1. Predicting the distribution of maerl By Malcolm Thomson International Centre for Island Technology Heriot-Watt University (Orkney Campus) Old Academy Stromness Orkney Scotland

2. What is maerl? coralline red seaweed secrete calcium carbonate (CaCO 3 ) coastal distribution long lived

3. Importance of maerl commercial scientific –biodiversity sensitivity / fragility –natural & man-made threats

4. Maerl habitats living & dead maerl beds small scale “patchiness” Video: Wyre Sound, Orkney Aug 2000

5. Large scale distribution water depth (light penetration) water movement –tides & waves temperature water chemistry seabed type

6. Project SUMARE develop models using a priori knowledge to delimit the regions where we would expect maerl to occur (wp1)

7. ICIT model water depth tidal velocity wave exposure

8. Existing datasets Admiralty data MNCR/JNCC SUMARE fieldwork ICIT student research

9. Combined dataset...

10. Set of possible conditions 11 depth bands 4 tidal categories 3 exposure categories 132 possible scenarios ~1750 samples »assign a frequency to each derived from the number of occurrences of maerl under each different scenario

11. Frequency data e.g. for the 11-15m depth band:

12. 11-15 m depth band Frequency Tidal category Exposure

13. Red: 0-15m, tide = 3. exposure = 1, 0.174 Gold: 0-15m, tide = 3, exposure = 2, 0.073 Blue:0-15m, tide = 3, exposure = 3, 0.071 Green: 16-20m, tide = 3, exposure 1-2 = 0.070 5 km

14. Frequency of maerl

15. Predictions... an idea under what conditions maerl is more likely to occur a good idea of the conditions where maerl is not going to occur Navigation of AUV