Data from: Increased diversity and concordant shifts in community structure of coral-associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

Coral-associated bacteria and endosymbiotic algae (Symbiodiniaceae spp.)
are both vitally important for the biological function of corals. Yet
little is known about their co-occurrence within corals, how their
diversity varies across coral species, or how they are impacted by
anthropogenic disturbances. Here, we sampled coral colonies (n =
472) from seven species, encompassing a range of life history traits,
across a gradient of chronic human disturbance (n = 11 sites on Kiritimati
(Christmas) atoll) in the central equatorial Pacific, and quantified the
sequence assemblages and community structure of their associated
Symbiodiniaceae and bacterial communities. Although Symbiodiniaceae alpha
diversity did not vary with chronic human disturbance, disturbance was
consistently associated with higher bacterial Shannon diversity and
richness, with bacterial richness by sample almost doubling from sites
with low to very high disturbance. Chronic disturbance was also associated
with altered microbial beta diversity for Symbiodiniaceae and bacteria,
including changes in community structure for both and increased variation
(dispersion) of the Symbiodiniaceae communities. We also found concordance
between Symbiodiniaceae and bacterial community structure, when all corals
were considered together, and individually for two massive species,
Hydnophora microconos and Porites lobata, implying that symbionts and
bacteria respond similarly to human disturbance in these species. Finally,
we found that the dominant Symbiodiniaceae ancestral lineage in a coral
colony was associated with differential abundances of several distinct
bacterial taxa. These results suggest that increased beta diversity of
Symbiodiniaceae and bacterial communities may be a reliable indicator of
stress in the coral microbiome, and that there may be concordant responses
to chronic disturbance between these communities at the whole-ecosystem
scale.