scholarly journals Morphological and morphometric comparisons of the first zoea of four species of purse crabs (Decapoda: Brachyura: Leucosiidae) from the Brazilian South Atlantic

Zootaxa ◽  
2012 ◽  
Vol 3167 (1) ◽  
pp. 17 ◽  
Author(s):  
GUSTAVO L. HIROSE ◽  
RAFAEL A. GREGATI ◽  
ADILSON FRANSOZO ◽  
MARIA L. NEGREIROS-FRANSOZO
Keyword(s):  
Discriminant Function ◽  
South Atlantic ◽  
Species Level ◽  
Ecological Studies ◽  
The South ◽  
Morphometric Measurements ◽  
Data Set ◽  
Larval Stages ◽  
Identification Of Species

Morphological descriptions of the first larval stages of Persephona mediterranea, P. lichtensteinii and P. punctata (Leu-cosiidae: Eballinae) from the South Atlantic are provided, with comparisons among the morphometry of the species. Adetailed description and eight morphometric measurements were made for each larva, and a discriminant function analysiswas used to interpret the data set. The species differed significantly in certain morphological and morphometric features.These characteristics may help in the identification of species of Leucosioidea found in the South Atlantic, and can be an important tool in ecological studies, supporting the identification of planktonic morphotypes at the species level.

scholarly journals Variability of carbon monoxide and carbon dioxide apparent quantum yield spectra in three coastal estuaries of the South Atlantic Bight

2012 ◽  
Vol 9 (6) ◽  
pp. 6947-6985 ◽  
Author(s):  
H. E. Reader ◽  
W. L. Miller
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Quantum Yield ◽  
South Atlantic ◽  
South Atlantic Bight ◽  
The South ◽  
Apparent Quantum Yield ◽  
Data Set ◽  
Direct Production ◽  
Coastal System

Abstract. The photochemical oxidation of oceanic dissolved organic carbon (DOC) to carbon monoxide (CO) and carbon dioxide (CO2) has been estimated to be a significant process with global photoproduction transforming petagrams of DOC to inorganic carbon annually. To further quantify the importance of these two photoproducts in coastal DOC cycling, 38 paired apparent quantum yield (AQY) spectra for CO and CO2 were determined at three locations along the coast of Georgia, USA over the course of one year. The AQY spectra for CO2 were considerably more varied than CO. CO AQY spectra exhibited a seasonal shift in spectrally integrated (260 nm–490 nm) AQY from higher efficiencies in the fall to less efficient photoproduction in the summer. While full-spectrum photoproduction rates for both products showed positive correlation with pre-irradiation UV-B sample absorption (i.e. chromophoric dissolved organic matter, CDOM) as expected, we found no correlation between AQY and CDOM for either product at any site. Molecular size, approximated with pre-irradiation spectral slope coefficients, and aromatic content, approximated by the specific ultraviolet absorption of the pre-irradiated samples, were also not correlated with AQY in either data set. The ratios of CO2 to CO photoproduction determined using both an AQY model and direct production comparisons were 23.2 ± 12.5 and 22.5 ± 9.0, respectively. Combined, both products represent a loss of 2.2 to 2.6 % of the DOC delivered to the estuaries and inner shelf of the South Atlantic Bight yearly, and 5 to 6 % of the total annual degassing of CO2 to the atmosphere. This result suggests that direct photochemical production of CO and CO2 is a small, yet significant contributor to both DOC cycling and CO2 gas exchange in this coastal system.

scholarly journals A study of the variability in the Benguela Current volume transport

Ocean Science ◽  
2018 ◽  
Vol 14 (2) ◽  
pp. 273-283 ◽  
Author(s):  
Sudip Majumder ◽  
Claudia Schmid
Keyword(s):  
Energy Density ◽  
Three Dimensional ◽  
Atlantic Water ◽  
Volume Transport ◽  
South Atlantic ◽  
The South ◽  
Meridional Transport ◽  
Data Set ◽  
Argo Floats ◽  
Benguela Current

Abstract. The Benguela Current forms the eastern limb of the subtropical gyre in the South Atlantic and transports a blend of relatively fresh and cool Atlantic water and relatively warm and salty Indian Ocean water northwestward. Therefore, it plays an important role not only for the local freshwater and heat budgets but for the overall meridional heat and freshwater transport in the South Atlantic. Historically, the Benguela Current region is relatively data sparse, especially with respect to long-term velocity observations. A new three-dimensional data set of the horizontal velocity in the upper 2000 m that covers the years 1993 to 2015 is used to analyze the variability in the Benguela Current. This data set was derived using observations from Argo floats, satellite sea surface height, and wind fields. Since Argo floats do not cover regions shallower than 1000 m, the data set has gaps inshore. The main features of the horizontal circulation observed in this data set are in good agreement with those from earlier studies based on limited observations. Therefore, it can be used for a more detailed study of the flow pattern as well as the variability in the circulation in this region. It is found that the mean meridional transport in the upper 800 m between the continental shelf of Africa and 3∘ E, decreases from 23 ± 3 Sv (1 Sv = 106 m3 s−1) at 31∘ S to 11 ± 3 Sv at 28∘ S. In terms of variability, the 23-year long time series at 30 and 35∘ S reveals phases with large energy densities at periods of 3 to 7 months, which can be attributed to the occurrence of Agulhas rings in this region. The prevalence of Agulhas rings is also behind the fact that the energy density at 35∘ S at the annual period is smaller than at 30∘ S because the former latitude is closer to Agulhas Retroflection and therefore more likely to be impacted by the Agulhas rings. In agreement with this, the energy density associated with mesoscale variability at 30∘ S is weaker than at 35∘ S. With respect to the forcing, the Sverdrup balance and the observed transport at 30∘ S exhibit a strong correlation of 0.7. No significant correlation between these parameters is found at 35∘ S.

On the Growth of Wind-Generated Waves in a Swell-Dominated Region in the South Atlantic

2001 ◽  
Vol 124 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Nelson Violante-Carvalho ◽  
Carlos Eduardo Parente ◽  
Ian S. Robinson ◽  
Luis Manoel P. Nunes
Keyword(s):  
Meteorological Data ◽  
South Atlantic ◽  
The South ◽  
Spectral Parameters ◽  
Data Set ◽  
Campos Basin ◽  
Open Sea ◽  
Range Theory ◽  
Novel Method ◽  
Equilibrium Range

The growth of surface gravity waves is investigated in an open sea region dominated by swell. An extensive database was collected by the Brazilian Oil Company during the South Atlantic Deep Water Program (PROCAP) in Campos Basin, off coast of Rio de Janeiro. This is the most important petrolic basin in Brazil where tens of drilling platforms are located. The data set contains over 5800 directional wave spectra measured by a heave-pitch-roll buoy in conjunction with meteorological data. A spectral approach is applied in a novel method for the partitioning of sea from swell and for the adjustment of the spectral parameters. The wave growth is investigated and the regression laws of the windsea extracted from the swell-contaminated spectra are compared to earlier works in sheltered areas. It is shown that, on the grounds of the equilibrium range theory, the high-frequency spectral level (the alpha parameter) scale with the reciprocal wave age in the same manner as in unimodal swell-free spectra.

Temporal Variability of the Meridional Overturning Cells in the South Atlantic

2020 ◽  
Author(s):  
Marion Kersalé ◽  
Christopher Meinen ◽  
Renellys Perez ◽  
Matthieu Le Hénaff ◽  
Daniel Valla ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Global Scale ◽  
Volume Transport ◽  
South Atlantic ◽  
Meridional Overturning Circulation ◽  
The South ◽  
Data Set ◽  
Air Temperatures ◽  
Coastal Sea ◽  
Meridional Overturning

<p>Variations in the Meridional Overturning Circulation (MOC) are known to have important impacts on global scale climate phenomena including precipitation patterns, surface air temperatures, coastal sea level, and extreme weather. The MOC flow structure in the South Atlantic is thought to control the stability of the entire global MOC system. Given this importance, significant resources have been invested on observing the MOC in the South Atlantic over the past decade. Multiple years of full-depth daily observations from moored instruments at 34.5°S are used to calculate the meridional transports near the western and eastern boundaries, as well as the basin-wide interior transports, via geostrophic methods. These transport estimates are combined with Ekman transports derived from satellite wind products to yield daily estimates of the total meridional transports. Analysis of the MOC volume transport using all available moored instruments from 2013 to 2017 allows us to quantify for the first time the daily volume transport of both the upper and abyssal overturning cells at 34.5°S. The structure of these flows is characterized in unprecedented detail; no statistically significant trend is detectable in either cell. Abyssal-cell transport variability is largely independent of the transport variability in the upper-cell. Analysis of this new data set is crucial for improving our understanding of the temporal and spatial scales of variability that governs MOC related flows, and for disentangling their respective roles in modulating its overall variability.</p>

scholarly journals Variability of carbon monoxide and carbon dioxide apparent quantum yield spectra in three coastal estuaries of the South Atlantic Bight

2012 ◽  
Vol 9 (11) ◽  
pp. 4279-4294 ◽  
Author(s):  
H. E. Reader ◽  
W. L. Miller
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Quantum Yield ◽  
South Atlantic ◽  
South Atlantic Bight ◽  
The South ◽  
Apparent Quantum Yield ◽  
Data Set ◽  
Direct Production ◽  
Coastal System

Abstract. The photochemical oxidation of oceanic dissolved organic carbon (DOC) to carbon monoxide (CO) and carbon dioxide (CO2) has been estimated to be a significant process with global photoproduction transforming petagrams of DOC to inorganic carbon annually. To further quantify the importance of these two photoproducts in coastal DOC cycling, 38 paired apparent quantum yield (AQY) spectra for CO and CO2 were determined at three locations along the coast of Georgia, USA over the course of one year. The AQY spectra for CO2 were considerably more varied than CO. CO AQY spectra exhibited a seasonal shift in spectrally integrated (260 nm–490 nm) AQY from higher efficiencies in the autumn to less efficient photoproduction in the summer. While full-spectrum photoproduction rates for both products showed positive correlation with pre-irradiation UV-B sample absorption (i.e. chromophoric dissolved organic matter, CDOM) as expected, we found no correlation between AQY and CDOM for either product at any site. Molecular size, approximated with pre-irradiation spectral slope coefficients, and aromatic content, approximated by the specific ultraviolet absorption of the pre-irradiated samples, were also not correlated with AQY in either data set. The ratios of CO2 to CO photoproduction determined using both an AQY model and direct production comparisons were 23.2 ± 12.5 and 22.5 ± 9.0, respectively. Combined, both products represent a loss of 2.9 to 3.2% of the DOC delivered to the estuaries and inner shelf of the South Atlantic Bight yearly, and 6.4 to 7.3% of the total annual degassing of CO2 to the atmosphere. This result suggests that direct photochemical production of CO and CO2 is a small, yet significant contributor to both DOC cycling and CO2 gas exchange in this coastal system.

scholarly journals A taxonomic guide to the Echinodermata of the South Atlantic Bight, USA: 1. Sea cucumbers (Echinodermata: Holothuroidea)

Zootaxa ◽  
2010 ◽  
Vol 2449 (1) ◽  
pp. 1 ◽  
Author(s):  
DAVID L. PAWSON ◽  
DORIS J. PAWSON ◽  
RACHAEL A. KING
Keyword(s):  
North Carolina ◽  
New Genus ◽  
South Atlantic ◽  
Species Level ◽  
South Atlantic Bight ◽  
The South ◽  
Sea Cucumbers ◽  
General Biology ◽  
Cape Hatteras

A summary account is given of the 33 holothurian species known from the South Atlantic Bight, from Cape Hatteras, North Carolina, to Cape Canaveral, Florida, from the shore to a depth of 200 meters. Four of the six known orders of holothurians are represented in the study area. Each species is diagnosed and illustrated; citations of informative literature and brief discussions of distribution and general biology are included. Also included are dichotomous keys to aid in identification to the species level. A new genus is erected to accommodate Pseudocolochirus mysticus Deichmann, 1930. Ocnus pygmaeus (Théel, 1886b) and O. surinamensis (Semper, 1868) are referred to the genus Aslia Rowe, 1970.

scholarly journals Paleo Agulhas rings enter the subtropical gyre during the penultimate deglaciation

2013 ◽  
Vol 9 (6) ◽  
pp. 2631-2639 ◽  
Author(s):  
P. Scussolini ◽  
E. van Sebille ◽  
J. V. Durgadoo
Keyword(s):  
South Atlantic ◽  
The South ◽  
Data Set ◽  
The Core ◽  
Walvis Ridge ◽  
Core Site ◽  
Cape Basin ◽  
Globorotalia Truncatulinoides ◽  
Density Perturbations

Abstract. A maximum in the strength of Agulhas leakage has been registered at the interface between the Indian and South Atlantic oceans during glacial Termination II (T-II). This presumably transported the salt and heat necessary for maintaining the Atlantic circulation at rates similar to the present day. However, it was never shown whether these waters were effectively incorporated into the South Atlantic gyre, or whether they retroflected into the Indian and/or Southern oceans. To resolve this question, we investigate the presence of paleo Agulhas rings from a sediment core on the central Walvis Ridge, almost 1800 km farther into the Atlantic Basin than previously studied. Analysis of a 60 yr data set from the global-nested INALT01 model allows us to relate density perturbations at the depth of the thermocline to the passage of individual rings over the core site. Using this relation from the numerical model as the basis for a proxy, we generate a time series of variability of individual Globorotalia truncatulinoides δ18O. We reveal high levels of pycnocline depth variability at the site, suggesting enhanced numbers of Agulhas rings moving into the South Atlantic Gyre around T-II. Our record closely follows the published quantifications of Agulhas leakage from the east of the Cape Basin, and thus shows that Indian Ocean waters entered the South Atlantic circulation. This provides crucial support for the view of a prominent role of the Agulhas leakage in the shift from a glacial to an interglacial mode of the Atlantic circulation.

scholarly journals A Study of the Variability of the Benguela Current

2017 ◽  
Author(s):  
Sudip Majumder ◽  
Claudia Schmid
Keyword(s):  
Energy Density ◽  
Three Dimensional ◽  
Atlantic Water ◽  
South Atlantic ◽  
The South ◽  
Wind Fields ◽  
Meridional Transport ◽  
Data Set ◽  
Benguela Current ◽  
Heat Budgets

Abstract. The Benguela Current forms the eastern limb of the subtropical gyre in the South Atlantic and transports a blend of relatively fresh and cool Atlantic water as well as relatively warm and salty Indian Ocean water northward. Therefore, it plays an important role not only for the local freshwater and heat budgets but for the overall meridional heat and freshwater transports in the South Atlantic. Historically, the Benguela Current region is relatively data sparse, especially with respect to long-term observations. A new three dimensional data set of the horizontal velocity in the upper 2000 m that covers the years 1993 to 2015 is used to analyze the variability of the Benguela Current. This data set was derived using observations from Argo floats, satellite sea surface height and wind fields. The main features of the horizontal circulation observed in this data set are in good agreement with those from earlier observations based on more limited data sets. Therefore, it can be used for a more detailed study the flow pattern as well as the variability of the circulation in this region. It is found that the mean meridional transport in the upper 800 m between the continental shelf of Africa and 3° E, decreases from 23 ± 3 Sv at 31° S to 11 ± 3 Sv at 28° S. In terms of variability, the 23-year long timeseries at 30° S and 35° S reveal phases with large energy densities at periods of 3 to 7 months, which can be attributed to the occurrence of Agulhas rings in this region. The prevalence of these rings is also behind the fact that the energy density at 35° S at the annual period is smaller than at 30° S, because the former latitude is closer to Agulhas retroflection and therefore more likely to be impacted by the Agulhas rings. In agreement with this, the energy density associated with mesoscale variability at 30° S is weaker than at 35° S. With respect to the forcing, the significant correlation between the Sverdrup balance derived from the wind stress and the observed transports at 30° S is 0.7. No significant correlation between these parameters was found at 35° S.

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