RAPID: Immediate and Subsequent Effects of Coral Bleaching on Fore Reef Community Metabolism

珊瑚礁是生产力最高的海洋生态系统之一，可提供重要的生态系统服务，如食物资源和海岸保护。珊瑚礁主要是由钙化的无脊椎动物(珊瑚)建造的，它们为包括许多鱼类在内的各种相关生物创造了栖息地。珊瑚对温度的耐受性范围很窄，当温度超过某个阈值时，它们会“漂白”，释放出主要的共生藻类。珊瑚可以从漂白中恢复，但更常见的结果是死亡。这有可能极大地改变珊瑚礁上有机和无机碳的循环，但我们对这些过程是如何影响的知之甚少。从2019年4月开始，法属波利尼西亚莫雷亚的珊瑚礁发生了中度严重的白化事件，这是唯一一个由NSF资助的专注于珊瑚礁的LTER项目的所在地。该项目利用MCR-LTER方案的知识，测量了最近的珊瑚漂白如何在前礁的两个深度立即(1个月后)和一年长的时间内影响珊瑚礁初级生产和钙化。这些是珊瑚漂白如何影响珊瑚礁前功能的第一次测量。该项目培训人员(博士后、技术员)，涉及研究生，结果被传播到几个教育级别(在美国和法属波利尼西亚)和摩尔的岛屿资源经理。该项目研究了最近在法属波利尼西亚莫雷亚发生的珊瑚漂白事件如何在两个深度随着时间的推移影响珊瑚前礁功能(初级生产力[NEP]、呼吸[R]、钙化[NEC])。我们知道珊瑚礁的组成会受到珊瑚漂白的很大影响。然而，我们对珊瑚礁功能是如何受到影响的知之甚少。该项目在岛屿周围6个地点以及10米和17米深的漂白之后的3个时间点测量珊瑚礁的功能。研究人员使用梯度通量方法，将垂直梯度量化为标量，并结合垂直扩散系数的测量来计算进出底栖生物的通量速率。他们从氧通量测量NEP/R，从pH和总碱度(DIC通量)测量NEC。所有的速率都被归一化为光合作用的有效辐射，以考虑光的时间变化。研究人员预测，漂白后NEP/R不会改变，甚至可能增加，但NEC与珊瑚死亡率成比例下降。珊瑚礁群落结构的新陈代谢“足迹”在每个地点/深度组合使用照片马赛克量化。这一奖项反映了国家科学基金会的法定使命，并已被认为是值得支持的评估使用基金会的智力价值和更广泛的影响审查标准。

Coral reefs are among the most productive marine ecosystems that provide important ecosystem services such as food resources and coastal protection. Coral reefs are constructed primarily by calcified invertebrates (corals), and they create habitat for a large diversity of associated organisms, including many fish species. Corals have a narrow range of temperature tolerance and when temperature exceeds a threshold, they "bleach" releasing their primary producing symbiotic algae. Corals can recover from bleaching but a more frequent outcome is mortality. This has the potential to drastically change of the cycle of organic and inorganic carbon on the reef, however we know little about how these processes are affected. Beginning in April 2019, there was a moderately severe bleaching event on the coral reefs of Moorea, French Polynesia, the site of the only NSF-funded LTER program focused on coral reefs. This project leverages knowledge from the MCR-LTER program and measures how the recent coral bleaching affects both reef primary production and calcification both immediately (after 1 month) and over a year- long period at two depths on the fore reef. These are the first measurements of how coral bleaching affects coral fore reef function. The project trains personnel (postdoc, technician), involve graduate students, and results are disseminated to several educational levels (in both the US and French Polynesia) and to island resource managers in Moorea.This project addresses how a recent coral bleaching event in Moorea, French Polynesia affects coral fore reef function (primary production [NEP], respiration [R], calcification [NEC]) over time at two depths. We know that coral reef composition can be affected greatly by coral bleaching. However, we know little about how coral reef function is affected. This project measures coral reef function at 3 time points following the bleaching at 6 sites around the island and at both 10 and 17-m depths. The investigators use a gradient flux approach that quantifies vertical gradients in scalar quantities combined with measures of vertical diffusivity to calculate rates of flux to and from the benthos. They measure NEP/R from oxygen flux and NEC from pH and total alkalinity (DIC flux). All rates are normalized to photosynthetically active radiation to account for temporal variation in light. The investigators predict that NEP/R will not change or might even increase post-bleaching but that NEC decreases in proportion to coral mortality. Coral reef community structure for the metabolic "footprint" at each site/depth combination is quantified using photo-mosaics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.