Role of plankton communities in sea–air variations in pCO2 in the SW Atlantic Ocean

Abstract

The influence of the plankton community structure on carbon dynamics was studied in the surface waters of the Argentinean continental shelf (SW Atlantic Ocean) in summer and fall 2002, 2003 and 2004. The horizontal changes in plankton community respiration (R), net community production (NCP) and gross primary production (GPP) were (1) compared with the difference in the partial pressure of CO 2 (pCO 2 ) between the sea surface and the atmosphere (ΔpCO 2 ), (2) compared with oxygen saturation and (3) related to the microscopic phytoplankton assemblages. This area, which has recently been shown to be a CO 2 sink, had an average surface oxygen saturation of 108.1%, indicating that net photosynthesis could have played a dominant role in the CO 2 dynamics. At most stations, the production:respiration (GPP:R) ratio was greater than 1, indicating that planktonic communities were autotrophic; the average GPP:R ratio for the whole study was 2.99. Phytoplankton biomass (chlorophyll a) and NCP showed an inverse relationship with ΔpCO 2 and a direct relationship with %O 2 saturation when phytoplankton assemblages were dominated by diatoms (30% of the stations). This was not the case when small (≤5 µm) flagellates were the most abundant organisms. Although NCP was mostly positive for both groups of stations (i.e. diatom-dominated or small flagellate-dominated), other physical and biological processes are thought to modify the CO 2 dynamics when small flagellates are the prevailing phytoplankton group.

Diversity of the diatom genus Fragilariopsis in the Argentine Sea and Antarctic waters: morphology, distribution and abundance

“…Productive areas, such as the Western Antarctic Peninsula (Walsh et al 2001;Garibotti et al 2003;Prézelin et al 2004), the Weddell Sea (Fryxell and Kendrick 1988), Prydz Bay (Kopczyńska et al 1995), the Bellingshausen Sea (Barlow et al 1998;van Leeuwe et al 1998) and the Ross Sea (Arrigo et al 1999), tend to be rich in diatoms (Kopczyńska et al 2007;Kozlowski 2008). Productive waters of the Argentine Sea (Southwestern South Atlantic) are also rich in diatoms (e.g., Carreto et al 1981;Akselman 1996;Almandoz et al 2007). Diatoms can be identified by microscopy, pigment content or genetic analyses.…”

“…The Argentine Sea, the Polar Front and the Weddell Sea are characterized by high primary productivity and rich phytoplankton communities (Longhurst 1998;Romero et al 2006;Schloss et al 2007). Phytoplankton are the main source of organic carbon in the ocean and are subject to high spatial variability and strong seasonality (Fischer et al 2002).…”

Influence of microbial community composition and metabolism on air−sea ΔpCO2 variation off the western Antarctic Peninsula

“…Moreover, this relationship held true for stations dominated by diatoms (i.e. defined by Schloss et al 2007 as stations with more than 50% of the phytoplankton biomass represented by diatoms; r = −0.68, p < 0.01; Fig. 4b) but not for stations dominated by phytoflagellates (i.e.…”

“…The north of the peninsula was sampled both during the summer (before 21 March) and fall (after 21 March) while the south of the peninsula was only sampled during fall. The sampling methods of the ARGAU missions were described by Schloss et al (2007) and Bianchi et al (2005). Roughly, they consisted of a continuous acquisition and recording of meteorological, atmospheric, and seawater data.…”

Remote sensing of coccolithophore blooms in selected oceanic regions using the PhytoDOAS method applied to hyper-spectral satellite data

“…-The sAtl is located at the eastern part of the Patagonian Shelf, which is regarded as one of the richest areas of primary production (Bianchi et al, 2005(Bianchi et al, , 2009Schloss et al, 2007), and features recurring large coccolithophore blooms (Longhurst, 1995;Painter et al, 2010). The Patagonian Shelf, between 38 • S and 51 • S, is located southwest of the confluence zone and therefore is affected by that.…”