ASSESSING THE IMPACT OF CONTAMINATED SEDIMENT RESUSPENSION AND ANTI-SCALANT EFFECTS ON PHYTOPLANKTON COMMUNITY COMPOSITION, DYNAMICS, STRUCTURE, AND FUNCTION IN QATAR'S COASTAL ENVIRONMENT

Abstract

Phytoplankton play a fundamental role in marine ecosystems, contributing to primary production, carbon cycling, and food web stability. However, their community structure and physiological functions are highly sensitive to climatic and environmental changes in coastal environments, particularly sediment resuspension and chemical pollutants. This study investigates the effects of sediment resuspension and anti-scalant from desalination plants exposure on phytoplankton community composition, diversity, biomass accumulation, and physiological responses in Doha Bay, a highly dynamic, shallow water and urbanized coastal environment. The sediment resuspension promoted phytoplankton biomass due to nutrient release from the sediments. However, over time, nutrient depletion contributed to diversity shifts and reduced photosynthetic efficiency (Fv/Fm), particularly in SE treatments. While diatoms exhibited resilience to environmental changes in both experiments with a dominance of Chaetoceros species, dinoflagellates and chlorophytes were more vulnerable, showing significant declines in abundance, especially under higher anti-scalant concentrations. The 50 ppm anti-scalant treatment caused the most pronounced reduction in species richness, diversity indices, and photosynthetic performance, indicating potential toxicity effects.