Contribution to the ecological quality of Aliakmon river (Macedonia, Greece): a multivariate approach

In the present study, an attempt was made to estimate the water quality of Aliakmon river using five biotic scores (based on benthic macroinvertebrate s), physicochemical variables and multivariate data analyzes. Benthic and c hemical samples were obtained from 20 sites, during the low flow season (Se ptember, 1995). Benthic macroinvertebrates were collected with the three mi nute kick-sweep method and several physicochemical parameters (D.O., pH, te mperature, nutrients etc.) were measured. The multivariate techniques FUZZY and CANOCO were applied to the data. Aliakmon river appeared to have poore r water quality during the low flow season than during the high flow season as determined by comparison with a previous survey undertaken in April 199 5. The upstream sites had better water quality than the downstream sites. T he performance of the biotic scores was generally satisfactory, but in some cases they were deficient in distinguishing between running waters of good and excellent water quality. On the contrary, the multifactorial analyzes, which consider the abundance of the taxonomic groups, appeared to be more appropriate for the classification of the sites based on the structure of t heir biocommunities.