| Summary: | 17th Ocean Sciences Meeting, 23-28 February 2014, Honolulu, Hawaii USA The metabolic carbon requirements and excretion rates of ammonia and phosphate by salps and krill, two of the major zooplankton groups in the Southern Ocean, were studied in the vicinity of the Antarctic Peninsula in February 2009. The research was conducted in the framework of the ATOS project (POL2006-00550/CTM), as part of the Spanish contribution to the International Polar Year. Our objective was to ascertain the possible consequences for biogenic carbon cycling and nutrient stoichiometry of the shift from krill, the dominant zooplankton group, to salps. The carbon-specific respiration and NH4-N and PO4-P excretion rates of Euphausia superba and Salpa thompsoni were estimated by incubation experiments. The metabolic carbon requirements by salps and the N:P atomic ratios of their excreted products were higher by a factor of five and two respectively than those of krill. The substitution of krill by salps could include, aside from direct consequences for krill predators, indirect changes in the Antarctic food webs by alterations of the pool of nutrients available for phytoplankton due to the higher N:P ratios of the excreted products by salps This study was supported by the projects ATOS, ATP and TOP-COP from the Spanish MICINN Peer Reviewed
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