Our goals were: (i) to determine whether sublethal concentrations of water-borne ammonia would prevent the formation of a dominance hierarchy, or alter its structure, in groups of 4 juvenile trout; (ii) to investigate the behavioral and physiological responses of individuals of different social rank exposed to a concentration of ammonia that still allowed hierarchy formation. Social hierarchies were created by using a technique in which a food delivery system that created competition also served to isolate individual fish for respirometry. Groups of 4 fish were exposed to elevated ammonia (NH₄HCO₃) 12 h before first feeding; aggression was recorded by video camera during morning feedings. Experimental ammonia concentrations were 700, 1200 and 1500 μmol L⁻¹ at pH 7.3, 12 °C (9.8, 16.8, and 21.0 mg L⁻¹ as total ammonia-N, or 0.0515, 0.0884, and 0.1105 mg L⁻¹ as NH₃-N). Aggression was severely reduced by 1200 and abolished by 1500 μmol L⁻¹ total ammonia, such that hierarchies did not form. However, groups exposed to 700 μmol L⁻¹ total ammonia still formed stable hierarchies but displayed lower levels of aggression in comparison to control hierarchies. Exposure continued for 11 days. Physiological parameters were recorded on day 5 (end of period 1) and day 10 (end of period 2), while feeding and plasma cortisol were measured on day 11. In control hierarchies, dominant (rank 1) trout generally exhibited higher growth rates, greater increases in condition factor, higher food consumption, and lower cortisol levels than did fish of ranks 2, 3, and 4. In comparison to controls, the 700 μmol L⁻¹ total ammonia hierarchies generally displayed lower growth, lower condition factor increases, lower O₂ consumption, lower cortisol levels, but similar feeding patterns, with smaller physiological differences amongst ranks during period 1. Effects attenuated during period 2, as aggression and physiological measures returned towards control levels, indicating both behavioral and physiological acclimation to ammonia. These disturbances in social behavior and associated physiology occurred at an ammonia concentration in the range of regulatory significance and relevance to aquaculture.

我们的目标是：（i）确定亚致死浓度的水性氨水是否会阻止以4个成年鳟鱼为一组的优势等级的形成或改变其结构；（ii）调查暴露于浓度仍允许等级形成的氨浓度下不同社会阶层的个体的行为和生理反应。通过使用一种技术来创建社会等级，在该技术中，引起竞争的食品输送系统还可以隔离单个鱼以进行呼吸测定。在第一次喂食之前的12小时，将4只鱼的组暴露于高浓度氨水（NH ₄ HCO ₃）中。在早上喂奶时用摄像机记录了侵略行为。实验氨浓度为700、1200和1500μmolL ^-1在pH 7.3、12 °C（9.8、16.8和21.0 mg L ^-1的总氨氮或0.0515、0.0884和0.1105 mg L ^-1的NH ₃ -N）中。侵略性严重降低了1200，并被1500μmolL ^-1的总氨消除了，因此没有形成等级结构。但是，暴露于700μmolL ^-1的基团总氨仍然形成稳定的层次，但与对照层次相比，其侵略性较低。暴露持续11天。在第5天（第1阶段结束）和第10天（第2阶段结束）记录生理参数，而在第11天测量喂养和血浆皮质醇。与第2、3和4级的鱼类相比，条件因子的增加更大，食品消耗量更高，皮质醇水平更低。与对照相比，700μmolL ^-1的总氨等级通常显示出较低的生长，较低的条件因子增加，较低的O ₂食用，皮质醇水平较低，但饲喂模式相似，在第1阶段中各等级间的生理差异较小。随着攻击和生理措施恢复到控制水平，作用在第2阶段减弱，表明对氨的行为和生理适应。这些社会行为和相关生理障碍是在氨浓度范围内发生的，该浓度在具有管理意义和与水产养殖有关的范围内。