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Pico-, nano- and microplankton communities in hydrothermal marine coastal environments of the Eolian Islands (Panarea and Vulcano) in the Mediterranean Sea

1996; Oxford University Press; Volume: 18; Issue: 5 Linguagem: Inglês

10.1093/plankt/18.5.715

1464-3774

M. Lucila, C. Acosta Pomar, Giovanni Giuffrfè,

Microbial Community Ecology and Physiology

This paper reports the relationship among pico-, nano- and microplanktonic communities observed in two different shallow marine hydrothermal environments. Seawater samples from five stations in the coastal area of the ‘Porto di Levante’ (Vulcano Island) and from three stations off the Island of Panarea (Eolian Islands, Italy) were collected in May and July of 1989, respectively. Microbiological investigations were carried out in order to determine the density of: (i) the total picoplankton (both autotrophic and heterotrophic): (ii) the total picophytoplankton (autofluorescent picoplanktonic cells); (iii) the larger phytoplankton (>2 μm): (iv) the ‘metabolically active’ cells of total picoplankton and cyanobacteria; (v) the heterotrophic aerobic bacteria. The peak values of picoplankton and picophytoplankton components, with an order of magnitude of 109 and 107 cells 11, respectively, were registered in the wannest water samples (30–75°C) collected from the Vulcano area. At Panarea. eukaryotic picophytoplankton and ‘metabolically active’ coccoid cyanobacteria showed an opposite trend. A possible competition between the two groups is to be considered. Cyanobacteria, diatoms and the genus Licmophora. in particular, were prevalent in the warmest hydrothermal vents of Vulcano. Nano- and microphytoplanktonic communities in the offshore waters of the Island of Panarea showed more variability than in Vulcano. Moreover, in the Panarea waters the prevalence of phytoflagellates above the thermocline was observed, whereas diatoms were predominant below this layer.