3.5 Environmental and sea cucumber core microbiota
A majority of ASVs in microbiota communities (on average 73.59 % ± 6.74
SD) were considered rare because of their low representation among
samples (present in less than 30% of samples, as defined in Bjork et
al., 2018). On average, 13.64 % (± 3.38 SD) of ASVs were considered as
core (Table 4). Around 20.54 % of the core ASVs in the midgut or skin
were not found in either of the environmental samples, although a small
number of core ASVs were shared among the four sources (Figure 6). On
top of that, 13 ASVs belonging to the core midgut microbiome were absent
from sediment samples (Table S5). Indicator species also comprised on
average 13.97 % (± 9.43 SD) of the microbial community (Table S6). The
contributions of unique ASVs from different sources were different
between the three sites. The highest contribution of unique ASVs in
Starfish Bay and Tung Ping Chau originated from midgut samples, while
more unique skin ASVs were found in Lai Chi Chong (Figure 6).