SEASONAL VARIATION IN FISH TROPHIC STRUCTURE OF THE HEISHUI RIVER BASED ON CARBON AND NITROGEN STABLE ISOTOPES

To investigate the characteristics and seasonal variations of the aquatic food web in the Heishui River Basin, fishery resources were collected from different river sections in July (wet season) and November (dry season) of 2024. Based on the carbon and nitrogen stable isotope values of the main consumers and prey organisms, the SIBER model was used to analyze the seasonal differences in fish trophic levels and community trophic structure. The δ13C values of organisms ranged from –20.45‰ to –5.27‰ in the wet season and and from –29.40‰ to –1.12‰ in the dry season; δ15N values ranged from 0.88‰ to 14.68‰ in the wet season and from 0.87‰ to 12.66‰ in the dry season. The trophic level of fish ranged from 1.817 to 3.918, with no significant overall difference between the wet and dry seasons (P>0.05). However, significant seasonal variations occurred in certain species: the average trophic level of Abbottina obtusirostris and Zacco platypus was significantly higher in the wet season (P