Award: OCE-1031064

The collaborative research project titled "Seasonal and decadal changes in temperature drive Prochlorococcus ecotype distribution patterns" was a joint effort between Duke University and University of Tennessee Knoxville and encompassed 4 research cruises (over 100 days at sea) and traversed the Northern Pacific Ocean multiple times over multiple seasons. The project trained numerous undergraduates, graduate students and postdocs and involved collaborating scientists from other institutions as well as school teachers, journalism students and other non-professionals. The goal of the project was to investigate how the diversity and activity of Prochlorococcus, the most abundant phytoplankton in the open ocean, responds to temperature changes as a function of latitude and seasons. Our broader goal was to put these findings in to the context of climate change, which is expected to result in increasing ocean temperatures. Towards these goals we used the latest techniques in physiology and molecular ecology, and developed some new approaches that allow the assessment of the activity of genetically distinct types of Prochlorococcus (as well as other marine microbes). Using these laboratory- and field-based approaches, we discovered that Prochlorococcus is much more diverse than previously thought, and that it is composed of >1000 different "species." These species differentially respond to environmental change, with some optimized for unique environments (e.g. combinations of nutrients, temperature, etc.) while others are apparently regulated by interactions with other organisms (e.g. viruses, grazers, other microbes). Further, we found that these different types of Prochlorococcus have different impacts on the carbon cycle (and presumably the marine foodweb), with some having tightly temperature controlled carbon dioxide uptake whereas others are differentially regulated. All types respond to environmental variability on multiple time scales and this variability can be seen in the diversity and activity of Prochlorococcus across multiple space and time scales. Projecting these findings into future climate scenarios, it is clear that Prochlorococcus cannot be treated a single organisms, but the extent and nature of its molecular diversity must be taken into account to understand the carbon cycle and ocean ecology of future oceans. In addition to numerous publications and public presentations, these findings have been communicated to a broad array of educators and incorporated into K-12 lessons plans as well as undergraduate and graduate courses. Data from this project is publically available on BCO-DMO (http://www.bco-dmo.org/project/2237) with additional molecular data available from NCBI (http://www.ncbi.nlm.nih.gov/). Finally, this project has supported our team to interact, educate and to help inspire the broader public and future scientists through an array of open houses, classroom visits, "adopt-a-teacher" programs, and other public educational forums. Last Modified: 12/30/2015 Submitted by: Zackary I Johnson