Environmental factors controlling the phytoplankton blooms at the Patagonia shelf-break in spring

Tavano, Virgínia Maria; Garcia, Carlos Alberto Eiras; Mata, Maurício M.; Pollery, Ricardo; Piola, Alberto R.; Signorini, Sérgio R.; McClain, Charles R.; Iglesias‐Rodríguez, M. Débora

doi:10.1016/j.dsr.2008.04.011

Cited by 104 publications

(92 citation statements)

References 48 publications

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“…These high Csat concentrations have been verified by in-situ determinations (>11 mg m −3 , e.g. Garcia et al, 2008;Bianchi et al, 2009). Given the proper light and stratification conditions, inshore intrusions of nutrient-rich Malvinas Current waters may act to promote or enhance the growth of phytoplankton over the continental shelf.…”

Section: Impact Of Slope Water Intrusionsmentioning

confidence: 97%

Malvinas-slope water intrusions on the northern Patagonia continental shelf

et al. 2010

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Abstract. The Patagonia continental shelf located off southeastern South America is bounded offshore by the Malvinas Current, which extends northward from northern Drake Passage (∼55 • S) to nearly 38 • S. The transition between relatively warm-fresh shelf waters and Subantarctic Waters from the western boundary current is characterized by a thermohaline front extending nearly 2500 km. We use satellite derived sea surface temperature, and chlorophyll-a data combined with hydrographic and surface drifter data to document the intrusions of slope waters onto the continental shelf near 41 • S. These intrusions create vertically coherent localized negative temperature and positive salinity anomalies extending onshore about 150 km from the shelf break. The region is associated with a center of action of the first mode of nonseasonal sea surface temperature variability and also relatively high chlorophyll-a variability, suggesting that the intrusions are important in promoting the local development of phytoplankton. The generation of slope water penetrations at this location may be triggered by the inshore excursion of the 100 m isobath, which appears to steer the Malvinas Current waters over the outer shelf.

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Section: Impact Of Slope Water Intrusionsmentioning

confidence: 97%

Malvinas-slope water intrusions on the northern Patagonia continental shelf

et al. 2010

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“…The peaks of this maximum are unusually high. Spring blooms, for example, have surface values of 25-30 mg/m 3 , which are an order of magnitude larger than those observed in typical offshore locations (e.g., Acha et al, 2004;Romero et al, 2006;Garcia et al, 2008;Signorini et al, 2009). The chlorophyll blooms of the MC are symptomatic of the upwelling of nutrient-rich waters to the surface, but the mechanisms driving such upwelling are still poorly understood.…”

Section: The Influence Of the MC On The Patagonian Shelfmentioning

confidence: 99%

The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation

2010

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Abstract. The oceanic circulation over the southwestern Atlantic shelf is influenced by large tidal amplitudes, substantial freshwater discharges, high wind speeds and -most importantly -by its proximity to two of the largest western boundary currents of the world ocean: the Brazil and Malvinas currents. This review article aims to discriminate the dynamical processes controlling the interaction between this extensive shelf region and the deep-ocean. The discussion is focused on two broad regions: the South Brazil Bight to the north, and Patagonia to the south. The exchanges between the Brazil Current and the South Brazil Bight are characterized by the intermittent development of eddies and meanders of the Brazil Current at the shelfbreak. However, it is argued that this is not the only -nor the most important -influence of the Brazil Current on the shelf. Numerical simulations show that the thermohaline structure of the South Brazil Bight can be entirely ascribed to steady state, bottom boundary layer interactions between the shelf and the Brazil Current. The Malvinas Current does not show the development of eddies and meanders, but its influence on the Patagonian shelf is not less important. Models and observations indicate that the Malvinas Current not only controls the shelfbreak dynamics and cross-shelf exchanges but also influences the circulation in the shelf's interior.

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“…More recently, iron has been shown to control the distribution and growth of coccolithophores in the Great Calcite Belt (Balch et al, 2016) in the Southern Hemisphere. Furthermore, iron supplied through sedimentary sources has also been suggested to influence the formation of the Patagonian Shelf coccolithophore bloom, which occurs in cold, macronutrient-rich water originating north of the SAF (Garcia et al, 2008;Poulton et al, 2013;Balch et al, 2014Balch et al, , 2016. Clearly more work is required to examine the role of iron on Southern Ocean coccolithophore biogeography and calcification, as well as its potential influence on coccolithophore blooms and coccolithophore growth in mixed communities.…”

Section: Environmental Drivers Of Coccolithophores and Calcificationmentioning

confidence: 99%

Environmental drivers of coccolithophore abundance and calcification across Drake Passage (Southern Ocean)

et al. 2016

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Abstract. Although coccolithophores are not as numerically common or as diverse in the Southern Ocean as they are in subpolar waters of the North Atlantic, a few species, such as Emiliania huxleyi, are found during the summer months. Little is actually known about the calcite production (CP) of these communities or how their distribution and physiology relate to environmental variables in this region. In February 2009, we made observations across Drake Passage (between South America and the Antarctic Peninsula) of coccolithophore distribution, CP, primary production, chlorophyll a and macronutrient concentrations, irradiance and carbonate chemistry. Although CP represented less than 1 % of total carbon fixation, coccolithophores were widespread across Drake Passage. The B/C morphotype of E. huxleyi was the dominant coccolithophore, with low estimates of coccolith calcite ( ∼ 0.01 pmol C coccolith −1 ) from biometric measurements. Both cell-normalised calcification (0.01-0.16 pmol C cell −1 d −1 ) and total CP (< 20 µmol C m −3 d −1 ) were much lower than those observed in the subpolar North Atlantic where E. huxleyi morphotype A is dominant. However, estimates of coccolith production rates were similar (0.1-1.2 coccoliths cell −1 h −1 ) to previous measurements made in the subpolar North Atlantic. A multivariate statistical approach found that temperature and irradiance together were best able to explain the observed variation in species distribution and abundance (Spearman's rank correlation ρ = 0.4, p < 0.01). Rates of calcification per cell and coccolith production, as well as community CP and E. huxleyi abundance, were all positively correlated (p < 0.05) to the strong latitudinal gradient in temperature, irradiance and calcite saturation states across Drake Passage. Broadly, our results lend support to recent suggestions that coccolithophores, especially E. huxleyi, are advancing polewards. However, our in situ observations indicate that this may owe more to sea-surface warming and increasing irradiance rather than increasing CO 2 concentrations.

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Environmental factors controlling the phytoplankton blooms at the Patagonia shelf-break in spring

Cited by 104 publications

References 48 publications

Malvinas-slope water intrusions on the northern Patagonia continental shelf

Malvinas-slope water intrusions on the northern Patagonia continental shelf

The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation

Environmental drivers of coccolithophore abundance and calcification across Drake Passage (Southern Ocean)

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