Otolith mass asymmetry in Otolithes ruber (Bloch and Schneider, 1801) (Actinopterygii: Perciformes) collected from the Iraq marine waters

Water pollution is mainly an anthropogenic event affecting water resources of all types. With such a happening, fish are harmfully disturbed. Otolith mass asymmetry can reveal some growing disarrays of fish due to environmental impact. Particularly, high level of otolith mass asymmetry can negatively disturb fish life, consequently the assessment of the asymmetry is imperative for each fish species. In the present work, the otolith mass asymmetry was computed as the difference between the mass of the right and left paired otoliths divided by average otolith mass in Otolithes ruber. According to the previous cases obtained on other symmetrical fish species, the absolute value of x in O. ruber does not depend on fish length and otolith growth rate, while the absolute value of otolith mass difference is boosted with the fish length. The value of x was between -0.2 and +0.2.

水污染主要是由人类活动引发的、影响各类水资源的环境事件。此类污染会对鱼类造成有害干扰。耳石质量不对称性（otolith mass asymmetry）可反映鱼类因环境影响而出现的生长紊乱。尤为重要的是，耳石质量不对称程度过高会对鱼类生存产生负面影响，因此对各鱼类物种开展不对称性评估具有必要性。在本研究中，研究人员以红牙䱛（Otolithes ruber）为研究对象，将耳石质量不对称性计算为左右成对耳石的质量差值除以耳石平均质量。基于其他对称鱼类物种的既往研究结果，红牙䱛的x绝对值与鱼类体长及耳石生长速率均无关联，而耳石质量差值的绝对值则随鱼类体长增加而增大。本次研究中x的取值范围为-0.2至+0.2。