Nile crocodiles (Crocodylus niloticus) at Lake St Lucia, South Africa, have some of the highest blood lead (Pb) concentrations ever recorded in wildlife globally. Although exposure to Pb is known to pose major risks to wildlife reproductive success, potential impacts on crocodile reproduction at Lake St Lucia have yet to be examined. In this study, we investigated the accumulation of Pb and other trace metals (Al, V, Cr, Co, Cu, Ni, Zn and Cd) in eggs (n = 20) collected from five wild crocodile nests at Lake St Lucia. All metals analysed in this study were detected in egg contents, although concentrations varied considerably among nests and within clutches. Lead was detected in the contents of all eggs, but only at relatively low concentrations (43 ± 26 ng g⁻¹ dry weight). Although sampling limitations commonly associated with wild population surveys prevent a complete assessment of exposure variability, our findings suggest maternal transfer may not be a significant depuration pathway for Pb and females possibly clear Pb through other mechanisms (e.g. sequestration into claws, bone and osteoderms). Metal concentrations in eggshells and shell membranes were poorly correlated with concentrations measured in egg content and thus do not provide viable non-lethal indicators for monitoring metal exposure in Nile crocodiles. Intra-clutch variability accounted for a considerable proportion of the total variance in egg content metal concentrations, suggesting the “one egg” sampling strategy often applied in reptile studies may not be an effective biomonitoring tool for wild crocodilian populations. Although maternally derived Pb does not appear to present widespread toxicological concern at Lake St Lucia, adverse effects of Pb exposure on other reproductive functions (e.g. spermatogenesis) cannot be discounted and warrant further investigation.

南非圣卢西亚湖的尼罗河鳄鱼 ( Crocodylus niloticus ) 的血铅 (Pb) 浓度是全球野生动物有史以来最高的。尽管已知暴露于铅会对野生动物的繁殖成功构成重大风险，但对圣卢西亚湖鳄鱼繁殖的潜在影响仍有待研究。在这项研究中，我们调查了 从圣卢西亚湖的五个野生鳄鱼巢中收集的鸡蛋（ n = 20）中铅和其他微量金属（Al、V、Cr、Co、Cu、Ni、Zn 和 Cd）的积累。在这项研究中分析的所有金属都在鸡蛋内容物中检测到，尽管巢穴之间和离合器内的浓度差异很大。在所有鸡蛋的内容物中都检测到铅，但仅在相对较低的浓度（43 ± 26 ng g ^-1净重）。尽管通常与野生种群调查相关的抽样限制阻碍了对暴露变异性的完整评估，但我们的研究结果表明，母体转移可能不是铅的重要净化途径，雌性可能通过其他机制（例如螯合到爪、骨和骨皮中）清除铅。蛋壳和壳膜中的金属浓度与鸡蛋含量中测量的浓度相关性较差，因此不能提供可行的非致命指标来监测尼罗河鳄鱼中的金属暴露。离合器内的变异性占鸡蛋含量金属浓度总变化的相当大比例，这表明爬行动物研究中经常应用的“一个鸡蛋”采样策略可能不是野生鳄鱼种群的有效生物监测工具。