Native European crayfish may face diminishing habitats due to global warming, study finds

We need to watch that we are only boiling crayfish in pots- not in their natural freshwater habitats. According to an international team of researchers, climate change may diminish the range of habitat for the five native species of European crayfish.

Image by Isaac Wedin

Image by Isaac Wedin

As published in the journal, Conservation Biology, all five species of crayfish native to European freshwater sources are expected to face habitat reduction between nineteen and seventy-one percent within just seven decades. These reductions are due to rising water temperatures heralded by global warming, and exacerbated by the introduction of invasive species to European waters.

Alien species introduced to European watersheds threaten indigenous populations by competing for resources including food and shoreline. They can also carry the pathogen A. astaci, the purveyor of the lethal crayfish plague, which threatens to infect and eliminate native European species of crayfish when these species are introduced into the same range of habitat.

Unfortunately, due to the emission of greenhouse gases and the warming of the planet, these ranges are coming into closer contact. Scientists recently created a model to quantitatively evaluate the threat to crayfish due to climate change.

To build a model, researchers utilized decades of historical information on the range of European crayfish, built grids in European waterways to estimate the population density of five species of crayfish, and extrapolated data on climate change over the past fifty years, creating two estimates of future climactic data, one using low values of greenhouse emissions, and the other with higher numbers.

Image by U.S. Fish and Wildlife Service- Midwest

Image by U.S. Fish and Wildlife Service- Midwest

Using a distribution model, scientists were able to estimate the distribution of crayfish in 2080 for five separate native species in European watersheds, along with three invasive species, thus allowing scientists to gauge the overlap between native and non-native animals, and how this may affect habitat distribution in the future.

The results show that with high gas emissions, for each of the five species of European crayfish, noble, narrow-clawed, thick-clawed, white-clawed, and stone, respectively, habitats are expected to diminish anywhere from nineteen percent to seventy-one percent.

This represents a significant reduction in the areas available for crayfish to survive, one that is further challenged by changes to the range of invasive species due to climate change. North American crayfish are capable of living in waters up to eight degrees Celsius warmer than their European counterparts, thus, one species of American crayfish, the red swamp crayfish, may see an increase in its potential range by fifty-three percent, representing an increased overlap in range with European species.

This overlap threatens to perpetuate problems of disease transmission between species, along with competition for resources. This poses a severe threat for the continued survival and reproduction of crayfish, which are inherently affected by climate change, which will affect the natural biological processes of the native species, including reproduction and lifecycle patterns.

Even more basic than future interspecies interaction is the issue of migration for crayfish, which have no natural migration patterns outside freshwater watersheds, and therefore cannot move between habitats on their own. Human intervention would be required to transport crayfish to accessible habitats in the future.

In the coming years, as climate change continues to alter the temperatures of our planet’s waters, human modification, including the separation of native and invasive species, and the transport of crayfish to adaptable habitats, will be necessary in order to ensure the species’ survival.

While crayfish are only one component of the watershed systems of Europe, the potential alterations in their distribution due to climate change signal a greater call to ensure that biodiversity is not diminished by rising temperatures, and native species do not face disproportionate threats due to a combination of warming and invasion by outside species.

Citation:

Capinha, C., Larson, E. R., Tricarico, E., Olden, J. D. and Gherardi, F. (2013), Effects of Climate Change, Invasive Species, and Disease on the Distribution of Native European Crayfishes. Conservation Biology, 27: 731–740.

-Kira Clingen (traditional)

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