Retroactive Determination of Movement at Age in Relation to Water Mass in Patagonian Toothfish Through Laser-Based Elemental Analysis of Otoliths

9614756 Jones激光电感耦合等离子体质谱法（LA-ICPMS）是首次在南大洋应用于研究巴塔哥尼亚齿鱼（Dissostichus eleginoides）年龄运动的新技术。鱼耳石中生长增量的化学结构反映了通过鳃的水的组成；增量还提供了捕获前单个鱼的生活史的时间顺序记录，并用于老化。使用LA-ICPMS进行元素分析，可以对耳石中的一系列元素进行精确采样，从而记录鱼所经历的水质量变化。这可以回溯到使用增量的年龄和实时。该项目是美国、英国、法国、智利和澳大利亚科学家的国际合作项目。这项核心合作是由老道明大学的科学家和英国南极调查局的科学家共同完成的，他们将目前最广泛的技术经验与南极生命系统的经验结合在一起。来自法国、智利、澳大利亚和美国的科学家提供了来自南大洋和南美洲南部的齿鱼耳石样本。该项目由四个相互关联的模块组成，解决了一个整体问题：巴塔哥尼亚齿鱼在其生活史上的运动模式与时间和空间中水质量的变化有关？目的是证明LA-ICPMS技术可以区分来自不同地理区域的巴塔哥尼亚齿鱼，开发一种有效的老化方法，并表征化学信号随年龄和年份之间的变化。其他目标是阐明不同的产卵地点，并回顾性地检查南大洋和巴塔哥尼亚-斯科舍弧区域内个别鱼类的特定年龄运动。NSF将只资助模块3（元素分析是否表明巴塔哥尼亚齿鱼在南大洋的大西洋、印度洋和太平洋区域之间运动？），而模块1、2和4将由其他政府资助。第一个模块包括使用LA-ICPMS对耳石元素变异性进行初步测试。第二是开发一种可靠的老化方法，使用边际增量分析，用完全有效的标准来解释生长增量。第三个模块包括使用LAICPMS分析从南大洋的麦夸里岛、克尔盖伦群岛和南乔治亚岛采集的鱼的耳石部分中存在的一系列元素。区域间耳石边缘元素浓度的区分将证实该技术可以检测出巴塔哥尼亚齿鱼的地理分离。按年级在核上的浓度区分将表明产卵地点是分开的。比较耳石中已知年龄的位置将测试元素剖面随年龄的变化，这些变化与鱼在水体之间的运动相对应。将同一已知年龄的不同年龄组别的鱼进行比较，将检验年份之间的差异。第四个模块在更精细的尺度上检查元素浓度，比较从智利北部和南部、福克兰群岛和南乔治亚州取样的耳石连续一年的地点。该项目的成果将直接惠及在南大洋内外工作的人口和生态系统生态学家、海洋学家和渔业管理人员。它们将表明在时间和空间上发生迁移的地方，以及人口可能被海洋屏障隔离的地方。老化标准的验证将对巴塔哥尼亚齿鱼的准确老化作出重大贡献。更好地了解鱼龄和种群结构以及混合水平对使用渔业产量模型很重要；更好地理解环境过程所起的作用将有助于更好地预测招聘和增长。耳石的化学结构可用作追溯性的环境记录，提供的数据可增进对年际变率在海洋生态系统结构中的作用的了解，并可探测与气候引起的变化有关的趋势。

9614756 Jones Laser-based Inductively-Coupled Plasma Mass Spectrometry LA-ICPMS) is a new technique, which is being applied for the first time in the Southern Ocean, to examine movement-at-age in Patagonian Toothfish (Dissostichus eleginoides). The chemical structure of growth increments in the otoliths of fish reflects the composition of water passing across the gills; the increments also give a chronological record of the life history of individual fish before capture and are used for aging. Elemental analysis using LA-ICPMS allows accurate sampling of a suite of elements in the otoliths, giving a record of changes in the water mass experienced by the fish. This can be related retroactively to age and real time using the increments. The project is an international collaboration between scientists from the United States, United Kingdom, France, Chile and Australia. The central collaboration is between scientists at Old Dominion University and the British Antarctic Survey, bringing together the most extensive experience currently available of the technique, with that of Antarctic life systems. Scientists from France, Chile, Australia and the United States are providing samples of Toothfish otoliths from the Southern Ocean and southern South America. The project consists of four inter-linked modules, addressing the overall question: what are the patterns of movement of Patagonian Toothfish over its life history in relation to variability of water mass in time and space? The objectives are to show that the LA-ICPMS technique can discriminate between Patagonian Toothfish from different geographical regions, develop a validated aging method, and characterize the variability of the chemical signal with age and between years. Other objectives are to elucidate differential spawning sites, and examine age-specific movement retrospectively in individual fish within the Southern Ocean, and within the Patagonia-Scotia Arc region. NSF will fund only module 3 (Does eleme ntal analysis indicate movement of Patagonian toothfish between the Atlantic, Inian, and Pacific sectors of the Southern Ocean?), while modules 1, 2, and 4 will be funded by other governments. The first module consists of a preliminary test for elemental variability in otoliths, using LA-ICPMS. The second is the development of a reliable aging method with fully validated criteria for interpretation of growth increments, using marginal increment analysis. The third module consists of analysing, with LAICPMS, a suite of elements present across otolith sections of fish taken from Macquarie Island, the Kerguelen Islands and South Georgia in the Southern Ocean. Discrimination of element concentrations at the otolith edge between regions will confirm that the technique can detect geographic separation in Patagonian Toothfish. Discrimination by year class of concentrations at the nucleus will indicate that spawning sites are separate. Comparison between known-age sites in the otoliths will test for changes in the elemental profile with age corresponding to movement of fish between water masses. Comparison between the same known-age sites of fish from different age classes will test for variability between years. The fourth module examines elemental concentrations on a finer scale, comparing consecutive year sites across otoliths sampled from northern and southern Chile, the Falkland Islands and South Georgia. The results of the project will be of direct benefit to population and ecosystem ecologists, oceanographers, and fisheries managers working in the Southern Ocean and outside. They will indicate where movement occurs in time and space, and where populations are isolated potentially by oceanographic barriers. The validation of aging criteria will be a major contribution to accurate aging of Patagonian Toothfish. Better knowledge of age and stock structure, and mixing levels, is important for the use of fisheries yield models; better understanding of the role playe d by environmental processes will allow better prediction of recruitment and growth. The chemical structure of the otolith may be used as a retroactive environmental record, giving data that may enhance understanding of the role of inter-annual variability in structuring marine ecosystems, and allow detection of trends associated with climate-induced change.