RESEARCH - Research Summary

Animal Production Theme

Research Summary

Paralytic shellfish poisoning (PSP) has plagued mankind throughout recorded history. When specific toxin producing marine algae are consumed by shellfish, they are concentrated to varying degrees throughout the body of the filter-feeding bivalve. The digestive system of bivalves is known to contain high levels as compared to the rest of the body tissues. Although PSP toxins are not normally harmful to shellfish, when consumed by humans they can cause severe neurological symptoms and are potentially deadly, depending on the amount of toxin consumed. A second but distinctly different marine algal toxin, domoic acid, is also related to the consumption of shellfish. Rarely fatal, domoic acid is however capable of severe neurological damage leading to permanent memory loss. It is for this reason that domoic acid poisoning has been called Amnesic Shellfish Poisoning (ASP).

To date, surveillance and testing are the troprimary conl strategies for marine shellfish toxins, and therefore the frequency of testing, the time to complete sample analyses and the overwhelming complexity of sampling Canada’s coastline make the job of surveillance extremely difficult. This project is based on the premise that in nature certain bacteria which colonize the digestive tract of marine bivalves have the ability to grow on and break down toxin compounds, since both PSP and ASP levels tend to rise and fall over time. This project focuses on the development of a strategy in which toxin-degrading bacteria are fed to toxic shellfish in order to accelerate the speed of detoxification.

Research to date has successfully screened toxic bivalves for bacteria that can degrade PSP and/or domoic acid in situ. Specifics regarding the toxin breakdown are under further investigation. This project could result in significant benefits to the shellfish aquaculture industry if the appropriate toxin-degrading bacterial culture can be introduced into shellfish during commercial depuration procedures. The ability to introduce the bacteria in large enough numbers and their effectiveness in completely breaking down toxins resulting in innocuous end products still needs to be determined.

Network Investigators

Tom Gill, Department of Food Science and Technology, Dalhousie University, Halifax, NS
Michael Quilliam, Institute for Marine Biosciences, National Research Council, Halifax, NS
Monica Bricelj, Institute for Marine Biosciences, National Research Council, Halifax, NS
Rafael Garduno, Department of Microbiology and Immunology, Dalhousie University, Halifax, NS