In summer, as the weather and water warms up, life processes in water bodies become more active. We asked Dr. Judita Koreivienė, Chief Researcher, and Dr. Jūratė Karosienė, Senior Researcher at Nature Research Centre, to comment on the video made the owner of a water body, Aliaus Mazaliauskas from Alytus.
What can we see on the surface of the water? Under what circumstances can this be formed? Is it harmful for humans and fish or not? What measures should be taken by the owner of the body of water?
The material captures water blooms caused by cyanobacteria. During the bloom, cyanobacteria multiply rapidly forming aggregations and turning the water a bluish-green colour. In calm weather, they float to the surface of the water and form films. Water blooms are the most visible consequence of eutrophication in water bodies. Excess nitrogen and phosphorus compounds entering water bodies from the catchment due to intensive farming activities, unsuitable wastewater treatment systems, household chemicals and temperature are among the most important factors for the intensive growth of cyanobacteria and the formation of aquatic blooms. Therefore, water blooms are a common phenomenon in summer.
Studies have shown that up to 75% of bloom water bodies are harmful for humans and animals. Cyanobacteria synthesise and release toxic compounds such as cyanotoxins into the environment. Depending on their composition and concentration in the water body, cyanotoxins can cause allergic skin reactions, shortness of breath or digestive problems. Bathing in bloom water can cause signs of poisoning, such as general weakness, dizziness, difficult breathing, and tingling in hands and feet. Some cyanotoxins accumulate in the body and cause various chronic diseases (cancer, multiple sclerosis, accelerated Alzheimer’s disease, etc.). In addition, these toxins accumulate in fish and other aquatic organisms and can enter the human body through food.
Please note that the greatest risk to human and animal health comes after the end of the bloom, when cyanobacteria decompose and cyanotoxins enter the water. This is when cyanotoxin amounts are the highest and can persist for weeks to months.
Care should be taken in bloom water, as cyanotoxins can enter the body: do not dive, avoid swallowing water when swimming or playing water sports, do not allow animals bark at the water, and do not water gardens with bloom water. Allergy sufferers, young children and the elderly should be particularly careful.
To cope with the problem of water bloom, the first step is to find out and eliminate the cause – potential sources of nitrogen and phosphorus pollution. Subsequently, different measures can be taken to improve water quality, which should be chosen depending on the size of the water body, flow rate, as well as the intensity and nature of the bloom.
Lithuania’s bloom water bodies can be seen on an interactive map. You can also mark the water blooms you see yourself.
Mark bloom water body here: https://arcg.is/0jqvCn or
The map with bloom water bodies can be found here: https://arcg.is/1v5faT or
