Carbon cycling and food web energy transfer in salinized headwater streams

地球仪的淡水生态系统正因农业、道路除冰、废水排放和采矿等活动而盐碱化（或“咸化”）。在阿巴拉契亚中部，源头河流生态系统特别容易受到地表采煤造成的盐碱化的影响，而地表采煤是该地区广泛的经济活动。盐浓度的增加会对水生生物造成压力，并可能使一些微生物和动物无法在水源中生存。这是令人担忧的，因为阿巴拉契亚的源头是一些独特的生物的家园，总的来说，有一些世界上最多样化的水生昆虫群落。溪流昆虫特别适合循环养分，并将周围森林的食物能量分配到水生食物网中。有迫切需要了解盐碱化如何影响淡水昆虫群落，流生产力和食物网能量转移。盐碱化对淡水动物的影响将与当地K-12教师和学员，科学家和区域政策制定者分享。还将制定和分享溪流生物评估的新指标。 这项研究将通过测量食物网C的生产和转移来评估盐度对源头河流中碳（C）处理的影响。采矿暴露的矿物的风化作用增强，可以提高源头河流中的主要离子和盐度，并对微生物和大型无脊椎动物的生长和群落组成产生影响。这种生物应激反应可能对河流食物网和生态系统过程（如分解和初级生产）产生级联效应。预计盐渍化将减轻初级生产者的盐限制，增加初级生产总值（GPP）。相反，在异养生产中，预测沉降应力响应。因此，沿着一个不断增加的盐度梯度，类似的沉降应力反应的营养转移效率，最终降低食物网C转移在最高盐度。为了检验这些假设，同时测量碳池，转移和转换将采取在九个研究流，代表一个盐度gradient.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Freshwater ecosystems are becoming salinized (or “salty”) across the globe from activities associated with agriculture, road de-icing, wastewater discharge, and mining. In central Appalachia, headwater stream ecosystems are particularly vulnerable to the impacts of salinization from surface coal mining, a widespread economic activity in the region. Increased salt concentrations stress aquatic organisms and can make headwaters unlivable for some microbes and animals. This is concerning because Appalachian headwaters are home to some unique organisms and collectively, have some of the most diverse aquatic insect communities in the world. Stream insects are especially adapted to cycling nutrients and distributing food energy from the surrounding forests into aquatic food webs. There is an urgent need to understand how salinization affects the freshwater insect community, stream productivity, and food web energy transfer. The consequences of salinization on freshwater animals in headwater streams will be shared with local K-12 teachers and trainees, scientists, and regional policy makers. New metrics for stream bioassessments will also be developed and shared. This research will assess salinity effects on carbon (C) processing in headwater streams through measurements of food web C production and transfer. Enhanced weathering of mining-exposed minerals can elevate major ions and salinity in headwater streams, with documented impacts to microbial and macroinvertebrate growth and community composition. Such organismal stress responses likely have cascading effects on stream food webs and ecosystem processes like decomposition and primary production. Salinization is predicted to alleviate salt limitation in primary producers and increase gross primary production (GPP). In contrast, subsidy-stress responses are predicted in heterotrophic production. Thus, along an increasing salinity gradient, similar subsidy-stress responses in trophic transfer efficiency could ultimately decrease food web C transfer at the highest salinities. To test these hypotheses, simultaneous measurements of C pools, transfers, and transformations will be taken in nine study streams that represent a salinity gradient.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.