Impacts of mesoscale eddies on the nitrate distribution in the deep-water region of the Gulf of Mexico

Lee-Sánchez, Erika; Camacho-Ibar, Víctor F.; Velásquez-Aristizábal, Jorge A.; Valencia-Gasti, José A.; Samperio-Ramos, Guillermo

doi:10.1016/j.jmarsys.2022.103721

Cited by 14 publications

(13 citation statements)

References 61 publications

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“…In the upper layer where CSWr and NASUW dominated, nitrate was depleted due to phytoplankton consumption and DO showed concentrations greater than 190 μmol/kg. Below the mixed layer, at depths of 31–68 m, concentrations were >202 μmol/kg, which were above DO saturation and corresponded to a subsurface maximum that probably resulted from photosynthetic activity (Lee‐Sánchez et al., 2022). Below the nitrate‐depleted layer, an oxycline delimited by concentration values decreasing from 190 to 130 μmol/kg and a nitracline delimited by concentration values increasing from ∼0.5 to 7 μmol/kg were observed.…”

Section: Discussionmentioning

confidence: 99%

Water Mass Structure and Mixing Fractions in the Deepwater Region of the Gulf of Mexico

Valencia-Gasti¹,

Camacho-Ibar²,

Herguera

2022

JGR Oceans

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The Gulf of Mexico (GoM) is a semienclosed system that includes a semipermanent cyclonic eddy in the Bay of Campeche and anticyclonic circulation in the central and western regions (Nowlin et al., 2000;Pérez-Brunius et al., 2013;Tenreiro et al., 2018). These circulation patterns are associated with the interactions among rotational wind stress, the bathymetry, and anticyclonic Loop Current eddies (LCEs) that detach from the Loop Current (LC) within the gulf. These LCEs have diameters of ∼300 km and separate from the LC in the eastern region of the gulf every 5-19 months, advecting waters from the Caribbean toward the central and western regions of the GoM (

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Section: Discussionmentioning

confidence: 99%

Water Mass Structure and Mixing Fractions in the Deepwater Region of the Gulf of Mexico

Valencia-Gasti¹,

Camacho-Ibar²,

Herguera

2022

JGR Oceans

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“…It is worth comparing the sinking flux of POC and T 100 in the Kuroshio region to those in the Gulf of Mexico. In the Gulf of Mexico, mesoscale activities driven by the Loop Current and the eddies affects hydrography and biogeochemistry in the oligotrophic environments (Green et al, 2014;Stukel et al, 2021;Lee-Sańchez et al, 2022). Similarly, diverse routes of nutrient supply along the Kuroshio Current, including diapycnal turbulent mixing, windor tide-induced near-inertial internal waves, and doublediffusive convection, support higher primary productivity in the Kuroshio Current area relative to the subtropical gyre (Nagai et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

et al. 2022

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The biological pump that transports carbon from the surface ocean to the ocean interior is an important determinant of ocean carbon absorption from the atmosphere, and of biological activity beneath the euphotic zone. Various factors influence the magnitude and efficiency of this biological pump, such as primary production, particle size, and the composition of consumers of particulate organic carbon (POC). The complex factors influencing the biological pump induce high regional and temporal variability; however, the mechanisms of this variability are not understood and its causes remain unclear. The size of sinking particles has been hypothesized to affect the attenuation of POC flux via reduction of residence time within the water column. Here, we conducted sediment trap experiments in slope and subtropical gyre areas along the Kuroshio in the subtropical North Pacific. The ratio of POC flux at a depth 100 m below the base of the euphotic zone to that at the base of the euphotic zone (T100) varied from 0.307 to 0.646 and from 0.090 to 0.958 in the slope and subtropical gyre areas, respectively, and was positively correlated with variations in the volume-weighted mean particle diameter (Spearman rank order correlation coefficient: 0.700, p< 0.05, n = 9). However, the variation in T100 was not correlated with ambient water temperature (p > 0.05). The results support the hypothesis that attenuation of POC flux is influenced by the size of sinking particles in oligotrophic oceanic areas.

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“…In general, these mesoscale structures are responsible for much of the physical dynamics at the surface inside the Gulf, while diurnal tidal forcing plays a much smaller role (tidal amplitudes are low and range from 11-17 cm; Kantha, 2005). It should be noted that LC anticyclonic eddies strongly impact the chemical and biological characteristics of the surface waters of the GoM given that they introduce warm and nutrient-depleted Caribbean waters and consequently affect primary productivity (e.g., Biggs, 1992;Linacre et al, 2015;Lee-Sańchez et al, 2022). On the contrary, cyclonic eddies, which develop as counterparts to the anticyclonic eddies (Oey et al, 2005), can overcome the thermal barrier created by highly stratified surface waters during the warm months of summer (Portela et al, 2018).…”

Section: Study Areamentioning

confidence: 99%

“…Concentrations of PO 4 and NO 3 in water samples were determined using wet chemical colorimetry (Armstrong et al, 1967;Gordon et al, 1993;Lee-Sańchez et al, 2022) with an AA3-HR segmented flow autoanalyzer (Seal Analytical, Fareham, UK). Analytical precision and accuracy were obtained by repeated measurements of the SCOR-JAMSTEC certified reference material (Lots CD and CC; Kanso Co. Ltd., Osaka, Japan).…”

Section: Analysis Of Macronutrients (Po 4 and No 3 )mentioning

confidence: 99%

“…Hence, these mesoscale eddies are able to control the flux and availability of bioessential elements for primary producers that inhabit the surface waters of the GoM. In fact, it has recently been demonstrated that mesoscale eddies can modulate the inorganic nitrogen stock in the first 200 m under conditions of high stratification, which provides compelling evidence of the impacts of mesoscale dynamics on the euphotic zone of the GoM (Lee-Sańchez et al, 2022;Velaśquez-Aristizabal et al, 2022). Thus, given their capabilities to generate mixing and vertical fluxes, mesoscale eddies should potentially have a strong control over the supply of Ni (and other elements with nutrient-like distributions) to surface waters and, consequently, on its availability to primary producers in the GoM.…”

Section: Introductionmentioning

confidence: 96%

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Spatial variability of dissolved nickel is enhanced by mesoscale dynamics in the Gulf of Mexico

et al. 2023

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The Gulf of Mexico (GoM) is one of the most dynamic marginal seas in the world owing to the intrusion of the Loop Current and the shedding of anticyclonic eddies (LCE) that travel westward across the Gulf. However, the impacts of these mesoscale dynamics on the supply and removal of bioessential trace metals in surface waters remain unclear. We study the impact of mesoscale eddies on the distribution of dissolved nickel (Ni), a biologically active element scarcely studied in the region. The vertical distribution of Ni was determined in the deep-water region of the GoM during summer of 2017, when two anticyclonic LCE (Quantum and Poseidon) were present. Nutrient-like profiles of Ni in the GoM resemble those from the Atlantic Ocean, but they showed high spatial variability within the first 1000 m, which was associated with the impact of mesoscale eddies. Similarly to subtropical gyres, macronutrients were almost depleted in surface waters, while Ni never fell below 1.51 nmol kg-1, suggesting low Ni lability or alternatively, slow biological uptake compared to that of macronutrients. In particular, lowest levels of Ni and macronutrients (PO4 and NO3) were recorded in surface waters of the anticyclonic eddies and the Loop Current area. Anticyclonic LCEs deepened these Ni-poor waters pushing the Ni-rich core of Tropical Atlantic Central Water up to 600 m, whereas its shallowest position (up to 200 m) was recorded under cyclonic conditions in Campeche Bay. This eddy-induced vertical displacement of water masses also affected the integrated Ni and macronutrient concentrations in the upper 350 m but without modifying their stoichiometries. We suggest that a significant decrease in surface inventories of Ni and macronutrient in areas impacted by LCEs is a consequence of the trapping of the water within eddies, the biological uptake of Ni and macronutrients combined with their limited replenishment from below, which likely affects autotrophic groups. In conclusion, the mesoscale dynamic permanently present in the GoM play an important role in modifying the vertical distribution of Ni and macronutrients as well as their availability in the upper water column of this marginal sea.

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Impacts of mesoscale eddies on the nitrate distribution in the deep-water region of the Gulf of Mexico

Cited by 14 publications

References 61 publications

Water Mass Structure and Mixing Fractions in the Deepwater Region of the Gulf of Mexico

Water Mass Structure and Mixing Fractions in the Deepwater Region of the Gulf of Mexico

Temporal and regional variabilities in the attenuation of sinking particulate organic carbon in the Kuroshio region

Spatial variability of dissolved nickel is enhanced by mesoscale dynamics in the Gulf of Mexico

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