Algal bloom

An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems, and is recognized by the discoloration in the water from their pigments.[2] Cyanobacteria were mistaken for algae in the past, so cyanobacterial blooms are sometimes also called algal blooms. Blooms which can injure animals or the ecology are called "harmful algal blooms" (HAB), and can lead to fish die-offs, cities cutting off water to residents, or states having to close fisheries. A bloom can block the sunlight from reaching other organisms, deplete oxygen levels in the water, and some algae even secrete toxins into the water.

Toxic Algae Bloom in Lake Erie
Taken from orbit in October 2011, the worst algae bloom that Lake Erie has experienced in decades. Record torrential spring rains washed fertilizer into the lake, promoting the growth of microcystin producing cyanobacteria blooms.[1]


River algae Sichuan
Algal blooms can present problems for ecosystems and human society.

Since 'algae' is a broad term including organisms of widely varying sizes, growth rates and nutrient requirements, there is no officially recognized threshold level as to what is defined as a bloom. For some species, algae can be considered to be blooming at concentrations reaching millions of cells per milliliter, while others form blooms of tens of thousands of cells per liter. The photosynthetic pigments in the algal cells determine the color of the algal bloom, and are thus often a greenish color, but they can also be a wide variety of other colors such as yellow, brown or red, depending on the species of algae and the type of pigments contained therein.

Bright green blooms in freshwater systems are frequently a result of cyanobacteria (colloquially known as "blue-green algae" as a result of their confusing taxonomical history) such as Microcystis. Blooms may also consist of macroalgal (non-phytoplanktonic) species. These blooms are recognizable by large blades of algae that may wash up onto the shoreline.

Of particular note are the rare harmful algal blooms (HABs), which are algal bloom events involving toxic or otherwise harmful phytoplankton such as dinoflagellates of the genus Alexandrium and Karenia, or diatoms of the genus Pseudo-nitzschia. Such blooms often take on a red or brown hue and are known colloquially as red tides.

Freshwater algal blooms

Freshwater algal blooms are the result of an excess of nutrients, particularly some phosphates.[3][4] The excess of nutrients may originate from fertilizers that are applied to land for agricultural or recreational purposes. They may also originate from household cleaning products containing phosphorus.[5] These nutrients can then enter watersheds through water runoff.[6] Excess carbon and nitrogen have also been suspected as causes. Presence of residual sodium carbonate acts as catalyst for the algae to bloom by providing dissolved carbon dioxide for enhanced photosynthesis in the presence of nutrients.

When phosphates are introduced into water systems, higher concentrations cause increased growth of algae and plants. Algae tend to grow very quickly under high nutrient availability, but each alga is short-lived, and the result is a high concentration of dead organic matter which starts to decay. The decay process consumes dissolved oxygen in the water, resulting in hypoxic conditions. Without sufficient dissolved oxygen in the water, animals and plants may die off in large numbers. Use of an Olszewski tube can help combat these problems with hypolimnetic withdrawal.

Blooms may be observed in freshwater aquariums when fish are overfed and excess nutrients are not absorbed by plants. These are generally harmful for fish, and the situation can be corrected by changing the water in the tank and then reducing the amount of food given.

Harmful algal blooms

Cwall99 lg
An algae bloom off the southern coast of Devon and Cornwall in England, in 1999
Van Gogh from Space
Satellite image of phytoplankton swirling around the Swedish island of Gotland in the Baltic Sea, in 2005

A harmful algal bloom (HAB) is an algal bloom that causes negative impacts to other organisms via production of natural toxins, mechanical damage to other organisms, or by other means. HABs are often associated with large-scale marine mortality events and have been associated with various types of shellfish poisonings.[7]

In studies at the population level bloom coverage has been significantly related to the risk of non-alcoholic liver disease death.[8]


In the marine environment, single-celled, microscopic, plant-like organisms naturally occur in the well-lit surface layer of any body of water. These organisms, referred to as phytoplankton or microalgae, form the base of the food web upon which nearly all other marine organisms depend. Of the 5000+ species of marine phytoplankton that exist worldwide, about 2% are known to be harmful or toxic.[9] Blooms of harmful algae can have large and varied impacts on marine ecosystems, depending on the species involved, the environment where they are found, and the mechanism by which they exert negative effects.

Harmful algal blooms have been observed to cause adverse effects to a wide variety of aquatic organisms, most notably marine mammals, sea turtles, seabirds and finfish. The impacts of HAB toxins on these groups can include harmful changes to their developmental, immunological, neurological, or reproductive capacities. The most conspicuous effects of HABs on marine wildlife are large-scale mortality events associated with toxin-producing blooms. For example, a mass mortality event of 107 bottlenose dolphins occurred along the Florida panhandle in the spring of 2004 due to ingestion of contaminated menhaden with high levels of brevetoxin.[10] Manatee mortalities have also been attributed to brevetoxin but unlike dolphins, the main toxin vector was endemic seagrass species (Thalassia testudinum) in which high concentrations of brevetoxins were detected and subsequently found as a main component of the stomach contents of manatees.[10]

Additional marine mammal species, like the highly endangered North Atlantic Right Whale, have been exposed to neurotoxins by preying on highly contaminated zooplankton.[11] With the summertime habitat of this species overlapping with seasonal blooms of the toxic dinoflagellate Alexandrium fundyense, and subsequent copepod grazing, foraging right whales will ingest large concentrations of these contaminated copepods. Ingestion of such contaminated prey can affect respiratory capabilities, feeding behavior, and ultimately the reproductive condition of the population.[11]

Immune system responses have been affected by brevetoxin exposure in another critically endangered species, the Loggerhead sea turtle. Brevetoxin exposure, via inhalation of aerosolized toxins and ingestion of contaminated prey, can have clinical signs of increased lethargy and muscle weakness in loggerhead sea turtles causing these animals to wash ashore in a decreased metabolic state with increases of immune system responses upon blood analysis.[12] Examples of common harmful effects of HABs include:

  1. the production of neurotoxins which cause mass mortalities in fish, seabirds, sea turtles, and marine mammals
  2. human illness or death via consumption of seafood contaminated by toxic algae[13]
  3. mechanical damage to other organisms, such as disruption of epithelial gill tissues in fish, resulting in asphyxiation
  4. oxygen depletion of the water column (hypoxia or anoxia) from cellular respiration and bacterial degradation

Due to their negative economic and health impacts, HABs are often carefully monitored.[14][15]

HABs occur in many regions of the world, and in the United States are recurring phenomena in multiple geographical regions. The Gulf of Maine frequently experiences blooms of the dinoflagellate Alexandrium fundyense, an organism that produces saxitoxin, the neurotoxin responsible for paralytic shellfish poisoning. The well-known "Florida red tide" that occurs in the Gulf of Mexico is a HAB caused by Karenia brevis, another dinoflagellate which produces brevetoxin, the neurotoxin responsible for neurotoxic shellfish poisoning. California coastal waters also experience seasonal blooms of Pseudo-nitzschia, a diatom known to produce domoic acid, the neurotoxin responsible for amnesic shellfish poisoning. Off the west coast of South Africa, HABs caused by Alexandrium catanella occur every spring. These blooms of organisms cause severe disruptions in fisheries of these waters as the toxins in the phytoplankton cause filter-feeding shellfish in affected waters to become poisonous for human consumption.[16]

If the HAB event results in a high enough concentration of algae the water may become discoloured or murky, varying in colour from purple to almost pink, normally being red or green. Not all algal blooms are dense enough to cause water discolouration.

Red tides

Maré vermelha
A red tide

Red tide is a term often used synonymously with HABs in marine coastal areas; however, the term is misleading since algal blooms can widely vary in color, and growth of algae is unrelated to the tides. The term algal bloom or harmful algal bloom has since replaced red tide as the appropriate description of this phenomenon.

Causes of HABs

It is unclear what causes HABs; their occurrence in some locations appears to be entirely natural,[17] while in others they appear to be a result of human activities.[18] Furthermore, there are many different species of algae that can form HABs, each with different environmental requirements for optimal growth. The frequency and severity of HABs in some parts of the world have been linked to increased nutrient loading from human activities. In other areas, HABs are a predictable seasonal occurrence resulting from coastal upwelling, a natural result of the movement of certain ocean currents.[19] The growth of marine phytoplankton (both non-toxic and toxic) is generally limited by the availability of nitrates and phosphates, which can be abundant in coastal upwelling zones as well as in agricultural run-off. The type of nitrates and phosphates available in the system are also a factor, since phytoplankton can grow at different rates depending on the relative abundance of these substances (e.g. ammonia, urea, nitrate ion). A variety of other nutrient sources can also play an important role in affecting algal bloom formation, including iron, silica or carbon. Coastal water pollution produced by humans (including iron fertilization) and systematic increase in sea water temperature have also been suggested as possible contributing factors in HABs.[20] Other factors such as iron-rich dust influx from large desert areas such as the Sahara are thought to play a role in causing HABs.[21] Some algal blooms on the Pacific coast have also been linked to natural occurrences of large-scale climatic oscillations such as El Niño events. HABs are also linked to heavy rainfall.[22] While HABs in the Gulf of Mexico have been occurring since the time of early explorers such as Cabeza de Vaca,[23] it is unclear what initiates these blooms and how large a role anthropogenic and natural factors play in their development. It is also unclear whether the apparent increase in frequency and severity of HABs in various parts of the world is in fact a real increase or is due to increased observation effort and advances in species identification technology.[24][25] However recent research found that the warming of summer surface temperatures of lakes, which rose by 0.34 °C decade per decade between 1985 and 2009 due to global warming, also will likely increase algal blooming by 20% over the next century.[26]

Researching solutions

The decline of filter-feeding shellfish populations, such as oysters, likely contribute to HAB occurrence.[27] As such, numerous research projects are assessing the potential of restored shellfish populations to reduce HAB occurrence.[28][29][30]

Since many algal blooms are caused by a major influx of nutrient-rich runoff into a water body, programs to treat wastewater, reduce the overuse of fertilizers in agriculture and reducing the bulk flow of runoff can be effective for reducing severe algal blooms at river mouths, estuaries, and the ocean directly in front of the river's mouth.

Notable occurrences

  • Lingulodinium polyedrum produces brilliant displays of bioluminescence in warm coastal waters. Seen in Southern California regularly since at least 1901.[31]
  • In 1972, a red tide was caused in New England by a toxic dinoflagellate Alexandrium (Gonyaulax) tamarense.[32]
  • The largest algal bloom on record was the 1991 Darling River cyanobacterial bloom, largely of Anabaena circinalis, between October and December 1991 over 1,000 kilometres (620 mi) of the Barwon and Darling Rivers.[33]
  • In 2005, the Canadian HAB was discovered to have come further south than it has in years prior by a ship called The Oceanus, closing shellfish beds in Maine and Massachusetts and alerting authorities as far south as Montauk (Long Island, NY) to check their beds.[34] Experts who discovered the reproductive cysts in the seabed warn of a possible spread to Long Island in the future, halting the area's fishing and shellfish industry and threatening the tourist trade, which constitutes a significant portion of the island's economy.
  • In 2008 large blooms of the algae Cochlodinium polykrikoid were found along the Chesapeake Bay and nearby tributaries such as the James River, causing millions of dollars in damage and numerous beach closures.[22]
  • In 2009, Brittany, France experienced recurring algal blooms caused by the high amount of fertilizer discharging in the sea due to intensive pig farming, causing lethal gas emissions that have led to one case of human unconsciousness and three animal deaths.[35]
  • In 2010, dissolved iron in the ash from the Eyjafjallajökull volcano triggered a plankton bloom in the North Atlantic.[36]
  • In 2013, an algal bloom was caused in Qingdao, China, by sea lettuce.[37]
  • In 2014, Myrionecta rubra (previously known as Mesodinium rubrum), a ciliate protist that ingests cryptomonad algae, caused a bloom in southeastern coast of Brazil.[38]
  • In 2014, blue green algae caused a bloom in the western basin of Lake Erie, poisoning the Toledo, Ohio water system connected to 500,000 people.[39]
  • In 2016, a harmful algal bloom in Florida closed several beaches (ex. Palm Beach, Florida). The blooms consisted of several harmful genera of algae.
  • In 2019, A harmful bloom in Virginia's Chris Greene Lake which had been treated was once again open to the public, but the water continues to be tested to remove all harmful bacteria and poisons.[40]
Red, orange, yellow and green represent areas where algal blooms abound. Blue patches represent nutrient-poor zones where blooms exist in low numbers.
The US Coast Guard Cutter Healy ferried scientists to 26 study sites in the Arctic, where blooms ranged in concentration from high (red) to low (purple).
Researcher David Mayer of Clark University lowers a video camera below the ice to observe a dense bloom of phytoplankton.

See also


  1. ^ Joanna M. Foster (20 November 2013). "Lake Erie Is Dying Again, And Warmer Waters And Wetter Weather Are To Blame". ClimateProgress.
  2. ^ Ferris, Robert (26 July 2016). "Why are there so many toxic algae blooms this year". CNBC. Retrieved 27 July 2016.
  3. ^ Diersling, Nancy. "Phytoplankton Blooms: The Basics" (PDF). NOAA FKNMS. Retrieved 26 December 2012.
  4. ^ Hochanadel, Dave (10 December 2010). "Limited amount of total phosphorus actually feeds algae, study finds". Lake Scientist. Retrieved 10 June 2012. [B]ioavailable phosphorus – phosphorus that can be utilized by plants and bacteria – is only a fraction of the total, according to Michael Brett, a UW engineering professor ...
  5. ^ Gilbert, P. A.; Dejong, A. L. (1977). "The use of phosphate in detergents and possible replacements for phosphate". Ciba Foundation Symposium (57): 253–268. PMID 249679.
  6. ^ Lathrop, Richard C.; Stephen R. Carpenter; John C. Panuska; Patricia A. Soranno; Craig A. Stow (1 May 1998). "Phosphorus loading reductions needed to control blue-green algal blooms in Lake Mendota" (PDF). Canadian Journal of Fisheries and Aquatic Sciences. 55 (5): 1169–1178. doi:10.1139/cjfas-55-5-1169. Retrieved 13 April 2008.
  7. ^ "Harmful Algal Blooms: Red Tide: Home". Archived from the original on 27 August 2009. Retrieved 23 August 2009.
  8. ^ Feng Zhang; Jiyoung Lee; Song Liang; CK Shum (2015). "Cyanobacteria blooms and non-alcoholic liver disease: evidence from a county level ecological study in the United States". Environ Health. 14: 41. doi:10.1186/s12940-015-0026-7. PMC 4428243. PMID 25948281.
  9. ^ Landsberg, J. H. (2002). "The effects of harmful algal blooms on aquatic organisms". Reviews in Fisheries Science. 10 (2): 113–390. doi:10.1080/20026491051695.
  10. ^ a b Flewelling, L. J.; et al. (2005). "Red tides and marine mammal mortalities". Nature. 435 (7043): 755–756. Bibcode:2005Natur.435..755F. doi:10.1038/nature435755a. PMC 2659475. PMID 15944690.
  11. ^ a b Durbin E et al (2002) North Atlantic right whale, Eubalaena glacialis, exposed to paralytic shellfish poisoning (PSP) toxins via a zooplankton vector, Calanus finmarchicus. Harmful Algae I, : 243-251 (2002)
  12. ^ Walsh, C. J.; et al. (2010). "Effects of brevetoxin exposure on the immune system of loggerhead sea turtles". Aquatic Toxicology. 97 (4): 293–303. doi:10.1016/j.aquatox.2009.12.014. PMID 20060602.
  13. ^ "Red Tide FAQ - Is it safe to eat oysters during a red tide?". Retrieved 23 August 2009.
  14. ^ Florida Fish and Wildlife Research Institute. "Red Tide Current Status Statewide Information". Archived from the original on 22 August 2009. Retrieved 23 August 2009.
  15. ^ "Red Tide Index". Retrieved 23 August 2009.
  16. ^ "Red Tide Fact Sheet - Red Tide (Paralytic Shellfish Poisoning)". Archived from the original on 26 August 2009. Retrieved 23 August 2009.
  17. ^ Adams, N. G.; Lesoing, M.; Trainer, V. L. (2000). "Environmental conditions associated with domoic acid in razor clams on the Washington coast". J Shellfish Res. 19: 1007–1015.
  18. ^ Lam, C. W. Y.; Ho, K. C. (1989). "Red tides in Tolo Harbor, Hong Kong". In Okaichi, T.; Anderson, D. M.; Nemoto, T. (eds.). Red tides. biology, environmental science and toxicology. New York: Elsevier. pp. 49–52. ISBN 978-0-444-01343-9.
  19. ^ Trainer, V. L.; Adams, N. G.; Bill, B. D.; Stehr, C. M.; Wekell, J. C.; Moeller, P.; Busman, M.; Woodruff, D. (2000). "Domoic acid production near California coastal upwelling zones, June 1998". Limnol Oceanogr. 45 (8): 1818–1833. Bibcode:2000LimOc..45.1818T. doi:10.4319/lo.2000.45.8.1818.
  20. ^ Moore, S.; et al. (2011). "Impacts of climate variability and future climate change on harmful algal blooms and human health". Proceedings of the Centers for Oceans and Human Health Investigators Meeting. 7: S4. doi:10.1186/1476-069X-7-S2-S4. PMC 2586717. PMID 19025675.
  21. ^ Walsh; et al. (2006). "Red tides in the Gulf of Mexico: Where, when, and why?". Journal of Geophysical Research. 111 (C11003): 1–46. Bibcode:2006JGRC..11111003W. doi:10.1029/2004JC002813. PMC 2856968. PMID 20411040.
  22. ^ a b Morse, Ryan E.; Shen, Jian; Blanco-Garcia, Jose L.; Hunley, William S.; Fentress, Scott; Wiggins, Mike; Mulholland, Margaret R. (1 September 2011). "Environmental and Physical Controls on the Formation and Transport of Blooms of the Dinoflagellate Cochlodinium polykrikoides Margalef in the Lower Chesapeake Bay and Its Tributaries". Estuaries and Coasts. 34 (5): 1006–1025. doi:10.1007/s12237-011-9398-2. ISSN 1559-2723.
  23. ^ Cabeza de Vaca, Álvar Núnez. La Relación (1542). Translated by Martin A. dunsworth and José B. Fernández. Arte Público Press, Houston, Texas (1993)
  24. ^ Sellner, K.G.; Doucette G.J.; Kirkpatrick G.J. (2003). "Harmful Algal blooms: causes, impacts and detection". Journal of Industrial Microbiology and Biotechnology. 30 (7): 383–406. doi:10.1007/s10295-003-0074-9. PMID 12898390.
  25. ^ Van Dolah, F.M. (2000). "Marine Algal Toxins: Origins, Health Effects, and Their Increased Occurrence". Environmental Health Perspectives. 108 (suppl.1): 133–141. doi:10.1289/ehp.00108s1133. JSTOR 3454638. PMC 1637787. PMID 10698729. Archived from the original on 20 January 2009.
  26. ^ O'Reiley et al, Rapid and highly variable warming of lake surface waters around the globe. In: Geophysical Research Letters (2015), doi:10.1002/2015GL066235.
  27. ^ Brumbaugh, R.D.; et al. (2006). "A Practitioners Guide to the Design & Monitoring of Shellfish Restoration Projects: An Ecosystem Approach. The Nature Conservancy, Arlington, Virginia" (PDF). Archived from the original (PDF) on 4 March 2016. Retrieved 18 March 2017.
  28. ^ "Shinnecock Bay Restoration Program". Retrieved 18 March 2017.
  29. ^ "Delaware Oyster Gardening and Restoration - A Cooperative Effort" (PDF). Archived from the original (PDF) on 4 March 2016. Retrieved 18 March 2017.
  30. ^ "The Mobile Bay Oyster Gardening Program" (PDF). Archived from the original (PDF) on 25 May 2013. Retrieved 5 August 2017.
  31. ^ Bryan Nelson (11 November 2011). "What is causing the waves in California to glow? | MNN - Mother Nature Network". MNN. Retrieved 18 March 2017.
  32. ^ HAB 2000 Archived 11 December 2008 at the Wayback Machine
  33. ^ Bowling, L.C. and Baker, P.D; ‘Major Cyanobacterial Bloom in the Barwon-Darling River, Australia, in 1991, and Underlying Limnological Conditions’; Marine and Freshwater Research, 47 (1996); pp. 643-57
  34. ^ Moore, Kirk. "Northeast Oysters: The bigger danger, growers assert, would be the label of endangered". National Fisherman. Archived from the original on 8 August 2007. Retrieved 31 July 2008.
  35. ^ Chrisafis, Angelique (10 August 2009). "Lethal algae take over beaches in northern France". The Guardian. London.
  36. ^ "Iceland volcano ash cloud triggers plankton bloom". BBC News. 10 April 2013.
  37. ^ Jacobs, Andrew (5 July 2013). "Huge Algae Bloom Afflicts Coastal Chinese City". The New York Times.
  38. ^ "A Dark Bloom in the South Atlantic : Image of the Day". 30 January 2014. Retrieved 18 March 2017.
  39. ^ Tanber, George (2 August 2014). "Toxin leaves 500,000 in northwest Ohio without drinking water". Reuters. Retrieved 18 March 2017.
  40. ^ Abbott, Eileen (19 June 2019). "Bloom time: Chris Greene Lake dodges algae so far". Retrieved 19 June 2019.

Further reading

External links

Alexandrium catenella

Alexandrium catenella is a species of dinoflagellates. It is among the group of Alexandrium species that produce toxins that cause paralytic shellfish poisoning, and is a cause of red tide. These organisms have been found in the west coast of North America, Japan, Australia, and parts of South Africa.

Alexandrium catenella can occur in single cells (similar to A. fundyense), but more often they are seen in short chains of 2, 4, or 8 cells. The organism is typically 20–25 µm in length and 25–32 µm in width. The cells are compressed both in the anterior and posterior ends of this specimen. Alexandrium has two flagella that enable it to swim. While one flagellum encircles the cell causing the cell the rotate and move forward, the other extends behind the cell and controls the direction. In some instances, these organisms can appear like small trains moving in the water under a microscope.

The dinoflagellate produces saxitoxin, which is a highly potent neurotoxin. If consumed, this toxin can cause paralytic shellfish poisoning (PSP). By ingesting saxitoxin, humans can suffer from numbness, ataxia, incoherence, and in extreme cases respiratory paralysis and death. The toxin was discovered in 1927 in central California. Shellfish poisoning affected over a hundred humans, and now saxitoxin is recognized as one of the most deadly algal toxins.

These algal blooms have caused severe disruptions in the fisheries of these waters, and have caused filter-feeding shellfish in affected waters to become poisonous for human consumption. Because of this, A. catenella is categorized as a Harmful Algal Bloom (HAB) species. While in some areas the causes of HABs appears to be completely natural, in others, they appear to be a result of human activity, which is often coastal water pollution and over-fertilization.

Alexandrium catenella's multiplication is stimulated by higher ammonia and inorganic nitrogen concentrations. The optimal growth conditions for A. catenella include a cool temperature of around 17 to 23 °C, a medium to light illumination of 3500 to 4000 lux, and a high salinity of around 26 to 32 percent.


The Chroococcales are an order of cyanobacteria in some classifications which includes the harmful algal bloom Microcystis aeruginosa. Molecular data indicate that the members of the Chroococcales may not be a clade.


Cyanotoxins are toxins produced by bacteria called cyanobacteria (also known as blue-green algae). Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under high concentration of phosphorus conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such concentrations that they poison and even kill animals and humans. Cyanotoxins can also accumulate in other animals such as fish and shellfish, and cause poisonings such as shellfish poisoning.

Among cyanotoxins are some of the most powerful natural poisons known, including poisons which can cause rapid death by respiratory failure. The toxins include potent neurotoxins, hepatotoxins, cytotoxins, and endotoxins. Despite the similarity in name, they are not cyanides. Recreational exposure to cyanobacteria can result in gastro-intestinal and hay fever symptoms or pruritic skin rashes. Exposure to the cyanobacteria neurotoxin BMAA may be an environmental cause of neurodegenerative diseases such as ALS, Parkinson's Disease and Alzheimer's Disease. There is also an interest in the military potential of biological neurotoxins such as cyanotoxins, which "have gained increasing significance as potential candidates for weaponization."The first published report that blue-green algae or cyanobacteria could have lethal effects appeared in Nature in 1878. George Francis described the algal bloom he observed in the estuary of the Murray River in Australia, as "a thick scum like green oil paint, some two to six inches thick." Wildlife which drank the water died rapidly and terribly. Most reported incidents of poisoning by microalgal toxins have occurred in freshwater environments, and they are becoming more common and widespread. For example, thousands of ducks and geese died drinking contaminated water in the midwestern United States. In 2010, for the first time, marine mammals were reported to have died from ingesting cyanotoxins.


Eutrophication (from Greek eutrophos, "well-nourished"), or hypertrophication, is when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. This process may result in oxygen depletion of the water body. One example is an "algal bloom" or great increase of phytoplankton in a water body as a response to increased levels of nutrients. Eutrophication is often induced by the discharge of nitrate or phosphate-containing detergents, fertilizers, or sewage into an aquatic system.


Flaten is a lake in southern Stockholm, Sweden, located just north of Lake Drevviken. The name is also used for the surrounding area and the nature reserve created there in 2007.Flaten has the best water quality of all lakes around the Swedish capital and is highly popular for bathing and angling. The surrounding area is dominated by forests, with allotment-gardens and some industrial activities located north of the lake. Algal bloom occasionally occurs in spring.


HAB may refer to:

Hab, Cambodia

Hab River, in Pakistan

Battle of Hab, a 12th-century conflict

Book of Habakkuk, a book of the Hebrew Bible

The HAB Theory, a 1976 novel by Allan W. Eckert

Habrough railway station, England

Habilitation, a post-doctoral research stage in Europe and Asia

Habitat (disambiguation)

Hanoi Sign Language

Harmful algal bloom, a toxic or harmful concentration of algae

Home Affairs Bureau, Hong Kong

High-altitude balloon

High-altitude bombing

Hokuriku Asahi Broadcasting, a television station in Ishikawa Prefecture, Japan

Hospitality Awarding Body

Herzog August Bibliothek, a library in Wolfenbüttel, Germany.

Marion County – Rankin Fite Airport, serving Hamilton, Alabama, United States

Hangable Auto Bulb, a 1995 EP by electronic musician Richard D. James.

Harmful Algal Bloom and Hypoxia Research and Control Amendments Act of 2013

The Harmful Algal Bloom and Hypoxia Research and Control Amendments Act of 2013 (S. 1254; Pub.L. 113–121) is a U.S. public law that reauthorizes and modifies the Harmful Algal Bloom and Hypoxia Research and Control Act of 1998 and would authorize the appropriation of $20.5 million annually through 2018 for the National Oceanic and Atmospheric Administration (NOAA) to mitigate the harmful effects of algal blooms and hypoxia.The bill was introduced into the United States Senate during the 113th United States Congress.

Harmful algal bloom

A harmful algal bloom (HAB) contains organisms that can severely lower oxygen levels in natural waters, killing marine life. Some HABs are associated with algae-produced toxins. Blooms can last from a few days to many months. After the bloom dies, the microbes which decompose the dead algae use up even more of the oxygen, which can create fish die-offs. When these zones of depleted oxygen cover a large area for an extended period of time, they are referred to as dead zones, where neither fish nor plants are able to survive.

HABs are induced by an overabundance of nutrients in the water. The two most common nutrients are fixed nitrogen (nitrates, ammonia, urea) and phosphate. These nutrients are emitted by agriculture, other industries, excessive fertilizer use in urban/suburban areas and associated urban runoff. Higher water temperature and low circulation are contributing factors. HABs can cause significant harm to animals, the environment and economies. They have been increasing in size and frequency worldwide, a fact that many experts attribute to global climate change. The U.S. National Oceanic and Atmospheric Administration (NOAA) predicts more harmful blooms in the Pacific Ocean.

Heterosigma akashiwo

Heterosigma akashiwo is a species of microscopic algae of the class Raphidophyceae. It is a swimming marine alga that episodically forms toxic surface aggregations known as harmful algal bloom. The species name akashiwo is from the Japanese for "red tide".Synonyms include Olisthodiscus luteus (Hulburt 1965), and Entomosigma akashiwo (Hada 1967). H. akashiwo and H. inlandica have been recognized as two species of Heterosigma. However, Hara and Chihara (1987) described both specimens as one species, validly describing them as H. akashiwo.

Lake Rotoiti (Bay of Plenty)

Lake Rotoiti is a lake in the Bay of Plenty region of New Zealand. It is the northwesternmost in a chain of lakes formed within the Okataina caldera. The lake is close to the northern shore of its more famous neighbour, Lake Rotorua, and is connected to it via the Ohau Channel. It drains to the Kaituna River, which flows into the Bay of Plenty near Maketu.

The full name of the lake is Te Rotoiti-kite-a-Īhenga, which in the Māori language means "The Small Lake Discovered By Īhenga", the Māori explorer also credited with discovering Lake Rotorua. Legend says that the lake was named as such because when Ihenga first saw it, he was only able to see a small part of it and thought the lake was a lot smaller.

Since the 1960s, the quality of lake water has been negatively affected by inflows of nitrogen rich water from Lake Rotorua, agricultural run-off from surrounding farms and seepage from domestic septic tanks. The effects of this included an almost permanent algal bloom in the Okere arm of the lake and choking lake weed growth in other still areas of the lake. A barrier to divert the nutrient rich waters of Lake Rotorua into the Kaituna River was completed in late 2008.

The Bay of Plenty Regional Council expected to see improvement in lake water quality within five years and the Rotorua Te Arawa Lakes Program reported in 2013 that the intervention has significantly improved water quality. Water quality is the highest it has been in decades, on track to meet targets set by the Program to meet community expectations.Lake Rotoiti has thermal hot-spring baths on the southern shore which are accessible by boat.

Loch Eck

Loch Eck; (Gaelic: Loch Eich) is a freshwater loch located on the Cowal peninsula, north of Dunoon, Argyll and Bute, Scotland. It is seven miles long. Apart from Loch Lomond, it is the only naturally occurring habitat of the Powan (fish). Besides powan, the loch also has salmon, sea trout, brown trout and arctic charr.Loch Eck is within the Argyll Forest Park which, is itself part of the Loch Lomond and The Trossachs National Park. It is close to the Benmore Botanic Garden and the Benmore Outdoor Centre, which uses the loch and its surrounding for outdoor learning.A pathway runs along the west side of the loch, and gives access to the Paper Caves, set in the steep hillside with caving access to a platform set above a steep scarp within the cave. A legend holds that the Argyll family documents were hidden in the caves when the 9th Earl of Argyll was arrested, to prevent his lands from being made forfeit.The loch is also an impounding reservoir with a concrete dam measuring 0.870 metres high. The dam was completed in 1973. Loch Eck now supplies the freshwater to much of the southeast of Cowal, including Dunoon.In July 2013, two dogs died due to algal bloom present in the loch. Warnings were then posted advising that people and animals should avoid contact with the water.


LOHAFEX was an Ocean Iron Fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany. The experiment followed a Memorandum of Understanding signed on 30 October 2007 by Dr. T. Ramaswami, Director General, CSIR, and Dr. Juergen Mlynek, President, Helmholtz Foundation, Germany, on Cooperation in Marine Sciences, during the visit of the German Chancellor, Frau Angela Merkel to India. The experiment was conducted mainly by CSIR-National Institute of Oceanography (NIO), Goa, and Alfred-Wegener Institute (AWI) of Polar and Marine Research, Bremerhaven, with participation of scientists from Chile, France, Spain and UK. The German Research Vessel POLARSTERN was utilized for the experiment on her ANT XXV/3 cruise. It was jointly led by Wajih Naqvi of CSIR-NIO and Victor Smetacek of AWI. Weekly reports of the expedition were published on the website of AWI.A cyclonic eddy centred on 48 deg S, 16 deg E was selected for fertilization. The experiment began on India's Republic Day (26 January 2009). Ten tonnes of ferrous sulphate dissolved in seawater was spread over an area of 300 square kilometers, and the patch created was monitored for 38 days to investigate the effects of iron addition on marine biogeochemistry and ecosystem. Another iron addition of similar magnitude was done two weeks later. It was expected that iron addition would trigger algal bloom leading to sequestration of carbon dioxide from the atmosphere.

The ship left Cape Town 7 January 2009. The expedition ended after 70 days on 17 March 2009 in Punta Arenas, Chile.

Following protests from several NGOs, the German Government ordered a halt of the experiment. The environmentalists feared damage to marine ecosystem by an artificial algal bloom. The critics argued that long-term effects of ocean fertilization would not be detectable during short-term observation. Other critics feared the entry into large-scale manipulation of ecosystems with these large geo-engineering experiments. The German Government sent the proposal for scientific and legal reviews that were supportive of the project and the experiment was allowed to continue.

LOHAFEX was not the first experiment of its kind. In 2000 and 2004, comparable amounts of iron sulfate were discharged from the same ship ( EisenEx experiment). 10 to 20 percent of the algal bloom died off and sank to the sea floor. This removed carbon from the atmosphere, which is the intended carbon 'sink'.

As expected iron fertilization led to development of a bloom during LOHAFEX, but the chlorophyll increase within the fertilized patch, an indicator of biomass, was smaller than in previous experiments. The algal bloom also stimulated the growth of zooplankton that feed on them. The zooplankton in turn are consumed by higher organisms. Thus, ocean fertilization with iron also contributes to the carbon-fixing marine biomass of fish species which have been removed from the ocean by over-fishing.


Microcystaceae is family of cyanobacteria which contains the harmful algal bloom Microcystis aeruginosa.


Microcystis is a genus of freshwater cyanobacteria which includes the harmful algal bloom Microcystis aeruginosa. The cyanobacteria can produce neurotoxins and hepatotoxins, such as microcystin and cyanopeptolin.

Phosphates in detergent

Phosphates in detergent refers to the use of phosphates as an ingredient in a detergent product. The advantage of using phosphates in a consumer laundry detergent or dishwashing detergent is that they make detergents more efficient by chelating calcium and magnesium ions. The disadvantage of using phosphates is that they remain in wastewater and eventually make their way to a natural body of water. While phosphates are low toxicity, they instead cause nutrient pollution and feed the algae. This leads to eutrophication and harmful algal bloom.Many countries have banned the use of phosphates in detergent, including the European Union and the United States.Independent product testing noted that manufacturers reformulated their products after bans. Those reports indicated that the new products without phosphates were satisfactory.

Popes Creek (Virginia)

Coordinates: 38°11′29″N 76°54′16″WPope's Creek is a 5.3-mile-long (8.5 km) tidal tributary of the Potomac River in Westmoreland County, Virginia. The George Washington Birthplace National Monument lies along the north side of Popes Creek. Popes Creek landing is located at 38°11′29″N 76°54′16″W.

Red tide

Red tide is a common name for algal blooms, which are large concentrations of aquatic microorganisms, such as protozoans and unicellular algae (e.g. dinoflagellates and diatoms). The upwelling of nutrients from the sea floor, often following massive storms, provides for the algae and triggers bloom events. Harmful algal blooms can occur worldwide, and natural cycles can vary regionally.The growth and persistence of an algal bloom depends on wind direction and strength, temperature, nutrients, and salinity. Red tide species can be found in oceans, bays, and estuaries, but they cannot thrive in freshwater environments. Certain species of phytoplankton and dinoflagellates found in red tides contain photosynthetic pigments that vary in color from brown to red. When the algae are present in high concentrations, the water may appear to be discolored or murky. The most conspicuous effects of red tides are the associated wildlife mortalities and harmful human exposure. The production of natural toxins such as brevetoxins and ichthyotoxins are harmful to marine life.

Richard Vollenweider

Richard Albert Vollenweider (June 22, 1922 in Zürich, Switzerland – January 20, 2007 in Burlington, Ontario, Canada) was a notable limnologist.

Richard Vollenweider wrote several widely cited academic works about lake eutrophication management. His pioneering work included a technical report from 1968, which related inputs of total phosphorus to chlorophyll a concentrations (a common proxy measure of algal bloom intensity).

His findings thereby laid the ground for predicting expected environmental effects on the Secchi depth and algal bloom intensity from phosphorus abatement, e.g., in sewage treatment plants.

He also played an important role in restoring several eutrophicated lakes, such as the Great Lakes of North America.

Richard Vollenweider was awarded the Tyler Environmental Prize (1986), the Naumann-Thiennemann Medal by SIL (1987), the Global 500 Roll of Honor by UNEP (1988), and the Premio Internationale Cervia for his advise on eutrophication in the Adriatic Sea (Italy). On June 2, 1989 Vollenweider received an honorary doctorate from the Faculty of Mathematics and Science at Uppsala University, Sweden

The blob (Chukchi Sea algae)

The blob was the name given to a large black algal bloom that was first spotted floating in the Chukchi Sea between the Alaskan cities of Wainwright and Utqiaġvik in July 2009.

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