Environmental data collected in the Fundy Ocean Research Centre for Energy (FORCE) lease area in Minas Passage, Bay of Fundy, during 2008-2009, included underwater video surveys and >2000 still photographs of the seafloor. The present study uses these materials and associated technical reports by Envirosphere Ltd to further examine the epibenthic fauna-substrate relationships for the purposes of quantifying baseline conditions prior to installation of in-stream tidal energy conversion infrastructure (cables, moorings and turbines) in the FORCE test area.
Computer image analysis and qualitative and quantitative classification techniques were used to characterize the benthic environment and to map the epibenthic macrofauna (for organisms >10 mm) of three FORCE berth sites and associated cable routes. Still frames taken from videographic surveys were processed using ImageJ software. Data recorded include presence/absence and percent cover of macrofaunal species, percent cover of substrate type (based on bedrock type and clast size) and depth below MLW. Commonly observed macrofauna from video stills include Halichondria panicea (yellow breadcrumb sponge), Asterias vulgaris (a variety of seastar), Henricia sanguinolenta (bloodstar), and Urticina felina (northern red anemone). H. panicea is the most abundant species observed in the FORCE lease area, with extensive sponge cover appearing in Berth A, an area of exposed basalt bedrock and the shallowest of the three berth areas.
The distribution patterns of the dominant epibenthic fauna in the FORCE test area were mapped as an aid to FORCE project developers and environmental regulators. A Classification and Regression Tree (CART) statistical analysis was used to determine the environmental factors most influential in determining species distribution. CART analyses showed that the most important factor controlling H. panicea distribution was substrate type (volcanic or sedimentary bedrock), followed by water depth.
Given the observed low biodiversity of macrofauna and the prevalence of encrusting yellow breadcrumb sponge, the risk of negative impact on epibenthic productivity and biodiversity, following any installation of subsea infrastructure at FORC, is low.