Just as organisms do not passively exist in their environment, developing sea turtle embryos affect their own incubation microclimate by producing metabolic heat and other waste products. This metabolic heat ultimately contributes to successful development, but it is unclear how it influences embryonic traits such as hatchling sex, and whether trends exist in the magnitude of metabolic heat produced by different species. In this systematic review, we document all empirical measurements of metabolic heat in sea turtle species, its impact on their development, and explore the methods used to predict nest temperature and how these methods account for metabolic heat. Overall we found metabolic heat increases throughout incubation in all seven species. Typically, the temperature at the center of an egg clutch peaked during the final third of incubation, and exceeded the adjacent sand temperature by 2.5°C. Metabolic heat was not influenced by species or clutch size (n = 16 studies), but this finding was likely influenced by inconsistency in the methods used to measure metabolic heat, and by localized differences in sand properties, such as moisture, albedo, and thermal conductivity. The influence of metabolic heat on embryo sex determination and survival was dependent on the sand temperature surrounding the nest chamber, and had an appreciable affect only when it caused nest temperatures to exceed key thresholds for sex determination and survival. Methods for modeling nest temperature were either correlative (70% of publications) or mechanistic (30% of publications). Correlative models describe relationships between empirical data to predict sand temperature, while mechanistic models are based on physical laws and do not require extrapolation when predicting novel situations, such as climate change. Most correlative models (74%) accounted for metabolic heat when predicting nest temperatures, but no mechanistic models did—largely because they were developed for predicting primary sex ratios, which are widely believed to be unaffected by metabolic heat. Consequently, developing a generalisable mechanistic model that incorporates metabolic heat will be critical for predicting incubation success as the sand temperatures at sea turtle beaches increase due to anthropogenic climate change.

中文翻译：

---

海龟巢中代谢热的系统评价及其对孵化成功影响的建模方法

正如生物不会被动地存在于它们的环境中一样，发育中的海龟胚胎会通过产生代谢热和其他废物来影响它们自身的孵化小气候。这种代谢热最终有助于成功发育，但尚不清楚它如何影响孵化性别等胚胎性状，以及不同物种产生的代谢热的大小是否存在趋势。在这篇系统综述中，我们记录了海龟物种代谢热的所有经验测量及其对它们发育的影响，并探索了用于预测巢穴温度的方法以及这些方法如何解释代谢热。总的来说，我们发现所有七个物种在整个孵化过程中代谢热都会增加。通常情况下，卵窝中心的温度在孵化的最后三分之一期间达到峰值，并超过了相邻的沙温 2.5°C。代谢热不受物种或离合器大小的影响（n = 16 研究），但这一发现可能受到用于测量代谢热的方法不一致以及沙子特性的局部差异的影响，例如湿度、反照率和热电导率。代谢热对胚胎性别决定和存活的影响取决于巢室周围的沙温，并且只有当它导致巢温度超过性别决定和存活的关键阈值时才会产生明显影响。模拟巢穴温度的方法要么是相关的（70% 的出版物），要么是机械的（30% 的出版物）。相关模型描述了预测砂温的经验数据之间的关系，而机械模型基于物理定律，在预测气候变化等新情况时不需要外推。大多数相关模型 (74%) 在预测巢穴温度时考虑了代谢热，但没有机械模型这样做——主要是因为它们是为预测初级性别比而开发的，人们普遍认为这些模型不受代谢热的影响。因此，由于人为气候变化导致海龟海滩的沙温升高，因此开发包含代谢热的通用机械模型对于预测孵化成功至关重要。但没有机械模型这样做——主要是因为它们是为预测初级性别比例而开发的，人们普遍认为初级性别比例不受代谢热的影响。因此，由于人为气候变化导致海龟海滩的沙温升高，因此开发包含代谢热的通用机械模型对于预测孵化成功至关重要。但没有机械模型这样做——主要是因为它们是为预测初级性别比例而开发的，人们普遍认为初级性别比例不受代谢热的影响。因此，由于人为气候变化导致海龟海滩的沙温升高，因此开发包含代谢热的通用机械模型对于预测孵化成功至关重要。