Reproductive success of Pacific copepods in the Arctic Ocean and the possibility of changes in the Arctic ecosystem

Kohei Matsuno; Atsushi Yamaguchi; Toru Hirawake; Shigeto Nishino; Jun Inoue; Takashi Kikuchi

1. Arctic Environment Research Center, National Institute of Polar Research, 10–3 Midori-cho, Tachikawa, Tokyo, 190-8518, Japan.

2. Laboratory of Marine Biology, Graduate School of Fisheries Sciences, Hokkaido University, 3–1–1 Minato-cho, Hakodate, Hokkaido, 041-8611, Japan.

3. Japan Agency for Marine-Earth Science and Technology, 2–15 Natsushima-cho, Yokosuka, Kanagawa, 237-0061, Japan

【Abstract】The species composition of Arctic zooplankton differs greatly from that of the zooplankton of the North Pacific and Bering Sea. Particularly with greater warming from sea-ice retreat, the reproduction of North Pacific species transported into the Chukchi Sea and beyond may lead to changes in the Arctic pelagic ecosystem. We report the egg production and hatching of the Pacific copepod Neocalanus flemingeri in the Chukchi Sea based on shipboard experiments performed in September 2013. The reproductive capability of N. flemingeri observed in the Chukchi Sea resembled that reported in the Pacific, with the exception of a lower hatching success. Only 7.5 % of N. flemingeri eggs hatched compared with 93 % in Pacific experiments. Low hatching success is considered to be caused by failures of fertilization. The potential recruitment number for N. flemingeri suggests that it is unlikely to establish expatriate Arctic populations in the near future.

【Keyword】 Arctic Ocean; Pacific copepods; Neocalanus flemingeri; Reproduction