Plastics are abundant artificial substrates in aquatic systems that host a wide variety of organisms (the plastisphere), including potential pathogens and invasive species. Plastisphere communities have many complex, but not well-understood ecological interactions. It is pivotal to investigate how these communities are influenced by the natural fluctuations in aquatic ecosystems, especially in transitional environments such as estuaries. Further study is needed in subtropical regions in the Southern Hemisphere, where plastic pollution is ever increasing. Here we applied DNA-metabarcoding (16S, 18S and ITS-2) as well Scanning Electron Microscopy (SEM) to assess the diversity of the plastisphere in the Patos Lagoon estuary (PLE), South Brazil. Through a one-year in situ colonization experiment, polyethylene (PE) and polypropylene (PP) plates were placed in shallow waters, and sampled after 30 and 90 days within each season. Over 50 taxa including bacteria, fungi and other eukaryotes were found through DNA analysis. Overall, the polymer type did not influence the plastisphere community composition. However, seasonality significantly affected community composition for bacteria, fungi and general eukaryotes. Among the microbiota, we found Acinetobacter sp., Bacillus sp., and Wallemia mellicola that are putative pathogens of aquatic organisms, such as algae, shrimp and fish, including commercial species. In addition, we identified organisms within genera that can potentially degrade hydrocarbons (e.g. Pseudomonas and Cladosporium spp). This study is the first to assess the full diversity and variation of the plastisphere on different polymers within a subtropical Southern Hemisphere estuary, significantly expanding knowledge on plastic pollution and the plastisphere in estuarine regions.

塑料是水生系统中丰富的人造基质，含有多种生物体（塑料圈），包括潜在的病原体和入侵物种。塑料圈群落具有许多复杂但尚未充分理解的生态相互作用。研究这些群落如何受到水生生态系统自然波动的影响至关重要，特别是在河口等过渡环境中。塑料污染日益严重的南半球亚热带地区需要进一步研究。在这里，我们应用 DNA 元条形码（16S、18S 和 ITS-2）以及扫描电子显微镜 (SEM) 来评估帕托斯塑料球的多样性泻湖河口 (PLE)，巴西南部。通过为期一年的原位定植实验，将聚乙烯（PE）和聚丙烯（PP）板放置在浅水区，并在每个季节的30天和90天后取样。通过DNA分析发现了超过50个类群，包括细菌、真菌和其他真核生物。总体而言，聚合物类型不影响塑料球群落组成。然而，季节性显着影响细菌、真菌和一般真核生物的群落组成。在微生物群中，我们发现了不动杆菌属、芽孢杆菌属和壁球菌它们是水生生物（例如藻类、虾和鱼，包括商业物种）的推定病原体。此外，我们还确定了属内可能降解碳氢化合物的生物体（例如假单胞菌属和枝孢属属）。这项研究首次评估了南半球亚热带河口内不同聚合物上塑料圈的全部多样性和变化，显着扩展了对河口地区塑料污染和塑料圈的了解。