Environmental Engineering Reference
In-Depth Information
FIGURE 8.4
Selected genera of cyanobacteria, with length of scale bar: (A)
Aphanizomenon,
30
m; (B)
Anabaena,
20
m; (C)
Oscillatoria,
20
m; (D)
Microcystis,
20
m; (E)
Rivu-
laria,
habit view 50
m, single trichome 25
m; and (F) picocyanobacteria, 3
m, (indeter-
minate genera) (A-E reproduced with permission from Prescott, 1982).
appearance. The gas vesicles give the cyanobacteria a competitive advan-
tage in eutrophic conditions by allowing them to compete well for light at
the surface and shade out the phytoplankton below. Halting vesicle syn-
thesis allows cells to sink to deeper, nutrient-rich waters.
Cyanobacteria are excellent competitors for light because they have
phycobilins,
pigments that absorb light in the green region (where chloro-
phyll does not absorb). The ability to utilize green light allows some species
Search WWH ::
Custom Search