Preventing Microcystis Blooms

Several measures can be taken to prevent microcystis blooms. As noted in a previous post, blooms occur in waters with enhanced and added nutrients. Efforts to reduce the infiltration of nutrient run off from farms and agricultural are a great start to reducing the chances and severity of blooms. Fertilizers from agricultural areas can increase the likelihood of algal blooms due to their high levels of phosphorus and nitrogen. For homeowners living near water sources, this can also mean simply watering lawns carefully and preventing runoff from nearby waters.

Water agencies that control places like dams can help prevent blooms by periodically flushing water through to promote the mixing of layers, as blooms typically bloom in stagnant waters that have not been mixed for long periods of time. Many states have also begun to monitor algae density and distribution in order to better understand environmental factors that lead to their presence and to create preventative strategies to limit their spread.

What effect do microcystis have on plants and animals?

The ingestion of microcystis- infected waters can be harmful to the health of many different species. Humans swimming in waters with high levels of microcystis have experienced such things as skin burns and rashes and blistering of the mouth. Inhalation or ingestion can also cause nausea, vomiting, diarrhea, fever, and pneumonia. In severe cases, humans and other animals have experienced liver malfunctions and even failure as well as the promotion of tumors. While no human deaths have been reported due to exposure, other animals have died.

The most common source of exposure to humans is drinking water. Unfortunately, many water treatment plants are unable to completely remove the microcystis that forms in their reservoirs and clog their waterways. Children are often exposed when playing in contaminated waters and unintentionally swallowing the water. While microcystis only remain in the bodies of edible fish for a short period of time, those who frequently consume sport fish are at higher risks of exposure.

Ultimately, microcystis pollutes the aquatic system, lessens the quality of drinking water, and decreases the oxygen levels of water, putting aquatic animals at a higher risk of death. When the colonies die and sink to the bottom, they also make the surrounding water foul smelling and bad tasting. In order to avoid exposure, people should stay out of waters containing blooms and only drink treated water.

What are Microcystis blooms and why are they a problem?

Microcystis algal blooms are the genus of freshwater cyanobacteria. It is a single-celled planktonic blue-green type of algae that blooms naturally in surface waters. The single cells organize themselves into colonies that begin spherically, but eventually lose shape as they grow in surface area. Their buoyancy is a result of intracellular structures called gas vesicles which allow them to float when water is stable. Colonies range from a few to hundreds of cells, making it difficult to see anything over a couple inches below the water. When they bloom rapidly, they form dense blooms that can be very harmful to the environment. As they grow, they produce toxins that remain inside their cells until they die, at which point the cells break open, releasing the toxins into the water around them. If this toxin containing water is ingested, it can pose serious threats to the health of many different aquatic species, terrestrial organisms, and humans.

Microcystis blooms typically occur in in warm and stagnant waters with low salinity. They are most prevalent and dense in eutrophic waters -  waters containing high levels of phosphorus and nitrogen. Blooms can only occur through photosynthesis, so these algal plants also require sufficient light sources. They bloom during the warmest times of the year, typically from the late months of summer to the end of fall, and live for about two to four months. During hotter years, blooms are more common, live longer, and more severe. Though most blooms remain visible at the surface, they can sink if they become dense enough, making them invisible to the the human eye.