著者

Akiyuki Kenmochi Hiroyuki Matsuura Takashi Yoshikawa Rumi Sohrin Yumiko Obayashi Jun Nishikawa

出版者

The Plankton Society of Japan, The Japanese Association of Benthology

雑誌

Plankton and Benthos Research (ISSN:18808247)

巻号頁・発行日

vol.17, no.1, pp.57-65, 2022-02-22 (Released:2022-02-23)

参考文献数

53

被引用文献数

1

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Seasonal occurrences of marine cladocerans in offshore Suruga Bay, Japan, were studied from 2014 to 2019. Zooplankton samples were collected monthly from a station (depth: ca. 1000 m) located in the offshore area of the bay. Cladocerans appeared each year from February to December, and disappeared in January. Their abundance increased drastically from April to September and comprised a substantial portion of the offshore mesozooplankton community during this period. Maximum cladoceran abundance occurred from June to August, ranging from 65.9–1341.9 individuals m−3. These patterns in cladoceran abundances were basically repeated each year throughout the study period. This result suggests that mass occurrences of cladocerans in offshore regions of the bay during the spring-summer are regular events rather than sporadic. Seven species, which have previously been reported from Japanese waters, were identified, and successional changes in the dominant species were observed. The most abundant species, Penilia avirostris, carried parthenogenetic embryos in brood pouches, suggesting that they were not simply transported from coastal areas, but that they also reproduce in the offshore waters. Regular mass occurrences of marine cladocerans in offshore Suruga Bay could have an important impact on the offshore ecosystem of the bay, and factors enabling these population cycles need to be determined.