WetlandCare Australia Sponsors

 

Business Partners

Wetland Stuff for Schools

Issues that may impact on wetland viability

Ecosystem services provided by wetlands face a range of direct, indirect, immediate and longer-term impacts. Below is a range of factors that may impact on wetland viability, character and sustainability.

• Land reclamation for urban and tourism development or farming - many estuarine wetlands have been turned into canal housing estates.
• Construction of dams - large dams can reduce river flows, change flow rates and lower downstream water temperatures that impact on the lifecycles of wetland animals and plants. It also creates non-flowing habitat upstream of the dam.
• Land clearing and irrigation developments - can change water flow and water quality. It may also lead to rising water tables which bring salts to the surface, making freshwater wetlands brackish and the land unproductive. Removal of vegetation cover, including dead trees, results in loss of habitats and increases the rate of runoff and erosion of sediment, nutrients and agricultural chemicals.
• Pollution - sewage effluents contain plant nutrients such as phosphorus and nitrogen. Urban, agricultural and industrial runoff also contributes to nutrients in water. This can cause or increase the frequency of algal blooms including bluegreen algal blooms. High levels of algae discolour water, can smell and can be toxic.
• Introduced plants such as Salvinia, water hyacinth and alligator weed form mats which change the physical characteristics of wetlands, making them unsuitable habitat for some the original plants and animals.
• Poisons - agricultural and industrial chemicals may be trapped and concentrated in the food chain. Poisons reduce the diversity and abundance of aquatic life.
• Dredging and sand mining - these activities can seriously disrupt or destroy the physical characteristics of the wetland and the plants and animals in it. Often suspended sediments smother wetland habitat.
• Feral animals and stock - cattle and feral animals such as pigs, actively dig up and trample banks and destroy vegetation.
• Introduced fish - species such as trout, European carp and mosquito fish often displace native fish species.
• Global warming or greenhouse effect - may lead to significant changes in water levels and temperatures - which are likely to impact on wetland plants and animals in the longer term.