Aarhus University - Danish coast

Restoration Project

Aarhus University - Danish coast

Restoration Objective:

In addition, coastal ecosystems affected by eutrophication may become more sensitive to other pressures such as climate change and fishery (Justíc et al. 1996; Baden et al. 2012), reducing the rate of recovery and likely altering achievable restoration targets (Carstensen et al. 2013). Consequently, the use of conceptual and numerical models to test recovery and restoration scenarios as well as legislative frameworks focusing on specific targets, measures, and tolerable deviations often lack information from empirical data for validation.

Key Reasons For Decline:

Water Pollution

Scientific Paper

Recovery of Danish Coastal Ecosystems After Reductions in Nutrient Loading: A Holistic Ecosystem Approach.

Bo Riemann, Jacob Carstensen, Karsten Dahl, Henrik Fossing, Jens W. Hansen, Hans H. Jakobsen, Alf B. Josefson, Dorte Krause-Jensen, Stiig Markager, Peter A. Stæhr, Karen Timmermann, Jørgen Windolf, Jesper H. Andersen
Estuaries and Coasts.

Site Observations:

Observation Date

1st Jan 1989 – 1st Jan 2013

Action Summary:

We examined 45 estuarine and coastal sites scattered across Denmark that have been regularly monitored as part of the Danish National Aquatic Monitoring and Assessment Program (DNAMAP). The majority of the study sites (29) are from the Kattegat and Belt Sea areas, i.e., the transition Estuaries and Coasts (2016) 39:82–97 83 area between the brackish Baltic Sea and the saline North Sea and Skagerrak (Fig. 1). The five sites on the west coast of Denmark are influenced by north-flowing nutrient-rich waters from the southern North Sea. Two of these sites are located in the Wadden Sea, and two other sites represent lagoonal systems, where the exchange with the North Sea is controlled by sluices. A total of 10 sites are located in the Limfjorden complex, a shallow (mean depth 5.5 m) strait connecting the North Sea to the west and the Kattegat to the east. Due to the dominating westerly winds, the transport of water is generally from the west to the east in this system. Finally, there is a station near Bornholm, an island in the southern Baltic Sea.

Lessons Learned:

None to report

Project Outcomes:

Macroalgal cover exhibited an overall increase from 1990 to 2013 despite marked year-to-year variation; total cover increased by 0.69% per year and cumulative cover by 1.49% per year over this period (Table 1). This increase in algal cover mirrored the observed decline in TN and chlorophyll a concentrations (Figs. 3 and 4) and occurred even though the Secchi depths solely increased during the most recent years and not during the period 1990–2013 as a whole (Fig. 5, Table 1).

Area of Restoration (Ha)


Indicator Data:


Ending Value:

Starting Value:

Kelp Cover