scholarly journals The biodiversity of the deep Southern Ocean benthos

2006 ◽  
Vol 362 (1477) ◽  
pp. 39-66 ◽  
Author(s):  
A Brandt ◽  
C De Broyer ◽  
I De Mesel ◽  
K.E Ellingsen ◽  
A.J Gooday ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Deep Water ◽  
Deep Sea ◽  
Large Scale ◽  
Environmental Parameters ◽  
Weddell Sea ◽  
Sediment Type ◽  
Biodiversity Patterns ◽  
Biogeographic Patterns ◽  
Relationship Of

Our knowledge of the biodiversity of the Southern Ocean (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global oceans are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep Antarctic shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae.

The work of the Discovery Committee

1950 ◽  
Vol 202 (1068) ◽  
pp. 1-16 ◽  
Keyword(s):  
Southern Ocean ◽  
Deep Water ◽  
Deep Sea ◽  
Original Form ◽  
The Past ◽  
Scientific Staff ◽  
Form Part ◽  
Whaling Industry ◽  
Major Industry ◽  
Colonial Office

The geographical field in which most of the Discovery Committee’s work has been carried out during the past 25 years is the Southern Ocean. This zone of continuous deep water, very rich in marine fife, supports one major industry—the whaling industry—but is otherwise little developed as yet, and seldom visited. It is not easy to find a short descriptive label for the work itself, but nearly all of it comes under the headings of deep-sea oceanography, whales and whaling, or Antarctic geography, and much of it is concerned with the interrelations of these subjects. Since the beginning in 1924 the Discovery Committee has worked under the Colonial Office, but in 1949 the Committee’s functions, together with the scientific staff, the ships, and other assets, were taken over by the Admiralty, and now form part of the new National Institute of Oceanography. The Discovery Committee, in its original form, has been dissolved, but it is encouraging to know that the continuation of its work is assured.

Acanthocopinae (Crustacea: Isopoda: Munnopsididae) from the Southern Ocean deep sea with the description of Acanthocope eleganta sp. nov.

Zootaxa ◽  
2004 ◽  
Vol 550 (1) ◽  
pp. 1 ◽  
Author(s):  
MARINA MALYUTINA ◽  
ANGELIKA BRANDT
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Deep Sea ◽  
Weddell Sea ◽  
Terminal Spine ◽  
Ventral Spine

Acanthocope eleganta sp. nov. is described from the abyssal Southern Ocean near the Southern Ocean Peninsula. The new species differs from others in the following: a slender dorsomedial spine on the pleon anteriorly, a pair of short dorsal spines and long ventral spine on each of pereonites 5 and 6; uropods half as long as the terminal spine of the pleotelson and with a minute exopod. A. annulatus Menzies, 1962 is redescribed; A. galatheae Wolff, 1962, previously known only from the Gulf of Panama and from Angola Basin, is recorded from the northwest Weddell Sea.

scholarly journals The Role of Southern Ocean Surface Forcings and Mixing in the Global Conveyor

2008 ◽  
Vol 38 (7) ◽  
pp. 1377-1400 ◽  
Author(s):  
Daniele Iudicone ◽  
Gurvan Madec ◽  
Bruno Blanke ◽  
Sabrina Speich
Keyword(s):  
Southern Ocean ◽  
North Atlantic ◽  
Deep Water ◽  
Thermohaline Circulation ◽  
North Atlantic Deep Water ◽  
Surface Fluxes ◽  
Weddell Sea ◽  
Mode Water ◽  
Circumpolar Deep Water ◽  
Subantarctic Mode Water

Abstract Despite the renewed interest in the Southern Ocean, there are yet many unknowns because of the scarcity of measurements and the complexity of the thermohaline circulation. Hence the authors present here the analysis of the thermohaline circulation of the Southern Ocean of a steady-state simulation of a coupled ice–ocean model. The study aims to clarify the roles of surface fluxes and internal mixing, with focus on the mechanisms of the upper branch of the overturning. A quantitative dynamical analysis of the water-mass transformation has been performed using a new method. Surface fluxes, including the effect of the penetrative solar radiation, produce almost 40 Sv (1 Sv ≡ 106 m3 s−1) of Subantarctic Mode Water while about 5 Sv of the densest water masses (γ > 28.2) are formed by brine rejection on the shelves of Antarctica and in the Weddell Sea. Mixing transforms one-half of the Subantarctic Mode Water into intermediate water and Upper Circumpolar Deep Water while bottom water is produced by Lower Circumpolar Deep Water and North Atlantic Deep Water mixing with shelf water. The upwelling of part of the North Atlantic Deep Water inflow is due to internal processes, mainly downward propagation of the surface freshwater excess via vertical mixing at the base of the mixed layer. A complementary Lagrangian analysis of the thermohaline circulation will be presented in a companion paper.

scholarly journals Glacial CO<sub>2</sub> decrease and deep-water deoxygenation by iron fertilization from glaciogenic dust

2019 ◽  
Author(s):  
Akitomo Yamamoto ◽  
Ayako Abe-Ouchi ◽  
Rumi Ohgaito ◽  
Akinori Ito ◽  
Akira Oka
Keyword(s):  
Southern Ocean ◽  
Ocean Circulation ◽  
Deep Water ◽  
Large Scale ◽  
Deep Ocean ◽  
Oxygen Solubility ◽  
Biological Pump ◽  
Surface Cooling ◽  
Iron Fertilization ◽  
Water Deoxygenation

Abstract. Increased accumulation of respired carbon in the deep ocean associated with enhanced efficiency of the biological carbon pump is thought to be a key mechanism of glacial CO2 drawdown. Despite greater oxygen solubility due to sea surface cooling, recent quantitative and qualitative proxy data show glacial deep-water deoxygenation, reflecting increased accumulation of respired carbon. However, the mechanisms of deep-water deoxygenation and contribution from the biological pump to glacial CO2 drawdown have remained unclear. In this study, we report the significance of iron fertilization from glaciogenic dust for glacial CO2 decrease and deep-water deoxygenation using our numerical simulation, which successfully reproduces the magnitude and large-scale pattern of the observed oxygen changes from the present to Last Glacial Maximum. Sensitivity experiments reveal that physical changes (e.g., more sluggish ocean circulation) contribute to only half of all glacial deep deoxygenation, whereas the other half is driven by enhanced efficiency of the biological pump. We found that iron input from the glaciogenic dust with higher iron solubility is the most significant factor for enhancement of the biological pump and deep-water deoxygenation. Glacial deep-water deoxygenation expands the hypoxic waters in the deep Pacific and Indian Ocean. The simulated global volume of hypoxic waters is nearly double the present value, which suggest that the glacial deep-water is sever environment for the benthic animals. Our model underestimated the deoxygenation in the deep Southern Ocean due to enhanced ventilation. The model-proxy comparison of oxygen change suggest that the stratified Southern Ocean is required for reproducing oxygen decline in the deep Southern Ocean. Enhanced efficiency of biological pump contributes to decrease of glacial CO2 by more than 30 ppm, which is supported by the model-proxy agreement of oxygen change. Our findings confirm the significance of the biological pump in glacial CO2 drawdown and deoxygenation.

scholarly journals Picoplankton Distribution and Activity in the Deep Waters of the Southern Adriatic Sea

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1655 ◽  
Author(s):  
Danijela Šantić ◽  
Vedrana Kovačević ◽  
Manuel Bensi ◽  
Michele Giani ◽  
Ana Vrdoljak Tomaš ◽  
...  
Keyword(s):  
Deep Sea ◽  
Large Scale ◽  
Heterotrophic Bacteria ◽  
Eastern Mediterranean ◽  
Environmental Parameters ◽  
Anoxygenic Phototrophic Bacteria ◽  
Heterotrophic Nanoflagellates ◽  
Nucleic Acid Content ◽  
Viral Lysis ◽  
Deep Waters

Southern Adriatic (Eastern Mediterranean Sea) is a region strongly dominated by large-scale oceanographic processes and local open-ocean dense water formation. In this study, picoplankton biomass, distribution, and activity were examined during two oceanographic cruises and analyzed in relation to environmental parameters and hydrographic conditions comparing pre and post-winter phases (December 2015, April 2016). Picoplankton density with the domination of autotrophic biomasses was higher in the pre-winter phase when significant amounts of picoaoutotrophs were also found in the meso-and bathy-pelagic layers, while Synechococcus dominated the picoautotrophic group. Higher values of bacterial production and domination of High Nucleic Acid content bacteria (HNA bacteria) were found in deep waters, especially during the post-winter phase, suggesting that bacteria can have an active role in the deep-sea environment. Aerobic anoxygenic phototrophic bacteria accounted for a small proportion of total heterotrophic bacteria but contributed up to 4% of bacterial carbon content. Changes in the picoplankton community were mainly driven by nutrient availability, heterotrophic nanoflagellates abundance, and water mass movements and mixing. Our results suggest that autotrophic and heterotrophic members of the picoplankton community are an important carbon source in the food web in the deep-sea, as well as in the epipelagic layer. Besides, viral lysis may affect the activity of the picoplankton community and enrich the water column with dissolved organic carbon.

Recent deep-water sedimentation, trace metal and radioisotope geochemistry across the Southern Ocean and Northern Weddell Sea, Antarctica

2007 ◽  
Vol 54 (16-17) ◽  
pp. 1652-1681 ◽  
Author(s):  
John A. Howe ◽  
Charles R. Wilson ◽  
Tracy M. Shimmield ◽  
Robert J. Diaz ◽  
Lawrence W. Carpenter
Keyword(s):  
Southern Ocean ◽  
Trace Metal ◽  
Deep Water ◽  
Weddell Sea

Molecular evolutionary relationships of the octopodid genus Thaumeledone (Cephalopoda: Octopodidae) from the Southern Ocean

2008 ◽  
Vol 20 (3) ◽  
pp. 245-251 ◽  
Author(s):  
J.M. Strugnell ◽  
M.A. Collins ◽  
A.L. Allcock
Keyword(s):  
Southern Ocean ◽  
Deep Water ◽  
Deep Sea ◽  
Nuclear Gene ◽  
Population Level ◽  
Molecular Study ◽  
South Shetland Islands ◽  
Evolutionary Relationships ◽  
Sequence Variability ◽  
Shetland Islands

AbstractRecent trawling in the Southern Ocean has yielded individuals of a number of species of the deep sea octopod genus Thaumeledone. This paper provides the first molecular study of the genus, employing molecular sequences from five mitochondrial (12S rDNA, 16S rDNA, COI, COIII, cytochrome oxidase b) and a single nuclear gene (rhodopsin) and includes representatives of each of the known Southern Ocean species. Thaumeledone rotunda, believed to be circumpolar in distribution and found in relatively deep water is the sister taxa to T. gunteri, known only from South Georgia. A notable level of sequence variability was evident between a T. peninsulae individual recently captured from the Powell Basin, and two T. peninsulae individuals captured from the continental slope, north of the South Shetland Islands. This is likely to represent population level intraspecific variation within this species.

scholarly journals What fraction of the Pacific and Indian oceans' deep water is formed in the Southern Ocean?

2018 ◽  
Vol 15 (12) ◽  
pp. 3779-3794 ◽  
Author(s):  
James W. B. Rae ◽  
Wally Broecker
Keyword(s):  
Southern Ocean ◽  
Deep Water ◽  
Large Scale ◽  
Bottom Water ◽  
Deep Ocean ◽  
Ocean Bottom ◽  
Biological Pump ◽  
Water Value ◽  
The Pacific ◽  
Northern Atlantic

Abstract. In this contribution we explore constraints on the fractions of deep water present in the Indian and Pacific oceans which originated in the northern Atlantic and in the Southern Ocean. Based on PO4* we show that if ventilated Antarctic shelf waters characterize the Southern contribution, then the proportions could be close to 50–50. If instead a Southern Ocean bottom water value is used, the Southern contribution is increased to 75 %. While this larger estimate may best characterize the volume of water entering the Indo-Pacific from the Southern Ocean, it contains a significant portion of entrained northern water. We also note that ventilation may be highly tracer dependent: for instance Southern Ocean waters may contribute only 35 % of the deep radiocarbon budget, even if their volumetric contribution is 75 %. In our estimation, the most promising approaches involve using CFC-11 to constrain the amount of deep water formed in the Southern Ocean. Finally, we highlight the broad utility of PO4* as a tracer of deep water masses, including descending plumes of Antarctic Bottom Water and large-scale patterns of deep ocean mixing, and as a tracer of the efficiency of the biological pump.

scholarly journals Macrostylis cerritus sp. nov., a new species of Macrostylidae (Isopoda: Asellota) from the Weddell Sea, Southern Ocean

Zootaxa ◽  
2009 ◽  
Vol 2096 (1) ◽  
pp. 356-370
Author(s):  
AIDAN VEY ◽  
SASKIA BRIX
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Deep Sea ◽  
Weddell Sea ◽  
Ventral Spine ◽  
A New Species

Macrostylis cerritus sp. nov. (Macrostylidae) is described from the Weddell Sea, Antarctica, at a depth of 2149 m. The new species differs from other species of Macrostylis due to the incisor with 4 cusps; the strongly hook-shaped ischium of pereopod 3; pereopod 4 being greatly reduced and juvenile in appearance; the operculum bearing a ventral spine-like seta; and the absence of pleopod 5. This species is the fourth deep-sea macrostylid identified from the Southern Ocean, and is one more species described from the specimens of ANDEEP I–III expeditions.

scholarly journals Deep sea without limits—four new closely related species of Emertonia Wilson, 1932 (Copepoda: Harpacticoida: Paramesochridae) show characters with a world-wide distribution

Zootaxa ◽  
2021 ◽  
Vol 5051 (1) ◽  
pp. 443-486
Author(s):  
ANNABEL MATHISKE ◽  
DAVID THISTLE ◽  
HENDRIK GHEERARDYN ◽  
GRITTA VEIT-KÖHLER
Keyword(s):  
Related Species ◽  
Deep Sea ◽  
Large Scale ◽  
Wide Distribution ◽  
Weddell Sea ◽  
Closely Related Species ◽  
The Pacific ◽  
Harpacticoid Copepods ◽  
The Family ◽  
Biogeographical Pattern

The large-scale dispersal of deep-sea harpacticoid copepods is an increasing focus for ecological studies. A fundamental prerequisite for monitoring and explaining their geographical distribution is precise descriptions of their morphology. Four new, closely related species of the family Paramesochridae (Copepoda, Harpacticoida) were found in the deep sea of the Pacific (San Diego Trough and off Chile), the Atlantic Ocean (Porcupine Abyssal Plain and Angola Basin), and the Atlantic and Indian Ocean sectors of the Southern Ocean (Weddell Sea and off Crozet Island). The discovery of Emertonia berndi sp. nov., E. hessleri sp. nov., E. ilse sp. nov., and E. serrata sp. nov. increases the number of known deep-sea species in this genus to ten. The new species are placed in Emertonia Wilson, 1932 because of their one-segmented endopods on the second and third swimming legs. The presence of a two-segmented endopod on the fourth swimming leg allocates them to the “andeep-group” within this genus. The four species can be distinguished from their congeners by the strongly serrated spines on the exopods of their swimming legs and an outwardly directed flexible seta on the exopod of the fifth leg. It is conveivable that these two specific characters evolved only once in the genus Emertonia. Their apparently cosmopolitan distribution covers thousands of kilometres and spans all major oceans. This biogeographical pattern may be explained by resuspension events followed by passive transport by benthic currents. Discrepancies in their dispersal ranges may be a result of changing geological and oceanographic boundaries.  

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