“Red Tides,” or Harmful Algal Blooms

Seth WinkenwerderPhycology, Spring 2009

Topic Presentation, May 21, 2009

Image: http://serc.carleton.edu/images/microbelife/topics/red_tide_genera.v3.jpg

“Red Tides” are actually Harmful Algal Blooms, or simply Algal Blooms.

•Algal blooms are not always red, can also be green, brown, orange, or even not pigmented at all.

•“Red Tides” have little to no relation to actual ocean tides.

•Many different species and organisms can cause the phenomenon, and there is no single cause.

Image: http://drake.marin.k12.ca.us/stuwork/ROCKwater/PLANKTON/redtide.jpg

Algal Blooms

• Abnormally large concentrations of algae in an aquatic environment

• Can be caused by a variety of different species

• May occur naturally, but mostly the result of human activity (such as chemical waste released into the ocean)

• “Harmful” variety produce toxins.

Image: http://shiftingbaselines.org/blog/team_redtide.jpg

Species involved

• Too many to find a single definitive list.• Predominantly Phytoplankton• Bright green blooms caused by cyanobacteria

(can appear to be thick green goo)

Images: http://www.whoi.edu/redtide/

•Less common, but Macroalgaecan also cause bloomeventsto take place.

What causes them?

• Natural causes???• Compounded by upwelling or unusually calm

weather in some cases.• Human waste

– Nitrogen-fertilizer runoff– Untreated waste– Other industrial bi-products

How are they detected?

• When in coastal regions and colorful, obviously easy to spot.

• In most cases, amounts of certain pigments are a reasonably accurate way to check the concentration

• Satellite imagery is used to look at blooms that are very large or are harder to study from the surface (such as large blooms in the Baltic Sea.)

• It is possible that monitoring systems may be able to be implemented in the future using the knowledge we are currently building and new technologies. (Schofield 1999)

Impact on Human Health

• Around 2000 cases of human poisoning are reported each year (Zingone p.729)

• National Institute of Health study on Karenia brevis blooms in Florida (Backer 2003)– Known to kill millions of fish and other marine

animals, but human affects were unknown– Humans who came in contact with aerosolized

toxins studied during harmful algal blooms off the Florida coast

NIH Study Results (Backer 2003)

• High exposure days resulted in more (in both quality and quantity) severe symptoms.

• Only a couple people that were not already showing ‘symptoms’ before exposure were afterwards, but those that were got slightly worse.

• The bloom did not come onto the beach, and measured levels of brevetoxin on the beach and in the air over the beach were very low.

• Could be less of a big deal, or the conditions of the study• Study did confirm that such exposure can cause upper and

lower respiratory and even skin irritation, but more studies and more intense experiments would have to be undertaken to learn more than that.

Affect on other marine animals

• Some studies have recently shown that brevetoxins produced can remain in food webs for long periods of time, as they accumulate in fish and seagrass. (Flewelling2005)

• Studies were done to try to explain increased mantate, dolphin, and fish death in some recent algal blooms compared to what would have been expected

• Toxins can build up in shellfish, which harm other organisms, not just humans.

http://i.pbase.com/o4/77/630577/1/67045799.nRnEFOuh.redtide.jpg

http://www.whoi.edu/cms/images/lstokey/2005/1/v43n2-anderson4en_5499.jpg

Negative Economic Effects (Hoagland 2002)

• Congress estimated in 1998 that HAGs had caused 1 billion dollars in damage in the last decade

• September 1980 closure of the Maine coastline- estimated $15 million lost.

• Loss of value of coastal property in areas strongly affected by algal blooms

• Estimated loss of $68 million by tourism industry in Florida due to HAGs for the summer of 1971.

Works Cited:• Backer, Lorraine et. al. “Recreational exposure to aerosolized

brevetoxins during Florida red tide events. Harmful Algae. 2(1) p.19-28. March 2003.

• Flewelling, Leanne et. al. “Red Tides and Marine Mammal mortalities.” Nature. Vol. 435 p.755-756. 9 June 2005.

• Hoagland, P. et. al. “The economic affects of harmful algal blooms in the United States.” Estuaries. Vol 25, no 4B, p.819-837. August 2002

• Zigone, Adriana and Henrik Oksfeldt Enevoldsen. “The Diversity of Harmful Algal Blooms: a challenge for science and management.” Ocean and Coastal Management. 43 p. 725-748. 2000.

• Schofield, Oscar et. al. [including Mark Moline ] “Optical monitoring and forecasting systems for harmful algal blooms: possibility or pipe dream?” Journal of Phycology 35, p.1477-1496. 1999.