Changing wind patterns linked to unusually high Dinophysis blooms around the Shetland Islands, Scotland

- 70 people in South East England ate contaminated shellfish from the Shetland Islands.
- Large blooms of Dinophysis occurred in Shetland at the time the shellfish were harvested.
- Dinophysis accumulation was greater than that expected from an in situ growth model.
- The accumulation of Dinophysis was associated with a change in local wind patterns.
- Analysis of wind direction may provide a method of predicting future bio-toxicity events.

During the summer of 2013, 70 people received Diarrhetic Shellfish Poisoning following consumption of mussels harvested in the Shetland Islands, Scotland. At this time, large numbers of the biotoxin-producing phytoplankton genus Dinophysis was observed around the Shetland Islands. Analysis indicated this increase was not due to in situ growth but coincided with a change in the prevalent wind direction. A previous large bloom of Dinophysis during 2006 also coincided with a similar change in the prevalent wind patterns. Wind direction and speed in the North East Atlantic and the North Sea is strongly influenced by the North Atlantic oscillation (NAO) with a positive relationship between it and wind direction. It has been noted that a positive trend in the NAO is linked to climate change and predictions suggest there will be an increasingly westward component to prevalent wind directions in the North Sea which could lead to an increase in the occurrence of these harmful algal blooms. Analysis of wind patterns therefore offers a potential method of early warning of future bio-toxicity events.