Photographic Evidence of Temporal and Spatial Variation in Hardbottom Habitat and Associated Biota of the Southeastern U.S. Atlantic Continental Shelf
Glasgow, Dawn M.
This study was designed to develop a standardized habitat characterization scheme to classify benthic habitats in the southeastern U.S. Atlantic continental shelf. For integration with other classification schemes, this scheme incorporates current federal classification standards with modifications based on information derived from digital images taken with chevron trap-mounted cameras during the Marine Resources Monitoring, Assessment and Prediction program (MARMAP) 2009 fish trapping survey. Classifications were based on dominant geologic (e.g. surface substrate, morphology and relief) and biotic components (e.g. biota, growth patterns, and percent cover) that could most accurately be determined from images. The data were used to create habitat location maps with ArcGIS. Two examples were provided for utilizing the scheme to: (1) examine changes in benthic habitats over time; and (2) observe species interactions with specific habitat components. Mean percent biotic cover was used to detect changes in benthic habitat in areas representing three depth zones (Charleston inshore, mid, and outer shelf) where repetitive sampling occurred between 1990-1993 and 2006-2009. A statistically significant change in mean percent cover over time was detected in the Charleston inshore habitat only. To identify species and habitat component interactions, associations between the presence of invasive Indo-Pacific lionfish (Pterois spp.), mean percent cover, and vertical relief were examined. Categorical data analysis showed a statistically significant association between lionfish and areas with vertical relief. Also, a baseline catch per unit effort (CPUE = Sigma lionfish observed in each collection / Sigma trap camera collections) was calculated for all lionfish present in all image collections (CPUE = 0.08); per shelf depth zone (inner shelf = 0, mid shelf = 0.01, outer shelf = 0.23, and shelf break = 0); and per level of vertical relief (none = 0.03, low-moderate = 0.20, and moderate-high = 0.27), providing one of the first estimates of relative abundance of lionfish in the region. This thesis provides baseline information to assist fisheries managers in utilizing trap cameras and GIS to move towards a habitat characterization standard. The data can be used as a tool to observe spatial patterns, to assess trends and relationships in habitats and associated faunal assemblages, to aid in the identification of essential fish habitats, and to assist managers with marine spatial planning decisions.
Continental shelf -- Research -- Atlantic Coast (South Atlantic States); Benthos -- Habitat -- Atlantic Coast (South Atlantic States)