Award: OCE-1061876

Every spring in surface waters of theNortheast Atlantic Ocean, south of Iceland, a massive bloom of the unicellular coccolithophorid algae, Emiliania huxleyi can be seen from space using satellites. This algal bloom is an important component of the global carbon cycle since it removes carbon dioxide from the surface ocean waters due to both photosynthesis and calcification processes. Algal carbon fixed by these processes is then available for transport to the deep ocean. This export of carbon to the deep ocean allows more atmospheric carbon dioxide to move into surface waters of the ocean and thereby influence climate. Because of the impact of the carbon cycle on climate it is important to understand the factors that increase the growth rate, calcification rate and death of this organism. Our specific goal on this project was to identify and quantify the impact of viral infection on the physiology and ecology of Emiliania huxleyi during the spring and summer bloom period. A major field expedition entitled "North Atlantic Virus Infection of Coccolithophores Expedition (NA-VICE)" was completed in June/July 2012. Our science team boarded the RV Knorr at Ponta Delgado in the Azores on June 15, 2012 and then spent approximately 30 days collecting data and performing oceanographic experiments to study the importance of viruses on the carbon and sulfur cycles in Emiliania huxleyi. Our specific objectives on the research cruise included measuring the community composition of algae in the water column, determining their growth and death rates and isolating various cells to make biochemical measurements of carbon and sulfur compounds that are important with respect to climate change. We determined using pigment analyses and microscopy that Emiliania huxleyi cells were the dominant algal population in surface waters. We measured doubling times of Emiliania huxleyi of approximately once per day and loss rates due to either predator grazing and/or by viral lysis of approximately one half that value. We measured photosynthetic and calcification rates as well as the amount of organic and inorganic carbon at various depths in the bloom areas. One major goal of our project was to determine the concentration of the climatically active trace gas, dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) within the algal cells. DMS in the atmosphere is oxidized tosulfate and ultimately is involved in cloud formation. Hence production of DMSP and DMS by marine coccolithophorids can influence the EarthÆs heat budget since clouds are important in reflecting sunlight away from the Earth's surface. We isolated both healthy and virally infected coccolithophorid cells using a high speed flow cytometer at sea to determine the intracellular DMSP concentrations. Infected cells had significantly lower DMSP cell concentrations compared to healthy uninfected cells. Hence, it is possible that virally infected cells will contribute less DMS to the atmosphere compared to a healthy growing bloom. The College of Charleston participants on the NA-VICE field expedition included one graduate (Jacob Kendrick) and one undergraduate student (Rachel Stevens). This expedition was the first research oceanographic experience for Ms. Rachel Stevens. Ms. Stevens performed the dilution experiments at sea to estimate growth and grazing rates and those data were used as part of her Bachelors Honors Thesis at the College of Charleston. Intracellular DMSP levels in virally infected and healthy Emiliania huxleyi populations served as part of the data leading to the completion of Mr. Jacob KendrickÆs MasterÆs Thesis in Marine Biology at the College of Charleston. Blogs from the cruise were posted and can be found online and educational videos are currently being finalized at Rutgers University to disseminate the results of our expedition to the general public. Last Modified: 06/25/2014 Submitted by: Giacomo R Ditullio