Biological Hazard – Toxic Cyanobacteria Algae: Cardrona River, New Zealand
TOXIC ALGAE – NEW ZEALAND (02): (OTAGO) BLUE-GREEN ALGAE, CANINE DEATHS
Published Date: 2016-02-21 20:35:05
Subject: PRO/AH/EDR> Toxic algae – New Zealand (02): (OT) blue-green algae, canine deaths
Archive Number: 20160221.4039687
Date: 20 Feb 2016
Source: Otaga Daily times.com.nz [edited]
River warning after dog deaths
The Otago Regional Council (ORC) says the toxic algae which caused the death of 2 dogs in the Cardrona River this week can be toxic to people and is warning people to stay away from the river.
Cyanobacteria algae mats were discovered by ORC surveyors in the Cardrona River near the Larches Bridge on Monday, following the death of a dog from toxic algae poisoning in the area on Saturday.
On Monday another dog died from suspected toxic algae poisoning after being near the river, close to Riverbank Rd in Wanaka, on Sunday.
ORC resource science manager Dean Olsen said the algae could be toxic to people, and it was most dangerous when consumed. “Members of the public should not swim, fish, or carry out any other recreational activity in an affected river. The poison can be absorbed through the skin, so direct contact should be avoided.”
Symptoms [in human beings] could include skin rashes, nausea, stomach cramps, and tingling and numbness around the mouth and fingertips.
Dr Olsen said the council had erected warning signs near State Highway 6, between Wanaka and Luggate, the Albert Town Reserve, the river access point on Ballantyne Rd, and near the Larches Bridge on Cardrona Valley Rd.
The council received samples and photos of the algae on Tuesday, he said.
“The reason signs didn’t go up straight away is because we didn’t actually have signs for cyanobacteria in the Wanaka depot, Dr Olsen said. And the reason for that is that we have actually never had an issue along these lines in Wanaka.”
Yesterday the council confirmed samples of algae taken from the river were toxic.
“The lab said that the concentration of toxins was very high, and that eating only a small amount could prove fatal to dogs,” Dr Olsen said.
He said the council “could have been a bit faster” to alert the public to the risk. “Given that we have never had a toxic cyanobacteria bloom in the Cardrona before, I think the response, the first step of the response, was really to confirm what we are dealing with. Certainly we will be learning from this and we will have signs in Wanaka.”
He said the algae was the result of high temperatures and low rivers.
“It has just been a total lack of floods for a number of months, so this is an exceptional set of circumstances.”
Heavy rain on Wednesday and Thursday might have lifted the risk of algal bloom, Dr Olsen said.
ProMED-mail from HealthMap Alerts
[There are a number of very toxic blue-green algae or cyanobacteria. The toxin may be present even if the algae are not, and likewise the algae may be present but the toxin may not be. However, safety for humans and animals means avoiding bodies of water with any blue-green algae.
“There are a number of blue-green algae, many of which are toxic, frequently resulting in rapid death for animals. Blue-green algae, also known as cyanobacteria, are a group of photosynthetic bacteria that many people refer to as ‘pond scum.’ Blue-green algae are most often blue-green in color, but can also be blue, green, reddish-purple, or brown. Blue-green algae generally grow in lakes, ponds, and slow-moving streams when the water is warm and enriched with nutrients like phosphorus or nitrogen.
“When environmental conditions are just right, blue-green algae can grow very quickly. Most species are buoyant and will float to the surface, where they form scum layers or floating mats. When this happens, we call this a ‘blue-green algae bloom.’ Blue-green algae blooms generally occur between mid-June and late September, although in rare instances, blooms have been observed in winter, even under the ice.
“Many different species of blue-green algae occur, but the most commonly detected include _Anabaena_ sp, _Aphanizomenon_ sp, _Microcystis_ sp, and _Planktothrix_ sp. It is not always the same species that blooms in a given water body, and the dominant species can change over the course of the season.
“Blue-green algal toxins are naturally produced chemical compounds that sometimes are produced inside the cells of certain species of blue-green algae. These chemicals are not produced all of the time, and there is no easy way to tell when blue-green algae are producing them and when they are not. When the cells are broken open, the toxins may be released. Sometimes this occurs when the cells die off naturally and they break open as they sink and decay in a lake or pond. Cells may also be broken open when the water is treated with chemicals meant to kill algae, and when cells are swallowed and mixed with digestive acids in the stomachs of people or animals.
“Typical clinical signs in dogs exposed to blue-green algae include seizures, vomiting, and/or diarrhea after contact with surface water. Although the water appears clear, if a ‘bloom’ is just starting, it may be difficult to see any sheen, an early indication of blue-green algae formation. Some forms of blue-green algae may start forming slightly below the surface and may not be visible, but are just as toxic.
“1 toxic alga frequently involved in illness and deaths is _Microcystis aeruginosa_, a single-celled blue green alga, or cyanobacterium, that occurs naturally in surface waters. Microcystis can proliferate to form dense blooms and mats under certain conditions. Many variants of these cyanobacteria produce multiple toxins, including the potent liver toxin microcystin. When microcystis die, their cells break open, releasing the toxin microcystin into the water. Ingestion of water or algal cells containing microcystin has produced adverse effects in fish, dogs, cats, livestock, and humans. Sometimes the mats and the sheen of the organisms are visible on the surface of the water, if it is a pond. In larger bodies of water, such as large lakes, it may be more difficult or impossible to see the sheen or the mat of accumulation.
“People swimming in dense microcystis blooms have experienced irritation such as skin rashes, burns, and blistering of the mouth. Ingestion or inhalation of water containing dense bloom material may cause vomiting, nausea, headaches, diarrhea, pneumonia, and fever. Ingestion of significant levels of the toxin microcystin can cause liver damage and dysfunction in humans and animals. No deaths from ingestion of microcystins have been reported in humans in the US; however, Brazil has reported human deaths. Dogs, wildlife, and livestock have died following exposure to this toxin.
“Microcystis blooms typically thrive in warm, turbid, and slow-moving waters. The blooms with the highest biomass occur in waters that are high in nitrogen or phosphorus (eutrophic waters). Microcystis also requires sufficient light intensity to conduct photosynthesis, which results in blooms.
“The commonest route of exposure to microcystin is drinking water, followed by recreational exposures and food supplements. Typical water treatment processes do not fully remove microcystin that might be present in drinking water supplies stored in reservoirs. Swimming and playing in water that contains, or recently contained, microcystis blooms is another common exposure route. Children have the highest risk of exposure since they tend to unintentionally ingest water while swimming. Microcystin can move through the aquatic food web, exposing fish and shellfish, as well as the people who consume them. Microcystin does not remain in edible fish and shellfish tissues for more than a few weeks. However, people who frequently consume sport fish caught from a water body that supports microcystis blooms have a higher risk of exposure. Dogs can ingest large amounts of microcystis cells when they clean their coats after playing in water. Livestock, wildlife, and dogs are exposed through drinking water containing microcystis or through ingesting algal mats.”
Toxins produced by blue-green algae
Toxins are compounds that have a harmful effect on other cells, tissues and organisms. In the natural environment, these toxins are generally contained within the blue-green algal cell but they are released into the water when the cell is damaged or dies.
Blue-green algal toxins can be divided into the following groups:
– Hepatotoxins cause blood to collect in the liver causing circulatory shock and can lead to death by internal hemorrhaging.
– Hepatotoxins can cause weakness, vomiting and diarrhoea.
– Nodularin and microcystin are 2 types of hepatotoxins.
– Nodularin is produced by the algal species _Nodularia spumigena_.
– In NSW [New South Wales, Australia], microcystin is produced by _Microcystis_.
– Microcystins can bioaccumulate in aquatic invertebrates such as mussels so aquatic animals caught from water where there is an algal bloom should not be eaten.
– Neurotoxins interfere with the functioning of the nervous system and can cause death of humans and animals within minutes by causing paralysis of the respiratory muscles.
– In NSW, a neurotoxin known as saxitoxin is produced by the blue-green alga _Anabaena_.
– Marine dinoflagellates (red tides) produce saxitoxins (also known as paralytic shellfish poisons) which concentrate in shellfish and have been known to cause death in humans.
3. Non-specific Toxins
– Cylindrospermopsin is a non-specific toxin that in NSW is produced by the blue-green algae _Cylindrospermopsis raciborskii_ and _Aphanizomenon ovalisporum_.
– This toxin is a relatively slow-acting toxin that damages most organs in the body including the liver.
4. Dermatoxic Lipopolysachharides
– When non-toxic species of blue-green algae are present at concentrations above 10 cubic mm per litre, the water may still pose a risk to recreational and domestic users as all blue-green algae have lipopolysachharides in their cell walls.
– Lipopolysachharides are less toxic than hepatotoxins or neurotoxins but are significant in terms of water supply for drinking, showering and recreation.
– Lipopolysachharides have been associated with outbreaks of gastroenteritis, skin and eye irritations and hay fever, in humans who have come into contact with algal blooms. Humans who contact lipopolysachharides in the aerosol form (fine spray e.g. sprinkler) may suffer asthma, eczema, and blisters in the lining of the nose and mouth.
Portions of this comment were extracted from http://oehha.ca.gov/ecotox/pdf/microfactsheet122408.pdf. Portions of this comment have been extracted from: http://www.water.nsw.gov.au/water-management/water-quality/algal-information. – Mod.TG
A HealthMap/ProMED-mail map can be accessed at: http://healthmap.org/promed/p/1621.]
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