Landscape attributes explain co-occurrence between an endemic amphibian and alien trout in mountainous streams of Cordoba (Argentina)

Amphibians inhabiting mountainous water bodies are frequently documented as the most affected by alien species, being trout one of the introduced aquatic predators that most affect them globally. Strikingly, there are some records of co-occurrence between native amphibians and introduced trout in the same water bodies. We intended to elucidate which variables at the landscape scale explain the occurrence of the endemic frog Boana cordobae in streams invaded by alien trout (Sierras Grandes, central Argentina). We surveyed mountainous streams occupied by alien trout, measuring landscape variables and recording the occurrence of B. cordobae and found co-occurrence in almost 20% of surveyed streams (n = 81). We used Generalized Linear Models and LASSO regression to relate amphibian occurrence in invaded streams to landscape composition and configuration variables. The presence of tussock grasslands around streams appears to be the most critical variable explaining co-occurrence between B. cordobae and trout in our study site. Our study contributes with specific elements relevant to consider for invaded streams management actions, suggesting that alien trout management should consider the spatial features surrounding streams to concentrate trout eradication efforts in sites where amphibian populations are more likely to recover.

Automated summary

Amphibians inhabiting mountainous water bodies, particularly the endemic frog Boana cordobae, are significantly affected by the introduction of alien species, such as trout. However, co-occurrence between native amphibians and introduced trout has been observed in some streams. This study aimed to identify the landscape variables that explain the occurrence of B. cordobae in streams invaded by alien trout in central Argentina. The presence of tussock grasslands around streams was found to be the most significant variable influencing the co-occurrence of B. cordobae and trout.