Report: Macrozoobenthos: Evaluation system WFD — Weser fatigue (2006)»

This study was prepared by KÜFOG GmbH and was commissioned in August 2005 by the NLWKN Coast Research Centre, Wilhelmshaven branch office. Designed as a follow-up study of the compilation of benthos data of the Weser (KÜFOG 2004) already carried out in 2004, the core of the study consists of a digital data collection of the macrozoobenthos investigations in the Weser that have been collected so far in numerous reports and publications. On the basis of the first comprehensive data-based description of benthic partial habitats of the brackish water zone of the Weser in WITT (2004) and additional data from the limnic part of the Weser (KÜFOG 2006a), further extensive data were added, which were collected and evaluated for the planning for the current Weser adaptation (see Chapter 3). The data base is used to describe and evaluate partial habitats of the transition waters taking into account abiotic conditions. From historical maps and area descriptions, the partial habitats are identified, digitally processed and compared with the current structures before the significant extensions of the Weser to the Greater Shipping Route (FRANZIUS 1888). The benthic habitats are described and qualitatively and quantitatively characterised on the basis of the benthos data. A data-based historical reference state is reconstructed from the comparison of hydromorphological development and colonisation. The close connection of benthic settlement to hydromorphological conditions is the basis of the assessment approach and is significantly more important than other assessment systems (cf. Dutch approach according to BOUMA et al. 2006). In this context, the approach adopted here assumes, in principle, a separate consideration of the different sub-habitants within the transitional waters, as proposed, inter alia, by WITT (2004) and specified in KÜFOG (2004). The evaluation criteria developed here are compared with the existing approaches of Ysebaert on the Westerschelde and War on the Elbe. The suitability of Ysebaert’s content-related approach is examined and technically discussed on the basis of the Weser data. Suggestions for changes and deviations are presented and justified. A discussion on the applicability of the resulting evaluation proposal will be held in the light of the requirements arising from the implementation of the Water Framework Directive, e.g. for appropriate monitoring of transitional waters.”