Details

Autor(en) / Beteiligte

• Khammeri, Yosra
• Bellaaj-Zouari, Amel
• Hamza, Asma
• Medhioub, Walid
• Sahli, Emna
• Akrout, Fourat
• Barraj, Nouha
• Ben Kacem, Mohamed Yassine
• Bel Hassen, Malika

Titel

Ultraphytoplankton community composition in Southwestern and Eastern Mediterranean Basin: Relationships to water mass properties and nutrients

Ist Teil von

• Journal of sea research, 2020-03, Vol.158, p.101875, Article 101875

Ort / Verlag

Lausanne: Elsevier B.V

Erscheinungsjahr

2020

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The composition, biomass, and spatial and vertical distribution of ultraphytoplankton (< 10 μm) were investigated at the single-cell level by flow cytometry during the INCOMMET oceanographic cruise carried out during the fall of November 2013, covering eleven stations spread out along coastal Tunisian waters at less than 100 m depth. Flow cytometry analysis of samples taken at different stations and depths allowed the determination of five major groups of ultraphytoplankton; among them two populations of pico-cyanobacteria Synechococcus and Prochlorococcus, picoeukaryotes, nanoeukaryotes and cryptophytes. In addition to these autotrophic groups, three unknown groups were resolved and were distinguished by their fluorescence and size signals. The unknown groups' integrated biomass was larger than that of the other ultraphytoplankton components. The abundance of picoeukaryotes, nanoeukaryotes and cryptophytes increased gradually southwards towards the Gulf of Gabès, whereas Prochlorococcus were more abundant in the Gulf of Hammamet at more than 60 m depth. Structural equation modeling analysis showed weak links between most of the cell groups and nutrients concentrations. Clustering analysis based on the abundance of the phytoplankton groups resulted in aggregation into three clusters and two major zones, discriminating the Gulf of Gabès from the more northern Bays. The results suggest that the physical features, essentially the water mass properties, were the main drivers shaping the ultraphytoplankton community composition and that the autotrophic biomasses were not determined by nutrient control. •Most of the ultraphytoplankton groups increased gradually southwards, except for Prochlorococcus.•Ultraphytoplankton was clustered into three groups and two major zones discriminating the south from the other northern Gulfs.•The unidentified groups exhibited high integrated biomass compared to the five identified groups.•Water masses properties are the main drivers shaping the ultraphytoplankton community composition.•The close links between the identified and unidentified groups suggest likely trophic relationships.