Phytoplankton distribution along a transect across the north atlantic

Abstract

Physical-biological coupling in pelagic ecosystems at macroscale level provide a way to understand the variability of ecological processes at global scale. In the context of the Malaspina Expedition, the vertical distribution of phytoplankton was determined using flow citometry along a cruise between Santo Domingo and Vigo on board R/V Sarmiento de Gamboa The distribution of four phytoplanktonic groups (Synechococcus, Eukaryotic picoplankton, ultraplankton and large nanoplankton) followed the main chlorophyll a pattern along the transect, whereas Prochlorococcus showed a more ubiquitous distribution. The main phytoplanton distribution pattern was determined by the presence of three biogeographic provinces well differentiated both from the nutritional status and the physical-chemical characteristics of the water column. Phytoplankton generally showed a scarce representation in the more oligotrophic waters of the North Atlantic Tropical Gyre, where Prochlorococcus constituted the the main group , with maximum,densities of 5.1x104 cells/ml. On the other hand, the rest of pico and nanoplanktonic groups reached the higher abundances in the colder and nutrient richer waters of the North Atlantic Subtropical (West Gyre and East Gyre), with peaks of 1.1x105 Synechococcus/ml and 4x104 picoeukaryotes/ml.