engleski

Bacterial, phyto-, and zooplankton community succession in highly dynamic ecosystem of the southern Adriatic

Island trapped internal waves (ITW) were observed at Lastovo island, with an effect of daily vertical thermocline movement. To link ITW effect with net primary production (NPP), dense temporal sampling was conducted using Niskin bottles and plankton nets (12th - 21st July 2021). Overall diversity was investigated with light microscopy (plankton communities), flow cytometry (picocyanobacteria, heterotrophic bacteria and picoeukaryotes), and next-generation sequencing (NGS) targeting 16S and 18S rRNA genes. Statistical analyses tested similarity between samples, and dominant taxa contribution. Community dynamics shifted after 16th July. Phytoplankton abundance increase was not significant, but initially high microzooplankton abundances and nutrient concentrations declined significantly. Bacterio-archaeal and eukaryotic assemblages composition also shifted, but the same oligotrophic key higher taxa dominated at both instances. Chlorophyceae, nano-scale coccolitophorids, micro-scale dinoflagellates, and diatoms L. danicus, P. delicatissima, and T. frauenfeldii contributed the most to distinct spatial distribution. Deep chlorophyll maximum (DCM), and the thermocline layer were dominated by micro-, and nanophytoplankton, so as Prochlorococcus and Synechococcus, respectively. Heterotrophic bacteria dominated the thermocline layer. Observed community succession indicates a fast response to changes in environment, and further research will observe its link to ITW effect.

spatial distribution ; thermocline movement ; ITW effect ; community dynamics

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