An Evaluation of the risks to food safety and shellfish farming in Great Britain,posed by marine biotoxins from, current and future emerging, marine microalgal species

Harmful marine microalgae are a global concern, impacting human and ecosystem health as well as having socioeconomic impacts for coastal communities. The changing world climate has an impact on marine organisms including the harmful algal species. These changes will have impacts on species already present in a nations waters whilst also influencing the emergence of novel species. This is assessed here, in part, with regards to Great Britain (GB).

This thesis explores the current extent of a harmful species, Alexandrium minutum, globally and in the South of GB. This shows that A. minutum occurs widely across the globe with different populations possessing varying toxin profiles. Populations from GB geographically neighbouring areas share similar toxin profiles. Within the South of GB, the current extent of A. minutum appears patchy, with evidence gathered by toxin profile analysis but successful germinations of vegetative cells from field samples proving unsuccessful. Experimental work determined a mechanism for the use of chemotaxonomy to differentiate the source of shellfish intoxications, allowing for separation of two key GB saxitoxin producers, A. minutum and Alexandrium catenella. This technique could enhance routine monitoring data with little additional cost.

Assessment of harmful microalgal taxa considered as non-native species (NNS) to GB suggested that several species could pose a risk of future successful invasion of GB coastal waters, within the next 30 years. This was principally based on the environmental tolerances of NNS. If established the impacts which NNS could impose on GB include similar impacts to native harmful species as well as a higher risk of environmental damage. Experimental work with a high-risk potential invasive species, Ostreopsis cf. ovata, indicated that this impact could be acute, with rapid mortalities observed in exposed naïve GB mussels.

Taken together this body of work shows the validity of chemotaxonomic assessment of toxin profiles as an additional tool for the tracking of harmful microalgal species as well as proactively assessing the risk and impacts which climate change might have for the future impacts of harmful marine microalgal species around GB.