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Physicochemical habitat association of a native and a non-native crayfish in the lower Flint river, Georgia: implications for invasion success


Invasive species must cope with a suite of environmental conditions that are different from those in their native ranges. We examine how the physicochemical environment contributes to the invasion success of Orconectes palmeri, a non-native crayfish, in the lower Flint River basin, Georgia, USA. We examined the distribution of Procambarus spiculifer, a native crayfish, and O. palmeri within the lower Flint River basin, and examined associations between species relative abundance and physicochemical variables. Within the lower Flint River, O. palmeri was found almost exclusively at upstream sites, while P. spiculifer was more abundant downstream. We did not detect small O. palmeri downstream, suggesting little recruitment in this area. Within tributaries, only native crayfish were observed. O. palmeri was more abundant at sites with warmer water temperatures, and P. spiculifer was more abundant at sites with cooler water temperatures, which were maintained by ground water seepage. P. spiculifer abundance was also positively associated with abundance of coarse wood. Laboratory studies demonstrated that O. palmeri selected warmer temperatures than P. spiculifer, suggesting that warmer temperatures in the upstream area favor O. palmeri. Water temperatures may have increased in recent years due to human withdrawals from the aquifer and the installation of upstream dams, creating a thermal regime that P. spiculifer has not historically encountered. Our findings suggest that the maintenance of groundwater inputs and a forested riparian buffer is crucial to protect populations of P. spiculifer and to prevent further spread by O. palmeri, especially if climatic changes result in warmer waters.