GEOGRAPHIC PROVICES OF PHYTOPLANKTON ALONG LATITUDINAL TRANSECT IN THE EASTERN ATLANTIC OCEAN FROM THE CONCEPT THAT PIGMENT RATIOS DRIVE THE SPECTRAL ABSORPTION SHAPES
ABSTRACT
Oceanographic cruise with 59 stations in the eastern Atlantic Ocean (EAO) from October 15 to November 14, 2005. Data were collected on phytoplankton bio-optical variability of suspended particulate matter (ap) and photosynthetic pigment analysis at two depth levels (surface and 10 m), where values of light absorption coefficient by phytoplankton (aph) and non-pigmented material (ad) were determined, as well as the pigment composition of phytoplankton through the HPLC technique. In general, the EAO region showed oligotrophic characteristics, except in the northern Cantabrico Sea and Cape Town region. In these two areas, high values of aph440 nm and chlorophyll-carotenoids were observed. The most relevant chlorophylls/carotenoids were: divinyl chlorophyll a, zeaxanthin, hexanoyloxyfucoxanthin and fucoxanthin; so we assume that the different phytoplankton assemblages were: Prochlorococcus, Synechococcus, prymnesiophytes, and diatoms that were present during autumn 2005. In this study, determined 4 Geographic Provinces of phytoplankton (GPv) based mainly on the normalized spectral shape of light absorption (aphn/440 nm). We were consider that oceanographic meteorological events, upwelling, and permanent rivers are the ones that cause instability in the water column, determining the changes in the phytoplankton community structure.