Utilization of Nutrients Entering Through the Bering Strait to the SouthwesternChukchi Sea with the Example of Mineral Phosphorus

Spatial variations of nutrients along the northwestward stream from Bering Sea to Chukchi Sea are considered for dissolved inorganic phosphorus (DIP) on the data of two surveys conducted in early September of 2010 and 2020. The waters of Bering Sea origin have higher DIP than the waters of Chukchi Sea, but in the upper layer gradually loose phosphorus because of both mixing with local waters and consumption for photosynthesis. In the subsurface layer, the DIP decreasing is prevented by its recycling from destructed organics. The fluxes of phosphorus are estimated separately using the balance model with TS-analysis, previously used in estuarine studies. Successive utilization of DIP along the stream is traced, that forms in the Chukchi Sea two zones of high productivity divided by wide low-productive zone. The nutrients from the upper layer are utilized within the southwestern Chukchi Sea providing primary production 0.1–0.2 gC/m3day, but the main stock of allochtonous nutrients from the subsurface layer is utilized further downstream (at Wrangel Is. or in the northern Chukchi Sea) and provides the production of 0.3–0.4 gC/m3day. Localization of the high-productive zones is determined by density stratification that possibly depends on the stream strength: the stronger advection through Bering Strait – the further from the strait both zones are located. Recent tendency of the stream strengthening tends to remove the zones of utilization the nutrients of Pacific origin out of the southwestern Chukchi Sea.