Cyanophyta 
Link to Dr. Smith's Web Page on Cyanophyta
Cyanophyta 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) |
fixed Nitrogen.Planktonic: There are only a few species but they are an
important source for
Reef Lagoon: Lyngbya majuscula is the most common Marine Species in Hawaii.
Rubble - Intertidal Zone in "Ooid Sand Grains"
Terrestrial
Surface Crusts which appear
lifeless, are revived following significant rains. These dry to a
brittle crust as the
substrate looses water.
These can be ecologically 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.
These can also be seen locally on abandoned,
dry lots. Heavy rains allow desiccated Cyanobacteria to revive. They form undulating
to round hydrated masses. These gradually shrink and crack as the substrate dries.
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 can live just below the surface of rocks. This sounds unbelievable but it is true. They may also survive in the cold dry soil of Antarctica. They become active when melt water appears.
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
Scytonema endolithicumOrganisms 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.
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| 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
Cyanobacteria 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.
Cyanobacteria use water (H20) as an electron source and produce Oxygen. Other photosynthetic bacteria use Hydrogen Sulfide H2S as an electron donor and produce Sulphur.
Fossil Cyanobacterium
 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.
Heterocysts are the cells which fix nitrogen for most Cyanobacteria.
 Heterocyst flanked bt two Akinetes: Both have Thick Cell Walls |
 Heterocysts of Anabaena isolated from Azolla. |
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. The fixed nitrogen supplied by Cyanobacteria allow lichens to inhabit substrates that are nitrogen deficient.
 Lichen with a Blue Color |
 Lichen showing Cyanobacteria inside |
 Hornwort (Anthocerophyta) |
 Hornwort with Endophytic Cyanobacteria |
 Azolla Plants (Dorsal View) |
 Individual Azolla Plant showing its Main Axis and Branches |
 Azolla Shoot Apex |
 Isolated Azolla Leaf: The dark area is due to the presence of Anabaena inside a pouch formed by the Leaf. |
 Section through an Azolla Leaf showing the chamber in which the N-fixing Cyanobacteria reside. |
 Anabaena isolated from an Azolla Leaf: note the Heterocysts and Photosynthetic Cells. |
 Cycas |
 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". |
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| Gunnera growing in Hawaii | |
 Synechococcus |
 Crococcus |
 Cells of Anacystis |
 Anacystis Colony |
 Nostoc Ball (Colony) |
 Microscopic View of a Nostoc Colony |
 Nostoc Filaments seen with Phase Microscopy |
 Individual Noctoc Filaments from a large Colony (Phase Microscopy) |
 Anabaena |
 Oscillatoria |
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 Oscillatoria Embossed |
 Planktothrix sp. |
 Lyngbya sp. |
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| Spirlina
sp. have a Spiral filament morphology but the individual cells resemble those of Oscillatoria. |
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Filaments may be Branched, Unbranched or Clustered
 Calothrix |
 Gleotrichia
Individuals |
 Gleotrichia Colony |
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 Tolypthrix |
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Electron Microscope Images of Dividing Cyanobacterial Cells |
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the filament.Cyanobacteria are Prokaryotes.They have No Nuclear Envelope &
No Membrane-Bound Organelles
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They have Photosynthetic Thylakoids which contain Chlorophyll a and the other photosynthetic pigments.
Thylakoids are Invaginations
of the Plasmalemma.
Cyanophycin Granules (CPG) contain storage Amino Acids.
Heterocysts have a Round Shape & Thick Cell Walls. They often appear to be devoid of contents at the light microscope level.
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 Embossed image of Anabaena showing the Thick Walls and Pores of a Heterocyst |
 Heterocyst as seen with Phase Optics |
| Heterocysts seen with different types of Light Microscopy | ||
 Heterocyst seen with an Electron Microscope |
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Heterocysts are the sites for the fixation of atmospheric Nitrogen
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Vegetative cells are converted into Heterocysts.
An Oxygen-free Anaerobic Environment is Required because Oxygen inhibits Nitrogenase which is the N-fixing enzyme.
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. These Pores can be seen at the light microscope level.
Locate the Pores in this Photo!!!!!
TEM of an Akinete
Larger Image of an Akinete
Survive unfavorable Conditions
They contain Storage Products
Cyanophyphtcin Granules contain storage Amino Acids & are noticeably present in resting cells.
Lipid Vacuoles can be seen.
Polyglucan Granules are present.
 Anabaena with a nearly translucent Sheath: Identify the Round Smooth-looking Cell. |
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The Sheath Provides a Buffering Microenvironment.
It may absorb damaging Ultraviolet radiation.
Some are Digestive Enzymes.
Function = Secretory?
Low light -> Many
High Light -> Few
Oscillatoria Thylakoids = 20% Dry Weight
Accessory Pigments
Thylakoids have a Precise Spacing
the Phycobilisomes which are attached to the Surface of
the Thylakoids
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)
Consequently, organisms with these pigments are
 Aerial View of a Large Cyanobacterial Bloom |
 Cyanophyte Bloom |
 Microcystis Bloom |
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Terrestrial Environments
Pioneering Organisms contribute fixed nitrogen & some biomass. Nostoc balls and crusts can grow on bare soil including Volcanic Sites.
They may be Free Living
They can be Epiphytic and even Epizooic.
Their Symbiotic relationships with Lichens is ecologically important, especially in the Arctic..
Other symbiotic relationships are significant for the plants which have them.
Azolla can carpet the surface of small lakes and ponds. This can be a major, local ecological effect. This can lead to eutrophication!
The symbiosis with Hornworts (Anthocerophyta) may have ecological significance in Hawaii because Hornworts colonize disturbed sites like pig runs and runoff streams.
Fresh Water
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 can expolit habitats that Green Algae can not.
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.
