Distribution of Copepoda along 140°E in the Indian sector of the Southern Ocean

NORPAC net samplings at three stations along a south-north transect on ca. 140°E were conducted in the Indian sector of the Southern Ocean from March 10 to 12 in 2002 during the 43rd Japanese Antarctic Research Expedition. The survey was held to examine the community structure and abundance of Copepoda in the seasonal ice zone of the Southern Ocean. A total of 15 species of copepod were identified at the stations. For nine species of copepod, Microcalanus pygmaeus, Calanus simillimus, Rhincalanus gigas, Euchaeta antarctica, Clausocalanus laticeps, Scolecithricella minor, Metridia lucens, Haloptilus oxycephalus and Oithona frigida, disparities of the distributions between the south of the Southern Boundary (SB) and the north became apparent. As here was a distinct difference of, about 2°C, in the sea surface temperature between the south and north of the SB, these disparities were considered to be influenced by the difference in the physical structure in the ocean, in particular by the water temperature, which was driven by the SB. Among Calanoides acutus, Calanus propinquus, and R. gigas, the earlier copepodite stages were observed at higher latitudes at all stations. This trend was considered to be a result of the sea ice retreat, which caused a later spawning period for Copepoda. In addition, an interaction between the sea ice conditions and the community structure of copepod along 140°E was suggested. key words: Copepoda, sea ice retreat, seasonal ice zone, Southern Boundary (SB), zooplankton

[1]  G. Hosie,et al.  The seasonal succession of zooplankton in the Southern Ocean south of Australia, part I: The seasonal ice zone , 2006 .

[2]  G. Hosie,et al.  Zonal structure of zooplankton communities in the Southern Ocean South of Australia: results from a 2150 km continuous plankton recorder transect , 2005 .

[3]  S. Aoki,et al.  Inter‐annual variability of chlorophyll and sea‐ice in the Antarctic Divergence region: an attempt to derive their quantitative relationship , 2005 .

[4]  Peter Rothery,et al.  Long-term decline in krill stock and increase in salps within the Southern Ocean , 2004, Nature.

[5]  高橋 邦夫.  Life cycle strategy of herbivorous copepod Calanoides acutus (Crustacea, Calanoida) in the Antarctic Ocean , 2004 .

[6]  Odate Tsuneo,et al.  Report on Workshop "Data management and synthesis of the results obtained during multi-ship/time-series study in 2001/2002 austral summer" , 2003 .

[7]  S. Sokolov,et al.  Structure of Southern Ocean fronts at 140°E , 2002 .

[8]  G. Hosie,et al.  Zooplankton distribution patterns in relation to the Antarctic Polar Front Zones Recorded by Continuous Plankton Recorder (CPR) during 1999/2000 Kaiyo Maru cruise , 2002 .

[9]  S. Chiba.  Spatio-temporal variability in life cycle strategy of four pelagic Antarctic copepods: Rhincalanus gigas, Calanoides acutus, Calanus propinquus and Metridia gerlachei , 2002 .

[10]  S. Chiba,et al.  Spatio-temporal variability of zooplankton community structure off east Antarctica (90 to 160°E) , 2001 .

[11]  N. Bindoff,et al.  Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent , 2000, Nature.

[12]  A. Atkinson,et al.  Zonal distribution and seasonal vertical migration of copepod assemblages in the Scotia Sea , 2000, Polar Biology.

[13]  G. Vargo,et al.  Effects of a rapidly receding ice edge on the abundance, age structure and feeding of three dominant calanoid copepods in the Weddell Sea, Antarctica , 1999, Polar Biology.

[14]  Kazutaka Takahashi,et al.  Long-term observation of zooplankton biomass in the Indian Ocean sector of the Southern Ocean , 1998 .

[15]  A. Atkinson.  Life cycle strategies of epipelagic copepods in the Southern Ocean , 1998 .

[16]  P. Ward,et al.  Regional differences in the life cycle of Calanoides acutus (Copepoda:Calanoida) within the Atlantic sector of the Southern Ocean , 1997 .

[17]  G. Hosie,et al.  ZOOPLANKTON COMMUNITY STRUCTURE OF PRYDZ BAY, ANTARCTICA, JANUARY-FEBRUARY 1993 (18th Symposium on Polar Biology) , 1997 .

[18]  A. Orsi,et al.  On the meridional extent and fronts of the Antarctic Circumpolar Current , 1995 .

[19]  U. Bathmann,et al.  Winter distribution and overwintering strategies of the Antarctic copepod species Calanoides acutus, Rhincalanus gigas and Calanus propinquus (Crustacea,Calanoida) in the Weddell Sea , 1993, Polar Biology.

[20]  S. Yamada,et al.  Copepods collected along 33.5 deg E longitude of the Antarctic Ocean in the 1976 summer , 1992 .

[21]  A. Atkinson.  Life cycles ofCalanoides acutus, Calanus simillimus andRhincalanus gigas (Copepoda: Calanoida) within the Scotia Sea , 1991 .

[22]  アキト カワムラ,et al.  TWO SERIES OF MACROZOOPLANKTON CATCHES WITH THE N70V NET IN THE INDIAN SECTOR OF THE ANTARCTIC OCEAN (Ninth Symposium on Polar Biology) , 1987 .

[23]  T. Hirawake,et al.  Unusual abundance of appendicularians in the seasonal ice zone(140°E ) of the Southern Ocean , 2006 .

[24]  A. Brierley,et al.  Ecology of southern ocean pack ice. , 2002, Advances in marine biology.

[25]  G. Deacon.  Physical and biological zonation in the Southern Ocean , 1982 .