Report on Harmonisation of freshwater biological methods

NO qualitativ method species number, ALS relative abundance, areacoverageNOSEplants recorded using aqua scope andcollected by dredging from boat,whole-lake investigation with respectto species richness, quantitativeestimate of the percentage coveragefor randomly selected squares alongone transect.species richness, indicatorscoresIE inshore transects using rake frequency of occurrence,indicator taxa, group ratiosrelative abundanceabundance of the species isscored by ascale(1=rare,2=scattered,3=common, 4=locallydominant and 5=dominant)area coverage - expertopinionpercentage coverrelative abundanceBENTHIC INVERTEBRATES21. The percentage of lakes for which benthic invertebrates are sampled within theGIGs is for part most below 40%, with exception of AT and CE (Fig. 21).Benthic invertebratesper GIG%9080706050403020100Al AT BA CE EC ME NOFigure 21. Percentage of lakes sampled for benthic invertebrates in the GIGs.22. Sampling frequency is variable between GIGs, the most common frequencies are1 or 2-6 times per year, but EC countries sample a few lakes 7-12 times per year, andthe BA, AT and AL include a combination of different sampling frequencies (Fig.22). Sampling occurs mostly in spring and summer but in the AL and NO GIGs it isperformed most often in the Autumn (Fig. 23).61