Towards the implementation of the Water Framework Directive in Mediterranean transitional waters: the use of macroinvertebrates as biological quality elements

Abstract

During the last decade the Water Framework Directive (WFD) has driven scientific community endeavours towards the development of assessment tools to determine the Ecological Quality Status (EQS) for all surface waters, including transitional waters (TWs). Macroinvertebrates being used as Biological Quality Elements encouraged the development of distinct multimetric and multivariate indices, initially based on taxonomic approaches. Those indices were mostly developed for the marine environment and applied extensively on TWs. The main discrepancies in the ecological quality status assessment arise on TWs, partially due to the difficulty in discriminating the effects of natural stress from anthropogenic impact. As a response, indices following functional approaches are being developed and applied in assessing the EQS in these environments. Next, the validation and intercalibration of the metrics as well as the settlement of reference conditions are additional sources of variability inherent to any assessment. This paper aims at briefly presenting the different steps needed for the implementation of WFD on Mediterranean TWs. It highlights existing difficulties and possible research lines to be explored in order to reduce sources of variability and better assess the status of such water bodies.

Keywords:

• Water Framework Directive
• Mediterranean coastal lagoon
• transitional waters
• assessment
• macroinvertebrate indices
• body size
• biological traits
• reference conditions
• intercalibration

Acknowledgements

The authors are grateful to the anonymous reviewers for their suggestions and comments, which allowed significant improvement of the manuscript.

Additional information

Funding

This work was funded by the European project ‘Training Network for Monitoring Mediterranean Marine Protected Areas’ (MMMPA: FP7-PEOPLE-2011-ITN) [grant number 290056].