Collaborative Proposal: Optimizing Recruitment of Neocalanus copepods through Strategic Timing of Reproduction and Growth in the Gulf of Alaska

阿拉斯加湾支持着一个多样化和多产的海洋群落，其中包括许多商业上重要的鱼类。在这个食物网的底部是小型浮游甲壳类动物，它们是许多这些鱼类、海鸟和海洋哺乳动物的主要食物来源。桡足类动物新弗莱明是这些甲壳类动物之一，在每年春天的藻类或浮游植物繁殖期间，它的数量会迅速增长。在初冬出现的最年轻的桡足类（nauplii）和几个月后不可预测的春季浮游植物繁殖期之间的明显不匹配，引发了关于雌性何时繁殖以及这与nauplii的生存和生长有何关系的重要问题。两种类型的休眠，成年雌性的滞育和幼体的生理静止，可能是这一桡足类物种成功的关键。成年雌性产卵的时间和持续时间与从滞育中出现有关。此外，在食物资源匮乏时，nauplii可能会进入生理静止状态，等到浮游植物数量增加后才会恢复生长。这项研究将解决生物海洋学家长期以来的一个目标，即了解海洋桡足类动物的休眠及其在控制种群周期中的作用。它将使用分子生物学中被称为转录组学的新技术来编目细胞用来控制桡足动物生命过程的信息，在这种情况下，这些信息与成虫和幼体的休眠有关。本科生和博士后研究员将接受跨学科研究的培训，夏威夷原住民和阿拉斯加原住民群体的学生将成为参与的目标。渔业是阿拉斯加湾的一项主要产业，推广活动将侧重于宣传桡足类动物在海洋生态系统中的作用。包括图像在内的新内容将为现有网站生成：苏厄德线长期观测项目、阿拉斯加海洋观测系统和阿拉斯加海湾观察项目。新马蹄铁春季种群的招募依赖于成功地从滞育中脱颖而出，然后是下一代的繁殖、生存和生长。以食物、温度和平流为主要环境因子的个体模型在预测类鱿鱼桡足类种群增长方面取得了重大进展。然而，由于采样困难和缺乏生物标志物来评估生理状态，对生命周期的这一部分知之甚少，因此这些模型中很少包括naupliar招募的预测因子。这项研究将利用现有的监测工作，在冬季和早春期间跟踪弗莱明黑貂的种群。研究小组将结合实验室和实地的方法来确定新出现的雌性繁殖的持续时间和同步，以及在低食物条件下的无性系生存策略。浮游动物样本将被处理，以枚举nauplii到物种，并确定nauplii和成年雌性的生理状况。基因表达研究将开发雌性休眠和生殖准备的分子标记，以及单侧生长和可能的休眠，这些标记反过来将用于评估现场收集的个体。这将是第一个将分子和传统工具结合起来的综合研究，将滞育成虫、无尾虫生产和由此产生的春季桡足动物种群联系起来。

The Gulf of Alaska supports a diverse and productive marine community that includes many commercially important fishes. Toward the base of this food web are small planktonic crustaceans that serve as the primary food source for many of these fish, as well as seabirds and marine mammals. The copepod Neocalanus flemingeri is one of these crustaceans, and it experiences rapid population growth during each spring's algal, or phytoplankton, bloom. An apparent mismatch between the presence of the youngest stages of the copepod, or nauplii, in early winter and the unpredictable timing of the spring phytoplankton bloom several months later raises important questions about when females reproduce and how this relates to survival and growth of nauplii. Two types of dormancy, diapause in adult females and physiological quiescence in nauplii, may be the key to the success of this copepod species. Timing and duration of the egg-laying period by adult females is linked to emergence from diapause. In addition, nauplii may enter a state of physiological quiescence while food resources are low, resuming growth after phytoplankton levels increase. This research will address a long-standing goal of biological oceanographers to understand dormancy and its role in controlling population cycles in marine copepods. It will use new technologies in molecular biology called transcriptomics to catalog the messages used by the cells to control copepod life processes, in this case those related to dormancy in adults and nauplii. Undergraduate students and a postdoctoral investigator will be trained in interdisciplinary research, and students from Native Hawaiian and Native Alaskan groups will be targeted for participation. Fishing is a major industry in the Gulf of Alaska, and outreach will focus on communicating the role copepods play in marine ecosystems. New content, including images, will be generated for existing websites: the Seward Line long-term observation program, the Alaska Ocean Observing System and the Gulf Watch Alaska Program. Recruitment to the Neocalanus flemingeri spring population is dependent on successful emergence from diapause followed by reproduction, survival, and growth of the next generation. Individual-based models have made significant progress in predicting population growth in calanoid copepods using food, temperature, and advection as key environmental factors. Few of these models include predictors for naupliar recruitment, however, because little is known about this part of the life cycle given sampling difficulties and the lack of biomarkers to evaluate physiological state. This study will leverage existing monitoring efforts to track the N. flemingeri population during the winter and early spring. The research team will combine laboratory and field approaches to determine duration and synchronization of reproduction in emerging females and strategies for naupliar survival during low food conditions. Zooplankton samples will be processed to enumerate nauplii to species and to determine physiological condition of both nauplii and adult females. Gene expression studies will develop molecular markers for female dormancy and reproductive readiness and for naupliar growth and possible dormancy, which in turn will be used to evaluate field collected individuals. This will be the first comprehensive study to combine molecular and traditional tools to connect diapausing adults, naupliar production, and the resulting spring population of copepodites.