Report on Harmonisation of freshwater biological methods

IT 90% acetone spectrophotometricPT acetone spectrophotometric Lorenzen (1967)NORTHERNNO 100% methanol spectrophotometricIE boiling methanolUKcold acetone (100% or hot methanol spectrophotometric HMSO (1980)(90% methanol); acetone)FIN spectrophotometric ISO 10260:1992SEspectrophotometricPHYTOPLANKTON7. Most countries include in their biological monitoring systems some metric forphytoplankton, as shown in Figure 6. The lowest number of lakes for whichphytoplankton is monitored is in the NO GIG (54%), in all other GIGs at least 60% ofthe lakes are monitored for phytoplankton. A possible explanation for a smallerpercentage of lakes with phytoplankton data in the Northern GIG could be amonitoring strategy targeted to identify acidification impacts and for whichchlorophyll a is less used.Percentage determining phytoplankton by GIG1008060%40200AL AT BA CE EC ME NOFigure 6. Percentage measuring phytoplankton within the GIGs.8. Lake sampling frequency is variable but in most GIGs, and for most lakes is 2-12times per year (Fig.7), and spring and summer as the most common sampling seasons(Fig. 8).7 Spectrophotometric determination8 Talling and Driver (1963)49