The objectives of the ICES NSBP 2000 are:

1. to re-visit several stations sampled during the 1986 ICES North Sea Benthos Survey;
2. to augment the NSBP 2000 data with information from other sources (principally from the period 1999 � 2001) in order to maximise coverage of the North Sea area;
3. to establish a new NSBP data-base at the Flanders Marine Institute;
4. to work through annual ICES Study Group meetings, inter-sessional Workshops and via the ICES Benthos Ecology Working Group to resolve problems affecting the compatibility of data sets from different sources;
5. to determine patterns in contemporary North Sea benthic assemblages and the causal influences, by reference to supporting environmental data from the NSBP 2000 and other sources;
6. to compare the outcome of the NSBP 2000 with that of 1986 and to postulate causes for any observed differences, with reference to information on temporal changes in biotic and environmental factors, including human influences;
7. to report findings to ICES and to produce publications;
8. to provide a strategic evaluation of the utility of the collaborative exercise for sea-wide quality assessments, and to make recommendations for the timing and co-ordination of any future work.

Rationale

Macrobenthic infaunal communities are especially suited for long-term comparative investigations since many of the constituent species are of low mobility, relatively long lived and integrate effects of environmental changes over time. Further, the macrobenthos of the North Sea has been well studied on localized scales over the last hundred years. The sampling and analytical methodology is well established and so is the theoretical framework within benthic ecology. The macrobenthos is relatively easy to sample quantitatively and is of great importance for environmental surveillance for of the above reasons. It is in fact the main component of biological trend monitoring programmes aimed at evaluating the status of benthic ecosystems. However, the initiative to conduct a synoptic sampling excercise for the North Sea benthos was only taken in 1986, under ICES auspices (e.g., Heip & Craeymeersch, 1995; Heip et al., 1992; K�nitzer et al., 1992; Craeymeersch et al., 1997). This involved collaboration between five countries (Belgium, the Netherlands, Germany, France and UK) in the sampling of the entire southern part in April 1986. The data were supplemented by an earlier extensive grid survey of the northern part conducted by Scotland (see, e.g., Eleftheriou and Basford, 1989). In addition to analysis of the benthic macrofauna from grabs, data were also generated on the physico-chemical status of sediments (Basford et al., 1993; Irion & M�ller, 1987), on the meiofauna (principally copepods: see Huys et al., 1992) and the epifauna from small trawls or dredges (e.g., Duineveld et al., 1991).

Following the success of this work, the ICES Benthos Ecology Working Group recommended that a repeat survey should be conducted after more than 10 years had elapsed, in order to evaluate any changes to the status of assemblages identified in 1986, in relation to natural or human influences. A decision was therefore made to promote national effort towards the re-sampling of stations from the 1986 North Sea Benthos Survey or, alternatively, to seek contributions from ongoing national research and monitoring effort that might, collectively, allow a comparable holistic assessment to that achieved in 1986.

Plans for data analysis

Preliminary analyses of the status of the macrobenthic fauna in 2000 have been conducted using univariate and multivariate methods (e.g., TWINSPAN, Group-Average cluster analysis), aimed at a description of community structure and its attributes, such as biodiversity (see www.ices.dk for NSBP 2000 Study Group reports to date). Spatial distribution patterns will be analyzed for their relationship with environmental parameters. These include physico-chemical measurements of sediment samples (grain size, organic content, contaminants), depth, information on the annual cycle of the temperature of the bottom water, and water quality (e.g., turbidity, salinity). Additionally, we will use existing ecological and hydrographical models (e.g., the European Regional Seas Ecosystem Model: ERSEM) to obtain information on bottom currents, bottom shear stress and carbon input. We will also attempt to include spatial differences in fishing effort.

The NSBP 2000 data will be used for comparison with the 1986 ICES North Sea Benthos Survey (see www.ices.dk for preliminary outcomes to date). The data will be further analyzed for possible changes in the distribution of assemblages and different species, changes in density and biomass of species, phyla and trophic guilds. These changes will be discussed in the light of environmental fluctuations in the North Sea recorded by other studies. One example is the outcome from the Continuous Plankton Recorder programme, which shows changes in the algal biomass since the 1980s. Another example is the trawl survey database collated by Ruth Calloway-Zülke, incorporating information on epibenthos trawl surveys in the North Sea conducted in 2000.

Expected scientific outputs

The main aim of the survey is a descriptive evaluation of the macrozoobenthos communities in the North Sea in the year 2000 (+/-1 year), i.e., about 15 years after the first co-ordinated survey under the auspices of the ICES Benthos Ecology Working Group. Accordingly, an overall comparison with the results of the 1986 ICES North Sea Benthos Survey will be made, considering distribution patterns of the main benthic communities and of indicator species. To enable such comparison and to identify the causative factors involved in possible changes, long-term observation data from other sources (e.g., monitoring-type studies, meteorological/hydrological series, CPR data) will be included in the analyses. The planned publications will provide valuable material for forthcoming quality status assessments of the North Sea and also for measures to be taken for the protection of marine biodiversity and ecosystem functioning. Moreover, as several new uses and intensifications of existing ones are planned for North Sea waters (e.g., wind energy farms, sand and gravel extraction), co-ordinated spatial planning is required, for which benthos data are a fundamental requirement.

In addition to physico-chemical measurements of sediment samples alongside the benthic fauna, information on water depths, temperature, water quality and salinity will be incorporated in the analysis of species and community distributions. Also, we will use existing ecological and hydrographical models for currents, bottom shear stress and carbon input, along with information on the distribution of habitat types, to explain the observed distribution patterns.

Possible changes according to climatic trends (including the North Atlantic Oscillation) will be analysed. Principally, a shift of distribution patterns of species (and communities) that benefit or suffer from warming in the North Sea south of the Dogger Bank, may be expected (see, e.g., Wieking & Kr�ncke, 2001).

Considering the ongoing intensive bottom trawl fisheries in large areas of the North Sea, investigations will be made of the relationship between the benthos (mainly large and long-lived and fragile species) and bottom trawling intensities.

Together with sediment distribution data, results from the epifaunal studies performed during the NSBP 2000 (either by trawling and dredging or by imaging) and morphological features (e.g., depth contours) identified from sea charts, a contribution will be made to the efforts to classify and describe habitats in the North Sea. This may serve as a basis for nature protection measures (e.g., through the EU �Habitats� Directive, OSPAR activities and as compensation measures for localized human impacts) and for spatial planning in general (see above). Since new data on the relevant communities and characterising species of specific habitats will be provided by the NSBP 2000, the task of habitat classification should therefore be greatly facilitated.

Through a combination of the intended analyses and publications it will also be possible to provide a strategic evaluation of the utility of our collaborative exercise for sea-wide quality assessments, including recommendations for the timing and coordination of any future work.