The highest number of unique OTUs (178) and reads (53681) were in the natural community of Vostok Bay. Of these, 156 OTUs with 93.7% of the reads belonged to Eukaryota. The Bacteria in this sample included representatives of the only family Flavobacteriaceae, which contained the genera Aquimarina, Formosa, and Polaribacter. The latter accounted for the majority of bacterial OTUs (83.3%) and reads (98.7%). The species-level identity of the bacterial OTUs was not possible to determine. Among the found eukaryotic OTUs there were 16 phyla, 30 classes, 51 orders, 65 families, 74 genera, and about one hundred unambiguously defined clusters of putatively species rank (Table S2). The most of the found OTUs (61) belonged to the plylum Bacillariophyta. This plylum also accounted for more than a half (51.8%) of all reads. The vast majority of reads per OTU were from the genus Phoronopsis (7511 or 14.9%). More than 1000 reads per OTU also came from the species Ditylum brightwellii, Coscinodiscus wailesii, Thalassiosira nordenskioeldii, Minutocellus polymorphus, Asterionellopsis glacialis, Coscinodiscus sp. and Thalassiosira punctigera of Bacillariophyta plylum, as well as genera Hyaloperonospora of Oomycota plylum and Macrocystis pyrifera of Ochrophyta plylum (Figure S1, Table S1). No OTUs belonging to P. latirostris or related decapods were detected, nor were the species of Zostera in whose belts the samples were collected.
Among the samples of artificial communities, as well as individual samples of environmental DNA and those from the reservoir tank in the aquarium, there were almost no common OTUs. With the exception of Oncorhynchus keta species OTU with a high number of reads (from 23 to 793 per sample). In the environmental DNA samples from hydrobionts genotyped by the first and second haplotype samples of P. latirostris, 44 and 38 OTUs were detected, respectively; in the first, second and third haplotype samples of H. octogrammus, 30, 37 and 23 OTUs were found. The first and second haplotype samples of P. dybowskii accounted for the least number of OTUs – 5 and 19. Vostok and Vityaz Bays mock samples had 47 and 50 OTUs, respectively, and the storage tank had 39 OTUs (Table S1).