Dahl, K. & Carstensen, J. 2008: Tools to assess conservation status on open water reefs in Nature-2000 areas. National Environmental Research Institute, University of Aarhus. 25 pp. – NERI Technical Report No. 663.

 

Summary

This work shows that total and cumulative vegetation covers are excellent indicators of the ecological quality of reefs in open waters.

 

Total nitrogen load to inner Danish waters from January to July, solar radiation from May to July, depth and grazing pressure caused by sea urchins are important anthropogenic and natural factors controlling the two indicators. Furthermore, there are significant differences between most reef locations used in the analyses.

 

Based on parameter estimates from the statistical analyses, predictive models for both indicators have been established for a number of reef locations with good data coverage. Scenarios were made for reefs with high data sampling giving the best description of variables controlling the vegetation. In Danish waters there is a general lack of knowledge on the quality of biological variables before eutrophication, fishery and extraction of boulders and stone became a problem. Use of models to set targets for the vegetation covers is a way to establish a quality assessment tool. A precondition in this case is targeted nitrogen loads based on other indicators, measurements or models.

 

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