AsianScientist (Aug. 23, 2016) – A loss in certain species can provide early warning signals of large, potentially catastrophic, changes or tipping points in ecosystems, according to new research published in the journal Ecology.
Like canaries that coal miners used to check for poisonous gasses deep underground, ‘ecosystem canaries’ are species that are often the first to disappear from a stressed ecosystem. Their vanishing can be linked to changes in the functioning of ecosystems, which can serve as a warning that a tipping point is approaching.
In a study involving three lake ecosystems in China, researchers showed changes in the abundance of species from algae (diatom) and aquatic midges (chironomid) communities as they compete for resources under environmental pressures.
From this data it was possible to identify three types of organisms: slowly-replicating but strongly competitive ‘keystone’ species; weakly-competitive but fast-replicating ‘weedy species’; and slowly-replicating and weakly-competitive ‘canary’ species.
As environmental degradation impacts on the ecosystem, keystones initially prevail through competitive dominance over others, resulting in the early demise of canary species. With continuing degradation affecting all species, this leads to the eventual collapse of the keystone species as they are replaced by the weedy species. The loss of keystones puts the ecosystem into a critical transition—the point at which a system tips into an alternate state which can be very hard to recover from.
The vulnerability of canary species suggests a role for this group as a sensitive indicator of environmental forcing, yet it is often assumed their presence or absence has no useful ecological information.
“We were able to detect a clear signal of an approaching tipping point in our selected Chinese lake ecosystems, through the analysis of multi-decadal data of fossilized diatoms and chironomids. In some cases we could detect an early warning signal up to three decades before the actual tipping point,” Professor Patrick Doncaster, from the University of Southampton and lead author of the study, said.
The article can be found at: Doncaster et al. (2016) Early Warning of Critical Transitions in Biodiversity from Compositional Disorder.
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Source: University of Southampton; Photo: Pixabay.
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