Searching for common macroinvertebrate metrics for assessment of ecological status of Western Balkan lakes

Abstract

We investigated benthic macroinvertebrates from the littoral zone of six Balkan lakes: Lake Ohrid, Lake Prespa, Lake Lura, Lake Sava, Lake Biogradsko, and Lake Crno, located in North Macedonia, Albania, Serbia and Montenegro, to search for common evaluation metrics to be applied for ecological status assessment. Samples were taken by Kick and Sweep sampling and using a van Veen grab. We sampled in different depths, from six localities in each of the six lakes, and recorded data on water chemistry, habitat heterogeneity and lake typology. A multivariate analysis was carried out to identify the main trends in the macroinvertebrate data, to select reference versus impaired sites, to detect multicollinearity between metrics, and to identify metrics that were independent of lake typology. Several metrics were tested representing structural and functional properties of macroinvertebrates. Our data so far indicate that the best suitable metrics for ecological status assessment of these lakes (which may also be used at regional level) could be some functional metrics as well as indices sensitive to organic pollution, mainly ASPT (Average Score Per Taxon) and BMWP (Biological Monitoring Working Party Score). Our results indicate that these metrics should be ecologically sound for monitoring of lakes and that they provide information relevant for the assessment of ecological status according to the Water Framework Directive, independent of the actual uses of those water bodies.