Commercial use of coastal waters
This section focuses on the trends in three important commercial uses of coastal waters in Australia, and their coastal impacts: shipping (particularly the impacts of ballast water), commercial fishing, and the expansion of aquaculture. These three areas are significant in that they are not only associated with several adverse impacts on the coastal and marine environment, but also have high economic value for Australia. In the early 1990s, the Australian Marine Industries and Sciences Council estimated that shipping had a domestic value of $2212 million, fishing $360 million and aquaculture $ 118 million (1993 1994 values; updated figures from McKinnon 1993, quoted in Wescott 2000). The figures for fishing and aquaculture are likely to be underestimates, given that in the late 1990s the gross economic value of fisheries and aquaculture combined was estimated at $1.86 billion (Caton & McLoughlin 2000). What these figures indicate is that a reduction in such activities is unlikely, so there is a need to focus on management and mitigation of impact. This is, however, confounded by a lack of knowledge about the interactions between these activities and the coastal and marine environment.
Shipping and ballast
According to the International Maritime Organisation (IMO), 90% of goods on the international trade market are transported by ships (e.g. by bulk carriers, ore carriers, woodchip carriers and chemical tankers; Kerr 1994, IMO 1998). Shipping activities are particularly significant for Australia, which on an international scale, is the fifth largest user of shipping (ANZECC 1996a), with approximately 98% of goods transported in this manner (AQIS 1999). The coastal environmental impacts associated with shipping are numerous, and relate primarily to pollution and the transportation of marine species. For example, shipping activities are associated with:
• marine and coastal pollution by the generation and disposal of waste or 'marine debris', with approximately 6500 tonnes discharged into the marine environment from shipping activities each year in Australia (ANZECC 1996a; waste is predominantly characterised by plastics which can, for example, be ingested by birds). Monitoring of the total extent of the problem is difficult, and there is still a lack of information on this issue (ANZECC 1996a)
• marine and coastal pollution by oil or other spills due to accidents or faulty equipment. Oil spills were considered to be a major risk in Australian ports by a government inquiry into human impacts on the coastal environment (Commonwealth of Australia 1991)
• the transfer of marine species between regions on ships' hulls. Some of these become 'pests' because they foul the hulls, with the accumulation of seaweeds, barnacles and other species (EPA Vic 1999);
• the use of antifouling paints, many of which contain copper and tributyl tin (TBT), although this latter is being phased out (Rooyen 2000). TBT has been described as one of the most toxic pollutants to be released into the marine environment (Foale 1993). The paint prevents organisms from attaching to a ship's hull, to improve speed and fuel economy (EPA Vic 1999). The compounds in these paints, which accumulate in sediments, are highly toxic and have been linked to deaths of rainbow trout eggs, adverse impacts on commercial shellfish farms (e.g. oyster farms in New South Wales), and the development of male characteristics in female snails (otherwise known as 'imposex'; Commonwealth of Australia 1991, Foale 1993, Nias et al. 1993, Rooyen 2000)
• the transfer of marine species between regions by the release of ballast water. The issue of ballast water, which is used in this section as a case study of shipping impacts, is particularly significant and has received increasing attention since the 1970s (Kerr 1994, Paterson 1994,1MO 1998). Ballast can refer to both a solid or a liquid, and is used to provide ship stability and hull strength, and to ensure that the propellers remain submerged when a ship is empty of cargo. Since the 1880s, sea water rather than solid materials has been used as ballast because of the more efficient uptake and improved ship stability (IMO 1998). Sea water is siphoned and transferred into special holding bays at the start of a ship's journey (when it is empty of cargo), and discharged at the point where cargo is received. As a result, coastal waters (and marine organisms within this water) have been transported between regions around the world.
The introduction of exotic marine species into new regions via ballast water was recognised by the World Bank as 'one of the four major imminent threats' to international waters (Raaymakers 1998, p. 8), and in 1992 it was acknowledged as a 'major international concern' at the United Nations Conference on Environment and Development (IMO 1998). At an international level, approximately 10 billion tonnes of ballast water are transported between coastal regions each year, with the daily transfer of an estimated 3000 species of animals and other organisms (IMO 1998, AQIS 1999). Although only about 3% of these species will survive in a new location, the IMO noted that it takes only one introduced species to cause major impacts (IMO 1998). Not all introduced organisms will cause environmental problems; those that do have an impact are commonly termed 'pest' species (EPA Vic 1999).
In the Australian context, there are 72 international ports which are affected by the transport of ballast water from approximately 300 overseas
Figure 3.3 Australian ports affected by ballast
ports (McEnnulty et al. 2000, IMO 1998). Figure 3.3 provides an illustration of some of the Australian ports affected by ballast, with the majority of ships visiting ports in Western Australia, Queensland, and New South Wales. Most of the foreign ballast water entering Australian ports, which is estimated at 150 million tonnes each year, is introduced from Asian countries, particularly from Japan (T. Thwaites 1999). The source of coastal ballast in Southeast Asia is frequently polluted, there is limited treatment of sewage discharge, and it often contains aquaculture diseases (Hutchings 1992). Approximately 34 million tonnes of ballast water is also transported between Australian ports via domestic shipping around the Australian coast (Paterson 1994, IMO 1998), and this further serves to spread exotic species arriving from foreign ports.
The extent of the environmental and economic impacts of ballast water and exotic marine species in Australia are still not known, particularly given the lack of efficient monitoring and testing mechanisms for ballast water. There is also uncertainty about how many exotic species have actually been introduced. In the early 1990s, fourteen exotic species were known to have been introduced into Australian coastal waters (Paterson 1994), but in 1997 the Austral ian Quar antine and Inspection Service (AQIS) suggested that up to 170 species may have been introduced, with ballast water being the main mechanism of transport (IMO 1998; see also Raaymakers 1998). Later, AQIS (1999) and McEnnulty et al. (2000) estimated that at least 200 marine species had been introduced, primarily via ballast and shipping.
Given that surveys have been conducted at only 21 Australian ports, these figures are believed to be an underestimate (McEnnulty et al. 2000). However, only about 12 of the introduced species are considered to be in pest proportions (McEnnulty et al. 2000). A review of each of these species' impacts, trends and management is provided in McEnnulty et al. (2000). Examples of species that have been introduced into Australia include toxic dinoflagellates (e.g. in Tasmania, Port Phillip Bay, and Port Adelaide), European Shore Crab (e.g. in South Australia), sea slugs, Japanese Kelp (e.g. in Tasmania), North Pacific Seastar (e.g. in Tasmania and Victoria), mysid shrimp species, Asian Mussel (e.g. in Perth), polychaete worm species, Japanese Sea Bass, Yellow-fin Goby, and Striped Goby (e.g. in Sydney Harbour, Port Phillip Bay) (Hallegraeff & Bolch 1991, IMO 1998).
The possible environmental impacts associated with introduced marine pests in Australia and other parts of the world are numerous, and relate to threats to natural marine and coastal ecosystems, aquaculture industries and fishing, human health, and tourism (AQIS 1999). They can include, for example:
• disruption to natural populations and aquaculture, with introduced species occupying the niches of native species, competing for resources, or acting as new predators (EPA Vic 1999). In Tasmania, for example, Japanese Kelp has threatened the abalone industry and oyster and mussel farms (Paterson 1994, IMO 1998, T. Thwaites 1999)
• changes to nutrient pathways and physical environments (e.g. sedimentation by molluscs; EPA Vic 1999)
• spread of diseases, viruses and predators which affect fish species and aquaculture operations (EPA Vic 1999)
• spread of human diseases such as cholera (EPA Vic 1999)
• contamination of seafood which can result in paralytic shellfish poisoning. Contamination arises from toxic dinoflagellates or 'red tide' algal blooms, with impacts on human health, and declines in the diversity and/or abundance of fish and wildlife. Blooms can also have major economic impacts, such as the closure of marine farms and loss of income. For example, 15 shellfish farms were closed for six months in Tasmania due to these blooms, which were believed to have been transported from Japan (Hallegraeff & Bolch 1991, Hutchings 1992, Paterson 1994, EPA Vic 1999)
• reduced water quality from toxic algae blooms, and associated impacts on wildlife, human recreation and tourism (EPA Vic 1999).
Port Phillip Bay in Victoria is a particularly significant location in terms of marine species introduced by both ballast and hull fouling, and has been the subject of intensive research (EPA Vic 1999). Victoria receives the greatest number of ships from domestic or coastal shipping (Kerr 1994). According to McEnnulty et al. (2000), 165 introduced marine species have been identified solely in this location, of which eight are of major concern, the remainder having minimal impact (EPA Vic 1999). Those identified as pest species include for instance, the Northern Pacific Seastar, Asian Mussel (a fouling species that displaces native species and alters the physical environment via sedimentation), Japanese Kelp (threatens native algae, is a fouling organism in marine farms, and displaces natives species), and toxic dinoflagellate species (EPA Vic 1999). The Northern Pacific Seastar, which has a population of approximately 30 million in the Bay, was believed to have arrived in the Bay via domestic shipping from Tasmania (Paterson 1994, EPA Vic 1999). Despite attempts to manage the problem, the impacts associated with the seastar have been significant, with economic impacts on aquaculture, predation on bivalve molluscs, and the displacement of native species (Paterson 1994, EPA Vic 1999). They are also threatening the extinction of the Tasmanian Spotted Hand- fish (AQIS 1999).
The significance of this issue is gradually increasing in Australia and the rest of the world, particularly with the construction of new ports around the world, increases in international shipping movements and in ship sizes (and hence the amount of ballast), and faster travel times, which improves the chances of organisms surviving within the ballast (EPA Vic 1999). Once established, exotic species can proliferate rapidly and are expensive and difficult to control (compared to, for example, waste disposal or oil spills from shipping; 1MO 1998, AQIS 1999). For example, in 1999, $2 million was expended in Darwin to control an outbreak of the Black-striped Mussel that was threatening the multimillion dollar pearl industry (CSIRO 2000).
Australia has been at the forefront in developing voluntary guidelines for control of ballast, beginning in 1990, with an emphasis on prevention rather than clean-up (AQIS 1991, Raaymakers 1998). Guidelines were also prepared by the 1MO in 1993 at an international level, but these still have a long way to go in terms of implementation (Paterson 1994; AQIS 1999). The lack of standard compliance to these guidelines by many countries makes it even more difficult for Australia to manage the problem, as marine pests continue to be transported from countries where management guidelines are not applied.