Collaborative Research: Kelp forest interaction webs in the Aleutian Archipelago: patterns and mechanism of change following the collapse of an apex predator.

过去35年对海獭和海带森林生态系统的研究提供了大型脊椎动物捕食者自上而下强迫的一个比较著名的例子。这些研究表明，1)海獭通过限制草食性海胆间接维持海带森林，2)这种营养级联对许多其他物种和生态系统过程具有强烈的间接影响。这些见解主要是通过对阿留申群岛上有海獭和没有海獭的岛屿进行比较获得的，这是太平洋海上毛皮贸易导致海獭大量灭绝后，海獭数量在空间上不同步恢复所创造的机会。在超过35年的研究过程中，这些研究人员获得了大量关于海獭种群、海带森林群落和一系列相关海洋野生动物的数据，这些数据来自众多有或没有海獭的阿留申群岛。从那以后，海獭的数量急剧减少，整个地区的海獭已经在生态上灭绝了。在这项研究中，dr。科纳尔、爱德华兹和埃斯蒂斯将把多年代际数据库与这次灭绝事件结合起来，记录海胆和肉质大型藻类（海带和其他物种）分布和丰度的时空变化模式和机制。为此，他们将重新访问20个拥有长期数据的岛屿，并重新调查历史上的海带森林监测点，以了解海胆的丰度和种群结构，以及海带和其他肉质大型藻类的丰度和种类组成。综合起来，这些数据将说明随着海獭在阿留申群岛的减少，海獭-海胆海带营养级联的变化程度。现有信息表明，海獭数量减少后，海带森林迅速消失，海胆从深海向上迁移，而不是原地补充和生长，促进了这种快速转变。这组海洋科学家将通过测量从浅水和深水中收集的海胆刺沿着生长增量的各种温度和营养敏感同位素模式来验证这一想法。与海胆的深度避难所类似，来自其他地区的研究表明，大型藻类可能在浅水或非常密集的藻类群落中有一个空间避难所，以避免海胆放牧。他们将利用在海带森林监测点重新普查期间收集的数据，并将调查范围扩大到较浅的水域和孤立的海带床，探索大型藻类的空间避难所。本研究是一个严谨探索和记录大型脊椎动物捕食者对其相关生态系统相互作用网络动态影响的机会。该项目的智力优势在于强调海洋岛屿和北极的特殊性，以研究近岸生态系统结构和过程。该项目的更广泛影响包括对社会、教学和培训的好处。该项目将非常具有新闻价值，因为它将描述一种迅速减少的海洋哺乳动物的现状，并将记录由于过去20多年来该物种丰度的波动而发生的变化。将为来自三所不同大学的研究生提供培训和教育机会。该项目将涉及阿拉斯加费尔班克斯大学、加州大学圣克鲁斯分校和圣地亚哥州立大学。

Research on sea otters and kelp forest ecosystems conducted over the past 35 years provides one of the better known examples of top-down forcing by a large vertebrate predator. These studies have shown that 1) sea otters indirectly maintain kelp forests by limiting herbivorous sea urchins, and 2) this trophic cascade has strong indirect effects on a number of other species and ecosystem processes. These insights were obtained largely through the comparison of islands in the Aleutian archipelago with and without sea otters, an opportunity created by the spatially asynchronous population recovery of sea otters following their decimation by the Pacific maritime fur trade. In the course of more than 35 years of studies, these researchers have obtained an extensive amount of data on sea otter populations, kelp forest communities, and an array of associated marine wildlife from numerous Aleutian Islands with and without sea otters. Sea otter populations have since collapsed and the species is now ecologically extinct across the entire region. In this study, Drs. Konar, Edwards and Estes will combine the multi-decadal database with this extinction event to chronicle the patterns and mechanisms of spatial and temporal change in distributions and abundances of sea urchins and fleshy macroalgae (kelps and other species). They will do this by revisiting 20 islands for which they have long-term data and re-censusing the historical kelp forest monitoring sites for the abundance and population structure of sea urchins, and for the abundance and species composition of kelps and other fleshy macroalgae. In combination, these data will provide an account of the degree to which the otter-urchin kelp trophic cascade has changed with the collapse of sea otters across the Aleutian archipelago.The available information indicates that kelp forests collapsed very rapidly following the sea otter decline, and that this rapid shift was facilitated by the upward migration of sea urchins from deep water as opposed to in situ recruitment and growth. This group of marine scientists will test this idea by measuring various temperature- and nutrient sensitive isotopic patterns along the growth increment of sea urchin spines of animals collected from shallow and deep water. Similar to a depth refuge for urchins, studies from other areas have suggested that macroalgae may have a spatial refuge from urchin grazing in shallow waters or amongst very dense algal stands. They will explore macroalgal spatial refuges by using data collected during the re-censusing of the kelp forest monitoring sites and by extending our surveys to shallower waters and isolated kelp beds.This research is an opportunity to rigorously explore and document the influences of a large vertebrate predator on the interaction web dynamics of its associated ecosystem. The intellectual merit of this project emphasizes the special character of oceanic islands and the Arctic for the study of near-shore ecosystem structure and processes.Broader impacts of this project include benefits to society, teaching, and training. The project will be very newsworthy because it will describe the current status of a rapidly declining marine mammal and will document changes that have occurred due to fluctuations in the abundance of this species over the last 20+ years. Training and educational opportunities will be offered to graduate students from three different universities. The project will involve the University of Alaska Fairbanks, University of California Santa Cruz, and San Diego State University.