What's growing in my water?

Wendy Gill, Senior Land Services Officer - Mixed Farming

With the heat of summer well and truly upon us, a lot of our on-farm monitoring involves checking water.  As a result a lot of people are noticing changes to their water quality as well as different types of aquatic growth.

There are many different types of aquatic growths, including aquatic plants and different forms of algae that form in our freshwater storages. This is particularly more evident to water users the drier it gets in our water sources and especially in periods of drought.

Often we scratch our head trying to work out if the things we see floating in our water are aquatic plants, one of the many free floating algae types that has no root hairs, stems or leaves and that act similar to microorganisms or if they are indeed Blue Green Algae (cyanobacteria) which acts differently to other common forms of algae as it has a cellular structure, and functions more like a form of bacteria than other algae’s that exhibit distinct plant features.

I also get asked "where did the algae or aquatic plant that is now in my water source come from?" It is important to remember that algae is naturally occurring within our environment.  So often, even in good years, dams for example may have algae present, but the environmental condition at that time mean’s it might not be as visible to us.

Algae lives in a wide variety of environments; in the soil, snow, water and symbolically on other animals. It can be made up of many cell types i.e singular of multi celled and be different shapes, colours and in many sizes, from the algae we see like seaweed/kelp in salt water marine environments to algae’s you can only see under a microscope.

Not all algae is bad…Some algae’s have a positive role to play in the environment such as in the aquaculture industries.  But sometimes with excess growth and blooms algae can affect both livestock, irrigation systems, waterways and infrastructure. Because algae is not static and water is constantly changing it’s state through differing conditions such as temperature, sunlight, runoff of pollutants, increase in nutrients to the water from storm’s, removal of sediment from topsoil in our paddocks etc,  water sources should be constantly monitored  and algae kept in check to maintain or improve water quality.

Most algae’s cause problems by blocking irrigation pipes, emitting strong odours and makes water taste bad, it has the potential to turn into algae blooms under the right conditions which become toxic to humans and livestock and make water sources look unhealthy and visually unappealing.

Algae treatment can be either through mechanical, by physical removal or chemical based. Regardless of the management action taken it should be done as a proactive step, and as early as possible to keep the growth of these organisms to a minimum and minimise the impact on your water system.  Which type of management you use will largely be driven by which group of algae’s are present in each of your water systems. The starting point is to always try an identify it.

There are different ways of identifying which type of algae or aquatic plant type you have in your water sources, it’s not easy and most are hard to distinguish between. The main groups of plants found in fresh water include:

  1. Filamentous Algae’s – also called Green algae’s or Macro Algae’s
  2. Plant structured Algae’s – i.e is free floating, roots or no roots present, differing leave types
  3. Blue Green Algae’s – also called Micro Algae’s
  4. Aquatic plants- such as azolla, cumbungi or sedges.

Within each group there are multiple different unique species, which can make it difficult to identify one particular type. Water NSW has developed a handy resource to distinguish between the algae groups.

If you suspect Blue Green Algae in your water source/s, contact your Local Land Services District Vet or Ag Advisory staff member to discuss water testing as this poses a serious risk to livestock, pets and humans. As a precaution, it is recommended that you remove stock access to prevent losses.

Additional resources:

Department of Primary Industries Primefact - Farm water quality & treatment

Department of Agriculture- Victoria

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