caa a22 4500 60545535X CHVBK 20210128100212.0 cr unu---uuuuu 210128e20150601xx s 000 0 eng 10.1007/s10872-015-0287-3 doi (NATIONALLICENCE)springer-10.1007/s10872-015-0287-3 Vertical segregation and population structure of ontogenetically migrating copepods Neocalanus cristatus, N. flemingeri, N. plumchrus , and Eucalanus bungii during the ice-free season in the Sea of Okhotsk [Elektronische Daten] [Atsushi Tsuda, Hiroaki Saito, Hiromi Kasai, Jun Nishioka, Takeshi Nakatsuka] The Sea of Okhotsk is a semi-enclosed marginal sea of the subarctic North Pacific. One of the prominent characteristics of this area is the fast ice coverage during winter and early spring. We investigated the life cycles and vertical distributions of four species of large suspension feeding copepods, Neocalanus plumchrus, N. flemingeri, N. cristatus, and Eucalanus bungii in the southern part of the Sea of Okhotsk during the ice-free season. Neocalanus plumchrus and N. cristatus showed annual life cycles while a major part of the population of N. flemingeri and E. bungii showed biennial life cycles. Their occurrences in the surface layer for grazing and development were 1-2months later than in the adjacent area of the Pacific Ocean, and they remained longer in the surface layer for development. Consequently, the seasonal overlap among the copepods in the surface productive layer was intensified. In contrast, the vertical distribution of the four species of copepods during the growing period extended to deeper layers and became more finely segregated than those of Oyashio region and open ocean of the North Pacific. Thus, the seasonal segregations in the Oyashio region are replaced by vertical segregation in the Sea of Okhotsk. A major factor modifying the seasonal occurrences in the surface layer was considered to be the presence of fast ice during winter and early spring which greatly reduces the photosynthesis in the water column. The Oceanographic Society of Japan and Springer Japan, 2015 Neocalanus copepods nationallicence Eucalanus bungii nationallicence Life cycle nationallicence Vertical distribution nationallicence Habitat segregation nationallicence Sea of Okhotsk nationallicence Tsuda Atsushi Atmosphere and Ocean Research Institute, University of Tokyo, Nakano, 164-8639, Tokyo, Japan aut Saito Hiroaki Atmosphere and Ocean Research Institute, University of Tokyo, Nakano, 164-8639, Tokyo, Japan aut Kasai Hiromi Hokkaido National Fisheries Research Institute, 085-0802, Kushiro, Hokkaido, Japan aut Nishioka Jun Institute of Low Temperature Science, Hokkaido University, 060-0819, Sapporo, Hokkaido, Japan aut Nakatsuka Takeshi Graduate School of Environmental Studies, Nagoya University, 464-8601, Nagoya, Aichi, Japan aut Journal of Oceanography Springer Japan 71/3(2015-06-01), 271-285 0916-8370 71:3<271 2015 71 10872 https://doi.org/10.1007/s10872-015-0287-3 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10872-015-0287-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tsuda Atsushi Atmosphere and Ocean Research Institute, University of Tokyo, Nakano, 164-8639, Tokyo, Japan aut NATIONALLICENCE 700 1- Saito Hiroaki Atmosphere and Ocean Research Institute, University of Tokyo, Nakano, 164-8639, Tokyo, Japan aut NATIONALLICENCE 700 1- Kasai Hiromi Hokkaido National Fisheries Research Institute, 085-0802, Kushiro, Hokkaido, Japan aut NATIONALLICENCE 700 1- Nishioka Jun Institute of Low Temperature Science, Hokkaido University, 060-0819, Sapporo, Hokkaido, Japan aut NATIONALLICENCE 700 1- Nakatsuka Takeshi Graduate School of Environmental Studies, Nagoya University, 464-8601, Nagoya, Aichi, Japan aut NATIONALLICENCE 773 0- Journal of Oceanography Springer Japan 71/3(2015-06-01), 271-285 0916-8370 71:3<271 2015 71 10872