NORTHERNLAkeGIG – MACROPHYTES

1. Methods and required BQE parameters

Macrophytes / Phytobenthos / Combination rules
MemberState / Full BQE method / Taxonomic composition / Abundance / Taxonomic composition / Abundance
IE / Only MP / Percent relative frequency of Chara
Percent rel. freq. of Elodeids
Plant trophic index
Percent rel. freq. of tolerant taxa / Maximum depth of colonisation (Zc)
Mean depth of presence / no / no / Avg metric scores
FI / Only MP /

Proportion of type specific taxa PTST

Percent Model Affinity PMA

Reference Index RI

/ Abundance is included in PMA. / no / no / Median metric scores
SE / Only MP / Trophic Macrophyte Index (TMI) / no / no / no
NO / Only MP / TIc (trophic index count) based on sensitive, tolerant, indiiferent taxa composition / no / no / no
UK / Only MP / LakeMacrophyte Nutrient Index (LMNI)
Number of Functional Groups
Number of Taxa / Macrophyte Cover
Relative percent cover of Filamentous Alga (?) / no / Relative percent cover of Filamentous Alga (? / Weighted avg metric scores, Worst metric score

Explanations :

1)Phytobenthos not included in the assessment methods. From IC guidance: If only one component is used of a BQE which consists of two components ("macrophytes and phytobenthos" for rivers and lakes) then it must be demonstrated that the impacts of the existing pressures are being sufficiently detected by that component.

Eutrophication pressure is very clearly described by macrophyte species as demonstrated by our intercalibration exercise. Lakes naturally without higher macrophytic vegetation are rare in Nordic areas or in the cases of high altitude mountain lakes without significant pressures. Only exception could be regulated mountain reservoirs, but in this excercise we have removed all regulated lakes and reservoirs due to different pressure. However, there are several ongoing studies which try to develop new indiced taking also littoral phytobenthos into account.

2) Why abundance not included in the FI, SE, NO methods ?

Three member states, UK, FI and IE have accounted for abundance within their tool but not necessarily as a metric per se. However, NO and SE have not used abundance. All of the member state methods tend to be, either a single metric or multiple metrics based on sensitive and / or tolerant taxa because they are best correlated (responsive) with the pressure enrichment. In that light, it is not considered necessary to account for abundance because it is not the strongest response, it is difficult to quantify, no member state uses abundance as metric per se, only 3 actually account for abundance but not directly so, and furthermore it is not measured in the same way by member states.

2. National reference conditions

MemberState / Methodology used to derive the reference conditions
IE / Reference sites selected by expert opinion and also for some lakes through palaeolimnological validation:
FI / Existing near-natural reference sites, selected mostly based on pressure criteria
SE / Existing near-natural reference sites, Historical data, Least Disturbed Conditions
NO / Existing near-natural reference sites, selected by expert judgement and water chemistry data
UK / Existing near-natural reference sites, Historical data, Modelling (extrapolating model results) Sites selected by iterative application of biological and physicochemical criteria, ca 600 surveys (mixture of historic and contemporary surveys)

Explanations needed: FR, SI ?

True reference sites were selected according to specific criteria. The criteria used consisted of pressure data, impact data, knowledge of biology and chemistry, land-use data in conjunction with expert judgement, and in some cases confirmation by paleodata.

The general approach used by the GIG was to establish a common method for the estimation of the reference values for the macrophyte status common metric (ICCM). Rather than develop a type specific reference value for the ICCM the GIG agreed to develop a lake specific reference value using a multiple regression model. Thus when the EQR for the common metric was determined for all lakes in the common data set each country used the same model and thus identical reference conditions, thus ensuring the harmonisation of reference conditions for the common metric.

Due to the high number of lakes in the NGIG area, it was not possible to quantify the pressure criteria for every single lake. It is important to note that because the GIG applied the boundary setting protocol to a common data set, substantial differences between MS identification of reference sites would become obvious during the boundary setting procedure as the common metric was applied to the whole database.

In addition to this the values for supporting elements indicative of pressure such as Total Phosphorus and other indicators of impact such as water transparency and phytoplankton biomass for reference sites were examined

3. National boundary setting

MemberState / Methodology used to set class boundaries
IE / Boundary setting based on points of ecological change along a pressure gradient. For example where the depth of colonisation of the Charophytes is reduced by 24% from reference condition or where diversity declines with eutrophication pressure
FI / High – Good boundary lower quartile of reference lake metrix value. Other classes based equidistant division of the EQR gradient. Good-Moderate status is representing a significant change of type specific reference species
SE / Using discontinuities in the relationship of anthropogenic pressure and the biological response (the species used for classification were those showing sudden drops in their occurrence)
NO / Boundaries are based on changes in vegetation abundance and species composition: Good/moderate: where stands of the large isoetids (in low alkalinity lakes) or Chara spp. (in high alkalinity lakes) decrease ("sudden drop")
UK / Using paired metrics (sensitive and tolerant taxa) that respond in different ways to the influence of the pressure. EQR boundaries are subsequently adjusted to equidistant divisions

Explanations needed: FR, SI, IT ?

4. Pressures-response relationships

Pressures addressed by the MS assessment methods

MemberState / Metrics tested / Pressure / Pressure indicators / Strenght of relationship
IE / EQR / EU / TP / R2 =0.59, p< 0.001
IE /

All metrics

/ EU / TP / Correlations R = 0.36-0.69
FI /

EQR

/ EU, HM / TP, winter drawdown / EQR - TP r2=0.52, EQR -winter drawdown r2=0.58, n=248
SE / Trophic Macrophyte Index (TMI) / EU / TP / Correlation R > 0.6, sign, > 300 lakes
NO / Tic / EU / TP / r2=0.68, n=281
UK / LMNI / EU / TP / R2 TP annual = 0.49, R2 summer TP = 0.45
UK / Other metrics / EU / TP / tested, not significant, still supporting the use of these metrics in the ecological assessment

Explanations needed: missing information

Why we need to explain strengths of our national methods? Numbers above are based on Wiser questionnaire, but surely our national methods are nationally valid and we are using common ICCM to do intercalibration?