scholarly journals Nutrient regimes control phytoplankton ecophysiology in the South Atlantic

2013 ◽  
Vol 10 (7) ◽  
pp. 11969-12008
Author(s):  
T. J. Browning ◽  
H. A. Bouman ◽  
C. M. Moore ◽  
C. Schlosser ◽  
G. A. Tarran ◽  
...  
Keyword(s):  
Photochemical Efficiency ◽  
South Atlantic ◽  
The South ◽  
Western Atlantic ◽  
Southern Boundary ◽  
The North ◽  
Circumpolar Current ◽  
Control Patterns ◽  
Chlorophyll Concentrations ◽  
Fe Addition

Abstract. Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton photophysiology from an across-basin South Atlantic cruise (as part of the GEOTRACES programme) characterized two dominant ecophysiological regimes which were interpreted on the basis of nutrient limitation. South of the South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters are characterized by elevated chlorophyll concentrations, a dominance by larger phytoplankton cells, and low apparent photochemical efficiency (Fv / Fm). Shipboard 24 h iron (Fe) addition incubation experiments confirmed that Fe stress was primarily responsible for the low Fv / Fm, with Fe addition to these waters, either within the artificial bottle additions or naturally occurring downstream enrichment from Gough Island, significantly increasing Fv / Fm values. Satellite images suggest a broader region of enhanced chlorophyll concentrations around the SSTC in the Western Atlantic relative to the Eastern Atlantic: hypothesized to be a result of higher iron supply from the South American continent. To the north of the SSTC at the southern boundary of the South Atlantic Gyre, phytoplankton are characterized by high values of Fv / Fm which, coupled with the low macronutrient concentrations and increased presence of picocyanobacteria, are interpreted as conditions of Fe replete, balanced macronutrient-limited growth. Spatial correlation was found between Fv / Fm and Fe:nitrate ratios, supporting the suggestion that the relative supply ratios of these two nutrients can control patterns of limitation and consequently the ecophysiology of phytoplankton in subtropical gyre and ACC regimes.

scholarly journals Nutrient regimes control phytoplankton ecophysiology in the South Atlantic

2014 ◽  
Vol 11 (2) ◽  
pp. 463-479 ◽  
Author(s):  
T. J. Browning ◽  
H. A. Bouman ◽  
C. M. Moore ◽  
C. Schlosser ◽  
G. A. Tarran ◽  
...  
Keyword(s):  
Photochemical Efficiency ◽  
South Atlantic ◽  
The South ◽  
Southern Boundary ◽  
The North ◽  
Incubation Experiments ◽  
Circumpolar Current ◽  
Control Patterns ◽  
The Antarctic ◽  
Fe Addition

Abstract. Fast Repetition Rate fluorometry (FRRf) measurements of phytoplankton photophysiology from an across-basin South Atlantic cruise (as part of the GEOTRACES programme) characterised two dominant ecophysiological regimes which were interpreted on the basis of nutrient limitation. South of the South Subtropical Convergence (SSTC) in the northern sub-Antarctic sector of the Antarctic Circumpolar Current (ACC) in the Eastern Atlantic Basin, waters are characterised by elevated chlorophyll concentrations, a dominance by larger phytoplankton cells, and low apparent photochemical efficiency (Fv / Fm). Shipboard 24 h iron (Fe) addition incubation experiments confirmed that Fe stress was primarily responsible for the low Fv / Fm, with Fe addition to these waters, either within the artificial bottle additions or naturally occurring downstream enrichment from Gough Island, significantly increasing Fv / Fm values. To the north of the SSTC at the southern boundary of the South Atlantic Gyre, phytoplankton are characterised by high values of Fv / Fm which, coupled with the low macronutrient concentrations and increased presence of picocyanobacteria, are interpreted as conditions of Fe replete, balanced macronutrient-limited growth. Spatial correlation was found between Fv / Fm and Fe:nitrate ratios, supporting the suggestion that the relative supply ratios of these two nutrients can control patterns of limitation and consequently the ecophysiology of phytoplankton in subtropical gyre and ACC regimes.

Taxonomy of Nystiellidae (Caenogastropoda, Epitonioidea) from Brazil, with description of three new species from the South-western Atlantic

2017 ◽  
Vol 98 (7) ◽  
pp. 1619-1644 ◽  
Author(s):  
Alexandre Dias Pimenta ◽  
Bruno Garcia Andrade ◽  
Ricardo Silva Absalão
Keyword(s):  
Rio Grande ◽  
Taxonomic Revision ◽  
South Atlantic ◽  
Shell Morphology ◽  
The South ◽  
Western Atlantic ◽  
North East ◽  
The North ◽  
Eastern Brazil ◽  
North Eastern

A taxonomic revision of the Nystiellidae from Brazil, including samples from the Rio Grande Rise, South Atlantic, was performed based on shell morphology. Five genera and 17 species were recognized. For the richest genus,Eccliseogyra, the three species previously recorded from Brazil were revised:E. brasiliensisandE. maracatu, previously known only from their respective type series, were re-examined. Newly available material ofE. maracatuexpanded the known geographic range of this species to off south-east Brazil.Eccliseogyra nitidais now recorded from north-eastern to south-eastern Brazil, as well as from the Rio Grande Rise. Three species ofEccliseogyraare newly recorded from the South Atlantic:E. monnioti, previously known from the north-eastern Atlantic, occurs off eastern Brazil and on the Rio Grande Rise; its protoconch is described for the first time, confirming its family allocation.Eccliseogyra pyrrhiasoccurs off eastern Brazil and on the Rio Grande Rise, andE. folinioff eastern Brazil. The genusIphitusis newly recorded from the South Atlantic.Iphitus robertsiwas found off northern Brazil, although the shells show some differences from the type material, with less-pronounced spiral keels. Additional new finds showed thatIphitus cancellatusranges from eastern Brazil to the Rio Grande Rise, and Iphitusnotiossp. nov. is restricted to the Rio Grande Rise.Narrimania, previously recorded from Brazil based on dubious records, is confirmed, including the only two living species described for the genus:N. azelotes, previously only known from the type locality in Florida, andN. concinna, previously known from the Mediterranean. A third species,Narrimania raquelaesp. nov. is described from eastern Brazil, diagnosed by its numerous and thinner cancellate sculpture. To the three species ofOpaliopsispreviously known from Brazil, a fourth species,O. arnaldoisp. nov., is added from eastern Brazil, and diagnosed by its very thin spiral sculpture, absence of a varix, and thinner microscopic parallel axial striae.Papuliscala nordestina, originally described from north-east Brazil, is recorded off eastern Brazil and synonymized withP. elongata, a species previously known only from the North Atlantic.

scholarly journals Subtropical Frontal Zone of the Southern Ocean

2021 ◽  
Author(s):  
Igor M Belkin
Keyword(s):  
Data Analysis ◽  
Frontal Zone ◽  
South Pacific ◽  
South Atlantic ◽  
Literature Survey ◽  
The South ◽  
Southern Boundary ◽  
The North ◽  
Brazil Current ◽  
Southeast Pacific

This paper combines a literature survey and data analysis. The literature on the Subtropical Front (STF) in the Southern Ocean is reviewed with a two-pronged emphasis on the double-front structure of the STF, hence the existence of a subtropical frontal zone (STFZ), and the circumpolar continuity of the STFZ. The data analysis is based on the World Ocean Circulation Experiment (WOCE) sections. The STFZ is detected along each section independently from other sections, while moving circum-polarly downstream (eastward). The literature survey and data analysis confirm the circumpolar continuity of the STFZ extending from the Brazil Current across the South Atlantic, South Indian, and South Pacific up to Chile, being bound by the North and South STF. The circumpolar continuity of the STFZ is partly interrupted by South Africa and Tasmania, where the North STF ceases, while the South STF continues eastward. The South Atlantic STFZ is the southern boundary of the well-defined Subtropical Mode Water (STMW) thermostad, which cools eastward from 15°C to 11°C between the Brazil Current and Greenwich Meridian. In the southeast Pacific, the STFZ is the southern boundary of the 17-to-19°C thermostad (South Pacific Eastern STMW). The STFZ’s vertical extent is at maximum in the South Atlantic (>1000 m), decreasing eastward to 300 m in the southeast Pacific off Chile. A special attention is given to the South Pacific and the STFZ’s role in the ecology of Chilean jack mackerel Trachurus murphyi that spawn at the STFZ and migrate along the STFZ from Chile up to New Zealand.

Observed seasonal regimes of North-South Atlantic Ocean interbasin exchange

2019 ◽  
Author(s):  
Hamed D. Ibrahim
Keyword(s):  
North Atlantic ◽  
Climate Models ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
Volume Flux ◽  
The South ◽  
The North ◽  
Basin Scale ◽  
Interbasin Exchange ◽  
North And South

North and South Atlantic lateral volume exchange is a key component of the Atlantic Meridional Overturning Circulation (AMOC) embedded in Earth’s climate. Northward AMOC heat transport within this exchange mitigates the large heat loss to the atmosphere in the northern North Atlantic. Because of inadequate climate data, observational basin-scale studies of net interbasin exchange between the North and South Atlantic have been limited. Here ten independent climate datasets, five satellite-derived and five analyses, are synthesized to show that North and South Atlantic climatological net lateral volume exchange is partitioned into two seasonal regimes. From late-May to late-November, net lateral volume flux is from the North to the South Atlantic; whereas from late-November to late-May, net lateral volume flux is from the South to the North Atlantic. This climatological characterization offers a framework for assessing seasonal variations in these basins and provides a constraint for climate models that simulate AMOC dynamics.

Distribution, history, and taxonomy of the Thais clade (Gastropoda: Muricidae) in the Neogene of tropical America

2001 ◽  
Vol 75 (3) ◽  
pp. 697-705 ◽  
Author(s):  
Geerat J. Vermeij
Keyword(s):  
New Species ◽  
South Atlantic ◽  
Eastern Pacific ◽  
Caribbean Region ◽  
Large Species ◽  
The South ◽  
Western Atlantic ◽  
Extinction Rates ◽  
Tropical America ◽  
The Caribbean

The earliest known members of the Thais clade of rapanine muricid neogastropods comprise four species from the Cantaure Formation (early Miocene: Burdigalian) of Venezuela; three of these species are new. Neorapana rotundata Gibson-Smith et al., 1997, is most closely related to the Recent Pacific Mexican N. tuberculata (Sowerby, 1835), and represents the only known Atlantic occurrence of the genus. Thais brevicula new species is closest to T. callaoensis (Gray, 1828) from the Recent of northern Peru and the Galápagos. A review of the genus Thais indicates that the typical members of this group occur in the South Atlantic, West Africa, and eastern Pacific, but not in the Recent fauna of the southern Caribbean. Stramonita bifida new species is a large species related to the Recent S. haemastoma floridana (Conrad, 1837), which occurs throughout the Caribbean. A review of American species of Stramonita indicates that the taxon S. biserialis (de Blainville, 1832) from the Recent fauna of the eastern Pacific, and the taxon S. h. haemastoma (Linnaeus, 1767), may each be composed of more than one species despite the teleplanic dispersal of their larvae. Stramonita semiplicata new species is closely related to the Recent S. bicarinata (de Blainville, 1832) from the South Atlantic, and represents a lineage that occurred in the Caribbean region until at least the late Miocene. It may have given rise to the eastern Pacific genus Acanthais. The higher diversity and greater antipredatory specialization of eastern Pacific as compared to western Atlantic members of the Thais clade may have resulted from higher post-Miocene rates of speciation and lower extinction rates in the eastern Pacific.

scholarly journals Activity, habitat utilization, feeding behaviour, and diet of the sand moray Gymnothorax ocellatus (Anguilliformes, Muraenidae) in the south western Atlantic

2003 ◽  
Vol 3 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Flávia Borges Santos ◽  
Ricardo M. C. Castro
Keyword(s):  
Feeding Behaviour ◽  
Habitat Utilization ◽  
South Atlantic ◽  
Muddy Sand ◽  
The South ◽  
Western Atlantic ◽  
Sense Of Smell ◽  
Sand Bottom

Activity, habitat utilization, feeding behaviour, and diet of the sand moray Gymnothorax ocellatus (Anguilliformes, Muraenidae) in the South western Atlantic. The sand moray Gymnothorax ocellatus is a nocturnal predator from the western South Atlantic that actively forages on the bottom, preying mostly on crustaceans (mainly shrimps and crabs) and ray-finned fishes, which are located primarily by the sense of smell. The individuals stay stationary during the day, almost always being hidden in individual tunnels dug by animals other than the morays in the muddy sand bottom.

Control of Precambrian-to-Paleozoic orogenic trends on along-strike variations in Early Cretaceous continental rifts of the South Atlantic Ocean

2019 ◽  
Vol 7 (4) ◽  
pp. SH45-SH69 ◽  
Author(s):  
Kyle Reuber ◽  
Paul Mann
Keyword(s):  
Early Cretaceous ◽  
South Atlantic ◽  
Orogenic Belt ◽  
Deep Penetration ◽  
The South ◽  
The North ◽  
Continental Rifts ◽  
Rift Zones ◽  
Seismic Reflection Profiles ◽  
Orogenic Belts

The Early Cretaceous (135–130 Ma) continental rupture of Western Gondwana to form the South American and African plates closely paralleled the elongate trends of Precambrian and Paleozoic orogenic belts. These orogenic belts were produced as a result of the Neoproterozoic convergent and strike-slip assembly of Gondwana that redeformed during later, Paleozoic orogenic events. Continued continental rifting led to the formation of conjugate, South Atlantic volcanic passive margins whose widths vary from 55 to 180 km. Along-strike variations in crustal stretching, as measured from deep-penetration seismic reflection profiles, correlate with parallel and oblique orientations of rifts relative to the trend of the orogenic, basement fabric. Where orogenic fabric trends parallel to the north–south South Atlantic rift direction such as in the Dom Feliciano orogenic belt of Uruguay and Brazil and the Kaoko Uruguay/Brazil and Kaoko orogenic belt of Namibia, we observe narrow (55–90 km) rift zones with modest continental beta factors of 2.5–3.5 because smaller amounts of rifting were needed to stretch the weaker and parallel, orogenic, basement fabric. Where the basement fabric trends near-orthogonally to the north–south South Atlantic rift direction such as in the Salado suture of Southern Uruguay and the Damara Belt of Namibia, we observe wider (185–220 km) rift zones with higher beta factors of 4.3–5 because greater amounts of stretching were needed to rupture the orthogonal, orogenic, basement fabric. The rift-oblique Gariep Belt intersects the South Atlantic continental rupture at an intermediate angle (30°) and exhibits a predicted intermediate beta factor of 4.0. A compilation of published beta factors from 36 other rifted margins worldwide supports the same basement-trend-degree of stretching relationship that we have developed — with rift-parallel margins having lower beta factors in a range of 1.3–3.5 and rift-orthogonal or oblique margins having higher beta factors in a range of 4–8.

scholarly journals Identification guide to the shallow water (0–200 m) octocorals of the South Atlantic Bight

Zootaxa ◽  
2010 ◽  
Vol 2599 (1) ◽  
pp. 1 ◽  
Author(s):  
SUSAN T. DEVICTOR ◽  
STEVE L. MORTON
Keyword(s):  
Shallow Water ◽  
South Atlantic ◽  
South Atlantic Bight ◽  
The South ◽  
Sem Images ◽  
Western Atlantic ◽  
Identification Guide ◽  
Cape Hatteras ◽  
History Of

Octocoral diversity is well documented in the tropical western Atlantic and Indo–Pacific, but it has been several decades since a thorough species account of the shallow South Atlantic Bight region was produced (northwestern Atlantic between Cape Hatteras, NC and Cape Canaveral, FL, USA). Through the use of material from the NMNH and SERTC Octocorallia (=Alcyonaria) collections, this work documents the presence of 28 species of octocorals recorded in the shallow (0–200 m) South Atlantic Bight and reports five new range extensions. Included are illustrated keys to the species, synonymies, species images and remarks, and SEM images of sclerites from described species without previously published sclerite imagery. A brief history of previous work and discussion of octocoral morphology are also included.

scholarly journals Agulhas ring injection into the South Atlantic during glacials and interglacials

Ocean Science ◽  
2008 ◽  
Vol 4 (3) ◽  
pp. 223-237 ◽  
Author(s):  
V. Zharkov ◽  
D. Nof
Keyword(s):  
Critical Angle ◽  
South Atlantic ◽  
African Continent ◽  
The South ◽  
Wind Stress Curl ◽  
Agulhas Current ◽  
The North ◽  
Meridional Overturning ◽  
The Indian Ocean ◽  
The Last Glacial

Abstract. Recent proxies suggest that, at the end of the last glacial, there was a significant increase in the injection of Agulhas rings into the South Atlantic (SA). This brought about a dramatic increase in the salt-influx (from the Indian Ocean) into the SA helping re-start the then-collapsed meridional overturning cell (MOC), leading to the termination of the Younger Dryas (YD). Here, we propose a mechanism through which large variations in ring production take place. Using nonlinear analytical solutions for eddy shedding, we show that there are restricted possibilities for ring detachment when the coast is oriented in the north-south direction. We define a critical coastline angle below which there is rings shedding and above which there is almost no shedding. In the case of the Agulhas region, the particular shape of the African continent implies that rings can be produced only when the retroflection occurs beyond a specific latitude where the angle is critical. During glaciation, the wind stress curl (WSC) vanished at a latitude lower than that of the critical angle, which prohibited the retroflection from producing rings. When the latitude at which the WSC vanishes migrated poleward towards its present day position, the corresponding coastline angle decreased below the critical angle and allowed for a vigorous production of rings. Simple process-oriented numerical simulations (using the Bleck and Boudra model) are in satisfactory agreement with our results and enable us to affirm that, during the glacials, the behavior of the Agulhas Current (AC) was similar to that of the modern East Australian Current (EAC), for which the coastline slant is supercritical.

scholarly journals Stalked crinoids (Echinodermata) collected by the R/V Polarstern and Meteor in the south Atlantic and in Antarctica

Zootaxa ◽  
2012 ◽  
Vol 3425 (1) ◽  
pp. 1 ◽  
Author(s):  
MARC ELÉAUME ◽  
JENS-MICHAEL BOHN ◽  
MICHEL ROUX ◽  
NADIA AMÉZIANE
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
South Atlantic ◽  
The South ◽  
The West ◽  
Walvis Ridge ◽  
The North ◽  
West Antarctic ◽  
Stalked Crinoids ◽  
Hard Substrates

During the last decades, R/V Meteor and R/V Polarstern deep-sea investigations in the south Atlantic and neighbouringSouthern Ocean collected new samples of stalked crinoids belonging to the families Bathycrinidae, Phrynocrinidae andHyocrinidae which are herein described. The species found are Bathycrinus australis A.H. Clark, 1907b (the most abun-dant), Dumetocrinus aff. antarcticus (Bather, 1908), Hyocrinus bethellianus Thomson, 1876, Feracrinus heinzelleri newspecies, and Porphyrocrinus cf. incrassatus (Gislén, 1933). As only stalk fragments of bathycrinids were frequently col-lected, a distinction between the two Atlantic species B. australis and B. aldrichianus is proposed using characters of co-lumnal articulations. A few specimens attributed to Porphyrocrinus cf. incrassatus, Hyocrinus bethellianus and Hyocrinussp. collected by the N/O Jean Charcot on the Walvis Ridge are also described, plus a new specimen of Porphyrocrinusincrassatus collected in the central mid-Atlantic. Biogeography and close affinities between species in the genera Bathy-crinus and Porphyrocrinus suggest an Antarctic origin of some stalked crinoids among the north Atlantic deep-sea fauna.The presence of B. australis in both the Angola and Cape basins suggests that the Walvis Ridge is not a bio-geographicalbarrier for this relatively eurybathic species, which can attach to hard substrates as well as anchor in sediment. The genusDumetocrinus seems to be an example of colonization of the west Antarctic platform from deeper environment where its ancestor lived.

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