Biotic assessment of an aquatic ecosystem affected by mining activities

In the region of the Apuseni Mountains, part of the Western Carpathians in Romania, metal mining activities have a long-standing tradition. Their activities caused impairments to the environment, such as acid mine drainage (AMD) resulting in long-lasting heavy metal pollution of waters and sediments. The paper presents the biological analysis of an aquatic ecosystem in 9 control sections in order to assess the affected area by mining activities. The sampling for biological analysis was performed during two sampling campaigns: winter - February 2010 and spring - May 2010. The results of analysis for the biotic communities were according to the Norm concerning the reference objectives for the surface water quality classification (Order MMGA no.161/2006) and also, to the Directive 2000/60/EC which established a framework for community action in the field of water policy. To achieve the objectives were sampled momentary storage compartments - water and sediment – in order to study the most representative biotic communities of the aquatic ecosystems (phytoplankton, zooplankton, benthic macro invertebrates) and to evaluate the contaminated sites by the distribution of pollutant substances in terms of biotic communities. This was choosen for captured important stages of life cycles and fluctuation fields of the main factors that influencing the control structure and functions of biotic populations. The analysis of the biotic communities in the all sampling site focused on the quantitative (numerical density, biomass, abundance after numerical density and biomass) and qualitative component (dominant species, indicator species). The results of the study can be used by various stakeholders, mainly the mining company and local municipalities, in order to integrate them in their post-mining measures, thereby making them aware of the potential long-term impact of mining on the environment and on human health as well as on the local economy.