Assessing the threat of a South American cichlid on anurans in the Chilean Mediterranean region

Abstract

Mediterranean biomes have been recognized as having high value due to their diversity; they are under threat due to anthropic pressures. Both freshwater fish and amphibians show high endemism and vulnerability to several threats; among the latter is the introduction of fishes. In Chile there is scarce documentation of the presence of the non-native Australoheros facetus (chameleon cichlid), where it cohabits with other non-native and native fish and anurans. In this study we first sampled for the presence/absence of A. facetus in 69 localities in the Chilean Mediterranean region. Secondly, to estimate their potential impact, we evaluated the predatory capacity of A. facetus and other two sympatric fish, Gambusia holbrooki (mosquitofish; non-native) and Cheirodon pisciculus (pocha; native), on larvae of four species of native anurans and on the eggs of a non-native anuran. We report that A. facetus has expanded in the entire Chilean Mediterranean region; its presence is related to low altitude areas. We confirmed that lentic environments and irrigation systems of streams increase the probability of successful establishment. The results for predatory capacity showed that A. facetus regularly predated larvae of all the tested anurans, being significantly more successful in predating larvae, but also significantly less successful in predating eggs, compared to other fish species. The control of non-native fish is a priority to avoid the invasion of new localities in these ecosystems.