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Olympic Alliance oil spillage
Marine Pollution Bulletin
Results a n d D i s c u s s i o n All the following results are given in dry weight. The standard set down by the National Health and Medical Research Council is 2 ppm Cd wet wt or approximately 10 ppm dry wt. The U.S., however, has now reduced the permissible levels of cadmium to 1 ppm wet wt. With the exception of seven locations, the results indicate that the waters and sediments of Port Phillip and Corio Bays are heavily polluted with cadmium. Even those locations not so polluted are, however, close to it. If, on the other hand, World Health Organisation standards and not N . H . M . R . C . standards are used, the whole area may be considered as being polluted. Two anomalies appear to exist, one in Corio Bay and in the inner part of Point Richard Channel, the other, and to a lesser extent, in the mouth of the Yarra River. Erratic results occur in these estuaries and industrial areas because of dredging, currents, etc. which cause unnatural migration of the mussels. On N . H . M . R . C . standards, the non-industrial area between Portsea and Mornington might be considered as a borderline case. Mussels, collected on the base of piers were found to be less contaminated, probably due to the higher level of
trace metals in sediments than in suspended material (Table 3). A notable fact is that mud oysters accumulate this toxic metal more than mussels (Table 2). V. W. T A L B O T R. J. MAGEE
Department of Inorganic and Analytical Chemistry, La Trobe University, Bundoora, Melbourne, Victoria, Australia 3083 M. HUSSAIN
Environment Protection Authority, State of Victoria, Victoria Parade, East Melbourne, Victoria, Australia 3002 Flick, D. F., Kraybill, H. F. & Dimitroff, J. M. (1971). Toxic effects of cadmium: A review. Environ. Res., 4, 71-85. Talbot, V. W., Magee, R. J. & Hussain, M. (1976). Distribution of heavy metals in Port Phillip Bay. Mar. Pollut. Bull., 7,
Olympic Alliance Oil Spillage Despite the 1967 traffic separation scheme for the Straits of Dover another loaded tanker was damaged in a Channel collision. On this occasion approximately 20003000 tonnes of oil were spilt and despite extensive and rapid measures to disperse it at sea, the English coastline was again affected. At approximately 0110 hr, Wednesday, 12 November 1975, the Leander class frigate HMSAchilles (2500 tonnes dwt) and the Panamanian owned, Liberian registered supertanker Olympic Alliance (220000 tonnes dwt) collided 13 km from the Varne Lightship in the Dover Strait. Before the collision both vessels were proceeding in the correct northeast bound lane in thick fog. The tanker was holed and as a result lost an estimated 2000-3000 tons of light Iranian crude oil into the sea, forming a slick 11.3 km long and 1.6 km wide. Both ships later reached port without assistance. When the tanker left the collision site it was still leaking oil, and by the time it reached Wilhelmshaven, following a refusal to accept it at Rotterdam, an additional 10000 tonnes of oil had escaped, endangering large populations o f wintering wildfowl in the area (Tinker, 1975). Oil C l e a r a n c e O r g a n i z a t i o n a n d M e t h o d s The oil clearance operation was organized jointly by the Marine Division of the Department of Trade and Industry (off-shore oil dispersal) and the Kent County and District Councils (in-shore oil dispersal and removal from 86
beaches). The Coastal Protection Service of the Department of the Environment, Nature Conservancy Council, Royal Society for the Protection of Birds and the Royal Society for the Prevention of Cruelty to Animals assisted in the operation, rescuing and estimating the numbers of oiled seabirds recovered on the shore. Off-shore and in-shore oil dispersing activities were conducted by a fleet of 10 vessels, including the Dover Harbour Board tugs Dominant and Diligent which were equipped and dispatched immediately to the scene of the collision, the tug Calshot from Southampton, two French naval vessels, two Royal Navy vessels, including the Coastal Mine Hunter Bildeston from Lowestoft, and three fishing boats from Folkestone chartered by the Kent County Council. This fleet was directed and co-ordinated by Royal Navy aerial reconnaissance aircraft. Despite considerable success in dispersing larg~ quantities of the oil with the emulsifier BP 1100X, crud~ oil came ashore at high tide on 13 November betweer Sandwich and Kingsdown. The following day more wide spread shoreline pollution occurred between Dover anc Dungeness (Fig. 1). Oil deposition patterns varied with th~ location and nature of particular beach characteristics Sandy, low energy beaches with shallow profiles nea~ Folkestone were extensively covered by a wide band of oi ranging from 100 to 250 m in width, while narrow band: up to 3 m in width but 15-30 cm deep were characteristic o high energy shingle beaches with steeper profiles nea Dover and Deal. The rocky foreshores between Dover ant Folkestone were severely polluted;many of the larger rocl pools were filled with oil (Fig. 2).
Volume 7 / N u m b e r 5 / M a y 1976
a n i n f l a t a b l e b o o m , was only partially successful, as 5001. were removed later by a BP Sea Skimmer Recovery System f r o m the Isle of Grain, North Kent. Once the extent of the shore pollution was known, the duration of the clearance operation was estimated to be two or three weeks. However, a change in the wind direction to off-shore on 16 November pushed remaining '~" Dover Tanker steams away slicks out to sea. With higher tides and larger waves 14 th ~:~'~"'S:~'~I 5t h "~ docking 4 days later (2-4 m), treated oil deposits remaining on the beaches oymc0urc . ,nw,,he,.h. . . . were rapidly emulsified by wave action or buried. By 19 November only scattered weathered residues remained in I ,~t~ estt mated 2 0 0 0 ~ ~ ForI g(~tres ~;Uu rt~ s ;het°~dk~ Os' from the vicinity of untreated rocky areas, although further observations of oil and emulsifier inshore or on the / ~Reported obt slicks ~. beaches were made intermittently for a period of six weeks. Fig. 1 Sequence of events in the Straits of Dover after the collision of The costs for the oil clearance operations were the the tanker OlympicA lliance, 220000 tons dwt, and H M S A chilies, largest to date in the area and a direct result of 350 0001. of a frigate 2500 tons. emulsifier used. A total bill of £65 000 was shared by three sources--the County Council £47 000, Shepway and Unlike previous incidents oil clearance operations were Dover District Councils £8 000 and Central Government restricted or a b a n d o n e d in conservation zones or sites of £10 000. scientific interest, previously designated by the County Authority in conjunction with the Nature Conservancy Effects u p o n Seabirds Council (South East Region). Consequently, the rocky Following the collision, oiled seabirds were sighted over foreshore between Dover and Folkestone was left to recover naturally while oil residues on the sandy beaches in a wide area. An emergency collecting station was the vicinity of Dymchurch and Greatstone were removed established at Dover, where the birds were sorted; the by mechanical methods, thereby minimizingthe disturb- more heavily contaminated and emaciated victims ance to intertidal flora and fauna. Oil clearance ashore humanely destroyed and the remainder dispatched to a was therefore selective, and also limited by the available rehabilitation centre in Sussex. Special beached bird w.orkforce, equipment and access to particular areas. surveys were organized to estimate the total numbers and Shingle beaches were cleaned with the dispersant BP species affected. A small, continuous supply arrived at the 1100X by manual or mechanized units (Fig. 3). Sandy emergency centre from 13 to 18 N o v e m b e r with a beaches were cleaned by burying or removing oil in sand m a x i m u m of 40 on 17 November. However, precise numbers are unknown since details were not recorded deposits both manually and by mechanical diggers. An attempt to prevent oil entering Folkestone H a r b o u r using accurately from beach surveys or at the emergency centre. i~ WFnd vector dnagram ~ "~-Y'~N I, t h - 17 t h N. . . . ber /
4,t.h,~cff
0 I
I0 I
km
20 I
30 I
Fig. 2 Heavily polluted rocky foreshore at Dover.
87
Marine Pollution
Fig. 3 Mechanised
beach spraying
As expected the Auks (Alcidae) were most frequently recorded although the numbers were small since the main dispersing grounds are outside the affected area in November (Table 1). The resident non-breeding Cormorant (Phalacrocorax carbo)population, shown to be supplemented at this time of year with vagrants (Table 2), was particularly affected, as shown by the high proportion of the total population oiled and their scarcity in the area during subsequent observations. Some unexpected species were recovered, including a Brent Goose (Branta bernicla), Tufted Duck (Aythya fuligula)and Coot (Fulicaatra), usually observed oiled on the shore during prolonged periods of colder weather in January and February. Most of the diving birds and the majority of floating debris, particularly containers, were completely covered with a uniform layer of oil, a pattern associated with the effects of previous acute oil spillages in the area (Dixon,
Bulletin
unit (Bazoo) at Dover.
1969). Various types of pollution patterns are still being investigatedbytheauthors. To obtain an accurate assessment of the numbers of oiled seabirds in a sample area, four consecutive weekly shore surveys were conducted between Deal and Sandwich from 16 November. Although the numbers of dead or incapacitated victims were small, approximately 1OOC Gulls (Laridae) were observed with varying degrees of oil contamination but apparently unharmed, a phenomenon noted following a previous oil spillage in the area (Dixon & Estimates
TABLE I of the numbers and species of oiled seabirds.
Species Cormorant Phalacrocorax carbo Brent Goose Branta bernicla Tufted Duck Aythafuligula Common Scoter Melanittanigra Eider Somateria mollissima
Recovered alive and incapacitated
Reported dead
Total
12
6
18
1
Nil
I
3
Nil
3
I
2
3
1
2
3
2
I
3
I
2
3
3
3
6
1
I
2
Nil
4
4
6
2
8
15
16
31
19 57
18 20
37 77
122
77
199
coot
S Sandettie EG East GoodwIn ““v $yt$ Goodwn
I
Boulogne 0
IO ,
20,
30,
4c
km
Fig. 4 Present traffic separation scheme in the Dover Strait and the sites of collisions from its inception on 1 June 1967 to 28 February 1971.
88
Fulica atra Greater Black Backed Gull Larus tnarinus Herring Gull Larus argentatus Common Gull Larus canus Black Headed Gull Larus ridibundus Kittiwake Rissa tridactyla Razorbill Alca torda Guillemot Uris aalge Unidentified Totals
Volume7/Number 5/May 1976 TABLE2 Age and origin of oiled seabirds recoveredringed. Ring number Species
Ringing place
Ringing Recovery Recovery date date place
506.8704 Cormorant St. Margaret's 28.6.75 18.11.75 Dover Island, Tenby, (Kent) Pembrokeshire, U.K. 505.9680 Cormorant St. Margaret's 28.6.75 18.11.75 Dover Island, Tenby, (Kent) Pembrokeshire, U.K. Dixon, 1971). In most cases the extent of contamination was slight, confined to superficial blobs on ventral surfaces and the head. Observations indicated this pattern originated from contact with beached oil deposits rather than oil in water emulsions observed in other areas (Bourne & Bibby, 1975). In the absence of corpses and continuous reduction in the numbers of relative proportions of birds observed oiled during subsequent observations (Table 3) it would appear that many cleaned themselves by preening, without apparent harmful effects, as demonstrated by other authors (Birkhead, etal., 1973). The press reported oil damage to local inshore fishery equipment and a possible closedown of the Dungeness Nuclear Power Stations had oil entered intakes to seawater cooling systems. Pending the outcome of investigations and postoperational reports by the Ministry of Defence (Royal Navy), the Department of Trade and Industry, and the Liberian Government, the cause of the collision is unknown. However, one or both of the vessels may have been taking evasive action to avoid a collision with one or more 'rogue' ships in the incorrect sea lane. A radar film of these events was recorded by the St. Margaret's Bay Coastguard Station, one of two purpose built radar tracking systems monitoring shipping movements in the Straits of Dover. From the available data (Grimes, 1971) there has been no apparent improvement in the collision rate since the introduction of the traffic separation scheme. These events add to the controversy over shipping routes through the Dover Strait. At present there are several faults with the system. The scheme is advisory and not compulsory, therefore there are a number of vessels that ignore recommendations and have the right to do so. This in turn endangers vessels adhering to the routing scheme and in some cases may be responsible for causing collisions (Dixon, 1972). Since the scheme has been introduced, the size, draught and number of ships using the Dover Strait has exceeded forecasts. Consequently, TABLE3 Proportions of Gull populations observedoiledduring four consecutiveweeklycounts between Dealand Sandwich. (% Total numbersobserved) Greater Black BackedGull (Larusmarinus) Herring Gull (Larusargentatus) CommonGull (Laruscanus) Black Headed Gull (Larus ridibundus)
38 (80) 26 (550) 31 (25) 28 (250)
21 (35) 12 (200) 17 (11) 9 (90)
(Figures in brackets refer to sample numbers.)
7 (8) 4 (60) Nil
Nil
2 (25)
1 (4)
1 (6) Nil
the obligation on these ships to manoeuvre in relatively confined and shallow waters is creating a serious hazard, not only to themselves, but to all other craft using the Strait. Until coastal states can promulgate a comprehensive navigational code for these waters, the collision and pollution risk will remain high, especially where routes converge or cross (Anon, 1972,1975). This can be substantiated by the frequency of acute oil spillages resulting in extensive coastal pollution on Kent beaches between January 1963 and December 1975, the majority of incidents occurring since March 1969 (Dixon, 1969; Dixon & Dixon, 1971 ; Tittley, 1971). The organization for rescuing and counting oiled seabirds was shown to be only partially effective. Fortunately the numbers recovered were small and voluntary assistance available from press and television appeals for help. This spillage was of sufficient size to thoroughly test the existing oil clearance organization. Despite extensive beach pollution the seaborne operation was effective, although hampered by short daylight hours, poor visibility, gale force winds and the strong tidal and residual water movements experienced in these waters (Carruthers, 1925; Cartwright, 1961). However, criticisms have been made concerning the ability of seaborne operations to prevent extensive coastal pollution in the area. Tanker collisions or groundings to date have involved either small losses of fuel oil from empty tankers (Texaco Caribbean 1000 tonnes) or minor cargolosses from fully laden vessels (Panther, 11 tonnes). However, extensive coastal pollution resulted from each incident, although offshore dispersing operations tried to prevent it. The risk of further coastal pollution remains high, since the distribution pattern for recent collision sites indicates a concentration in the southbound sea lane close to the English coastline (Fig. 4). In the preparation of this manuscript comments were received from the Department of Trade and Industry (Marine Division), Kent County Council, Royal Society for the Protection of Birds, Royal Society for the Preventionof Cruelty to Animals, Department of the Environment and the Nature Conservancy Council. Assistance with estimates of oiled seabirds was received from D. Smith and the Sandwich Bay Bird Observatory. T. J. D I X O N T. R. D I X O N Oil Pollution South East Kent Ashburnham, Green Lane, Temple Ewell, Nr. Dover, Kent, C T 1 6 3 A S , U.K.
Anon (1972). Law of the sea. Mar. Pollut. Bull., 3, 19. Anon (1975). Sea traffic control. Mar. Pollut. Bull. 6, 33-35. Birkhead, T. R., Lloyd,C. & Corkill, P. (1973). Oiledbirds successfully cleaning their plumage. Brit. Birds, 66, 535-537. Bourne, W. R. P. & Bibby, C. J. (1975). Temperature and the seasonal and geographical occurrenceof oiled birds on West European Beaches. Mar. Pollut. BulL,6, 77-80. 89
Marine Pollution Bulleti~
Carruthers, J. N. (1925). The water movement in the neighbourhood of the English Channel-North Sea Junction. J. m a r BioL Ass., UK 13,665. Cartwright, D. E. (1961). A study of currents in the Strait of Dover. J. Inst. Navig., 14, 130-151. Dixon, T. J. (1972). Another Collision in the English Channel. Mar. Pollut. Bull., 3,180. Dixon, T. R. (1969). Oil Pollution South East Kent, Report 1968-1969. Mar. Pollut. Bull., Series 1, 13, 9-13.
Dixon, T. R. & Dixon, T. J. (1971). The Panther affair. Mar. Pollut Bull., 2,107-108. Grimes, C. (1971). A survey of marine accidents involving oil pollutioJ and other dangers from hazardous cargoes. Defence Operationa Analysis Establishment. Report 7103. Project DL 14/01 (Ministry of Defence, London). Tinker, J. (1975). The case of the vanishing vessel. N e w Scientist 20 November 1975. Tittley, I. (1972). Kent Coast in i971. Mar. Pollut. Bull., 3, 135-138.
Transport of Mercury Through a Laboratory Two-level Marine Food Chain Algal cultures grown in the presence of 164 ~g/I mercury as mercuric chloride acquired and retained about half of the mercury. When the algae which had been grown in the presence of mercury were fed to planktonic copepods: (1) egg-laying rate showed no significant change; (2) eggs of a female fed mercury-enriched algae hatched, and nauplii moulted to apparently normal copepodites while in contact with spiked algae, and (3) analysis of the algae/copepod system showed that neither the copepods nor their eggs and faeces retained mercury in detectable amounts. At least in the one simple f o o d chain, although mercury was concentrated by the algae, the mercury was not passed up the chain to the next trophic level. It has often been intimated that the concentration of a heavy trace metal such as mercury would be increased at each trophic level in the food chain. Recent analyses of naturally occurring populations (Leatherland et al., 1973) have tended to cast doubt upon this paradigm, but the low levels of mercury existing in ocean waters as well as the complexity of the interactions in a naturally occurring food web have made firm conclusions difficult to draw. We have chosen to examine a simple system consisting of the primary algal producer Croomonas salina, and the second level omnivorous calanoid copepod Acartia tonsa Dana. Culturing techniques and analytical practices have been previously described by Zillioux & Wilson (1966) and Carr et al. (1972). In the first stage of the experiment, we grew the algae in an enriched culture, spiked with 5000 ng of mercury (conc. = 164~g/1) as mercuric chloride• Within 48 h, about half the mercury associated with the algae cells, some was deposited on the culture tube walls, and the remainder stayed in solution (Fig. 1). At this time the algae contained 1400 p p m Hg by dry weight. This should be compared with a range of 0.1-10 p p m reported by W i n d o m (1973) for Atlantic coastal plankton and 0.1-0.7 ppb for Pacific pelagic phytoplankton reported by Knauer & Martin (1972). Notice (Fig. 1) that our mass balances allowed us to identify about 95°70 of the 5000 ng of mercury added. The second stage of the study involved feeding portions of mercury-rich algae to female copepods on two separate occasions. Individual females were transferred and fed, and egg counts were recorded at the end of every 24-h period. We observed that when mercury-enriched algae were kept in test solution for 24 h without copepods, the 90
mercury remained associated with the algae and did no redistribute. In the first experiment, after a five-da~ control period, mercury-spiked algae were fed to 1! copepods at a concentration of 1400 p p m Hg by dry weigh algae• Six controls were fed unspiked algae for the entin period. In the second experiment, 8 females were fed concentration of 1800 p p m Hg, and 3 control females wer, used. In both copepod experiments, during the 5-da,. period when spiked algae were fed, we noted no significan difference between the mean egg laying rates of th, experimental females when compared to the controls ( test; 0.1 • P :- 0.05)• Other research (Wilson & Parrish, ii prep.) has shown that conditions of stress affect this rate The contents of the culture dishes were analysed after on, 24-h period. Figure 2 shows the distribution found During this contact time, the minimum amount of alga, thecopepods ingested averaged 5 x 10 ~ cells per day. Thi :
I00
Losses
-
= ÷ere:l SOILJTon 80
Culture
tube
WailS
0 0 0 if3
40
Algae
o~ 2O
,/
/
.
.
.
.
.
.
.
.
,
.
0
.
.
.
Blank
~3 1500
i c_
i
:~ L
IOOi) !
l ,
20
40
¢]0-
Hours
--
contact
8('
- - -
with
it3()
5000
i'O
140
ng mercury
Fig. 1 Distribution of mercury (5000 ng) as function of time. Figure 1 represents a cumulative graph in which % Hg associated wit algal ceils, solution, culture tube walls, and losses, is indicated b the area between the curves.
Results a n d D i s c u s s i o n All the following results are given in dry weight. The standard set down by the National Health and Medical Research Council is 2 ppm Cd wet wt or approximately 10 ppm dry wt. The U.S., however, has now reduced the permissible levels of cadmium to 1 ppm wet wt. With the exception of seven locations, the results indicate that the waters and sediments of Port Phillip and Corio Bays are heavily polluted with cadmium. Even those locations not so polluted are, however, close to it. If, on the other hand, World Health Organisation standards and not N . H . M . R . C . standards are used, the whole area may be considered as being polluted. Two anomalies appear to exist, one in Corio Bay and in the inner part of Point Richard Channel, the other, and to a lesser extent, in the mouth of the Yarra River. Erratic results occur in these estuaries and industrial areas because of dredging, currents, etc. which cause unnatural migration of the mussels. On N . H . M . R . C . standards, the non-industrial area between Portsea and Mornington might be considered as a borderline case. Mussels, collected on the base of piers were found to be less contaminated, probably due to the higher level of
trace metals in sediments than in suspended material (Table 3). A notable fact is that mud oysters accumulate this toxic metal more than mussels (Table 2). V. W. T A L B O T R. J. MAGEE
Department of Inorganic and Analytical Chemistry, La Trobe University, Bundoora, Melbourne, Victoria, Australia 3083 M. HUSSAIN
Environment Protection Authority, State of Victoria, Victoria Parade, East Melbourne, Victoria, Australia 3002 Flick, D. F., Kraybill, H. F. & Dimitroff, J. M. (1971). Toxic effects of cadmium: A review. Environ. Res., 4, 71-85. Talbot, V. W., Magee, R. J. & Hussain, M. (1976). Distribution of heavy metals in Port Phillip Bay. Mar. Pollut. Bull., 7,
Olympic Alliance Oil Spillage Despite the 1967 traffic separation scheme for the Straits of Dover another loaded tanker was damaged in a Channel collision. On this occasion approximately 20003000 tonnes of oil were spilt and despite extensive and rapid measures to disperse it at sea, the English coastline was again affected. At approximately 0110 hr, Wednesday, 12 November 1975, the Leander class frigate HMSAchilles (2500 tonnes dwt) and the Panamanian owned, Liberian registered supertanker Olympic Alliance (220000 tonnes dwt) collided 13 km from the Varne Lightship in the Dover Strait. Before the collision both vessels were proceeding in the correct northeast bound lane in thick fog. The tanker was holed and as a result lost an estimated 2000-3000 tons of light Iranian crude oil into the sea, forming a slick 11.3 km long and 1.6 km wide. Both ships later reached port without assistance. When the tanker left the collision site it was still leaking oil, and by the time it reached Wilhelmshaven, following a refusal to accept it at Rotterdam, an additional 10000 tonnes of oil had escaped, endangering large populations o f wintering wildfowl in the area (Tinker, 1975). Oil C l e a r a n c e O r g a n i z a t i o n a n d M e t h o d s The oil clearance operation was organized jointly by the Marine Division of the Department of Trade and Industry (off-shore oil dispersal) and the Kent County and District Councils (in-shore oil dispersal and removal from 86
beaches). The Coastal Protection Service of the Department of the Environment, Nature Conservancy Council, Royal Society for the Protection of Birds and the Royal Society for the Prevention of Cruelty to Animals assisted in the operation, rescuing and estimating the numbers of oiled seabirds recovered on the shore. Off-shore and in-shore oil dispersing activities were conducted by a fleet of 10 vessels, including the Dover Harbour Board tugs Dominant and Diligent which were equipped and dispatched immediately to the scene of the collision, the tug Calshot from Southampton, two French naval vessels, two Royal Navy vessels, including the Coastal Mine Hunter Bildeston from Lowestoft, and three fishing boats from Folkestone chartered by the Kent County Council. This fleet was directed and co-ordinated by Royal Navy aerial reconnaissance aircraft. Despite considerable success in dispersing larg~ quantities of the oil with the emulsifier BP 1100X, crud~ oil came ashore at high tide on 13 November betweer Sandwich and Kingsdown. The following day more wide spread shoreline pollution occurred between Dover anc Dungeness (Fig. 1). Oil deposition patterns varied with th~ location and nature of particular beach characteristics Sandy, low energy beaches with shallow profiles nea~ Folkestone were extensively covered by a wide band of oi ranging from 100 to 250 m in width, while narrow band: up to 3 m in width but 15-30 cm deep were characteristic o high energy shingle beaches with steeper profiles nea Dover and Deal. The rocky foreshores between Dover ant Folkestone were severely polluted;many of the larger rocl pools were filled with oil (Fig. 2).
Volume 7 / N u m b e r 5 / M a y 1976
a n i n f l a t a b l e b o o m , was only partially successful, as 5001. were removed later by a BP Sea Skimmer Recovery System f r o m the Isle of Grain, North Kent. Once the extent of the shore pollution was known, the duration of the clearance operation was estimated to be two or three weeks. However, a change in the wind direction to off-shore on 16 November pushed remaining '~" Dover Tanker steams away slicks out to sea. With higher tides and larger waves 14 th ~:~'~"'S:~'~I 5t h "~ docking 4 days later (2-4 m), treated oil deposits remaining on the beaches oymc0urc . ,nw,,he,.h. . . . were rapidly emulsified by wave action or buried. By 19 November only scattered weathered residues remained in I ,~t~ estt mated 2 0 0 0 ~ ~ ForI g(~tres ~;Uu rt~ s ;het°~dk~ Os' from the vicinity of untreated rocky areas, although further observations of oil and emulsifier inshore or on the / ~Reported obt slicks ~. beaches were made intermittently for a period of six weeks. Fig. 1 Sequence of events in the Straits of Dover after the collision of The costs for the oil clearance operations were the the tanker OlympicA lliance, 220000 tons dwt, and H M S A chilies, largest to date in the area and a direct result of 350 0001. of a frigate 2500 tons. emulsifier used. A total bill of £65 000 was shared by three sources--the County Council £47 000, Shepway and Unlike previous incidents oil clearance operations were Dover District Councils £8 000 and Central Government restricted or a b a n d o n e d in conservation zones or sites of £10 000. scientific interest, previously designated by the County Authority in conjunction with the Nature Conservancy Effects u p o n Seabirds Council (South East Region). Consequently, the rocky Following the collision, oiled seabirds were sighted over foreshore between Dover and Folkestone was left to recover naturally while oil residues on the sandy beaches in a wide area. An emergency collecting station was the vicinity of Dymchurch and Greatstone were removed established at Dover, where the birds were sorted; the by mechanical methods, thereby minimizingthe disturb- more heavily contaminated and emaciated victims ance to intertidal flora and fauna. Oil clearance ashore humanely destroyed and the remainder dispatched to a was therefore selective, and also limited by the available rehabilitation centre in Sussex. Special beached bird w.orkforce, equipment and access to particular areas. surveys were organized to estimate the total numbers and Shingle beaches were cleaned with the dispersant BP species affected. A small, continuous supply arrived at the 1100X by manual or mechanized units (Fig. 3). Sandy emergency centre from 13 to 18 N o v e m b e r with a beaches were cleaned by burying or removing oil in sand m a x i m u m of 40 on 17 November. However, precise numbers are unknown since details were not recorded deposits both manually and by mechanical diggers. An attempt to prevent oil entering Folkestone H a r b o u r using accurately from beach surveys or at the emergency centre. i~ WFnd vector dnagram ~ "~-Y'~N I, t h - 17 t h N. . . . ber /
4,t.h,~cff
0 I
I0 I
km
20 I
30 I
Fig. 2 Heavily polluted rocky foreshore at Dover.
87
Marine Pollution
Fig. 3 Mechanised
beach spraying
As expected the Auks (Alcidae) were most frequently recorded although the numbers were small since the main dispersing grounds are outside the affected area in November (Table 1). The resident non-breeding Cormorant (Phalacrocorax carbo)population, shown to be supplemented at this time of year with vagrants (Table 2), was particularly affected, as shown by the high proportion of the total population oiled and their scarcity in the area during subsequent observations. Some unexpected species were recovered, including a Brent Goose (Branta bernicla), Tufted Duck (Aythya fuligula)and Coot (Fulicaatra), usually observed oiled on the shore during prolonged periods of colder weather in January and February. Most of the diving birds and the majority of floating debris, particularly containers, were completely covered with a uniform layer of oil, a pattern associated with the effects of previous acute oil spillages in the area (Dixon,
Bulletin
unit (Bazoo) at Dover.
1969). Various types of pollution patterns are still being investigatedbytheauthors. To obtain an accurate assessment of the numbers of oiled seabirds in a sample area, four consecutive weekly shore surveys were conducted between Deal and Sandwich from 16 November. Although the numbers of dead or incapacitated victims were small, approximately 1OOC Gulls (Laridae) were observed with varying degrees of oil contamination but apparently unharmed, a phenomenon noted following a previous oil spillage in the area (Dixon & Estimates
TABLE I of the numbers and species of oiled seabirds.
Species Cormorant Phalacrocorax carbo Brent Goose Branta bernicla Tufted Duck Aythafuligula Common Scoter Melanittanigra Eider Somateria mollissima
Recovered alive and incapacitated
Reported dead
Total
12
6
18
1
Nil
I
3
Nil
3
I
2
3
1
2
3
2
I
3
I
2
3
3
3
6
1
I
2
Nil
4
4
6
2
8
15
16
31
19 57
18 20
37 77
122
77
199
coot
S Sandettie EG East GoodwIn ““v $yt$ Goodwn
I
Boulogne 0
IO ,
20,
30,
4c
km
Fig. 4 Present traffic separation scheme in the Dover Strait and the sites of collisions from its inception on 1 June 1967 to 28 February 1971.
88
Fulica atra Greater Black Backed Gull Larus tnarinus Herring Gull Larus argentatus Common Gull Larus canus Black Headed Gull Larus ridibundus Kittiwake Rissa tridactyla Razorbill Alca torda Guillemot Uris aalge Unidentified Totals
Volume7/Number 5/May 1976 TABLE2 Age and origin of oiled seabirds recoveredringed. Ring number Species
Ringing place
Ringing Recovery Recovery date date place
506.8704 Cormorant St. Margaret's 28.6.75 18.11.75 Dover Island, Tenby, (Kent) Pembrokeshire, U.K. 505.9680 Cormorant St. Margaret's 28.6.75 18.11.75 Dover Island, Tenby, (Kent) Pembrokeshire, U.K. Dixon, 1971). In most cases the extent of contamination was slight, confined to superficial blobs on ventral surfaces and the head. Observations indicated this pattern originated from contact with beached oil deposits rather than oil in water emulsions observed in other areas (Bourne & Bibby, 1975). In the absence of corpses and continuous reduction in the numbers of relative proportions of birds observed oiled during subsequent observations (Table 3) it would appear that many cleaned themselves by preening, without apparent harmful effects, as demonstrated by other authors (Birkhead, etal., 1973). The press reported oil damage to local inshore fishery equipment and a possible closedown of the Dungeness Nuclear Power Stations had oil entered intakes to seawater cooling systems. Pending the outcome of investigations and postoperational reports by the Ministry of Defence (Royal Navy), the Department of Trade and Industry, and the Liberian Government, the cause of the collision is unknown. However, one or both of the vessels may have been taking evasive action to avoid a collision with one or more 'rogue' ships in the incorrect sea lane. A radar film of these events was recorded by the St. Margaret's Bay Coastguard Station, one of two purpose built radar tracking systems monitoring shipping movements in the Straits of Dover. From the available data (Grimes, 1971) there has been no apparent improvement in the collision rate since the introduction of the traffic separation scheme. These events add to the controversy over shipping routes through the Dover Strait. At present there are several faults with the system. The scheme is advisory and not compulsory, therefore there are a number of vessels that ignore recommendations and have the right to do so. This in turn endangers vessels adhering to the routing scheme and in some cases may be responsible for causing collisions (Dixon, 1972). Since the scheme has been introduced, the size, draught and number of ships using the Dover Strait has exceeded forecasts. Consequently, TABLE3 Proportions of Gull populations observedoiledduring four consecutiveweeklycounts between Dealand Sandwich. (% Total numbersobserved) Greater Black BackedGull (Larusmarinus) Herring Gull (Larusargentatus) CommonGull (Laruscanus) Black Headed Gull (Larus ridibundus)
38 (80) 26 (550) 31 (25) 28 (250)
21 (35) 12 (200) 17 (11) 9 (90)
(Figures in brackets refer to sample numbers.)
7 (8) 4 (60) Nil
Nil
2 (25)
1 (4)
1 (6) Nil
the obligation on these ships to manoeuvre in relatively confined and shallow waters is creating a serious hazard, not only to themselves, but to all other craft using the Strait. Until coastal states can promulgate a comprehensive navigational code for these waters, the collision and pollution risk will remain high, especially where routes converge or cross (Anon, 1972,1975). This can be substantiated by the frequency of acute oil spillages resulting in extensive coastal pollution on Kent beaches between January 1963 and December 1975, the majority of incidents occurring since March 1969 (Dixon, 1969; Dixon & Dixon, 1971 ; Tittley, 1971). The organization for rescuing and counting oiled seabirds was shown to be only partially effective. Fortunately the numbers recovered were small and voluntary assistance available from press and television appeals for help. This spillage was of sufficient size to thoroughly test the existing oil clearance organization. Despite extensive beach pollution the seaborne operation was effective, although hampered by short daylight hours, poor visibility, gale force winds and the strong tidal and residual water movements experienced in these waters (Carruthers, 1925; Cartwright, 1961). However, criticisms have been made concerning the ability of seaborne operations to prevent extensive coastal pollution in the area. Tanker collisions or groundings to date have involved either small losses of fuel oil from empty tankers (Texaco Caribbean 1000 tonnes) or minor cargolosses from fully laden vessels (Panther, 11 tonnes). However, extensive coastal pollution resulted from each incident, although offshore dispersing operations tried to prevent it. The risk of further coastal pollution remains high, since the distribution pattern for recent collision sites indicates a concentration in the southbound sea lane close to the English coastline (Fig. 4). In the preparation of this manuscript comments were received from the Department of Trade and Industry (Marine Division), Kent County Council, Royal Society for the Protection of Birds, Royal Society for the Preventionof Cruelty to Animals, Department of the Environment and the Nature Conservancy Council. Assistance with estimates of oiled seabirds was received from D. Smith and the Sandwich Bay Bird Observatory. T. J. D I X O N T. R. D I X O N Oil Pollution South East Kent Ashburnham, Green Lane, Temple Ewell, Nr. Dover, Kent, C T 1 6 3 A S , U.K.
Anon (1972). Law of the sea. Mar. Pollut. Bull., 3, 19. Anon (1975). Sea traffic control. Mar. Pollut. Bull. 6, 33-35. Birkhead, T. R., Lloyd,C. & Corkill, P. (1973). Oiledbirds successfully cleaning their plumage. Brit. Birds, 66, 535-537. Bourne, W. R. P. & Bibby, C. J. (1975). Temperature and the seasonal and geographical occurrenceof oiled birds on West European Beaches. Mar. Pollut. BulL,6, 77-80. 89
Marine Pollution Bulleti~
Carruthers, J. N. (1925). The water movement in the neighbourhood of the English Channel-North Sea Junction. J. m a r BioL Ass., UK 13,665. Cartwright, D. E. (1961). A study of currents in the Strait of Dover. J. Inst. Navig., 14, 130-151. Dixon, T. J. (1972). Another Collision in the English Channel. Mar. Pollut. Bull., 3,180. Dixon, T. R. (1969). Oil Pollution South East Kent, Report 1968-1969. Mar. Pollut. Bull., Series 1, 13, 9-13.
Dixon, T. R. & Dixon, T. J. (1971). The Panther affair. Mar. Pollut Bull., 2,107-108. Grimes, C. (1971). A survey of marine accidents involving oil pollutioJ and other dangers from hazardous cargoes. Defence Operationa Analysis Establishment. Report 7103. Project DL 14/01 (Ministry of Defence, London). Tinker, J. (1975). The case of the vanishing vessel. N e w Scientist 20 November 1975. Tittley, I. (1972). Kent Coast in i971. Mar. Pollut. Bull., 3, 135-138.
Transport of Mercury Through a Laboratory Two-level Marine Food Chain Algal cultures grown in the presence of 164 ~g/I mercury as mercuric chloride acquired and retained about half of the mercury. When the algae which had been grown in the presence of mercury were fed to planktonic copepods: (1) egg-laying rate showed no significant change; (2) eggs of a female fed mercury-enriched algae hatched, and nauplii moulted to apparently normal copepodites while in contact with spiked algae, and (3) analysis of the algae/copepod system showed that neither the copepods nor their eggs and faeces retained mercury in detectable amounts. At least in the one simple f o o d chain, although mercury was concentrated by the algae, the mercury was not passed up the chain to the next trophic level. It has often been intimated that the concentration of a heavy trace metal such as mercury would be increased at each trophic level in the food chain. Recent analyses of naturally occurring populations (Leatherland et al., 1973) have tended to cast doubt upon this paradigm, but the low levels of mercury existing in ocean waters as well as the complexity of the interactions in a naturally occurring food web have made firm conclusions difficult to draw. We have chosen to examine a simple system consisting of the primary algal producer Croomonas salina, and the second level omnivorous calanoid copepod Acartia tonsa Dana. Culturing techniques and analytical practices have been previously described by Zillioux & Wilson (1966) and Carr et al. (1972). In the first stage of the experiment, we grew the algae in an enriched culture, spiked with 5000 ng of mercury (conc. = 164~g/1) as mercuric chloride• Within 48 h, about half the mercury associated with the algae cells, some was deposited on the culture tube walls, and the remainder stayed in solution (Fig. 1). At this time the algae contained 1400 p p m Hg by dry weight. This should be compared with a range of 0.1-10 p p m reported by W i n d o m (1973) for Atlantic coastal plankton and 0.1-0.7 ppb for Pacific pelagic phytoplankton reported by Knauer & Martin (1972). Notice (Fig. 1) that our mass balances allowed us to identify about 95°70 of the 5000 ng of mercury added. The second stage of the study involved feeding portions of mercury-rich algae to female copepods on two separate occasions. Individual females were transferred and fed, and egg counts were recorded at the end of every 24-h period. We observed that when mercury-enriched algae were kept in test solution for 24 h without copepods, the 90
mercury remained associated with the algae and did no redistribute. In the first experiment, after a five-da~ control period, mercury-spiked algae were fed to 1! copepods at a concentration of 1400 p p m Hg by dry weigh algae• Six controls were fed unspiked algae for the entin period. In the second experiment, 8 females were fed concentration of 1800 p p m Hg, and 3 control females wer, used. In both copepod experiments, during the 5-da,. period when spiked algae were fed, we noted no significan difference between the mean egg laying rates of th, experimental females when compared to the controls ( test; 0.1 • P :- 0.05)• Other research (Wilson & Parrish, ii prep.) has shown that conditions of stress affect this rate The contents of the culture dishes were analysed after on, 24-h period. Figure 2 shows the distribution found During this contact time, the minimum amount of alga, thecopepods ingested averaged 5 x 10 ~ cells per day. Thi :
I00
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Fig. 1 Distribution of mercury (5000 ng) as function of time. Figure 1 represents a cumulative graph in which % Hg associated wit algal ceils, solution, culture tube walls, and losses, is indicated b the area between the curves.