Atmospheric bulk deposition of dissolved nitrogen, phosphorus and silicate in the Gulf of Gabès (South Ionian Basin); implications for marine heterotrophic prokaryotes and ultraphytoplankton

Abstract Monthly variability of atmospheric deposition of dissolved nitrogen, phosphorus and silicate was assessed during the year period from June 2014 to May 2015 in the Gulf of Gabes, situated near the most active source of dust. Nutrient concentrations, ultraphytoplankton Synecococcus and heterotrophic prokaryotes while nanophytoplankton biomass decreased from 62.38% to 43.39% towards the wet season. During the wet season, heterotrophic prokaryotes become the first contributors to the carbon biomass in the surface water. This suggests a possible contribution of bacteria to the organic nutrient pool driven by atmospheric deposition or/and a reinforcement of the heterotrophic character of the system due to the organic content mineralization processes.