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汤森最近在乔治浅滩-缅因湾地区的工作记录了从新斯科舍大陆架到乔治浅滩的斯科舍陆架水（SSW）的显着且明显间歇性的通量。 SSW 是一个相对寒冷的淡水团，主要成分来自圣劳伦斯河，通常可以通过水文数据的温度-盐度分析和海面温度的卫星图像来识别。去年 3 月（1997 年），通过卫星图像和乔治浅滩的船上水文采样观察到了一次这样的通量事件。对三月航行中采集的浮游鱼类样本进行的海上定性分析显示，海鱼卵的丰度与SSW的分布之间存在着非常紧密的联系，与其他证据一起表明，这些卵中的大多数是在斯科舍大陆架上产卵并通过平流输送的与 SSW 水团一起到达乔治浅滩。因此出现了一个基本问题：乔治浅滩上的鳕鱼在早期发育阶段在多大程度上是通过从加拿大水域向东部的平流进口到乔治浅滩的？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）博士。 Townsend 和 Radtke 将对存档的鳕鱼幼虫样本中的耳石以及 1998 年和 1999 年收集的鱼类浮游生物样本进行回顾性元素分析，作为持续的乔治银行 GLOBEC 项目的一部分，使用 X 分析它们的 Sr/Ca 比率。射线电子显微探针和元素“指纹”，使用紫外激光烧蚀电感耦合等离子体质谱法（ICPMS）。 (2) 他们还将使用核 DNA 微卫星技术评估幼虫相对于乔治滩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成分。这种元素分析将与幼虫的实验室饲养实验相结合，以确定温度、盐度、摄食和生长速率对耳石中元素掺入的影响。 基于 DNA 的技术将用于识别这些普通花园饲养实验中的个体。第二步将是根据核 DNA 微卫星特征生成的个体 DNA 图谱来识别幼虫的起源，这是一类新型遗传标记，他们用它来区分乔治银行鳕鱼和斯科舍大陆架水域的鳕鱼。使用两种不同的、独立的方法的目的是能够识别幼虫的产卵位置，并根据该地区水团的水文特征跟踪它们的运输。