engleski

Dynamics of eukaryotic and prokaryotic communities in Croatian karst lakes

A major part of the Croatian coast belongs to the Dinaric karst region being characterized by porous limestone and semi-porous dolomites. Though the karst lakes are essential drinking water resources, their importance lies in their high biomineralization rates and strong preservation of biodiversity. High porosity and a wide catchment area of lakes expose them to the inflow of nutrients from surrounding areas, which can be reflected in their microbial composition. According to previous studies, karst lakes in Croatia differentiate from oligotrophic (Kozjak, Vrana on Cres, Oćuša), meso-oligotrophic (Prošće, Visovačko lake) to mesotrophic (Crniševo) lakes. The aim of this study was to characterize the seasonal diversity of microbial communities using molecular tools and to investigate their response to environmental parameters. We compared eukaryotic and free-living prokaryotic communities of six natural karst lakes through 16S and 18S rRNA amplicon sequencing in the period from April to September in 2017. High throughput sequencing revealed a high seasonal intra- and inter-lake diversity. Species richness of eukaryotic communities appeared to be more diverse than of prokaryotic communities, with the lowest richness being encountered in lake Crniševo which was characterized by changes in salinity. Similarities in eukaryotic community composition, based on a higher taxonomic level, were shown between lakes Kozjak and Prošće, and lakes Oćuša, Crniševo and Visovačko lake, respectively. The observed high dissimilarity of lake Vrana on Cres to the other lakes could be traced back to a high relative abundance of Dinophycea. The prokaryotic communities consisted of similar compositions during the season and all lakes. The most abundant prokaryotes were affiliated to the phyla Actinobacteria, Proteobacteria and Bacteroidetes, and to a lesser extent to Cyanobacteria and Verrucomicrobia. This study highlights the diversity and seasonal changes in eukaryotic and prokaryotic communities and provides valuable knowledge to fill the gap in our understanding of the ecological functioning of microbial communities in karst lakes.

Eukaryotes ; Prokaryotes ; NGS ; karst lakes

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