Biodiv Sci ›› 2021, Vol. 29 ›› Issue (8): 1108-1119.DOI: 10.17520/biods.2021086

• Original Papers: Animal Diversity • Previous Articles     Next Articles

Food sources and trophic levels of terrestrial cave fauna in Yuping Town, Libo County, Guizhou Province

Chengxiang Xu(), Lu Zhao, Weifeng Du, Siqiang Zhang, Yongying Wu, Fei Zhou   

  1. School of Life Sciences, Guizhou Normal University, Guiyang 550025
  • Received:2021-03-09 Accepted:2021-05-07 Online:2021-08-20 Published:2021-07-28
  • Contact: Chengxiang Xu

Abstract:

Aims:Karst caves are a gathering place for biodiversity in belowground extreme environments, but little is known about their food web structure. We investigated this by assessing the food sources and trophic levels of terrestrial cave fauna in Yuping Town, Libo County, Guizhou Province. We further documented cave biodiversity resource utilization to provide important reference data to inform conservation of karst ecosystems.

Methods: We investigated terrestrial cave animals in three representative caves in Yuping Town, Libo County, Guizhou Province in October 2016. In each cave system, we recorded δ13C and δ15N values of terrestrial cave animals and assessed variation in these characteristics. We then assessed the basic carbon source by analyzing the stable isotopes δ13C and δ15N. We then estimated the contribution rates of five types of basic carbon sources to terrestrial consumers using IsoSource software, and explored the trophic level of each faunal species in each cave.

Results: The δ13C value of cave plants ranged from -38.25‰ ± 0.95‰ to -29.44‰ ± 0.49‰, while that of soil organic matter ranged from -32.73‰ ± 0.03‰ to -24.68‰ ± 0.41‰. Most of these values were outside the change interval of δ13C in cave plants. The δ13C and δ15N values of cave fauna ranged from -34.22‰ ± 0.39‰ to -14.83‰ ± 0.78‰ and from 1.86‰ ± 0.20‰ to 16.43‰ ± 0.05‰, respectively, suggesting large differences among species and groups. The 78.3% contribution rate of soil organic matter to cave fauna was higher than that of the primary productivity of plants. The trophic level of cave consumers in Yuping Town, Libo County ranged from 1.01 to 5.32. Megascolecidae, snails, Oniscidae, horseshoes, Tipulidae, and Noctuidae were mainly classified as primary consumers into the second trophic level; Scutigeridae, Myrmeleontidae (larvae), and bats were classified into the third trophic level; Blattidae were classified into the second to third trophic level; Rhaphidophoridae and Labiduridae were classified into the second to fourth trophic level; and spiders spanned three trophic levels, being classified into the second to fifth trophic level.

Conclusions: Organic matter in cave soil is the main food source for cave consumers. Most cave fauna in the same taxonomic group had a consistent trophic level in caves, though some fauna belonging to the same taxa had different trophic levels in different caves or in different light zones of the same cave.

Key words: stable isotope, trophic level, food source, cave fauna, Libo County, Guizhou Province