Seasonal abundance, population structure, sex ratio and gonad maturation of Metridia okhotensis Brodsky, 1950 in the Okhotsk Sea: analysis of samples collected by pumping up from deep water

Seasonal abundance, population structure, sex ratio and gonad maturation of Metridia okhotensis... INTRODUCTION The calanoid copepod Metridia spp. is distributed worldwide throughout the oceans and is listed as one of the dominant species, particularly among oceanic zooplankton fauna (Mauchline, 1998). In the North Pacific, Metridia okhotensis Brodsky, 1950 is listed as a secondary dominant metridinid species, following M. pacifica Brodsky, 1950 (Yamaguchi et al., 2002, 2010). The life cycle of M. okhotensis was only studied in the Oyashio region (Padmavati et al., 2004). In the Oyashio region, M. okhotensis is consistently found at depth (250-1000 m) throughout the year, except for excursions to the subsurface layer for spawning during the phytoplankton bloom (Padmavati et al., 2004). A two-year life cycle with diapause and C1 and C5 was proposed for M. okhotensis (cf. Padmavati et al., 2004). However, there was a low abundance of middle copepodid stages (C2-C4) throughout the year. Padmavati et al. (2004) suggested that the population in the Oyashio region was actually the population originating from the adjacent Okhotsk Sea. In the Okhotsk Sea, M. okhotensis accounts more than half of the numerical abundance in the zooplankton fauna (Asami et al., 2009; Yamaguchi, 2009; Shimada et al., 2012). Thus, their relative importance in the marine ecosystem varies with http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Crustaceana Brill

Seasonal abundance, population structure, sex ratio and gonad maturation of Metridia okhotensis Brodsky, 1950 in the Okhotsk Sea: analysis of samples collected by pumping up from deep water

Seasonal abundance, population structure, sex ratio and gonad maturation of Metridia okhotensis Brodsky, 1950 in the Okhotsk Sea: analysis of samples collected by pumping up from deep water


INTRODUCTION The calanoid copepod Metridia spp. is distributed worldwide throughout the oceans and is listed as one of the dominant species, particularly among oceanic zooplankton fauna (Mauchline, 1998). In the North Pacific, Metridia okhotensis Brodsky, 1950 is listed as a secondary dominant metridinid species, following M. pacifica Brodsky, 1950 (Yamaguchi et al., 2002, 2010). The life cycle of M. okhotensis was only studied in the Oyashio region (Padmavati et al., 2004). In the Oyashio region, M. okhotensis is consistently found at depth (250-1000 m) throughout the year, except for excursions to the subsurface layer for spawning during the phytoplankton bloom (Padmavati et al., 2004). A two-year life cycle with diapause and C1 and C5 was proposed for M. okhotensis (cf. Padmavati et al., 2004). However, there was a low abundance of middle copepodid stages (C2-C4) throughout the year. Padmavati et al. (2004) suggested that the population in the Oyashio region was actually the population originating from the adjacent Okhotsk Sea. In the Okhotsk Sea, M. okhotensis accounts more than half of the numerical abundance in the zooplankton fauna (Asami et al., 2009; Yamaguchi, 2009; Shimada et al., 2012). Thus, their relative importance in the marine ecosystem varies with that in the Oyashio region. While M. okhotensis is important in the Okhotsk Sea, little information is available regarding its life cycle there, partially because of the ice cover during winter. Because of this temporal ice cover, the collection of seasonal samples on a fine time-scale is difficult when using ordinary ship observations. In the town of Rausu, located on the southern coast of the Okhotsk Sea, deep-ocean water was collected by pumping up every day from a depth of 350 m for refrigerating fishery products, food processing and other industries (Takahashi & Yamashita, 2005; Takahashi et al., 2014). Zooplankton contained in the deep-ocean water was removed through a strainer (mesh size...
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Publisher
Brill
Copyright
Copyright 2016 by Koninklijke Brill NV, Leiden, The Netherlands.
Subject
Articles
ISSN
0011-216x
eISSN
1568-5403
DOI
10.1163/15685403-00003516
Publisher site
See Article on Publisher Site

Abstract

INTRODUCTION The calanoid copepod Metridia spp. is distributed worldwide throughout the oceans and is listed as one of the dominant species, particularly among oceanic zooplankton fauna (Mauchline, 1998). In the North Pacific, Metridia okhotensis Brodsky, 1950 is listed as a secondary dominant metridinid species, following M. pacifica Brodsky, 1950 (Yamaguchi et al., 2002, 2010). The life cycle of M. okhotensis was only studied in the Oyashio region (Padmavati et al., 2004). In the Oyashio region, M. okhotensis is consistently found at depth (250-1000 m) throughout the year, except for excursions to the subsurface layer for spawning during the phytoplankton bloom (Padmavati et al., 2004). A two-year life cycle with diapause and C1 and C5 was proposed for M. okhotensis (cf. Padmavati et al., 2004). However, there was a low abundance of middle copepodid stages (C2-C4) throughout the year. Padmavati et al. (2004) suggested that the population in the Oyashio region was actually the population originating from the adjacent Okhotsk Sea. In the Okhotsk Sea, M. okhotensis accounts more than half of the numerical abundance in the zooplankton fauna (Asami et al., 2009; Yamaguchi, 2009; Shimada et al., 2012). Thus, their relative importance in the marine ecosystem varies with

Journal

CrustaceanaBrill

Published: Jan 1, 2016

References

  • Seasonal and inter-species comparison of asymmetry in the genital system of some species of the oceanic copepod genus Metridia (Copepoda, Calanoida)
    Arima D. Matsuno K. Yamaguchi A. Nobetsu T. Imai I.

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