SoE 2009 > Water > 6.5 Marine waters and ecosystems

6.5 Marine waters and ecosystems

The ecosystem health of the New South Wales marine environment is good overall as is recreational water quality, particularly in dry years.

The condition of marine waters and ecosystems is also considered to be good. While instances of contamination from stormwater runoff and sewage overflows and outfall emissions do exist, the impacts tend to be localised and of limited effect.

The listing of some marine species as threatened indicates that external pressures are having an impact on some species and, by implication, ecosystems.

Measures taken to address pressures include continued development of the marine protected areas system through implementation of zoning plans for the Batemans and Port Stephens–Great Lakes marine parks and improved management of fisheries, critical habitats and stormwater runoff.

NSW indicators

Notes: Terms and symbols used above are defined in About SoE 2009 at the front of the report.

Introduction

NSW marine waters have high biodiversity because of the wide range of oceanic, shoreline and estuarine habitats they contain and the strong influence of both subtropical and temperate currents. These varied environments provide many important ecosystem services, including preventing coastal and seabed erosion, maintaining coastal water quality, and acting as both a recreational and tourism resource and as critical habitats for fish and other marine life.

The state's marine jurisdiction extends three nautical miles off the 1900-kilometre NSW coast. Marine waters adjacent to urban and industrial areas are more susceptible to the effects of pollution from urban runoff, stormwater and sewage discharge on water quality and marine ecosystems, such as coral reefs in subtropical regions of the state and rocky intertidal zones and macroalgal-dominated reefs in temperate areas.

Status and trends

Despite the development of indicators to measure progress in meeting Priority E4 in State Plan 2006: A new direction for NSW (NSW Government 2006), the information available to assess the status of the marine environment is still quite limited. Information on marine protected areas and rocky reef biota (fish stocks) are addressed in more detail in Biodiversity 7.3 and Biodiversity 7.6, respectively.

Water quality

Marine waters are generally considered to be in good condition as currents, wave action and tides are usually able to dilute pollution, making them less vulnerable to degradation. Nonetheless, even in well-flushed systems, pollutants can bind to organic material and sediments and accumulate in filter feeders and higher order predators with adverse effects on ecosystems and human health.

Sedimentation and local pollution from sewage and stormwater overflows associated with urban development can have an impact on water quality. Marine Water Quality Objectives for NSW Ocean Waters (DEC 2005) simplify and streamline the consideration of water quality in coastal planning and management. The objectives reflect the environmental values the community places on marine waters and its uses. Together with the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ 2000), they identify the steps required to protect these values and uses, now and in the future.

Monitoring under several programs provides information on NSW marine and estuarine water quality. The Beachwatch and Harbourwatch programs monitor 131 beaches in the Sydney, Illawarra and Hunter regions. Coastal councils also monitor beaches in their area under the Beachwatch Partnership Program, with the number of beaches varying from year to year depending on council resources and priorities: 148 beaches in 12 local council areas were included in the program during the summer of 2007–08 (Map 6.4).

Both programs provide the community with information on the risks of sewage and stormwater pollution at beaches. Two bacterial indicators – faecal coliforms (also called thermotolerant coliforms) and enterococci – are used to assess recreational water quality, in accordance with the National Health and Medical Research Council swimming guidelines (NHMRC 1990).

Although monitoring water for recreational use does not provide an assessment of overall water quality and waterway health, changes over time enable the effectiveness of stormwater and wastewater management to be assessed.

Rainfall is the principal determinant of pollution in NSW waterways as it causes stormwater discharges and sewerage overflows. Summer 2007–08 was the wettest in 24 years in coastal NSW and many swimming locations failed to comply with the swimming water quality guidelines more than 90% of the time (Map 6.4). Estuarine swimming areas were the worst affected due to the lower dilution and tidal flushing capacities of these waterways.

Detailed results for each of the 131 sites monitored in the Sydney, Hunter and Illawarra regions are available in the Beachwatch and Harbourwatch State of the Beaches reports (DECC 2008b). Detailed results for sites monitored in regional coastal areas in partnership with local councils can be found in the Beachwatch Partnership Program State of the Beaches reports (DECC 2008c).

Map 6.4: Compliance with swimming water quality guidelines at beach and estuary monitoring sites, 2007–08 summer swimming season

Less than a decade ago wet weather had a much greater impact on swimming locations in Sydney (Figure 6.6). During summer 1998–99, a period with almost as much rainfall as summer 2007–08, only 20% of Sydney's ocean beaches and 4% of Sydney's estuarine swimming areas complied more than 90% of the time. Improvements in stormwater and wastewater management through projects such as the Northside Storage Tunnel, upgrades to sewage treatment plants, the Urban Stormwater Program and licensing of sewerage overflows have resulted in significant reductions in pollution levels at swimming locations in the Sydney region.

While significant progress has been achieved in controlling point sources of pollution and certain diffuse sources such as stormwater, diffuse source water pollution remains one of the biggest challenges in improving water quality for government, industry and the community (DECC 2009b).

Figure 6.6: Sydney, Hunter and Illawarra beach and estuary monitoring sites complying with swimming water quality guidelines at least 90% of the time, 1998–99 to 2007–08

Source: DECC data 2008

Notes: Data does not include results from the Beachwatch Partnership Program.

Algal blooms

While algal blooms occur naturally in the marine environment, some species, such as dinoflagellates, can be harmful to aquatic organisms (DEH 2005). Less harmful blooms can cause odours or discolouration, such as the red tides that affect visual amenity. The nutrients which promote the growth of algal blooms come from ocean upwellings and estuarine outputs, both of which are closely related to El Niño weather cycles. Ocean outfalls, runoff and stormwater discharge may also boost local nutrient supplies, particularly in waters close to urban areas.

Satellite data since 1998 is now being used to derive information on the occurrence of marine algal blooms in NSW waters. This data allows for a broader scale and more realistic assessment of the frequency and type of blooms and improves on previous reporting on algal events that was largely based on sightings and the results of water quality testing in affected areas.

An algal bloom is considered to have occurred when the concentration of chlorophyll-a in the water is equal to or exceeds the ANZECC trigger value of 1 microgram per litre (1 µg/L) (ANZECC & ARMCANZ 2000). Using preliminary data averaged across the state, Figure 6.7 shows that the frequency of algal blooms at 16 sites covering the length of the NSW coast was stable between 1998 and 2007. The southern part of the state generally had fewer days where trigger levels were reached. Higher rates of exceedence at some sites may be caused by natural upwellings while others may be influenced by river discharges. Data will continue to be analysed to identify algal bloom events outside the natural range.

Figure 6.7: Sampling days when chlorophyll-a levels indicate an algal bloom, 1998–2007

Source: DECCW data 2009

Notes: An algal bloom is indicated when the concentration of chlorophyll-a in the water is greater than or equal to the ANZECC trigger value of 1 µg/L.

Rocky reef biota

The abundance of abalone, lobster, purple sea urchins and reef fish in NSW marine waters is indicative of the health of rocky reef ecosystems. The status of key fish stocks and the impacts of aquatic species harvesting are more thoroughly addressed in Biodiversity 7.6.

Commercial harvesting of abalone takes place on the south coast of NSW, primarily from Jervis Bay to the Victorian border. Harvesting is limited to 'shareholders' in each fishery with the take based on an allocation per share, as determined by the Total Allowable Catch Committee each year. However as most abalone is found close to the shore on rocky reefs and shelfs, it is also susceptible to illegal harvesting.

Comprehensive information on the abundance and distribution of abalone is available from the independent assessments of fisheries stock which are used to determine the total allowable catch for the fishery (DPI 2008a). The distribution and abundance of abalone in NSW waters is rated as poor. Between 1998 and 2007–08, the abalone take fell almost two-thirds, as indicated in Figure 6.8. This can be attributed to the limited range of the species, the effects of the parasitic disease Perkinsus, and harvesting, both illegal and regulated. Loss of habitat to the highly invasive and adaptable purple urchin has also been a significant factor.

Eastern rock lobsters are harvested in marine waters throughout NSW with commercial fishing pressure stable over the past 10 years and little change in the total allocated catch levels. However the commercial catch has increased slightly over the past four fishing periods, as shown in Figure 6.8 (DPI 2008b). Recreational fishers also target lobsters by hand or using a single pot, but they are limited to two lobsters per person. Recreational harvest levels of lobsters are unknown, but an overall allowance of 25.8 tonnes for recreational fishing in NSW is used when determining the total allocated catch in the commercial fishery to help ensure sustainable levels of harvest (DPI 2008b). Based on information from independent assessments of fisheries stock where the number of small lobsters in water less than 10 m deep was counted, the change in abundance of lobsters over this period is rated as fair.

Figure 6.8: NSW commercial eastern rock lobster and abalone fisheries catch, 1998–99 to 2007–08

Source: DII data 2009

Notes: Statistics for abalone catch switched from calendar year to financial year fishing periods following the 2002 fishing period, making 2003–04 an 18-month fishing period. The figure for 2003 includes the data for the entire 2003 financial year, with 6 months of this data replicated in the 2003–04 figures.

Twenty-four species regularly caught in demersal fish traps set on rocky reefs in the NSW Ocean Trap and Line Fishery were assessed for abundance based on commercial catch records. Reef fish catches in the fishery have remained stable between 1998 and 2008, albeit with an increase in catch in 2007–08 due largely to more leatherjackets being taken.

The results of underwater surveys of urchin abundance at a number of locations along the NSW coast have been published by several researchers in technical reports and scientific papers (Andrew & Underwood 1989; Andrew et al. 1998; The Ecology Lab 2007). No data is available for northern NSW as sea urchins are only harvested commercially off the south coast as part of the Sea Urchin and Turban Shell restricted fishery. Estimates of densities of sea urchins have been combined with estimates of the area of available habitat to calculate their likely biomass. In most cases, because of the limited commercial harvesting to date, urchin biomass is probably close to unexploited levels (Worthington & Blount 2003). There is no evidence of a change in the abundance of sea urchins over the past 10 years, based on population estimates, and commercial stocks are considered to be stable.

Marine protected areas

Marine protected areas, including marine parks and aquatic reserves, aim to conserve biodiversity by protecting representative samples of habitats, thus removing or reducing a range of pressures on the marine environment, particularly from certain fishing activities. The length of NSW coastline included in marine protected areas has increased since 2000, notably in 2006 with the declaration of two new marine parks in the Batemans Bay and Port Stephens–Great Lakes regions. The marine parks system now covers approximately 345,000 hectares or around 34% of the state's waters.

Multiple-use zoning within marine parks restricts activities in line with conservation and management priorities while permitting reasonable uses and providing protection for the diverse marine ecosystems found within park boundaries (NSW Government 2001). There are four types of zones: sanctuary, habitat protection, special purpose and general use. The role of marine protected areas and the areas under each zoning category are discussed further in Biodiversity 7.3.

Threatened species

Currently 36 marine species are listed as extinct or under threat by the Fisheries Management Act 1994 and Threatened Species Conservation Act 1995. While no additional species have been listed since 2006, the status of the green sawfish has changed from endangered to extinct.

Approximately half of the listings are marine seabirds (19), the majority of which are classed as vulnerable. Marine mammals (7), reptiles (3), sharks and rays (3), bony fish (2) and macroalgae (2) make up the remaining listings. Information on marine species is not generally as good as for terrestrial species. This lack of knowledge is highlighted by the relatively small number of species listed, suggesting that with better information the number could grow, as pressures increase in the marine environment. Higher order species, such as sharks, tuna and whales, remain the most vulnerable to external pressures.

Seven key threatening processes are listed under the Fisheries Management Act. Three relate to the marine environment: 'Introduction of non-indigenous fish and marine vegetation to the coastal waters of NSW', 'The current shark meshing program in NSW waters' and 'Hook and line fishing in areas important for the survival of threatened fish species'. The shark meshing program is also listed under the Threatened Species Conservation Act along with 'Entanglement in or ingestion of anthropogenic debris in marine and estuarine environments'. The Fisheries Management (General) Regulation 2002 also lists 13 protected species, including the entire zoological families of Syngnathidae, Solenostomidae and Pegasidae and five species protected from commercial fishing, including southern bluefin tuna.

Pressures

Pollution and habitat disturbance

Pollutants have a range of impacts on biodiversity in the marine environment (NBSRTG 2009) by:

• degrading habitats
• changing the distribution and density of species
• increasing the levels of contaminants in some species (which have impacts throughout the food chain)
• reducing the relative abundance of top-order predators.

Most of the pollution in coastal and marine waters comes from land-based activities. The main pressures arise from human settlement, population growth and urbanisation in the coastal zones adjacent to marine waters and include sewage and stormwater discharges, estuarine outputs and marine debris. This highlights the need for improved sewage and stormwater management as coastal populations expand.

Sediments, nutrients, pollutants and freshwater from rivers, creeks and coastal lagoons discharge through estuaries into the ocean. Around 135 NSW estuaries discharge into marine waters, contributing about 837,000 tonnes of sediment, 2400 t of phosphorus and 23,000 t of nitrogen annually (see also Water 6.6). Excess sediment, phosphorus and nitrogen in the marine environment, usually delivered during flooding, can have significant impacts on both marine water quality and habitats, including seagrass beds and reefs.

Figure 6.9 shows licensed discharges of total suspended solids, total phosphorus and total nitrogen to open marine waters and the number of licences for each pollutant. Discharges to the marine environment of the nutrients phosphorus and nitrogen have been relatively stable since 2001–02. These are largely the outputs of sewage treatment plants. Discharges of suspended solids into marine waters increased in 2006–07 and 2007–08 primarily due to the increase in average yearly rainfall in coastal areas in those years following a dry period (SWC 2008). High levels of iron, steel and coke production also contribute to discharges of suspended solids into marine waters.

Compared with estimates of total estuarine discharges through modelling, licensed discharges of suspended solids contribute less than 7% of the overall total to the marine environment. Licensed discharges of phosphorus and nitrogen are predominately restricted to waters off Sydney and Wollongong. Diffuse source discharges to the marine environment are more significant than point source discharges in most coastal waters, excluding the waters off Sydney, where ocean outfalls contribute the majority of nutrients to marine waters.

Figure 6.9: Licences and licensed discharges to NSW open marine waters, 2001–02 to 2007–08

Source: DECCW data 2009

Notes: Data covers all licensees discharging into the marine environment as part of DECCW's Load-based Licensing Scheme.
Data for 2007–08 incomplete.

Some marine pollution is not from land-based sources. This generally includes material from shipping-related incidents, such as oil or chemical spills, ballast water discharges and release of sewage from vessels. Many of these incidents are minor and usually occur around ports and harbours. No major pollution incidents have been recorded in NSW marine waters over the last three years.

In addition to the listing of marine debris as a key threatening process in NSW (see Status and trends above), the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 lists: 'Injury and fatality to vertebrate marine life caused by ingestion of, or entanglement in, harmful marine debris'. Harmful marine debris consists of garbage washed or blown from land into the sea, fishing gear abandoned by recreational and commercial fishers, and solid non-biodegradable floating materials (such as plastics) disposed of by ships at sea (DEH 2003). Entanglement and ingestion of debris, such as plastic bags, cigarette butts, lolly wrappers and discarded fishing gear, can be fatal to marine species, particularly listed threatened species such as seabirds, turtles and whales. Grey nurse sharks in NSW waters have also been found to have fishing hooks snared in both their mouths and stomachs, with the potential to cause death. Recovery in the populations of threatened species such as the humpback whales is also likely to result in a greater number of entanglements.

Demersal trawl nets used in the NSW Ocean Trawl Fishery are dragged along the seabed in suitable fishing areas (DPI 2004). Gear restrictions, area closures and a reduction in licence holders in the fishery have helped reduce the impacts of trawling on marine habitats. The mapping of habitat and trawl grounds presently under way should provide for improved management of trawling into the future.

Fishing and hunting

Commercial and recreational fishing occurs in the marine waters of NSW and is discussed in detail in Biodiversity 7.6. Currently, commercial fish landings and overall numbers of recreational anglers are relatively stable in NSW, although the number of commercial catch returns, which can be used as an indicator of fishing 'effort', has been steadily decreasing over the last 10 years. The decrease in the number of submitted catch returns indicates an increase in the average catch per return.

The number of commercial fishing licences has decreased over recent years. This is the result of licence buybacks for marine parks, the introduction of 'recreational fishing havens', commercial closures in Sydney Harbour and other areas, as well as a reduction of effort in Commonwealth fisheries that would have had an impact on dual Commonwealth and NSW licence holders. High fuel prices and low product prices have also affected fishing effort in NSW commercial fisheries.

Invasive species

Marine invasive species are plants or animals, often introduced from overseas, that can have a significant impact on marine industries and the environment, by taking over habitats and directly competing with native species for food. Marine pests include mussels, crabs, seaweeds, sea stars and other marine species. Some marine pests are native to other regions of Australia but have been transported into NSW through shipping or the aquarium trade (see also Biodiversity 7.4).

Climate change

The potential impacts of climate change on the marine environment are not well known or understood at this time. However, predicted increases in sea surface temperature and ocean acidification are likely to have the most impact on the marine environment. Climate modelling predicts that waters around Australia will warm by 1–2°C by 2070 with the greatest warming expected to occur in the waters off south-eastern Australia and the Tasman Sea, largely due to a strengthening of the East Australia Current (Hobday et al. 2006).

Warmer ocean temperatures are likely to affect the distribution and reproductive patterns of marine species, while ocean acidification may have an impact on the growth and function of calcitic organisms such as molluscs and corals (Fabry et al. 2008). The long-term effects of acidification on marine species and associated impacts on marine food webs are still not known (Guinotte & Fabry 2008).

Changes to the East Australia Current, regional wind patterns and mixed layer depths may lead to upwellings with an impact on the associated primary productivity (Hobday et al. 2006). Rises in sea level from thermal expansion and glacial melt and more frequent storms will result in increased shoreline erosion and inundation of low-lying areas of coastal NSW (see also Climate Change 2.3).

Responses

State Plan 2006

State Plan 2006: A new direction for NSW (NSW Government 2006) has the following target under Priority E4: 'By 2015 there is no decline in the condition of marine waters and ecosystems'. A Monitoring, Evaluation and Reporting (MER) strategy is being implemented to monitor progress towards all E4 targets.

A review of State Plan 2006 commenced in August 2009 and this may adjust some of the plan's priorities and targets.

Improvements in the condition of marine waters and ecosystems are also directly linked to improvements in NSW estuaries and coastal lakes. The target for these is described in Water 6.6.

Legislation

The Fisheries Management Act 1994 and supporting regulations provides for conservation of fish stocks, key fish habitats, threatened species, populations and ecological communities of fish and marine vegetation. This includes the regulation and management of recreational and commercial fisheries, including licence, gear and species restrictions, application of commercial catch quotas for some species, recreational bag limits and habitat protection through the establishment of aquatic reserves and closures (see also Biodiversity 7.6).

The Marine Pollution Act 1987 aims to protect the sea and certain waters from pollution by oil and other noxious substances discharged from ships. The Protection of the Environment Operations Act 1997 provides for the protection of the environment through mechanisms such as protection of the environment policies and licensing, including the regulation of point source discharges into the marine environment.

The Marine Parks Act 1997 aims to conserve marine biological diversity, habitats and ecological processes in marine parks (see also Biodiversity 7.3). The Port Stephens–Great Lakes Marine Park zoning plan, which came into effect in April 2007, designated 17,766 hectares of sanctuary zone in the marine park. The Batemans Marine Park zoning plan commenced in June 2007 and declared 16,169 ha of the park sanctuary zone.

Marine park zoning

Five-yearly reviews of the current zoning plans for Jervis Bay and Solitary Islands marine parks commenced in 2008 to determine whether the plans remain appropriate for meeting the objects of the Marine Parks Act. Following finalisation of the reviews, the Marine Parks Authority will provide reports for the consideration of the Minister for Climate Change and the Environment and the Minister for Primary Industries.

Future directions

While NSW marine waters and ecosystems are currently considered to be in good condition, there is significant potential for this to change in the future with growing pressures from resource extraction to improve food or fuel security and the impacts of climate change.

The process under the Monitoring, Evaluation and Reporting Strategy for measuring achievement of the State Plan target for no decline in the condition of marine waters and ecosystems provides an excellent baseline for future reporting on this issue. However, outside commercial fishing and sea surface temperature records, little ongoing monitoring has occurred to determine the impacts of the key pressures on the marine environment. Improved information on marine water quality, species diversity and abundance, and marine habitats through remote sensing, aerial helicopter surveys and underwater video surveys will also improve our understanding of the marine environment.

The Integrated Marine Observing System has established ongoing physical monitoring of temperature, salinity, stratification and currents, chemical monitoring of nutrients and acidification, and biological monitoring of plankton at National Reference Stations around Australia, including off Port Hacking (Sydney). This is building on historical data collected by CSIRO.

A mix of pollution control, natural resource management and conservation measures will continue to be required in order to maintain the condition of marine waters and ecosystems. This mix of approaches is likely to evolve in response to our understanding of how best to adapt to the changing marine environment.