{"596153":{"#nid":"596153","#data":{"type":"event","title":"Does Silicon Limitation Terminate the High-Latitude Atlantic Spring Bloom?","body":[{"value":"\u003Ch4\u003E\u003Cstrong\u003EEAS Fall 2017 Seminar Series Presents: Dr. Jeffrey Krause, University of South Alabama, Department of Marine Sciences\u003C\/strong\u003E\u003C\/h4\u003E\r\n\r\n\u003Cp\u003EDiatoms\u0026rsquo; contribution to productivity and organic matter export are significant in high-latitude marine ecosystems.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EUnlike other abundant phytoplankton groups, diatoms have an obligate silicon requirement; therefore, silicon availability has the potential to regulate major high-latitude events like the spring bloom.\u0026nbsp; Waters in the high-latitude sector of the Atlantic (e.g. coastal Greenland, Faroe Islands, Barents Sea, Svalbard) have lower silicic acid concentrations than nitrate.\u0026nbsp; Given diatoms require Si and N near unity, the deplete Si relative to N sets a potential control on diatom productivity in this system, such that Si could limit diatom biomass yield in a bloom.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ERecent publications have reported declining silicic acid concentrations between ~60 \u0026ndash; 75 \u0026deg;N latitude in the Atlantic.\u0026nbsp; \u0026nbsp;Despite the clear changes in Si availability, there are no reported data for the magnitude of diatom Si uptake and whether ambient silicic acid limits Si uptake or diatom growth.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EHere I report data from the Atlantic sector of the Arctic in the Svalbard archipelago and the sub-Arctic West Greenlandic Nuup Kangerlua fjord.\u0026nbsp; In both systems, we quantified biogenic silica production and the kinetics of Si uptake (to diagnose limitation).\u0026nbsp; In Svalbard, we assessed spatial variability in waters fed by the North Atlantic, glacial fjords and the high-Arctic, whereas in Kangerlua fjord we quantified the development of the spring bloom over two months at a single site influenced by the subpolar mode water, Greenland coastal water and early-season glacial melt water.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIn both systems, the ambient silicic acid chronically limited the rate of Si uptake by diatoms and, at times, may have limited their growth rate.\u0026nbsp; Therefore, we present the first direct evidence that silicon availability plays an important role in the bloom phenology (e.g. termination) of the high-latitude Atlantic.\u0026nbsp;\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"A seminar by Dr. Jeffrey Krause, Earth and Atmospheric Sciences Fall 2017 Seminar Speaker Series"}],"uid":"34458","created_gmt":"2017-09-19 16:25:29","changed_gmt":"2017-10-03 13:32:14","author":"nlawson3","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2017-10-12T12:00:00-04:00","event_time_end":"2017-10-12T12:55:00-04:00","event_time_end_last":"2017-10-12T12:55:00-04:00","gmt_time_start":"2017-10-12 16:00:00","gmt_time_end":"2017-10-12 16:55:00","gmt_time_end_last":"2017-10-12 16:55:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"hg_media":{"596834":{"id":"596834","type":"image","title":"Seminar Jeffrey Krause","body":null,"created":"1507037245","gmt_created":"2017-10-03 13:27:25","changed":"1507037245","gmt_changed":"2017-10-03 13:27:25","alt":"","file":{"fid":"227471","name":"Dr.Jeffrey Krause.jpg","image_path":"\/sites\/default\/files\/images\/Dr.Jeffrey%20Krause.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/Dr.Jeffrey%20Krause.jpg","mime":"image\/jpeg","size":30706,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Dr.Jeffrey%20Krause.jpg?itok=Fi4DcuoC"}}},"media_ids":["596834"],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003Enatasha.lawson@eas.gatech.edu\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}