Why is algae bad for the environment

O n 3 August , residents of Toledo, Ohio, woke to the news that overnight their water supply had become toxic. They were advised not only to avoid drinking the water, but also touching it — no showers, no baths, not even hand-washing.

About half a million residents of the city and surrounding area have relied on Lake Erie for water for hundreds of years. After the news broke on 3 August bottled water quickly vanished in concentric circles around the city. Eventually, a state of emergency was called and the national guard arrived with drinking water. Toledo is not alone. According to scientists, algae blooms are becoming more frequent and more toxic worldwide.

Hundreds of tonnes of dead fish also washed ashore. In , there were more than reported incidents of toxic or harmful algae blooms around the world. This year about have been listed on an international database, but that number is expected to increase. The causes of the blooms vary, and in some cases are never known, but in many parts of the world they are being increasingly linked to climate change and industrialised agriculture.

Algae includes everything from micro-algae, like microscopic diatoms, to very large algae, such as seaweed and kelp. An algae bloom occurs when a single member of these species — because of certain conditions — suddenly becomes dominant for a time. Algae are vital to our survival. Algae, like land plants, also sequester carbon dioxide; scientists have explored their potential to draw carbon dioxide out of the atmosphere.

They have been used as fertiliser, food sources such as seaweed , and could be a promising source of biofuel in a more sustainable world. Harmful algae bloom HAB , as scientists have come to describe the phenomenon, often manifest by forming a kind of scum over a body of water that can be green, blue, brown or even red. But others are completely invisible.

The problem has become increasingly widespread and the impact can be deadly to marine life. Off the eastern coast of the US, a dinoflagellate — a type of marine plankton named Alexandrium catenella — has the potential to make shellfish lethal. Its appearance routinely shuts down fisheries, crippling local economies. Other blooms wipe out marine life. In , a bloom of various dinoflagellates off the coast of South Africa led to low-oxygen conditions, known as eutrophication, killing tonnes of rock lobster.

Freshwater blooms, like those in Lake Erie made up of cyanobacteria or blue-green algae, have not only shut down local water sources but have also been blamed for the death of dogs that had been swimming in them.

Scientists have identified about toxic bloom species in the oceans. Dozens of potentially harmful species of cyanobacteria are known to affect bodies of fresh water. During most of the past century, harmful algae blooms were rarely headline news, inspiring little scientific study beyond ecological curiosity.

There is no consistent evidence that exposure to harmful algae causes motor neurone disease in humans. Likewise, there is no evidence that people living in the vicinity of algae-affected water are at increased risk of developing the disease. Harmful algal blooms will remain as long as there are favourable conditions, including warmth, sunlight and low flow rates.

Blooms can last from weeks to months and it is difficult to predict when they will clear. Cooler, windy weather or increased water flow may reduce or stop algal blooms. This page has been produced in consultation with and approved by:. When returning to a flood-affected area, remember that wild animals, including rats, mice, snakes or spiders, may be trapped in your home, shed or garden.

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The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website. Skip to main content. Environmental health. Home Environmental health. Harmful algal blooms.

Actions for this page Listen Print. Summary Read the full fact sheet. On this page. What is an algal bloom? What are harmful algae? What are the health impacts of harmful algae? Why are children more susceptible to harmful algae? How can I avoid exposure to algal toxins? What should I do if I contact algae-affected water? Can I swim and play other water sports in algae-affected water? How do I keep animals safe from harmful algae?

Can I eat fish caught in waters affected by harmful algae? Can harmful algae affect my drinking water? Marine salt water Blooms in marine environments such as oceans and bays have affected all coastal U. They are most commonly caused by dinoflagellates or diatoms but can also be caused by cyanobacteria.

Brackish water mix of fresh and salt water Blooms can occur in brackish waters in the United States, including estuaries and coastal waters.

Blooms in brackish water are most commonly caused by dinoflagellates or diatoms but can also be caused by cyanobacteria. When in doubt, keep out! Look for signs of a bloom of harmful algae or cyanobacteria before going in water and stay out if water looks or smells bad.

As algae or cyanobacteria in a bloom die and start decaying, they can release gases that smell like rotten eggs or rotting plants.

Cyanobacterial blooms can grow on rocks beneath the water. They can also grow on the surface of the water and look like. Some blooms are easy to spot, but others are hard to see. Looks can be deceiving. Some blooms grow on or near the bottom of water bodies called the benthic zone like lakes, rivers, and oceans.

Some of these blooms make toxins and release them into the water. These blooms can also wash up on the shore. People and animals can get sick from these blooms. You cannot tell if a water body has a harmful bloom just by looking at it. Find tips for protecting yourself and your loved ones. Ecosystems are made up of living organisms and their physical environment. People, animals, and local environments are all part of an ecosystem. Harmful algae and cyanobacteria are a One Health issue and can affect ecosystems in many ways.

Toxins can be in the cells of the phytoplankton or released into the water. Learn more about how people and animals can be exposed to harmful algal blooms and what you can do to protect yourself from toxins. If a bloom becomes so dense that sunlight cannot go through, it can block other plants and animals in the water from getting the sunlight they need to survive.

Dense blooms can also clog the gills of fish, shellfish, and other animals, preventing them from breathing. When a bloom dies off, the decay process may use up all the oxygen in the water, causing other organisms in the water to suffocate not be able to breathe.

As a bloom decays, it may also release gases that can harm people, such as methane and hydrogen sulfide which smells like rotten eggs.

Climate change can increase the growth of harmful algae and cyanobacteria in fresh, salt, and brackish water. It can make blooms occur more often and be more severe. For example, warming temperatures in Lake Erie have contributed to extensive blooms of the cyanobacteria Microcystis aeruginosa that last into the early winter months. In the past several years, such blooms have been found more often and in more places across the United States.

Skip directly to site content Skip directly to page options Skip directly to A-Z link. Section Navigation. Facebook Twitter LinkedIn Syndicate. Causes and Ecosystem Impacts. Minus Related Pages. On This Page. Blooms basics Signs of a bloom Ecosystem impacts Contributing factors.

Blooms basics. Algae Algae are a group of plants that are usually found in water. Seaweed, or macroalgae.