Fine-scale observations of high density Heliometra glacialis (Crinoidea) beds from five near-seafloor imagery transects from a two-year survey in the St. Anns Bank Marine Protected Area, Atlantic Canada

A derivative of DFO's benthic imagery surveys for the Marine Conservation Targets Program in the St. Anns Bank Marine Protected Area (https://open.canada.ca/data/en/dataset/2a55e2b4-cbb6-4fea-b17e-a16f5e99e68f), occurrence records in this analysis represent presence/absence and density of a biogenic habitat-forming species in five drift-camera 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 high-resolution Nikon D850 still images (n=428, see link to parent record for more descriptive survey information and complete imagery dataset) and 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). Substrates were reported for each video observation, documenting the dominant substrate (>50% cover) according to a modified Wentworth scale (i.e., sand, gravel, pebble, cobble, boulder, bedrock; Wentworth 1922). 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 59 ind. m-2 and 139 ind. m-2 in the digital still images and video observations, respectively.

Cite this data as: Lawton P, Teed L. Fine-scale observations of high density Heliometra glacialis (Crinoidea) beds from five near-seafloor imagery transects from a two-year survey in the St. Anns Bank Marine Protected Area, Atlantic Canada. Published March 2026. Coastal Ecosystems Science Division, Fisheries and Oceans Canada, St. Andrews, N.B.

References:

- Wentworth, C.K. 1922. A scale of grade and class terms for clastic sediments. The Journal of Geology 30(5): 377-392.