Morpho-functional groups and size classes Sample Clauses

Morpho-functional groups and size classes. To provide a better assessment of the functional impact of eutrophication, a novel phytoplankton composition metric, based on functional traits has been developed. The assemblage is classified by size classes and morpho-functional groups outlined in the scientific literature. The changes in these groups have been analysed in a set of about 200 European lakes of the same type (lowland and shallow or very shallow). The results indicate that shifts from smaller to larger taxa, as well as a change in the importance of the different morpho-functional groups takes place across the trophic gradient (Figure 3.1-2). Two indices, based on size spectra and morpho-functional groups respectively have been proposed and are being considered by the GIGs alongside the PTI as candidate composition metrics towards the development of a common phytoplankton metric for the second phase of the intercalibration process. Until now, there has been little progress in developing classification schemes for phytoplankton bloom frequency and intensity for the WFD. No consistent definition for an algal bloom even exists across Europe. WP3.1 established a number of characteristics that define a bloom: • High phytoplankton abundance relative to typical levels of abundance for that time of year (i.e. there should be a critical density above which a bloom is defined). • Uneven community – dominance by one or two species • Abundance of nuisance species e.g. potentially toxic cyanobacteria These three characteristics were incorporated into the following two metrics, which will be combined to create a candidate bloom metric for IC purposes. As no national metrics are available, it is likely that this will be adopted as a constituent of a common metric by the GIGs, and as a national metric by many Member States for the 2nd phase of Intercalibration.