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The formation and sinking of biogenic particles mediate vertical mass fluxes and drive elemental cycling in the ocean. Whereas marine sciences have focused primarily on particle production by phytoplankton growth, particle formation by the assembly of organic macromolecules has almost been neglected. Here we show, by means of a combined experimental and(More)
The carbon and nitrogen content of transparent exopolymer particles (TEP) was determined and related to the concentration of TEP as quantified by a colorimetrical method. TEP were produced in the laboratory from dissolved precursors by laminar or turbulent shear. Dissolved precursors were obtained by 0.2 μm filtration from diatom cultures, with or without(More)
We studied the direct effects of CO2 and related changes in seawater carbonate chemistry on marine planktonic organisms in a mesocosm experiment. In nine outdoor enclosures (;11 m3 each), the partial pressure of CO2 (pCO2) in the seawater was modified by an aeration system. The triplicate mesocosm treatments represented low (;190 parts per million by volume(More)
A scanning transmission electron microscope is employed to determine the mass of biological macromolecules. Elastically scattered electrons are collected by an annular detector that is capable of counting single electrons. Off-line processing of these dark field micrographs stored on a magnetic tape is accomplished by a mini-computer. It allows the number(More)
The pelagic ocean harbors one of the largest ecosystems on Earth. It is responsible for approximately half of global primary production, sustains worldwide fisheries, and plays an important role in the global carbon cycle. Ocean warming caused by anthropogenic climate change is already starting to impact the marine biota, with possible consequences for(More)
a r t i c l e i n f o The present study investigates the combined effect of phosphorous limitation, elevated partial pressure of CO 2 (pCO 2) and temperature on a calcifying strain of Emiliania huxleyi (PML B92/11) by means of a fully controlled continuous culture facility. Two levels of phosphorous limitation were consecutively applied by renewal of(More)
Marine bacteria are the main consumers of freshly produced organic matter. Many enzymatic processes involved in the bacterial digestion of organic compounds were shown to be pH sensitive in previous studies. Due to the continuous rise in atmospheric CO2 concentration, seawater pH is presently decreasing at a rate unprecedented during the last 300 million(More)
Iglesias-Rodriguez et al. (Research Articles, 18 April 2008, p. 336) reported that the coccolithophore Emiliania huxleyi doubles its organic matter production and calcification in response to high carbon dioxide partial pressures, contrary to previous laboratory and field studies. We argue that shortcomings in their experimental protocol compromise the(More)
During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed(More)