engleski

Diversity and ecological preference of ciliates assemblage in a freshwater karstic river

Ciliates (Protista) are an important component of aquatic ecosystems. In this study we investigated molecular and morphological diversity of ciliates in the Krka River (Croatia), a karstic aquatic ecosystem characterized by tufa barriers, high biomineralization rates and high biodiversity. Sampling of four representative habitats at the spring, upstream, middle stream and downstream parts of Krka was performed in September 2017. Samples collected from light- and dark-exposed sides of sampling substrates (biofilms from stones) were investigated using traditional morphology and environmental DNA metabarcoding (hypervariable V9-region of the SSU rRNA gene). A total of 364 taxa were detected by molecular approach, while 36 were determined via traditional microscopy. Considering the divergence between sampling locations, morphology did not show statistical significance in separation of assemblage as opposed to molecular analysis. The significantly different ciliate patterns in alpha diversity at distinct sampling sites can be explained by the ecological preferences of ciliate identities inferred from the taxonomic assignments of molecular operational taxonomic units (OTUs). This study confirmed that the molecular approach may provide deeper insights into ciliate assemblage of river biofilms. We show that, in accordance with previous studies, ciliates are excellent biomarkers for rivers and that eDNA metabarcoding has the possibility to fully unlock this bioindicator potential. Further research will include a comprehensive molecular approach in order to affirm the indicator potential of this group compared to other microbial groups.

ciliates ; Krka River ; biodiversity ; molecular and morphological diversity

University of Kaiserslautern, Ecology group