Salinity tolerance and geographical origin predict global alien amphipod invasions.

Area of Science:

• Ecology
• Invasive Species Biology
• Aquatic Ecology

Background:

• Invasive alien species are a major driver of global biodiversity loss and impact ecosystem services.
• Predicting the success of invasive species, especially in aquatic environments, is crucial for effective management.
• Salinity tolerance and geographical origin are potential key factors influencing invasion success.

Purpose of the Study:

• To investigate whether salinity tolerance and geographical origin predict invasion success in aquatic gammarids (Crustacea: Amphipoda: Gammaroidea).
• To analyze global diversity and invasion patterns of gammarid species.
• To identify characteristics that enhance the invasiveness of aquatic crustaceans.

Main Methods:

• Compiled global data on aquatic gammarid diversity, salinity tolerances, and regions of origin.
• Examined the proportion of alien species across different salinity environments and geographical origins.
• Statistical analysis to determine if salinity tolerance and origin significantly predict invasion status.

Main Results:

• Only 3% of 918 aquatic gammarid species were reported as aliens, despite invasion opportunities.
• Alien gammarids were disproportionately salt-tolerant (32% of brackish-water species) compared to freshwater and marine species (1%).
• Alien gammarids significantly originated from the Ponto-Caspian region (20%) and primarily invaded Eurasian waters, with salt-tolerant taxa frequently translocated to freshwaters.

Conclusions:

• Habitat characteristics, such as broad environmental tolerances to harsh conditions, significantly predict aquatic gammarid invasiveness.
• Geographical origin, particularly the Ponto-Caspian region, is a strong predictor of invasive gammarid success.
• Evolutionary history and adaptation to challenging environments likely promote the global success of alien gammarids.