Water Framework Directive Marine Plants Task Team Tools Paper ...

Establishing Boundaries
As with the use of a full species list the additional parameters were also used, for
which ecological quality status boundaries needed to be devised. Establishing the
quality boundaries for each of the parameters is quite difficult as there is very limited
data on which to base these values. The reduced species lists were applied to all the
records within the database including those sites considered to be of good, moderate
and poor quality. Quality status boundaries were then established using the same
method as with the full species list i.e. the mid point between upper and lower error
bars on adjacent quality classes.
The boundary values were based on solely on the predicted quality status values and
by matching this up with the overall scoring system, no statistical methods were used
as the results were far too variable. Unfortunately there have been no shores surveyed
within Northern Ireland that were thought to be of poor quality so the moderate/poor
boundary value for this area would need to be refined once further data has been
collected. The boundary values vary considerably between the different areas but this
is mainly as a result of the difference in reduced species lists between areas. Tables 5,
6 and 7 show the classification scoring system for each of the geographic areas.
Table 5: Boundaries values for RSL, ESG, Green, Red and opportunist proportions
for Scotland/Northern England area.
Score
EQR 0 – 0.2 0.2 – 0.4 0.4 – 0.6 0.6 – 0.8 0.8 – 1.0
Bad Poor Moderate Good High
RSL 0­5 5­17 17­25 25­35 35­70
Greens 80­100 30­80 20­30 12­20 0­12
Reds 0­15 15­35 35­45 45­55 55­100
ESG 0­0.2 0.2­0.7 0.7­0.8 0.8­1.0 1.0­1.2
Opportunist 50­100 25­50 15­25 10­15 0­10