In this paper the results from a workshop of the OSPAR Intersessional Correspondence Group on Eutrophication Modelling (ICG-EMO) held in Lowestoft in 2007 are presented. The aim of the workshop was to compare the results of a number of North Sea ecosystem models under different reduction scenarios. In order to achieve comparability of model results the participants were requested to use a minimum spin-up time, common boundary conditions which were derived from a widerdomain model, and a set of common forcing data, with special emphasis on a complete coverage of river nutrient loads. Based on the OSPAR requirements river loads were derived, taking into account the reductions already achieved between 1985 and 2002 for each country. First, for the year 2002, for which the Comprehensive Procedure was applied, the different horizontal distributions of net primary production are compared. Furthermore, the differences in the net primary production between the hindcast run and the 50% nutrient reduction runs are displayed. In order to compare local results, the hindcast and reduction runs are presented for selected target areas and scored against the Comprehensive Procedure assessment levels for the parameters DIN, DIP and chlorophyll. Finally, the temporal development of the assessment parameter bottom oxygen concentration from several models is compared with data from the Dutch monitoring station Terschelling 135. The conclusion from the workshop was that models are useful to support the application of the OSPAR Comprehensive Procedure. The comparative exercise formulated specifically for the

Potential long-distance dispersal of eelgrass seeds via floating generative shoots from a 256 ha meadow in the Ems Estuary (Wadden Sea) was studied by means of computer-simulation modelling. Flowering shoot density (peaking at 7.8 m -2 ) and total seed production (1094 million seeds yr -1 ) of this meadow was determined in the field and used as model input. Dispersal of floating generative shoots dislodged by increased water turbulence during autumn was modelled using a 3D transport model (Delft3D-WAQ). Transport of eelgrass seeds contained in floating reproductive shoots with the prevailing hydrodynamic regime revealed maximum dispersal distances of up to 130 km from the source of seed production. The effect of wind speed and direction on seed transport was assessed by applying a wind drag function (3% of wind speed) on surface currents in the model using actual wind data from 10 consecutive years (1993 to 2002). Main transport direction under average autumn wind conditions was northeastward. Easterly winds (occurring at an average frequency of 15%) were responsible for some westward transport of eelgrass seeds (at densities > 0.2 seeds m -2 ) up to 20 km from the estuary. Westward eelgrass colonization of suitable areas in the Dutch Wadden Sea appears to be limited by seed supply due to transport limitations posed by the prevailing hydrodynamic regime. Extreme events, such as prolonged Eastern storms, might promote seed dispersal further westwards, allowing for natural recovery of eelgrass in this area; this theory is supported by observations of localized eelgrass patches up to 40 km west of the estuary. KEY WORDS: Seed dispersal · Zostera marina · Transport modelling · Wind effects · Recruitment limitation · Wadden SeaResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 358: 115-124, 2008 exists (McMillan 1991), Zostera marina seeds are not viable beyond their first season (Orth et al. 2000). Successful eelgrass regeneration will therefore depend on the dispersal of seeds from existing eelgrass stands, the subsequent retention of these seeds in potentially suitable locations, and their successful germination and establishment (Hootsmans et al. 1987, Greve et al. 2005.The potential for reproductive shoots of eelgrass to become dislodged and raft over great distances was investigated in Chesapeake Bay (USA) by Harwell & Orth (2002). Dislodgement of reproductive shoots under the influence of extreme hydrodynamic conditions depended on their biomechanical properties, such as breaking stress, breaking strain, elasticity modulus and toughness (Patterson et al. 2001). Once detached, floating reproductive shoots were found to remain positively buoyant for 2 to 3 wk and to retain mature seeds for up to 3 wk before release, allowing for substantial transport of seed-containing, floating generative shoots from source populations by a combination of tidal currents and wind influences (Harwell & Orth 2002).Recent genetic and field studies have shown greater variati...

ABSTRACT. The European Union Marine Strategy Framework Directive requires the Good Environmental Status of marine environments in Europe's regional seas; yet, maritime activities, including sources of marine degradation, are diversifying and intensifying in an increasingly globalized world. Marine spatial planning is emerging as a tool for rationalizing competing uses of the marine environment while guarding its quality. A directive guiding the development of such plans by European Union member states is currently being formulated. There is an undeniable need for marine spatial planning. However, we argue that considerable care must be taken with marine spatial planning, as the spatial and temporal scales of maritime activities and of Good Environmental Status may be mismatched. We identify four principles for careful and explicit consideration to align the requirements of the two directives and enable marine spatial planning to support the achievement of Good Environmental Status in Europe's regional seas.Key Words: DPSWR; Good Environmental Status; marine spatial planning; maritime spatial planning; spatial scale temporal scale THE POLICY CONTEXT Global and regional assessments confirm that the capacity of our ocean ecosystems to continue to deliver ecosystem services that underpin human well-being is declining because of human activities (e. The EU is drafting a directive on MSP specifically to give cross-border cooperation a firm legal footing (European Commission 2013). Although the responsibility for MSP lies at the national level and addresses maritime activities in a nation's Exclusive Economic Zone (EEZ), a transnational, subregional, and even a regional sea perspective is called for when maritime activities and/or their effects cross national borders (Gee et al. 2011). This creates considerable challenges for the planning process and stakeholder consultation (e.g., Argardy et al. 2011, Maritime Spatial Planning in the North Sea 2012, Halpern et al. 2012, Jentoft and Knol 2014. However, it also provides challenges for assessing effects on the marine environment given the requirement under the MSFD to achieve GES at subregional and 9]). We address effects on the marine environment by examining the spatial and temporal dimensions of both GES and MSP.We examine the role of MSP in an ecosystem approach and MSP's potential contributions to achieving GES. We aim to assess whether mismatches of spatial and temporal scales between MSP and marine ecosystems might constrain this role and these contributions. The methodology is based on the Driver Pressure State Welfare Response (DPSWR) framework (Cooper 2013). Findings are illustrated by two case studies representing aspects of traditional and emerging sea use. We use DPSWR to provide a context for MSP in an ecosystem approach to achieve GES. We then compare the spatial and temporal scales of MSP and GES. We identify a number of principles that require explicit consideration by MSP. These principles address the specific focus of our work; namely, the spatial an...

No abstract

No abstract