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Variabilité du microphytoplancton et des Tintinnida (protozoaires ciliés) d'un secteur eutrophe du golfe d'Annaba (Méditerranée sud-occidentale) = Variability of microphytoplankton and Tintinnida (ciliated protozoa) in an eutrophic sector of the Annaba Gulf (S.W. Mediterranean)
Ounissi, M.; Frehi, H. (1999). Variabilité du microphytoplancton et des Tintinnida (protozoaires ciliés) d'un secteur eutrophe du golfe d'Annaba (Méditerranée sud-occidentale) = Variability of microphytoplankton and Tintinnida (ciliated protozoa) in an eutrophic sector of the Annaba Gulf (S.W. Mediterranean). Cah. Biol. Mar. 40(2): 141-153
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723, more
Peer reviewed article  

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Keyword
    Marine

Authors  Top 
  • Ounissi, M.
  • Frehi, H.

Abstract
    The western sector of the Annaba Gulf is a bay opened to the outside neritic water and to the continental discharge proceeding principally from the Seybouse river. The plankton was sampled monthly by horizontal hauls in four stations in 1992. The results show the existence of two zones fundamentally different: the zone of interface, receiving the continental runoff, and the zone exposed directly to the intrusion of the outside waters. The first zone is highly fertile and distinguished by the low transparency and low salinity of enclosed waters. It shelters dense but weakly diversified populations. Diatom populations are abundant and comprise principally Coscinodiscus radiatus, Chaetoceros curvisetus, Chaetoceros spp. and Rhizosolenia spp. The Dinophycea Protoperidinium depressum, Dinophysis caudata, Ceratium spp. can, in hot season, develop into strong abundance. On the other hand, Tintinnida exhibit demographic explosions, particularly in summer and comprise essentially 4-5 opportunists species such as Favella serrata, Tintinnopsis campanula, Porecus apiculatus, Codonellopsis morchella. The second zone is characterized by its more transparent and renewed water with a low fertility. Dinoflagellates dominate in this area and diatom and tintinnid populations decrease in density and their hierarchy abundance is modified. The proliferation of Pseudo-nitzschia multiseries in April spreads however to the whole sector. It appears finally, that the fraction of the studied planktonic Protista seems to be controlled principally by the physical factors (intrusion of external neritic water and continental runoff).

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