Dynamic Nature of Algal Symbioses: Consequences for Host Fitness in an Intertidal Alga-Anemone Association.

花冠海葵是东北太平洋潮间带群落中含量最丰富的海葵。这种占主导地位的无脊椎动物在这些系统的生态中扮演着重要的角色。由于线虫与两种不同的光合作用藻类具有独特的共生关系，因此它也是帮助我们更好地理解共生伙伴关系以及它们如何应对不断变化的环境的重要模型。这两种藻类在华盛顿州外海岸的线虫种群中的相对丰度将被评估。这将为气候变化提供一个晴雨表；例如，如果温度或光照水平发生变化，这两种共生体的分布和丰度预计将发生变化。这一预测是基于藻类共生体的不同生理耐受性(其中一种更喜欢凉爽、弱光环境，而另一种在温暖、强光环境中表现更好)。在实验室研究中，将通过测量它们对海葵宿主生长和繁殖的影响来测试每种共生体的相对价值。海葵将暴露在不同水平的自然阳光下，有性繁殖、无性分裂和身体生长将受到监测。共生体的健康状况也将通过光合作用生产力和分裂速率来衡量。这项工作的结果将为研究一种重要而丰富的潮间带物种的生态提供有价值的见解。结果对于开发可检验的假说也将是重要的，这些假说是关于具有多个共生伙伴的其他长寿物种(例如地衣和珊瑚)将如何受到与气候变化相关的共生体补体变化的影响。该项目将参与共生研究14名本科生和2名研究生，包括在科学界代表性不足的群体成员。该项目的内容将被纳入现有的本科课程和一项小学推广计划，并通过公开讲座进行传播。

Anthopleura elegantissima is the most abundant sea anemone in intertidal communities of the northeast Pacific Ocean. This dominant invertebrate plays an important role in the ecology of these systems. Because of the unique symbiotic relationship A. elegantissima has with two distinct photosynthetic algae, it is also important as a model to help us better understand symbiotic partnerships and how they respond to a changing environment. The relative abundance of the two algae in A. elegantissima populations along the outer coast of Washington State will be assessed. This will provide a barometer for climate change; the distributions and abundances of the two symbiont species are predicted to shift if, for example, temperature or light levels change. This prediction is based on the different physiological tolerances of the algal symbionts (one prefers cooler, low-light environments while the other does better in warmer, high-light environments). In laboratory studies, the relative value of each symbiont will be tested by measuring their impact on growth and reproduction of the anemone host. Anemones will be exposed to different levels of natural sunlight, and sexual reproduction, asexual division, and body growth will be monitored. Health of the symbionts will also be measured in terms of photosynthetic productivity and division rate. Results of the work will provide valuable insights into the ecology of an important and abundant intertidal species. Results will also be important for developing testable hypotheses about how other long-lived species with multiple symbiotic partners (e.g., lichens and corals) will be affected by climate change-related shifts in symbiont complements. This project will engage in symbiosis research 14 undergraduate and 2 graduate students, including members of groups underrepresented in science. Elements of the project will be incorporated into existing undergraduate courses and an elementary school outreach program, and also disseminated through public lectures.