Aim: Zoobenthos are important components of local biodiversity, food webs, and biogeochemical circulation processes, and are important water quality indicators. Despite their recognized importance, current research on freshwater macrozoobenthic fauna in forested inland water bodies (reservoirs, lakes, streams) in China is lacking. To better understand macrozoobenthic communities and their ecosystem services in these habitats, we choose a typical subtropical forest reserve, the Chebaling National Nature Reserve for investigation.
Methods: We conducted a two-year (2019-2020) systematic field survey across nine sampling sites of different substrates in the Chebaling National Nature Reserve, Guangdong Province. These sites encompassed experimental, buffer, and core zones, and elevations stretched from 345 m to 751 m. The surveyed habitats included forested rivers, mountain streams, ponds, reservoirs, paddy fields, and ditches, which contained substrates comprising rock, gravel, sand, hardened riverbed, and silt. We applied multiple methods to survey the various habitats, including dip netting in shallow water, brushes and tweezers to isolate attached species under rocks, and baits and shrimp cages to capture species in deep water. During field surveys, we measured species composition and their population levels. We then analyzed metrics of species composition, spatial distribution, environmental indicators, and ecosystem function.
Results: In total, we identified 57 species of macrobenthic fauna (belonging to 4 phylum, 6 classes, 18 orders, and 38 families) in the reserve. Eighty percent of species were arthropods, and 90% of arthropods were aquatic insects and their nymphs. We recorded 22 species and 8 families of nymphs in Odonata (dragonflies and damselflies), which constituted 38% of all captured species. Nymphs of EPT (Ephemeroptera, Plecoptera, and Trichoptera) species constituted 22% of all species. We commonly recorded Semisulcospira libertina in various flowing water bodies, along with a considerable population of pristine water indicator species in the low-altitude experimental area.
Conclusion: Macrozoobenthic fauna in Chebaling National Nature Reserve comprised species typical of subtropical forest freshwater ecosystems. Large proportions of species that favored flowing water conditions were recorded in sites with various water bodies and elevations, and were even recorded in disturbed sites (i.e., in both experimental areas and artificial water bodies). Most species were water quality indicators that reflected the major water forms and overall quality of the reserve. The high diversity of aquatic predatory insects we recorded indicates that there is a sufficient amount of small prey in the ecosystem. Furthermore, our results suggest that the diverse and abundant macrozoobenthos can serve as considerable source of prey to predators in the reserve. Overall, our results provide data to inventory zoobenthic species and perform environmental assessments, which can further be enhanced by continued long-term monitoring of zoobenthos in the Chebaling National Nature Reserve.