Introduction: Phosphorus (P) is an essential nutrient for all life forms. In aquatic environments, P is a double-edged sword. In some areas, habitat biodiversity is strongly limited by low P bioavailability, while in others, P inputs in excess of plant needs have led to pollution of water bodies and eutrophication. There is little information available on P status in river sediments by single chemical extraction and its correlation with algae growth in Iran. This study was performed to select proper single chemical extraction methods by algal bioassay. …