RAPID: El Nino and the controls of marine virus diversity

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AbstractIn July 2009, the NOAA National Weather Service Climate Prediction Center announced the arrival of El Niño, an episode of abnormal warming of sea surface temperature (SST) in the equatorial Pacific that occurs every 3-8 years. This project will investigate the impact of El Niño on marine virus communities, using cyanophages that infect the cyanobacterium Synechoccocus as a model system. The upcoming El Niño presents an opportunity to advance research on the fundamental question of what drives temporal variability in cyanophage diversity.The goals of this project are: (1) to disentangle various abiotic factors that influence cyanophage diversity and (2) to test the mechanisms behind temporal variability in cyanophage diversity, by comparing the evolutionary processes by which cyanophages adapt to temperature and host composition. To meet these objectives, ~150 cyanophage will be isolated monthly from three coastal sites in the Southern California Bight. The purified isolates will be characterized by sequencing their g20 gene. Phenotypic assays will be carried out on a selection of these isolates and isolates from the previous non-El Niño years.The environmental variability that El Niño will provide is crucial to both parts of this project. It will help to disentangle the effect of covarying factors on in situ cyanophage composition. For instance, in Southern California, El Niño should provide higher-than-normal SST during months of relatively low UV intensity (fall and winter). It will also permit isolation of a broader genetic diversity of cyanophages from a wider array of environmental conditions, providing crucial statistical power to the laboratory experiments. The project will further our mechanistic understanding of the controls of marine virus diversity.Broader impacts consist of an increased understanding of how virus diversity is distributed and maintained in the ocean. Viral lysis of marine microorganisms alters the pools of dissolved organic matter and inorganic nutrients and therefore may have a major impact on marine biogeochemical cycling. The project will also be the first to investigate the impact of El Niño on any non-pathogenic virus community. Further, it will contribute to the training of at least 3 undergraduate students and a PhD student.