Cephalopod Fauna of the Scotia Sea at South Georgia: Potential for Commercial Exploitation and Possible Consequences

1990 ◽  
pp. 289-298 ◽  
Author(s):  
P. G. Rodhouse
Keyword(s):  
Commercial Exploitation ◽  
Scotia Sea ◽  
South Georgia

Changes in seabird species abundance near South Georgia during a period of rapid change in sea surface temperature

1992 ◽  
Vol 4 (1) ◽  
pp. 15-22 ◽  
Author(s):  
G.L. Hunt ◽  
J. Priddle ◽  
M.J. Whitehouse ◽  
R.R. Veit ◽  
R.B. Heywood
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Rapid Change ◽  
Species Abundance ◽  
Sea Surface ◽  
Resident Species ◽  
Seabird Species ◽  
Scotia Sea ◽  
South Georgia ◽  
Time Observation

During a three month research cruise near the island of South Georgia, sea surface temperature (SST) increased from c. 2°C to over 4°C. Satellite derived SST show that this corresponded to a rapid southward and eastward shift of isotherms in the northern Scotia Sea, which could have resulted from changes in the wind field. At the same time, observation from the ship of seabirds close to the island indicated changes in the abundance of some non-resident species, whereas resident breeders from South Georgia, such as black-browed albatrosses (Diomedea melanophris) and prions (Pachyptila spp.) which were foraging locally, were present at consistent density in both halves of the survey. Blue petrels (Halobaena caerulea) left the area after breeding, so were associated only with the low water temperatures during the first part of the cruise. In contrast, great shearwaters (Puffinus gravis) and soft-plumaged petrels (Pterodroma mollis) migrated into the area later in the survey. These birds were almost certainly non-breeders which were feeding in the warmer water which had moved towards the island.

Testing early life connectivity using otolith chemistry and particle-tracking simulations

2010 ◽  
Vol 67 (8) ◽  
pp. 1303-1315 ◽  
Author(s):  
Julian Ashford ◽  
Mario La Mesa ◽  
Bettina A. Fach ◽  
Christopher Jones ◽  
Inigo Everson
Keyword(s):  
Antarctic Peninsula ◽  
Early Life ◽  
Large Scale ◽  
Circulation Model ◽  
Model Material ◽  
Otolith Chemistry ◽  
Larval Phase ◽  
Scotia Sea ◽  
South Georgia ◽  
The Antarctic

We measured the otolith chemistry of adult Scotia Sea icefish ( Chaenocephalus aceratus ), a species with a long pelagic larval phase, along the Antarctic Circumpolar Current (ACC) and compared the chemistry with simulated particle transport using a circulation model. Material laid down in otolith nuclei during early life showed (i) strong heterogeneity between the Antarctic Peninsula and South Georgia consistent with a population boundary, (ii) evidence of finer-scale heterogeneity between sampling areas on the Antarctic Peninsula, and (iii) similarity between the eastern and northern shelves of South Georgia, indicating a single, self-recruiting population there. Consistent with the otolith chemistry, simulations of the large-scale circulation predicted that particles released at depths of 100–300 m on the Antarctic Peninsula shelf during spring, corresponding to hatching of icefish larvae from benthic nests, are transported in the southern ACC, missing South Georgia but following trajectories along the southern Scotia Ridge instead. These results suggest that the timing of release and position of early life stages in the water column substantially influence the direction and extent of connectivity. Used in complement, the two techniques promise an innovative approach for generating and testing predictions to resolve early dispersal and connectivity of populations related to the physical circulation of oceanic systems.

New data on Martialia hyadesi feeding in the Scotia Sea during winter; with emphasis on seasonal and annual variability

2004 ◽  
Vol 84 (4) ◽  
pp. 785-788 ◽  
Author(s):  
J. Dickson ◽  
S.A. Morley ◽  
T. Mulvey
Keyword(s):  
Prey Availability ◽  
Stomach Contents ◽  
Euphausia Superba ◽  
The South ◽  
Scotia Sea ◽  
South Georgia ◽  
Annual Variability

The diet of the seven star flying squid, Martialia hyadesi, from the South Georgia sector of the Scotia Sea was described from stomach contents collected in winter (June) 2001. Diet was dominated by the hyperiid amphipod, Themisto gaudichaudii, fish (nine species, mainly myctophids) and cephalopods (mainly cannibalism). The absence of krill, Euphausia superba, and the presence of larger myctophids in the diet are discussed in terms of seasonal and annual prey availability.

The Maximum Ice Extent on Island Groups in the Scotia Sea, Antarctica

1977 ◽  
Vol 7 (2) ◽  
pp. 268-282 ◽  
Author(s):  
D.E. Sugden ◽  
C.M. Clapperton
Keyword(s):  
Ice Cover ◽  
South Shetland Islands ◽  
Falkland Islands ◽  
The South ◽  
Scotia Sea ◽  
Shetland Islands ◽  
South Georgia ◽  
Orkney Islands ◽  
Ice Caps ◽  
The Antarctic

Evidence is presented for a more extensive ice cover over South Georgia, the South Orkney Islands, the South Shetland Islands, and the tip of the Antarctic Peninsula. Ice extended across the adjacent submarine shelves to a depth of 200 m below present sea level. Troughs cut into the submarine shelves by ice streams or outlet glaciers and ice-scoured features on the shelf areas suggest that the ice caps were warm-based. The South Shetland Islands appear not to have been overrun by continental ice. Geomorphological evidence in two island groups suggests that the maximum ice cover, which was responsible for the bulk of glacial erosion, predates at least one full glaciation. Subsequently there was a marine interval and then a glaciation which overran all of the lowlying peninsulas. The Falkland Islands, only 2° of latitude north of South Georgia, were never covered by an ice cap and supported only a few slightly enlarged cirque glaciers. This suggests that the major oceanographic and atmospheric boundary represented by the Antarctic Convergence, which is presently situated between the Falkland Islands and South Georgia, has remained in a similar position throughout the glacial age. Its position is probably bathymetrically controlled.

scholarly journals Summer microplankton community structure across the Scotia Sea: implications for biological carbon export

2010 ◽  
Vol 7 (1) ◽  
pp. 343-356 ◽  
Author(s):  
R. E. Korb ◽  
M. J. Whitehouse ◽  
M. Gordon ◽  
P. Ward ◽  
A. J. Poulton
Keyword(s):  
Austral Summer ◽  
Open Water ◽  
Carbon Export ◽  
Scotia Sea ◽  
South Georgia ◽  
Group A ◽  
Circumpolar Current ◽  
Physical Features ◽  
Previous Summer ◽  
Mixed Community

Abstract. During the austral summer of 2008, we carried out a high resolution survey of the microplankton communities along a south to north transect covering a range of environments across the Scotia Sea, Southern Ocean; high and low productivity, sea-ice to open water conditions, and over a number of oceanographic fronts and bathymetric features. Cluster analysis revealed five distinct communities that were geographically constrained by physical features of bathymetry and fronts. From south to north the communities were: (1) the South Orkney group, a mixed community of naked dinoflagellates and heavily silicified diatoms, (2) southern Scotia Sea, a mixed community of cyptophytes and naked dinoflagellates, (3) central Scotia Sea, dominated by naked dinoflagellates, (4) southwest of the island of South Georgia, lightly silicified diatoms and naked dinoflagellates (5) northwest of South Georgia, dominated by diatoms. Data from a previous summer cruise (2003) to the Scotia Sea followed a similar pattern of community distribution. MODIS images, Chlorophyll a and macronutrient deficits revealed dense phytoplankton blooms occurred around the island of South Georgia, were absent near the ice edge and in the central Scotia Sea and were moderate in the southern Scotia Sea. Using these environmental factors, together with community composition, we propose that south of the Southern Antarctic Circumpolar Current Front, biogenic silica is preferentially exported and north of the front, in the vicinity of South Georgia, carbon is exported to depth.

A Discussion on volcanism and the structure of the Earth - The evolution of the Scotia Ridge and Scotia Sea

1972 ◽  
Vol 271 (1213) ◽  
pp. 151-183 ◽  
Keyword(s):  
South America ◽  
Antarctic Peninsula ◽  
Weddell Sea ◽  
East Antarctica ◽  
The South ◽  
Scotia Sea ◽  
South Georgia ◽  
Scotia Ridge ◽  
Magnetic Lineations ◽  
The Antarctic

Marine geophysical surveys over the Scotia Ridge show it to be composed of blocks mainly of continental origin. Major structures found on the blocks are in many cases truncated at block margins and their existence is also inconsistent with the present isolated situation of the blocks. The evidence suggests post-Upper Cretaceous fragmentation of a continuous continental area. Complementary marine geomagnetic studies over the deep water of the Scotia Sea have dated two areas as younger than 22 million years (Ma) and have indicated the direction of spreading in others. A model of present plate motions, based on the magnetic anomalies, explains the active volcanism of the South Sandwich Islands as being caused by consumption of Atlantic crust at the associated trench at a rate of 5.5 cm/year for the past 7 to 8 Ma at least. An Upper Tertiary episode of plate consumption at 5 cm/year at the South Shetland trench, suggested by the magnetic lineations, with a secondary slow extensional widening of Bransfield Strait is used to explain similarly the contemporaneous volcanism of the South Shetland Is. Making the reasonable assumption of a Tertiary formation of the undated parts of the Scotia Sea by spreading in the directions indicated by the magnetic lineations, a tentative reconstruction of the component blocks of the Scotia Ridge is made. The attempt is only partly successful in matching structural patterns across adjacent margins of reconstructed blocks, South Georgia being most obviously wrongly situated. It is suggested that the misfits result from minor errors in the initial assumptions and the modification of structures during fragmentation and drift. South Georgia may have formed on the Atlantic rather than the Pacific side of the compact continental region which is thought to have joined South America and west Antarctica for much of the Mesozoic at least. A Gondwanaland reconstruction is presented which is consistent with the Scotia Ridge reconstruction, in which the Antarctic Peninsula lies alongside the Caird Coast of east Antarctica. Upon break-up of Gondwanaland, the Antarctic Peninsula remained rigidly attached to South America, east Antarctica rotating clockwise to open the Weddell Sea, until early Tertiary times when the Peninsula transferred to east Antarctica which continued rotating clockwise to open the Scotia Sea.

Glacier fluctuations in South Georgia and comparison with other island groups in the Scotia Sea

2020 ◽  
pp. 95-104 ◽  
Author(s):  
C.M. Clapperton ◽  
D.E. Sugden ◽  
R.V. Birnie ◽  
J.D. Hanson ◽  
G. Thom
Keyword(s):  
Scotia Sea ◽  
South Georgia ◽  
Glacier Fluctuations

scholarly journals Krill transport in the Scotia Sea and environs

1998 ◽  
Vol 10 (4) ◽  
pp. 406-415 ◽  
Author(s):  
Eileen E. Hofmann ◽  
John M. Klinck ◽  
Ricardo A. Locarnini ◽  
Bettina Fach ◽  
Eugene Murphy
Keyword(s):  
Flow Field ◽  
Antarctic Peninsula ◽  
Antarctic Circumpolar Current ◽  
Large Scale ◽  
Scotia Sea ◽  
South Georgia ◽  
Composite Flow ◽  
Large Scale Flow ◽  
Circumpolar Current ◽  
The Antarctic

Historical observations of the large-scale flow and frontal structure of the Antarctic Circumpolar Current in the Scotia Sea region were combined with the wind-induced surface Ekman transport to produce a composite flow field. This was used with a Lagrangian model to investigate transport of Antarctic krill. Particle displacements from known krill spawning areas that result from surface Ekman drift, a composite large-scale flow, and the combination of the two were calculated. Surface Ekman drift alone only transports particles a few kilometres over the 150-day krill larval development time. The large-scale composite flow moves particles several hundreds of kilometres over the same time, suggesting this is the primary transport mechanism. An important contribution of the surface Ekman drift on particles released along the continental shelf break west of the Antarctic Peninsula is moving them north-northeast into the high-speed core of the southern Antarctic Circumpolar Current Front, which then transports the particles to South Georgia in about 140–160 days. Similar particle displacement calculations using surface flow fields obtained from the Fine Resolution Antarctic Model do not show overall transport from the Antarctic Peninsula to South Georgia due to the inaccurate position of the southern Antarctic Circumpolar Current Front in the simulated circulation fields. The particle transit times obtained with the composite large-scale flow field are consistent with regional abundances of larval krill developmental stages collected in the Scotia Sea. These results strongly suggest that krill populations west of the Antarctic Peninsula provide the source for the krill populations found around South Georgia.

Interannual variations in cephalopod consumption by albatrosses at South Georgia: implications for future commercial exploitation of cephalopods

2007 ◽  
Vol 58 (12) ◽  
pp. 1136 ◽  
Author(s):  
J. C. Xavier ◽  
A. G. Wood ◽  
P. G. Rodhouse ◽  
J. P. Croxall
Keyword(s):  
Impact Assessment ◽  
Marine Environment ◽  
Interannual Variations ◽  
Commercial Exploitation ◽  
Squid Species ◽  
South Georgia ◽  
Commercial Potential ◽  
Cephalopod Species ◽  
Precautionary Measures ◽  
Oceanographic Conditions

Assessing the consumption of prey by predators in the marine environment is key to fisheries assessment and management. Although environmental and ecological variations can affect the consumption of certain prey by albatrosses interannually, this issue has not been addressed to date. In the present study, the interannual consumption of cephalopods by grey-headed and black-browed albatrosses was assessed while breeding at South Georgia between 1996 and 2000, by comparing consumption estimates from a reparameterised version of the South Georgia Seabird Impact Assessment (SGSIA) model. The reparameterised model showed that there are considerable interannual variations in cephalopod consumption in both albatross species, with the highest consumption occurring in 1996 (5787 tonnes; for black-browed albatrosses) and 1997 (11 627 tonnes; for grey-headed albatrosses), and the lowest in 2000 (2309 tonnes and 772 tonnes for grey-headed and black-browed albatrosses respectively). These interannual variations were linked to oceanographic conditions and changes in cephalopod abundance/availability to predators. The cephalopod species with the most commercial potential (Martialia hyadesi, Kondakovia longimana, Moroteuthis knipovitchi and Gonatus antarcticus) also showed considerable differences in their consumption by predators. Owing to the importance of these squid species in the diet of albatrosses, precautionary measures for future commercial exploitation are suggested.

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