The significance of phosphorus in algae growth and the subsequent ecological response of consumers

Abstract Human activities have substantially disrupted phosphorus (P) cycles in the ecosystem, affecting producers and consumers along the food chain. To assess the ecological effects of imbalanced P on producers as well as consumer reactions to changes in food quality, the effects of P concentrations (HP, MP, LP) on Scenedesmus obliquus, were investigated. To investigate the indirect effects of P levels on consumer feeding behavior and life history strategies, the algae were fed to Rotaria rotatoria. The results showed that P concentrations increased population density, environment capacity, cell size, specific growth rate, chlorophyll a, and chlorophyll b substantially. As a result of the P intracellular concentration of algae produced in HP and MP media, the algae were classified as two categories of food quality (P-rich, P-poor). Rotifers' grazing and filtration rates were significantly increased when they were fed P-poor algae. In reaction to a lack of P in their diet, rotifers extended their juvenile and reproductive periods, resulting in a longer life span, generation time, and life expectancy at rotifer hatching. Despite living longer than P-rich groups, rotifers fed P-poor algae produced much fewer offspring and had a significantly lower net reproductive rate, which was linked to the rotifers' longer generation period. According to the findings, phosphorus has a major impact on algal food quality, and herbivorous consumers are subjected to significant food quality variation of algae, which they respond to by modifying their life history strategies and feeding behavior.