Stress responses in juvenile pacu (Piaractus mesopotamicus) submitted to repeated air exposure

Jaqueline  Dalbello Biller; Fabiano  Bendhack; Leonardo  Susumu Takahashi; Elisabeth  Criscuolo Urbinati

Stress responses in juvenile pacu (Piaractus mesopotamicus) submitted to repeated air exposure

Autores

Jaqueline Dalbello Biller

Fabiano Bendhack

Leonardo Susumu Takahashi

Elisabeth Criscuolo Urbinati

Editor

Universidade Estadual de Maringá

Descripción

Pacu juveniles (5.2 ± 1.5 g) were submitted to two one-minute air exposures in a 24h interval, and sampled before the exposure (control) and 5, 15, 30 and 60 min., 24 and 48h afterwards for whole-body cortisol, sodium, potassium and calcium ion concentrations. For the first air exposure, there was a trend of increased cortisol concentration after 15 min., whereas in the second air exposure, the cortisol concentration increased significantly within 5 min. after stress was induced. Sodium ion concentration increased significantly 24h after both air exposures. Potassium concentration presented fluctuations over the experimental period. Calcium ion concentration increased progressively from 5 to 30 min., in both air exposures. The repeated air exposures exacerbated the cortisol response, but they did not affect the recovery ability of pacu over the experimental period. Additionally, the whole-body cortisol measurement might be a reliable indicator of stress, when sampled fish are smaller and blood volumes are very low, making samples inadequate for analysis.