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Edited by Leon P. Zann and David Sutton
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1996)
ISBN 0 642 23012 9
Marine Resources Branch
Department of Conservation and Natural Resources
Victoria has an area of 227 600 km2, a 2000 km coastline and a population of 3.7 million, giving it the highest population density and population-to-coastline ratio of all states and territories. The coast features two major embayments, Port Phillip Bay and Westernport Bay; the largest estuarine lakes system in the southern hemisphere, the Gippsland Lakes; the large shallow coastal lagoon system Corner Inlet/Nooramunga; and numerous smaller inlets and coastal streams.
By world standards, no major rivers drain to the Victorian coast; the largest is the Snowy River which has an average annual discharge of 1 790 000 megalitres. Of the State's total annual rainfall, 14% (21 000 000 ML) eventually flows to the sea (Vic. Govt 1982). The Great Dividing Range extends through north eastern to central Victoria, feeding major rivers northwards into the Murray River and southwards into the estuaries and coast of eastern Victoria.
The Victorian coast forms the northern boundary of Bass Strait, a shallow basin whose waters are influenced by the Tasman Sea and the East Australian current to the east, and the colder and more fertile subantarctic waters of the Southern Ocean to the south and west. While seasonal upwellings occur off western and eastern Victoria, the coastal and offshore waters are characterised by low nutrient concentrations. The water temperature range is from about 12oC to 18oC (Gibbs et al. 1986a).
The state's major industrial centres are concentrated around Port Phillip Bay's 264 km shoreline, and 70 % (3.2 million) of the State's population live in the expanding Bay-side cities of Melbourne and Geelong.
Port Phillip Bay's marine environment is of special interest and concern. The main body of the 1950 km2 Bay is a shallow basin, 24 m deep at its deepest point, with predominantly sand, silt and clay substrates. The average tidal exchange with Bass Strait, through the 3 km wide Rip, is about 1 km3 or 4% of the Bay's volume (Vic. Govt 1992c). The water temperature range is from about 10oC to 21oC.
Each year, the Bay's volume of 25 km3 receives 1.4 km3 of fresh water from the rivers which drain its 9790 km2 catchment, plus 1.2 km3 of rainwater, 0.2 km3 of treated sewage effluent and 40 000 tonnes of sediment from the Yarra River. Melbourne has about one third of Australia's manufacturing industry, disposing of 35 million tonnes of industrial wastes to sewers each year (Vic. Govt 1989a). The range of chemicals and materials manufactured and used, with potential for environmental damage, is increasing.
Coastal, bay and inlet waters support a variety of commercial activities: shipping, oil and natural gas fields, fishing and aquaculture. The infrastructure (e.g. harbours, wharves) and industrial complexes (e.g. refineries, chemical storages, superphosphate plants, aluminium smelters, fish processors) which support or depend upon these maritime activities are concentrated in particular areas on the fringes of these waters. The Port of Melbourne is Australia's largest general cargo port and, in 1987-88, handled merchandise worth over $23 billion, representing 27% of the total value of the country's international trade (Vic. Govt 1989a). Submarine pipelines bring oil and natural gas ashore from the Bass Strait oilfields to the Ninety Mile Beach and carry natural gas across the floor of Port Phillip Bay.
Several important recreational activities also focus on these coastal waters: recreational fishing, boating, sightseeing and related tourism - all of which are of great significance to coastal economies. Each year the Bay receives around 30 million recreational visits, including two million boat trips by Victoria's 65 000 recreational boats (Vic. Govt 1992c). Careful impact monitoring, assessment and planning are essential to ensure that the benefits derived from these recreational activities do not occur at the cost of the marine resources and environments on which they depend.
Figure 1: State map showing localities mentioned in the text
Coastal waters also play a vital role in receiving point and non point source discharges of domestic and industrial origins, requiring strict licensing and monitoring programs. Population growth, industrial development and consequent increases in the environmental pressures on coastal waters, require careful long-term planning and capital works programs. At the same time, there is a need to improve the quality of coastal discharges and to mitigate the effects of past pollution, adding to the complexity and costs of these tasks.
Most major problems arise from the concentration of population and industry around Victoria's two bays and the advanced state of development of the catchments to the bays and inlets. These problems take the form of discharges (both point source and diffuse) with their consequent inputs of nutrients, toxicants, silt and debris and their short-term (e.g. occasional algal blooms and bacterial contamination) and longer-term environmental impacts (e.g. seagrass loss and seafood contamination).
These problems are aggravated by physical disturbances to marine environments from shipping and related works, coastal development and fishing, and by the introduction of exotic species.
This section of the report focuses on chronically and acutely disturbed and contaminated waters, and the factors producing these impacts, in: Victoria's bays, inlets and estuaries; its Territorial waters (total area about 8 000 km2); and contiguous offshore waters. The emphasis is on factors that limit options for the future, by causing profound or enduring habitat changes. Locations mentioned in the text are shown in Figure 1.
Point source and diffuse inputs of nutrients continue to be the most pressing marine pollution issue in Victoria. Elevated nutrient levels can cause eutrophication and may increase the frequency of algal blooms, which may in turn cause major ecological problems, significant human health problems, and mortality and contamination of fishery and aquaculture stocks.
In Port Phillip Bay, while the annual nutrient load comes from a number of areas, the largest is the Werribee Treatment Complex where 65% of Melbourne's domestic sewage and 80% of its industrial wastes are treated through an extensive lagoon and land filtration system (Vic. Govt 1992c). Treated wastewater, containing nutrients and trace levels of toxicants are discharged into the western side of the Bay. The measurable impacts include more prolific growth of reduced numbers of seaweed species within 4 km of the outfalls, and seagrass declines resulting from enhanced epiphyte growth.
Phytoplankton biomass is generally higher in Port Phillip Bay than in the open waters of Bass Strait (Longmore et al. 1990; Gibbs et al. 1986a), and is often highest near major nutrient discharges in Hobsons Bay and off Werribee (Longmore 1992). Chlorophyll concentration varies over time within the Bay, and concentrations are generally higher in winter than in summer. This pattern is a response to nutrients carried in freshwater discharges, rather than a typical seasonal pattern related to temperature and/or light. Two analyses of chlorophyll data collected in the Bay during 1970-1986 indicated a three-fold increase off Werribee, a decrease in Corio Bay, and no trend in the centre of the Bay (Brown 1990; Saunders & Goudey 1990).
The commissioning of the South Eastern Purification Treatment Plant at Carrum, south-east of Melbourne, has helped to accelerate the rate of connection of unsewered properties. This has resulted in a reduction in the amount of nitrogen compounds entering the Bay by 700 tonnes annually; average bacterial levels at beaches have also decreased (Vic. Govt 1992c).
Nutrient enrichment from catchments is implicated in algal blooms which are occasionally severe in the Gippsland Lakes (see below). Recent anthropogenic sources supplement nutrients stored in sediments as a result of accession over thousands of years when the Lakes were terminal wetlands with limited and intermittent connection with the ocean.
In areas where discharges occur to the open waters of Bass Strait, the effects of nutrient addition appear limited to the vicinity of the discharge point. While these inputs may be of local significance, they are unlikely to cause nutrient enrichment of open ocean waters.
Trace levels of toxicants are released in treated sewage and other effluents which are discharged directly into bays and coastal waters. The EPA licences discharges of effluents.
During the last 20 years, almost all industrial discharges to the Bay and its tributaries have been diverted to the sewerage system. This, together with the EPA's licensing and monitoring of discharges has been very successful in reducing the inputs of many toxicants into Port Phillip Bay. Mean concentrations of heavy metals (particularly mercury and cadmium) in fish, shellfish, sediments and water in Port Phillip Bay have decreased since analyses started in the 1960s. For example, the mean mercury concentration in sand flathead flesh has fallen from 0.5 ppm (the food health standard) in 1975-1978 to 0.24 ppm in 1990 (Fabris et al. 1992b).
The presence of mercury in the edible flesh of many shark and dogfish species found off Victoria led to the banning of landing and possession for sale or consumption of all species other than school shark, gummy shark, southern and common sawshark, angel shark and elephant fish (Fishing(Shark Amendment) Regulations 1990).
Tributyltin (TBT) based antifouling paints are particularly potent toxicants which gained widespread usage during the 1980s. TBT is so toxic in the marine environment (producing imposex or shell thickening in gastropods) that the use of TBT-based paints on vessels smaller than 25 m long was banned in Victoria in 1989. However, the residual levels in the waters and sediments in Port Phillip Bay, and the TBT present on larger ships that ply the Bay mean that environmental impacts can be expected to continue for some time. Recent EPA work found low levels of TBT in water, sediments and biota; the biological effects appear to originate prior to the 1989 ban on TBT (Foale 1993).
PCBs and chlorinated pesticides such as DDT and dieldrin are persistent compounds which show high degrees of bio-accumulation in marine food chains. Both of these classes of organic toxicants are present (at levels below the maximum permitted concentrations) in flathead flesh from all sites sampled in Port Phillip Bay (Nicholson et al. 1991). Flathead livers showed elevated levels of heptachlor in the Geelong Arm and PCB in Corio Bay and the Geelong Arm. An unpublished 1990 report indicated that levels of PCDD and PCDF (toxic equivalents) in mussels and fish represented only a low human health risk, on the basis of international standards. Congener profiles show a different pattern on each side of the Bay, suggesting different processes affecting contamination; the Werribee Treatment Complex is important to the western side, and diffuse run-off to the eastern side of the Bay.
The lethal and sublethal effects of toxicants on marine species and communities present in Victoria's bays, inlets and coastal waters are completely unknown.
The run-off of stormwater, silt and debris from rural and suburban areas is a major pollution issue in Victorian bays and inlets. In Westernport Bay, accelerated sedimentation due to catchment erosion and stream channelisation is believed to have been a major factor contributing to the loss of about 70% of the seagrass beds during the 1980s. In this instance, there are thought to have been two harmful effects of silt: elevation and shallowing of the banks where seagrass grows, and increased turbidity and reduced light penetration necessary for bottom plant growth.
Plastic litter such as bags, package strapping material and fishing tackle maim and kill marine birds, mammals and fishes, as well as reducing the aesthetic values of Victoria's waters and shores. This litter originates from stormwater, beachgoers, fishers and shipping.
Over 300 drains enter Port Phillip Bay, carrying untreated stormwater, oils, grease, wastes and litter from roads and gutters, and part of the estimated 90 tonnes of dog faeces produced each day (Vic. Govt 1992c).
The increase in sediment inputs to rivers and streams due to human activities has been proposed for listing as a Potentially Threatening Process (under the Flora and Fauna Guarantee Act) which ultimately impacts on Victorian estuaries and inlets (DCNR 1991). The Victorian Flora and Fauna Guarantee provides both the power and active programs to protect threatened species and biological communities through a process that provides for full public participation.
Given the right combination of nutrients, temperature and salinity, the periodic blooming of marine algae is a natural phenomenon. The frequency and extent of such blooms appear to have increased as the result of increased nutrients and altered stream flows. These effects have been particularly marked in the Gippsland Lakes where severe blooms have caused major environmental damage over wide areas, reducing dissolved oxygen levels to the point of killing fish and other aquatic life. In turn these effects flow on to fish stocks and the commercial and recreational fisheries that depend upon them, as well as the associated tourism on which much of the regional economy depends.
Although infrequent in Port Phillip Bay, algal blooms have been observed to have severe direct and indirect impacts on fish and shellfish. For instance, in 1950, large numbers of fish and invertebrates died in Port Phillip Bay at the time of a bloom, believed to have been a `red tide' dinoflagellate species Gymnodinium mikimotoi (Callan et al. 1993).
Early in 1984, large numbers of flathead (two species), flounders (two species), spikey globefish and smaller numbers of several other species in the northern part of the Bay were recorded suffering from severe lesions on their heads, bodies and fins, and high external parasite loads (Gibbs et al. 1986b). In some cases, eyes were absent and fins completely eroded. Close examination showed the presence of extensive degeneration and deposits of iron compounds in the livers and, in some cases, the kidneys. Analyses of affected fish failed to find elevated levels of heavy metals or a range of organic toxins. Biotoxins resulting from a large phytoplankton bloom in the northern part of the Bay late in 1983 (following heavy drought-breaking rains), or polynuclear aromatic hydrocarbons were regarded as the most likely primary causes of this event.
In the spring of 1987, the bloom of a diatom Rhizosolenia chunii (normally present in the Bay in smaller numbers) resulted in a bitter taste in shellfish and, later, a high incidence of shellfish mortality (Parry et al. 1989). Harvesting and marketing by mussel farmers was suspended during most of the 1987-88 season, resulting in the loss of mussels worth $1 million. In August 1993, when the compilation of this report was completed, a bloom of R. chunii extended through most of the Geelong Arm affecting mussels off Clifton Springs and Portarlington.
Blooms of the toxic dinoflagellate Alexandrium catenella in January 1988, April 1991 and January 1992, resulted in the issuing of public health warnings against eating shellfish from the northern areas of the Bay. This exotic species, capable of causing paralytic shellfish poisoning (PSP), was first recorded from the Bay in 1986, but there has been no report of PSP resulting from shellfish consumption, despite high PSP toxin concentrations being recorded in mussels off Williamstown during the 1992 bloom (Callan et al. 1993). These blooms have been observed to follow heavy rainfalls in summer or autumn.
A widespread bloom of the diatom Nitzschia pseudodelicatissima, capable of producing domoic acid which causes amnesic shellfish poisoning (ASP), was first recorded from Port Phillip Bay in November 1991 (Callan et al. 1993). All mussel harvesting was suspended temporarily, although extensive analyses showed that the Bay strain was nontoxic. In August 1992, domoic acid levels detected in the viscera of scallops off Lakes Entrance caused a ban on the distribution and marketing of unprocessed scallops; N. pseudodelicatissima was not detected in the region.
Although Dinophysis acuminata, which can produce diarrhetic shellfish poisoning (DSP), has been identified as common in Port Phillip Bay, no shellfish from the Bay have been reported to have caused DSP (Callan et al. 1993).
During the winter of 1993, Alexandrium tamarense was reported from Port Phillip Bay for the first time. Levels were highest in the Geelong Arm in the vicinity of mussel farms where PSP toxins were detected in mussels.
The current ban on harvesting of shellfish for consumption from Hobsons Bay was introduced following frequent occurrences of high levels of Escherichia coli and other bacteria. In 1956, three cases of typhoid fever diagnosed in Melbourne, were attributed to consumption of shellfish from Hobsons Bay.
During the last five years, Port Phillip Bay shellfish aquaculture areas have been studied and ranked according to strict environmental standards, and are monitored to ensure that the marketed products are free of contamination by pathogens such as Escherichia coli and toxic algae (Arnott 1990).
The EPA monitors Port Phillip Bay waters during the summer swimming season to ensure that people engaging in swimming and other primary contact activities are not exposed to unacceptable risks from exposure to pathogens.
Monitoring of coastal sewage discharges is also required; for example, the Geelong and District Water Board regularly publishes the results of its monitoring of Escherichia coli on the coast either side of its offshore discharge at Black Rock, south of Geelong.
Heavy mortalities of native flat oysters Ostrea angasi were reported in Port Phillip Bay and some other Victorian waters in 1991. Investigations showed the presence of a haplosporidian parasite believed to be Bonamia sp. (Hine et al. in press).
Large volumes of seawater are used for industrial cooling purposes, resulting in significant though localised heating of receiving waters. The Newport D Power Station on Port Phillip Bay discharges the largest volume of heated effluent into Victoria's coastal waters. This effluent is also licensed to contain chlorine, ammonia and iron. In the early 1970s, predischarge studies concluded that the effluent may increase the likelihood and duration of algal blooms in Hobsons Bay. However, there has been no subsequent assessment of the actual impacts on blooms or other aspects of the ecology and fisheries resources in the area.
The Shell refinery in Corio Bay daily discharges 250 000 m3 of heated seawater which may contain traces of hydrocarbons. This effluent is also treated with chlorine to prevent settling of fouling organisms in the pipelines and heat exchanges.
The Alcoa aluminium smelter and Pivot Phosphate Cooperative are also licensed to discharge cooling water into Corio Bay.
The petroleum industry in and offshore from Victoria affects coastal and offshore marine environments in a number of ways.
Most exploration and all current oil production (and the associated environmental risks) off Victoria takes place outside Territorial waters. The eastern Bass Strait oilfield contains 12 platforms, a number of well heads and a system of connected pipelines which carry oil and natural gas to the shore at several points on the Ninety Mile Beach. Development of this field continues, accompanied by large quantities of cuttings and drilling muds. These platforms, well heads, pipelines and drilling wastes constitute a significant alteration to the marine environment. Exclusion zones around these fixtures encroach on several commercial fisheries and minor spillages and blowouts have occurred, but there is no evidence of contamination of fish arising from the drilling and extraction operations.
During the 1970s, the Danish seine fishery based at Lakes Entrance drew public attention to the incidence of marine debris resulting from the exploration, construction and operations of the oilfields. In 1983, their subsequent Supreme Court action and compensation highlighted the damage to fishing gear caused by this debris and resulted in a major clean-up of the area.
During 1992 and 1993, BHP Petroleum's survey and exploration program in the Otway Basin, off western Victoria, resulted in a number of exploratory drilling operations and raised well heads. This raised a number of concerns about physical disturbances to the bottom, impacts of drilling muds, possibilities of blowouts and spills, with consequent damage to marine communities. Particular concerns were focused on the rock lobster fishery, calving whales and marine birds. Prior to this, acoustic survey work had attracted opposition by conservation groups and commercial fishers concerned about the possible impacts on marine ecosystems and resources, particularly whales and fish populations.
Spillages associated with loading and unloading crude oil and petroleum products at the refineries in Port Phillip Bay, Corio Bay and Westernport Bay result in localised contamination by both hydrocarbons and dispersants. In Corio Bay, for instance, fish tainted with hydrocarbons are reported periodically by anglers and fish consumers. Analyses of petroleum hydrocarbons in the flesh of sand flathead from 10 sites in Port Phillip Bay showed the highest level (46 ppm) 8 km east of Corio Bay; the highest level in flathead livers (641 ppm) was from Corio Bay (Nicholson et al. 1991). Although there is no maximum permitted concentration for petroleum hydrocarbons, taint in fish has been detected at 10 ppm (Connell & Miller 1981). Hydrocarbons of pyrogenic origin enter Port Phillip Bay through the atmosphere and stormwater run-off and from vessels operating on the Bay (Vic. Govt 1992c).
Minor oil spills are regular events in Victorian bays. In Port Phillip Bay, spills of less than five litres occur almost daily while spills greater than 100 litres occur less than once per month (Vic. Govt 1992c). Larger spills occur offshore occasionally, affecting penguins and other marine life. In 1988, a spill of 180 l in Portland Harbour resulted in the deaths of seabirds and the issuing of a warning to local fishers about the possible contamination of fish (LCC 1993).
Seepage of petroleum products from storage sites close to Port Phillip Bay causes localised contamination. For example, in 1993 it was discovered that a Bayside petrol station had for years been losing petrol through a broken pipe, into the soil 50 m from the shore at Hampton. The possible impacts of seepage from larger current and past storage areas in Hobsons Bay, Corio Bay and Westernport Bay are unknown. During the 1980s, a much larger and very expensive clean-up was required at a former oil storage site, adjacent to Hobsons Bay, before a major residential development could proceed.
Oil pollution events in Victorian territorial waters are dealt with under the Victorian supplement (or State Plan) to the National Plan for combating such pollution at sea. The Port of Melbourne Authority is responsible for coordinating State and Commonwealth agencies and industry bodies in these operations. The occasional incidence of ships running aground in the lower end of Port Phillip Bay, in clear conditions and well marked channels, are a reminder of the potential for major oil spills in coastal waters and embayments.
In Victoria, the public ownership of nearly all coastal foreshores has helped to buffer the marine environmental impacts of nearby land use and has also limited development on coastal land. This affect is greatest where the public reserve is at least several hundred metres wide.
Some coastal developments have become widely accepted, particularly where they are perceived to provide useful and accessible public amenities, for example public boating and lifesaving club facilities. Others are perceived to enhance the marine environment by adding to the diversity of habitats for shellfish (e.g. seawalls and breakwaters), fish (e.g. artificial reefs, shellfish farms and piers), penguins (e.g. St Kilda harbour) and seals (e.g. channel markers and Bass Strait oil rig buoys).
Many coastal developments, while providing a number of benefits, entail significant ongoing environmental costs to the community. For example, the establishment of Portland Harbour has altered coastal processes in the area, changing the reef and seagrass habitats and eroding public and private land to the north. Major protective works have been necessary to prevent further property losses, but nothing can be done to mitigate the marine habitat impacts. Furthermore, dredging and dumping of sand from the harbour is a continuing, costly and controversial issue that causes further disturbance to marine habitats.
In the Gippsland Lakes, the proliferation of public and private jetties, marinas and related boating facilities has grossly altered the nature of the shoreline and inshore habitats and restricted general access to those areas.
Still other coastal developments are less well accepted because community perception of their benefits is outweighed by concern over their potential for adverse marine environmental impacts. Examples include coastal sewage treatment plants and discharges, and oil terminals and refineries. In August 1991, a massive fire at the bulk liquid chemicals storage facility at Coode Island drew public attention to the hazards associated with the increasing usage and resultant maritime transport, handling and storage of a wide range of hazardous chemicals at shore-based facilities. In this case the solution chosen - a proposal to relocate the storage facility from one Bayside site to another more remote one west of Pt Wilson (either on land or on a man-made island) - has also aroused wide public concern.
Exotic species may be introduced into Victorian waters through the discharge of ballast waters, from growths on the hulls of ships or - possibly - through translocations of fish and shellfish for aquaculture and fisheries purposes (DCNR 1993). That most introduced species have been reported from major port areas like Hobsons Bay and Corio Bay, suggests that shipping is the main source.
Millions of tonnes of ballast water from foreign ports have been discharged annually into Victorian ports. In 1986-87, about two million tonnes were discharged in the ports of Melbourne and Geelong, and a further 0.5 million tonnes in Westernport Bay (NREC 1991). Australian Quarantine Inspection Service guidelines for ballast water movement and discharge, introduced in 1990, are intended to reduce the risk of further introductions of exotic species from ballast water.
Already, a number of exotic species have become established in Victorian waters. Little is known about the timing of the introductions, their range and rate of spread or their ecological impacts.
The following exotic macroflora and fauna species have been identified in Victoria:
|blue spot goby||Pseudogobius olorum|
|striped goby||Tridentiger trigonocephalus|
|yellow-fin goby||Acanthogobius flavimanus|
|Pacific oyster||Crassostrea gigas|
|Asian mussel||Musculista senhousia|
Of these species, only the Pacific oyster was deliberately introduced into Victorian waters, decades ago.
The colonial polychaete Sabella spallanzanii has recently been reported to be the visually dominant organism in the Geelong Arm (Carey & Watson 1992).
The alga Polysiphonia brodiaei, first recorded around ports and subsequently found at a number of more exposed locations, may also be an exotic.
Rice grass Spartina townsendii was deliberately introduced and planted for land reclamation and bank stabilisation in inlets and estuaries, and has significantly altered the nature and ecology of areas where it is now established, such as Anderson Inlet.
The toxic phytoplankton species Alexandrium catenella, capable of causing PSP, has been identified in Port Phillip Bay since 1986, including major blooms in 1988, 1991 and 1992. There is a slight possibility that this species may be endemic to Australian water, but only discovered by recent monitoring programs.
Some additional species have recently been introduced into Tasmanian waters from Japan, and may reach Victoria. These include the kelp Undaria pinnatifida, the toxic alga Gymnodinium catenatum and the predatory starfish Asterias amurensis. All three species have the potential to cause ecologically and economically important changes and it is difficult to see how they can be kept out of Victorian waters in the long-term.
Recognising their potential ecological significance, the introduction of exotic species into Victorian marine waters has been formally listed as a Potentially Threatening Process (DCNR 1993).
Marine habitat modifications have occurred in Victoria as the result of a variety of human activities: coastal development and reclamation; land clearance, agriculture, forestry and water management in the catchments; coastal discharges; disposal of junk; port maintenance and development; fishing; and the introduction of exotic species. These result in effects such as: shallowing and infilling; seagrass loss; increased turbidity; altered temperature and salinity; burying or removal of benthos; eutrophication and chemical contamination.
While some of these, such as reclamations for the development of recreational boating facilities or container terminals, clearly destroy marine habitats entirely, others such as the establishment of marinas may replace a natural habitat with highly modified habitats which may support marine communities. In the latter example, leaching and discharges of hydrocarbons, antifouling paints and other pollutants must be controlled if these communities are to remain healthy.
Until about 20 years ago, Port Phillip Bay and coastal waters were frequently made the final resting place for unwanted ships, munitions and other items. The `ships graveyard' immediately west of Pt Nepean features a number of First World War submarines. This form of disposal of unwanted hardware is no longer practised.
During the 1970s, artificial reefs were established at several sites in Port Phillip Bay and off Phillip Island. Other reefs have since been built off Portland and at the southern end of the Bay. However, there has been no attempt to monitor the ecological and fishery impacts of any of these reefs, hence their real benefit is uncertain.
The blasting of sand barriers at the mouths of inlets such as the Tamboon, Sydenham and Curdies Inlets is undertaken primarily to protect private property and land use from high water levels. However, it clearly represents a significant interference with natural coastal processes and the condition of aquatic environments in these inlets.
Human activities that alter rivers and streams have substantial effects on estuaries and inlets. In Victoria, this has been recognised formally in the listing of alteration to flow regimes (resulting mainly from diversions and storages) as a Potentially Threatening Process under the Flora and Fauna Guarantee Act (DCNR 1992a).
The establishment of mussel farms in Port Phillip Bay has added a new three dimensional form of marine habitat characterised by diverse and abundant assemblages of fish species targeted by commercial and recreational fishers.
A number of marine environmental issues have serious public health implications: phytoplankton blooms, toxicants and bacteria.
Human health may be threatened by primary contact with contaminated water (e.g. swimming) or by eating contaminated seafood. Because of the potential seriousness of these risks, programs are in place to monitor coastal discharges, toxicant levels in fish and shellfish, and the presence of potentially toxic plankton species, particularly in commercial shellfish and aquaculture production areas.
The harvesting of shellfish for human consumption is prohibited in Hobsons and Corio Bays and off the Werribee Treatment Complex, and public health messages and signs warn against collecting shellfish near a number of drains around Port Phillip Bay. However, shellfish from most areas of the Bay pose no human health problems.
In the latter part of 1992 and early 1993, the collapse of large sewerage pipes in Melbourne lead to the discharge of large volumes of raw sewage via the Maribyrnong River into Port Phillip Bay. This resulted in public health warnings about the private collection and consumption of fish and shellfish, and in the suspension of commercial fishing in the northern waters of the Bay. The high levels of bacterial contamination associated with this event also restricted swimming and related activities on northern and eastern beaches.
This was a particularly dramatic example of the raw sewage discharges which occur quite regularly when Melbourne's sewerage system is unable to cope with breakdowns or overloads.
It must be emphasised that conditions posing risks to human health are extremely limited in their geographic and temporal occurrence in Victorian waters.
Several marine and/or estuarine areas containing features of high conservation value have been proclaimed as Marine Parks or Marine Reserves in recent years.
The Harold Holt Marine Reserves (Victoria's first marine protected areas, proclaimed in 1979), comprise five areas at the southern end of Port Phillip Bay: Point Nepean, Point Lonsdale, Popes Eye, Mud Island and Swan Bay. A further reservation, Point Cook Marine Reserve on the western shoreline of Port Phillip Bay, was proclaimed in 1982.
Subsequently, the Wilsons Promontory Marine Park and Reserve, and the Corner Inlet, Nooramunga and Shallow Inlet Marine Parks in South Gippsland were proclaimed in 1986. The Bunurong Marine Park, near Inverloch, is Victoria's most recent reservation, being proclaimed in 1992.
These areas have been reserved to protect their special conservation, recreation, education and scientific values. Only the Wilsons Promontory and Bunurong marine communities were surveyed in any detail prior to their proclamation (Wilson et al. 1990). Otherwise, there has been a distinct lack of detailed research on the communities in marine protected areas and of effective programs to monitor the response of communities in recently proclaimed areas.
The 1987 State Conservation Strategy and the 1988 Coastal Policy for Victoria outlined proposals for a systematic ecological survey of Victoria's marine ecosystems: to provide an inventory of species, communities and habitats; to determine their conservation status; and to provide the basis for protecting representative examples of ecosystems of special significance. This work has not proceeded and there is no systematic basis for assessing conservation values or the need for further reservations or other special protective measures. This situation has also made it extremely difficult to judge the potential impact of major developments and of discharges.
Victorians want to make use of their common property bays, inlets and coastal marine waters in a variety of ways, including:
Many of these uses are, or are perceived to be, incompatible with each other if applied to the same area or to the same stock of natural resources. Such situations usually lead to competition and conflict of interest between different user groups. Types of conflict which commonly occur include:
Three recent reviews or planning processes emphasise the complexity and intensity of natural resource management issues when it comes to marine and estuarine areas. These were the proclamation of the South Gippsland Marine Parks, the development of the Port Phillip Bay Management Plan, and the Parliamentary Natural Resources and Environment Committee's (NREC) review of Victoria's bay and inlet commercial and recreational fisheries.
In the first case, the special conservation values of the shallow mangrove-fringed waters of Corner Inlet, Nooramunga and Shallow Inlet and the granite reefs at Wilsons Promontory, were recognised and protected by proclamations under the Crown Lands Reserves Act. The proclamations were strongly opposed by some commercial and recreational fishing interests concerned by the possible loss of access to fishing opportunities. The proposal to phase out commercial abalone and rock lobster fishing in the Wilsons Promontory Marine Reserve in particular, was strongly opposed and led to a successful Supreme Court challenge. Research conducted by the Department of Conservation and Natural Resources established the suitability of waters in the Corner Inlet and Nooramunga Marine Parks for commercial aquaculture of native flat oysters. However, development of the aquaculture potential of the area has not progressed, largely because of some concerns over the compatibility of commercial aquaculture with the protection objectives of the Corner Inlet and Nooramunga Marine Parks.
The Port Phillip Bay Management Plan (Vic. Govt 1992a) highlights the difficulty of avoiding conflicts between activities and values that are basically incompatible. In this instance, the protection of marine habitats in the Bay for effective marine conservation and to maintain fish stocks for commercial and recreational fishing and aquaculture, is at odds with plans for significant further development around the Bay, including expanding shipping and port facilities.
In the late 1980s, a small increase in commercial gill netting for snapper in Port Phillip Bay lead to a successful campaign by some anglers and commercial longline fishers to have all target gill netting for snapper banned during the October-December period each year. Within 12 months, bag limits were also introduced for recreational snapper catches. In neither instance was the decision based on an assessment that the snapper stocks required greater levels of protection, or that the measures taken would achieve increased protection if such were needed.
Responses to the NREC's enquiry emphasised the ongoing conflict over fisheries resource allocation between commercial and recreational fishers in Victoria's bays and inlets. Predictably, strong arguments were put by both groups. Tourism and local government submissions generally favoured giving preference to recreational fishing, particularly in the smaller inlets, because of its increasing importance to coastal economies.
Living marine resource conservation and environment protection has been characterised by fragmentation of policy development, administration, information-gathering programs and recognition of the needs of client groups. At the heart of this issue has been the absence of a clear overriding aquatic conservation policy framework (ARSFC 1992).
This means that, while some sectors of government agencies and the community are now more aware than ever of the fundamental importance of protecting marine habitat to assure the future of marine resources and the resulting community benefits, the separation of responsibilities for fisheries management, environment protection, ecological diversity, water resource management and catchment/coastal management, inevitably leads to inconsistency or incompatibility of agency objectives and programs. Attempts to have sister agencies develop a team approach to issues of mutual concern often failed because of the absence of an overall guiding policy framework, the basic incompatibility of their separate objectives and the incompleteness of their combined objectives and responsibilities.
The need for an integrated approach in the conservation of marine (and other) natural resources in Victoria has been recognised in bringing these agencies together in one ministry, and commencing a thorough marine and coastal planning process (see below).
Many human activities in and around Victoria's coastal waters have the potential to modify aquatic habitats and fish stocks and are therefore, in the long-term, incompatible with the maintenance of such natural resources. The Government is therefore faced with two policy options which are mutually exclusive in any one area (ARSFC 1992). These are to:
(a) give priority to development activities at the expense of degraded marine habitats and resources; or
(b) protect marine habitats and conserve fish stocks at the expense of restricting further development activities.
Failure to recognise and to make a clear choice between these options, or failure to implement option (b) if chosen, is effectively a decision against the maintenance of habitats and living resources. Irrespective of the choice made, continued population growth close to Victoria's public waters will inevitably cause further losses or degradation of marine habitat and fish resources.
The Victorian Government's most recent response to this issue has been the establishment of the Marine and Coastal Study being conducted by the Land Conservation Council. The scope of this strategic marine planning effort extends to Victorian coastal public land and waters, including bays, inlets and estuaries. The LCC is scheduled to make its recommendations to the Minister for Planning and Development in December 1994.
A major contributor to this dilemma is the lack of credible information to demonstrate the likely impacts of proposed developments. In the absence of this information and in the face of demonstrable economic benefits, development usually proceeds.
The cumulative effects of years of commercial and recreational fishing are demonstrable for many fish and shellfish stocks in Victorian waters. However, the judgement of where the impacts of fishing on stocks reach the point of being described as 'overfishing' can be rather arbitrary and ill-defined.
Evidence of overfishing of fish stocks in Victorian waters is available for at least two important fisheries. The clearest evidence is for school sharks Galeorhinus australis and gummy sharks Mustelus antarcticus in Victorian, Bass Strait and other southern Australian waters. Current estimates suggest that the biomass of school sharks has been reduced to about 20% of the virgin biomass, and the biomass of gummy sharks has been reduced to 40-50 % of the virgin biomass (T.I. Walker DCNR, unpublished). While limited entry, tough gear restrictions and licence consolidations with gear forfeits have significantly reduced fishing capacity, further substantial reductions in catch must be achieved to enable the decline to be halted and the school shark stocks to be rehabilitated. State and Commonwealth agencies are working with industry to develop a long-term management strategy and a structural adjustment process for the fishery.
In the case of rock lobster (Jasus edwardsii) stocks, the mean catch rate of the commercial fishery is taken to be an index of stock abundance; this rate is expressed as kg/potlift or kilograms of rock lobster taken for sale each time a pot is lifted. Since 1950, the mean catch rate has declined from about 2.5 to 0.5 kg/potlift and is still falling. This has occurred despite technological advances that enable more precise navigation and position fixing and better discrimination of bottom features, all of which make rock lobster stocks easier to target.
The public perception that scallop stocks, particularly in Port Phillip bay, have been severely overfished, is really a result of the extreme variability of annual recruitment to scallop stocks and the fact that the Bay fishery is largely based on 1+ year old scallops. This means that the potentially harvestable stock each year can vary from 20 million to 2700 million in the space of two years, as happened between 1990 and 1992.
Although not based on any quantitative assessments or surveys, the Shellfish Protection Regulations (1983) were introduced in recognition of a general view that uncontrolled gathering of molluscs and crustaceans (for food and fishing bait) from some intertidal and shallow subtidal shores in the bays and the central Victorian coast have an unacceptable impact on marine communities and habitats. Impacts on intertidal molluscs, resulting from noncompliance with these regulations, has been demonstrated near Williamstown (Keough & Quinn 1991).
The earliest major commercial fishing requiring legislative control in Victoria was dredging and raking for native oysters (Crassostrea angasi) in several bays and inlets. The fishery in Westernport Bay supported 21 boats at one stage and the fishery at Port Albert shipped oysters to Melbourne as early as 1843 (K.J. Street DCNR, unpublished). As a fishery resource, these stocks were extinguished by the 1920s. However, it remains unclear whether stocks crashed because of overfishing, impacts of dredging or habitat changes caused by clearance in catchments of those bays and inlets.
Overexploitation of whales and seals during the early settlement of Victoria caused the elimination of the New Zealand fur seal, Australian sea lion and the Southern Right whale from the region and the elimination of Australian fur seal colonies from a number of Bass Strait islands. The numbers of sightings of Southern Right whales in western Bass Strait is increasing, suggesting that, while the more accessible sub-population that was hunted off Tasmania was extinguished, the subpopulation whose range extended into the Great Australian Bight survived and is recovering (Warneke 1989).
Between 1963 when the scallop fishery commenced in Port Phillip Bay, and 1968 when the fishery collapsed, catch rates progressively decreased as the virgin stock was caught. Subsequently, the fishery has experienced wide variations in annual catches, reflecting the variability of annual recruitment. Public concern over perceived ecological damage from the use of scallop dredges increased during the 1980s. In 1984, this lead to the banning on commercial scallop and mussel fishing in depths less than 10 m in Port Phillip Bay (5 m in the Geelong Arm) to protect seagrass and shallow reefs and shellfish beds.
Brief studies carried out in 1984 (Anon. 1981) showed no impacts on benthos or mobilisation of toxicants in sediments, but indicated that scallop fishing damaged seagrass beds in shallow waters. As a result, scallop fishing was prohibited in the shallows where seagrass occurs.
In 1991, following a resurgence of scallop fishing in the Bay, public concern prompted the commencement of the first detailed studies of the short, medium and long-term impacts of scallop fishing on benthic communities, associated fishes and sediment disturbance (Parry & Currie 1992). These studies continued into 1993, with early results indicating that scallop fishing causes changes to animal communities in the sediments. The extent of these changes and their persistence are still under investigation.
For decades, commercial mussel dredging in Port Phillip Bay produced most of the mussels (Mytilus galloprovincialis) sold in Australia, with an annual production of up to 1600 tonnes. However, in 1986 the Victorian Government closed this fishery because of concerns about its ecological impacts and because the emerging mussel aquaculture industry provided an alternative source of mussels.
The possibility that poor breeding seasons of little penguins (Eudyptula minor) may be related to the availability of pilchards (Sardinops neopilchardus) and anchovies (Engraulis australis) was first raised during the 1970s. Commercial catches of pilchards in Port Phillip Bay increased from about 200 tonnes per annum in the late 1970s to a peak of about 1400 tonnes in 1988-89 (DCNR, unpublished data). In some years during this period, exceptionally poor penguin breeding success and high juvenile and adult mortality were observed among the Phillip Island birds, many of which overwinter in the Bay.
Community concern about the ecological impacts of large annual catches of pilchards, anchovies and related species was recognised as a major issue in a Parliamentary review of commercial and recreational fisheries in bays and inlets (NREC 1991). Stock assessments of Port Phillip Bay pilchard and anchovy stocks and studies of the relationship between these stocks with those in nearby open waters were identified as important areas for future research (Vic. Govt 1992b).
The same review identified the possible ecological impacts of commercial haul seine netting in Corner Inlet, Westernport Bay and Port Phillip Bay as an issue of great concern to many anglers, commercial fishers and conservation groups (NREC 1991). Aspects of this method that were of particular concern were the impacts on seagrass, nontarget species and undersized target species.
Extremely little is known of the structure and diversity of marine communities or the conservation of marine flora and fauna on the open coast. This deficiency severely impedes considered decision making where marine conservation issues are important (Vic. Govt 1989a). Proper consideration of ecological issues usually requires large-scale investigations which may take several years.
A study of possible future pulp and paper mill effluent discharge sites off East Gippsland, between Lakes Entrance and Bemm River, revealed benthic communities of extraordinary diversity on substrates of coarse and medium sands and low-relief limestone reefs (Parry et al. 1990). Most notable was the infauna: a total of 353 species were identified from only four sites at each of which three 0.1 m2 grab samples were taken. Further sampling in the area (L. Avery & N. Coleman DCNR unpublished data) has expanded the list of species known to occur to over 750. This diversity is considerably higher than has been found in similar surveys elsewhere in the world. Further consideration of a new pulp and paper mill will require additional marine investigations.
Detailed studies, over many years, of a shallow reef community close to San Remo identified a species-rich community, characterised by an unusually large number of species of opisthobranchs and bryozoans, including several species currently not known from elsewhere (DCNR 1992b). The uniqueness of this community resulted in its listing under Victoria's Flora and Fauna Guarantee Act, and caused the relocation of a marina development proposal. More importantly, an Action Statement (DCNR 1992b) specified the monitoring, survey and works control actions to be implemented to protect this community. To the extent that the special significance of this area may be partly attributable to the intensity of the studies there, the lack of baseline studies of the Victorian coast is again emphasised.
Although the marine communities of Port Phillip Bay have been studied several times over the years (Anon. 1973, 1971, 1966), there has been insufficient intensity and consistency between these studies to identify changes in the conservation status of these communities.
Baseline studies of Westernport Bay biota were carried out in 1973 and 1974. The highest number of crustacean species found during the survey of the benthic fauna (Coleman et al. 1978) led to the description of Westernport Bay as `species packed' (Barnard & Drummond 1978). Another unusual feature of the benthic fauna was the relatively high abundance of the trigonid bivalve Neotrigonia margaritacea (Coleman & Cuff 1980). Bivalves of the family Trigoniidae occur as fossils throughout the world, but living species occur only in Australia. The Westernport Bay study is the only one to have provided quantitative data on the distribution of Neotrigonia and shown it to be a dominant member of the fauna.
Despite the significant ecological changes that are likely to have resulted from the extensive loss of seagrass in Westernport Bay, and despite the potential effects of proposed industrial development, there have been no follow-up studies or attempts to assess the current ecological status of benthic the Bay since the baseline studies noted above.
Dredging of shipping channels and port facilities, and the subsequent dumping of spoil, are important environmental issues, particularly in Port Phillip Bay and Westernport Bay. In the past, tens of millions of tonnes of sediments, some from contaminated port areas, have been dredged and dumped in hundreds of operations in Port Phillip Bay. Because of exemptions from, or limited application of, the requirements of the Environmental Effects Act, it is still not possible to describe the short-, medium- or long-term ecological impacts of this form of dredging and spoil disposal.
For many years, most of the 40 000 m3 per annum of material dredged from the lower Yarra River and dumped in Port Phillip Bay was silt which originated in the Yarra catchment. This dredging work was suspended in 1989, pending an evaluation of future desilting needs.
In 1992, a major Port of Geelong Authority channel dredging program was scheduled to dump 14 million m3 of spoil in the Geelong Arm. That longstanding spoil dumping grounds in the area could not accommodate this material indicates that previous dumping has significantly altered the hydrographic (and presumably the ecological) character of these grounds. During the previous 140 years, about 20 million m3 of spoil has been dredged and dumped in the Corio Bay/Geelong Arm area.
Dredging programs of different magnitudes and frequencies are conducted elsewhere in Port Phillip Bay, in other bays and inlets and coastal waters - all with little knowledge of their ecological impacts. Most are small scale operations or are repeated at intervals of several years. However, at Lakes Entrance, 500 000 tonnes of sand per annum are dredged from the inshore sandbar to maintain safe access to port. At the other end of the scale, the disposal of even small volumes of spoil can cause localised concern.
This issue has concerned fishers for decades. Early this century, commercial and recreational fishers banded together in a united campaign opposed to the dumping of dredged silt in Port Phillip Bay (K.J. Street DCNR, unpublished).
Sand removal from the shoreline occurs to a limited extent, with localised effects. At Sand Island, Queenscliff, sand is removed for purposes which include beach renourishment in Geelong and on the Bellarine Peninsula. Much of the Queenscliff coastline, including Sand Island itself, is an artifact resulting from continual dredging of the entrance to the boat harbour, and associated seawalls. The overall effects of these works include the progressive accretion to the shoreline and shallowing of waters immediately south of the harbour, accretion to Sand Island, and erosion of the shore of Swan Island further north.
In the past decade, approaches for permits to mine sands off Point Cook, in Port Phillip Bay, and to explore Corner Inlet for minerals such as tin and zircon have not progressed to the Environmental Effects Statement stage.
The practice of beach renourishment by the transfer of sand dredged from offshore is largely confined to Port Phillip Bay, although some work has also been done in the Gippsland Lakes. While the primary purpose is usually the improvement or restoration of swimming beaches, some projects are primarily intended to prevent coastal erosion. During the 1970s and 1980s, hundreds of thousands of cubic metres of sand were dredged offshore, dumped close to shore, then suction-pumped ashore to beaches at Mentone and Parkdale. Since 1975, a total of 20 km of beaches have been enhanced around the Bay. In recent years, the high costs and reduced funding available for these works have reduced their frequency and extent. Their ecological impacts on the borrow areas, inshore dumping areas and the nearshore habitats have not been assessed.
Discharges of sewage and other wastes (illegally or by accident), ballast water, spillages (while loading and unloading) and contamination from hull maintenance may have significant localised effects in areas such as Corio Bay, Hobsons Bay, Crib Point and Portland Harbour.
Under Victoria's Environment Protection Act 1970, three State Environment Protection Policies (SEPPs) have been proclaimed to protect coastal waters; the 1975 SEPP Waters of Port Phillip Bay, the 1979 SEPP Waters of Westernport and the 1988 SEPP Waters of Victoria. These SEPPs set out the basis for maintaining environmental quality sufficient to protect existing and anticipated beneficial uses of these waters and their natural living resources (EPA 1991). A guide for the future use and protection of the coastline, including nearshore waters, has been produced (Vic. Govt 1988), and the environment, history, commercial and recreational uses, and a management and planning framework has been developed for Port Phillip Bay (Vic. Govt 1990). In addition, during the last decade, there has been a great deal achieved in the area of management plan development for specific coastal areas and inlets, such as the Gippsland Lakes Management Plan.
These policies and plans, together with the legislation relating to marine and coastal environment protection, conservation and development, form the current framework for dealing with marine environment protection and management in Victoria.
A recent environmental health report for the Bay (Vic. Govt 1992c), rated the condition of the majority of the 1 km coastal margin as excellent and the offshore 90% of the Bay as good, measured in terms of compliance with environmental standards. Hobsons Bay, Corio Bay and the Werribee segment (immediately adjacent to the Werribee Treatment Complex) rated fair to poor in relation to shellfish quality, nutrients, toxicants and, in the case of the two bays, the general state of marine habitats.
It is estimated that 1000 tonnes of nitrogen and 30 tonnes of lead (as well as pyrogenic hydrocarbons) from motor vehicles enter the Bay, via the atmosphere, each year. These and other contaminants enter via dust fallout and rainfall (Vic. Govt 1992c).
Recent studies have shown that nutrient concentrations are highest in Hobsons Bay, off the Werribee coast and in Corio Bay. Phytoplankton growth has increased near Altona, in Hobsons Bay and on the east coast of the Bay (Vic. Govt 1992c). During 1987-89, bottom waters in the centre of the Bay had high dissolved oxygen concentrations for 76% of the time. However, during spring and summer, oxygen levels were lower than the current environmental objective (90% saturation) 40% of the time. The lowest levels recorded approached the level at which some organisms may experience sublethal stresses (Mickelson 1990).
Sediment oxygen demand is low in comparison with values published for other coastal waters around the world, supporting the idea that Port Phillip Bay is relatively unproductive (Newell 1990).
The concentrations of some toxicants are decreasing in sediments and fish tissues, for instance cadmium, lead and PCB in Corio Bay, and mercury in fish Bay-wide (Nicholson 1992). In 1990, the mean concentrations of mercury in the axial muscle of sand flathead (Platycephalus bassensis) from 37 sites in Port Phillip Bay were less than half those reported for this species during 1975-78 (Fabris et al. 1992b). The 1990 study showed that concentrations were significantly higher in flathead sampled from deeper waters than in those from shallow waters, suggesting that heavy metal concentrations may be greater in the fine clay sediments present in the deeper central region of the Bay than in the coarser silts and sands in shallower regions.
Petroleum hydrocarbons and organochlorines have been detected in flathead and sediments collected throughout the Bay, with particularly high levels in the Geelong Arm and Corio Bay (Nicholson et al. 1991). Concentrations have not changed much since the 1970s (Vic. Govt 1992c).
The concentrations of metals in mussels in Port Phillip Bay have not changed significantly in the last decade. Mean cadmium levels in mussels in Corio Bay have fallen from the high levels recorded in the 1970s to below the maximum permissible concentrations, although high levels persist at some locations (Nicholson et al. 1992d).
Three years after the 1989 ban on the use of TBT on boats less than 25 m long, all indicators pointed to low levels in the Bay (Foale 1993). The highest severities of imposex (a reproductive impairment caused by TBT) in the whelk (Thais orbita) continued to be observed close to marinas and harbours.
While the concentrations of dioxins in Bay sediments are low by world standards, their impacts on marine communities there are unknown (Vic. Govt 1992c).
Published and unpublished information on the environment of the Bay has recently been summarised in a number of reports and reviews, as the initial phase of the Port Phillip Bay Environmental Study (Beer et al. 1992; Black & Mourtikas 1992; CSIRO 1992b ).
During the spring and summer of 1992-93, broken sewer pipes in inner Melbourne suburbs resulted in large overflows of raw sewage through the Maribyrnong River and into Hobsons Bay. In one incident, untreated sewage flowed into the estuarine section of the river at a rate of 3.1 ML/hr (equivalent to less than 1% of the river flow). Combined with high rainfall and the consequent high outflow rates of the Maribyrnong and Yarra Rivers, this produced high Escherichia coli levels over a wide area of northern and eastern Port Phillip Bay for several weeks. Warnings were issued to avoid swimming and collecting of fish and shellfish in the area. Localised outbreaks of illnesses among beachgoers at Williamstown were linked to this episode.
Three large blooms of the toxic dinoflagellate, Alexandrium catenella, have occurred mainly in Hobsons Bay; in January 1988, April 1991 and January 1992.
Corio Bay is extremely vulnerable to environmental damage because it is shallow, has a low rate of exchange with Port Phillip Bay and a high concentration of industrial and shipping activities.
Cadmium contamination of Corio Bay is the most notable of all pollution events in Victoria. During the 1960s, effluent from a paint pigments factory discharged through the stormwater system into this bay. Since this discharge was stopped, cadmium concentrations in mussels have decreased and are now below the maximum permitted concentration (Nicholson 1992). However, the wider impact of this contamination has extended out into the Geelong Arm where the farming of native oysters off Clifton Springs was prohibited because of the combination of the trace levels of cadmium and the oyster's ability to concentrate this metal.
In the period between studies conducted from 1976 to 1978, and 1987 to 1988, concentrations of cadmium, copper, iron, lead, manganese and zinc in tissues of mussels decreased at most sites (Nicholson et al. 1992d). In all cases in the latter study, concentrations of these metal toxicants were well below the maximum permissible concentrations for public health. Concentrations remained highest in mussels from the sites off the industrialised region in the north-western part of Corio Bay. Concentrations of cadmium and other metal toxicants in sediments were also found to have generally deceased, although high cadmium levels persist in the inner Rippleside region (Nicholson et al. 1992c).
A comprehensive study of mercury concentrations in sediments in Corio Bay (Nicholson et al. 1992b), showed that high concentrations remain associated with two historical sources (the former Corio Shire tip and the Phosphate Cooperative plant) and the Shell Oil Refinery. In general, concentrations were greatest 20-30 cm below the surface. While the concentrations reported were considered to pose little danger to aquatic organisms, the ecological implications of channel dredging and spoil disposal warrant careful examination in Corio Bay. Of 13 species of fish studied in Corio Bay, only yank flathead (Platycephalus caeruleopunctatus) and snapper (Pagrus auratus), had mercury concentrations above the National Food Authority health standard (Nicholson et al. 1992a). Concentrations in sand flathead (Platycephalus bassensis) were found to have decreased since the mid-1970s. Mercury concentrations in flathead species have decreased during the 1980s (Nicholson 1992).
Between 1987 and 1990, studies of petroleum hydrocarbons and pesticides in sediments in Corio Bay found that, while concentrations in some areas were lower than in the late 1970s, they were still high enough to be toxic to some benthic species (Fabris et al. 1992a); organochlorine pesticide concentrations were low. Studies of mussels showed that, while inputs of PCBs decreased during the 1980s, Corio Bay continued to be chronically contaminated with petroleum hydrocarbons from oil refining, shipping and recreational boating (Fabris et al. 1992a).
The highest levels of petroleum hydrocarbons and PCBs found in flathead tissues from Port Phillip Bay came from sites in and close to Corio Bay (Nicholson 1992).
The Geelong Shell refinery daily releases large volumes of heated seawater which has been treated with chlorine to prevent settlement of fouling organisms in the cooling system. The quality of the discharge has been improved by the separation of process water (which now goes to sewer) from cooling water.
In 1987, studies of the benthic communities in Corio Bay found them to be typical of those which are to be expected in shallow, muddy environments. Comparison of these communities with those from similar habitats elsewhere in Port Phillip Bay showed that the species diversity in Corio Bay was typical, but the number of animals present was lower (Coleman 1993).
Major human environmental impacts on this Bay began in the 1890s with the commencement of large-scale drainage of the surrounding swamplands. The input of sediments is substantially less now and most of the earlier material appears to have become sorted and stabilised, although it is thought to have smothered large areas of former seagrass beds (NREC 1991). Intertidal banks make up about 35% of the Bay area. Of this, about 260 km2 were covered by seagrass of which some 70% has disappeared in the last two decades. While the causes are not known, accelerated sediment deposition from catchment erosion and swamp drainage, as well as port development, shipping and boating activities, and associated pollutants have all been suggested. The impacts on seagrass-dependent fish species, notably King George whiting (Sillaginodes punctatus), and the consequent impacts on commercial and recreational fisheries, have been significant.
BHP's industrial cold steel rolling works are licensed to discharge effluent containing phosphorus compounds, zinc, and surfactants. Esso Australia Pty Ltd at Long Island Point is licensed to discharge effluent containing sulphides, phosphorus compounds, surfactants and other pollutants.
The biological and chemical thresholds set in the SEPP are exceeded at times, probably as the result of phosphorus and suspended solids from agricultural run-off (LCC 1993).
Since the construction of the permanent opening to the ocean in 1889, the Lakes have undergone a number of major ecological changes, some of which have occurred over periods of decades. Increased salinity in the Lakes has led to the establishment of seagrass beds which now cover about 12% of the Lakes area and dieback of former fringing vegetation from much of the shore.
Lake Wellington has high turbidity (the result of loss of bottom vegetation) and extreme variability in salinity levels, presenting a hostile environment which is reflected by poorer flora and fauna than the lakes further east (NREC 1991).
The presence of the salt-water wedge under brackish outflows and the resultant stratification is thought to be connected to the incidence of algal blooms, particularly of the blue-green alga (Nodularia spumigena) (NREC 1991). There are reports of blooms in the Lakes in the 19th century and well documented major blooms in 1971, 1974 and 1987-88 (Chessman 1988). Following the last of these (which lasted for five months), a seminar examined in detail the condition of the Lakes and the range of possible factors which may influence the occurrence of algal blooms. The general consensus was that the major cause was nutrient release from sediments, caused by high oxygen demand in sediments isolated by stratification linked to the inflow of ocean water through the artificial entrance (Bremner 1988).
Since 1986, monthly monitoring of compliance with SEPP water quality objectives has been conducted in Lakes King, Victoria and Wellington. A more intensive program to monitor algal blooms started after the major bloom of 1987-88, but was discontinued in 1991. In the three years since a contingency plan for algal bloom occurrences in the Gippsland Lakes was prepared, there has been no bloom large enough to warrant its implementation.
One significant pollution input into the Lakes system was eliminated in 1992 with the commissioning of the Delray Beach Ocean Outfall. Previously, the Maryvale APM pulp and paper mill's treated wastewater was discharged into Lake Coleman, an enclosed wetland adjacent to Lake Wellington. In addition, the major lakeside towns of Lakes Entrance, Metung and Paynesville have been sewered in recent years.
Victoria periodically experiences minor oil spills along the open coast. For instance, a spill from a passing ship in 1990 resulted in the deaths of hundreds of little penguins off the Otway Peninsula. In the major bays and in harbours such as Portland, minor spills occur frequently.
The main point source discharges to coastal waters are from sewage treatment plants of which nine are treated to a secondary level. The 17 licensed discharges to Victoria's open coastal waters are, from west to east: Portland, Port Fairy, Warrnambool, Apollo Bay, Lorne, Anglesea, Black Rock, Boags Rocks, Cowes, Wonthaggi, Leongatha, Foster, Toora, Port Welshpool, Yarram, McGaurans Beach and Delray Beach.
A descriptive study of these discharges and their impacts (McKenzie & Goudey 1991) showed that some of the sewage discharges (e.g. Warrnambool) have a significant localised effect on marine communities through nutrient enrichment, and all contain low levels of persistent toxicants. Two outfalls, Toora and Foster, discharge into marine parks and are to be phased out. Only two discharges are mainly from industrial sources: the Leongatha outfall discharges milk wastes into the surf zone at Venus Bay, and the Saline Waste Outfall Pipeline at McGaurans Beach discharges saline wastewater containing metals from the Loy Yang power station.
The Boags Rock outfall discharges the highest volume (200 000 megalitres per annum), being 35% of Melbourne's sewage treated to secondary stage at the South Eastern Treatment Plant.
The second largest volume comes from Black Rock where 20 300 megalitres per annum of domestic and industrial waste from the Geelong region is screened before discharging through a submerged pipeline, 1.2 km offshore. Prior to 1989, this discharge was unscreened and occurred at the shore. Acute toxicity tests show that the Black Rock effluent is acutely toxic requiring considerable dilution to satisfy the SEPP Waters of Victoria standards. Anionic and nonionic surfactants, and phenols were determined as the main contributors to this toxicity (McKenzie & Goudey 1991).
During 1992, potentially toxic algae were first reported from Lorne (Gymnodinium catenatum) and at several locations from Portland to Lorne (Alexandrium tamarense) (S. Conron DCNR, pers. comm.).
In virtually every inlet and estuary from Mallacoota Inlet to the Glenelg River, upstream land use practices associated with farming and forestry, plus reduced flow rates resulting from water management, have resulted in significant shallowing and alteration of aquatic habitats. In some instances, this effect has been magnified by other factors. For instance, in Anderson Inlet the introduction of Spartina to stabilise banks has accelerated the shallowing and modification of habitats, to the detriment of fish and birds.
Catchment land degradation has caused siltation and high total dissolved solid levels in the estuarine reaches of a number of coastal rivers and streams, notably Glenelg River, Hopkins River, Curdies Inlet, Lake Connewarre and Barwon River, Werribee River, Anderson Inlet, Shallow Inlet, Corner Inlet and Nooramunga, Sydenham Inlet, Snowy River and Mallacoota Inlet. Other consequences include brackish groundwater and severe dry land salting which affect rivers such as the Glenelg, Hopkins and Barwon.
Other common indicators of degraded systems include elevated nutrient concentrations (Hopkins, Curdies, Barwon, Little, Yarra, Bunyip and Thompson), colour (Gellibrand, Barwon, Little, Maribyrnong, Bunyip, Thompson, Tambo and Snowy), bacterial contamination (Barham, Yarra, Bunyip, Tambo and Snowy) and low dissolved levels (Hopkins, Yarra, Bunyip and Thompson).
In several instances, grazing and land clearance has resulted in damage to fringing vegetation and the introduction of weeds.
The damming of many small coastal streams (e.g. Spring Creek and Anglesea River) has greatly modified the physical and biotic nature of their estuaries.
Since 1984, the EPA and the Department of Conservation and Natural Resources have sampled fixed sites, fortnightly, as part of a Fixed Sites Monitoring Program, aimed primarily at assessing compliance with SEPP standards for Port Phillip Bay (Colman et al. 1991). In 1988, the number of sites was increased to six. From 1987 to 1989, routine monitoring of salinity, temperature, nutrient and chlorophyll levels was supplemented by a study of the frequency, duration and severity of depressed dissolved oxygen levels in the centre of the Bay (Mickelson 1990).
Since 1990, in a separate but related program, the Department of Conservation and Natural Resources has conducted a Water Quality Monitoring Program in Port Phillip Bay to provide continuous assessment of water quality to ensure the quality of harvested fish and shellfish and to protect flora and fauna. At two sites, automated data loggers continuously monitor salinity and temperature. At six sites, fortnightly depth-integrated samples are analysed for inorganic nitrogen; phosphate; silicate; particulate phosphorus, nitrogen and carbon; total phosphorus and nitrogen; total organic carbon, suspended solids and chlorophyll pigments. Vertical profiles of temperature, salinity, dissolved oxygen, chlorophyll fluorescence and photosynthetically active radiation are also recorded fortnightly. Time series analysis will be applied to the data to detect temporal trends and to relate trends to possible causal factors.
The Fixed Sites Monitoring Program also covers Westernport Bay (3 sites) and the Gippsland Lakes (5 sites). Water samples are taken at the surface in Westernport Bay and Gippsland Lakes, and near-bottom waters are also sampled in the Lakes to look for conditions that may lead to algal blooms. The following parameters are measured at each site: nutrients, chlorophyll and suspended solids in waters; trace metal concentrations in waters and sediments; petroleum hydrocarbons in sediments.
Since 1989, an annual trawl survey has been conducted each autumn to detect any changes to the abundance and species composition of fish communities in Port Phillip Bay. A total of 22 depth-stratified stations are sampled.
The draft revision of the Port Phillip Bay State Environment Protection Policy (EPA 1991) proposes that the annual load of nitrogen discharged into Port Phillip Bay from the Werribee Treatment Complex must not exceed 4300 tonnes. The draft proposes that the EPA will continue monitoring chlorophyll a, nitrogen and phosphorus, and that it will establish an algal monitoring program. It also proposes that the EPA and the Department of Conservation and Natural Resources will jointly develop a Port Phillip Bay Management Plan (in consultation with other government and nongovernment organisations). Initially, this should address the nutrient sources, loads and status of the Bay; the sources, fate, impact and management of toxicants in Bay waters, sediments and biota; and the strategy necessary for management of environmental quality in the inshore segment of the Bay. The revised SEPP will address all aspects of physical and chemical pollution and disturbance to the Bay.
In September 1987, due to the presence of the toxic dinoflagellate, Alexandrium catenella, a marine biotoxin monitoring program was established to protect the health of human consumers of Port Phillip Bay shellfish and to assist with the management of the aquaculture industry (Arnott 1990). The program entails routine phytoplankton monitoring, bioassays and an early warning network.
The value of monitoring of contaminant levels in waters, sediments and biota has been proven repeatedly in Victoria. For instance in Corio Bay, monitoring of heavy metals in sediments has shown general decreases which are at least partly attributable to stricter regulatory measures by the EPA (Nicholson et al. 1992c).
Other recent initiatives include:
During the last decade, a number of programs have commenced to address the complex environmental issues facing the Gippsland Lakes. The Gippsland Lakes Strategy focuses on key issues such as catchments, water quality, planning, management and tourism, to provide broad policy directions. Among the more specific programs are the Gippsland Lakes Management Plan, South East Water Management Strategy and algal bloom initiatives (Smith 1988), and the Gippsland Regional Landcare Plan (Regional Landcare Community Reference Group 1993). By early 1993, about 30% of the actions proposed in the Gippsland Lakes Management Plan had been implemented.
Over and above the continuation of current programs, the following initiatives are being planned or implemented to further improve Victoria's marine environment:
In addition, industry and the community are being urged to act to improve their respective voluntary contributions to improvement in the quality of the marine environment (Vic. Govt 1992c).
Water authorities with ocean outfalls not meeting the requirements of the SEPP Waters of Victoria are required to upgrade their treatment works to produce effluent of secondary treatment quality or discharge their wastes to land (the preferred option) by 1997. Several authorities are already taking steps to upgrade the quality of their coastal discharges. For instance, the Geelong and District Water Board's Black Rock plant and the Warrnambool system are both at advanced stages of planning and upgrading to comply with the SEPP. The Alberton Water Board (Yarram) expects to cease discharging to the ocean by mid-1993.
Authorities responsible for the smaller discharges are at various stages of planning or upgrading their treatment and discharge facilities.
Under recent policy statements for Victoria, representative habitats and marine and estuarine areas of high conservation value or importance as habitats for production of fisheries resources are to be identified and, if necessary, set aside as protected areas.
The Land Conservation Council (LCC) is conducting a major statewide planning and assessment task upon which much of the future security of Victoria's marine environments rest. This includes an investigation of marine, coastal and estuarine resources; their status and use, and strategic planning advice on the protection of significant environmental values and the sustainable use of these resources. The first stage of this investigation has been the production of a comprehensive report which `describes the physical, biological and cultural values of the study area, identifies current and potential uses and outlines the broad social, economic, legislative, and conservation context for planning (LCC 1993). The LCC is scheduled to report to the Government at the end of 1994, following public input on the information base, issues and a draft report.
Another significant recent contribution to planning and assessment of the marine environment has been the first stage of a review of conditions and trends in marine and coastal environments, initiated by the former Office of the Commissioner for the Environment (Colman et al. 1991).
The first output of this task was a report outlining a comprehensive approach to detecting long term change in the condition of the marine environment. This report sets out key indicators for marine environments with details on recommended monitoring programs for Victorian marine waters, sediments, biota and ecosystems (Colman et al. 1991).
The study found that very little of the extant environmental data would provide for the detection of long term change, often because the sampling regimes of past monitoring programs were designed for other purposes (e.g. regulatory monitoring and impact assessments). The study observed that `Unless due attention is given to statistical design, there is a risk that substantial monitoring may be undertaken without any resultant ability to draw any significant conclusions about long-term change.'
Major recommendations were made on recommended key indicators for marine environments. In the case of water quality, key indicators were identified for specific areas (e.g. dissolved oxygen in central Port Phillip Bay) and wider areas (e.g. nutrients and chlorophyll a in Bass Strait). Other key indicators were recommended for marine biota (e.g. extent and health of seagrass meadows), sediments (e.g. nutrient, carbon and toxicant concentrations) and estuaries (e.g. salinity regimes and community structure). To distinguish between changes resulting from natural processes and from human activity, the study also proposed an approach to monitoring process and activity indicators for marine environments.
The establishment of the Office of the Commissioner for the Environment in 1986 was a major step towards a systematic approach to overviewing trends and the state of Victoria's marine environment. In October 1992, this position was terminated and the responsibility for continuing work was taken up by the Office of the Environment. The policy of the current Government is to establish a Parliamentary Committee to continue monitoring of Victoria's environment.
Progress continues towards a systematic approach to the assessment and protection of marine (and estuarine) areas of special significance. The development of biogeographic classifications for the description of the distributions of marine flora and fauna, the development of a national approach to the designation of marine protected areas, and the trend towards nominating significant areas to the Register of the National Estate are contributing to this progress. Malcolm (1992) has reviewed the work in this area, listing Victorian areas proposed for listing on the Register.
In practical terms, the Environmental Effects Statements produced for works, developments and discharges affecting Victoria's marine waters generally provide no more than a snapshot of the environments and marine communities involved. For instance, despite the fact that port authorities have dredged and dumped tens of millions of tonnes of sediment, much from contaminated areas, into bays and coastal waters, there is no basis for determining ecological impacts or of predicting the likely impacts of future spoil disposal on marine ecosystems. Some major developments with the potential for significant marine environmental impacts, such as the Shell/Mobil oil storage at Crib Point, proceed without a requirement for Environmental Effects Statements.
A Trial Dredge Protocol (EPA 1992) has been established to provide guidelines for maximum environmental protection from public works dredging associated with ports, shipping and boating facilities in Victoria. Referring to the relevant SEPP standards, the trial protocol sets out: the protocol objectives; the planning, evaluation procedures; the roles of approvals and works agencies; guidelines for dredging and spoil disposal (including preference for land disposal); and procedures for determining the contaminant status of dredged material. Thus while recognising the importance of shipping, this initiative attempts to control an environmentally damaging activity in a way that previous coastal planning and permitting processes were unable to do.
The protocol perpetuates the provision for exemption of dredging operations `which are considered essential for the operation of normal port activities'. Such operations usually involve the removal and dumping of large volumes of spoil (particularly in Port Phillip Bay), both in maintenance and development projects. In many instances, the spoil contains low levels of contaminants. The rationale offered is that, provided `the possible environmental costs associated with legitimate port activities' and other details of these operations are made public, they may proceed.
The implementation of the Gippsland Lakes Management Plan and Strategy Plan, developed during the late 1980s, and the completion and implementation of the revised Port Phillip Bay State Environment Protection Policy are other specific actions that will play important parts in the protection of coastal waters and resources and the improvement of land use management in the catchment and land adjacent to the Lakes.
Monitoring of contaminant concentrations in water, sediments and biota has proven the effectiveness of the EPA's discharge licensing and alternative waste treatment and disposal programs (and the value of environmental monitoring). This has provided a confident basis for a range of current measures designed to achieve further improvements in Victorian marine environments.
Further significant improvements to the quality of coastal waters can be expected under the Coastal Discharges Strategy which requires that all discharges to these waters meet secondary treatment standards, or that disposal occurs on land, by 1977.
In recent years, the Victorian Government has recognised the need for an integrated approach to the planning and management of public waters and their catchments (Vic. Govt 1989a). This has resulted in a shift from river to catchment management boards, and in the establishment of Catchment Coordinating Groups to link agencies and community groups as part of the implementation of integrated catchment principles. The future environmental condition of Victoria's inlets and estuaries will largely depend on how effectively this approach proves to be in reversing river and catchment degradation.
In 1991, for the first time since commercial scallop fishing began in Port Phillip Bay in 1963, detailed investigations were started into the fisheries and ecological impacts of the use of scallop dredges. It is intended that long-term impacts will be studied after the completion of short to medium-term impact studies in 1993. The ecological impacts of other commercial fishing activities are also being proposed, for instance pilchard and anchovy fishing in Port Phillip Bay and the use of haul seine nets in bays and inlets.
Because blooms of potentially-toxic algae such as Alexandrium catenella are occurring regularly in Port Phillip Bay, continuation of the Shellfish Quality Assurance Program, begun in 1987, will be necessary to safeguard public health of local and export market consumers of shellfish farmed or taken by fisheries, and to indicate changes to the environmental status of Victorian waters (Callan et al. 1993). National proposals to apply the same monitoring, certification and labelling standards to locally-marketed shellfish as currently apply to exports offer improved product quality, protection of public health and improved cost-effectiveness of management programs.
In 1992, the Victorian Government's unequivocal endorsement of the principles of Ecological Sustainable Development (ESD) in fisheries gave hope that protection of the marine environment, particularly that of fish habitats, will be given greater prominence in future. Already, fishery management plans are being produced on an ESD framework which emphasises the importance of factors including habitat protection and water quality, from the points of view of maintaining exploited fish stocks and ensuring seafood quality.
The Government outlined its commitment (Vic. Govt 1992b) to the 51 recommendations made by a parliamentary review of bay and inlet commercial and recreational fisheries, and emphasising the importance of fish habitat protection. Those recommendations feature expressions of concern and actions to be taken to deal with:
During 1992, a major study of the Bay was commenced by Melbourne Water, the Environment Protection Authority, the Port of Melbourne Authority and the Department of Conservation and Natural Resources (CSIRO 1992a). The main aim of the three year study is to determine the environmental status of the Bay and its capacity to absorb future increases in nutrients (and trace levels of toxicants), principally from the Werribee Treatment Complex. This information is essential as the basis for the environmental management of the Bay for at least the next 20 years (CSIRO 1992a).
The key scientific information to be sought includes a comprehensive understanding of the physical processes which influence transport, distribution and mixing of discharged materials; knowledge of the status of inputs, water and biota and certain transformation processes for nutrients and toxicants; and the role of sediments as storage reservoirs and as sites for transformation processes.
The major challenges lie with protecting and restoring marine environments in the face of further population growth, water usage and intensification of urbanisation and land use. The population of Melbourne is forecast to grow from 3.02 million in 1991, to more than 3.3 million in 2001 and to 3.6 million in 2015 - an increase of 580 000 people in 24 years. Victoria's population will rise to about 5.7 million in that period, increasing by 1.3 million people.
To service the projected growth of Melbourne, upgrading of the sewerage system will be required, plus a reassessment of the environmental impact of point-source and diffuse load to waterways and coastal waters receiving effluent discharges (Vic. Govt 1989a). With major urban growth extending east, particularly into the Westernport catchment, a major additional treatment plant with capacity to service 100 000 people will be needed before the year 2015. Following the trend in environmental policy, land disposal of sewage effluent must be properly evaluated.
The combination of expanded water storages and improved demand management have improved the medium-term outlook for water usage in Victoria. Reduced domestic consumption rates, improved sewage treatment, stricter industrial wastewater management and other related measures will help in the overall effort to reduce the inputs of contaminants to marine waters.
Notwithstanding the previous Government's undertakings given in the state conservation and coastal strategies (Vic. Govt. 1988 & 1987), surveys of Victoria's marine habitats and communities and assessment of their conservation and special protection needs have not proceeded. This will continue to severely hamper the task of marine conservation and promote the continuation of an ad hoc and reactive approach.
Despite the precautionary measures implemented at a national level, a major area of concern for Victoria is the increased incidence and severity of harmful algal blooms in marine waters, apparently resulting from the combination of the global spreading of toxic species and increased nutrient loadings.
Further, it appears to be only a matter of time before the seastar (Asterias amurensis) and the Japanese seaweed (Undaria pinnatifida) reach Victorian coastal waters. Both are believed to have been introduced in ballast water to the Tasmanian east coast, where they are having significant ecological and fisheries impacts.
In 1989, the Victorian Government prepared a strategy to address the broad implications of the Greenhouse Effect for the State (Vic. Govt 1989a & 1989b). Climate and ocean studies were identified as priority strategic research areas and cooperative research programs commenced with the CSIRO and the Australian Bureau of Meteorology.
Overall, Victorian waters and marine habitats are in reasonably good condition, supporting healthy living resources, supporting a significant fishing industry and water-based recreation and tourism. However, pollution and development have had obvious impacts on water quality and natural resources and there are concerns over their cumulative effects as the population of Melbourne and Victoria grow, accompanied by continuing industrial, coastal infrastructure and residential growth. Even with improved quality of coastal discharges in recent years, the enclosed nature of Port Phillip Bay, Westernport Bay and the Gippsland Lakes, coupled with this continuing growth, mean that there is no room for complacency.
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