Assessing the environmental status and identifying the dominant pressures of a trans-boundary river catchment, to facilitate efficient management and mitigation practices

Implementing efficient water resources management plans at trans-boundary river catchments is a difficult task that requires strong international cooperation, intensive monitoring programs, and common understanding of the impacts imposed on water resources by human pressures. Evros River, which flows through Bulgaria, Greece, and Turkey, is an ecologically important water body, protected by international legislation but nevertheless it is susceptible to numerous significant pollution sources that may lead to the deterioration of its environmental status. In this study, a water monitoring program was applied, incorporating chemical and biological parameters to assess the environmental status in the Greek part of the river and identify the associated pollution pressures. For this purpose, seasonal water sampling occurred in 13 sites along the longitudinal course of the river and a series of parameters were recorded including nutrients, heavy metals, microbiological loads, macroinvertebrate, and fish assemblages and abundance. The results indicated that the water quality of Evros River illustrate substantial spatiotemporal fluctuations, which can be well related to specific human activities and associated pressures. Therefore, a trans-boundary monitoring program should be initiated that will provide continuous information for the development and revision of the catchment's adaptive management plan in order to restrict pollution impacts and achieve a good ecological status as required by the Water Framework Directive 2000/60EC.