Global analysis of temperature regimes to stratify the management of coral reefs for climate change

数亿人依靠珊瑚礁为生和食物来源。珊瑚礁提供的几乎所有生态系统服务都建立在活珊瑚上，通过与共生藻类的共生，活珊瑚能够沉积珊瑚骨架。不幸的是，这种共生是不稳定的，很容易受到热应力的干扰；海洋温度的迅速上升只有1摄氏度，可能会导致大片珊瑚死亡。事实上，巴哈马活珊瑚覆盖的模式与1998年的热应力强度密切相关(孟比未公布的数据)。随着全球变化导致海洋温度持续上升，珊瑚礁是地球上最受威胁的生态系统之一。珊瑚礁管理者无力避免其管辖范围内的海温上升。然而，对来自巴哈马群岛的卫星海温数据的试点分析表明，在白化事件期间，一些珊瑚礁承受的压力比其他珊瑚礁大得多。此外，一些珊瑚礁在非漂白年份通常比其他珊瑚礁更冷，这意味着珊瑚对温度的适应程度在整个海景中是可以预测的不同。慢性热应激(在正常非漂白期间)和急性热应激(在漂白事件期间)的大规模模式的存在，为试图在地方尺度上管理气候变化提供了新的机会。可以确定的是，在白化事件期间，预计会经历较低水平的物理压力的珊瑚礁区域-可能是因为高海浪暴露区域混合了水柱，有助于其降温。如果管理者随后将他们的干预目标对准这些地区，例如指定海洋保护区(减少生物压力，如海藻过度生长珊瑚)，那么气候变化的影响在这些地点将被降至最低的可能性相对较大。换句话说，管理者可以将他们的努力目标放在最小化生物压力上，从而使一些珊瑚礁总体上经历最低水平的压力。虽然我们已经在试点分析中证明了我们方法的有效性(提案中给出了其中一个结果)，但这笔NERC赠款允许我们通过测试其在全球范围内的适用性来完成我们的研究。此外，全球分析将使我们能够检验关于推动珊瑚礁海洋温度模式的过程的假说，并产生新的假说以供后续行动。所有需要的数据集都已经可用，因此我们只需要员工时间来处理我们的全局数据集并执行一些特定的分析。我们的结果将产生广泛影响，因为它们评估了在世界各地的珊瑚礁上管理气候变化的范围。那些在热应力上没有很大地理差异的地区将不适合对珊瑚白化进行分层管理，因此这将是此类地区管理武器库中的一个减少工具。然而，如果确实存在适当的地域差异，这笔赠款的产出将使管理人员能够立即开始对其活动进行分层。该项目是以当地资源管理为目标解决全球气候变化问题的首批示范项目之一。因此，我们预计会对可持续管理和气候变化的科学产生广泛的影响。

Hundreds of millions of people depend on coral reefs for their livelihood and source of food. Almost all of the ecosystem services provided by reefs are founded upon living corals which, through a mutualism with symbiotic algae, are able to deposit a coral skeleton. Unfortunately, this symbiosis is precarious and easily disturbed by thermal stress; rapid increases in sea temperature of only 1 degree can result in massive areas of coral dying off. Indeed, patterns of living coral cover in the Bahamas are strongly associated with the intensity of thermal stress in 1998 (Mumby unpublished data). With sea temperatures continuing to rise through global change, coral reefs are one of the most threatened ecosystems on Earth. Coral reef managers are powerless to avert the rise of sea temperature within their jurisdiction. However, a pilot analysis of satellite-derived sea temperature data from the Bahamas shows that some reefs experience much greater stress than others during a bleaching event. Furthermore, some reefs are routinely cooler than others during non-bleaching years which implies that the acclimation of corals to temperature varies predictably across the seascape. The existence of large-scale patterns in both chronic thermal stress (during normal non-bleaching periods) and acute thermal stress (during bleaching events), provides novel opportunities for attempting to manage climate change at local scales. Areas of reef can be identified that are expected to experience lower levels of physical stress during bleaching events - probably because areas of high wave exposure mix the water column and help it cool. If managers then target their interventions, such as marine reserve designation (which reduces biological stress such as the overgrowth of coral by seaweed), to these areas then there is a relatively strong possibility that the effects of climate change will be minimised at such sites. In other words, managers can target their efforts on minimising biological stress so that some reefs experience minimal levels of stress overall. Although we have demonstrated the efficacy of our approach in a pilot analysis (one of the results of which is given in the proposal), this NERC grant allows us to complete our study by testing its applicability at global scales. Moreover, a global analysis will enable us to test a hypothesis concerning the processes driving patterns of sea temperature on reefs and generate new hypotheses to follow up. All of the datasets required are already available so we simply require staff time to process our global dataset and carry out some specific analyses. Our results will have widespread impact because they assess the scope for managing climate change on reefs throughout the World. Those regions that do not possess great geographic variation in thermal stress will not lend themselves to a stratification of management for coral bleaching, so this will be one less tool in the management arsenal for such places. However, where appropriate geographic variation does exist, outputs from this grant will enable managers to begin stratifying their activities immediately. This project is one of the first demonstrations of targeting local resource management to address the problem of global climate change. As such, we anticipate a broad impact upon the science of sustainable management and climate change.