Macrophytes as biological indicators of organic pollution in the Lepenci River Basin in Kosovo

Macrophytes represent one part of the biological quality elements defined by the European Water Framework Directive (WFD) as 'macrophytes and phytobenthos'. The aim of this study was to evaluate the reliability of ecological status classification by the use of macrophytes for lowland rivers with different habitat conditions, corresponding to EWFD requirements. The classification of water quality is based on the Ecological Quality Ratios (EQRs) which is proposed for the purpose of macrophyte-based classification for the WFD. To determine the ecological quality ratio, we calculated the following indices: River Macrophyte Nutrient Index (RMNI), River Macrophyte Hydraulic Index (RMHI), Macrophyte Index for Rivers (MIR), Number of macrophyte taxa which are not helophytes (NTAXA). Water sources that supply Lepenci River are located in alpine and subalpine areas of the Sharri mountain, which are considered as ecologically clean. Our results show that the water in spring area is clean but as a result of the anthropogenic activities downstream, the river becomes polluted by different pollution substances. This fact is also confirmed by the presence or absence of macrophytes that we used in this work as a biological indicator of water pollution. River Macrophyte Hydraulic Index (RMHI), has shown the highest value at SP6-Gerlice, with a value of 8.74 that classifies this station downstream the river as the most polluted. The water flow velocity in this station is smooth and as such it is characterized with Macrophyte species associated with this type of water flow. According to the assessment of ecological status with RMNI index, the stations SP7-Kacanik and SP8-Hani i Elezit, have good water quality and high ecological status and belong to first class (I), whereas the station with poorest water quality (fourth class) and poorest ecological status is rated SP5-Nike. MIR index classify the quality of water as very good at S8-Hani i Elezit, whereas the values of this index at stations S5-Nike and S6- Gerlice indicate the bad water quality and poor ecological status. The largest number of macrophyte species that were not heliophytes was recorded in SP8-Hani i Elezit. We can conclude that the presence of macrophyte species in river varies from nutrient levels in water. Our results show that values of macrophyte based indices reflect the water quality in sampling stations therefore we can consider them as a reliable instrument for the assessment of the ecological status of the rivers.