Detecting Indicator Taxa Associated with Benthic Organic Enrichment Using Different Video Camera Orientations

Abstract

Sutherland, T.F.; Sterling, A.M.; Shaw, K.L.; Blasco, N.N.J., and Bradford, M.J., 2019. Detecting indicator taxa associated with benthic organic enrichment using different video camera orientations. Journal of Coastal Research, 35(2), 467–479. Coconut Creek (Florida), ISSN 0749-0208.Two video cameras mounted on a remotely operated vehicle (ROV) were used to generate paired forward-facing (FF) and downward-facing (DF) observations of benthic epifauna along 10 single transects at eight marine finfish aquaculture sites in British Columbia, Canada. The abundance of mat-forming primary indicators of organic enrichment, such as sulphide-oxidizing bacteria and opportunistic polychaete complexes (OPC), were quantified through percentage coverage estimates. Coverage estimates for sulphide-oxidizing bacteria were strongly correlated between the FF and DF orientations across all substrate types. The occurrence of OPC was limited to a single mixed-substrate site, which provided the strongest FF vs. DF relationship within this study. In contrast to sulphide-oxidizing bacteria, epifaunal abundance (count data) revealed strong relationships between camera orientations for fine sediments and mixed sediments and a weaker relationship observed for vertical rock wall environments. Similar observations occurred for estimates of both sessile (dominated by plumose anemones) and motile taxa guilds comprising the total epifaunal community. Weaker relationships associated with the rock wall substrate are likely due to alternating blackout periods experienced by each camera orientation as the ROV passes vertical or ledge habitat zones. Overall, a combination of FF and DF video orientations may provide more robust abundance estimates for settings that are characterized by various substrate grades and structural and/or mat-forming taxa.