Bight 23 Grab Event

The Southern California Bight 2023 Regional Monitoring Program (Bight '23) is the seventh in a series of regional marine monitoring efforts beginning with a pilot project in 1994 and repeated in 1998, 2003, 2008, 2013, and 2018. More than 100 different organizations encompassing regulatory, regulated, academic, and non-governmental agencies collaborated in the Bight '23 Program. This report presents the results of the Demersal Fishes and Megabenthic Invertebrates sub-element, one component of the sediment quality element that utilizes multiple lines of evidence to assess coastal ecosystem health. A stratified random sampling design was used to assess areal extent of environmental condition across five strata: three continental shelf strata (4-30 m, 31-120 m, 121-200 m), an upper slope stratum (201-500 m), and an embayment stratum. A total of 122 trawl stations were sampled, capturing more than 53,194 fishes from 50 families and 130 species, and more than 63,360 invertebrates from 88 families and 140 species. Approximately 95% of SCB inner and middle continental shelf areas (3 to 120 m depth) had Fish Response Index (FRI) values indicative of reference conditions. Pollutant-related stress anomalies such as external tumors, lesions, or fin erosion comprised less than 0.03% of all fishes examined. The extent of reference-like fish communities has remained comparably high over three decades of the Bight Program, ranging from 91% to 100% of reference area since Bight '94. Megabenthic invertebrate communities also showed no major trends or changes in traditional ecological metrics such as diversity or richness, indicating a stable ecological community. Due to limited participation, the outer shelf and upper slope strata did not meet data quality objectives for completeness and were not assessed regionally.南加州湾2023年区域监测项目（Southern California Bight 2023 Regional Monitoring Program, Bight '23）是系列区域海洋监测工作的第七次项目，该系列始于1994年的试点项目，并分别于1998年、2003年、2008年、2013年及2018年重复开展。本次Bight '23项目共有超100家涵盖监管机构、被监管主体、学术机构及非政府组织的不同单位参与协作。 本报告呈现了底栖鱼类（Demersal Fishes）与大型底栖无脊椎动物（Megabenthic Invertebrates）子模块的监测结果，该子模块属于沉积物质量组分（sediment quality element）的一部分，依托多证据链开展近岸生态系统健康评估。本次监测采用分层随机抽样设计（stratified random sampling design），对五类分层的环境状况覆盖范围进行评估：三类大陆架分层（4~30米、31~120米、121~200米）、一个上坡带分层（201~500米）及一个海湾分层。 本次共布设122个拖网采样站位（trawl stations），采集到隶属于50个科、130个物种的鱼类共53194余尾，以及隶属于88个科、140个物种的无脊椎动物共63360余只。南加州湾（Southern California Bight, SCB）内、中大陆架区域（水深3~120米）中约95%的区域的鱼类响应指数（Fish Response Index, FRI）值符合参照条件标准。受检鱼类中，由污染物引发的胁迫异常（如体表肿瘤、组织损伤或鳍部糜烂）占比不足0.03%。 在Bight系列项目开展的三十余年间，类似参照群落的鱼类群落覆盖范围始终维持在较高水平，自1994年Bight项目以来，其占参照区域的比例介于91%~100%之间。大型底栖无脊椎动物群落的传统生态指标（如多样性、丰富度）未出现显著趋势或变化，表明群落生态状态稳定。由于参与度有限，外陆架及上坡带分层未达到数据完整性的质量目标，因此未开展区域评估。