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Danish marine oil pollution policy
Marine Pollution Bulletin, Vol, 10, pp. 251)-253 ~) Pergamon Press Ltd. 1979. Printed in Great Britain.
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Viewpoint is a column which allows authors to express their own opinions about current events.
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Danish Marine Oil Pollution Policy HANS ULRIK RIISGP, RD
Dr Rissgiird is Project Leader at the Kavalergarden Marine Pollution Laboratory and is concerned chiefly with the sub-lethal effects of pollutants on marine organisms. In this article he discusses the biological basis for the Danish marine oil pollution policy which has recently been revised. In the period 1973-1977 more than 400 oil spills, most of them small, were reported to the National Agency of Environmental Protection (NAEP), Denmark. The total oil transport through Danish territorial waters is now about 45m tons per year, not including an unknown amount of oil/oil products transported on Soviet Russian ships, and, further, tankers up to 130 000 tons dwt, now sail through the heavily trafficked Great Belt which connects the Baltic Sea and the Kattegat. Fear of the obvious possibility of large oil spills in Danish waters was strengthened after the Ekofisk 'Bravo' blow-out in the North Sea, April 1977, and the running aground of several tankers in the narrow Danish straits in 1977-78. Therefore, Danish marine oil policy has recently been revised, and in November 1978 a report on the biological effects of oil pollution in the marine environment was published by NAEP. The present paper gives a short review of the main points and the conclusions of this report, which forms the basis of Danish marine oil pollution policy.
Open Marine Areas A short time after an oil spill, a thin layer of oil a few rniilimetres in thickness will usually cover a relatively large area on the sea surface. While the oil is floating on the water, it is physically and chemically transformed ('weathered'), mainly due to evaporation. More than 50°70 of a light crude oil can evaporate within the first week after a spill (I.C.E.S., 1977). However, a small fraction of the oil is always dissolved in the water. As the most volatile hydrocarbons, especially the atomatic compounds, constitute both the most soluble and the most toxic fraction of oil, weathering processes protect the marine organisms against being exposed to dissolved harmful hydrocarbons. Depending on the vertical mixing in the water column, a certain concentration of hydrocarbons can always be found in the water some time after an oil spill (Mackie et al., 1978). In open marine areas it is, therefore, primarily plankton organisms and fry near the sea surface which take up oil and are injured. Depending on wave action, oil is also emulsified in the water as small particles in the size range of 5--40/an. These oil particles are retained and eaten as plankton particles by suspension feeding copepods (Conover, 1971) and mussels, through which the oil is brought into the marine food-webs and distributed throughout the entire biological system. 250
Generally, the biological damage due to an uncombatted oil spill in an open marine area is limited, when injuries to seabirds are not taken into account. This is partly due to the weathering processes, the tremendous dissolving capacity of the sea and the large regenerative ability of the marine biological system.
Shallow Marine Waters Shallow waters with a relatively small volume of water are generally very sensitive to oil pollution, and large, oil spills can result in extensive biological damage. The immediate consequences are often mass killing of fish and invertebrates (O'Sullivan, 1978), and oil pollution in shallow waters can give rise to chronic effects and an oily taste in fish and mussels up to several years after an oil spill, if oil is trapped in the sediments under anaerobic conditions (Sanders, 1977). The Danish shoreline, with its many fjords and coves, is extremely long and the relatively large areas with shallow waters are very productive in the summertime. The most important primary producers are diatoms and macrophytes, which give rise to a rich production of polychaetes, gastropods and bivalves that are the most important prey organisms for fry and young fish. A larger oil spill in these areas may therefore result in severe ecological damage and destruction of important edible fish and mussels.
Sublethal Effects of Oil Petroleum hydrocarbons are taken up in marine animals by assimilation of oil-contaminated food in the intestine and by absorption of hydrocarbons through the outer surfaces. Absorption of hydrocarbons is a rapid process depending on the oil concentration in the surrounding water (Stegeman & Teal, 1973; Fossato & Canzonier, 1976). The toxicity of petroleum hydrocarbons depends on their chemical and physiological properties. The lipophilic low molecular hydrocarbons are particularly toxic: they are easily taken up in the lipid-rich cell membranes through which they diffuse, damaging important membrane functions and intracellular biochemical processes. Chemically reactive hydrocarbons, especially aromatic compounds, can thus give rise to severe injury to marine organisms.
Volume 10/Number 9/September 1979
The first signs of toxic effects of oil on fish and invertebrates are reduced reaction time, muscle control failure, and behavioural disorders. These effects can be classified as narcotic, possibly because the impulse conductivity of the nerves is inhibited by petroleum hydrocarbons in the membrane of the nerve cells (Seeman, 1972). If oil-contaminated organisms are transferred to clean water, most of the hydrocarbons will soon be released and only smaller amounts, possibly concentrated in lipid depots, are released very slowly (Stegemann & Teal, 1973). Many acute injuries are reversible and the normal biological functions can be reestablished in clean water if the petroleum hydrocarbons are released before they have caused permanent damage (Percy & Mullin, 1977). Chronic effects can arise when aromatic hydrocarbons, instead of being hydroxylated by the cells' normal detoxificationsystem, are transformed into more poisonous intermediate products. These products may be strongly toxic and possibly damage the genetic information mechanism. As genetic injuries can result in cancer, it is perhaps these reactive intermediate products that are the carcinogenic components in oil (Longwell, 1977; Barry & Yevich, 1975). Other chronic injuries caused by oil pollution are reduced growth (Dow, 1975) and fertility (Lind6n, 1976). These effects are due to physiological stress because the energy consumption for maintaining normal cellular, and with that, physiological functions can be raised significantly so that a smaller amount of food energy can be spent on these purposes. Serious chronic injuries can also be due to sublethal effects on the early ontogenetic stages which are generally much more sensitive than the adult organism (Well, 1972). Finally, oil can inhibit the fertilization of marine organisms that spawn their sex products in the water (Renzoni, 1975).
Microbiological Decomposition of Oil After an oil spill, it is possible to demonstrate an increase in the number of microorganisms, mainly bacteria, which are able to metabolize oil. No single organism is able to decompose all the different hydrocarbons in crude oil, and the temperature and the amount of nutrients influence the rate of decomposition (Tagger et al., 1976). The chemical composition of the oil is an important factor in the microbiological breakdown because the different oil components have differing degrees of persistence, solubility and toxicity to the microorganisms. A very important factor in the microbiological breakdown is the molecular configuration of the hydrocarbons: alkanes are more degradable than aromatic or cycloalkane compounds, and long carbon chains are broken down more easily than branched compounds (Floodgate, 1972). The microbiological decomposition of oil is mainly located at the water/oil interface, and a thin oil film is, therefore, broken down faster than a thick oil slick on the water surface. Two types of oil emulsions can, depending on the circumstances (wave action, use of dispersing chemicals, etc.), be formed after an oil spill: a. oil-in-water emulsion, and b. water-in-oil emulsion ('chocolate mousse'). The difference in decomposition rate of the two emulsions is large. The oil-in-water emulsion, where the oil is mixed in the water as small oil drops, is broken down much more easily than the more compact water-in-oil emulsion, which
often ends up as 'pelagic tar' when the oxygen and the nutrients in the off-bound water are used up by the microorganisms (Butler, 1975). The amount of oxygen in the sea water is possibly never a limiting factor for the decomposition of oil. This contrasts with the situation in marine sediments. In shallow waters the amount of inorganic particles in the water is often high, especially in stormy weather. If oil adsorb to these particles, they may sink to the bottom and the oil is eventually trapped in the sediment. Oil in the sediment will at first stimulate the growth of oil-degrading bacteria, but as the oxygen is used by the microorganisms in the combustion of the organic hydrocarbons, all the oxygen will soon be used up (Johnston, 1970). Oil in the sediment is often degraded extremely slowly (Blumer & Sass, 1972), not only due to anerobic conditions, but the protection against photo-chemical breakdown, frequently in combination with depletion of nutrients, can inhibit the decomposition. Thus, shallow waters with muddy and anaerobic sediments are especially vulnerable to oil spills because oil in the sediment can give rise to severe chronic oil pollution over a long period (Cretneay et al., 1978; Keizer et ai., 1978; Vleet &Quinn, 1978).
Damage of Oil on Seabirds Oil pollution in Danish waters kills thousands of seabirds every year, mainly ducks but sometimes also a considerable number of other web-footed birds. Above all, oil pollution has attracted the attention of the public through extensive damage to seabirds, as was the case twice in 1972 where relatively small amounts of oil from unknown ships resulted in seabird disasters where more than 30 000 birds in each case died from exposure to oil (Joensen, 1973). The plumage of sea birds is waterproof but oil absorbing. When a seabird comes in contact with oil, the waterproof effect is lost and the water forces its way into the normal heat isolating layer of the plumage. In cold water, a 2-3 cm~spot without heat isolation on the breast of a duck will soon kill the bird, while contamination of the plumage in warmer water can weigh down the bird so much that swimming and flying are made impossible, finally leading to the death of the bird. Seabirds may also die from injuries to inner organs caused by eating oil-contaminated food or by cleaning the oil-polluted plumage (Clark, 1968). The damage to inner organs are multitudinous and may result in anaemia, degeneration of the liver, lung inflammation or injuries to the kidneys or the nervous system (Hartnung & Hunt, 1966; Goethe, 1968). The overall damage ofoil to seabirds is often so pronounced that even moderately contaminated birds have only a small chance to survive, and human efforts to clean oiled birds have never been very successful (Clark, 1978). Oil contamination can also have injurious effects on the hormone regulation, leading to reduced fertilitywhile oil on the eggs can result in embryonic damage (Albers & Szaro, 1978). Deaths of seabirds due to oil pollution in Danish waters are mainly registered from October to April, presumably due to the high sensitivity of oiled birds to cold water and because enormous concentrations of many species of seabirds stay in these areas during the winter (Joensen & Hansen, 1977). A considerable part of the North-West European population of common eiders have their winter 251
MarinePollutionBulletin quarters in Danish waters, especially in the Kattegat, and an oil spill in the wintertime is therefore a serious Danish environmental problem.
Dispersing o f O i l Chemical dispersants which can emulsify oil in water have been used for many. years for a number of purposes: cleaning of machines, oil tanks, etc., before they were used to combat oil spills on the sea. The 'first generation' of dispersants was not developed for combating oil spills, and because they were toxic as well as resistent to biodegradation, new 'second' and 'third generations' of dispersants have been developed without these disadvantages (Swedmark et al., 1973). But not all biological problems caused by using chemical dispersants are solved with this. C o m m o n to the use of both old and new dispersants is that oil is removed from the sea surface and dispersed in the water column within a short time, making the oil concentration many times higher than it would have been due to natural dispersal (wave action, etc.) (Wells & Keizer, 1975). Use of dispersants will most often lead to a much larger exposure of marine organisms to oil, resulting in more pronounced biological effects (Shelton, 1971). Especially in shallow waters with slow water renewal, oil disposal can lead to long exposure times at high oil concentrations resulting in severe damage to the ecosystem. Spawning and nursery areas are also sensitive to dispersed oil. The fertilized eggs of all commercially exploited Danish fish species-except herring and sand eel - have a tendency to assemble near the sea surface where, in cases of oil disposal, they can be exposed to high oil concentrations and be injured (Wilson, 1976; Lind6n, 1976). Finally, dispersing of oil increases the risk of tainting the taste of edible fish and mussels even though actual physiological damage may not be noticeable. The main biologicalreason for using chemical dispersants is to protect the seabirds, and quick and efficient dispersing of oil slicks in areas with m a n y seabirds can prevent mass killing of them, but, of course, quick mechanical clean-up would lead to the same result.
Oil Pollution Policy Chronic oil pollution
The scope of acute and chronic effects are not only dependent on the oil concentrations to which the marine organisms are exposed, but the chemical composition of the oil and the exposure time also have significant influence. Therefore, long exposure time of organisms even to low concentrations of oil can produce severe sublethal effects. Chronic oil pollution due to oil trapped in the sediments after an oil spill or due to continuous oil introduction from sewage or oil refineries can result in long term effects and taste-tainting of edible fish. The possible injurious effects of oil contamination of marine foodstuffs to human health are not clear, but it has been suggested that the carcinogenic polyaromatic hydrocarbons (PAIl) might be particularly dangerous. On this background, the Danish oil pollution policy has now become more restrictive, and a project to be led by the Marine Pollution Laboratory, Charlottenlund, is planned for 1979 with the purpose of clarifying the need for reduction and monitoring programs in areas with chronic oil pollution. 252
Oil spills at sea
Every oil spill on the sea is potentially biologically injurious and the Danish policy is that any large oil spill should be combatted as soon as possible by mechanical clean-up. Therefore, N A E P ' s division for oil combatting has set up the goal that oil spills up to 10 000 tons could be handled by mechanical clean-up in 1980. Even a small oil spill in areas with large seabird concentrations, as found in the Kattegat during the winter months, can result in a mass killing of seabirds. Oil spills in these areas therefore demands particularly quick and effective combatting, probably by use of dispersants.
Use o f dispersants
Dispersing can seriously be considered in! the winter months in areas with a reasonably high water renewal if there is a threatened risk of damage to seabird populations. The use o f dispersants in Danish waters is restrictive and can only take place if biological experts after careful consideration find it reasonable that dispersing will result in a generally smaller environmental damage, e.g. it might be reasonable to disperse an oil slick over deep water if mechanical clean-up is impossible and the wind is forcing the oil towards sensitive shallow waters. The main rule is that dispersants must not be used in the biologically productive spring and summer months (when also the concentrations and the vulnerability of seabirds are low) and never in shallow waters with slow water renewal, e.g. fjords, coves and bays.
P r e v e n t i v e steps
To minimize the risk of oil spills due to collisions or groundings of ships, the Danish legislation concerning prevention o f pollution by oil is now being reconsidered as the need o f more rigorous rules for the transport o f oil and oil products in Danish waters is obvious. Albers, P. H. & Szaro, R. C. (1978). Effects of no. 2 fuel oil on common eider eggs.Mar. Pollul. Bull., 9,138-139. Barry, M. & Yevich, P. P. (1975). Part IlI. Histopathological studies. Mar. Pollut. Bull., 6,171-173. Blumer, M. & Sass, J. (1972). Indegeneousand petroleum-derivedhydrocarbons in a polluted sediment. Mar. Pollut. Bull., 3 (6), 92-93. Buffer, J. N. (1975). Pelagictar. Scient. Am., 90-97. Clark, R. B. 0968). Oil pollution and the conservationof seabirds. Proc. Int. Conf. OilPollution Sea, Rome. 76-112.
Clark, R. B. (1978). Oiled seabird rescueand conservation. J. Fish. Res. Bd Can., 35, 675-678. Conover, A. J. (19?l). Some relations betweenzooplankton and bunker oil in Chedabucto Bay followingthe wreckof the tanker Arrow. J. Fish Res. 8d Can., 28,1327-1330.
Cretneay, W. J., Wong, C. S., Green, D. R. & Bawden, C. A. 09?8). Longterm fate of a heavy fuel oil in a spill-contaminatedB.C. Coastal Bay. J. Fish. R es. Bd Can., 35, 521-527. Dow, R. (I 9?5). Reducedgrowth and survivalof clamstransplanted to an oil spillsite. Mar. Pollut. Bull., 6,124-125. Floodgate, G. D. (19?2). Microbialdegradationof oil Mar. Pollut. Bull., 3(6), 41--43. Fossato, V. U. & Canzonier, W. J. (1976). Hydrocarbon uptake and loss by musselMytilus edulis. Mar. BioL, 36, 243-250. Goethe, F. (1968). The effects of oil pollution on populations of marine and coastalbirds. Helgoltinderwiss. Meeresunters., 17, 370-374. Hartung, R. & Hunt, G. S. (1966). Toxicityof some oils to waterfowl. J. Wildl. Mgmt., 30, 564--570. I.C.E.S. (International Council for the Exploration of the Sea). (1977). The Ekofisk Bravo blow out. Compiled Norwegian contributions. C. M. 1977/E:55.
Volume 10/Number 9/September 1979 Joensen, A. H. (1973). Danish seabird disasters in 1972. Mar. Pollut. Bull., 4,117-118. Joensen, A. H. & Hansen, E. B. (1977). Oil pollution and seabirds in Denmark 1971-1976. DanishRev. GameBiol., 10(5), 1-31. Johnston, R. (1970). The decomposition of crude oil residues in sand columns. J. mar. biol. Ass. U.K., 50, 925-937. Keizer, P. D., Ahem, T. P., Dale, J. & Vandermeulen, J. H. (1978). Residues of Bunker C oil in Chedabucto Bay, Nova Scotia, 6 years after the Arrow spill. J. Fish. Res. Bd Can., 35,528-535. Lind6n, O. (1976). Effects of oil on the reproduction of the amphipod Gammarus oceanicus. Ambio, 5, 36-37. Lind6n, O. (1976). The influence of crude oil and mixtures of crude oil/dispersants on the ontogenic development of the Baltic herring, Clupea harengus membras L. A mbio, 5, 136-140. Longwell, A. C. (1977). A genetic look at fish eggs and oil. Oceanus, 20, 46-58. Mackie, P. R., Hardy, R. &Whittle, K. J. (1978). Preliminary assessment of the presence of oil in the ecosystem at Ekofisk after the blow out, April 22-30, 1977. J. Fish. R es. Bd Can., 35,544-551. O'Sullivan, A. J. (1978). The Amoco Cadiz oil spill. Mar. Pollut. Bull., 9,123-128. Percy, J. A. & Mullin, T. C. (1977). Effects of crude oil on the locomotory activity of artic marine invertebrates. Mar. Pollut. Bull., 8, 35-39. Renzoni, A. (1975). Toxicity of three oils to bivalve gametes and larvae. Mar. Pollut. Bull., 6,125-128.
Marine Pollution Bulletin, Vol. 10, pp. 253-255 ©aergamon Press Ltd. 1979. Printed in Great Britain.
Sanders, H. L. (1977). The West Falmouth spill - Florida, 1969. Oceanus, 20, 15-24. Seeman, P. (1972). The membrane actions of anesthestics and tranquilizers.Pharmac. Rev., 24, 583-655. Shelton, R. G. J. (1971). Effects of oil and oil dispersants on the marine environment. Proc. R. Soc. Lond. B., 177,411-422. Stegemann, J. J. & Teal, J. M. (I973). Accumulations, releaseand retention of petroleum hydrocarbons by the oyster, Crassostrea virginica. Mar. Biol., 22, 37--44. Swedmark, M., Granmo, .~. & Kollberg, S. (1973). Effects of oil dispersants and oilemulsions on marine animals. Wat. Res., 7, 1649-1672. Tagger, S., Deveze, L. & Le Petit,J. (1976). The conditions for biodegration of petroleum hydrocarbons at sea. Mar. Pollut. Bull., 7 (9), 172-174. Van Vleet, E. S. & Quinn, J. G. (1978). Contribution of chronic petroleum inputs to Narragansett Bay and Rhode Island Sound sediments. J. Fish. Res. B d Can., 35,536-543, Wells, P. G. & Keizer, P. D. (1975). Effectiveness and toxicity of an oil dispersant in large outdoor salt water tanks. Mar. Pollut. Bull., 6, 153-157. Wells, P. G. (1972). Influence of Venezuelan crude oil on lobster larvae. Mar. Pollut. Bull., 3,105-106. Wilson, K. W. (1976). Effects of oil dispersants on the developing embryos of marine fish.Mar. Biol.,36, 259-268.
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Small Oil Spill Kills 10-20000 Seabirds in North N orway ROBERT T. B A R R E T T
Department of Zoology and Marine Biology, Troms¢ Museum, University of Troms¢, 9000 Troms¢, Norway An estimated 10-20 000 seabirds were killed by a very small oil spill off the coast of North Norway in March 1979. Despite the fact that over 90070 of these were Brnnnich's Guillemots Uria lomvia, the breeding population of this species was not considered to have been seriously threatened by this spill. On the other hand, this episode did illustrate how extremely vulnerable certain seabird species are to oil.
On 23 March, 1979 a few oiled seabirds were found on the shore between Vard¢ and Vads¢ in East Finnmark, North Norway (Fig. 1). More birds were found washed ashore on 24 March and the local police, the local game boards and the Finnmark Wildlife Manager were immediately notified. Notice was also given to the Norwegian Directorate for Wildlife and Freshwater Fish who then coordinated and f'manced all further operations concerning the birds. As yet no oil had been found along or immediately off the about 100 km long coastline, and all action was concentrated on humanely killing injured birds. This and the subsequent collection of all corpses found were carried out by members of the local game societies and army cadets. The corpses were later driven to Vads~ for sorting. No organized cleaning of oiled birds was attempted. By 29 March, when only a few birds were found and when the Directorate stopped all organized operations, an estimated total of 5 000 birds had been collected.
Despite 3-4 aerial searches during the week, only two or three small oil slicks were seen in the fjord and only two small areas of the shore were found covered in oil. In all cases the areas covered by oil amounted to a few hundred or thousand square metres. Samples of oil were analysed and results indicate that it was of a light fuel oil type. As yet the source of the oil is unknown. Despite so little oil being found, it is estimated that 1020 000 birds died as a result of oil pollution. This estimate is based on the approximately 5000 which were collected. It also takes into consideration those which never reached the shore and those which did but which either became frozen into the ice or which crept or were washed under the ice overhang at the top of the shore. There was a force 4-5 S to SE wind and at times much freezing spray from 24 to 29 March. Air temperatures ranged from - 6 to + 2°C. Of a sample of 1616 identified birds, 1477 or 91.4°70 were Brunnich's Guillemots Urialomvia. Other species found are listed in Table 1. To gather information concerning the birds to be found offshore, an air reconnaissance was made on 29 March. The flight was made along the coast from Vads¢ to Syltefjord and then 5-20 km out to sea N and E of Vard~. It returned to Vads~ via Grense Jakobselv and the southern shore of Varangerfjord. A large concentration of auks was seen about 10 km off Komagvaer, while 15-20 km NE and E of Vard~ immense flocks were seen (Fig. 1). Both flocks were impossible to
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0025-326X/79/0901 -.0250 $02.00/0
!
Viewpoint is a column which allows authors to express their own opinions about current events.
I
I
Danish Marine Oil Pollution Policy HANS ULRIK RIISGP, RD
Dr Rissgiird is Project Leader at the Kavalergarden Marine Pollution Laboratory and is concerned chiefly with the sub-lethal effects of pollutants on marine organisms. In this article he discusses the biological basis for the Danish marine oil pollution policy which has recently been revised. In the period 1973-1977 more than 400 oil spills, most of them small, were reported to the National Agency of Environmental Protection (NAEP), Denmark. The total oil transport through Danish territorial waters is now about 45m tons per year, not including an unknown amount of oil/oil products transported on Soviet Russian ships, and, further, tankers up to 130 000 tons dwt, now sail through the heavily trafficked Great Belt which connects the Baltic Sea and the Kattegat. Fear of the obvious possibility of large oil spills in Danish waters was strengthened after the Ekofisk 'Bravo' blow-out in the North Sea, April 1977, and the running aground of several tankers in the narrow Danish straits in 1977-78. Therefore, Danish marine oil policy has recently been revised, and in November 1978 a report on the biological effects of oil pollution in the marine environment was published by NAEP. The present paper gives a short review of the main points and the conclusions of this report, which forms the basis of Danish marine oil pollution policy.
Open Marine Areas A short time after an oil spill, a thin layer of oil a few rniilimetres in thickness will usually cover a relatively large area on the sea surface. While the oil is floating on the water, it is physically and chemically transformed ('weathered'), mainly due to evaporation. More than 50°70 of a light crude oil can evaporate within the first week after a spill (I.C.E.S., 1977). However, a small fraction of the oil is always dissolved in the water. As the most volatile hydrocarbons, especially the atomatic compounds, constitute both the most soluble and the most toxic fraction of oil, weathering processes protect the marine organisms against being exposed to dissolved harmful hydrocarbons. Depending on the vertical mixing in the water column, a certain concentration of hydrocarbons can always be found in the water some time after an oil spill (Mackie et al., 1978). In open marine areas it is, therefore, primarily plankton organisms and fry near the sea surface which take up oil and are injured. Depending on wave action, oil is also emulsified in the water as small particles in the size range of 5--40/an. These oil particles are retained and eaten as plankton particles by suspension feeding copepods (Conover, 1971) and mussels, through which the oil is brought into the marine food-webs and distributed throughout the entire biological system. 250
Generally, the biological damage due to an uncombatted oil spill in an open marine area is limited, when injuries to seabirds are not taken into account. This is partly due to the weathering processes, the tremendous dissolving capacity of the sea and the large regenerative ability of the marine biological system.
Shallow Marine Waters Shallow waters with a relatively small volume of water are generally very sensitive to oil pollution, and large, oil spills can result in extensive biological damage. The immediate consequences are often mass killing of fish and invertebrates (O'Sullivan, 1978), and oil pollution in shallow waters can give rise to chronic effects and an oily taste in fish and mussels up to several years after an oil spill, if oil is trapped in the sediments under anaerobic conditions (Sanders, 1977). The Danish shoreline, with its many fjords and coves, is extremely long and the relatively large areas with shallow waters are very productive in the summertime. The most important primary producers are diatoms and macrophytes, which give rise to a rich production of polychaetes, gastropods and bivalves that are the most important prey organisms for fry and young fish. A larger oil spill in these areas may therefore result in severe ecological damage and destruction of important edible fish and mussels.
Sublethal Effects of Oil Petroleum hydrocarbons are taken up in marine animals by assimilation of oil-contaminated food in the intestine and by absorption of hydrocarbons through the outer surfaces. Absorption of hydrocarbons is a rapid process depending on the oil concentration in the surrounding water (Stegeman & Teal, 1973; Fossato & Canzonier, 1976). The toxicity of petroleum hydrocarbons depends on their chemical and physiological properties. The lipophilic low molecular hydrocarbons are particularly toxic: they are easily taken up in the lipid-rich cell membranes through which they diffuse, damaging important membrane functions and intracellular biochemical processes. Chemically reactive hydrocarbons, especially aromatic compounds, can thus give rise to severe injury to marine organisms.
Volume 10/Number 9/September 1979
The first signs of toxic effects of oil on fish and invertebrates are reduced reaction time, muscle control failure, and behavioural disorders. These effects can be classified as narcotic, possibly because the impulse conductivity of the nerves is inhibited by petroleum hydrocarbons in the membrane of the nerve cells (Seeman, 1972). If oil-contaminated organisms are transferred to clean water, most of the hydrocarbons will soon be released and only smaller amounts, possibly concentrated in lipid depots, are released very slowly (Stegemann & Teal, 1973). Many acute injuries are reversible and the normal biological functions can be reestablished in clean water if the petroleum hydrocarbons are released before they have caused permanent damage (Percy & Mullin, 1977). Chronic effects can arise when aromatic hydrocarbons, instead of being hydroxylated by the cells' normal detoxificationsystem, are transformed into more poisonous intermediate products. These products may be strongly toxic and possibly damage the genetic information mechanism. As genetic injuries can result in cancer, it is perhaps these reactive intermediate products that are the carcinogenic components in oil (Longwell, 1977; Barry & Yevich, 1975). Other chronic injuries caused by oil pollution are reduced growth (Dow, 1975) and fertility (Lind6n, 1976). These effects are due to physiological stress because the energy consumption for maintaining normal cellular, and with that, physiological functions can be raised significantly so that a smaller amount of food energy can be spent on these purposes. Serious chronic injuries can also be due to sublethal effects on the early ontogenetic stages which are generally much more sensitive than the adult organism (Well, 1972). Finally, oil can inhibit the fertilization of marine organisms that spawn their sex products in the water (Renzoni, 1975).
Microbiological Decomposition of Oil After an oil spill, it is possible to demonstrate an increase in the number of microorganisms, mainly bacteria, which are able to metabolize oil. No single organism is able to decompose all the different hydrocarbons in crude oil, and the temperature and the amount of nutrients influence the rate of decomposition (Tagger et al., 1976). The chemical composition of the oil is an important factor in the microbiological breakdown because the different oil components have differing degrees of persistence, solubility and toxicity to the microorganisms. A very important factor in the microbiological breakdown is the molecular configuration of the hydrocarbons: alkanes are more degradable than aromatic or cycloalkane compounds, and long carbon chains are broken down more easily than branched compounds (Floodgate, 1972). The microbiological decomposition of oil is mainly located at the water/oil interface, and a thin oil film is, therefore, broken down faster than a thick oil slick on the water surface. Two types of oil emulsions can, depending on the circumstances (wave action, use of dispersing chemicals, etc.), be formed after an oil spill: a. oil-in-water emulsion, and b. water-in-oil emulsion ('chocolate mousse'). The difference in decomposition rate of the two emulsions is large. The oil-in-water emulsion, where the oil is mixed in the water as small oil drops, is broken down much more easily than the more compact water-in-oil emulsion, which
often ends up as 'pelagic tar' when the oxygen and the nutrients in the off-bound water are used up by the microorganisms (Butler, 1975). The amount of oxygen in the sea water is possibly never a limiting factor for the decomposition of oil. This contrasts with the situation in marine sediments. In shallow waters the amount of inorganic particles in the water is often high, especially in stormy weather. If oil adsorb to these particles, they may sink to the bottom and the oil is eventually trapped in the sediment. Oil in the sediment will at first stimulate the growth of oil-degrading bacteria, but as the oxygen is used by the microorganisms in the combustion of the organic hydrocarbons, all the oxygen will soon be used up (Johnston, 1970). Oil in the sediment is often degraded extremely slowly (Blumer & Sass, 1972), not only due to anerobic conditions, but the protection against photo-chemical breakdown, frequently in combination with depletion of nutrients, can inhibit the decomposition. Thus, shallow waters with muddy and anaerobic sediments are especially vulnerable to oil spills because oil in the sediment can give rise to severe chronic oil pollution over a long period (Cretneay et al., 1978; Keizer et ai., 1978; Vleet &Quinn, 1978).
Damage of Oil on Seabirds Oil pollution in Danish waters kills thousands of seabirds every year, mainly ducks but sometimes also a considerable number of other web-footed birds. Above all, oil pollution has attracted the attention of the public through extensive damage to seabirds, as was the case twice in 1972 where relatively small amounts of oil from unknown ships resulted in seabird disasters where more than 30 000 birds in each case died from exposure to oil (Joensen, 1973). The plumage of sea birds is waterproof but oil absorbing. When a seabird comes in contact with oil, the waterproof effect is lost and the water forces its way into the normal heat isolating layer of the plumage. In cold water, a 2-3 cm~spot without heat isolation on the breast of a duck will soon kill the bird, while contamination of the plumage in warmer water can weigh down the bird so much that swimming and flying are made impossible, finally leading to the death of the bird. Seabirds may also die from injuries to inner organs caused by eating oil-contaminated food or by cleaning the oil-polluted plumage (Clark, 1968). The damage to inner organs are multitudinous and may result in anaemia, degeneration of the liver, lung inflammation or injuries to the kidneys or the nervous system (Hartnung & Hunt, 1966; Goethe, 1968). The overall damage ofoil to seabirds is often so pronounced that even moderately contaminated birds have only a small chance to survive, and human efforts to clean oiled birds have never been very successful (Clark, 1978). Oil contamination can also have injurious effects on the hormone regulation, leading to reduced fertilitywhile oil on the eggs can result in embryonic damage (Albers & Szaro, 1978). Deaths of seabirds due to oil pollution in Danish waters are mainly registered from October to April, presumably due to the high sensitivity of oiled birds to cold water and because enormous concentrations of many species of seabirds stay in these areas during the winter (Joensen & Hansen, 1977). A considerable part of the North-West European population of common eiders have their winter 251
MarinePollutionBulletin quarters in Danish waters, especially in the Kattegat, and an oil spill in the wintertime is therefore a serious Danish environmental problem.
Dispersing o f O i l Chemical dispersants which can emulsify oil in water have been used for many. years for a number of purposes: cleaning of machines, oil tanks, etc., before they were used to combat oil spills on the sea. The 'first generation' of dispersants was not developed for combating oil spills, and because they were toxic as well as resistent to biodegradation, new 'second' and 'third generations' of dispersants have been developed without these disadvantages (Swedmark et al., 1973). But not all biological problems caused by using chemical dispersants are solved with this. C o m m o n to the use of both old and new dispersants is that oil is removed from the sea surface and dispersed in the water column within a short time, making the oil concentration many times higher than it would have been due to natural dispersal (wave action, etc.) (Wells & Keizer, 1975). Use of dispersants will most often lead to a much larger exposure of marine organisms to oil, resulting in more pronounced biological effects (Shelton, 1971). Especially in shallow waters with slow water renewal, oil disposal can lead to long exposure times at high oil concentrations resulting in severe damage to the ecosystem. Spawning and nursery areas are also sensitive to dispersed oil. The fertilized eggs of all commercially exploited Danish fish species-except herring and sand eel - have a tendency to assemble near the sea surface where, in cases of oil disposal, they can be exposed to high oil concentrations and be injured (Wilson, 1976; Lind6n, 1976). Finally, dispersing of oil increases the risk of tainting the taste of edible fish and mussels even though actual physiological damage may not be noticeable. The main biologicalreason for using chemical dispersants is to protect the seabirds, and quick and efficient dispersing of oil slicks in areas with m a n y seabirds can prevent mass killing of them, but, of course, quick mechanical clean-up would lead to the same result.
Oil Pollution Policy Chronic oil pollution
The scope of acute and chronic effects are not only dependent on the oil concentrations to which the marine organisms are exposed, but the chemical composition of the oil and the exposure time also have significant influence. Therefore, long exposure time of organisms even to low concentrations of oil can produce severe sublethal effects. Chronic oil pollution due to oil trapped in the sediments after an oil spill or due to continuous oil introduction from sewage or oil refineries can result in long term effects and taste-tainting of edible fish. The possible injurious effects of oil contamination of marine foodstuffs to human health are not clear, but it has been suggested that the carcinogenic polyaromatic hydrocarbons (PAIl) might be particularly dangerous. On this background, the Danish oil pollution policy has now become more restrictive, and a project to be led by the Marine Pollution Laboratory, Charlottenlund, is planned for 1979 with the purpose of clarifying the need for reduction and monitoring programs in areas with chronic oil pollution. 252
Oil spills at sea
Every oil spill on the sea is potentially biologically injurious and the Danish policy is that any large oil spill should be combatted as soon as possible by mechanical clean-up. Therefore, N A E P ' s division for oil combatting has set up the goal that oil spills up to 10 000 tons could be handled by mechanical clean-up in 1980. Even a small oil spill in areas with large seabird concentrations, as found in the Kattegat during the winter months, can result in a mass killing of seabirds. Oil spills in these areas therefore demands particularly quick and effective combatting, probably by use of dispersants.
Use o f dispersants
Dispersing can seriously be considered in! the winter months in areas with a reasonably high water renewal if there is a threatened risk of damage to seabird populations. The use o f dispersants in Danish waters is restrictive and can only take place if biological experts after careful consideration find it reasonable that dispersing will result in a generally smaller environmental damage, e.g. it might be reasonable to disperse an oil slick over deep water if mechanical clean-up is impossible and the wind is forcing the oil towards sensitive shallow waters. The main rule is that dispersants must not be used in the biologically productive spring and summer months (when also the concentrations and the vulnerability of seabirds are low) and never in shallow waters with slow water renewal, e.g. fjords, coves and bays.
P r e v e n t i v e steps
To minimize the risk of oil spills due to collisions or groundings of ships, the Danish legislation concerning prevention o f pollution by oil is now being reconsidered as the need o f more rigorous rules for the transport o f oil and oil products in Danish waters is obvious. Albers, P. H. & Szaro, R. C. (1978). Effects of no. 2 fuel oil on common eider eggs.Mar. Pollul. Bull., 9,138-139. Barry, M. & Yevich, P. P. (1975). Part IlI. Histopathological studies. Mar. Pollut. Bull., 6,171-173. Blumer, M. & Sass, J. (1972). Indegeneousand petroleum-derivedhydrocarbons in a polluted sediment. Mar. Pollut. Bull., 3 (6), 92-93. Buffer, J. N. (1975). Pelagictar. Scient. Am., 90-97. Clark, R. B. 0968). Oil pollution and the conservationof seabirds. Proc. Int. Conf. OilPollution Sea, Rome. 76-112.
Clark, R. B. (1978). Oiled seabird rescueand conservation. J. Fish. Res. Bd Can., 35, 675-678. Conover, A. J. (19?l). Some relations betweenzooplankton and bunker oil in Chedabucto Bay followingthe wreckof the tanker Arrow. J. Fish Res. 8d Can., 28,1327-1330.
Cretneay, W. J., Wong, C. S., Green, D. R. & Bawden, C. A. 09?8). Longterm fate of a heavy fuel oil in a spill-contaminatedB.C. Coastal Bay. J. Fish. R es. Bd Can., 35, 521-527. Dow, R. (I 9?5). Reducedgrowth and survivalof clamstransplanted to an oil spillsite. Mar. Pollut. Bull., 6,124-125. Floodgate, G. D. (19?2). Microbialdegradationof oil Mar. Pollut. Bull., 3(6), 41--43. Fossato, V. U. & Canzonier, W. J. (1976). Hydrocarbon uptake and loss by musselMytilus edulis. Mar. BioL, 36, 243-250. Goethe, F. (1968). The effects of oil pollution on populations of marine and coastalbirds. Helgoltinderwiss. Meeresunters., 17, 370-374. Hartung, R. & Hunt, G. S. (1966). Toxicityof some oils to waterfowl. J. Wildl. Mgmt., 30, 564--570. I.C.E.S. (International Council for the Exploration of the Sea). (1977). The Ekofisk Bravo blow out. Compiled Norwegian contributions. C. M. 1977/E:55.
Volume 10/Number 9/September 1979 Joensen, A. H. (1973). Danish seabird disasters in 1972. Mar. Pollut. Bull., 4,117-118. Joensen, A. H. & Hansen, E. B. (1977). Oil pollution and seabirds in Denmark 1971-1976. DanishRev. GameBiol., 10(5), 1-31. Johnston, R. (1970). The decomposition of crude oil residues in sand columns. J. mar. biol. Ass. U.K., 50, 925-937. Keizer, P. D., Ahem, T. P., Dale, J. & Vandermeulen, J. H. (1978). Residues of Bunker C oil in Chedabucto Bay, Nova Scotia, 6 years after the Arrow spill. J. Fish. Res. Bd Can., 35,528-535. Lind6n, O. (1976). Effects of oil on the reproduction of the amphipod Gammarus oceanicus. Ambio, 5, 36-37. Lind6n, O. (1976). The influence of crude oil and mixtures of crude oil/dispersants on the ontogenic development of the Baltic herring, Clupea harengus membras L. A mbio, 5, 136-140. Longwell, A. C. (1977). A genetic look at fish eggs and oil. Oceanus, 20, 46-58. Mackie, P. R., Hardy, R. &Whittle, K. J. (1978). Preliminary assessment of the presence of oil in the ecosystem at Ekofisk after the blow out, April 22-30, 1977. J. Fish. R es. Bd Can., 35,544-551. O'Sullivan, A. J. (1978). The Amoco Cadiz oil spill. Mar. Pollut. Bull., 9,123-128. Percy, J. A. & Mullin, T. C. (1977). Effects of crude oil on the locomotory activity of artic marine invertebrates. Mar. Pollut. Bull., 8, 35-39. Renzoni, A. (1975). Toxicity of three oils to bivalve gametes and larvae. Mar. Pollut. Bull., 6,125-128.
Marine Pollution Bulletin, Vol. 10, pp. 253-255 ©aergamon Press Ltd. 1979. Printed in Great Britain.
Sanders, H. L. (1977). The West Falmouth spill - Florida, 1969. Oceanus, 20, 15-24. Seeman, P. (1972). The membrane actions of anesthestics and tranquilizers.Pharmac. Rev., 24, 583-655. Shelton, R. G. J. (1971). Effects of oil and oil dispersants on the marine environment. Proc. R. Soc. Lond. B., 177,411-422. Stegemann, J. J. & Teal, J. M. (I973). Accumulations, releaseand retention of petroleum hydrocarbons by the oyster, Crassostrea virginica. Mar. Biol., 22, 37--44. Swedmark, M., Granmo, .~. & Kollberg, S. (1973). Effects of oil dispersants and oilemulsions on marine animals. Wat. Res., 7, 1649-1672. Tagger, S., Deveze, L. & Le Petit,J. (1976). The conditions for biodegration of petroleum hydrocarbons at sea. Mar. Pollut. Bull., 7 (9), 172-174. Van Vleet, E. S. & Quinn, J. G. (1978). Contribution of chronic petroleum inputs to Narragansett Bay and Rhode Island Sound sediments. J. Fish. Res. B d Can., 35,536-543, Wells, P. G. & Keizer, P. D. (1975). Effectiveness and toxicity of an oil dispersant in large outdoor salt water tanks. Mar. Pollut. Bull., 6, 153-157. Wells, P. G. (1972). Influence of Venezuelan crude oil on lobster larvae. Mar. Pollut. Bull., 3,105-106. Wilson, K. W. (1976). Effects of oil dispersants on the developing embryos of marine fish.Mar. Biol.,36, 259-268.
0025-326X/79/0901--0253 $02.00/0
Small Oil Spill Kills 10-20000 Seabirds in North N orway ROBERT T. B A R R E T T
Department of Zoology and Marine Biology, Troms¢ Museum, University of Troms¢, 9000 Troms¢, Norway An estimated 10-20 000 seabirds were killed by a very small oil spill off the coast of North Norway in March 1979. Despite the fact that over 90070 of these were Brnnnich's Guillemots Uria lomvia, the breeding population of this species was not considered to have been seriously threatened by this spill. On the other hand, this episode did illustrate how extremely vulnerable certain seabird species are to oil.
On 23 March, 1979 a few oiled seabirds were found on the shore between Vard¢ and Vads¢ in East Finnmark, North Norway (Fig. 1). More birds were found washed ashore on 24 March and the local police, the local game boards and the Finnmark Wildlife Manager were immediately notified. Notice was also given to the Norwegian Directorate for Wildlife and Freshwater Fish who then coordinated and f'manced all further operations concerning the birds. As yet no oil had been found along or immediately off the about 100 km long coastline, and all action was concentrated on humanely killing injured birds. This and the subsequent collection of all corpses found were carried out by members of the local game societies and army cadets. The corpses were later driven to Vads~ for sorting. No organized cleaning of oiled birds was attempted. By 29 March, when only a few birds were found and when the Directorate stopped all organized operations, an estimated total of 5 000 birds had been collected.
Despite 3-4 aerial searches during the week, only two or three small oil slicks were seen in the fjord and only two small areas of the shore were found covered in oil. In all cases the areas covered by oil amounted to a few hundred or thousand square metres. Samples of oil were analysed and results indicate that it was of a light fuel oil type. As yet the source of the oil is unknown. Despite so little oil being found, it is estimated that 1020 000 birds died as a result of oil pollution. This estimate is based on the approximately 5000 which were collected. It also takes into consideration those which never reached the shore and those which did but which either became frozen into the ice or which crept or were washed under the ice overhang at the top of the shore. There was a force 4-5 S to SE wind and at times much freezing spray from 24 to 29 March. Air temperatures ranged from - 6 to + 2°C. Of a sample of 1616 identified birds, 1477 or 91.4°70 were Brunnich's Guillemots Urialomvia. Other species found are listed in Table 1. To gather information concerning the birds to be found offshore, an air reconnaissance was made on 29 March. The flight was made along the coast from Vads¢ to Syltefjord and then 5-20 km out to sea N and E of Vard~. It returned to Vads~ via Grense Jakobselv and the southern shore of Varangerfjord. A large concentration of auks was seen about 10 km off Komagvaer, while 15-20 km NE and E of Vard~ immense flocks were seen (Fig. 1). Both flocks were impossible to
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