B04005: Correlation between algal presence in water and toxin presence in shellfish
Monday 30 April 2029
This study aims to examine the correlation between environmental phytoplankton and toxin levels in shellfish.
Background
Phytoplankton are single celled microscopic algae. Shellfish that feed on some of these algae, which produce toxins, can be rendered toxic and pose a health risk to people that eat them. This project aims to examine the relationship between phytoplankton cell numbers in the environment and toxin levels in shellfish by establishing a high frequency sampling programme for both shellfish flesh and toxic phytoplankton.
Research Approach
The project will survey three UK sites for both phytoplankton and shellfish toxicity. Phytoplankton samples will be taken for genetic analysis to determine if any differences exist between the molecular makeup of these toxin-producing cells from the three UK regions.
Results and findings
Phytoplankton are single celled microscopic algae, some of which can produce toxins. Shellfish that feed on such toxic algae can be rendered toxic to humans, when consumed. This project undertook a high frequency sampling programme of toxins in shellfish flesh (mostly mussels) and of toxic phytoplankton species within the water column, in order to examine the statistical relationship between the two. The data was collected from two Scottish sites (Scapa Bay & Isle of Ewe) and the Fal Estuary in Cornwall.
The data collected from this project�s three sampling sites was statistically analysed using standard time series techniques.
Pseudonitzschia spp. and amnesic shellfish poisoning (ASP) toxin (domoic acid)
For samples from the Isle of Ewe site, significant correlations of moderate strength (0.50<cc<0.80) were found for Pseudonitzschia cell numbers and domoic acid levels in mussels. For samples from Scapa Bay, only weak correlations of marginal significance were observed. Only limited data was available from the Fal Estuary.
Dinophysis. spp (and Prorocentrum lima) and diarrhetic shellfish poisoning (DSPDSP toxins
For the Isle of Ewe and Scapa Bay sites significant correlations of mostly moderate strength were found between the cell number of Dinophysis spp, (and P. lima) and the two DSP toxins okadaic acid and DTX-2.
Alexandrium spp. and paralytic shellfish poisoning (PSP) toxins
At Scapa Bay and the Fal Estuary the presence of PSP toxins (>40
g STX equivalents/100g) in mussels was determined with the semi-quantitative Jellett Rapid Test and was found to largely coincide with periods of increased Alexandrium spp. cell numbers. Genetic analysis showed that the Alexandrium species present in Scottish samples (A. tamarense) were different to the species found in Fal Estuary samples (A. minutum and A. ostenfeldii).
The study concluded that sampling frequency was of crucial importance if intending to use phytoplankton cell numbers as a viable marker for shellfish toxicity. However, phytoplankton cell numbers may not always be a good proxy for phytoplankton toxicity and it may instead be better to measure phytoplankton toxicity directly. The results and conclusions of this study will help to inform the future direction of the UK�s phytoplankton monitoring programme.
Dissemination information
The final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk, Dr Elsie Widdowson Library and Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email: library&info@foodstandards.gsi.gov.uk
Contact: For any enquiries concerning this research project, please contact the relevant Programme contact or email science@foodstandards.gsi.gov.uk