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

本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。底栖生物群落直接改变了它们的物理栖息地，因为经过许多代的死亡生物的骨骼碎片（贝壳、骨头、硬膜等）在沉积物中积累，形成了下层生物（表面生物）可以定居的粗糙底物斑块。尽管在现代大陆架上很少见，但贝壳砾石栖息地是生物多样性的热点，也许是在普遍存在的软沉积物动物群落（6500万年前）出现之前的早期化石组合的最好的现代类似物。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，但我们对决定化石组合产生、持续和保存的过程中的纬度变化知之甚少。PI将从北美东太平洋沿岸两个著名的贝壳砾石环境中收集和评估不同基质条件下的沉积物样本（砾石vs泥浆，浅vs深）：南加州暖温带海峡群岛和华盛顿冷温带圣胡安群岛，形成一个纬度梯度，底栖生物群落，沉积物基质及其局部反馈效应将被量化。PI将通过与生物监测机构合作，为当地学校制定课程计划，与加州大学古生物学博物馆合作，并指导本科生进行研究，进一步增加旧金山湾区的科学参与。本项目将进行三项总体调查：(1)死壳群落的发育、持续和时间尺度与沉积速率、水温和生物扰动强度的关系；(2)死壳群落与底栖生物群落之间的保真度及其与死壳持久性的关系；(3)将这些生态和地学动态联系起来的反馈效应。第一次调查将使用通过放射性碳定年法确定的尸体年龄来量化时间平均的持续时间，并确定每个区域内和区域之间的壳损失参数（解体、固存和掩埋）。第二项调查将评估取样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来模拟它们之间的相互作用，并确定对这些栖息地起作用的地语学反馈。这项研究将通过确定底栖生物栖息地塑造无脊椎动物群落演替的机制，从而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)在海洋条件不断变化的世界中管理沿海生物多样性的保护策略。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。

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.