Table 3.

Response of Lutjanus griseus to PAG + ammonia-N, urea-N and ammonia-N/urea-N (1:1)

0-25 cm* 25-50 cm* Visual scan Enter shelter Duration in shelter (s)
TreatmentControlTreatmentControlTreatmentControlTreatmentControlTreatmentControl
Trial 4 (N=8)
Baseline0.2±0.2a0±00.1±0.1a0.2±0.20±0a0±00±0a0±00±0a0±0
PAG1.5±1.6b0.3±0.21.6±0.6b0.3±0.21.3±0.4a,b0.1±0.10.1±0.1a0±00.4±0.4a0±0
PAG+Ammonia4.4±1.6c0.4±0.22.9±0.9b0.1±0.13.1±1.2b0.3±0.20.1±0.1a0±00.3±0.2a0±0
PAG+Ammonia/urea1.6±0.7b0.3±0.21.4±0.3b0.1±0.11.0±0.5a,b0.1±0.10±0a0±00±0a0±0
Positive control11.9±4.3c0.4±0.22.6±0.8b0.1±0.115.3±6.5c0.3±0.24.8±2.5b0±052±30b0±0
Trial 5 (N=6)
Baseline0.2±0.2a0.2±0.10.1±0.1a0.2±0.20.1±0.1a0.2±0.20±0a0±00±0a0±0
PAG7.2±3.1b2.3±1.85.8±1.6b0.8±0.34.5±1.9b0.5±0.50.3±0.3a0±00±0a0±0
PAG+urea5.7±2.2b2.2±1.57.0±2.3b0.8±0.45.0±2.6b0.3±0.20±0a0±00±0a0±0
Positive control16.2±5.5c3.0±1.79.7±3.4b1.8±0.913.0±5.6b0.2±0.20.7±1.3a0±05±4a0±0
  • PAG=2.5 μmol N l−1 mixture (1:1:1) of l-alanine, l-glycine and l-proline; PAG+Ammonia=2.5 μmol N l−1 PAG + 25 μmol N l−1 ammonia-N; PAG+Urea=2.5 μmol N l−1 PAG + 25 μmol N l−1 urea-N; PAG+Ammonia/urea=2.5 μmol N l−1 PAG with 25 μmol N l−1 amm-N/urea-N (1:1).

    Categories include the distance (*) gray snapper passed from odorant source; visual scan refers to when fish ceased locomotion for >1 cycle of pectoral fin sweeps and visually scan the internal shelter chamber. The duration of each odorant challenge was 60 min.

    Baseline controls for pump noise prior to odorant delivery, the control columns represent simultaneous seawater delivery during odorant challenges and the positive control was clarified toadfish homogenate.

    Values are presented as means ± s.e.m.; significant differences between treatments and controls; significant differences among treatments groups are indicated by different lower case letters.