1. Predicting the distribution of maerlBy
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 (CaCO3)
coastal distribution
long lived

3. Importance of maerl commercial scientific sensitivity / fragility
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
Exposure
Tidal category

13. 5 km 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

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