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Cyanobacteria in Ponds & Lakes

Cyanobacteria identification of some of the common species found in and around lakes and ponds. Analyzing samples of potential cyanobacteria under microscope is the best way to confirm if you have a harmful algal bloom.

Dolichospermum (previously known as Anabaena)

A type of blue-green algae, is found in damp soil and in shallow water as plankton. Dolichospermum can be found as a colony or as single cells. Dolichospermum will cause blooms during summer months or months with increased temperatures. Dolichospermum (anabaena) produces a green paint like film at the water surface.

Dolichospermum under microscope

Dolichospermum bacteria form cells that resemble beads or barrels. These cells connect end to end creating filaments that look like a pearl necklace. These filaments can either be straight, curved or form a spiral. Filaments may include heterocysts, cells that fix nitrogen. The heterocysts are larger than the normal cells and lack color. They are irregularly dispersed in the colonies.

Under a microscope, dolichospermum is similar in appearance to nostoc.

Is dolichospermum harmful?

Dolichospermum can produce a number of cyanotoxins. These toxins include microcystin, anatoxin, cylindrospermopsin, and saxitoxin.

Microscopic view of Dolichospermum blue-green algae showing spiral and filamentous structures with bead-like cells, relevant to cyanobacteria identification and pond maintenance.
Surface of water showing blue-green algae bloom, with a green film and bubbles, indicative of Dolichospermum presence in aquatic environments.

Dolichospermum surface film

Microscopic view of Dolichospermum blue-green algae, showing bead-like cells forming filaments resembling a pearl necklace, relevant to cyanobacteria identification.
Microscopic view of Dolichospermum algae, showcasing bead-like and spiral filaments, relevant to cyanobacteria identification and pond health.
Microscopic view of Dolichospermum algae filaments resembling beads and barrels, showcasing heterocysts and filamentous structure, relevant to cyanobacteria identification and pond health.
Microscopic view of Dolichospermum filaments, resembling a wavy green strand with bead-like cells, highlighting characteristics of cyanobacteria.

Microcystis spp

A type of blue-green algae, is a single cell, but can form colonies with hundreds of cells. When the colonies form, they float to the surface of the water. When cells collect on the surface of the water, this is referred to as a "bloom." Microcystis aeruginosa is found in freshwater with high nutrient levels.

Microcystis blooms usually peak during the warmest months of the year. Growth drops off in the water column in cooler weather. Cells can lay dormant in bottom sediment for extended periods of time.

Microcystis under microscope

Each cell is spherical or ovoidal in shape, but the colonies can vary in appearance.

Is microcystis harmful?

Microcystis can be harmful as it has the potential to produce cyanotoxins, including microcystin and anatoxin. These toxins can pose risks to human health and aquatic life when present in high concentrations.

Even if there is not a current microcystis bloom, scums that have dried along shorelines can still be a threat. These microcystis cells may still contain high concentrations of microcystin for several months after drying. The toxins can dissolve back into the water.

Microscopic view of Microcystis colonies, spherical and ovoidal cells clustered, relevant to cyanobacteria blooms and potential toxin production.
Microscopic view of Microcystis cells, spherical and ovoidal shapes, related to harmful cyanobacteria blooms and potential cyanotoxin production.
Green microcystis bloom on water surface reflecting trees, indicating potential cyanotoxin presence in aquatic environments.

Microcystis bloom

Microscopic view of Microcystis colonies, spherical and ovoidal cells clustered, relevant to cyanobacteria blooms and potential health risks.
Microscopic view of Microcystis colonies, spherical and ovoidal cells, relevant to cyanobacteria blooms and their potential health risks.
Spherical colony of Microcystis cyanobacteria under microscope, displaying dense green cells, relevant to pond health and cyanotoxin risks.
Microcystis colonies under microscope, showing spherical and ovoidal cells, relevant to cyanobacteria blooms and potential toxins.

Nostoc

A type of blue-green algae, can be found in soil or floating in calm water. Colonies of nostoc form green jelly-like blobs.

Nostoc under microscope

Within the colonies, spherical cells are linked in chains and held together in a gelatinous structure. Similar to Anabaena, Nostoc has heterocysts that fixate nitrogen.

Is nostoc harmful?

Nostoc can produce the cyanotoxin called microcystin.

Microscopic view of Nostoc cyanobacteria with green gelatinous chains of spherical cells, relevant to cyanotoxins and pond maintenance.
Hand holding green jelly-like Nostoc algae by the water, illustrating potential cyanobacteria hazards in pond maintenance.

Oscillatoria

Oscillatoria is a filamentous cyanobacteria or blue-green algae, which is found in freshwater. This type of bloom is a benthic cyanobacteria. It forms mats which grow in the sediments of lakes and ponds. Oscillatoria can be found in tangled mats or as one cell.

Oscillatoria under microscope

Oscillatoria are dark green filaments which are unbranched. These filaments consist of a series of cells which look like stacked coins. Oscillatoria moves through water by secreting mucilage to push itself in the opposite direction.

Other similar types of cyanobacteria include phormidium, planktothrix, and limnoraphis.

Is oscillatoria harmful?

Oscillatoria can produce the cyanotoxins microcystin and anatoxin.

Dark green, unbranched filamentous cyanobacteria, resembling stacked coins, representing Oscillatoria under a microscope.
Microscopic image of Oscillatoria filaments, unbranched dark green cyanobacteria with stacked coin-like cells, relevant for identifying harmful blue-green algae in freshwater ecosystems.
Microscopic view of Oscillatoria filaments, dark green unbranched cyanobacteria resembling stacked coins, surrounded by sediment particles, illustrating characteristics relevant to freshwater pond ecosystems.
Microscopic view of Oscillatoria cyanobacteria filaments, dark green unbranched structures resembling stacked coins, amidst organic material in freshwater sediments.
Microscopic view of Oscillatoria filaments, dark green, unbranched, resembling stacked coins, highlighting characteristics of cyanobacteria in freshwater environments.

Phormidium

A type of blue-green algae, found in freshwater streams, ponds and lakes. Phormidium can be found in tangled mats or free-floating in water.

Phormidium under microscope

Phormidium consists of a fine, smooth filament. The connected cells are square shaped. The end of the cell is tapered.

Is Phormidium harmful?

Phormidium can produce the cyanobacteria toxin anatoxin .

Microscopic view of Oscillatoria filaments, dark green unbranched cyanobacteria resembling stacked coins, relevant to discussions on harmful cyanotoxins in freshwater ecosystems.
Dark green cyanobacteria mats in shallow water, featuring textures and shapes resembling filaments and algae, relevant to pond health and cyanotoxins.
Microscopic view of green filaments resembling Oscillatoria cyanobacteria, showcasing unbranched structures and interconnected cells, relevant to pond and lake ecology.
Microscopic view of Oscillatoria filaments, dark green unbranched cyanobacteria with stacked coin-like cells, surrounded by fine green strands, relevant to pond algae discussion.
Microscopic view of green filaments resembling Oscillatoria cyanobacteria, featuring circular structures and fine, smooth strands, relevant to discussions on harmful blue-green algae in freshwater environments.

Lyngbya Lyngbya in Ponds: Identification, Hazards & Control

A type of blue-green algae, found in freshwater streams, ponds and lakes. Lyngbya forms dense mats at the bottom of water bodies. These mats are often dark in coloration. The benthic cyanobacteria (bottom growing) can float to the surface due to the trapped gasses in the mats. When lyngbya mats float at the surface they oxidize and shift in color to yellow-orange.  

Is Lyngbya toxin producing?

Lyngbya can produce a number of cyanotoxins. These toxins include saxitoxins, aplysiatoxins, lyngbyatoxins, and lipopolysaccharides.

Microscopic image of Phormidium filament, showing smooth, tapered cells connected in a linear arrangement, relevant to discussions of cyanobacteria in freshwater environments.
Microscopic image of cyanobacteria filaments, showing a green, unbranched filament with square-shaped cells and a tapered end, alongside a spherical cluster of cells, relevant to identifying harmful algae like Phormidium and Lyngbya.

Aphanizomenon

A type of blue-green algae, found in freshwater streams, ponds and lakes. Aphanizomenon can forms clusters of filaments which look grass clippings.

Aphanizomenon under microscope

These filaments form linear chains called trichomes. They are unbranched. The individual cells within a filament are typically cylindrical or barrel-shaped.

Is Aphanizomenon toxin producing?

Aphanizomenon can produce a number of cyanotoxins. These toxins include anatoxin, saxitoxin and cylindrospermopsin.

Microscopic view of Lyngbya cyanobacteria forming dense mats with elongated, hair-like structures, relevant to pond maintenance and cyanotoxin information.
Microscopic view of Aphanizomenon filaments, showcasing unbranched trichomes with cylindrical cells, relevant to cyanobacteria identification and pond maintenance.
Cylindrospermopsis filaments under a microscope, showcasing cylindrical to rectangular cell shapes, relevant to cyanobacteria identification and pond maintenance.
Microscopic view of Aphanizomenon filaments, showing unbranched trichomes in freshwater environments, relevant to cyanobacteria identification and pond maintenance.
Microscopic view of Aphanizomenon filaments, showcasing unbranched chains of cylindrical cells, relevant to identifying cyanobacteria in freshwater environments.

Cylindrospermopsis

Cylindrospermopsis is a cyanobacteria species found in ponds and lakes. Filaments are generally found free floating in water.

Cylindrospermopsis under microscope

Each filament consists of connected cells that are cylindrical to rectangular in shape and a tapered end cell. The end cell can be pointed.

Is Cylindrospermopsis harmful?

Cylindrospermopsis can produce the cyanotoxins cylindrospermopsin and saxitoxin.

Microscopic image of Aphanizomenon filaments, displaying unbranched trichomes with cylindrical cells, relevant to cyanobacteria identification and pond health.

Woronichinia

Woronichinia is a type of cyanobacteria found in ponds and lakes. It produces a film at the surface of the water which can range in color from green, blue-gree, yellowish-brown, or white.

Woronichinia under a microscope

Woronichinia produces dense round or oblong colonies of cells. Woronichinia can be confused with other colony forming bacteria like microcystis. Colonies of woronichinia cells are formed within a mucilaginous film. The colony shape are similar to the shape of pine pollen under a microscope. Unlike microcystis, the woronichinia cells are only one layer thick, with the center of the colony being void of cells.

Is Woronichinia harmful?

Woronichinia is a toxin producing cyanobacteria. The type of toxin produced by woronichinia is anatoxin.

Microscopic view of Woronichinia cyanobacteria colonies, showing dense, round shapes within a mucilaginous film, relevant to pond health and cyanobacteria identification.
Lily pads floating on the surface of a pond with a greenish-brown film of Woronichinia cyanobacteria, illustrating potential cyanobacterial growth in aquatic environments.