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

数以亿计的人依靠珊瑚礁维持生计和食物来源。珊瑚礁提供的几乎所有生态系统服务都是以活珊瑚为基础的，活珊瑚通过与共生藻类的互惠共生，能够存款珊瑚骨架。不幸的是，这种共生关系是不稳定的，很容易受到热应力的干扰;海水温度仅上升1度就可能导致大面积的珊瑚死亡。事实上，巴哈马活珊瑚覆盖的格局与1998年的热应力强度密切相关（Mumby未公布的数据）。随着全球气候变化，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。珊瑚礁管理者无力阻止其管辖范围内海水温度的上升。然而，对巴哈马卫星获取的海水温度数据进行的试点分析表明，在白化事件期间，一些珊瑚礁比其他珊瑚礁承受的压力大得多。此外，在非白化年份，一些珊瑚礁通常比其他珊瑚礁更冷，这意味着珊瑚对温度的适应在整个海景中可预测地变化。在慢性热应力（在正常的非漂白期）和急性热应力（漂白事件）的大规模模式的存在，提供了新的机会，试图在当地尺度上管理气候变化。可以确定的珊瑚礁区域预计将经历较低水平的物理压力在漂白事件-可能是因为高波暴露的地区混合水柱，并帮助它冷却。如果管理者将他们的干预措施，如海洋保护区的指定（减少生物压力，如海藻对珊瑚的过度生长），针对这些地区，那么气候变化的影响将在这些地点被最小化的可能性相对较强。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，以便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（其中一个结果在提案中给出），但NERC的资助使我们能够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驱动珊瑚礁海水温度模式的过程的假设，并提出新的假设。所有所需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球数据集并进行一些特定的分析。我们的研究结果将产生广泛的影响，因为它们评估了世界各地珊瑚礁管理气候变化的范围。那些在热应力方面没有很大地理差异的地区将不适合对珊瑚漂白进行分层管理，因此这将是这些地方管理武器库中的一个工具。但是，如果确实存在适当的地域差异，则该补助金的产出将使管理人员能够开始立即对其活动进行分层。该项目是针对当地资源管理以解决全球气候变化问题的首批示范项目之一。因此，我们预计这将对可持续管理和气候变化科学产生广泛影响。

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of living coral cover in the Bahamas are strongly associated with the intensity of thermal stress in 1998 (Mumby unpublished data).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.