Table 4. Core and abundant OTUs found in the Porphyra umbilicalis microbiome identified using V5V6 (Taxonomic level 2 = phylum, 3 = class, 4 = order, 5 = family, 6 = genus).

A. Core Microbiomea
Tax level	Taxon	No. of OTUs	OTU code number
2	Bacteroidetes	9
3	Sphingobacteria	2
4	Sphingobacteriales	2	4509(W)*, 4580(W)*
3	Flavobacteria	6
5	Flavobacteriaceae	6	3834(E), 3913(E), 3944(F), 3969(E), 4507(F)*, 4510(W)* L
2	Chloroflexi	1	4599(W)*
2	Planctomycetes	2
3	Phycisphaerae	1
5	Phycisphaeraceae	1
6	Phycisphaera	1	3875(W)
3	Planctomycetacia	1
5	Planctomycetaceae	1	3994(F)*
2	Proteobacteria	1
3	Alphaproteobacteria	1
5	Rhodobacteraceae	1	4349(W)* L
2	Unclassified(Bacteria)	6	2742(E), 4252(F)*, 4368(E), 4392(F)*, 4453(W),4491(E)*
B. Lab: Most abundant OTUsb
Tax level	Taxon	No. of OTUs	OTU code number
2	Bacteroidetes	1
3	Flavobacteria	1
5	Flavobacteriaceae	1	4510
2	Proteobacteria	1
3	Alphaproteobacteria	1
5	Rhodobacteraceae	1	4349
2	Unclassified (Bacteria)	1	2443
C. Field: Most abundant OTUsc
Tax level	Taxon	No. of OTUs	OTU code number
2	Bacteroidetes	3
3	Sphingobacteria	2
4	Sphingobacteriales	2	4509, 4580
3	Flavobacteria	1
5	Flavobacteriaceae	1	4507
2	Chloroflexi	1	4599
2	Unclassified (Bacteria)	2	4392, 4491

^a19 OTUs (0.03 distance) shared between Fall, Winter & Lab Groups

^*present at ≥1% of all sequences on at least one blade (n = 12)

^{* L} ≥1% on a lab blade

^bOTUs (0.03 distance) with sequence abundance greater than 1% on both lab blades

^cOTUs (0.03 distance) with sequence abundance greater than 1% on at least 3 of the 10 winter (n = 5) and fall (n = 5) blades

Designations of F = Fall, E = Evenly distributed between fall and winter, W = Winter refer to a ≥3× skew in sequence abundance toward that group.