Effects of habitat on physiological indicators in Leporinus friderici (Pisces, Anostomidae) in the influence area of the Corumbá Reservoir, Goiás, Brazil

BENEDITO-CECILIO¹, E.; PEREIRA², A.L.; BALERONI³, H. & FARIA², A.C.E.A.

^1,2 Laboratório de Ecologia Energética – Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura, Nupélia/PEA – Curso de Pós-graduação em Ecologia de Ambientes Aquáticos Continentais Universidade Estadual de Maringá, Avenida Colombo, 5790 - 87020-900, Maringá, PR, Brazil.

³ Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal do Tocantins, BR 153, Km 112 - 77804-970, Araguaína, TO, Brazil.

ABSTRACT: The physiological variables, indicative of the use of energy by fish, were analysed during habitat changes caused by the impounding of the Corumbá reservoir. Samplings were undertaken prior to the formation of the Corumbá reservoir (March 1996 - August 1996, river phase), during impounding (September 1996 - February 1997, transition phase) and after its formation (March 1997 - February 2000, reservoir phase). Each specimen was analysed Stomach Fullness Index (SFI), Gonadosomatic Index (GSI) Condition Factor (K’) and Caloric Content. Alterations in environment affected the physiological indicators analysed for L. friderici. These indicators were distinct for each sex, while positive changes (an increase in mean SFI and K’) and negative ones (decrease in mean standard length, GSI and energy), conditioned to the species’s ecological plasticity, may still occur. Total of positive variations of fitness warrants the species’s success in the occupation and in the maintenance of the recently formed environment. It should be emphasized that impact intensity is a mitigating factor on the stress borne by the species.

Key words: Fish, Leporinus friderici, impact, Paraná river, energy.