Photo: Enikő Krasznai
When the growth of algae within a certain place and time frame shows an exponential tendency, (like viruses in a pandemic), this process is called an algae bloom. If neither nutrients, light or temperature limit their growth, then only the rate of their reproduction will determine their quantity. When an algae bloom occurs, a body of water that has been transparent turns to a dense green color and can possibly emit an unpleasant smell or be unpleasant to touch. Algae blooms are
usually caused by pollution of the water and an overload of nitrogen and phosphorus. This phenomenon can cause a lack of oxygen in the water, potentially leading to mass death in the fish population and the invertebrate organisms they consume. Blooms of certain algae species are known to release toxins that cause skin rashes and diarrhea. Local short-term algae blooms have occurred on Lake Balaton, but have not caused widespread anoxia or health problems yet.
Algae, like many plants, need carbon, oxygen, phosphorus and smaller amounts of other nutrients to grow. The main carbon source of the algae floating in water is the soluble carbon-dioxide released from the air, oxygen and hydrogen gained through photosynthesis during the breakdown of water; as well as nitrogen and phosphorus absorbed from the water. They can only use these nutrients in specific ratios, and no quantity of one nutrient can substitute another nutrient. Therefore algae growth is restricted by the nutrient available in the lowest quantity relative to the required ratio.