Threats to the Yalgorup Lakes System
There are three major threats to the sustainability of the Yalgorup Lake System:
- Urban development
- Climate Change
- Change in the quality and quantity of the Underground aquifer
The Yalgorup Lakes are a unique gift sitting right on our doorstep. They only require to be recognised, structured, harnessed and managed. The benefits this will bring to the State of Western Australia in both revenue from tourism and savings to the health and welfare budget, are immeasurable.
1 Urban development
85% of the original wetlands of Western Australia have been destroyed due to urban development and infrastructure. The Yalgorup Lake System is one of the largest remaining wetlands and, if destroyed, would have a significant adverse effect on the biosphere of the southwest.
The loss of the ecosystem services provided by the Lake System would be catastrophic. The potential to harness the cultural services provided by this area in education, recreation and spiritual and aesthetic appreciation have yet to be explored and expanded. The benefits these could bring to the health and wellbeing of Western Australians are immeasurable. For more information on ecosystem services, you might like to read our brochure or the presentation made by FRAGYLE to the International Union for Conservation of Nature.
Any urban development on the porous sand dunes would totally destroy the integrity of the ecosystem and threaten both the already endangered thrombolites and the Ramsar status of the wetlands.
Household and garden pollutants and contaminants would seep through the porous sands into the underground freshwater aquifer. This contaminated water would spread to the lakes and destroy the benthic microbial communities. These microbial communities are central to the formation of the thrombolites and the food source for the bird populations.
Pyrethrum, a natural insecticide, is used widely on pests in both house and garden and in dog shampoos for killing fleas and ticks. Pyrethrum is lethal to all aquatic life.
Pyrethrum alone seeping down through the sands into the aquifer and then into the lakes could exterminate all the benthic microbial communities in the lake system.
A large population of people, dogs and cats roaming freely over the area would destroy the shore nests of the plovers, the tree nests of the black cockatoos, disturb and disperse the feeding birds and trample and destroy the thrombolites both extant and extinct.
It would, in fact, destroy the whole ecosystem.
No commercial development whatsoever, should be allowed in this area of international, national and regional environmental value. An Ecological, Educational and Recreational Park incorporated in a Natural Health Clinic would be the only sustainable development that would ensure the continuation of the natural assets of the area while at the same time bringing health, wellbeing, enjoyment and fulfilment to all who visited it.
2 Climate Change
Over time the salinity of the water in each lake has changed according to the amount of freshwater entering from the underground aquifer, the temperature of the atmosphere and the annual rainfall. As the climate has changed over the thousands of years since their formation, so too, has the chemistry of each lake changed. As the evaporation rate of the surface has for a long period been greater than the recharge from rainfall the freshwater source from underground has played a major part in the salinity of each individual lake. Some lakes have a salinity of up to six times that of sea water at the end of summer. Lake Clifton, however, was hyposaline until 1991. The salinity of the water determines the makeup of the benthic microbial communities of each lake. The microbial communities form the thrombolites and feed the visiting birds. Since 1970 the average rainfall in the South West has reduced by nearly 50 per cent. This has meant less precipitation directly into the lakes and a reduction of the recharge of the superficial aquifer. The IPCC has predicted that the reduction in rainfall in the South West will continue over the next 50 years. 14 of the last 15 years have been the hottest on record. A combination of rising temperatures and rising evaporation and reducing rainfall and reducing aquifer recharge will result in increasing salinity in the eliminating the less salt tolerant microbes as they are pushed beyond their endurance limits. This will leave only the high salt tolerant microbes for the continued production of the thrombolites and feed for the visiting birds. To mitigate this it is essential that the level of the underground aquifer is not reduced in any way. All water extracted from the aquifer should be licensed and monitored.
3 Change in the quality and quantity of the Underground freshwater aquifer
Eutrophication is already causing severe problems to the thrombolites on the east side of Lake Clifton. Nutrients from the housing developments to the east of the Lake are seeping into the lake causing the growth of blue-green algae. The algae is smothering the thrombolites and excluding sunlight to the benthic microbial communities at the bottom of the Lake. The thrombolites are now a Federally recognised Ecologically Endangered community.
Should the level and depth of the aquifer be reduced the amount of fresh water seeping into the lakes will be reduced. This will affect the salinity of the Lakes and the endemic microbes. The visiting birds rely on the fresh water seeps around the Lakes for drinking. A reduction in the depth of the fresh water aquifer;
- increases the risks of contamination by salt water intrusion from the sea water below the fresh water lens;
- reduces the water available for the Tuarts causing them to be susceptible to disease
- reduces the amount of freshwater seepage at the side of the lakes for drinking water for the birds