Importance of Winter Upwelling to California Current Ecosystem Dynamics

气候在多个时间尺度上的变异性日益被认为是影响加州当前生态系统结构、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，但仍然缺乏对气候影响的详细了解，这损害了我们解释生态系统随时间变化并利用这些信息评估生态系统健康和复原力等重要概念的能力。最近更好地确定气候影响的努力强调了鱼类和海鸟的繁殖和生长战略与生态系统物候的关系，特别是所谓的从冬季到春季上升流条件的“春季过渡”的时间安排。然而，对春季过渡还没有明确的定义，估计的春季过渡日期也不能充分预测生态系统生产力。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敏感。为了处理冬季海洋条件的重要性，将根据环境变异性，整理和分析与生长和繁殖成功有关的独特的岩鱼和海鸟时间序列。所有岩鱼和海鸟的时间序列都有几十年的长度，每年都可以分辨，并通过在级联通过多个较低营养层后整合生态系统生产力从顶部提供了一个视角。考虑到岩鱼和海鸟的数据相互独立地相互加强，这种多物种方法特别有效。试点工作表明，岩鱼和海鸟的时间序列具有很强的相关性，这些关系是由对冬季海洋条件的共同敏感性推动的，特别是2月份的上升流。因此，这项研究的目标是i)量化岩鱼和海鸟生长和繁殖时间序列之间的相互关系，ii)确定气候变量，重点是冬季，与岩鱼和海鸟的协变性相对应，以及iii)评估生态系统中的关键猎物--真甲壳类动物的丰度、分布和空间组织程度，以及与海鸟、岩鱼和冬季海洋条件共同变化的程度。本研究将建立气候对关键的上层营养层物种影响最大的一年中的时间，并提供领先的生态系统生产力的生物学和物理指标。这些生物物理指标将被纳入渔业种群评估，并将用于预报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资料。此外，该项目将提供物理海洋学博士后培训和岩鱼耳石生长-增量分析本科生培训。

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.