Observations of a living macroalga at 166m depth in a high Arctic fjord

Still photos of the seafloor in Raudfjorden, Spitsbergen, recorded in 2011, showed an abundant macroalga at a depth of 166 m. The macroalga was observed attached to stones of varying size and streaming in the bottom current, which would imply that the alga was alive and growing in situ. The alga likely experiences very low-light conditions, as it is present in a turbid fjord influenced by glacial sedimentation. Arctic macroalgae are often adapted to low-light conditions, but to the authors’ knowledge, the present report is the deepest record of living macroalgae in the high Arctic.