Collaborative Research: From Latrines to Landscapes: Effects of Temporal and Spatial Variation in Nutrient Transport by Coastal River Otters on Terrestrial Communities

摘要我们不能再把生态系统看作是不同的实体。就像人类社会一样，自然环境通过广泛的运输和通信过程联系在一起。生态系统之间的能量和物质运动可以改变食物网的相互作用和养分循环，并影响植物、动物和其他生物的数量和多样性。然而，这些运输过程的中断可能会中断生态系统的连通性。为了理解复杂的生态过程，我们必须探索这些现象的时空变化（生态拓扑）。例如，我们需要问自然群落如何随着时间的推移对能量和养分输入的变化做出反应。沿海河獭（Lontra canadensis）通过在海洋环境中觅食和在厕所地点进行气味标记，将营养物质从海洋运输到陆地。水獭的这种社会交流创造了“热点”，海洋碳(C)、氮(N)和磷(P)在沿海沉积。水獭的社会性很大程度上是由合作觅食鱼群的好处所驱动的，比如鲑鱼（Oncorhynchus spp.）和鲱鱼（Clupea pallasi）。因此，由于全球变暖、污染或收获，这些鱼类的丰度和分布发生任何变化，都可能改变营养物质向水獭厕所的运输。通过水獭活动将海洋和陆地系统联系起来，为探索海洋养分输入对陆地植物和土壤生物的时空变化影响提供了一个很好的模型系统。利用稳定同位素分析和遗传标记，我们将测量水獭在营养物质运输方面的变化。然后，我们将探讨水獭施肥变化对土壤微生物群落多样性、养分循环、植物对海洋养分的吸收、植物多样性、植物生长、开花和结果率的影响。利用在树木年轮中测量的同位素，我们还将评估“热点”沿海岸移动的时间尺度。在建立这些关系之后，我们将开发一个模型，该模型将模拟基于鱼群分布、水獭活动和水獭运输碳、氮和磷的变化对陆地景观的潜在变化。

AbstractWe can no longer think of ecosystems as distinct entities. Much like human societies, the natural environment is connected through a wide range of transport and communication processes. Movement of energy and matter between ecosystems can modify food web interactions and nutrient cycling, as well as affect the number and diversity of plants, animals, and other organisms. Connectivity of ecosystems may be interrupted, however, by disruption in these transport processes through time. In our quest to understand complex ecological processes, we must explore the spatial and temporal variation (ecological topology) of such phenomena. For example, we need to ask how natural communities respond to changes in inputs of energy and nutrients through time. Coastal river otters (Lontra canadensis) transport nutrients from sea to land by feeding in the marine environment and scent-marking at latrine sites. This social communication of river otters creates "hotspots" where marine carbon (C), nitrogen (N), and phosphorus (P) are deposited along the coast. Sociality in otters is driven largely by the benefits of cooperative foraging on schooling fishes, such as salmon (Oncorhynchus spp.) and herring (Clupea pallasi). Therefore, any changes in the abundance and distribution of these fishes through global warming, pollution, or harvest, could change the transport of nutrients to otter latrines. This linking of marine and terrestrial systems through otter activity provides an excellent model system to explore the effects of spatial and temporal variation in inputs of marine nutrients on terrestrial plants and soil organisms. Using stable isotope analyses and genetic markers we will measure the variation in nutrient transport by river otters. We will then explore the effects of variation in otter fertilization on the diversity of the soil microbial community, nutrient cycling, plant uptake of marine nutrients, diversity of plants, plant growth, flowering and fruiting rates. Using isotopes measured in tree rings, we will also evaluate the time scale in which "hotspots" shift along the coast. After establishing these relations, we will develop a model that will simulate potential changes to the terrestrial landscape based on changing distributions of schooling fish, otter activity, and C, N, and P transport by river otters.