Linking nearshore kelp forest dynamics to sandy beach ecosystems

初级生产者，如植物和藻类，构成了大多数食物网的基础，它们的生产力和命运从根本上塑造了生态系统。然而，食物和其他资源往往是从外部来源提供给食物网的，为接受者的生态系统提供补贴。了解这些类型的生态系统之间的营养连接和交换对于预测食物网可能如何应对变化是必要的，无论是环境变化还是人为变化。尽管它们具有潜在的重要性，但缺乏对跨生态系统物质通量、这些通量在时间和空间上的变化以及接受者社区的生态反应的定量评估，特别是对于海洋生态系统。通过研究来源生态系统海藻森林和接受生态系统沙滩之间的联系，这个项目将扩大和改变我们对沿海海洋跨生态系统通量的理解。近岸海藻林是生产力很高的海洋生态系统，其特点是净初级生产量的季节和年际变化很大。超过90%的海带森林NPP出口到包括潮间带在内的邻近生态系统。由于缺乏附着的植物和藻类，海带森林附近的沙滩生态系统严重依赖进口的漂流海带(WRACK)来支持复杂和多样化的食物网。尽管沙滩是美国所有海岸的主要海岸线类型，为包括濒危物种在内的野生动物提供栖息地和猎物，并被社会高度重视为推动充满活力的沿海经济的娱乐和文化资源，但与其他海岸线类型相比，它们得到的生态学研究很少。这种知识的缺乏阻碍了作为生态系统的海滩的保护和管理。海滩坐落在陆地和海洋之间的狭窄边缘，非常容易受到气候变化，特别是海平面上升的影响，并将受到气候变化的影响，海藻森林也是如此。该项目综合了生物学和物理方法，以了解出口海藻的命运和运输，以及这种资源补贴的可变性如何影响受援国海滩生态系统的群落结构和功能。研究生和本科生将成为研究团队不可或缺的成员，接受沿海海洋生态以及公共宣传和教育方面的科学培训和指导。对当地居民和沿海管理人员进行培训，并让他们参与对海滩海藻植物的定期海岸线调查，这将是这项研究的重要研究内容，并将提高公众对科学研究、沿海生态以及海藻森林与海滩生态系统之间联系的作用的认识。该项目的结果将为沿海海洋生态系统之间的连通性动态提供新的见解，可用于其保护和管理。该项目试图了解供体生态系统海藻森林和受助生态系统沙滩之间的营养连通性，主要目标有两个：1)评估海带海藻输入的变化如何影响海滩生态系统的模式和过程；2)通过海带森林到沙滩的漂流海带生物量的物理输送和输入，定量了解营养连通性。该项目将首先在莫霍克礁圣巴巴拉海峡和邻近10公里海岸线上的一个经过充分研究的海藻森林进行为期两年的密集工作，研究小组将在那里测量潮间带群落结构随时间的变化，以应对海藻输入的变化。为了评估鱼类投入量的变化对生态系统功能的影响，他们还将测量邻近海滩上潮间带消费者的海藻消耗量和次生生产量。他们将使用免费的方法直接观察海带的命运和运输：1)使用带有GPS的漂移器跟踪在莫霍克礁标记的海带植物；以及2)在莫霍克礁用漂移卡标记大量的海带植物(2000)，由项目组和训练有素的志愿者海滩搜索员进行恢复。然后将计算沿海岸线恢复的漂移卡和漂流道的结束分布。这些数据将用于根据区域海洋模拟系统(ROMS)对沿海表层流的数值模拟建立海藻从森林到海滩的运输模型并加以验证。使用这一区域运行的模型预测的海藻搁浅速度，研究人员随后将在南加州海岸线100公里的更大一组海滩上采样群落结构和珊瑚生物量，以测试研究结果的一般性。这种命运和运输观测、海滩群落调查和过程测量以及建模的结合，将使调查人员能够表征海藻补贴投入的时间变异性，以及这种变异性对受援海滩生态系统的群落结构和功能的影响。

Primary producers, such as plants and algae, form the basis of most food webs and their productivity and fate fundamentally shape ecosystems. Often, however, food and other resources are delivered to a food web from an outside source, providing a subsidy to the recipient ecosystem. Understanding these types of trophic connections and exchanges between ecosystems is necessary for predicting how food webs may respond to change, whether environmental or anthropogenic. Despite their potential importance, quantitative evaluations of cross-ecosystem material fluxes, variation of these fluxes in time and space, and ecological responses of recipient communities are lacking, particularly for marine ecosystems. By investigating links between a source ecosystem, kelp forests, and a recipient ecosystem, sandy beaches, this project will expand and transform our understanding of cross-ecosystem fluxes in the coastal ocean. Nearshore kelp forests are highly productive marine ecosystems characterized by large seasonal and interannual variations in net primary production (NPP). More than 90% of kelp forest NPP is exported to adjacent ecosystems including the intertidal zone. Lacking attached plants and algae, sandy beach ecosystems near kelp forests depend heavily on imported drift kelp (wrack) to support complex and diverse food webs. Although sandy beaches are a dominant shoreline type along all U.S. coasts, provide habitat and prey for wildlife, including endangered species, and are highly valued by society as recreational and cultural resources that drive vibrant coastal economies, they receive little ecological study compared to other shoreline types. This lack of knowledge hinders the conservation and management of beaches as ecosystems. Perched on the narrow rim between land and sea, beaches are highly vulnerable to climate change, particularly sea level rise, and will be impacted by changes in climate, as will kelp forests. This project integrates biological and physical approaches to achieve an understanding of the fate and transport of exported kelp, and how variability in this resource subsidy shapes the community structure and function of recipient beach ecosystems. Graduate and undergraduate students will be integral members of the research team, receiving scientific training and mentoring in coastal marine ecology and in public outreach and education. The training and participation of local residents and coastal managers in regular shoreline surveys for beached kelp plants will provide an essential research component of the study and enhance public awareness of scientific research, coastal ecology and the role of links between kelp forest and beach ecosystems. The results of this project will provide new insights into the dynamics of connectivity between coastal marine ecosystems that can be applied to their conservation and management.The project seeks to understand trophic connectivity between a donor ecosystem, kelp forests, and a recipient ecosystem, sandy beaches, with two primary goals: 1) an evaluation of how variation in kelp wrack input affects patterns and processes in beach ecosystems and 2) a quantitative understanding of trophic connectivity through physical transport and input of drift kelp biomass from kelp forests to sandy beaches. The project will begin with two years of intensive work at a well-studied kelp forest in the Santa Barbara Channel, Mohawk Reef, and along 10 km of adjacent coastline, where the research team will measure intertidal community structure over time in response to variability in kelp inputs. To assess effects of variation in wrack input on ecosystem function, they will also measure kelp consumption and secondary production rates of intertidal consumers on adjacent beaches. They will directly observe fate and transport of kelp using complimentary approaches: 1) tracking kelp plants tagged at Mohawk Reef using drifters with GPS; and 2) tagging large numbers of kelp plants (2000) with "drift cards" at Mohawk Reef for recovery by the project team and trained volunteer beachcombers. Ending distributions of recovered drift cards and drifter tracks along the shoreline will then be computed. These data will be used to inform and validate a kelp forest-to-beach kelp transport model based on numerical simulations of coastal surface currents from the Regional Oceanic Modeling System (ROMS). Using predicted kelp beaching rates from this model run regionally, the investigators will then sample community structure and wrack biomass at a larger set of beaches spanning 100 km of the southern California shoreline to test the generality of research findings. This combination of fate and transport observations, beach community surveys and process measurements, and modeling will allow the investigators to characterize temporal variability in kelp subsidy inputs and the consequences of this variability for community structure and function of recipient beach ecosystems.