Picoplankton community structure on the Atlantic Meridional Transect: a comparison between seasons

Photosynthetic electron turnover in the tropical and subtropical Atlantic Ocean

“…Maximum ETRs were highly variable within and between provinces and could be partly explained by changes of light absorption in response to water column structure and light intensity. These observations were consistent with the differing taxonomic and physiological nature of phytoplankton communities from tropical and subtropical environments that has been observed previously (Maran˜o´n and Holligan, 1999;Maran˜o´n et al, 2000;Zubkov et al, 2000;Barlow et al, 2002;Maran˜o´n, 2005). However, consideration of corresponding changes of light absorption, maximum ETRs and the light saturation parameter, E k , and of differences between ETRs and previous C-based measurements of P max demonstrate that photochemistry may not be tightly coupled with C uptake throughout these environments.…”

“…Bricaud et al, 2004 and biophysical (Moore et al 2005(Moore et al , 2006 absorption measurements when large changes of nutrient status and thus phytoplankton cell size of the system in question are encountered. However, the subtropical and tropical Atlantic systems we investigated are oligotrophic and largely dominated by small cells (Zubkov et al, 2000;Maran˜o´n et al, 2003). Each ETR calculation is the product of effective absorption cross-section and actinic PPFD to yield the rate of light absorption.…”

“…Picoeukaryotes, Synechococcus and Prochlorococcus dominate biomass throughout these provinces; however, typically picoeukaryotes and Synechococcus predominate the northern tropical Atlantic and, to a lesser extent the equatorial upwelling, whilst Prochlorococcus predominates the tropical equatorial and subtropical gyres (Zubkov et al, 2000). At the same time, the ratio of PS to PP pigments is lower in tropical than subtropical gyre provinces (Barlow et al, 2002).…”

“…Recent evidence from both the laboratory (Suggett et al, 2004) and field (Moore et al, 2005(Moore et al, , 2006) has demonstrated that s PSII,478 can be highly variable both between taxa and with photoacclimatory state. This would imply that the dark-adapted effective absorption cross-section is not constant with depth where distinct phytoplankton populations occur at different depths within the water column, as frequently occurs within tropical and subtropical Atlantic provinces (Zubkov et al, 2000;Barlow et al, 2002).…”

Chemotaxonomic phytoplankton patterns on the eastern boundary of the Atlantic Ocean

“…Most of the cruise tracks have predominated across oligotrophic waters of the northern and southern gyres where TChla (total chlorophyll a) is o0.25 mg m À 3 and flow cytometric analysis demonstrated the dominance of picoprokaryotes (Prochlorococcus and Synechococcus spp.) and picoeukaryotes (Zubkov et al, 1998(Zubkov et al, , 2000Heywood et al, 2006;Tarran et al, 2006). Pigment data showed the dominance of divinyl chlorophyll a and zeaxanthin that were related to the prokaryotes in these regions (Gibb et al, 2000;Barlow et al, 2002).…”