Title: Vertical Variability and Diel Dynamics of Picophytoplankton in the Strait of Sicily (Mediterranean Sea) in Summer
Citation: MARINE ECOLOGY-PROGRESS SERIES vol. 346 p. 15-26
Publication Year: 2007
JRC N°: JRC37630
ISSN: 0171-8630
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC37630
DOI: 10.3354/meps07017
Type: Articles in periodicals and books
Abstract: Phytoplankton pigment diversity and photoacclimation during the natural day-night cycle was investigated at a fixed location in the Strait of Sicily in July 1997, using HPLC pigment analysis on fractionated samples (<3 micrometers and >3 micrometers) and flow cytometry. Picophytoplankton dominated phytoplankton biomass in terms of chla with an average value of 57%, and was mainly represented by prokaryotes, prymnesiophytes and pelagophytes. Prochlorococcus and picoeukaryotes equally contributed to the picophytoplankton in terms of chla, but Prochlorococcus were numerically more abundant and were represented by two ecotypes, one replacing the other with depth. Larger phytoplankton was dominated by prymnesiophytes and diatoms. Photoacclimation was evident from changes in pigment content and strongly increased with depth. The deep chlorophyll maximum (DCM), present between 75 and 90 m, showed a diverse and rich phytoplankton community with the two size classes almost equally represented. Growth rates of Prochlorococcus and Synechococcus, estimated from cell cycle measurements, were 0.67 and 0.41 d-1, respectively at 75 m. Only Prochlorococcus was able to sustain a good growth rate of 0.43 d-1 at the base of the DCM (90 m), where only 0.5% of incident light was available. Light-shift experiments using on-board incubated natural seawater showed much faster kinetic coefficients for acclimation in picophytoplankton than in larger algae. In general, the data present evidence about the dynamics of picophytoplankton and its light adaptation through the water column and in the DCM, and can be considered representative of stable summer conditions in the Mediterranean Sea.
JRC Directorate:Sustainable Resources

Files in This Item:
There are no files associated with this item.

Items in repository are protected by copyright, with all rights reserved, unless otherwise indicated.