Harmful algal blooms (or HABs as they are often referred to as) occur when certain species of algae become so densely populated that it begins to have a harmful effect on aquatic life and the environment. There are many ways in which this can happen, however some of those include:

Harmful algal blooms are complicated, but some of the major factors that contribute to their formation are nutrient runoff (from fertilizers), warm sea surface temperatures (El Niño cycles), poor watershed management (increased sediment, deforestation, etc.), and climate change.

One of the most significant factors in harmful algal blooms is nutrient runoff.  This comes from fertilizer runoffs and wastewater runoffs, which enter the ocean through rivers and streams during rainfall events. According to NOAA, “Nutrient pollution is widely recognized as one of the most challenging threats facing our nation’s coastal resources.” The fertilizers that are introduced into the water supply cause phytoplankton growth to increase by 2-5 times. This is because when phosphate and nitrate enter the ocean, they act as a fertilizer for phytoplankton (algae). The nutrients nitrogen and phosphorus are most dangerous because they can spur quick growth of phytoplankton (algae).

The impact of HABs has been felt not just in Oregon but worldwide, from the United States and Europe to Japan and Australia. HABs can cause negative impacts on food webs by depleting oxygen levels, killing fish and other marine wildlife, creating dead zones or harmful conditions for human activities such as swimming or drinking the water. HABs can have a wide range of negative effects on coastal communities. In addition to killing wildlife, HABs can cause a variety of short-term and long-term health problems in humans and other marine wildlife. Short term impacts from exposure may include respiratory irritation or gastrointestinal distress from swallowing water while swimming or ingesting seafood caught from the affected area. Longer-term exposure can cause liver or nervous system damage from consuming contaminated seafood.

In Oregon, HABs have been linked to wildlife deaths, including sea lions and otters . In addition, shellfish beds in Yaquina Bay and Tillamook Bay were closed due to high levels of domoic acid in the algae during a 2015 bloom.  When HABs occur in Oregon, we often recommend that residents and visitors limit direct contact with coastal waters until the bloom has passed. If you come into contact with algae scum or water, wash your skin and rinse your eyes with fresh water. If you experience respiratory irritation, seek medical attention immediately. Be aware that any seafood product may be contaminated with high levels of domoic acid for up to a week after the end of the HAB event. It is best to avoid consuming recreationally caught crab during this time period. Harmful algal blooms are not something anyone can completely avoid, but knowing about them gives us the tools to limit their impact on our coastal communities.

References used for this article: http://www.oregonlive.com/pacific-northwest-news/index.ssf/2015/05/hazards_of_harmful_algae_blooms.html http://www.opb.org/earthfix/blogpost/2015/06/09-28-15-health-warning-bluegreenalgaepoisoning-oregon/ http://www.hawaii247.com/2015/06/09/blue-green-algae-bloom-causes-newport-beach-closure/ http://www.epa.gov/nutrientpollution/effects_algal_blooms.html https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=1277

Sources:  http://www.epa.gov/hiri/habs_web/basics.html#causes , http://www.marine-conservation-explorations.com/habs-3 , http://www.huffingtonpost.com/daniel-g-barry/red-tide_b_4023374.html, http://scientopia.org/blogs/scicurious/2009/05/13/what-causes-harmful-algae-blooms/

Algae Bloom – causes, symptoms, treatments, photos http://answers.yahoo.com/question/index?qid=20080905154855AALvkMB

Harmful Algal Blooms (Red Tide) 3-D Video http://www.youtube.com/watch?v=wQ6iUasg8qY

Harmful Algal Blooms (Red Tide) 3-D Video http://www.youtube.com/watch?v=wQ6iUasg8qY