Briski, Elizabeta (2019) Is salinity an obstacle for biological invasions?. [Talk] In: 21. International Conference on Aquatic Invasive Species. , 27.-31.10.2019, Montreal, Quebec, Canada .

Abstract

Invasions of freshwater habitats by marine species have become increasingly common in recent years, with most of these species originating from Ponto-Caspian region. In contrast, few freshwater species have invaded brackish, but not marine habitats. To determine if species from certain areas can better tolerate transitions from saline to freshwater habitats and vice versa, we explored nonindigenous species (NIS) established in the North and Baltic Seas and Great Lakes–St. Lawrence River regions—two areas intensively studied in concern to NIS, highly invaded by Ponto-Caspian species and with different salinity patterns (marine vs. freshwater). We compared observed numbers of NIS in these two regions to expected numbers of NIS from major donor regions which were calculated based on the available species pool from donor regions, frequency of shipping transit, and an environmental match between donor and recipient regions. Then we conducted salinity tests on eight species native to Northern Europe, the Great Lakes-St. Lawrence River and Ponto-Caspian region, as well as experimental selection experiments on Ponto-Caspian gammarid Pontogammarus maeoticus to determine their salinity tolerance and adaptation potential for higher and lower salinity than the tested population was collected from (i.e., 10 ppt), respectively. Our results demonstrated that Ponto-Caspian taxa colonized both types of habitats, marine areas of the North and Baltic Seas and freshwater of the Great Lakes–St. Lawrence River, in much higher numbers than expected. All eight species tolerate wide ranges of salinity, however, different patterns arose among species from different regions. Ponto-Caspian taxa showed lower mortality in fresh water, while Northern European taxa showed higher survival in fully marine conditions. Finally our experimental selection of P. maeoticus resulted in successful selection to lower, but not to higher salinity.

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