engleski

Metabarcoding of size-fractioned plankton affected by Island-trapped waves along Lastovo Island (Adriatic Sea)

Island-trapped waves (ITWs) represent a phenomenon whereby the Earth’s rotation causes the trapping of surface and internal waves at sea-coast boundaries, (in)directly affecting plankton diversity, dynamics and abundance. In this study we identified plankton taxa and their relative abundance of amplicon sequence variants - ASVs in seawater column at Struga station on Lastovo Island using amplicon metabarcoding with 16S rRNA and 18S rRNA genes. Sampling took place on two instances ; before (13th July) and during the ITWs phenomena (21st July 2022) ; and large volume of seawater (approx. 4L) was fractioned with filters of different pore-sizes to targeted different classes of taxa (pico: 0.2-3µm ; nano: 3-20µm and micro: >20µm). Most dominant bacteria were Alphaproteobacteria and Gammaproteobacteria, which altered in relative abundance between 15% to 47% and 11% to 21%, respectively. Third dominant bacterial class, Cyanobacteria, were most abundant in samples collected 13th of July when their abundances were 11-36% of total ASVs, while at 21st their abundance significantly dropped to levels 3-5% of total ASVs. Differences in community composition among size-fractions were observed mostly between nano and microplankton vs. picoplankton, where for example Actinobacteria were significantly more abundant in larger fractions ; while in pico-fraction archaeal taxa Nitrososphaeria were recorded in higher rel. abundances (8-12%). Eukaryotic plankton also showed significant differences in community composition among size classes, with mixotrophic Dinophyceae dominating in nano fraction (30-65%), parasitic Syndiniales dominating in pico-fraction (25-50%), while larger Arthropoda (ciliates and copepods) and Cnidaria (very likely parts of mesozooplankton, e.g. jellyfish) dominated in micro-fraction (69-87%).

metabarcoding ; plankton ; Lastovo

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