Food Web Structure and Trophic Interactions Revealed by Stable Isotope Analysis in the Midstream of the Chishui River, a Tributary of the Yangtze River, China

Abstract

Understanding energy flow and nutrient pathways is crucial to reveal the dynamics and functions of riverine ecosystems and develop appropriate conservation strategies. In this study, we utilized stable isotopes of δ13C and δ15N to examine the fundamental characteristics of trophic position, trophic niche, and carbon source for the food web in the midstream of the Chishui River, a tributary to the Yangtze River. Our results showed that stable isotope signatures among different sorts of basal resources and consumers were significantly distinguishable and that the food chain consisted of four trophic levels, indicating the multiple trophic pathways and long food chain length here. The trophic guilds of fish were classified into four categories, in which herbivorous and carnivorous fish showed greater trophic diversity and omnivorous fish had higher trophic redundancy, which meant that there was a stable trophic niche structure in the study area. Phytoplankton and periphyton presented the largest contributions to consumers, indicating that autochthonous productivity was the dominant carbon source in the midstream of the Chishui River. Since the Chishui River is still in a natural condition without any dam constructions, the autochthonous productivity, stable trophic niche structure, multiple trophic pathways and long food chain length found here demonstrate its high conservation value. Therefore, the strategy to refrain from damming on this river should persist into the future.

The Low Ontogenetic Diet Diversity and Flexibility of the Pike-Perch, Sander lucioperca (Linnaeus, 1758) (Osteichthyes, Percidae): A Case Study

“…Specific to this fish in the studied area, data about its trophic relations and the food composition are vital when researching fish biology and ecology, at least because the growth of fish and, consequently, the productivity of the fish herd depends on the availability of food. Knowledge of the main food sources of various species of the fish community will lead to knowledge of the trophic network and, consequently, of the interrelationships of species [41][42][43][44][45][46][47][48][49].…”

Trophic niche isotope analysis of the fish assemblages in a subtropical river, Southern China

“…There is an urgent need to gather basic information on the distribution and trophic structure of freshwater fish for biological conservation and restoration (Chen et al, 2012). There are increasing studies on few trophic structure of riverine fish assemblages in China using the stable isotope approach (Chen et al, 2010;Qin et al, 2021;Zhang et al, 2007Zhang et al, , 2019.…”

Invasive carp alter trophic niches of consumers and basal resources in African reservoirs

“…An increasingly popular approach to examine the effects of organic pollution on fishes is via the use of biogeochemical tracers, such as stable isotopes (Baeta et al, 2017;Jackson et al, 2020;Prada et al, 2020;Almela et al, 2021). These studies are predicated on the principle that animals "are what and where they eat", with isotopic values of animal tissues reflecting the same biomarkers in their diet and surrounding food web (de Baeta et al, 2017;Qin et al, 2021). For example, nitrogen isotopic values (δ 15 N) are commonly used to infer consumer trophic level and diets (Post, 2002).…”