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Vertical distribution, life cycle, and developmental characteristics of the mesopelagic calanoid copepod Gaidius variabilis (Aetideidae) in the Oyashio region, western North Pacific Ocean
Title: | Vertical distribution, life cycle, and developmental characteristics of the mesopelagic calanoid copepod Gaidius variabilis (Aetideidae) in the Oyashio region, western North Pacific Ocean |
Authors: | Yamaguchi, A. Browse this author →KAKEN DB | Ikeda, T. Browse this author →KAKEN DB |
Issue Date: | Aug-2000 |
Journal Title: | Marine Biology |
Volume: | 137 |
Issue: | 1 |
Start Page: | 99 |
End Page: | 109 |
Publisher DOI: | 10.1007/s002270000316 |
Abstract: | Vertical distribution, life cycle, and developmental characteristics of the mesopelagic copepod Gaidius variabilis in the Oyashio region were investigated by combining the analyses of field copepodite populations with laboratory-rearing data of egg hatching and naupliar development. Field samplings from five discrete depths between the surface and ≤ 2000 m were made approximately every month for one year. Most populations of G. variabilis occurred at 600-1000 m depth. A modest degree of reversed diel vertical migration behavior and some stage-specific depth-distribution patterns were noted. All copepodite stages were observed throughout the year, suggesting a year-round spawning of G. variabilis. From a prominent abundance peak of copepodite stage 1 (C1) seen in June-August, together with development times of eggs and nauplii obtained in laboratory-rearing experiments, the major spawning season was extrapolated to April-June, the phytoplankton bloom season. Tracing the peak abundance of each copepodite stage (distinguishing males and females for C4-C6), the generation lengths of males and females were deduced as 2 and 1 yr, respectively. All between-stage increments in terms of wet-, dry-, and ash-free dry weights were greatest in C3/C4, and least in C5/C6 for both males and females. The increments in C3/C4 and C4/C5 were greater for males than for females, reflecting a longer stage duration of the males. These weights did not increase in C5/C6 males, possibly because feeding ceased in C6 males. These results of G. variabilis are compared with those of some mesopelagic copepods previously reported from other regions. |
Rights: | The original publication is available at www.springerlink.com |
Relation: | http://www.springerlink.com |
Type: | article (author version) |
URI: | http://hdl.handle.net/2115/45411 |
Appears in Collections: | 水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 山口 篤
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