Towards an assessment of host-determined microbial assemblage processes in freshwater ecosystems, HostMBias

Production of the dataset was conducted as part of the eLTER PLUS TA project 078. The project aimed to collect water samples from the three LTER sites for the analysis of microbiota and ichthyofauna diversity using DNA sequencing. The three LTER sites used are: Lehrforst Rosalia (LR) [AT], Lago Maggiore (LM) [IT], and Rhine-Main Observatory (RMO) [DE]. At randomly chosen points for LM and RMO and at all sampled points at LR, physico-chemical parameters were assessed to make a robust estimate of the link between biota and basic water quality indicators. For LM and RMO, where collection of samples was done from the same water body (Lake Maggiore and river Kinzig, respectively), coordinates for sampling were selected based on historical data from national fish and water quality monitoring programs, in such a manner as to maximize the heterogeneity between the samples and increase microbial and fish diversity. For LR, in the absence of historical data, nine distinct water bodies (ponds and rivers) were chosen for sampling: Grasliegengraben, Ofenbach, Leitha, Pitten, Schlattenbach, Schwarza, Feistritz, and two unidentified water bodies. Based on the imputed historical data (LR and RMO) and the results of on-site measurements of water quality, clustering silhouette scores obtained for LR, LM and RMO are: 0.334, 0.444 and 0.673, respectively, indicating moderate to good clustering (sample diversification). Comparison of water quality indicators suggested higher DO (median 10.38 mg/L) and EC (median 570 μS/cm), and lower water temperature (median 18.55 °C) at RMO, and higher pH (median 8.775) at LM. These differences between the research sites are expected to further contribute to heterogeneity of the biota in collected water samples.