在这项研究中,我们研究了两种鱼类的生长动力学和耳石形状不对称性,黑毛虫(CN)和尼罗罗非鱼(ON),在南部泻湖系统的城市化流域内,尼日利亚。使用vonBertalanffy生长模型(VBGM),除了沉积物金属浓度指数,如平均页岩含量,地质累积指数(Igeo),污染因子(CF),污染负荷指数(PLI),和潜在生态风险(PER)指数,污染水平被分类,并对生态风险进行了评估。值得注意的是,在Ikorodu观察到CN的生长潜力(t0)低于Epe,在旱季期间,Epe中的ON趋势相似。耳石不对称模式,特别是在旱季伊科罗杜的CN和Epe的ON,表现出明显的生态变化,表明伊科罗杜的压力水平升高。沉积物分析显示中度至强污染(Cd,Pb,Ni,和Cr)在拉各斯泻湖(Ikorodu)和Epe泻湖中,根据CF指数,Ikorodu表现出明显的高到中等污染水平。Ikorodu中Cd和Pb的PLI值升高,除了更大的PER,表明风险增加,Cd风险较高(61.42%),Pb风险中等(49.50%)。此外,旱季期间Epe的渐近长度减少表明,NigrodigitatusChrysichthys可适应季节性变化,而这两个领域不同的增长模式表明,在不断变化的条件下,存在权衡机制。栖息地特有的耳石不对称性和金属污染强调了物种的适应性,拉各斯的压力源变异性比Epe大。此外,多维尺度分析强调了耳石形状变量与环境因素之间的复杂关系,强调需要对城市化流域进行量身定制的保护工作。
In this study, we investigated the growth dynamics and otolith shape asymmetry of two fish species, Chrysichthys nigrodigitatus (CN) and Oreochromis niloticus (ON), within urbanized watersheds of the southern lagoon system, Nigeria. Using the von Bertalanffy growth model (VBGM), in addition to sediment metal concentration indices such as the average shale content, index of geoaccumulation (Igeo), contamination factor (CF), pollution load index (PLI), and potential ecological risk (PER) index, contamination levels were classified, and ecological risks were assessed. Notably, a lower growth potential (t0) was observed in CN at Ikorodu than at Epe, with similar trends for ON in the Epe during the dry season. Otolith asymmetry patterns, particularly in the CN at Ikorodu and ON in the Epe during the dry season, exhibited distinct ecological variations, indicating heightened stress levels at Ikorodu. Sediment analyses revealed moderate to strong contamination (Cd, Pb, Ni, and Cr) in both Lagos Lagoon (Ikorodu) and Epe Lagoon, with Ikorodu exhibiting notably high to moderate contamination levels according to the CF index. Elevated PLI values for Cd and Pb in Ikorodu, in addition to greater PER, indicated increased risk, with Cd posing a high risk (61.42%) and Pb posing a moderate risk (49.50%). Additionally, the reduced asymptotic length in the Epe during the dry season suggests that Chrysichthys nigrodigitatus is adaptable to seasonal variations, while divergent growth patterns in both areas indicate the existence of trade-off mechanisms in response to changing conditions. Habitat-specific otolith asymmetry and metal contamination underscore species adaptability, with wider stressor variability in Lagos than in Epe. Furthermore, multidimensional scaling analysis highlights the intricate relationship between otolith shape variables and environmental factors, emphasizing the need for tailored conservation efforts in urbanized watersheds.