- Algae have a bad reputation. However, true algae provide several benefits to ponds. True algae are eukaryotes belonging to the Protista kingdom of single-celled organisms. Eukaryotic organisms are those whose cell nucleus has a membrane surrounding it. The organisms that give algae a bad rap are cyanobacteria, often called blue-green algae because they use photosynthesis and are commonly found in aquatic habitats. Cyanobacteria are prokaryotes of the kingdom Monera. Monera are also single celled, but they are prokaryotic, meaning the cell nucleus has no membrane. Cyanobacteria blooms can be hazardous to the health of humans, pets and aquatic life forms.
- Eukaryotic algae compete for resources against cyanobacteria, which makes them a beneficial protector for pond water. Both types of algae can flourish in warm, sunny water and favor waters rich in nitrogen and phosphorous. By using up resources that could help cyanobacteria bloom, algae help prevent cyanobacteria blooms from overtaking ponds and creating toxic conditions.
- Clumps of algae can provide protection for pond life. Smaller fish can use the algae clumps to hide from larger predators. Creatures such as fish, snails, frogs, newts and dragonflies can lay their eggs near algae for protection as well. Conversely, unchecked algae growth can crowd out other pond life by using up space and other needed resources.
- Algae make a nutritious food source for newly hatched fry (baby fish), whose size restricts their food options to the very smallest of particles. A population of zooplankton often develop with the algae. Eating the zooplankton gives fish such as koi their intense color. Also, algae are often the only naturally available food source for fish in the winter.
- Algae oxygenate pond water through photosynthesis. In photosynthesis, the algae can take carbon dioxide released from fish respiration, use it to make food and put oxygen into the water as a waste product of this process. Well-oxygenated water promotes the health of pond wildlife and helps to keep the water clear. Unfortunately, algae actually use oxygen from the water during the night, while photosynthesis is paused. Therefore, extreme algae growth can literally choke the life out of a pond. Pond enthusiasts must try to maintain helpful amounts of algae but prevent algae from becoming so prevalent that they cause harm.
