Sequencing the meiofaunal metagenome of the marine/freshwater interface in key estuarine ecosystems

河口是重要的过渡性栖息地，受到当地和全球人类活动的显著影响（即它们是居住，工业化，污染和娱乐的主要中心）。河口通常被认为是生物多样性低的系统;这可能是由于大型底栖动物的阿尔法多样性低。相比之下，小型动物（小于45微米的动物，以线虫为主）的多样性是相当大的，大多数河口估计居住着大约200种线虫，数量从惊人的106-108动物/平方米不等，占后生动物动物区系物种丰富度（现有物种总数）的50-90%。小型底栖生物多样性在沉积物生态系统过程中起着非常重要的作用，有助于调节碳、氮和硫的循环、水柱过程、污染物分布、次级生产、食物链过程以及沉积物的稳定性。小型底栖动物显然是生态系统功能的关键组成部分，但使用标准形态学方法研究小型底栖动物群落需要高技能的分类学家，并且非常耗时。这不仅限制了生态研究中有意义的样本量的分析，而且不同种类小型底栖生物的小尺寸和形态相似性导致了对形态分类方法可靠性的严重怀疑。由于这些限制因素，目前正在为线虫生物多样性评估开发形态学方法和新的分子遗传学方法的组合。也许这一领域最令人兴奋的发展是应用大规模并行测序（MPS）来阐明微生物或小型底栖动物样品的分子群落组成的潜力。这项全新的技术能够同时对数十万条短链DNA进行测序（在4小时内），这些短链DNA可用作物种识别标签。到目前为止，使用标准的克隆和测序方法这是不可能的，MPS也代表了令人难以置信的金钱价值，这种类型的应用中的每个序列的成本不到5便士。MPS技术的可用性，除了最近在线虫类群的系统发育和生态关系的知识的重大进展，现在提供了一个分子和生物信息学的框架，可以用来准确地在真实的时间小型底栖动物的生物多样性。这些进展使人们能够提出和检验各种假设，以阐明小型底栖生物多样性与生物/非生物过程之间的关系。此外，这些方法将有助于开发水动力学模型，可用于根据流速和沉积物组成之间的关系预测小型底栖动物群落的空间和时间组成。目前的建议旨在创造新的生物多样性基因组序列资源，生态上重要的河口物种在河口生态系统的特点是正在进行的（默西）和恢复（泰晤士河）工业和市政污染物制度的基质类型的范围。这些数据将用于解决以生物和非生物为重点的生态假设，并将产生预测的c。320，000个新的序列读段，有效地表征了英国河口小型底栖动物的重要组成部分，从而为了解海洋沉积物中的生态系统功能提供了平台。然后，这些数据可以与从桑迪沉积物中获得的补充数据集相结合，用于开发具有成本效益、节省时间的基于DNA芯片的小型底栖动物群落识别工具（例如用于生物监测和生态毒理学研究），从而推动对海洋沉积物中生物多样性生态系统功能的研究（学术和商业）。

Estuaries are key transitional habitats that are significantly affected by local and global human activities (ie they are main centres of habitation, industrialization, pollution and recreation). Estuaries are typically considered to be low biodiversity systems; probably due to the presence of low alpha diversity of macrofauna. In contrast, meiofaunal diversity (animals smaller than 45um, dominated by nematodes) is substantial, with most estuaries estimated to be inhabited by approximately 200 species of nematodes, with numbers ranging from a staggering 106-108 animals/m2, contributing to between 50-90% of the metazoan faunal species richness (the total numbers of species present). Meiofaunal biodiversity plays a very important role in sediment ecosystem processes, contributing to the regulation of carbon, nitrogen, and sulphur cycling, water column processes, pollutant distribution, secondary production, food chain processes, and stability of sediments. Meiofauna are clearly key components of ecosystem functioning, but studying meiofaunal communities using standard morphological approaches requires highly-skilled taxonomists and is incredibly time consuming. Not only does this restrict the analysis of meaningful sample sizes in ecological studies, but the small size and morphological similarities of different species of meiofaunal organisms have led to severe doubts regarding the reliability of morphological taxonomic approaches. As a result of these constraints, combinations of morphological approaches and new molecular genetic methods are being developed for nematode biodiversity assessments. Perhaps the most exciting development in this field is the potential to apply massively parallel sequencing (MPS), to elucidate the molecular community composition of microbial, or meiofaunal samples. This brand new technology has the ability to simultaneously sequence hundreds of thousands of short strands of DNA (in four hours), that can be used as species identification tags. To date, this has never been possible using standard cloning and sequencing methods and MPS also represents incredible value for money, with each sequence in this type of application costing less than 5p. The availability of MPS technology, in addition to recent significant advances in the knowledge of the phylogenetic and ecological relationships of nematode taxa, now offers a molecular and bioinformatic framework that can be used to accurately characterise meiofaunal biodiversity in real time. Such advances allow hypotheses to be developed and tested to elucidate relationships between meiofaunal biodiversity and biotic/abiotic processes. Moreover, these methods will facilitate the development of hydrodynamic models that can be used to predict the spatial and temporal composition of meiofaunal communities according to the relationships between flow rates and sediment composition. The current proposal seeks to create novel biodiversity genome sequence resources for ecologically important estuarine species throughout a range of substrate types in estuarine ecosystems characterized by ongoing (Mersey) and recovering (Thames) industrial and municipal pollutant regimes. The data will be used to address biotic- and abiotic-focused ecological hypotheses, and will generate a predicted c. 320,000 novel sequence reads, effectively characterizing a significant component of the UK's estuarine meiofauna, thus providing a platform for understanding ecosystem functioning in marine sediments. These data can then be combined with complimentary datasets derived from sandy sediments and be used to develop cost-effective, time-saving, DNA chip-based meiofaunal community identification tools (e.g. for biomonitoring and ecotoxicology studies), thus, driving forward research (academic and commercial) into biodiversity-ecosystem functioning in marine sediments.