icolls - Sustainable Tourism CRC
icolls - Sustainable Tourism CRC icolls - Sustainable Tourism CRC
ECOLOGY, THREATS AND MANAGEMENT OPTIONS FOR SMALL ESTUARIES AND ICOLLS a more brackish type estuary for about seven months of the year at present. This drastic change in the salinity regime represents a major change in habitat for the biota. The degraded present state was also caused by other anthropogenic influences such as a road across the salt marshes, seepage of saline water from mining activities and human disturbance of birds. It was therefore not possible to improve the health of the system through river flow adjustments alone. The Orange River Mouth was designated Ramsar status in 1991, but it was placed on the Montreux Record in 1995 due to its severely degraded state. The study concluded that it was critical to improve the current health status of the estuary through: •Managing the river flow so that it resembles the natural conditions more by eliminating the winter release to facilitate mouth closure during the low flow period and elevating the flows in autumn/summer to facilitate a more river dominated system. Mitigating actions to reverse modifications caused by the non-flow related activities and developments in the estuary by the responsible authorities. Title of paper: Wilson Inlet – A case example of seasonally closed estuaries in the SW of WA Author: Malcolm Robb Author's email: malcolm.robb@environment.wa.gov.au Abstract: Many of the estuaries along the south coast of WA are showing the symptoms of eutrophication ranging from annual phytoplankton blooms to choking growths of macroalgae. Estuaries in the high rainfall area are either permanently open or open seasonally from winter rainfall whereas those in the lower rainfall areas to the east open irregularly often in response to summer rainfall events. Wilson Inlet lies in the medium rainfall area and is artificially opened each year to manage water levels in the estuary. Over the last 10 years a range of studies has elucidated the key eutrophication processes linking catchment influences, sediment accumulations and the effect of marine exchange often in the context of vigorous community debate centred around the annual opening of the bar. Wilson Inlet is remarkably resilient to nutrient accumulations partly due to its size (45km2) and vigorous wind mixing. Denitrification efficiencies and phosphorus retention capacities are high and the extensive Ruppia megacarpa growth at the mouths of the influent rivers acts to absorb and attenuate the nutrient signal in the estuary. The transfer of process understanding from Wilson Inlet across the across the other estuaries of the south coast provides managers with guidance to estuarine response to eutrophication and suggests direction for management intervention. Ocean connectivity, timing of rainfall events and relative size of estuary are key drivers of estuarine response. The similarity and differences of these estuaries may throw light on the behaviour of ICOLLs elsewhere 64
ECOLOGY, THREATS AND MANAGEMENT OPTIONS FOR SMALL ESTUARIES AND ICOLLS REFERENCES Adams, J.B., Bate, G.C., Harrison, T.D., Huizinga, P., Taljaard, S., van Niekerk, L., Plumstead, E.E., Whitifled, A.K. & Wooldridge, T.H. (2002). ‘A method to assess the freshwater inflow requirements of estuaries and application to the Mtata Estuary, South Africa’. Estuaries, 25: 11382-1393. Alber, M. (2002). ‘A conceptual model of estuarine freshwater inflow management’. Estuaries, 25: 1246-1261. Alcorlo, P., Diaz, P., Lacalle, J., Baltanas, A., Florin, M., Guerrero, M. C. & Montes, C. (1997). ‘Sediment features, primary producers and food web structure in two shallow temporary lakes (Monegros, Spain)’. Water, Air and Soil Pollution, 99: 681-688. Allanson, B. R. (2001). ‘Some factors governing water quality of microtidal estuaries in South Africa’. Water SA, 27: 373- 386. Allanson, B.R. & Baird, D. (1999). Estuaries of South Africa. Cambridge University Press, Cambridge. Almunia, J., Basterretxea, G., Aristegui, J. & Ulanowicz, R. E. (1999) Benthic-pelagic switching in a coastal subtropical lagoon. Estuarine, Coastal and Shelf Science 49: 363-384. Alonso-Rodriguez R., Paez-Osuna F. & Cortes-Altamirano R. (2000). ‘Trophic conditions and stoichiometric nutrient balance in subtropical waters influenced by municipal sewage effluents in Mazatlan Bay (SE Gulf of California)’. Marine Pollution Bulletin, 40: 331-339. Anderson, D.M., Glibert, P.M. & Burkholder, J.M. (2002) ‘Harmful algal blooms and eutrophication: Nutrient sources, composition and consequences’. Estuaries, 25: 704-726. ANZECC (1999). Draft Australian and New Zealand Guidelines for Fresh and Marine Waters. Australian and New Zealand Environment and Conservation Council, Canberra. Ardisson, P.-L. & Bourget, E. (1997). ‘A study of the relationship between freshwater runoff and benthos abundance: A scale-oriented approach’. Estuarine, Coastal and Shelf Science, 45: 535-545. Arlinghaus, R. & Mehner, T. (2003). ‘Socio-economic characterisation of specialised common carp (Cyprinus carpio L.) anglers in Germany, and implications for inland fisheries management and eutrophication control’. Fisheries Research, 61: 19-33. Arthington, A.H., Burton, H., Williams, R. & Outridge, P.M. (1986). ‘The ecology of humic and non-humic dune lakes, Fraser Island, with emphasis on the effects of sand infilling in Lake Wabby’. Australian Journal of Marine and Freshwater Research, 37: 743-64. Arthington, A.H. & Marshall, C.J. (1999). ‘Diet of the exotic Mosquitofish, Gambusia holbrooki, in an Australian lake and potential for competition with indigenous fish species’. Asian Fisheries Science, 12: 1-8. Arthington, A.H. & Pusey, B.J. (2003). ‘Flow restoration and protection in Australian rivers’. River Research and Applications, 19 (5-6): 377-395. Arthington, A.H., Tharme, R., Brizga, S.O., Pusey, B.J. & Kennard, M.J. (2004). ‘Environmental flow assessment with emphasis on holistic methodologies’. In: Welcomme, R. and Petr, T. (Eds). Proceedings of the Second International Symposium on the Management of Large Rivers for Fisheries Volume II. FAO Regional Office for Asia and the Pacific, Bangkok, Thailand. RAP Publication 2004/17, pp. 37-65. Arthington, A.H. & Zalucki, J.M. (Eds) (1998). ‘Comparative Evaluation of Environmental Flow Assessment Techniques: Review of Methods’. LWRRDC Occasional Paper 27/98. Land and Water Resources Research and Development Corporation, Canberra, p.141. Balls, P.W., Macdonald, A., Pugh, K. & Edwards, A.C. (1995). ‘Long-term nutrient enrichment of an estuarine system: Ythan, Scotland (1958-1993)’. Environmental Pollution, 90: 311-325. Bayly, I.A.E. (1964). ‘Chemical and biological studies on some acidic lakes of east Australian sandy coastal lowlands’. Australian Journal of Marine and Freshwater Research, 15: 56-72. Bayly, I.A.E. (1980). ‘Estuaries and Coastal Lakes’. In: Williams, E.D. (Ed). An Ecological Basis for Water Resource Management. Australian University Press, Canberra, pp.388-394. Beaudoin, C.P., Prepas, E.E., Tonn, W.M., Wassenaar, L.I. & Kotak, B.G. (2001). ‘A stable carbon and nitrogen isotope study of lake food webs in Canada's Boreal Plain’. Freshwater Biology, 46: 465-477. Beck, M.W., Heck, K.L.J., Able, K.W., Childers, D.L., Eggleston, D.B., Gillanders, B.M., Halpern, B., Hays, C.G., Hoshino, K., Minello, T.J., Orth, R.J., Sheridan, P.F. & Weinstein, M.P. (2001). ‘The identification, conservation, and management of estuarine and marine nurseries for fish and invertebrates’. BioScience, 51: 633-641. Bedard-Haughn, A., van Groenigen, J.K. & van Kessel, C. (2003). ‘Tracing 15 N through landscapes: potential uses and precautions’. Journal of Hydrology, 272: 175-190. Bell, F.W. (1997). ‘The economic valuation of saltwater marsh supporting marine recreational fishing in the southeastern United States’. Ecological Economics, 21: 243-254. Bell, K.N.I., Cowley, P.D. & Whitfield, A.K. (2001). ‘Seasonality in frequency of marine access to an intermittently open estuary: Implications for recruitment strategies’. Estuarine, Coastal and Shelf Science, 52: 327-337. 65
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ECOLOGY, THREATS AND MANAGEMENT OPTIONS FOR SMALL ESTUARIES AND ICOLLS<br />
REFERENCES<br />
Adams, J.B., Bate, G.C., Harrison, T.D., Huizinga, P., Taljaard, S., van Niekerk, L., Plumstead, E.E., Whitifled, A.K. &<br />
Wooldridge, T.H. (2002). ‘A method to assess the freshwater inflow requirements of estuaries and application to the<br />
Mtata Estuary, South Africa’. Estuaries, 25: 11382-1393.<br />
Alber, M. (2002). ‘A conceptual model of estuarine freshwater inflow management’. Estuaries, 25: 1246-1261.<br />
Alcorlo, P., Diaz, P., Lacalle, J., Baltanas, A., Florin, M., Guerrero, M. C. & Montes, C. (1997). ‘Sediment features, primary<br />
producers and food web structure in two shallow temporary lakes (Monegros, Spain)’. Water, Air and Soil Pollution, 99:<br />
681-688.<br />
Allanson, B. R. (2001). ‘Some factors governing water quality of microtidal estuaries in South Africa’. Water SA, 27: 373-<br />
386.<br />
Allanson, B.R. & Baird, D. (1999). Estuaries of South Africa. Cambridge University Press, Cambridge.<br />
Almunia, J., Basterretxea, G., Aristegui, J. & Ulanowicz, R. E. (1999) Benthic-pelagic switching in a coastal subtropical<br />
lagoon. Estuarine, Coastal and Shelf Science 49: 363-384.<br />
Alonso-Rodriguez R., Paez-Osuna F. & Cortes-Altamirano R. (2000). ‘Trophic conditions and stoichiometric nutrient<br />
balance in subtropical waters influenced by municipal sewage effluents in Mazatlan Bay (SE Gulf of California)’. Marine<br />
Pollution Bulletin, 40: 331-339.<br />
Anderson, D.M., Glibert, P.M. & Burkholder, J.M. (2002) ‘Harmful algal blooms and eutrophication: Nutrient sources,<br />
composition and consequences’. Estuaries, 25: 704-726.<br />
ANZECC (1999). Draft Australian and New Zealand Guidelines for Fresh and Marine Waters. Australian and New Zealand<br />
Environment and Conservation Council, Canberra.<br />
Ardisson, P.-L. & Bourget, E. (1997). ‘A study of the relationship between freshwater runoff and benthos abundance: A<br />
scale-oriented approach’. Estuarine, Coastal and Shelf Science, 45: 535-545.<br />
Arlinghaus, R. & Mehner, T. (2003). ‘Socio-economic characterisation of specialised common carp (Cyprinus carpio L.)<br />
anglers in Germany, and implications for inland fisheries management and eutrophication control’. Fisheries Research,<br />
61: 19-33.<br />
Arthington, A.H., Burton, H., Williams, R. & Outridge, P.M. (1986). ‘The ecology of humic and non-humic dune lakes,<br />
Fraser Island, with emphasis on the effects of sand infilling in Lake Wabby’. Australian Journal of Marine and<br />
Freshwater Research, 37: 743-64.<br />
Arthington, A.H. & Marshall, C.J. (1999). ‘Diet of the exotic Mosquitofish, Gambusia holbrooki, in an Australian lake and<br />
potential for competition with indigenous fish species’. Asian Fisheries Science, 12: 1-8.<br />
Arthington, A.H. & Pusey, B.J. (2003). ‘Flow restoration and protection in Australian rivers’. River Research and<br />
Applications, 19 (5-6): 377-395.<br />
Arthington, A.H., Tharme, R., Brizga, S.O., Pusey, B.J. & Kennard, M.J. (2004). ‘Environmental flow assessment with<br />
emphasis on holistic methodologies’. In: Welcomme, R. and Petr, T. (Eds). Proceedings of the Second International<br />
Symposium on the Management of Large Rivers for Fisheries Volume II. FAO Regional Office for Asia and the Pacific,<br />
Bangkok, Thailand. RAP Publication 2004/17, pp. 37-65.<br />
Arthington, A.H. & Zalucki, J.M. (Eds) (1998). ‘Comparative Evaluation of Environmental Flow Assessment Techniques:<br />
Review of Methods’. LWRRDC Occasional Paper 27/98. Land and Water Resources Research and Development<br />
Corporation, Canberra, p.141.<br />
Balls, P.W., Macdonald, A., Pugh, K. & Edwards, A.C. (1995). ‘Long-term nutrient enrichment of an estuarine system:<br />
Ythan, Scotland (1958-1993)’. Environmental Pollution, 90: 311-325.<br />
Bayly, I.A.E. (1964). ‘Chemical and biological studies on some acidic lakes of east Australian sandy coastal lowlands’.<br />
Australian Journal of Marine and Freshwater Research, 15: 56-72.<br />
Bayly, I.A.E. (1980). ‘Estuaries and Coastal Lakes’. In: Williams, E.D. (Ed). An Ecological Basis for Water Resource<br />
Management. Australian University Press, Canberra, pp.388-394.<br />
Beaudoin, C.P., Prepas, E.E., Tonn, W.M., Wassenaar, L.I. & Kotak, B.G. (2001). ‘A stable carbon and nitrogen isotope<br />
study of lake food webs in Canada's Boreal Plain’. Freshwater Biology, 46: 465-477.<br />
Beck, M.W., Heck, K.L.J., Able, K.W., Childers, D.L., Eggleston, D.B., Gillanders, B.M., Halpern, B., Hays, C.G., Hoshino,<br />
K., Minello, T.J., Orth, R.J., Sheridan, P.F. & Weinstein, M.P. (2001). ‘The identification, conservation, and management<br />
of estuarine and marine nurseries for fish and invertebrates’. BioScience, 51: 633-641.<br />
Bedard-Haughn, A., van Groenigen, J.K. & van Kessel, C. (2003). ‘Tracing 15 N through landscapes: potential uses and<br />
precautions’. Journal of Hydrology, 272: 175-190.<br />
Bell, F.W. (1997). ‘The economic valuation of saltwater marsh supporting marine recreational fishing in the southeastern<br />
United States’. Ecological Economics, 21: 243-254.<br />
Bell, K.N.I., Cowley, P.D. & Whitfield, A.K. (2001). ‘Seasonality in frequency of marine access to an intermittently open<br />
estuary: Implications for recruitment strategies’. Estuarine, Coastal and Shelf Science, 52: 327-337.<br />
65
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