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Acute toxicity of copper to a copepod
Marine Pollution Bulletin
species of copepods. No effects of Oil Killer were registered on these organisms. As already mentioned the experiments in TromsO were different in design from those performed in Naples. Moreover, the external conditions, and particularly the temperature, differed considerably from those found in the Mediterranean. The time factor is also quite different in Troms0 and Naples. In Troms0 the experiments often lasted for a week whereas the Naples experiments were completed within 48 h. Nevertheless, the results with Oil Killer were uniform on the two widely separated localities and no grave toxic effects were ever recorded.
HagstrOm, B. E. & LOnning, S. (1973). The sea urchin egg as a testing object in toxicology. Acta Pharmac. ToxicoL, 32, Suppl. 1, 1-49. Latiff, S. A. (1969). Preliminary results of the experiments on the toxicity of oil counteracting agent (Esso Corexit 7664), with and without Iraq crude oil, for selected members of marine plankton. Arch. Fisch Wiss., 20, 182-185. LOnning, S. (1977). The effects of crude Ekofisk oil and oil products on marine fish larvae. Astarte, 10, 3 7 - 4 7 . LOnning, S. & HagstrOm, B. E. (1975). The effects of crude oils and the dispersant Corexit 866,7, on sea urchin gametes and embryos. Norw. J. ZooL, 23, 121-129. L0nning, S. & HagstrOm, B. E. (1976). Deleterious effects of Corexit 9527 on fertilization and development. 3,far. Pollut. BulL, 7, 124-127. Sprague, J. B, & Carson, W. G. (1970). Toxicity tests with oil dispersants in connection with oil spill at Chedabucto Bay, Nova Scotia. Fish. Res. Bd Can. Techn. Rep. no. 201.
HagstrOm, B. E, & HagstrOm, B. (1959). The effect of decreased and increased temperatures'on fertilization. Exp. CellRes., 16, 174-183.
Marine Pollution Bulletin, Vol. 9, pp. 278-280 Pergamon Press t.td. 1978. Printed in Great Britain
Acute Toxicity of Copper to a Copepod M. MORAITOU-APOSTOLOPOULOU Zoological Laboratory, University of A thens, Greece The acute toxicity of copper to the marine copepod Acartia clausi was determined by means of static bioassays. Natural copepod assemblages from two different locations, one from an area polluted with industrial effluents and domestic wastes and another from a relatively uncontaminated area, were compared. Results of metal toxicity tests expressed as 48 h LCs0 values indicate a significant difference in the tolerance of copper between the two populations, with the LCso of the pollution-adapted population higher than that of the population from the uncontaminated area.
The effects of heavy metals on aquatic organisms is currently attracting widespread attention, particularly in studies related to industrial pollution. The establishment of critical concentrations of metal ion pollutants in aquatic systems by bioassay techniques is necessary in determining 'acceptable' levels of pollution. The use of copper in antifouling paint, in the treatment of diseases of fishes and as an algicide, increases the interest in the effects of this metal on aquatic organisms. The most extensive research on the effects of copper has been directed mostly to fishes because of their economic value. There are still only few data for the marine zooplankton, although their small size, and hence sensitivity, suggest their choice as bioassay organisms. The burden of marine pollution is first and most intensively felt in coastal waters, adjacent to the major sources of pollution activities, so animals from these regions are particularly suitable for such studies. In this paper the effect of copper on the survival of the marine copepod Acartia clausi, collected from two differently polluted areas of the Saronic Gulf, has been studied. 278
The Saronic Gulf (Gulf of Athens) is part of the south Aegean Sea (Fig. I). Due to the economic, industrial and social importance of the surrounding coast, the Gulf has become an area of particular interest in Greece. The northern part (Elefsis Bay-Keratsini) is subject to a high degree of pollution because of the industrial wastes and hydrocarbon products discarded from a flourishing industry around the bay and the large quantities of organic matter discharged at Keratsini from the main sewage outfall of the cities of Athens and Piraeus. Previous planktological studies conducted at Keratsini indicate that this point experiences primary organic pollution (Moraitou-Apostolopoulou, in press), and high concentrations of trace elements in Elefsis Bay sediments have been recently reported (Grimanis et al., 1976). Research on the content of sediments of Saronic Gulf (Pavlou & Dexter, 1973) and also planktological studies (Moraitou-Apostolopoulou, 1974, 1976; Kiortsis & Moraitou-Apostolopoulou, 1975; MoraitouApostolopoulou & Kiortsis, 1976) have shown that although the northern part of the Gulf is heavily polluted, southwards the influence of pollution sources is reduced and the south Saronic Gulf can be considered as a relatively clear area. Material and Methods
Acartia clausi is a calanoid copepod common in the Mediterranean. Frequent but not abundant in the Aegean Sea (Moraitou-Apostolopoulou, 1972), it increases in numbers in the Saronic Gulf, representing 50°70 of the total numbers of copepods (MoraitouApostolopoulou, 1974). This species also presents a very clear regional distribution. Inside Elefsis Bay it forms
Volume 9 / N u m b e r 10/October 1978
\
Saponlc Gulf
)
~'~'~
Fig, 1 The sampling area and collection stations.
very dense populations being the almost exclusive component of the zooplankton. This extreme abundance of Acartia in polluted areas has been mentioned by other authors (Citarella, 1973; Guglielmo, 1973) so that the species is currently considered as a pollution-adapted or even pollution indicator species. To test the toxicity of copper to Acartia clausi we used specimens belonging to a population living at the heavily polluted area of Elefsis Bay and specimens from a relatively uncontaminated area 25 km southwards. Static bioassays were conducted in order to determine the acute toxicity of copper in the form of copper sulphate (CuSO4.5H20) to the copepod. The experiments were conducted in four series extended from 10 October to 31 November 1977. The Acartia were exposed to a range of concentrations of the toxicant for a period of 96 h. The toxicant was added to Millipore filtered and autoclaved seawater from a freshly prepared stock solution of copper sulphate to obtain final concentrations of: 1; 0.5; 0.1; 0.05; 0.025; and 0.01 mg Cu 171 All experiments were conducted in constant temperature rooms at 18°C. Six phytoplankton species taken from monospecific cultures were used as food. The calculated density of the phytoplankton population did not exceed 2000 cells ml -I . For each concentration of the toxicant and for each one of the two populations 20 animals were placed individually in 50 ml of solution in 20 glass copels covered with aluminium foil sheets. The test solutions were renewed on alternate days. Ten copels without copper served as controls. The copels were checked daily for survivors. An animal was considered to be dead when it ceased to move and it no longer responded to mechanical stimulation. Forty-eight hours LCs0 values (concentration of a toxicant lethal to 50°70 of the test animals after 48 h exposure) were determined. The experimental results give two limit values between which the real lethal concentration is placed. In order to obtain an accurate
result we used Bliss's (1938) modified mathematical method.
Results The toxicity of copper to Acartia is presented in Table 1. The 48 h LCs0 for populations from the uncontaminated area is 0.034 + 0.0044 and from the polluted area is 0.082 + 0.0026 mg 1_ l Reeve et al. (1977) calculated the overall 96 h LCs0 of a zooplankton population consisting mainly of Temora, Paracalanus and Acartia from three different locations, 52, 45 and 60/~g 1:l, respectively. All the quoted toxicant levels of copper are nominal values because hydrolysis and precipitation dominate the chemistry of copper. The most significant process by which free copper is removed is by precipitation (malachite formation), and Reeve et al. (1977) found that even soon after the addition, measurable copper was only 50-75 °70 of that added. It is generally believed that only free copper is toxic to aquatic organisms. This is however too exclusive. The toxicities of particulate copper, biotically and abiotically absorbed copper and free inorganically and organically complexed copper, all need to be assessed before conclusions can be drawn (Sylva, 1976). The toxicity of copper is also influenced by environmental factors such as dissolved oxygen, temperature, turbidity, carbon dioxide, phosphate and magnesium salts, organic compounds, etc. (McKee & Wolf, 1963; D o u d o u r o f f & Katz, 1953; Bender etal., 1970). In all the experiments the 48 h LCs0 values show significant differences in tolerance between animals from the two regions, with a higher tolerance in pollutionadapted Acartia from Elefsis. Brown (1976) reports increased tolerance to copper and lead of the marine isopod Asellus meridianus living in regions receiving drainage from disused copper and tin mines. The type of adaptation either phenotypic or genotypic is of 279
Marine Pollution Bulletin
TABLE l Percentage of mortality of Acartia ctausi in different concentrations of copper.
Concentrations of copper (rag 17 ~) Duration of exposure (h)
1
0.5
0.1
0.05
0.025
0.01
Uncontaminated area 24 48 72 96
100 100 100 100
60 95 100 100
40 85 96 100
28 82 94 100
15 47 68 80
15 29 72 79
Polluted area 24 48 72 96
31 92 100 I00
25 56 87 100
14 51 70 95
0 40 61 100
0 36 62 100
0 25 52 80
particular importance. Brown (1976) noticed that tolerance to lead persists in animals of the F3 generation which have been cultured in the laboratory and considers it an evidence that metal tolerance could be a genetic factor. Bryan & Hummerstone (1971) showed that copper tolerance in the polychaete Nereis diversicolor was not easily lost by worms exposed to uncontaminated sediments and from this observation they also inferred that the adaptation may be genetically controlled. It seems possible that this phenomenon may be due to genetic selection over several generations. Survival is the best index of a copper stress since it proved as, or more sensitive than any of the other indices and also is the least variable (Winner & Farrell, 1970). However, in order to have a more complete idea of the toxicity of copper to Acartia, and also to verify the observed differences of tolerance, research on the sublethal effects of copper (respiration, longevity, nutrition, fertility) is now in progress. The study was conducted in the zoological laboratory of the University of Athens as part of Med. IV research p r o g r a m m e of the UNEP. I wish to thank the Director of the Laboratory, Professor V. Kiortsis for kind advices and criticism and Dr. G. Verriopoulos for the collection of the animals and aid during experimental procedure. Bliss, C. 1. (1938). The determination of the dosage mortality curve from small numbers. Q. J. Pharm., I1,192-216.
Tanker Safety and Pollution Prevention A Joint Conference on 'The Effect of the 1978 IMCO Tanker Safety and Pollution Prevention Conference on Ship Design and Operation' arranged by The Royal Institution of Naval Architects and The Institute of 280
Bender, M. E., Matson, W. R. & Jordan, R. A. (1970). On the significance of metal complexing agents in secondary sewage effluents. J. Environ. Sci. TechnoL, 4 , 5 2 0 - 5 2 1 . Brown, B. (1976). Observations on the tolerance of the Isopod Asellus meridianus Rac. to copper and lead. ['Vat. Res., 1 0 , 5 5 5 - 5 5 9 . Bryan, G. W. & H u m m e r s t o n e , L. G. (1971). Adaptation of the potychaete Nereis diversieolor to estuarine sediments containing high concentrations of zinc and cadmium. J. mar. biol. Ass. U.K., 53, 839-843. Bryan, G. W. & H u m m e r s t o n e , L. G. (1971). Adaptation of the polychaete Nereis diversicolor to estuarine sediments containing high concentrations of heavy metals. I. General observation and adaptations to copper. J. mar. bioL Ass. U.K., 5 1 , 2 0 7 - 2 1 7 . Citarella, G. (1973). Zooplankton and pollution. Cab. Biol. mar., 14, 57 - 6 3 . Doudouroff, P. & Katz, M. (1953). Critical review of literature on the toxicity of industrial wastes and their components to fish. 11. The metals and salts. Sewage ind. Wastes, 2 5 , 8 0 2 - 8 3 9 . Grimanis, A. P., Vassilaki-Grimani, M. & Griggs, G. B. (1976). Pollution studies of trace elements in sediments from the upper Saronikos Gulf, Greece. Proc. Int. Conf. on Modern Trends in Activation Analysis, Mtinchen, 1 September 1976, pp. 675-684. Guglielmo, L. (1973). Distribuzione quantitativa dello zooplancton in aree portuali inquinate della Sicilia orientale (Millazzo ed Augusta). A ttidel50 ColL Int. Oceanogr. med. Messina, 392-422. Kiortsis, V. & M o r a i t o u - A p o s t o l o p o u l o u , M. (1975). Marine Cladoceran (Crustacea) in the eutrophicated and polluted Saronic Gulf(Greece). lsraelJ. ZooL, 24, 7 1-74. McKee, J. E. & Wolf, H. W. (1963). Water quality criteria. 2nd Edn. Publication No. 3-A. Resources Agency of California, Sacramento. Moraitou-Apostolopoulou, M. (1972). Occurrence and fluctuation of the pelagic Copepods of the Aegean Sea with some notes on their ecology. H e l l Ocean. Limn., I!, 325-402. Moraitou-Apostolopoulou, M. (1974). An ecological approach to the systematic study of planktonic Copepods in a polluted area (Saronic Gulf, Greece). Boll Pesca Piscic. Idrobiol., 29, 2 9 - 4 7 . Moraitou-Apostolopoulou, M. (1976). Etude comparative du zooplancton super ficiel (0-100 cm) a une zone hautement pollu6e et une autre relativement propre (golfe Saronique-Grece). Rapp. C o m m . int. M e r Medit., 23, 59-60. Moraitou-Apostolopoulou, M. (in press). Contribution a la systematique et ecologie du zooplancton de surface (0-100 cm) dans une zone pollu6e. Moraitou-Apostolopoulou, M. & Kiortsis, V. (1976). Etude comparative des Cladoc~res du premier metre de l'eau de mer recueillis dans une zone polluee et dans une a autre relativement propre. Rev. Int. Oceanogr. Med., 43, 3 7 - 4 5 . Pavlou, S. P. & Dexter, R. N. (1973). Distribution patterns of chlorinated hydrocarbons in sediments from southern Greece. Presented at the A. Int. Syrup. o f Greek Scientists, Athens, 2 2 - 3 0 August. Reeve, M. R., Walter, M. A., Dareg, K. & Ikeda, T. (1977). Evaluation of potential indicators of sublethal toxic stress on marine zooplankton (feeding, fecundity, respiration and excretion). Controlled ecosystem pollution experiment. Bull. mar. Sci., 24, 105-113. Sylva, R. N. (1976). The environmental chemistry of copper (ll) in aquatic systems. Wat. Res., 10, 789-792. Winner, R. W. & Farrell, M. P. (1976). Acute and chronic toxicity of copper to four species of Daphnia. J. Fish Res. Bd Can., 33, 1685-1691.
Marine Engineers will be held on 7 December 1978 at the Institute Conference Centre, 76 Mark Lane, London EC3R 7JN. The conference will discuss problems facing shipowners resulting from the IMCO Conference involving ship design and operation, safety, pollution prevention, segregated ballast, cargo pumping systems, crude oil washing, steering gear, the structural design of ships, inspection and certification.
species of copepods. No effects of Oil Killer were registered on these organisms. As already mentioned the experiments in TromsO were different in design from those performed in Naples. Moreover, the external conditions, and particularly the temperature, differed considerably from those found in the Mediterranean. The time factor is also quite different in Troms0 and Naples. In Troms0 the experiments often lasted for a week whereas the Naples experiments were completed within 48 h. Nevertheless, the results with Oil Killer were uniform on the two widely separated localities and no grave toxic effects were ever recorded.
HagstrOm, B. E. & LOnning, S. (1973). The sea urchin egg as a testing object in toxicology. Acta Pharmac. ToxicoL, 32, Suppl. 1, 1-49. Latiff, S. A. (1969). Preliminary results of the experiments on the toxicity of oil counteracting agent (Esso Corexit 7664), with and without Iraq crude oil, for selected members of marine plankton. Arch. Fisch Wiss., 20, 182-185. LOnning, S. (1977). The effects of crude Ekofisk oil and oil products on marine fish larvae. Astarte, 10, 3 7 - 4 7 . LOnning, S. & HagstrOm, B. E. (1975). The effects of crude oils and the dispersant Corexit 866,7, on sea urchin gametes and embryos. Norw. J. ZooL, 23, 121-129. L0nning, S. & HagstrOm, B. E. (1976). Deleterious effects of Corexit 9527 on fertilization and development. 3,far. Pollut. BulL, 7, 124-127. Sprague, J. B, & Carson, W. G. (1970). Toxicity tests with oil dispersants in connection with oil spill at Chedabucto Bay, Nova Scotia. Fish. Res. Bd Can. Techn. Rep. no. 201.
HagstrOm, B. E, & HagstrOm, B. (1959). The effect of decreased and increased temperatures'on fertilization. Exp. CellRes., 16, 174-183.
Marine Pollution Bulletin, Vol. 9, pp. 278-280 Pergamon Press t.td. 1978. Printed in Great Britain
Acute Toxicity of Copper to a Copepod M. MORAITOU-APOSTOLOPOULOU Zoological Laboratory, University of A thens, Greece The acute toxicity of copper to the marine copepod Acartia clausi was determined by means of static bioassays. Natural copepod assemblages from two different locations, one from an area polluted with industrial effluents and domestic wastes and another from a relatively uncontaminated area, were compared. Results of metal toxicity tests expressed as 48 h LCs0 values indicate a significant difference in the tolerance of copper between the two populations, with the LCso of the pollution-adapted population higher than that of the population from the uncontaminated area.
The effects of heavy metals on aquatic organisms is currently attracting widespread attention, particularly in studies related to industrial pollution. The establishment of critical concentrations of metal ion pollutants in aquatic systems by bioassay techniques is necessary in determining 'acceptable' levels of pollution. The use of copper in antifouling paint, in the treatment of diseases of fishes and as an algicide, increases the interest in the effects of this metal on aquatic organisms. The most extensive research on the effects of copper has been directed mostly to fishes because of their economic value. There are still only few data for the marine zooplankton, although their small size, and hence sensitivity, suggest their choice as bioassay organisms. The burden of marine pollution is first and most intensively felt in coastal waters, adjacent to the major sources of pollution activities, so animals from these regions are particularly suitable for such studies. In this paper the effect of copper on the survival of the marine copepod Acartia clausi, collected from two differently polluted areas of the Saronic Gulf, has been studied. 278
The Saronic Gulf (Gulf of Athens) is part of the south Aegean Sea (Fig. I). Due to the economic, industrial and social importance of the surrounding coast, the Gulf has become an area of particular interest in Greece. The northern part (Elefsis Bay-Keratsini) is subject to a high degree of pollution because of the industrial wastes and hydrocarbon products discarded from a flourishing industry around the bay and the large quantities of organic matter discharged at Keratsini from the main sewage outfall of the cities of Athens and Piraeus. Previous planktological studies conducted at Keratsini indicate that this point experiences primary organic pollution (Moraitou-Apostolopoulou, in press), and high concentrations of trace elements in Elefsis Bay sediments have been recently reported (Grimanis et al., 1976). Research on the content of sediments of Saronic Gulf (Pavlou & Dexter, 1973) and also planktological studies (Moraitou-Apostolopoulou, 1974, 1976; Kiortsis & Moraitou-Apostolopoulou, 1975; MoraitouApostolopoulou & Kiortsis, 1976) have shown that although the northern part of the Gulf is heavily polluted, southwards the influence of pollution sources is reduced and the south Saronic Gulf can be considered as a relatively clear area. Material and Methods
Acartia clausi is a calanoid copepod common in the Mediterranean. Frequent but not abundant in the Aegean Sea (Moraitou-Apostolopoulou, 1972), it increases in numbers in the Saronic Gulf, representing 50°70 of the total numbers of copepods (MoraitouApostolopoulou, 1974). This species also presents a very clear regional distribution. Inside Elefsis Bay it forms
Volume 9 / N u m b e r 10/October 1978
\
Saponlc Gulf
)
~'~'~
Fig, 1 The sampling area and collection stations.
very dense populations being the almost exclusive component of the zooplankton. This extreme abundance of Acartia in polluted areas has been mentioned by other authors (Citarella, 1973; Guglielmo, 1973) so that the species is currently considered as a pollution-adapted or even pollution indicator species. To test the toxicity of copper to Acartia clausi we used specimens belonging to a population living at the heavily polluted area of Elefsis Bay and specimens from a relatively uncontaminated area 25 km southwards. Static bioassays were conducted in order to determine the acute toxicity of copper in the form of copper sulphate (CuSO4.5H20) to the copepod. The experiments were conducted in four series extended from 10 October to 31 November 1977. The Acartia were exposed to a range of concentrations of the toxicant for a period of 96 h. The toxicant was added to Millipore filtered and autoclaved seawater from a freshly prepared stock solution of copper sulphate to obtain final concentrations of: 1; 0.5; 0.1; 0.05; 0.025; and 0.01 mg Cu 171 All experiments were conducted in constant temperature rooms at 18°C. Six phytoplankton species taken from monospecific cultures were used as food. The calculated density of the phytoplankton population did not exceed 2000 cells ml -I . For each concentration of the toxicant and for each one of the two populations 20 animals were placed individually in 50 ml of solution in 20 glass copels covered with aluminium foil sheets. The test solutions were renewed on alternate days. Ten copels without copper served as controls. The copels were checked daily for survivors. An animal was considered to be dead when it ceased to move and it no longer responded to mechanical stimulation. Forty-eight hours LCs0 values (concentration of a toxicant lethal to 50°70 of the test animals after 48 h exposure) were determined. The experimental results give two limit values between which the real lethal concentration is placed. In order to obtain an accurate
result we used Bliss's (1938) modified mathematical method.
Results The toxicity of copper to Acartia is presented in Table 1. The 48 h LCs0 for populations from the uncontaminated area is 0.034 + 0.0044 and from the polluted area is 0.082 + 0.0026 mg 1_ l Reeve et al. (1977) calculated the overall 96 h LCs0 of a zooplankton population consisting mainly of Temora, Paracalanus and Acartia from three different locations, 52, 45 and 60/~g 1:l, respectively. All the quoted toxicant levels of copper are nominal values because hydrolysis and precipitation dominate the chemistry of copper. The most significant process by which free copper is removed is by precipitation (malachite formation), and Reeve et al. (1977) found that even soon after the addition, measurable copper was only 50-75 °70 of that added. It is generally believed that only free copper is toxic to aquatic organisms. This is however too exclusive. The toxicities of particulate copper, biotically and abiotically absorbed copper and free inorganically and organically complexed copper, all need to be assessed before conclusions can be drawn (Sylva, 1976). The toxicity of copper is also influenced by environmental factors such as dissolved oxygen, temperature, turbidity, carbon dioxide, phosphate and magnesium salts, organic compounds, etc. (McKee & Wolf, 1963; D o u d o u r o f f & Katz, 1953; Bender etal., 1970). In all the experiments the 48 h LCs0 values show significant differences in tolerance between animals from the two regions, with a higher tolerance in pollutionadapted Acartia from Elefsis. Brown (1976) reports increased tolerance to copper and lead of the marine isopod Asellus meridianus living in regions receiving drainage from disused copper and tin mines. The type of adaptation either phenotypic or genotypic is of 279
Marine Pollution Bulletin
TABLE l Percentage of mortality of Acartia ctausi in different concentrations of copper.
Concentrations of copper (rag 17 ~) Duration of exposure (h)
1
0.5
0.1
0.05
0.025
0.01
Uncontaminated area 24 48 72 96
100 100 100 100
60 95 100 100
40 85 96 100
28 82 94 100
15 47 68 80
15 29 72 79
Polluted area 24 48 72 96
31 92 100 I00
25 56 87 100
14 51 70 95
0 40 61 100
0 36 62 100
0 25 52 80
particular importance. Brown (1976) noticed that tolerance to lead persists in animals of the F3 generation which have been cultured in the laboratory and considers it an evidence that metal tolerance could be a genetic factor. Bryan & Hummerstone (1971) showed that copper tolerance in the polychaete Nereis diversicolor was not easily lost by worms exposed to uncontaminated sediments and from this observation they also inferred that the adaptation may be genetically controlled. It seems possible that this phenomenon may be due to genetic selection over several generations. Survival is the best index of a copper stress since it proved as, or more sensitive than any of the other indices and also is the least variable (Winner & Farrell, 1970). However, in order to have a more complete idea of the toxicity of copper to Acartia, and also to verify the observed differences of tolerance, research on the sublethal effects of copper (respiration, longevity, nutrition, fertility) is now in progress. The study was conducted in the zoological laboratory of the University of Athens as part of Med. IV research p r o g r a m m e of the UNEP. I wish to thank the Director of the Laboratory, Professor V. Kiortsis for kind advices and criticism and Dr. G. Verriopoulos for the collection of the animals and aid during experimental procedure. Bliss, C. 1. (1938). The determination of the dosage mortality curve from small numbers. Q. J. Pharm., I1,192-216.
Tanker Safety and Pollution Prevention A Joint Conference on 'The Effect of the 1978 IMCO Tanker Safety and Pollution Prevention Conference on Ship Design and Operation' arranged by The Royal Institution of Naval Architects and The Institute of 280
Bender, M. E., Matson, W. R. & Jordan, R. A. (1970). On the significance of metal complexing agents in secondary sewage effluents. J. Environ. Sci. TechnoL, 4 , 5 2 0 - 5 2 1 . Brown, B. (1976). Observations on the tolerance of the Isopod Asellus meridianus Rac. to copper and lead. ['Vat. Res., 1 0 , 5 5 5 - 5 5 9 . Bryan, G. W. & H u m m e r s t o n e , L. G. (1971). Adaptation of the potychaete Nereis diversieolor to estuarine sediments containing high concentrations of zinc and cadmium. J. mar. biol. Ass. U.K., 53, 839-843. Bryan, G. W. & H u m m e r s t o n e , L. G. (1971). Adaptation of the polychaete Nereis diversicolor to estuarine sediments containing high concentrations of heavy metals. I. General observation and adaptations to copper. J. mar. bioL Ass. U.K., 5 1 , 2 0 7 - 2 1 7 . Citarella, G. (1973). Zooplankton and pollution. Cab. Biol. mar., 14, 57 - 6 3 . Doudouroff, P. & Katz, M. (1953). Critical review of literature on the toxicity of industrial wastes and their components to fish. 11. The metals and salts. Sewage ind. Wastes, 2 5 , 8 0 2 - 8 3 9 . Grimanis, A. P., Vassilaki-Grimani, M. & Griggs, G. B. (1976). Pollution studies of trace elements in sediments from the upper Saronikos Gulf, Greece. Proc. Int. Conf. on Modern Trends in Activation Analysis, Mtinchen, 1 September 1976, pp. 675-684. Guglielmo, L. (1973). Distribuzione quantitativa dello zooplancton in aree portuali inquinate della Sicilia orientale (Millazzo ed Augusta). A ttidel50 ColL Int. Oceanogr. med. Messina, 392-422. Kiortsis, V. & M o r a i t o u - A p o s t o l o p o u l o u , M. (1975). Marine Cladoceran (Crustacea) in the eutrophicated and polluted Saronic Gulf(Greece). lsraelJ. ZooL, 24, 7 1-74. McKee, J. E. & Wolf, H. W. (1963). Water quality criteria. 2nd Edn. Publication No. 3-A. Resources Agency of California, Sacramento. Moraitou-Apostolopoulou, M. (1972). Occurrence and fluctuation of the pelagic Copepods of the Aegean Sea with some notes on their ecology. H e l l Ocean. Limn., I!, 325-402. Moraitou-Apostolopoulou, M. (1974). An ecological approach to the systematic study of planktonic Copepods in a polluted area (Saronic Gulf, Greece). Boll Pesca Piscic. Idrobiol., 29, 2 9 - 4 7 . Moraitou-Apostolopoulou, M. (1976). Etude comparative du zooplancton super ficiel (0-100 cm) a une zone hautement pollu6e et une autre relativement propre (golfe Saronique-Grece). Rapp. C o m m . int. M e r Medit., 23, 59-60. Moraitou-Apostolopoulou, M. (in press). Contribution a la systematique et ecologie du zooplancton de surface (0-100 cm) dans une zone pollu6e. Moraitou-Apostolopoulou, M. & Kiortsis, V. (1976). Etude comparative des Cladoc~res du premier metre de l'eau de mer recueillis dans une zone polluee et dans une a autre relativement propre. Rev. Int. Oceanogr. Med., 43, 3 7 - 4 5 . Pavlou, S. P. & Dexter, R. N. (1973). Distribution patterns of chlorinated hydrocarbons in sediments from southern Greece. Presented at the A. Int. Syrup. o f Greek Scientists, Athens, 2 2 - 3 0 August. Reeve, M. R., Walter, M. A., Dareg, K. & Ikeda, T. (1977). Evaluation of potential indicators of sublethal toxic stress on marine zooplankton (feeding, fecundity, respiration and excretion). Controlled ecosystem pollution experiment. Bull. mar. Sci., 24, 105-113. Sylva, R. N. (1976). The environmental chemistry of copper (ll) in aquatic systems. Wat. Res., 10, 789-792. Winner, R. W. & Farrell, M. P. (1976). Acute and chronic toxicity of copper to four species of Daphnia. J. Fish Res. Bd Can., 33, 1685-1691.
Marine Engineers will be held on 7 December 1978 at the Institute Conference Centre, 76 Mark Lane, London EC3R 7JN. The conference will discuss problems facing shipowners resulting from the IMCO Conference involving ship design and operation, safety, pollution prevention, segregated ballast, cargo pumping systems, crude oil washing, steering gear, the structural design of ships, inspection and certification.