Vertical distribution of zooplankton biomass during summer stratification in the western Mediterranean
Alcaraz, M. (1985). Vertical distribution of zooplankton biomass during summer stratification in the western Mediterranean, in: Gibbs, P.E. (Ed.) Proceedings of the Nineteenth European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. pp. 135-143 In: Gibbs, P.E. (Ed.) (1985). Proceedings of the Nineteenth European Marine Biology Symposium, Plymouth, Devon, UK, 16-21 September 1984. European Marine Biology Symposia, 19. Cambridge University Press: Cambridge. ISBN 0-521-30294-3. 541 pp., more In: European Marine Biology Symposia., more |
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| Abstract | The vertical distribution of zooplankton biomass, expressed as the organic nitrogen content of the mesoplankton ( > 200 µm fraction), was studied at a series of stations located along a transect from Barcelona to the channel between the islands of Mallorca and Menorca during July 1982. Sampling depths between 5 and 200 m were selected according to the vertical distribution of chlorophyll. Vertical profiles of mesoplankton N during the day showed the existence of a zooplankton maximum at a depth ranging from 60 to 90 m. Its position coincided with the chlorophyll maximum. On some occasions, 60% of the total zooplankton biomass was concentrated in a layer 10 m thick. At night, due to the vertical migration of zooplankton, the biomass maximum was displaced upwards to an average depth of 25m. This observation has interesting ecological implications: if zooplankton feed during the daylight hours in the deep phytoplankton layer and migrate to the surface waters (and excrete there) at night, the downward transport of nutrients, could be retarded. |
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