Indicators of Air Pollution-derived Stress in Birds

项目要点：这是第一个在鸟类体内比较颗粒物暴露对皮质酮水平影响的项目。这项研究将评估已识别的空气污染物与作为健康指标的禽类肠道微生物群之间的关系。这是一个多学科的项目，利用广泛的实地工作和实验室技术来调查鸟类污染压力的不同生物指标。概述：人类活动的增加(图1)导致空气污染的大幅增加1。其中一些物质，即使处于亚致死水平，也可能对非人类和人类2产生不利的健康影响。因此，重要的是找到可重复使用的方法来监测环境中的污染物水平。鸟类是极好的生物指示器，因为它们无处不在，而且相对容易从4收集观测数据。我们将测试这一假设，即鸟类通过其皮质酮水平和肠道微生物群的变化来对空气污染做出反应。这也将使我们能够开发基于特征的生物指标。我们将空气污染引起的压力称为降低个体达尔文适合度的暴露`5。我们不会在受控的实验室环境中进行这项研究，而是将在现场监测野生大山雀来研究暴露在空气污染中的情况。为了获得当地污染水平的准确指示，将从普利收集羽毛(即尚未离开鸟巢的环状幼鸟)。从普利采集的血液和粪便样本也将有助于确定空气污染的局部影响。利用单粒子电感耦合等离子体质谱(SPICPMS)研究城乡梯度上大山雀个体羽毛化学中金属污染物的空间变异。我们将使用SPICPMS和共聚焦显微镜将化合物分离为颗粒和溶解的形式。为监测空气污染而进行的有限鸟类研究往往局限于重金属元素，重点是海鸟7。就我们所知，还没有研究试图将颗粒物暴露与原位皮质酮水平联系起来。这项研究的另一个新元素是使用鸟类肠道微生物群作为压力的指示器。最终，这项工作可以在生物指标中识别新的空气污染压力指标，这些指标广泛分布并在城市中广泛传播。它还将加强羽毛作为纸巾的使用，这种纸巾可以非侵入性地采样来测量城市的空气污染。这两个结果对鸟类保护和人类健康都有积极的影响。大山雀巢将沿着城市到农村的坡度安装，使用绿色覆盖率来定义坡度。鸟巢将放置在现有的大学和议会空气质量监测站附近，因为这些监测站将提供基线NOx和颗粒物读数。我们将把每一只雏鸟放在鸟巢盒子里，并取样一根轮廓羽毛。羽毛上的污染物将用SPICPMS进行分析。共聚焦显微镜和SPICPMS将使我们能够区分颗粒物质和溶解物质9。每窝采血3只，用放射免疫法测定皮质酮。将在处理后3分钟内采集基线样本，然后在30分钟后获取压力诱导样本10。鸟儿将被捕获并放入袋子中收集粪便样本。我们将从粪便样本中提取DNA，并使用16S核糖体rRNA测序来鉴定和比较细菌组合11。

Project Highlights: This is the first project to compare the effects of particulate matter exposure on corticosterone levels in birds in situ. This study will assess the relationship between identified air pollutants and avian gut microbiome as an indicator of health. This is a multidisciplinary project using a wide variety of fieldwork and laboratory techniques to investigate different bioindicators of pollution-derived stress in birds.Overview: Increased anthropogenic activity (Fig. 1) has led to a large increase in air pollutants1. Some of these substances, even at sub-lethal levels, can have adverse health effects on non-humans, as well as humans2. It is therefore important to find repeatable methods for monitoring pollutant levels in the environment3. Birds are excellent bioindicators as they are ubiquitous and relatively easy to collect observational data from4. We will test the hypothesis that birds respond to air pollution through changes in their corticosterone levels and gut microbiome. This will allow us to develop trait-based bioindicators too. We refer to air pollution-derived stress as exposure that reduces the Darwinian fitness of an individual`5. Rather than conducting this research in a controlled laboratory environment, we will monitor wild great tits (Parus major) in situ to study exposure to air pollution in situ. In order to obtain a precise indication of local pollution levels, feathers will be collected from pulli (i.e. ringed young birds that have not left the nest). Blood and faecal samples collected from pulli will also help to identify the localised impacts of air pollution. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) will be used to investigate the spatial variation of metal contaminants in the feather chemistry of great tit individuals on an urban to rural gradient. We will use spICP-MS and confocal microscopy to separate the compounds into particulate and dissolved forms.The limited research on birds that has been conducted to monitor air pollution has often been confined to heavy metal elements, with a focus on seabirds7. To the best of our knowledge, no study has attempted to link particulate exposure with corticosterone levels in situ. Another novel element of this research is the use of the bird gut microbiome as an indicator of stress. Ultimately, this work could identify new indicators of air pollution-derived stress in bioindicators that are widely distributed and move extensively throughout cities. It will also reinforce the use of feathers as a tissue that can be non-invasively sampled to measure air pollution in cities. Both outcomes have positive implications for avian conservation and human health. Great tit nestboxes will be installed along an urban to rural gradient, using percent green cover to define the gradient. Nestboxes will be placed in close proximity to existing university and council air quality monitoring stations, as these will provide baseline NOx and particulates readings. We will ring each chick in nestboxes and sample one contour feather. Feathers will be analysed for pollutants using spICP-MS. Confocal microscopy and spICP-MS will enable us to distinguish between particulate and dissolved substances9. Blood samples will be taken from 3 ringed chicks per brood for corticosterone assessment by radioimmunoassay. A baseline sample will be taken within 3 minutes of handling, followed by a stress-induced sample obtained after 30 minutes10. Birds will be caught and placed inside bags to collect faecal samples. We will extract DNA from the faecal samples, and use 16S ribosomal rRNA sequencing to identify and compare the bacterial assemblages11.