Harmful algal blooms in the marine environment: the Tasmanian experience. Helena Bobbi, Environmental Health Officer

Transcription

1 Harmful algal blooms in the marine environment: the Tasmanian experience Helena Bobbi, Environmental Health Officer

2 Overview Harmful Algal Blooms (HABs) Toxins Recent History Impacts on Industry/Food Regulatory Issues Public Health Issues and Wild Shellfish Raising Public Awareness

3 What are they? Harmful Algal Blooms HABs HABs are colonies of algae (phytoplankton) growing out of control Can cover large areas and spread over hundreds of kms They contain species of algae that produce biotoxins Rapid growth occurs when environmental conditions favour a particular species of algae: temperature stratification of water body nutrients rainfall currents airflow Algae that produce biotoxins + the right environmental conditions = HAB

4 How are they harmful? Harmful Algal Blooms - HABs Biotoxins accumulate in species that feed on the algae Filter feeding species eg. shellfish like oysters and mussels accumulate the biotoxins in their flesh/viscera Mussels accumulate biotoxins rapidly (within 2-3 days of a HAB): a sentinel species indicator of the risks to human health from consuming shellfish and other affected species There is a very real risk to human health from shellfish poisoning during a HAB The Food Standards Code prescribes toxin limits

5 The toxins Toxins are produced by a range of species of Diatoms and Dinoflagellates (micro algae): Non-fatal toxins DST: Diarrhoeal shellfish toxin - abdominal pain and vomiting NST: Neurotoxic shellfish toxin - vomiting, nausea, slurred speech Potentially fatal toxins: AST: Amnesic shellfish toxin - diarrhoea, vomiting, headache, seizures, short term memory loss, coma PST: Paralytic shellfish toxin (Saxitoxin) vomiting, tingling/numbness/weakness, blurred vision, paralysis. (Safe limit as per Food Standards Code < 0.8mg/Kg PST) PST is produced during HABs in Tasmania by both Gymnodinium catenatum and Alexandrium tamarense and is the most commonly produced toxin

6 Toxicology Paralytic shellfish poisoning (PSP) Q: How much toxin do you actually need get sick? A: Not very much at all! Clinical Features Onset usually within 2 hours (15 mins to 10 hours) Tingling sensation Numbness / weakness Muscle incoordination Difficulty speaking Double vision Floating sensation Difficulty breathing - severe cases respiratory failure & death Treatment: supportive

7 HABs the Tasmanian timeline 1985 onwards Seasonal blooms of Gymnodinium catenatum in SE Warm water window, late summer - autumn - early winter Low levels of Alexandruim sp. detected, low toxicity strain = low risk Some anecdotal case reports of illness from foraging wild shellfish 2011 Documented case of PSP from eating wild mussels

8 HABs the Tasmanian timeline 2012 Oct 2012 Alexandrium tamarense bloom impacted on the entire East Coast of Tas: Cold water window, C Highly toxic strain, PST Shipment of mussels from the region tested by Japanese authorities high levels of PST (10mg/kg) Recall of mussels in Japan from affected shellfish farm and temporary ban on import all Australian shellfish to Japan Cost to industry $23 million PST also in mussels, oysters, scallops, clams and viscera of abalone and rock lobster

9 HABs the Tasmanian timeline, Low toxicity years: Low rainfall Small number of shellfish farm closures July Nov 2015 Widespread bloom: Especially cold winter temperatures Four cases of human hospitalisation Wild mussels had been collected and consumed at Little Swanport Mussels in the region up to 24mg/Kg PST and oysters 6mg/Kg (regulatory limit is 0.8mg/Kg) Many shellfish farm closures

10 HABs the Tasmanian timeline, June Sept 2016 Another widespread bloom: Preceded by major rainfall event Many shellfish farm closures April June 201, Huon Estuary: Gymnodinium catenatum July 2017 Tasman Peninsula: Alexandrium tamarense Shellfish farm closures June 2017 and still ongoing Entire East Coast: Alexandrium tamarense Highest reading recorded so far, 64mg/Kg PST near Maria Island (26/09/17) Many shellfish farm closures Food recall of exported product (Hong Kong)

11 70 PST Levels in Mussels and Oysters Great Oyster Bay - O Little Swanport -O Great Oyster Bay - M Spring Bay - M Reg Limit /01/ /05/ /08/ /11/2016 6/03/ /06/ /09/ /12/2017

12 Management Strategies Primary Industry Regulator/Industry manage the ongoing commercial risks Tasmanian Shellfish Quality Assurance program (TSQAP), shellfish farm closures, Biotoxin Management Plan Rock lobster, scallop and abalone fisheries Biotoxin Management Plans and protocols in place for commercial (and recreational) activities Primary Produce Safety (Seafood) Regulations 2014 Biotoxin Monitoring Program PST, DST, AST in mussels and oysters sentinel species High/medium risk areas weekly Low risk areas monthly Also algae analysis, monthly and weekly Food Act 2003, Food standards Code Prescribed limit 0.8mg/Kg PST Food safety Unit, DHHS - manage recalls Rapid test kit (field test) being developed by UTAS/IMAS

13 Who regulates the collection of wild shellfish? Safety of shellfish for sale existing regulatory framework Collecting wild shellfish for human consumption (foraging) is not regulated or monitored But the risks to human health are the same: Estimate over bivalves foraged each year by Tas residents Foraging by tourists - no data, but we know it happens All confirmed cases of PSP linked to foraging shellfish

14 Everything looks the same as it always has The water looks and smells normal

15 But something has changed There is a new normal HABs are now: Annual, recurrent events Expected, persistent and widespread A very real threat to public health January - June in the Huon Estuary June December on the East Coast

16 Past actions: Public Health Alerts Public Health Alerts issued Temporary signs and media releases But 2015 and 2016 were different, HABs widespread and long lasting And right now 2017 is looking similar Clearly we needed to improve our public health messaging Really??!!??

17 And more

18 PUBLIC HEALTH ACT SECT 7 7. General functions and powers of Director (1) The functions of the Director are (a) to develop and implement strategies to promote and improve public health; and (b) to ensure that the provisions of this Act are complied with; and (c) to advise the Minister on any changes to this Act that may be necessary or appropriate; and (d) to carry out any other function for the purpose of this Act the Minister determines. (2) The Director may do anything necessary or convenient to perform any functions under this Act. (3) The Minister may give the Director directions in respect of any power or function of the Director under this Act and the Director must comply with the directions.

19 Public Health Wild Shellfish Advice Program (PHWSAP) In 2016 the PHWSAP was initiated: To reduce the number of shellfish poisoning cases and other illness from collecting and eating wild shellfish By providing: timely, accurate and coordinated communication during HABs and at other times targeted messaging for both locals and tourists a seamless connection between commercial fisheries closures and DHHS Public Health Alerts a documented management plan detailing the necessary protocols/sops

20 Two public health messages Public Health Warning Danger Do Not Eat Wild Shellfish Wild shellfish can cause illness Ongoing standing warning Unsafe to eat wild shellfish from: marinas sewage and other outfalls near septics areas affected by heavy rain Linked to gastro type illness Toxic Algal Bloom Public Health Alert during a HAB Risks of shellfish poisoning Cooking and freezing won t prevent poisoning Symptoms detailed Seek urgent medical help

21 A third (food safety) message:. Seafood in restaurants and shops is safe to eat

22 Important considerations Risks and proposed actions explained Stakeholder input sought:. Ministers Offices/Premier Councils in the affected areas Relevant state government departments Seafood industry bodies Tourism industry bodies

23 Sensitivities recognised Risk of damage to the seafood and tourism industries reputation/branding from increased messaging. Vs Risk of reputational damage from severe illness or death from not taking further action

24 Actions Permanent signs location, number, size Webpage QR code linking to dedicated webpage. Brochures around 30% of the state s population don t have internet access Media articles during public health alerts and other times

25 71 Permanent signs installed Flinders Island Cockle Creek Sign displayed at all times Both signs displayed during a HAB.

26 Displayed at all times

27 Displayed during a Public Health Alert

28 Signs at popular boat ramps and jetties Municipalities: Flinders Island Dorset Break O Day GSB Sorell Tasman Clarence Kingborough Huon.

29 The brochure Ongoing risks and heightened risks during HABs And all other key messages For tourist info centres For tourism operators distributed through regional tourism bodies On DHHS website.

30 . The webpage easy to find

31 During HABs: Media articles Current details, location of affected areas Confirm key messages Broad scale. At other times (no HABs): Community newspapers/newsletters, GP newsletters Raising awareness of signs, website and ongoing risks

32 Issuing Public Health Alerts 1. Display signs: Danger Do Not Eat Wild Shellfish 2. Update the website: public health alerts pages 3. Media releases:. TV, radio, newspapers Is it really that simple?

33 DHHS Ongoing developments Identified the need for a more robust risk based approach to messaging: Step 1. Establish the level of biotoxin in shellfish that presents a low risk of shellfish poisoning (0.8mg/Kg PST) Step 2. Establish the levels that present a medium - high risk. Step 3. Match the risk level with the scale of public health messaging (media releases) CSIRO,UTAS - IMAS/IMOS Collaborative research and proposed development of a HAB forecasting system to assist industry and decision makers

34 Acknowledgements: Diane Caney, Senior Consultant Planning/Projects DHHS Stewart Quinn, Senior Food Safety Officer, DHHS Sven Rasmussen, Senior Scientific Officer, Food Safety, DHHS. Paul Hunt, State Manger Environmental Health Services, DHHS