Observation of polyp bailout after stress exposure in Primnoa pacifica

Abstract This study presents the first documented observation of polyp bailout in the red tree coral, Primnoa pacifica , an ecologically important species that forms dense aggregations in the North Pacific. Colonies exposed to environmental and physical stress during a collection event showed polyp detachment, with bailed polyps reattaching to an artificial substrate after two weeks. This process, similar to asexual reproduction, likely presents an acute stress response. Additionally, it facilitates both local and long-distance dispersal, particularly in the high-current environments this species inhabits. In fjord populations where gamete maturation appears incomplete, polyp bailout may provide an alternative mechanism for recruitment into deeper, more favorable habitats. Marine ecosystems are under increasing pressure from environmental change and human activities, where adverse conditions are becoming more frequent and intense. Polyp bailout may play a role in the distribution of P. pacifica by enabling individuals to avoid acute stressors.