Comparison of the Far Eastern seas and the North Pacific Ocean in terms of species diversity, its components, and other integral characteristics of net zooplankton in the epipelagial zone

Abstract: As a result of large-scale plankton surveys carried out by TINRO using the Juday net with a 0.1 m2 opening in 1984-2013, comparisons can be made on the Chukchi and Bering seas, the Sea of Okhotsk, the Japan/East Sea and the adjacent Pacific Ocean in terms of species diversity H (binary digits/specimen), species richness S (number of species), species evenness by number of individuals J (unit share), total population density in abundance units N (thousand specimen/m3) and biomass M (g/m3), and average individual weight of animal W (mg/specimen). The Pacific waters are first in terms of S, but lag behind in terms of N and J. W is higher than in the ocean only in the Bering Sea. H is lower than in the ocean only in the Chukchi Sea, and M is lower only in the Japan/East Sea. The Chukchi Sea is first in terms of plankton N and M, second in terms of J, third in terms of W, and last in terms of S and H. The Bering Sea is first in terms of W, second in terms of S, H and M, third in terms of N and last in terms of J. The Sea of Okhotsk is second in terms of W, last in terms of N and third in terms of all other indicators. The Japan/East Sea is first in terms of S, J, and H, second in terms of N, but last in terms of W and, as a consequence, in terms of M. It seems that when going from south to north plankton density and size increase, while its diversity and its components decrease. However, this trend has many exceptions: the latitudinal trend is broken by the Japan/East Sea in terms of N, the Sea of Okhotsk in terms of S and H, and the Chukchi Sea in terms of J and W.