Contents - Previous - Next
This is the old United Nations University website. Visit the new site at http://unu.edu
Trajectory and regional dynamics
Compared with some of the other regions examined in this volume, the North Sea is not critical in any non-sustainable sense, in part because the warning signs have been heeded and preventive action duly taken. Nevertheless, the sea is experiencing stress, notably from the accumulation of toxic chemicals and nutrients emanating from the waste discharges of many highly industrialized economies. It receives the outflows of major continental rivers - notably the Elbe, the Rhine, the Meuse, and the Scheldt - into which vast quantities of industrial wastes have been pouring for many years. Just how contaminated the estuarine sediments of all these rivers are is unknown, although dredging of harbour deposits is now controlled where high accumulations of toxic chemicals are evident.
Driving forces, vulnerability, and social equity
The main driving forces for environmental transformation in the North Sea centre on institutional failure, coupled with the popular and politically driven desire for material progress and the pursuit of more profit. As is well known, "the environment" suffers in such circumstances, simply because of a combination of ignorance, cumulative outcomes between individual acts and collective behaviour, and misleading price signals that encourage wholesale externalities and disruption of environmental systems.
This is why this chapter has emphasized both the precautionary principle and international conventions and cross-border binding regulations. Both of these cardinal issues depend in turn on better environmental science, the fundamental building blocks of knowledge that can tell us how much the North Sea environment is changing, who or what is losing and gaining, and what will be the benefits of various courses of action. It is the cost-effectiveness of various economic incentives and other regulatory measures, coupled with the best data, precaution, and cross-border sharing, that will determine the trajectory towards environmental criticality in the North Sea.
Vulnerability should be viewed in terms of those ecosystems most in danger - the global cycles of carbon, nitrogen, sulphur, and phosphorus, the addition of synthetic chemicals into the cycles that are not geared to assimilate such foreign elements, and the disruption of the nutrient status of the south-eastern North Sea. In general, it is eutrophication and toxification on a wide scale that create vulnerability in environmental systems in the North Sea.
But vulnerability has another meaning, namely the impact of remedial measures on those who either are poor or live in peripheral economies highly dependent on depleted natural resources. For instance, some of the many fishing communities affected by depletion of fish stocks and the tough regulation of industry are diversifying into fish farming, but that too carries environmental burdens, many of which are not fully understood.
The issue of cost-effectiveness in environmental management is, therefore, the most revealing. In the absence of good data and a sound knowledge of cause and effect, it is tempting to respond to the obvious cases of crisis, even when it may prove unnecessarily expensive to act on apparent causes. The cases of nutrient removal and sludge dumping are illustrative. As costs mount and as the burden on industrial growth increases, the impact of rearranged prices and diverted economic opportunity falls on those who are poor or who live in areas in which the economy is already moribund. In the case of North Sea communities, this means the isolated zones of the shoreline and the bypassed economies of the poorer or depressed regions - in western Norway, southern Sweden, northern Holland, eastern Germany, upland France, and upland and north-western United Kingdom.
Social-equity considerations are not fully incorporated into the management options for the future of the North Sea. The emphasis lies in environmental restoration and protection. The distributional aspects of the costs and consequences of such action are rarely examined and certainly not in an emphatic manner. The next phase in the programme to safeguard the North Sea will, therefore, have to attend to cost-effectiveness studies and their distributional consequences. These are two areas where institutional failure has not yet sufficiently been addressed.
This chapter indicates that, despite the reductions in recent years, large deposits of wastes still find their way into the North Sea. As the land and river sources are reduced, the contribution from the air becomes more significant. Yet this source of contribution is not easy to regulate, in so far as the sources are fugitive, arising from thousands of diverse emissions. It has recently been discovered, for example, that a potentially large source of nitrogen addition to the open North Sea comes from ammonia released from animal manure stored in heaps in the Netherlands and the United Kingdom (Rendell et al. 1993). This is a function of an overproductive livestock industry that can no longer dispose of its own wastes onto the land. Similarly, it is likely that sizeable proportions of the volatile organic compounds come from minute emissions from motor cars and from certain chemical reactions, again deposited via atmospheric particulates (QSR 1993). Many of these compounds accumulate in sediment and in food pathways, magnified by concentration. The effects are more chronic than acute, but still poorly documented and understood. Indicators of possible trouble in store include:
Changes in the species composition of algal populations. These may include species that contain toxins for fish and mammals (though this has yet to be proven) and species that can convert sulphur in the sea into a volatile compound that oxidizes into acid rain (dimethyl sulphide). This biogenic sulphur source could account for up to 30 per cent of acidity in continental Europe.
A general increase in plankton bloom, indicated by the Continuous Plankton Recorder Survey, although available evidence suggests a climatic cause linked to the movement of nutrient-rich waters from the north-eastern Atlantic rather than anthropogenic factors. This could well prove to be a significant factor in deciding how extensively to regulate future emissions from sewage works. It is likely that the North Sea is becoming steadily eutrophified from entirely natural causes, and human-derived nutrient may be a problem only in shallow waters where the circulation is slow (e.g. the Waddensea and the German Bight). The Swedish bloom of Chrysocromulina in 1988 was also probably of natural origin, associated with a stable water column and warm, sun-filled summers.
The disappearance of seals almost to the point of extinction in the Waddensea during the 1970s, a tragedy linked to the increase in PCB contamination. The evidence here is strong - hence the concern to eliminate PCBs entirely.
The death of seals on a massive scale in 1988 in the southern North Sea and Waddensea owing to a viral disease known as phocine distemper. Up to 60 per cent of the seals died in one year. Currently studies are in process to determine if a link exists between pollution and the immune systems in mammals, although at present the cause is believed to be natural in origin and some historical material exists to suggest that similar "plagues" have occurred in the past.
The dying, apparently from hunger, of large numbers of sea birds. This may be due to the significant reduction of their fish stocks and may be linked to chlorinated substances and industrial fishing of sandeels. Sea birds also die as a result of oil pollution, though in terms of total population numbers these losses are not excessive.
The rising incidence of diseases in fish in the German Bight and off the Dutch coast. This is also being attributed to environmental pollution, though the precise cause is still not known. Nevertheless, this is now regarded as one of the more convincing signs of environmental stress. (Lancelot, Billen, and Barth 1990)
This is where the precautionary principle comes into play.
Despite the millions of pounds spent on research and modelling,
most of the cause-and-effect chains are not proven and may never
be conclusively linked in the period during which action should
be taken. We are beginning to witness the emergence of a more
people-friendly and environment-friendly precautionary science,
where ethical values permeate cost-benefit analyses, and where
wealthy and technologically innovative societies can afford to
invest in preventive action and cleanup. Indeed, in the European
Union as a whole, the environmental protection industry is worth
about US$180 billion annually a sizeable component of new
economic activity in the region. One consequence of this more
vernacular approach to science is the creation of
computer-modelled scenarios of how different policy measures
might create particular environmental futures. The Dutch
MANS project is not confined to the study of organic, nutrient, and toxic pathways. Nor is it merely a risk-assessment tool. It is explicitly designed to assist economists, lawyers, and policy makers to consider the possible consequences of various courses of action, including regulatory measures to guide industrial activity and consumer behaviour, so that sensitivity can be identified and given weight. The scope for "user-friendly" modelling is considerable.
Commons require collective governance. This is rarely possible to achieve in advance, especially if the alteration of environmental systems is uneven and the countries involved are at different stages of economic development. It is hardly surprising to report that the first moves to control pollution came only in the early 1970s when the problem had already become evident.
The regulation of pollution in the North Sea is largely the work of three important forums:
The Oslo Convention, which came into force in 1974, covers the regulation of marine pollution from dumping by ships and aircraft. The Convention established the Oslo Commission, which consists of representatives of all 14 West European maritime states.
The Paris Convention, which covers the regulation of marine pollution from land-based sources, came into force in 1978. Again, the maritime states are involved in the Paris Commission, although their jurisdiction extends to freshwater sources as well as shore sources. The European Union is a member of this commission. The commission has broad powers for control, including discharge limits, environmental quality standards, and regulations covering the use of substances and products.
The International North Sea Conference (INSC) is not a standing body, but a meeting of environmental ministers of the eight basin states. This is essentially a political initiative that sets the policy framework for national action and specific implementation by the two commissions.
The two commissions, referred to as OSPARCOM, meet annually and tend to act on the advice of expert panels that are vetted by standing scientific and technical bodies. In this sense OSPARCOM provides the regulatory buttress for the INSC proposals, adding legal support for politically inspired positions. The INSC meetings are not in themselves very detailed, so an important measure of scientific and regulatory symbiosis links the two modes of management.
The creation of the North Sea Conferences was a result of a high level scientific study sponsored by the West German parliament in
1980 (RSU 1980). This brought together for the first time the known scientific information regarding the North Sea and pointed out the gaps in understanding. Above all, it showed clearly that no country acting alone could solve the environmental problems of the North Sea. Such recognition, coming at a time when Europe was becoming politically sensitive to environmental issues, prompted the then most politically powerful country of all, West Germany, to convene the first conference in Bremen in 1984. The North Sea Conference declarations and the two commissions together find the necessary legal, scientific, and economic bonds to ensure that commitments are made. Thus, the commissions provide the necessary legal and scientific framework to convey ministerial intent into lasting agreement. Following the 1987 London meeting of the conference, the commissions, in league with the International Council for the Exploration of the Seas, established a North Sea Task Force that produced a second Quality Status Report (QSR 1993) for a joint meeting of the conference and the commissions in 1993. Guiding the conference is a Political Working Group that sets the political framework for key decisions. These include the following actions:
strict control on all "blacklist" chemicals, notably mercury, cadmium, organotin compounds, and new synthetic substances (associated with organochlorine products);
setting precise targets of all "grey list" substances, including the persistent halogen compounds, PACs (polychlorinated aliphatic hydrocarbons), and dioxins;
the phasing out, by 1999, of all PCBs entering the North Sea;
the cessation of sewage sludge dumping by 1998;
the elimination of all incineration at sea by 1993;
the cessation of the practice of dumping oil-based muds from offshore platforms;
the establishment of best available technology for 10 key process industries aimed at process-based discharge standards;
a review of all nutrient sources with a view to substantial elimination (up to one-half) by 1995 for eastern coastal areas;
a substantial reduction in pesticides by 1993;
the cessation of all industrial waste disposal by 1992;
a reduction of 50 per cent in inputs from estuaries or rivers, and from the air of specified substances, by 1995 (or 1999 at latest);
a 70 per cent reduction in all substances that cause a major threat to the marine environment, including dioxins, mercury, cadmium, and lead;
the application of the best available techniques not entailing excessive costs (a variant of the precautionary principle) to all "red list" substances via the implementation of integrated pollution control applied at source in a total management frame of reference (Gibson and Churchill 1990).
All these decisions are set in a framework of both political and scientific backing. The commissions provide the independent scientific authority, whereas the conferences establish the political direction. This includes the prior justification procedure that prohibits any dumping at sea unless no practicable alternative can be found on land and the materials pose no risk as determined by a competent international scientific organization.
This raises the question of whether a single body, along the lines of the Helsinki Commission for the maintenance of peace and security throughout Europe, should be responsible for the North Sea. In essence there is no device that has supranational power both politically and legally that is not forever thwarted by nation-state manoeuvres. In pragmatic terms the current arrangements work well as long as attitudes shift in favour of tough measures and the collective political will is supported by a transfer of knowledge, predictive modelling techniques, technology, and management skills from the advanced to the less advanced nations.
The North Sea is unusual in that every country is sufficiently wealthy and environmentally motivated to reach a surprising degree of common agreement, albeit belatedly. This is not the case for the Mediterranean Sea, where even more formidable problems of resource depletion and environmental degradation abound, yet where the economic circumstances of the most afflicted countries encourage even greater abuse of their precious environmental assets (Haas 1990).
There is no easy solution to such dilemmas. At the heart of the matter is the need to establish a meaningful community of common futures. This needs at the very least:
adequate monitoring and gathering of comprehensive scientific information;
sound modelling schemes that can be made policy relevant by simulating outcomes of environmental states based on the proposed impact of possible policy measures. Such models may be used in the classroom as much as in the legislative chamber;
formal links between political structures, scientific task forces, and the framework for implementing international environmental law;
agreements to transfer critical resource needs to countries yet unable to establish their own environmental protection programmes. These transfers should be linked to policy performance and policy commitments and delivered through competent international institutions, not by bilateral arrangements;
commitments to a common protection strategy based on ambient quality standards, emission controls related to best available technology, the application of cost-benefit models related to the most practicable environmental option studies, and the application of the precautionary principle;
regional compacts to establish localized agreements on management measures to overcome small-scale, yet international problems. These could be based on the principles of critical environmental load based on indicators of environmental sensitivity, and applying the mechanisms of strict liability, best technology, and performance audits.
Restoring an area on a trajectory to endangerment to a semblance of normalcy requires a colossal shift of political attention, resources, and decision-making structures, and prolonged commitment. To bring even more critical regions, such as the Aral Sea (chap. 3) and the Nepal middle mountains (chap. 4), to the bare bones of habitability will require the assistance of the whole globe. It is very doubtful indeed that salvation measures for severe situations can be effectively implemented at the regional level.
This chapter has gone through a number of drafts. The authors are particularly indebted to Henry Cleery of the Department of the Environment in London, and to Albert Weale, Seeseana Bateman, Andrea Williams, and Alastair Grant of the University of East Anglia. The usual disclaimers apply.
Aalst, R. M., van. 1988. Input from the atmosphere. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner, 275-283. Berlin: Springer-Verlag.
Aalst, R. M. van, J. H. Duyzer, and C. Veldt. 1983. Atmospheric deposition of lead and cadmium in the southern part of the North Sea: Emissions and preliminary model calculations. Report R 83/222. Delft: TNO.
Andersen, S. H. 1984. Bycatches of the harbour porpoise (Phocaena phocaena) in Danish fisheries (1980-1981) and evidence for overexploitation. Report of the International Whaling Commission 34: 745-749.
Becker, Gerd Axel. 1987. Die Auswirkungen des Kenkraftwerkunfalles von Tschernobyl auf Nord- und Ostsee. Meereskundliche Beobachtungen und Ergebnisse no. 62. Hamburg: Deutsches Hydrographisches Institut.
Bedborough, D., and R. A. A. Blackman. 1986. A survey of inputs to the North Sea resulting from oil and gas development. Philosophical Transactions of the Royal Society (London), Series B 316: 495-509.
Bellamy, D. J., P. Edwards, M. J. D. Hirons, D. J. Jones, and P. R. Evans. 1973. Resources of the North Sea and some interactions. In North Sea science, ed. Edward D. Goldberg, 383-399. Cambridge, MA: MIT Press.
Boehmer-Christiansen, Sonja. 1990. Environmental quality objectives versus uniform emission standards. In The North Sea: Perspectives on regional environmental co-operation, ed. David Freestone and Ton IJlstra, 139-149. Special issue of the International Journal of Estuarine and Coastal Law. London: Graham & Trotman/ Martinus Nijhoff.
BNF (British Nuclear Fuels). 1985. SIXEP, site ion exchange effluent plant. Risley, Warrington, England: Information Services, BNF.
BP (British Petroleum Company). 1991. BP statistical review of world energy. London: BP.
Byrne, C. D. 1989. Community water quality policy for the nineties.. Luxembourg: Commission of the European Communities.
Camphysen, C. J., and J. van Dijk. 1983. See-en kustvogels fangs de Nederlandse kust, 1974-1979 (English summary). Limosa 57: 81-230.
Compaan, H. 1988. Waste incineration at sea. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner, 257-274. Berlin: Springer-Verlag.
Cotter, J. 1988. Sea disposal-licensing and monitoring. In Chemistry and Industry 2 May: 290-293.
Coull, lames R. 1988. The North Sea herring fishery in the twentieth century. Ocean Yearbook 7: 115-131.
De Wolf, P., and J. J. Zijlstra. 1988. The ecosystem. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner, 118-151. Berlin: Springer-Verlag.
Dicks, B., T. Bakke, and I. M. T. Dixon. 1988. Oil exploration and production and oil spills. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner, 524-537. Berlin: Springer-Verlag.
Driel, W. van, H. N. Kerdijk, and W. Salomons. 1984. Use and disposal of contaminated dredged material. Land and Water International 53: 13-18.
Eisma, D. 1986. The North Sea: An overview. In Reasons for concern: Proceedings of the 2nd North Sea Seminar '86, vol. 1, ed. E. Hey and G. Peet, 11-28. Amsterdam: Werkgroep Noordzee.
Evans, P. R. 1973. Avian resources of the North Sea. In North Sea science, ed. Edward D. Goldberg, 400-412. Cambridge, MA: MIT Press.
FAO (Food and Agriculture Organization of the United Nations). 1978. Mammals in the sea, vol. 1. FAO Fisheries Series no. 5. Rome: FAO.
Financial Times. 1990a. Pile of stinking fish fails to spur EC to accept quotas. 20 December: 32.
Financial Times. 1990b. Fishing quota reduction agreed. 21 December: 30.
Förstner Ulrich, and Wim Salomons. 1988. Dredged materials. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner 225-245. Berlin: Springer-Verlag.
Garrod, D. M., and J. M. Colebrook. 1978. Biological effects of variability in the North Atlantic ocean. Rapports et procès-verbaux des rèunions/Conseil international pour l'exploration de la mer 172: 128-144.
Gibson, John, and Robin R. Churchill. 1990. Problems of implementation of the North Sea declarations: A case study of the United Kingdom. In The North Sea: Perspectives on regional economic co-operation, ed. David Freestone and Ton IJIstra, 66-79. Special issue of the International Journal of Estuarine and Coastal Law. London: Graham & Trotman/Martinus Nijhoff.
Glover, R. S. 1967. The continuous plankton recorder survey of the North Atlantic. Symposia of the Zoological Society of London 19:189-210.
Glover, R. S., A. Robinson, and J. M. Colebrook. 1974. Marine biological surveyance. Environmental Change 2: 395-402.
Grahl-Nielsen, O. 1978. The Ekofisk Bravo blow-out: Petroleum hydrocarbons in the sea. In The Proceedings of the Conference on Assessment of Ecological Impacts of Oil Spills, 14-17 June 1978, Keystone, Colorado, 476-487. Arlington, VA: American Institute of Biological Physics.
Haas, Peter M. 1990. Saving the Mediterranean: The politics of international environmental cooperation. New York: Columbia University Press.
Hock, C. van den, W. Admiraal, F. Colijn, and V. N. de Jonge. 1979. The role of algae and seagrasses in the ecosystems of the Wadden Sea: A review. In Flora and vegetation of the Wadden Sea: Final Report, ed. W. J. Wolff, 9-118. Wadden Sea Working Group Report 3. Rotterdam: Balkema.
Höhn, R. 1973. On the climatology of the North Sea. In North Sea science, ed. Edward D. Goldberg, 183-236. Cambridge, MA: MIT Press.
INER (International Environment Reporter). 1993a. Tanker grounded, spilling crude oil off Scotland's Shetland Isles. INER Current Reports 16, no. 1 (13 January): 5-6.
INER (International Environment Reporter). 1993b. Ministers agree to push through unified policies to curb oil pollution. INER Current Reports 16, no. 2 (27 January): 37-38.
INSC (International North Sea Conference). 1990. Conference proceedings. The Hague: INSC.
IQSR, 1990. Interim report on the quality status of the North Sea. The Hague: Netherlands Ministry of Transport and Public Works.
Jaarsveld, J. A. van, R. M. van Aalst, and D. Onderdelinden. 1986. Deposition of metals from the atmosphere into the North Sea. Report RIVM 842015002. Bilthoven, the Netherlands: Rijksinstituut voor Volksgezondheid en Milieuhygiene (RIVM)
Joffre, Sylvain M. 1985. The structure of the marine atmospheric boundary layer: A review from the point of view of diffusivity, transport and deposition process. Technical Report 29. Helsinki: Finnish Meteorological Institute.
Kates, Robert W., B. L. Turner II, and William C. Clark. 1990. The great transformation. In The Earth as transformed by human action: Global and regional changes in the biosphere over the past 300 years, ed. B. L. Turner II, William C. Clark, Robert W. Kates, Jessica T. Mathews, and William B. Meyer, 1-17. Cambridge: Cambridge University Press with Clark University.
Kautsky, H. 1988. Radioactive substances. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner 390-399. Berlin: Springer-Verlag.
Kemp, Alexander G. 1990. An assessment of the North Sea oil and gas policies: Twenty five years on. Energy Policy 18: 599-623.
Lancelot, C., G. Billen, and H. Barth, eds. 1990. Eutrophication and algal blooms in North Sea coastal zones, the Baltic and adjacent areas: Prediction and assessment of preventive actions: Proceedings of a workshop organised by the Commission of the European Communities Environmental R and D Programme, in Brussels, 26-28 October 1989. Water Pollution Research Report no. 12. Brussels: Commission of the European Communities.
Lee, A. J. 1988. The North Sea: Setting the scene. In Environmental protection of the North Sea, ed. P. J. Newman and A. R. Agg, 1-24. Oxford: Heinemann.
MacGarvin, Malcolm. 1990. The North Sea. London: Collins & Brown.
Morley, George. 1968. The North Sea. London: Frederick Muller.
Parker, M. 1988. Sewage sludge disposal in the North Sea. In Pollution of the North Sea: An assessment, ed. Wim Salomons, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner 246-256. Berlin: Springer-Verlag.
QSR (Quality Status Report). 1987. Second international conference on the protection of the North Sea: A report by the Scientific and Technical working group. London: HMSO.
QSR (Quality Status Report). 1993. Quality status report for the North Sea. London: HMSO.
Radach, G. 1982. Dynamic interactions between lower tropic levels of the marine food web in relation to the physical environment during the Fladen Ground experiment. Netherlands Journal of Sea Research 16: 231-246.
Read, A. D., and R. A. A. Blackman. 1980. Oily discharges from North Sea installations: A perspective. Marine Pollution Bulletin 11: 44-77.
Reid, P. C. 1978. Continuous plankton records: Large-scale changes in the abundance of phytoplankton in the North Sea from 1958-1973. Rapports et procès-verbaux réunions/Conseil international pour l'exploration de la mer 172: 384-389.
Reid, P. C., and T. D. Budd. 1979. Plankton and environment in the North Sea in the period 1948-1977. International Council for the Exploration of the Sea (ICES) CM 1979: L26.
Rendell, A. R., C. J. Ottley, T. D. Jickells, and R. Harrison. 1993. The atmospheric input of nitrogen to the North Sea. Tellus 45: 53-63.
Rose, Chris, ed. 1990. Why Britain remains "the dirty man of Europe": A report for Greenpeace by Media Natural London: Greenpeace.
RSU (Rat fur Sachverständigung fur Umweltfragen). 1980. Umweltprobleme der Nordsee: Sondergutachten Juni 1980. Stuttgart: Verlag W. Kohlhammer.
Salomons, Wim, Brian L. Bayne, Egbert K. Duursma, and Ulrich Förstner eds. 1988. Pollution of the North Sea: An assessment. Berlin: Springer-Verlag.
Sibthorp, M., ed. 1975. The North Sea: Challenge and opportunity: Report of a study group of the Davis Davies Memorial Institute of international Studies. London: Europa for the Institute.
Summers, C. F., W. N. Bonner, and J. van Haaften. 1978. Changes in the seal populations in the North Sea. Rapports et procès-verbaux des réunions/Conseil international pour l'exploratron de la mer 172: 278-285.
Symes, David. 1990. North Sea fisheries: Trends and management issues. In The North Sea: Perspectives on regional environmental co-operation, ed. David Freestone and Ton IJlstra, 271-288. Special issue of the International Journal of Estuarine and Coastal Law. London: Graham & Trotman/Martinus Nijhoff.
Tiews, K. 1978. The German industrial fisheries in the North Sea and their by-catches. Rapports et procès-verbaux des réunions/Conseil international pour l'exploration de la mer 172: 230-238.
UK Digest of Energy Statistics. 1991- (annual). London: HMSO.
US Department of State. 1969. Sovereignty of the sea. Geographic Bulletin 3: 1-5.
Verweij, J., and W. J. Wolff. 1982. The common or harbour porpoise (Phocaena phocaena), the bottlenose dolphin (Tursiops truncatus). In Marine mammals of the Wadden Sea, ed. Peter J. H. Reijnders and Wim J. Wolff, 51-64. Rotterdam: Balkema.
Vincent, A. J., and R. F. Critchely. 1982. A review of sewage sludge treatment and disposal in Europe. Water Research Centre Medmenham Report 442-M: 31.
Wheeler, Alwyne C. 1969. The fishes of the British Isles and northwest Europe. London: Macmillan.
Wheeler, Alwyne C. 1978. Key to the fisheries of northern Europe. London: Frederick Warne.
Whitaker's almanac. 1986. London: Whitaker.
World Bank. 1992. World development report 1992: Development and the environment. Oxford: Oxford University Press for the World Bank.
Zijlstra, J. J. 1988. The North Sea ecosystem. In Ecosystems of the world, ed. D. W. Goodall. Part 27, Ecosystems of the continental shelves, ed. H. Postma and J. J. Zijlstra, 231-278. Amsterdam: Elsevier.
Zwiep, Karel van den 1990. The Wadden Sea: A yardstick for a clean North Sea. In The North Sea: Perspectives on regional environmental co-operation, ed. David Freestone and Ton IJlstra, 201-212. Special issue of the International Journal of Estuarine and Coastal Law. London: Graham & Trotman/Martinus Nijhoff.
Contents - Previous - Next