Caribbean Surface Water Research Articles

Water masses in the Caribbean Sea and sub-annual variability in the Guajira upwelling region

The study of water masses is important as they transport water properties affecting the biosphere and ocean dynamics. In this study, we revisit water masses in the Caribbean Sea using climatology and 11 months of observations at different depths from 3 moorings placed in the Guajira upwelling region, providing some new findings. The Caribbean Surface Water (CSW) seasonal variability is studied at the mixed layer depth. Salinity differences between CSW and the saltier North Atlantic Subtropical Underwater (SUW) determine static stability spatial and temporal variations, with implications for regional ocean dynamics. Besides, we assess the climatologic distribution of water masses below the salinity maximum using the optimum multiparameter analysis and the Thermodynamic Equation of Seawater 2010, defining their source water indices when entering the Caribbean Sea. The SUW, with its core at ~ 150 m depth, occupies 16% of the Caribbean Sea volume, complemented by 38% of Antarctic Intermediate Water, with its core at ~ 700 m depth and North Atlantic Deep Water, which as bottom water occupies 46% of the volume. Hydrographic observations do not differ from climatology, regardless of their large sub-annual variations decreasing with depth. Daily time series of dominant water fractions at different depths correlate at each mooring, indicating a common forcing. Besides, rotated wind stress, which is an indicator of the Guajira upwelling, correlates regularly with water mass fractions down to 700 m depth. However, during strong wind shifts, upwelling seems to affect them down to 1450 m depth.

Physical and biogeochemical controls of the carbonate system of the Yucatan Shelf

The dynamics and distribution of the carbonate system and the processes that regulate it over the Yucatan Shelf (YS), a region of karst geology and high productivity that is influenced by submarine groundwater discharges (SGDs) and upwelling, were explored with data from two oceanographic cruises. The first oceanographic cruise was conducted in November 2015 during the Nortes season, a period of intense northerly wind activity, and a second cruise was conducted during the rainy season in August/September 2016. Notable biogeochemical differences were present between them. At the surface, Caribbean Surface Water (CSW) predominated over the shelf in both periods. During the Nortes cruise, a surface nearshore-offshore gradient showed high dissolved inorganic carbon (DIC; ∼2470 μmol kg−1) and total alkalinity (TA; ∼2460 μmol kg−1) values near the coast and average pHTotal and pCO2 values of 7.42 ± 0.10 and 2206 ± 546 μatm, respectively. These geochemical characteristics were attributed to the influence of SGDs, punctuated by relatively low δ13CDIC values between −4.18‰ and −2.49‰, which reflects an important oxidation of organic carbon and the dissolution of carbonate minerals. The presence of upwelled water on the eastern side of the YS showed average DIC and pHTotal values of 2260 ± 15 μmol kg−1 and 7.69 ± 0.08, respectively, which were lower than coastal values. During the rainy cruise, the advection of CSW by the Yucatan Current was traced by its thermohaline properties. However, the surface water carbonate system was relatively homogeneous, with average DIC, TA, pHTotal, and pCO2 values of 2047 ± 16 μmol kg−1, 2388 ± 11 μmol kg−1, 8.02 ± 0.02, and 440 ± 27 μatm, respectively. Lastly, the δ13CDIC values during this cruise ranged from −1.21‰ to 1.25‰, which suggests that the carbonate system is mainly regulated by organic matter production and respiration.

Understanding upper water mass dynamics in the Gulf of Mexico by linking physical and biogeochemical features

In the Gulf of Mexico (GoM), the upper 300 m of the water column contains a mixture of water types derived from water masses from the North Atlantic and the Caribbean Sea, namely Caribbean Surface Water (CSW), Subtropical Underwater (SUW), Gulf Common Water (GCW), and Tropical Atlantic Central Water (TACW). These are mainly altered by mesoscale processes and local evaporation, which modulate biogeochemical cycles. In this study, we improve our understanding of water mass dynamics by including biogeochemical data when evaluating the T-S relationship to define water-mass boundaries, particularly when the observed thermohaline characteristics overlap. The variables considered were apparent oxygen utilization (AOU), nitrate, and dissolved inorganic carbon (DIC). The data were obtained from eight cruises carried out in the central and southern regions of the GoM and an additional cruise that covered the entire coastal-ocean region. The new proposed boundaries were instrumental in clarifying the dynamics of surface waters. Of note, GCW on the western side of the GoM is not formed from the mixing of CSW and SUW but by the mixing of remnant CSW with TACW. In winter, a remnant of CSW mixed with GCW, and the biogeochemical composition of surface waters was affected, as observed from an increase in nitrate and DIC concentrations and positive AOU values. CSW was mainly detected at the surface during summer with negative AOU values, low DIC values, and almost undetectable nitrate concentrations. The presence or absence of CSW modulated the depth of the nitracline and likely influenced primary productivity.

Copepods of the off-shore waters of Caribbean Colombian Sea and their response to oceanographic regulators

AbstractSeven oceanographic expeditions were conducted between the years 2013 and 2018 to determine the horizontal and vertical distribution schemes in the epipelagic and mesopelagic copepod community structure of the Caribbean Oceanic ecoregion (CAO) and the oceanographic variables that regulate it. Four indicator species are suggested for the North Equatorial Current and the Caribbean Surface Water (CSW) mass (Clausocalanus furcatus, Oncaea venusta, Temora stylifera and T. turbinate) and two indicator species for deep-water masses such as the Western North Atlantic Central Water (NACW) and the Antarctic Intermediate Water (AAIW) (Mormonilla phasma and Conaea rapax). The copepod assemblage responds to local oceanographic patterns that are regulated (24%) by the variability of dissolved oxygen and temperature in the water column. The horizontal structure of the copepod assemblage in offshore waters presented a spatial sectorization. Three zones were differentiated: (1) oceanic Colombian zone; (2) influence of the Magdalena River zone; and (3) offshore north-east zone. Water mass mixing processes and migration mechanisms favour the homogeneity of the vertical assemblage of copepods in the CAO ecoregion. This study provides relevant information on the structure and density of copepod species, providing key information to describe the ecological processes and the different responses to the oceanographic factors that modulate them.

Horizontal and vertical distribution of cephalopod paralarvae in the Mesoamerican Barrier Reef System

AbstractHorizontal and vertical distribution of cephalopod paralarvae (PL) from the Mesoamerican Barrier Reef System (MBRS) in the Western Caribbean was studied during two oceanographic cruises in 2006 and 2007. A total of 1034 PL belonging to 12 families, 22 genera, 24 species, 5 morphotypes and a species complex were identified. Abralia redfieldi, Onychoteuthis banksii and Ornithoteuthis antillarum were the most abundant taxa. The taxonomic identification from these three species was corroborated with DNA barcoding (99.8–100% of similarity). Paralarvae of Octopus insularis were reported for the first time in the wild. Most PL occupied the Caribbean Surface Water mass in the 0–25 m depth stratum. Largest paralarval abundances were related to local oceanographic features favouring retention such as the Honduras Gyre and Cozumel eddy. No day-night differences were found in PL abundance, although Abralia redfieldi showed evidence of diel vertical migration. Distribution of PL in epipelagic waters of the MBRS was probably related to ontogenetic migration, hydrographic features of meso and subscale, and to the circulation regimes dominated by the Yucatan Current. The MBRS represents an important dispersion area for PL, potentially connecting a species-rich Caribbean community with the Gulf of Mexico and Florida waters.

Dynamics of physicochemical variables of the northern Colombian Caribbean coastal waters

This study explored oceanographic dynamics related to high productivity processes in the northern Colombian Caribbean. Four scientific expeditions were carried out between May and December 2018, where selected physicochemical variables were measured using a CTDO (conductivity, temperature and dissolved oxygen sensor system), and transparency with a Secchi disc. May and December showed typical upwelling waters, while August and November showed waters characteristic of the rainy season. Spatial dynamics were related to temperature and salinity. Thus, northeastern stations showed colder and saltier surface waters compared to those located to the southwest. Vertical readings were taken and the Caribbean Surface Water mass was identified, and below it the subtropical subsurface water mass, which emerges at the beginning of the year. The results suggest that upwelling and freshwater runoff have a direct impact on the hydrographic structure of the region.

Vertical Structure of the Water Column at the Virgin Islands Shelf Break and Trough

The steep US Virgin Islands Shelf Break (VISB) and the Virgin Islands Trough (VIT) at the Northeastern Caribbean Sea comprise a dynamic region of the Atlantic Ocean. In situ oceanographic data collected in the region during April 2017 were used to examine the spatial variability in temperature, density, salinity, and relative Chlorophyll-a. Analysis of data from the upper 300 m of the water column, that include deep and shallow water stations in the shelf break region, shows strong stratification of the water column. Stations shallower than 800 m along the shelf break are more variable in temperature, density, and salinity than those that are deeper than 800 m along the trough. For shallow stations, the mixed layer depth deepens along-shelf from West to East while at the deep stations the opposite occurs. Salinity maxima exhibit more variability in depth and range of values in the shallow stations compared to deep stations. Six different types of water masses that contribute to the strong stratification in the region were identified in our study: Caribbean Surface Water, Subtropical Underwater, Sargasso Sea Water, Tropical Atlantic Central Water, Antarctic Intermediate Water, and North Atlantic Deep Water. The upper level Caribbean Surface Water, Subtropical Underwater, and Sargasso Sea Water are present in shallow stations, indicating potential meridional intrusions from the VIT to the VISB which may not be resolved by current ocean circulation models and are not captured in satellite data. The analysis presented here indicates that competing physical processes may be controlling the vertical structure of the water column in the region and merit further examination.

Hydrography of the Central and Western Gulf of Mexico

AbstractThis study describes in detail the water masses of the Gulf of Mexico (GoM) west of 88°W based on their thermohaline properties and dissolved oxygen concentration. The existent historical information is complemented with new data from 14 cruises, Argo floats, and over one year of continuous glider monitoring. The results describe the general hydrography of the central and western GoM with focus on the difference between the water properties inside and outside Loop Current Eddies (LCEs). Caribbean Surface Water, Subtropical Underwater, and 18 °C Sargasso Sea Water (18SSW) are exclusive of the LCEs, and they are found along the LCEs preferred path between 23°N and 27°N. Outside the LCEs, the prominent characteristics of these water masses erode, and the Gulf Common Water is ubiquitous in the subsurface. It is shown that the water masses in the GoM need to be described in the frame of the dominant mesoscale features that take place there and that the dissolved oxygen is a key variable to identify some water masses of Caribbean origin as the Tropical Atlantic Central Water and the 18SSW. The previous potential temperature and salinity limits of the water masses within the GoM were revised and redefined in terms of absolute salinity and conservative temperature in the frame of the Thermodynamic Equation of Seawater, 2010 (TEOS‐10). While temperature values after conversion have little variation compared to the previous ones, the absolute salinity is in average 0.2 units greater than the former practical salinity.

Condiciones hidrográficas y climatológicas en el Caribe Sur de Costa Rica durante El Niño 2014-2016

En mayo, junio, septiembre y octubre del año 2014 y junio, agosto, septiembre y noviembre del año 2015, se realizaron campañas hidrográficas en el Caribe Sur de Costa Rica, con el objetivo de determinar la influencia del fenómeno de El Niño sobre esta región. Con un perfilador se determinó en 23 estaciones la temperatura, la salinidad y la clorofila a. La temperatura superficial se ubicó entre 26.6 y 30°C, las salinidades superficiales entre 29-33.5 UPS y la clorofila a superficial varió entre 1.1 mg m-3 y 0.1 mg m-3. Existe una capa de mezcla delgada (T ~ 29°C), la cual no sobrepasó los 20 m de profundidad en el 2014 y se extendió hasta los 40 m en septiembre y noviembre del año 2015. Los índices termohalinos del Agua Superficial del Caribe presentaron una disminución considerable en su salinidad por dilución debido a El Niño y un ligero aumento en su temperatura. El análisis entre una serie temporal de la temperatura superficial del mar en un punto situado 15 km frente a Cahuita y el Índice Oceánico de El Niño (ONI) determinaron que la zona estudiada presenta una señal de calentamiento con un desfase de 7 meses posterior a la presencia de El Niño en el Océano Pacífico Tropical. Durante El Niño 2014-2016 el área de estudio presentó en algunos meses un exceso en las precipitaciones que superó el valor de la norma climatológica en más de un 50%.

Freshwater exchanges and surface salinity in the Colombian basin, Caribbean Sea.

Despite the heavy regional rainfall and considerable discharge of many rivers into the Colombian Basin, there have been few detailed studies about the dilution of Caribbean Surface Water and the variability of salinity in the southwestern Caribbean. An analysis of the precipitation, evaporation and runoff in relation to the climate variability demonstrates that although the salt balance in the Colombian Basin overall is in equilibrium, the area south of 12°N is an important dilution sub-basin. In the southwest of the basin, in the region of the Panama-Colombia Gyre, Caribbean Sea Water is diluted by precipitation and runoff year round, while in the northeast, off La Guajira, its salinity increases from December to May by upwelling. At the interannual scale, continental runoff is related to El Niño Southern Oscillation, and precipitation and evaporation south of 12°N are related to the Caribbean Low Level Jet. During El Niño years the maximum salinification occurs in the dry season (December-February) while in La Niña years the maximum dilution (or freshening), reaching La Guajira Coastal Zone, occurs in the wet season (September-November).

Pathways and hydrography in the Mesoamerican Barrier Reef System Part 2: Water masses and thermohaline structure

Hydrographic data from two oceanographic cruises conducted during March 2006 and January/February 2007 are used to investigate the thermohaline structure related to the observed circulation along the Mesoamerican Barrier Reef System (MBRS). From our observations we identify three water masses in the MBRS: the Caribbean Surface Water (CSW), North Atlantic Subtropical Underwater (SUW), and Tropical Atlantic Central Water (TACW). Little vertical structure in temperature is observed in the upper 100m of the water column, but important differences are observed in the salinity distribution both horizontally and with depth. Freshwater inputs to the system from the mainland can be traced in the surface layer, with two possible sources: one from surface rivers located along the southern portion of the MBRS, and the other originating from an underground river system located along the northern portion of the MBRS. The thermohaline structure in the MBRS reflects the dynamics of the observed circulation. Uplifted isopycnals along most of the central and northern coastline of the MBRS reflect the effects of the strong geostrophic circulation flowing northward, i.e. the Yucatan Current. To the south along the MBRS, much weaker velocities are observed, with the Honduras Gyre dominating the flow in this region as presented during January/February 2007. These two regions are separated by onshore and divergent alongshore flow associated with the impingement of the Cayman Current on the shore and the MBRS.

Amazon River water in the northeastern Caribbean Sea and its effect on larval reef fish assemblages during April 2009

AbstractDuring April to June 2009, a large bolus of Amazon River water impacted the northeastern Caribbean Sea. Shipboard observations collected near Saba Bank, the U.S. and British Virgin Islands, and the Anegada Passage showed low surface salinity (35.76 ± 0.05 Practical Salinity Unit (PSU)), elevated surface temperature (26.77 ± 0.14°C), high chlorophyll‐a (1.26 ± 0.21 mg m−3) and high dissolved oxygen (4.90 ± 0.06 mL L−1) in a 20‐ to 30‐m thick surface layer in the riverine plume. The water was ~1°C warmer, 1 PSU fresher, 0.3 mL L−1 higher in oxygen and 1.2 mg m−3 higher in chlorophyll‐a than Atlantic Ocean waters to the north, with Caribbean surface waters showing intermediate values. Plankton net tows obtained in the upper 100 m of the water column revealed larval fish assemblages within the plume that were significantly different from those of the surrounding waters and from those encountered in the area in previous years. The plume waters contained higher concentrations of mesopelagic fish larvae from the families Myctophidae and Nomeidae, which as adults typically inhabit offshore, deep water habitats. Concentrations of larvae from inshore and reef‐associated families such as Scaridae, Serranidae, Labridae and Clupeidae were lower than those found outside the plume in similar shallow areas, particularly in near‐surface waters. An event like the one observed in 2009 had not been documented in at least the past 30 yr, and yet it was followed by another similarly extreme event in 2010. The ecological implications, including any long‐term consequences of such recent extreme events, are important and merit further study.

Influence of the Orinoco River on the primary production of eastern Caribbean surface waters

Key Points River plume increases primary production of eastern Caribbean waters. Climate fluctuations are observed in remote sensed primary production. River plume coverage and seasonality influences primary production gradients.

Foraminiferal Mg/Ca increase in the Caribbean during the Pliocene: Western Atlantic Warm Pool formation, salinity influence, or diagenetic overprint?

We constructed a high‐resolution Mg/Ca record on the planktonic foraminifer Globigerinoides sacculifer in order to explore the change in sea surface temperature (SST) due to the shoaling of the Isthmus of Panama as well as the impact of secondary factors like diagenesis and large salinity fluctuations. The study covers the latest Miocene and the early Pliocene (5.6–3.9 Ma) and was combined with δ18O to isolate changes in sea surface salinity (SSS). Before 4.5 Ma, SSTMg/Ca and SSS show moderate fluctuations, indicating a free exchange of surface ocean water masses between the Pacific and the Atlantic. The increase in δ18O after 4.5 Ma represents increasing salinities in the Caribbean due to the progressive closure of the Panamanian Gateway. The increase in Mg/Ca toward values of maximum 7 mmol/mol suggests that secondary influences have played a significant role. Evidence of crystalline overgrowths on the foraminiferal tests in correlation with aragonite, Sr/Ca, and productivity cyclicities indicates a diagenetic overprint on the foraminiferal tests. Laser ablation inductively coupled plasma–mass spectrometry analyses, however, do not show significantly increased Mg/Ca ratios in the crystalline overgrowths, and neither do calculations based on pore water data conclusively result in significantly elevated Mg/Ca ratios in the crystalline overgrowths. Alternatively, the elevated Mg/Ca ratios might have been caused by salinity as the δ18O record of Site 1000 has been interpreted to represent large fluctuations in SSS, and cultivating experiments have shown an increase in Mg/Ca with increasing salinity. We conclude that the Mg/Ca record <4.5 Ma can only reliably be considered for paleoceanographical purposes when the minimum values, not showing any evidence of secondary influences, are used, resulting in a warming of central Caribbean surface water masses after 4.5 Ma of ∼2°C.

Iron fertilization of Trichodesmium off the west coast of Barbados: A one-dimensional numerical model

A one-dimensional quasi-Eulerian model, describing the biological and chemical interactions of autotrophic and heterotrophic plankton populations within the upper 100 m of the water column, was used to explain the relative impact of iron fertilization from Saharan dust on phosphorus cycling by the cyanobacterium, Trichodesmium spp. We examined the Caribbean surface waters off the west coast of Barbados using seasonal cases of dust delivery (summer peak) in relation to periods of elevated phosphorus stocks found in episodic pulses of Amazon River water advected past Barbados by the Guiana Current. The additional iron and phosphorus supplied by fluvial sources, available after biological depletion of nitrogen, could alleviate the growth limitation of Trichodesmium far downstream of the river plumes. The model results were compared with measurements made of Trichodesmium stocks 8 km off the west coast of Barbados. Modeled concentrations within the low-salinity Amazon plumes reached ∼7.4 mg chl m −2, as seen at Barbados. In the absence of the low-salinity signal, the Trichodesmium biomass shifted to phosphorus limitation with little response to iron fertilization. This indicates that Trichodesmium stocks may indeed be mainly a function of phosphorus availability within the upper water column. Therefore, the supply of phosphorus from subtropical/tropical rivers, such as the Amazon and Orinoco, limits the potential cyanophyte response, despite adequate atmospheric iron delivery. This alters our view not only of the western North Atlantic nitrogen budget, but potentially several regions downstream of low N:P river systems.

Century‐scale movement of the Atlantic Intertropical Convergence Zone linked to solar variability

The abundance of the planktic foraminifer Globigerinoides sacculifer in Gulf of Mexico (GOM) sediments is a proxy for the influx of Caribbean surface waters (the Loop Current) into the GOM. Penetration of the Loop Current into the GOM is related to the position of the Intertropical Convergence Zone (ITCZ): northward migration of the ITCZ results in increased incursion of the Loop Current into the GOM; southward migration of the ITCZ results in decreased penetration of the Loop Current into the GOM. Abundance variations of G. sacculifer in a sediment core from the Pigmy Basin in the GOM show distinct century‐scale cyclicity over the last 5,000 years. The periodicity of these abundance variations is similar to the century‐scale periodicity observed in proxy records of solar variability, which suggests that the average position of the ITCZ and thus Holocene century‐scale variability in the Caribbean‐GOM region is linked to solar variability.

Millennial‐ to century‐scale variability in Gulf of Mexico Holocene climate records

Proxy records from two piston cores in the Gulf of Mexico (GOM) provide a detailed (50–100 year resolution) record of climate variability over the last 14,000 years. Long‐term (millennial‐scale) trends and changes are related to the transition from glacial to interglacial conditions and movement of the average position of the Intertropical Convergence Zone (ITCZ) related to orbital forcing. The δ18O of the surface‐dwelling planktic foraminifer Globigerinoides ruber show negative excursions between 14 and 10.2 ka (radiocarbon years) that reflect influx of meltwater into the western GOM during melting of the Laurentide Ice Sheet. The relative abundance of the planktic foraminifer Globigerinoides sacculifer is related to transport of Caribbean water into the GOM. Maximum transport of Caribbean surface waters and moisture into the GOM associated with a northward migration of the average position of the ITCZ occurs between about 6.5 and 4.5 ka. In addition, abundance variations of G. sacculifer show century‐scale variability throughout most of the Holocene. The GOM record is consistent with records from other areas, suggesting that century‐scale variability is a pervasive feature of Holocene climate. The frequency of several cycles in the climate records is similar to cycles identified in proxy records of solar variability, indicating that at least some of the century‐scale climate variability during the Holocene is due to external (solar) forcing.

Late Pliocene Caribbean surface water dynamics and climatic changes based on calcareous nannofossil records

Quantitative analyses of nannofossil assemblages from two ODP sites were performed to determine changes in the surface water structure in the Caribbean Sea and implications for climatic changes during the late Pliocene. Analysis was made by calculation of accumulation rates and division of nannofossils into ecological groups based on their depth distributions and trophic regime (oligotrophic vs eutrophic). Between 3.5 and 2.7 Ma, separate surface water masses existed in the northern and southern Caribbean. The northern surface water was strongly oligotrophic, with a deep thermocline/nutricline. Prior to 3.1 Ma, the southern Caribbean was characterized by a shallower thermocline/nutricline with minor upwelling induced by the presence of the past ITCZ (Intertropical Convergence Zone). After 3.1 Ma, the thermocline/nutricline deepened in the southern Caribbean and the upper water became oligotrophic as a result of the completion of the closure of the Isthmus. After an episodic invasion of cooler surface waters associated with high-latitude cooling at approximately 2.7 Ma, coccolith productivity in the Caribbean was at its lowest. A deep thermocline existed between 2.7 and 2.4 Ma and nutrient-depleted waters spread on the SUW (Subtropical Under Water) in the Caribbean. After 2.4 Ma, the increase of terrigenous materials from the South American continent caused an abundance of eutrophic taxa. This suggests that recent climate systems were established due to the intensification of the northern hemisphere glaciation.

Seasonal variation of physical and biogeochemical features in eastern Caribbean Surface Water

We describe vertical and temporal variation of water mass structure, dissolved nutrients, phytoplankton chlorophyll a (Chl a), and dissolved organic matter south of the island of Puerto Rico at 67°W, 17°36′N with particular emphasis on variability of Caribbean Surface Water (CSW) features. CSW at the Caribbean Time Series (CaTS) station experiences yearlong continental riverine influence as evidenced by surface salinity consistently below that of Tropical Atlantic Surface Water and elevated silicate content. Salinity exhibits close correlation to average rainfall over the Orinoco River basin with a 3–4 month offset, and salinity and silicate are in turn closely correlated. Calculations using a simple mixing model and based on known end‐members for salinity and silicate indicate that rainwater accounts for 0–3.1% of CSW, while river water accounts for 0.6–5.5% at CaTS, indicating that surface waters of the NE Caribbean are under the influence of riverine water throughout the year. No significant correlation was found between salinity and phytoplankton Chl a, but the depth of the Chl a maximum was statistically correlated to seasonal salinity fluctuations. This observation may account for the apparent seasonal Chl a increase in these waters deduced from remote‐sensing estimates. Analysis of historical data shows that seasonal shoaling of the Chl a maximum results in a net increase in phytoplankton carbon biomass during the period of influence of the Orinoco River plume.

Water masses and circulation in the surface layers of the Caribbean at 66°W

A meridional hydrographic section was made in August–September 1997 at 66°W from the coast of Venezuela to Woods Hole aboard the R/V Knorr. In this report, we concentrate on near surface measurements in the Caribbean. The data show two distinct water masses with different origins. From approximately 14°N to Puerto Rico, Caribbean Surface Water and Subtropical Under Water with their source in the North Atlantic are found, as previously observed. From Venezuela to approximately 13°N, a less saline water mass with its source in the Tropics and South Atlantic is found. Within the southern portion of the section, two different velocity patterns are observed, namely, an eastward flow with a subsurface maximum near the coast of Venezuela, and a surface intensified westward jet with Velocities of 130 cm s−1 in midbasin.