Algae Blooming

NSW Murray Regional Algal Coordinating Committee (MRACC) has provided all the invaluable information of the Blue-green Algae on this Blue-Green Algal Bloom Management website. MRACC is a public Service Committee which serves the public, water users and the Organisations who manage blue-gree Alage in the NSW Murray River catchment.
It was the Year 1878 when the first first Australian toxic bloom of blue-green algae was discovered in Lake Alexandria, South Australia.The reports of harmful blooms have been increased which are badly affecting the water use. In the Summer of 1991-1992, The world’s largest Algal Bloom was recorded  at the Barwon-Darling River System. The range of this poisionous bloom was 1000 km as authentically reported by the Blue-Green Algae Task Force 1992.

The algae are a polyphyletic and paraphyletic group of organisms. They are defined in differing ways, but are usually considered to be the photosynthetic organisms excepting plants. Using the term ‘plants’ in its most restrictive fashion, the algae are then photosynthetic organisms excepting the sister group to the Charales (i.e. the land plants). Such a definition allows inclusion of photosynthetic prokaryotes such as the cyanobacteria. The definition applied here is that the algae is that artificial subset of the photosynthetic eukaryotes which excludes the sister group to the Charales (land plants).

Algal bloom :- An algal bloom occurs when the numbers of algal cells increase rapidly to reach concentrations usually high enough to be visible to the naked eye. This high growth reproduction require favourable conditions such as high nutrient or light levels.

Many types of algae form blooms. Some of these blooms are harmless, but when the blooming organisms contain toxins, other harmful chemicals, or pathogens it is known as a harmful algal bloom, or HAB. HABs can cause the death of nearby fish and foul up nearby coastlines, and produce harmful conditions to marine life as well as humans.

Blue-green algae is the common name for several different types of algae. They are actually bacteria (Cyanobacteria) which are able to photosynthesise, hence the green colour. Cyanobacteria are bacteria that grow in water and are photosynthetic (use sunlight to create food and support life). Cyanobacteria live in terrestrial, fresh, brackish, or marine water. They usually are too small to be seen, but sometimes can form visible colonies. Cyanobacteria have been found among the oldest fossils on earth and are one of the largest groups of bacteria. Cyanobacteria have been linked to human and animal illnesses around the world, including North and South America, Africa, Australia, Europe, Scandinavia, and China. Cyanobacteria are the most common, but not the only, group of algae to form HABs.

Some cyanobacterial blooms can look like foam, scum, or mats on the surface of fresh water lakes and ponds. The blooms can be blue, bright green, brown, or red and may look like paint floating on the water. Some blooms may not affect the appearance of the water. As algae in a cyanobacterial bloom die, the water may smell bad.

Dangers of HABs

1. They spoil water quality when present in large numbers by producing odours or thick scums.
2. They can make drinking water smell and taste bad.
3. They can make recreational areas unpleasant.
4. Dense blooms can block sunlight killing other plants and animals.
5. When algae decompose they may use up oxygen in the water and cause fish kills.
6. Some cyanobacteria that can produce toxins that are among the most powerful natural poisons known. The toxins are poisonous to humans and may be deadly to livestock and pets.
7.  CyanoHABs can make people, their pets, and other animals sick. Often, the first sign that an HAB exists is a sick dog that has been swimming in an algae-filled pond. Children are at higher risk than adults for illness from CyanoHABs because they weigh less and can get a relatively larger dose of toxin.

Safety Precautions

We can protect ourselves, our family and our pets from exposure to HABs by following the instructions as under:-

1) Don’t swim, water ski, or boat in areas where the water is discolored or where you see foam, scum, or mats of algae on the water.

2) If you do swim in water that might have a HAB, rinse off with fresh water as soon as possible.
3) Don’t let pets or livestock swim in or drink from areas where the water is discolored or where you see foam, scum, or mats of algae on the water.
4) If pets (especially dogs) swim in scummy water, rinse them off immediately-do not let them lick the algae (and toxins) off their fur.
5) Don’t irrigate lawns or golf courses with pond water that looks scummy or smells bad.
6)  Report any “musty” smell or taste in your drinking water to your local water utility.

7) Respect any water-body closures announced by local public health authorities.


The Algal bloom can be prevented in the following ways:-

1) Algae need three things for optimal growth: light, nutrients and high temperatures. Therefore, By Lowering the nutrients, light and temperature available to the blue-green algae in the water supply will help reduce algal growth. The speed at which water is flowing and mixing is important in controlling light and nutrient availability to algal cells.

2)  Keeping livestock away from the farm dam or water supply.

3)  Avoiding run-off into water supply from fertilizers and pesticides

4) Taking some water treatment measures BEFORE a bloom starts; and if practical – changing mixing patterns or covering the dam/water supply to screen out light may help.