Interventions to help coral reefs under global change—A complex decision challenge

Abstract

Climate change is impacting coral reefs now. Recent pan-tropical bleaching events driven by unprecedented global heat waves have shifted the playing field for coral reef management and policy. While best-practice conventional management remains essential, it may no longer be enough to sustain coral reefs under continued climate change. Nor will climate change mitigation be sufficient on its own. Committed warming and projected reef decline means solutions must involve a portfolio of mitigation, best-practice conventional management and coordinated restoration and adaptation measures involving new and perhaps radical interventions, including local and regional cooling and shading, assisted coral evolution, assisted gene flow, and measures to support and enhance coral recruitment. We propose that proactive research and development to expand the reef management toolbox fast but safely, combined with expedient trialling of promising interventions is now urgently needed, whatever emissions trajectory the world follows. We discuss the challenges and opportunities of embracing new interventions in a race against time, including their risks and uncertainties. Ultimately, solutions to the climate challenge for coral reefs will require consideration of what society wants, what can be achieved technically and economically, and what opportunities we have for action in a rapidly closing window. Finding solutions that work for coral reefs and people will require exceptional levels of coordination of science, management and policy, and open engagement with society. It will also require compromise, because reefs will change under climate change despite our best interventions. We argue that being clear about society's priorities, and understanding both the opportunities and risks that come with an expanded toolset, can help us make the most of a challenging situation. We offer a conceptual model to help reef managers frame decision problems and objectives, and to guide effective strategy choices in the face of complexity and uncertainty.

The coral conservation crisis: interacting local and global stressors reduce reef resiliency and create challenges for conservation solutions

“…The increase in the severity and frequency of marine heatwaves challenges conventional management strategies [59,107]. Therefore, there is a critical need to reassess restoration and management strategies to sustain coral reef ecosystems under these continuing challenging conditions [108]. The global coral reef degradation that has occurred over the last 30-40 years has shifted coral reef resilience and therefore requires focused science and management efforts to prevent the loss of valuable social, ecological, and cultural resources [109].…”

“…Science advancements have shifted to promote coral reef resilience through an adaptation-focused intervention that will account for a suite of multiple stressors [57,108]. Assisted evolution, the acceleration of evolutionary processes through the enhancement of specific traits, includes four mechanisms to increase environmental stress tolerance: (1) epigenetic programming and exposing adult colonies to high levels of environmental stress, (2) manipulation of the microbes associated with the coral holobiont, (3) culturing coral-associated endosymbiotic algae (Symbiodinium spp.)…”

“…New interventions, such as genetic engineering, could be added to the coral reef restoration toolbox, but there are challenges in managing risks and uncertainties ( Fig. 1) [108]. Therefore, while advances in science are important to consider when making a restoration plan, it is imperative to create a risk assessment outlining all…”

“…The structured decision-making framework, created by Anthony et al, 2020, can help develop a management plan for high-risk ecosystems or watersheds [108]. This framework allows for the creation of a risk-assessment that integrates both local and global management efforts (Fig.…”

Optimising cool-water injections to reduce thermal stress on coral reefs of the Great Barrier Reef

“…The mechanism by which temperature and light drives bleaching is through the build-up of reactive oxygen stress inside the coral host due to inactivation of the zooxanthallae photosystem at anomalously-high summertime temperatures [ 4 , 5 ]. As a result of the direct dependence of bleaching on environmental temperature and light levels, researchers have advocated interventions to reduce light reaching corals and/or to cool the water surrounding corals [ 6 – 8 ].…”