Zeitschrift für Fischerei und Aquakultur
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Ichthyofauna-Struktur durch Bioinvasion von Clarias gariepinus in einem Fluss im Umweltschutzgebiet Guapimirim im Südosten Brasiliens gefährdet

Michelle Torres Dumith, Alejandra FGN Santos

The African sharp tooth catfish (Clarias gariepinus) is the most important catfish species for aquaculture. It has a great capacity to endure several stressing factors, such as adverse environmental conditions, besides having broad feeding flexibility. Notwithstanding, the presence of this alien fish species in the Guapimirim Environmental Protection Area, in southeast Brazil, may have negative impacts on the community of native fish. In 2018, during dry and rainy seasons, samples from the fish community were collected in 32 sites of the Guapi-Macacu River, in addition to abiotic variables (salinity, pH, temperature, turbidity, dissolved oxygen, and transparency) to diagnose which factors influence the distribution of the alien fish along the river. Moreover, species were evaluated as bio indicators in the ichthyofauna to identify potential alterations in the community. Multivariate analyses indicated that the African sharp tooth catfish dominates the buffer zone of the environmental protection area, benefiting from higher levels of dissolved oxygen and temperature. However, C. gariepinus still does not dominate the most protected area of Guapimirim, where a higher percentage of native fish species dwell. Alterations in abiotic factors, related to the increase in the temperature, can significantly contribute to the dominance of this invasive alien fish in this protected area, requiring constant monitoring of some key species, as well as the population of the invasive species in this environmental preservation area.