4.5 Marine waters and ecosystems
The overall health of the New South Wales marine environment and ecosystems is considered to be good, as is recreational water quality.
While instances of contamination from stormwater runoff, sewage overflows and outfall emissions do occur, their impacts tend to be localised and of limited effect. Beach suitability, based on levels of stormwater and sewage contamination, is rated as good or very good at 83% of all beaches in NSW and at over 99% of ocean beaches. It is lower at around 60% of beaches in the enclosed waters of coastal lakes, estuaries and rivers.
Forty-one species found in NSW coastal waters are listed as threatened or extinct, around half of them ocean birds and most of the rest higher order species, such as marine mammals and large fish.
The listing of some marine species as threatened indicates that external pressures are having an impact on some species and, by implication, on ecosystems.
The main pressures on marine species include destruction of vital habitats, chemical contamination, overfishing, and entanglement in disused fishing gear and refuse, such as plastic bags and ring pulls.
Indicator and status
Percentage of beaches with beach suitability grades for swimming of good or better
Frequency of algal blooms
Distribution of rocky reef-covering biota
Notes: Terms and symbols used above are defined in About SoE 2012 at the front of the report.
NSW marine waters contain high levels of biodiversity because of their wide range of oceanic, shoreline and estuarine habitats 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 critical habitats for fish and other marine life. The community values and uses provided by the NSW marine environment include healthy aquatic ecosystems, recreation, visual amenity and aquatic food production.
The state's marine jurisdiction extends three nautical miles (5.6 kilometres) off the 1900-kilometre NSW coast. Marine waters and ecosystems adjacent to urban and industrial areas are more susceptible to the effects of pollution from urban runoff, stormwater and sewage discharge.
Status and trends
To meet the requirements of the NSW Natural Resources Monitoring, Evaluation and Reporting Strategy (DECCW 2010d), indicators have been developed to assess the status of the marine environment but information is still quite limited. Information on marine protected areas is addressed in more detail in Biodiversity 5.3.
Marine waters are generally considered to be in good condition as currents, wave action and tides are usually able to dilute pollution, making marine systems 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. These objectives reflect the environmental values the community places on marine waters and their uses. Together with the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ 2000), the objectives identify the steps required to protect these values and uses, now and in the future.
Recreational water quality
Information on the recreational water quality in marine and estuarine waters is provided by the Beachwatch programs. The Beachwatch program conducted by the NSW Office of Environment and Heritage (OEH) monitors 127 swimming sites in the Sydney, Hunter and Illawarra regions, while coastal councils also monitor beaches in their areas under the Beachwatch Partnership Program. In the 2010–11 swimming season, 14 local councils participated in this program, monitoring 132 swimming sites, including beaches, coastal lagoons, tidal pools, estuaries and rivers.
Both programs provide information on the risks of sewage and stormwater pollution at beaches. Swimming sites are assigned a beach suitability grade ranging from 'very good' to 'very poor' based on a risk assessment of pollution sources affecting the beach and the level of the bacterial indicator enterococci, in accordance with the Guidelines for Managing Risks in Recreational Water (NHMRC 2008). Map 4.7 shows the beach suitability grades at NSW sites in 2010–11.
This system for grading beaches is based on new guidelines that were adopted in NSW in May 2009, replacing the earlier 1990 guidelines. 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.
In 2010–11, 83% of the 259 swimming locations monitored were graded as 'very good' or 'good'. However, there are differences between swimming sites with over 99% of all ocean beaches achieving ratings of very good or good, compared with around 60% of sites in coastal lagoons, estuaries and rivers due to the lower dilution and tidal flushing capacities of these waterways (Map 4.7). Overall, this is a strong result which was achieved despite the NSW coast experiencing its wettest spring and fifth-wettest summer on record. High rainfall causing stormwater discharges and sewerage overflows is recognised as the principal factor in the contamination of water at NSW beaches. Detailed results for all swimming sites monitored in NSW can be found in the State of the Beaches reports (OEH 2011b).
Map 4.7: Beach suitability grades at swimming sites in NSW, 2010–11
Figure 4.9 shows the proportion of sites with low levels of faecal contamination over the past 13 years at ocean and estuarine beaches in the greater Sydney area. Less than a decade ago wet weather had a much greater impact on swimming locations in Sydney. During 1998–99, when almost as much rain fell as in 2007–08 and 2010–11, only 35% of Sydney's ocean beaches and 2% of Sydney's estuarine swimming areas recorded low levels of faecal contamination (Microbial Assessment Categories A and B defined by NHMRC 2008). These results are based on the measure used prior to 2009 and they are therefore not directly comparable to the outcomes displayed in Map 4.7. Improvements in stormwater and wastewater management over the past decade have resulted in significant reductions in bacterial levels at swimming locations in the Sydney region.
Figure 4.9: Sydney, Hunter and Illawarra beach and estuary monitoring sites graded as having low levels of faecal contamination, 1998–99 to 2010–11
Source: OEH data 2011
Notes: Beach suitability grades are only available from 2009–10 onwards. To report on trends through time, Microbial Assessment Categories have been back-calculated using historical enterococci data. Microbial Assessment Categories A and B indicate generally low levels of faecal contamination and are required for a swimming site to achieve a 'very good' or 'good' beach suitability grade.
Data from the Beachwatch Partnership Program is not included.
While significant progress has been achieved in controlling point sources of pollution and some 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 2009).
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, which have a close association with El Niño weather cycles, and from the outflows of estuaries. Ocean outfalls, rainfall runoff and stormwater discharges may also boost local nutrient levels in waters close to urban areas.
Satellite data from 1998 onwards is being used to derive information on the occurrence of marine algal blooms in NSW waters. This data allows for a broad and systematic assessment of the frequency and type of blooms and improves on the largely reactive reporting of the past which relied on testing of water quality in affected areas after algal blooms were sighted. Following the failure of the SeaWiFS satellite initially used, it has been necessary to transition to the MODIS Aqua satellite to monitor blooms. As there are some differences between the characteristics of the two sensors, the results recorded are similar but not directly equivalent as shown in Figure 4.10.
Figure 4.10: Sampling days when chlorophyll-a levels indicate an algal bloom, 1998–2011
Source: OEH data 2012
Notes: An algal bloom is indicated when the water concentration of chlorophyll-a is greater than or equal to the ANZECC trigger value of 1 µg/L.
Figure 4.10 shows the frequency of algal blooms at 17 sites covering the length of the NSW coast between 1998 and 2011. An algal bloom is considered to have occurred when the concentration of chlorophyll-a in the water is equal to or exceeds a trigger value of 1 microgram per litre (1 µg/L) (ANZECC & ARMCANZ 2000). Overall, the frequency of algal blooms appears to be relatively stable, allowing for some differences in the characteristics of the two satellite sensors. Trigger levels were generally reached on fewer days in the southern part of the state. Higher rates of exceedence at some sites may be caused by natural upwellings, while others may be influenced by river discharges. Further analysis is probably needed to identify algal blooms outside their natural range with confidence.
Rocky reef biota
Previous SoE reports relied on commercial harvest data to report on the condition of rocky reef biota. Since 2009, a statewide program has been sampling the dominant biota covering near-shore rocky reefs. Each year, approximately 40 sites associated with a range of nearby human population levels are sampled. Over time, it will be possible to assess the impact of anthropogenic (human-derived) disturbances on rocky reef biota, as an indicator of marine condition. With only two years of monitoring, the data collected so far only allows an estimate of condition and not trend.
The sampling of near-shore rocky reefs indicates that there is considerable variation in covering biota in permanently submerged (subtidal) habitats along the NSW coast. However, there appears to be no significant association between human population level and either condition or patterns of change in condition. The indicators suggest that subtidal habitats are in similar condition throughout NSW.
Similar surveys of periodically exposed (intertidal) rocky shore habitats where specific habitat categories can be distinguished indicate that various species may be responding in different ways to human disturbances. For example, the green seaweed, Caulerpa filiformis, is significantly more abundant when located near large human populations than smaller ones. This pattern was consistent in 2009 and 2010 (Figure 4.11). For the smaller brown seaweed, Hormosira banksii, this pattern appears to be reversed (Figure 4.11). Increased disturbance (such as elevated levels of nutrients) could favour the growth of this green seaweed, while more human activity (such as an increase in trampling) could adversely affect the brown variety. Other species show no clear patterns associated with population level.
Figure 4.11: Changes in biota covering rocky reefs
Source: NSW Department of Trade and Investment, Regional Infrastructure and Services data 2012
It had also been predicted that fewer cunjevoi (Pyura stolonifera) would be associated with large human populations, since fishers use cunjevoi for bait, but this pattern was not observed in the surveys undertaken (Figure 4.11).
While there are some indications that certain intertidal species may be affected by human activities, at this stage there is no strong overall association between the rocky reef biota sampled and human population levels.
Information on the status of marine species is not generally as good as that for terrestrial species. However 41 marine species and one population are currently listed as extinct or under threat by the Fisheries Management Act 1994 (FM Act) and Threatened Species Conservation Act 1995 (TSC Act).
Around half of the listings are marine seabirds (19 species), the majority of which are classed as vulnerable. Marine mammals (7 species), fish (6), reptiles (3), marine invertebrates (4), macroalgae (2) and one marine vegetation population make up the remaining listings. The four invertebrates were added over the past three years and two – Haswell's caprellid (Metaprotella haswelliana) and the marine worm, Hadrachaeta aspeta – are presumed extinct.
As information improves, more species may be recognised as being extinct or under threat than are currently known and the number of species listed may also grow as pressures on the marine environment increase. Higher order species, such as sharks, tuna and whales, remain the most vulnerable to external pressures.
Eight key threatening processes are listed under the FM Act. Four 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
- Hook and line fishing in areas important for the survival of threatened fish species
- Human-caused climate change.
Climate change and shark meshing are also listed as threats under the TSC Act along with 'Entanglement in or ingestion of anthropogenic debris in marine and estuarine environments' (see Biodiversity 5.1).
The Fisheries Management (General) Regulation 2010 lists seven protected marine or estuarine species, the entire zoological families of seahorses and pipefish (Syngnathidae), ghostpipefish (Solenostomidae) and seamoths (Pegasidae), and four marine or estuarine species protected from commercial fishing, including southern bluefin tuna.
Marine protected areas
Marine protected areas, which include six marine parks and 12 aquatic reserves, aim to conserve biodiversity by protecting representative habitats and reducing pressures on the marine environment, particularly from certain fishing activities. Marine parks and aquatic reserves cover approximately 347,000 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 use 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 5.3.
The report from an independent scientific audit of marine parks in NSW, undertaken at the request of the NSW Government, was released in February 2012 (Beeton et al. 2012) with the public invited to comment until 30 June 2012.
Pollutants have a range of impacts on biodiversity in the marine environment (NBSRTG 2009) including:
- degrading habitats
- changing the distribution and density of species
- increasing the levels of contaminants in some species (which can accumulate up 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, diffuse sources of pollution (such as runoff from agricultural land), outflows from estuaries and marine debris.
Sediments, nutrients and other pollutants in freshwater from rivers, creeks and coastal lagoons are discharged into the ocean through estuaries. Modelling indicates that each year 135 NSW estuaries discharge an average 23,000 tonnes of nitrogen, 2400 tonnes of phosphorus and around 835,000 tonnes of sediment into marine waters (Roper et al. 2011). Excess sediments, phosphorus and nitrogen in the marine environment, usually delivered by flooding, can have significant impacts on marine water quality and habitats, including seagrass beds and reefs.
Figure 4.12: Licensed discharges to NSW open marine waters and estuaries, 2000–01 to 2009–10
Source: Environment Protection Authority data 2012
Notes: Data covers all licensees discharging into the marine environment under the Load-based Licensing Scheme.
Figure 4.12 shows licensed discharges of total nitrogen, total phosphorus and total suspended solids to open marine waters and estuaries. Nitrogen and phosphorus discharges to the marine environment have been relatively stable over the period shown. 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.
On average, licensed discharges of suspended solids to the marine environment represent less than 7% of the overall load of total suspended solids to the marine environment. Licensed discharges of nitrogen and phosphorus are predominantly 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.
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 sewage released 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.
Refuse and habitat disturbance
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' as a key threatening process. 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 humpback whales, is likely to result in a greater number of accidental 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.
Commercial and recreational fishing occurs in the marine waters of NSW. Commercial fish landings and overall numbers of recreational anglers are currently 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 or to restructure fisheries, 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.
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 5.4).
The potential impacts of climate change on the marine environment are not well understood but predicted increases in sea surface temperature and ocean acidification (Guinotte & Fabry 2008) are likely to have the most significant impacts.
Sea surface temperature and salinity
Over the past 40 years, average sea surface temperatures in NSW coastal waters have increased by 0.5°C in the north of the state and up to 0.8°C in the south (OEH 2011c). The temperature in the Tasman Sea off the east coast of NSW has risen markedly. Climate change predictions for NSW include higher sea surface temperatures (by possibly up to 4°C), stronger currents and more frequent storms (Hobday & Lough 2011). Changes to currents, regional wind patterns and mixed layer depths are also likely to affect upwellings with an associated impact on primary productivity (Hobday et al. 2006).
To illustrate this, the East Australian Current now extends 350 kilometres further south, making southern waters warmer and saltier than previously (Ridgway 2007). An observed impact of this change has been the spread of the black spiny sea urchin from NSW into Tasmania, where it was not previously found. The urchin is a voracious predator of important algal species and threatens fisheries (Ling et al. 2009). In addition, it has been found that 45 species of fish have changed their distribution in south-eastern Australia over recent years, with the change corresponding to warming observed in the marine environment (Last et al. 2010).
The world's oceans currently absorb about 25% of the carbon dioxide (CO2) generated by humans, with about 40% of this absorbed in the Southern Ocean (CSIRO & BoM 2010). The CO2 absorbed by the ocean increases its acidity, which is registered as a decrease in pH. Since 1750, the pH of the world's oceans has decreased by an average of 0.1 (McNeil & Matear 2007; Riebesell et al. 2009).
Any measurable change in pH is significant and has a potential impact on the marine environment. Ocean acidification will decrease the ability of calcitic organisms such as molluscs to form shells and corals (Fabry et al. 2008; CSIRO & BoM 2010). These effects are now being observed in the Southern Ocean where it was predicted they would first become evident. Since these organisms play an important role in food webs and the natural cycling of carbon, this will have far-reaching implications for the future health of ocean ecosystems.
NSW 2021: A plan to make NSW number one (NSW Government 2011) is the Government's 10-year plan for NSW. Under Goal 22 – 'Protect our natural environment', the plan contains the following target: 'Protect rivers, wetlands and coastal environments'. Further details on Goal 22 are provided in Water 4.1.
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.
The Protection of the Environment Operations Act 1997 aims to protect the sea and certain waters from pollution by oil and other noxious substances discharged from ships through such mechanisms 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 5.3). All six NSW marine parks have their own zoning plan, which specifies the activities that are allowed in each zone (such as where fishing is allowed).
Water quality objectives
Marine Water Quality Objectives for NSW Ocean Waters (DEC 2005) describe the water quality needed to protect the community's values for, and uses of, the marine environment. The objectives simplify and streamline the consideration of water quality in coastal planning and management.
Policy and programs
The NSW Diffuse Source Water Pollution Strategy (DECC 2009) provides a framework for coordinating efforts to reduce diffuse source water pollution across NSW. The strategy promotes partnerships and provides a guide for investment and an avenue to share information on projects and their outcomes across the state. Reducing diffuse sources of pollution in upstream catchments will help to improve the quality of the marine waters into which they discharge.
NSW marine waters and ecosystems are currently considered to be in good condition. However, pressures from urban, industrial and recreational development are growing. NSW will need to continue to implement suitable management and adaptation strategies to prevent a decline in the quality of the marine environment.
Apart from 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 and aerial helicopter and underwater video surveys will improve our understanding of the marine environment and enable it to be managed more effectively.
A mix of pollution control, fishing management and conservation measures will continue to be required 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.