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Compiled by Leon P. Zann
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1995)
ISBN 0 642 17391 5
Around 60,000 different synthetic compounds have been produced for agricultural and industrial use over the past 50 years, and an additional 5,000 are now being produced each year. The persistence and toxicity of one group of synthetic chemicals, the organochlorine compounds, have made them very effective pesticides but has also made them potential environmental threats. Although organochlorines are present in very low concentrations in the sea, they are preferentially soluble in animal fats where they may reach 50,000 times the concentration in surrounding waters. They may also bioaccumulate in food chains and become most concentrated in predatory fish, seabirds, marine mammals and humans.(45)
A range of organochlorine compounds have been widely used in Australia as herbicides (2,4-D, 2,4,5-T), insecticides (DDT, lindane, chlordane), fungicides (hexachlorobenzene, chlorinated phenyls) and as insulating fluids (poly-chlorinated biphenyls, or PCBs). Organochlorines are also produced in chlorination processes such as chlorine pulp bleaching(45). These substances have a wide range of persistences; some break down quickly in sunlight and moisture but persist within fats(84).
Little is known of the levels of these in Australia's marine environment. Pesticides like DDT are thought to be widely present in marine life around Australia, but in very low concentrations away from urban and intensively farmed lands.(45)
In Queensland, organochlorines have been detected in very low concentrations on the Great Barrier Reef, and in higher concentrations in the Brisbane River. In New South Wales they were in very high levels near Sydney's sewage outfalls but have declined in these areas since the relocation of the outfalls offshore. In South Australia they were found to be widely present in fish sampled.(45)
Few surveys of PCBs have been undertaken in Australia. PCBs have been detected in offshore waters, with increasing levels towards the coast, but at lower levels than in equivalent Atlantic waters. PCBs have been detected in Queensland at low levels on the Great Barrier Reef and Brisbane River. In New South Wales they were high at the former Sydney ocean sewage outfalls but have declined since the relocation of the outfalls into deep water. In Port Phillip Bay levels remain high near Melbourne, but are declining in Corio Bay.(45)
Dioxins, waste products related to organochlorines, are recognised as significant problems in Australia although again, very few studies have ever been undertaken. In Sydney they have been found in fish and sediments in Homebush Bay, and in Melbourne near sewage outfalls.(45)
Because of their harmful environmental effects, many organochlorines are now banned or controlled. From the scattered surveys undertaken, levels appear to be declining near urban sewage outfalls since their uses have been regulated, but more systematic nationwide monitoring programs for organochlorines are needed to determine their status.(45)
Australia's beaches are increasingly littered with plastic bottles, plastic bags, tangled fishing lines, nets and other rubbish. Litter comes from 'tourist trash' left by beach-goers or is washed there. The latter comes from land litter washed from catchments and stormwater drains, from ships' garbage, from discarded fishing gear from anglers and fishing boats, and from remote sources far across the ocean. Urban beaches are worst affected, but even the most remote coastal and island beaches are not free from litter.(46)
There is some debate on who is ultimately responsible for beach litter, and what can be done to reduce it. Recent scientific surveys of beaches near Brisbane, Sydney and Melbourne found that most litter came from streets and garbage dumps and reached beaches via streams and drains. Blame was attributed to littering practices of the general public and poor waste management by local authorities. However, Greenpeace argues that the core of the problem really lies with our consumer society, and targets the packaging industry. (46)
The fishing industry is also a major contributor of ocean litter. Greenpeace found 20% of items came from recreational and commercial fishers. Systematic surveys by Tasmanian authorities in the isolated south-west found fishing litter constituted as much as 80& of all beach litter. (45,54)
Sources of beach litter (Source: Greenpeace Australia)
There is some debate on who is ultimately responsible for beach litter, and what can be done to reduce it. Recent scientific surveys of beaches near Brisbane, Sydney and Melbourne found that most litter came from streets and garbage dumps and reached beaches via streams and drains. Blame was attributed to littering practices of the general public and poor waste management by local authorities. However, Greenpeace argues that the core of the problem really lies with our consumer society, and targets the packaging industry.(46)
The fishing industry is also a major contributor of ocean litter. Greenpeace found 20% of items came from recreational and commercial fishers. Systematic surveys by Tasmanian authorities in the isolated south-west found fishing litter constituted as much as 80% of all beach litter.(46),(54)
Litter not only reduces the beauty of our beaches, but may also endanger marine life. Worldwide, many thousands of marine mammals, turtles and seabirds die each year from swallowing plastic bags and other objects, or get trapped in discarded fishing gear. Lost fishing nets and traps may also continue to catch fish (often referred to as 'ghost fishing'). In Australia the incidence of entanglement of fur seals in net fragments and other litter is alarmingly high. It is estimated that at any one time, around 500 seals in Tasmanian waters, and 45 seals at Victoria's Seal Rocks have 'collars' of plastic litter (Chapter 1).(18),(46),(54)
Greenpeace Australia first focused public attention on the problem of beach pollution through the 'Adopt-a-Beach' program between 1990 and 1992. Some 123 beaches were 'adopted' by local groups and are now regularly cleaned. Greenpeace documented the composition of over 340,000 pieces of litter to determine the sources.(46) The 'Clean up Australia' campaign has continued the focus on the beach litter problem.
There have been suggestions that the management of ocean and beach litter requires a coordinated national and international effort to reduce disposable packaging, an increase in the use of biodegradable packaging, a reduction in the littering practices of the public and fishermen, and improved waste management by local authorities. Stricter enforcement of MARPOL regulations on disposal of garbage from vessels is also required.(46)
Over 80% of the Australian population reside in large coastal cities with aging and inadequate sewage treatment systems. Sewage outfalls, septic seepage and stormwater may carry disease-causing micro-organisms into the sea, endangering bathers and seafood consumers with illnesses such as gastroenteritis, hepatitis, conjunctivitis, and upper-respiratory tract and wound infections.(47)
Little is known of these disease-causing micro-organisms in the marine environment and how long they stay alive in seawater. Viruses are particularly poorly understood because of difficulties in culturing them, but diseases such as polio and hepatitis 'A' and those caused by 'E' viruses have been associated with swimming. Viruses may bioaccumulate in filter-feeding bivalves near sewage outfalls and may cause viral food poisoning in seafood consumers.(47)
Bacteria are also a problem in bathing waters. In Australia they are causes of common wound infections, particularly in fish handlers, and of 'swimmer's ear'. Parasitic protozoans may also be transmitted in seawater.(47)
There is also some risk that diseases such as cholera may be introduced from overseas via ships' ballast waters. Introduced species of dinoflagellates (single-celled algae) produce toxic red tides and paralytic shellfish poisoning (p.64).(47)
Monitoring of disease-causing micro-organisms in the sea is difficult, as traditional bacteria indicators such as E. coli do not reliably reflect their presence. Standards for safe levels of viruses, parasitic protozoa and natural pathogens are lacking. Research is required to identify better indicators.(47)
The Surfrider Foundation of Australia investigated the state of the environment and surfing beaches during 1992-93 using questionnaires (47,101). Of the 439 beaches investigated:
While the SOS survey was not a scientific survey, it does provide a good indication of the environmental condition of Australia's surfing beaches.