title: Diversity of planktonic photoautotrophic microorganisms along a salinity gradient as depicted by microscopy, flow cytometry, pigment analysis and DNA-based methods.
abstract: The diversity of prokaryotic and eukaryotic phytoplankton was studied along a gradient of salinity in the solar salterns of Bras del Port in Santa Pola (Alacant, Spain) using different community descriptors. Chlorophyll a, HPLC pigment composition, flow cytometrically-determined picoplankton concentration, taxonomic composition of phytoplankton (based on optical microscopy) and genetic fingerprint patterns of 16S (cyanobacteria- and chloroplast-specific primers) and 18S rRNA genes were determined for samples from ponds with salinities ranging from 4% to 37%. Both morphological and genetical descriptors of taxonomic composition showed a good agreement and indicated a major discontinuity at salinities between 15% and 22%. The number of classes and the Shannon diversity index corresponding to the different descriptors showed a consistent decreasing trend with increasing salinity. The results indicate a selective effect of extremely high salinities on phytoplanktonic assemblages.
authors.affiliation: Institut de Ciències del Mar, CMIMA (CSIC), Pg. Marítim de la Barceloneta, 37-49, 08003 Barcelona, Spain. marta@icm.csic.es
authors.forename: Marta
authors.initials: M
authors.lastname: Estrada
authors.forename: Peter
authors.initials: P
authors.lastname: Henriksen
authors.forename: Josep M
authors.initials: JM
authors.lastname: Gasol
authors.forename: Emilio O
authors.initials: EO
authors.lastname: Casamayor
authors.forename: Carlos
authors.initials: C
authors.lastname: Pedrós-Alió