Collaborative Research: Revealing the changing trophic niches of large herbivorous fish on modern coral reefs using an interdisciplinary approach

合作研究：利用跨学科方法揭示现代珊瑚礁上大型草食性鱼类营养生态位的变化

• 批准号: 2232884
• 负责人: Jordan Casey
• 金额: $ 51.72万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2232884&HistoricalAwards=false
• 关键词: Collaborative; Research; Revealing; changing; trophic

Globally, coral reefs are experiencing human-induced disturbances with growing intensity and pace. Coral recovery after a disturbance is shaped, in part, by whether grazing herbivores prevent harmful algae from blooming and taking over the reef. This important grazing activity is carried out by a diverse group of co-existing herbivorous fish species, such as parrotfishes and surgeonfishes, which collectively control algae and thereby facilitate coral recovery. However, the specific types of algae that many of these fish feed on is largely unknown. It is also unknown if the feeding behaviors of these herbivores are constant, or instead depend on reef condition such as loss of coral. More detailed studies of herbivore diets are needed to understand how these species co-exist, as well as which species have unique roles and underpin key ecosystem processes on modern reefs. The aims of this project are thus to (a) define the feeding behaviors and diets of herbivorous fishes on healthy coral reefs – using both traditional and cutting-edge techniques – to better quantify resource partitioning among these herbivores, and (b) determine whether and how the feeding ecology of each herbivore shifts with changing reef conditions. To accomplish these objectives, the research team is focusing on core members of the coral reef herbivorous fish assemblage and quantifying their feeding ecology on reefs that range from minimally impacted to heavily degraded. By revealing hidden aspects of herbivore feeding, as well as which herbivorous fishes serve unique ecological roles, this project stands to reshape our understanding of coral reef ecology. More broadly, this project is: (1) cross-training a diverse group of undergraduate and graduate students in cutting-edge scientific methods, (2) augmenting public data repositories to foster scientific discovery across the wider scientific community, (3) sharing results with resource managers to enhance decision-making processes, and (4) increasing public science literacy and engagement via the co-development of visual art.On coral reefs, many herbivorous fish species co-exist and exert strong impacts on benthic communities via top-down control of a diverse algal assemblage. However, resource partitioning among these species is not fully understood and the extent of niche overlaps that exist among herbivorous fishes remains unknown. It also remains unknown how the feeding activities and diet (i.e., the “trophic niche”) of each herbivore shifts in response to changing ecosystem context, such as the loss of coral. Broad, higher-resolution studies are thus needed to understand how these species co-exist, as well as which species are functionally unique and underpin key ecosystem processes on modern reefs. The researchers’ preliminary work showed that DNA metabarcoding of gut contents, a cutting-edge tool, vastly improves niche descriptions for herbivorous fishes. This technique illuminates fine-scale differences among species, thus complementing previous approaches that, albeit coarser, quantify the niche at larger scales of space and time. The aims of this project are to (a) define the trophic niches of key herbivorous fishes on healthy reefs – using a combination of field observations, traditional diet tracing methods, compound-specific isotopes, and high-resolution DNA metabarcoding of gut contents – to better quantify the types and degree of trophic niche partitioning in such ecosystems, and (b) determine whether and how herbivore niches shift with changing reef condition. To meet these objectives, the researchers are characterizing the trophic niches of key members of the coral reef herbivorous fish guild (via the aforementioned methods) at numerous study sites that span a gradient of reef condition. By quantifying herbivore niche overlaps on healthy reefs, species-level niche expansions or contractions as a function of reef decline, and resultant impacts to total trophic niche breadth, this research is reshaping our understanding of large consumers on coral reefs, with implications for managing fisheries and reef processes simultaneously. More broadly, this study provides new insights into the niche – a fundamental concept in ecology that underlies topics ranging from species coexistence to the relationship between biodiversity and ecosystem function.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.

在全球范围内，珊瑚礁正以越来越大的强度和速度遭受人为干扰。珊瑚在受到干扰后的恢复，在一定程度上取决于食草动物是否能阻止有害藻类的繁殖和占领珊瑚礁。这一重要的放牧活动是由多种共存的草食性鱼类进行的，如鹦嘴鱼和刺尾鱼，它们共同控制藻类，从而促进珊瑚的恢复。然而，这些鱼所吃的藻类的具体类型在很大程度上是未知的。这些食草动物的摄食行为是恒定不变的，还是取决于珊瑚礁的状况，比如珊瑚的消失，这也是未知的。需要对食草动物的饮食进行更详细的研究，以了解这些物种如何共存，以及哪些物种在现代珊瑚礁上具有独特的作用并支撑关键的生态系统过程。因此，该项目的目的是(a)利用传统和尖端技术确定健康珊瑚礁上食草鱼类的摄食行为和饮食，以更好地量化这些食草动物之间的资源分配，以及(b)确定每种食草动物的摄食生态是否以及如何随着珊瑚礁条件的变化而变化。为了实现这些目标，研究小组专注于珊瑚礁草食性鱼类组合的核心成员，并量化它们在珊瑚礁上的摄食生态，范围从最小影响到严重退化。通过揭示草食动物喂养的隐藏方面，以及草食鱼类发挥独特的生态作用，该项目将重塑我们对珊瑚礁生态的理解。更广泛地说，该项目是：(1)交叉培训本科生和研究生的前沿科学方法，(2)扩大公共数据存储库，以促进更广泛的科学界的科学发现，(3)与资源管理者分享结果，以加强决策过程，(4)通过视觉艺术的共同发展提高公众的科学素养和参与度。在珊瑚礁上，许多草食性鱼类共存，并通过自上而下控制多样化的藻类组合对底栖生物群落产生强烈影响。然而，这些物种之间的资源分配并不完全清楚，草食性鱼类之间存在的生态位重叠程度仍然未知。每种食草动物的摄食活动和饮食（即“营养生态位”）如何响应不断变化的生态系统背景（如珊瑚的消失）而发生变化，这也是未知的。因此，需要更广泛、更高分辨率的研究来了解这些物种是如何共存的，以及哪些物种在功能上是独特的，并支撑着现代珊瑚礁的关键生态系统过程。研究人员的初步工作表明，肠道内容物的DNA元条形码（一种前沿工具）极大地改善了草食性鱼类的生态位描述。这项技术阐明了物种之间的细微差异，从而补充了之前的方法，尽管比较粗糙，但可以在更大的空间和时间尺度上量化生态位。该项目的目的是(a)通过野外观察、传统饮食追踪方法、化合物特异性同位素和肠道内容物的高分辨率DNA元条形码相结合，确定健康珊瑚礁上关键草食性鱼类的营养生态位，以更好地量化这种生态系统中营养生态位分配的类型和程度，以及(b)确定草食性生态位是否以及如何随着珊瑚礁条件的变化而变化。为了实现这些目标，研究人员在跨越珊瑚礁条件梯度的许多研究地点（通过上述方法）描述了珊瑚礁草食性鱼类协会主要成员的营养生态位。通过量化健康珊瑚礁上草食动物生态位的重叠，物种水平生态位的扩张或收缩作为珊瑚礁衰退的功能，以及由此产生的对总营养生态位宽度的影响，本研究正在重塑我们对珊瑚礁大消费者的理解，同时对渔业和珊瑚礁过程的管理具有启示意义。更广泛地说，这项研究为生态位提供了新的见解——生态位是生态学中的一个基本概念，是从物种共存到生物多样性和生态系统功能之间关系的基础。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。