Geomorphic Features And Benthos In A Deep Glacial Trough In Atlantic Canada

The Laurentian Channel is a deep glacial trough located in Atlantic Canada, extending from the St. Lawrence Estuary to the shelf edge between Nova Scotia and Newfoundland. The outer Laurentian Channel close to its entrance at the shelf edge has been designated as an Area of Interest for the establishment of a Marine Protected Area, but baseline information was lacking. Here, a benthoscape map of the outer Laurentian Channel was generated using geomorphic features mapped using multibeam sonar (density of iceberg scours and pockmarks/iceberg pits, depth and slope) and ground truthed with surficial geology samples and underwater imagery. Individual surrogates and mapped patterns were compared to faunal patterns (infauna and epifauna) derived from the ground truthing. Water depth was the main predictor of infauna abundance and richness, while both depth and density of pockmarks/iceberg pits influenced community composition. Some benthoscape classes had close associations with distinct infauna, but diffuse patterns were mostly observed. Epifauna-namely sea pens-were most abundant at the confluence of multiple benthoscape classes.