Comparative aggression and dominance of Oreochromis niloticus (Linnaeus, 1758) and Oreochromis mortimeri (Trewavas, 1966) from paired contest in aquaria

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• 作者：Portia Chiyedza Chifamba ; Tendai Mauru
• 关键词：Aggression ; Relative size ; Invasive and native fish ; Oreochromis niloticus ; Oreochromis mortimeri
• 刊名：Hydrobiologia
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：788
• 期：1
• 页码：193-203
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Freshwater & Marine Ecology; Ecology; Zoology;
• 出版者：Springer International Publishing
• ISSN：1573-5117
• 卷排序：788

文摘

Oreochromis niloticus was introduced in Lake Kariba, and it displaced the endemic Oreochromis mortimeri from many areas of the lake. Studying the interaction between the two species sheds light on the nature of the displacement process. The levels of aggression within and between the two species and the effect of relative size were studied in the laboratory. O. mortimeri attacked O. niloticus first in most of the encounters whether it was the bigger or smaller of the pair. In encounters where O. niloticus was smaller, 2 (8.3%) O. niloticus made the first bite and 8 (40.0%) made the first bite when O. niloticus was the bigger of the pair. Over a 30-min encounter, O. mortimeri was dominant and delivered significantly more bites (7.79 ± 2.31 bites) than O. niloticus (4.53 ± 1.53 bites) (P = 0.03, t = 2.18). Unlike O. mortimeri, O. niloticus attacked first only when it was considerably bigger than the opponent. The association of large body size with higher aggression may mean that O. niloticus, which grows faster and larger than O. mortimeri, has size advantage. Therefore, interaction between the two species may be complex, and aggression may be just one of the factors that affect the interaction of these fish species.