Biodiversity of freshwater ciliates (Protista, Ciliophora) in the Lake Weishan Wetland, China: the state of the art

Ciliates are core components of the structure of and function of aquatic microbial food webs. They play an essential role in the energy flow and material circulation within aquatic ecosystems. However, studies on the taxonomy and biodiversity of freshwater ciliates, especially those in wetlands in China are limited. To address this issue, a project to investigate the freshwater ciliates of the Lake Weishan Wetland, Shandong Province, commenced in 2019. Here, we summarize our findings to date on the diversity of ciliates. A total of 187 ciliate species have been found, 94 of which are identified to species-level, 87 to genus-level, and six to family-level. These species show a high morphological diversity and represent five classes, i.e., Heterotrichea, Litostomatea, Prostomatea, Oligohymenophorea, and Spirotrichea. The largest number of species documented are oligohymenophoreans. A comprehensive database of these ciliates, including morphological data, gene sequences, microscope slide specimens and a DNA bank, has been established. In the present study, we provide an annotated checklist of retrieved ciliates as well as information on the sequences of published species. Most of these species are recorded in China for the first time and more than 20% are tentatively identified as new to science. Additionally, an investigation of environmental DNA revealed that the ciliate species diversity in Lake Weishan Wetland is higher than previously supposed.

Automated summary

Ciliates play a critical role in the energy flow and material circulation within aquatic ecosystems. However, studies on the taxonomy and biodiversity of freshwater ciliates, particularly in Chinese wetlands, are limited. A project to investigate the freshwater ciliates of Lake Weishan Wetland in Shandong Province was initiated in 2019. The findings to date indicate a high morphological diversity of ciliates, with 187 species identified, including several that are potentially new to science. A comprehensive database including morphological data, gene sequences, microscope slide specimens, and a DNA bank has been established. This study provides valuable insights into the previously underestimated ciliate species diversity in Lake Weishan Wetland.