Human‐induced expansion of oxygen‐deficient zones can have dramatic impacts on marine systems and its resident biota. One example is the formation of the potent neurotoxic methylmercury (MeHg) that is mediated by microbial methylation of inorganic divalent Hg (Hg II ) under oxygen‐deficient conditions. A negative consequence of the expansion of oxygen‐deficient zones could be an increase in MeHg production due to shifts in mic...

Regulating partner abundance may allow symbiotic organisms to mediate interaction outcomes, facilitating adaptive responses to environmental change. To explore the capacity for adaptive regulation in an ecologically important endosymbiosis, we studied the population dynamics of symbiotic algae in reef‐building corals under different abiotic contexts. We found high natural variability in symbiont abundance in corals across reef...