Morphology and ecological studies of the Chlorophyta in relation with water quality parameters of the Dor River Abbottabad, Pakistan

The present study investigated the monthly dynamics of algal diversity in relation to the physicochemical parameters of the Dor River, a key freshwater tributary of the Indus Basin in Khyber Pakhtunkhwa, Pakistan. Water and algal samples were collected monthly for one year from two hydrological distinct stretches of the river, extending from Barengali to Dhamtor (freshwater zone) and from Domail to Tarbela Dam. Standard limnological protocols and taxonomic microscopy were employed to identify Chlorophyta species, quantify their community structure, and evaluate the environmental influences on the algal distribution. A total of 23 algal species belonging to 3 classes, 8 orders and 14 families were recorded, with Chlorophyceae being the most dominant group. Diversity indices revealed the highest species richness and Shannon diversity during autumn and late winter, while monsoon months exhibited reduced diversity associated with increased turbidity, dilution, and ionic fluctuations. The physicochemical variables, such as pH (7.1–7.87), conductivity (254–444 μS/cm), turbidity, and nutrient levels, displayed clear seasonal patterns, significantly shaping the algal abundance, frequency, and importance value index (IVI). Chlorophycean taxa, including <i>Scenedesmus bijuga</i>, <i>Ulothrix zonata</i> and <i>Oocystis borgei,</i> showed strong ecological plasticity and served as indicators of stable water quality. Overall, the Dor River maintained a healthy ecological status with strong resilience to seasonal variations, although monsoon-driven disturbances temporarily altered the algal community structure. This study highlights the value of integrating algal bioassessment with water quality monitoring as an effective tool for evaluating freshwater ecosystem health and guiding conservation strategies for the Dor River.