Causes and Impacts of Coral Reef Bleaching

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[...] Expanding on the broader implications of climate change for coral reefs, Veron et al. (2009) provided a comprehensive review of the "coral reef crisis," emphasizing the critical role of atmospheric CO2 levels. Veron et al. (2009) analysis synthesized evidence from palaeoecological records, contemporary observations, and climate/biogeochemical modeling to examine the causes, consequences, and potential thresholds associated with mass bleaching events and ocean acidification. Veron et al. (2009) documented the dramatic increase in mass coral bleaching events since the late 1970s, closely correlated with rising CO2 levels and the resulting heat stress. [...]

[...] (2022) proposed the concept of "mesoscale multinational sanctuaries" as a potential conservation strategy to sustain coral populations and facilitate adaptation through climate change. These sanctuaries, spanning thousands of square kilometers across national boundaries, would be designed to protect coral habitats, genetic diversity, and connectivity, providing a buffer against local and regional disturbances while preserving the raw material for evolutionary adaptation. Moreover, an advanced study by Boonnam et al. (2022) utilized machine learning techniques to model and predict coral reef bleaching risk based on environmental data collected over five years from sites in southern Thailand. Boonnam et al. [...]

[...] In the field, they monitored colonies of the coral species Seriatopora hystrix, both with and without resident damselfish populations at multiple sites around Lizard Island. They measured physiological markers like symbiont and chlorophyll density to quantify bleaching progression. Their key finding from the field observations was that S. hystrix colonies hosting damselfish maintained higher symbiont and chlorophyll levels than colonies without fish, even as the bleaching event unfolded (Chase et al. 2018). However, the buffering capacity of the fish was overwhelmed, with over 90% of colonies suffering whole colony mortality regardless of fish presence. Chase et al. [...]

[...] J., Oliver, J. K., Putnam, H. M., & Gates, R. D Building coral reef resilience through assisted evolution. Proceedings of the National Academy of Sciences, 112(8), 2307-2313. https://doi.org/10.1073%2Fpnas.1422301112 Van Woesik, R., Shlesinger, T., Grottoli, A. G., Toonen, R. J., Vega Thurber, R., Warner, M. E & Zaneveld, J. (2022). Coral-bleaching responses to climate change across biological scales. Global Change Biology, 28(14), 4229-4250. https://doi.org/10.1111/gcb.16192 Veron, J. E., Hoegh-Guldberg, O., Lenton, T. M., Lough, J. [...]

[...] Third, integrating observational data, experimental manipulations, and interdisciplinary analyses has yielded a more comprehensive understanding of coral bleaching. However, some inconsistencies and knowledge gaps remain, particularly in disentangling the complex interactions among environmental drivers and elucidating the molecular mechanisms underlying bleaching responses. To address the existential threat to coral reefs, the sources converge on the need for an integrated, multi-pronged strategy combining global mitigation efforts to reduce emissions, strengthened conventional management actions such as pollution control and marine protected areas, and the responsible development of new interventions aimed at assisting adaptation or reducing heat exposure on coral reefs. [...]