Connecting AARHUS UNIVERSITY the Habitats BlueReef Directive End Conference and the Water Framework Directive using restoration of stone reefs as a supplementary measure Jesper H. Andersen 1,2 Projekt Director, Ph.D. 1: Department of Bioscience, AU 2: DCE Nationalt Center for Environment and Energy, AU In collaboration with: Peter Bondo Christensen, Karsten Dahl, Henrik Fossing og Ciarán Murray, AU Flemming Møhlenberg, DHI
Danish marine waters are impacted by multiple stressors Source: Jacksson et al. (2001). Science.
Eutrophication status in Danish marine waters Based on: Naturstyrelsen (2012): Danmarks Havstrategi. Udkast til Basisanalyse.
Status of biodiversity in Danish marine waters Based on: Naturstyrelsen (2012): Danmarks Havstrategi. Udkast til Basisanalyse.
Source: Hansen et al. (submitted); based on HELCOM (2010) and Andersen & Stock (2013) BIOSCIENCE Mapping of cumulative (additive) human pressures and impacts
Management of human activities in marine waters is a minefield In Demark, work to reverse trends and the current impaired conditions is in general driven by: Danish Actions Plans on the Aquatic Environment, e.g. the EC UWWT Directive and the EC Nitrates Directive (eutrophication) The EC Habitats Directive (biodiversity) The EU Water Framework Directive (ecological and chemical status) And starting up, we have the EU Marine Strategy Framework Directive as well as long list of other: EC/EU Directives, international agreements (e.g. CBD and HELCOM BSAP) and national plans and strategies (e.g. pesticides).
Source: HELCOM (2010) BIOSCIENCE Ecosystem-based management should not be made complicated
Source: HELCOM (2010): Ecosystem Health of the Baltic Sea. BIOSCIENCE Hvordan virker den foreslåede strategi?
On the role of submerged aquatic vegation in Danish coastal waters More structure Biodiversity Slow turnover of detritus Basis for long food chains Stable ecosystems Oxygen production close to the sea floor Better Production and consumption separated in time oxygen conditions Restoration of habitats with long-lived SAV species is essential to meet the targets of a good conservation status (cf. HD), a good ecological status (cf. WFD). and a good environmental status (cf. MSFD) Based on: Middelboe (2013).
2km 2 scattered stone reef could potentially result in an ecological improvement which otherwise would require a reduction of nitrogen loads in the order of 800-1000 tonnes TN. BIOSCIENCE Pilot project (2007-2008) A collaboration between DHI and NERI (now Aarhus University). Model based with true forcings, i.e. wind and light availability In addition based on a number of assumptions (described in details on pages 18-20 in the report). Interim conclusion:
Stones + light = O 2 = better conditions
Area and duration of hypoxia is reduced when oxygen producing reefs are introduced A total of 40 scenarios: Reef area. Location of reefs Specific oxygen production Climate effects Kilde: DHI & DMU (2008): Stenrev i Limfjorden.
XX N-fluxreduktion (tons/år) 1400 1200 1000 800 600 400 200 Meget Spredt Very scattered Spredt 1,2 Samlet 1,2 Single reefs 1,2 Scattered reefs 1,2 0 0 2 4 6 8 10 Kilde: DHI & DMU (2008): Stenrev i Limfjorden. Revareal (km 2 )
Wrap up Restoration of stone reefs could be a supplementary measure to further reductions of nutrient loads. An ongoing screening project (by DHI and AU) has so far identified only two promising areas (Limfjorden and Flensborg Fjord) Stone reefs are a basis measure sensu the HD, but not sensu the WFD. Mini stone reefs? Would be good for biodiversity but any N effect would probably be marginal. A demonstration project in central parts of Limfjorden is needed to finetune the assumptions on which the pilot project is based and also to document potential effects of large scale restoration of reefs. When results from a demonstration project become available, a restoration project, split into phases, could be considered We should strive for a better coordination of the implementation of EU Directives, especially the Habitats Directive and the Water Framework Directives