae growth that could still be identified to the species level.

Consistency for photographic random transect methods was ensured by using multiple, scientific divers all trained on the same camera systems for correct camera operation. Camera settings and equipment were standardized so that consistent transect images were taken annually, and equipment checklists were provided in the field to ensure divers had all equipment and were confident with tasks assigned. Random transect photographs were reviewed promptly after images were taken, in the field, to ensure the quality was sufficient for analysis. After all benthic components were identified in CPCe files, quality assurance/quality control (QA/QC) consisted of an independent review by a separate, trained researcher, different from the CPCe analyzer, to ensure all identified points from the random transect photographs were accurate. Any mistakes were corrected before percent cover analysis was completed.