German Exclusive Economic Zone Research Articles

Composition of the epibenthic decapod crustacean megafauna of the German Exclusive Economic Zone: comparison and analysis of past and recent surveys

This study comprises and compares epibenthic samples of the marine crustacean decapod megafauna, taken with a beam trawl at numerous stations in the German Exclusive Economic Zone of the North Sea in the years 1987, 1990, 2007 and 2013. All decapod crustacean species were recorded quantitatively. An overview of the decapod faunal composition with respect to changes in space, species and abundance with time is given. A time-dependent decrease of rare and often northern species at the research area is obvious, as a result of an increase of some dominant species concentrating in coastal areas. In 2013, a more uniform species composition seems to have developed. Decapod species and abundance depletions may be influenced by many factors, among them also climate change and fisheries.

Co-location of passive gear fisheries in offshore wind farms in the German EEZ of the North Sea: A first socio-economic scoping

Worldwide the renewable energy sector is expanding at sea to address increasing demands. Recently the race for space in heavily used areas such as the North Sea triggered the proposal of co-locating other activities such as aquaculture or fisheries with passive gears in offshore wind farms (OWFs). Our interdisciplinary approach combined a quantification of spatial overlap of activities by using Vessel Monitoring System and logbook data with a stakeholder consultation to conclude and verify on the actual feasibility of co-location. In the German Exclusive Economic Zone (EEZ) of the North Sea up to 90% of Danish and 40% of German annual gillnet fleet landings of plaice overlapped with areas where OWFs are developed. Our results indicated further that the international gillnet fishery could lose up to 50% in landings within the North Sea German EEZ when OWF areas are closed entirely for fisheries. No spatial overlap was found for UK potters targeting brown crab in the German EEZ. We further identified a number of key issues and obstacles that to date hinder an actual implementation of co-location as a measure in the marine spatial planning process: defining the legal base; implementation of safety regulations; delineation of minimum requirements for fishing vessels such as capacities, quotas, technical equipment; implementation of a licensing process; and scoping for financial subsidies to set up business. The stakeholder consultation verified the scientific findings and highlighted that all those points need to be addressed in a planning process. In the German EEZ we have shown that the socio-economic importance of spatial overlap varies within planning boundaries. Therefore we recommend an interdisciplinary bottom-up approach when scoping for suitable areas of co-location. Hence, an informed marine spatial planning process requires comprehensive and spatial explicit socio-economic viability studies factoring in also ecological effects of OWFs on target species.

A GIS modelling framework to evaluate marine spatial planning scenarios: Co-location of offshore wind farms and aquaculture in the German EEZ

The concept of co-location of marine areas receives an increased significance in the light of sustainable development in the already heavily used offshore marine realm. Within this study, different spatial co-location scenarios for the coupling of offshore aquacultures and wind farms are evaluated in order to support efficient and sustainable marine spatial management strategies. A Geographic Information System (GIS) and multi-criteria evaluation (MCE) techniques were combined to index suitable co-sites in the German exclusive economic zone of the North Sea. The MCE was based on criteria such as temperature, salinity or oxygen. In total, 13 possible aquaculture candidates (seaweed, bivalves, fish and crustaceans) were selected for the scenario configuration. The GIS modelling framework proved to be powerful in defining potential co-location sites. The aquaculture candidate oarweed (Laminaria digitata) revealed the highest suitability scores at 10–20m depth from April to June, followed by haddock (Melanogrammus aeglefinus) at 20–30m depth and dulse (Palmaria palmata) and Sea belt (Saccharina latissima) at 0–10m depth between April and June. In summary, results showed several wind farms were de facto suitable sites for aquaculture since they exhibited high suitability scores for Integrated Multi-Trophic Aquaculture (IMTA) systems combining fish species, bivalves and seaweeds. The present results illustrate how synergies may be realised between competing needs of both offshore wind energy and offshore IMTA in the German EEZ of the North Sea. This might offer guidance to stakeholders and assist decision-makers in determining the most suitable sites for pilot projects using IMTA techniques.

Estimating historical trawling effort in the German Bight from 1924 to 1938

Based on historical landings and landings-per-unit-effort data, fishing effort was estimated in the period of 1924–1938 in a study area representing the German exclusive economic zone (EEZ) in the North Sea. Three main trawling fisheries were identified, i.e. the international flatfish fisheries comprising the effort of steam trawlers and motor cutters, the German shrimp fisheries and the industrial inshore fisheries. Except for shrimp trawling, which was performed by beam trawling with one beam per vessel, all historical trawling effort was identified as otter board trawling. The trawling effort increased from 1,131,000 to 1,232,000h in 1924 to 3,170,000 to 3,836,000h in 1937 and declined in 1938. The main fishery effort was contributed by the German shrimp fisheries, accounting for a maximum of 2,140,000h in 1937. In comparison, in 2006, approximately 540,000h were spent fishing in the trawl fisheries of the study area, comprising effort from small (≤221kW) to large beam trawlers (>221kW), shrimp fisheries and otter board trawling. The bulk of the historical effort was concentrated at water depths of 5–20m. With the implementation of combustion engines and new gear technology, the period of 1924–1938 marked a new era for marine fishing when virtually all space became accessible and, in particular, the trawling of inshore areas increased.

Investigation of sonar transponders for offshore wind farms: Modeling approach, experimental setup, and results

The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed.

A spatially explicit risk approach to support marine spatial planning in the German EEZ

An ecosystem approach to marine spatial planning (MSP) promotes sustainable development by organizing human activities in a geo-spatial and temporal context. (1) This study develops and tests a spatially explicit risk assessment to support MSP. Using the German exclusive economic zone (EEZ) of the North Sea as a case study area, current and future spatial management scenarios are assessed. (2) Different tools are linked in order to carry out a comprehensive spatial risk assessment of current and future spatial management scenarios for ecologic and economic ecosystem components, i.e. Pleuronectes platessa nursery grounds. With the identification of key inputs and outputs the suitability of each tool is tested. (3) Here, the procedure as well as the main findings of the spatially explicit risk approach are summarised to demonstrate the applicability of the framework and the need for an ecosystem approach to risk management techniques using geo-spatial tools.

Extension of distribution of Pseudodiaptomus marinus, an introduced copepod, in the North Sea

Pseudodiaptomus marinus was described from eastern Asian waters and has subsequently been spread in the Indo-Pacific region, but has only been found in European waters since 2007. The presence of the species in inshore waters of the Southern Bight of the North Sea, in Calais Harbour and off Gravelines was noted in 2010 and 2011. The present records from the Continuous Plankton Recorder survey extend the known distribution northwards and across the Southern Bight between The Netherlands and British coasts. Net hauls for biological monitoring in the German exclusive economic zone add a location further north and east in the German Bight. Spread of the species to inshore waters of the eastern North Sea and to the Baltic is predicted.

Epifauna dynamics at an offshore foundation – Implications of future wind power farming in the North Sea

In the light of the introduction of thousands of large offshore wind power foundations into the North Sea within the next decades, this manuscript focuses on the biofouling processes and likely reef effects. The study explores the macrozoobenthos (biofouling) colonization at an offshore platform which is comparable to offshore wind turbine foundations. A total of 183 single samples were taken and the parameters water depth and time were considered comparing biofouling masses and communities. The blue mussel Mytilus edulis, Anthozoa and the Amphipoda Jassa spp. were the dominant species. The community from the 1 m zone and those from the 5 and 20–28 m zones can clearly be differentiated. The 10 m zone community represents the transition between the M. edulis dominated 1 m and 5 m zones and the Anthozoa dominated 20–28 m zone. In the future offshore wind farms, thousands of wind turbine foundations will provide habitat for a hard bottom fauna which is otherwise restricted to the sparse rocky habitats scattered within extensive sedimentary soft bottoms of the German Bight. However, offshore wind power foundations cannot be considered natural rock equivalents as they selectively increase certain natural hard bottom species. The surface of the construction (1280 m²) was covered by an average of 4300 kg biomass. This foundation concentrates on its footprint area (1024 m²) 35 times more macrozoobenthos biomass than the same area of soft bottom in the German exclusive economic zone (0.12 kg m−2), functioning as a biomass hotspot. Concerning the temporal biomass variation, we assume that at least 2700 kg biomass was exported on a yearly basis. 345 × 104 single mussel shells of different sizes were produced during the study period. It is anticipated that the M. edulis abundance will increase in the North Sea due to the expansion of the offshore wind farm development. This will result in the enhanced production of secondary hard substrate (mussel shells) and its associated fauna and will intensify filtration rates of the seawater. This predicted ecological system change is coined the ’Mytilusation’ of the German Bight.

Benthos and demersal fish habitats in the German Exclusive Economic Zone (EEZ) of the North Sea

We compiled data from different monitoring surveys to analyse and compare community and diversity patterns of fish, epi- and infauna in the German Exclusive Economic Zone (EEZ) of the North Sea in order to identify benthic habitats common to all faunal components. We found congruent community patterns of fish, epi- and infauna for the coastal waters, the Oysterground and the area called “Duck’s Bill”, which coincided with specific abiotic characteristics of these regions. The three regions were defined as special habitats for fish, epi- and infauna species in the German EEZ. The differences in the seasonal variability of abiotic factors seem to be the most important discriminating abiotic characteristic for the three habitats. The spatial distribution of fish, epifauna and infauna communities remained stable over time although habitat characteristics such as sea surface temperature increased due to climate change. However, it is expected that the coastal habitat will be more sensitive to future climate change effects in contrast to the Oysterground and Duck’s Bill habitat.

Early European Experience in Marine Spatial Planning: Planning the German Exclusive Economic Zone

Marine spatial planning is emerging as an integrated, resource management-led approach to governing the use of the seas. Recent initiatives include those of some north European countries, including Germany, which has now completed a plan for its federal offshore territory. In this article, an analysis is presented of this pioneering plan and the consultation process behind its production, with a particular emphasis on the treatment of different sectoral interests around which the plan was structured. This revealed the attempts to coordinate not only the different demands at sea by means of allocation of areas and cross-sectoral considerations, but also the uneven representation of activities with certain interests gaining strongly and others effectively marginalized. This study provides early empirical evidence of the tensions involved in the attempt to adopt a spatial approach to marine governance. This new domain for planning is situated in the overlapping, but distinct domains of marine management and spatial planning. The conceptual backgrounds of both are drawn upon in assessing the strengths and weaknesses of the plan and in suggesting how marine plans might gain by giving close attention to the broader principles of marine and strategic planning.

Integrated modelling tools to support risk-based decision-making in marine spatial management

The implementation of an ecosystem approach to marine spatial management requires practical tools to support risk-based decision-making. We combined a Bayesian Belief Network with a Geographical Information System (GIS) for the spatially explicit quantification of the ecological and economic risks of spatial management options. As an example we assessed the German exclusive economic zone (EEZ) in the North Sea to determine the potential effects of 2 scenarios on the vulnerability of plaice Pleuronectes platessa to fishing, fishing fleets and their revenues. In the first scenario we simulated a shift in plaice distribution due to changes in bottom temperatures to assess spatial management options. Then we imitated an expansion of offshore wind energy development with an associated reallocation of international fishing effort to assess the ecological and economic consequences. We predicted that an increase of 0.5°C in the average bottom temperature would require a significant reduction in fishing effort to maintain the current relative level of the vulnerability of plaice to fishing. The likely consequences of the second sce- nario were a homogenous increase in plaice catches around the areas closed for fishing, together with a decrease in the vulnerability of plaice to fishing within 17% of the study area. Our results showed the great potential of this framework to integrate the spatially explicit assessment of the economic and ecological risks of spatial management options. We conclude that this modelling framework can support the implementation of an ecosystem approach to marine spatial manage- ment, as it enables the derivation of probabilistic estimates which can be used directly in risk- based decision-making.

Integrating Multiple Pressures at Different Spatial and Temporal Scales: A Concept for Relative Ecological Risk Assessment in the European Marine Environment

ABSTRACT A Relative Ecological Risk Assessment model is presented with an emphasis on risk calculation and risk characterization. Several types of impacts are incorporated including mortality, competition, and disturbance effects at different spatial scales exemplifying fisheries effects on benthic communities, marine mammals, and birds. Fisheries sectors analyzed are beam trawlers, demersal otter trawlers, gillnet, and sandeel fisheries in the German Exclusive Economic Zone of the North Sea. The basic ecological unit to which the risk score applies is the population/stock level or the distribution range of a community. The risk function comprises an exposure term and the loss function. The loss function is driven by a relative term, that is, the ratio between negative potential, that is, decline or mortality, and positive potential, that is, recovery. Sensitivity analysis is carried out to indicate model precision and its capabilities to distinguish between high and low risk areas and impacts. Limit reference values important for characterization of relative ecological risk are analytically defined. Model parameterization is based on literature review, and calculated examples show that beam trawling appears as a strong risk component to benthic communities, likely to exceed the limit reference value. For marine mammals (i.e., Harbour porpoise) in the German EEZ, by-catch in gillnet fisheries is a relatively strong risk.

Spatio-temporal associations between harbour porpoise Phocoena phocoena and specific fisheries in the German Bight

Interactions between cetaceans and fisheries are a major concern of cetacean conservation and fisheries management, as by-catch and resource competition occur as a result. To assess potential interaction between porpoises and fisheries in the German Bight, high-resolution spatial and temporal data were analysed in order to reveal association patterns between cetaceans and fisheries in the German Exclusive Economic Zone (EEZ) of the North Sea. To facilitate interpretation of resulting patterns, additionally, relationships of fish assemblages were analysed. Vessel monitoring system (VMS) data from 2006 and fisheries surveillance data from 2002 to 2006 were acquired to calculate fishing effort, aerial survey data from 2002 to 2006 to evaluate porpoise distribution, and trawl survey data from 2000 to 2007 to assess fish assemblage. Relationships were analysed in terms of seasonal association and overlap. Results showed that porpoise distribution was positively associated with sandeel fisheries in all seasons and with gillnet fisheries in summer. Overlaps for sandeel and gillnet fisheries were high in summer, while negligible in spring and autumn. In spring, high overlap was found for large beam trawlers targeting sole and plaice. In parallel, porpoise distribution was positively linked to fish assemblage components representing sandeel and poor cod in summer and flatfish in spring. Our results suggest that, especially in summer, resource competition between porpoises and industrial sandeel fisheries is likely and the risk of by-catch in gillnets is increased. In spring, interference with sole and plaice fisheries is to be expected.

Offshore wind power development as affected by seascape values on the German North Sea coast

In Germany, the first permits have now been issued for the construction of large-scale offshore wind farms in the German Exclusive Economic Zone (EEZ). This paper focuses on perceptions of the local seascape and the role of aesthetic seascape qualities in shaping local attitudes to offshore wind farming. Based on a survey of local residents in the districts of Dithmarschen and North Frisia, it shows that aesthetic seascape perception alone cannot account for local attitudes to offshore wind farming. Three main aspects seem to come together to determine these attitudes: deeply held convictions of the sea as a natural space, deeply held views of the local landscape and linked to this local identity, and also perceptions of renewable energies in combination with attitudes to issues such as climate change and sea level rise. The paper draws some conclusions on the future of the sea as a natural space or energy space.

Gesamtplanerische Abstimmung zu Wasser – Rechtslage und Rechtsentwicklung

New forms of using the sea (e.g. offshore wind power, cable laying, tourism, offshore mining), and the corresponding concern for environmental protection, have considerably increased the necessity for an early and balanced co-ordination of conflicting interests. The resulting conflicts need to be regulated and controlled by law, particularly through the application of prospective planning instruments (maritime spatial and regional planning). It should be noted that, compared to the coastal zone, the scope of sea use and environmental protection requirements comprised by maritime spatial planning in the exclusive economic zone (EEZ) is restricted by international law which does not, however, question the specifics of maritime spatial planning in the EEZ. The necessity to take action in respect of this subject matter was recognized by the German legislator and accommodated by means of the Raumordnungsgesetz (ROG) as early as in 2004; it will also be dealt with in the amendment of the ROG. The allocation of competences in maritime spatial planning in the EEZ remains a matter of dispute, since the federal reform of 2006 (Föderalismusreform 2006) did not clarify this matter at all. Moreover, legal issues regarding the Raumordnungsplan for the German EEZ, which currently is in the process of formation, have yet to be dealt with. In spite of such problems, the activity is of considerable significance for the co-ordination of sea use and protection. Beyond that, it signifies a substantial step towards a “maritime infrastructure law“.

Mapping fisheries in the German exclusive economic zone with special reference to offshore Natura 2000 sites

Large intensity and diversity of human activities result in an increase in complexity in the utilization of space. This paper describes the fisheries and a method to map fishing efforts and catches of different fleets by combining vessel monitoring system (VMS) data and logbook data. The method makes it possible to explore the spatial and temporal variability of fishing and the potential impacts of proposed management measures on the fisheries. The method is proposed to be used in the development of management plans for marine protected areas such as Natura 2000 sites, designated to protect vulnerable habitats and species.

Natura 2000 sites and fisheries in German offshore waters

Abstract Pedersen, S. A., Fock, H., Krause, J., Pusch, C., Sell, A. L., Böttcher, U., Rogers, S. I., Sköld, M., Skov, H., Podolska, M., Piet, G. J., and Rice, J. C. 2009. Natura 2000 sites and fisheries in German offshore waters.–ICES Journal of Marine Science, 66: 155–169. The principal objective of sites selected as part of Natura 2000 is to achieve or maintain a favourable conservation status of habitats and species named in the EU Birds and Habitats directives. In the German exclusive economic zone, the habitat types protected by this legislation are sandbanks and reefs; protected species include marine mammals, seabirds, and specific migratory fish species. The ICES project Environmentally Sound Fishery Management in Protected Areas (EMPAS) aims to answer two questions: (i) To what extent do specific fishing activities significantly threaten attainment of the conservation objectives of the Natura 2000 sites? (ii) What management measures would reduce these conflicts and how effective would they be at helping to ensure the favourable condition of these sites? Assessments of fishing impacts on Natura 2000 sites require basic data on the conservation status of individual habitats and species, as well as data for fine-scale distributions of ongoing fishing activities. This paper describes and discusses the process used by the EMPAS project in developing fishery-management plans for each Natura 2000 site in German offshore waters.

The use of 'ecological risk' for assessing effects of human activities: An example including eutrophication and offshore wind farm construction in the north sea

This paper takes the move from the uncertainty surrounding ecosystem thresholds and addresses the issue of ecosystem-state assessment by means of ecological integrity indicators and 'ecological risk'. The concept of 'ecological risk' gives a measure of the likelihood of ecosystem failure to provide the level of natural ecological goods and services expected/desired by human societies. As a consequence of human pressures (use of resources and discharge into the environment), ecosystem thresholds can be breached thus resulting in major threats to human health, safety and well-being. In this study we apply the concept of 'ecological risk' to two case-studies in the German exclusive economic zone: eutrophication and construction of offshore wind farms. The effects of different future scenarios for single-uses upon ecosystem integrity are analysed as well as the effects of one combined scenario. We conclude that in the short term construction of offshore wind farms can influence some processes to a much larger degree than eutrophication, however, combined impacts deriving from eutrophication and offshore wind farm construction need a more detailed analysis. Due to non-linear ecosystem processes, effects of combined or multiple uses of marine resources in terms of 'ecological risk', cannot be extrapolated from single-use scenarios.

Fisheries in the context of marine spatial planning: Defining principal areas for fisheries in the German EEZ

A method is presented to define principal areas for fisheries at high spatial resolution applicable to be implemented into marine spatial planning procedures. Vessel monitoring system (VMS) data from 2005 to 2006 are acquired to determine vessel-based fishing effort. Principal areas for the German exclusive economic zone (EEZ) are defined as areas in which 75% of the effort of either year is carried out. Examples are given for the 5 most abundant fisheries in the German EEZ in terms of vessel-based effort, i.e. gill netting, pelagic trawling, demersal otter board trawling and beam trawling >300 and <300 HP. A historical comparison for demersal otter board trawling shows relative stability of spatial utilization patterns in the North Sea section of the EEZ.

Using decision trees to predict benthic communities within and near the German Exclusive Economic Zone (EEZ) of the North Sea

In this article a concept is described in order to predict and map the occurrence of benthic communities within and near the German Exclusive Economic Zone (EEZ) of the North Sea. The approach consists of two work steps: (1) geostatistical analysis of abiotic measurement data and (2) calculation of benthic provinces by means of Classification and Regression Trees (CART) and GIS-techniques. From bottom water measurements on salinity, temperature, silicate and nutrients as well as from punctual data on grain size ranges (0-20, 20-63, 63-2,000 mu) raster maps were calculated by use of geostatistical methods. At first the autocorrelation structure was examined and modelled with help of variogram analysis. The resulting variogram models were then used to calculate raster maps by applying ordinary kriging procedures. After intersecting these raster maps with punctual data on eight benthic communities a decision tree was derived to predict the occurrence of these communities within the study area. Since such a CART tree corresponds to a hierarchically ordered set of decision rules it was applied to the geostatistically estimated raster data to predict benthic habitats within and near the EEZ.