Krill Excretion Boosts Microbial Activity in the Southern Ocean Arístegui, Javier Duarte Quesada, Carlos Manuel Reche Cañabate, Isabel Gómez-Pinchetti, Juan L. Antartic Ocean Antarctica Bacterial growth Excretion Grazing Marine bacteria Phytoplankton Sea water Antarctic krill are known to release large amounts of inorganic and organic nutrients to the water column. Here we test the role of krill excretion of dissolved products in stimulating heterotrophic bacteria on the basis of three experiments where ammonium and organic excretory products released by krill were added to bacterial assemblages, free of grazers. Our results demonstrate that the addition of krill excretion products (but not of ammonium alone), at levels expected in krill swarms, greatly stimulates bacteria resulting in an order-of-magnitude increase in growth and production. Furthermore, they suggest that bacterial growth rate in the Southern Ocean is suppressed well below their potential by resource limitation. Enhanced bacterial activity in the presence of krill, which are major sources of DOC in the Southern Ocean, would further increase recycling processes associated with krill activity, resulting in highly efficient krill-bacterial recycling that should be conducive to stimulating periods of high primary productivity in the Southern Ocean. 2014-03-27T13:51:12Z 2014-03-27T13:51:12Z 2014 journal article Arístegui, J.; Duarte, C.M.; Reche, I.; Gómez-Pinchetti, J.L. Krill Excretion Boosts Microbial Activity in the Southern Ocean. Plos One, 9(2): e89391 (2014). [http://hdl.handle.net/10481/31141] 1932-6203 doi: 10.1371/journal.pone.0089391 http://hdl.handle.net/10481/31141 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ open access Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Public Library of Science (PLOS)