著者

Sijun Chen Victor S. Kuwahara Tomoyo Katayama Fuminori Hashihama Kazuo Yabe Satoru Taguchi Kazutaka Takahashi

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.18, no.4, pp.214-224, 2023-11-27 (Released:2023-11-30)

参考文献数

53

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We measured the concentrations of photoprotective compounds, carotenoids and mycosporine-like amino acids (MAAs), in surface-dwelling copepods in relation to their vertical distribution patterns along a zonal transect in the subtropical North Pacific to better understand their adaptation to strong ultraviolet (UV) radiation. All the dominant copepod groups analysed had detectable levels of both photoprotective compounds, while the concentrations differed among taxonomic groups. Farranula spp. had high carotenoid and MAA content (mean carotenoids: 0.0656; mean MAAs: 0.0230 µg mg dry wt−1) and the accumulation of MAAs correlated positively with in-situ UV penetration, explaining their constant occurrence in the surface layer throughout the transect. Oncaea spp. and Acrocalanus spp. had higher levels of carotenoids than MAAs and showed variable vertical distribution patterns regardless of UV penetration, suggesting that carotenoids are used only temporally to mitigate the effect of UV radiation. In contrast, Clausocalanus spp. and Calocalanus spp. had the lowest concentrations of both photoprotective compounds (mean carotenoids: 0.0148 and 0.0209; mean MAAs: 0.0015 and 0.0029 µg mg dry wt−1). The mean weighted depth of Clausocalanus spp. showed a significant negative relationship with UV penetration, suggesting that they mitigated the harmful effects of UV radiation through behavioural responses. Calocalanus spp. may have adapted to subtropical surface waters with relatively low photoprotective compound concentrations. Our study demonstrated that surface-dwelling subtropical copepods exhibit taxon-specific patterns in photoprotective compound concentrations that are adaptations to intense UV radiation, which is crucial for understanding the high species diversity of copepod communities in subtropical open waters.

著者

Kenji Tsuchiya Tomoko Yoshiki Ryota Nakajima Hideo Miyaguchi Victor S. Kuwahara Satoru Taguchi Tomohiko Kikuchi Tatsuki Toda

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.8, no.2, pp.74-87, 2013-05-25 (Released:2014-08-30)

参考文献数

74

被引用文献数

17 29

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Climate change has the potential for intensification of typhoons, which will cause stronger effects on aquatic ecosystems in the future. The effect of typhoon Mawar (T0511), passing Manazuru Port located in the western part of Sagami Bay, Japan, was investigated from August to September 2005. Immediately after the passage of Mawar, photosynthetically available radiation showed high values, salinity decreased dramatically and nutrient concentrations (NO2+NO3, PO4 and Si(OH)4) increased. Skeletonema spp. and Leptocylindrus spp. were dominant after the passage of Mawar, and their succession was linked to the variability of the N/P ratio. Primary production was highest at 349 mg C m−3 day−1 three days after Mawar, and high assimilation numbers lasted for nine days. The integrated primary production during the nine days after Mawar was 2.1×103 mg C m−3, which accounted for 7.2–9.1% of the annual primary production in the upper waters of Sagami Bay. The study confirms that enhanced primary production induced by episodic typhoon events in temperate coastal regions are significant, and should be considered in annual primary production estimates.