Postdoctoral Fellowship: OCE-PRF: Do dead shells make good homes? Assessing the Development, Stability, and Evolution of Shell Gravel Habitats Across Space and Time

该项目的目的是评估底栖无脊椎动物群落和贝壳砾石生境沿纬度梯度的共同进化。底栖生物群落直接将它们的物理栖息地修改为骨骼碎片(贝壳、骨头、岩屑等)。经过许多世代的死亡有机体在沉积物中积累，形成一片片粗糙的底物，表生生物可以在其上定居。尽管贝壳砾石栖息地在现代大陆架上很少见，但它们是生物多样性的热点，也可能是普遍存在的软沉积动物群(6500万年前)出现之前早期化石组合的最佳现代类比。此外，尽管已经对全球纬度梯度的进化起源和生态后果进行了严格的评估，以解释现代和深层生物多样性，但我们仍然对决定化石组合的生产、持久性和保存的过程中的纬度变化知之甚少。PI将收集和评估北美东太平洋沿岸两个著名的贝壳砾石环境--南加州暖温带海峡群岛和华盛顿州冷温带圣胡安群岛--不同底质条件(砾石与泥浆、浅与深)的沉积物样本，形成一个纬度梯度，通过该纬度将量化底栖群落、沉积物基质及其当地反馈效应。PI将通过与生物监测机构合作，为当地学校创建教案，为加州大学古生物学博物馆做志愿者，以及指导本科生进行研究，进一步增加旧金山湾区的科学参与。在本项目期间，将进行三个总体调查：(1)关于沉积速率、水温和生物扰动强度的死壳组合的发展、持续和时间尺度，(2)死壳组合和活的底栖生物群落之间的保真度，及其与死壳持续的关系，以及(3)将这些生态和地膜动力学联系起来的反馈效应。第一项调查将使用通过放射性碳测年确定的尸检年龄来量化平均时间的持续时间，并确定每个田野区域内和之间的贝壳损失参数(解体、封存和掩埋)。第二项调查将评估样本群落和死壳组合之间的单变量生态指标和多变量组成的相关性。第三项调查将结合这些物理和生物学结果，对它们的相互作用进行建模，并确定作用于这些栖息地的触角反馈。这项研究将通过确定底栖动物栖息地塑造无脊椎动物群落演替的机制，并通过这些机制来弥合物理海洋学和生物海洋学之间的重要差距。这些见解将改善(1)化石记录的古生态解释和(2)在不断变化的海洋条件下管理沿海生物多样性的保护战略。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The aim of this project is to assess the coevolution of benthic invertebrate communities and shell gravel habitats along a latitudinal gradient. Benthic communities directly modify their physical habitat as the skeletal debris (shells, bones, sclerites, etc.) of dead organisms over many generations accumulate in the sediment, creating patches of coarse substrates upon which epibenthic (surface-living) organisms can colonize. Despite being rare on modern continental shelfs, shell gravel habitats are hotspots for biodiversity and perhaps the best modern analogs of early fossil assemblages from before the onset of pervasive soft-sediment infaunal communities ( 65 million years ago). Further, while the evolutionary origins and ecological consequences of the global latitudinal gradient have been rigorously assessed to explain both modern and deep-time biodiversity, we still know little about latitudinal variation in the processes that determine the production, persistence, and preservation of fossil assemblages. The PI will collect and assess sediment samples from various substrate conditions (gravel vs mud, shallow vs deep) from two notable shell gravel environments along the Eastern Pacific coast of North America: The warm-temperate Channel Islands of Southern California and the cold-temperate San Juan Islands of Washington, forming a latitudinal gradient across which benthic communities, sediment substrates, and their local feedback effects will be quantified. The PI will further increase scientific engagement in the San Francisco Bay area by collaborating with biomonitoring agencies, creating lesson plans for local schools, volunteering with the University of California Museum of Paleontology, and mentoring undergraduates in research. Three overarching investigations will be conducted during this project: (1) the development, persistence, and temporal scale of dead-shell assemblages with respect to sedimentation rates, water temperature, and bioturbation intensity, (2) the fidelity between dead-shell assemblages and living benthic communities, and its relationship with dead-shell persistence, and (3) feedback effects that link these ecological and taphonomic dynamics. The first investigation will use postmortem ages determined via radiocarbon dating to quantify the duration of time averaging and determine shell loss parameters (disintegration, sequestration, and burial) within and between each field area. The second investigation will assess correlations in both univariate ecological metrics and multivariate composition among sampled communities and dead-shell assemblages. The third investigation will combine these physical and biological results to model their interactions and identify taphonomic feedbacks that act on these habitats. This research will bridge important gaps between physical and biological oceanography by identifying mechanisms by which benthic habitats shape – and are themselves shaped by – the succession of invertebrate communities. These insights will improve both (1) paleoecological interpretations from the fossil record and (2) conservation strategies for managing coastal biodiversity in a world of changing ocean conditions.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.