Periods of enlarged algal growths that affect water quality. Algal blooms indicate potentially hazardous changes in the chemistry of water. They can be perceived through the color of the water, which is usually a blue-green color that is made up of bacteria. Many algal blooms arise due to an overabundance of nutrients such as nitrogen and phosphorus within water, which produce greater degrees of vegetation and algae. The effects that algal blooms have on humans are toxicity-related and can also cause harm to all living marine animals, and birds.

But algal blooms do not necessarily have to generate toxins to be considered detrimental to the environment. Blooms are capable of sucking out oxygen from water by causing anoxic circumstances, and can also prevent light from reaching organisms in deep water. However, some algal blooms can have a positive impact by increasing the amounts of phytoplankton in the water. The aquatic life depends on phytoplankton and algal blooms are a good sign of changes in the environment not only throughout water sources but including on land.