Journal of the Marine Biological Association of the United Kingdom

Research Article

Phytoplankton assemblages in coastal waters of the northern Ionian Sea (eastern Mediterranean), with special reference to cyanobacteria

Carmela  Caroppo a1c1, Silvia  Turicchia a2 and Maria Cristina  Margheri a2
a1 Istituto Ambiente Marino Costiero, Sede di Taranto, Consiglio Nazionale delle Ricerche, Via Roma, 374100 Taranto, Italy
a2 Istituto per lo Studio degli Ecosistemi, Sede di Firenze, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, sn, 50019 Sesto Fiorentino, Firenze, Italy

Article author query
caroppo c   [PubMed][Google Scholar] 
turicchia s   [PubMed][Google Scholar] 
margheri mc   [PubMed][Google Scholar] 


Sampling cruises were carried out on three coastal stations of the northern Ionian Sea over one year to investigate the effects of environmental factors on phytoplankton and picophytoplankton composition and succession. Larger phytoplankton (micro and nano fractions) was determined by using the Utermöhl settling technique, while picophytoplankton fraction was determined by epifluorescence microscopy. Furthermore, microbiological procedures were applied to investigate cyanobacterial diversity in the studied area. Results suggested that the most striking feature of phytoplankton communities was the high spatial variability in terms of abundance and biomass, which showed specific coastal Mediterranean values. Undetermined phytoflagellates and diatoms were the dominant groups of the Utermöhl fraction of phytoplankton, while round to rod-shaped small sized cyanobacteria represented the picophytoplankton fraction. Our data suggested that in the northern Ionian Sea the phytoplankton development was related to phosphorus availability and to ‘nitrogen-rich’ waters. Also the picophytoplankton seasonal trend was significantly correlated to N-compounds as well as to water temperature.

In addition to the typical picoplanktonic Synechococcus, the culture techniques allowed us to isolate and identify cyanobacteria belonging to the pleurocapsalean genus Stanieria and the oscillatoriacean genera Geitlerinema, Leiblenia, Leptolyngbya, Oscillatoria, Pseudanabaena and Spirulina. These species represent a minor fraction of the total cyanobacterial community in terms of biomass, but their importance is related to their contribution to the phytoplankton diversity.

(Published Online August 25 2006)
(Received July 20 2005)
(Accepted May 25 2006)

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