Data underlying publication: Seagrass ecosystem multifunctionality under the rise of a flagship marine megaherbivore

This dataset contains the data collected from field experiments that assessed the effects of experimentally simulated grazing intensity scenarios on ecosystem functions and multifunctionality in a tropical Caribbean seagrass ecosystem. <strong>Abstract of the paper</strong> Large grazers (megaherbivores) have a profound impact on ecosystem functioning. However, how ecosystem multifunctionality is affected by changes in megaherbivore populations remains poorly understood. Understanding the total impact on ecosystem multifunctionality requires an integrative ecosystem approach, which is especially challenging to obtain in marine systems. We assessed the effects of experimentally simulated grazing intensity scenarios on ecosystem functions and multifunctionality in a tropical Caribbean seagrass ecosystem. As a model, we selected a key marine megaherbivore, the green turtle, whose ecological role is rapidly unfolding in numerous foraging areas where populations are recovering through conservation after centuries of decline, with an increase in recorded overgrazing episodes. To quantify the effects, we employed a novel integrated index of seagrass ecosystem multifunctionality based upon multiple, well-recognized measures of seagrass ecosystem functions that reflect ecosystem services. Experiments revealed that intermediate turtle grazing resulted in the highest rates of nutrient cycling and carbon storage, while sediment stabilization, decomposition rates, epifauna richness, and fish biomass are highest in absence of turtle grazing. In contrast, intense grazing resulted in disproportionally large effects on ecosystem functions and a collapse of multifunctionality. These results imply that i) the return of a megaherbivore can exert strong effects on coastal ecosystem functions and multifunctionality, ii) conservation efforts that are skewed towards megaherbivores, but ignore their key drivers like predators or habitat, will likely result in overgrazing-induced loss of multifunctionality, and iii) the multifunctionality index shows great potential as a quantitative tool to assess ecosystem performance. Considerable and rapid alterations in megaherbivore abundance (both through extinction and conservation) cause an imbalance in ecosystem functioning and substantially alter or even compromise ecosystem services that help to negate global change effects. An integrative ecosystem approach in environmental management is urgently required to protect and enhance ecosystem multifunctionality.

本数据集涵盖野外实验采集所得数据，相关实验旨在评估人工模拟放牧强度情景对加勒比热带海草生态系统（seagrass ecosystem）的生态系统功能与生态系统多功能性（ecosystem multifunctionality）的影响。<strong>论文摘要</strong> 大型植食动物（megaherbivores）对生态系统功能具有深远影响。然而，大型植食动物种群变化对生态系统多功能性的影响机制仍不甚明晰。全面理解其对生态系统多功能性的总影响，需采用整合式生态系统研究方法，而在海洋生态系统中获取此类方法尤为困难。本研究以加勒比热带海草生态系统为研究对象，评估了人工模拟放牧强度情景对其生态系统功能与多功能性的影响。本研究选取一种关键海洋大型植食动物——绿海龟作为研究模型。绿海龟的生态角色在诸多觅食区域正逐步被揭示：在经历数百年种群衰退后，其种群通过保护措施得以恢复，但记录在案的过度放牧事件也随之增多。为量化此类影响，本研究基于多项公认的、可反映生态系统服务功能的海草生态系统功能指标，构建了一种全新的海草生态系统多功能性整合指数。实验结果显示，中等强度的海龟放牧可实现最高的养分循环速率与碳储存能力；而在无海龟放牧的情况下，沉积物稳定能力、分解速率、附生动物物种丰富度以及鱼类生物量均达到最高水平。与之相对，高强度放牧则会对生态系统功能造成不成比例的严重影响，并导致多功能性崩溃。本研究结果表明：其一，大型植食动物的回归可对海岸生态系统功能与多功能性产生显著影响；其二，若保护工作仅偏向大型植食动物，却忽视其关键调控因子（如捕食者或栖息地），则可能因过度放牧导致生态系统多功能性丧失；其三，该多功能性指数具备作为评估生态系统状态的量化工具的巨大潜力。大型植食动物种群数量的剧烈快速变化（无论因灭绝还是保护措施所致）会打破生态系统功能的平衡，并大幅改变甚至削弱那些有助于抵消全球变化影响的生态系统服务功能。当前亟需在环境管理中采用整合式生态系统研究方法，以保护并提升生态系统多功能性。