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Predicting the distribution of maerl

Predicting the distribution of maerl. By Malcolm Thomson International Centre for Island Technology Heriot-Watt University (Orkney Campus) Old Academy Stromness Orkney Scotland. What is maerl?. coralline red seaweed secrete calcium carbonate (CaCO 3 ) coastal distribution long lived.

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Predicting the distribution of maerl

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  1. Predicting the distribution of maerl By Malcolm Thomson International Centre for Island TechnologyHeriot-Watt University (Orkney Campus)Old AcademyStromness OrkneyScotland

  2. What is maerl? • coralline red seaweed • secrete calcium carbonate (CaCO3) • 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 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

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