Collaborative Research: Do Crustacean Zooplankton Play a Pivotal Role in Structuring Heterotrophic Plankton Communities?

最近对海洋生态系统的研究表明，营养级联的证据相互矛盾，特别是甲壳类动物浮游植物联系的相对强度。罗斯海是调查这场明显冲突的天然实验室。这是一个季节性高丰度的浮游植物，其特点是不同的浮游植物类群的地区;中南部的冰间湖是强烈占主导地位的殖民地形成prymnesiophyte的Phaeocystis ananaitica，而沿海地区的这片海通常是由硅藻或鞭毛虫物种占主导地位。最近的研究表明，虽然中南部的冰间藻显示出大量的浮游植物水华，但对许多甲壳类浮游动物来说，南极冰间藻的食物质量很差，使许多浮游植物水华无法直接利用。相反，有证据表明，这种生产的间接利用可能是碳和能量可用于这些较高营养级的主要机制。具体而言，我们假设，纳米和微型浮游动物构成了一个重要的食物来源，甲壳类浮游动物（主要是桡足类和少年磷虾）在夏季期间在罗斯海的浮游植物组合是由prymnesiophyte为主。反过来，我们还假设，桡足类（和其他甲壳类）的捕食控制和结构的物种组成，这些原生生物组合。我们将占领站在中南部的罗斯海Polynya（RSP）和特拉诺瓦湾（TNB）在南部的夏天，以测试这些假设。我们假设，占主导地位的浮游植物组合在TNB的硅藻物种构成的直接营养源，以草食性/杂食性浮游动物（相对于在中南部的RSP的情况）。也就是说，异养原生生物对甲壳类食物的贡献将在TNB中减少。 我们的研究将解决我们的食物网结构和营养级联知识的根本差距，并提供更好地了解这个常年寒冷的海洋生物群落内的碳和能量流动。PI将通过课程开发（南极生物学）和海洋科学教育卓越中心（COSEE-West）的教师培训活动在公共教育（K-12）中发挥积极作用，这是一个以南加州大学和加州大学洛杉矶分校为中心的创新，NSF资助的项目。

Recent studies of marine ecosystems show conflicting evidence for trophic cascades, and in particular the relative strength of the crustacean zooplankton-phytoplankton link. The Ross Sea is a natural laboratory for investigating this apparent conflict. It is a site of seasonally high abundances of phytoplankton, characterized by regions of distinct phytoplankton taxa; the southcentral polynya is strongly dominated by the colony-forming prymnesiophyte Phaeocystis antarctica, while coastal regions of this sea are typically dominated by diatoms or flagellate species. Recent studies indicate that, while the south-central polynya exhibits a massive phytoplankton bloom, the poor food quality of P. antarctica for many crustacean zooplankton prevents direct utilization of much of this phytoplankton bloom. Rather, evidence suggests that indirect utilization of this production may be the primary mechanism by which carbon and energy become available to those higher trophic levels. Specifically, we hypothesize that nano and microzooplankton constitute an important food source for crustacean zooplankton (largely copepods and juvenile euphausiids) during the summer period in the Ross Sea where the phytoplankton assemblage is dominated by the prymnesiophyte. In turn, we also hypothesize that predation by copepods (and other Crustacea) controls and structures the species composition of these protistan assemblages. We will occupy stations in the south-central Ross Sea Polynya (RSP) and Terra Nova Bay (TNB) during austral summer to test these hypotheses. We hypothesize that the diatom species that dominate the phytoplankton assemblage in TNB constitute a direct source of nutrition to herbivorous/omnivorous zooplankton (relative to the situation in the south-central RSP). That is, the contribution of heterotrophic protists to crustacean diets will be reduced in TNB. Our research will address fundamental gaps in our knowledge of food web structure and trophic cascades, and provide better understanding of the flow of carbon and energy within the biological community of this perennially cold sea. The PIs will play active roles in public education (K-12) via curriculum development (on Antarctic biology) and teacher trainer activities in the Centers for Ocean Science Education Excellence (COSEE-West), an innovative, NSF-funded program centered at USC and UCLA.