A role for bacterial experimental evolution in coral bleaching mitigation?

Coral reefs are rapidly declining because of widespread mass coral bleaching causing extensive coral mortality. Elevated seawater temperatures are the main drivers of coral bleaching, and climate change is increasing the frequency and severity of destructive marine heatwaves. Efforts to enhance coral thermal bleaching tolerance can be targeted at the coral host or at coral-associated microorganisms (e.g., dinoflagellate endosymbionts and bacteria). The literature on experimental evolution of bacteria suggests that it has value as a tool to increase coral climate resilience. We provide a workflow on how to experimentally evolve coral-associated bacteria to confer thermal tolerance to coral hosts and emphasize the value of implementing this approach in coral reef conservation and restoration efforts. Coral mortality has drastically increased in recent years because of climate change, and there is increasing evidence that coral-associated bacteria play a role in coral thermal tolerance. Approaches targeted at coral-associated microorganisms aim to provide corals with tools to adapt more quickly to increasing temperatures. This includes the inoculation of corals with probiotic bacteria. Experimental evolution is a powerful method whereby organisms are maintained under given selection pressures for many generations, hence forcing adaptation. Microorganisms can be evolved very quickly because of their short generation time. Coral-bleaching-related selection pressures, such as oxidative stress, have successfully enhanced antioxidant capacity in candidate bacteria. Application of such approaches could increase antioxidant capacity in coral-targeted probiotics and enhance coral climate resilience. [ABSTRACT FROM AUTHOR]