Diatom distribution of surface sediment in the Bering Sea and Chukchi Sea

Abstract

Diatoms from surface sediment samples in the Bering and Chukchi seas were analyzed to reveal the distribution patternsand their relationship with the ocean environment. A low abundance was found to the north of the Arctic Sea Ice Minimum(ASIMin), indicating that diatom growth is strongly inhibited by perennial sea ice. Between the ASIMin and the Arctic Sea IceMaximum (ASIMax) which experiences seasonal sea ice, the sea ice related diatoms (mainly Fragilariopsis oceanica and Fragilariopsiscylindrus ) were dominant, thereby confirming that sea ice is an important influencing factor. The Chaetoceros restingspores were more abundant in the Chukchi Sea, which corresponds well with the active phytoplankton distribution in the watercolumn, and is possibly attributed to the stronger hydrodynamic conditions present in the Bering Sea. The abundances of Chaetoceros resting spores were the lowest on the northeast Bering Shelf, possibly because of lower water depth, stronger coastal currents,river influx, coarser particle sizes and stronger winds and bottom currents. The Arctic Diatom Group (dominated by B acterosirabathyomphala, Thalassiosira antarctica v. borealis and Thalassiosira antarctica resting spores) was more abundant in theBering Basin and the areas central of and to the north of Chukchi Plateau, while the Coastal Benthic Diatoms (including Paraliasulcata and Delphineis surirella ) were mainly found on the northeast Bering Shelf and nearby Cape Lisburne in the Chukchi Sea. Thalassiosira nordenskioeldii was found to be the most abundant around the Bering Strait, while Neodenticula seminae was onlyfound in the Bering Sea and mainly distributed in the Bering Basin, indicating its close correlation with the Pacific waters.