Hoellein Timothy, Rojas Miguel, Pink Adam, Gasior Joseph, Kelly John
Department of Biology, Loyola University Chicago, Chicago, Illinois, United States of America.
PLoS One. 2014 Jun 23;9(6):e98485. doi: 10.1371/journal.pone.0098485. eCollection 2014.
Accumulation of anthropogenic litter (i.e. garbage; AL) and its ecosystem effects in marine environments are well documented. Rivers receive AL from terrestrial habitats and represent a major source of AL to marine environments, but AL is rarely studied within freshwater ecosystems. Our objectives were to 1) quantify AL density in urban freshwaters, 2) compare AL abundance among freshwater, terrestrial, and marine ecosystems, and 3) characterize the activity and composition of AL biofilms in freshwater habitats. We quantified AL from the Chicago River and Chicago's Lake Michigan shoreline, and found that AL abundance in Chicago freshwater ecosystems was comparable to previously reported data for marine and terrestrial ecosystems, although AL density and composition differed among habitats. To assess microbial interactions with AL, we incubated AL and natural substrates in 3 freshwater ecosystems, quantified biofilm metabolism as gross primary production (GPP) and community respiration (CR), and characterized biofilm bacterial community composition via high-throughput sequencing of 16S rRNA genes. The main driver of biofilm community composition was incubation location (e.g., river vs pond), but there were some significant differences in biofilm composition and metabolism among substrates. For example, biofilms on organic substrates (cardboard and leaves) had lower GPP than hard substrates (glass, plastic, aluminum and tiles). In addition, bacterial communities on organic substrates were distinct in composition from those on hard substrates, with higher relative abundances of bacteria associated with cellulose decomposition. Finally, we used our results to develop a conceptual diagram designed to unite the study of AL in terrestrial and freshwater environments with the well-established field of marine debris research. We suggest this broad perspective will be useful for future studies which synthesize AL sources, ecosystem effects, and fate across multiple ecosystem types, and will benefit management and reduction of global AL accumulations.
人为垃圾（即垃圾；AL）在海洋环境中的积累及其对生态系统的影响已有充分记录。河流从陆地栖息地接收AL，是海洋环境中AL的主要来源，但在淡水生态系统中对AL的研究很少。我们的目标是：1）量化城市淡水中的AL密度；2）比较淡水、陆地和海洋生态系统中AL的丰度；3）描述淡水栖息地中AL生物膜的活性和组成。我们对芝加哥河和芝加哥密歇根湖海岸线的AL进行了量化，发现芝加哥淡水生态系统中AL的丰度与先前报道的海洋和陆地生态系统的数据相当，尽管不同栖息地的AL密度和组成有所不同。为了评估微生物与AL的相互作用，我们在3个淡水生态系统中培养了AL和天然底物，将生物膜代谢量化为总初级生产力（GPP）和群落呼吸（CR），并通过16S rRNA基因的高通量测序来描述生物膜细菌群落组成。生物膜群落组成的主要驱动因素是培养地点（如河流与池塘），但不同底物之间的生物膜组成和代谢存在一些显著差异。例如，有机底物（纸板和树叶）上的生物膜GPP低于硬底物（玻璃、塑料、铝和瓷砖）。此外，有机底物上的细菌群落组成与硬底物上的不同，与纤维素分解相关的细菌相对丰度更高。最后，我们利用研究结果绘制了一个概念图，旨在将陆地和淡水环境中AL的研究与成熟的海洋垃圾研究领域结合起来。我们认为，这种广阔的视角将有助于未来综合多种生态系统类型的AL来源、生态系统影响和归宿的研究，并将有利于全球AL积累的管理和减少。
