Bight 08 Benthic Infauna Abundance Harmonized

This report describes the benthic macrofaunal studies of the Southern California Bight (SCB) Regional Marine Monitoring Program (Bight'08), the fourth SCB regional survey conducted in 2008. The Southern California Bight is a 100,000-square-mile body of water and submerged continental shelf extending from Point Conception, California in the north to Cabo Colnett, Baja California, Mexico in the south. Benthic macrofauna were successfully collected and processed from 382 sites between Point Conception and the United States-Mexican border using a random tessellation stratified (RTS) study design. Sites ranging in depth from 0.3 to 1,023 m were stratified into 10 habitats including inner, middle, and outer continental shelf; Channel Island continental shelf; upper continental slope; lower continental slope and basins; estuaries, ports, marinas, and other bays. Samples were collected with a 0.1-m2 Van Veen grab, sieved through a 1-mm mesh screen, and processed using standard laboratory methods. A total of 179,338 organisms from 1,734 taxa were identified and counted. Two assessment tools were applied: the Benthic Response Index (BRI) for mainland and island shelf habitats, and the Sediment Quality Objectives Benthic Line of Evidence (BLOE) for marine bays and estuaries. Overall, the SCB benthos were in good condition during 2008, with 99.7% of the SCB in reference condition or deviating only marginally from reference. No evidence of disturbance was found on the island shelf or the mainland shelf. Macrofaunal communities in embayments were more frequently disturbed, with slightly over 12% of embayment area containing clearly disturbed benthos. Benthic communities in poor condition occupied more than half the area (59.0%) of southern California estuaries and more than a third (37.4%) of marinas. Regional benthic community condition showed no dramatic change between 1994 and 2008, with disturbed benthic community remaining less than 4% of the SCB for the last 15 years. A special study on gear size effects found that none of the tested sample areas were clearly preferable to the existing standard 0.1 m2 method.本报告阐述了南加州湾（Southern California Bight, SCB）区域海洋监测项目（Bight'08）的底栖大型动物研究，该项目是2008年开展的第四届南加州湾区域调查。南加州湾是一片面积达10万平方英里的水域与淹没大陆架，北起加利福尼亚州的康塞普西翁角，南至墨西哥下加利福尼亚州的科洛内特角。本研究采用随机镶嵌分层（random tessellation stratified, RTS）采样设计，在康塞普西翁角至美墨边境之间的382个采样点成功采集并处理了底栖大型动物样本。采样点水深范围为0.3至1023米，被划分为10类生境，包括大陆架内区、中架区与外架区、海峡群岛大陆架、大陆架上斜坡、大陆架下斜坡与盆地，以及河口、港口、游艇码头及其他海湾。样本采用0.1平方米范·维恩采泥器（Van Veen grab）采集，经1毫米孔径筛网筛分后，按照标准实验室流程进行处理。本次研究共鉴定并计数了1734个分类单元对应的179338个生物体。研究采用了两类评估工具：针对大陆与岛屿架生境的底栖响应指数（Benthic Response Index, BRI），以及针对海洋海湾与河口的沉积物质量目标底栖证据线（Sediment Quality Objectives Benthic Line of Evidence, BLOE）。总体而言，2008年南加州湾的底栖生物群落整体状况良好，99.7%的区域处于参考状态或仅与参考状态存在轻微偏离。岛屿架与大陆架未发现任何扰动迹象。海湾内的大型动物群落受扰动频率更高，略超过12%的海湾区域存在明显受扰的底栖生物群落。状况不佳的底栖群落占据了南加州河口超过一半的面积（59.0%），以及超过三分之一（37.4%）的游艇码头区域。1994年至2008年间，区域底栖群落状况未出现显著变化，过去15年中，受扰底栖群落占南加州湾总面积的比例始终低于4%。一项针对采泥器尺寸效应的专项研究发现，所有测试采样面积均未明显优于现行标准的0.1平方米采样方法。