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Assessment of Ecological Condition
of Dutch Lakes for the EuropeanWater Framework Directive
Hugo Coops
RIZA
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Heavily modified and ArtificialWater Bodies
(42) Natural WaterTypes
Reference
(ZGET, undisturbed state)
Good Ecological Status
Target(after derogation)
Maximum Ecological
Potential
1
Good Ecological
Potential
Target
(after derogation)
2
3
a
b
From reference condition to targets
in 3 steps
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References for ecological status of
natural water bodies
Type-specific (42 rivers, lakes, transitional- and coastal
waters)
Biological elements
4 quality elements (algae, macrophytes, macrofauna andfishes)
40 experts from 15 institutes (2003/ 2004)
Linked to present policy (Nature target types)
Role of product teams/ water managers
Preliminary assessment scales
Physical-chemical and hydromorphological elements Various quality elements
Derived from biology
Experts and watermanagers
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Deriving targets for chl-a and macrophytes
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Assessment of phytoplankton (3 indicators)
Type Chlf-a Chlf-a Chlf-a Chlf-a
Class Class Class limit Class limitmiddle upper l.
VG VG G-VG M-G
(g l-1) (g l-1) (g l-1) (g l-1)
M5,11,14,22,23 6,1 2,2 15,7 27,0
1. Chlorophyll-a
2. Desmidiaceae (positive indicator):Indicative value of species presence
3. Negative indicating taxaAlgal bloom-forming taxa
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Assessment of water flora (3 indicators)
1. Abundance of macrophyte growth forms
a. Submerged vegetation cover
b. Nymphaeid vegetation cover
c. Emergent vegetaton cover
d. Filamentous algae covere. Lemnid vegetation cover
f. Littoral vegetation cover
2. Composition of macrophytes: characteristic species
a. hydrophytes, incl. charophytes and aq. bryophytesb. helophytes, incl semi-aquatic bryophytes
3. Composition of phytobenthos (benthic diatoms)
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Phytobenthos
Group Class Proportion abund.(%) EQR
Pos. Ind. VG 70 > 0.8
G-VG 50 0.8
M-G 30 0.6
P-M 10 0.4
B-P 5 0.2
Neg. Ind. VG 5 > 0.8
G-VG 10 0.8
M-G 30 0.6
P-M 50 0.4
B-P 70 0.2
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Assessment of macrofauna (4 indicators)
Dominant taxa (> 90 indiv. In standard sampling)
1. Negative dominant taxa DN2. Positive dominant taxa DP
3. Characteristic taxa KM (specific for naturalconditions)
4. Rare taxa ZS (based on Nijboer & Verdonschot,2001)
Parameter Value Score
DN >50 % 0
25-50 % 0,1< 25 % 0,2KM + DP 5-50 % 0,1
> 50 % 0,3KM 5-20 taxa 0,1
21-33 0,3> 33 0,5
Total score:
0,3-0,4 Poor0,5-0,6 Moderate
0,7-0,8 Good
0,9-1,0 High
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Assessment of fish (6 indicators)
1. Species composition (species number)
Abundance: composition of the fish community
2. Relative biomass of bream
3. Perch + roach as percentage of all eurytopic fish
4. Limnophilous fish
5. Black fish (species tolerant for low oxygen, Ph
and temperature)
6. Age structure: proportion of large fish (eel andpikeperch, only in deep lakes)
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Preliminary assessment
Beoordeling kwaliteitselementen 1996-2002
0%10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fytoplankton Fytobenthos Macrofauna Vis
zeer goed
goed
matig
ontoereikend
slecht
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Consequences and follow-up
Reference, GES and GEP are qualitatively defined in
WFD and Guidances Quality elements and parameters: idem
Intercalibration
Very limited technical and legal degree of freedom
irreversible physical pressures & potential measures;use of derogations
Maximum use of degree of freedom
Intensive interaction between decision-makers andwater managers necessary to define ecological targets
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Follow-up
References and
assessment ofstatus of
natural waters
Legal
consequences
Communication
Monitoring
MEP en GEP (targetsfor NL water bodies,
from 2005 on)
Reporting ECMarch 2005Intercalibration