Collaborative Research: Origins of Cods on Georges Bank: Contributions of Early Developmental Stages for the Scotian Shelf

合作研究：乔治浅滩鳕鱼的起源：早期发育阶段对斯科舍大陆架的贡献

• 批准号: 9806712
• 负责人: David Townsend
• 金额: $ 49.26万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-10-01 至 2002-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9806712&HistoricalAwards=false
• 关键词: Collaborative; Research; Origins; Cods; Georges

9806712TownsendRecent work in the Georges Bank-Gulf of Maine area has documented significant, and apparently episodic, fluxes of Scotian Shelf Water (SSW) from the Nova Scotian continental shelf to Georges Bank. SSW is a relatively cold and fresh water mass with a significant component from the St. Lawrence River, and is commonly identifiable with temperature-salinity analyses of hydrographic data and in satellite images of sea surface temperature. One such flux episode was observed last March (1997) in satellite imagery and from shipboard hydrographic sampling on Georges Bank. Qualitative at-sea analyses of ichthyoplankton sampled on the March cruise revealed a remarkably tight association between abundances of gadid eggs and the distribution of SSW suggesting, along with other lines of evidence, that most of those eggs were spawned on the Scotian Shelf and were advected with the SSW water mass to Georges Bank. The fundamental question thus arises: to what extent are cod on Georges Bank imported to the Bank as early development stages by advection from Canadian waters to the east? The goal of this research is to answer the above question. The approach will be two tiered: (1) Drs. Townsend and Radtke will perform retrospective elemental analyses of otoliths from archived larval cod samples, as well as of ichthyoplankton samples to be collected in 1998 and 1999 as part of the continuing Georges Bank GLOBEC project, analyzing them for Sr/Ca ratios, using an X-ray electron microprobe, and elemental "fingerprints", using UV lazer ablation inductively coupled plasma mass spectroscopy (ICPMS). (2) They will also assess the genetic identity of the larvae relative to larval and adult populations from Georges Bank and from the Scotian Shelf using nuclear DNA microsatellite techniques. They will first verify the elemental composition of otoliths from cod larvae known to have been spawned in the two locations. This elemental analyses will be combined with laboratory rearing experiments of larvae to determine the effects of temperature, salinity, feeding, and growth rates on the incorporation of elements in the otoliths. DNA based techniques will be used to identify individuals in these common-garden rearing experiments. The second step will be to identify the origin of larvae based on individual DNA profiles generated by characterizing nuclear DNA microsatellites, a new class of genetic markers that they have used to differentiate Georges Bank cod from those of Scotian Shelf waters. The intent in using the two different, independent approaches is to be able to identify the spawning locations of the larvae and track their transport in relation to hydrographic characteristics of water masses in the region.

9806712汤森最近在乔治银行-缅因州海湾地区的工作记录了显著的，显然是偶发性的，从新斯科舍大陆架到乔治银行的斯科舍陆架水（SSW）通量。SSW是一个相对较冷的淡水团，主要成分来自圣劳伦斯河，通常可以通过水文数据的温度-盐度分析和海洋表面温度的卫星图像来识别。去年3月（1997年），在卫星图像和乔治海岸的船上水文取样中观察到了一次这样的通量事件。定性分析在3月巡航采样的鱼类浮游生物显示了一个显着的紧密联系之间的丰度gadid蛋和SSW的分布，这表明，沿着其他线的证据，这些鸡蛋中的大多数是在斯科舍大陆架上产卵，并平流与SSW水团乔治银行。这样就产生了一个基本问题：在多大程度上，乔治浅滩的鳕鱼在早期发展阶段是通过从加拿大沃茨向东的平流输入到该浅滩的？本研究的目的就是回答上述问题。该方法将分为两个层次：（1）汤森博士和拉德克博士将对存档的鳕鱼幼鱼样本的耳石以及作为乔治银行全球生物中心项目的一部分将于1998年和1999年收集的浮游鱼类样本进行回顾性元素分析，使用X射线电子微探针和元素“指纹”分析它们的Sr/Ca比率，使用UV激光烧蚀电感耦合等离子体质谱（ICPMS）。 (2)他们还将使用核DNA微卫星技术评估幼虫相对于乔治银行和斯科舍大陆架的幼虫和成虫种群的遗传特性。他们将首先验证已知在这两个地点产卵的鳕鱼幼虫的耳石的元素组成。这种元素分析将结合实验室饲养实验的幼虫，以确定温度，盐度，喂养和生长速度的影响，在耳石中的元素的掺入。 基于DNA的技术将用于识别这些共同花园饲养实验中的个体。第二步将是根据表征核DNA微卫星产生的个体DNA图谱来确定幼虫的起源，核DNA微卫星是一类新的遗传标记，他们曾用它来区分乔治浅滩鳕鱼和斯科舍陆架沃茨。使用这两种不同的独立方法的目的是能够确定幼虫的产卵地点，并根据该区域水团的水文特征跟踪其运输。