Coral environmental memory: causes, mechanisms, and consequences for future reefs.

The apparent ability of corals to acquire and maintain enhanced stress tolerance through a dose-dependent environmental memory, which may persist for multiple years, has critical implications for coral reef conservation research. Such responses are variable across coral species and environmental stressors, with primed corals exhibiting a modified response to secondary stress exposures. While the mechanisms underlying coral memory responses are poorly understood, they likely involve both the coral host and microbiome. With advances in molecular technologies, it is now possible to investigate potential memory mechanisms in non-model organisms, including transcriptional regulation through epigenetic modifications. We integrate evidence of coral environmental memory and suggest future research directions to evaluate the potential for this process to enhance coral resilience under climate change. Memory of a prior exposure to environmental stress can increase the tolerance of subsequent exposures, which is vital for sessile organisms. This phenomenon has been well described in terrestrial plants and there is evidence demonstrating environmental memory in marine organisms, particularly corals. Global climate change and local anthropogenic stressors have resulted in dramatic declines in many coral populations. Environmental memory may be an important mechanism for corals to cope with the rapidly changing climate, especially given their vulnerability to environmental stress. Increased coral stress tolerance has been observed across recurrent marine heatwaves and following experimentally applied stress exposures. Such 'stress hardening' methods have recently been highlighted as priority conservation interventions to enhance coral resilience. [ABSTRACT FROM AUTHOR]