Report on Harmonisation of freshwater biological methods

Sampling frequencyNOMEECCEBAATAL12-67-12+120 20 40 60 80 100Figure 22. Benthic invertebrates sampling frequency in the GIGs.Sampling period%120100806040200AL AT BA CE EC ME NOWhole yearVegetation periodIce free periodWinterSpringSummerAutumnFigure 23 Benthic invertebrates sampling period in the GIGs.23. In Table 5 the sampling methods and metrics for benthic invertebrates arepresented. It shows that a wide number of sampling approaches and metrics are used.The collection of samples is performed by several different devices: grab, Eckmanskip, sticking cylinder, triangle bottom scraper and hand net. The mesh size varieswidely from 100µm to 670µm. When kick sampling is used time (1-3 minutes), meshsize (100-670µm) and habitat sampled (littoral in general or stones) are different.Some countries sampled in lake littoral, other the profundal and some in both lakezones (IE). Two countries make use of international sampling standard methods,Estonia and Romania. These standards are currently under revision.24. Every country uses a different combination of metrics, the following metrics areeither used alone or in combination: abundance and relative abundance, diversity62