Bight 23 Debris Harmonized

Trash is widespread in the marine environment and has known impacts on marine ecosystems. From July to September 2023, we conducted 123 benthic trawls on the soft-bottom seafloor across the Southern California Bight to capture, quantify, and categorize the extent and magnitude of trash. Data collected during this survey is directly comparable to regionwide data from the past three decades, enabling regional trend analysis of benthic trash. Trawl success (n = 89) was sufficient to draw representative conclusions from three of the targeted strata: bays, and the inner and middle continental shelves. Overall, trash was found to cover an estimated 19% of these three strata, with the greatest relative extent and magnitude in bays. Approximately 40% of the seafloor in bays contained trash at an abundance of nearly 19,000 trash items per km2, which is 16 to 28 times higher than on the inner or middle shelf, respectively. Plastic items were the most abundant and widespread trash type. Bight-wide plastic abundance was 1,008 items/km2. By comparison, all trash categories comprised 1,316 items/km2. Among identifiable plastics, single-use food packaging was most common, while trash related to fishing activities was rarely observed. Over the past 25 years, anthropogenic trash has remained relatively stable, ranging from 19% to 22% of the seafloor from these same strata between 1998 and 2023. These findings demonstrate that trash is widespread and persistent in the Southern California Bight, with trash hotspots and observations of single-use plastic pointing toward land-based sources as primary inputs. Planning Documents Field Manual Sediment Quality QA Plan Assessment Reports Trash and Marine Debris Report海洋环境中垃圾分布广泛，且已被证实会对海洋生态系统造成负面影响。2023年7月至9月，我们在南加利福尼亚湾（Southern California Bight）的软质底质海床（soft-bottom seafloor）开展了123次底拖网采样（benthic trawls），以捕获、量化并分类海洋垃圾的覆盖范围与污染程度。本次调查采集的数据可与过去三十年的区域数据直接对标，为底栖海洋垃圾的区域趋势分析提供支撑。有效拖网样本量为89份（n=89），足以从三个预设采样层带（strata）——海湾、大陆架内缘与中缘——得出具有代表性的研究结论。整体而言，上述三个层带中约19%的区域存在海洋垃圾，其中海湾区域的垃圾相对覆盖范围与污染程度最高。海湾区域约40%的海床存在垃圾，单位面积丰度近19000件/平方公里，分别比大陆架内缘和中缘高出16至28倍。塑料制品是丰度最高、分布最广的垃圾类型。南加利福尼亚湾全域塑料垃圾丰度为1008件/平方公里；相较之下，所有垃圾类别的总丰度为1316件/平方公里。在可识别的塑料制品中，一次性食品包装最为常见，而与渔业活动相关的垃圾则极少被观测到。1998年至2023年的过去25年间，上述采样层带的人为垃圾占比始终相对稳定，覆盖19%至22%的海床区域。本研究结果表明，南加利福尼亚湾的海洋垃圾分布广泛且持续存在，垃圾热点区域与一次性塑料的观测结果均显示，陆地来源是海洋垃圾的主要输入渠道。Planning Documents Field Manual Sediment Quality QA Plan Assessment Reports Trash and Marine Debris Report