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决定了生态系统。然而，食物和其他资源通常是从外部来源输送到食物网，为接受者生态系统提供补贴。了解这些类型的营养联系和生态系统之间的交换，对于预测食物网如何应对环境或人为变化是必要的。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收群落的生态反应的定量评价，特别是对海洋生态系统。通过调查源生态系统（海带森林）和接收生态系统（沙滩）之间的联系，该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。近岸海带林是一个高产的海洋生态系统，其特点是净初级生产量（NPP）的季节性和年际变化很大。超过90%的海带森林NPP被出口到邻近的生态系统，包括潮间带。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（残骸）来支持复杂多样的食物网。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，并且作为推动沿海经济活力的娱乐和文化资源受到社会的高度重视，但与其他海岸线类型相比，它们很少得到生态研究。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。海滩位于陆地和海洋之间的狭窄边缘，极易受到气候变化的影响，尤其是海平面上升，并将受到气候变化的影响，海带森林也会受到影响。该项目整合了生物和物理方法，以了解出口海带的命运和运输，以及这种资源补贴的可变性如何塑造接受者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，在沿海海洋生态学、公众宣传和教育方面接受科学培训和指导。培训当地居民和海岸管理人员并让他们参与定期对搁浅的海带植物进行的海岸线调查，将是这项研究的一个重要研究组成部分，并提高公众对科学研究、海岸生态以及海带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，可应用于其保护和管理。该项目旨在了解供体生态系统（海带森林）和受体生态系统（沙滩）之间的营养连通性，主要有两个目标：1)评估海带残骸输入的变化如何影响海滩生态系统的模式和过程；2)定量了解海带生物量从海带森林到沙滩的物理运输和输入的营养连通性。该项目将首先在圣巴巴拉海峡、莫霍克礁和10公里长的相邻海岸线上的一片研究充分的海带森林进行为期两年的密集工作，研究小组将在那里测量随时间变化的潮间带群落结构，以响应海带输入的变化。为了评估海带输入的变化对生态系统功能的影响，他们还将测量邻近海滩的潮间带消费者的海带消耗和二次生产速率。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的漂流器跟踪在莫霍克礁标记的海带植物；2)在莫霍克礁给大量的海带植物贴上“漂流卡”（2000年），以便项目团队和训练有素的志愿海滩拾荒者进行回收。然后计算沿海岸线回收的漂流卡和漂流轨迹的结束分布。这些数据将用于根据区域海洋模拟系统（ROMS）的沿海表面流数值模拟建立的海带森林到海滩的海带运输模型。利用该模型在区域内运行的预测海带搁浅率，研究人员将在跨越南加州海岸线100公里的更大海滩上取样群落结构和破坏生物量，以测试研究结果的普遍性。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，将使研究人员能够描述海带补贴投入的时间变化，以及这种变化对接受者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.