Origins of Cod on Georges Bank: Contributions of Early Developmental Stages from the Scotian Shelf

乔治银行鳕鱼的起源：早期发展阶段的贡献从斯科舍ShelfRecent工作在乔治银行海湾的缅因州地区记录了显着的，显然是情节，斯科舍陆架水（SSW）通量从新斯科舍省大陆架乔治银行。 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T-S分析和海洋表面温度的卫星图像来识别。 1997年3月，在卫星图像中和在乔治浅滩的船上水文取样中观测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这个问题。 该方法将分为两个层次：（1）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多样性项目的一部分将于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射线电子显微探针分析Sr/Ca比值和元素“指纹”，使用紫外激光消融电感耦合等离子体质谱法（ICPMS）;（2）使用核DNA微卫星技术评估幼虫相对于来自乔治浅滩和斯科舍大陆架的幼虫和成虫种群的遗传特性。

Origins of Cod on Georges Bank: Contribution of Early Developmental Stages from the Scotian ShelfRecent 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 T-S analyses of hydrographic data and in satellite images of sea surface temperature. One such flux episode was observed 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 this question. The approach will be two tiered: (1) performing 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); and (2) assessing 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.