International Science Community Association International Research Journal of Environmental Sciences 2319-1414 8 4 2019 10 22 Phytoplankton biomass and primary production dynamic in Porto-Novo lagoon (Republic of Benin) 1 13 EN Henri Kpèdékpo AKOGBETO 1 International Chair in Mathematical Physics and Applications (ICMPA), Faculty of Sciences and Technologies (FAST), University Abomey-Calavi, 072 P.O.Box 50, Cotonou, Benin and Unité de Recherche sur les Zones Humides, Département de Zoologie, Faculté des Sciences et Techniques, Université d′Abomey-Calavi, 01BP526 Cotonou, Bénin Emile Didier FIOGBE 2 Unité de Recherche sur les Zones Humides, Département de Zoologie, Faculté des Sciences et Techniques, Université d′Abomey-Calavi, 01BP526 Cotonou, Bénin > Research Paper 2018 9 4 2019 10 22 Porto-Novo lagoon is eutrophical water on which more than 500,000 persons depend. The study of primary production tied to some relevant environmental physico-chemical parameters was carried out in order to build an exploitable data base on the potentialities of this lagoon. Measurements were carried out in relation to seasons in six sites divided in twelve areas with different hydrologic scheme, from June 2015 to February 2016. The AFNOR NFT 90 – 117 norm was used for chlorophyll-a measurement though primary production valuation was carried out through prior established general equations. The water temperature varied between 27.58 and 32.28°C. Salinity and pH ranged respectively between 6.33 – 7.03 and 0.00 – 2.93mg/L though the maximum and minimum conductivity values were respectively 9170 and 67.6µsem-1. Dissolved oxygen value fluctuated between 1.09 – 2.98 mg/L which are lower than standard normal suggested by FEPA. TDS varied between 107.80 and 3703.00mg/L with turbidity ranging between 2.50 and 54.67mg/L though maximum and minimum transparence were 2.52 and 0.68m respectively. Total Phosphorus (TP) and Total Nitrogen (TN) showed fluctuating values 1.85 – 5.25mg/L and 1.13 – 2.59mg/L respectively. Primary production varied between 840.10 and 3324.24mg C/m2.J. It was globally higher in the central area than in bank area. Primary production was significantly correlated with transparence (r= 0.81 and p=0). The current study shows that phytoplankton production in Porto-Novo lagoon is influenced by many factors such as geographical position that delimit lotic and lenthic area; climate; presence of macrophytes and human activities on the side basin. Copyright@ International Science Community Association