GLOBEC 2000 -- A long-Term Observation Program Using Natural Stable Isotope Abundance for Detecting Coastal Gulf of Alaska Zooplankton Source Fluctuations in Fishes

据推测，次北冰洋生产周期的十年尺度变化会通过浮游动物饲料基地影响鱼类种群的变化。发生在阿拉斯加湾大陆架断裂附近的浮游动物种群似乎在十年时间尺度上经历了戏剧性的振荡。它们主要由带间(因为生活史阶段跨越浅水区和深水区)浮游动物(主要是Neocalanus spp)组成。这个项目产生的数据将能够评估阿拉斯加湾大陆架大型浮游动物(主要是Neocalanus)在每年春季和夏季高峰期的季节性(2001年和2003年)和年际15N/14N和13C/12C的变化，这将与粉红色鲑鱼和其他幼鱼的类似测量结果相匹配。这些数据将用于描述沿海和海洋(近海)有机碳源及其被鱼类利用的同位素特征。鱼类和滞育的桡足类的同位素变化预计将同步变化，与跨陆架运输的强度成比例地变化。该项目将加强和补充沿Seward Line样带(GAK1至GAK13)进行的现有和持续的核心LTOP观测，并选择靠近威廉王子湾和位于威廉王子湾的部分站点。从1997年秋季到2000年夏季，P.I.在LTOP试点项目(P.I.Weingartner)上获取的样本在2001财年和2002财年期间，作为该项目的一部分，将对邮轮的13C/12C和15N/14N内容进行分析。在2001年至2005年期间，将作为该项目的一部分收集和分析更多的样本。这些数据还将被用来验证NEP GLOBEC回顾研究中的默认假设，即较低食物链生物群的15N/14N值是恒定的，以便可以解释变化的值以反映食物链长度或鲑鱼游动大小的变化。

Decadal-scale changes in the production cycles of the sub-Arctic Pacific Ocean have been conjectured to effect population changes in fishes via their zooplankton forage base. Zooplankton populations occurring near the Gulf of Alaska continental shelf break appear to undergo dramatic oscillations in abundance over decadal time scales. These consist principally of inter-zonal (because life-history stages span shallow- and deep-water zones) zooplankton (primarily Neocalanus spp. copepods) stocks that are driven onto the shelf providing the ecosystem with an important forage base.The data arising from this project will enable the assessment of seasonal (during 2001 and 2003) and inter-annual 15N/14N and 13C/12C variability of large-bodied zooplankton (primarily Neocalanus) across the Gulf of Alaska continental shelf during their peak occurrence in spring and summer each year, that will be matched to analogous measurements for juvenile pink salmon and other fishes. These data will be used to isotopically characterize coastal and oceanic (offshore) organic carbon sources and their utilization by fishes. Isotopic shifts in fishes and diapausing copepods are expected to shift in synchrony varying proportionately with the intensity of cross-shelf transport. This project will augment and complement existing and continuing core LTOP observations being made along the Seward Line transect (GAK1 to GAK13) and select stations near and in Prince William Sound. Samples that were acquired by the P.I. from fall 1997 through summer 2000 on pilot LTOP project (Weingartner, P.I.) cruises will be analyzed for 13C/12C and 15N/14N content as part of this project during FY2001 and FY2002. Additional samples will be collected and analyzed as part of this project from 2001 through 2005. The data will also be used to validate the tacit assumption in NEP GLOBEC retrospective studies that 15N/14N values of lower food chain biota are constant so that so that changing values can be interpreted to reflect varying food chain length or salmon run size.