Eddy-Like Features Near St. Matthew Island, Eastern Bering Sea Shelf: Observations From The Oculus Coastal Glider

The eastern Bering Sea Shelf is characterized by high biological productivity, seasonal sea ice, and commercially important fisheries. Enhanced productivity is often associated with small-scale oceanographic features. Our objective was to use an autonomous underwater vehicle to examine features typically missed by similar to 20-km spaced shipboard sampling. A coastal glider (Oculus) sampled similar to 3 dives hr(-1) with horizontal spacing of similar to 300 m per dive in August/September 2017. In the north-south transition zone near St. Matthew Island, the glider sampled four eddy-like features associated with weaker vertical stratification. These features had diameters of 15-20 km and were associated with higher surface chlorophyll. Shipboard data collected in the same region approximately a month later showed that a similar feature was associated with high concentrations of small copepods. Incorporating higher resolution sampling available with gliders into the Bering Sea observing network will improve our understanding of ecosystem response to patchiness in the system.Plain Language Summary The eastern Bering Sea Shelf is home to an important and well-studied ecosystem, including high biological productivity, endangered marine mammals, and valuable fisheries. Sites of enhanced biological productivity are often associated with small-scale oceanographic features difficult to observe using shipboard observations. The objective of this study was to use an autonomous underwater vehicle, a glider, to examine such features in the Bering Sea. A coastal glider (Oculus) sampled four eddy-like features with diameters of 15-20 km near St. Matthew Island in August/September 2017. The features were associated with higher surface chlorophyll (phytoplankton) surrounding the island and high concentrations of small copepods and may be important in providing food for the seabirds and marine mammals residing on and around St. Matthew Island. Incorporating gliders into the Bering Sea observing network will improve our understanding of ecosystem response to patchiness in the system.