地质科技通报 (Sep 2022)
Distribution of aquatic fauna in karstic groundwater and its enviro-nmental response on the south bank of the Yangtze River in Yichang
Abstract
To understand the distribution of aquatic fauna in karst groundwater and its environmental response, aquatic fauna and water samples were collected from 15 epikarst springs and 9 large karst springs on the south bank of the Yangtze River in Yichang from July to August 2018. In total, 809 individuals were collected, and they belonged to 13 subclasses. We found that: ①The spatial distribution of different animals in groundwater was different. Copepoda and Ostracoda stygobionts were abundant in epikarst springs (31.3%, 23.7%), Trichoptera and Diptera were less abundant (0.4%, 2.9%). Copepoda and Amphipoda were abundant in large springs (25.0%, 8.3%), Ostracoda stygobionts were less abundant (2.2%). ②The variation range of environmental factors (pH, Na+, Ca2+, Mg2+) in large karst springs (0.64, 1.25 mg/L, 34.0 mg/L, 22.1 mg/L) was narrower than that in epikarst springs (2.45, 5.68 mg/L, 59.6 mg/L, 33.4 mg/L), which indicated a relatively stable condition. ③According to the stepwise regression analysis, the main environmental factors of epikarst springs were pH, Na+ and Mg2+, and the main environmental factors of large karst springs were pH, SO42- and Mg2+. Moreover, the representative biological communities of epikarst springs were Ostracoda, Diptera and dark layer species of Turbellaria, and the representative biological communities of large karst springs were Mollusca, Diptera and Decapoda. ④According to the path analysis, Diptera mainly responded indirectly to Na+ and Mg2+ through Ostracoda, and Ostracoda stygobionts, Diptera and Turbellaria responded directly to pH in epikarst springs. In large karst springs, Mollusca mainly indirectly responded to pH through Diptera, Diptera indirectly responded to SO42- through Decapoda, and Mollusca, Diptera and Decapoda directly responded to Mg2+. The distribution of fauna in groundwater was the result of a direct response to environmental factors and an indirect response between different species.
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