- Email: [email protected]
Types and sources of marine debris in Fog Bay, Northern Australia
Pergamon PII: S0025-326X(98)00066-6
Marine Polh~tion Bulletbl, Vol. 36. No. 11, pp. 904-910, 1998 © 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain [~125-326X/98 $19,(~+{).00
Types and Sources of Marine Debris in Fog Bay, Northern Australia SCOTT D. WHITING Faculty of Science, Northern Territory University, Darwin, N T 0909, Australia Marine debris items were collected and categorized during surveys of beaches in Fog Bay, northern Australia in 1996 and 1997. Synthetic items (45%) were the most numerous followed by metal (35%) and glass (16%). Drink containers contributed 53% of the total items, while fishing gear and foreign material contributed only 4% and 3%, respectively. Scores were given to each possible source of marine debris according to their likelihood of contributing to each group of debris items. Using this method, commercial fishing, merchant shipping and recreational boaters were likely to contribute to over 85% of all debris items. Composition of debris items varied between beach orientation within the same year and within beach orientation between years, which suggests that a number of beaches and locations should be sampled to obtain an unbiased estimate of marine debris for annual comparisons. © 1998 Elsevier Science Ltd. All rights reserved Keywords: debris; marine; Australia; source; litter; rubbish; pollution.
Anthropogenic debris in the marine environment poses a serious threat to marine animals (Laist, 1987). Many types of debris including plastics and fishing gear, either entangle or are ingested by marine mammals (Fowler, 1987; Laist, 1987; Walker, 1989; Slater, 1991; Pemberton et al., 1992), turtles (Balazs, 1985; Bjorndal et al., 1994; Chatto et al., 1995), birds (Day et al., 1985; Fry et al., 1987; Slater, 1992), fish (Cawthorn, 1985; Jones, 1994) and crustaceans (Laist, 1987). Debris washed ashore also poses a hazard for terrestrial animals (Merrell, 1980) and can hinder and entrap sea turtle hatchlings and adults when they are on the beach during the nesting season (National Research Council, 1990). Marine debris not only represents a hazard to marine animals but may impact on many human activities as well. Marine debris damages and fouls shipping (Tomkin, 1989), causes injuries on beaches (Dixon and Dixon, 1981), poses a hazard to divers (Jones, 1994) and aesthetically degrades wilderness values (Land Conservation Council, 1991) and multi-use coastal habitat. International law implemented in 1988 (MARPOL, The International Convention for the Prevention of 904
Pollution from Ships, Annex V 1973/1978, see Brown, 1994) and Australian legislation implemented in 1990 (Protection of the Sea Act 1983 - - Prevention of Pollution from Ships) regulates the discharge of debris in Australian waters. Under these laws it is prohibited to discharge plastics and the discharge of other items is restricted by minimum distance from shore regulations. These laws, however, are difficult to enforce and illegal dumping of debris continues (Ryan and Moloney, 1993). To reduce debris in the marine environment, the sources of the debris must be identified (ANZECC, 1996) and practices implemented to reduce the amount discarded. There are two main sources of marine debris; oceanborne waste disposed of at sea and terrestrial waste originating from coastal users and urban centres (Rees and Pond, 1995). These two categories must be broken down further to identify user groups which contribute to the majority of the waste. Marine debris monitoring programs can help to identify the source, although most are aimed at determining amount and type rather than origin. Three main methods of monitoring have been used: (1) surveys to estimate the quantity and types of wastes generated by ships and pleasure craft (Horsman, 1982), (2) sea based surveys of the ocean surface to assess the amount and type of floating debris at sea (Dixon and Dixon, 1983) and (3) beach surveys to assess the type and amount of debris on a section of coast at a given time (for Australia see Wace, 1995). For a review of general methods for each of these types of surveys see Rees and Pond (1995). This study used beach surveys in Fog Bay to: (1) assess the amount of debris and categorize it by type of material, (2) identify individual pieces of debris and determine possible sources and (3) remove marine debris from those beaches surveyed in Fog Bay. This study is the first quantitative survey of marine debris on the northern Austi'alian coast between Cape York and North West Cape (Wace, 1995). Methods
Bare Sand Island (12°32.3'S, 130°25.1'E), and Quail Island (12°31'S, 130°26'E), are located in northern Fog Bay, approximately 60 km west of Darwin, Northern Territory, Australia (Fig. 1). The only other settlement
Volume 36/Number l l/November 1998
categories of debris, between islands, beach orientation and years. It is difficult to single out any one source for many debris items. For this reason a cross-tabulation probability scoring system was used to try to identify major contributors to marine debris in Fog Bay. Although this method is an estimate only, it does examine in detail all debris items and major categories of debris and offers the best means of identifying possible sources of common debris items collected during beach surveys. First, all debris was regrouped into similar categories of use (e.g. fishing gear, common domestic items, etc.) to help identify potential sources (e.g. fishing nets from commercial fisherman, domestic items from commercial fishing and merchant vessels). Major groups of debris items were then crosstabulated with seven potential sources and given a score based on the likelihood that they originated from each source. Scores (3 = highly probable, 2 = probable,
is a small recreational fishing community (Dundee Beach) 22 km to the south. The islands lie on the end of a series of eight islands that extend 15 km north of the mainland. Wind patterns are usually from the south east during the Southern Hemisphere winter and from the south west during the summer (Bureau of Meteorology, 1989). Current patterns are generally from east to west (Wace, 1995). A major shipping route and prawn trawling grounds occur offshore while recreational fishers and boaters use the inshore area. The western (0.9 km) and eastern beaches (0.9 km) of Bare Sand Island were surveyed in June of 1996 and 1997 while the western beaches (2.4kin) of Quail Island were surveyed in 1996 only. Volunteers collected all anthropogenic debris between the water line and the storm surge line (20-30 m width). All debris items collected were grouped into categories according to their material. Chi-squared contingency tables werc used to compare the composition of the three main
Bare Sand Island
,~"
Darwin
Quail Island
F°gBay(~. ~ c. Dundee Beach
INDIAN
I
i
i
i
120
1313
1413
1~0
e
•~
~#, Gulfef | ~ ~%._Carpemar|8 I
-10
PACIFIC r~r-¢:^~
20 km ~
Adq|t4ide
1000 km
e ~
Hob~'l
-40
Fig. 1 Location map of Fog Bay in northern Australia.
905
Marine Pollution Bulletin
On Bare Sand Island the composition of total debris items from both beaches combined was not significantly different between 1996 and 1997 (Table 2). However, the composition varied between beach orientation with each year and within beach orientation (both eastern and western) between years. Basically, the total composition of debris did not vary on Bare Sand Island between years but altered in its distribution. The western beaches of Bare Sand Island and Quail Island also differed. By cross-tabulating scores of possible sources of debris against groups of debris items (Table 3) it was estimated that commercial fishers, recreational boaters and domestic merchant vessels contributed over 85% of all debris items. Land based sources were given low scores because the nearest urban centre is 60 km to the east and the prevailing winds (Bureau of Meteorology, 1989) in this region were unlikely to carry debris items south-west from Darwin (the nearest urban centre). Similarly, debris would be unlikely to travel 25 km north west from Dundee Beach, a small recreational fishing community. Land based items (1.43%) (excluding camping debris) included the remains of three weather balloons (0.5%). Four others were also
1 = possible, 0 = unlikely) were based on many criteria: writing and labels on the item, type of debris, distance to each source, amount of activity of each source within the region, seasonal wind (Bureau of Meteorology, 1989) and current patterns (Wace, 1995). The percentage that each potential source contributed to the total debris was then estimated.
Results In total 596 items were collected from Bare Sand and Quail Islands in 1996 and 1997 (Table 1 and Appendix 1). This included 125 (52/kin) items from Quail Island in 1996 and 202 (ll2/km) items and 269 (149/km) items from Bare Sand Island in 1996 and 1997, respectively. In total, synthetic products (plastic, rubber, foam) accounted for 45% of total items collected while metal and glass accounted for 35% and 15.6%, respectively (Table 1). Drink containers (53%) comprising metal cans (32.5%), plastic drink bottles (12%) and glass bottles (8%) were the most common items found on the beaches. Total items found on both beaches on Bare Sand Island increased from 202 in 1996 to 269 in 1997.
TABLE 1 A summary of items collected from Bare Sand Island in 1996 and 1997 and Quail Island in 1997. Values in parentheses represent the percentage of the total. Bare Sand Island 1996 Material
W
Synthetics Plastics Foam Rubber Metal Glass Wood Paper Fabric Other
E
W
E
65 (33.7) 13 (6.7) 11 (5.7) 68 (35.2) 36 (18.7)
20 (26.3) 1 (1.3) 1 (1.3) 39 (51.3) 12 (15.8)
1 (0.9)
23 (27.3) 9 (10.7) 3 (3.6) 23 (27.4) 14 (16.7) 1 (1.2) 3 (3.6) 2 (2.4) 6 (7.2)
118
84
193
39 4 4 55 8 5 2
Total
1997
(33.0) (3.4) (3.4) (46.6) (6.8) (4.2) (1.7)
Quail Island 1996 W 45 25 6 24 23
2 (2.3)
(36.0) (20.0) (4.8) (19.2) (18.4)
2 (1.6)
1 76
125
Total 192 52 25 209 93 6 9 2 8
(32.2) (8.7) (4.2) (35.1) (15.6) (1.0) (1.5) (0.3) (1.4)
596
W, west beach; E, east beach.
TABLE 2 Chi-squared homogeneity tests for debris composition between beaches. Three categories were used from Table 1 (Synthetics, Metal and Glass). Synthetic comprised Plastic, Rubber and Foam items. Comparison between beaches Bare Bare Bare Bare Bare Bare
Sand Sand Sand Sand Sand Sand
Is. 1996 (total) vs. Bare Sand Is. 1997 (total) Is. 1996 (FB) vs. Bare Sand Is. 1997 (FB) Is. 1996 (BB) vs. Bare Sand Is. 1997 (BB) Is. 1996 (FB) vs. Bare Sand Is. 1996 (BB) Is. 1997 (FB) vs. Bare Sand Is. 1997 (BB) Is (FB) 1996 vs. Quail Is. 1996
NS, not significant.
906
~(2
df
P
Sig.
3.45 27.49 7.38 9.(}4 7.64 53.42
2 2 2 2 2 2
> 0.5 <0.001 0.025 < P < 0.05 0.025 < P < 0.05 0.025
NS *** * * * ***
Volume 36/Number l 1/November 1098 TABLE 3
A cross tabttlation of scores was used to estimate the percentage of debris items that may be attributed to possible sources. Scores were based on the probability of each source contributing to .each category of debris (3 = highly probable, 2 = probable, 1 = possible, 0 = unlikely). Values in square brackets represent the percentage that each category of debris contributed to the total debris. Values in parentheses represent the possible percentage each source contributed to each category of debris (calculated from the proportion of probability). Recreational boaters
Domestic Merchant vessels
Commercial fishing vessels
Aluminium cans 126%l Plastic bottles [12.2%] Glass drink containers (8%) Common domestic (7.0%) Torn aluminium cans (6.4%) Fishing gear (6.09~) Footware (4.2%) Specialized domestic (3.4%) Foreign items (3.2~) Light globes (2.7%) Commercial items 12.11%) Eski/coolers (1.7%) Flotation 11.5%) Paper drink (I.3) 5 1oil containers (I.2%) Timber 11%) Weather balloons (11.5"74) Special light globes (0.3%) Nappy (1t.3) Other (11.15k)
3 (8.67) 3 (3.67) 3 (2.67) 3 (2.33) 3 (3.84)
2 (5.78) 3 (3.67) 3 (2.67) 3 (2.33) I (1.28)
3 (1.26)
3 (1.26) 3 (1.46)
2 (5.78) 3 (3.67) 3 (2.67) 3 (2.33) 1 (1.28) 3 (6.110) 3 (I.26) 3 (1.46)
3 (0.23) 3 (2.78)
3 (2.78)
3 (2.78)
1 (0.93)
1 111.07) ] (0.93)
1 (0.93)
Total (1110%)
(28.25)
125.1)
(32.25)
(1.43)
14.31)
(7.03)
3 (1.02) 3 (0.75) 3 (0.43) 3 (1/.60)
3 (1.35) 3 (1.00) 1 111.34) 3 (1/.43) 3 (11.75)
Urban/landbased
Camping
Foreign vessels
1 (2.89)
1 (2.89) 1 11.22)
Foreign shores
1 (0.42) 1 (11.49) 3 (2.40)
I (11.8)
3 (1.351 3 (1 .Ill}) 1 (0.34) 3 (0.75) 3 (11.43) 3 (0.611) 1 (11.25) 3 (11.5) 3 (0.31/)
o b s e r v e d outside the survey; two in the w a t e r and two on a n o t h e r beach. Items a t t r i b u t e d to c a m p e r s (4.3%) were given low scores b e c a u s e few g r o u p s visit the islands each year. Also, c a m p e r s can only access the islands by private p l e a s u r e craft, so this g r o u p o v e r l a p s with r e c r e a t i o n a l boaters. Items s u s p e c t e d to have o r i g i n a t e d from o c e a n - b a s e d sources included drink containers, d o m e s t i c items, light globes and fishing gear. S o m e c o m m o n d o m e s t i c items ( 7 % ) such as coffee and milk containers, j a m jars, various sauce bottles a n d m a r g a r i n e c o n t a i n e r s could be used by both large vessels (hmg trips) and r e c r e a t i o n a l b o a t e r s (day and w e e k e n d trips). However, s o m e specialized d o m e s t i c items (3.4%) such as clothes d e t e r g e n t containers, toilet cleaners, floor detergents, after shave bottles and i n c a n d e s c e n t and fluorescent light bulbs most likely o r i g i n a t e d from large m e r c h a n t o r fishing vessels. Similarly, c o m m e r c i a l items ( 2 % ) like 201 and 2(181 steel d r u m s and o t h e r items f o u n d on non surveyed b e a c h e s ( r e f r i g e r a t o r s and packing t i m b e r - 4 m lengths) are likely to have o r i g i n a t e d from larger vessels. Fishing g e a r ( 6 % ) such as ropes, polystyrene floats, trawl net and s o m e special light globes from their decks (0.3%) could be a t t r i b u t e d directly to commercial fisherman. Drink containers 153%) including a l u m i n i u m cans (33%), plastic bottles (12%) and glass bottles ( 8 % ) were the most n u m e r o u s items f o u n d on the b e a c h e s and could be a t t r i b u t e d to several user g r o u p s ( r e c r e a t i o n a l boats, m e r c h a n t and c o m m e r c i a l fishing vessels). However, the c o m m o n practice by r e c r e a t i o n a l b o a t e r s to tear their a l u m i n i u m cans across the c e n t r e b e f o r e discarding t h e m into the sea m e a n s that this user g r o u p was the most likely
Total 9 1(1 9 9 5 3 I11 7 4 6 6 5 6 9 6 4 3 3 4 3
11/.8)
sourcc of at least torn cans (6.4% of total items). T w e n t y - o n e p e r c e n t of the b e e r cans a n d 33% of soft drink cans were torn. N i n e t e e n items ( 3 % ) were identified as originating from foreign vessels or foreign shores by their label or o t h e r identifying m a r k s ( T a b l e 4).
Discussion Overall, synthetic (plastics, r u b b e r and f o a m ) and metal d e b r i s a c c o u n t e d for m o s t of the debris. This is similar to o t h e r studies which have shown that plastics (Pearce, 1992; Slater, 1992; W o o d a l l , 1993; W a c e , 1995), and in p a r t i c u l a r plastic bottles c o n t r i b u t e most to m a r i n e debris (Dixon and Dixon, 1983). T h e high p r o p o r t i o n of m e t a l debris in F o g Bay when c o m p a r e d with m o r e r e m o t e places (Benton, 1995) suggests that these items do not travel long distances and were p r o b a b l y d e p o s i t e d by user g r o u p s close to shore in
TABLE 4 A list of all items which could be identified as originating from foreign countries.
Country of origin Glass bottles Plastic bottles Cans Other Total Indonesia China West Germany Philippines USA Spain Other
1 2 I I 1 I I
2 2 2
Total
8
6
I
2
6 4 3 2 2 1 I
2
19
1 1
3
907
Marine Pollution Bulletin
Fog Bay (e.g. recreational boaters). Synthetic material, however, has the potential to remain in the environment for long periods and travel long distances (Slip and Burton, 1991; Benton, 1995) which means they could have originated from more distant sources (e.g. offshore fishing and shipping). Evidence of slow breakdown time comes from four plastic PET bottles with black bases found on the strand line of Bare Sand Island in 1997. The manufacture of these bottles ceased in southern states in 1992 and in the Northern Territory in 1995, which means that these bottles have been in the marine environment with no deterioration for at least 2 yr. Similarly, the production of steel drink cans ceased in 1991 in the Northern Territory but they were still found in the survey in 1997 (P. Harrington, personal communication 15 Dec. 1997). Some indication of the breakdown time of steel cans was given by the discovery of a cache of resurfaced Leeds' lemonade cans in the middle of Bare Sand Island. These cans were in good condition even though production ceased prior to 1986 (P. Harrington, personal communication 15 Dec. 1997) and were presumably left on Bare Sand Island by campers around this time. The number of items per linear kilometre was lower than other estimates from the southern coast of Australia (see Jones, 1994; Wace, 1995) but was high when considering the low population density in northern Australia. Total items on Bare Sand Island increased from 202 in 1996 to 269 in 1997. This is unusual because the beach was not cleared prior to 1996 and this survey should have represented many years of debris, while the 1997 survey should have represented accumulated debris from only 1 yr. An explanation for this is that annual surveys do not represent an accurate annual accumulation rate (Slip and Burton, 1991). There are two possible reasons for this: (1) differences in local wind direction and variation in tide height and intensity between seasons could remove or redistribute debris items; (2) sparse vegetation coverage causes large sand movement on the islands which covers and uncovers debris on a daily basis. This became apparent when debris items resurfaced in the dunes 24 h after the 1997 survey. Seasonal surveys of these islands may be needed to gain a more accurate indication of accumulation. The composition of debris items varied between beach orientation within each year and within beach orientation between years. However, a comparison of total debris on Bare Sand Island in 1996 and 1997 showed no significant difference in debris composition between years (Table 2). This showed that total composition between years has remained the same but distribution around the island changed. Preliminary results from this study suggest that a range of islands and beaches need to be sampled each year to obtain an unbiased assessment of total abundance and composition of debris for annual comparisons. 908
Sources of marine debris in Fog Bay Most debris items were attributed to ocean-based sources because of the lack of human settlement in the area and because debris items were characteristic of ocean borne waste. The prevailing wind patterns were the wrong direction to have driven land-based debris southwest from Darwin or north from Dundee Beach. This contrasts with many submissions to the Australian and New Zealand Environment and Conservation Council which suggest most debris results from landbased human activities (ANZECC, 1996). These results, however, were based on the populated coastlines of the eastern and southern states and not the remote northern coastline. Darwin is the nearest urban centre to Fog Bay and urban or industrial waste was not common in the survey. Also, unlike Queensland (Woodall, 1993), beach-goers are a small proportion of coastal users in Fog Bay; less than 20 groups visit Bare Sand and Quail Islands each year. Even though most items were identified as originating from ocean-based sources it was difficult to identify some groups of items (e.g. drink containers, the major item type) to any one source. The preliminary scoring system produced for this study (Table 3) provides a means of using all available data to predict the level on debris contributed by each possible source. This will inevitably need refining for future studies and for different study areas. Together, commercial fishing, recreational boating and merchant vessels were estimated to contribute 85% of the total debris items. This varies from other reports that attributes 89% of the six million tons per year of ocean vessel discharge to merchant ships (Pruter, 1987) or the majority of the debris to commercial fishing operations (Slater, 1992; Dalgetty and Hone, 1993; Jones, 1994). Large amounts of fishing debris, both domestic and foreign, are washed ashore each year in the Gulf of Carpentaria (N. Munungurritj, Ranger, Dhimirru Land Management Aboriginal Corporation, personal communication 11 Nov. 1997). A reduction in fishing debris on Fog Bay beaches over the past 10 yr (M. L. Guinea, personal communication 04 Dec. 1997) may be a result of better fishing practices by trawler operators. Debris in Fog Bay as a potential hazard to marine animals and humans Many items collected are a hazard to marine animals and also to humans. Plastics are probably the most dangerous because they are either readily ingested by, or entangle most animals (Laist, 1987). Sea turtles have been recorded entangled and dead in marine debris in waters around Darwin (Chatto et al., 1995). One of the most potentially dangerous items to marine animals were the remains of weather balloons, even though they represented only a small percentage of total items. In total, seven were observed; three from surveyed beaches, two from unsurveyed beaches and two at sea. They consisted of a foam base with the torn remains of
Volume 36/Number ll/November 1998 the rubber/plastic balloon. At sea the b a l l o o n section looked a n d b e h a v e d similar to jellyfish or squid which are m a j o r food sources for most animals. F o u r balloons are released by the B u r e a u of Meteorology from Darwin airport each day; 1460 per year. A s s u m i n g the n u m b e r which fall into the sea and o n t o the land are approximately equal, the r e m a i n s of approximately 730 w e a t h e r b a l l o o n s fall into the sea from this source each year a r o u n d Darwin. As most plastics are not biodegradable, a c c u m u l a t e d debris from this source may bc significant, especially when c o m b i n e d with all weather stations a r o u n d Australia. With today's technology, a b i o d e g r a d a b l e form of balloon and base should be an option. Many of the items f o u n d on the beaches of Fog Bay are a potential hazard to vessels. Large items such as the 2081 steel drums, packing timber a n d refrigerators f o u n d in Fog Bay can cause hull d a m a g e while ropes a n d nets can foul propellers and rudders and plastic sheet can block water intakes ( T o m k i n , 1989). In Australia a n d North America, high costs are associated with repairs to charter and commercial fishing vessels which have sustained d a m a g e due to m a r i n e debris (Jones, 1994). T h e large n u m b e r of sharp items, such as torn a l u m i n i u m cans, plastic and b r o k e n glass f o u n d on the beach has the potential to cause serious injuries (see Dixon and Dixon, 1981). Although not a direct hazard, the d e g r a d a t i o n of the aesthetic values of beaches a n d waterways can have a serious effect o n m a n y user groups. These groups include campers, bush walkers, adventurers, naturalists, tourists, recreational fishers and recreational boaters, most of whom visit and e n j o y these areas because of its physical and n a t u r a l wilderness values ( B r o c k m a n and Merriam, 1979; Ride, 1980). As m a r i n e debris is increasing in the world's oceans ( R y a n and Moloney, 1993), can travel long distances (Slip a n d Burton, 1991; B e n t o n , 1995) and has the potential to resurface (Ye and A n d r a d y , 1991), more research is r e q u i r e d to m o n i t o r , evaluate and identify m e t h o d s to reduce ocean d u m p i n g of waste materials. Funding for part of this project was provided by The Keep Australia Beautiful Committee/Territory Anti-Litter Campaign. Other funding from National Estates Grants Program and The Queens Trust for Young Australians for sea turtle research in this area contributed to this survey of marine debris. The author would like to thank all the volunteers who helped collect and sort the litter during the 1996 and 1997 surveys, Phil Harrington (Coca Cola Bottlers, Darwin) who provided historical information on some packaging items, and Michael Guinea, Michael Douglas, Diane Fontannaz and one anonymous reviewer for their comments on the manuscript. ANZECC (1996) Working Together to Reduce Impacts from Shipping Operations; ANZECC Strategy to Protect the Marine Em,ironment,
Vol. 1. Australian and New Zealand Conservation Council. Canberra. Balazs, G. H. (1985) Impact of ocean debris on marine turtles. In Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura
and O. Yoshida, pp. 387-429. NOAA Technical Memo: NMFS. NOAA-TM-NMFS-SWFSC-54,US Department of Commerce.
Benton, T. G. (1995) From castaways to throwaways: marine litter in the Pitcairn Islands. Biol. J. Linn. Soc. 56, 415-422. Bjorndal, K. A., Bolten, A. B. and Lageux, C. J. (1994) Ingestion of marine debris by juvenile sea turtles in coastal Florida habitats. Mar. Pollut. Bull 28, 154-158. Brockman, C. F. and Merriam, C., Jr. (1979) Recreational Use t~f Wild Lands', 3rd edn. McGraw-Hill, New York. Brown, E. D. (1994) The International Law of the Sea, Vol. 1. Introductory Manual. Dartmouth, Aldershot, 493 pp. Bureau of Meteorology (1989) Climate of Australia. Australian Government Publishing Service, Canberra. Cawthorn, M. W. (1985) Entanglement in, and ingestion of, plastic litter by marine mammals, sharks, and turtles in New Zealand waters. In Proceedings of the Workshop on the Fate and Impact of Marine Debris', 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura and O. Yoshida. NOAA Technical Memo: NMFS, NOAA-TM-NMFS-SWFSC-54,US Department of Commerce. Chatto, R. M. L., Guinea, M. L. and Conway, S. (1995) Marine turtles killed by flotsam in Northern Australia. Mar. Turt. News 69, 17-18. Dalgetty, A. and Hone, P. (1993) Flotsam and jetsom. Southern Fisheries Summer, 10-13. Day, R. H., Wehle, D. tt. S. and Coleman, F. C. (1985) Ingestion of plastic pollutants by marine birds. In Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura and O. Yoshida, pp. 344-386. NOAA Technical Memo: NMFS, NOAA-TM-NMFS-SWFSC-54, US Department of Commerce. Dixon, T. R. and Dixon, T. J. (1981) Marine litter surveillance. Mar. Pollat. BulL 12. 289-295. Dixon, T. J. and Dixon, T. R. (1983) Marine litter distribution and composition in the North Sea. Mar. Pollut. Bull. 14, 145-148. Fowler, C. W. (1987) Marine debris and northern fur seals: A case study. Mar. Pollut. Ball. 18, 326-335. Fry, D, M., Fefel, S. I. and Sileo, L. (1987) Ingestion of plastic debris by Layson albatrosses and wedge-tailed shearwaters in the Hawaiian Islands. Mar. Pollut~ Bull. 18, 339-343. Horsman, P. (1982) The amount of garbage pollution from merchant ships. Mar. Pollut. Bull. 13, 167-169. Jones, M. M. (1994) Fishing Debris in the Australia Marine Environment. Department of Primary Industries and Energy, Bureau of Resource Science. Australian Government Publishing Service, 39 pp. Laist, D. (19871 Overview of the biological effects of lost and discarded plastics debris in the marine environment. Mar. Pollut. Bull. 18, 319-326. Land Conservation Council ( 1991) Wildernes,~, Proposed Recommendations. Special Investigation. Land Conservation Council, Melbourne, 126 pp. Merrell, T. R. (1980) Accumulation of plastic litter on beaches of Amchitka Island, Alaska. Mar. Environ. Res. 3, 171-184. National Research Council (199(}) Decfine of the Sea Turtles'; Causes and Prevention. National Universi~ Press, Washington, DC. Pearce, J. B. (1992) Marine vessel debris: A North American perspective. Mar. Pollut. Bull. 12, 586-592. Pemberton, D.. Brothers, N. P. and Kirkwood, R. (1992) Entanglement of Australian fur seals in man-made debris in Tasmanian waters. WildL Res. 19, 151-159. Prutcr, A. T. (1987) Sources, quantities and distribution of persistent plastics in the marine environment. Mar. Pollut. Bull. 18, 305-310. Rees, G. and Pond, K. (1995) Marine litter monitoring programmes A review of methods with special reference to national surveys. Ma~ Pollut. Bull. 30, 1113-1(18. Ride, W. R. L. (1980) Wilderness: an Australian perspective. In -
-
WiMerne~'s Management in Austrafia, Proceedings Of a Symposium,
Canberra, 19-23 July 1978. Canberra College of Advanced Education, Canberra. Ryan, P. G. and Moloney, C. L. (1993) Marine litter keeps increasing.Nature 361, 23 Slater, J. (1991) Leopard seal entanglement in Tasmania, Australia. Mar. Mammal Sci. 7, 323 Slater, J. (1992) The incidence of marine debris in the south-west of the World Heritage Area. The Tasmanian Naturalist Oct., 32-35. Slip, D. J. and Burton, IV, H. R. (1991) Accumulation of fishing debris, plastic litter, and other artefacts on Heard and Macquarie Islands in the Southern Ocean. Environ. Conserv. 18, 249-254. 909
Marine Pollution Bulletin Tomkin, J. (1989) Plastic pollution: Turning the tide. Aust. Fish. Jan., 16-17. Wace. N. (1995) Ocean litter stranded on Australian coasts. In State
q[ the Marine Environment Report for Australia, Technical Annex 2, eds. L. Z a n n and D. Sutton. Ocean Rescue 2000, D e p a r t m e n t of the Environment, Sport and Territories, Canberra.
APPENDIX 1 List of total items collected from each beach in each year. BS, Bare Sand Island; W, west beach: E, east beach. Bare Sand Island 1996 W
1997 E
W
E
7
33
6
1I
4
Quail Island 1996 W
Total
Plastics Bottles - - drink Bottles - - foreign Bottles/containers - - other Lids Plant pot 5 I oil containers Bags Lighters Fishing gear Other Subtotal
13 I 2
14 4 8 1 1 2 I 1 4 9 45
73 5 25 3 3 7 7 6 15 48 192
2 2 9 7 5 25
3 10 2I 9 9 52
5 1 6
22 3 25
13 2 2 3 I
2 24
118 31 14 7 17 5 2 2 13 2119
3 1 1 12
2 1 4 2 4 7 2 1 23
5 13 14 10 9 25 7 11t 93
2
2
2 I 1
1 1 1
2 19 39
3 10 23
2 2
5
5 6 8 65
3 5
2 20
Foam W e a t h e r balloon Eski/cup/cooler Floats - - fishing Flotation - - boat Other Subtotal
4
1 1 1(I 1
1
4 9
13
1
2 1 3
I0 1 I1
1
Rubber Thongs Shoes Subtotal
4 4
1
Metal Beer can (aluminium) Beer can torn Soft can Soft can torn Unidentified can Spirit can Drink can (steel) 208 1 d r u m Miscellaneous Subtotal
30 8 5 2 4 4
12 2 I 1
1 1 1 1 5 55 23
33 30 18 I 3 4 1 7 4 1
I 5 68
39
Glass Fluorescent bulb Incandescent bulb Beer bottles Foreign alcohol Spirit/wine/bottle Soft drink bottle Jars O t h e r bottles Subtotal Wood Paper Fabric Other Total
910
1 2 2
1 1 l 8 5 2 1 118
1 1 3 3 2 4 14
1 8 3 7 2 11 I 3 36
I 3 "~ 6 84
2 4 I
1 193
76
125
6 9 "~ 8 596
Walker, S. (1989) Deadly debris. Cruising Helsman Feb., 16-19. Ye, S. and Andrady, A. (1991) Fouling of floating plastic debris under Biscayne Bay Exposure conditions. Mar. Pollut. Bull. 22, 608-613. Woodall, P. F. (1993) Marine litter on the beaches of Deepwater National Park, central Queensland. QId. Nat. 32, 72-75.
Marine Polh~tion Bulletbl, Vol. 36. No. 11, pp. 904-910, 1998 © 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain [~125-326X/98 $19,(~+{).00
Types and Sources of Marine Debris in Fog Bay, Northern Australia SCOTT D. WHITING Faculty of Science, Northern Territory University, Darwin, N T 0909, Australia Marine debris items were collected and categorized during surveys of beaches in Fog Bay, northern Australia in 1996 and 1997. Synthetic items (45%) were the most numerous followed by metal (35%) and glass (16%). Drink containers contributed 53% of the total items, while fishing gear and foreign material contributed only 4% and 3%, respectively. Scores were given to each possible source of marine debris according to their likelihood of contributing to each group of debris items. Using this method, commercial fishing, merchant shipping and recreational boaters were likely to contribute to over 85% of all debris items. Composition of debris items varied between beach orientation within the same year and within beach orientation between years, which suggests that a number of beaches and locations should be sampled to obtain an unbiased estimate of marine debris for annual comparisons. © 1998 Elsevier Science Ltd. All rights reserved Keywords: debris; marine; Australia; source; litter; rubbish; pollution.
Anthropogenic debris in the marine environment poses a serious threat to marine animals (Laist, 1987). Many types of debris including plastics and fishing gear, either entangle or are ingested by marine mammals (Fowler, 1987; Laist, 1987; Walker, 1989; Slater, 1991; Pemberton et al., 1992), turtles (Balazs, 1985; Bjorndal et al., 1994; Chatto et al., 1995), birds (Day et al., 1985; Fry et al., 1987; Slater, 1992), fish (Cawthorn, 1985; Jones, 1994) and crustaceans (Laist, 1987). Debris washed ashore also poses a hazard for terrestrial animals (Merrell, 1980) and can hinder and entrap sea turtle hatchlings and adults when they are on the beach during the nesting season (National Research Council, 1990). Marine debris not only represents a hazard to marine animals but may impact on many human activities as well. Marine debris damages and fouls shipping (Tomkin, 1989), causes injuries on beaches (Dixon and Dixon, 1981), poses a hazard to divers (Jones, 1994) and aesthetically degrades wilderness values (Land Conservation Council, 1991) and multi-use coastal habitat. International law implemented in 1988 (MARPOL, The International Convention for the Prevention of 904
Pollution from Ships, Annex V 1973/1978, see Brown, 1994) and Australian legislation implemented in 1990 (Protection of the Sea Act 1983 - - Prevention of Pollution from Ships) regulates the discharge of debris in Australian waters. Under these laws it is prohibited to discharge plastics and the discharge of other items is restricted by minimum distance from shore regulations. These laws, however, are difficult to enforce and illegal dumping of debris continues (Ryan and Moloney, 1993). To reduce debris in the marine environment, the sources of the debris must be identified (ANZECC, 1996) and practices implemented to reduce the amount discarded. There are two main sources of marine debris; oceanborne waste disposed of at sea and terrestrial waste originating from coastal users and urban centres (Rees and Pond, 1995). These two categories must be broken down further to identify user groups which contribute to the majority of the waste. Marine debris monitoring programs can help to identify the source, although most are aimed at determining amount and type rather than origin. Three main methods of monitoring have been used: (1) surveys to estimate the quantity and types of wastes generated by ships and pleasure craft (Horsman, 1982), (2) sea based surveys of the ocean surface to assess the amount and type of floating debris at sea (Dixon and Dixon, 1983) and (3) beach surveys to assess the type and amount of debris on a section of coast at a given time (for Australia see Wace, 1995). For a review of general methods for each of these types of surveys see Rees and Pond (1995). This study used beach surveys in Fog Bay to: (1) assess the amount of debris and categorize it by type of material, (2) identify individual pieces of debris and determine possible sources and (3) remove marine debris from those beaches surveyed in Fog Bay. This study is the first quantitative survey of marine debris on the northern Austi'alian coast between Cape York and North West Cape (Wace, 1995). Methods
Bare Sand Island (12°32.3'S, 130°25.1'E), and Quail Island (12°31'S, 130°26'E), are located in northern Fog Bay, approximately 60 km west of Darwin, Northern Territory, Australia (Fig. 1). The only other settlement
Volume 36/Number l l/November 1998
categories of debris, between islands, beach orientation and years. It is difficult to single out any one source for many debris items. For this reason a cross-tabulation probability scoring system was used to try to identify major contributors to marine debris in Fog Bay. Although this method is an estimate only, it does examine in detail all debris items and major categories of debris and offers the best means of identifying possible sources of common debris items collected during beach surveys. First, all debris was regrouped into similar categories of use (e.g. fishing gear, common domestic items, etc.) to help identify potential sources (e.g. fishing nets from commercial fisherman, domestic items from commercial fishing and merchant vessels). Major groups of debris items were then crosstabulated with seven potential sources and given a score based on the likelihood that they originated from each source. Scores (3 = highly probable, 2 = probable,
is a small recreational fishing community (Dundee Beach) 22 km to the south. The islands lie on the end of a series of eight islands that extend 15 km north of the mainland. Wind patterns are usually from the south east during the Southern Hemisphere winter and from the south west during the summer (Bureau of Meteorology, 1989). Current patterns are generally from east to west (Wace, 1995). A major shipping route and prawn trawling grounds occur offshore while recreational fishers and boaters use the inshore area. The western (0.9 km) and eastern beaches (0.9 km) of Bare Sand Island were surveyed in June of 1996 and 1997 while the western beaches (2.4kin) of Quail Island were surveyed in 1996 only. Volunteers collected all anthropogenic debris between the water line and the storm surge line (20-30 m width). All debris items collected were grouped into categories according to their material. Chi-squared contingency tables werc used to compare the composition of the three main
Bare Sand Island
,~"
Darwin
Quail Island
F°gBay(~. ~ c. Dundee Beach
INDIAN
I
i
i
i
120
1313
1413
1~0
e
•~
~#, Gulfef | ~ ~%._Carpemar|8 I
-10
PACIFIC r~r-¢:^~
20 km ~
Adq|t4ide
1000 km
e ~
Hob~'l
-40
Fig. 1 Location map of Fog Bay in northern Australia.
905
Marine Pollution Bulletin
On Bare Sand Island the composition of total debris items from both beaches combined was not significantly different between 1996 and 1997 (Table 2). However, the composition varied between beach orientation with each year and within beach orientation (both eastern and western) between years. Basically, the total composition of debris did not vary on Bare Sand Island between years but altered in its distribution. The western beaches of Bare Sand Island and Quail Island also differed. By cross-tabulating scores of possible sources of debris against groups of debris items (Table 3) it was estimated that commercial fishers, recreational boaters and domestic merchant vessels contributed over 85% of all debris items. Land based sources were given low scores because the nearest urban centre is 60 km to the east and the prevailing winds (Bureau of Meteorology, 1989) in this region were unlikely to carry debris items south-west from Darwin (the nearest urban centre). Similarly, debris would be unlikely to travel 25 km north west from Dundee Beach, a small recreational fishing community. Land based items (1.43%) (excluding camping debris) included the remains of three weather balloons (0.5%). Four others were also
1 = possible, 0 = unlikely) were based on many criteria: writing and labels on the item, type of debris, distance to each source, amount of activity of each source within the region, seasonal wind (Bureau of Meteorology, 1989) and current patterns (Wace, 1995). The percentage that each potential source contributed to the total debris was then estimated.
Results In total 596 items were collected from Bare Sand and Quail Islands in 1996 and 1997 (Table 1 and Appendix 1). This included 125 (52/kin) items from Quail Island in 1996 and 202 (ll2/km) items and 269 (149/km) items from Bare Sand Island in 1996 and 1997, respectively. In total, synthetic products (plastic, rubber, foam) accounted for 45% of total items collected while metal and glass accounted for 35% and 15.6%, respectively (Table 1). Drink containers (53%) comprising metal cans (32.5%), plastic drink bottles (12%) and glass bottles (8%) were the most common items found on the beaches. Total items found on both beaches on Bare Sand Island increased from 202 in 1996 to 269 in 1997.
TABLE 1 A summary of items collected from Bare Sand Island in 1996 and 1997 and Quail Island in 1997. Values in parentheses represent the percentage of the total. Bare Sand Island 1996 Material
W
Synthetics Plastics Foam Rubber Metal Glass Wood Paper Fabric Other
E
W
E
65 (33.7) 13 (6.7) 11 (5.7) 68 (35.2) 36 (18.7)
20 (26.3) 1 (1.3) 1 (1.3) 39 (51.3) 12 (15.8)
1 (0.9)
23 (27.3) 9 (10.7) 3 (3.6) 23 (27.4) 14 (16.7) 1 (1.2) 3 (3.6) 2 (2.4) 6 (7.2)
118
84
193
39 4 4 55 8 5 2
Total
1997
(33.0) (3.4) (3.4) (46.6) (6.8) (4.2) (1.7)
Quail Island 1996 W 45 25 6 24 23
2 (2.3)
(36.0) (20.0) (4.8) (19.2) (18.4)
2 (1.6)
1 76
125
Total 192 52 25 209 93 6 9 2 8
(32.2) (8.7) (4.2) (35.1) (15.6) (1.0) (1.5) (0.3) (1.4)
596
W, west beach; E, east beach.
TABLE 2 Chi-squared homogeneity tests for debris composition between beaches. Three categories were used from Table 1 (Synthetics, Metal and Glass). Synthetic comprised Plastic, Rubber and Foam items. Comparison between beaches Bare Bare Bare Bare Bare Bare
Sand Sand Sand Sand Sand Sand
Is. 1996 (total) vs. Bare Sand Is. 1997 (total) Is. 1996 (FB) vs. Bare Sand Is. 1997 (FB) Is. 1996 (BB) vs. Bare Sand Is. 1997 (BB) Is. 1996 (FB) vs. Bare Sand Is. 1996 (BB) Is. 1997 (FB) vs. Bare Sand Is. 1997 (BB) Is (FB) 1996 vs. Quail Is. 1996
NS, not significant.
906
~(2
df
P
Sig.
3.45 27.49 7.38 9.(}4 7.64 53.42
2 2 2 2 2 2
> 0.5 <0.001 0.025 < P < 0.05 0.025 < P < 0.05 0.025
NS *** * * * ***
Volume 36/Number l 1/November 1098 TABLE 3
A cross tabttlation of scores was used to estimate the percentage of debris items that may be attributed to possible sources. Scores were based on the probability of each source contributing to .each category of debris (3 = highly probable, 2 = probable, 1 = possible, 0 = unlikely). Values in square brackets represent the percentage that each category of debris contributed to the total debris. Values in parentheses represent the possible percentage each source contributed to each category of debris (calculated from the proportion of probability). Recreational boaters
Domestic Merchant vessels
Commercial fishing vessels
Aluminium cans 126%l Plastic bottles [12.2%] Glass drink containers (8%) Common domestic (7.0%) Torn aluminium cans (6.4%) Fishing gear (6.09~) Footware (4.2%) Specialized domestic (3.4%) Foreign items (3.2~) Light globes (2.7%) Commercial items 12.11%) Eski/coolers (1.7%) Flotation 11.5%) Paper drink (I.3) 5 1oil containers (I.2%) Timber 11%) Weather balloons (11.5"74) Special light globes (0.3%) Nappy (1t.3) Other (11.15k)
3 (8.67) 3 (3.67) 3 (2.67) 3 (2.33) 3 (3.84)
2 (5.78) 3 (3.67) 3 (2.67) 3 (2.33) I (1.28)
3 (1.26)
3 (1.26) 3 (1.46)
2 (5.78) 3 (3.67) 3 (2.67) 3 (2.33) 1 (1.28) 3 (6.110) 3 (I.26) 3 (1.46)
3 (0.23) 3 (2.78)
3 (2.78)
3 (2.78)
1 (0.93)
1 111.07) ] (0.93)
1 (0.93)
Total (1110%)
(28.25)
125.1)
(32.25)
(1.43)
14.31)
(7.03)
3 (1.02) 3 (0.75) 3 (0.43) 3 (1/.60)
3 (1.35) 3 (1.00) 1 111.34) 3 (1/.43) 3 (11.75)
Urban/landbased
Camping
Foreign vessels
1 (2.89)
1 (2.89) 1 11.22)
Foreign shores
1 (0.42) 1 (11.49) 3 (2.40)
I (11.8)
3 (1.351 3 (1 .Ill}) 1 (0.34) 3 (0.75) 3 (11.43) 3 (0.611) 1 (11.25) 3 (11.5) 3 (0.31/)
o b s e r v e d outside the survey; two in the w a t e r and two on a n o t h e r beach. Items a t t r i b u t e d to c a m p e r s (4.3%) were given low scores b e c a u s e few g r o u p s visit the islands each year. Also, c a m p e r s can only access the islands by private p l e a s u r e craft, so this g r o u p o v e r l a p s with r e c r e a t i o n a l boaters. Items s u s p e c t e d to have o r i g i n a t e d from o c e a n - b a s e d sources included drink containers, d o m e s t i c items, light globes and fishing gear. S o m e c o m m o n d o m e s t i c items ( 7 % ) such as coffee and milk containers, j a m jars, various sauce bottles a n d m a r g a r i n e c o n t a i n e r s could be used by both large vessels (hmg trips) and r e c r e a t i o n a l b o a t e r s (day and w e e k e n d trips). However, s o m e specialized d o m e s t i c items (3.4%) such as clothes d e t e r g e n t containers, toilet cleaners, floor detergents, after shave bottles and i n c a n d e s c e n t and fluorescent light bulbs most likely o r i g i n a t e d from large m e r c h a n t o r fishing vessels. Similarly, c o m m e r c i a l items ( 2 % ) like 201 and 2(181 steel d r u m s and o t h e r items f o u n d on non surveyed b e a c h e s ( r e f r i g e r a t o r s and packing t i m b e r - 4 m lengths) are likely to have o r i g i n a t e d from larger vessels. Fishing g e a r ( 6 % ) such as ropes, polystyrene floats, trawl net and s o m e special light globes from their decks (0.3%) could be a t t r i b u t e d directly to commercial fisherman. Drink containers 153%) including a l u m i n i u m cans (33%), plastic bottles (12%) and glass bottles ( 8 % ) were the most n u m e r o u s items f o u n d on the b e a c h e s and could be a t t r i b u t e d to several user g r o u p s ( r e c r e a t i o n a l boats, m e r c h a n t and c o m m e r c i a l fishing vessels). However, the c o m m o n practice by r e c r e a t i o n a l b o a t e r s to tear their a l u m i n i u m cans across the c e n t r e b e f o r e discarding t h e m into the sea m e a n s that this user g r o u p was the most likely
Total 9 1(1 9 9 5 3 I11 7 4 6 6 5 6 9 6 4 3 3 4 3
11/.8)
sourcc of at least torn cans (6.4% of total items). T w e n t y - o n e p e r c e n t of the b e e r cans a n d 33% of soft drink cans were torn. N i n e t e e n items ( 3 % ) were identified as originating from foreign vessels or foreign shores by their label or o t h e r identifying m a r k s ( T a b l e 4).
Discussion Overall, synthetic (plastics, r u b b e r and f o a m ) and metal d e b r i s a c c o u n t e d for m o s t of the debris. This is similar to o t h e r studies which have shown that plastics (Pearce, 1992; Slater, 1992; W o o d a l l , 1993; W a c e , 1995), and in p a r t i c u l a r plastic bottles c o n t r i b u t e most to m a r i n e debris (Dixon and Dixon, 1983). T h e high p r o p o r t i o n of m e t a l debris in F o g Bay when c o m p a r e d with m o r e r e m o t e places (Benton, 1995) suggests that these items do not travel long distances and were p r o b a b l y d e p o s i t e d by user g r o u p s close to shore in
TABLE 4 A list of all items which could be identified as originating from foreign countries.
Country of origin Glass bottles Plastic bottles Cans Other Total Indonesia China West Germany Philippines USA Spain Other
1 2 I I 1 I I
2 2 2
Total
8
6
I
2
6 4 3 2 2 1 I
2
19
1 1
3
907
Marine Pollution Bulletin
Fog Bay (e.g. recreational boaters). Synthetic material, however, has the potential to remain in the environment for long periods and travel long distances (Slip and Burton, 1991; Benton, 1995) which means they could have originated from more distant sources (e.g. offshore fishing and shipping). Evidence of slow breakdown time comes from four plastic PET bottles with black bases found on the strand line of Bare Sand Island in 1997. The manufacture of these bottles ceased in southern states in 1992 and in the Northern Territory in 1995, which means that these bottles have been in the marine environment with no deterioration for at least 2 yr. Similarly, the production of steel drink cans ceased in 1991 in the Northern Territory but they were still found in the survey in 1997 (P. Harrington, personal communication 15 Dec. 1997). Some indication of the breakdown time of steel cans was given by the discovery of a cache of resurfaced Leeds' lemonade cans in the middle of Bare Sand Island. These cans were in good condition even though production ceased prior to 1986 (P. Harrington, personal communication 15 Dec. 1997) and were presumably left on Bare Sand Island by campers around this time. The number of items per linear kilometre was lower than other estimates from the southern coast of Australia (see Jones, 1994; Wace, 1995) but was high when considering the low population density in northern Australia. Total items on Bare Sand Island increased from 202 in 1996 to 269 in 1997. This is unusual because the beach was not cleared prior to 1996 and this survey should have represented many years of debris, while the 1997 survey should have represented accumulated debris from only 1 yr. An explanation for this is that annual surveys do not represent an accurate annual accumulation rate (Slip and Burton, 1991). There are two possible reasons for this: (1) differences in local wind direction and variation in tide height and intensity between seasons could remove or redistribute debris items; (2) sparse vegetation coverage causes large sand movement on the islands which covers and uncovers debris on a daily basis. This became apparent when debris items resurfaced in the dunes 24 h after the 1997 survey. Seasonal surveys of these islands may be needed to gain a more accurate indication of accumulation. The composition of debris items varied between beach orientation within each year and within beach orientation between years. However, a comparison of total debris on Bare Sand Island in 1996 and 1997 showed no significant difference in debris composition between years (Table 2). This showed that total composition between years has remained the same but distribution around the island changed. Preliminary results from this study suggest that a range of islands and beaches need to be sampled each year to obtain an unbiased assessment of total abundance and composition of debris for annual comparisons. 908
Sources of marine debris in Fog Bay Most debris items were attributed to ocean-based sources because of the lack of human settlement in the area and because debris items were characteristic of ocean borne waste. The prevailing wind patterns were the wrong direction to have driven land-based debris southwest from Darwin or north from Dundee Beach. This contrasts with many submissions to the Australian and New Zealand Environment and Conservation Council which suggest most debris results from landbased human activities (ANZECC, 1996). These results, however, were based on the populated coastlines of the eastern and southern states and not the remote northern coastline. Darwin is the nearest urban centre to Fog Bay and urban or industrial waste was not common in the survey. Also, unlike Queensland (Woodall, 1993), beach-goers are a small proportion of coastal users in Fog Bay; less than 20 groups visit Bare Sand and Quail Islands each year. Even though most items were identified as originating from ocean-based sources it was difficult to identify some groups of items (e.g. drink containers, the major item type) to any one source. The preliminary scoring system produced for this study (Table 3) provides a means of using all available data to predict the level on debris contributed by each possible source. This will inevitably need refining for future studies and for different study areas. Together, commercial fishing, recreational boating and merchant vessels were estimated to contribute 85% of the total debris items. This varies from other reports that attributes 89% of the six million tons per year of ocean vessel discharge to merchant ships (Pruter, 1987) or the majority of the debris to commercial fishing operations (Slater, 1992; Dalgetty and Hone, 1993; Jones, 1994). Large amounts of fishing debris, both domestic and foreign, are washed ashore each year in the Gulf of Carpentaria (N. Munungurritj, Ranger, Dhimirru Land Management Aboriginal Corporation, personal communication 11 Nov. 1997). A reduction in fishing debris on Fog Bay beaches over the past 10 yr (M. L. Guinea, personal communication 04 Dec. 1997) may be a result of better fishing practices by trawler operators. Debris in Fog Bay as a potential hazard to marine animals and humans Many items collected are a hazard to marine animals and also to humans. Plastics are probably the most dangerous because they are either readily ingested by, or entangle most animals (Laist, 1987). Sea turtles have been recorded entangled and dead in marine debris in waters around Darwin (Chatto et al., 1995). One of the most potentially dangerous items to marine animals were the remains of weather balloons, even though they represented only a small percentage of total items. In total, seven were observed; three from surveyed beaches, two from unsurveyed beaches and two at sea. They consisted of a foam base with the torn remains of
Volume 36/Number ll/November 1998 the rubber/plastic balloon. At sea the b a l l o o n section looked a n d b e h a v e d similar to jellyfish or squid which are m a j o r food sources for most animals. F o u r balloons are released by the B u r e a u of Meteorology from Darwin airport each day; 1460 per year. A s s u m i n g the n u m b e r which fall into the sea and o n t o the land are approximately equal, the r e m a i n s of approximately 730 w e a t h e r b a l l o o n s fall into the sea from this source each year a r o u n d Darwin. As most plastics are not biodegradable, a c c u m u l a t e d debris from this source may bc significant, especially when c o m b i n e d with all weather stations a r o u n d Australia. With today's technology, a b i o d e g r a d a b l e form of balloon and base should be an option. Many of the items f o u n d on the beaches of Fog Bay are a potential hazard to vessels. Large items such as the 2081 steel drums, packing timber a n d refrigerators f o u n d in Fog Bay can cause hull d a m a g e while ropes a n d nets can foul propellers and rudders and plastic sheet can block water intakes ( T o m k i n , 1989). In Australia a n d North America, high costs are associated with repairs to charter and commercial fishing vessels which have sustained d a m a g e due to m a r i n e debris (Jones, 1994). T h e large n u m b e r of sharp items, such as torn a l u m i n i u m cans, plastic and b r o k e n glass f o u n d on the beach has the potential to cause serious injuries (see Dixon and Dixon, 1981). Although not a direct hazard, the d e g r a d a t i o n of the aesthetic values of beaches a n d waterways can have a serious effect o n m a n y user groups. These groups include campers, bush walkers, adventurers, naturalists, tourists, recreational fishers and recreational boaters, most of whom visit and e n j o y these areas because of its physical and n a t u r a l wilderness values ( B r o c k m a n and Merriam, 1979; Ride, 1980). As m a r i n e debris is increasing in the world's oceans ( R y a n and Moloney, 1993), can travel long distances (Slip a n d Burton, 1991; B e n t o n , 1995) and has the potential to resurface (Ye and A n d r a d y , 1991), more research is r e q u i r e d to m o n i t o r , evaluate and identify m e t h o d s to reduce ocean d u m p i n g of waste materials. Funding for part of this project was provided by The Keep Australia Beautiful Committee/Territory Anti-Litter Campaign. Other funding from National Estates Grants Program and The Queens Trust for Young Australians for sea turtle research in this area contributed to this survey of marine debris. The author would like to thank all the volunteers who helped collect and sort the litter during the 1996 and 1997 surveys, Phil Harrington (Coca Cola Bottlers, Darwin) who provided historical information on some packaging items, and Michael Guinea, Michael Douglas, Diane Fontannaz and one anonymous reviewer for their comments on the manuscript. ANZECC (1996) Working Together to Reduce Impacts from Shipping Operations; ANZECC Strategy to Protect the Marine Em,ironment,
Vol. 1. Australian and New Zealand Conservation Council. Canberra. Balazs, G. H. (1985) Impact of ocean debris on marine turtles. In Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura
and O. Yoshida, pp. 387-429. NOAA Technical Memo: NMFS. NOAA-TM-NMFS-SWFSC-54,US Department of Commerce.
Benton, T. G. (1995) From castaways to throwaways: marine litter in the Pitcairn Islands. Biol. J. Linn. Soc. 56, 415-422. Bjorndal, K. A., Bolten, A. B. and Lageux, C. J. (1994) Ingestion of marine debris by juvenile sea turtles in coastal Florida habitats. Mar. Pollut. Bull 28, 154-158. Brockman, C. F. and Merriam, C., Jr. (1979) Recreational Use t~f Wild Lands', 3rd edn. McGraw-Hill, New York. Brown, E. D. (1994) The International Law of the Sea, Vol. 1. Introductory Manual. Dartmouth, Aldershot, 493 pp. Bureau of Meteorology (1989) Climate of Australia. Australian Government Publishing Service, Canberra. Cawthorn, M. W. (1985) Entanglement in, and ingestion of, plastic litter by marine mammals, sharks, and turtles in New Zealand waters. In Proceedings of the Workshop on the Fate and Impact of Marine Debris', 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura and O. Yoshida. NOAA Technical Memo: NMFS, NOAA-TM-NMFS-SWFSC-54,US Department of Commerce. Chatto, R. M. L., Guinea, M. L. and Conway, S. (1995) Marine turtles killed by flotsam in Northern Australia. Mar. Turt. News 69, 17-18. Dalgetty, A. and Hone, P. (1993) Flotsam and jetsom. Southern Fisheries Summer, 10-13. Day, R. H., Wehle, D. tt. S. and Coleman, F. C. (1985) Ingestion of plastic pollutants by marine birds. In Proceedings of the Workshop on the Fate and Impact of Marine Debris, 27-29 November 1984, Honolulu, HI, eds. R. S. Shomura and O. Yoshida, pp. 344-386. NOAA Technical Memo: NMFS, NOAA-TM-NMFS-SWFSC-54, US Department of Commerce. Dixon, T. R. and Dixon, T. J. (1981) Marine litter surveillance. Mar. Pollat. BulL 12. 289-295. Dixon, T. J. and Dixon, T. R. (1983) Marine litter distribution and composition in the North Sea. Mar. Pollut. Bull. 14, 145-148. Fowler, C. W. (1987) Marine debris and northern fur seals: A case study. Mar. Pollut. Ball. 18, 326-335. Fry, D, M., Fefel, S. I. and Sileo, L. (1987) Ingestion of plastic debris by Layson albatrosses and wedge-tailed shearwaters in the Hawaiian Islands. Mar. Pollut~ Bull. 18, 339-343. Horsman, P. (1982) The amount of garbage pollution from merchant ships. Mar. Pollut. Bull. 13, 167-169. Jones, M. M. (1994) Fishing Debris in the Australia Marine Environment. Department of Primary Industries and Energy, Bureau of Resource Science. Australian Government Publishing Service, 39 pp. Laist, D. (19871 Overview of the biological effects of lost and discarded plastics debris in the marine environment. Mar. Pollut. Bull. 18, 319-326. Land Conservation Council ( 1991) Wildernes,~, Proposed Recommendations. Special Investigation. Land Conservation Council, Melbourne, 126 pp. Merrell, T. R. (1980) Accumulation of plastic litter on beaches of Amchitka Island, Alaska. Mar. Environ. Res. 3, 171-184. National Research Council (199(}) Decfine of the Sea Turtles'; Causes and Prevention. National Universi~ Press, Washington, DC. Pearce, J. B. (1992) Marine vessel debris: A North American perspective. Mar. Pollut. Bull. 12, 586-592. Pemberton, D.. Brothers, N. P. and Kirkwood, R. (1992) Entanglement of Australian fur seals in man-made debris in Tasmanian waters. WildL Res. 19, 151-159. Prutcr, A. T. (1987) Sources, quantities and distribution of persistent plastics in the marine environment. Mar. Pollut. Bull. 18, 305-310. Rees, G. and Pond, K. (1995) Marine litter monitoring programmes A review of methods with special reference to national surveys. Ma~ Pollut. Bull. 30, 1113-1(18. Ride, W. R. L. (1980) Wilderness: an Australian perspective. In -
-
WiMerne~'s Management in Austrafia, Proceedings Of a Symposium,
Canberra, 19-23 July 1978. Canberra College of Advanced Education, Canberra. Ryan, P. G. and Moloney, C. L. (1993) Marine litter keeps increasing.Nature 361, 23 Slater, J. (1991) Leopard seal entanglement in Tasmania, Australia. Mar. Mammal Sci. 7, 323 Slater, J. (1992) The incidence of marine debris in the south-west of the World Heritage Area. The Tasmanian Naturalist Oct., 32-35. Slip, D. J. and Burton, IV, H. R. (1991) Accumulation of fishing debris, plastic litter, and other artefacts on Heard and Macquarie Islands in the Southern Ocean. Environ. Conserv. 18, 249-254. 909
Marine Pollution Bulletin Tomkin, J. (1989) Plastic pollution: Turning the tide. Aust. Fish. Jan., 16-17. Wace. N. (1995) Ocean litter stranded on Australian coasts. In State
q[ the Marine Environment Report for Australia, Technical Annex 2, eds. L. Z a n n and D. Sutton. Ocean Rescue 2000, D e p a r t m e n t of the Environment, Sport and Territories, Canberra.
APPENDIX 1 List of total items collected from each beach in each year. BS, Bare Sand Island; W, west beach: E, east beach. Bare Sand Island 1996 W
1997 E
W
E
7
33
6
1I
4
Quail Island 1996 W
Total
Plastics Bottles - - drink Bottles - - foreign Bottles/containers - - other Lids Plant pot 5 I oil containers Bags Lighters Fishing gear Other Subtotal
13 I 2
14 4 8 1 1 2 I 1 4 9 45
73 5 25 3 3 7 7 6 15 48 192
2 2 9 7 5 25
3 10 2I 9 9 52
5 1 6
22 3 25
13 2 2 3 I
2 24
118 31 14 7 17 5 2 2 13 2119
3 1 1 12
2 1 4 2 4 7 2 1 23
5 13 14 10 9 25 7 11t 93
2
2
2 I 1
1 1 1
2 19 39
3 10 23
2 2
5
5 6 8 65
3 5
2 20
Foam W e a t h e r balloon Eski/cup/cooler Floats - - fishing Flotation - - boat Other Subtotal
4
1 1 1(I 1
1
4 9
13
1
2 1 3
I0 1 I1
1
Rubber Thongs Shoes Subtotal
4 4
1
Metal Beer can (aluminium) Beer can torn Soft can Soft can torn Unidentified can Spirit can Drink can (steel) 208 1 d r u m Miscellaneous Subtotal
30 8 5 2 4 4
12 2 I 1
1 1 1 1 5 55 23
33 30 18 I 3 4 1 7 4 1
I 5 68
39
Glass Fluorescent bulb Incandescent bulb Beer bottles Foreign alcohol Spirit/wine/bottle Soft drink bottle Jars O t h e r bottles Subtotal Wood Paper Fabric Other Total
910
1 2 2
1 1 l 8 5 2 1 118
1 1 3 3 2 4 14
1 8 3 7 2 11 I 3 36
I 3 "~ 6 84
2 4 I
1 193
76
125
6 9 "~ 8 596
Walker, S. (1989) Deadly debris. Cruising Helsman Feb., 16-19. Ye, S. and Andrady, A. (1991) Fouling of floating plastic debris under Biscayne Bay Exposure conditions. Mar. Pollut. Bull. 22, 608-613. Woodall, P. F. (1993) Marine litter on the beaches of Deepwater National Park, central Queensland. QId. Nat. 32, 72-75.