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.

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.

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.

scholarly journals Orographic Wave Drag over the Southern Ocean: A Linear Theory Perspective

2014 ◽  
Vol 71 (11) ◽  
pp. 4235-4252 ◽  
Author(s):  
Qingfang Jiang ◽  
Alex Reinecke ◽  
James D. Doyle
Keyword(s):  
Southern Ocean ◽  
Antarctic Peninsula ◽  
Large Scale ◽  
Climate Models ◽  
Temporal Variations ◽  
Wave Drag ◽  
Linear Wave ◽  
Surface Winds ◽  
South Georgia ◽  
The Antarctic

Abstract Recent studies suggest that stratospheric wind biases in global and climate models in the Southern Hemisphere may result from insufficient orographic wave drag, particularly over the Southern Ocean in the latitude belt centered near 60°S. In this study, contributions to the stratospheric wave drag along 60°S from three neighboring orographic wave sources are evaluated using a multiple-layer linear wave model with large-scale wind and stratification profiles derived from the Interim ECMWF Re-Analysis (ERA-Interim) between the years 1991 and 2010. The orographic wave sources include the Patagonian peaks in the southern Andes, the Antarctic Peninsula, and the island of South Georgia. The climatological and dynamical aspects of the wave drag and its dependence on tropospheric winds are investigated. The results suggest that these orographic wave sources may have significant contributions to the stratospheric drag over the Southern Ocean through meridional spreading of the wave momentum flux aloft associated with three-dimensional wave propagation. Among the three locations considered, the wave drag from the Antarctic Peninsula is substantially larger than that from Patagonia and nearly two orders of magnitude larger than that from South Georgia island. The orographic wave drag is in general proportional to the westerly component of the surface winds and becomes virtually zero when the surface winds have an easterly component, associated with critical level absorption between the tropospheric easterlies and prevailing westerlies in the stratosphere. The derived wave drag exhibits substantial temporal variations, including synoptic-scale, month-to-month, and interannual variations.

Movements of southern elephant seals

1996 ◽  
Vol 74 (8) ◽  
pp. 1485-1496 ◽  
Author(s):  
B. J. McConnell ◽  
M. A. Fedak
Keyword(s):  
Southern Ocean ◽  
Continental Shelf ◽  
Antarctic Peninsula ◽  
Average Rate ◽  
Stationary Phases ◽  
Mirounga Leonina ◽  
Elephant Seals ◽  
South Georgia ◽  
Southern Elephant Seals ◽  
The Antarctic

Twelve southern elephant seals (Mirounga leonina) were tracked for an average of 119 days as they left their breeding or moulting beaches on the island of South Georgia between 1990 and 1994. Females travelled either eastward up to 3000 km away to the open Southern Ocean or to the continental shelf on or near the Antarctic Peninsula. Males either stayed close to South Georgia or used South Georgia as a base for shorter trips. The females all left South Georgia in a directed manner at an average rate of 79.4 km/day over at least the first 15 days. Thereafter travel was interrupted by bouts of slower travel or stationary phases. The latter were localized at sites on the continental shelf or along its edge. Three seals that were tracked over more than one season repeated their outward direction of travel and used some of the same sites in subsequent years. The magnitude of the movements makes most of the Southern Ocean potentially available to elephant seals.

Observations of a newborn Ross seal pup (Ommatophoca rossi) near the Antarctic Peninsula

1980 ◽  
Vol 58 (11) ◽  
pp. 2156-2158 ◽  
Author(s):  
J. Thomas ◽  
D. DeMaster ◽  
S. Stone ◽  
D. Andriashek
Keyword(s):  
Antarctic Peninsula ◽  
Early Life ◽  
Amount Of Information ◽  
Behavioral Observations ◽  
The Antarctic

A Ross seal mother and male pup (Ommatophoca rossi) were sighted on 14 November 1978 in Dallmann Bay near the Antarctic Peninsula. This is believed to be the first documented observation of a newborn Ross seal. Behavioral observations and standard measurements taken from this pup enhance the small amount of information known about the early life of the species.

The first record of a myxomycete from subantarctic Macquarie Island

1992 ◽  
Vol 4 (4) ◽  
pp. 431-432 ◽  
Author(s):  
Steven L. Stephenson ◽  
Rodney D. Seppelt ◽  
Gary A. Laursen
Keyword(s):  
Antarctic Peninsula ◽  
Boreal Forests ◽  
Woody Debris ◽  
First Record ◽  
South Georgia ◽  
Orkney Islands ◽  
Signy Island ◽  
Slime Moulds ◽  
Plasmodial Slime Moulds ◽  
The Antarctic

Myxomycetes (plasmodial slime moulds) are best known from temperate and boreal forests, where they are commonly found in association with decaying coarse woody debris and leaf litter on the forest floor (Martin & Alexopoulos 1969). There have been only a few reports of myxomycetes from either the continent of Antarctica or the subantarctic islands. In what apparently represents the first record of a myxomycete from the south polar region, Horak (1966) described a new species, Diderma antarcticolum Horak, from material collected on the Antarctic Peninsula (64°53′S, 62°53′W). Later, Ing & Smith (1980,1983) reported Didymium dubium Rost., Lamproderma arcyrioides (Sommerf.) Rost., Stemonitopsis (Comatricha) subcaespitosa (Peck) Nann.- Brem. and Diderma niveum (Rost.) Macbr. from South Georgia (54–55°S, 36–38°W). They also indicated that the latter species was known from Signy Island, South Orkney Islands (60°43′S, 45°36′W) and the Antarctic Peninsula (65°16′S, 64°08′W) as well as South Georgia.

scholarly journals Glacier Fluctuations in George VI Sound Area, West Antarctica (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 345 ◽  
Author(s):  
C.M. Clapperton ◽  
D.E. Sugden
Keyword(s):  
Antarctic Peninsula ◽  
Ice Age ◽  
List Type ◽  
West Antarctica ◽  
Ice Shelf ◽  
Scotia Sea ◽  
Field Evidence ◽  
Glacial Chronology ◽  
History Of ◽  
The Antarctic

George VI Sound lies between Alexander Island and the Antarctic Peninsula and is over 20 km wide and 500 km long. At present an ice shelf fills the sound and is nourished largely by ice from the Antarctic Peninsula which flows across the sound to ground against the coast of Alexander Island. Ice-free areas, comprising small nunataks and larger massifs, fringe both sides of the sound and contain evidence of the former glacial history of the area. This paper describes the field evidence in detail and uses geomorphological and sedimentary analyses to put forward a relative glacial chronology, constrained by two absolute dates. The chronology distinguishes: (1) a maximum state during which all ice-free areas were submerged by ice flowing into George VI Sound from both the Antarctic Peninsula and Alexander Island and thence along the sound as an ice stream. This occurred in the late Wisconsin and followed an interstadial or interglacial when George VI Sound was free of an ice shelf. (2) a valley-based stadial during overall deglaciation represented by pronounced marginal moraines on Alexander Island. (3) deglaciation to a stage where there was less landbased ice on Alexander Island than today. At this stage isostatic recovery was incomplete, relative sealevel was higher, and George VI Ice Shelf penetrated further into embayments on Alexander Island than at present. (4) probable disappearance of George VI Ice Shelf by 6.5 14C ka BP. (5) neoglacial readvance of local glaciers on Alexander Island to form three closely spaced terminal moraines and the growth of a new George VI Ice Shelf which was again more extensive than at present. (6) subsequent oscillations of both smaller Alexander Island glaciers and George VI Ice Shelf probably during the Little Ice Age. These fluctuations are similar to those in other sub-Antarctic Islands in the Scotia Sea and also in southern Chile.

A new species of Placopsis (Agyriaceae: Ascomycota) from Antarctica

2005 ◽  
Vol 37 (4) ◽  
pp. 321-327 ◽  
Author(s):  
David J. GALLOWAY ◽  
Ronald I. LEWIS-SMITH ◽  
Wanda QUILHOT
Keyword(s):  
New Species ◽  
Antarctic Peninsula ◽  
Key To Species ◽  
South Georgia ◽  
The Antarctic ◽  
A New Species

Placopsis antarctica, which is apparently endemic to antarctic regions south of lat. 60°S (South Orkney Is, South Shetland Is and the Antarctic Peninsula), is described. Details of its morphology, anatomy, chemistry, ecology and distribution are given. Placopsis bicolor is newly reported from South Georgia. A revised key to species of Placopsis occurring in South Georgia and Antarctica is given.

Temperature Change on the Antarctic Peninsula Linked to the Tropical Pacific*

2013 ◽  
Vol 26 (19) ◽  
pp. 7570-7585 ◽  
Author(s):  
Qinghua Ding ◽  
Eric J. Steig
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Large Scale ◽  
Wave Train ◽  
Warming Trend ◽  
Tropical Pacific ◽  
The West ◽  
Spring Warming ◽  
Western Side ◽  
The Antarctic

Abstract Significant summer warming over the eastern Antarctic Peninsula in the last 50 years has been attributed to a strengthening of the circumpolar westerlies, widely believed to be anthropogenic in origin. On the western side of the peninsula, significant warming has occurred mainly in austral winter and has been attributed to the reduction of sea ice. The authors show that austral fall is the only season in which spatially extensive warming has occurred on the Antarctic Peninsula. This is accompanied by a significant reduction of sea ice cover off the west coast. In winter and spring, warming is mainly observed on the west side of the peninsula. The most important large-scale forcing of the significant widespread warming trend in fall is the extratropical Rossby wave train associated with tropical Pacific sea surface temperature anomalies. Winter and spring warming on the western peninsula reflects the persistence of sea ice anomalies arising from the tropically forced atmospheric circulation changes in austral fall.

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