Lake Clifton thrombolites declared a critically endangered community

 
Well are they dead or are they alive? There have certainly been considerable changes in the microbial communities in the thrombolites in the last 10 years. Yesterday the Lake Clifton thrombolites were listed as critically endangered under the Federal EPBC Act under the following criteria

  • Criterion 2 as critically endangered because its geographic distribution is very restricted and the nature of its distribution makes it likely that the action of a threatening process could cause it to be lost in the immediate future;
  • Criterion 3 as critically endangered because the loss or decline of functionally important species is very severe;
  • Criterion 4 as critically endangered because the reduction in integrity of critical ecological processes is very severe; and
  • Criterion 5 as endangered because the rate of continuing detrimental change is severe and is projected to continue in the immediate future.

“The Lake Clifton thrombolite community is subject to numerous threats, most of which originate outside the ecological community itself. Scientific research suggests that there has been significant environmental degradation at Lake Clifton since at least the early 1990s (Moore, 1990; WA CALM, 2004a). This is despite the Peel-Yalgorup System being recognised as a wetland of international importance, and Lake Clifton being situated within the Yalgorup National Park (Moore, 1990).

…the thrombolite community occupies much of the eastern edge of Lake Clifton, which in turn forms the eastern boundary of the Yalgorup National Park. This means that the thrombolites are adjoined by private rural and rural-residential land holdings, which contributes significantly to the level of threat they face (Moore, 1990). The vegetation buffer zone between these properties and the foreshore of Lake Clifton is considered inadequate (Davies and Lane, 1996). The greatest current threat to the ongoing growth and survival of the Lake Clifton thrombolite community appears to be increased salinity due to increased groundwater extraction and altered groundwater flows, followed by increased nutrient levels coming from adjacent agricultural and rural-residential properties. If Lake Clifton becomes permanently hypersaline, it is likely that the patterns of thrombolite growth, faunal diversity and waterbird useage will also be affected. It is possible that the international scientific significance of the Lake will also be lost as a direct result (Knott et al., 2003). Current studies suggest that the change to a permanent state of hypersalinity may have already occurred (Alexander and John, 2008a).

Pollution, changes to surrounding vegetation, sedimentation and the introduction of fauna not native to the area also negatively impact on the ecological community (WA CALM, 2004a). People visiting Lake Clifton also directly impact by crushing or trampling the thrombolite structures, which are very fragile. Finally, possible impacts of climate change must also be considered.”

http://www.environment.gov.au/cgi-bin/sprat/public/publicshowcommunity.pl?id=96&status=Critically+Endangered

3 thoughts on “Lake Clifton thrombolites declared a critically endangered community”

  1. Hi,
    As I understand it stromatolites grow in those few areas where they have been naturally protected from grazing predators and Hamelin Pool (Shark Bay), being hypersaline is one of those areas. But what is the reason thrombolites exist in fresh water where I would have thought grazers would also exist? Will keep googling, but if you know the answer would be much appreciated.
    Cheers,
    Peter Lane
    Margaret River

    1. Grazing has certainly been put forward as the reason why stromatolites are found at Hamelin Pool but it may not be the key factor. High salinity (and less grazers) are found other salt lakes around WA like at Rottnest and Lake Thetis. However microbialites are found in less secluded shallow ocean waters in the Bahamas (with presumably no limits on marine grazers). Also until recently Lake Clifton was brackish and not saline so salinity is not the primary reason either. When you have a lake the vital conditions seem to be low nutrient levels (Nitrogen and Phosphorus) and groundwater high in calcium carbonate*. Low nutrient levels may do something like knock out algae (as competitors).

      Sometimes (in cases such as Lake Walyungup) high magnesium carbonate seems to have allowed the stromatolites for form. I think I read there is another place in Turkey where the structures are formed from magnesium minerals and not calcium. I found Ken McNamara’s updated book on stromatolites helpful (available from WA Museum bookstore) but also googled papers by various microbialite researchers as well.

      cheers

      Perdy

      *you can have low salinity waters that are high in carbonates.

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