Deep-sea polychaetes in the Weddell Sea and Drake Passage: first quantitative results

Polar Biology ◽  
2001 ◽  
Vol 24 (7) ◽  
pp. 538-544 ◽  
Author(s):  
Brigitte Hilbig
Keyword(s):  
Deep Sea ◽  
Drake Passage ◽  
Weddell Sea ◽  
Quantitative Results

scholarly journals An approach using ddRADseq and machine learning for understanding speciation in Antarctic Antarctophilinidae gastropods

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Juan Moles ◽  
Shahan Derkarabetian ◽  
Stefano Schiaparelli ◽  
Michael Schrödl ◽  
Jesús S. Troncoso ◽  
...  
Keyword(s):  
Machine Learning ◽  
Deep Sea ◽  
Weddell Sea ◽  
Nucleotide Polymorphisms ◽  
Sea Levels ◽  
Suitable Material ◽  
Genetic Lineages ◽  
Genome Wide ◽  
Gastropod Mollusks ◽  
Double Digestion

AbstractSampling impediments and paucity of suitable material for molecular analyses have precluded the study of speciation and radiation of deep-sea species in Antarctica. We analyzed barcodes together with genome-wide single nucleotide polymorphisms obtained from double digestion restriction site-associated DNA sequencing (ddRADseq) for species in the family Antarctophilinidae. We also reevaluated the fossil record associated with this taxon to provide further insights into the origin of the group. Novel approaches to identify distinctive genetic lineages, including unsupervised machine learning variational autoencoder plots, were used to establish species hypothesis frameworks. In this sense, three undescribed species and a complex of cryptic species were identified, suggesting allopatric speciation connected to geographic or bathymetric isolation. We further observed that the shallow waters around the Scotia Arc and on the continental shelf in the Weddell Sea present high endemism and diversity. In contrast, likely due to the glacial pressure during the Cenozoic, a deep-sea group with fewer species emerged expanding over great areas in the South-Atlantic Antarctic Ridge. Our study agrees on how diachronic paleoclimatic and current environmental factors shaped Antarctic communities both at the shallow and deep-sea levels, promoting Antarctica as the center of origin for numerous taxa such as gastropod mollusks.

An Antarctic shelf population of the deep-sea, Pacific brachiopod Neorhynchia strebeli

1997 ◽  
Vol 77 (2) ◽  
pp. 399-407 ◽  
Author(s):  
David K.A. Barnes ◽  
Lloyd S. Peck
Keyword(s):  
Deep Sea ◽  
Growth Function ◽  
Weddell Sea ◽  
Von Bertalanffy ◽  
Growth Rings ◽  
Von Bertalanffy Growth Function ◽  
Annual Periodicity ◽  
A Site ◽  
The Antarctic ◽  
Order Rhynchonellida

Thirty-five specimens of the articulate brachiopod Neorhynchia strebeli were collected from a site at 814 m in the Weddell Sea. This was only the second species of the order Rhynchonellida to be found in Antarctica. Formerly N. strebeli was known solely from abyssal Pacific Ocean localities. A circumantarctic distribution is suggested in addition to the known deep-sea Pacific range. The specimens of this collection showed considerable commissure variation, suggesting that the previously proposed erection of two subspecies on the basis of this character is erroneous, and emphasises the phenotypic plasticity of some articulate brachiopods. The valve lengths and the number of alpha growth rings in the sample showed a normal distribution and a von Bertalanffy growth function was fitted to the data: Lt = 23 (1-exp[-0·228t]). If the alpha growth rings were of annual periodicity, the ages attained by the Antarctic N. strebeli of 11 y would be substantially lower than those reported for other Weddell Sea brachiopods. The epibiotic communities occurring on the valves of N. strebeli were impoverished, which is characteristic of deep water Antarctic brachiopods. The few specimens collected with their substratum were attached to small pebbles, but the typical attachment substrata may be different.

scholarly journals Fish Teeth Sr Isotope Stratigraphy and Nd Isotope Variations: New Insights on REY Enrichments in Deep-Sea Sediments in the Pacific

2021 ◽  
Vol 9 (12) ◽  
pp. 1379
Author(s):  
Fenlian Wang ◽  
Gaowen He ◽  
Xiguang Deng ◽  
Yong Yang ◽  
Jiangbo Ren
Keyword(s):  
Deep Sea ◽  
Surface Sediments ◽  
Drake Passage ◽  
Marshall Islands ◽  
Early Oligocene ◽  
The Pacific ◽  
Deep Sea Sediments ◽  
Isotope Stratigraphy ◽  
Topographic Barriers ◽  
Fish Teeth

Rare earth elements and yttrium (REY) are widely recognized as strategic materials for advanced technological applications. Deep-sea sediments from the eastern South Pacific and central North Pacific were first reported as potential resources containing significant amounts of REY that are comparable to, or greater than, those of land-based deposits. Despite nearly a decade of research, quantitative abundances and spatial distributions of these deposits remain insufficient. Age controls are generally absent due to the lack of biostratigraphic constraints. Thus, the factors controlling the formation of REY-rich sediments are still controversial. In this study, the REY contents of surface sediments (<2 m depth) in 14 piston cores from the Middle and Western Pacific were investigated. The results show that deep-sea sediments with high REY contents (>1000 μg/g) were mainly concentrated around seamounts (e.g., the Marshall Islands). The REY contents of surface sediments generally decreased with distance from the seamounts. Biostratigraphic and fish teeth debris (apatite) Sr isotopic stratigraphy of one piston cores (P10) from the Middle Pacific indicate that deep-sea sediments with high REY contents were aged from early Oligocene to early Miocene. Since the opening of the Drake Passage during the early Oligocene, the northward-flowing Antarctic Bottom Water (AABW) would have led to an upwelling of nutrients around seamounts with topographic barriers, and at the same time, AABW would delay the rate of sediment burial to try for enough time for REY entering and enriching in the apatite (fish teeth debris). Understanding the spatial distribution of fertile regions for REY-rich sediments provides guidance for searching for other REY resources in the Pacific and in other oceans.

scholarly journals The Skytrain plate and tectonic evolution of southwest Gondwana since Jurassic times

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Graeme Eagles ◽  
Hannes Eisermann
Keyword(s):  
Tectonic Evolution ◽  
Drake Passage ◽  
Weddell Sea ◽  
Falkland Islands ◽  
South American ◽  
Long Distance ◽  
Oblique Collision ◽  
Scotia Sea ◽  
Continental Extension ◽  
Pacific Margin

AbstractUncertainty about the structure of the Falkland Plateau Basin has long hindered understanding of tectonic evolution in southwest Gondwana. New aeromagnetic data from the basin reveal Jurassic-onset seafloor spreading by motion of a single newly-recognized plate, Skytrain, which also governed continental extension in the Weddell Sea Embayment and possibly further afield in Antarctica. The Skytrain plate resolves a nearly century-old controversy by requiring a South American setting for the Falkland Islands in Gondwana. The Skytrain plate’s later motion provides a unifying context for post-Cambrian wide-angle paleomagnetic rotation, Cretaceous uplift, and post-Permian oblique collision in the Ellsworth Mountains of Antarctica. Further north, the Skytrain plate’s margins built a continuous conjugate ocean to the Weddell Sea in the Falkland Plateau Basin and central Scotia Sea. This ocean rules out venerable correlation-based interpretations for a Pacific margin location and subsequent long-distance translation of the South Georgia microcontinent as the Drake Passage gateway opened.

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 Global Change and the Biostratigraphy of North Atlantic Cainozoic deep water Ostracoda

1991 ◽  
Vol 9 (2) ◽  
pp. 119-132 ◽  
Author(s):  
Robin C. Whatley ◽  
Graham P. Coles
Keyword(s):  
Deep Sea ◽  
Middle Eocene ◽  
Drake Passage ◽  
Distribution Patterns ◽  
Global Changes ◽  
Climatic Fluctuations ◽  
Faunal Turnover ◽  
Extinction Rates ◽  
Large Numbers ◽  
Total Fauna

Abstract. The biostratigraphical distribution of deep-sea (>1000m) Palaeocene to Recent benthonic Ostracoda, based on nannofossil NP and NN zones is presented. By excluding very rare species and those represented by juveniles, 184 species are used in constructing range tables from a total fauna for the interval of 230 species. The vertical distribution of these specimens clearly allows of the recognition of all the major stratigraphical units within the Cainozoic and is also sufficiently precise to distinguish most of the nannofossil zones. The principal criteria employed are the first and last appearances of taxa. While eminently possible to create a series of ostracod zones, it is argued that they are best employed in the recognition of particular levels within the existing nannofossil scheme. The interpretation of the range tables is complicated in places by large numbers of Lazarus taxa and also by the fact that many of the ‘originations’ actually record the arrival of immigrants from the Indo-Pacific.Graphs of both simple and cumulative species diversity, and of origination and extinction rates, are used to demonstrate major faunal events such as the first arrival in the area, during the Middle Eocene, of cosmopolitan deep-sea species, or the very marked, but stepped, Palaeogene-Neogene faunal turnover. The distribution patterns of the Ostracoda record such global changes as the formation of the psychrosphere and the inception of a marked thermocline but they do not, as other authors have suggested, indicate a dramatic faunal turnover at the Eocene-Oligocene boundary. The more vigorous circulation patterns of the Oligocene, related to the opening of the Drake Passage, are reflected in enhanced ostracod diversity at that time. Elevated late Oligocene extinction rates may be correlated with cooling consequent upon the growth of polar ice. Similarly, Lower Miocene low levels of diversity may be associated with the closure of the Iberian Portal and the effective isolation of the Tethys. The deep-sea ostracods do not, for the most part, record such events as the mid-Pliocene warming nor Quaternary climatic fluctuations.

Taxonomy and biogeography of Molgolaimus Ditlevsen, 1921 (Nematoda: Chromadoria) with reference to the origins of deep sea nematodes

2006 ◽  
Vol 18 (1) ◽  
pp. 23-50 ◽  
Author(s):  
Gustavo Fonseca ◽  
Ann Vanreusel ◽  
Wilfrieda Decraemer
Keyword(s):  
Deep Sea ◽  
Tail Length ◽  
Species Level ◽  
Weddell Sea ◽  
Similar Species ◽  
Disturbed Areas ◽  
The Pacific ◽  
Morphometric Features ◽  
Total Community ◽  
The Pacific Ocean

Molgolaimus is a genus of free-living marine nematodes which is found in high densities (10–35% of the total community) up to 2000 m depth. Its occurrence is often associated with organically enriched and recently disturbed areas. Currently, only 16 species have been described, mainly from shallow waters. The present study contributes 17 new species mainly from the Weddell Sea but also from the Pacific Ocean, and provides an illustrated polytomous identification key to species level. The 33 Molgolaimus species described can be identified based on just a few morphometric features: spicule length, body length, anal body diameter, tail length and pharynx length. A first insight into the biogeography of this deep sea genus at species level is presented. A comparison of morphometric characteristics between species suggests that the most similar species co-occur in the same geographical region, rather than within the same bathymetric zones or similar ecosystems separated over long distances. These observations suggest that deep sea nematodes may not have a common origin but might have derived “recently” from shallow water taxa. Therefore, global distribution of nematodes could be explained by means of palaeogeographical events.

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