State of the Arctic Marine Biodiversity Report: chapter 3.1: Sea ice biota

Sea ice biota chapter of the State of the Arctic Marine Biodiversity Report covering four Focal Ecosystem Components: Bacteria and Archaea, microalgae and other protists, meiofauna and under-ice macrofauna.

The sea-ice related food web and biodiversity are critical components of the Arctic marine ecosystem. Higher trophic levels are directly or indirectly supported by over 2,000 species of small algae and animals that are associated with sea ice, but are often inconspicuous to the naked eye. These species inhabit a wide range of microhabitats inside the brine channel system, on top of the ice in melt ponds, immediately underneath the ice at the ice-water boundary and including extensive pressure ridges (Figure 3.1.1). The spatial distribution of sea ice biota (hereafter referred to as sympagic or ice biota, cf. Legendre et al. 1992) is shaped by dynamic properties of the sea ice. Spatial scales range from the micrometre dimension of the brine channel network to the metre scale that defines ice thickness and horizontal floe extent, to the hundreds of kilometre scale of ice drift patterns across the entire Arctic Ocean. The origin and age of sea ice are important factors which impact the resulting community composition of sea ice biota, with pronounced differences among biota and living conditions in annual landfast sea ice, offshore annual pack ice and multi-year pack ice (also called drift ice).