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Climate change is the primary threat to coral reefs, causing catastrophic coral mortality on a global scale. Stressors such as ocean acidification limit calcium carbonate availability needed to build skeletons. A wealth of research has shown that climate stressors impair the ability of coral to produce and maintain their skeletons, thereby disrupting functions critical to maintaining coral health as well as threatening the ecologically significant framework for reef building. There are natural marginal and extreme environments however, where coral reefs thrive despite unfavourable conditions. These habitats provide a natural long-term setting to examine the impact of multiple interacting climate change factors on corals and understand the adaptations required by corals to inhabit these conditions. We review studies of coral skeletogenesis in extreme and marginal environments, with a particular focus on mangrove habitats due to their natural fluctuations in temperature, pH and oxygen, analogous to those projected under climate change models. The changes in coral skeletal morphology under stress are described as are the techniques used to visualise these changes. In marginal and extreme environments, corals experience lower calcification rates and produce more porous, less robust skeletons whilst maintaining normal rates of linear extension, suggesting the integrity of coral skeletons are likely to be threatened under future ocean conditions. The biomineralisation processes of corals inhabiting extreme and marginal environments remains an underexplored area of research and has the potential to yield valuable insights into how corals might adapt to climate change and the mechanisms that underlie their resilience to global environmental change. [ABSTRACT FROM AUTHOR]

To persist in an ocean changing in temperature, pH and other stressors related to climate change, many marine species will likely need to acclimatize or adapt to avoid extinction. If marine populations possess adequate genetic variation in tolerance to climate change stressors, species might be able to adapt to environmental change. Marine climate change research is moving away from single life stage studies where individuals are directly placed into projected scenarios ('future shock' approach), to focus on the adaptive potential of populations in an ocean that will gradually change over coming decades. This review summarizes studies that consider the adaptive potential of marine invertebrates to climate change stressors and the methods that have been applied to this research, including quantitative genetics, laboratory selection studies and trans- and multigenerational experiments. Phenotypic plasticity is likely to contribute to population persistence providing time for genetic adaptation to occur. Transgenerational and epigenetic effects indicate that the environmental and physiological history of the parents can affect offspring performance. There is a need for long-term, multigenerational experiments to determine the influence of phenotypic plasticity, genetic variation and transgenerational effects on species' capacity to persist in a changing ocean. However, multigenerational studies are only practicable for short generation species. Consideration of multiple morphological and physiological traits, including changes in molecular processes (eg, DNA methylation) and long-term studies that facilitate acclimatization will be essential in making informed predictions of how the seascape and marine communities will be altered by climate change. [ABSTRACT FROM AUTHOR]

Written to serve as a guideline for future research in this field, this roadmap provides some perspectives on the main developments and remaining challenges in the field of marine animal acclimatisation, adaptive potential and resilience to climate change. There has been extensive research conducted on the impact of climate change stress on marine animals, with studies recognising the potential for cross- and multi-generational impacts. Parents can potentially pass on resilience to offspring. The response of marine animals to climate change stressors is complex where utilising marginal and extreme systems as natural laboratories can help to address key research gaps and provide an understanding of the plastic and adaptive changes necessary for survival under stress. [ABSTRACT FROM AUTHOR]

Globally, coral reefs are degrading due to a variety of stressors including climate change and pollution. Active restoration is an important effort for sustaining coral reefs where, typically, coral fragments are outplanted onto degraded reefs. Coral outplants, however, can experience mortality in response to a range of stressors. We pair results of outplant monitoring observations with satellite‐based measurements of multiple oceanographic variables to estimate the relative importance of each driver to coral outplant survival. We find that when considering mean environmental conditions experienced by outplants during the monitoring period, particulate organic carbon (POC) levels are most important in determining outplant survival, with certain levels of POC beneficial for outplants. Sea surface temperature anomalies (SSTA) are also important determinants of outplant survival, where survival is greatest in regions with minimal or slightly negative anomalies. Survival also increases with increasing distance to land, likely due to a reduction in negative ridge‐to‐reef effects on coral outplants. When considering the range (min–max) of environmental conditions experienced during the monitoring period, large fluctuations in photosynthetically active radiation (PAR) and POC are most important in determining outplant survival. Increasing outplant depth can help to counter the negative impacts of large fluctuations in environmental variables. We find that a variety of remotely sensed oceanographic variables have significant impacts on survival and should be considered in coral restoration planning to help evaluate potential restoration sites and ultimately maximize coral outplant survival. [ABSTRACT FROM AUTHOR]

Although cross generation (CGP) and multigenerational (MGP) plasticity have been identified as mechanisms of acclimation to global change, the weight of evidence indicates that parental conditioning over generations is not a panacea to rescue stress sensitivity in offspring. For many species, there were no benefits of parental conditioning. Even when improved performance was observed, this waned over time within a generation or across generations and fitness declined. CGP and MGP studies identified resilient species with stress tolerant genotypes in wild populations and selected family lines. Several bivalves possess favourable stress tolerance and phenotypically plastic traits potentially associated with genetic adaptation to life in habitats where they routinely experience temperature and/or acidification stress. These traits will be important to help 'climate proof' shellfish ventures. Species that are naturally stress tolerant and those that naturally experience a broad range of environmental conditions are good candidates to provide insights into the physiological and molecular mechanisms involved in CGP and MGP. It is challenging to conduct ecologically relevant global change experiments over the long times commensurate with the pace of changing climate. As a result, many studies present stressors in a shock‐type exposure at rates much faster than projected scenarios. With more gradual stressor introduction over longer experimental durations and in context with conditions species are currently acclimatized and/or adapted to, the outcomes for sensitive species might differ. We highlight the importance to understand primordial germ cell development and the timing of gametogenesis with respect to stressor exposure. Although multigenerational exposure to global change stressors currently appears limited as a universal tool to rescue species in the face of changing climate, natural proxies of future conditions (upwelling zones, CO2 vents, naturally warm habitats) show that phenotypic adjustment and/or beneficial genetic selection is possible for some species, indicating complex plasticity–adaptation interactions. [ABSTRACT FROM AUTHOR]

CO SB 2 sb vent systems are not perfect analogues of future ocean acidification; however, they are invaluable for providing a window into the future state of organisms, communities and ecosystems in a high CO SB 2 sb ocean. Oceans have absorbed approximately 30% of anthropogenic CO SB 2 sb emissions, causing a phenomenon known as "ocean acidification". [Extracted from the article]