engleski

Stability of the freshwater network ecosystem despite seasonal and downstream changes in environmental conditions and diversity of microbial communities

Freshwater network ecosystems consist of interconnected lotic and lentic habitats within the same catchment area. The hydrologic and biogeochemical changes that occur during runoff in lotic systems significantly affect the succession of microbial communities in these systems [1]. Similarly, surface runoff from lotic systems has a significant impact on the environmental conditions and diversity of microbial communities in lentic systems [1]. Therefore, hydrology, system location, and local environmental conditions, along with community assembly processes [2], are the most important factors affecting microbial community formation in an interconnected freshwater network ecosystem. Using Plitvice Lakes as an example, we studied changes in environmental conditions and microbial communities (bacteria and fungi) that occur with runoff. Water samples from tributaries, interlake streams, and the Korana River were collected in three different seasons (spring, summer and autumn). Physio-chemical parameters were measured in situ (temperature and dissolved oxygen concentration) and subsequently from filtered water samples (DOC, Ca2+, NO3 - and Clconcentrations). The microbial communities of the water samples were characterized by amplicon sequencing of bacterial 16S rRNA and fungal ITS2 genes. All statistical analysis was performed using R software (R Core Team, 2021). The obtained results showed differences among three stream types and three different seasons, both in environmental conditions and diversity of microbial communities. They also showed seasonal differences in the bacterial community assembly processes, while fungal community assembly was not dominated by any single process. Despite the microbial diversity among different stream types and seasons, we proved the stability of the Plitvice lakes by determining the core microbiome, which accounted for the majority of the microbial communities in all stream types and seasons.

freshwater network ecosystem ; lotic systems ; environmental conditions, community assembly processes ; microbial communities

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