Draining and infilling

conceptual diagram of Draining and infilling threat

 Fish production
Contaminants
Change in tidal dynamics
Connectivity
Flow of contaminants
Increase in phytoplankton production
Habitat provision
Algal growth
Foodwebs
Nutrient cycling
Suspended sediment
Potential loss
Trophic structure
Increase in nutrient levels
Phytoplankton
  1. Removal of wetlands and vegetation will lead to the loss of associated habitat, food webs and nutrient cycling processes. Hydrological connectivity and therefore fish migration between the estuary and floodplain wetland pools will be reduced. This may impact on fish production. (Adam, 2002; Kennish, 2002; Sheaves, 2006)
  2. Reclamation can disturb acid sulphate and contaminated soils potentially allowing toxic levels of leachate to enter the waterway. (Birch and Taylor, 1999; Russell and Helmke, 2002; Clark and McConchie, 2004)
  3. The construction of hard surfaces over estuarine banks can cause changes in tidal dynamics. Clearing of riparian vegetation can result in a decline in water quality through increased turbidity, nutrient inputs and water flow. This modified hydrology and water and habitat quality can disrupt remaining wetland vegetation resulting in a decline of some species and the growth of other species that are suited to hard substrates (for example algae). (Munro et al, 1967; Edyvane, 1999; Davis and Froend, 1999; Kennish, 2002; Connolly, 2003; Lee, 2006)
  4. Turbidity can negatively impact on benthic vegetation and the food webs they support (Davis and Froend, 1999; Dennison and Abal, 1999; Hemminga and Duarte, 2000; Kennish, 2002)
  5. With more nutrients entering the system and less riparian and benthic vegetation to sequester them eutrophication may result, increasing the risk of harmful algal blooms (Prastka et al 1998; Edyvane, 1999; Davis and Froend, 1999; Dennison and Abal; 1999; Rassam, 2006)

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References

  1. Adam, P. 2002, Saltmarshes in a time of change, Environmental Conservation, 29 (1): 39-61. Birch, G., Taylor, S., 1999, Source of heavy metals in sediments of the Port Jackson estuary, Australia, The Science of the Total Environment, 227 (2) 123-138(16).
  2. Clark, M. W., McConchie, D. M., 2004, Development of acid sulfate soil in sub-aerially disposed dredge spoil at Fisherman Islands, Brisbane, Australia, Australian Journal of Soil Research, 42 (5-6): 553-567.
  3. Connolly, R.M., 2003, Differences in trophodynamics of commercially important fish between artificial waterways and natural coastal wetlands, Estuarine, Coastal and Shelf Science, 58 (4): 929-936
  4. Davis, J.A., Froend, R 1999 Loss and degradation of wetlands in southwestern Australia: underlying causes, consequences and solutions, Wetlands Ecology and Management 7: 13-23.
  5. Dennison, W.C, Abal, E.G., 1999, Moreton Bay Study: A Scientific Basis for the Healthy Waterways Campaign, South East Queensland Regional Water Quality Management Strategy, Brisbane, 246p.
  6. Edyvane, K.S. 1999 Coastal and marine wetlands in Gulf St. Vincent, South Australia: understanding their loss and degradation, Wetlands Ecology and Management 7: 83-104.
  7. Lee, S.Y., Connolley, R.M., Dale, P.E.R., Dunn, R.J.K., Knight, J.M., Lemckert, C.J., McKinnon, S., Powell, B., Welsh, D.T., Young, R., 2006, Impact of Urbanisation on Coastal Wetlands: A Case Study of Coombabah Lake, Southeast Queensland, UWA Project, Coastal CRC Report.
  8. Hemminga M.A., Duarte, C.M. 2000 Seagrass ecology. Cambridge University Press. Kennish, M.J. 1999 Coastal and marine wetlands in Gulf St. Vincent, South Australia: understanding their loss and degradation, Wetlands Ecology and Management 7: 83-104.
  9. Munro, C.H., Foster, D.N., Nelson, R.C., Bell, F.C. 1967 The Georges River hydraulic, hydrologic and reclamation studies, NSW University Water Research Laboratory Report No 101, 32 pg.
  10. Prastka, K., Sanders, R. and Jickells, T., 1998, Has the Role of Estuaries as Sources or Sinks of Dissolved Inorganic Phosphorus Changed Over Time? Results of a Kd Study, Marine Pollution Bulletin, Vol. 36, No. 9, pp. 718-728.
  11. Rassam et al, 2006 [in press]
  12. Russell, D.J., Helmke, S.A., 2002 Impacts of acid leachate on water quality and fisheries resources of a coastal creek in northern Australia, Marine & Freshwater Research, 53 (1): 19-33.
  13. Sheaves, M. 2006, [in press]

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