How can algal blooms be harmful to humans

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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? Is it safe to use untreated algae-affected water from a lake, dam or stream? Can I water my garden with water affected by harmful algae? Do harmful algae cause motor neurone disease? How long do algal blooms last? Algal blooms occur when conditions for growth are ideal for algae, for example when: the weather is warm and sunny the water is not flowing or moving, or is doing so slowly the water is nutrient-rich for example, due to runoff containing fertilisers and sewage.

Harmful algae can be found in both marine and freshwater environments. Direct skin contact with algal toxins can cause skin and eye irritation. If you are concerned for your health, consult your GP immediately.

As much as possible, make sure children in your care are aware of the dangers of harmful algae. Algae can impact the smell and taste of water supplies. Give feedback about this page. Was this page helpful? Yes No. View all environmental health. Not all algal blooms are harmful, some can actually be beneficial. Phytoplankton are found at the base of the marine food chain therefore all other life in the ocean relies on phytoplankton. Blooms can also be a good indicator of environmental change not only in the water, but also on land.

Home Ocean Facts Are all algal blooms harmful? Symptoms of a neurotoxin HAB exposure may appear within minutes while symptoms of a hepatotoxin HAB exposure may take hours or several days to appear.

Mammals and birds exposed to cyanobacteria toxins may become ill or die. As other bacteria in the water break-down dead cyanobacteria, the dissolved oxygen in the water may become depleted, which may cause a fish kill. Cyanobacteria bloom toxins at high concentrations can be directly harmful to fish and may cause fish kills as well. Dense bacterial blooms in the water column will block out sunlight necessary to other organisms to survive. Wildlife, pets, and livestock are also prone to exposure by wading and drinking bloom water.

A very small amount of toxin can cause illness to small animals if ingested. Internal organs innards of fish and crabs caught in bloom waters may be contaminated and, therefore, should not be consumed. It is safe to consume fish filets that appear healthy when caught in bloom waters, providing you carefully clean the fish, discarding all guts and the carcass, thoroughly cook the fish fillet, and wash hands and surfaces with fresh, soapy water afterward.

In waters with persistent, reoccurring blooms where toxin levels are high, consumption may not be advised. Several state agencies and municipal governments work together to regularly monitor the water and shellfish growing areas for the presence of cyanobacteria and their toxins, and to conduct surveillance for human health effects.