Toxicity of single metals and metal mixtures to Antarctic Marine Copepods

This metadata record contains the results of two bioassays testing the response of Antarctic marine copepods to both individual and combined metals via 14 day toxicity tests. The tests were conducted during the 2012-2013 season at Davis Station, East Antarctica.

Three metals (cadmium, copper and zinc) were tested singularly and in metal mixture combinations. The concentrations used in the two tests are outlined in the excel spreadsheet (AAS4100_12-13_MixedMetalTox.xlsx). Tests were carried out in 70 mL plastic vials (exposure vials) that contained 50 mL of test solutions. Test solutions were prepared by mixing stock solutions with filtered (0.45 microns) sea water and were stored in a constant temperature cabinet at 0 plus or minus 1 degree C for at least 2 hours prior to the start of tests in order to get to the required test temperature. Each treatment included four replicates and each test included eight controls. Within each replicate vial, 9-12 copepods were carefully added. No additional air, food or water was provided over the test period. At five days a water change was completed by removing the old test solution and replacing it with freshly prepared test solution at the same concentration. The tests were carried out in a constant temperature cabinet set at 0 plus or minus 1 degree C on a 16:8 light:dark photoperiod over 14 days. The number of surviving copepods were counted in each test container, at the same time each day, for 10 days and then a final count was completed on day 14. Mortality was determined by observing the copepods over 20 seconds and if there was no movement they were considered dead.

Test solutions were sampled four times during the tests for measurement of metal concentrations. Samples were collected at day 0, day 5 pre-water change, day 5 post-water change and at day 10. Concentrations of the three test metals were determined in theses samples using Inductively-Coupled Plasma Optical Emission Spectrometer (ICP-OES) with appropriate matrix matched standards and blanks to ensure quality control.

For all analyses, measured metal concentrations (as opposed to nominal concentrations) were used. Point estimates, including LC10 and LC50 values, were determined using the maximum likelihood-probit method using the software ToxCalc (version 5.0.26 Tidepool Scientific Software). Point estimates were calculated at 4, 7, 10 and 14 days of exposure. Whenever the assumptions for the maximum likelihood-probit method were not met then the Trimmed Spearman-Karber Analysis was used.

Data are provided in an Excel workbook (filename: AAS4100_12-13_MixedMetalTox.xlsx). The first worksheet ("/Test Conditions") provides descriptive details for the tests and a key to abbreviations and units. Each worksheet includes a "This worksheet provides..." statement to assist interpretation of the data. A second data file is provided (filename: AAS4100_12-13_ToxCalc.xlsx) containing relevant test data from AAS4100_12-13_MixedMetalTox.xlsx, for input to ToxCalc software for analysis. This file also contains subsequent ToxCalc outputs, with key data (LC10 and LC50 values) provided in a summary worksheet.

Other support files provided are seven images of the test species (images by Frances Alexander) and two figures showing copepod response to test solutions (% survival) over the exposure period of the two tests.

Copepod samples were collected from the nearshore environment of Prydz Bay, offshore from Davis Station, on two days: 20 December 2012 and 9 January 2013. The 20 December collection was composed of Tisbe sp., collected from benthic habitats and the 9 January collection was composed of Paralabidocera Antarctica, collected from surface waters.

Two 14-day laboratory-based toxicity tests were conducted in the Davis laboratories. The test dates were: 2 - 16 January 2013 (test 01; using Tisbe sp., collected 20 December 2012) and 10 - 24 January 2013 (test 02; using P. Antarctica, collected 9 January 2013).

本元数据记录包含两项生物测定（bioassays）的结果，该试验通过14天毒性测试，探究南极海洋桡足类（Antarctic marine copepods）对单一金属及复合金属的响应。试验于2012-2013年科考季在南极东部戴维斯站（Davis Station）开展。

本次试验共测试镉（cadmium）、铜（copper）与锌（zinc）三种金属，分别设置单一金属处理与复合金属混合处理。两项试验所用浓度详见Excel电子表格（AAS4100_12-13_MixedMetalTox.xlsx）。

试验在70 mL塑料培养瓶（暴露瓶）中进行，每瓶装入50 mL试验液。试验液由储备液与过滤（0.45微米）海水混合配制而成，并置于0±1℃的恒温箱中静置至少2小时，以达到试验所需温度。每个处理组设置4个重复组，每项试验设置8个对照组。每个重复瓶中小心移入9-12只桡足类。试验期间不额外添加空气、食物或水体。试验进行至第5天时，完成换水操作：移除旧试验液，更换为同浓度的新鲜配制试验液。试验全程在0±1℃的恒温箱中开展，采用16:8的光暗周期（light:dark photoperiod），总时长14天。

每日固定时间对每个试验容器中的存活桡足类进行计数，持续10天，最终于第14天完成末次计数。死亡率通过观察桡足类20秒判定，无运动个体视为死亡。

试验期间共采集4次试验液样本，用于金属浓度测定。样本分别采集于试验第0天、第5天换水前、第5天换水后及第10天。采用电感耦合等离子体发射光谱仪（Inductively-Coupled Plasma Optical Emission Spectrometer，ICP-OES）对三种试验金属的浓度进行测定，同时使用匹配基体标准品与空白对照以保障质量控制。

所有分析均采用实测金属浓度（而非标称浓度）。使用Tidepool Scientific Software开发的ToxCalc软件（版本5.0.26），通过最大似然-概率单位法（maximum likelihood-probit method）计算包括LC10、LC50值在内的点估计值。点估计值分别于暴露4、7、10及14天时计算。当最大似然-概率单位法的假设条件未满足时，则采用修正斯皮尔曼-卡伯分析法（Trimmed Spearman-Karber Analysis）。

试验数据存储于Excel工作簿（文件名：AAS4100_12-13_MixedMetalTox.xlsx）中。首个工作表（"Test Conditions"）提供了试验的描述性细节以及缩写与单位对照表。每个工作表均附带“此工作表提供……”的说明文本，以辅助数据解读。另有第二份数据文件（文件名：AAS4100_12-13_ToxCalc.xlsx），包含来自AAS4100_12-13_MixedMetalTox.xlsx的相关试验数据，用于输入ToxCalc软件进行分析。该文件同时包含后续的ToxCalc输出结果，其摘要工作表中提供了关键数据（LC10与LC50值）。

附带的其他支持文件包括7张试验物种的影像（由Frances Alexander拍摄），以及2张展示两项试验中桡足类对试验液的响应（存活率百分比）随暴露周期变化的图表。

桡足类样本采集于戴维斯站近海的普里兹湾（Prydz Bay）近岸环境，分别于2012年12月20日与2013年1月9日两次采集。2012年12月20日采集的样本为尖水虱属（Tisbe sp.），采自底栖生境（benthic habitats）；2013年1月9日采集的样本为南极拟唇足水蚤（Paralabidocera Antarctica），采自表层水体（surface waters）。

两项14天室内毒性试验均在戴维斯站实验室开展，试验日期分别为：2013年1月2日至16日（试验01，使用2012年12月20日采集的Tisbe sp.），以及2013年1月10日至24日（试验02，使用2013年1月9日采集的Paralabidocera Antarctica）。