Assessment of water quality in the coastal wetland of Kalathas, Crete, Greece: A local-scale wetland at high risk

Coastal wetlands are highly dynamic ecosystems where natural processes and anthropogenic pressures interact to control water quality. This study evaluates the physicochemical characteristics, nutrient dynamics, photosynthetic pigments, and fluorescence properties of the Kalathas coastal wetland in Crete, Greece, over one year (2022), providing an integrated assessment of its environmental status. The wetland exhibited alkaline conditions and pronounced spatial variability associated with marine intrusion. Among nutrients, silicon showed a strong and consistent positive relationship with chlorophyll a, indicating its key role in regulating phytoplankton biomass. In contrast, total hardness was negatively associated with chlorophyll a, suggesting that increased ionic strength may limit biological productivity. A strong negative relationship between chloride concentrations and fluorescence emission intensity was also observed, consistent with fluorescence quenching under high ionic conditions. Overall, water quality in the wetland appears to be controlled by the combined influence of geological background, marine intrusion, and localized anthropogenic inputs. These findings provide a robust baseline for this understudied ecosystem and highlight the need for continuous monitoring to support effective management and conservation.