Seasonal variation in plankton abundance and diversity of Tanga coastal waters, Tanzania

Several studies have reported on seasonal patterns in plankton (phytoplankton and zooplankton), in different ecoregions. However, information on these plankton along the coastal waters of Tanga is limited. This study attempts to uncover and describe information related to abundance, distribution, and diversity of phytoplankton and zooplankton in the coastal waters located in the western side of the Pemba Channel, Tanzania, during the southeast monsoon (SEM) and the northeast monsoon (NEM) seasons. The samples of phytoplankton, zooplankton and environmental variables were collected in the coastal waters of Tanga, from June 2019 to January 2021. A total of 199 species of phytoplankton and 32 genera of zooplankton were identified. Although the abundance varied between the SEM and the NEM seasons, Bacillariophyceae were the most abundant among the phytoplankton groups, while Copepods were the most abundant zooplankton in both seasons. The abundance variation in phytoplankton and zooplankton could be attributed to environmental variables, which varied significantly between seasons. The results suggest that high nutrients concentration during the SEM season influences high plankton abundance, richness, and diversity.