Tilapia venturing into high-salinity environments: A cause for concern?

Invasive species are continuously introduced in several ecosystems from human activities. Aquaculture activities are noteworthy among the many different species introduction vectors currently in place, generating a pattern of constant, frequent or massive release of propagules into aquatic ecosystems, increasing species establishment success rates. Reported cases in marine or brackish ecosystems, however, are still scarce. As aquaculture constantly generate propagules with the ability to employ these facilities as corridors to further spread to interconnected brackish and freshwater ecosystems, colonising high salinity systems, this study aimed to compile evidence of Tilapiines detected in Brazilian coastal marine and brackish ecosystems. Nineteen records were obtained, with the presence of this invader suggested as higher following rainfall seasons. The widespread distribution of Tilapiines is relatively well-known in Brazilian freshwater ecosystems but, up to now, its potential to use brackish and marine ecosystems as ecological corridors has been described only experimentally. Our findings highlight the potential for a typically freshwater invader to spread through marine ecosystems, raising concerns regarding the licensing of aquaculture projects within rivers and estuaries, as tilapia may significantly affect native Brazilian biota.