Importance of Winter Upwelling to California Current Ecosystem Dynamics

气候变率在多个时间尺度上越来越被认为是影响加州洋流生态系统结构、功能和生产力的主要因素。然而，尽管进行了长期和综合的研究，我们仍然缺乏对气候影响的详细了解，这影响了我们解释生态系统随时间变化的能力，并影响了我们利用这些信息评估生态系统健康和恢复力等重要概念的能力。最近，为了更好地确定气候的影响，人们强调了鱼类和海鸟的繁殖和生长策略与生态系统物候的关系，特别是从冬季到春季上升流条件的所谓“春季过渡”的时间。然而，目前还没有建立春季过渡的明确定义，估计的春季过渡日期不能充分预测生态系统的生产力。此外，越来越多的证据表明，在传统的春季过渡日期之前，生态系统生产力对冬季海洋变化最为敏感。为了解决冬季海洋条件的重要性，将根据环境变化整理和分析与生长和繁殖成功有关的独特岩鱼和海鸟时间序列。所有岩鱼和海鸟的时间序列都是几十年的长度，每年确定，并通过整合生态系统的生产力，在它通过多个较低的营养水平级联之后，从顶部提供一个视图。考虑到岩鱼和海鸟的数据相互独立地加强，这种多物种方法尤其强大。试点工作表明，岩鱼和海鸟的时间序列密切相关，而这些关系是由对冬季海洋条件的共同敏感性驱动的，特别是2月份的上升流。因此，本研究的目的是：1)量化岩石鱼和海鸟生长和繁殖时间序列之间的相互关系；2)确定与岩石鱼和海鸟的协变相对应的气候变量，重点是冬季月份；3)评估生态系统中主要猎物——大鳞甲壳类动物的丰度、分布和空间组织与海鸟、岩石鱼和冬季海洋条件的协变程度。本研究将确定气候对主要上营养层物种影响最大的年份，并提供加州洋流生态系统生态系统生产力的主要生物和物理指标。这些生物物理指标将用于纳入渔业种群评估，也将用于预测各种气候情景下的渔业反应。这些信息还将为NOAA-NMFS和其他机构正在开发的加州当前综合生态系统评估提供投入。此外，该项目还将提供物理海洋学的博士后培训和岩鱼耳石生长增量分析的本科生培训。

Climate variability on multiple temporal scales is increasingly recognized as a major factor influencing the structure, functioning, and productivity of the California Current Ecosystem. Yet despite long-term and integrative studies, a detailed understanding of climatic impacts is still lacking, compromising our abilities to interpret ecosystem variability over time and use that information to assess important concepts such as ecosystem health and resilience. Recent attempts to better establish the effects of climate have emphasized the relationship of reproductive and growth strategies of fish and seabirds to ecosystem phenology, particularly the timing of what is known as the "spring transition" from wintertime to spring upwelling conditions. However, there no clear definition of the spring transition has yet been established, and estimated spring transition dates do not adequately predict ecosystem productivity. Moreover, an increasing body of evidence suggests that ecosystem productivity is most sensitive to wintertime ocean variability prior to the traditional spring transition date. To address the importance of wintertime ocean conditions, a unique assemblage of rockfish and seabird time series relating to growth and reproductive success will be collated and analyzed with respect to environmental variability. All rockfish and seabird time series are multidecadal in length, annually resolved, and provide a view from the top by integrating ecosystem productivity after it has cascaded up through multiple lower trophic levels. This multi-species approach is particularly powerful considering that rockfish and seabird data independently reinforce one another. Pilot work shows that rockfish and seabird time series are strongly interrelated, and that these relationships are driven by shared sensitivities to wintertime ocean conditions, particularly February upwelling. Thus, the objectives of this study are to i) quantify the interrelationships among rockfish and seabird growth and reproduction time series, ii) identify the climatic variables, with an emphasis on the winter months, that correspond with covariability in rockfish and seabirds, and iii) evaluate the extent to which the abundance, distribution, and spatial organization of euphausiid crustaceans, a key prey item in the ecosystem, covary with seabirds, rockfish, and wintertime ocean conditions.This study will establish the times of year under which climate exerts the greatest influence on key upper-trophic level species, and provide leading biological and physical indicators of ecosystem productivity in the California Current Ecosystem. These biophysical indicators will be made available for integration into fisheries stock assessments and will also be of use for forecasting fisheries responses under various climatic scenarios. This information will also provide input to the California Current Integrated Ecosystem Assessment under development by NOAA-NMFS and others. In addition, the project will provide postdoctoral training in physical oceanography and undergraduate training in rockfish otolith growth-increment analysis.