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Marine pollution mismanagement: Towards the precautionary concept
Marine Pollution Bulletin Mari,e t'olh/tion Bnlleti,. Vol. 17. No. 2. pp. 54-57. 1986 Printed in Great Britain
(tlt25-326X/86 S3.(t()+O.O() 1986 Pergamon Press Ltd.
Viewpoint is a column which allows authors to express their own opinions about current events.
Marine Pollution Mismanagement: Towards the Precautionary Concept VOLKERT DETHLEFSEN
Dr Dethlefsen is with the Federal Research Board of Fisheries, Hamburg, Federal Republic of Germany. He is head of the Toxicology Laboratory in Cuxhaven. His work is on biological effects of pollution in the North Sea and the Baltic, with the main interest in diseases and reproduction of fishes in relation to pollution. Despite the manyfoldness of concepts to manage marine pollution we are faced with increasing amounts of certain wastes dumped, for example, into some areas of the Oslo Convention (SACSA, 1980). Despite the existence of legal instruments to reduce or even ban dumping of sewage sludge at the US East Coast, we are threatened with the prospect of increasing amounts of wastes being dumped there. In the United States, the 1981 deadline for the cessation of ocean dumping has been successfully challenged. Swanson & Devine (1982) therefore foresee significant and long lasting repercussions for the reversal of the US ocean dumping policy. Schwabacher & Boiton (1982) call the revisiting of the 1981 deadline a tragedy for the oceans. In the light of increasing populations and increasing amounts of wastes to be disposed of, it is worth examining whether current practices in ocean dumping management provide the necessary degree of protection for the marine environment. In the following paper some of the reasons for this possibly conceptional failure will be investigated and some advice will be developed on how they could be overcome to ensure long-term protection of marine ecosystems. Dumping is in this paper understood as one example of sources of marine pollution, clearly having in mind that it is not the most important one in terms of quantities. It is also clear that the marine environment is only one compartment amongst many of the total ecosystem. Calls for the protection of coastal areas should not lead to a mere shifting of contamination into another environment.
Current Practice in Marine Pollution Management Concepts followed by the Oslo, Paris and Heisinki 54
Convention contain terms which still await exact definition. Some of these expression are either characterizing properties of the waste like 'trace' or 'significant amounts', 'rapidly converted', 'non-toxic', 'safety levels', or properties of the recipient like 'assimilative capacity', 'sensitive areas 'unreasonable degradation' or 'acceptable effects'. The implementation of regulatory measures depends upon exact and accepted definitions of these crucial terms. Since there is often no absolute definition, criteria for the acceptability of a dumping or its effects were in the past chosen rather arbitrarily. In this situation of uncertainty, when no firm grounds are available to refuse granting of applications for dumping permits, it is the almost automatic result that no reduction of the amounts of wastes dumped will be possible. In order to highlight some of the shortcomings of presently applied management techniques an approach developed by Preston (1980) will briefly be reviewed. Preston calls this approach an idealized framework for the derivation of standards and their application to the regulation of marine environmental quality and control of pollution. He clearly affirms the role of the ocean as recipient for man-made wastes. His concept allows the input of wastes until acceptable levels are surpassed and unacceptable changes occur. To achieve this aim, prior to dumping or introduction of the wastes a critical target has to be identified which will allow toxicological evaluation. By toxicity testing, body burden data will be established and the relation between these body burden data and accompanying toxicity will deliver the relevant thresholds. Through environmental monitoring on the basis of chemical residue monitoring it will then be recognized whether concentrations measured in the recipient are close to those that revealed toxicity in the critical target. The margins between laboratory-derived safety levels and those reached in the marine environ-
Volume 17/Number 2/February 1986
ment should be small and do not demand unrealistic margins of safety for every uncertainty. Since cost-benefit considerations play an important role in the Preston concept, it is one further aim to keep costs for measures to reduce waste loads as low as possible. This implies increasing pressure put on the marine environment. Preston, in his concept, sees weak points in experimentally-derived thresholds. They will have questionable relevance to real life environmental considerations. And he also questions the value of environmental monitoring being unlikely to demonstrate actual effects in unequivocal terms. The viability of this concept stands and falls with the ability to recognize subtle pollution-induced changes in the recipient. That means that monitoring techniques applied should be able to deliver results which allow this conclusion to be drawn. Most of the presently followed monitoring approaches are site by site and waste by waste analyses (Swanson & Devine, 1982). So it is doubtful whether they can produce the kind of information necessary to recognize pollution-induced changes in the ecosystem under consideration. All approaches presently followed concentrate on dumpsites not having the ability to disclose effects on ecosystems in a holistic way. It is therefore doubtful whether an approach as outlined by Preston provides the necessary degree of safety required for effective protection of marine ecosystems.
The Weakness of Threshold Considerations Since threshold considerations play an important role in the above-mentioned concept, two examples will be given to demonstrate discrepancies between experimentally derived standards and those effective in the marine environment. Reproduction success was reduced after experimental exposure of Pimephales promelas to PCBs when body burdens reached PCB levels of 92 000 ng g-t (Nebeker et al., 1974). Egg mortality was 50% in Baltic salmon when egg concentrations of PCB reached 17 000 ng g-l (Johansson et al., 1970). Results with Phoxinus phoxinus were similar, the effective ovary residue level of PCB was 15 000 ng g-~ (Bengtsson, 1980). In hatcheryreared rainbow trout eggs, high mortality was found at PCB gonad levels of 2800 ng g-t (Hogan & Brauhn, 1975). Von Westernhagen et al. (1981) showed reduced viable hatch of naturally occurring Baltic flounder at ovary levels of 120 ng g-~ PCB. In a second investigation a similar threshold could be demonstrated for Baltic herring (Hansen et aL, 1982). This example clearly shows what differences might be encountered in experimentally derived and real world thresholds. The danger of applying these extremely high thresholds with a narrow safety margin to a dumping situation is self-evident and needs no further explanation. In toxicity tests with cadmium, concentrations as high as 10 mg 1-l did not kill shore crabs (Carcinus rnaenas) after 1 week. As much as 2.5 mg 1-t did not reduce the growth of brown shrimp (Crangon crangon) and algae of the Fucus sp. On the other hand, sublethal effects were
demonstrated on primary producers inthe range of I gg Cd 1-1 seawater. This value is very close to cadmium levels actually found in coastal waters. The introduction of only trace amounts of cadmium would pose pressure on the sensitive primary producers. There would be no space for safety margins or safety factors (Sperling,
1983). Effects of Current Management Practices Present waste disposal practices are largely characterized by misjudgements of what is assumed to be the assimilative capacity of waste water recipients. Main reason for these misjudgements are lack of knowledge or lack of understanding of the complex waste ecosystem interactions in the recipient. The inability to link in situ effects to specific causes provokes thoughts that waste disposal is harmless and promotes readiness to enhance dumping. When, as in the case of the US east coast, the assimilative capacity of recipient waters is surpassed (Pearce, 1980) it is thought to be a solution to move dumping grounds from onshore to offshore locations (106 miles dump site). Swanson & Devine (1982) describe the progress in the development of the US sewage disposal strategies which began a century ago, when the waste was put on the streets, in the late 1800s it was put into the rivers, and in the 1920s the 12 n mile dump site was put into operations. This approach might thus be called the 'prolonged chimney approach" which has the immediate advantage to dilate the waste and take it out of sight. Lee & Ramster (1981) give details on the United Kingdom waste disposal practices which can be taken to demonstrate the 'multiple chimney approach' where the strategy of multiple inputs is chosen. This approach has the advantage of obscuring the effects of single dumpings by keeping each dumping or discharge small enough as not to produce unacceptable harm at the site of disposal. Coastal parallel currents (Kautsky, 1977) collect wastes from a multitude of dumping areas or discharge sites. This accumulation of waste by coastal parallel currents leads to a summation of waste effects which could not be attributed to any of the isolated inputs. It is obvious that current monitoring practices which concentrate on dumpsites or discharge locations will not allow one to discern other effects than drastic changes in water quality or organism communities. These changes will only be relatable to the waste input if some regional proximity between effects and assumed causes exists. As soon as changes of water quality or of organism communities occur at a distance from the waste input it is impossible to satisfactorily establish links between the two events. The monitoring techniques, however well developed, will not be able to separate effects existing throughout water masses, which due to their coastal parallel movements are already heavily preloaded. A general degradation of coastal ecosystems due to this excess of preloads will thus not be recognized. This statement not only relates to persistent substances, it also includes biodegradable material. 55
Marine Pollution Bulletin
Non-interpretable Changes in Ecosystems A striking example for our insufficient knowledge on complex ecosystem interactions is our inability to logically explain large scale changes in fish or plankton populations, fish disease occurrences or water quality (deoxygenation). Van de Kamp & Corten (1982) showed that fishery was a major cause of the decline of the Dogger Bank herring, but this population showed less resilience under heavy fishing pressure than neighbouring herring populations under similar conditions. This does suggest that apart from fisheries there was also a natural factor (sub-optimal hydrographic conditions) that counteracted the recovery of the population. Considerable decreases in the abundance of six species of fishes in the by-catch of German shrimpers during the last 28 years cannot be explained by meteorological, hydrographic or changes in intensity or structure of fisheries. The total biomass of fish by-catch remained fairly constant since three pelagic spawning fish species took over. It is discussed whether pollution of the respective areas might be the cause for these drastic changes (Tiews, 1983a, b). Only 50% of the variability in the annual means of plankton time series can be attributed to climatic changes (Radach, 1982). Other reasons such as possible influence of pollutants have to remain unregarded due to lack of knowledge, but are not unlikely to exist. While significant long-term changes in benthic communities in the Sylt area of the German Wadden Sea are interpreted to be due to fisheries (Riesen & Reise, 1982) no such conclusion was possible to explain recent phenomena in the lower Saxony Wadden Sea benthic communities (Michaelis, 1981), where pollution is speculated to be the prime cause. Reid (1984) in a recent paper provided data on longterm decreases in zooplankton species diversities and quantities in the North Sea. From 1948 to today zooplankton quantities decreased by two thirds and after 1970 severe decreases of North Sea fish stocks were documented. A sufficient explanation for this phenomenon is not available.
The Disease Controversy The recent upsurge of material on diseases of marine organisms in relation to pollution gave rise to a controversy still unresolved. While one part of the scientific community is convinced that increased disease rates in wide areas are to be interpreted as reaction to high pollution levels, others tend to believe that natural factors might be the cause. It has to be realized that this debate can be perpetuated without the chance to highlight cause-effect relationships in highly complex ecosystem interactions. To illustrate the absurdity of the arguments used to defend the hypothesis that factors other than pollution cause the increased disease prevalences, two papers on causes of blackspot diseases of crustaceans from British coastal waters will be cited. While one author claims that in the region of high fishing activity his crabs are ill because of 56
high frequencies of net injuries, the other author states for another crab in another area that his crabs are ill because they are not fished and can grow old enough to develop disease symptoms (Ayres & Edwards, 1982; Nottage, 1982). This example illustrates the existing uncertainty as to the interpretation of ecosystem changes. Concerning the debate on causes of diseases of marine fishes in the North Sea it can presently be observed that the fraction of scientists in favour of the pollution hypothesis is growing. While Danish, Dutch and German investigators believe they have positive material, British disease specialists especially are definitely rejecting this connection. They either claim that disease rates encountered were low during their studies, or when they found indications for increased disease rates in polluted areas they deem their material as too preliminary to draw final conclusions. Diseases of dab (Lirnanda limanda) are routinely monitored in the southern North Sea (Dethlefsen, 1984). Maximum prevalences of 50% of externally diseased dab were encountered during a recent sampling in May 1984 in wide parts of the southern North Sea. It might be disastrous to hope that the reason for these high disease rates could be natural. In the absence of our ability to link alarming largescale ecological dysfunctions to specific causes convincingly and in the presence of a multitude of indications for damages in organism communities of coastal areas current waste disposal strategies bear a suicidal character. In a situation of such uncertainty it would be an appropriate time to call a halt for the excessive use of coastal areas for the disposal of wastes.
Future Concepts Certainly one way to overcome this dilemma would be to intensify monitoring programmes or marine pollution research in general. This will at some future time lead to a better understanding of ecosystems. Long time-series will help to understand long-term changes in ecosystem structures. But the debate in the scientific community over the assimilative capacity of the oceans and whether the dumping of sludges and industrial wastes constitutes an unreasonable degradation can be expected to continue indefinitely (Schwabacher & BoRon, 1982). Successful marine waste disposal policy should therefore follow the precautionary concept (Rat von Sachverstiindigen fiir Umwelffragen, 1980). Environmental policy has to preclude distinct dangers for or dysfunctions of marine ecosytems. Its aim is to avoid these dangers by implementing fixed emission standards. It avoids the introduction of substances with potential negative effects even in the absence of accepted proof for their harmfulness. An increased concentration of harmful substances in seawater is avoided by the reduction of discharges containing even trace amounts of xenobiotics. The most stringent expression of the precautionary concept would be the obligation to all waste producers to apply most advanced avoidance techniques even if dangers or dis-
Volume 17/Number 2/February 1986
turbances in the marine environment have not yet been demonstrated. Fixed emission standards would be useless if they did not have reference points relating either to the water quality or to the organisms in the recipient waters. Emission standards would have to be followed by all polluters and the objection that under given circumstances neither a concrete danger exists nor is damage to a marine ecosystem likely to occur would not be legally relevant. One argument against the implementation of the precautionary concept is based on considerations of proportionality. In the view of its opponents, the precautionary concept will lead to zero discharges and would therefore mean an unnecessary and too expensive degree of overprotection. This is not necessarily so, because the application of best technical means for the setting of emission standards does include cost-benefit considerations. Only those reduction measures will be applicable which are technically and economically feasible. But the decision whether xenobiotic substances are introduced into the marine environment or not should not be based on considerations of the assimilative capacity of the recipient water but on technically available reduction options. The precautionary concept always has to be accompanied by intensive research on the effects of pollutants in the marine environment. Much of the controversy concerning the state of the health of parts of the North Sea is certainly due to lack of knowledge. An increase of knowledge could in the future lead to modifications of emission standards for substances which in the absence of proof for their harmlessness were set too stringently. This procedure clearly represents a reversal of today's practice. Its effect would be to reduce the pressure presently put on marine ecosystems by transferring it to the producer of wastes. The best example for the introduction of the precautionary principle was the prohibition of dumping in the area under the Helsinki Convention. The Baltic Sea was accepted to be a sensitive area and dumping was realized to present an uncalculable risk which, according to all signatories, should not be taken. A similar approach is now envisaged for the German Bight where sewage sludge dumping was terminated in 1980 (Dethlefsen, 1981). It is the expressed wish of the government of the Federal Republic of Germany that the dumping of wastes from titanium dioxide production will be ended in the second half of the 1980s. In both cases it was realized that it could not be excluded that the dumping creates negative effects to the ecosystem of the German Bight as a whole, although the scientific material presented in this context was not accepted unequivocally. Thereby it is planned to totally cease dumping in an ecologically-sensitive area. It is hoped that these examples for the implementa-
tion of the precautionary concept to protect marine ecosystems will soon find imitators in all North Sea riparian countries. We should realize that the protection of marine ecosystems is not only a task for our generation but should aim far ahead to secure future generations the use of reasonably unpolluted coastal waters. Ayres, P. A. & Edwards, E. (1982). Notes on the distribution of "black spot" shell disease in crustacean fisheries. Chem. Ecol. 1, 125-130. Bengtsson, B.-E. (1980). Long-term effects of PCB (Clophen A 50) on growth, reproduction and swimming performancc in thc minnow, Phoxinus phoxinus. Water Res. 14, 681-687. Dethlefsen, V. (1981). Hamburg beendet Kl~irschlammverklappung in der Nordsee. lnfnFischw. 28, 53-57. Dethlefsen, V. (1984). Discases in North Sea fishcs. Helgoliinder Meersunters 37,353-374. Hansen, P.-D., Rosenthal, H. & Westernhagen, H. von (19821. Chlorinated hydrocarbons and hatching success in spring spawners of Baltic herring. ICES C.M./E:31. Hogan, J. W. & Brauhn, J. L. (19751. Abnormal rainbow trout fry eggs containing high residues of a PCB (Aroclor 1242). Prog. Fish Cult. 37,229-293. Johansson, N., Jcnscn, S. & Ohlsson, M. (197(I). PCB-indication of effects on fish. PCB-Conference 1, Stockholm, September 29, 58-68 (from Olsson, 1978). Kamp, G, van de & Corten, A. (1982). A hypothesis for the decline of the Dogger Bank herring stock. ICES C.M./H:30. Kautsky, H. (1977). Str/Smungcn in dcr Nordscc. Umscha, 77, 672573. Lee, A. J. & Ramster, J. W. (1981). Atlas of the Sea around the British Isles. MAFF Direct, Fish. Res., Lowestoft, 67pp. Michaelis, H. (19811. Recent changes in the communities of thc Wadden Sea--natural phenomena or effects of pollution. Biol. Meddr, 4, 8795. Nebecker, A. V., Puglisi, E A. & DeFoe, D. L. (1974). Effect of polychlorinated biphenyl compounds on survival and reproduction of thc fathead minnow and flagfish. Trans. Am. Fish. Soc. 103, 562-568. Nottage, A. S. (19821. Shell disease of brown shrimp Crangon crangon (L.), and other marine crustacca from the Solway Firth. Chem. Ecol. 1,107-123. Pearce, J. B. (1980). Status of estuaries and coastal waters between Cape Hatteras and Maine; a review. ICES C.M./E:56. Preston, A. (19801. Standards and environmental criteria: An idealised framework for their derivation and application to the regulation of marine environmental quality and the control of pollution. ICES Annex 2 to ACMP-Report 1981,29-40. Radach, G. (19821. Variations in the plankton in relation to climate. ICES C.M./Gen:5, Mini Symp. Rat yon Sachverst~indigen fiir Umweltfragen (1980). Umwelt-probleme der Nordsee, Sondergtttachten Juni 1980. W. Kohlhammer, Stuttgart. Reid, P. C. (1984). Year-to-year changes in zooplankton biomass, fish yield and fish stock in the North Sea. ICES C.M./L:39. Riesen, W. & Reise, K. (1982). Macrobenthos of the subtidal Wadden Sea: revisited after 55 years. Helgoliinder Meeresunters 35,409-423. SACSA (1980). Trends in the amounts of wastes dumped in the Oslo Convention Area 1976-1979. Eighth meeting of the Standing Advisory Committee for Scientific Advice, Antibes 24-28 November 1980. SACSA VIII/4/4-E, 1-6. Schwabachcr, R. A. & Bolton, H. S. (1982). The tragedy of the oceans-the 1981 deadline revisited. Mar. POIlut. Pap. Oceans 1982, 11191124. Sperling, K.-R. (1983). Lethal and sublethal effects of cadmium on marine organisms--A critical discussion about "safety levels". Ecotoxicol. Environ. Safety 7, 521-524. Swanson, R. L. & Devine, M. (1982). Ocean dumping policy--a coming reversal? ICES C.M./E:32. Ticws, K. (1983a). Ober die Ver~inderungen im Auflreten yon Fischcn und Krcbsen im Beifang der Deutsehen Garnelenfischerci w~ihrend der Jahre 1954-1981. Arch. FischWiss. 34, 1-1156. Tiews, K. (1983b). On the changes of fish and crustacean stocks on thc German North Sea Coast during the years 1954-1981 and the hypothetical role of pollution as a causative factor. ICES C.M./E:16. Westernhagen, H. von, Rosenthal, H., Dethlefsen, V., Ernst, W., Harms, U. & Hanson, P.-D. (1981). Bioaccumulating substances and reproductive success in Baltic flounder Platichthys flesus. Aquatic Toxicol. I, 85-99.
57
(tlt25-326X/86 S3.(t()+O.O() 1986 Pergamon Press Ltd.
Viewpoint is a column which allows authors to express their own opinions about current events.
Marine Pollution Mismanagement: Towards the Precautionary Concept VOLKERT DETHLEFSEN
Dr Dethlefsen is with the Federal Research Board of Fisheries, Hamburg, Federal Republic of Germany. He is head of the Toxicology Laboratory in Cuxhaven. His work is on biological effects of pollution in the North Sea and the Baltic, with the main interest in diseases and reproduction of fishes in relation to pollution. Despite the manyfoldness of concepts to manage marine pollution we are faced with increasing amounts of certain wastes dumped, for example, into some areas of the Oslo Convention (SACSA, 1980). Despite the existence of legal instruments to reduce or even ban dumping of sewage sludge at the US East Coast, we are threatened with the prospect of increasing amounts of wastes being dumped there. In the United States, the 1981 deadline for the cessation of ocean dumping has been successfully challenged. Swanson & Devine (1982) therefore foresee significant and long lasting repercussions for the reversal of the US ocean dumping policy. Schwabacher & Boiton (1982) call the revisiting of the 1981 deadline a tragedy for the oceans. In the light of increasing populations and increasing amounts of wastes to be disposed of, it is worth examining whether current practices in ocean dumping management provide the necessary degree of protection for the marine environment. In the following paper some of the reasons for this possibly conceptional failure will be investigated and some advice will be developed on how they could be overcome to ensure long-term protection of marine ecosystems. Dumping is in this paper understood as one example of sources of marine pollution, clearly having in mind that it is not the most important one in terms of quantities. It is also clear that the marine environment is only one compartment amongst many of the total ecosystem. Calls for the protection of coastal areas should not lead to a mere shifting of contamination into another environment.
Current Practice in Marine Pollution Management Concepts followed by the Oslo, Paris and Heisinki 54
Convention contain terms which still await exact definition. Some of these expression are either characterizing properties of the waste like 'trace' or 'significant amounts', 'rapidly converted', 'non-toxic', 'safety levels', or properties of the recipient like 'assimilative capacity', 'sensitive areas 'unreasonable degradation' or 'acceptable effects'. The implementation of regulatory measures depends upon exact and accepted definitions of these crucial terms. Since there is often no absolute definition, criteria for the acceptability of a dumping or its effects were in the past chosen rather arbitrarily. In this situation of uncertainty, when no firm grounds are available to refuse granting of applications for dumping permits, it is the almost automatic result that no reduction of the amounts of wastes dumped will be possible. In order to highlight some of the shortcomings of presently applied management techniques an approach developed by Preston (1980) will briefly be reviewed. Preston calls this approach an idealized framework for the derivation of standards and their application to the regulation of marine environmental quality and control of pollution. He clearly affirms the role of the ocean as recipient for man-made wastes. His concept allows the input of wastes until acceptable levels are surpassed and unacceptable changes occur. To achieve this aim, prior to dumping or introduction of the wastes a critical target has to be identified which will allow toxicological evaluation. By toxicity testing, body burden data will be established and the relation between these body burden data and accompanying toxicity will deliver the relevant thresholds. Through environmental monitoring on the basis of chemical residue monitoring it will then be recognized whether concentrations measured in the recipient are close to those that revealed toxicity in the critical target. The margins between laboratory-derived safety levels and those reached in the marine environ-
Volume 17/Number 2/February 1986
ment should be small and do not demand unrealistic margins of safety for every uncertainty. Since cost-benefit considerations play an important role in the Preston concept, it is one further aim to keep costs for measures to reduce waste loads as low as possible. This implies increasing pressure put on the marine environment. Preston, in his concept, sees weak points in experimentally-derived thresholds. They will have questionable relevance to real life environmental considerations. And he also questions the value of environmental monitoring being unlikely to demonstrate actual effects in unequivocal terms. The viability of this concept stands and falls with the ability to recognize subtle pollution-induced changes in the recipient. That means that monitoring techniques applied should be able to deliver results which allow this conclusion to be drawn. Most of the presently followed monitoring approaches are site by site and waste by waste analyses (Swanson & Devine, 1982). So it is doubtful whether they can produce the kind of information necessary to recognize pollution-induced changes in the ecosystem under consideration. All approaches presently followed concentrate on dumpsites not having the ability to disclose effects on ecosystems in a holistic way. It is therefore doubtful whether an approach as outlined by Preston provides the necessary degree of safety required for effective protection of marine ecosystems.
The Weakness of Threshold Considerations Since threshold considerations play an important role in the above-mentioned concept, two examples will be given to demonstrate discrepancies between experimentally derived standards and those effective in the marine environment. Reproduction success was reduced after experimental exposure of Pimephales promelas to PCBs when body burdens reached PCB levels of 92 000 ng g-t (Nebeker et al., 1974). Egg mortality was 50% in Baltic salmon when egg concentrations of PCB reached 17 000 ng g-l (Johansson et al., 1970). Results with Phoxinus phoxinus were similar, the effective ovary residue level of PCB was 15 000 ng g-~ (Bengtsson, 1980). In hatcheryreared rainbow trout eggs, high mortality was found at PCB gonad levels of 2800 ng g-t (Hogan & Brauhn, 1975). Von Westernhagen et al. (1981) showed reduced viable hatch of naturally occurring Baltic flounder at ovary levels of 120 ng g-~ PCB. In a second investigation a similar threshold could be demonstrated for Baltic herring (Hansen et aL, 1982). This example clearly shows what differences might be encountered in experimentally derived and real world thresholds. The danger of applying these extremely high thresholds with a narrow safety margin to a dumping situation is self-evident and needs no further explanation. In toxicity tests with cadmium, concentrations as high as 10 mg 1-l did not kill shore crabs (Carcinus rnaenas) after 1 week. As much as 2.5 mg 1-t did not reduce the growth of brown shrimp (Crangon crangon) and algae of the Fucus sp. On the other hand, sublethal effects were
demonstrated on primary producers inthe range of I gg Cd 1-1 seawater. This value is very close to cadmium levels actually found in coastal waters. The introduction of only trace amounts of cadmium would pose pressure on the sensitive primary producers. There would be no space for safety margins or safety factors (Sperling,
1983). Effects of Current Management Practices Present waste disposal practices are largely characterized by misjudgements of what is assumed to be the assimilative capacity of waste water recipients. Main reason for these misjudgements are lack of knowledge or lack of understanding of the complex waste ecosystem interactions in the recipient. The inability to link in situ effects to specific causes provokes thoughts that waste disposal is harmless and promotes readiness to enhance dumping. When, as in the case of the US east coast, the assimilative capacity of recipient waters is surpassed (Pearce, 1980) it is thought to be a solution to move dumping grounds from onshore to offshore locations (106 miles dump site). Swanson & Devine (1982) describe the progress in the development of the US sewage disposal strategies which began a century ago, when the waste was put on the streets, in the late 1800s it was put into the rivers, and in the 1920s the 12 n mile dump site was put into operations. This approach might thus be called the 'prolonged chimney approach" which has the immediate advantage to dilate the waste and take it out of sight. Lee & Ramster (1981) give details on the United Kingdom waste disposal practices which can be taken to demonstrate the 'multiple chimney approach' where the strategy of multiple inputs is chosen. This approach has the advantage of obscuring the effects of single dumpings by keeping each dumping or discharge small enough as not to produce unacceptable harm at the site of disposal. Coastal parallel currents (Kautsky, 1977) collect wastes from a multitude of dumping areas or discharge sites. This accumulation of waste by coastal parallel currents leads to a summation of waste effects which could not be attributed to any of the isolated inputs. It is obvious that current monitoring practices which concentrate on dumpsites or discharge locations will not allow one to discern other effects than drastic changes in water quality or organism communities. These changes will only be relatable to the waste input if some regional proximity between effects and assumed causes exists. As soon as changes of water quality or of organism communities occur at a distance from the waste input it is impossible to satisfactorily establish links between the two events. The monitoring techniques, however well developed, will not be able to separate effects existing throughout water masses, which due to their coastal parallel movements are already heavily preloaded. A general degradation of coastal ecosystems due to this excess of preloads will thus not be recognized. This statement not only relates to persistent substances, it also includes biodegradable material. 55
Marine Pollution Bulletin
Non-interpretable Changes in Ecosystems A striking example for our insufficient knowledge on complex ecosystem interactions is our inability to logically explain large scale changes in fish or plankton populations, fish disease occurrences or water quality (deoxygenation). Van de Kamp & Corten (1982) showed that fishery was a major cause of the decline of the Dogger Bank herring, but this population showed less resilience under heavy fishing pressure than neighbouring herring populations under similar conditions. This does suggest that apart from fisheries there was also a natural factor (sub-optimal hydrographic conditions) that counteracted the recovery of the population. Considerable decreases in the abundance of six species of fishes in the by-catch of German shrimpers during the last 28 years cannot be explained by meteorological, hydrographic or changes in intensity or structure of fisheries. The total biomass of fish by-catch remained fairly constant since three pelagic spawning fish species took over. It is discussed whether pollution of the respective areas might be the cause for these drastic changes (Tiews, 1983a, b). Only 50% of the variability in the annual means of plankton time series can be attributed to climatic changes (Radach, 1982). Other reasons such as possible influence of pollutants have to remain unregarded due to lack of knowledge, but are not unlikely to exist. While significant long-term changes in benthic communities in the Sylt area of the German Wadden Sea are interpreted to be due to fisheries (Riesen & Reise, 1982) no such conclusion was possible to explain recent phenomena in the lower Saxony Wadden Sea benthic communities (Michaelis, 1981), where pollution is speculated to be the prime cause. Reid (1984) in a recent paper provided data on longterm decreases in zooplankton species diversities and quantities in the North Sea. From 1948 to today zooplankton quantities decreased by two thirds and after 1970 severe decreases of North Sea fish stocks were documented. A sufficient explanation for this phenomenon is not available.
The Disease Controversy The recent upsurge of material on diseases of marine organisms in relation to pollution gave rise to a controversy still unresolved. While one part of the scientific community is convinced that increased disease rates in wide areas are to be interpreted as reaction to high pollution levels, others tend to believe that natural factors might be the cause. It has to be realized that this debate can be perpetuated without the chance to highlight cause-effect relationships in highly complex ecosystem interactions. To illustrate the absurdity of the arguments used to defend the hypothesis that factors other than pollution cause the increased disease prevalences, two papers on causes of blackspot diseases of crustaceans from British coastal waters will be cited. While one author claims that in the region of high fishing activity his crabs are ill because of 56
high frequencies of net injuries, the other author states for another crab in another area that his crabs are ill because they are not fished and can grow old enough to develop disease symptoms (Ayres & Edwards, 1982; Nottage, 1982). This example illustrates the existing uncertainty as to the interpretation of ecosystem changes. Concerning the debate on causes of diseases of marine fishes in the North Sea it can presently be observed that the fraction of scientists in favour of the pollution hypothesis is growing. While Danish, Dutch and German investigators believe they have positive material, British disease specialists especially are definitely rejecting this connection. They either claim that disease rates encountered were low during their studies, or when they found indications for increased disease rates in polluted areas they deem their material as too preliminary to draw final conclusions. Diseases of dab (Lirnanda limanda) are routinely monitored in the southern North Sea (Dethlefsen, 1984). Maximum prevalences of 50% of externally diseased dab were encountered during a recent sampling in May 1984 in wide parts of the southern North Sea. It might be disastrous to hope that the reason for these high disease rates could be natural. In the absence of our ability to link alarming largescale ecological dysfunctions to specific causes convincingly and in the presence of a multitude of indications for damages in organism communities of coastal areas current waste disposal strategies bear a suicidal character. In a situation of such uncertainty it would be an appropriate time to call a halt for the excessive use of coastal areas for the disposal of wastes.
Future Concepts Certainly one way to overcome this dilemma would be to intensify monitoring programmes or marine pollution research in general. This will at some future time lead to a better understanding of ecosystems. Long time-series will help to understand long-term changes in ecosystem structures. But the debate in the scientific community over the assimilative capacity of the oceans and whether the dumping of sludges and industrial wastes constitutes an unreasonable degradation can be expected to continue indefinitely (Schwabacher & BoRon, 1982). Successful marine waste disposal policy should therefore follow the precautionary concept (Rat von Sachverstiindigen fiir Umwelffragen, 1980). Environmental policy has to preclude distinct dangers for or dysfunctions of marine ecosytems. Its aim is to avoid these dangers by implementing fixed emission standards. It avoids the introduction of substances with potential negative effects even in the absence of accepted proof for their harmfulness. An increased concentration of harmful substances in seawater is avoided by the reduction of discharges containing even trace amounts of xenobiotics. The most stringent expression of the precautionary concept would be the obligation to all waste producers to apply most advanced avoidance techniques even if dangers or dis-
Volume 17/Number 2/February 1986
turbances in the marine environment have not yet been demonstrated. Fixed emission standards would be useless if they did not have reference points relating either to the water quality or to the organisms in the recipient waters. Emission standards would have to be followed by all polluters and the objection that under given circumstances neither a concrete danger exists nor is damage to a marine ecosystem likely to occur would not be legally relevant. One argument against the implementation of the precautionary concept is based on considerations of proportionality. In the view of its opponents, the precautionary concept will lead to zero discharges and would therefore mean an unnecessary and too expensive degree of overprotection. This is not necessarily so, because the application of best technical means for the setting of emission standards does include cost-benefit considerations. Only those reduction measures will be applicable which are technically and economically feasible. But the decision whether xenobiotic substances are introduced into the marine environment or not should not be based on considerations of the assimilative capacity of the recipient water but on technically available reduction options. The precautionary concept always has to be accompanied by intensive research on the effects of pollutants in the marine environment. Much of the controversy concerning the state of the health of parts of the North Sea is certainly due to lack of knowledge. An increase of knowledge could in the future lead to modifications of emission standards for substances which in the absence of proof for their harmlessness were set too stringently. This procedure clearly represents a reversal of today's practice. Its effect would be to reduce the pressure presently put on marine ecosystems by transferring it to the producer of wastes. The best example for the introduction of the precautionary principle was the prohibition of dumping in the area under the Helsinki Convention. The Baltic Sea was accepted to be a sensitive area and dumping was realized to present an uncalculable risk which, according to all signatories, should not be taken. A similar approach is now envisaged for the German Bight where sewage sludge dumping was terminated in 1980 (Dethlefsen, 1981). It is the expressed wish of the government of the Federal Republic of Germany that the dumping of wastes from titanium dioxide production will be ended in the second half of the 1980s. In both cases it was realized that it could not be excluded that the dumping creates negative effects to the ecosystem of the German Bight as a whole, although the scientific material presented in this context was not accepted unequivocally. Thereby it is planned to totally cease dumping in an ecologically-sensitive area. It is hoped that these examples for the implementa-
tion of the precautionary concept to protect marine ecosystems will soon find imitators in all North Sea riparian countries. We should realize that the protection of marine ecosystems is not only a task for our generation but should aim far ahead to secure future generations the use of reasonably unpolluted coastal waters. Ayres, P. A. & Edwards, E. (1982). Notes on the distribution of "black spot" shell disease in crustacean fisheries. Chem. Ecol. 1, 125-130. Bengtsson, B.-E. (1980). Long-term effects of PCB (Clophen A 50) on growth, reproduction and swimming performancc in thc minnow, Phoxinus phoxinus. Water Res. 14, 681-687. Dethlefsen, V. (1981). Hamburg beendet Kl~irschlammverklappung in der Nordsee. lnfnFischw. 28, 53-57. Dethlefsen, V. (1984). Discases in North Sea fishcs. Helgoliinder Meersunters 37,353-374. Hansen, P.-D., Rosenthal, H. & Westernhagen, H. von (19821. Chlorinated hydrocarbons and hatching success in spring spawners of Baltic herring. ICES C.M./E:31. Hogan, J. W. & Brauhn, J. L. (19751. Abnormal rainbow trout fry eggs containing high residues of a PCB (Aroclor 1242). Prog. Fish Cult. 37,229-293. Johansson, N., Jcnscn, S. & Ohlsson, M. (197(I). PCB-indication of effects on fish. PCB-Conference 1, Stockholm, September 29, 58-68 (from Olsson, 1978). Kamp, G, van de & Corten, A. (1982). A hypothesis for the decline of the Dogger Bank herring stock. ICES C.M./H:30. Kautsky, H. (1977). Str/Smungcn in dcr Nordscc. Umscha, 77, 672573. Lee, A. J. & Ramster, J. W. (1981). Atlas of the Sea around the British Isles. MAFF Direct, Fish. Res., Lowestoft, 67pp. Michaelis, H. (19811. Recent changes in the communities of thc Wadden Sea--natural phenomena or effects of pollution. Biol. Meddr, 4, 8795. Nebecker, A. V., Puglisi, E A. & DeFoe, D. L. (1974). Effect of polychlorinated biphenyl compounds on survival and reproduction of thc fathead minnow and flagfish. Trans. Am. Fish. Soc. 103, 562-568. Nottage, A. S. (19821. Shell disease of brown shrimp Crangon crangon (L.), and other marine crustacca from the Solway Firth. Chem. Ecol. 1,107-123. Pearce, J. B. (1980). Status of estuaries and coastal waters between Cape Hatteras and Maine; a review. ICES C.M./E:56. Preston, A. (19801. Standards and environmental criteria: An idealised framework for their derivation and application to the regulation of marine environmental quality and the control of pollution. ICES Annex 2 to ACMP-Report 1981,29-40. Radach, G. (19821. Variations in the plankton in relation to climate. ICES C.M./Gen:5, Mini Symp. Rat yon Sachverst~indigen fiir Umweltfragen (1980). Umwelt-probleme der Nordsee, Sondergtttachten Juni 1980. W. Kohlhammer, Stuttgart. Reid, P. C. (1984). Year-to-year changes in zooplankton biomass, fish yield and fish stock in the North Sea. ICES C.M./L:39. Riesen, W. & Reise, K. (1982). Macrobenthos of the subtidal Wadden Sea: revisited after 55 years. Helgoliinder Meeresunters 35,409-423. SACSA (1980). Trends in the amounts of wastes dumped in the Oslo Convention Area 1976-1979. Eighth meeting of the Standing Advisory Committee for Scientific Advice, Antibes 24-28 November 1980. SACSA VIII/4/4-E, 1-6. Schwabachcr, R. A. & Bolton, H. S. (1982). The tragedy of the oceans-the 1981 deadline revisited. Mar. POIlut. Pap. Oceans 1982, 11191124. Sperling, K.-R. (1983). Lethal and sublethal effects of cadmium on marine organisms--A critical discussion about "safety levels". Ecotoxicol. Environ. Safety 7, 521-524. Swanson, R. L. & Devine, M. (1982). Ocean dumping policy--a coming reversal? ICES C.M./E:32. Ticws, K. (1983a). Ober die Ver~inderungen im Auflreten yon Fischcn und Krcbsen im Beifang der Deutsehen Garnelenfischerci w~ihrend der Jahre 1954-1981. Arch. FischWiss. 34, 1-1156. Tiews, K. (1983b). On the changes of fish and crustacean stocks on thc German North Sea Coast during the years 1954-1981 and the hypothetical role of pollution as a causative factor. ICES C.M./E:16. Westernhagen, H. von, Rosenthal, H., Dethlefsen, V., Ernst, W., Harms, U. & Hanson, P.-D. (1981). Bioaccumulating substances and reproductive success in Baltic flounder Platichthys flesus. Aquatic Toxicol. I, 85-99.
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