Together We Bring Science to your farm

Algae and Algal Blooms -

Understand the cause and RCI Treatments Available

About Algae

Algae grow almost everywhere in the world. They are a vital part of the aquatic ecosystem providing food and shelter to other organisms. They play a crucial role in the ability of an aquatic ecosystem to absorb Algae Crop

nutrients and heavy metals. In Australia there are at least 3000 freshwater species and we are still counting.

However, excessive growth of algae can reduce the aesthetic and recreational value of a water body, can trap litter and sediment, and reduce the holding capacity of a dam and cause smells and scum when decaying. Algal blooms may deplete oxygen concentrations in water which can smother fish, other animals and plant life, Floating algal masses can smother rice crops and prevent young plants from emerging, They block pipes, siphon tubes, irrigation channels and pumps severely impeding water flow. Certain blue-green algal blooms are toxic and cause a rash known as swimmer's itch, while powerful neuromuscular toxins released by other cyanobacteria can kill fish living in the water or the animals that drink the water. In certain conditions, cyanobacteria may form dense blooms, which may produce toxins that make seafood poisonous to humans. Even if the cyanobacteria do not produce toxins, blooms can cause water to have an unpleasant taste and odour.

Information on Algae - Quick Links

What Are Algae?

What do they look like?

Types of Algae

Problems associated with Blue-Green Algae

Causes of Algal Blooms

How to Control Algae

Coptrol Algaecide

Blue-Green Algae Safety Checklist

What Are Algae?

There is no easy definition of an alga. Algae are generally microscopic organisms, are generally thought of as simple aquatic plants which do not have roots, stems or leaves and have primitive methods of reproduction. However some algae display primitive animal features such as motility, while blue-green algae differ markedly from plants and all other algae, in that they have a cellular structure and function that is more common to bacteria than to the plant kingdom.

Algae live in a wide range of aquatic environments and are a natural component of most aquatic ecosystems. Additionally, a great many are also terrestrial, living in soil, snow, or in association with other organisms, especially fungi (as lichens), and animals. Aquatic algae are found in both fresh and marine waters. They range in size from large kelp (metres in length) to those visible only under a microscope.

What do they look like?

Algae vary considerably in size, shape, and growth form.

They can be:

Single celled
Many celled - either colonially or as filaments of cells; or
Elaborate plant bodies with differentiated cell types

Main habitat preferences:

Free floating in the water column (planktonic). These comprise the microscopic unicellular algae and colonial and filamentous algae, known as "phytoplankton".
Growing as a film on rocks on the bottom (benthic) or on plants growing in the water (epiphytic). These may be single celled or small colonial and filamentous species.
Growing out into the water column but attached to a substrate at one point. These comprise the larger filamentous algae, and macroalgae (eg. seaweeds).

Types of Algae

The main groups of algae found in Australian freshwater are:

Green algae (Chlorophyceae)	Diatoms (Bacillariophyceae)
Euglenoids (Euglenineae)	Blue-green algae (Cyanophyceae)

However there are also other less common groups of algae that do occur in freshwater.

Golden Brown Algae (Chrsophyta)
Crytomonads (Cryptophyta)
Dinoflagellates (Dinophyta)
Glaucophyta

Brown Algae (Phaeophyta)
Haptophytes
Red Algae (Rhodphyta)
Yellow-Green Algae (Tribophyta)

Identifying the algae to be treated.

Generally speaking, Coptrol will control all free floating and filamentous green algae including brown slime. The most common species of algae are:

Free floating - these are microscopic plants usually existing in suspension in the upper 60 - 90 cm of water often reaching bloom proportions making the water appear brownish or pea soup green. The natural die-off of this form can cause summer fish kills due to depletion of dissolved oxygen. Some species are known to be toxic to livestock, wildlife, and man or impart odour and taste problems.

Euglena, are commonly found in freshwater streams and ponds, reproduce rapidly and are especially common in warm seasons when they may form a green scum on the surfaces of storages, irrigation bays or drainage ditches.

Microcystis, a blue green algae has numerous small cells crowded within a gelatinous matrix, forming a colony which may be ovate (like an egg) or an open meshwork.

Dictyosphaerium Anabaena, are blue green species which grow in spirally coiled filaments, both species often occur as water blooms which can be concentrated by wind action.

Oscillatoria, cylindrical or sometimes slightly tapering, unbranched filaments. Some are tolerant of high levels of organic pollution and some are shade-tolerant and able to survive in water below blooms of green algae. It is implicated in irritation of skin and mucous membranes suffered by people swimming.

Filamentous, also known as "pond moss" or "pond scum" these threadlike algae often occur in huge greenish masses floating upon the waters' surface. They can form dense mats in static water or long, rope-like strands in flowing water.

Its filaments consist of series of cells being joined end to end giving a thread-like appearance. This form begins growing on the bottom or substrate and then lifts to the surface as buoyancy grows due to its production of oxygen. This form of algae may seem cottony, slimy, or coarse in texture.

Spirogyra, - very common green algae which feel like wet, soapy hair, bright green often found free floating in static water near the surface or in masses in the sediment.

Chlorella, a small grass-green plant which usually stores starch.

Hydrodictyon, (Anacystis) - probably the most common toxic algae occuring in farm dams, usually form greenish-yellow bubbly masses in still or nearly still water. The plant cells are arranged like a small hair net.

Cladophora - filaments are usually about the thickness of a human hair and are composed of long,cylindrical, thick-walled cells. The filaments are thickly branched, coarse and green to dull brownish green depending on growth stage and muddiness of the water.

Mats of Nitella and Chara have a wiry, coarse texture as well as a slightly fishy odor. The common name for these algae is stonewort due to the very coarse, sandpapery feel to the mats.

Chara - dark grey-green with orange or green pinpoints on the branches. Chara often grows at the bottom of lakes in water one to six metres deep and is usually more noticed in droughts when the water level drops.

Nitella - thrive in water less alkaline than Chara. The plants are greener and are distinctly branched. Both are found in ricefields when the crop is thin.

Green Algae

Green algae range in size from microscopic to large plants, and can be single celled, colonial, or filamentous. Some of the single celled and colonial green algae have small tails or "flagella" attached to each cell, with which they use to swim. However many green algae are non-motile. Green algae may be either planktonic or attached. They show the greatest diversity of shapes, sizes and species of any group of freshwater algae. Green chloroplasts are frequently observable within the cells of green algae when looked at under a microscope.

Blue-Green Algae

Blue-green algae or Cyanobacteria are microscopic cells that grow naturally in Australian fresh and salt waters. They are a type of bacteria, but in some ways act like plants by using sunlight to manufacture carbohydrates from carbon dioxide and water, a process know as photosynthesis. In doing so, they release oxygen. They grow in dams, rivers, creeks, reservoirs, lakes and even hot springs. blue green algae bloom

Blue-Green Algal Blooms

When blue-green algae bloom, that is, grow to large numbers, they can form thick accumulations on the surface of the water. These accumulations are commonly known as scums. Blue-green algal scums form when large numbers of the algae float to the water surface using vesicles within their cells that they inflate with gas. Coming close to the surface enables them to gain maximum sunlight.

Wind pushes the floating algae across the water, concentrating scums against leeward shores. Scums can vary from small dots (blue-green algal colonies) resembling green dust floating on the water at the beginning of a bloom, to thick paint-like accumulations on the surface during the height of a bloom. Blooms are often green or blue-green but can also be white, brown, blue, yellow-brown or red. Wind movement, bleaching by sunlight, and other blooming algae, can cause swirling patterns of a mixture of these colours in scums.

While the problem is not new, it has increased in recent times because of our land and water management practices and seasonal droughts.

Water affected with blue-green algae usually smells and tastes unpleasant so that people are unlikely to drink it, however, take care to avoid skin contact, see the blue-green algae safety checklist for further details.

Blue-green algal blooms happen when there are high nutrient levels, low flows in rivers, low wind and high temperatures. There was a severe blue-green algal bloom over 1000 km long in the Barwon-Darling River system in October and November of 1991. This bloom impacted greatly on water supplies, agriculture, fish and aquatic animals, tourism and recreation.

Problems associated with Blue-Green Algae

Unpleasant Odours & Tastes.
Filters on pumps and machinery clog.
Large fluctuations in pH.
Deoxygenation due to decomposition endangers fish.
Increased costs of operating water treatment plants.
Poor aesthetics spoil recreation and tourism.
Poisoning of humans & livestock.
Skin irritation in humans.

Blue-green algae produce highly potent toxins

The main cause of concern about blue-green algae is the ability of some to produce highly potent toxins. There are four different forms of toxins that can be produced:

Hepatotoxins: These attack the liver and other internal organs of the poisoned victim. Some have also been identified as cancer promoting substances.
Neurotoxins: These act as neuromuscular blocking agents, leading to respiratory arrest.
Endotoxins : These are contact irritants, and can cause severe dermatitis and conjunctivitis in people coming into contact with the algae through swimming or showering. They may also cause stomach cramps, nausea, fever and headaches if consumed. Their presence in airborne droplets can cause asthma. Some are also thought to be possible tumour promoters, although this has yet to be shown.
Non-specific toxins: These are relatively slow acting general toxins which progressively damage most organs, including the liver.

Stock deaths

In Australia no recorded human deaths have been attributed to blue-green algal toxins. The best documented case of human deaths occurred in Brazil, where around 75 dialysis patients died after direct exposure to toxins in their dialysis fluid. However, many stock deaths have been documented. The first scientifically documented case of an algal bloom causing deaths was in South Australia's lake Alexandrina in 1878, where cattle, pigs and sheep died within hours of drinking contaminated water.The toxins produced can persist in water for weeks. The toxins can also be concentrated by shellfish, which poses a potential health risk if they are consumed.

Toxic Blue-green algae

The four main toxic blue-green algae in Australia are:

Anabaena, Microcystis, Cylindrospermopsis and Nodularia.

Anabaena, and Microcystis are the two main bloom-forming genera in Australian waters.

Anabaena forms long chains of cells, called a trichome, which sometimes grow in a spiral, depending on the species.

Microcystis aeruginosa is most common in lakes and reservoirs. It forms irregularly shaped colonies of cells up to 1 to 2 mm wide that can be visible to the naked eye. Microsystis blooms can be quite persistent lasting for months, or even years in some cases.

Nodularia often forms thinner scums than those of Anabaena and Microcystis blooms. Nodularia, like Anabaena, forms chains of cells or trichomes. Although it occurs in fresh waters, it is more common in brackish waters.

Cylindrospermopsis is commonly thought of as subtropical blue-green algae, but it also occurs in more temperate regions during the summer, including parts of Australia. It has very tiny cells that form chains or trichomes. It is a freshwater species, and causes problems in town water supply systems due to its highly potent toxins.

Irritant Blue-green algae

Not all blue-green algal species are toxic, and even different strains of the same species may differ, with some being highly toxic and others non-toxic.

All blue-green algae however, contain lipopolysaccharides, which act as contact irritants, Even if the other more potent blue-green algal toxins are not present, the presence of these contact irritants may make the water unsuitable for body contact or recreation if the blue-green algae are present in bloom proportions.

A number of other blue-green algae have been shown to be toxic overseas, but not yet so in Australia. Therefore these too should be treated with caution when present in bloom proportions.

Causes of Blooms

High nutrient load

Blue-green algal blooms are natural phenomena and while it is not exactly clear what triggers a bloom, excess human sources of nutrients such as fertilisers and sewage certainly can increase the intensity of blooms (i.e. greater number of algae).

Thermal stratification

One of the most important factors triggering blue-green algal blooms appears to be a lack of mixing of surface and deeper water layers in a river or reservoir. In lakes and reservoirs mixing is mainly controlled by wind and temperature. Through the summer months the surface waters heat up resulting in a warmer top layer and cooler bottom layer which do not mix. In rivers, mixing is mainly caused by flow. Flows from headwaters can decrease or stop during drought conditions allowing thermal stratification to develop. Weirs and extraction of water for irrigation and stock watering also reduce flow in rivers.

Algae float to surface

Some blue-green algae can float to the surface under these conditions having access to all the light in the top waters (photic region) and nutrients in the top and bottom waters. This allows the algae to flourish and bloom. Some other algae are motile and can swim to the photic region under these conditions.

Many other factors play a role in the formation of blue-green algal blooms including temperature, salinity, zooplankton grazing, pH and turbidity.

Blue-Green Algae Safety Checklist

Regard blooms as toxic until water is tested.
Avoid skin contact: wear rubber gloves when collecting.
Inspect all dams, ponds, troughs regulary in hot weather.
Isolate all people and stock from affected areas.
Make sure an alternative drinking water supply is available to stock.
Contact veterinarian if animals show symptoms of poisoning.
Boiling algal water will not make it safe.
Blue-green algal toxins are colourless, odourless, and can remain present in the water for weeks after the blue-green algae have disappeared.
Do not use water that has blue-green algae in it on plants being grown for human consumption, particularly for spray-irrigated salad and leafy vegetables, because dried algal cells on the leaves can remain toxic for several months.

Do not:

Drink or swim in it.
Rinse feestuffs in it.
Eat fish, seafish, etc caught in affected water.
Spray or irrigate crops with it.

Click here for Coptrol - How to Control Algae

Click here for application rates

Click here for Coptrol Bibliography

Click here for Coptrol Frequently Asked Questions.

Click here for information on Coptrol and Environmental Safety

If you have further questions on algae control click here

If you wish to purchase Coptrol click here

COPTROL WILL NOT CONTROL AQUATIC WEEDS

Privacy Statement Terms Of Use