Interactions between Emiliania huxleyi and the dissolved inorganic carbon system

De oceanen bedekken 71 procent van het oppervlak van onze planeet en Oceaan zou een beter passende naam zijn dan Aarde. De buitenkant van de Aarde noemen we de biosfeer waar alle levende organismen een nauwe relatie hebben met hun omgeving: de chemische stoffen in de bodem, de lucht en het water.

Production, oxygen respiration rates, and sinking velocity of copepod fecal pellets: Direct measurements of ballasting by opal and calcite

Production, oxygen uptake, and sinking velocity of copepod fecal pellets egested by Temora longicornis were measured using a nanoflagellate (Rhodomonas sp.), a diatom (Thalassiosira weissflogii), or a coccolithophorid (Emiliania huxleyi) as food sources. Fecal pellet production varied between 0.8 pellets ind21 h21 and 3.8 pellets ind21 h21 and was significantly higher with T. weissflogii than with the other food sources. Average pellet size varied between 2.2 3105 mm3 and 10.0 3105 mm3. Using an oxygen microsensor, small-scale oxygen fluxes and microbial respiration rates were measured directly with a spatial resolution of 2 mm at the interface of copepod fecal pellets and the surrounding water. Averaged volume-specific respiration rates were 4.12 fmol O2 mm23 d21, 2.86 fmol O2 mm23 d21, and 0.73 fmol O2 mm23 d21 in pellets produced on Rhodomonas sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d21 independent on diet (range: 0.08– 0.21 d21). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 6 169 m d21) and E. huxleyi (200 6 93 m d21) than on Rhodomonas sp. (35 6 29 m d21). Preservation of carbon was estimated to be approximately 10-fold higher in fecal pellets produced when T. longicornis was fed E. huxleyi or T. weissflogii rather than Rhodomonas sp. Our study directly demonstrates that ballast increases the sinking rate of freshly-produced copepod fecal pellets but does not protect them from decomposition

Production, oxygen uptake, and sinking velocity of copepod fecal pellets originated from the central North Sea

Production, oxygen uptake, and sinking velocity of copepod fecal pellets egested by Temora longicornis were measured using a nanoflagellate (Rhodomonas sp.), a diatom (Thalassiosira weissflogii), or a coccolithophorid (Emiliania huxleyi) as food sources. Fecal pellet production varied between 0.8 pellets ind**-1 h**-1 and 3.8 pellets ind**-1 h**-1 and was significantly higher with T. weissflogii than with the other food sources. Average pellet size varied between 2.2 x 10**5 µm**3 and 10.0 x 10**5 µm**3. Using an oxygen microsensor, small-scale oxygen fluxes and microbial respiration rates were measured directly with a spatial resolution of 2 µm at the interface of copepod fecal pellets and the surrounding water. Averaged volume-specific respiration rates were 4.12 fmol O2 µm**-3 d**-1, 2.86 fmol O2 µm**-3 d**-1, and 0.73 fmol O2 µm**-3 d**-1 in pellets produced on Rhodomonas sp., T. weissflogii, and E. huxleyi, respectively. The average carbon-specific respiration rate was 0.15 d**-1 independent on diet (range: 0.08-0.21 d**-1). Because of ballasting of opal and calcite, sinking velocities were significantly higher for pellets produced on T. weissflogii (322 +- 169 m d**-1) and E. huxleyi (200 +- 93 m d**-1) than on Rhodomonas sp. (35 +- 29 m d**-1). Preservation of carbon was estimated to be approximately 10-fold higher in fecal pellets produced when T. longicornis was fed E. huxleyi or T. weissflogii rather than Rhodomonas sp. Our study directly demonstrates that ballast increases the sinking rate of freshly produced copepod fecal pellets but does not protect them from decomposition

Global distributions of microzooplankton abundance and biomass - Gridded data product (NetCDF) - Contribution to the MAREDAT World Ocean Atlas of Plankton Functional Types

Microzooplankton database. Originally published in: Buitenhuis, Erik, Richard Rivkin, Sévrine Sailley, Corinne Le Quéré (2010) Biogeochemical fluxes through microzooplankton. Global Biogeochemical Cycles Vol. 24, GB4015, doi:10.1029/2009GB003601 This new version has had some mistakes corrected

Bacterial biomass distribution in the global ocean

International audienceWe compiled a database of bacterial abundance of 39 766 data points. After gridding with 1 spacing, the database covers 1.3% of the ocean surface. There is data covering all ocean basins and depth except the Southern Hemisphere below 350m or from April until June. The average bacterial biomass is 3.9±3.6 μg l−1 5 with a 20-fold decrease between the surface and the deep sea. We estimate a total ocean inventory of about 1.3×1029 bacteria. Using an average of published open ocean measurements for the conversion from abundance to carbon biomass of 9.1 fg cell−1, we calculate a bacterial carbon inventory of about 1.2 PgC. The main source of uncertainty in this inventory is 10 the conversion factor from abundance to biomass