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Marine debris contamination of beaches in St. Lucia and Dominica
Volume 2 6 / N u m b e r 6/June 1993 0025-326X/93 $6.00+0.00 © 1993PergamonPressLtd
Marine Pollution Bulletin, Volume26, No. 6, pp. 325-328, 1993.
Printed in GreatBritain.
Marine Debris Contamination of Beaches in St. Lucia and Dominica C. J. CORBIN* and J. G. SINGH Caribbean Environmental Health Institute, P.O. Box 1111, Castries, St. Lucia, West Indies *Present address: Centre for Resource Management and Environmental Studies, University of the West Indies, EO. Box 64, Barbados, West Indies
There is greater focus on the increasing amounts of man-made debris and the associated problems that this brings. Pilot surveys of beaches in islands of the Eastern Caribbean show substantial levels of beach debris, but no long term assessment has been conducted. A survey of two islands in the Caribbean region was conducted between 1991 and 1992. Mean debris levels by number and weight ranged from 4.5 to 11.2 items m -1 and 8.2 to 109.2 g m -~ of beach front in St. Lucia and 1.9-6.2-items m -1 and 5 1 . 5 - 1 5 3 . 7 g m -1 in Dominica. Plastic was commonest in St. Lucia, 51.3% by number and 38.6% by weight, while driftwood was most common in Dominica, 35.9% by number and 59.3% by weight.
There is greater focus on the increasing amounts of man-made debris that litter the worlds' oceans and coastlines, and the associated problems which this brings. This debris consists mostly of persistent material such as plastics, metal, glass and rubber. Sources include maritime activities, beach recreation activities and land-based refuse (IOC/FAO/UNEP, 1989). Many scientists believe that plastic is the most far reaching man-made threat facing many marine species (Springer, 1989). Apart from its persistence in the environment, the reason that plastic is such a problem is that it floats and is concentrated into specific locations by ocean currents. Marine debris has been found to pose serious threats to marine wildlife, navigation, and affects aesthetic qualities of marine areas. Trash on the shoreline is an even more potentially serious problem for Caribbean islands where it threatens the health and safety of beach users. This is detrimental to the tourism industry, a major revenue earner in many of these islands, Regional experts have identified the problem of marine debris pollution as one of primary concern. This was ratified by government representatives at the Third session of the IOC Sub-Commission for the Caribbean and Adjacent Regions in 1989 (IOC/IOCARIBE, 1989). Recent pilot studies have shown that islands of the Eastern Caribbean have substantial plastic present on their beaches (Springer, 1989; Wilber, 1987). However, no long term assessment of the extent of the problem
has been undertaken. This report presents the results of a survey done over a period of 1 year in the Caribbean islands of St. Lucia and Dominica (Fig. 1).
Methods
Site selection and the monitoring protocol followed that recommended by IOCARIBE (IOCARIBE, 1990). Two recreational beaches on the west and one nonrecreational on the east coast of St. Lucia, and three recreational beaches on Dominica's west coast were surveyed. Four fixed transects, 5 m wide, spread equidistantly along the beach front, were sampled. The transect extended from the low water line to the vegetation line. Samples were collected monthly between January and December 1991. All visible persistent litter greater than 1-2 cm were collected, cleaned and sorted as: /. Plastics; 2. Styrofoam; 3. Fishing gear; 4. Glass; 5. Metal; 6. Rubber; 7. Wood (driftwood); 8. Cloth; and 9. Other. Results were recorded as numbers and weights of items m -a of beach front.
Results
Figures 2a and 2b show marine debris composition for the islands of St. Lucia and Dominica by numbers and weights. In St. Lucia, plastics were the main component of litter (51.3% by number and 38.6% by weight) with plastic bags and cups representing the major components of this. Other major inputs included glass, metal and other, mainly paper products. In Dominica, driftwood was commonest accounting for 35.9 and 59.3% by number and weight respectively of debris items. Plastics was the second most common by number with 16.0% with other major inputs from glass and metal. Tables 1 and 2 show the percentage compositions of the individual beaches surveyed in St. Lucia and Dominica respectively. In St. Lucia, the highest percentage composition by number (82.2%) and weight (54.7%) of plastics was obtained for the east coast beach. Mean numbers of debris items m -1 of beach front ranged from 1.9 in Dominica to 11.2 in St. Lucia and mean weights from 8.2 g m -1 in St. Lucia to 153.7 g m -1 in Dominica (Fig. 3). 325
Marine Pollution Bulletin I
61o00 ' -15"50'
0
5
i0
I
I
I
km
N. E. T R A D E S
DOMINICA
-15"00'~ EQUATORIAL CURRENT
CARIBBEAN CURRENT
CARIBBEAN
"e..SEA
ATLANTIC
OCEAN
-14o00 '
ST.LUCIA
°~o -13o50 '
SI.HEIA '°,o
~
Fig. 1 Location of the islands St. Lucia and Dominica in the Eastern Caribbean, selected for a Marine Debris survey from 1991-92. Major wind currents and direction are indicated by solid arrows and ocean currents as broken arrows.
Discussion The results presented for St. Lucia are consistent with other worldwide surveys where plastics have been identified as the major category of marine debris reported by weights and/or numbers (Caulton & Mocogni, 1987; IOC/FAO/UNEP, 1989; Shiber, 1987; Vauk & Schrey, 1987). The Centre for Marine Conservation (CMC), 1989 Beach Cleanup Report identifies the major debris components in Puerto Rico as plastics (47.4%), metal (21.4%) and glass (18.6%). These and paper items were the most common found during the surveys of the two islands. In Dominica, the large quantity of driftwood is unusual when compared to other beach surveys. A number of coastal communities in this island practice fishing and reports indicate that a large number of abandoned wooden fishing vessels wash ashore. Observations made of the type of litter indicate that most of the plastics is from local land-based refuse. The only exception to this is on the east coast beach in St. 326
Lucia, where labels on glass and plastic bottles suggest an origin as far north as the United States Virgin Islands. The beach, which is non-recreational, also shows a substantially higher percentage of plastics (82.2%) compared to the recreational, west coast beaches where debris items are more varied. Moderate levels of marine debris are found on the beaches surveyed in Dominica and St. Lucia. IOCARIBE data from Puerto Rico reflect an average abundance of 3.9 items m -1 and 945 g m -1 of beach front for isolated beaches (IOC/IOCARIBE, 1989). Additional data from the same source report that recreational beaches had 50% more debris than isolated beaches. Numbers recorded for recreational, west coast beaches vary between 1.9 and 6.2 items m -1 which is similar to the results obtained in Puerto Rico. However, the average abundance by weight is much less with the highest recorded being 153.7 g m -1 in Dominica. Isolated beaches, as evidenced from the east coast beach in St. Lucia, have higher numbers and weights of
Volume 26/Number 6/June 1993
Fig. 2 Percentage composition of marine debris items according to number (i) and weight (ii) for selected beaches in the islands of St. Lucia (2a) and Dominica (2b). Debris was categorized as fishing line, plastics, styrofoam, glass, metal, rubber, wood, cloth and other. The location of the islands is shown in Fig. 1.
TABLE 1
TABLE 2
Mean percentage composition of marine debris by number and weight for three St. Lucian beaches.
Mean percentage composition of marine debris by number and weight for three Dominican beaches.
A* Category
No.
Wt
Fishing line Plastics Styrofoam Glass Metal Rubber Wood Cloth Other
3.5 82.2 3.2 0.7 3.4 0.9 0.4 1.1 4.6
5.3 54.7 1.2 18.7 1.9 9.6 1.6 3.4 3.6
Beaches B No. Wt
No.
Wt
Category
No.
0.0 29.6 12.6 1.8 14.8 0.0 1.8 0.4 39.0
0.2 42.0 14.7 2.3 11.3 3.5 1.5 7.0 17.5
0.1 26.6 1.4 8.1 17.4 14.2 6.6 11.2 14.4
Fishing line Plastics Styrofoam Glass Metal Rubber Wood Cloth Other
2.9 7.4 8.1 13.6 5.5 1.3 50.2 1.0 10.0
0.0 34.6 2.9 5.4 24.5 0.0 9.6 4.2 18.8
C
Wt
Beaches E No. Wt
No.
Wt
0.6 5.6 3.0 12.3 2.8 2.3 71.5 1.2 0.7
1.3 16.0 8.0 12.0 18.0 4.7 35.3 2.0 2.7
5.3 24.5 8.5 16.0 9.6 0.0 22.3 3.2 10.6
2.3 3.3 1.5 17.2 6.4 0.0 63.2 1.6 4.5
D
0.4 5.9 3.8 9.3 26.5 9.6 43.2 0.6 0.7
F
*Represents the east coast beach surveyed.
327
Marine Pollution Bulletin 15 14
mNUMBER / m WEIGHT g/ m
(a)
140
13 120
12 11
100
10
E
9
n,,
8
E
80
LIJ
7 Z
60
6
icn IT (,9
5 4
40
5 2
20
1 0
A
BEACHES
B -
C ST.LUCIA
10
160 m NUMBER / m E[~] WEIGHTg / m I
(b)
140
beaches located on the exposed east (windward) coasts. East coast beaches are thus subject to a greater input of marine debris. A similar trend of distribution of tar balls on west and east coast beaches in St. Lucia, Dominica and other islands of the Eastern Caribbean has been reported (Atwood et al., 1988; Corbin & Ibiebele, 1992). The level of human activity, type of beach usage and location are the most important factors controlling levels of marine debris for the beaches surveyed. Levels are a function not only of the quantity of debris in adjacent waters and the direct input from visitors to the beach, but also of the beach physiography, slope, exposure and environmental factors influencing the transport of the debris items. Values reported here cannot be used as a generalized description of beach pollution for the region. Individual island surveys are thus recommended. When beach debris results mainly from local disposal practices, as indicated in the two countries surveyed, control needs to be effected at the local level (Caulton & Mocogni, 1987; Pruter, 1987).
120 7
E
6
lOO
n~ ~J
5
8O
4
-60
m Z
E E:n
w
.40
20
D BEACHES
E -
F DOMINICA
Fig. 3 Mean marine debris levels for three beaches (A, B and C) in (a) St. Lucia and (19)Dominica (D, E and F). Shaded bars represent number of items and open bars weight of items m -1 of beach front. A represents the only East coast (non-recreational) beach sampled during the survey.
debris items compared to recreational beaches. This differs from the results of the Puerto Rico survey and may be due to differences in location, sampling methodology, duration and period of sampling. The most important factor influencing distribution of debris on the west and east coasts is the direction of prevailing winds and ocean currents (Fig. 1). Recreational beaches are found mainly on the sheltered west (leeward) coasts of the islands compared to isolated
328
The contributions of the Ministry of Health in Dominica in field data collection and the technical assistance of Miss N. Edgecombe are acknowledged. This study formed part of CEHI's programme for the 'Enhancement of Coastal and Marine Environmental Monitoring', a regional project funded by the International Centre for Oceans Development (ICOD). Atwood, D. K., Burton, F. J., Corredor, J., Mata-Jimenez, A., VasquezBotello, A. & Wade, B. A. (1988). Petroleum Pollution in the Caribbean. Oceanus 30, 25-32. Caulton, E. & Mocogni, M. (1987). Preliminary studies of man-made litter in the Firth of Forth, Scotland. Mar. Pollut. Bull. 18, 446-450. CMC (1989). Centre for Marine Conservation. 1989 Beach Cleanup Report--Puerto Rico. Corbin, C. J. & Ibiebele, D. D. (1992). Tar Ball Survey of Six Caribbean Is/ands. Proc. Caribbean 2nd Annual Haztech Conference Oct. 21-23, 1992, San Juan, Puerto Rico, 2A.27-2A.39. IOC/FAO/UNEP (1989). Pilot survey of coastal pollution by persistent synthetic materials in selected Mediterranean areas. IOC/IOCARIBE (1989). Report from Third session of the IOC SubCommission for the Caribbean and Adjacent Regions. IOCARIBE (1990). Guidelines for Monitoring of persistent synthetic materials. Laist, D. W. (1987). Overview of the biological effects of lost and discarded plastic debris in the marine environment. Mar. Pollut. Bull. 6B, 319-326. Pruter, A. T. (1987). Sources, quantities and distribution of persistent plastics in the marine environment. Mar. Pollut. Bull. 6B, 305-310. Shiber, J. G. (1987). Plastic pellets and tar on Spain's Mediterranean beaches. Mar. Pollut. Bull. 18, 84-86. Springer, A. M. (1989). Plastic Pollution in the aquatic environment-The unnecessary evil. (Unpublished.) Vauk, G. J. M. & Schrey, E. (1987). Litter pollution from ships in the German Bight. Mar. Pollut. Bull. 6B, 316-319. Wilber, R. J. (1987). Plastic in the North Atlantic. Oceanus 30(3), 6168.
Marine Pollution Bulletin, Volume26, No. 6, pp. 325-328, 1993.
Printed in GreatBritain.
Marine Debris Contamination of Beaches in St. Lucia and Dominica C. J. CORBIN* and J. G. SINGH Caribbean Environmental Health Institute, P.O. Box 1111, Castries, St. Lucia, West Indies *Present address: Centre for Resource Management and Environmental Studies, University of the West Indies, EO. Box 64, Barbados, West Indies
There is greater focus on the increasing amounts of man-made debris and the associated problems that this brings. Pilot surveys of beaches in islands of the Eastern Caribbean show substantial levels of beach debris, but no long term assessment has been conducted. A survey of two islands in the Caribbean region was conducted between 1991 and 1992. Mean debris levels by number and weight ranged from 4.5 to 11.2 items m -1 and 8.2 to 109.2 g m -~ of beach front in St. Lucia and 1.9-6.2-items m -1 and 5 1 . 5 - 1 5 3 . 7 g m -1 in Dominica. Plastic was commonest in St. Lucia, 51.3% by number and 38.6% by weight, while driftwood was most common in Dominica, 35.9% by number and 59.3% by weight.
There is greater focus on the increasing amounts of man-made debris that litter the worlds' oceans and coastlines, and the associated problems which this brings. This debris consists mostly of persistent material such as plastics, metal, glass and rubber. Sources include maritime activities, beach recreation activities and land-based refuse (IOC/FAO/UNEP, 1989). Many scientists believe that plastic is the most far reaching man-made threat facing many marine species (Springer, 1989). Apart from its persistence in the environment, the reason that plastic is such a problem is that it floats and is concentrated into specific locations by ocean currents. Marine debris has been found to pose serious threats to marine wildlife, navigation, and affects aesthetic qualities of marine areas. Trash on the shoreline is an even more potentially serious problem for Caribbean islands where it threatens the health and safety of beach users. This is detrimental to the tourism industry, a major revenue earner in many of these islands, Regional experts have identified the problem of marine debris pollution as one of primary concern. This was ratified by government representatives at the Third session of the IOC Sub-Commission for the Caribbean and Adjacent Regions in 1989 (IOC/IOCARIBE, 1989). Recent pilot studies have shown that islands of the Eastern Caribbean have substantial plastic present on their beaches (Springer, 1989; Wilber, 1987). However, no long term assessment of the extent of the problem
has been undertaken. This report presents the results of a survey done over a period of 1 year in the Caribbean islands of St. Lucia and Dominica (Fig. 1).
Methods
Site selection and the monitoring protocol followed that recommended by IOCARIBE (IOCARIBE, 1990). Two recreational beaches on the west and one nonrecreational on the east coast of St. Lucia, and three recreational beaches on Dominica's west coast were surveyed. Four fixed transects, 5 m wide, spread equidistantly along the beach front, were sampled. The transect extended from the low water line to the vegetation line. Samples were collected monthly between January and December 1991. All visible persistent litter greater than 1-2 cm were collected, cleaned and sorted as: /. Plastics; 2. Styrofoam; 3. Fishing gear; 4. Glass; 5. Metal; 6. Rubber; 7. Wood (driftwood); 8. Cloth; and 9. Other. Results were recorded as numbers and weights of items m -a of beach front.
Results
Figures 2a and 2b show marine debris composition for the islands of St. Lucia and Dominica by numbers and weights. In St. Lucia, plastics were the main component of litter (51.3% by number and 38.6% by weight) with plastic bags and cups representing the major components of this. Other major inputs included glass, metal and other, mainly paper products. In Dominica, driftwood was commonest accounting for 35.9 and 59.3% by number and weight respectively of debris items. Plastics was the second most common by number with 16.0% with other major inputs from glass and metal. Tables 1 and 2 show the percentage compositions of the individual beaches surveyed in St. Lucia and Dominica respectively. In St. Lucia, the highest percentage composition by number (82.2%) and weight (54.7%) of plastics was obtained for the east coast beach. Mean numbers of debris items m -1 of beach front ranged from 1.9 in Dominica to 11.2 in St. Lucia and mean weights from 8.2 g m -1 in St. Lucia to 153.7 g m -1 in Dominica (Fig. 3). 325
Marine Pollution Bulletin I
61o00 ' -15"50'
0
5
i0
I
I
I
km
N. E. T R A D E S
DOMINICA
-15"00'~ EQUATORIAL CURRENT
CARIBBEAN CURRENT
CARIBBEAN
"e..SEA
ATLANTIC
OCEAN
-14o00 '
ST.LUCIA
°~o -13o50 '
SI.HEIA '°,o
~
Fig. 1 Location of the islands St. Lucia and Dominica in the Eastern Caribbean, selected for a Marine Debris survey from 1991-92. Major wind currents and direction are indicated by solid arrows and ocean currents as broken arrows.
Discussion The results presented for St. Lucia are consistent with other worldwide surveys where plastics have been identified as the major category of marine debris reported by weights and/or numbers (Caulton & Mocogni, 1987; IOC/FAO/UNEP, 1989; Shiber, 1987; Vauk & Schrey, 1987). The Centre for Marine Conservation (CMC), 1989 Beach Cleanup Report identifies the major debris components in Puerto Rico as plastics (47.4%), metal (21.4%) and glass (18.6%). These and paper items were the most common found during the surveys of the two islands. In Dominica, the large quantity of driftwood is unusual when compared to other beach surveys. A number of coastal communities in this island practice fishing and reports indicate that a large number of abandoned wooden fishing vessels wash ashore. Observations made of the type of litter indicate that most of the plastics is from local land-based refuse. The only exception to this is on the east coast beach in St. 326
Lucia, where labels on glass and plastic bottles suggest an origin as far north as the United States Virgin Islands. The beach, which is non-recreational, also shows a substantially higher percentage of plastics (82.2%) compared to the recreational, west coast beaches where debris items are more varied. Moderate levels of marine debris are found on the beaches surveyed in Dominica and St. Lucia. IOCARIBE data from Puerto Rico reflect an average abundance of 3.9 items m -1 and 945 g m -1 of beach front for isolated beaches (IOC/IOCARIBE, 1989). Additional data from the same source report that recreational beaches had 50% more debris than isolated beaches. Numbers recorded for recreational, west coast beaches vary between 1.9 and 6.2 items m -1 which is similar to the results obtained in Puerto Rico. However, the average abundance by weight is much less with the highest recorded being 153.7 g m -1 in Dominica. Isolated beaches, as evidenced from the east coast beach in St. Lucia, have higher numbers and weights of
Volume 26/Number 6/June 1993
Fig. 2 Percentage composition of marine debris items according to number (i) and weight (ii) for selected beaches in the islands of St. Lucia (2a) and Dominica (2b). Debris was categorized as fishing line, plastics, styrofoam, glass, metal, rubber, wood, cloth and other. The location of the islands is shown in Fig. 1.
TABLE 1
TABLE 2
Mean percentage composition of marine debris by number and weight for three St. Lucian beaches.
Mean percentage composition of marine debris by number and weight for three Dominican beaches.
A* Category
No.
Wt
Fishing line Plastics Styrofoam Glass Metal Rubber Wood Cloth Other
3.5 82.2 3.2 0.7 3.4 0.9 0.4 1.1 4.6
5.3 54.7 1.2 18.7 1.9 9.6 1.6 3.4 3.6
Beaches B No. Wt
No.
Wt
Category
No.
0.0 29.6 12.6 1.8 14.8 0.0 1.8 0.4 39.0
0.2 42.0 14.7 2.3 11.3 3.5 1.5 7.0 17.5
0.1 26.6 1.4 8.1 17.4 14.2 6.6 11.2 14.4
Fishing line Plastics Styrofoam Glass Metal Rubber Wood Cloth Other
2.9 7.4 8.1 13.6 5.5 1.3 50.2 1.0 10.0
0.0 34.6 2.9 5.4 24.5 0.0 9.6 4.2 18.8
C
Wt
Beaches E No. Wt
No.
Wt
0.6 5.6 3.0 12.3 2.8 2.3 71.5 1.2 0.7
1.3 16.0 8.0 12.0 18.0 4.7 35.3 2.0 2.7
5.3 24.5 8.5 16.0 9.6 0.0 22.3 3.2 10.6
2.3 3.3 1.5 17.2 6.4 0.0 63.2 1.6 4.5
D
0.4 5.9 3.8 9.3 26.5 9.6 43.2 0.6 0.7
F
*Represents the east coast beach surveyed.
327
Marine Pollution Bulletin 15 14
mNUMBER / m WEIGHT g/ m
(a)
140
13 120
12 11
100
10
E
9
n,,
8
E
80
LIJ
7 Z
60
6
icn IT (,9
5 4
40
5 2
20
1 0
A
BEACHES
B -
C ST.LUCIA
10
160 m NUMBER / m E[~] WEIGHTg / m I
(b)
140
beaches located on the exposed east (windward) coasts. East coast beaches are thus subject to a greater input of marine debris. A similar trend of distribution of tar balls on west and east coast beaches in St. Lucia, Dominica and other islands of the Eastern Caribbean has been reported (Atwood et al., 1988; Corbin & Ibiebele, 1992). The level of human activity, type of beach usage and location are the most important factors controlling levels of marine debris for the beaches surveyed. Levels are a function not only of the quantity of debris in adjacent waters and the direct input from visitors to the beach, but also of the beach physiography, slope, exposure and environmental factors influencing the transport of the debris items. Values reported here cannot be used as a generalized description of beach pollution for the region. Individual island surveys are thus recommended. When beach debris results mainly from local disposal practices, as indicated in the two countries surveyed, control needs to be effected at the local level (Caulton & Mocogni, 1987; Pruter, 1987).
120 7
E
6
lOO
n~ ~J
5
8O
4
-60
m Z
E E:n
w
.40
20
D BEACHES
E -
F DOMINICA
Fig. 3 Mean marine debris levels for three beaches (A, B and C) in (a) St. Lucia and (19)Dominica (D, E and F). Shaded bars represent number of items and open bars weight of items m -1 of beach front. A represents the only East coast (non-recreational) beach sampled during the survey.
debris items compared to recreational beaches. This differs from the results of the Puerto Rico survey and may be due to differences in location, sampling methodology, duration and period of sampling. The most important factor influencing distribution of debris on the west and east coasts is the direction of prevailing winds and ocean currents (Fig. 1). Recreational beaches are found mainly on the sheltered west (leeward) coasts of the islands compared to isolated
328
The contributions of the Ministry of Health in Dominica in field data collection and the technical assistance of Miss N. Edgecombe are acknowledged. This study formed part of CEHI's programme for the 'Enhancement of Coastal and Marine Environmental Monitoring', a regional project funded by the International Centre for Oceans Development (ICOD). Atwood, D. K., Burton, F. J., Corredor, J., Mata-Jimenez, A., VasquezBotello, A. & Wade, B. A. (1988). Petroleum Pollution in the Caribbean. Oceanus 30, 25-32. Caulton, E. & Mocogni, M. (1987). Preliminary studies of man-made litter in the Firth of Forth, Scotland. Mar. Pollut. Bull. 18, 446-450. CMC (1989). Centre for Marine Conservation. 1989 Beach Cleanup Report--Puerto Rico. Corbin, C. J. & Ibiebele, D. D. (1992). Tar Ball Survey of Six Caribbean Is/ands. Proc. Caribbean 2nd Annual Haztech Conference Oct. 21-23, 1992, San Juan, Puerto Rico, 2A.27-2A.39. IOC/FAO/UNEP (1989). Pilot survey of coastal pollution by persistent synthetic materials in selected Mediterranean areas. IOC/IOCARIBE (1989). Report from Third session of the IOC SubCommission for the Caribbean and Adjacent Regions. IOCARIBE (1990). Guidelines for Monitoring of persistent synthetic materials. Laist, D. W. (1987). Overview of the biological effects of lost and discarded plastic debris in the marine environment. Mar. Pollut. Bull. 6B, 319-326. Pruter, A. T. (1987). Sources, quantities and distribution of persistent plastics in the marine environment. Mar. Pollut. Bull. 6B, 305-310. Shiber, J. G. (1987). Plastic pellets and tar on Spain's Mediterranean beaches. Mar. Pollut. Bull. 18, 84-86. Springer, A. M. (1989). Plastic Pollution in the aquatic environment-The unnecessary evil. (Unpublished.) Vauk, G. J. M. & Schrey, E. (1987). Litter pollution from ships in the German Bight. Mar. Pollut. Bull. 6B, 316-319. Wilber, R. J. (1987). Plastic in the North Atlantic. Oceanus 30(3), 6168.