Defining ecological status of phytobenthos in very large rivers: a case study in practical implementation of the Water Framework Directive in Romania

Abstract

Establishing ecological assessment schemes is challenging when gradients are short and there are no sites with minimal anthropogenic alteration against which metrics can be calibrated. This is the situation for large rivers in Romania and this paper describes efforts to establish meaningful ecological status concepts. The intercalibration exercise, conducted as part of Water Framework Directive (WFD) implementation, has provided a metric (“phytobenthos Intercalibration Common Metric“, pICM) which allows ecological status in different countries to be expressed on a common scale. The average boundary positions of countries who participated in this exercise provided a “common view” of status and, together with pICM, offer an “off-the-shelf” solution for countries unable to develop independent methods. However, even when expressed as pICM, Romanian phytobenthos data have a weak relationship with nutrients. Analysis of chemical data and comparison with similar data from elsewhere in Europe confirm that there are few sites with significantly elevated nutrient concentrations. Incorporation of the Romanian data into the larger dataset produced a stronger relationship from which the status of phytobenthos in very large rivers in Romania could be confirmed. This paper shows how the consensus that emerged from the WFD intercalibration exercise supports those countries unable to participate in the initial exercises.