title: Krill excretion boosts microbial activity in the Southern Ocean.
abstract: 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.
authors.affiliation: Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Arístegui
authors.affiliation: Instituto Mediterráneo de Estudios Avanzados (IMEDEA), CSIC-UIB, Esporles, Illes Balears, Spain ; The UWA Oceans Institute, The University of Western Australia, Perth, Australia.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Duarte
authors.affiliation: Departmento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Reche
authors.affiliation: Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain ; Spanish Bank of Algae (BEA), Telde, Gran Canaria, Spain.
authors.forename: Juan L
authors.initials: JL
authors.lastname: Gómez-Pinchetti
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism; D000818:Animals; D000864:Antarctic Regions; D018533:Biomass; D033201:Euphausiacea / Q000737:chemistry / Q000502:physiology*; D005434:Flow Cytometry; D052836:Heterotrophic Processes / Q000502:physiology; D013058:Mass Spectrometry; D064307:Microbiota / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D014871:Water Microbiology
chemical_list: D064751:Ammonium Compounds