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Lyngbya majuscula (Lyngbya) is a naturally occurring, thread-like, marine cyanobacterium.  It occurs naturally in Queensland coastal waters growing attached to seagrass, corals and other shallow substrates. On occasions it can grow rapidly to form an algal bloom. When the algae is in bloom proportions it often detaches from the substrate and floats in mats across the surface of the ocean, sometimes washing onto surrounding beaches where it can cause human health and odour problems.

Scientific and common names

Microscopic view of Lyngbya filament (courtesy: University of Queensland).

Microscopic view of Lyngbya filament (courtesy: University of Queensland).

The scientific name of the cyanobacterium (blue-green algae) is Lyngbya majuscula, but it is also commonly known as Mermaid Hair, Stinging Limu and Fire Weed—a name that has caused some confusion in the wider community. Fire weed was the name first given to Lyngbya by the Fraser Island community due to the similarity of its contact symptoms and the symptoms from another organism, ‘fireweed’, which is a small hydroid with stinging cells commonly found in the waters of south-east Queensland.

Basic features

A detached piece of Lyngbya (courtesy: University of Queensland).

A detached piece of Lyngbya (courtesy: University of Queensland).

Lyngbya is a potentially toxic, marine cyanobacterium (blue-green algae). It grows attached to seagrass, seaweed (macroalgae), coral and the sediment in clumps or mats of fine, dark, cotton wool-like strands 10 to 30 centimetres long. When Lyngbya is present in large amounts it accumulates gas bubbles (from high rates of photosynthesis) around the filaments causing the clumps to rise to the surface and form large conspicuous floating mats. Floating Lyngbya may wash up on beaches, often mixed with seagrass.

Where does it grow?

Common bloom areas in Moreton Bay including the Pumicestone Passage, northern Deception Bay and eastern Moreton Bay.

Common bloom areas in Moreton Bay including the Pumicestone Passage, northern Deception Bay and eastern Moreton Bay.

Lyngbya is common in seagrass and coral reef habitats in tropical and subtropical waters worldwide. Dense blooms of Lyngbya have occured in various locations around the world including Hawaii, United State of America, where they were first reported as toxic during the 1950’s. In coastal Queensland, blooms have been recorded in both urban and more pristine areas such as Hardy Reef and the Whitsunday Islands, in the Great Barrier Reef, Shoalwater Bay and Fraser Island. The most prolific blooms reported have been in Moreton Bay, south-east Queensland with common bloom areas including Pumicestone Passage, northern Deception Bay and eastern Moreton Bay (shown below).

Major bloom events in south-east Queensland coastal waters during the late 1990’s and 2000, prompted the Queensland Government to facilitate a coordinated response by State and local government and key stakeholders. As part of this coordinated effort, the Department of Environment and Heritage Protection (EHP) will continue to provide up-to-date information on Lyngbya outbreaks and its management on this website.

Impacts of Lyngbya blooms

Lyngbya bloom washed onto foreshores in Deception Bay and smothering mangrove roots (courtesy: Moreton Bay Regional Council).

Lyngbya bloom washed onto foreshores in Deception Bay and smothering mangrove roots (courtesy: Moreton Bay Regional Council).

Lyngbya blooms have impacted on the environment and people’s health. While contact with Lyngbya is generally rare, it is more likely to occur under bloom conditions and during close contact. The blooms in Moreton Bay were first reported by local fisherman who experienced severe dermatitis and asthma-like symptoms. Generally fish do not swim in areas affected by Lyngbya and tend to leave these areas to find waters that are not affected. This may reduce the available catch for the fishing industry and recreational fishermen. In a large bloom, oyster leases may be impacted because of concern about toxins from the Lyngbya.

Lyngbya can smother seagrass, coral and other benthic habitats. In significant bloom conditions, such as occurred in 2000 in Moreton Bay, blooms may be associated with reduced reproductive success in sea turtle species. This may be due to a food shortage impact because turtles avoid the seagrass covered in Lyngbya or due to the impact of Lyngbya toxins.  

Large blooms of Lyngbya washed onto public beaches can create odour issues and often requires management to minimise any potential public health impacts.

Causes of Lyngbya blooms

Over recent decades blooms have increased in tropical and subtropical regions around the world. The key environmental conditions for Lyngbya growth appear to be the presence of bio-available nutrients phosphorus, nitrogen and iron; dissolved organic matter; and favourable light, salinity and temperature conditions in the environment. Land uses and management activities that alter groundwater levels and surface water runoff, in association with major rainfall events, result in significant loads of these nutrients transported to coastal waters.

The bloom in Hardy Reef, near the Whitsunday Islands in the Great Barrier Reef was thought to be associated with the installation of a tourist helicopter platform. The platform provided a roost for hundreds of sea-birds which resulted in increased nutrients from the bird-derived waste.

Blooms in Deception Bay are thought to be triggered by high concentrations of nutrients and bio-available iron being discharged into the marine environment from wet-weather surface run-off and some groundwater discharges. In contrast, blooms on the eastern banks are considered to be primarily a result of groundwater discharges or some other forms of environmental disturbance. Blooms have also occurred, however, in the relatively pristine areas of Shoalwater Bay.

Causes of Lyngbya blooms - conceptual diagram

Conceptual diagram summarising the current understanding of causes of Lyngbya blooms in Deception Bay. Source: Coastal Algal Bloom Action (SEQHWP, 2008). Note: Key nutrients (iron, phosphorus, nitrogen and dissolved organic carbon) move from the catchment through surface and groundwater into Deception Bay and onto the seagrass flats. There they are sequested in the sediments and subsequently become available for Lyngbya growth or are immediately available for uptake from the water column.

Health advice

Lyngbya is a contact irritant that can produce skin and eye irritation following direct contact. In severe cases, affected skin may blister and peel off. Lyngbya has the potential to irritate any part of the body that it comes into contact with. Thus, inhalation or ingestion of Lyngbya can cause irritation to the respiratory and gastrointestinal tracts. The severity of irritation usually depends on the level of exposure.

People who have come into contact with Lyngbya may complain of a stinging, burning or itching sensation within minutes or hours after exposure. Affected areas may appear red and swollen, and small blisters may form. Reddening and swelling of the conjunctiva of the eye and the mucous membrane of the nose can occur if those parts of the body have direct contact with Lyngbya. In view of its potential to cause severe irritation, people should avoid areas affected by Lyngbya if at all possible.

Safe handling of Lyngbya

People conducting or undertaking business are obliged to ensure the workplace health and safety of themselves, their workers and others where occupational exposure to harmful algae may occur. Managing occupational exposure to toxic algae can be done by conducting a risk assessment of the work task, considering the likelihood and consequences of exposure, implementing appropriate control measures, and monitoring and reviewing the effectiveness of the control measures.

A fact sheet on managing occupational exposure to Lyngbya algal toxins (PDF)* is available from the Workplace Health and Safety Queensland website.

For more information see Workplace Health and Safety Queensland or phone 1300 369 915.

Further information on collecting (for identification purposes), handling and transporting of Lyngbya are outlined in the document Queensland Harmful Algal Bloom Operational Procedures. 

Advice to the general public

People should avoid swimming or wading in areas where Lyngbya is growing or floating in the water and should not have direct contact with material washed onto the beach. Local councils may clear large amounts of Lyngbya that has washed onto high-use public beaches. See the contact list below to obtain local beach and swimming information.

If you have any of the symptoms listed above, and have been in an area affected by the algae, see your doctor.

South-east Queensland contacts

For current and historical monitoring information in Moreton Bay:

For local information, updates or beach and swimming reports for:

North Stradbroke Island and other Redland City Council related matters:

  • Customer Service Centre (07) 3829 8999.

Marine Park related matters:

  • Moreton Bay Marine Park (07) 3131 2888.

National Parks:

  • Bribie Island National Park (07) 3408 8451;
  • Moreton Island National Park (07) 3408 2710.

Deception Bay, Bribie Island and other Moreton Bay Regional Council related matters:

  • Caboolture District Customer Service Centre (07) 5433 3000;
  • Redcliffe District Customer Service Centre, (07) 3283 0233.

Northern Pumicestone Passage and other Sunshine Coast Regional Council related matters:

  • Sunshine Coast Regional Council Customer Service 1300 007 272 (local, excluding calls from mobiles) or (07) 5475 7272 (outside the local area).

For matters relating to Brisbane City Council:

  • Brisbane City Council Customer Service Centre (07) 3403 8888.

For matters relating to Gold Coast City Council:

  • Catchment Management Unit, (07) 5581 6722 or consult the waterways section of the Gold Coast City Council website.

To report incidents of pollution, fish kills or potential environmental harm:

Queensland-wide contacts

For local information, updates or beach and swimming reports, please contact the relevant local government customer service centre.

To report incidents of pollution, fish kills or potential environmental harm:

Marine Parks:

  • Great Sandy Marine Park (07) 4197 4002;
  • Great Barrier Reef Marine Park (07) 4726 0501.

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Last updated
29 June 2012