Collaborative Research: The Role of Regenerated Nitrogen for Rocky Shore Productivity

在众多的生态系统中，一个基本而持久的问题是新的与再生的营养物质支持生态系统生产力的程度。在沿海海洋系统中，来自上升流的硝酸盐（=新氮）和沿海沃茨和沉积物中的铵再生（=再生氮）是促进沿海海洋生产力的主要氮源。由于无机氮的可用性在许多地区都能明显调节生产，因此了解氮的供应至关重要。在远离河口的开阔海岸地区，硝酸盐输入是由大规模的物理过程决定的，这些物理过程促进了深层营养丰富的水的上涌，包括风向和强度。相反，再生氮（主要是铵）通常是当地动物和微生物过程的结果。沿着沿着的海洋岩石海岸，上升流通常被用作生产力的代理，我们知道很少的动态再生营养物质及其潜在的贡献，在更大的规模生产力;只有上升流通常被用作生产力的代理。丰富的加州贻贝，贻贝，与水营养，藻类生产力，稳定同位素的签名，和微生物遗传学的协会表明这些动物潜在的强大的再生氮，并建议附属于这些动物的硝化微生物的重要的次要作用。在这个项目中，研究人员将通过在贻贝丰度梯度上的普查和实验来量化岩石海岸上再生氮的相对贡献。他们将使用铵、亚硝酸盐和硝酸盐的稳定氮和氧同位素来解开不同生物过程与上升流对岩石海岸地区氮供应和吸收的贡献。这包括天然丰度和示踪剂添加研究。更广泛的影响。再生氮的供应，而不是新的氮通过上升流，是一个当地的过程依赖于一个完整的动物群落。然而，贻贝和其他近岸动物可能特别容易受到不断变化的热环境、有毒藻类大量繁殖和海洋酸化的影响。考虑到近年来沿海氮循环的巨大变化，以及全球气候变化预示的洋流、上升流、海洋化学和厄尔尼诺频率的潜在变化，我们需要了解局部与较大规模海洋事件对氮循环的相对影响。拟议的工作将就地生物相互作用与其对沿海生产力的影响联系起来。除了预期在高质量期刊上发表文章外，教育活动将继续侧重于研究生和本科生教育和指导。该提案将每年资助两名研究生和两名本科生。PI将与政府（奥林匹克海洋国家保护区）和部落（Makah部落）代表密切合作，以传达这项研究。我们还将与麦加博物馆董事会和麦加高等教育委员会合作，确定麦加学生为研究助理。所有三个PI的教学广泛跨越各自的校园，指导几乎每一种类型的本科专业。

A fundamental and persistent question in a multitude of ecosystems is the extent to which new versus regenerated nutrients support ecosystem productivity. In coastal marine systems, nitrate derived from upwelling (= new nitrogen) and ammonium regeneration in coastal waters and sediments (= regenerated nitrogen) are major nitrogen sources that fuel coastal ocean productivity. Because inorganic nitrogen availability clearly regulates production in a large number of areas, understanding nitrogen supply is essential. In open coast regions away from river mouths, nitrate inputs are determined by large-scale physical processes promoting upwelling of deep, nutrient-rich water including wind direction and intensity. In contrast, regenerated nitrogen (mainly ammonium) is generally the result of local animal and microbial processes. Along marine rocky shores, where upwelling is typically used as a proxy for productivity, we know very little about the dynamics of regenerated nutrients and their potential contribution to productivity at larger scales; only upwelling is typically used as a proxy for productivity. Associations of the abundant California mussel, Mytilus californianus, with water nutrients, algal productivity, stable isotope signatures, and microbial genetics indicate potentially strong regeneration of nitrogen by these animals and suggest an important secondary role of nitrifying microbes affiliated with these animals. In this project, the investigators will quantify the relative contribution of regenerated nitrogen on rocky shores through censuses and experiments across a gradient of mussel abundance. They will use stable nitrogen and oxygen isotopes of ammonium, nitrite, and nitrate to disentangle the contribution of different biological processes versus upwelling to the nitrogen supply and uptake of rocky shore regions. This includes both natural abundance and tracer addition studies. Broader Impacts. Regenerated nitrogen supply, as opposed to new nitrogen via upwelling, is a local process dependent upon an intact animal community. However, mussels and other nearshore animals may be particularly vulnerable to a changing thermal environment, toxic algal blooms, and ocean acidification. Given the dramatic changes to the coastal nitrogen cycle in recent years, and potential changes to currents, upwelling, ocean chemistry, and El Niño frequencies portended by global changes to our climate, we to know the relative effect of local versus larger scale oceanic events on the nitrogen cycle. The proposed work links biological interactions in situ with its implications for coastal productivity. In addition to expected publications in high quality journals, educational activities will continue to focus on graduate and undergraduate education and mentoring. The proposal will fund two graduate students and two undergraduates per year. The PI's will work closely with government (Olympic Marine National Sanctuary) and tribal (Makah Tribe) representatives to communicate this research. We will also work with Makah Museum Board of Trustees and the Makah Higher Education Committee to identify Makah students as research assistants. All three PI's teach broadly across their respective campuses, instructing almost every type of undergraduate major.