The summer migration of Pacific zooplankton follows the temperature and salinity of Bering Sea/Anadyr Water in the Chukchi Sea

Abstract

The Bering Strait is the only gateway to the Arctic Chukchi Sea from the Pacific Ocean and is a major route to the influx of Pacific water. The recent oceanographic changes, such as rising water temperatures and shifting sea ice cover, have resulted in sub-polarization of zooplankton communities from the Arctic boundary. We collected zooplankton at 13 stations in the Chukchi Sea and Bering Strait in 2014-16. In addition, the mooring systems installed at the Bering Strait were analyzed to obtain water temperature and salinity data for the corresponding period. As a result, the abundance of Pacific zooplankton species (Eucalanus bungii, Metrida pacifica, and Neocalanus spp.) was high in 2015, and water temperature and salinity were also high. In particular, water mass analysis showed that the temperature of Bering Summer Water (BSW) was high. On the other hand, Pacific species were rarely found in 2014 and 2016, and water temperature and salinity were relatively low. In conclusion, the Pacific species introduced into the Chukchi Sea were known to flow along the BSW, but the Pacific species showed high abundance only in the relatively high temperature (> 3 °C) of the BSW.