Solar
energy
Phototrophic sulfur
bacteria
Algae, plants
cyanobacteria
Aerobic heterotrophic
bacteria
Fermentative and
Sulfate-reducing bacteria
Trophic food
web
Detritic organic
matter
Detritic organic
matter
CO 2
H 2 S
CO 2
H 2 O
O 2
SO 4
2Oxic conditions
Anoxic conditions
(1)
(1)
(2)
(2)
(2)
(2)
(3)
(3)
(3)
(3)
Fig. 14.43 Comparison of the primary production (oxygenic photosynthesis due to algae, macrophytes, and cyanobacteria) and paraprimary production (anoxygenic phototrophic bacteria) in aquatic
ecosystems and their contribution to food webs. 1 photosynthetic production, 2 organic matter incorporation in food webs, 3 organic matter
degradation
2 - 5 mm
Air
Night
Concentration
Concentration
Water
Sediment
Depth
Oxygen
Sulfide
Cyanobacteria, algae
and aerobic bacteria
Aerobic sulfur oxidizing
bacteria
Phototrophic purple
bacteria
Sulfate-reducing
bacteria
a
b
Day
Fig. 14.44 Microbial mats. (a) Photograph showing spatial distribution of the main metabolic groups and the presence of oxygen bubbles
at the surface (arrows); (b) distribution of oxygen and sulfide during the
day and the night in a microbial mat (Modified from van Gemerden
1993) (Photograph from Re ´my Guyoneaud)
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