Carbon cycling and food web energy transfer in salinized headwater streams

由于与农业、道路除冰、废水排放和采矿有关的活动，全球淡水生态系统正在变得盐碱化(或“盐碱化”)。在阿巴拉契亚中部，源头河流生态系统特别容易受到地面煤炭开采造成的盐碱化的影响，这是该地区一种广泛的经济活动。盐浓度的增加会给水生生物带来压力，并可能使一些微生物和动物的水源无法生存。这令人担忧，因为阿巴拉契亚源头是一些独特生物的家园，总体上拥有世界上一些最多样化的水生昆虫群落。溪流昆虫特别适合循环营养物质，并将食物能量从周围的森林分配到水生食物网中。迫切需要了解盐碱化如何影响淡水昆虫群落、河流生产力和食物网能量转移。盐碱化对源头溪流中淡水动物的影响将与当地的K-12教师和学员、科学家和地区政策制定者分享。还将开发和分享用于溪流生物评估的新指标。这项研究将通过测量食物网碳的产生和转移来评估盐度对水源中碳(C)处理的影响。暴露于采矿的矿物的风化增强可提高水源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有据可查的影响。这种有机应激反应可能会对溪流食物网以及分解和初级生产等生态系统过程产生连锁效应。盐碱化预计将缓解初级生产者的盐分限制，增加初级总产量(GPP)。相反，在异养生产中，补贴-压力反应是可以预测的。因此，随着盐度梯度的增加，营养转移效率上类似的补贴-胁迫反应最终可能会减少最高盐度下的食物网碳转移。为了验证这些假设，将在代表盐度梯度的九个研究流中同时测量C池、转移和转化。这一奖项反映了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。

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.