SGER: Southern and Coastal Extent of Picophytoplankton Populations in the South Pacific

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The most abundant and ubiquitous members of the marine phytoplankton belong to two cyanobacterial genera, Synechococcus and Prochlorococcus, which together contribute more than half of the primary productivity in the open ocean. Each of these genera, which form a distinct picophytoplankton clade within the marine cyanobacteria, can be further subdivided into multiple phylogenetic clades (referred to as genotypes or ecotypes), some of which have clear physiological characteristics that can be related to their ecological distributions. However, the boundaries of the horizontal distributions of the various genotypes are not fully understood, and discrepancies between studies in the South Atlantic require further examination of the picophytoplankton distributions, particularly of the Prochlorococcus populations. In a research cruise during Dec 2008 to the Patagonia shelf region from ~40 deg S, 57deg W to ~53 deg S, 55 deg W near the Falkland Islands, the PI will be able to examine the southern extent of picophytoplankton populations as well as the distributions across the shelf break front going east into oligotrophic waters. At stations representing different water types, samples will be collected for flow cytometric analysis of picophytoplankton populations, will be filtered for later qPCR analysis of Prochlorococcus and Synechococcus ecotypes, and will be cryopreserved for isolations using high throughput culture methods.This SGER project will provide a new dataset of the southern and coastal extent of picophytoplankton populations, and possibly address the question of whetherProchlorococcus populations are extending further south into colder waters than initially observed more than a decade ago. Additionally, it will enable a MS student to participate in the research cruise and get experience with field research, provide funds for supplies and shipping samples, and provide a MS student stipend to analyze the samples.