Fine-scale video observations of high-density crinoid (Heliometra glacialis) beds in the St. Anns Bank Marine Protected Area, Atlantic Canada

Anns Bank Marine Protected Area, occurrence records in this analysis represent presence/absence and density of a biogenic habitat-forming species in five drift-camera benthic imagery transects in the southeast corner of the MPA, off the coast of Cape Breton, Nova Scotia, Canada. Presence/absence and count data of the unstalked crinoid (Heliometra glacialis) were derived from the use of continuous high-definition video observations (approximately one observation every second using a 1Cam Mk6, SubC Imaging camera; n=8522).

Densities were estimated by dividing the crinoid counts by the field of view (calculated from lasers with 10-cm spacing). Crinoids were observed in ~44% of the area of the five transects (~4811 m2), forming dense beds along sloped features from 77-119-m depths, predominantly on cobble and pebble substrates, reaching densities of up to 139 ind. m-2.