Eight coral species in a 2.5-year mesocosm test show adaptive or dysbiotic symbiont shifts

In a 2.5-year factorial future-ocean mesocosm experiment, researchers tracked symbiont community shifts in eight coral species representing the major coral lineages, according to a study in Science Advances doi.orgScience Advancesdoi.orgOpen source ↗. They compared replicate fragments taken from the same individual coral doi.orgScience Advancesdoi.orgOpen source ↗. The authors note that coral reefs support over a quarter of marine species and nearly a billion people worldwide.

Responses differed between corals. Some showed stochastic divergence of symbiont communities, consistent with dysbiosis, while others showed deterministic, thermally adaptive shifts doi.orgScience Advancesdoi.orgOpen source ↗. Heat stress generally reduced symbiont diversity and promoted predictable restructuring of the community doi.orgScience Advancesdoi.orgOpen source ↗.

The authors report that the results support deterministic processes under moderate stress and stochastic dysbiosis under extreme conditions doi.orgScience Advancesdoi.orgOpen source ↗. They propose that adaptive and stochastic responses are endpoints along a continuum of host-orchestrated symbiont sorting doi.orgScience Advancesdoi.orgOpen source ↗. The study addresses a long-standing debate over whether coral symbioses will be disrupted or respond adaptively under future ocean conditions, and links coral reef ecology with broader host–microbiome theory doi.orgScience Advancesdoi.orgOpen source ↗.