Phytoplankton as an indicator of coastal water quality: Spatiotemporal patterns in protected and disturbed areas

Phytoplankton communities are crucial for marine ecosystems and ecological balance, serving as effective bioindicators due to their sensitivity to environmental changes, particularly pollution. This study evaluated the abundance and composition of phytoplankton communities in both protected and disturbed coastal marine areas between 2023 and 2024, focusing on their relationship with water quality during the dry and rainy seasons. Increased algal abundance was observed during the rainy season, especially in disturbed areas, likely due to continuous nutrient-rich discharges. Additionally, genera often associated with nutrient enriched conditions and occasionally with bloom events, including Oscillatoria , Euglena and Anabaena , were more prevalent in these areas. These genera are typically found in environments with high organic matter and nutrient levels. Variations in phytoplankton community were significantly influenced associated with gradients in temperature, dissolved oxygen, pH, suspended solids, and phosphate, further supporting the role of phytoplankton as sensitive indicators of water quality changes. These findings emphasize the potential of phytoplankton as an ecological monitoring tool and highlight the need for enhanced protection measures in marine protected areas. Management strategies aimed at controlling wastewater discharge in coastal zones are recommended to mitigate eutrophication and preserve marine ecosystem functionality.