Trillions of plastic debris fragments are floating at sea, presenting a substantial surface area for microbial colonization. Numerous cultivation-independent surveys have characterized plastic-associated microbial biofilms, however, quantitative studies addressing microbial carbon biomass are lacking. Our confocal laser scanning microscopy data show that early biofilm development on polyethylene, polypropylene, polystyrene, and glass substrates displayed variable cell size, abundance, and carbon biomass, whereas these parameters stabilized in mature biofilms. Unexpectedly, plastic substrates presented lower volume proportions of photosynthetic cells after 8 weeks, compared to glass. Early biofilms displayed the highest proportions of diatoms, which could influence the vertical transport of plastic debris. In total, conservative estimates suggest 2.1 × 10²¹ to 3.4 × 10²¹ cells, corresponding to about 1% of the microbial cells in the ocean surface microlayer (1.5 × 10³ to 1.1 × 10⁴ tons of carbon biomass), inhabit plastic debris globally. As an unnatural addition to sea surface waters, the large quantity of cells and biomass carried by plastic debris has the potential to impact biodiversity, autochthonous ecological functions, and biogeochemical cycles within the ocean.

数以万亿计的塑料碎片漂浮在海上，为微生物定植提供了巨大的表面积。许多独立于培养的调查已经表征了与塑料相关的微生物生物膜，但是，缺乏针对微生物碳生物量的定量研究。我们的共聚焦激光扫描显微镜数据表明，聚乙烯、聚丙烯、聚苯乙烯和玻璃基材上的早期生物膜发育显示出不同的细胞大小、丰度和碳生物量，而这些参数在成熟的生物膜中稳定。出乎意料的是，与玻璃相比，塑料基材在 8 周后呈现出较低的光合细胞体积比例。早期的生物膜显示出最高比例的硅藻，这可能会影响塑料碎片的垂直运输。总的来说，保守估计表明 2。²¹至 3.4 × 10 ²¹细胞，相当于海洋表面微层中约 1% 的微生物细胞（1.5 × 10 ³至 1.1 × 10 ⁴吨碳生物量），在全球范围内栖息在塑料碎片中。作为海表水的一种非自然添加物，塑料碎片携带的大量细胞和生物量有可能影响海洋内的生物多样性、本土生态功能和生物地球化学循环。