Instructions and considerations for ecosystem based management in a useful guide.

Observations of coral reef losses to climate change far exceed our understanding of historical degradation before anthropogenic warming. This is a critical gap to fill as conservation efforts simultaneously work to reverse climate change while restoring coral reef diversity and function. Here, we focused on southern China’s Greater Bay Area, where coral communities persist despite centuries of coral mining, fishing, dredging, development, and pollution. We compared subfossil assemblages with modern-day communities and revealed a 40% decrease in generic diversity, concomitant to a shift from competitive to stress-tolerant species dominance since the mid-Holocene. Regions with characteristically poor water quality—high chl-a, dissolved inorganic nitrogen, and turbidity—had lower contemporary diversity and the greatest community composition shift observed in the past, driven by the near extirpation of Acropora. These observations highlight the urgent need to mitigate local stressors from development in concert with curbing greenhouse gas emissions.

Economic development and environmental conservation are often seen as opposing forces in the arena of government policy-making. With more than 7 million people and a rich diversity of marine species and habitats, Hong Kong is an excellent case study to explore this dynamic. Despite anthropogenic impacts, Hong Kong still hosts more than 90 species of stony corals within a marine area of 1650 km2. This is remarkable in light of the global plight of coral reefs, which have been reduced by ~80% worldwide in recent decades. The Hong Kong Special Administrative Region has not been immune to this negative trend with an unfortunate track of marine environmental disasters and, as such, can be viewed a harbinger for the future trajectory of coral reefs worldwide. Yet, the story is not entirely negative. Hong Kong possesses key assets, including capable government environmental agencies and competitive research led by local universities, which can bring novel and promising approaches for coral biodiversity conservation in an urbanized context. To coordinate and assist conservation efforts in Hong Kong, we here identify and prioritize major management efforts and identify knowledge gaps for coral conservation based on updated coral biodiversity distribution and a current literature review. Specifically, we propose five priorities for the most positive impact on conservation efforts: (1) reconstruct environmental baselines and establish long-term monitoring of local coral communities, (2) enhance the management and protection of local coral habitats, (3) improve water quality, (4) gain an understanding of the genetic connectivity among local and distant coral communities, and finally, (5) establish an active restoration program for local coral species/communities. In order to build progressive and integrative management strategies for coral biodiversity conservation in Hong Kong, we suggest specific ways in which these priorities be addressed and encourage a fresh dialogue between the government, the public and academia

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