Molecular Assessment of Salp Gut Content - an improved method to determine phytoplankton biodiversity in the Southern Ocean?

浮游生物群落结构对气候变化的响应和物种的气候敏感性是当前海洋生态学的热门话题。预计气候相关的环境变化会导致浮游生物物种的丰度、空间分布、生物地理或优势度的变化。这将强烈影响生物地球化学循环，以及海洋食物网，直到鱼类或鸟类等顶级捕食者。浮游植物是海洋食物网的基础，它由微型、纳米和微型浮游生物的细胞组成。为了评价气候变化对南极海洋生态系统的影响，有必要掌握关于海洋浮游植物的丰度、生物多样性或群落结构的全面资料。采用自动核糖体RNA基因间间隔分析（ARISA）、PHYLOCHHIP -分析和18S rDNA克隆文库测序技术，对拉扎雷夫海不同季节的南大洋Salpa thompsoni和Ihlea racovitzai两种海鞘的肠道内容进行分析，探讨浮游植物的季节性和空间变异性。Salpa thompsoni和Ihlea racovitzai在同一站点的共同出现将被用来检验假说，即Salpa内脏确实提供了整个水柱浮游植物多样性的综合信号。对浮游生物多样性的详细研究将进一步深入了解南大洋，特别是在浮游植物稀少的冬季，海鞘的饮食。

Changes in plankton community structures in response to climate change and the climatic sensitivity of species are currently driving topics in marine ecology. It is expected that climate related environmental change could result in changes in the abundance, spatial distribution, biogeography or dominance of plankton species. This would strongly influence biogeochemical cycling, and also marine food-webs up to top predators like fish or birds. Phytoplankton is the base of marine food webs, it consist of cells from the pico-, nano-, and microplankton. In order to evaluate consequences of climate change for marine ecosystems in the Antarctic, it is necessary to possess comprehensive information on the abundance, biodiversity or community structure of marine phytoplankton. By applying Automated ribosomal RNA intergenic spacer analysis (ARISA), PHYLOCHHIP – analysis and sequencing of 18S rDNA clone librarieson on the gut content of two Southern Ocean salps, Salpa thompsoni and Ihlea racovitzai from various season of the Lazarev sea, we will investigate the seasonality and spatial variablility of phytoplankton. The co-occurrence of Salpa thompsoni and Ihlea racovitzai on the same stations will be used to test the hypothesis, that salp guts truly give an integrated signal of phytoplankton diversity over the entire water column. Detailed studies of the plankton diversity will give further insights in the diet of salps in the Southern Ocean, particular during winter time, when phytoplankton is scare.