Cloutier Danielle D, Alm Elizabeth W, McLellan Sandra L
School of Freshwater Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA.
Department of Biology and Institute for Great Lakes Research, Central Michigan University, Mount Pleasant, Michigan, USA.
Appl Environ Microbiol. 2015 Aug;81(15):4904-13. doi: 10.1128/AEM.00233-15. Epub 2015 May 15.
Microbial communities within beach sand play a key role in nutrient cycling and are important to the nearshore ecosystem function. Escherichia coli and enterococci, two common indicators of fecal pollution, have been shown to persist in the beach sand, but little is known about how microbial community assemblages are related to these fecal indicator bacteria (FIB) reservoirs. We examined eight beaches across a geographic gradient and range of land use types and characterized the indigenous community structure in the water and the backshore, berm, and submerged sands. FIB were found at similar levels in sand at beaches adjacent to urban, forested, and agricultural land and in both the berm and backshore. However, there were striking differences in the berm and backshore microbial communities, even within the same beach, reflecting the very different environmental conditions in these beach zones in which FIB can survive. In contrast, the microbial communities in a particular beach zone were similar among beaches, including at beaches on opposite shores of Lake Michigan. The differences in the microbial communities that did exist within a beach zone correlated to nutrient levels, which varied among geographic locations. Total organic carbon and total phosphorus were higher in Wisconsin beach sand than in beach sand from Michigan. Within predominate genera, fine-scale sequence differences could be found that distinguished the populations from the two states, suggesting a biogeographic effect. This work demonstrates that microbial communities are reflective of environmental conditions at freshwater beaches and are able to provide useful information regarding long-term anthropogenic stress.
海滩沙子中的微生物群落对养分循环起着关键作用，对近岸生态系统功能至关重要。大肠杆菌和肠球菌是粪便污染的两种常见指标，已被证明能在海滩沙子中持续存在，但对于微生物群落组合如何与这些粪便指示菌（FIB）库相关联，人们了解甚少。我们考察了跨越地理梯度和多种土地利用类型的八个海滩，并对水体、后滨、护堤和水下沙子中的原生群落结构进行了表征。在毗邻城市、森林和农业用地的海滩的沙子中，以及在护堤和后滨中，FIB的含量水平相似。然而，即使在同一海滩内，护堤和后滨的微生物群落也存在显著差异，这反映了FIB能够生存的这些海滩区域截然不同的环境条件。相比之下，特定海滩区域的微生物群落在不同海滩之间是相似的，包括密歇根湖两岸的海滩。海滩区域内确实存在的微生物群落差异与养分水平相关，而养分水平在不同地理位置有所不同。威斯康星州海滩沙子中的总有机碳和总磷含量高于密歇根州海滩沙子中的含量。在优势属内，可以发现能区分两个州种群的细微序列差异，这表明存在生物地理效应。这项研究表明，微生物群落反映了淡水海滩的环境状况，并能够提供有关长期人为压力的有用信息。
