Algae

Physical clogging of pumps, irrigation lines and aerators occurs when algal matter builds up in and around fixtures within the water body. This can cause major damage to irrigation systems and other infrastructure, as well as resulting in irrigation system down time causing possible drought stress on turf surfaces. Filamentous algae tends to pose a risk to inlets and aerators, which the smaller free flowing unicellular algae can build up within irrigation lines, causing blockages and clogging sprinkler nozzles.

Increased level of suspended solids occurs during algal blooms, particularly with high populations of unicellular algae. The algal cells become suspended in solution, causing problems during pesticide application by binding to pesticide molecules. For instance, it is understood that glyphosate will be quickly bound up in dirty water as it is attracted to organic particles, including algal cells.

Deoxygenation of water occurs in the water body as algal cells photosynthesise, using oxygen to create carbohydrates. This can quickly deplete the oxygen levels within the water, damaging aquatic life and encouraging anaerobic bacterial activity which generate toxic compounds during anaerobic respiration processes. Fish kill often results from oxygen depletion, and can be the first sign that water quality needs to be addressed. Larger fish will begin to die first as their oxygen requirements are higher. Some fish such as carp can be seen gulping for air at the water’s surface before death occurs; this is a sure sign that oxygen is low and action should be taken.

Toxic compounds can be released by some varieties of algae. Most commonly these are the cyanobacteria (blue / green algae). This group of algae are unicellular and will create compounds toxic to humans, livestock and wildlife. This presents health and safety issues for staff and clientele and if this algae is suspected an algal count and identification should be undertaken and action should be taken to control the bloom. Some blue / green algae are toxic when in contact with skin, and may be even more dangerous if ingested.

The use of algaecides is often unavoidable if blooms occur. Traditional methods included the application of copper sulphate (bluestone or blue powder) to the water body. Copper is toxic to algae and inhibits various chemical processes within the algal cells, including the electron transport chain in Photosystem 1. While this has often proved effective in controlling algae, the use of copper sulphate has many negative side effects. Copper is a cation with a strong charge and once in the water immediately begins to bond to negative molecules, precipitating out of the solution. This renders the copper cation useless in control of the algae and therefore excessive rates of copper sulphate are required, particularly in hard water. When precipitation occurs, the copper compounds then make their way to dam edges, staining lining materials and rocks a blue or black colour. In addition to this, excessive inputs of copper and sulphur into the water bodies can be toxic to aquatic plants and animals, as well as turfgrass that is irrigated with the water.

By using an algaecide based on a complexed or chelated copper, the above problems can be overcome, allowing turf managers to apply algaecides at much lower rates, and with confidence that the impact on the environment will be minimal. Copcide from Amgrow is an example of a complex copper-based algaecide. Delivering the copper to the water body in a complex molecule eliminates the problems associated with hard water and staining, as well as reduces the copper’s interaction with the environment.

Nutrient management within the water body is vital in minimising the likelihood of algal blooms. Like all plants, algae require nutrients to grow, particularly nitrogen and phosphorous. By allowing N and P to accumulate through the improper use of fertilisers, turf managers run the risk of encouraging major algal blooms. Regular water testing and monitoring nutrient levels are essential. Following the control of any algae within the water body, it is important to remember that the dead algal cells will result in a major release of nutrients within the water body. This can often cause secondary blooms and nutrient fixing products should be applied to prevent this.