Collaborative Research: Quantifying the Effects of Iron and Light on the Growth of Diatoms from the Ross Sea, Antarctica

建议：0739685 PI名称：Sedwick，PeterProposal标题：合作研究：量化铁和光对南极洲罗斯海硅藻生长的影响机构：百慕大海洋科学研究所(BIOS)，Inc.摘要日期：04/08/08智力优势：在南大洋的大部分地区，铁和光照被认为对两个主要浮游藻类--南极棕囊藻和硅藻--水华的时间和位置起着主要控制作用。最近的数值模拟研究模拟了罗斯海南部藻类生物量和物种组成的大范围特征，规定硅藻相对于南极洲生长需要更高的铁，并允许南极洲在低辐射下有更高的生长速度。然而，这些模型中使用的参数有很大的不确定性，特别是关于浮游植物铁的参数，这些参数通常被指定为静态值。最近在殖民地南极洲进行的实验室实验结果表明，该物种对铁的需求可能相对较高，并且似乎随着辐射的变化而强烈变化。在这个项目中，研究人员将利用实验室实验来量化代表罗斯海南部开阔水域、冰缘和海冰环境的硅藻物种的铁需求量，包括纤细海藻、拟次曲线藻、圆柱藻和冰针藻。这些实验数据将被用来检验一系列假说，这些假说涉及铁的可获得性、光照和紫外线照射对生长速度、二甲基磺酸丙酸盐和二甲基硫化物的产生、细胞色素组成以及对大量营养素的相对吸收的影响。此外，研究人员还将进行初步的“藻类竞争实验”，在该实验中，将考察含有硅藻和南极棕囊藻的混合组合的生长情况，作为铁和光照的函数，在有和没有紫外线照射的情况下。该项目还将通过让研究生和本科生直接参与实验室研究，并通过计划的针对K-12学生和普通公众的外联活动，包括在百慕大和南卡罗来纳州的讲座，以及与一组K-12科学教师协商开发网络材料，在几个层面上作出教育贡献。

Proposal:0739685 PI Name:Sedwick, PeterProposal Title: Collaborative Research: Quantifying the Effects of Iron and Light onthe Growth of Diatoms from the Ross Sea, AntarcticaInstitution: Bermuda Institute of Ocean Sciences (BIOS), Inc.Abstract Date: 04/08/08Intellectual merit: In much of the Southern Ocean, iron and irradiance are thought toexert major controls on the timing and location of blooms of the two major phytoplanktongroups, Phaeocystis antarctica and diatoms. Recent numerical modeling studies havesimulated the broad-scale features of algal biomass and species composition in thesouthern Ross Sea, by prescribing a higher iron requirement for the growth of diatomsrelative to P antarctica and by allowing higher growth rates by P. antarctica under lowirradiance. However, there are large uncertainties associated with the parameterizationsused in these models, particularly with regard to phytoplankton iron parameters, whichare typically assigned static values. Results of recent laboratory experiments withcolonial P. antarctica suggest that the iron requirement of this species can be relativelyhigh, and appears to vary strongly as a function of irradiance. In this project, theinvestigators will use laboratory experiments to quantify the iron requirements of diatomspecies that are representative of open-water, ice-edge and sea-ice environments of thesouthern Ross Sea, including Thalassiosira gracilis, Pseudo-nitzschia subcurvata,Fragilariopsis cylindrus and Navicula glaciei. The experimental data will be used to testa number of hypotheses concerning the effects of iron availability, irradiance and UV-Bexposure on growth rates, production of dimethylsulfoniopropionate and dimethylsulfide,cellular pigment composition, and the relative uptake of macronutrients. In addition, theinvestigators will conduct preliminary "algal competition experiments", in which thegrowth of mixed assemblages containing both diatoms and colonial Phaeocystisantarctica will be examined, as a function of iron and irradiance, with and without UV-Bexposure.Broader impacts: The research will provide quantitative information that is required toconstruct robust, mechanistically-accurate numerical models of Southern Oceanecosystems and biogeochemistry. This project also will make educational contributionsat several levels, through the direct involvement of graduate and undergraduatestudents in laboratory research, and through planned outreach activities aimed at K-12students and the general public, including lecture presentations in Bermuda and SouthCarolina, and the development of web materials in consultation with a group of K-12science teachers.