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Bacterial pollution of the Bristol channel
Laboratory study In early work upon this effluent during 1969, the precautions described by Perkins (1972a, b) were not observed to the degree which was later found to be necessary. Nevertheless it was shown that the 24 h LC~0 of Thais (Nucella) with respect to the gas flume effluent was more than 64% effluent in sea water of salinity 32.5%. Concurrently, it was shown that Buccinum undatum, a sensitive species, was not killed by 33 days exposure to 10% and 1% gas flume effluent in seawater of salinity 25.4%. Similarly, little mortality
at dilutions of 100 times or more. Since E. bernhardus is known to be highly sensitive to toxic materials (Perkins, 1968) and is used in this laboratory as a sensitive agent in bioassay generally, the results recorded in Table 1 suggest that the effects of these effluents are likely to be very local: a conclusion consistent with observations made in the field. Provided no unusually large amounts of material with a toxicity greater than that of the samples studied are released, this plant is expected to cause little damage. However, it should be emphasized that this is a pre-
TABLE 1 Long term survival of Eupagurus bernhardus exposed to chronic dosage of gas flume and coke oven effluents, 1971 Days to Mortality Gas Flume Coke Oven* Effluent 50% 100% 50% 100% Concentration Mortality Mortality Mortality Mortality (%) 0.5 ~86 ~129 13 to ~114 29 to ~114 1.0 ~11 to ~ 8 6 ~11 to ~86 1--~17 ~ 1 7 to 80 5.0 ~86 ~86 1--2 1--2 10.0 2 to ~ 8 6 11 to :>86 1--2 1--2 * This effluent is diluted by external sources at least 1 or 2 times before release to the sea and is, in practice, less toxic than these figures indicate. occurred in Carcinus exposed for 23 days. In contrast, Buccinum exposed to 10% and 1% coke oven effluent were all killed within 48 h; Carcinus were all killed by a 24 h exposure to a 5% solution in this effluent, but more than 50% of the test stock survived more than 19 days exposure to a 1% solution of coke oven effluent in sea water. In the latter series of experiments no controls died, but in the former series an unacceptably high death of controls (12.5% of Buccinum and 36% of Carcinus died on days 33 and 23 respectively) and the experiments were terminated for this reason. The chronic exposure of Eupagurus barnhardus to coke oven and gas flume effluents (Table 1) indicates that while there is a marked variation in the toxicity of individual samples, the coke oven effluent is significantly more toxic than that of the gas flume at dilutions less than 20 times, but is diluted 1 to 2 times before release to the sea. The differences are less marked
liminary result, and further confirmation would be of value. E. J. PERKINS
Marine Laboratory, University of Strathclyde, Dalandhui House, Garelochhead, Dunbartonshire, Scotland.
Buchanan, D. (1967), Aspects of effluent disposal from the manufacture of pig-iron. Wat. Pollut. Control, 66(6), 570582. Perkins, E. J. (1968), The toxicity of oil emulsifiers to some inshore fauna. Field Studies, 2 (suppl), 81-90. Perkins, E. J. (1972a), Some problems of marine toxicity studies. Mar. Poll. Bull., 3, 13-14. Perkins, E. J. (1972b), Some methods of assessment of toxic effects upon marine invertebrates. Proc. Soc. Analyt. Chem. (in press).
Bacterial Pollution of the Bristol Channel The Bristol Channel is becoming a site for intensive studT of the effects of industrial and urban effluents on the marine and estuarine environment. Microbiologists at Bristol University find that bacteria survive an unusually long time. The Bristol Channel, a body of water approximately 3,000 k m 2 in area, forms an inlet between the south coast of Wales and the north coast of the south-western counties of England. At its eastern end the Bristol Channel changes at an undefined longitude into the Severn Estuary and ultimately into the River Severn. Westward the Channel opens to the sea south-east of 88
Ireland at a point between St George's Channel and the Atlantic Western Approaches. The Atlantic tidal wave reaches the mouth of the Channel along both these waters simultaneously, to produce the exceptionally high tides characteristic of the area. The predicted mean spring tidal range at Avonmouth for 1972 was 12.3 m with spring tides reaching nearly 14 m. These tides give rise to correspondingly swift tidal streams in the Channel and in turn contribute to the formation of the famous Severn Bore. Williams Smith (1971) has reported the presence of up to 100,000/100 ml of Escherichia coli, a species of bacteria invariably of faecal origin, in samples of sea-
water taken off the beach at Porthcawl on the north coast of the Bristol Channel, while Thomas and Jones (1971) have isolated pathogenic typhoid organisms from rather more westerly areas of the Channel. This is not perhaps surprising when one considers that an estimated 1.3 million people live along the Bristol Channel coast in both urban and rural communities, and that there are only two major sewage treatment works serving the area. Furthermore, these provide only primary sedimentation for by far the greater part of their effluents. As a contribution to the Sabrina Project of Bristol University, we have examined 176 samples of water, mostly collected by boats at a depth of 2m, but including some samples collected from the shore. Counts of aerobic bacteria growing on water-yeastrel agar at 30 ° for 50 h and of coliforms able to produce acid gas in McConkey's medium at 37 ° for 48 h were carried out on all samples.
Tidal Corrections Because of the large tides characteristic of the Bristol Channel and the consequent rapid movement of the water, little immediate significance could be attached to the positions at which various samples were taken. To overcome this difficulty and make samples taken on different days and at different states of the tide comparable, a computer program was written to correct the position at which samples were taken to their predicted positions at a standard tide height. Published Admiralty tidal stream data were used for the calculation by conventional navigational methods (Reed, 1971) of the corrected positions but for times and heights of tides values observed by the Port of Bristol Authority at Avonmouth were used when available in preference to Admiralty predictions, from which they sometimes differed significantly.
Ca~
Results Total aerobic organisms ranged from 10/ml to 5.8 × 10~/ml, the counts being somewhat higher, though not consistently so, in the narrower part of the estuary cast of longitude 4°15'W, but counts were stillhigh in some of the most westerly samples taken. Faecal coliform counts ranged from 0/100ml to more than 10,000/100 ml with a greater tendency towards higher numbers in the narrower parts of the channel. Fig. I indicates position corrections applied to nine samples taken on one trip, and shows the considerable movement of the water in the estuary between the time a sample was taken and the standard tide height. Corrections of up to 22.5 k m were required with some samples.
Calculations of Water Movement The computer program was also used to estimate the overall movement of water, and Fig. 2 shows the predicted movement of a body of water in the channel over a period of ten tides following the first low water on 8 November, 1971. Throughout the period of the prediction the tidal range was falling, yet the surface water in mid-channel appeared to be working its way eastward with very little movement northward or southward. The water achieved its most easterly excursion at high water on the seventh tide corresponding to the lowest neap tide, and subsequently started to move westward again as the tidal range started to increase once more. By low water on the fifth day of this experiment, the overall movement of the water and, of course, of its pollution burden, was nearly 16 km eastward. The general easterly movement of the midstream surface water body was most unexpected.
,+7 Weston-s-Mare
Fig. 1 The positions in which nine samples were taken (01 to 09) and to which the water bod
from which they were taken moved under tidal influences (Xl to X9) between the time of sampling and the next standard height, namely mean sea level at the next falling tide. (Computer calculation.)
89
Cardiff
i
° ] ~ ,
.... 2 ' ~ --le°.~ , B ~
5 ~ . •7
!
19.713
10 N.Miles
"~"--.~ ~-o
22. 16.....14 ~o ? eo 18dl 2
w
l
Fig. 2 The position of a body of water (point 1) at low water on 8 November 1971 (spring tide) and its subsequent calculated position at the following high waters (points 2 to 22) and low waters (1 to 19). An average quality sewage effluent treated by either activated sludge or percolating filtration could be expected to have a coliform count of between 104 and 10~ organisms/100 ml and if treated only by primary sedimentation about ten times higher (Ware & Mellon, 1956). Gameson and Saxon (1967) showed that coliform bacteria die rapidly in seawater, numbers failing on average by 90% in under 36 h. Moreover, Wheatland (1965) has shown that coliform contamination of seawater near sewage outfalls is to some extent limited to the surface water, the coliform count falling to less than half the surface figure at a depth of 2 m (6 feet), no doubt reflecting that sewage tends to float in seawater on account of its lower salinity and higher temperature. These considerations, coupled with the high bacterial count observed, confirm the computer findings that little surface water movement occurs outward from the centre of the estuary--and also suggests that the organisms are either surviving longer or even multiplying in the water of the Channel. We hope to continue sampling the area with a view to preparing a contour map of the pollution in the Channel. Bacteria are a particularly suitable tracer for
this kind of study since they can be detected in very small numbers, 1 cell per litre presenting no particular problems and representing a dilution of 1 in 1015 of original material. We thank the Bristol Corporation, the master Capt Kenneth Seadon and officers of the M.V. Glen Avon, Cardiff Corporation, the master Capt H. H. Francis and Chief Engineer of the M.V. Marguerita for permission to use their respective vessels. G. C. WARE AVRIL E. ANSON YOLANDE F. ARIANAYAGAM
Department of Bacteriology, (Sabrina Project), University of Bristol, Bristol, UK. Admiralty Tide Tables (1971, 1972), Volume I. The Hydrographer of the Navy. Gameson, A. L. H. & Saxon, J. R. (1967), Water Research, 1, 279. Reed (1971), Reed's Nautical Almanac. Ed O. M. Watts. Thomas Reed's Publications Ltd., London. Thomas, K. L. & Jones, A. M. (1971), J. Appl. Bact., 34, 717. Ware, G. C. & Mellon, M. A. (1956), J. Hygiene, 54, 99. Wheatland, A. B., Agg, A. R. & Bruce, A. M. (1965), J. Inst. Sew. Purification, 291. Williams Smith, H. (1971), Nature, Lond., 234, 155.
Stressed Coral Reef Crabs in Hawaii Destructio~ of coral reefs in Hawaii elhnlnates the associated fauna by loss of its habitat, but evidence is now produced of damage to reef crabs wkich may be a more direct consequence of pollution. 90
During microbiological studies of coral reef regenerative sediments in Kaneohe Bay (DiSalvo, 1970; DiSalvo & Gundersen, 1971), I observed shell distress in several unidentified species of xanthid crabs inhabit-
at dilutions of 100 times or more. Since E. bernhardus is known to be highly sensitive to toxic materials (Perkins, 1968) and is used in this laboratory as a sensitive agent in bioassay generally, the results recorded in Table 1 suggest that the effects of these effluents are likely to be very local: a conclusion consistent with observations made in the field. Provided no unusually large amounts of material with a toxicity greater than that of the samples studied are released, this plant is expected to cause little damage. However, it should be emphasized that this is a pre-
TABLE 1 Long term survival of Eupagurus bernhardus exposed to chronic dosage of gas flume and coke oven effluents, 1971 Days to Mortality Gas Flume Coke Oven* Effluent 50% 100% 50% 100% Concentration Mortality Mortality Mortality Mortality (%) 0.5 ~86 ~129 13 to ~114 29 to ~114 1.0 ~11 to ~ 8 6 ~11 to ~86 1--~17 ~ 1 7 to 80 5.0 ~86 ~86 1--2 1--2 10.0 2 to ~ 8 6 11 to :>86 1--2 1--2 * This effluent is diluted by external sources at least 1 or 2 times before release to the sea and is, in practice, less toxic than these figures indicate. occurred in Carcinus exposed for 23 days. In contrast, Buccinum exposed to 10% and 1% coke oven effluent were all killed within 48 h; Carcinus were all killed by a 24 h exposure to a 5% solution in this effluent, but more than 50% of the test stock survived more than 19 days exposure to a 1% solution of coke oven effluent in sea water. In the latter series of experiments no controls died, but in the former series an unacceptably high death of controls (12.5% of Buccinum and 36% of Carcinus died on days 33 and 23 respectively) and the experiments were terminated for this reason. The chronic exposure of Eupagurus barnhardus to coke oven and gas flume effluents (Table 1) indicates that while there is a marked variation in the toxicity of individual samples, the coke oven effluent is significantly more toxic than that of the gas flume at dilutions less than 20 times, but is diluted 1 to 2 times before release to the sea. The differences are less marked
liminary result, and further confirmation would be of value. E. J. PERKINS
Marine Laboratory, University of Strathclyde, Dalandhui House, Garelochhead, Dunbartonshire, Scotland.
Buchanan, D. (1967), Aspects of effluent disposal from the manufacture of pig-iron. Wat. Pollut. Control, 66(6), 570582. Perkins, E. J. (1968), The toxicity of oil emulsifiers to some inshore fauna. Field Studies, 2 (suppl), 81-90. Perkins, E. J. (1972a), Some problems of marine toxicity studies. Mar. Poll. Bull., 3, 13-14. Perkins, E. J. (1972b), Some methods of assessment of toxic effects upon marine invertebrates. Proc. Soc. Analyt. Chem. (in press).
Bacterial Pollution of the Bristol Channel The Bristol Channel is becoming a site for intensive studT of the effects of industrial and urban effluents on the marine and estuarine environment. Microbiologists at Bristol University find that bacteria survive an unusually long time. The Bristol Channel, a body of water approximately 3,000 k m 2 in area, forms an inlet between the south coast of Wales and the north coast of the south-western counties of England. At its eastern end the Bristol Channel changes at an undefined longitude into the Severn Estuary and ultimately into the River Severn. Westward the Channel opens to the sea south-east of 88
Ireland at a point between St George's Channel and the Atlantic Western Approaches. The Atlantic tidal wave reaches the mouth of the Channel along both these waters simultaneously, to produce the exceptionally high tides characteristic of the area. The predicted mean spring tidal range at Avonmouth for 1972 was 12.3 m with spring tides reaching nearly 14 m. These tides give rise to correspondingly swift tidal streams in the Channel and in turn contribute to the formation of the famous Severn Bore. Williams Smith (1971) has reported the presence of up to 100,000/100 ml of Escherichia coli, a species of bacteria invariably of faecal origin, in samples of sea-
water taken off the beach at Porthcawl on the north coast of the Bristol Channel, while Thomas and Jones (1971) have isolated pathogenic typhoid organisms from rather more westerly areas of the Channel. This is not perhaps surprising when one considers that an estimated 1.3 million people live along the Bristol Channel coast in both urban and rural communities, and that there are only two major sewage treatment works serving the area. Furthermore, these provide only primary sedimentation for by far the greater part of their effluents. As a contribution to the Sabrina Project of Bristol University, we have examined 176 samples of water, mostly collected by boats at a depth of 2m, but including some samples collected from the shore. Counts of aerobic bacteria growing on water-yeastrel agar at 30 ° for 50 h and of coliforms able to produce acid gas in McConkey's medium at 37 ° for 48 h were carried out on all samples.
Tidal Corrections Because of the large tides characteristic of the Bristol Channel and the consequent rapid movement of the water, little immediate significance could be attached to the positions at which various samples were taken. To overcome this difficulty and make samples taken on different days and at different states of the tide comparable, a computer program was written to correct the position at which samples were taken to their predicted positions at a standard tide height. Published Admiralty tidal stream data were used for the calculation by conventional navigational methods (Reed, 1971) of the corrected positions but for times and heights of tides values observed by the Port of Bristol Authority at Avonmouth were used when available in preference to Admiralty predictions, from which they sometimes differed significantly.
Ca~
Results Total aerobic organisms ranged from 10/ml to 5.8 × 10~/ml, the counts being somewhat higher, though not consistently so, in the narrower part of the estuary cast of longitude 4°15'W, but counts were stillhigh in some of the most westerly samples taken. Faecal coliform counts ranged from 0/100ml to more than 10,000/100 ml with a greater tendency towards higher numbers in the narrower parts of the channel. Fig. I indicates position corrections applied to nine samples taken on one trip, and shows the considerable movement of the water in the estuary between the time a sample was taken and the standard tide height. Corrections of up to 22.5 k m were required with some samples.
Calculations of Water Movement The computer program was also used to estimate the overall movement of water, and Fig. 2 shows the predicted movement of a body of water in the channel over a period of ten tides following the first low water on 8 November, 1971. Throughout the period of the prediction the tidal range was falling, yet the surface water in mid-channel appeared to be working its way eastward with very little movement northward or southward. The water achieved its most easterly excursion at high water on the seventh tide corresponding to the lowest neap tide, and subsequently started to move westward again as the tidal range started to increase once more. By low water on the fifth day of this experiment, the overall movement of the water and, of course, of its pollution burden, was nearly 16 km eastward. The general easterly movement of the midstream surface water body was most unexpected.
,+7 Weston-s-Mare
Fig. 1 The positions in which nine samples were taken (01 to 09) and to which the water bod
from which they were taken moved under tidal influences (Xl to X9) between the time of sampling and the next standard height, namely mean sea level at the next falling tide. (Computer calculation.)
89
Cardiff
i
° ] ~ ,
.... 2 ' ~ --le°.~ , B ~
5 ~ . •7
!
19.713
10 N.Miles
"~"--.~ ~-o
22. 16.....14 ~o ? eo 18dl 2
w
l
Fig. 2 The position of a body of water (point 1) at low water on 8 November 1971 (spring tide) and its subsequent calculated position at the following high waters (points 2 to 22) and low waters (1 to 19). An average quality sewage effluent treated by either activated sludge or percolating filtration could be expected to have a coliform count of between 104 and 10~ organisms/100 ml and if treated only by primary sedimentation about ten times higher (Ware & Mellon, 1956). Gameson and Saxon (1967) showed that coliform bacteria die rapidly in seawater, numbers failing on average by 90% in under 36 h. Moreover, Wheatland (1965) has shown that coliform contamination of seawater near sewage outfalls is to some extent limited to the surface water, the coliform count falling to less than half the surface figure at a depth of 2 m (6 feet), no doubt reflecting that sewage tends to float in seawater on account of its lower salinity and higher temperature. These considerations, coupled with the high bacterial count observed, confirm the computer findings that little surface water movement occurs outward from the centre of the estuary--and also suggests that the organisms are either surviving longer or even multiplying in the water of the Channel. We hope to continue sampling the area with a view to preparing a contour map of the pollution in the Channel. Bacteria are a particularly suitable tracer for
this kind of study since they can be detected in very small numbers, 1 cell per litre presenting no particular problems and representing a dilution of 1 in 1015 of original material. We thank the Bristol Corporation, the master Capt Kenneth Seadon and officers of the M.V. Glen Avon, Cardiff Corporation, the master Capt H. H. Francis and Chief Engineer of the M.V. Marguerita for permission to use their respective vessels. G. C. WARE AVRIL E. ANSON YOLANDE F. ARIANAYAGAM
Department of Bacteriology, (Sabrina Project), University of Bristol, Bristol, UK. Admiralty Tide Tables (1971, 1972), Volume I. The Hydrographer of the Navy. Gameson, A. L. H. & Saxon, J. R. (1967), Water Research, 1, 279. Reed (1971), Reed's Nautical Almanac. Ed O. M. Watts. Thomas Reed's Publications Ltd., London. Thomas, K. L. & Jones, A. M. (1971), J. Appl. Bact., 34, 717. Ware, G. C. & Mellon, M. A. (1956), J. Hygiene, 54, 99. Wheatland, A. B., Agg, A. R. & Bruce, A. M. (1965), J. Inst. Sew. Purification, 291. Williams Smith, H. (1971), Nature, Lond., 234, 155.
Stressed Coral Reef Crabs in Hawaii Destructio~ of coral reefs in Hawaii elhnlnates the associated fauna by loss of its habitat, but evidence is now produced of damage to reef crabs wkich may be a more direct consequence of pollution. 90
During microbiological studies of coral reef regenerative sediments in Kaneohe Bay (DiSalvo, 1970; DiSalvo & Gundersen, 1971), I observed shell distress in several unidentified species of xanthid crabs inhabit-