Nv. Pimenov et al., Carbon dioxide assimilation and methane oxidation in various zones of the rainbow hydrothermal field, MICROBIOLOG, 69(6), 2000, pp. 689-697
Rates of carbon dioxide assimilation and methane oxidation were determined
in various zones of the Rainbow Hydrothermal Field (36 degreesN) of the Mid
-Atlantic Ridge. In the plume above the hydrothermal field, anomalously hig
h methane content was recorded, the microbial population density (up to 10(
5) cells/ml) was an order of magnitude higher than the background values, a
nd the CO2 assimilation rate varied from 0.01 to 1.1 mug C/(1 day). Based o
n the data on CO2 assimilation, the production of organic carbon due to bac
terial chemosynthesis in the plume was calculated to be 930 kg/day or 340 t
ons/year (about 29% of the organic carbon production in the photic zone). I
n the black smoke above active smokers, the microbial population density wa
s as high as 10(6) cells/ml, the rate of CO2 assimilation made up 5-10 mug
C/(1 day), the methane oxidation rate varied from 0.15 to 12.7 mul/(1 day),
and the methane concentration ranged from 1.05 to 70.6 mul/l. In bottom se
diments enriched with sulfides, the rare of CO2 assimilation was at least a
n order of magnitude higher than in oxidized metal-hearing sediments. At th
e base of an active construction, whitish sediment was found, which was cha
racterized by a high methane content (92 mul/dm(3)) and a high rate of meth
ane oxidation (1.7 mul/(dm(3) day)).