The characterisation and summer distribution of ultraphytoplankton in the Gulf of Gabès (Eastern Mediterranean Sea, Tunisia) by using flow cytometry

Synthesis review of the Gulf of Gabes (eastern Mediterranean Sea, Tunisia): Morphological, climatic, physical oceanographic, biogeochemical and fisheries features

“…The ultraphytoplankton (cells up to 10 μm), studied using flow cytometry, were resolved into five cell groups, Prochlorococcus, Synechococcus, picoeukaryotes, nanoeukaryotes and a group of unidentified cells characterized by a low fluorescence signal (Hamdi et al, 2015). The low ultraphytoplankton abundance was explained by the heterotrophic nanoflagellates feeding on picoplankton, suggesting a tight top-down control of the picoplankton community (Hamdi et al, 2015). More recently, the distribution and phylogenic diversity of picoeukaryote assemblages was studied by Bellaaj Zouari et al 2018using biomolecular techniques.…”

Distribution of the plankton assemblages during the winter and summer along the southern coast of the Kerkennah Islands (Tunisia, Eastern Mediterranean Sea)

“…Nitrogen, which is the most common element limiting microphytoplankton growth in most marine ecosystems (Livingston, 2001), was found at substantial concentrations during the summer along the coast of the Kerkennah Islands, while orthophosphate concentrations were low and N/P was higher than the Redfield ratio (16). Orthophosphate was still at a very high concentration with respect to the rest of the ultraoligotrophic Eastern Mediterranean basin where phosphorus is a limiting factor for plankton growth (Krom, Emeis, & Cappellen, 2010), comparable results were found in the Eastern (Aktan, 2010) (Hamdi et al, 2015). Total phosphate concentration presented the same pattern as orthophosphate and was three to nine times more abundant.…”

“…This is probably due to the shallow waters of the Kerkennah Islands, combined with the large tides favoring sediment re‐suspension and so maintaining the presence of nutrients throughout the year. In addition, Saharan dust deposits are likely to be an important source of nutrients although this remains to be quantified by in situ investigations (Hamdi et al, ). Total phosphate concentration presented the same pattern as orthophosphate and was three to nine times more abundant.…”

Application of cryopreservation to genetic analyses of a photosynthetic picoeukaryote community

“…Sample concentration before sorting-especially in the case of ocean specimens with low cell density-is essential (Marie et al, 2010). The morphology of FCM-sorted cells from ocean specimens has been studied with scanning electron microscopy (Gömez-Pereira et al, 2013;Hamdi et al, 2015). FCM sorting, especially in combination with other techniques, may lead to breakthroughs in our understanding of the biodiversity and ecological roles of microorganisms including photosynthetic picoeukaryotes.…”