Warm Currents Shift Species Composition in the Sea of Okhotsk

Warm currents are redrawing the biological map of the Kuril Islands, shifting the species composition of the Okhotsk Sea. The Tsushima Current and its branch, the Soya Current, are pushing warmer waters toward the shores of Iturup and Kunashir, allowing southern species to move north.

Photo: Pravda.Ru by Mikhail Oleynikov is licensed under All rights reserved

A flock of small silverfish swims in clear water near the surface

Tropical tuna have appeared in the northern waters of Sakhalin, specifically in the Noglik district, while southern algae species are becoming staples of the Southern Kurils' flora.

As warm-water species expand, cold-water communities are receding. A September algological expedition to Kunashir found a decline in both the biomass and the total area of brown laminarian seaweed forests. Similar losses in kelp density were recorded on Moneron and the Commander Islands.

These seaweed forests serve as primary shelter and food for hundreds of marine organisms. Their degradation threatens to lower the overall biological productivity of the Okhotsk Sea by dismantling the base of its food chain.