1. Typology for fully saline waters

2. Transitional waters
Transitional waters are bodies of surface water in the vicinity of river mouths which are partly saline in character as a result of their proximity to coastal waters but which are substantially influenced by freshwater flows.

3. Transitional versus coastal
Same salinity descriptors
<0.5 freshwater
0.5 - <5 oligohaline
5-18 mesohaline
18-30 polyhaline
30-40 euhaline
Transitional - tidal range (micro, meso, macro)
Coastal - depth (shallow, intermediate, deep)

4. Transitional and Coastal Waters
Types - not categories that are important
Are categories a red herring?
Significance of transitional waters
using fish as a biological quality element

5. Transitional Waters - for discussion
Could be defined using
politics (existing legislation)
chemistry (salinity)
biology
geomorphology
modelling
For WFD, ecologically sound approach should be used

6. Possible approach….. UK&ROI
1st proviso - our transitional waters are estuaries
UWWTD Definition
An estuary is the transitional area at the mouth of a river between fresh waters and coastal waters
Defined using biologically relevant chemical (salinity) parameters
salinity 30
Or, where biologically appropriate, geomorphology

7. Salinity criteria Stenohaline - >30 salinity
Brackish / estuarine spp salinity
18-30 salinity - excludes both groups
Draw lines of where the salinity 30 isohaline meets the shoreline and the seabed at high and low water.
Problems
benthic / pelagic
stratification

8. Dry year Wet year Extent of freshwater influence

9. Geomorphological
Use geomorphological features where ecologically appropriate
Or a combination of salinity and geomorphology

11. Modelling based approach…..

12. Or if all else fails, use real salinity data!
Catchment Area = A m2 e.g. A~10 km2
Rainfall F metre/year = F/700 m/tide e.g. F~1 m/y
Ignore smaller catchment areas than 10 km2 B
Affected area B m2 B~???
Tidal range R m e.g. R~2m
salinity depression ~ 35 A.F/B.R
If we take “substantial” as: e.g. 1 to 5
Answer: B ~ 0.1 to 1 km2
Or if all else fails, use real salinity data!

13. Question
Is guidance required on defining transitional from coastal water?
Is this a national issue?

14. Summary

15. Summary

16. Summary

17. Summary

18. Objectives
To establish a common framework for typology of transitional and coastal waters across the North East Atlantic Ecoregion Complex (Annex XI)
Atlantic Ocean
Norwegian Sea
Barents Sea
North Sea

19. Observations Think European MSs only consider factors relevant to them
e.g. Germany only consider 1 ‘exposure’, 1 depth etc because that is all they have
for each Member State
Are these the same? No
Think European

20. Europe wide typology framework
Need to decide on key factors
Think European
Need to use the factors in the same way
Can we do this?