Katrin Schmidt, British Antarctic Survey, NERC, Cambridge, UK holder foredraget "Iron-fertilisation by Antarctic krill enhances the South Georgia mega bloom" i Kaffeklubben på DTU Aqua. Gæster er velkomne.
Resume
The micronutrient iron limits primary productivity over large parts of the world ocean, with the local inventory depending on new physical supply and chemical and biological recycling processes. While microbes are key agents in biogenic turnover and nutrient regeneration, large grazers have been associated with accumulation of biomass and nutrient export via fecal pellets. Here we show that Antarctic krill can recycle similar amounts of dissolved iron to microbes (0.3-33 pM d-1) and that this leads to enhanced phytoplankton biomass downstream of the island of South Georgia. Processes involved are, first, krill’s ability to feed efficiently on large diatoms with subsequent release of dissolved iron (5 nmol DFe krill-1 d-1) and second, their ingestion of glacial flour, which lifts adsorbed non-bioavailable iron into the food web either via their body tissue or their fecal pellets. While phytoplankton abundance in the main krill habitat on the South Georgia shelf is controlled by grazing, fertilising effects override in a large (200 x 200 km) area downstream. Here, bloom duration increases from 16 to 19 weeks and average chl a concentration from 0.8 to 1.0 μg L-1 in years with high krill abundance. The South Georgia phytoplankton bloom provides the largest carbon uptake in the Antarctic Circumpolar Current and Antarctic krill play a crucial role in the dynamic of this bloom.
Om Kaffeklubben
DTU Aquas såkaldte Kaffeklub arrangerer foredrag om akvatisk forskning som en del af den faglige videndeling på instituttet.
Foredragene holdes både af DTU Aquas egne forskere og forskere fra andre danske eller udenlandske forskningsinstitutioner. Tilhørerne er hovedsageligt ansatte i DTU Aqua, men andre interesserede er også velkomne til at deltage. Tilmelding er ikke nødvendig.
Foredragene er på engelsk og varer 1 time, inklusive spørgsmål og diskussion. De afholdes i uformelle rammer på DTU Aqua i Charlottenlund.