In oviparous wildlife, many critical physiological and behavioural components are strongly influenced by the embryonic and early post-hatch developmental environment. As such, early life stages in these species are highly vulnerable to both natural and anthropogenic stressors. For example, in birds, incubation temperature may influence the rate of egg development while also affecting contaminant metabolism and absorption in body tissues, resulting in potentially multiplicative impacts on embryonic and posthatch development. We tested the hypothesis that cumulative effects of early contaminant exposure and temperature stress can negatively affect avian development and may have interactive effects that are more detrimental than either stressor individually. Using a controlled egg injection and incubation study on killdeer (Charadrius vociferous), eggs were exposed to a known endocrine disruptor, 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126) and incubated at either low (36 °C), intermediate (37.5 °C), or high (39 °C) temperatures. Our results indicated that eggs incubated at low temperature had earlier detection of heartbeat, longer incubation length, lower growth rate post-hatch, and higher post-hatch mortality, compared to eggs incubated under intermediate temperatures. Higher incubation temperatures resulted in shorter incubation length, earlier detection of heart rate and faster righting time. As predicted, embryo and chick mortality were greater in the PCB-dosed birds incubated at intermediate and high temperatures. Incidence of distended yolk sacs (%) also increased with PCB exposure in all temperature groups, with the largest increase in the high temperature group. Overall, our results show that low incubation temperature can cause greater adverse effects than PCB-126 exposure alone, but that negative effects of PCB-126 exposure are exacerbated by high incubation temperatures. These findings suggest that in natural settings, shorebird embryos may be more susceptible to contaminant exposure when incubated at temperatures either below or above the apparent optimum.

在卵生野生动物中，许多关键的生理和行为成分受到胚胎和孵化后早期发育环境的强烈影响。因此，这些物种的早期生命阶段极易受到自然和人为压力的影响。例如，在鸟类中，孵化温度可能会影响卵子的发育速度，同时也会影响污染物在人体组织中的代谢和吸收，从而对胚胎和孵化后的发育产生潜在的倍增影响。我们测试了以下假设：早期污染物暴露和温度胁迫的累积效应可能会对禽类发育产生负面影响，并且可能具有比任何一个应激源都更有害的相互作用。使用控制性卵注射和温育研究双翅目（Charadrius vociferous）将鸡蛋暴露于已知的内分泌干扰物3,3'，4,4'，5-五氯联苯（PCB-126）并在低（36°C），中（37.5°C）或高（39 °C）温度。我们的结果表明，与在中等温度下温育的卵相比，在低温下温育的卵具有更早的心跳检测，更长的温育长度，孵化后较低的生长速率和较高的孵化后死亡率。较高的孵育温度导致较短的孵育时间，较早的心率检测和较快的恢复时间。如预测的那样，在中温和高温下孵育的多氯联苯给药的禽类中，胚胎和雏鸡的死亡率更高。在所有温度组中，暴露于PCB的卵黄囊的发生率（％）也均增加，其中高温组的增幅最大。总体，我们的结果表明，较低的孵育温度会比单独暴露于PCB-126引起更大的不利影响，但是较高的孵育温度会加剧PCB-126暴露的负面影响。这些发现表明，在自然环境中，在低于或高于表观最佳温度下孵育时，shore鸟胚胎可能更容易受到污染物的影响。