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Marine microbial communities are complex and dynamic, and their ecology impacts biogeochemical cycles in pelagic ecosystems. Yet, little is known about the relative activities of different microbial populations within genetically diverse communities. We used rRNA as a proxy for activity to quantify the relative specific activities (rRNA/ribosomal DNA [rDNA(More)
Marine phytoplankton have conserved elemental stoichiometry, but there can be significant deviations from this Redfield ratio. Moreover, phytoplankton allocate reduced carbon (C) to different biochemical pools based on nutritional status and light availability, adding complexity to this relationship. This allocation influences physiology, ecology, and(More)
Theoretical studies predict that competition for limited resources reduces biodiversity to the point of ecological instability, whereas strong predator/prey interactions enhance the number of coexisting species and limit fluctuations in abundances. In open ocean ecosystems, competition for low availability of essential nutrients results in relatively few(More)
T he oceans account for approximately half of global carbon fixation (1), but unlike plantdominated terrestrial environments, marine photosynthesis is dominated by single-celled microbes, or phytoplankton. These phytoplankton are the engines that drive marine food webs and biogeochemistry. Among the vast variety of phytoplankton found in the open ocean, the(More)
The vast majority of the phytoplankton communities in surface mixed layer of the oligotrophic ocean are numerically dominated by one of two ecotypes of Prochlorococcus, eMIT9312 or eMED4. In this study, we surveyed large latitudinal transects in the Atlantic and Pacific Ocean to determine if these ecotypes discretely partition the surface mixed layer niche,(More)
The distribution of major clades of Prochlorococcus tracks light, temperature and other environmental variables; yet, the drivers of genomic diversity within these ecotypes and the net effect on biodiversity of the larger community are poorly understood. We examined high light (HL) adapted Prochlorococcus communities across spatial and temporal(More)
In the open ocean genetically diverse clades of the unicellular cyanobacteria Prochlorococcus are biogeographically structured along environmental gradients, yet little is known about their in situ activity. To address this gap, here we use the numerically dominant Prochlorococcus clade eHL-II (eMIT9312) as a model organism to develop and apply a method to(More)
Despite our current realization of the tremendous diversity that exists in plankton communities, we have little understanding of how this biodiversity influences the biological carbon pump other than broad paradigms such as diatoms contributing disproportionally to carbon export. Here we combine high-resolution underway O2/Ar, which provides an estimate of(More)
The Growth and Activity of Genetically Diverse Prochlorococcus by Yajuan Lin Marine Science and Conservation Duke University Date:_______________________ Approved: ___________________________ Zackary Johnson, Supervisor ___________________________ Erik Zinser ___________________________ Dana Hunt ___________________________ Jennifer Wernegreen An abstract(More)
Carly Moreno: A transcriptomic comparison of physiological responses to iron and light in Southern Ocean diatoms (Under the direction of Adrian Marchetti) Iron and light are two important abiotic factors that influence diatom growth and distribution in the Southern Ocean (SO). Through a combination of physiological and transcriptomic approaches, I have(More)
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