Tetrodotoxin in Kaimoana: Science and Mātauranga Mitigating Health Risks from a Lethal Neurotoxin

The Hauraki Māori Trust Board and the Cawthron Institute collaborated in this research project which stemmed from a spate of dog deaths on the beaches of Tikapa Moana (the Hauraki Gulf) in August 2009.  The dogs died from the poison tetrodotoxin (TTX) and this poison was present in sea slugs that had washed up on beaches. It became apparent research was needed to determine the poisoning risk associated with kaimoana from Tikapa Moana.

The first step in this process was the Trust Board investigating historical reports, recordings of kaumātua mātauranga (elder knowledge) and kōrero, and current knowledge around toxic events in Tikapa Moana.  The conclusion was the poisoning events in August 2009 appear to be a new phenomenon – there was no historic record of this happening previously. The research team took monthly samples of kaimoana species to monitor TTX risk, which were tested for TTX presence in the Cawthron laboratories in Nelson. A total of 383 samples including 53 species, were taken and analysed. TTX was shown to be present in five of these species. Two of the species were the sea slug (already known to be toxic), and a starfish. The remaining four species were all kaimoana, including; pipi, one individual tio repe or Pacific oyster, one tio or rock oyster, and one pūpū or cat’s eye. The finding of TTX in these samples is significant, as this toxin has rarely been found in shellfish. Pipi was the only kaimoana species where TTX was present in more than one individual and over multiple months.

This information was reported back to the Marae Forum members, with a caution against the risks of eating large quantities of pipi from Whangapoua. The members were in general agreement that it was unlikely this quantity of pipi would be consumed at any one time. Additional information was also given about how to identify the toxic sea slugs, and about avoiding direct contact with them. The results of this research were also reported to the Waikato District Health Board, Auckland Council, and a steering committee of representatives from 19 agencies involved in the response to toxic sea slugs in the Auckland region.

Outputs
Journal articles
Wood SA., Taylor DI., McNabb P., Walker J., Adamson J., Cary SC. 2012. Tetrodotoxin concentrations in Pleurobranchaea maculata: Temporal, spatial, individual and generational variability from New Zealand populations. Marine Drugs 10(1): 163–176.

Wood S.A., Casas M., Taylor D.I., McNabb P., Salvitti L., Ogilvie S., Cary S.C. (2012) Depuration of tetrodotoxin and changes in bacterial communities in Pleurobranchea maculata adults and egg masses maintained in captivity. Journal of Chemical Ecology, Nov; 38(11):1342-50.

Conference papers

• Ogilvie SC., Ngamane L., Taylor D., McNabb P. 2011. Tetrodotoxin and Kaimoana: Mātauranga and science to mitigate health risks of a naturally-occurring neurotoxin. National Water Symposium, 15-16 November 2011, Christchurch, NZ.
• Paul McNabb, Andy Selwood, Shaun Ogilvie, Dave Taylor, Susie Wood, Rex Munday (2012). The discovery of tetrodotoxin in the common grey side-gilled sea slug Pleurobranchaea maculata. AOAC (Association of Analytical Communities) Pacific Northwest Section. Annual Meeting, Seattle, June 20-21, 2012.
• Taylor DI, Ogilvie SC, McNabb P, Wood SA, Anderson A, Wilkinson L, Hamon D (2012). Zombies, alien invasions and toxic sea-slugs: ecological processes and consequences of population explosions in the common grey side-gilled sea slug, Pleurobranchaea maculata. Western Society of Naturalists, Annual Meeting, Seaside California, November 8-14, 2012.

Presentations

• McNabb P. 2010. Tetrodotoxin in NZ waters. International Tetrodotoxin Science Workshop, 20 August 2011, Nelson, NZ.
• Taylor D. 2010. The Toxic (Sc-)Avenger: Ecology of the toxic sea slug, Pleurobranchaea maculata. International Tetrodotoxin Science Workshop, 20 August 2011, Nelson, NZ.
• Ogilvie SC, Taylor DI, McNabb P, Anderson A, Hamon D, Wilkinson L. 2012. Marine Toxins and Kaimoana: Minimising health risks from a naturally-occurring toxin. Presentation at Manaia Marae hui - 14 January 2012.