The Mediterranean Sea is one of the most polluted marine basins and currently serves as a hotspot for marine litter. The seafloor represents the ultimate sink for most litter worldwide. Nevertheless, the knowledge about litter distribution and its interactions with benthic organisms in deep water is poorly understood. In 2018, we investigated spatial patterns of macro- and micro-litter distribution, and their effects on benthic communities in the Ligurian Sea. An oceanographic survey was carried out with a remotely operated vehicle and a multibeam echosounder on seven seamounts and canyons, at depths ranging from 350 to 2200 m. High litter accumulations were discovered at the mouth of the Monaco canyon, where estimated densities of up to 3.8 × 10⁴ items km^-2 were found at 2200 m depth. The highest abundance of urban litter items was found on the soft substrate, at the bottom of the deeper parts of the submarine canyons, which seem to act as conduits carrying litter from the shelf towards deeper areas. In contrast, fishing-related items were most abundant in the upper layer of the seamounts (300–600 m depths). Furthermore, more than 10% of the observed deep gorgonian colonies were entangled by lost longlines, indicating the detrimental effects of this fishing gear on benthic habitats. The discovery of new litter hotspots and the evaluation of how deep-sea species interact with litter contribute to increasing the knowledge about litter distribution and its effects on the deep ecosystem of the Mediterranean basin. All the observations recorded in this study showed substantial and irreversible changes in the deep and remote areas of marine environments, and these changes were found to be caused by humans. Our findings further stress the need for urgent and specific measures for the management of deep-sea pollution and the reduction of litter inputs in the environment.

地中海是污染最严重的海洋盆地之一，目前是海洋垃圾的热点地区。海底代表了全球大多数垃圾的最终汇入点。然而，关于垃圾分布及其与深水底栖生物相互作用的知识知之甚少。在2018年，我们调查了宏观和微观凋落物分布的空间格局及其对利古里亚海底栖生物群落的影响。在7个海山和峡谷上，用遥控车辆和多波束回声测深仪进行了海洋学调查，测深范围为350至2200 m。在摩纳哥峡谷的河口发现了大量的凋落物，估计密度高达3.8×10 ⁴平方公里km ^-2被发现在2200 m的深度。在海底峡谷较深部分的底部，在柔软的基质上发现了数量最多的城市垃圾，这些垃圾似乎起着将垃圾从架子向更深的区域运送的作用。相反，与捕鱼有关的物品在海山上层（300-600 m深度）最丰富。此外，超过10％的观察到的深戈尔贡人殖民地被延绳钓缠住，表明该渔具对底栖生境的有害影响。新的凋落物热点的发现以及深海物种与凋落物之间的相互作用的评估有助于增加有关凋落物分布及其对地中海盆地深层生态系统影响的知识。这项研究中记录的所有观察结果表明，在海洋环境的深处和偏远地区发生了巨大且不可逆的变化，这些变化被发现是由人类造成的。我们的研究结果进一步强调，需要采取紧急和具体措施来管理深海污染和减少环境中的垃圾投入。