Bähr Susanne, Dunn Natalie, van der Meij Sancia E T, Chowdhury Joydeep, Benzoni Francesca
Marine Science Program, Biological and Environmental Science and Engineering Division (BESE) King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia.
Groningen Institute for Evolutionary Life Sciences (GELIFES) University of Groningen Groningen the Netherlands.
Ecol Evol. 2025 Jun 3;15(6):e71474. doi: 10.1002/ece3.71474. eCollection 2025 Jun.
Symbiotic relationships between corals and invertebrates contribute significantly to coral reef biodiversity. However, their ecological functions within this ecosystem remain understudied due to limited knowledge of the interplay among lifehistory strategies, host density and condition, population variations, and mortality rates. To address this, we investigated the population dynamics of coral-dwelling gall crabs (Cryptochiridae), obligate symbionts of scleractinian corals, across four central Red Sea reefs. Combining transect surveys with a novel fate-tracking approach, we monitored 799 crabs on 517 host colonies from September 2022 to 2024. Our data revealed significant variation in host community composition, with reef-specific conditions shaping crab abundance and diversity more than cross-shelf gradients. Fate-tracking uncovered unexpectedly frequent crab colonization and extinction events and a strong preference for settling on already inhabited hosts. In 2023, a mass reef bleaching event provided a unique opportunity to assess disturbance impacts one year into our study, resulting in greater population declines on inshore reefs. Interestingly, fate-tracking showed that most sites maintained reproductively active crab populations despite bleaching, while compounded stressors at one site caused a local population collapse. Our findings underscore the complex dynamics of the relationship between cryptochirids and their coral hosts, where high reproductive output may offset the costs of host specificity and settlement requirements, thus enabling resilience to moderate disturbances. This study provides novel insights into cryptochirid ecology, revealing unexpectedly high temporal variability in their populations. The observed dynamics suggest gall crabs may occupy a functional role akin to cryptobenthic reef fish by contributing to reef energy transfer, converting host-derived resources like coral mucus into forms accessible to higher trophic levels and supplementing zooplankton communities with larvae. In light of increasing disturbances, this study highlights the need to integrate reef invertebrates into coral reef conservation strategies for preserving biodiversity and sustaining ecosystem functionality in a rapidly changing world.
珊瑚与无脊椎动物之间的共生关系对珊瑚礁生物多样性有重大贡献。然而，由于对生活史策略、宿主密度与状况、种群变化及死亡率之间相互作用的了解有限，它们在这个生态系统中的生态功能仍未得到充分研究。为解决这一问题，我们调查了红海中部四个珊瑚礁上栖息于珊瑚的瘿蟹（隐螯蟹科）的种群动态，瘿蟹是石珊瑚的专性共生体。我们将断面调查与一种新颖的命运追踪方法相结合，在2022年9月至2024年期间监测了517个宿主群体上的799只螃蟹。我们的数据显示宿主群落组成存在显著差异，特定珊瑚礁的条件对螃蟹丰度和多样性的塑造作用大于跨陆架梯度。命运追踪发现螃蟹的定殖和灭绝事件出乎意料地频繁，并且它们强烈倾向于在已被占据的宿主上定居。2023年，一次大规模的珊瑚礁白化事件为我们评估研究进行一年后的干扰影响提供了独特机会，导致近海珊瑚礁上的种群数量下降幅度更大。有趣的是，命运追踪表明尽管发生了白化，大多数地点的螃蟹种群仍保持繁殖活跃，而一个地点的复合压力源导致了当地种群的崩溃。我们的研究结果强调了隐螯蟹与其珊瑚宿主之间关系的复杂动态，其中高繁殖率可能抵消宿主特异性和定居要求的成本，从而使它们能够抵御中度干扰。这项研究为隐螯蟹生态学提供了新的见解，揭示了其种群中出乎意料的高时间变异性。观察到的动态表明，瘿蟹可能通过促进珊瑚礁能量转移，将宿主衍生的资源（如珊瑚黏液）转化为更高营养级可利用的形式，并为浮游动物群落补充幼虫，从而发挥类似于隐栖性珊瑚礁鱼类的功能作用。鉴于干扰不断增加，这项研究强调需要将珊瑚礁无脊椎动物纳入珊瑚礁保护策略，以在快速变化的世界中保护生物多样性并维持生态系统功能。
