Matiere organique presente dans les eaux d'un site hydrothermal actif du Pacific-Est (13 degree N)

Organic matter present in seawater was investigated in various samples collected in an active hydrothermal site of the East Pacific Rise (EPR) near 13 degree N. During three dives of the submersible Cyana, sampling was carried out at the mouth of active chimneys and near animal communities (Alvinellinae, Pogonophora and Serpulidae). The organic C and total N content of particulate material are higher than the mean concentrations of deep water; combined amino-acids do not show a comparative augmentation, but fatty acids and hydrocarbons are higher in the vicinities of Alvinellinae and Pogonophora than in reference samples or near Serpulidae zones. It is suggested that simultaneous determination of the concentrations of organic substances and bacterial activities would favour a better understanding of biological activity in the hydrothermal region.