Multiannual trends in fronts and distribution of nutrients and chlorophyll in the southwestern Atlantic (30-62°S)

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: Pereira Brandini, Frederico, Boltovskoy, Demetrio, Piola, Alberto Ricardo, Kocmur, Santiago, Röttgers, Rüdiger, Cesar Abreu, Paulo, Mendes Lopes, Rubens
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd
• Subjects: Brazil-Malvinas Confluence Zone; Chlorophyll; Nutrients; Polar Front; Southwestern Atlantic; Thermal Fronts; https://purl.org/becyt/ford/1.5; https://purl.org/becyt/ford/1; Antarctic; The Antarctic; Austral; Argentina; Ricardo; Armada Argentina; Antarc*
• Online Access: http://hdl.handle.net/11336/71703

This paper presents the first data on the vertical distribution of chlorophyll and nutrients in the upper layers of the southern southwestern Atlantic and interprets it in relation to frontal systems and the general hydrographic features. The survey covered quasi-synoptically the area between 30 and 62°S, at the beginning of the austral summers of three consecutive years (1993 through 1995). Our results show a rather consistent oceanographic structure, with similar patterns of chlorophyll and nutrient distributions with latitude. Outstanding features present throughout the three seasons are two zones of high phytoplankton production, where chlorophyll concentrations of > 1 μg/l seem to occur frequently. The first is the upper euphotic zone of the Brazil-Malvinas Confluence Zone between approximately 36 and 50°S. The second is centered on subsurface layers of the Antarctic Surface Water south of the Polar Front as far as 62°S. The rest of the area covered shows low chlorophyll concentrations (< 0.4 μg/l), due either to nutrient limitation in the oligotrophic subtropical waters of the Brazil Current or to excessive turbulence and upper-layer instability in the energetic Malvinas Current. The occurrence of a permanent meander around 38°S coincided with the cyclonic retroflexion of the Malvinas Current, causing upwelling of deep water. The ecological implications of this eddy-induced upwelling are discussed. (C) 2000 Elsevier Science Ltd. Fil: Pereira Brandini, Frederico. Universidade Federal do Paraná; Brasil Fil: Boltovskoy, Demetrio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Piola, Alberto Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina ...