6.2 Marine contamination

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Priority Rating: 4

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Description

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Contamination of the marine environment occurs when nutrients, toxic chemicals and pathogens enter the environment and are present at levels greater than found naturally, or result in adverse effects on the marine environment. Toxic compounds include agricultural and industrial chemicals (e.g. heavy metals, pesticides and herbicides), runoff from acid sulphate soils, oil spills, produced formation water (water extracted during oil recovery), drilling muds (lubricants used in drilling for oil and gas), and chemicals released as a result of day-to-day port operations (e.g. tributyltin (or TBT), an ingredient in antifouling paints used on the hulls of ships). These substances can persist for long periods of time, and may accumulate in biota causing serious health impacts to animal or human health at very low concentrations.

Nutrients (including nitrogen and phosphorus) are one of the most widespread threats to the marine environment and can change ecosystems by stimulating the growth of marine primary producers such as phytoplankton and algae, often to the detriment of other species. Nutrients are discharged to the marine environment through treated wastewater outfalls, industrial and aquaculture discharges, stormwater runoff, and from waterways or groundwater discharge. Pathogens include bacteria, viruses and toxic algae are typically found in stagnant waters with elevated nutrient levels. Pathogens also pose health risks to humans and animals that come into contact with, or eat seafood from, affected areas. They can enter the marine environment through a number of sources such as wastewater outfalls, stormwater, boat sullage and groundwater.

Other contaminants of the marine environment include stressors that alter the marine environment. Excess sediment deposition can result in the smothering of marine flora and fauna and increased turbidity in the water column (see 'Degradation of marine environments'). Hypersaline water or discharges of hot or cold waste water (from industrial sources) can detrimentally affect local marine ecosystems, particularly when these are beyond the limits of natural variation. Non-biodegradable litter dumped into the marine environment is also a threat to marine animals through entanglement or ingestion.

Objectives

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To protect our marine environment by ensuring that levels of marine contaminants meet relevant standards by:

• defining and protecting environmental values in order to protect and improve the condition of the marine environment;
• reducing and eliminating (where practical) the sources of contamination of the marine environment;
• conserving the marine environment and associated values identified as most important; and
• managing and using marine resources in a sustainable manner and rehabilitate areas affected by marine contamination where practical.

Condition

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Indicator M7: Levels of nutrients, toxicants and pathogens compared to guidelines and standards.

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Cockburn Sound is currently the only area of the State's marine environment where the environmental quality management framework is being given effect through the State Environmental Protection (Cockburn Sound) Policy 2005 (Government of Western Australia, 2005). Water and sediment quality targets that are set out in contemporary management plans for marine conservation reserves are a non-binding form of environmental quality framework.

Each year, the Cockburn Sound Management Council produces a series of report cards on the health of Cockburn Sound (Table M2.1). In 2005, the moderate ecological protection area of Cockburn Sound was divided into areas within Jervoise Bay harbours, and all areas outside Jervoise Bay harbours (Table M2.1). Prior to this date no distinction was made between the two areas. Environmental quality standards for chlorophyll a and tributyltin have not been met within the Jervoise Bay Harbours (a moderate ecological protection area) over a number of years (Cockburn Sound Management Council, 2006b).

Tributyltin levels in sediment have historically exceeded environmental criteria within the moderate ecological protection areas (especially for harbours and jetties) and this has been a long term issue for the Sound. However, changes to international regulations banning tributyltin paint are being implemented and are believed to be reducing tributyltin levels in sediments. The environmental quality standard for tributyltin was not met for the high ecological protection area in 2006 because marine snails at Woodman Point showed signs of imposex affecting females (Table M2.1).

Nutrient enrichment commonly results in increased abundance of algae in the water column (i.e. phytoplankton) and attached to the seabed and organisms that live there (i.e. epiphytes). The proliferation of phytoplankton and attached algae can reduce water quality and the health of benthic communities such as seagrasses meadows, and lead to changes in marine ecology. This is important in WA because our marine environment is naturally low in nutrients, so any enrichment that occurs is likely to alter natural ecology.

Generally, there are no contaminant issues of concern in Cockburn Sound, especially in the high ecological protection areas (Table M2.1). Chlorophyll a (used as an indicator of algal growth) levels have improved in the high ecological protection areas, but remain a problem in the moderate ecological protection areas within Jervoise Bay Harbours. Light attenuation (reduction of light passing through the water column) was thought to be improving in the high ecological protection areas of Cockburn Sound, but recent results are again of concern. Light attenuation continues to be a problem in the moderate protection area. Phytoplankton blooms (due to elevated nutrient levels) have been historically noted in the moderate level of protection areas and remain a concern within the Jervoise Bay Harbours (Table M2.1).

There are ongoing issues with seagrass shoot density in the high ecological protection area as plants are further apart than those in healthy ecosystems. This is consistent with research that shows that seagrasses in Mangles Bay (Rockingham) and on the eastern side of Garden Island are highly stressed with low shoot density, height and biomass, and dead rhizomes in the sediment (Lavery & Westra, 2004).

Table M2.1: Environmental quality indicators for ecosystem health in Cockburn Sound, 2001-06.

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Data source: Cockburn Sound Management Council (2006). Notes: a) Low protection areas are not listed due to limited monitoring data, and report cards have not been prepared. b) The method of data display does not allow the distinction between Jervoise Bay and outside Jervoise Bay prior to 2005. c) Non-metallic inorganics, organics, pesticides, herbicides and fungicides, surfactants, hydrocarbons, and miscellaneous/others were also measured but were consistently found to be below detection limits.

Environmental quality indicators for seafood consumption, aquaculture and recreational water quality (i.e. for boating and swimming; Table M2.2) indicate that most criteria have been met over time, with the exception of faecal contamination at Rockingham Beach in the summer of 2005 and 2006. Management actions have been initiated by the State and local governments to identify the sources of contamination and upgrade stormwater outfall drains to affected beaches. Faecal bacteria have been detected in water (but not in seafood flesh) at three sites around Rockingham and further investigation is required. The presence of potentially toxic algae was detected at several sites in Cockburn Sound however further testing revealed no further problems for two of the sites. Cockburn Sound Management Council recommends that the public are aware of the risk of eating seafood collected recreationally from Jervoise Bay harbours.

Table M2.2: Environmental quality indicators for seafood safe for eating, protecting the health of aquaculture, and clean waters for swimming and boating in Cockburn Sound, 2001-2006.

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Data source: Cockburn Sound Management Council (2006). Note: a) Environmental quality indicators for industrial water supply were not reported. Note: Key is the same as that for Table M2.1.

Indicator M8: Number of marine algal blooms.

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Anecdotally, there are very few problems with algal blooms in marine waters except for the Jervoise Bay northern harbour in Cockburn Sound, where phytoplankton biomass criteria are being exceeded (R. Masini, Department of Environment and Conservation, pers. comm.). The Strategic Research Fund for the Marine Environment undertook monthly monitoring between 2002 and 2004 off the coast of Perth from 100 to1000 m depth. The study found that more phytoplankton is present during summer and this is probably related to the intensification of the Leeuwin Current, possibly as a result of high nutrients levels and temperature in surface waters. Monitoring data around major ocean discharges of treated domestic wastewater suggests the effects of nutrient discharges can be detected (Thompson & Waite, 2003; Cosgrove et al., 2004). In the absence of a management framework it is not possible to assess whether or not these changes are acceptable or not.

Indicator M9: Mollusc and sediment levels of heavy metals and tributyltin.

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Imposex (females developing male sexual organs) in shellfish is an indicator of marine tributyltin contamination over time, as it interferes with hormone production and causes higher testosterone levels. Cockburn Sound sites have consistently failed to meet environmental quality objectives for tributyltin in sediments in the moderate protection area (Table M2.1). Previous studies in Perth coastal waters (Reitsema, Field & Spickett 2003; K Sylva, M Gagnon & T Reitsema, Curtin University, pers. comm.) showed a general decrease in the incidence of imposex in whelks (Thais orbita) between 1993 and 2005 in areas frequented by small recreational craft including Hillarys, Cottesloe, Carnac and Penguin islands, and all Rottnest Island sites (Figure M2.1). The decrease may be attributable to a ban on the use of tributyltin paints on vessels less than 25 metres. However, areas visited by larger vessels (including Arthur Head, Fishing Boat Harbour, North and South Jervoise Bay, Challenger Beach and Colpoys Point) remain high and generally did not show a decrease in imposex rates (Figure M2.1).

 

Figure M2.1: Percentage of female whelks displaying imposex condition in Perth coastal waters over time, in larger port and harbour facilities and areas frequented by small recreational vessels.

Data source: Reitsema, Field & Spickett (2003); K Sylva, M Gagnon & T Reitsema, Curtin University, pers. comm. Analysis: EPA. Presentation: EPA. Note: The 2005 collection points for Rous Head, Arthur Head and North Jervoise Bay are not exactly the same as previous years. Sampling at Rous Head was conducted on the outside of the Mole (technically North Mole), and this might have resulted in the decrease from 100% to 86%. The same collection technique was used for the Arthur Head and South Mole 2005 data, but no decrease in imposex was observed at these sites. The 2005 sampling at North Jervoise Bay was closer to Woodman Point than in previous years.

A North West study showed that molluscs at Dampier had a lower incidence of female imposex (0% to 54%) than Perth (Reitsema & Spickett, 1999), despite having the highest tonnage of any port in WA and Australia. It is believed that tributyltin may break down or disperse more quickly in northern waters due to increased sunlight and water circulation (Reitsema & Spickett, 1999). The replacement of tributyltin with other antifouling products needs to be approached with caution, as alternative biocides are also likely to have ecosystem effects. However, the fouling of ships' hulls in the absence of tributyltin or other biocide has serious implications for the transportation of introduced marine species around the world (see 'Introduced marine species').

Surveys for background concentrations of selected heavy metals and organic compounds in water and sediments off Perth, Jurien Bay Marine Park, the North West Shelf and the Pilbara all revealed very low levels. Concentrations of metals were low by world standards and toxic organic compounds were not detected in any of the samples from Perth or Jurien Bay (McAlpine et al., 2005a & 2005b). There was no evidence of heavy metal contamination in sediments near treated wastewater outfalls in Perth's metropolitan waters at Sepia Depression, Swanbourne and Trigg (DAL Science and Engineering, 2004).

North West Shelf waters generally have very low concentration of metals, with localised elevations of some metals adjacent to industrial centres and ports. Metal concentrations met the environmental quality guidelines for a very high level of ecological protection (99% species protection) throughout the sampled area, with the exception of the inner harbour at Port Hedland (Wenziker et.al., 2006). The inner harbour had copper and zinc levels elevated above background concentrations, but below the 95% species protection guidelines (representing a high level of ecological protection). No organic chemicals were detected in any of the samples from the North West Shelf (Wenziker et.al., 2006).

Pilbara marine sediments contained higher concentrations of some metals and organic compounds, thought to be naturally higher due to local geology (Department of Environment and Conservation, 2006). At most sites, compounds were below normal detection limits, but the sediments of the Ashburton River had very high levels of aluminium and iron. Arsenic concentrations were generally high across all of the sampled sites (except Dampier Archipelago) and natural background concentrations were close to, or above, the recommended interim sediment quality guideline. Slightly elevated levels of arsenic and zinc were detected in sediments of Dampier Port. However, the concentrations were well below the recommended national interim sediment quality guidelines.

A number of water and sediment surveys have also been undertaken in the vicinity of industrial areas and ports around WA for environmental impact assessment purposes. Although the results suggest that localised high concentrations of some toxic compounds do occur, the data cannot be interpreted with confidence, given the various methods used.

Indicator M10: Number of aquaculture and beach water closures due to detection of pathogens.

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The lack of coordinated and consistent monitoring of the marine environment means that it is difficult to quantify marine contamination, or to establish trends over time (with the exception of Cockburn Sound). Areas prone to contamination are generally those that are close to human settlements with limited water exchange between bays and the open ocean (e.g. Cockburn Sound, Princess Royal Harbour, Shark Bay, Exmouth Gulf, Mermaid Sound and all ports and marinas).

The Department of Health and local councils undertake some sampling of water quality at Perth metropolitan beaches, although the results are not publicly available or reported.

Sampling of water and seafood quality is undertaken in areas of aquaculture operations (Cockburn Sound and Oyster Harbour) to ensure that health regulations relating to domestic consumption and export of seafood are met. Between 1997 and 2005 faecal pathogen contamination in Cockburn Sound was detected seven times and short-term actions were taken (such as suspension of harvest for one to two days). There was one incidence of discharge of arsenic into Cockburn Sound (approximately 900 kg over 6 weeks) resulting in the temporary closure of fisheries as a precaution. There were nine incidences of petrochemical spills around Kwinana Grain Terminal and only one resulted in a fishery closure (due to persistent algal blooms). The aquaculture fisheries in Oyster Harbour estuary also experienced contamination between 1997 and 2005, mostly due to faecal pathogen contamination, which resulted in harvest suspension or fishery closure for up to three weeks. 

Pressures

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Sources of marine contaminants include ocean discharges of industrial wastes and treated domestic wastewater, stormwater runoff, groundwater and waterway discharge, commercial shipping, port developments, recreational boating, harbours and marinas, and the atmosphere. Of these sources of marine contamination, only treated wastewater is reliably measured.

Indicator M11: Nutrients entering the marine environment.

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Wastewater treatment outfalls are the most significant nutrient sources to the marine environment. Wastewater treatment plants in Beenyup, Woodman Point and Subiaco have outfall pipes in Perth coastal waters at Ocean Reef (Beenyup), Sepia Depression and Swanbourne respectively. These plants are operated by the Water Corporation under licence and Ministerial conditions regulated under the Environmental Protection Act 1986. A total of 320 million litres of treated wastewater is discharged each day, composed of 99.97% water; the remainder is dissolved and suspended matter (Water Corporation, 2005b). Nitrogen and phosphorus loads for the three wastewater treatment plants have consistently been within licence limits (Figures M2.2, M2.3 and M2.4).

 

Figure M2.2: Average output loads of phosphorus and nitrogen from Beenyup Wastewater Treatment Plant to ocean outfall pipe, 1995-2006.

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Data source: Water Corporation [ver. 2007]. Presentation: EPA.

 

Figure M2.3: Average output loads of phosphorus and nitrogen from Woodman Point Wastewater Treatment Plant to outfall, 1995-2006.

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Data source:  Water Corporation [ver. 2007]. Presentation: EPA. 

 

Figure M2.4: Average output loads of phosphorus and nitrogen from Subiaco Wastewater Treatment Plant to outfall, 2002-06.

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Data source:  Water Corporation [ver. 2007]. Presentation: EPA. 

Monitoring of all metropolitan outfalls shows no evidence of detrimental environmental effects (Water Corporation, 2003). Perth's Long Term Ocean Outlet Monitoring program involves regular monitoring of seawater quality, treated wastewater quality, phytoplankton, periphyton and benthic habitats. In 2002, the Woodman Point Wastewater Treatment Plant underwent significant process upgrades from primary treatment to secondary treatment (where nitrogen is removed from the wastewater using a biological agent) and increased capacity. Increasing coastal populations across the South West are likely to result in increasing volumes of wastewater being discharged from Perth, Mandurah, Bunbury and Busselton (Figure M2.5).

Groundwater is also a significant source of nutrients to the marine environment, and there has been a concerted effort by industry to reduce nitrogen inputs from groundwater sources to Cockburn Sound. Studies in Cockburn Sound have shown that the nutrient inputs from human activities have declined from an estimated 2000 tonnes per year in 1978 to about 300 tonnes per year in 2000, about 70% of which is from groundwater (Department of Environment, 2005). Altered circulation and flushing movements of water in the Sound also has a significant impact on nutrient concentrations (D.A. Lord and Associates, 2001).

Figure M2.5: Total inflows of wastewater to all Water Corportation treatment plants, 1995-2006.

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Data source: Water Corporation [ver. 2007]. Analysis: Water Corporation. Presentation: Water Corporation. 

Indicator M12: Toxic compounds entering the marine environment.

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Oil and other hydrocarbon products can spill from rigs, storage facilities or transport vessels. These pollutants can spread, oxidise and emulsify (dissipate through the water column) quickly and poison biota, as well as create a viscous physical coating on marine habitats and biota. The risk of contamination from oil and chemical spills is significant in WA, with an extensive coastline, large transport vessels and major shipping routes. There were 92 reports of oil pollution between February 2003 (when ports began to report to a central database) and December 2006 (Department for Planning and Infrastructure, unpublished data). Small spills and reports of sheens in harbours, marinas and ports made up the majority, with only 6 reports for spills over 100 litres. Responses to these spills varied according to type of oil, location and environmental resources at risk. The typical response to larger spills involves attempts to contain and recover the oil, while for smaller spills recovery may be attempted and the oil monitored for natural dispersion. Five instances of tarballs washed up on beaches were reported in this period. Geochemical analyses of tarballs collected from beaches around Margaret River suggest they originated from natural seeps in Indonesia and had not been processed into fuel oil. While no areas appear to be directly under threat at present, there is potential for a large spill or one that affects a sensitive marine area to occur. However, good management practices aim to minimise risk of environmental damage due from oil spills. The Environmental Protection Authority has defined a number of areas it considers particularly sensitive, especially to oil spills (Figure M2.6; Environmental Protection Authority, 1993).

Marine environments can also become contaminated by terrestrial sites (see 'Land contamination'). The Contaminated Sites Register lists140 reported sites within 50 m of the WA coastline (Department of Environment and Conservation, unpublished data April 2007). Of these, 11 have been verified as being contaminated and needing remediation, and one has been remediated for restricted use. However, the presence of a contaminated site near the coast does not infer contamination of the marine environment. Often the release of contaminants only occurs when earthmoving work is conducted which disturbs land or sediments. Some areas of concern for release of toxic compounds into the marine environment include Coogee (south of Fremantle) and Geraldton.

Studies of the groundwater movement into Cockburn Sound have shown that there is still considerable groundwater contamination under industrial sites due to metals and organic compounds. For example, as a result of past practices, a plume of groundwater pollution containing high concentrations of phenols and two herbicides exists within the Kwinana Industrial Area (D.A. Lord and Associates, 2001).

The EPA has defined a number of areas it considers particularly sensitive, especially to oil spills (Figure M2.6). There are different criteria for sensitivity, such as environments of international and national ecological or conservation significance, environments where biological resources are of major economic significance (eg. fishery and aquaculture areas), environments of major cultural significance and environments of major scientific and educational significance.

Figure M2.6: Sensitive marine environments in Western Australia, as defined by the EPA.

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Data source: Environmental Protection Authority (1993). Presentation: EPA. 

Indicator M13: Pathogens entering the marine environment.

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Bacteria and viruses can enter the marine environment in treated domestic wastewater, sullage from boats or ships and stormwater runoff, particularly from areas where animals live or are active (e.g. bird colonies and exercise areas for dogs and horses). All stormwater outfalls and treated wastewater outfalls are sources of pathogens. A study of wastewater overflows in the Perth metropolitan area between 1991 and 2003 showed that wastewater spills into the marine environment are far less frequent (4% of overflows by frequency or 2% by volume) than into the Swan-Canning River System, drains and basins (Water Corporation, 2004). With the exception of small areas around metropolitan domestic treated wastewater outfalls, the values for primary contact recreation (e.g. swimming) and seafood safety for human consumption (e.g. fishing) are generally achieved throughout the State's coastal waters.

Indicator M14: Other physical and chemical stressors as pollution in the marine environment.

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Other important physical and chemical parameters in the marine environment include sedimentation and turbidity (the effects of which have been discussed in detail elsewhere), salinity level, dissolved oxygen, water temperature, light and sound.

Concerns about the effects of changes in salinity level and potential stratification of Cockburn Sound have been raised with the construction of a desalination plant in Kwinana to supply drinking water to Perth. The plant was completed in late 2006 but there are no current monitoring results to report. Models found the desalination plant was expected to increase the salinity of Cockburn sound by less than 1% and have minimal impact due to tidal movements (Water Corporation, 2005a). However, Spiegel et al. (2005) found that this assessment was simplified and the monitoring results over one year were not predictive of future results. CSIRO found that previous reports on modelling work failed to convey the seriousness and reality of effects of release of hypersaline water into the Sound, e.g. reduced oxygen levels in water and sediment, sustained algal blooms, reduced benthic biodiversity, production of hydrogen sulphide and increase in bacteria (Craig & Wild-Allen, 2005).

Some marine species rely on the moon for navigation and can be adversely impacted by light pollution (e.g. many turtles and birds), especially from coastal industry and port facilities. Whales and dolphins are also known to be sensitive to acoustic pollution (especially as sound waves are transmitted differently in water and air).

Current responses

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State Environmental (Cockburn Sound) Policy: establishes an environmental quality management framework for Cockburn Sound (Government of Western Australia, 2005). The policy empowers the Cockburn Sound Management Council to facilitate and coordinate sustainable management of the Sound through an environmental management plan and to report publicly on the plan's implementation.

Licensing: of all significant contaminant emissions to the environment is regulated by the Department of Environment and Conservation.

Monitoring: The Perth Long Term Ocean Outlet Monitoring program monitors wastewater discharges on the marine environment. Individual port authorities conduct monitoring for spills and pollution. Monitoring data is collected in a central database for ports managed by the Department for Planning and Infrastructure, to improve emergency response and planning. Monitoring of Perth Metropolitan beaches is undertaken by the Department of Health.

Research: Scientific programs are underway in Perth, Jurien Bay Marine Park and the Pilbara to collect baseline data to help develop environmental quality criteria for future management.

Pilbara Environmental Quality Management Framework: The marine and coastal waters of the Pilbara have been identified as a priority region for the implementation of an environmental quality management framework, similar to that undertaken for Cockburn Sound. The Department of Environment and Conservation is conducting a community consultation program to define the marine environmental values and objectives that will underpin the environmental quality management framework for Pilbara marine and coastal waters. The framework will be used to guide environmental impact assessment, regulation and environmental quality management.

Oil spill response: The WestPlan Marine Oil Pollution (MOP) has been developed to prevent, prepare for and respond to oil spills, and to assist in the recovery of an area in State waters after an incident. WestPlan is WA's implementation of the National Plan, and the Department for Planning and Infrastructure is the Hazard Management Agency. Other agencies such as the Departments of Industry and Resources, Environment and Conservation and Fisheries are also involved in contingency and response on a state level.

Kwinana Water Recycling Project: is resulting in the diversion of some industrial wastewater streams from Cockburn Sound to the Sepia Depression outfall at Cape Peron. It is anticipated that this will reduce the load of contaminants entering Cockburn Sound via industrial discharges. The project will change the characteristics of wastewater currently discharged through the Water Corporation's pipeline, as the water will be a mixture of treated wastewater and industrial effluent.

Implications

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Environmental implications of marine contaminants vary significantly. Contaminants may be short-lived or persistent, depending on the nature of the pollutant and the extent of its spread through the environment. Persistent chemicals such as heavy metals and antifouling agents (e.g. TBT) pose the greatest risk to people (through eating seafood) and for marine biodiversity. The environmental repercussions of marine contamination are extremely serious and may vary from subtle ecological changes to widespread death of marine species. Marine contamination is usually a localised problem, but the rapid expansion of WA's economy is likely to result in increased demand for more and busier port facilities and industrial areas, along with further contamination pressures from other sources. The increased pressures of a growing population are likely to result in increased wastewater discharges and potentially increased hypersaline discharges (should desalinisation become a more popular water supply option).

Suggested responses

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6.8 Develop a baseline of the extent of marine contamination for developed areas, including ports.