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State of the Marine Environment Report for Australia: State and Territory Issues - Technical Annex 3

Edited by Leon P. Zann and David Sutton
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1996)
ISBN 0 642 23012 9


Issues in the South Australian Marine Environment

Karen Edyvane
South Australian Research and Development Institute (Aquatic Sciences)
Adelaide, South Australia

Introduction

South Australia has a large range of coastal habitats and ecosystems; from the rough-water rocky habitats of the south-east and west coast, to the calm-water seagrass and mangrove habitats of the gulf regions. Threats to these environments and their fauna and flora result primarily from the effects of land-based pollution discharges, habitat loss through urbanisation and coastal development, the effects of overfishing and fishing methods (such as trawling), sea-based aquaculture and conflict between competing user groups.

Most of South Australia's population of 1.4 million is situated on the coast (see Figure 1 for locations mentioned in the text), with major towns and cities concentrated on the Fleurieu Peninsula (including Adelaide) and northern Spencer Gulf (i.e. Whyalla, Port Pirie, Port Augusta). Other major regional centres include Port Lincoln and the towns of Robe, Kingston and Mt Gambier in the south-east. Within the coastal regions of the State, economically important activities such as commercial fishing, shipping and mineral and petroleum exploration occur. Of increasing economic importance is the developing mariculture industry which is primarily based in the coastal inlets and bays of Eyre Peninsula. Tourism and recreational fishing are particularly important in regional and local economies, especially in the towns on far-west coast and on Yorke and Eyre Peninsula. Despite the vastness of the South Australian coastline, human activities tend to be concentrated near centres of population and here most conflict or competition occurs. Hence, sound management and protection measures are needed to ensure the equitable and sustainable use of marine and coastal resources.

Marine environmental management in South Australia is achieved through several mechanisms, under a variety of State and Commonwealth legislation. Marine resources and marine protected areas are principally managed and regulated under fisheries legislation. In contrast, coastal development proposals are presently regulated under various State and Local Government planning legislation. Coastal development is regulated by the Planning Commission and overseen by the Coast Protection Board, however coastal management is often uncoordinated, fragmented and prone to jurisdictional and administrative overlap. Human activities such as mining, fishing, shipping, or tourism, which may detrimentally affect marine or coastal habitats, are generally regulated through conditions on the permits or licenses issued under the respective controlling legislation.

Effective control or regulation of marine pollution in South Australia was implemented in 1990 with the passing of legislation to control land-based point source discharges to the marine environment (DEP 1989, 1986). Under the Marine Environment Protection Act 1990, licensees are required to submit an environmental improvement program in order to meet targets within a timetable permitted under transitional arrangements. The arrangements allow a period of up to eight years for all existing discharges to comply with water quality guidelines. Discharges commencing after the Act received assent must comply with guidelines immediately they are licensed. No effective control or regulation of diffuse source pollution currently exists in South Australia. Point source marine pollution legislation in South Australia has recently been repealed and incorporated into new legislation to establish a South Australian Environmental Protection Agency (DEP 1991).

Although there are several major areas of concern in the marine environment of South Australia, overall, it appears to have been less affected by human activities than inland aquatic ecosystems (EPCSA 1988).

Marine Pollution

Marine pollution in South Australia, as elsewhere in the world, is strongly linked to land-based activities. While there are no figures on the contribution of land-based activities to marine pollution in South Australia, the majority of pollution sources are known to be close to land-based centres of human activity, in particular, the Adelaide metropolitan area and the northern Spencer Gulf region (EPCSA 1988). Because of this, marine and coastal management must address the strong land-sea-air interactions.

Figure 1

South Australian Coastline

Table 1 Action priorities for estuarine and marine pollutants in South Australia. Source: Environment Protection Council of South Australia (1992)

Pollutant Human Impact Ecological impact Source Areas most affected Probable spread or increase Scope to prevent or ameliorate Action priority
nutrients and other organic wastes

boost algal growth; create 'nuisance'

Special case is red tides - combination of nutrient build up and pest species

algal growth reduces light penetration, killing seagrasses. Change in nutrient ratios can alter make up of plant and animal communities; organic wastes deplete oxygen

point - sewers

diffuse - drains, stormwater

metropolitan Adelaide
Port Lincoln
moderate -
through fish farming
moderate high
red tides restrict recreation and consumption of seafoods red tides deplete oxygen during and after "bloom" and introduce toxins   red tides also off metropolitan Adelaide and Port Lincoln red tides likely to increase with development of fish farming moderate - but expensive
faecal wastes restricts recreation and consumption of seafoods may promote filter feeders point - sewage diffuse - other human and animal sources Adelaide - West Lakes/Port R. River Torrens Patawalonga Onakaparinga R. Port Lincoln low for human, high for other animal (pets) moderate - but expensive high
particulates and turbidity aesthetic, swimming accidents smothers substrate and changes species mix - (e.g Aldinga) stormwater; industrial discharge; dredging all larger towns and ports high - with further residential demands good, but lies with Local Government high
exotic pests and diseases foul hulls free living algae bloom compete directly, or reduce advantages of local species

point - ships and boats

fish farming

statewide and continuous high high to exclude, nil to eradicate high
heavy metals contaminates seafoods reduce numbers of fish that may be taken or consumed by humans reduce diversity of marine organisms point (municipal and industrial process) diffuse (agriculture and cars) Upper Spencer Gulf Adelaide - Port River/West Lakes, Patawalonga

low

falling

Pirie - good

Whyalla - fair

diffuse - poor

medium

 

litter restricts recreation - accidents (needles stick) kills birds, mammals diffuse (drains, stormwater boating) statewide moderate high medium
other chemicals (pesticides, consumer and household products) contaminates seafoods, recreational exposure kills marine organisms household and agriculture statewide low - many problem chemicals no longer registered (hence unavailable) moderate medium
process waste perceived effects often aesthetic; contamine seafoods; recreational exposure may affect behaviour or organisms; kill birds industry

Adelaide

regional centres

Lake Bonney (SE)

low high
chemical spill/overspray (from pest control) kill fish that may be taken/consumed by humans kill marine organisms point statewide sporadic low high low
hydrocarbons (oil)

foul structure and beaches

may taint seafoods

probably metabolic effects on organisms; kill birds

point - tankers and pipelines, industrial (solvents etc.)

diffuse - road runoff

statewide but sporadic

regular at Adelaide and Port Augusta

low high for point sources, moderate for diffuse low
bitterns (salt fields) aesthetic probably affects organisms point (salt fields)

Adelaide Price (at intervals)

low moderate low
thermal restricts recreation (but boosts fish growth) excludes some organisms - facilitate exotic species point - power stations metropolitan and Upper Spencer Gulf low low low

Nutrient enrichment or coastal eutrophication, as elsewhere in Australia and the world, is the highest-priority marine pollution issue in South Australia (Table 1). The most visible result of nutrient enrichment or eutrophication in South Australia is seagrass loss or degradation (Shepherd et al. 1989). In addition, increased nutrient loads to coastal waters have also been directly implicated in the increased frequency of algal blooms, particularly 'Red Tides', and more recently, in the loss of mangroves (Edyvane 1991; Connolly 1986).

In a study of land-based marine pollution in South Australia, 49 nutrient, 17 chemical and 15 thermal, point sources of pollution have been identified (Miller 1982). Nutrients in South Australia are from both point sources and diffuse sources, with the major contributions being clearly identified as sewage and stormwater discharges, respectively (EPCSA 1992; Steffensen et al. 1989). The main point sources of nutrients in South Australia are sewerage outfalls. Treated effluent is discharged at Bolivar, Port Adelaide, Glenelg and Christies Beach in metropolitan Adelaide, and at Whyalla, Port Augusta, and Port Pirie. Treatment of effluent at Finger Point (Mt Gambier) began two years ago, while untreated effluent is still discharged at Port Lincoln into Proper Bay. The environmental impacts of many of these sewage discharges have generally been monitored through water quality programs (e.g. Walters 1977, 1989; Steffensen 1981a, b, 1982, 1985; Steffensen & Walters 1980; Lewis 1975). The steelworks at Whyalla and food processing industries at Port Lincoln also discharge some nutrients. In addition, nutrients in the form of wastes from fish processing works are discharged into sea at Port MacDonnell, Cape Northumberland, Carpenter Rocks, Southend, Beachport and Robe in the south-east, Edithburgh and Moonta on Yorke Peninsula, and at Port Lincoln and Streaky Bay on Eyre Peninsula (EPCSA 1988; Miller 1982). The relative environmental impacts of sewage and stormwater discharges in South Australia is summarised in Tables 2 and 3, respectively.

Table 2: Ranking of the environmental impact of sewage discharges in South Australia (from EWS 1989)

Sewage Discharge EnvironmentalImpact Rating Public Health /Use Impact Rating Impact Score PriorityRating
Bolivar Effluent 10 8 18 1
Port Adelaide Sludge * 4 9 13 2
Glenelg Effluent 6 6 12 3
Port Adelaide Effluent 8 4 12 4
Glenelg Sludge * 7 4 11 5
Port Lincoln 1 8 9 6
Christies Beach 1 5 6 7
Mt Gambier 1 4 5 8
Port Augusta East 1 4 5 9
Port Pirie 1 4 5 10

* - decommissioned in 1993

Table 3: Ranking of the environmental impact of stormwater discharges in South Australia (from EWS 1989)

Stormwater System Receiving Water and Rating Area (km2) /Discharge Rating Discharge Quality Rating Impact Score Priority Rating
Sturt Creek Patawalonga 10 135/7 7 490 1
Brownhill Creek Patawalonga 10 75/4 7 280 2
Onkaparinga Onkaparinga Estuary 9 550/8 3 216 3
North Arm drains North Arm 8 38/2 10 160 4
West Lakes West Lakes 9 32/1.5 8 105 5
Dry Creek Barker Inlet 5 90/4 4 80 6
Port Adelaide Port River 7 15/1 10 70 7
Torrens River Gulf St Vincent 1 450/8 8 64 8
Little Para River Barker Inlet 5 85/4 3 60 9
Salisbury Barker Inlet 3 65/3 3 27 10
Brighton Gulf St Vincent 1 305/1.5 7 11 11
Gawler River Gulf St Vincent 1 1350/10 1 10 12
Christies Creek Gulf St Vincent 1 35/2 4 5 13
Smithfield Gulf St Vincent 1 12/1 2 2 14

The main sources of chemical discharges in South Australia are located at the industrial plants at Whyalla and Port Pirie, the Playford Power Station at Port Augusta, all at the northern end of Spencer Gulf, and the various sewerage outfalls, and saline discharges from salt and chemical works at Dry Creek and Osborne (Port Adelaide). Lake Bonney in the State's south east is the only case of pulp mill pollution in South Australia. In general, the levels of heavy metals in seawater appear relatively low and the levels of contamination of aquatic species are considered within defined limits (Jones 1989; Olsen 1988, 1983). However, this assessment has recently been brought into question (Rozenbilds 1991).

The main sites of marine pollution off metropolitan Adelaide are shown in Figure 2.

Seasgrass Loss

Seagrass degradation in South Australia has been the focus of many studies because of the widespread loss of habitat and productivity it engenders (see Shepherd et al. 1989, for a comprehensive review). In South Australia, seagrass degradation was first linked to increased nutrient levels from sewage, when seagrass loss was observed adjacent to the Glenelg effluent outfall in 1970 (Shepherd 1970). Since this time, numerous studies have demonstrated a close link between elevated nutrient (and suspended solid levels) and extensive seagrass degradation (Shepherd et al. 1989; Clarke 1987; Clarke & Thomas 1987; Neverauskas 1987a, 1987b, 1987c 1985a, 1985b; Steffensen 1985; Johnson 1981; Shepherd 1970).

Off the metropolitan coast of Adelaide in particular, nutrients and suspended particulates from stormwater, sewage and sewage sludge, have been directly implicated in the loss since 1935 of some 4000 ha or 22% of the total seagrass area (Shepherd et al. 1989; Clarke & Thomas 1987; Neverauskas 1987a). Seagrass degradation off metropolitan Adelaide is concentrated in Holdfast Bay (Brighton to Outer Harbour), off the mouth of the Port River at Outer Harbour and between St Kilda and Port Gawler (DELM 1993).

Total seagrass degradation in the metropolitan region covers approximately 5000 ha. This represents 22% of seagrass in Holdfast Bay, 25% of the St Kilda-Port Gawler region and 3% of the total seagrass area in Gulf St Vincent (DELM 1993). In addition to the areas of total loss there has been selective loss of Amphibolis over 1100 ha in the vicinity of the Port Adelaide sludge outfall and current surveys in progress indicate that Amphibolis may have been lost over a further 3000 ha in Holdfast Bay (DELM 1993).

Of particular concern is the cycle of instability which seagrass loss causes. While seagrass decline is initiated by algal epiphytes shading and smothering the leaves, seagrass loss results in the release of sediments previously bound by the seagrass roots, and contributes to greater instability and even larger areas of seagrass loss or 'blowouts' (Clarke & Kirkman 1989; Clarke & Thomas 1987).

Seagrass loss, particularly off the metropolitan coast of Adelaide, is still continuing and possibly accelerating. Inshore loss of seagrass between Glenelg and Semaphore, occurred gradually until about 1961, when it increased rapidly due to fragmentation of the beds (Steffensen 1985). The inshore seagrass boundary is still receding with significant regression still occurring within the beds (Shepherd et al. 1989). Within existing beds off the metropolitan coast, seagrass cover has declined from 80% in 1949 to 28% in 1993 (Gordon-Mills, unpubl. data). With the present low level of water quality off Adelaide's metropolitan coast, it has been estimated that at the current rate of seagrass decline, no seagrass will be left off the metropolitan Adelaide coast (i.e. Holdfast Bay) by the year 2014 (E. Gordon-Mills, University of SA, pers. comm.). The implications for coastal erosion and fisheries depletion are considerable.

It is important to note that point source sewerage sludge outfalls are also a significant source of increased particulates and turbidity, particularly to the offshore areas of Adelaide (Steffensen et al. 1989). Suspended solids attenuate the light and can therefore have the same effect on seagrasses as epiphytes (Steffensen et al. 1989), and have also been implicated in the decline of seagrasses (see Shepherd et al. 1989).

Outside the metropolitan Adelaide region, large scale loss of Amphibolis (and to a lesser extent, Posidonia) has continued to occur in the poorly flushed northern Spencer Gulf region (Tickera to Port Pirie). The latest episode of loss followed an extensive algal bloom in February 1993. While the coastal area affected extends approximately 80 km, the causes of the loss have not been determined. They possibly include the effects of elevated nutrients and sediments from agricultural run-off, salinity and temperature changes or a pathogenic outbreak.

The effects of nutrient enrichment on the benthic fauna of areas not dominated by seagrass remains almost completely unexplored.

Algal blooms ('red tides')

High levels of nutrients (i.e. nitrogen and phosphorus) also result in excessive algal growth or in the formation of algal blooms. In the upper reaches of the Port River, high levels of nutrients, due mainly to effluent discharges from the Port Adelaide sewage treatment works (Steffensen & Walters 1980), are utilised by several species of opportunistic dinoflagellates, some toxic, forming algal blooms or 'red tides' (Cannon 1990). Shellfish in the region feed on these microscopic organisms, and with toxic species, accumulate their toxins. Consumption of contaminated shellfish by humans can produce the near-fatal condition, Paralytic Shellfish Poisoning (PSP). This has resulted in regular closures of the Port River - Barker Inlet system to the taking of shellfish; primarily during the spring months when conditions are most favourably for bloom formation.

Figure 2

Figure 2: Main site of sewage pollution off metropolitan Adelaide

Elevated nutrient levels have also resulted in the nuisance growth of the seaweeds, sea lettuce weed (Ulva sp.),Gracilaria sp. and Giffordia sp. off metropolitan Adelaide. The brown algal species, Giffordia sp. bloom off Adelaide beaches mid-summer causing nuisance drifts to swimmers and result principally from the significant nutrient enrichment of the waters by urban sewage and stormwater inputs (DELM 1993). Nuisance seaweed growths are also of particular concern in the northern metropolitan area and in the Barker Inlet estuary, where nutrient enrichment is primarily from effluent from the Bolivar sewage treatment works (Connolly 1986). Under prevailing conditions, drift Ulva (and to a lesser extent, Gracilaria sp.) can accumulate in mangrove and beach areas (such as St Kilda), where it forms large, decomposing drifts. Until recently, these seaweed drifts were primarily considered an aesthetic problem through producing odours and looking unsightly.

Mangrove Loss

Recent studies are now indicating that elevated nutrient levels, from sewage and stormwater discharges, could also be affecting mangrove ecosystems adjacent to outfalls. These studies suggest that the progressive build-up of Ulva in the coastal waters of metropolitan Adelaide due to increased nutrients have not only resulted in the large-scale loss of seagrass, but also the loss of mangroves (Edyvane 1991; Connolly 1986). In shallow sheltered areas, large drifts of Ulva (together with dead seagrass), prevent or retard the establishment and growth of young mangrove seedlings, and also choke established trees by smothering and eventually killing the aerial roots or pneumatophores (Edyvane 1991; Connolly 1986). The major area of 'nutrient-induced' mangrove dieback is the shallow tidal flats between St Kilda and Port Gawler, in particular, adjacent to the Bolivar sewerage outfall (Edyvane 1991; Connolly 1986).

Work to date indicates that the gradual loss of mangroves adjacent to the Bolivar effluent outfall began 6 years after the commissioning of the Bolivar Sewage Treatment Works and the rate of loss is increasing (Bayard 1992). In contrast, in regions such as Light River, out of the zone of influence of the effluent, there has been a seaward increase in mangrove area at approximately 18 metres/year between 1935 and 1979 (Burton 1982). Approximately 68 hectares of mangroves have died in the region between St Kilda and Port Gawler since 1969 , with the greatest area of loss concentrated around the Bolivar sewerage effluent outfall (Bayard 1992). However, significantly greater areas of mangroves are presently in poor health. Recent estimates indicate that in the region immediately adjacent to the Bolivar sewerage outfall approximately 250 ha have been lost since 1956 (Bayard 1992). The full extent of nutrient-induced mangrove loss in the metropolitan Adelaide region has not been estimated.

In the long-term, continued poor recruitment and increased mortality of mangroves, particularly in the St Kilda to Port Gawler region, could result in severe reductions in the productivity of these ecosystems. Since the tidal wetlands in this region represent the most important nursery area in Gulf St Vincent for commercial and recreational fisheries (Jones 1984), this problem potentially rivals seagrass degradation in its significance to the State's gulf fisheries.

Industrial discharges

Port Pirie:

The largest lead and zinc smelter in the world is situated at Port Pirie on the eastern shore of the upper end of Spencer Gulf. Since 1890 it has been polluting the surrounding environment with aerial and liquid discharges. While Broken Hill Associated Smelters (BHAS), the company operating the smelters, has made considerable efforts to reduce pollution, the effects of pollutants are persistent and long lived. Liquid effluent containing 250 tonnes of zinc and 100 tonnes of lead each year is still discharged into Spencer Gulf via First Creek. This is in marked contrast to BHAS's affiliate at Port Kembla, which effectively removes all metals (Rozenbilds 1991).

The effects of the smelter operations on the marine environment have been considerable. In 1979 the CSIRO, sponsored by the International Lead Zinc Research Organisation (ILZRO), began a four year study of the effects of pollution at Port Pirie on the adjacent marine environment. The study concluded that sediments over an area of 600 km2. were contaminated by particulate cadmium, lead and zinc, the main sources of which were smelter stack emissions (since ceased), ore spillage and fugitive dusts. Lesser areas were contaminated by copper, arsenic and manganese.

In addition to large scale contamination of sediments, almost all the biota found in these contaminated areas displayed elevated levels of cadmium, lead and zinc (Ward et al. 1986). Despite this, metals in the flesh of species commonly consumed by humans did not exceed health standards, provided only the muscle was eaten. However, three species approached the limit, and some reservations were expressed about the accuracy and definition of the recording techniques (Ward et al. 1982). Measures to reduce pollutant discharges to the marine environment are currently being supervised by the newly established Environment Protection Authority.

There has also been considerable long-term effects on the ecology of the adjacent seagrass community. Widespread contamination in the region has resulted in changes to the structure of the seagrass community. For the seagrass fauna, species richness and composition (both measures of diversity), and species abundance (number of individuals of a species) all decrease as contamination increase (Ward & Young 1982). Of the species in the seagrass community, 20 were identified as sensitive to metals, and a further 15 as sensitive to metals or clays (Ward et al. 1986, 1982).

In a recent report, liver cadmium levels were shown to be elevated in adult Bottlenose Dolphins, Tursiops truncatus, inhabiting the inshore gulfs of South Australia. The cadmium emissions from the lead smelter at Port Pirie have been implicated as the prime source of cadmium (Kemper et al. 1994a).

Whyalla:

Spencer Gulf is also the region for the largest chemically contaminated effluent discharge into the marine environment in South Australia. Broken Hill Pty. Ltd. (BHP) steelworks is located at Whyalla on the western side of Spencer Gulf. Effluent from the combined steelworks, blast furnace and coke oven is contaminated with solids, metals, cyanides, ammonia compounds and phenols, and discharged to an area open to the sea. Additionally, discharges from the magnetic plant tailings dam, which contain high levels of dissolved iron, also percolate through to the sea (Miller 1982).

The immediate effects of these discharges are most probably the elevated concentrations of zinc, cadmium, chromium, copper and lead which occur in the intertidal mudflats around Whyalla (Harbison 1984). The effects of these effluents on marine life have not been studied but are considered likely to be similar to those of Port Pirie. A cause for concern is the bio-availability of these metals and the consequent contamination of the marine food chain (McLaren & Wiltshire 1984; Thomas 1981). While zinc was considered the only metal which could be taken up by organisms in a soluble form, the other heavy metals, which attach to fine particulate matter, could be readily taken up as food by the benthic organisms (Harbison 1984).

Thermal Pollution

The most significant thermal discharges in South Australia are from the power stations at Torrens Island (Port Adelaide) and Port Augusta, although most major industries discharge some cooling water (Miller 1982).

Monitoring studies at the Torrens Island and Port Augusta power stations, conducted by the Electricity Trust of SA (ETSA), have reported changes in the composition of benthic faunal communities in the intertidal zone, and the fringing seagrass subtidal zone, adjacent to the cooling water outfalls (Ainslie et al. 1989; Thomas et al. 1986).

Further, elevated heavy metal contamination near the power station at Port Augusta, at the head of Spencer Gulf, is thought to be due to fly ash in the power station effluent (Harbison 1984).

The fly ash ponds at the Playford power station at Port Augusta were relocated following reports of mangrove dieback (Kinhill Stearns 1986). These particular areas of dieback have since stabilised, however the cause of a recent and on-going patch of dieback adjacent to Hospital Creek is presently unknown (Bayard 1993).

Pulp mill pollution

Lake Bonney in the State's south-east is the only case of pulp mill pollution in South Australia. Lake Bonney is a permanent, shallow coastal lake, heavily polluted by effluent from two pulp and paper mills located near Millicent. The lake's water level is regulated by the Engineering and Water Supply Department, and it is usually necessary to release water to the sea in spring or early summer, through the outlet channel. The contaminants of major concern in the effluent are halogenated organic compounds, measured as Adsorbable Organic Halogen (AOX) in water, or Extractable Organic Halogen (EOX) in sediments and biota. Halogenated organic compounds, such as organochlorines, range from completely harmless substances to extremely toxic ones (such as dioxins and furans), which are generally persistent, lipophilic, small, or polychlorinated and often strongly bioconcentrated (Fandry et al. 1989). Although the lake is thought to effectively act as a treatment basin, studies to date have found no trace of dioxins in the lake (Kinhill Stearns 1990).

The effects of the lake discharge on the marine environment are also inconclusive. From September to November 1989, over 35 tonnes of AOX was released to the sea from Lake Bonney, causing a visual plume covering over 55 km2. However, studies found no contaminants in either the sediment or the biota tested (Neverauskas 1990). Recent changes in the pulp milling process has virtually eliminated all chlorine in bleaching and reduced other pollutant loads to Lake Bonney. Monitoring is required to document any potential recovery of the lake ecosystem.

Diffuse sources

It has been estimated that 90% of land-based discharges in South Australia are derived from diffuse sources (EPCSA 1988). Stormwater run-off and river catchment discharges are the principal components of diffuse source pollution, with the water quality of the discharge being primarily determined by the dominant land use of the catchment area. Urban run-off contains solid wastes, litter, chemicals, vehicle pollutants, pesticides, bacteria, soil and dust. In addition, offensive domestic chemicals, and oils and greases from backyard garages are usually directed into stormwater drains, as are chemical spills and sewer pumping overflows. In contrast, rural run-off may contain a combination of animal wastes, fertilisers, pesticides, agricultural chemicals and soil.

In South Australia, problems with urban run-off are principally of concern in metropolitan Adelaide. Stormwater has been identified as a major source of faecal bacteria in Lake Patawalonga at Glenelg, the Onkaparinga Estuary (Manning & Associates 1985), and West Lakes. The Patawalonga receives stormwater flows via stormwater channels from the Sturt River and a large catchment of creeks and drains controlled among approximately 11 separate local government councils. Water quality in the basin is poor because of restricted flushing, a result of a barrage and lock system, and deteriorates whenever stormwater enters (Patawalonga Basin Task Group 1989). As a consequence, bacteriological standards for recreation in the lake are exceeded most of the time and the Council of the City of Glenelg has banned contact water sports. The Patawalonga also has a high sediment and nutrient loading, and unsightly floating debris, rubbish and trash, which accumulates in high volumes. The discharge of these waters into the sea has possibly contributed to the decline in seagrasses in the vicinity of the outlet and has affected the quality of the local beaches.

West Lakes, an artificial lake, receives stormwater run-off from a smaller catchment area. However, this is sufficient to cause short-term bacteriological contamination, nuisance growths of seaweeds and algae, and toxic contamination of shellfish by dinoflagellates (one occasion), and lead in 50% of mussels samples (Steffensen 1988).

Recently it has been realised that the quality of stormwater run-off in the Onkaparinga Estuary could be improved significantly by filtering through artificial wetlands (Manning & Associates 1986). As such, a number of suitable sites have been identified in which to establish wetlands (Onkaparinga Estuary Task Group 1990).

Pollution from diffuse sources in South Australia can also contribute amounts of industrial pollution to marine environments. For instance, the total load of heavy metals discharged by the River Torrens annually is an order of magnitude equivalent to the effluent load from the Bolivar sewage treatment works. For copper and cadmium, the mass loads are higher than the Glenelg sewage treatment works sludge outfall. The loads for each of the four major stormwater drains between Glenelg and Seacliff are equivalent to the effluent load from Christies Beach or Finger Point sewage treatment works (EPCSA 1988). Of particular concern is the North Arm of the Port River Estuary, which receives discharges from four major and several minor stormwater drains.

The Port River estuary is the most diversely polluted estuary in South Australia and receives pollutant inputs from numerous point and diffuse sources (Rozenbilds 1991; Hine et al. 1989). This has resulted in significant heavy metal contamination of sediments, particularly of lead and zinc (Harbison 1986a, 1986b). Inputs include effluent from the Port Adelaide sewage treatment works and the outflow from West Lakes to the head of the Port River, discharges from the numerous stormwater drains along the North Arm, discharges from Dry Creek and the Little Para River into Barker Inlet, thermal effluent from the Torrens Island Power Station in Angus Inlet, and run-off from a heavily industrialised local catchment. Within the estuary the cumulative effect of these inputs results in water quality which consistently exceeds the recommended national and state criteria for protection of aquatic ecosystems (PPK Consultants 1992).

Ship-based pollution

Oil spills:

Port Adelaide and Port Stanvac remain the major sites for oil spills in South Australia. However, the number of oil spills over the past decade is considerably greater than during the first half of the 1970s and the annual volume of oil spilled remains high (DELM 1993). Between January 1988 and June 1992 there was a total of 14 oil spills in South Australian waters, in which 8610 litres was released (DELM 1993). During this time there were 2 spills at Port Adelaide and 10 at Port Stanvac. However, in August 1992, an accident at Port Bonython resulted in the largest coastal oil spill in Australia's maritime history, in which approximately 300 000 litres (296 tonnes) of bunker oil were released into a region of the sensitive mangrove-seagrass communities of upper Spencer Gulf. Prior to this, the largest oil spill in South Australia was a spill of 234 325 litres at Port Stanvac in 1982 (EPCSA 1988). All clean-up operations for oil spills in South Australia are coordinated under the national Oil Spill Contingency Plan.

The effects of oil spills on the marine environment in South Australia have until recently generally received little attention. The monitoring of a minor spill upon mangroves in the Port River indicated few long-term effects (Wardrop & Wagstaff 1988). However, the monitoring of the recent 'Era' oil spill in upper Spencer Gulf has revealed that approximately 23 hectares of mangroves are dead or totally defoliated in heavy oiled areas (Butler 1993, Wardrop et al. 1993) and show no sign of significant recovery 2 years post-spill (Edyvane, SARDI, unpubl. data). No hydrocarbons were detected in benthic sediment samples collected within the upper Spencer Gulf region or in flesh from collected fish and crab specimens (Butler 1993). No tainting of prawns was observed. However, biochemical studies of 2 fish species, Yellow Fin Whiting and Yellow Eye Mullet, indicate post-spill changes in the level of mixed-function oxidases (K. Bellette, University of Adelaide, pers. comm.).

The long-term effects of frequent minor spillages at the main oil-handling facilities at Port Stanvac, and in the Port River are not known (Rozenbilds 1991). However, the impact of spillages and ballast water discharges at the port and terminal facilities at Port Bonython (Stony Point) have been monitored as a condition of licensing. No effect from any test, including taste testing for tainting of prawns has been observed (SANTOS 1985, 1984).

Antifoulants:

Organotin compounds, especially tributyltin (TBT), have been used extensively throughout the world and in Australia as marine antifoulant paints preventing encrustation of the hulls of ships and small boats by tubeworms and barnacles. Recent studies have shown TBT to be highly toxic, having effects upon marine life at levels as low as parts per trillion. At lesser concentrations, TBT has been shown to cause oyster shell deformities and induce severe reproductive abnormalities in some gastropods (i.e. neogastropod imposex). This, coupled with frequent findings that TBT concentrations are rising in waters subject to high levels of boating activity, has sparked growing concern about TBT (Champ 1986). New South Wales, Queensland, Victoria and Tasmania, have banned the use of TBT as an antifoulant paint on boats less than 25 meters, and imposed restrictions upon its rate of leaching from larger vessels. Similar legislation banning the use of TBT does not exist in South Australia.

In South Australia, a recent survey of neogastropod imposex in the marine gastropod Lepsiella venosa by Nias et al. (1993) revealed 100% imposex in specimens collected from Barker Inlet, Port Lincoln and Coffin Bay. All these places had significant moorings of boats.

Ballast water discharges:

The discharge of ballast water from international shipping appears to be responsible for the introduction of a number of exotic microscopic algae in Australia. Of particular concern is the introduction of toxic dinoflagellate phytoplankton, which under favourable conditions can lead to the occurrence of toxic 'red tides'. These algal blooms not only discolour the water, but toxic species can cause health problems for humans who consume contaminated shellfish and sea farm products.

South Australia is the location for 3 of the 16 introductions of exotic organisms attributed to ballast water or sediment in Australia: the polychaete, Pseudopolydora paucibranchiata and the crustaceans, Tanais dulongi and Eurylana arcuata (Jones 1991). In particular, the toxic dinoflagellate, Alexandrium minutum, which is responsible for the regular toxic red tides in the Port River, is thought to have been introduced to the state from the ballast water of shipping (Hallegraeff et al. 1988). Other similar ballast water introductions are thought to have occurred in Hobart and Port Phillip Bay, Melbourne. The introduction and spread of A. minutum in South Australia has been directly linked with shipping, including recreational craft. A recent survey has shown A. minutum cysts in the sediments of other major ports and bays in South Australia, including Port Lincoln, Ceduna (Thevenard), Kangaroo Island (American River, Penneshaw, Ballast Head, Kingscote), Coffin Bay, Franklin Harbour and Streaky Bay (J. Cannon, University of Adelaide, unpubl. data). The introduction of A. minutum is of major concern to the oyster industry in many of these areas.

Overfishing

Over-exploitation of fish resources has been documented in many fisheries around the world. In South Australia, marine resources, particularly fish, crustacea and molluscs, have long been important sources of food and other materials for humans (EPCSA 1988). Aboriginal communities, prior to the coming of European settlers, caught fish using stone fish traps in shallow waters and early whalers and sealers established fishing communities on Kangaroo Island even before the arrival of settlers in 1836. However, the commercial and recreational fishing industries are now the main users of marine resources in South Australia, and ensuring their sustainable and equitable use continues to present a major challenge to managers.

Approximately 20 fish species and 3 species of crustacea and molluscs provide the basis for the fishing industry in South Australia. The 1991-92 commercial marine fisheries reported landed catch was 18 087 tonnes with a value of production of $128.4 million (excluding processing and marketing), which represents approximately 10% of the national total (DELM 1993). The major fisheries in terms of value of landed catch were Southern Rock Lobster, Western King Prawn, Abalone, Tuna and Marine Scalefish.

Modern fisheries management measures were first introduced in South Australia in 1968 in recognition of the fully exploited status of the State's traditional fisheries (i.e. marine scalefish and Southern Rock Lobster). Since then, these measures have developed to include all the State's fisheries. Nevertheless, several commercial fisheries have become seriously overexploited despite improved management practices (EPCSA 1988). Commercial catches of Western King Prawn have dropped substantially from 1981 to 1991, while Southern Rock Lobster catches have stabilised despite a significant increase in fishing effort due to satellite navigation (DELM 1993). Annual commercial catch limits or quotas have been proposed for several major commercial finfish species in South Australia (Rohan et al. 1991), however these have yet to be introduced. Following declines in catches, quotas have already been introduced for Southern Bluefin Tuna and Greenlip and Blacklip Abalone in South Australia.

In South Australia, there are three fisheries which are considered to be 'overfished': Catfish (FW), Murray Cod (FW), and Western King Prawn (Gulf St Vincent) (Commonwealth of Australia 1991). A further twelve fisheries are considered 'fully fished' (see Table 4). However the status of knowledge for management is considered 'adequate' for only 5 of 27 fisheries (i.e. 19%) in South Australia: Blacklip and Greenlip Abalone, Southern Rock Lobster, King George Whiting and Australian Salmon. Further, the knowledge required for 'ecologically sustainable development' is considered 'adequate' for only 2 fisheries in South Australia (i.e. 7%): Blacklip and Greenlip Abalone (Commonwealth of Australia 1991).

In Australia there are relatively few fished species for which the state of biological knowledge is adequate to undertake even the most basic stock assessment for management purposes (Commonwealth of Australia 1991). There are a number of reasons for this. Firstly, sound management of fisheries needs a wide range of data: biological, environmental and economic. Secondly, our state of knowledge about the aquatic environment is very poor relative to land-based environments, because research is both difficult and costly (Commonwealth of Australia 1991). Hence, we have little understanding of the interdependence of species, their relative positions and importance in the food web, or how they interact with both natural and human-induced changes in their environment. While we can be certain that a fishery ecosystem is being affected by the physical impact of trawling operations on habitat, and by the relatively large by-catch, our knowledge base is such that we cannot quantify the effect, nor understand the implications for crucial issues such as marine biodiversity (Commonwealth of Australia 1991).

Table 4: Status of South Australian commercial fisheries (from Commonwealth of Australia 1991)

''Over Fished'

Catfish (FW)

Murray Cod (FW)

Western King

Prawn (GSV)

'Fully Fished'

Golden Perch (FW)

Blacklip Abalone*

Greenlip Abalone*

Garfish

Mulloway

Western King

Prawn (Spencer)

Southern Rock

Lobster

Snapper

Squid

King George

Whiting*

Yellowfin Whiting

'Uncertain Status'

Redfin Perch (FW)

Bream

Cockles

Snook

Blue-Eyed Trevalla

'Underfished'

Bony Bream (FW)

Yabbie (FW)

Blue Crab

Ocean Jacket

Yellow Eyed Mullet

Tommy Ruff

Australian Salmon*

* - status of knowledge for management considered 'adequate'

In South Australia, fishery information does not extend to the take of bycatch which is discarded, nor to the physical impact of fishing. In some fisheries, such as prawn trawling, the weight of discarded bycatch can be in the order of eight times the catch retained. Thus, for the estimated 1991 prawn catch of approximately 2000 tonnes, in the order of 16 000 tonnes of non target species were probably killed as bycatch (DELM 1993).

There are 4 commercial licenses for scallop dredges in South Australia. However license conditions and regulations so restrict the use of these dredges that they are unlikely to have any effect on the sea bottom. As such, scallop dredging activities are restricted within major bays and the gulfs.

Sea-based aquaculture

Aquaculture in South Australia is defined as the farming of aquatic organisms, including fish, molluscs, crustaceans and aquatic plants. It includes the breeding, hatching, rearing and cultivation for sale of all aquatic organisms. Farming is defined as the input of labour and attention to promote or improve growth of stock, implying individual or corporate ownership of that stock. This definition is in line with that proposed by the Draft National Aquaculture Strategy. Australian aquaculture production (including oysters, pearls, salmonids, prawns, marine and ornamental fish) was valued at $277 million for 1991-92. Production increased at 16% in comparison with 1990-91, and now constitutes approximately 20% of the total Australian fisheries production.

Aquaculture in South Australia is a relatively new industry, with only three sea-based industries: Pacific Oyster (Crassostrea gigas) farming, cage culture of Southern Bluefin Tuna (Thunnus maccoyii), and cage/barrel culture of Abalone (Haliotis rubra and H. laevigata). Land-based aquaculture industries include: extensive crayfish pond culture of Yabbie (Cherax destructor) and marron (Cherax tenuimanus); raceway based abalone culture; extensive euryhaline pond culture of the microalgae, Dunaliella salina; and finfish farming of Trout (Oncorhyneus mykiss) in extensive ponds and Barramundi (Lates calcarifer) in intensive culture systems. Only Abalone and D. salina are dependent on the water quality of seawater for successful cultivation. There are presently (30 June 1993) 88 approved marine aquaculture sites in South Australia comprising 76 oyster leases, 11 tuna farm leases (9 farms, 1 R&D farm and 1 tourist facility), and 1 sea-based Abalone farm site (located off Cape Forbin, Kangaroo Island). A further 20-30 applications on a variety of tried and new species are pending, including Snapper (Pagrus auratus) and Southern Rock Lobster (Jasus edwardsii).

Pacific Oyster culture using the intertidal rack method occurs in six main regions in South Australia: Coffin Bay (19 approved), Denial Bay (16 approved), Streaky Bay (6 approved leases), Smoky Bay (13 approved), Franklin Harbour (12 approved leases) and Western Cove - Bay of Shoals, Kangaroo Island (4 approved). Unlike oyster culture in other countries, or interstate, farming is restricted to inverse estuaries that are productivity dependent on ocean water exchange. The low phytoplankton productivity of South Australian coastal waters and the extreme environmental culture conditions (12-35oC and 35-42 ppt) has likened farming oysters in SA to the equivalent of marginal wheat farming. Farmers can expect to have several years where the equivalent of drought conditions prevail. This has considerable ramifications on the impact of farmed oysters on competing filter feeders during these periods.

Tuna farming is presently isolated to the Boston Bay region adjacent to Port Lincoln. Capture boats purse seine suitable tuna stocks (15 to 40 kg fish), that are then transferred by divers through an underwater raceway into a towing cage. The fish are then towed back to Boston Bay, where the underwater transfer process is reversed into 40-50 m cages. Fish are then fattened for between 3 and 9 months, currently using pilchards or mackerel. Approximately 1.5 tonnes of feed is added to each cage daily. Harvesting starts within two to three months of capture to take advantage of the high market values in Japan. By holding the tuna, fishers control market timing to optimise their product value and increase the meat quality, which is essential for the sashimi market. There are presently 11 approved tuna farming sites with the potential to use 98 cages of 40m diameter at an initial stocking rate of 2.4 kg/m3.

Planning

Aquaculture development proponents submit applications to the appropriate local council, which then forwards all developments involving crown land to the South Australian Aquaculture Committee (SAAC), a sub-committee of the South Australian Planning Commission with representatives from the Department of Primary Industries (DPI), Department of Environment and Natural Resources (DENR), Office of Planning and Urban Development (OPUD), South Australian Conservation Council, South Australian Fishing Industry Council (SAFIC) and an independent chair appointed by the Planning Commission). All applications are assessed by a Technical Advisory Group (TAG) with representatives from DENR, OPUD and the South Australian Research and Development Institute (SARDI). The advisory group inspects the site and then makes recommendations to SAAC on the validity of the proposal, taking into account public comments. Depending on the nature of the development, the TAG will also recommend planning conditions and the statutory authority which will administer them. Incorporating DPI and DENR in the planning process approval by SAAC also implies the applicant will be granted a DPI licence and a DENR miscellaneous lease. Currently DPI licences are renewed yearly, while DENR miscellaneous leases are for one year plus ten and ten, subject to appropriate surveying of the site in the first year. Fees are levied from farmers in two main areas as part of their planning approval: firstly, for environmental monitoring (tuna farmers pay $9000 and oyster farmers $500); and secondly, for public resource allocation (rent). A right of appeal exists for both the developer and concerned members of the public. Since the inception of SAAC no environmental group has been successful in overturning a planning decision.

To remove the uncertainty inherent in developing the coastal zone, DENR and DPI have initiated a series of aquaculture management plans (Coffin Bay, Murat and Smoky Bay, Streaky Bay, Franklin Harbour, Kangaroo Island and Port Lincoln) that provide both a zoning of the area concerned and a series of development guidelines (Bond 1993, 1991; PPK Consultants 1992a, 1992b, 1992c, 1992d; Wilson 1989, 1988). This has allowed for a more systematic and strategic approach to aquaculture planning, in South Australia. However, plans often have to be modified due to the failure to incorporate other, often conflicting, coastal uses and future development strategies within the coastal zone (such as tourism, recreation, nature conservation and fishing). As such, there is a need for integrated, multiple-use, coastal management plans for specified areas which address the cooperative management of specified areas for the range of existing and potential coastal uses and activities.

Environmental impact

There are two issues concerning the environmental impact of aquaculture activities. Firstly the impact of the activity on the environment and, secondly, the impact of the environment on the farm. While sea-based aquaculture developments rely on a clear and healthy environment for their viability, the developments themselves have the potential to introduce exotic species and diseases to wild stock. Further, unless adequately controlled through management plans, aquaculture activities can result in the pollution of adjacent areas and/or the eutrophication of confined water bodies. Defining what constitutes an aquaculture impact creates conflict between competing resource users. Farmers tend to focus on local water quality effects and do not consider such issues as aesthetic and noise pollution, bird and marine mammal impact, fish behaviour and ecosystem changes from nutrient accumulation. In some cases such effects are often described as environmental improvements by fish farmers.

The major environmental problem attributed to aquaculture in South Australia is the establishment of natural breeding populations of the exotic Pacific Oysters in areas adjacent to farm sites. One of the major factors in approving the introduction of Pacific Oysters into South Australia was scientific evidence that showed successful settlement could not occur. This was based on the fact that Pacific Oyster larvae could not survive the high salinities that occur in all growing regions during the summer spawning period.

Sea-based fish farming in South Australia has the potential to result in significant habitat modification, possible environmental degradation from waste and effluent, introduction of diseases and chemicals, translocation of exotic species, and conflict over space with other resource users. Further, because this activity often relies on the use of fish food manufactured from wild stocks, demands are also placed on those resources. This can be a negative aspect if those wild stocks are improperly managed. Further, fish farms may attract natural predatory species, such as sharks, which are then treated as pest species.

Sea-based fish farming activity in South Australia is presently confined to the 'growing out' or 'fattening' of wild-caught juvenile Southern Bluefin Tuna in cages in the Boston Bay region, described above. Serious concerns exist over the impact on pilchard stocks which are used as fish food and the present poor water quality in Boston Bay, particularly, the elevated nutrient levels in the bay and the potential for algal blooms and disease outbreaks. In accordance with the recommendations of the Port Lincoln Aquaculture Management Plan (Bond 1993), by 1995 a total of 17 sites comprising 158 cages could be located in Boston Bay and the adjacent Spencer Gulf zone.

Environmental monitoring

Environmental monitoring of aquaculture activities in South Australia is conditional for both the DENR miscellaneous lease and DPI licence. To facilitate this, DPI and SARDI have established the Shellfish Environmental Monitoring Program (SEMP) and the Tuna Environmental Monitoring Program. The SEMP started in December 1991 while the TEMP is still in the documentation and development phase. The SEMP currently measures and records :

In addition, research has started on determining how to quantify carrying capacity for each shellfish growing region. At present this research has focused on the waterways of Coffin Bay. One of the current problems with the SEMP is the development of appropriate management responses to monitoring results. This is currently being reviewed to insure that quantified impacts have appropriate management responses.

The focus of the proposed TEMP is to develop a predictive assimilative capacity model for Boston Bay. The main components of the model include modelling the hydrodynamic pattern, and measuring changes in phytoplankton productivity and seagrass cover.

Conflict between user groups

The multiple, and generally conflicting, uses of coastal and marine environments can often result in habitat loss and destruction. In short, there are major conflicts between using coastal habitats and their resources as places to live, as places to recreate, or as places to work. Activities in coastal and marine environments range from those which require the maintenance of the natural state, such as tourism, recreation, scientific research, education and conservation; to exploitative or extractive activities which modify the ecosystem, such as urban or industrial developments, fishing, aquaculture, and mining. Inevitably, without integrated and coordinated management of these activities through integrated coastal zone management, the range of different activities and uses of the marine environment will continue to conflict with each other and create considerable discord amongst the different user groups.

In South Australia, there are major conflicts between urban and industrial development and fishing interests. Commercial and recreational fishing groups have been concerned for a long time over the impact of sewage and stormwater pollution on the destruction of seagrass habitats, particularly in Gulf St Vincent; the loss of mangrove and saltmarsh habitats due to coastal developments; and also the potential contamination of fish stocks from oil spills and the considerable industrial discharges in the upper Spencer Gulf region. Even in the more remote areas of South Australia (for example, Smoky Bay), sewage pollution from the septic tanks of shack developments are of concern to local fishers. Of particular concern is the proposed freeholding of coastal shack developments in South Australia, which will perpetuate existing environmental problems, including septic tank seepage, destruction of coastal habitats, rubbish, coastal erosion and flood and storm risk.

Aquaculture, although a relatively recent industry in South Australia, is particularly prone to land-based pollution. Oyster farms, in particular, require high water quality and hence are generally incompatible with urban developments. In the USA, approximately 40% of all shellfish farms have been closed due to sewage pollution. In New South Wales, several commercial oyster farms have been closed due to faecal contamination from nearby sewage discharges. Shipping and port and marina developments are also incompatible with oyster farming activities because of the widespread use of antifoulants. Tin-based paints, particularly, are known to result in shell loss and deformities in oysters.

In South Australia, aquaculture developments in some areas directly compete with other users of marine resources. Oyster racks and caged tuna farms in South Australia reduce visual aesthetics, which may reduce tourist or conservation values; aquaculture sites may compete with netting or angling sites for commercial or recreational fishers; oyster farms may reduce the overall productivity of bays; effluent from tuna farms may degrade nearby habitats; the farming of exotic species may introduce disease or result in the release of exotic species into natural areas. In particular, the incremental development of oyster leases in many scenic areas of South Australia (e.g. Coffin Bay) is causing local conflict with community, fishing and tourism interests (Wilson 1988).

While tourism generally capitalises on the natural values of areas, uncontrolled tourist developments can lead to the destruction of the very features that made them attractive in the first place. Visitors often require facilities such as parking, marinas, toilets and accommodation, all of which can detract from the natural beauty of wild places. Unfortunately many of the remote and wild coastal areas of South Australia, particularly on the west coast and Eyre and Yorke Peninsulas, are suffering from the results of uncontrolled tourism. Uncontrolled shack development, off-road vehicle usage, and parking and camping areas, are causing considerable erosion of some of South Australia's most scenic coastal regions and their wilderness values.

Key marine habitats under threat or significant in South Australia

Estuaries

Coastal estuaries in Australia, as elsewhere in the world, are seriously threatened by human activities (Hutchings & Saenger 1987). As such, there has been considerable documentation on the decline of estuarine resources, in particular seagrass beds, which have been fragmented, and loss and destruction, through such practices as sewage discharges, urban run-off, dredging, boating, and land reclamation (Shepherd et al. 1989).

Estuaries are of special importance in South Australia because of the State's generally arid nature. The majority of rivers in South Australia are temporary streams which flow (and flood) only after local rains have fallen. Hence, many of the estuaries receive irregular freshwater inputs. For this reason, many have been called 'reverse estuaries' because they are often most saline at the top, rather than at the mouth, of the estuary.

The small numbers of rivers which were permanent at the time of European settlement have been severely affected by their use as water supply sources. This has resulted in a drastic reduction in their flow, and the virtual elimination of flow downstream of storage and diversion structures. This has had major impacts on the extent of flowing water available as habitat, and points to the urgent need for the State's remaining streams to be protected from development (EPCSA 1988). A number of rivers and streams have already been identified in South Australia as being of outstanding environmental value and consequently recommended for declaration as wetland reserves (Table 5; Lloyd & Balla 1986).

South Australia has the least number of estuaries in Australia. Of the 738 estuaries (and enclosed marine waters) identified in Australia, 15 occur in South Australia, compared with 307 in Queensland; 145 in Western Australia; 137 in the Northern Territory; 81 in New South Wales; 63 in Tasmania; and 35 in Victoria (Bucher & Saenger 1989).

In an inventory of Australian estuaries, Bucher & Saenger (1989) have identified 5 (out of 15) estuaries under threat in South Australia (i.e. threat to fisheries and conservation values). These include: the Coorong, due to increasing salinity in the lower reaches of the Murray River, reduced flow and lower flood frequency; Port Adelaide River, due to poor water quality from pollution, and threat of adjacent urban and industrial development; Second Creek, Port Pirie, due to the threat from the nearby sewage treatment works; Port Pirie, due to run-off and discharges from shipping, residential and heavy industrial development; northern Spencer Gulf, due to potential poor water quality from port facilities, sewage treatment plant, power station and urban run-off from Port Augusta (see Table 6).

However, only 3 of these estuaries have been assessed as 'moderately' or 'considerably affected' ecologically by human activities: Port Adelaide River (considerably), the Coorong (moderately), and Port Pirie (moderately). Port Douglas (25-50% cleared) and Franklin Harbour (50-75% cleared) are also significant estuaries in that their catchments are the only catchments which are not 'intensively developed' (i.e. >75% cleared of native vegetation).

There is an urgent need for a state-wide wetlands policy in South Australia, as has been developed in New South Wales, Victoria and Western Australia (DELM 1993). Wetland management in South Australia is uncoordinated, with management being conducted on a project or regional basis. While recent activity has been concentrated in the Murray Valley and South East, areas such as the Eyre Peninsula, Yorke Peninsula, Mount Lofty Ranges, Flinders Ranges and Kangaroo Island remain neglected (DELM 1993).

Table 5: Inland waters of South Australia of outstanding environmental value recommended for status as Wetland Reserves

Region Environmentally important waters
Type Location
South east Swamps Marshes, Mt McIntyre perched swamps, Mt Lyons perched swamps, Lake Frome-Mullins Swamp, Sawpit Swamp
Lakes Bool Lagoon, Woolwash, Blue Lake
Rivers Eight Mile Creek (the only significant river in the whole region)
River Murray Swamps Opposite Cooinda, Complex N. of Swan Reach
Lakes Coorong, Lakes Alexandrina & Albert, River Marne mouth, Milang....Roonka, Irwin Flat, Chowilla Region
Rivers Tookayerta Creek, Dawson Creek, Finniss River, Marne River, River Murray Channel (none of the Murray's main channel is within a conservation park or reserve), Murray Mouth (including islands within Lake Alexandrina)
Gulfs Swamps Ducknest Ck Perched Swamps (FP), Myponga Swamp (FP), Peesey Swamp (YP), Grainger Lagoon (KI)
Lakes Big Swamp (EP), Lake Wangary (EP), White Lake (KI), Lake Ada (KI), Halls Rd. Salt Lake (KI), Cygnet River Billabongs (KI)
Rivers Little Para River (M), Tod River (EP), Harriet River (KI), Stunsail Boom River (KI), Cygnet River (KI)
Lake Eyre Enbarka Swamp, Tirrawirra Swamp, Coopers Creek, Mound springs - Francis Swamp, Mt Dennison, Billa Kalina, Neales River
Western Plateau Lake Newland, Lake Hamilton and Sheringa Lagoon.

Source: Lloyd & Balla (1986)

FP=Fleurieu Peninsula; M=Metropolitan; YP=Yorke Peninsula; EP=Eyre Peninsula; KI=Kangaroo Island

Table 6: The status of estuaries in South Australia (data from Bucher & Saenger 1989)

Estuaries F T C A E L Q W I M S
Coorong M P H M M I
310 <1 0 0
Port Adelaide River M P M H C I
3 12 17 13
Port Davis Creek M N M M S I
3 <1 2 10
Fisherman Creek M N M L S I
14 8 12 10
Third Creek L N L M S I
40 25 7 17
Second Creek M P M L S I
24 21 15 9
Port Pirie M P M H M I
1 7 8 13
Northern Spencer Gulf M P H H S I 3 2 6 12
Franklin Harbour M N M L S H
69 67 17
Port Douglas M N M L S M
119 <1 3
Venus Bay M N M L U I E 65 15 <1
Baird Bay L N L L U I E 45 0 0
Blanche Port M N M L U I E 32 7 3
Smokey Bay M N M L U I E 16 11 8
Tourville Bay M N H L U I E 16 42 13

F fisheries value [H=high, M=moderate, L=low]; T threat [R=real, P=perceived, N=none]; C conservation value [H=high, M=moderate, L=low]; A amenities value [H=high, M=moderate, L=low]; E ecological status [U=unaffected, S=slightly, M=moderately; C=considerably affected]; L land use [I=>75% developed, H=50-75%, M=25-50%]; Q water quality [E=excellent]; W area of water [sq.km.]; I intertidal flats [sq.km.]; M mangroves [sq.km.]; S samphires [sq.km.]

FISHERIES VALUE: Criteria considered include the importance of the estuary as a recreational or commercial fishing ground, significance as a breeding/nursery area for exploitable stocks, use or suitability for use as mariculture site and records of potentially exploitable stocks.

CONSERVATION VALUE: Criteria considered include the importance of the estuary as a scientific reference area (eg. representative example of a habitat type, a convenient study site, type locality, etc.), a remnant example of the natural condition in an otherwise developed area, its general habitat resources, educational value, unique habitat types, unusual communities, habitat for rare or endangered species, range limits and breeding/nursery grounds for fish, etc. other than commercial species.

Seagrasses

Seagrass beds are one of the important habitats within estuaries threatened by development (see review by Shepherd et al. 1989). Seagrass habitats in Australia, as elsewhere in the world, have been lost, fragmented and damaged through such practices as sewage discharges, urban run-off, dredging, boating, and land reclamation (Shepherd et al. 1989). In South Australia, sewage and stormwater discharges are thought to be responsible for the loss since 1935 of approximately 4000 hectares of seagrass off metropolitan Adelaide (Shepherd et al. 1989; Clarke & Thomas 1987; Neverauskas 1987a).

Seagrass meadows are particularly important for a number of reasons: as primary producers they occupy the base of the food chain; they provide important or 'critical' habitats such as nursery, breeding or feeding areas for the juveniles and adults of many fish, crustaceans and other marine animals, including a large number of commercial species (Bell & Pollard 1989; Howard et al. 1989); and their extensive root and rhizome systems stabilise nearshore sediments and sand banks, enhancing coastal water clarity and reducing coastal erosion (Scoffin 1971).

In South Australia there are extensive meadows of seagrass all along the metropolitan coast, Gulf St Vincent, Spencer Gulf, Backstairs Passage offshore from Robe on the south-east coast, and in bays along the western coast and Eyre Peninsula wherever suitable substrate occurs (Greenwood & Gum 1986). It is estimated that there are over 15 000 km2 of seagrass beds in Southern Australian waters (Greenwood & Gum 1986). As such, the seagrasses of South Australia (together with Western Australia) represent one of the largest temperate seagrass ecosystems in the world.

The sheltered gulf ecosystems of Gulf St Vincent and Spencer Gulf comprise the largest areas of seagrass in the state, providing the essential basis for many commercial and recreational fisheries and playing an important role in stabilising seabed sediments. However they are also the areas under greatest threat of increased urban and industrial development and consequently, land-based marine discharges. As mentioned previously, seagrass communities are particularly sensitive to the effects of sewage and stormwater discharges.

In addition, the effect of prawn trawling activities on seagrass habitats in both Gulf St Vincent and Spencer Gulf, although relatively uninvestigated, is likely to be considerable. A review of the marine scalefish fisheries in South Australia in 1991 concluded that prawn trawling had affected the ecology of the seabed by reducing diversity of animals and changing seabed characteristics (Rohan et al. 1991). Increased trawling in Hardwicke Bay appeared to correlate with reduced catches of King George Whiting. Further, studies both in Australia and overseas have demonstrated that bottom trawling activities result in significant modification or destruction of habitat, with resultant changes in the structure or composition of benthic communities (see Craik et al. 1990). The quantification of the physical and ecological impacts of fishing in South Australia should be a high priority area for future research.

Mangroves

In South Australia, mangrove forests are composed solely of one species, the Grey Mangrove, Avicennia marina var. resinifera. Mangrove forests occur at a number of sheltered sites on the South Australian coast and cover a total area of about 230 km2 (EPCSA 1988). The most significant stands occur near Ceduna on the West Coast, Franklin Harbour near Cowell, around the northern ends of Gulf St Vincent and Spencer Gulf, near Port Pirie and between Port Adelaide and Port Gawler (Butler et al. 1977).

In South Australia the removal of mangroves is controlled both by regulations under the Fisheries Act, 1971-1982, and also, the Harbours Act, 1936-1981, which controls the development of coastal land. However, mangroves are still under considerable threat in South Australia due to small, incremental losses. These losses arise from adjacent urban and industrial developments, such as the salt ponds and waste and landfill areas in the Port River estuary region which are preventing the natural landward colonisation of mangroves (Burton 1982) and also, changes due to predicted greenhouse effects (Ainslie 1988); from changes in terrigenous sediment flow which are altering the seaward colonisation of mangroves in the northern metropolitan area (Burton 1982); from trampling of seedlings and pneumatophores by recreational fishers in the Barker Inlet-Port River estuary and Port Gawler region; from the effects of the recent oil spill in upper Spencer Gulf; and north of metropolitan Adelaide, from the effects of drift seaweed and seagrass, smothering young seedlings and adult trees and preventing the recruitment of young plants (Edyvane 1991a; Connolly 1986). Together, these threats pose significant potential losses of mangroves in South Australia.

In addition, another eight areas of mangroves have been recognised as being subject to physical disturbance (from recreational activities and structural development): Arno Bay, Cowell, Whyalla South, Whyalla North, Port Augusta South, Port Pirie, Port Broughton, St Kilda. Another three areas are affected by possible leaching of contaminants from nearby tailings or slag-heaps: Port Augusta, Port Pirie South, Whyalla (Burton 1984). A monitoring program has been recommended at these sites. A system has been devised to monitor the condition of mangroves in South Australia and to detect and identify any areas undergoing stress (Burton 1984).

Saltmarshes

In contrast to mangroves and seagrasses habitats, it is only recently that the importance of supratidal saltmarshes to coastal fisheries and the functioning of estuarine ecosystems has been recognised (Morton et al. 1987; Boesch & Turner 1984; Blaber & Blaber 1980; Subrahmanyam & Coultas 1980; Haines 1979; Subrahmanyam & Drake 1975). As such, coastal saltmarsh communities are an important buffer zone between the terrestrial and marine environments and form an important habitat for both terrestrial and marine fauna. In South Australia, a number of plant species within them, such as Centrolepis cephaloformis (dwarf centrolepis), Halosarcia flabelliformis and Wilsonia spp. have a high conservation rating (DELM 1993).

Together, mangrove and saltmarsh communities along the South Australian coast total approximately 82 000 ha, with the largest communities occurring in Spencer Gulf (46 000 ha) and Gulf St Vincent (20 000 ha). Other substantial communities occur in lower Spencer Gulf (6 000 ha), on the west coast of Eyre Peninsula (9 000 ha) and on Kangaroo Island (7 000 ha) (DELM 1993). In South Australia, as elsewhere in Australia, saltmarshes are under considerable threat from agricultural, urban and industrial developments. Unlike mangroves, saltmarshes are presently afforded no legislative protection in South Australia.

In the Adelaide metropolitan and northern beaches area alone, some 80% of the original saltmarshes have been lost to land reclamation for salt pans and industrial development. The remaining saltmarshes in the area are presently under threat from the recently proposed Multi-Function Polis urban development (PPK Consultants 1992). Although saltmarsh communities in South Australia are highly diverse (D. Fotheringham, Coastal Management Branch, pers. comm.), no inventory has ever been conducted to determine the status of these communities in South Australia. This should be a high priority area for future research.

Rocky reefs

Status not known.

Key marine species under threat or significant in South Australia

With the exception of marine mammals, reptiles and birds, the status of most marine species in South Australia, as elsewhere in Australia, is generally poorly-known. In contrast, the status of our terrestrial fauna is relatively well-known (see Greenwood & Gum 1986). For terrestrial species, the offshore islands of South Australia are particularly important because they often contain relict species that were once common on the mainland, but now only remain on offshore islands.

While the status of many marine organisms is uncertain or unknown, a number of marine organisms, particularly mammals are legally protected. However, legislative protection of the species alone is not enough and should extend protection to include 'critical' habitats (i.e. nursery, breeding and feeding areas) and key ecological processes (such as upwellings and currents, water quality) which sustain these species.

Fishes

Knowledge of fish species in South Australia and their status is limited. There are 370 species of fish recorded from South Australian waters (Scott et al. 1974). Of these, some 77 species are utilised commercially, but only 20 contribute to most of the annual commercial fish catch (DELM 1993). Although no marine species is regarded as endangered, the status of the Southern Bluefin Tuna (Thunnus maccoyii) is of particular concern. Tuna catches declined from 14 000 tonnes in 1981 to 2 500 tonnes in 1991. The catch is now restricted to a quota at a level reflecting the real concern for the survival of this stock from overfishing (DELM 1993). Gummy and School Sharks (Galeorhinus australis) are also seriously overexploited. Although effort has increased over the 1980s, the stock has seriously declined. This is primarily because these species have been treated like 'fish', rather than 'sharks', with the assumption that they produce abundant offspring. Concern also exists over local depletions of Snapper (Pagrus auratus) in Gulf St Vincent, particularly the large individuals or 'megaspawners' which contribute significantly to the egg biomass.

In contrast to the status of marine fish, the status of river fish are of considerable concern. All of the South Australian fish species which are officially designated as 'rare', 'vulnerable', 'endangered' are freshwater species. Since 1988 an additional 15 species have been recorded for the State and a further 3 species have been rated as extinct (DELM 1993). In addition, two major freshwater fisheries in South Australia, Catfish and Murray Cod are considered 'overfished' (Commonwealth of Australia 1991). The Department of Primary Industries (Fisheries) has imposed a moratorium on the taking of Murray Cod as there has been no significant recruitment of this species since flood flows in 1973-75 (DELM 1993).

The infrequent failure of freshwater to flow through the Murray Mouth during dry years seems to prevent Mulloway (Sciaena antarctica) from spawning (Hall 1986). This can mean an absence of adult fish three years later, by which time they would normally have reached maturity and returned to the Murray to breed, and can therefore eliminate a whole season's catch of the fish. Fishing and gear restrictions have been introduced for this species and a decline in catch reported in 1988 is no longer evident (DELM 1993). No significant catches have been taken from the southern Coorong Lagoon in recent years. Due to the decline, measures have been introduced to prevent spawning stocks from being depleted to a level from which they cannot regenerate.

Some legal protection has been given to several marine species in South Australia, including the Leafy Seadragon (Phycodurus eques) which is completely protected. This unusual fish resembles the fronds of seaweed amongst which it lives. It is now completely protected in South Australia because demand for aquarium specimens threatened the species with extinction. The Blue Groper (Achoerodus gouldii), a large attractive reef fish which has been depleted by spear fishing activity, is protected within the gulfs but can still be caught and used as bait to catch other fish. There has also been recent proposals for complete protection of the Great White Shark (Carcharodon carcharius) (Rohan et al. 1992).

Marine mammals

A number of rare and endangered species of marine mammals are found in South Australian waters. There are 31 recorded species of marine mammals (seals, whales and dolphins) in South Australia and these are largely known from occasional sightings and stranded specimens. Although the international status of many marine mammals is known, there is generally inadequate data available to quantify the status of many marine mammals in South Australian waters (EPCSA 1988). Despite this, the occurrence of the two species of pinnipeds which occur in South Australian waters, the New Zealand Fur Seal (Arctocephalus forsteri) and the rare Australian Sea Lion (Neophoca cinerea), is relatively well documented. Both these species have significant breeding colonies in South Australia, with populations representing a major proportion of the world complement for both species. Although all whales, dolphins, porpoises and seals in Australian waters are completely protected under the Commonwealth Whale Protection Act 1980, there is a clear need to protect the key feeding and foraging areas of these mammals, in addition to their breeding areas.

Table 7: Breeding sites of Australian Sea Lions in South Australia (adapted from Robinson & Dennis 1988*; Gales 1990; T. Dennis, SANPWS pers. comm.#)

Breeding Island Pup Number Pup Production Population Estimate
(pup number x 5.09)
Western Nuyts Reef

Middle Nuyts Reef

Purdie Island

Fenelon Island

Small NE Franklin Is.

Olive Island

Jones Island

Ward Island

Liguanea Island

Albatross Island

North Islet Island

Peaked Rocks

English Island

Dangerous Reef (NW)

Dangerous Reef (SE)

Kangaroo Island

North Pages Island

South Pages Island

?

?

49

8

43

25

2

?

23

12

8

23

40

236

162

280

242

28

28

49

50

43

25

2

28

25

12

8

30

40

236

180

310

260

143

143

249

255

219

127

10

143

127

61

41

153

204

1 201

916

1 578

1 323

SA Islands
(% Australian)

Point Labatt *
Nullabor Cliffs#

707

1-3
90

1 354

180

6 892
(69%)

68-46
1 000
(10%)

Pinnipeds:

The Australian Sea Lion in particular is one of Australia's most endangered marine mammals and one of the rarest and most endangered pinnipeds in the world (Gales 1990). Prior to seal hunting, this species occurred along the whole of the southern coastline, but is now confined to the waters of South Australia and Western Australia. The estimated population of 6900 sea lions in South Australia represents approximately 69% of the estimated Australian or world population of 10 000 for this species (Gales 1990). Major breeding areas for sea lions in South Australia include the Pages, Dangerous Reef and Seal Bay, and Kangaroo Island (Gales 1990; Robinson & Dennis 1988). Point Labatt on western Eyre Peninsula remains the only and largest mainland breeding site for this species in the world. In South Australia, Australian Sea Lions have been recorded on a total of 69 offshore islands and reefs and three mainland sites (Robinson & Dennis 1988). A total of 18 offshore islands, particularly off the Eyre Peninsula, support breeding populations of sea lions and a further 18 islands have been identified as possible breeding sites (see Table 7).

New Zealand Fur Seals (Arctocephalus forsteri) are also well represented in South Australian waters, comprising approximately 22 600 individuals or 83% of the Australian population (Shaughnessy 1990). The major breeding colonies for this species occur on the Neptune Islands (the northern of the South Neptune Islands and the western of the North Neptune Islands), southern Kangaroo Island and Liguanea Island, which comprise approximately 13 800, 5800 and 2200 individuals, respectively (Shaughnessy 1990). In addition, the offshore islands in South Australia, particularly off the Eyre Peninsula (i.e. Sir Joseph Banks Group, Nuyts Archipelago and islands off the Jussieu Peninsula) comprise smaller but significant breeding and haul out sites for both these species. In South Australia, fur seals have been recorded on a total of 36 offshore islands and reefs and 14 sites on Kangaroo Island (Shaughnessy 1990). Of these, 11 have been identified as breeding sites (see Table 8).

As the New Zealand Fur Seal population increases in South Australia, interaction between fur seals and fishers can be expected to increase (Shaughnessy 1990). This will take the form of covert interaction (with boats and gear) and overt interaction (competition for common prey species). One outcome of the former is entanglement of fur seals in marine debris and incidental mortality of seals during fishing activity. Although the feeding areas of fur seals are not known, they spend a considerable proportion of their time either resting or traversing waters in the immediate vicinity of colonies. Therefore some of the adverse effects of the covert interaction between fishers and fur seals could be alleviated if marine reserves were declared in waters surrounding fur seal colonies. Such reserves should prohibit fishing activity, but it would be unrealistic to prohibit fishing vessels from using well established anchorages in the lee of fur seal colonies (Shaughnessy 1990).

Breeding populations of both Neophoca cinerea and Arctocephalus forsteri are highly susceptible to disturbance by humans (Gales 1990; Shaughnessy 1990). As such, affording breeding colonies prohibited area status has been recommended as the most straightforward method of protecting these colonies (Gales 1990; Shaughnessy 1990).

Whales:

Many coastal bay and inlets around South Australia are also popular sites for visits by the endangered Southern Right Whale (Eubalaena australis) (Ling & Needham 1991, Kemper et al. 1994b). In particular, the waters at the Head of the Great Australian Bight (and to a lesser extent, at the Merdayerrah sand patch) in the Nullabor Cliffs region, is the most significant breeding and calving site for this endangered species in Australia (S. Burnell, University of Sydney, pers. comm.). The Head of Bight region is also one of the few areas in the world where Southern Right Whales breed and nurse their young in an area that is within close proximity to shore and readily accessible to the general public. Estimates currently put the world population of Southern Right Whales at around 3000, with an estimated Australian population of 400-800 (see Bowker 1994; Stephensen 1993).

The Great Australian Bight region is also recognised as a significant seasonal habitat for many other species of rare and endangered marine mammals. At least 17 species of cetaceans have been recorded including Blue Whales, Sperm Whales, Minke Whales and Humpbacks (Kemper & Ling 1991).

Dolphins:

Two species of dolphin are commonly sighted in the coastal waters of South Australia, the Bottlenose Dolphin (Tursiops truncatus) and the Common Dolphin (Delphinus delphis), both of which have a cosmopolitan distribution.

Table 8: Estimates of New Zealand fur seals at breeding localities in South Australia, 1989-90 summer (from Shaughnessy 1990)

Locality Pup No. Population
Estimate
(pup no. x 4.0)
Cape Gantheaume (KI)

North Casuarina (KI)

Cape du Couedic (KI)

Kangaroo Island (other)

South Neptune Island

North Neptune Island

Liguanea Island

Little Hummock Island

Four Hummocks Island

Rocky (South) Island

Greenly Island

Ward Island

525

442

477

2

1 974

1 472

555

7

42

75

11

64

2 100

1 768

1 908

8

7 896

5 888

2 220

28

168

300

44

256

SA Population
(% Australian)
5 646 22 584
(83%)

KI-Kangaroo Island

Sea birds

The bird fauna is probably the best known of all the faunal groups in South Australia, owing largely to the efforts of many amateur ornithologists over the years. Information from this source is collated by the Royal Australian Ornithological Union at a national level, and by the State Museum and the South Australian Ornithological Association in South Australia. Despite this, the abundance and population trends of practically all species of sea birds breeding in Australia are not known (van Tets & Fullagar 1984).

There are six species of penguins and over 75 species of marine birds recorded from South Australia. Little is known of most species, the main exceptions being those species that nest and rear their young on land. The oceanic sea birds are the least well understood (Greenwood & Gum 1986). Information on the seasonal movements of birds has been gleaned from the ringing of chicks while still in the nest and the subsequent recovery of the rings when birds are washed up on the shore.

Of the six species of penguins which occur in South Australia, five species are considered 'occasional visitors'. As such, South Australia does not form an essential part of the range for these species. However one species of penguin, the Little Penguin (Eudyptula minor), commonly occurs on a number of islands and coastal and offshore regions, with a total of 21 breeding sites recorded in South Australia (van Tets & Fullagar 1984). This represents approximately 14% of the total number of breeding sites recorded for this species in Australia. Although the species is common in South Australia it has rarely been reported in the Head of the Bight region, which may reflect lack of observers as breeding occurs at the foot of the Nullarbor cliffs (Reilly 1974); many observations of Little Penguins have been between Victor Harbour and Port MacDonnell .

Two species of sea birds which may have been affected by human activities are the Osprey (Pandion haliaetus) and the White-Breasted Sea Eagle (Haliaetus leucogaster) for which there have been no known breeding records in the upper Spencer Gulf region since 1890 (Greenwood & Gum 1986). The Port Pirie lead and zinc smelter commenced operations in 1889. If the heavy metals released affected the survival of any species, those high on the food chain would be most likely to be in danger. It is possible that other factors may also be involved in the loss of these species of birds. The Osprey, previously rated as endangered in South Australia, have been upgraded to the less severe category of vulnerable (DELM 1993).

Marine reptiles

Three species of tropical and subtropical marine turtles are recorded from South Australian waters, the Loggerhead (Caretta caretta), the Green Turtle (Chelonia miydas) and the Leathery Turtle (Dermochelys coriacea). All three species have the major parts of their ranges in tropical and subtropical waters and individuals encountered in South Australia are likely to be vagrant individuals. Their status here is not known, but all are considered under threat on a worldwide basis, owing to human predation of adults and eggs, and disturbance of breeding beaches (Greenwood & Gum 1986).

Marine invertebrates

The status of invertebrates of economic importance (such as the Southern Rock Lobster, Western King Prawn and Green and Blacklip Abalone) are relatively well known in South Australia. Of the commercially-fished invertebrates, only the Western King Prawn is considered 'overfished' (Commonwealth of Australia 1991). However, the status of the remainder of the invertebrate fauna is poorly known in South Australia. In part this is due to the lack of taxonomic knowledge and research. Of the 6440 species estimated to occur in South Australian waters, only a third of these have been collected and described to date (EPCSA 1988). The crustacean and mollusc fauna is very diverse in South Australia, however less than half of the fauna has been described (W. Zeidler, SA Museum, pers. comm.). Some groups such as the jellyfish and echinoderms are well documented, however other groups such as sponges, acoelomate worms and plankton, are either variable in growth forms, small in size or belong to groups that are difficult to identify.

The lack of detailed taxonomic information and the lack of information on distribution and numbers, means that estimates of the status of many marine invertebrate species in South Australia is impossible. Many diverse groups of marine invertebrates produce few, large eggs and have small numbers of direct developing young and therefore may be expected to have extremely patchy and localised distributions. For these reasons, habitat rather than individual species protection is a more effective strategy for protection of marine invertebrate faunas.

The most pressing threat to marine invertebrates is habitat destruction resulting in extinction at the local or regional level. In South Australia, estuaries and bays near centres of population represent the major affected habitats. As such, the local loss of seagrasses, mangroves and saltmarshes is generally accompanied by local reduction or extinction of the marine invertebrates which inhabit these habitats. As in many parts of Australia, many edible intertidal invertebrates near large human population centres are now subject to over-exploitation at high levels unknown a few decades ago. In South Australia, uncontrolled harvesting of intertidal invertebrates for bait or food is common along the metropolitan Adelaide coast and is probably having a major local impact on these intertidal ecosystems. The extent of harvesting of intertidal organisms has not been investigated in South Australia.

Marine monitoring in South Australia

South Australia was the last State in Australia to legislate to control marine pollution from point sources. As such, the introduction of the Marine Environment Protection Act in 1990, occurred approximately 17 years after all other States in Australia (Rozenbilds 1991). The last State to introduce legislation before South Australia was Tasmania in 1973 when it passed it's Environment Protection Act.

The Marine Environment Protection Act 1990 requires the Minister to protect the marine environment and keep it's condition under review. Virtually all point sources of pollution (115) are now licensed, with conditions which require licensees to monitor their discharges and to reach guidelines values before the year 2001, or discontinue the activity. However, diffuse source pollution is not addressed under the act. Further, sea-based fish farming and areas of severe pollution such as the Patawalonga and Lake Bonney, are exempt under the legislation. Ambient marine monitoring is coordinated by a Marine Environment Protection Committee (MEPC). The MEPC has budgeted funds and sought co-operation of other State and Local Government agencies and research organisations to plan ambient monitoring of nutrients, faecal contamination, suspended particulates, exotic species and heavy metals in areas of known contamination. This reflects action priorities for South Australia, published in the 'State of the Environment Report'. Apart from license conditions requirements for the monitoring of point source discharges, no ambient marine monitoring programs have been established to date in South Australia. Existing marine monitoring programs are often irregular and generally inadequate (Rozenbilds 1991). Monitoring programs are principally outfall-based and often lack biological/ecological criteria (see Reichelt 1990 for an outline of environmental monitoring in South Australia).

Of particular concern is the significant lack of biological information on South Australian coastal marine ecosystems, specifically the distribution, nature and composition of subtidal benthic habitats. This baseline information is essential if the effects of pollution or coastal developments are to be assessed in monitoring programs. Both comprehensive marine faunal and floral surveys and detailed taxonomic studies (particularly of marine invertebrates) are required if the status of South Australia's coastal marine ecosystems are to be accurately monitored and assessed.

The regulatory provisions of the Marine Environment Protection Act 1990 will be taken up into integrated pollution management under the Environment Protection Act 1993 (DEP 1991). The newly established Environment Protection Authority has allocated a budget of approximately $150 000 for ambient marine monitoring in South Australia for 1993/94.

State of the environment reporting

A preliminary report for South Australia was issued in 1985 and was followed by more comprehensive reports in 1988 and 1993. The Environment Protection Act 1993 requires a further report every 5 years. A total of fifteen pages of the current report deal with the marine environment, including pollution, fishing and the conservation status of its flora and fauna. No specific environmental goals or monitoring guidelines (for example, physical indicators, biological indicators, sampling regimes) are indicated either for particular coastal areas or for particular coastal or marine habitat types.

Summary & conclusions

South Australia possesses a large range of coastal habitats and ecosystems; from the rough-water rocky habitats of the south-east and west coast, to the calm-water seagrass and mangrove habitats of the gulf regions. Threats to these environments and their fauna and flora result primarily from the effects of land-based pollution discharges, habitat loss through urbanisation and coastal developments, the effects of overfishing and conflict between competing user groups. These problems have resulted primarily from the lack of a national or state marine conservation strategy to provide a coordinated framework in which to protect South Australia's diverse coastal and marine ecosystems.

The two extensive gulf systems of Gulf St. Vincent and Spencer Gulf represent one of the largest, sheltered coastal ecosystems to be found anywhere in Australia, comprising one of the largest temperate seagrass ecosystems in the world (Shepherd et al. 1989). However the considerable level of human activity and the sheltered nature of these ecosystems have made them particularly vulnerable to the effects of pollution. This has resulted in a significant decline, since the 1960s, of the nearshore seagrass communities along Adelaide's metropolitan coast (due primarily to sewage and stormwater run-off) and more recently, in the loss of mangroves. In northern Spencer Gulf, seagrasses and mangroves, an essential ecological component of the commercial and recreational fisheries in the area, are under increasing pressure from the industrial activity in that region. This comes, in particular, from the continued industrial and urban discharges of Port Pirie and Whyalla and the threat of oil and chemical spills from shipping.

According to the State of the Environment Report for South Australia (DELM 1993), land-based pollution has a significant impact on the coastal areas of South Australia. Major areas of concern identified include the northern Spencer Gulf, the Port River, and the outfall areas of treated and untreated sewage along the Adelaide coast, Port Lincoln and the South East. In areas adjacent to intensive urban development, such as the city of Adelaide, pollution from stormwater run-off is a significant source of contaminants to offshore coastal waters (DELM 1993). While the levels of heavy metals in seawater appear relatively low and the levels of contamination of aquatic species with heavy metals are generally considered within defined standards, this assessment has recently been brought into question (Rozenbilds 1991). In a recent comprehensive review of marine pollution in South Australia, Rozenbilds (1991) has highlighted the lack of the scientific rigour of past studies; the lack of comprehensive monitoring of marine pollution, particularly biological monitoring; and the lack of monitoring of diffuse sources of pollution. In general, monitoring programs are limited and outfall-based. As such, very little is known of the effects of marine pollution on the coastal ecosystems of South Australia (Rozenbilds 1991).

The paucity of biological information, particularly the distribution, nature and composition of marine benthic habitats, is seriously limiting the accurate monitoring and assessment of the status of South Australia's coastal marine ecosystems and habitats. To this end, urgent baseline studies are required to document the range of habitats, their distribution, and identify key monitoring organisms. Taxonomic studies are also required for many marine invertebrate groups if local or regional species extinctions are to be detected.

However, while some localised instances of severe pollution do give cause for concern, the South Australian marine environment is overall, relatively unpolluted (Rozenbilds 1991). The main problem is currently nutrient enrichment, and is likely to remain so for the foreseeable future (Rozenbilds 1991). Stormwater run-off and sewerage effluent, as the major contributors to coastal eutrophication, are the probable issues of growing concern over time, while dinoflagellate blooms have the potential to become an increasingly significant and intractable problem. While their contribution to nutrient enrichment is likely to be negligible, the full ecological effects of sea-based aquaculture activities, such as caged tuna farming, and the effects of prawn trawling, have yet to be assessed.

In addition to marine pollution, overfishing by commercial and recreational fishers also poses a considerable threat to South Australia's aquatic resources. Three fisheries are considered to be 'overfished'; twelve are considered 'fully fished', seven are considered 'underfished', and five are of 'uncertain status' (Commonwealth of Australia 1991). Further, the status of knowledge for management is considered adequate for only 5 of 27 fisheries (i.e. 19%): Blacklip and Greenlip Abalone, Southern Rock Lobster, King George Whiting and Australian Salmon. The knowledge required for Ecologically Sustainable Development is considered adequate for only 2 fisheries in South Australia (i.e. 7%): Blacklip and Greenlip Abalone (Commonwealth of Australia 1991).

In South Australia, the sheltered gulf ecosystems are the major centres of urbanisation and industrial development, and are particularly prone to habitat loss. In these ecosystems, major areas of concern are: extensive seagrass loss and potential mangrove loss in the metropolitan area due to sewage and stormwater pollution; loss of saltmarsh and mangrove habitat due to urban and industrial developments; and damage to soft bottom benthos due to trawling activities.

Some habitats are of particular ecological importance in South Australia. Estuaries, for instance, worldwide are not only under considerable threat from human activities, but are also places of outstanding ecological importance. South Australia however, has the least number of estuaries of any state in Australia. For this reason they are of special importance to the state. Of the 15 estuaries in South Australia, it has been estimated that one third are either considerably altered or under threat (Bucher & Saenger 1989).

In addition to habitats, there are a number of rare and endangered species in South Australia which require specific management strategies. Of particular significance are two species of marine mammals: the rare Australian Sea Lion (Neophoca cinerea) and the endangered Southern Right Whale (Eubalaena australis). For both these species, South Australian waters represent the most significant breeding and calving sites in the world. While these species have legislative protection, there is also a clear need to protect the 'critical' habitats of threatened species, such as breeding and calving areas, and the key ecological processes which sustain these habitats.

South Australia's diverse marine and coastal ecosystems and their resources are of immense ecological, cultural and economic importance to South Australians. The adoption of both a coordinated approach to the management of marine resources and activities, and the preservation of the fundamental ecosystem processes and habitats which produce and maintain these resources, will be essential for the continued protection and conservation of the State's marine heritage, and also the economic welfare of the State's aquatic resource base.

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