Collaborative Research: The Chemical Ecology of Shallow-water Marine Macroalgae and Invertebrates on the Antarctic Peninsula

[au:]南极洲帕尔默站附近的底栖海洋生态系统为研究海洋生物化学防御的功能和进化提供了一个极好的场所。南极洲的独特之处在于，海星和其他无脊椎动物是底栖动物的主要捕食者。海星与其他咬人的捕食者有很大的不同，因为它们经常把心胃挤压到猎物身上，以便外部消化。这种进食模式对于化学防御的表面隔离应该是一种特别强的选择性力量，特别是在南极洲，海星是主要的海绵捕食者，而咬海绵动物相对罕见。南极海星是移动缓慢的捕食者，它们长时间以单个海绵为食，并且可能有不均匀的分布。然而，它们比小型食草动物要大得多，这些食草动物被认为在低纬度地区引起化学防御很重要。研究人员先前的研究已经确定了次生代谢物在各种无根和迟钝的南极海洋无脊椎动物和海洋大型藻类中的存在和生态作用。目前的项目集中在两组关于化学防御的功能和演变的问题。首先，对动植物化学防御的最优防御理论和诱导防御模型的预测进行检验。前一种理论预测，在最容易被捕食的组织中，化学防御将以不同的方式被隔离。后一种理论预测，这些捕食者应该选择诱导防御，这些南极捕食者-猎物关系提供了将捕食者大小问题从模型的基本预测中分离出来的机会。其次，研究人员建议利用南极半岛丰富的大型藻群的生态优势成员和南极沿海独特的营养环境来测试棕色大型藻次生代谢物的多种交互作用预测，包括诱导防御模型的预测。另一项试验将检查大气臭氧消耗造成浅水底栖生物群落紫外线辐射增加是否可能影响次生代谢物的产生。由于这些大型藻类在其群落中占主导地位，了解影响其营养关系的因素对于了解整个群落动态非常重要。研究人员计划继续积极寻求和培养机会，将他们的科学研究与各种教育活动相结合，包括支持本科生、研究生和研究生的研究；和科学教师通过国家科学基金会教师体验南极洲项目。

0125152Amsler/Baker/McClintockThe benthic marine ecosystem near Palmer Station, Antarctica provides an excellent site for the study of the function and evolution of chemical defenses in marine organisms. Antarctica is unique in that sea stars and other invertebrates are the major predators on benthic animals. Sea stars are quite different from other, biting predators because they often feed by extruding their cardiac stomach over their prey for external digestion. This feeding pattern should be a particularly strong selective force for surface-sequestration of chemical defenses, especially in Antarctica where sea stars are the major sponge predator and biting spongivores are relatively uncommon. Antarctic sea stars are slow moving predators that feed on individual sponges for long periods of time and can have patchy distributions. However, they are much larger than the small grazers thought to be important in inducing chemical defenses at lower latitudes. Previous studies by the investigators have established the presence and ecological role of secondary metabolites in a wide variety of sessile and sluggish antarctic marine invertebrates and in marine macroalgae. The current project focus on two sets of questions concerning the function and evolution of chemical defenses. First, the predictions of the Optimal Defense Theory and the Induced Defense Model of plant and animal chemical defenses will be tested. The former theory predicts that chemical defenses will be differentially sequestered in tissues that are most susceptible to predation. The latter theory predicts that such predators should select for inducible defenses and these Antarctic predator-prey relationships provide the opportunity to separate the issue of predator size from the basic predictions of the model. Second, the investigators propose to utilize the ecologically dominant members of the Antarctic Peninsula's rich macroalgal flora and the distinctive nutrient environment of coastal Antarctica to test predictions of multiple, interactive roles for secondary metabolites in brown macroalgae including predictions of the Induced Defense Model. An additional test will examine whether increased ultraviolet radiation in shallow water benthic communities caused by atmospheric ozone depletion might be affecting secondary metabolite production. Because of the dominance of these macroalgae in their communities, understanding factors that influence their trophic relationships are important for understanding community dynamics as a whole. The investigators plan to continue to vigorously pursue and foster opportunities to integrate their scientific research with a variety of educational activities, including supporting undergraduate, as well as graduate and postgraduate research; and science teachers through the NSF Teachers Experiencing Antarctica program.