An unusual hermaphrodite reproductive trait in the Antarctic brooding bivalve Lissarca miliaris (Philobryidae) from the Scotia Sea, Southern Ocean

Polar Biology ◽  
2012 ◽  
Vol 36 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Adam J. Reed ◽  
Sven Thatje ◽  
Katrin Linse
Keyword(s):  
Southern Ocean ◽  
Reproductive Trait ◽  
Scotia Sea ◽  
The Antarctic

scholarly journals Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

2018 ◽  
Vol 15 (6) ◽  
pp. 1843-1862 ◽  
Author(s):  
Andrés S. Rigual Hernández ◽  
José A. Flores ◽  
Francisco J. Sierro ◽  
Miguel A. Fuertes ◽  
Lluïsa Cros ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Ocean Acidification ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Global Ocean ◽  
Field Observations ◽  
Scotia Sea ◽  
Allochthonous Species ◽  
Circumpolar Current ◽  
The Antarctic

Abstract. The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since high-latitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species. Coccolithophores are the most prolific calcium-carbonate-producing phytoplankton group playing an important role in Southern Ocean biogeochemical cycles. Satellite imagery has revealed elevated particulate inorganic carbon concentrations near the major circumpolar fronts of the Southern Ocean that can be attributed to the coccolithophore Emiliania huxleyi. Recent studies have suggested changes during the last decades in the distribution and abundance of Southern Ocean coccolithophores. However, due to limited field observations, the distribution, diversity and state of coccolithophore populations in the Southern Ocean remain poorly characterised. We report here on seasonal variations in the abundance and composition of coccolithophore assemblages collected by two moored sediment traps deployed at the Antarctic zone south of Australia (2000 and 3700 m of depth) for 1 year in 2001–2002. Additionally, seasonal changes in coccolith weights of E. huxleyi populations were estimated using circularly polarised micrographs analysed with C-Calcita software. Our findings indicate that (1) coccolithophore sinking assemblages were nearly monospecific for E. huxleyi morphotype B/C in the Antarctic zone waters in 2001–2002; (2) coccoliths captured by the traps experienced weight and length reduction during summer (December–February); (3) the estimated annual coccolith weight of E. huxleyi at both sediment traps (2.11 ± 0.96 and 2.13 ± 0.91 pg at 2000 and 3700 m) was consistent with previous studies for morphotype B/C in other Southern Ocean settings (Scotia Sea and Patagonian shelf); and (4) coccolithophores accounted for approximately 2–5 % of the annual deep-ocean CaCO3 flux. Our results are the first annual record of coccolithophore abundance, composition and degree of calcification in the Antarctic zone. They provide a baseline against which to monitor coccolithophore responses to changes in the environmental conditions expected for this region in coming decades.

scholarly journals New target-strength model indicates more krill in the Southern Ocean

2005 ◽  
Vol 62 (1) ◽  
pp. 25-32 ◽  
Author(s):  
David A. Demer ◽  
Stéphane G. Conti
Keyword(s):  
Southern Ocean ◽  
Euphausia Superba ◽  
Target Strength ◽  
Scotia Sea ◽  
Biomass Estimate ◽  
Antarctic Marine ◽  
Survey Results ◽  
The Antarctic

Abstract Antarctic krill, Euphausia superba, comprises the foundation of the foodweb in the Southern Ocean and is the target of a large fishery. Recently, the total abundance of krill in the Scotia Sea was estimated from an international echosounder and net survey (CCAMLR 2000) to be 44.3 million metric tonnes (Mt; CV 11.4%) (Hewitt et al., 2002). The new biomass estimate prompted the Antarctic Treaty's Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to revise the precautionary catch level for krill in the area from 1.5 to 4 Mt (SC-CAMLR, 2000). These survey results are based on the total echo energy attributed to krill, scaled by the Greene et al. (1991) model of krill acoustical reflectivity or target strength (TS). Presented here is a re-analysis of the CCAMLR 2000 data incorporating recent improvements in the characterization of krill TS. The results indicate that the estimated krill biomass in the Scotia Sea may be as high as 192.4 Mt (CV = 11.7%), or as low as 109.4 Mt (CV = 10.4%), depending solely on the expected distribution of krill orientations. The new Stochastic, Distorted-Wave, Born-Approximation (SDWBA) TS model solved with an empirically estimated distribution of in situ orientations leads to a krill-biomass estimate that is nearly 2.5 times the previous estimate. In consequence, revisions may be warranted of the standard krill TS model, the CCAMLR 2000 biomass estimate, and the associated precautionary catch level for krill in the Scotia Sea.

Conservation in the Antarctic

1977 ◽  
Vol 279 (963) ◽  
pp. 97-104 ◽  
Keyword(s):  
Southern Ocean ◽  
Control Measures ◽  
Falkland Islands ◽  
Voluntary Agreement ◽  
South Georgia ◽  
Tristan Da Cunha ◽  
Conservation Measures ◽  
Antarctic Seals ◽  
Antarctic Treaty ◽  
The Antarctic

Formidable legal and administrative complexities arise from conflicting claims to jurisdiction and the continued absence of generally recognized sovereignty over much of the region. Existing conservation measures fall into three groups: elaborate laws made by governments claiming Antarctic territories, more restricted laws, and simple instructions for particular expeditions. The Antarctic Treaty, 1959, made it possible to begin coordinating all these separate instruments. No claimed jurisdiction has been surrendered or recognized: each government has started to harmonize its own control measures with the ‘Agreed Measures for the Conservation of Antarctic Fauna and Flora’, 1964. This scheme applied only to land areas and has since been evolving in the light of experience. Although not yet formally approved by all the governments concerned, it is working effectively by voluntary agreement. Different approaches are necessary for conservation of Southern Ocean resources, especially krill. A start has been made with the ‘ Convention for the Conservation of Antarctic Seals’, 1972. There are many outstanding problems: all require effective cooperation between scientific and legal advisers, diplomats and politicians. Mention is made of recent British conservation legislation for South Georgia, the Falkland Islands and the Tristan da Cunha group. Some of the next steps are outlined.

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.

scholarly journals The trophodynamics of Southern Ocean Electrona (Myctophidae) in the Scotia Sea

Polar Biology ◽  
2014 ◽  
Vol 37 (6) ◽  
pp. 789-807 ◽  
Author(s):  
Ryan A. Saunders ◽  
Martin A. Collins ◽  
Emma Foster ◽  
Rachel Shreeve ◽  
Gabriele Stowasser ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Scotia Sea

Developments in Simulating and Parameterizing Interactions Between the Southern Ocean and the Antarctic Ice Sheet

2017 ◽  
Vol 3 (4) ◽  
pp. 316-329 ◽  
Author(s):  
Xylar S. Asay-Davis ◽  
Nicolas C. Jourdain ◽  
Yoshihiro Nakayama
Keyword(s):  
Southern Ocean ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
The Antarctic

Molecular systematics of Thouarella (Octocorallia:Primnoidae) with the description of three new species from the Southern Ocean based on combined molecular and morphological evidence

2021 ◽  
Author(s):  
Mónica Núñez-Flores ◽  
Daniel Gomez-Uchida ◽  
Pablo J. López-González
Keyword(s):  
New Species ◽  
Southern Ocean ◽  
Species Delimitation ◽  
Nuclear Dna ◽  
Phylogenetic Analyses ◽  
Weddell Sea ◽  
Morphological Evidence ◽  
Three New Species ◽  
Taxonomic Framework ◽  
The Antarctic

Thouarella Gray, 1870, is one of the most speciose genera among gorgonians of the family Primnoidae (Cnidaria:Octocorallia:Anthozoa), being remarkably diverse in the Antarctic and sub-Antarctic seafloor. However, their diversity in the Southern Ocean is likely underestimated. Phylogenetic analyses of mitochondrial and nuclear DNA markers were integrated with species delimitation approaches as well as morphological colonial and polyps features and skeletal SEM examinations to describe and illustrate three new species within Thouarella, from the Weddell Sea, Southern Ocean: T. amundseni sp. nov., T. dolichoespinosa sp. nov. and T. pseudoislai sp. nov. Our species delimitation results suggest, for the first time, the potential presence of Antarctic and sub-Antarctic cryptic species of primnoids, based on the likely presence of sibling species within T. undulata and T. crenelata. With the three new species here described, the global diversity of Thouarella has increased to 41 species, 15 of which are endemic to the Antarctic and sub-Antarctic waters. Consequently, our results provide new steps for uncovering the shelf benthonic macrofauna’s hidden diversity in the Southern Ocean. Finally, we recommend using an integrative taxonomic framework in this group of organisms and species delimitation approaches because the distinctions between some Thouarella species based only on a superficial examination of their macro- and micromorphological features is, in many cases, limited.

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