Global change, zooplankton shifts, and C, N and P cycles in the southern ocean

• Main Authors: Alcaraz, Miquel, Almeda, Rodrigo, Duarte, Carlos M., Horstkotte, Burkhard, Lasternas, Sebastien, Agustí, Susana
• Other Authors: Ministerio de Ciencia e Innovación (España)
• Format: Conference Object
• Language: unknown
• Published: Russian Academy of Sciences 2014
• Subjects: Antarctic; Antarctic Peninsula; Southern Ocean; The Antarctic; Antarc*; Euphausia superba; Sea ice
• Online Access: http://hdl.handle.net/10261/127629; https://doi.org/10.13039/501100004837

49th European Marine Biology Symposium (49TH EMBS), 7-12 september 2014, S. Petersburg, Russia.-- 1 page The transfer of matter and energy from autotrophs to upper consumers in the Southern Ocean is essentially controlled by two groups of zooplankton, krill and salps. While krill (mainly Euphausia superba) is almost the unique food source for Antarctic fish, birds and mammals, salps (Salpa thompsoni) are of very indifferent nutritious value. Salps play a role at least as important as krill in the carbon cycle, filtering and packing biogenic carbon into larger and heavier faecal pellets than krill, thus accelerating the vertical flux of matter towards the long-lived and even sequestered carbon pools. Both groups show huge temporal and spatial fluctuations, with the irregular alternation of krill-dominated and salp-dominated years when salps, owing to their high rates of population growth and short life cycles dominate Antarctic zooplankton. At the same time, the continuous decreasing trend of krill populations along the last forty years has lead to predict a shift in Antarctic ecosystems, with the global substitution of krill by salps. The drivers of the change are not clear, but warmer temperatures, the extension of sea ice, and the decimation of whales appear as the most probable sources. Another consequence of the high warming rates in some Antarctic areas (i.e., the Antarctic Peninsula) would be the reduction of the individual biomass spectrum. Under these conditions, not only the populations depending of krill as food source will be severely threated, but the removal rates and fate of biogenic carbon, as well as the regeneration rates of nutrients by zooplankton excretion would change. With the objective of ascertaining the possible consequences for the cycling of biogenic carbon and the stoichiometry of regenerated nutrients of the predicted shifts in the Southern Ocean zooplankton we estimated the metabolic carbon requirements and inorganic N and P excretion rates of three major zooplankton groups in the ...