Jan Barton, Gerry Quinn, John Sherwood ( Deakin University, Warrnambool )

1. Developing methodology for assessing pressures on estuaries: relationships with catchment condition Jan Barton, Gerry Quinn, John Sherwood (Deakin University, Warrnambool)

2. Project background • Estuaries major foci of human activity • easily degraded • Major drivers of estuarine condition • upstream catchment modification • freshwater extraction • urban and coastal development • opening and closing of estuary mouths • Little information on relative importance of different drivers to estuarine condition

3. Project background • Restoration • environmental flows • longitudinal (upstream) & lateral (floodplain) connectivity • Restoration targets • commonly water quality, algal blooms, recreational fishing, waterbirds • other targets, such as ecological condition?

4. Project background • Two years NHT-funds through DSE • Deakin University to provide science underpinning management of estuaries • Jan Barton, Gerry Quinn, John Sherwood • only initial funding yet approved • commenced October 05

5. Aims • Identifying relationship between key pressures and rehabilitation tools and measures of ecological condition of estuarine environments • summarising measures (indicators) of both pressures on estuaries and condition or health of estuaries • assessment of effectiveness of relevant estuarine indicators • available datasets for Victoria’s estuaries • GIS-referenced database • validate cause-effect relationships between pressures and estuarine condition responses

6. Project overview • Literature review • Conceptual models • Data collation and analysis • Indicator development analysis • Testing cause-effect relationships

7. Literature review • Focus on links between estuaries and pressures & rehabilitation • Local, national and international literature • Build on Barton (2003) and Barton PhD • Strategic review (e.g. Lloyd et al. 2003): • directions of response to drivers • quantitative effect (response) sizes • methods (e.g. spatial comparisons, experimental) • indicators used

8. Relevant recent literature • USA • many recent papers relating biological & chemical characteristics of estuaries to surrounding watersheds (e.g. land-use) • estuaries different to Vic (generally permanently open, predictable flows) • South Africa • links between flow changes and biological condition of estuaries (focus on fish) • more comparable to Vic (size, flows)

9. Relevant recent literature • Australian • estuary classifications, estuarine fish (life cycles), nutrient cycling • little work linking estuaries to catchments, except Edgar et al. (Tasmania) • Focused on large estuaries (e.g. Chesapeake, Moreton, Port Phillip Bays) • little data on smaller, typical, representative, estuaries

10. Conceptual models • Ozestuaries (NLWRA) database • different models for different estuary types • models descriptive (pictorial), focus on materials rather than biota and interactions • Simple Estuarine Response Model (SERM) • generic (national?) allowing quantitative relationships • less applicable to smaller, intermittently open, estuaries • Little data available to populate or validate models • Requirement for models for local, smaller, estuaries • targeted data collection to fill key knowledge gaps

11. Data collation and analysis • Find and collate available data on Victorian estuaries • methodology for GIS-referenced database • summary measures of catchment, estuary and nearby coastal environment using most appropriate indicators • Classification of Victoria’s estuaries (again!?....) • following Edgar et al. (1999) for Tasmanian estuaries

12. Available data • Previous local summaries: • collations/theses by Deakin (Arundel, Matthews, Mondon, Pope, Sherwood) and Flinders (Barton, Fairweather, Hirst) • Other data • NLWRA habitat mapping (large-scale) • species lists within management plans • little on biota except fish (ARI, PIRVic) • EPA WQ monitoring • Barton PhD

13. Barton PhD • Data and field sampling for 31 estuaries in central and west Victoria • previously sampled for WQ by Vic EPA • Fine-scale geographic data collated • Some limited hydrology and mouth data available • Physico-chemical, nutrients, metals measured • Biota sampled • microbial, macroinverts, macroalga, microflora

14. Indicator development • Pressure indicators • amended Annual Proportional Flow Deviation • GIS mapping • vegetation change • land-use change metrics • Estuary response indicators • Barton PhD (following talk) • Cost-effectiveness of indicators? • Causal links between pressure and response indicators?

15. Cause-effect 1 • Spatial comparison across estuaries with different catchment characteristics, mouth opening/closing regimes etc. • broad-scale correlation • probably inadequate data available (esp. estuarine response) except….. • Barton PhD • 31 estuaries ranging from degraded (e.g. Curdies) through “pristine” (e.g. St George, Tidal Rivers)

16. Cause-effect 2 • Estuary responses to natural “pulse” disturbances • floods, droughts, mouth opening/closing, deoxygenation events • Targeted sampling before and after • Spatial comparison to “control” estuaries • too much-between estuary variation • comparable estuaries close so similar disturbances • Match mouth opening and catchment size across estuaries • Maybe east-facing estuaries along GOR

17. Cause-effect 3 • Evaluate response of estuaries to specific management actions • environmental flow releases (e.g. Coorong and Murray flows) • nutrient management schemes (e.g. regularly monitoring algal blooms) • estuary mouths artificially opened or closed (e.g. non-management action in Surry) • Management (ecosystem) experiments

18. Decision tools for managers • Estuary open/close decision support tool • Deakin (Arundel & Sherwood) • Risk assessment • Bayesian Decision Networks • VPSIRR • vulnerability – pressure – state – impact - risk and response • experience from DIPNR NSW, ANU (ICAM) and Coastal CRC (MODSIM conference)