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Volume 45 - Number 2 - 2010


Evidence of microhabitat overlap between juvenile of introduced salmon Oncorhynchus tshawytscha and the native fish Trichomycterus areolatus in the Allipén River, Chile

Pamela V. Vargas1, Iván Arismendi2,3, Gladys Lara1, Javier Millar1 y Santiago Peredo1


1Escuela de Ciencias Ambientales, Facultad de Recursos Naturales, Universidad Católica de Temuco, Casilla D-15, Temuco, Chile

2Escuela de Graduados, Facultad de Ciencias Forestales, Universidad Austral de Chile, Casilla 567, Valdivia, Chile

3USGS Forest and Rangeland Ecosystem Science Center, Aquatic Ecology Laboratory, 3200 SW Jefferson Way, Corvallis, Oregon 97331, Estados Unidos




Introduced juvenile Chinook salmon (Oncorhynchus tshawytscha) have been found co-occurring with native fishes in the Allipén River, Chile. Due to this co-occurence, the microhabitat use, microhabitat preferences, and overlap between juvenile Chinook salmon and the native catfish, Trichomycterus areolatus, were examined during the summer and fall of 2007-2008. Microhabitat preferences and overlap between juvenile Chinook salmon and the native catfish were determined using the Instream Flow Incremental Methodology and the Pianka´s index. Juvenile Chinook salmon and the native catfish microhabitat preferences varied seasonally showing a high degree of similarity and overlap between the species (higher than 80%). The results suggest the risk of negative interactions and interactive segregation over habitat processes between juvenile Chinook salmon and native catfish. As a consequence, the Chinook salmon invasion may threaten the stability of native catfish populations at Allipén River


Key words: Biological invasions, co-occurrence, negative interactions, interactive segregation, temperate ecosystems



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