Stable isotopes reveal effects of natural drivers and anthropogenic pressures on isotopic niches of invertebrate communi
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RESEARCH ARTICLE
Stable isotopes reveal effects of natural drivers and anthropogenic pressures on isotopic niches of invertebrate communities in a large subtropical river of China Sai Wang 1,2 & Lin-Hui Su 1,2 & Bang-Ke Luo 1 & Ying-Jun Qin 1 & Simon D. Stewart 3 & Jin-Peng Tang 1,2 & Tuan-Tuan Wang 4 & Yang Yang 1,2 & Gong Cheng 5 Received: 29 October 2019 / Accepted: 11 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Isotopic niches reflect the basic structure and functioning of river food webs; however, their response to riverine environments remains unclear. We used stable isotope analysis and community-wide metrics to quantify how invertebrate niches vary with environmental changes along a large subtropical river in China. Eight niche metrics, which had higher values in the wet than in the dry season, increased from headwaters to the middle river and decreased sharply near the estuarine industrial zones. The δ13C value of > − 23.8‰, which indicated consumption of epilithic diatoms, separated the invertebrates between the upper and mid-lower reaches. The δ15N values > 9.4‰ identified site-specific nitrogen sources from manure (e.g., animal effluent) and domestic sewage in agricultural area. The output of mixing models showed a downstream shift in carbon utilization by invertebrates from autochthonous periphyton and submerged hydrophytes to allochthonous C3 plants. Principle component (PC) and cluster analysis decomposed and grouped 40 environmental variables into 4 PCs that explained 84.5% of the total variance. Hierarchical partitioning revealed that the second and first PCs, which were driven mainly by biological indicators and habitat characteristics, had the highest explanatory power for niche ranges and areas (e.g., Bayesian ellipse), respectively. Our results suggest that reducing anthropogenic pressures (e.g., habitat loss and water pollution) on river ecosystems through measures, such as protecting diatom-dominated biofilms in riffles and controlling nitrogen loading in rural regions, may produce the greatest impact for river management. Keywords East River . Layman metrics . SIBER . MixSIAR . Functional feeding group . Nitrogen pollution . Biological indicator Responsible Editor: Philippe Garrigues Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-09252-8) contains supplementary material, which is available to authorized users. * Yang Yang [email protected] * Gong Cheng [email protected] 1
Research Center of Hydrobiology, Department of Ecology, Jinan University, Guangzhou 510632, China
2
Research Center of Tropical and Subtropical Aquatic Ecological Engineering, Ministry of Education Engineering, Jinan University, Guangzhou 510632, China
3
Cawthron Institute, 98 Halifax St East, Nelson, New Zealand
4
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
5
Environmental Engineering Center, Shenzhen Academy of Environmental
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