State of the Environment Report 2007
The marine environment includes both coastal waters (under the jurisdiction of the Western Australian Government) and deeper marine waters to the edge of the Exclusive Economic Zone (under the jurisdiction of the Commonwealth Government). WA's coastal waters cover an area of 117 887 km2, and extends three nautical miles (or 5.5 km) seaward from the high tide mark on the shore. An additional 2 188 647 km2 of marine area is included from the limit of State waters into the Commonwealth administered Exclusive Economic Zone. The State's mainland shoreline stretches 12 889 km from the Timor Sea in the north to the Great Australian Bight in the south. WA has 3747 islands (and an additional 7892 km of coastline around those islands) that also form part of the coastal environment.
Most of WA's marine ecosystems are typified by clear and low nutrient waters, low productivity, and tides that vary between 1 m in the south to over 10 m in the north. Inshore waters along the Mid West, Pilbara and Kimberley generally contain higher sediment levels and are more turbid. The Leeuwin Current flows south along the coast, maintaining relatively high marine temperatures along the west coast, and presents favourable conditions for tropical species in temperature waters. As a result, WA has an exceptionally rich marine biodiversity that is ranked second in the world in terms of its species richness and endemism. Unique marine ecosystems range from extensive mangrove communities in arid Pilbara areas; a coral reef 270 km long and less than six kilometres offshore (Ningaloo Reef); an inverse-estuary with 20 000 km2 of seagrass meadows (Shark Bay); a high latitude coral reef (Abrolhos Islands); and nutrient poor coastal embayments with highly diverse seagrass (central west and south coasts).
While West Australians value marine resources and enjoy living close to the sea, very little about the ecology and biodiversity of the marine environment is well-understood or researched (see 'Biodiversity'). People are generally familiar with large fauna such as whales, dolphins, turtles and fish, and habitats such as coral reefs and seagrasses. However, events such as the collapse and closure of some fisheries (see 'Fisheries'), industrial development, oil spills, coral bleaching, increased ecotourism, increased coastal populations, dredging, international poaching, and instances of coastal waters and seafood contamination have brought a greater awareness of the vulnerability of WA's marine environment.
To protect and conserve the marine environment by:
Environmental values reflect community views and aspirations for the marine environment. They are the particular values or uses of the environment that are important for a healthy ecosystem or for public benefit, welfare, safety or health, and which require protection from the effects of pollution, waste discharges and deposits (ANZECC & ARMCANZ, 1994). Some examples of environmental values include fishing, recreation, conservation, and commercial operations. WA uses the State Water Quality Management Strategy No. 6 to formally assign environmental values and enhance policy and management outcomes (Government of Western Australia, 2002).
Environmental values have been formally ascribed to Pilbara marine waters (for State waters between Exmouth and Cape Keraudren east of Port Hedland) and to Perth Coastal Waters and Cockburn Sound around Perth (Figure M0.1). The State Government is implementing a marine protected area system that also establishes ecological and recreational values via the New Horizons Policy (Government of Western Australia, 1998b) (Figure M0.1). When these two methods of defining environmental values are added together, about 33% of State coastal waters have some defined environmental values. However this figure drops to 1.7% if the Exclusive Economic Zone (Table M0.1) is included.
![Figure M0.1: Areas for which values have been defined in Western Australia. [Data source: Environmental Protection Authority (2000) - Perth Coastal Waters; Department of Environment (2006) - Pilbara Coastal Waters as endorsed by the EPA in 2006; Department of Conservation and Land Management [ver. 2006] - CALM gazetted marine areas and Commonwealth protected areas. Analysis: EPA. Presentation: EPA.]](/site/files/images/Figure-M0.1_Large.jpg)
Cockburn Sound is the only area in WA that has both defined environmental values and is regularly monitored for compliance (0.1% of State waters). Monitoring of Cockburn Sound is undertaken to determine if environmental values are being protected. The Cockburn Sound Management Council publicly reports the findings each year (Cockburn Sound Management Council, 2006) and has prepared State of Cockburn Sound reports in 2005 and 2006 (Cockburn Sound Management Council, 2005; Cockburn Sound Management Council, 2006b).
Monitoring associated with environmental values set by the EPA also occurs at several locations associated with development proposals put through the environmental impact assessment process. Environmental monitoring for some parameters also occurs in marine protected areas; however, monitoring data are not collated or publicly available.
Monitoring of the condition of the marine environment in near-shore marine waters in WA is extremely limited, and is mostly of Cockburn Sound and Warnbro Sound (Shoalwater Islands Marine Park). Overall there appears to have been no significant change in the overall health of Cockburn Sound since monitoring programs began in 2000 (Cockburn Sound Management Council, 2005). However, recent data (2004-06) indicates that further investigation and action is required in several areas (seagrass shoot density in Mangles Bay; chlorophyll a, light attenuation and tributyltin in Jervoise Bay; bacterial contamination at several beaches; Table M2.1). Management action is also required to address elevated summer levels of faecal contamination at Rockingham Beach (Cockburn Sound Management Council, 2006).
Monitoring data elsewhere are extremely limited. In some places, seagrass monitoring is used as a sensitive measure of changes occurring in the marine environment. Posidonia sp. seagrasses are extremely sensitive to changes in environmental conditions and represent a major component of sheltered, lagoonal marine ecosystems in the South West. Seagrass health condition has been monitored in Cockburn Sound since the 1960s, with a severe decline in meadow area occurring in recent decades (See 'Degradation of marine environments').
In more open near-shore marine ecosystems of the South West, Amphibolis sp. seagrasses are dominant and used as indicators of a reduction in water clarity (e.g. due to sediments or nutrient enrichment) or sedimentation. Edith Cowan University, CSIRO and the Geraldton Port Authority have been conducting studies of Amphibolis sp. seagrass health condition in the Jurien Bay area, a relatively 'pristine' marine area, to measure the response of these plants to experimentally imposed stress, identify indicators of health condition and to investigate indicators of resilience and recovery. Similar studies have also been conducted in the Geraldton area - an area with a history of environmental stress (sedimentation and light deprivation) due to dredging.
Monitoring data collected by the Water Corporation on percentage cover of various algal types in the Marmion Lagoon show some promise in terms of developing indicators of algal-dominated reef condition, but further development is required for these indicators to be robust.
There are far greater gaps in our knowledge of tropical marine communities, their response to stress, and indicators of their health condition than is the case for temperate marine communities. Industry in Dampier has conducted some basic coral condition studies in assessing coral condition and recovery.
Eighteen actions were identified for the 'Marine' theme in response to the 1998 State of the Environment report (Government of Western Australia, 1998a). Of these, 78% remain incomplete, 11% have been completed but not evaluated, and 11% have been completed and evaluated. The large number of incomplete actions reflects the lack of attention to the marine environment. Confounding factors include the sheer size of the State's marine environment, its remoteness from major settlements, and the high costs of research and monitoring. It is also extremely difficult to evaluate the effectiveness of completed actions when there is a lack of adequate data. Initiatives of the National Action Plan for Salinity and Water Quality, and the Natural Heritage Trust programs may help improve our understanding of the marine environment.
6.1 Implement the State Water Quality Management Strategy No. 6: for Perth coastal waters, the Pilbara, Mid West and Kimberley near shore waters as a matter of priority within the next five years.
6.2 Establish a baseline of condition of the marine environment and develop a consistent monitoring network in the priority areas.
6.3 Improve the recognition, understanding and management of cumulative impacts on the environment and modify planning, environmental impact assessment and development processes where appropriate.
