Coastal phytoplankton community change in response to environmental variability in South Africa

Long term datasets are important to elucidate the effects of climate change and the Anthropocene on the environment. We present a 14-year dataset of phytoplankton of a reference station in Algoa Bay. Additionally, the environmental data of the entire bay at a further seven stations. Samples were collected at a monthly frequency using the same methodology. We provide 3 228 nutrients, 3 315 chlorophyll-a samples between 2010 and 2024, 1 088 Secchi disk casts between 2011 and 2024 and a total of 1 005 CTD casts between 2012 and 2024 across eight stations. The phytoplankton surface community was captured by 144 horizontal net tows, and 143 water-column community (vertical tows) samples collected between 2010 and 2024 identifying 124 different taxa at the reference station. Together with this, continuous underwater temperature data at 10 stations and a weather station at Coega Harbor provides hourly data from 2008 and 2015, respectively. These datasets are important in understanding hydrological, biogeochemical and phytoplankton community structure, dynamics and changes in Algoa Bay.