ABSTRACT
The EU Water Framework Directive (2000/60/EC) defines a framework for assessing all kinds of water bodies in Europe and member countries must assess and classify surface waters into 5 different water quality classes based on ecological quality. Fifteen small and mid sized calcareous lowland streams were selected according to System A classification scheme of the Directive. Benthic macroinvertebrate fauna was used for the assessment of the ecological quality of the streams combined with hydromorphological and physicochemical analyses. The vast majority of the sites were classified as moderate quality waters mainly due to agricultural and urban impacts. The aim of this study was to examine macroinvertebrate community structure and diversity in Greek lowland streams and identify the environmental factors that determine their distribution and abundances. The findings suggested that microhabitat composition (sand/mud and terrestrial plant roots) and water chemistry (nitrite, chloride, and phosphate) were the main factors.
