Risk Profile For Paralytic Shellfish Toxins In Tasmanian Periwinkles
Funder
Fisheries Research and Development Corporation
Funding Amount
$180,504.00
Summary
Recurrent harmful algal blooms in Tasmanian waters (Gymnodinium in the South and Alexandrium on the East Coast) have impacted Oyster, Mussel, Abalone and Rock Lobster industries, necessitating the implementation of biotoxin monitoring programs and harvest closures during high risk periods. It is currently unknown whether Periwinkles can accumulate paralytic shellfish toxins (PST) from Tasmanian microalgal blooms and a conservative risk management approach has been taken thus far to protect both ....Recurrent harmful algal blooms in Tasmanian waters (Gymnodinium in the South and Alexandrium on the East Coast) have impacted Oyster, Mussel, Abalone and Rock Lobster industries, necessitating the implementation of biotoxin monitoring programs and harvest closures during high risk periods. It is currently unknown whether Periwinkles can accumulate paralytic shellfish toxins (PST) from Tasmanian microalgal blooms and a conservative risk management approach has been taken thus far to protect both public health and market access.
Unlike bivalve shellfish, Abalone and Rock Lobster, there is currently no clearly defined biotoxin management plan for Periwinkles in Tasmania. As grazers, Periwinkles are loosely grouped with Urchins and Abalone, the latter of which are a proven PST risk. This Abalone biotoxin sampling plan is triggered when Tasmanian Shellfish Market Access Program (ShellMAP) closes bivalve harvest areas due to PST risk. In a conservative approach, the current recommendation is PST analysis of 20 pooled Periwinkles per Abalone block on at least a monthly basis to maintain market access. This presents a considerable cost burden to the small dive fishery and interrupts harvest operations, as PST sampling of Periwinkles is required if elevated PST are detected in Abalone, which are known to hold onto PST for longer time periods in between blooms (years).
To date, the vast majority of Periwinkle samples that have been analysed for PST were collected from weak or no bloom years or regions. Evidence from French tank trials exposing the common European Periwinkle (Littorina littorea) to Alexandrium minutum cysts containing PST showed significant toxin uptake (0.2 mg PST/kg) within six days of exposure (Neves et al, 2015). It remains unknown whether commercially harvested Tasmanian Periwinkles (Lunella undulata) are at risk of PST accumulation and if the current conservative monitoring approach is commensurate to risk. In such scenarios, risk managers will commonly outsource a preliminary risk assessment (known as a risk profile). Risk profiles are an important tool for risk managers and industry. They provide a summary of all information pertinent to food safety associated with the specific hazard/food combination. The purpose of a risk profile is to assist initial risk management activities, such as identifying future actions required (if any), and the options for food safety management programs. They also inform the level of resourcing required to control the hazard/food pairing.
This project will deliver an urgently required risk profile for PST in Periwinkles to inform future actions (if any) and provide options for cost-effective food safety management programs. This profile will: 1. Determine the risk of PST accumulation in Periwinkles in Tasmania as a result of harmful microalgal blooms during high risk exposures at peak algal bloom densities in the field and in tank trials. 2. Outline potential management options and knowledge gaps, should risk management be necessary. This includes an assessment of whether the bivalve PST regulatory limit is appropriate to use in Periwinkle risk management (currently based on shellfish serving size of 100-400g) and the spatial variability associated with sampling.
References Neves, Raquel AF, et al. "Responses of the common periwinkle Littorina littorea to exposure to the toxic dinoflagellate Alexandrium minutum." Journal of Molluscan Studies 81.2 (2015): 308-311.
Objectives: 1. Determine whether Tasmanian Periwinkles can bioaccumulate PST from Alexandrium and/or Gymnodinium microalgal blooms during both field and laboratory exposures. 2. Identify the most suitable size of biotoxin management zones for Periwinkles. 3. Assess whether the use of the bivalve PST regulatory limit is appropriate for Periwinkles by conducting a literature search and consumption survey. 4. Generate a risk profile for PST in Tasmanian wild caught Periwinkles and provide guidance for risk management. Read moreRead less
Detecting Paralytic Shellfish Toxins In Oysters - Initial Assessment Of AquaBC Rapid Test Kit
Funder
Fisheries Research and Development Corporation
Funding Amount
$29,845.00
Summary
Reliable detection of marine biotoxins is a critical requirement for any effective biotoxin monitoring program, requiring any analytical technique to be properly validated. The Neogen rapid test kit for the detection of paralytic shellfish toxin (PSTs) was successfully validated in both single lab and inter-lab validations for use in oysters, offering rapid (within 20 min) on farm results. The test was used in Tasmania to reduce business risk, (i.e. frequent testing of shellfish that can rapidly ....Reliable detection of marine biotoxins is a critical requirement for any effective biotoxin monitoring program, requiring any analytical technique to be properly validated. The Neogen rapid test kit for the detection of paralytic shellfish toxin (PSTs) was successfully validated in both single lab and inter-lab validations for use in oysters, offering rapid (within 20 min) on farm results. The test was used in Tasmania to reduce business risk, (i.e. frequent testing of shellfish that can rapidly accumulate PST within a week) and employed in South Australia for regulatory purposes (low frequency of PST detection in this region).
A key factor influencing the suitability of antibody based rapid test kits is the PST profile present in the sample to be analysed. The term PST profile describes the relative concentrations of different PST analogues that might be present in each seafood sample. These profiles differ between toxic algal species, different seafood species and their tissues. Not all PST analogues are equally detected by the antibodies of different test kits (quantified as the % cross-reactivity). These cross-reactivities are critical for ensuring reliable detection across different combinations of PST analogues that might be present in shellfish.
To determine if the AquaBC rapid test kit is suitable replacement for routine monitoring, a full validation for each seafood tissue matrix would normally be conducted to determine the probability of detection curve (probability of detection across a range of PST concentrations) for multiple PST profiles, ideally followed by an inter-laboratory validation (as was conducted for the Neogen test). However, a full validation study requires repeat testing of hundreds of samples and is therefore expensive. From our previous work with the Neogen test kit, we have identified some key performance indicators that would allow for a quick initial assessment of the new AquaBC test kit, using much reduced sample numbers. These small pilot trials would include testing the most commonly encountered PST profiles (i.e. which PST toxin analogues are present) and their relative concentrations (i.e. can we reliably detect the presence of PST at the regulatory level without obtaining too many positive results at PST levels below concern?). Rather than conducting a full validation, this project will provide an initial assessment of these parameters in regard to the PST profiles commonly encountered in TAS, SA and NSW. Should this assessment be positive, a full follow up validation may be recommended. Objectives: 1. Review & identify different PST profiles that may be encountered in TAS, SA and NSW oysters. 2. Challenge the AquaBC test kit against a range of different PST concentrations and profiles to provide an initial assessment of its suitability for detecting PST in Australian oyster tissues. Read moreRead less
The Detection Of Ciguatera Toxins In NSW Spanish Mackerel
Funder
Fisheries Research and Development Corporation
Funding Amount
$490,000.00
Summary
Ciguatera Fish Poisoning (CFP) causes the largest number of seafood-related food safety incidents in Australia. In NSW and southern QLD waters, CFP is mostly related to Spanish Mackerel (Scomberomorus commerson). Ciguatoxins (CTXs) produced by marine microalgae (Gambierdiscus spp), are polyether toxins that accumulate in fish and cause CFP when fish are eaten. CTXs are heat stable, odourless, tasteless, and toxic at low concentrations, therefore it is very difficult to distinguish toxic fish. In ....Ciguatera Fish Poisoning (CFP) causes the largest number of seafood-related food safety incidents in Australia. In NSW and southern QLD waters, CFP is mostly related to Spanish Mackerel (Scomberomorus commerson). Ciguatoxins (CTXs) produced by marine microalgae (Gambierdiscus spp), are polyether toxins that accumulate in fish and cause CFP when fish are eaten. CTXs are heat stable, odourless, tasteless, and toxic at low concentrations, therefore it is very difficult to distinguish toxic fish. In NSW, since 2014, 31 people have contracted CFP after consuming Spanish Mackerel caught locally, mostly through recreational fishing.
Validated commercial monitoring methods for CTXs are unavailable internationally, although research tools for CTX measurement have been developed. Regulatory methods for CFP prevention are to avoid certain fish species, fish of certain sizes (ie >10kg), or fish from certain regions. In Australia, effective prevention methods have not been clearly evaluated. This results in Spanish Mackerel that are safe to eat potentially being excluded from sale, resulting in significant losses (ie > ~$200k p.a in NSW). This project addresses this issue, which was identified as high priority in the Australian ciguatera research strategy formulated at a recent workshop (27-28th March, 2019).
In 2014, FRDC (Tactical Response) and the NSW Recreational Fisheries Trust funded an initial study on the incidence of CTXs in NSW Spanish Mackerel. CTX was present in flesh and liver samples (1-7% incidence), and was not clearly correlated with the weight of individual fish. This information showed that CFP risk management may require reassessment. This project will advance knowledge by: evaluating methods of detection of CTXs; determining detailed predictive data on CTX incidence; and evaluating environmental and biological factors associated with CTX in Spanish Mackerel to allow for an evaluation of risk assessment strategies. This information will benefit industry by enhancing consumer safety and industry confidence, and enabling the sale of safe Spanish Mackerel.
Objectives: 1. Determine industry CTX needs and conduct of review of available CTX measurement tools (including cell based assays, ELISA kits, and LCMS) against these needs. Conduct an assessment of the currently available screening tools to determine which, if any, hold promise for industry use. Conduct a viability assessment for how a tool might be used in industry or, if none of the currently available tools are appropriate, make recommendations for future activities to develop a rapid screening tool that meets industry needs. 2. Obtain samples of flesh and liver from ~300 individual Spanish Mackerel of all sizes caught in Industry relevant regions of NSW waters over a period of 2 years, as well as length, weight, sex and site information, with the participation of the Sydney Fish Market and commercial fishing Cooperatives. Obtain samples from any individual Spanish Mackerel associated with illnesses in NSW or QLD. Measure CTX1B and other available CTX analogs using best practice methods identified in Objective 1. 3. Conduct statistical data analyses of all available data on CTX concentrations in Spanish Mackerel in comparison to biological and environmental variables.Develop recommended options for food safety risk management for Spanish Mackerel in NSW that will allow for a viable industry while protecting public health. Read moreRead less