Ecotoxicological Assessment of Climate Change-Related Stressors and Agents of Pollution on A Tropical Estuarine Phytoplankton Species 2024

Abstract

This study assessed the ecotoxicological effects of climate change-related stressors (temperature, salinity, and pH) and agents of pollution (cadmium and pyrene) on selected estuarine phytoplankton adapted to the Whin Estuary in Ghana. Field investigations were first conducted to assess the abiotic environmental parameters and phytoplankton abundance, composition, and distribution within the Estuary. Diatoms, particularly from the genera Thalasiosira, Navicula and Nitzschia, were the most abundant phytoplankton in the selected estuary. As a result, Thalassiosira weissflogii cultures were isolated, acclimatised and used for ecotoxicological assessments on the impacts of change- and pollution-related stressors, and the impacts on their functional (growth rate, chlorophyll-a content, and biomass) and molecular attributes. The impacts on functional attribute results showed that lower salinity and pH have the greatest impact on T. weissflogii growth rate, chlorophyll-a, and biomass concentration. For instance, salinities of 1 and 5‰ resulted in more than 75% decrease in cell growth, while exposure to higher levels of combined pyrene and cadmium reduced the growth rate by more than 30%. The genotoxicity analysis revealed that exposure to high levels of pollution stressors significantly altered the molecular setup of T. weissflogii as portrayed by the high number of differently expressed genes (DEGs), particularly in the temperature, cadmium and pyrene treatments. This study has provided evidence on impacts of climate change-related stressors and pollution agents on T. weissflogii at the species and molecular genetics levels. The outcome could be critical for modelling the impacts of climate change and pollution on coastal ecosystems, particularly within the tropics