Causes And Removal Of Cyanobacteria (Blue-Green Algae) In A Fish Pond

Cyanobacteria, commonly known as blue-green algae, are micro-organisms similar to bacteria without a nucleus and organelles. They contain chlorophyll and can photosynthesize which bacteria cannot. They have, thus, provided oxygen to Earth since time immemorial and enriched the atmosphere. They are found in oceans, lakes, ponds, damp soil, wet rocks, etc.

Cyanobacteria have evolved and adapted dramatically with modern changes in the climate. They have become accustomed to good UV lights, high temperatures, more saline levels in water and others. Although they are too small to be seen without a microscope, their colonies are visible from afar. Cyanobacterial blooms could be harmful to humans, animals or our ecosystem.

Causes of Cyanobacteria

The changes in the climate have had a significant boost in the increase in the growth of cyanobacteria. Change in the hydrologic patterns, enrichment of anthropogenic nutrients, increased supply of nutrients like oxygen and phosphorus, enhancement in carbon dioxide levels and rise in temperatures of water had a massive effect on the growth of cyanobacteria. Contact with other biota and vertical stratification also are major causes behind the development of cyanobacteria.

• Nutrient pollution

  Humans have been polluting the water for many years. Cyanobacteria love to thrive upon nutrient pollution, caused due to industrial, agricultural or urban practises as well as eutrophication from waterways. As a result, more frequent cyanobacterial blooms are visible.

• Climatic changes

  The changes in the climatic conditions have created a massive impact on the growth of cyanobacteria. The temperature has risen all over the world, and changes in rain patterns have been noticed. All these have stimulated the growth of cyanobacteria. Higher temperatures and longer intervals of thermal stratification have led to more cyanobacteria.

  The growth of cyanobacteria is heavily dependent on the availability of nutrients. The increase in temperatures and the altered patterns of rainfall have made more nutrients available, thus causing larger cyanobacterial blooms.

• Cyanobacterial blooms

  Cyanobacterial blooms take in carbon dioxide from the atmosphere, turning lakes into sinks. During photosynthesis, they emit large amounts of methane, a greenhouse gas, which causes global warming. Thus increase in water temperatures stimulate the growth of cyanobacteria, which in turn emits methane gas to cause global warming.

• Feeding food to the fish

  The food provided to the fishes in the pond affect the growth of cyanobacteria. The fish waste provides nutrients for the growth of cyanobacteria. Hence, if excess food or low quality of food is offered to the fishes, then more fish waste will be created, paving the way for the growth of cyanobacteria.

Dangers of cyanobacteria

The growth of cyanobacteria is a cause of concern for many and has become a source of danger. They have a tremendous impact on wide areas:

• Impact on environment

  They are a danger to the plants, fishes and micro-organisms presiding in the water and disturb the harmony of the water ecosystem by emitting cyanotoxins in the water

• Impact on economy

  Many business sectors like agriculture, fisheries, tourism and real estate sectors near water bodies have experienced economic losses due to cyanobacteria.

• Impact on health

  Cyanobacteria release cyanotoxins which are very harmful to the health of humans, animals as well as the environment. Humans consuming cyanotoxins or affected fish can experience problems related to the liver, nervous system, skin or increased size of the tumour.

  Hence it is crucial to curb the growth of cyanobacteria as they can prove to be harmful to us as well as the environment and disrupt the balance of the ecosystem. So it would be beneficial to keep them in check.

Removal of cyanobacteria

Cyanobacteria constitute a significant threat to the water bodies and the organisms living inside. It becomes essential to manage them properly to keep the water bodies safe. There are several methods through which cyanobacteria can be controlled:

• Chemical method

  This is widely regarded as the most common methods adopted, but, at the same time, also the most harmful for the environment. The chemical treatment uses copper sulfate and hydrogen peroxide, which causes the death of the cyanobacteria cells. This leads to the emission of huge amounts of cyanotoxins. But this chemical treatment is not a permanent solution to the problem as the cyanobacteria can re-emerge later.

• Reducing nutrition

  The growth of cyanobacteria can be significantly thwarted by reducing the amount of nutrients available to them. But this is a major problem because controlling nutrient levels are not easy. There is a wide range of sources of nutrient pollution which include agriculture, industries, animal farming, fossil fuels, stormwater, wastewater and households, among others. Having effective control over all these sources is very difficult in practice.

• Ultrasonic method

  This is a much safer method to control the blooms of the cyanobacteria where there is no need of using harmful chemicals and is yet effective. The ultrasonic system creates a sound barrier on the upper layers of the water, which hinders the cyanobacterial growth.

  Due to this treatment, the cyanobacteria cannot move up to the surface of the water, and thus its growth is controlled. It does not harm the cyanobacteria completely but reduces them to about 90%. Thereby the ultrasonic treatment prevents the growth of cyanobacteria and maintains the ecological balance of the water ecosystem.

• Using UV Pond clarifiers

  UV clarifiers use good UV lights for destroying the cells of cyanobacteria, clumping them together and removing through the filter system. The good UV lights pass through the water and destroy the cells, leaving behind clean water.

  It is the safest option if there are a number of fishes present in the pond and is very effective as well. It will hinder the growth of the cyanobacteria as well as keep the fishes healthy and maintain the balance of the water body.

Final Word

It is crucial to understand the dynamics of the aquatic ecosystem and we should keep an eye on the means of removal of cyanobacteria. We should be careful that they do not harm the water and the other organisms living inside it and disturb their harmony. Hence the use of good UV lights or ultrasonic sounds has become prevalent as safe and secure means to carry out the process.