Exposure of Hyalella bonariensis (Crustacea, Amphipoda) to Essential Oils: Effects on Anesthesia and Swimming Activity

Amphipods are frequently used as bioindicators of water quality in experimental or behavior trials. Thus, it is a group considered suitable for use as a model organism in tests with essential oils (EOs). This study evaluated the time required for anesthesia induction and recovery of the amphipod crustacean H. bonariensis exposed to the essential oils of Aloysia triphylla (EOAT) and Lippia alba (EOLA), and their major compounds citral and linalool, respectively. In addition, we evaluated the locomotor activity of amphipods using ANY-maze(R) software. Mortalities were observed at concentrations of 100 and 200 mu L/L of citral (50.0 +/- 0.39%) and 750 mu L/L of EOLA (66.7 +/- 0.33%). Except for linalool, increased concentrations of the compounds of the essential oils decreased the time for sedation and anesthesia induction. There were differences for the induction of anesthesia (p < 0.05) and recovery (p < 0.05) between EOLA and linalool treatments, but not between that for EOAT and citral. Reduced locomotor activity and longer time and episodes of freezing were observed in animals exposed to EOAT. The EOs and their major compounds induced anesthesia and affected the locomotor activity of H. bonariensis, Therefore, EOAT and linalool are recommended for anesthesia of this species. EOAT can also be utilized in long-term exposure.