State of the Arctic Marine Biodiversity Report: chapter 3.3: Benthos

Benthos chapter of the State of the Arctic Marine Biodiversity Report covering two Focal Ecosystem Components: megafauna, and macrofauna.

The seabed environment includes a great variety of physically diverse and biologically distinct habitats that, collectively, add to regional biodiversity of benthic fauna. Large spatial and temporal variation in community structure of benthic fauna is related to water depth (from shallow intertidal zones to the deep abyss), currents, temperature, food availability, irradiance, and type of substratum, ranging from hard and rocky, to soft, muddy floors (e.g., Gray 2002, Piepenburg 2005). Sea ice is an additional environmental driver that influences benthos, because it modifies hydrographic features, scours in shallow water, and affects primary production, amongst other effects (Sejr et al. 2009). Arctic benthic fauna act as long-term integrators of overlying water-column processes because of life spans on the order of years or decades (e.g., Sejr et al. 2002, Blicher et al. 2007). Although some benthic organisms are mobile, many remain relatively stationary on or in bottom sediments and their community patterns are thus directly affected by local hydrographic conditions and the export production regime from the overlying water column (Roy et al. 2014). Consequently, the distribution, abundance and biomass of benthic invertebrate species vary on multiple spatial scales. Benthic organisms are key components of remineralization processes (Blicher et al. 2009, Link et al. 2013 a, b) and also provide an important food source to higher trophic levels, such as many fishes, seabirds and marine mammals (Stirling 1997, Born et al. 2003, Bluhm and Gradinger 2008, Blicher et al. 2011). Despite their importance in Arctic food webs and other functional roles in the ecosystem, relatively little is known about diversity of some taxonomic groups and regions, distributional patterns, and the environmental factors that may drive benthic invertebrate community patterns across larger spatial extents, especially on a pan-Arctic scale.