scholarly journals Barriers to gene flow along the Brazilian coast: a synthesis and data analysis

2021 ◽  
Author(s):  
Nuno Martins ◽  
Leonardo Macagnan ◽  
Valéria Cassano ◽  
CARLOS GURGEL
Keyword(s):  
Gene Flow ◽  
Strong Association ◽  
Continuous Distribution ◽  
Significant Negative Correlation ◽  
Additive Models ◽  
Phylogeographic Structure ◽  
Brazilian Coast ◽  
Published Data ◽  
Brazil Current ◽  
North Brazil

Barriers to gene flow (BGF) play a pivotal role in the dynamics of population genetics promoting genetic differentiation, thus, are inexorably associated with the development and maintenance of phylogeographic structure. Phylogeographic structure resulting from BGF represents data that help the management of natural genetic resources, aiding in the recognition of areas of conservation interest. Several geographic and oceanographic processes found along the Brazilian coast have been proposed as BGF. However, no consensus exist identifying which of them represents the most important in shaping biodiversity. Therefore, this study provides a synthesis of the scientific literature on Brazilian marine phylogeography and used published data to build datasets that allowed us apply linear (lm) and generalized additive models (gam) to identify spatially congruent phylogeographic breaks among marine species (as areas of high BGF frequency occurrence). Lm identified a significant negative correlation between the occurrence of BGF and latitude, suggesting that population in the tropics are genetically more structured than in higher latitudes. This result bears strong association with the latitude species diversity gradient observed worldwide. Gam identified Cape São Roque (05° 28’ S) as the main BGF for populations with continuous distribution along the Brazilian coast. Cape São Roque is located near the center point region where the South Equatorial Current splits into the northward North Brazil Current and the southward Brazil Current. This study represents the first literature synthesis of Brazil’s marine phylogeography and provides a novel explicit quantitative approach to comparative phylogeography.

scholarly journals Circulation of the thermocline salinity maximum waters off the Northern Brazil as inferred from in situ measurements and numerical results

2009 ◽  
Vol 27 (5) ◽  
pp. 1861-1873 ◽  
Author(s):  
A. C. Silva ◽  
B. Bourles ◽  
M. Araujo
Keyword(s):  
Numerical Model ◽  
Northern Hemisphere ◽  
Brazilian Coast ◽  
Western Boundary ◽  
Equatorial Undercurrent ◽  
High Salinity Water ◽  
The North ◽  
Brazil Current ◽  
North Brazil ◽  
Northern Edge

Abstract. High resolution hydrographic observations of temperature and salinity are used to analyse the subsurface circulation along the coast of North Brazil, off the Amazon mouth, between 2° S and 6° N. Observations are presented from four cruises carried out in different periods of the year (March–May 1995, May–June 1999, July–August 2001 and October–November 1997). Numerical model outputs complement the results of the shipboard measurements, and are used to complete the descriptions of mesoscale circulation. The Salinity Maximum Waters are here analyzed, principally in order to describe the penetration of waters originating in the Southern Hemisphere toward the Northern Hemisphere through the North Brazil Current (NBC)/North Brazil Undercurrent (NBUC). Our results show that, if the Equatorial Undercurrent (EUC) is fed by Northern Atlantic Waters, this contribution may only occur in the ocean interior, east of the western boundary around 100 m depth. Modeling results indicate a southward penetration of the Western Boundary Undercurrent (WBUC) below the thermocline, along the North Brazilian coast into the EUC or the North Equatorial Undercurrent (NEUC) (around 48° W–3° N). The WBUC in the region does not flow more south than 3° N. The northern waters are diverted eastward either by the NBC retroflection or by the northern edge of the associated clockwise rings. The existence of subsurface mesoscale rings associated to the NBC retroflection is evidenced, without any signature in the surface layer, so confirming earlier numerical model outputs. These subsurface anticyclones, linked to the NBC/NBUC retroflection into the North Equatorial Undercurrent and the EUC, contribute to the transport of South Atlantic high salinity water into the Northern Hemisphere.

Impact of mesoscale eddies on salinity and CO2 ocean parameters in the western tropical Atlantic in February 2020

2021 ◽  
Author(s):  
Léa Olivier ◽  
Jacqueline Boutin ◽  
Nathalie Lefèvre ◽  
Gilles Reverdin ◽  
Peter Landschützer ◽  
...  
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Salinity Gradient ◽  
Sea Surface Salinity ◽  
Amazon River ◽  
Tropical Atlantic ◽  
Surface Salinity ◽  
The North ◽  
Brazil Current ◽  
North Brazil

<p>Large oceanic eddies are formed by the retroflection of the North Brazil Current (NBC) near 8°N in the western tropical Atlantic. The EUREC<sup>4</sup>A-OA/Atomic cruise took place in January - February 2020, and extensively documented two NBC rings. The NBC flows northward across the Equator and pass the mouth of the Amazon River, entraining fresh and nutrient-rich water along its nearshore edge. From December to March, the Amazon river discharge is low but a freshwater filament stirred by a NBC ring was nevertheless observed. The strong salinity gradient can be used to delineate the NBC ring during its initial phase and its westward propagation. Using satellite sea surface salinity and ocean color associated to in-situ measurements of salinity, temperature, dissolved inorganic carbon, alkalinity and fugacity of CO<sub>2</sub> we characterize the salinity and biogeochemical signature of NBC rings.</p>

scholarly journals Preliminary results of drift-bottle releases and recoveries in the Western Tropical Atlantic

1967 ◽  
Vol 16 (1) ◽  
pp. 13-22 ◽  
Author(s):  
Ellen F. Luedemann
Keyword(s):  
Surface Current ◽  
Northeastern Brazil ◽  
Brazilian Coast ◽  
Northern Coast ◽  
The North ◽  
Strong Current ◽  
North Brazil ◽  
Equatorial Current ◽  
The Caribbean ◽  
Area North

In February-March 1963, during the Equalant Operation for the ICITA program, 476 drift-bottles were released at the equatorial waters off the northern Brazilian coast (01ºS to 09ºN and 043ºW to 053ºW). Thirty-five, bottles were recovered (7,4%). Those were classed in five groups according to their different velocity ranges and areas of recovery (Trinidad Island; Lesser Antilles; Caribbean and Florida area; north Brazil; northeastern Brazil). The recoveries of bottles released within 300 nm off the northern and northeastern coast of Brazil confirmed a strong current along the north and northeast coast in northwestern direction (South Equatorial Current and branches). In late February-early March the bottles showed maximum velocities of this current (3,6 knots). The region off the northern coast of Brazil, between 05ºN and 09ºN up to 050ºW seems to have been under the influence of an eastward component of the surface current in this same period, while at late March this influence appears to have been weaker. In the region from Trinidad Island to Yucatan Peninsula the current seems to be stronger on the northeastern side of the Caribbean Sea.

Retroflections of the North Brazil Current during February 2002

2005 ◽  
Vol 52 (4) ◽  
pp. 647-667 ◽  
Author(s):  
Marlos Goes ◽  
Robert Molinari ◽  
Ilson da Silveira ◽  
Ilana Wainer
Keyword(s):  
The North ◽  
Brazil Current ◽  
North Brazil ◽  
North Brazil Current

scholarly journals Population structure of the New Zealand whelk, Cominella glandiformis (Gastropoda: Buccinidae), suggests sporadic dispersal of a direct developer

2020 ◽  
Vol 130 (1) ◽  
pp. 49-60
Author(s):  
Kirsten M Donald ◽  
Graham A McCulloch ◽  
Ludovic Dutoit ◽  
Hamish G Spencer
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
New Zealand ◽  
Genetic Structure ◽  
Geographic Area ◽  
Null Alleles ◽  
Phylogeographic Structure ◽  
Large Geographic Area ◽  
Oceanic Currents ◽  
Minimal Evidence

Abstract We examined phylogeographic structure in the direct-developing New Zealand endemic intertidal mud whelk, Cominella glandiformis. Two hundred and ninety-six whelks from 12 sites were collected from sheltered shores around New Zealand’s four largest islands (North Island, South Island, Stewart Island and Chatham Island), encompassing the geographical range of this species. Despite being direct developers, gene flow among C. glandiformis populations may occur over short distances by adult floating, and over larger distances by rafting of egg masses. Primers were developed to amplify variable microsatellite regions at six loci. All loci were variable, with 8–34 alleles/loci. Observed and expected heterozygosities were high across all alleles, with minimal evidence of null alleles. The average number of alleles varied from 3.5 (Chatham Island) to 7.5 (Waitemata Harbour). Strong genetic structure was evident, with distinct ‘eastern’ and ‘western’ groups. Each group extended over a large geographic area, including regions of unsuitable habitat, but were linked by oceanic currents. We suggest that the intraspecific geographic genetic structure in C. glandiformis has arisen due a combination of ocean currents (promoting gene flow between geographically distant regions) and upwelling areas (limiting gene flow between certain regions).

scholarly journals On the propagation and decay of North Brazil Current rings

2010 ◽  
Vol 115 (C10) ◽  
Author(s):  
Kerstin Jochumsen ◽  
Monika Rhein ◽  
Sabine Hüttl-Kabus ◽  
Claus W. Böning
Keyword(s):  
Brazil Current ◽  
North Brazil ◽  
North Brazil Current ◽  
North Brazil Current Rings
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