Bight 13 Benthic Infauna Abundance Harmonized

This report presents the results and interpretation of the macrobenthic infaunal component of the 2013 Southern California Bight (SCB) Regional Monitoring Program's Contaminant Impact Assessment element. The Southern California Bight is a 100,000-square-mile body of water and submerged continental shelf and slope extending from Point Conception, California in the north to Cabo Colnett, Baja California, Mexico in the south. The 2013 SCB Regional Monitoring Program (Bight'13) represents the joint effort of more than 100 organizations and is the continuation of an ongoing regional monitoring effort begun in 1998. Samples of benthic macrofauna were successfully collected at 361 sites across the Southern California Bight using a random tessellation stratified design, with samples allocated across 12 different strata including enclosed embayments, continental shelf, and continental slope zones. Samples were collected with a 0.1-m2 Van Veen grab, sieved on a 1-mm screen, and preserved for taxonomic identification to the lowest possible level. All data passed Quality Assurance/Quality Control Data Quality Objectives for sorting accuracy (97.7%), taxonomic identification accuracy (97.7%), taxonomic discrimination (91.6%), and counting accuracy (95.3%). The Benthic Response Index (BRI) was used to assess continental shelf samples and the California Sediment Quality Objectives Benthic Line of Evidence (SQO BLOE) framework was used for embayment samples. Results indicated that more than 98% of the assessable portions of the region were in good condition in 2013, with embayment strata in relatively poorer condition (over 16% in moderate or high disturbance) compared to continental shelf strata (1.2% in moderate disturbance, none in high disturbance). Temporal trend analysis covering 1998-2013 indicated that 63% of the region showed a stable trend in condition scores, 32% showed a declining trend, and 5% showed an improving trend, with the most notable reductions located in the Channel Islands stratum. Planning Documents: Bight13SedQualityQAPlan Bight13FieldManual Bight13MacrobenthicLabManual Bight13SedQualityIMPlan Assessment Reports: Bight'13 Benthic Infauna本报告呈现了2013年南加州湾（Southern California Bight, SCB）区域监测计划污染物影响评估模块下的大型底栖内栖生物组分的调查结果与解读。南加州湾总面积达10万平方英里，涵盖水域与水下大陆架及陆坡区域，北起美国加利福尼亚州的康塞普申角（Point Conception），南至墨西哥下加利福尼亚州的科洛内特角（Cabo Colnett）。2013年南加州湾区域监测计划（简称Bight'13）由超100家机构联合推进，是1998年启动的长期区域监测工作的延续。 本研究采用随机镶嵌分层采样设计，在南加州湾全域361个采样点成功采集底栖大型动物样本，样本被分配至12个不同采样分层，包括封闭海湾、大陆架及大陆坡区域。采样使用0.1平方米的范维恩采泥器（Van Veen grab），采集后以1毫米孔径筛网冲洗分选，并保存样本以开展尽可能精细的分类鉴定。所有数据均符合质量保证与质量控制（QA/QC）的数据质量目标要求：分选准确率达97.7%、分类鉴定准确率达97.7%、分类区分度达91.6%、计数准确率达95.3%。 针对大陆架区域样本，采用底栖生物响应指数（Benthic Response Index, BRI）开展评估；针对海湾区域样本，则采用加州沉积物质量目标底栖证据链（California Sediment Quality Objectives Benthic Line of Evidence, SQO BLOE）框架进行评价。评估结果显示，2013年该区域超98%的可评估区域处于良好状态；相较大陆架分层（仅1.2%区域存在中度扰动，无高度扰动区域），海湾分层的生态状况相对更差，超16%的区域存在中度或高度扰动。 针对1998-2013年的时间趋势分析表明，该区域63%的区域生态状况评分呈稳定趋势，32%呈下降趋势，5%呈上升趋势，其中海峡群岛分层的生态状况下降最为显著。 规划文件：Bight13SedQualityQAPlan、Bight13FieldManual、Bight13MacrobenthicLabManual、Bight13SedQualityIMPlan 评估报告：Bight'13 底栖内栖生物