Study on Physical and Functional Habitat Characteristics of Rivers Based on Protection Targets

Physical and functional habitats are two important components of river environments, both reflecting the adaptability of aquatic organisms to their surroundings and the shaping of their ecological habits by the habitat environment. Studying the two aspects together can lead to an in-depth understanding of aquatic organism living environments and is more conducive to the comprehensive protection and restoration of aquatic ecosystems. We simulated and analyzed the physical habitat characteristics of Plecoglossus altivelis in the Nanxi River and carried out four water ecological surveys in the main channel of the Nanxi River. The research and current stage survey analyses showed that the rapids and deep pools of the Nanxi River mainstream physical habitat are both alternatively and evenly distributed, and each account for more than 20% of the total length of the river. Under extreme flow conditions, a relatively stable distribution of shallow shoals and deep pools are maintained, providing habitats for fish. Under certain water conditions, changes in permanganate index, total phosphorus, and total nitrogen observed during the fattening and spawning periods were consistent with the migration habits of P. altivelis. Algae growth was related to water quality, species diversity, quantity, and distribution characteristics of benthic algae, and was closely related to the migration time and habitat selection of P. altivelis.