Microhabitat use by two silurid species of the Anizacate River (Central Argentina).

HUED, A. C.; BISTONI, M. A.

FOLIA ZOOLOGICA

Institute of Vertebrate Biology - Academy of Sciences of the Czech Republic

Lugar: República Checa; Año: 2006 vol. 55 p. 175 - 182

0139-7893

Fish species exhibit different preferences and segregate according to a set of physical habitat conditions. In order to determine the habitat use by two native species: Trichomycterus corduvense and Heptapterus mustelinus, we established microhabitat preferences based on the three major habitat dimensions: substrate type, water depth and current velocity. The study was carried out in a section of Anizacate River, located in a semiarid region of Córdoba Province (central region of Argentina). It was established a transect, perpendicular to flow direction, at the downstream end of the study site and subsequent transects at 5m-intervals parallel to the initial transect and throughout the length of the study site. Both fish collection and habitat variables measurements were made in 1m2-quadrates at 3m-intervals along each transect. We quantified available physical microhabitats and estimated the proportion of microhabitat use by both fish species through suitability curves, niche breadth and Shoener´s overlap formula. According to our results, current velocity is the key factor that determines different microhabitat use between T. corduvense and H. mustelinus. The former species is acting as a velocity specialist whereas the latter could be considered as a generalist. In spite of the trophic competition between both them, the spatial partitioning guarantees the coexistence of H. mustelinus and T. corduvense in Anizacate River. Key words: Freshwater, Suitability Curves, Heptapterus mustelinus, Trichomycterus corduvense.