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

中栖食草动物，特别是两足类，是南极洲大型藻类群落中显著和占主导地位的组成部分。尽管它们的丰度很高，但人们对南极两足类的功能生态，特别是营养关系知之甚少。该项目将评估中掠食者(体长约为1至25毫米的小型无脊椎动物捕食者)在南极半岛西部海洋生物群落中的重要性。这将通过研究中草动物在构建大型藻类群落中的作用以及阐明中食性动物与大型底栖无脊椎动物的主要群体--海洋海绵--的生态相互作用来实现。此外，将进行化学研究，以更彻底地了解南极半岛海绵对甲壳类中划虫的化学防御。将讨论三组问题，涉及南极半岛西部近岸生境中的中栖动物，特别是两足类动物的重要性。首先，将提出这样的假设，即中草性在南极半岛西部海洋群落中特别严重，并对藻类群落结构有重要影响。初步研究将记录哪些种类的两足类动物全部或部分以微藻和大型藻类为食，丝状内生真菌在优势大型藻类中的发生率和分布，大型植物上双足类丰度的比较夜间模式，以及化学中介在这些关系中的作用。第二，广泛的假设，即一般的中食动物，特别是两足类，与海绵的相互作用和捕食程度比迄今在南极群落中认识到的更大，这一假设将受到考验。这些联系的功能基础将通过检查海绵是否被用作猎物来考虑，如果是，是否有证据表明一些海绵产生次生代谢物，显示出对角足类等中食动物的有效性。第三，研究人员将测试假设：1)南极藻类和无脊椎动物生物合成次生代谢产物，阻止端足类捕食者觅食；2)在三种南极海绵中发现的色素是色氨酸分解代谢产物，用于防御影响蜕皮的甲壳类捕食者。对这些假说的评估将基于特定拒食代谢物的分离和表征，基于生物合成研究以确定色素的代谢来源，以及基于生物测试以确定两组化合物的化学防御作用。各种教育活动将是这一项目的主要组成部分。将有机会支持研究生和本科生的研究，既包括NSF项目，也包括基于国内大学的项目，包括一些资助的项目，以增强少数族裔在科学界的代表性。通过他们经过验证和非常成功的互动网络计划，调查人员将继续让大量教师、K-12学生和其他社区成员参与他们在南极洲的科学努力。此外，他们将积极参与外展工作，向学校和社区团体介绍他们的研究成果。

Mesoherbivores, and specifically amphipods, are a conspicuous and dominant component of the macroalgal community in Antarctica. Despite their high abundance, the functional ecology, and particularly the trophic relationships of Antarctic amphipods are poorly understood. This project will evaluate the importance of mesograzers (small invertebrate predators approximately 1 to 25 mm in body length) in western Antarctic Peninsula marine communities. This will be accomplished by examining the role of mesoherbivores in structuring macroalgal communities and by elucidating the ecological interactions of mesograzers with a dominant group of benthic macroinvertebrates, the marine sponges. Moreover, chemical studies will be conducted to gain a more thorough understanding of the chemical defenses that Antarctic Peninsula sponges direct towards crustacean mesograzers. Three sets of questions will be addressed concerning the importance of mesograzers, and amphipods in particular, in nearshore habitats of the western Antarctic Peninsula. First, the hypothesis that mesoherbivory is particularly heavy in western Antarctic Peninsula marine communities and has an important influence on algal community structure will be addressed. Initial studies will document which species of amphipods feed in whole or part on microalgae and macroalgae, the incidence and distribution of filamentous endophytes in dominant macroalgae, comparative night time patterns of amphipod abundances on macrophytes, and the role of chemical mediation in these relationships. Second, the broad hypothesis that mesograzers in general, and amphipods in particular, interact with and prey upon sponges to a greater extent than heretofore recognized in Antarctic communities will be tested. The functional basis of these associations will be considered by examining whether the sponges are used as prey, and if so, whether there is evidence that some sponges produce secondary metabolites that show efficacy against mesograzers such as amphipods. Third, the researchers will test the hypotheses that: 1) Antarctic algae and invertebrates biosynthesize secondary metabolites that deter feeding by amphipod predators; and 2) pigments found in three Antarctic sponges are tryptophan catabolites produced as defenses against crustacean predators that impact molting. Evaluation of these hypotheses will be based on isolation and characterization of the specific anti-feeding metabolites, on biosynthetic studies to establish the metabolic origin of the pigments, and on bioassays to establish the chemical defense roles of both groups of compounds. A variety of educational activities will be a major component of this project. Opportunities will be made to support graduate and undergraduate research, both through NSF programs as well as home university-based programs including a number of funded programs that enhance the representation of minorities in the sciences. Through their proven and highly successful interactive web program, the investigators will continue to involve a large numbers of teachers, K-12 students, and other members of the community at large in their scientific endeavors in Antarctica. Moreover, they will actively participate in outreach efforts by presenting numerous talks on their research to school and community groups.