Technical Report No. 27

Predicting change in condition of estuaries in : A description of the Landscape Logic Bayesian network

November 2010 Published by Landscape Logic, Hobart Tasmania, September 2010. This publication is available for download as a PDF from www.landscapelogicproducts.org.au

Cover photo: A Google Earth view of the Duck estuary, north-west Tasmania.

Preferred citation: Pollino CA (2010) Predicting change in condition of estuaries in Tasmania: A description of the Landscape Logic Bayesian network. Landscape Logic Technical Report No. 27, Hobart.

Contact: Dr Carmel Pollino, Australian National University, [email protected]

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LANDSCAPE LOGIC is a research hub under the Commonwealth Environmental Research Facilities scheme, managed by the Department of Sustainability, Environment, Water, Population and Communities. It is a partnership between: • six regional organisations – the North Central, North East & Goulburn–Broken Catchment Management Authorities in Victoria and the North, South and Cradle Coast Natural Resource Management organisations in Tasmania; • five research institutions – University of Tasmania, Australian National University, RMIT University, Charles Sturt University and NORTH CENTRAL Catchment Management CSIRO; and Authority • state land management agencies in Tasmania and Victoria – the Tasmanian Department of Primary Industries & Water, Forestry Tasmania and the Victorian Department of Sustainability & Environment. The purpose of Landscape Logic is to work in partnership with regional natural resource managers to develop decision-making approaches that improve the effectiveness of environmental management. Landscape Logic aims to: 1. Develop better ways to organise existing knowledge and assumptions about links between land and water management and environmental outcomes. 2. Improve our understanding of the links between land management and environmental outcomes through historical studies of private and public investment into water quality and native vegetation condition.

2 Landscape Logic Technical Report No. 27 Predicting change in condition of estuaries in Tasmania: A description of the Landscape Logic Bayesian network Carmel A. Pollino, Integrated Catchment Assessment and Management Centre, The Australian National University

Summary There are approximately 111 estuaries of moderate to large size on the Tasmanian mainland and the Bass Straight islands (Edgar et al 1999). Tasmania contains some of the most pristine estuaries in (DEWHA 2000), which come in a variety of types including coastal inlets, drowned river valleys, barrier estuaries, river estuaries and coastal lagoons (DPIW 2009). The diversity in estuaries is largely driven by differences in ‘wave energy and rainfall between the east and west coasts, a greater tidal range on the north coast and variation in local geomorphology’ (RPDC 2006). Small tidal ranges, high rainfall and high runoff are characteristic of catchments in the west, northwest and south, while those in the east and northeast are relatively much drier and possess greater tidal ranges (Edgar et al 1999). The Tasmanian Department of Primary Industries and Water (DPIW) have classified Tasmanian estuaries into 5 general types based on geomorphology (DPIW 2009):  Coastal Inlets (e.g. West Inlet, East Inlet): Enclosed marine embayments with wide mouths that lack large riverine inputs but have detectable reduction in salinity from small creeks after heavy rainfall. Coastal inlets are generally well mixed and can be hypersaline in summer.  Drowned River Valleys (e.g. Tamar Estuary, Derwent Estuary, Huon Estuary): Estuaries with wide river mouths, rocky headlands and deep channels. These estuaries can be stratified.  Barrier (or Bar) Estuaries: Estuaries with sandbars across their mouths. These estuaries can be per- manently-open (e.g. Prosser River, Ansons Bay) or seasonally-closed (e.g. Wanderer Estuary, ) and can be stratified.  River Estuaries (e.g. , ): Estuaries where fast flowing discharge into the sea with little bar or lagoon development and poor water mixing.  Coastal Lagoons (e.g. Grants Lagoon, Cameron Inlet): Saline lagoons with irregular input and infre- quent openings to the sea. Incursion by seawater generally occurs only after extreme runoff events or tidal or artificial breaching of the sand barrier. Can be hypersaline during summer periods. Estuarine environments are some of the most productive on earth, producing more organic matter than equivalent forest, grassland or agricultural areas (RPDC 2006). Tasmania’s estuaries provide an important shelter for many birds, fish and macrofauna, particularly during breeding and spawning. Most of the major cities and towns in Tasmania are situated on estuaries, utilising the significant cul- tural values offered by the water bodies, including fishing, swimming, tourism and aquaculture (DPIW 2009). Many commercially viable fish species depend on Tasmania’s estuaries at some point during their life cycle (RPDC 2006). In addition, many of Tasmania’s remaining aboriginal heritage sites are located along the shoreline of the states estuaries (DPIW 2009). Human intervention in and around Tasmania’s estuaries has caused significant deterioration of water quality, increased siltation and subsequent habitat loss (DPIW 2009). The unhealthiest of Tasmania’s estu- aries, relative to the rest of the state, tend to be located along the north coast with ‘elevated turbidity, nitrogen and phosphorus concentrations, particularly Duck Bay and Don River estuaries’ (Murphy et al 2003). Similarly, high nitrogen or chlorophyll concentrations were revealed in the north-east in Boobyalla Inlet, Little Musselroe River and Ansons Bay (Murphy et al 2003) making them susceptible to eutrophica- tion. Estuaries in the rest of the state are generally healthy, with the exceptions of Browns and Meredith River, and on occasion Douglas River (Murphy et al 2003). The presence of introduced species is a threat to many Tasmanian estuaries, as they can significantly alter habitat and alter the balance with these fragile marine environments (RPDC 2006). Vertical salinity stratification is a significant issue in Tasmanian estuaries, distinctly in river estuaries such as the large, deep estuaries on the west coast (Arthur and Pieman) and small, east coast river estu- aries (Douglas, Meredith, Browns and Catamaran) (Murphy et al 2003). Vertical stratification tends not to be an issue in open, marine inlets or shallow, low salinity estuaries (Murphy et al 2003).

Predicting change in condition of estuaries in Tasmania 3 Edgar et al. (1999) recognised nine major indirect threats to the ecosystem structure and function of Tasmanian estuaries. These were (i) increased siltation from land clearance and urban and rural runoff, (ii) increased nutrient loads from sewage and agricultural fertilisers, (iii) urban effluent, (iv) modifica- tion of water flow through dams and weirs, (v) marine farms, (vi) foreshore development and dredging, (vii) acidification and heavy metal pollution, (viii) introduced marine pests, and (ix) long-term climate change. Poor condition estuaries include the (RPDC 2006):  Derwent estuary which has heavy metal contamination, depressed dissolved oxygen and organi- cally enriched sediments.  Tamar estuary which is under considerable pressure from human activities urban and agricultural sources; and  where heavy metals in the estuary are sourced from Mt Lyell copper mine.

4 Landscape Logic Technical Report No. 27 Contents

Condition in Tasmanian estuaries 6 Description of the Tasmanian Estuary Model 9 Data Inputs 9 Model Outputs 9 Model behaviour 10 Sensitivity analysis by region 11 Predictions from Bayesian Network 18 References 19

Predicting change in condition of estuaries in Tasmania 5 Condition in Tasmanian estuaries

Condition metrics have been calculated for many  Modified: These estuaries are generally recog- Australian estuaries as part of the National Land nised and documented as having some problems and Water Resources Audit (NLWRA) conducted due to a complexity of impacts from within the in 2001. The NLWRA condition index was derived catchment, waterway and estuary. Remedial using physical characteristics (catchment natural works and activities for recovery may range from cover, land use, catchment hydrology, tidal regime, minor to substantial. floodplain, estuary land use) and estuarine ecol-  Largely unmodified: These estuaries are gen- ogy, including pests and weeds, as documented in erally recognised and documented as being in (NLWRA 2001). The condition metrics are reported good condition, but with some catchment and on the OzCoast website (http://www.ozcoasts.org. estuary use. au/). Estuaries are classified into one of the follow-  Near pristine: These estuaries are generally rec- ing categories: ognised as being in excellent condition, with  Extensively modified: These estuaries are management activities focused particularly on generally recognised and documented as hav- the protection of natural values. These estuaries ing multiple problems due to a complexity of are likely to provide baselines to judge the condi- impacts from within the catchment, waterway and tion of other estuaries. estuary. Remedial works and activities for recov- Condition values were obtained for the estuaries ery are likely to be substantial and may be cost shown in Figure 1. Estuaries highlighted in green prohibitive. correspond to Landscape Logic study estuaries.

Yellow Rock North East Inlet Sea Elephant Foochow Inlet Middle Inlet Patriarch Ettrick Mines Sellars Lagoon Yarra Cameron Inlet Pats Logans Lagoon Seal Mosquito Inlet Dover Lee Shag Rock Modder Thirsty Lagoon Montagu Rocky Head Duck Bay Rice East Inlet Tomahawk Crayfish Curries Little Musselroe Welcome Inglis Port Sorell Great Mussleroe West Inlet Blythe Arthur Black Boobyalla Ansons Bay Piper Brid Big Lagoon Nelson Bay Detention Little Forester Cam Sloop Lagoon Grants Lagoon Emu Mersey Pedder Leven Tamar Georges Bay Lagoon Forth Don Scamander Henderson's Lagoon Pieman Templestowe Douglas Great Swanport Denison Little Henty Meredith Saltwater Lagoon Henty Macquarie Harbour Stoney Freshwater Lagoon Buxton Bryans Lagoon Little Swanport Lisdillon Spring Bay Grindstone Hibbs Lagoon Prosser Spero Pittwater Carlton Wanderer Derwent Earlham Lagoon Mainwaring Browns Garden Island Blackman Bay Lewis Huon Giblin Crooks Mulcahy Port Cygnet Pipeclay Lagoon Payne Bay Esperence Cockle Ck North West Bay Bathurst Harbour Cloudy Bay Lagoon Lune Freney Southport Lagoon Louisa Ck South Cape Rt D`Entrecasteaux Louisa R. New River Lagoon Catamaran

Figure 1. Map showing Landscape Logic estuaries identified in green and other DSS estuaries identified in orange.

6 Landscape Logic Technical Report No. 27 All

Yellow Rock North East Inlet Sea Elephant Foochow Inlet NW Middle Inlet Patriarch Ettrick Mines Sellars Lagoon Yarra Cameron Inlet Pats Logag ns Lagoon Seal Mosquito Inlet Dover NE Lee Shag Rock Modder Thirsty Lagoon Montagu Rocky Headd Duck Bay Rice East Inlet Tomahawk Crayfish Curries Little Musselroe Welcome Inglis Port Sorell Great Mussleroe West Inlet Blythe Arthur Black Boobyalla Ansons Bay Piper Brid Big Lagoon Nelson Bay Detention Little Forester Cam Sloop Lagog on Grants Lagog on Emu Mersey Pedder Leven Tamar Georges Bay Lagoon Forth Don Scamander Henderson's Lagoon Pieman Templestowe Douglasg Great Swanport Denison Little Henty Meredith Saltwater Lagoon Henty Macquarie Harbour Stoney Freshwater Lagoon Buxton Bryans Lagoon Little Swanport Lisdillon Spring Bay Grindstone Hibbs Lagoon Prosser Spero Pittwater Carlton Wanderer Derwent Earlham Lagoon Mainwaring Browns W Garden Islanda Blackman Bay Lewis Huon Giblin Crooks Mulcahy Port Cygnetyg Pipeclay Lagoon E Payne Bay Esperence Cocklec Ck North West Bay Bathurst Harbour Cloudy Bay Lagoon Lune Freney Southport Lagoon Louisa Ck South Cape Rt D`Entrecasteaux Louisa R. New River Lagoon Catamaran

S

Near Prisne Largely unmodified Modified Extensively modified

Figure 2. Condition of the 56 estuaries (grouped by region)

Predicting change in condition of estuaries in Tasmania 7 likelihood of being near pristine (blue) than those in the east, where condition is more likely to be modified (green). This is reflected in TN concentra- tions (Figure 4), TP concentrations (Figure 5) and Turbidity (Figure 6). The Tasmanian Estuary Bayesian network also incorporates the ‘OzCoast Type’, which are divided into three categories: Wave Dominated, Tide Dominated and River Dominated. These divisions can be used to assess the various influences and affects of various factors on estuaries of the three different categories. Model predictions by type indicate that the River Dominated estuaries have undergone the most modification of the three groups Figure 3. Proportion of the 56 estuaries considered (Modified = 70%, Extensively Modified = 20%, Near In this study within each OzCoast Condition class. Pristine 10%), whereas Tide Dominated and Wave Dominated estuaries appear to have undergone The estuaries in orange relate to estuaries consid- similar, lesser levels of modification (Modified = ered in the model (described in the next section) 43%, Near Pristine = 33 and 25% respectively). but not studied as part of Landscape Logic. In total, Predicted versus actual condition for each estu- there are 56 estuaries. ary are reported in Table 2. A summary of the data sources obtained for Sensitivity analyses (against the variable: 'Condition each of the estuaries is shown in Table 1. Across relative to Ozcoast') are reported for the entire the 56 estuaries, almost half of the estuaries are in of Tasmania (Figure 8), and for the six regions: a modified condition. Approximately one third of the east (Figure 9), north east (Figure 10), north west estuaries are classified as being near pristine, one (Figure 11), south (Figure 12), south east (Figure 13) tenth are largely modified and the remaining estu- and west (Figure 14). Sensitivity analysis of all the aries are considered to be extensively modified. regions shows that the factors that are likely to have If we look at estuaries according to their loca- the most influence on the estuary condition vary tion, the conditions of estuaries vary intuitively with between regions (as indicated by the importance development across the state. of the variable 'Estuary'). Ranking of importance of Estuaries located in the west have a higher other factors were quite variable.

8 Landscape Logic Technical Report No. 27 Figure 4. Probability of being in a Turbidity range for each region in Tasmania.

Figure 5. Probability of being in a TN concentration range for each region in Tasmania.

Figure 6. Probability of being in a TP concentration range for each region in Tasmania.

Predicting change in condition of estuaries in Tasmania 9 Description of the Tasmanian Estuary Model

Using data from the 56 estuaries, an estuarine condi- The variable 'Change in condition' is used to tion model was constructed (Figure 7). The model is determine the relative change to the OzCoast designed to look at the shift in condition of the estu- condition, as reported on the OzCoast database, ary, given changes in water quality. Hydrodynamics relative to the predicted condition. Is the condition are only handled very coarsely in the model. The lower, higher or not changed. focus of hydrodynamics in the estuary BN is on flush- Dissolved oxygen is reported as an output in ing of the estuary, to relate the 'Vulnerability' of the the estuary BN, where it is linked to chlorophyll. estuary to water quality changes. Hydrodynamics However, monitoring data obtained was not pow- are not linked to water quality variables, this is han- erful enough to derive a relationship between dled through the Water Quality Simulator. these variables. This aspect of the model should The Tasmanian Estuary model has been created be improved before the outputs are used with any using the modelling platform Bayesian Networks. confidence. Bayesian Networks are probabilistic graphical mod- Likewise, seagrass is also on output, but the data els. The models comprise a series of interconnected for seagrass was restricted to only a select few estu- nodes and arcs (or arrows), incorporated with prob- aries, and the causality relationships for changes in ability tables. Probabilities are used to describe seagrass area were not available. Seagrass is also the strength of the relationships between vari- quite variable, and is not necessarily present in all ables. Bayesian networks can be used to integrate estuaries, thus it's use as a broad indicator of estu- different sources of information, and being probabi- ary health is questionable. listic, uncertainties are represented with predictions. Bayesian networks are becoming increasingly Model behaviour popular tools for use in ecological and adaptive To assess the behaviour of the estuary model, sensi- management. For a full description of Bayesian net- tivity analyses are reported by region. works, see (Pollino and Henderson 2010). Broadly, sensitivity analysis is a type of tool that The Tasmanian estuary Bayesian Network is can be used to explore the behaviour of complex a model embedded with the Tasmanian Aquatic models. It allows us to study how the variation (or Condition Decision Support System (DSS). The uncertainty) in the output of a model can be appor- Bayesian network links to the water quality simulator tioned to different sources of variation in the input of in the DSS, and allows you to run land use scenarios a model. Through sensitivity analysis, we can begin for the Landscape Logic catchments. to identify which variables in our models have the greatest influence on our model endpoints, as well Data Inputs as ordering the importance, strength and relevance The data inputs and model parameterisation meth- of the inputs in determining the variation of the ods are described in Table 1. output. Sensitivity assessment begins with sensitivity Model Outputs analysis but extends it to examine which hypothe- The estuary model has two assessment end- ses about model substructures are consistent with points: Vulnerability Index – Buffering Capacity and observations of system behaviours and knowl- Change in condition (condition relative to OzCoast). edge about the system. It allows one to attempt to The vulnerability index (buffering capacity) rep- discriminate between alternative, outcome-sensi- resents the ability of the estuary to withstand threats tive representations in the model and/or to identify to its health. The vulnerability index can be one or a where new information is required to assist that dis- mixture of four states: Poor Low, Low Fair, Fair Good, crimination. It is a powerful tool in model testing and and Good Excellent. simplification.

10 Landscape Logic Technical Report No. 27 26.2 7.50 50.1 16.2 Predicted condition 5.99 94.0 .009 0.73 6.96 25.4 66.9 12.8 12.5 20.0 54.7 Est_Chl_a Estuary Condition: Predicted Condition: Estuary Near Pristine Largely Unmodified Modified Extensively Modified DO - Trophic status - DO Condition relative to OzCoast to relative Condition Reduced No change Increased Change in condition Anoxia Hypoxia Stress Okay Hypereutrophic High Medium Low 17.7 37.2 34.6 10.4 11.4 42.0 33.0 13.6 59.5 22.4 18.1 49.5 37.8 12.7 52.4 9.30 38.3 Est_N Seagrass area Diversity_Macro Abundance_Macro Rel_Diversity_Fish 0.8 to 2.4 to 0.8 2.4 to 5 13 5 to 0 to 85 0 to 350 85 to 940 350 to 2 to 17 2 to 34 17 to 57.5 34 to 120 to 57.5 0.125 to 12.0667 44.5 to 12.0667 44.5 to 150 322 150 to 0 to 100 300 100 to 1000 300 to 44.9 17.9 37.2 23.9 19.7 43.4 13.1 23.2 21.7 27.7 27.3 Est_TN Est_TP 54.4 25.2 20.4 Salinity Est_Tu 0 to 10 20 10 to 45 20 to 80 45 to 0 to 400 1200 400 to 1500 1200 to 0 to 30 0 to 30 to 60 60 to 180 200 180 to 0 to 2 10 2 to 36 10 to 11.0 31.0 36.6 21.3 10.7 29.8 29.8 29.8 Time estuary closed to ocean, Co ocean, to closed estuary Time 1 to 2 2 to 3 3 to 4 4 to 5 Vulnerability Index- Buffering capacity Buffering Vulnerability Index- Poor Low Fair Low Good Fair Good Excellent 67.2 19.9 11.0 1.41 0.49 28.2 17.1 9.64 14.3 30.7 0.49 1.41 11.0 19.9 67.2 Est_no 0.53 5.87 23.5 70.1 Tidal prism, Tp Mixing index, Mi index, Mixing 1 2 3 4 5 1 to 2 2 to 3 3 to 4 4 to 5 Stratification potential 0 to 1 1 to 2 2 to 4 4 to 8 856.934 8 to 0 to 1 0 to 10 1 to 25 10 to 100 25 to 100 to 3136.98 5.19 10.6 10.2 6.92 67.1 RT_transform 26.8 8.93 48.2 16.1 1 2 3 4 5 Ce 4.29 16.8 13.2 34.7 31.0 1 2 3 4 5 Condition: OzCoast database Current condition Current 11.4 36.4 38.2 6.07 7.86 71.4 16.1 8.93 3.57 Near Pristine Largely Unmodified Modified Extensively Modified 31.0 34.7 13.2 16.8 4.29 67.1 6.92 10.2 10.6 5.19 69.6 30.4 Bar Est water area 89.3 10.7 Tidal Range Tidal River_flow_input Residence Time Residence 0 to 1.7 0 to 3 to 1.7 4.925 0 to 4.925 to 43.15 43.15 to 120 291.7 120 to Coastal exchange, Ce exchange, Coastal No Yes 0 to 1 10 1 to 10 to 35 35 to 70 200 70 to 10 0 to 10 to 20 20 to 30 30 to 40 100 40 to 6.094 to 14.0474 to 6.094 14.0474 to 87.89 973.939 to 87.89 1692.25 to 973.939 4224.42 to 1692.25 53.6 28.6 17.9 Type_OzCoast 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 1.79 10.7 Wave dominated Wave dominated Tide dominated River 17.9 10.7 28.6 5.36 16.1 21.4 Region Estuary E NE NW S SE W Estuary 36.3 38.1 25.6

Type_SERM Figure 7. Ansons Bay Ansons River Arthur Bathurst Harbour Blackman Bay Brid River Carlton River Cloudy Bay Lagoon Derwent River Detention River Don River River Douglas Duck Bay Earlham Lagoon InletEast Esperance River Bay Georges Giblin River River Musselroe Great Inglis River Lewis River River Little Forester River Henty Little Little Musselroe River Swanport Little Mainwaring River Harbour Macquarie River Meredith River Mersey Montagu Inlet Mosquito Nelson River Bay New River Bay Payne Pedder River Pieman River Water Pitt Sorell Port River Prosser Scamander River Lagoon Southport River Spero other-

Lagoon Tidal Saltwedge Estuary BN

Predicting change in condition of estuaries in Tasmania 11 Sensitivity analysis by region

Figure 8. Sensitivity of the 'Condition relative to Ozcoast' variable for the entire 56 Tasmanian estuaries represented in the estuary BN.

12 Landscape Logic Technical Report No. 27 Figure 9. Sensitivity of the 'Condition relative to Ozcoast' variable for the eastern Tasmanian estuaries represented in the estuary BN.

Predicting change in condition of estuaries in Tasmania 13 Figure 10. Sensitivity of the 'Condition relative to Ozcoast' variable for the north-eastern estuaries represented in the estuary BN.

14 Landscape Logic Technical Report No. 27 Figure 11. Sensitivity of the 'Condition relative to Ozcoast' variable for the north-western estuaries represented in the estuary BN.

Predicting change in condition of estuaries in Tasmania 15 Figure 12. Sensitivity of the 'Condition relative to Ozcoast' variable for the southern estuaries represented in the estuary BN.

16 Landscape Logic Technical Report No. 27 Figure 13. Sensitivity of the 'Condition relative to Ozcoast' variable for the south-eastern estuaries represented in the estuary BN.

Predicting change in condition of estuaries in Tasmania 17 Figure 14. Sensitivity of the 'Condition relative to Ozcoast' variable for the western estuaries represented in the estuary BN.

18 Landscape Logic Technical Report No. 27 Predictions from Bayesian Network

The Estuary BN allows users to create scenarios for Scenario 2 shows the Black River Estuary in near specific estuaries, regions, or types of estuaries, pristine condition prior to any intervention (Figure and establish the effect these scenarios will have on 16a), but in a modified to extensively modified state their selection of choice. Figures 15 and 16 show two once the hypothetical change of land use to mixed hypothetical examples of scenarios from the estuary agriculture scenario has been run (Figure 16b). model and the resulting predictions. These predic- tions are NOT based on the WQ Simulator, changes were made directly within the BN.

Scenario 1 shows that the condition of the Ansons  Near_Pristine  Largely_Unmodified Bay estuary will change from a modified state 1.00 (Figure 15a) to extensively modified in part with the  Modified  scenario increase in rain fed dairy (Figure 15b). Extensively_Modified

(a)

 Near_Pristine  Largely_Unmodified 1.00  Modified  Extensively_Modified 0.36  Near_Pristine  Largely_Unmodified 0.62  Modified (a)  Extensively_Modified

(b)

 Near_Pristine  Largely_Unmodified Figure 16. Black River Estuary: (a) Current condition, 0.50 0.50  Modified (b) Condition assuming water quality distributions  Extensively_Modified are similar to the Don River (i.e. increase in mixed agriculture)

(b)

Figure 15. Ansons Bay: (a) Current condition, (b) Condition assuming water quality distributions are similar to the Montagu (i.e. there is an increase in rainfed dairy)

Predicting change in condition of estuaries in Tasmania 19 References

Department of Environment, Water, Heritage and the Arts National Heritage Trust, February 2003 (DEWHA)(2000). Estuary Assessment 2000: Tasmania, NLWRA. 2001. Australian Estuaries and Coastal Waerways: Australian Natural Resource Atlas, URL: http://www.anra.gov. A Geoscience Perspective for Improved and Integrated au/topics/coasts/estuary/tas/index.html, accessed 13th May Resources Management. Canberra: A Report to the National 2010 Land and Water Resources Audit. Department of Primary Industry and Water (DPIW) (2009). Pollino CA, Henderson CH. 2010. Technical Report no. 14. Estuaries, Tasmania’s Water Resources, URL: http://www.dpiw. Bayesian networks: A guide for their application in natural tas.gov.au/inter.nsf/WebPages/RPIO-4Y34MG?open resource management and policy. CERF Hub: Landscape Edgar G.J. & Graddon, D.J. (1999). Conservation Significance Logic using Ecological and Physical Resource Planning and Development Commission (RPDC)(2006). Attributes, Population and Land Use, Marine Research Values: what do we need to sustain, State of the Environment Laboratories, October 1999 Tasmania, URL: http://soer.justice.tas.gov.au/2003/sus/8/ Murphy, R.J., Crawford, C.M. & Barmuta, L. (2003). Estuarine issue/107/ataglance.php, accessed 15th July 2010 Health in Tasmania, Status and Indicators: Water Quality,

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