Adelaide Coastal Waters Study

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Seagrass [posidonia sinuosa] in flower [photo: DEH]

Recommendations

The study has fourteen recommendations, of which the first five are focussed on the reduction of inputs to Adelaide's coastal waters.

Recommendation 1

As a matter of priority, steps must be taken to reduce the volumes of wastewater, stormwater and industrial inputs into Adelaide's coastal environment. This should be done within the context of an overarching strategy designed to remediate and protect the metropolitan coastal ecosystem.

Recommendation 2

The total load of nitrogen discharged to the marine environment should be reduced to around 600 tonnes per annum (representing a 75% reduction from the 2003 value of 2400 tonnes).

Recommendation 3

Commensurate with efforts to reduce the nitrogen load, steps should be taken to progressively reduce the load of particulate matter discharged to the marine environment. A 50% load reduction (from 2003 levels) would be sufficient to maintain adequate light levels above seagrass beds for most of the time. The reduced sediment load would also contribute to improved water quality and aesthetics.

Recommendation 4

To assist in the improvement of the optical qualities of Adelaide's coastal waters, steps should be taken to reduce the amount of CDOM (coloured dissolved organic matter) in waters discharged by rivers, creeks and stormwater drains.

Glenelg sewage outlet

Recommendation 5

While the available data suggests that toxicant levels in Adelaide's coastal waters pose no significant environmental risk, loads from point sources such as the Port River, wastewater treatment plants, and drains should continue to be reduced. Routine monitoring of toxicant loads and concentrations should be undertaken every 3-5 years.

Recommendation 6

Develop and implement a comprehensive and integrated environmental monitoring program that will enable natural resource managers and all stakeholders to evaluate changes in the coastal marine environment over time and at various spatial scales.

Recommendation 7

Maintain and develop the comprehensive database of historical inputs generated by this study. It is suggested that a single entity be created to oversee the administrative functions associated with data collection, storage/ retrieval, analysis, and reporting. This entity should also assume responsibility for the ongoing maintenance and application of the various models produced by ACWS so as to ensure that they remain both relevant and accessible. Consideration should also be given to the establishment of a research / monitoring coordination body. A primary function of this body would be to prioritise ongoing and future research activities and to seek and allocate funding in accordance with these priorities.

Recommendation 8

Implement a long-term monitoring program to assess seagrass quality (or 'health') at sites adjacent to land-based discharges and at suitable reference sites.

Recommendation 9

Implement a long-term monitoring program of the outer depth margin of Posidonia meadows in Holdfast Bay.

Recommendation 10

Implement a long-term monitoring program of seagrass meadow fragmentation at a range of sites in Holdfast Bay.

Recommendation 11

Undertake detailed mapping of the distribution of Amphibolis across the Adelaide metropolitan area, determine the lower depth limit of seagrasses in Holdfast Bay, and map seagrasses in the southern metropolitan area between Seacliff and Sellicks Beach.

Recommendation 12

Undertake a spatially intensive nitrogen stable isotope survey to determine the offshore and northern extents of nitrogen influence from WWTP (waste water treatment plants) and industrial outfalls along the Adelaide metropolitan coastline, and also characterise nitrogen stable isotope signatures of potential nitrogen sources.

Recommendation 13

Undertake an audit of key environmental assets in the southern metropolitan coastal region; identify risks to those assets and develop an integrated management plan to mitigate the risks. The applicability of management actions developed in response to the findings of this study to halt and reverse ecosystem degradation in the northern regions should be investigated with a view to adopting it (possibly with modification) in the southern region.

Recommendation 14

Adelaide's coastal marine environment must be managed as a component of a system that integrates catchment management, urban and rural land use, demographics, urban and industrial development, climate change / climate variability and water re-use.

Source: Adelaide Coastal Waters Study: Final Report Volume 1 - Study Findings

This page was last modified 03-03-2008