assessment of ecological condition of dutch lakes

8/6/2019 Assessment of Ecological Condition of Dutch Lakes

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8 oktober 2004

Assessment of Ecological Condition

of Dutch Lakes for the EuropeanWater Framework Directive

Hugo Coops

RIZA


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8 oktober 2004

2

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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3

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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8 oktober 2004

4

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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8 oktober 2004

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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


11/13


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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

assessment of ecological condition of dutch lakes

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