Deep-water bamboo coral forests in a muddy Arctic environment

Abstract

Keratoisis is a genus of bamboo coral commonly reported in the northwest (NW) Atlantic as a result of fishing bycatch or by in situ observations. In 1999, a scientific trawl survey recovered fragments of Keratoisis sp. in southeast Baffin Bay (NW Atlantic), but colonies had never been seen in situ at this location until 2013, when a remotely operated vehicle (ROV) was used to survey this location. Here we report the presence of dense forests of Keratoisis sp. in a muddy environment at depths >900 m. Colonies were found as dense patches up to ~55 m long along the ROV track and were estimated to reach ~1 m in height. At this location, Keratoisis sp. appears to have branched root-like structures probably used for anchorage on mud. The majority of colonies were alive, but fragments of dead colonies were also observed, especially in the path of the 1999 bottom trawl tow. Based on visual observation, the dense stands of Keratoisis sp. in this environment seem to form structure and habitat for other invertebrates and fishes in an otherwise mainly muddy environment.