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

点击翻译按钮获取中文摘要

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.