Coastal and marine ecosystems
Surface water-groundwater interactions can play a significant role in coastal and marine ecosystems. Groundwater, often overlooked as an ecological agent in such systems, is able to discharge in several localities (see Connectivity examples). In many settings this discharge provides a ready source of freshwater in an otherwise saline environment, influencing the location and abundance of native flora and fauna such as certain rush, bird, turtle, fish, crocodile and macro-invertebrate species (Creswell 2000; Clifton and Evans 2001). A significant change in the level of this freshwater input, for instance by over-pumping of groundwater for agriculture, will therefore have serious impacts on such groundwater dependent species. Groundwater discharge can also be a key source of nutrients and diffuse pollutants to certain coastal settings. While natural nutrient inputs may be important for particular ecosystems, such as lagoons or near-shore reefs, an over or under supply can potentially disrupt the system. For instance, excessive nutrient inputs from industrial, agricultural and urban sources may encourage algal blooms and the loss of biodiversity (see Appleyard 2002). Other issues of concern include the ecological effect of seawater intrusion in coastal aquifers and the activation of acid sulphate soils by lowered groundwater levels (Clifton and Evans 2001).
Australia relies heavily on its coastal and marine systems for activities such as recreation, industry and tourism. Similarly, coastal aquifers are an important component of agriculture as well as drinking water supplies. Conjunctive water management is fundamental to both understanding the processes that support such activities and devising methods for ensuring sustainable resource use. Importantly, it ensures that the role of surface water-groundwater interactions in coastal and marine ecosystems is a focal point of coastal resource management.
Case Studies
Swan-Canning Estuary
Cockburn Sound
Leschenault Inlet
References
Appleyard SJ, 2002. Submarine groundwater discharge as an environmental agent in the Perth region, Western Australia. Proceedings of International Groundwater Conference, Darwin, May 2002. International Association of Hydrogeologists.
Clifton C, Evans R. 2001. Environmental Water Requirements of Groundwater Dependent Ecosystems. Environmental Flows Initiative Technical Report Number 2, Commonwealth of Australia, Canberra.
Cresswell ID. 2000. Ecological significance of freshwater seeps along the western shore of the Leschenault Intlet Estuary. Journal of the Royal Society of Western Australia 83(4): 285-292.