Developing novel molecular tools for characterising food web responses to climate change

该项目的目的是量化全球变暖对淡水生态系统食物网结构的影响。我将研究这些联系的强度，以及几个不同食物网在温度梯度上的能量流动方向。为了解决这些关键的生态学问题，我将测试新的分子技术，如下一代测序(NGS)，它将被用于匹配更传统的食物网方法。特别是，通过对物种的部分遗传密码进行测序，并将其与数据库进行比较，而无需参考它们的形态特征，就可以识别物种。这种技术的使用为我们提供了极其有价值的信息，事实上：我们可以检测到形态相同但具有不同遗传特征的隐蔽物种(I)的存在，还可以识别在这种阶段无法区分的早期幼虫(II)，但它在受损标本方面也是有用的(III)。此外，我将利用锡尔伍德公园的新中温带设施来预测变暖对淡水生态系统稳定性和结构的影响，特别是我们的目标是将中温带加热4摄氏度和7摄氏度，这是我们预计在下个世纪在我们的纬度和高纬度地区分别遇到的热度。这一原理与英国多塞特的一项长期中附体研究所采用的原理相同，在该研究中，我们已经有了关于中上层和底栖生物食物网的群落组成和大小光谱的异常详细的数据，但处理的可复制性更高(锡尔伍德公园有96个中附体)。该项目还将在北半球火环沿线的五个不同地热地点进行一致的实地考察；这些地区包括：冰岛、格陵兰、阿拉斯加、堪察加和斯瓦尔巴群岛。由于全球变暖加剧，这些北极哨兵系统将成为向极地迁徙的物种的避难所。此外，研究这些系统将特别有趣，因为高纬度地区的表面温度预计在下一个世纪将上升到7.5摄氏度(政府间气候变化专门委员会，2014年)。了解这些食物网的结构和动态将是解决未来将出现在我们纬度的问题的根本。这种地热系统的美妙之处在于，它们几乎充当了户外实验室，事实上，溪流的化学成分相似，只是水温不同。冰岛遗址(Hengill)已经被研究了几年，我们现在有了它的食物网的详细描述。这将使我们能够将NGS技术应用到一个描述良好的食物网络中，在那里我们希望与从传统食物网络分析中收集的数据相匹配，特别是在物种丰富度和丰度方面。除此之外，我将尝试描述一些在食物网分析中还知之甚少的联系，例如某些群体(例如吸食性捕食者)的饮食，它们代表了食物网中缺失的一个环节。为了探索这些缺失的环节，我将应用NGS技术来分析从肠道内容物分析中看不到的捕食者的饮食，这将使我们能够在食物网络结构方面添加有价值的信息。冰岛的地点将作为一个平台，我们将在那里测试方法，并进行实验，然后将这些试验应用于所有其他地热地点。保持这些方法的一致性将是至关重要的，以便调查和理清不同地点将出现的差异和潜在的共性。特别是，我们预计气候变暖将在物种差异很大的生态系统中产生类似的模式。最后，我将研究自然系统和中层生态系统之间的共性，因为以前的研究已经支持了冰岛河流和英国中层生态系统之间与生态系统呼吸相关的一致的热响应。

The aim of this project is to quantify the effects of global warming on food web structure of freshwater ecosystems. I will be studying the strength of the links, and the direction of energy flows of several different food webs across a temperature gradient. To address these key ecological questions I will test novel molecular techniques such as next generation sequencing (NGS) which will be used to match more traditional food web approaches. In particular, it is possible to identify species by sequencing part of their genetic code, and comparing it to a database without referring to their morphological traits. The use of such techniques gives us extremely valuable information, in fact: we can detect the presence of cryptic species (I) which are morphologically identical, but have distinct genetic traits, also, identify early instar larvae (II) which are impossible to distinguish at such stage, but it can be useful also in terms of damaged specimens (III). Moreover, I will take advantage of new mesocosm facilities at Silwood park in order to predict the effects of warming on the stability and structure of freshwater ecosystems, in particular we are aiming to heat mesocosms by 4C and 7C which is the degree of heat that we expect to encounter at our latitudes, and high latitudes, respectively, in the following century. The principle is the same adopted in a long-term mesocosm study in Dorset (UK) where we already have an exceptionally detailed data of the community composition and size-spectra of both the pelagic and benthic food webs, but with a higher replicability (96 mesocosms in Silwood park) of treatments. This project will also have a consistent fieldwork component which will take place in five different geothermal sites along the ring of fire in the Northern hemisphere; these will include: Iceland, Greenland, Alaska, Kamchatka, and Svalbard. These arctic sentinel systems will act as a refuge for species migrating polewards due to increase global warming. Moreover, it will be particularly interesting to study these systems as high latitudes surface temperatures are predicted to increase up to 7.5C in the following century (IPCC, 2014). Understanding structure and dynamics of these food webs will be fundamental to address future issues which will appear at our latitudes. The beauty of such geothermal systems is that they almost act as outdoor laboratories, in fact, streams have similar chemical composition, and only differ by water temperature. The Icelandic site (Hengill) has been studied for several years, and we now have a detailed description of its food web. This will allow us to apply NGS techniques into a well described food web, where we expect to match data collected from traditional food web analysis, particularly in terms of species richness and abundances. In addition to this, I will try to describe some of the links yet poorly understood in food web analysis, such as the diet of some groups (e.g. suctorial predators) which represent a missing link within the food web. In order to explore these "missing links", I will apply NGS techniques to analyse the diet of predators not visible from gut content analysis, this will allow us to add valuable information in terms of food web structure. The Icelandic site will act as a platform where we will be testing methods, and experiments which will be then applied to all the other geothermal sites. Keeping these methods consistent will be crucial, in order to investigate and disentangle differences and potential generalities which will emerge across the different sites. In particular, we expect warming to produce similar patterns in ecosystems with a wide difference of species. Finally, I will investigate generalities between natural systems and mesocosms, as previous studies already support a consistent thermal response in relation to ecosystem respiration between the Icelandic streams and the UK mesocosms.