Hydrographic conditions and plankton distribution during march and september 2017 in the Mexican North Pacific coast

Abstract

From March 4 to 6 and from September 20 to 22 of 2017, two oceanographic cruises were used to study the hydrographic conditions and their relationship with the distribution of plankton in Todos Santos Bay (TSB), Mexico. With the intention of analyzing the response of the plankton comunity and its relationship with the hydrography in the TSB during the spring and fall of 2017 and compare it with the antecedents. Physical variables were analyzed in the bay using sections of salinity, temperature, PAR and chlorophyll A. Surface zooplankton distribution in the bay was studied, as well as the phytoplankton community on the surface and where the chlorophyll A maximum was found. The results showed upwelling all year in the north of TSB, where the zooplankton maxima was found, mostly copepods. The interior of the bay was dominated in the spring season by a anticilonic eddy characterized by a great abundance of phytoplankton cells and in fall by a cyclic eddy, dominated by diatoms and dinoflagellates related with retention of water. Evidence of recovery of the phytoplankton community was found after the warm events that occurred during 2015 and 2016, as well as new phytoplankton species not described for the bay and an decrese in the populations of decapods.