region with more gradual stratification (100-200m). The Bering Sea shelf break (a zone where the shallower continental shelf drops off into the North Aleutians Basin) is the dominant driver of primary productivity in the Bering Sea –– upwelling brings nutrients from the cold waters of the Aleutian basin to mix in shallow waters. This area is called home to many ecologically important species, including the snow crab. To assess trends and impacts of the warming climate in the Bering Sea, a recent study created a regional model of both physical and biological elements of the Bering Sea using three global climate simulations from the Intergovernmental Panel on Climate Change Fourth Assessment. This model detected overall trends of warmer temperatures and a retreat of sea ice in the southeastern Bering Sea. Primary drivers of these higher water column temperatures include increasing air temperature and northward wind stress. Warming trends on the outer Bering Sea shelf are concerning for a variety of reasons, one of which being that they may lead to decreased production of large crustacean zooplankton. On a broader spatial scale, sea surface temperatures (SSTs) that marked the start of summer in the North Pacific now come 11 days earlier and SSTs that marked the end of summer now come around 27 days later. Additionally, summers are on average 1.5 °C warmer and winters are on average 0.5 °C warmer. Historically, the Bering Sea continental shelf maintains between 40%-100% ice cover at its annual winter maximum. In 2018, the maximum sea ice cover was only 47% of the 1979-2016 mean seasonal maximum extent. Southeastward advection of melting sea ice contributes to the latitudinal salinity gradient of the Bering Sea, so when sea ice formation is reduced, the salinity gradient is altered. Though these don’t seem like significant changes, the inherent thermal conductivity of water (its ability to absorb heat) means that small changes like these are a big deal for marine organisms like the snow crab. It is yet unknown whether the Bering Sea snow crab population will recover, but scientists and policymakers will need to act quickly if improvement is to occur. References External links Alaska Department of Fish and Game: Tanner Crab Pacific Seafood Group - Snow Crab Majoidea Edible crustaceans Decapod genera Taxa named by Henrik Nikolai Krøyer