Harmful effects. As algal blooms grow, they deplete the oxygen in the water and block sunlight from reaching fish and plants. And when the algae eventually die off, the microbes which decompose the dead algae use up even more oxygen, which in turn causes more fish to die or leave the area.

Red tides, blue-green algae, and cyanobacteria are examples of harmful algal blooms that can have severe impacts on human health, aquatic ecosystems, and the economy. Algal blooms can be toxic. Keep people and pets away from water that is green, scummy or smells bad.

Some kinds of algae produce harmful toxins (poisons). An accumulation of these algae is known as a harmful algal bloom. Toxins produced by harmful algal blooms in a marine environment can impact human health as well as seafood harvested from algae-affected water.

Direct exposure to algae Harmful algal blooms sometimes create toxins that are detrimental to fish and other animals. After being consumed by small fish and shellfish, these toxins move up the food chain and can impact larger animals like sea lions, turtles, dolphins, birds and manatees.

If you see a bloom, stay out of the water and keep your pets and livestock out of the water. You cannot tell if a bloom is harmful by looking at it, so it is best to use caution and stay away. Do not fish, swim, boat, or play water sports in areas where there is harmful algae or cyanobacteria.

Keep a close eye on pets or small children, who may ingest water containing toxins produced by these algae. Exposure to blue-green algae during swimming, wading, and water-skiing can lead to rashes, skin, eye irritation, and effects such as nausea, stomach aches, and tingling in fingers and toes.

Algae-affected water may not be suitable for drinking, recreation or agricultural use. Contact with affected water can cause skin irritation, mild respiratory effects and hayfever-like symptoms. Ingesting toxins can cause gastroenteritis symptoms, such as vomiting, diarrhoea, fever and headaches.

Dinoflagellates

Use phosphorus-free fertilizers and detergents to limit nutrient-rich runoff. Have a pond management professional apply phosphorous-binding products, which prevent nutrients from stimulating algae growth, in nutrient heavy lakes and ponds. Practice relative awareness of changing climate and research support.

Algal blooms are the result of a nutrient, like nitrogen or phosphorus from fertilizer runoff, entering the aquatic system and causing excessive growth of algae. An algal bloom affects the whole ecosystem.

Elevated nutrient levels and algal blooms can also cause problems in drinking water in communities nearby and upstream from dead zones. Harmful algal blooms release toxins that contaminate drinking water, causing illnesses for animals and humans.

Several ways can be done to control the occurrence of algae blooming in waters such as lakes, namely controlling the use of fertilizers, checking the septic system, not using a garburator, reducing the use of detergents, minimizing impervious surfaces close to the water where possible.

And just like plants, algae generate oxygen. They increase dissolved oxygen in the water which good for higher organisms like fish. Much of the earth’s oxygen (>70%) comes from the oceans and algae are responsible for a significant portion of this. Algae, like plants, reduce carbon dioxide, a major greenhouse gas.

Ingestion: Gastrointestinal (GI) effects include nausea, vomiting, diarrhea, and mild liver enzyme elevations. The time to onset of GI symptoms after oral exposure is usually 3–5 hours and symptoms can last 1–2 days. Exposure can cause conjunctivitis, rhinitis, earache, sore throat, and swollen lips.

Algae spores can actually survive out of water and lay dormant for some time on our swimsuits, towels, pool care accessories, such as vacuum hoses, wall brushes, leaf nets, and so on.