Figure 1.

(A) Photographs of M. arctica in sea water and broken ice surrounding the ice floes at sites Mel_2 and (B) Mel_3. (C) Microscopic photograph of a subsample of Mel_1 taken for the species identification of M. arctica (credit with permission: A. Kraberg, AWI, magnification: ×400). (D) Ice algae (black arrows) deposited on the seafloor at ∼2500 m depth in the Fram Strait, depicted by a time-lapse camera on 24/07/20 (credit with permission: F. Wenzhöfer, AWI). (E) Map of the study area and sampling sites in the Fram Strait; red arrows indicate water masses of the Atlantic inflow, and blue arrows depict cooler waters of polar origin (current arrows are inspired with permission by Macdonald et al.²¹).