ABSTRACT
In the study of water ecology, food-web structure research has been crucial in the restoration of the lake ecological system and the evaluation of the lake ecosystem response to environmental changes. The stable isotopic technique has become an important means of the ecosystem’s food-web structure and the relationship between nutrition and its dynamic change. Studies have shown that there exist certain differences among the carbon stable isotope ratios (δ13C) of different sources of organic matter. The δ13C of consumers is almost the same as that of the digested and assimilated food, with the difference between changes being mainly in the range of 0-1‰. The nitrogen stable isotope ratio (δ15N) will produce enrichment in the process of animal feed. The δ15N of consumers is about 3.4 ± 1.1‰ higher than that of the food in the process of the trophic level transfer. Both δ13C and δ15N, respectively, reflect the food source of biology and the nutrition level position in the ecosystem’s food web, and therefore, it is possible to determine the source of natural or man-made carbon and nitrogen by carbon and nitrogen isotope technology, and track the act or process of assimilation and transfer way in the ecosystem’s food web.
