Dynamics of Community Structure and Phosphate Status of Picocyanobacterial Populations in the Gulf of Aqaba, Red Sea

• Published in: Limnology and oceanography 2005-01, Vol.50 (1), p.363-375
• Main Authors: Fuller, Nicholas J., West, Nyree J., Marie, Dominique, Yallop, Marian, Rivlin, Tanya, Post, Anton F., Scanlan, David J.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; DNA probes; Euphotic zone; Fundamental and applied biological sciences. Psychology; Genotypes; Nitrates; Phosphates; Population dynamics; Ribosomal DNA; Sea water; Sea water ecosystems; Seas; Surface water; Synecology
• ISSN: 0024-3590; 1939-5590
• DOI: 10.4319/lo.2005.50.1.0363

We monitored the genetic diversity and phosphate (P) status of Prochlorococcus and Synechococcus populations during an annual cycle (1999-2000) in the Gulf of Aqaba, Red Sea, using DNA probes and antibodies against the protein PstS, a molecular marker of P stress. The usual spring Synechococcus bloom was not observed in this year, and the picophytoplankton was dominated by Prochlorococcus from April to December. A single high light (HL)-adapted ecotype of Prochlorococcus, HLII, dominated, and this dominance extended even to the base of the euphotic zone for much of the year. Low light (LL)-adapted ecotypes only appeared between July and October and were confined to waters deeper than 50 m. The Synechococcus population was also dominated by a single clade (clade II), with the exception of a peak of clade III genotypes in June. Highest PstS expression from the collective Synechococcus and Prochlorococcus populations, indicative of P stress, was observed during the acutely oligotrophic summer, whereas low expression occurred during the winter and spring. Prochlorococcus abundance appeared unaffected by P stress and only decreased with the beginning of winter mixing, whereas P stress might have caused the decline of the Synechococcus population in May 1999.