Link to "Seaweeds of Hawaii" by William H. Magruder and Jeffrey W. Hunt
Oscillatoria au natural
Unknown Cyanobacterium from a warm spring near Mt. Lassen (CA)
Planktonic (few species) Important source for fixed Nitrogen
Rubble Intertidal Zone in "Ooid Sand Grains"
Surface Crusts which appear lifeless, are revived following significant rains. These dry to a brittle crust as the substrate looses water. These can beecologically significant because they add biomass and Nitrogen to barren areas. This is a long-term process, however. These crusts can be seen in places like Arches National Park (Utah) where it is very dry & there is little ground cover or litter.
This can also be seen locally on abandoned, dry lots. Heavy rains allow desiccated Cyanobacteria to flourish. They form undulating to round hydrated masses. These gradually shrink and crack as the substrate dries. They sometimes appear spherical.
Some Cyanobacteria (CBs) are also found in "green snow" which appears in the springtime on semi-permanent snowfields and glaciers.
Endolithic (Inside Rocks)
Cyanobacteria have recently found in the most barren area of Antarctica where no other life has been found. Similar observations have been made in the high Arctic. They live just below the surface of rocks. This sounds unbelievable but it is true.
Cyanobacteria can also inhabit carbonatic substrates like Limestone. (http://bio.bu.edu/~golubic/marine-cyano.html).
Some species inhabit the Calcium Carbonate secreted by Coralline Algae.
Hyella stella: a Cyanobacterium that lives in Marine Limestone
Organisms like this can live in Coral Rubble which rolls about as "sand". Consequently, they inhabit a reef zone that would otherwise be unavailable to them, due to the absence of a stable substrate and the presence of vigorous wave action which would be unfavorable for Planktonic algae. These areas are often turbid due to wave & wind action and from soil runoff.
"Ooid" sand grain containing Endolithic Cyanobacterium (CB).
The presence of these organisms in limestone & coral reefs can lead to erosion. This is caused by grazing animals who eat the Cyanobacteria and consequently decrease the amount of limestone present. The effect of this is illustrated below.
Erosion caused by Endolithic Cyanobacteria
This can sometimes produce fantastic "Biocarst" shapes.
|Hot Spring at Yellowstone Park: The dark color is due to the presence of Cyanobacteria.||Limestone deposit at Yellowstone Park. The localized areas of green are due to the presence of Cyanobacteria|
Stromatolites (Stromatoliths) are large columnar Calcium Carbonate structures produced byCyanobacteria. They accumulate slowly over immense time-spans. These were abundant in primeval times and constitute some of the oldest fossils. They can still be found today, particularly in Australian Tidal Flats. They are multilayered deposits that form in shallow pools where the climate is warm. The oldest Stromatolites are from the Precambrian and are 2.7 Billion Years-old!
CBs are thought to be the oldest Oxygen producing organisms. They profoundly changed the earth's atmosphere and allowed for the evolution of organisms that can use oxygen for respiration.
Illustration showing Fossil Stromatolites
Limestone deposit from ancient Cyanobacteria
(Glacier Park, Montana)
Living Stromatolites on the Beach
Stromatolites under water.
Some are Symbiotic
Cyanobacteria are involved in several symbiotic associations. CBs can fix atmospheric N which becomes available for its symbiotic partner.
Lichens: Cyanobacteria are frequently the Photosynthetic partners of Fungi that compose Lichens. Lichens are important pioneer organisms which inhabit extremely difficult sites that may be dry, hot, cold,windy or all of the above.
Upward Growing Root Nodules
Cross Section through a root nodule showing the dark zone that contains Cyanobacteria.
Long Section through a Root Nodule: The dark areas contain Cyanobacteria.
Commercial Cross Section showing the "Algal Zone" which contains CBs
Thin section showing the Cyanobacteria in the "Algal Zone".
Nostoc Ball (Colony)
Microscopic View of a Nostoc Colony
Nostoc Filaments seen with Phase Microscopy
Individual Noctoc Filaments from a large Colony
|Spirlina sp. have a Spiral filament Morphology but the individual cells resemble those of Oscillatoria.|
Filaments may be Branched, Unbranched or Clustered
Cyanobacteria are Prokaryotes.
They have No Nuclear Envelope &
No Membrane-Bound Organelles
They have Photosynthetic Thylakoids which contain Chlorophyll a and the other photosynthetic pigments.
These are Invaginations of the Plasmalemma.
Cyanophycin Granules (CPG) contain Amino Acids carbohydrates.
|Heterocysts seen with different types of Light Microscopy|
Heterocyst seen with an Electron Microscope
Heterocysts are the sites for the fixation of atmospheric Nitrogen.
They are Vegetative cells that are converted into Heterocysts.
The Thick Cell Walls are relatively impervious to Oxygen and this helps to create an anaerobic environment inside the Heterocyst.
The internal Membranes are thylakoids that have lost Chlorophyll. They provide the sites for Nitrogenase.
Other cell contents are generally lost. This helps to explain the lack of detail seen with the light Microscope.
|SEM of Rivularia sp. showing the Pore (arrow) that connects the Heterocyst (H) to a Vegetative cell (V)|
Heterocysts are connected to the Vegetative Cells through a special pore in their end walls. These are much larger than the Microplasmodesmata.
Larger Image of an Akinete
Survive unfavorable Conditions
They contain Storage Products
Cyanophycin Granules (Amino Acids)
Provides a Buffering Microenvironment.
Some are Digestive Enzymes.
Provides Protection from the Environment this aids in
Center of Cell
Low light -> Many
High Light -> Few
Oscillatoria Thylakoids = 20% Dry Weight
Thylakoids have a Precise Spacing
These include the following Pigments.
C-Phycocyanins Absorb Green-Yellow Light (615-620A).
Allophycocyanins Absorb Orange-Red (650-670A)
C-Phycoerythrin Absorbs Green Light (495-570)
Pioneering Organisms contribute fixed nitrogen & some biomass.
They may be Free Living
Nostoc Balls can grow on bare soil including Volcanic Sites.
They can be Epiphytic and even Epizooic.
Their Symbiotic relationships with Lichens is ecologically important.
Other symbiotic relationships are significant of the plants which have them.
Azolla can carpet the surface of small lakes and ponds. This can be a major, local ecological effect.
The symbiosis with Hornworts (Anthocerophyta) may have ecological significance in Hawaii because Hornworts colonize disturbed sites like pig runs and runoff streams.
Cyanobacteria can grow in thermal Hot Springs where algal photosynthetic organisms can't survive. They deposit limestone in the process. However, this is an extremely slow process.
They can grow in low light environments due to their Phycobillin pigments.
They Release Carbon & Nitrogen Metabolites which can stimulate the growth of other organisms.
They can grow at low Oxygen levels and may enrich the local Oxygen concentration because the produce O2.
Resist Grazing by Protists this can lead to enhanced Cyanobacterial populations that can lead to "blooms".
Their relatively high tolerance to heat can lead to "blooms" caused by thermal pollution.
Link to Hawaiian Cyanobacteria from
Black - Dark Gray - Red - Green - Yellow - Filaments 5 - 10 cm - Tangled with other species