Abstract
Cyanobacterial diversity in the Salton Sea, a high-salinity, eutrophic lake in Southern California, was investigated using a combination of molecular and morphological approaches. Representatives of a total of 10 described genera (Oscillatoria, Spirulina, Arthrospira, Geitlerinema, Lyngbya, Leptolyngbya, Calothrix, Rivularia, Synechococcus, Synechocystis) were identified in the samples; additionally, the morphology of two cultured strains do not conform to any genus recognized at present by the bacteriological system. Genetic analysis, based on partial 16S rRNA sequences suggested considerable cryptic genetic variability among filamentous strains of similar or identical morphology and showed members of the form-genus Geitlerinema to be distributed among three major phylogenetic clades of cyanobacteria. Cyanobacterial mats, previously described from the Sea were, in fact, composed of both filamentous cyanobacteria and a roughly equivalent biomass of the sulfur-oxidizing bacterium Beggiatoa, indicating their formation in sulfide rich regions of the lake. Flow cytometric analysis of the water samples showed three striking differences between samples from the Salton Sea and representative marine waters: (1) phycoerythrin-containing unicells, while abundant, were much less abundant in the Salton Sea than they were in typical continental shelf waters, (2) Prochlorococcus appears to be completely absent, and (3) small (3-5 μm) eukaryotic algae were more abundant in the Salton Sea than in typical neritic waters by one-to-two orders-of-magnitude. Based on flow cytometric analysis, heterotrophic bacteria were more than an order of magnitude more abundant in the Salton Sea than in seawater collected from continental shelf environments. Virus particles were more abundant in the Salton Sea than in typical neritic waters, but did not show increases proportionate with the increase in bacteria, picocyanobacteria, or eukaryotic algae.
| Original language | English |
|---|---|
| Pages (from-to) | 77-92 |
| Number of pages | 16 |
| Journal | Hydrobiologia |
| Volume | 473 |
| DOIs | |
| State | Published - Apr 1 2002 |
Funding
We want to thank the many people who contributed to this study, particularly Michael Waters and William Yeoung who spent many hours assisting in the isolation of the clonal cultures, to S. Garbush and L. Wingard for maintenance of the cultures, and to C. Everroad for assistance with graphics. We also thank Stuart Hurlbert for his continuous and enthusiastic encouragement and the SDSU Salton Sea research group, particularly Mary Ann Tiffany, B. Kuperman, Victoria Matey, and Joan Daimler for their assistance at the lake. Special thanks are offered to B.J. Wood and W.W. Wood for inspiration and encouragement and to C. Trees and K. Steidinger for introducing us to this fascinating ecosystem. Financial support was provided in part by the United States Environmental Protection Agency through grant #R86552-01-0 to the Salton Sea Authority, and from the Office of Naval Research through grant N0014-99-1-0177. The research results have not been subjected to the EPA’s required peer review and therefore do not necessarily reflect the view of the Agency. Therefore no official endorsement should be inferred.
| Funders | Funder number |
|---|---|
| Office of Naval Research | N0014-99-1-0177 |
| 86552-01-0 |
Keywords
- Beggiatoa
- Cyanobacteria
- Flow cytometry
- Geitlerinema
- Microbial mats
- Molecular systematics
- Oscillatoria
- Phylogeny
- Picoplankton
- Saline lake
- Ultraplankton
- Viruses
