International Weddell Sea Oceanographic Expedition 1980
References Amos, A. F. 1978. A green iceberg sampled in the Weddell Sea. Antarct ice Journal of the U.S., 13(4), 63-64. Anderson, J . B., Domack, E. W., and Kurtz, D. D. In press. Observations of sediment laden icebergs in antarctic waters: Implications to glacial erosion and transport. Journal of Glaciology. Anderson, J . B., Kurtz, D. D., Domack, E. L., and Baishaw, K. M. 1980. Glacial and glacial marine sediments of the antarctic continental shelf. Journal of Geology, 88, 399-414. Anderson, J . B., Kurtz, D. D., and Weaver, F. M. 1976. Sedimentation on the Antarctic continental slope. Society of Economic Paleontologists and Mineralogists. Special Publication 27, 265-283. Ciesielski, P., and Jones, S. C. 1979. Sediment ages of Islas Orcadas 15 piston cores. Antarctic Journal of the U.S., 14(5), 148-151. Gordon, A. L. 1978. Deep antarctic convection west of Maud Rise. Journal of Physical Oceanography, 8, 600-612. Gordon, A. L., and LaBrecque, J . L. 1977. Islas Orcadas cruise 12: Capetown to Buenos Aires. Antarctic Journal of the U.S., 12,60-62. Gordon, A. L., and LaBrecque, J . L. 1977. Islas Orcadas cruise 12: Capetown to Buenos Aires. Antarctic Journal of the U.S., 12(4),60-62.
International Weddell Sea Oceanographic Expedition 1980 THEODORE D. FOSTER and DAVID L. GARRISON Center for Coastal Marine Studies University of California Santa Cruz, California 95064
LaBrecque, J . L., and Barker, P. F. In press. The age of the Weddell Basin. Nature. LaBrecque, J. L., and Hayes, D. E. 1979. Seafloor spreading history of the Agulhas Basin. Earth and Planetary Science Letters, 45(2), 411-428. LaBrecque, J. L., and Keller, M. In press. A geophysical study of the Indo-Atlantic Basin. In C. Craddock (Ed.), Antarctic Geoscience. Madison: University of Wisconsin Press. LaBrecque, J. L., and Rabinowitz, P. D. In press. General bathymetric chart of the Oceans (GEBCO), sheet 5.16. In indo-Atlantic Basin. Ottawa, Canada: Canadian Hydrographic Service. Martinson, D. G., Killworth, P. D., and Gordon, A. L. In press. A convective model for the Weddell Polynya. Journal of Physical Oceanography. Wright, R. 1980. Sediment gravity transport on the Weddell Sea continental margin. Unpublished masters thesis, Rice University. Zlotnicki, V., Sclater, J . G., Norton, I. 0., and Von Herzen, R. P. 1980. Heat flow through the floor of the Scotia, Far South Atlantic, and Weddell Seas. Geophysical Research Letters, 421-424.
has concentrated in the shelf break region in the southern Weddell Sea where earlier work (Foster and Carmack 1976) has shown bottom water forms. This third phase of IWSOE has been a cooperative effort between the University of Bergen and the University of California and has involved cruises of the Polarsirkel in 1977 and 1979 and the Glacier in 1978. Four of the 10 current meters set out during IWSOE 78 were retrieved. Most of the acoustic releases evidently did 60'
ROBERT L. MICHEL Scripps Institution of Oceanography University of California La Jolla, California 92093
500
400 -
300
60'
TOR TRRESEN 65°
65°
Geofysisk Inst it utt Universitetet i Bergen N-5014 Bergen, Norway 70°
The International Weddell Sea Oceanographic Expedition (IwsoE) was carried out in 1980 aboard the USCGC Polar Sea. The scientific party embarked at Ushuaia, Argentina, on 5 February 1980 and disembarked at Valparaiso, Chile, on 13 March 1980. The cruise track south of 60°S is shown in figure 1. The main objective of IWSOE has been the study of the formation of Antarctic Bottom Water in the Weddell Sea. Investigation during the third and final phase of IWSOE 1980 REVIEW
70°
75° 800 600
300 IC'
75'
Figure 1. The cruise track of the USCGC Polar Sea during IWSOE 80.
95
not survive the unscheduled 2-year deployment that resulted when Polar Star operations in the Weddell Sea planned for 1979 were canceled. These current meters yielded data on current speed and direction as well as water temperature for periods of up to 420 days. A total of 130 high-resolution conductivity-temperature-depth (cm) profiles were made in four sections. One very closely spaced section of 64 CTD casts was made across the shelf break from about 74°S 45°W to about 72°30'S 40°W. A second section of 15 cm casts was made along the shelf break from about 74°S 38°W to about 74°S 31°W. A third section of 40 cm casts was made across the Weddell Sea from about 71 °S 40°W to 62 0 S 47 0 W. The final section of 11 cm casts was made across the Scotia Ridge along 48°W from 61 0 S to about 59030'S.
to be analyzed for nutrients. Some of the water samples were filtered in order to collect nanoplankton and to assess the algal biomass by chlorophyll-a analysis. In addition, 31 vertical net hauls were made with a 35-micrometer mesh net to sample near-surface plankton populations. The biological sampling was coordinated with sea ice sampling by Ackley, Cow, Buck, and Golden (this volume) in order to compare algal biomass and assemblages in the water column with those in the sea ice. Preliminary examination of these samples suggest that planktonic forms are incorporated into newly forming ice. There was an abundance of "resting cells" in samples from newly formed ice (figure 3). Resting cell formation may be an adaptive mechanism to allow planktonic forms to survive or overwinter as members of ice-algal communities.
A preliminary evaluation of the temperature in this section is shown in figure 2. The sharp transition between the Weddell Sea water and the water flowing through the Drake Passage can be seen at about 40 kilometers north of the crest of the Scotia Ridge. This frontal zone may be very important to the understanding of the life history of krill and will be studied much more thoroughly in 1981.
During the cruise efforts were made to collect krill for determination of the carbon-14 in their tissues. A 1-meter zooplankton net was hauled vertically and obliquely by towing behind the ship at a speed of 2 to 3 knots for approximately 30 minutes. No substantial krill biomass was found, but enough biomass of surface-dwelling species was found to analyze for carbon-14 in two of the oblique hauls. One of these hauls was on the southern Weddell Sea continental shelf, and the other was in the Scotia Sea. The zooplankton, being primarily surface feeders, should yield information on surface water carbon-14 for these two areas.
In addition to the two water samples taken at every station for calibration of the cm, 21 six-Niskin-bottle casts were made for chemical and biological analysis. Portions of the water samples were frozen and returned to Santa Cruz
61°S
60°S
E I I—
a-
500
Ui 0
Ire 6=01
0
50 T
100
150 km
RIDGE CREST Figure 2. Preliminary section of temperature across the Scotia Ridge along 480W.
96
ANTARcTIC JOURNAL
,s 14 r
OK/ .5
AL
a
b
-4 •
4. /4
'
•S '
C
d
Figure 3. Resting cells from newly formed sea ice. a,
b. Spores in Chaetoceros op. c, d. Cyst formation in Peridinum sp.
The authors were assisted in the shipboard operations by References Arthur W. Hester and W. Martin Parks of Scripps Institution of Oceanography; James G. Mitchell of the University Ackley, S. F., Gow, A. J., Buck, K. R., and Golden, K. 1980. Sea-ice of California, Santa Cruz; and the officers and men of the studies in the Weddell Sea region aboard the USCGC Polar Sea. USCGC Polar Sea.
Antarctic Journal of the U.S., 15 (5).
Foster, T. D., and Carmack, E. C. 1976. Frontal zone mixing and
This research was supported by National Science Foun- antarctic bottom water formation in the southern Weddell Sea. dation grant Dl'? 78-07797. Deep-Sea Research, 23, 301-317.
1980 REvIEw
97
International Weddell Sea Oceanographic Expedition 1980 THEODORE D. FOSTER and DAVID L. GARRISON Center for Coastal Marine Studies University of California Santa Cruz, California 95064
LaBrecque, J . L., and Barker, P. F. In press. The age of the Weddell Basin. Nature. LaBrecque, J. L., and Hayes, D. E. 1979. Seafloor spreading history of the Agulhas Basin. Earth and Planetary Science Letters, 45(2), 411-428. LaBrecque, J. L., and Keller, M. In press. A geophysical study of the Indo-Atlantic Basin. In C. Craddock (Ed.), Antarctic Geoscience. Madison: University of Wisconsin Press. LaBrecque, J. L., and Rabinowitz, P. D. In press. General bathymetric chart of the Oceans (GEBCO), sheet 5.16. In indo-Atlantic Basin. Ottawa, Canada: Canadian Hydrographic Service. Martinson, D. G., Killworth, P. D., and Gordon, A. L. In press. A convective model for the Weddell Polynya. Journal of Physical Oceanography. Wright, R. 1980. Sediment gravity transport on the Weddell Sea continental margin. Unpublished masters thesis, Rice University. Zlotnicki, V., Sclater, J . G., Norton, I. 0., and Von Herzen, R. P. 1980. Heat flow through the floor of the Scotia, Far South Atlantic, and Weddell Seas. Geophysical Research Letters, 421-424.
has concentrated in the shelf break region in the southern Weddell Sea where earlier work (Foster and Carmack 1976) has shown bottom water forms. This third phase of IWSOE has been a cooperative effort between the University of Bergen and the University of California and has involved cruises of the Polarsirkel in 1977 and 1979 and the Glacier in 1978. Four of the 10 current meters set out during IWSOE 78 were retrieved. Most of the acoustic releases evidently did 60'
ROBERT L. MICHEL Scripps Institution of Oceanography University of California La Jolla, California 92093
500
400 -
300
60'
TOR TRRESEN 65°
65°
Geofysisk Inst it utt Universitetet i Bergen N-5014 Bergen, Norway 70°
The International Weddell Sea Oceanographic Expedition (IwsoE) was carried out in 1980 aboard the USCGC Polar Sea. The scientific party embarked at Ushuaia, Argentina, on 5 February 1980 and disembarked at Valparaiso, Chile, on 13 March 1980. The cruise track south of 60°S is shown in figure 1. The main objective of IWSOE has been the study of the formation of Antarctic Bottom Water in the Weddell Sea. Investigation during the third and final phase of IWSOE 1980 REVIEW
70°
75° 800 600
300 IC'
75'
Figure 1. The cruise track of the USCGC Polar Sea during IWSOE 80.
95
not survive the unscheduled 2-year deployment that resulted when Polar Star operations in the Weddell Sea planned for 1979 were canceled. These current meters yielded data on current speed and direction as well as water temperature for periods of up to 420 days. A total of 130 high-resolution conductivity-temperature-depth (cm) profiles were made in four sections. One very closely spaced section of 64 CTD casts was made across the shelf break from about 74°S 45°W to about 72°30'S 40°W. A second section of 15 cm casts was made along the shelf break from about 74°S 38°W to about 74°S 31°W. A third section of 40 cm casts was made across the Weddell Sea from about 71 °S 40°W to 62 0 S 47 0 W. The final section of 11 cm casts was made across the Scotia Ridge along 48°W from 61 0 S to about 59030'S.
to be analyzed for nutrients. Some of the water samples were filtered in order to collect nanoplankton and to assess the algal biomass by chlorophyll-a analysis. In addition, 31 vertical net hauls were made with a 35-micrometer mesh net to sample near-surface plankton populations. The biological sampling was coordinated with sea ice sampling by Ackley, Cow, Buck, and Golden (this volume) in order to compare algal biomass and assemblages in the water column with those in the sea ice. Preliminary examination of these samples suggest that planktonic forms are incorporated into newly forming ice. There was an abundance of "resting cells" in samples from newly formed ice (figure 3). Resting cell formation may be an adaptive mechanism to allow planktonic forms to survive or overwinter as members of ice-algal communities.
A preliminary evaluation of the temperature in this section is shown in figure 2. The sharp transition between the Weddell Sea water and the water flowing through the Drake Passage can be seen at about 40 kilometers north of the crest of the Scotia Ridge. This frontal zone may be very important to the understanding of the life history of krill and will be studied much more thoroughly in 1981.
During the cruise efforts were made to collect krill for determination of the carbon-14 in their tissues. A 1-meter zooplankton net was hauled vertically and obliquely by towing behind the ship at a speed of 2 to 3 knots for approximately 30 minutes. No substantial krill biomass was found, but enough biomass of surface-dwelling species was found to analyze for carbon-14 in two of the oblique hauls. One of these hauls was on the southern Weddell Sea continental shelf, and the other was in the Scotia Sea. The zooplankton, being primarily surface feeders, should yield information on surface water carbon-14 for these two areas.
In addition to the two water samples taken at every station for calibration of the cm, 21 six-Niskin-bottle casts were made for chemical and biological analysis. Portions of the water samples were frozen and returned to Santa Cruz
61°S
60°S
E I I—
a-
500
Ui 0
Ire 6=01
0
50 T
100
150 km
RIDGE CREST Figure 2. Preliminary section of temperature across the Scotia Ridge along 480W.
96
ANTARcTIC JOURNAL
,s 14 r
OK/ .5
AL
a
b
-4 •
4. /4
'
•S '
C
d
Figure 3. Resting cells from newly formed sea ice. a,
b. Spores in Chaetoceros op. c, d. Cyst formation in Peridinum sp.
The authors were assisted in the shipboard operations by References Arthur W. Hester and W. Martin Parks of Scripps Institution of Oceanography; James G. Mitchell of the University Ackley, S. F., Gow, A. J., Buck, K. R., and Golden, K. 1980. Sea-ice of California, Santa Cruz; and the officers and men of the studies in the Weddell Sea region aboard the USCGC Polar Sea. USCGC Polar Sea.
Antarctic Journal of the U.S., 15 (5).
Foster, T. D., and Carmack, E. C. 1976. Frontal zone mixing and
This research was supported by National Science Foun- antarctic bottom water formation in the southern Weddell Sea. dation grant Dl'? 78-07797. Deep-Sea Research, 23, 301-317.
1980 REvIEw
97
