Benthic macroinvertebrates are considered to be good indicators of the trophic status
of lakes but in the Mediterranean area gaps in knowledge on taxonomical and
autoecological traits of species hinder their potential as indicators. Seventy-eight
Italian lakes were sampled, belonging to 10 types according to morphometrical,
geographical and geological parameters. An unsupervised neural network (SOM analysis)
was carried out using 65 Chironomid and Oligochaete species collected in 1865
samples. he accordance between lake types and species assemblages was tested.
Indicator weight of species was calculated considering their optima for trophic
variables (dissolved oxygen, TP, transparency). A Benthic Quality Index (BQI) and a
weighted diversity index were then calculated to test their potential as indicators of
trophic status of lakes. Alpine, volcanic and large profundal lakes were separated into
diferent clusters, characterized by diferent communities, chemical and morphometrical
parameters. On the contrary, other lake types with similar trophic status were
grouped together, showing similar taxa assemblages. BQI values were in agreement
with the trophic condition of lakes, while the weighted diversity index showed low
values for alpine lakes due to low species numbers
