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Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate
The iron cycle, in which iron-containing soil dust is transported from land through the atmosphere to the oceans, affecting ocean biogeochemistry and hence having feedback effects on climate and dust production, is reviewed.
Methodological Underestimation of Oceanic Nitrogen Fixation Rates
It is demonstrated that the 15N2-tracer addition method underestimates N2 fixation rates significantly when the15N2 tracer is introduced as a gas bubble, and proposed and tested a modified 15N 2 tracer method based on the addition of 15N1-enriched seawater that provides an instantaneous, constant enrichment and allows more accurate calculation of N2fixation rates for both field and laboratory studies.
Diazotrophic Diversity and Distribution in the Tropical and Subtropical Atlantic Ocean
The data suggest a community shift from filamentous cyanob bacteria in surface waters to unicellular cyanobacteria and/or heterotrophic bacteria in deeper waters.
A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization
It is demonstrated that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
Abundances and Distributions of the Dominant nifH Phylotypes in the Northern Atlantic Ocean
Environmental DNA samples from four cruises to the North Atlantic Ocean were analyzed for the presence and amount of seven nifH phylotypes using real-time quantitative PCR and TaqMan probes and the cyanobacterial phylotypes dominated in abundance and were the most widely distributed.
Light intensity regulation of cab gene transcription is signaled by the redox state of the plastoquinone pool.
A model for a light intensity signaling system where cab gene expression is reversibly repressed by a phosphorylated factor coupled to the redox status of plastoquinone through a chloroplast protein kinase is proposed.
Impacts of Atmospheric Anthropogenic Nitrogen on the Open Ocean
Although ∼10% of the ocean's drawdown of atmospheric anthropogenic carbon dioxide may result from this atmospheric nitrogen fertilization, leading to a decrease in radiative forcing, up to about two-thirds of this amount may be offset by the increase in N2O emissions.
Whole-cell response of the pennate diatom Phaeodactylum tricornutum to iron starvation
This work has explored the biochemical strategies preferred by Phaeo dactylum tricornutum at growth-limiting levels of dissolved Fe and found that this retrenchment is compensated by nitrogen (N) and carbon (C) reallocation from protein and carbohydrate degradation, adaptations to chlorophyll biosynthesis and pigment metabolism, and augmented Fe-independent oxidative stress responses.
Bioassays, batch culture and chemostat experimentation, Approaches and tools to manipulate the carbonate chemistry
Although the chemistry of ocean acidifi cation is very well understood (see chapter 1), its impact on marine organisms and ecosystems remains poorly known. The biological response to ocean acidifi