22/12/09
Blue-Green Algae in Recreational Water Management Strategy
This management strategy replaces the ACT Guidelines for the Management of Blue-Green Algae in Recreational Water. This management strategy has been developed based on the
recommendations of the National Health and Medical Research Council’s Guidelines for Managing Risks in Recreational Water (2008).
1.0 Introduction
Cyanobacteria, commonly referred to as blue-green algae, are found in all waters and form part of the phytoplankton and the benthos. Naturally-occurring low levels of blue-green algae are of benefit due to their nitrogen fixing capabilities. However, in excessive numbers (blooms) blue-green algae cause problems by giving rise to odours and taints, or by producing toxins.
The predominant species of blue-green algae found in the ACT’s lakes and rivers are Microcystis spp. and Anabaena spp.
During certain times of the year the occurrence of Tychonema bornetti is predominant. This species is benthic and will only grow attached to objects such as sand, rocks and possibly ribbon weed. During the process of photosynthesis, oxygen bubbles can become trapped in the benthic mats, causing them to float to the surface where they die, releasing toxins into the
water.
2.0 Scope
This paper outlines a management strategy for recreational waters in the ACT in the event of algal blooms. The management strategy provides a uniform approach for all managers of ACT waterways to ensure consistency and increase public understanding of the blue-green algal risk.
The approach outlined in this paper is based on a preventive, risk-management approach and will provide guidance on free floating blue-green algae, as well as the benthic Tychonema sp.
3.0 Health Effects
3.1 Exposure
There are three potential routes of exposure to blue-green algal toxins:
- · direct contact with exposed parts of the body, including sensitive areas such as the ears, eyes, mouth, nose and throat;
- · accidental swallowing; and
- · inhalation of water.
Reactions are unpredictable as certain individuals are more sensitive to algal exposure or may have underlying medical conditions that increase their reaction. The risks associated with blue-green algae also vary depending on length and type of contact.
Important toxin exposure routes during water contact sports include accidental swallowing, contact with nasal mucosa and inhalation. There have been reported cases of people becoming sick after exposure via inhalation and absorption through nasal and pharyngeal mucous membranes in water sports involving submersion of the head (jumping from diving
boards, sail boarding, canoe capsizing, and swimming) and inhalation of aerosols (water skiing).
The greatest risk to recreational users is posed by algal surface scums. These are concentrated accumulations of blue-green algae which tend to settle along shorelines, where
recreational users are likely to come in contact with them as they enter the water.
Primary contact recreation
This involves whole-body contact in which the entire body or the face and trunk are frequently immersed or the face is frequently wet by spray, and where it is likely that some water will be swallowed, inhaled, or come into contact with ears, nasal passages, mucous membranes or cuts in the skin (e.g. swimming, diving, waterskiing, windsurfing, white-water canoeing).
Secondary-contact recreation
This may involve incidental contact in which only the limbs are regularly wet and in which greater contact is unusual (e.g. boating, fishing, canoeing, rowing). There may be occasional
and inadvertent immersion through accidents (e.g. slipping into water).
3.2 Toxins
Blue-green algae can produce three types of toxins, each with different modes of action.
Hepatotoxins
These are the most common of the blue-green algal toxins. They attack the liver and other internal organs. They may also cause visual disturbances, gastroenteritis, nausea, vomiting
and muscle weakness. They are slower acting than neurotoxins. They can be produced by such species as Anabaena, Cylindrospermopsis, Microcystis, Nodularia, and Oscillatoria.
Neurotoxins
These act as neuromuscular blocking agents. They produce death by paralysis of peripheral skeletal muscles, then respiratory muscles, leading to respiratory arrest. Neurotoxins are
produced by species of Anabaena, Aphanizomenon, Nostoc and Oscillatoria.
Endotoxins
The outer walls of all blue-green algae contain lipopolysaccharides. These are mainly contact irritants and can cause severe dermatitis and conjunctivitis in people coming into contact with the algae through swimming or water spray. They may also cause stomach cramps, nausea, fever and headaches. If swallowed, they may also cause irritation to airways and breathing difficulties.
There have been many reported cases of adverse health events for recreationists exposed to blue-green algae blooms. The symptoms include itchy contact dermatitis, hay fever like
symptoms, conjunctivitis and asthma. Gastroenteritis may result from accidentally ingesting the water.
3.3 Potential Toxicity of Blue-Green Algae Species
This list below is to provide an indication of potential toxicity of certain genera. This list is not complete and provides an indication only of the potential toxicity, and hence potential risk, to recreational users of contaminated water.
High Risk Potential Risk Lower Risk
Microcystis sp Aphanizomenon sp. Cyanodictyon sp.
Anabaena sp. Planktothrix sp. Aphanocapsa sp.
Pseudoanabaena sp. Chroococcus sp.
Phormidium sp.
4.0 Management
4.1 Biovolume
Biovolume is the measure of space occupied by the algae. It is used as a quantitative measure of the volume of algae cell material in the sample.
The size of cells can vary within and between algae species. Toxin concentration relates more closely to the amount of dry matter in a sample than the number of algal cells. Therefore, biovolume has been included in the assessment process to account for mixed species or small algal cells in water samples.
Cell counts should be used as the primary source for determining risks from recreational activities. The biovolume should be used for determining the risks associated with mixed
species where a known toxin producer is dominant or small algae such as Aphanocapsa spp., Aphanothece spp., Cyanodictyon spp., Chroococcus spp.,or Radiocystis spp. are dominant.
4.2 Inspections and Observations
If visual inspections detect changes (e.g. colour of water, appearance of surface scums), cell counts and species identification should be undertaken to determine the suitability of the water for recreational activities. Water samples are to be taken from the swimming areas of the relevant lakes.
If identification reveals that the blue-green algae are dominated by small species, biovolume should be determined to provide additional data in assessing the suitability of the water body for recreational use.
4.3 Toxicity Testing
Research has shown that toxin production varies during a bloom and that a bloom may be toxic one week and not toxic the next. There are a large number of toxins produced and current toxicity testing only identifies a few. In addition, there is no way to accurately forecast what level of toxins will be produced in coming days or weeks. Based on the uncertainty from the testing and delay in receiving results, there is very little benefit to toxicity testing of recreational water from a public health perspective.
5.0 Blue-Green Algae Action Plan
Alert level Blue-green algae Biovolume Monitoring Typical actions
cells/ml* equivalent* requirements (NCA^, EPA^^ or ACT Health)
Low >500 to <5,000 >0.04 to<0.4 mm3/L. Weekly visual NCA/EPA: Maintain routine
inspections. monitoring.
Medium >5, 000 to <50,000 >0.4 to < 4mm3/L Increase to twice NCA/EPA: Increase visual
weekly visual inspections and
inspections & take sampling for algal counts.
water samples as
required.
>20,000 >1.6 mm3/L NCA/EPA: If > 20,000 cells/mL,
advise ACT Health &, following
advice from ACT Health, post
on-site warning signs to
indicate increased risks for skin
irritations, gastrointestinal illness.
NCA/EPA: Issue Media release to
public and lake users.
High >50,000 to <125, 000 >4 mm3/L to<10 mm3/L Maintain twice NCA/EPA: Maintain increased visual
weekly visual inspections. Regular algal counts.
inspections and
take wate samples
as required.
NCA/EPA: Advise ACT Health.
NCA/EPA: Advise public that water, or
part thereof, is closed for primary contact
users following advice from ACT Health.
NCA/EPA: Issue Media release to public
and lake users to indicate lake closed
rom primary contact use.
NCA/EPA: Change lake warning signs to
indicate lake closed for primary contact use.
Extreme >125,000 or >10 mm3/L Maintain twice weekly NCA/EPA: Advise ACT Health.
scums are visual inspections and take
consistently water samples as required. NCA/EPA: Advise public that contact
present** with water, or part thereof, poses an
(40,000 cells/mL increased level of risk for secondary
Anabaena sp.) contact users following advice from
ACT Health.
The risks associated with secondary
contact use at this alert level may be
reduced provided that:
· users are experienced;
· users understand the algae risk and
what to do if contact occurs;
· users do not engage in primarycontact;
and
· showers, with suitable water, are
available after recreation.
NCA/EPA: Issue Media release to public
and lake users.
* Figures refer to Microcystis aeruginosa only.
** Persistent scums are scums that are seen at some time each day at the recreational site.
^ National Capital Authority (NCA) – Commonwealth department responsible for Lake Burley Griffin.
^^ Environment Protection Authority (EPA) – ACT Government unit responsible for ACT waters.
5.1 Decreasing Alert Levels over Time
Reductions in alert levels from a higher to a lower level should not occur until the results from two consecutive samples have recorded lower counts and anticipated environmental conditions (e.g. temperature etc) are not conducive to facilitating a rapid increase in blue-green algae populations.
5.2 Tychonema sp. Action Plan
The advice to the public on the blue-green algae Tychonema sp. is based on visual site inspections and the detection of benthic growth or in worst-case situations floating clumps of
Tychonema.
Alert level Inspection Monitoring requirements Typical actions
Low No obvious Weekly visual inspections. Maintain routine monitoring.
benthic growth
Medium Benthic growth Twice weekly visual inspections. Maintain visual inspections and
observed indicate risk on permanent warning signs.
High Obvious benthic Maintain twice weekly visual After advice from ACT Health, close
growth and inspections and take a water sample affected area of the lake to primary
floating mats to confirm the identity of the algae. contact recreation. Change warning signs to reflect this closure.
5.3 Lake Burley Griffin Captain Cook Memorial Jet Action Plan
The jet fountain shoots water approximately 100 metres above the lake. Winds can create fine mists and cause it to travel to areas around the lake. This may expose the public to algae during an algal bloom through direct contact with, or inhalation of, the mist.
Blue-green algae cells/mL Biovolume equivalent Typical actions
>50,000 >4 mm3/L Turn off water jet
6.0 Agency Responsibilities
ACT lakes are inspected weekly to detect visual changes in water quality. The inspection results are updated and made available on the National Capital Authority (NCA) and
Department of the Environment Climate Change, Energy and Water (DECCEW) web sites. If algae are assessed to be at significant levels in any of the lakes, water samples are taken to determine the blue-green algal count.
The Health Protection Service (HPS) of ACT Health assesses information provided by the NCA for Lake Burley Griffin and/or the Environment Protection Authority (EPA) (part of DECCEW) for Lake Tuggeranong, Ginninderra, Yerribi, Gungahlin, Point Hut Pond and Molonglo River.
The HPS then provides advice on the course of action e.g. changing of warning signs or lake closures.
The HPS also provides advice on the health effects of algae, including routes of exposure, toxicity of the various species and exposure symptoms.
7.0 Advice from ACT Health
The collection of samples and availability of results is critical when providing advice to recreational users on the health risks and possible closures of a water body.
To provide timely advice to event organisers for weekend events, ACT Health requires the results from samples by 10.00 am on Thursdays.
Reductions in alert levels from a higher to a lower level require two consecutive samples to have recorded lower counts. For example, samples should be taken on Monday and
Wednesday to provide information by 10.00 am Thursday.
8.0 Warning Signs
Permanent warning signs are to be present at high-traffic water entry areas. These warning signs are to be changeable to indicate the current risk posed by blue-green algae. The EPA is responsible for changing the warning signs at the waters they manage in response to changes in blue-green algae risk levels.
The NCA will be responsible for changing warning signs at LBG in response to changes in blue-green algae risk levels.
9.0 Media
The NCA and DECCEW, in consultation with ACT Health, will issue media releases for Medium, High and Extreme blue-green algae alert levels. They will also advise key stakeholders of changes in these alert levels.
Key points for media messages when blue-green algae counts reach >20,000 cells/ml or biovolume is >1.6 mm3/L) include:
- that some susceptible individuals may experience skin irritations, hay fever-like symptoms or flu-like symptoms after contact with affected water;
- that water users should shower after water contact and avoid submersion; and
- that water users should look for algae warnings signs indicating the current alert level at major water entry points.
Key points for media messages when blue-green algae counts reach the High alert level (algae counts are >50,000 cells/ml or biovolume is >4 mm3/L) include:
- that there is an increased risk of adverse health events from water exposure;
- that symptoms of exposure may include skin/mucosa irritation, flu-like symptoms, and gastrointestinal illness;
- that the affected water is closed to primary contact recreation (including swimming, diving, water skiing and windsurfing);
- that persons engaged in secondary contact recreation should be careful to limit any water exposure;
- that water users should shower after water contact;
- that event organisers should ensure that participants are aware of the blue-green algae alert level, associated exposure risks and provide adequate showering facilities
- for after events; and
- that water users should look for algae warnings signs indicating the current alert level at major water entry points.
Key points for media messages when blue-green algae counts reach the Extreme alert level (algae counts are >125,000 cells/ml, scums are persistent, or biovolume is >10 mm3/L) include:
- a reiteration that waters, or part thereof, are closed to primary contact recreation (including swimming, diving, water skiing and windsurfing);
- that there is an increased risk of adverse health events from water exposure for secondary contact recreation;
- that symptoms of exposure may include skin/mucosa irritation, flu-like symptoms, and gastrointestinal illness;
- that people should not engage in secondary contact recreation unless:
- they are experienced;
- they are informed of the algal risks and what to do if contact occurs;
- they do not engage in primary-contact during the recreation; and
- showering facilities, with suitable water, are available for washing after the recreation;
- that event organisers should ensure that participants are aware of the blue-green algae alert level, associated exposure risks and provide adequate showering facilities for after events; and
- that water users should look for algae warnings signs indicating the current alert level at major water entry points.
10.0 Contacts
Health Protection Service
ACT Health
Locked Bag No. 5
Weston Creek ACT 2611
Phone: 6205 1700
Fax: 6205 1705
Website: www.health.act.gov.au/hps
National Capital Authority
Commonwealth Government
GPO Box 373
Canberra ACT 2601
Phone: 6271 2888
Fax: 6273 4427
Website: www.nationalcapital.gov.au
Environment Protection Authority
Department of the Environment, Climate Change, Energy and Water
GPO Box 158
Canberra City 2601
Phone: 13 22 81
Fax: 6207 6084
Website: http://www.environment.act.gov.au
