02818nas a2200229   4500008004100000245007000041210006900111260001200180300001200192490000800204520207500212653002002287653002402307653001802331653002202349653001302371653004402384100001802428700002202446700001702468856010302485       2006                        eng d00aMetabolic heating in Mediterranean loggerhead sea turtle clutches0 aMetabolic heating in Mediterranean loggerhead sea turtle clutche  c2006///  a151-1570 v3343 aOffspring sex ratio is an important demographic parameter and, given its determination by incubation temperature in sea turtles, might be a key factor for their conservation under climate warming. An appealing approach to estimate hatchling sex ratios is to measure sand temperatures at nest depth and deduce hatchling sex ratios from a beforehand-established relationship of hatchling sex ratio and sand temperature. Such estimates will only be accurate though if metabolic heat produced by the embryos is considered. Judging whether metabolic heating has a potential effect on hatchling sex ratios without actually measuring temperature within clutches would greatly facilitate monitoring protocols. We tested for a relationship between the amount of metabolic heating and the number of developed embryos as well as clutch size in the largest known loggerhead sea turtle (Caretta caretta) population of the Mediterranean on Zakynthos (Greece). Temperatures were measured within 20 nests as well as at a reference site in the sand at nest depth. Metabolic heating was detected, but only during the last third of the incubation period did nests heat up considerably (1.6 °C on average) above the temperature of the surrounding sand. During the middle third of incubation, when sex is determined, the amount of metabolic heating was negligible. The amount of metabolic heating during the last third of the incubation duration was significantly correlated to the number of offspring developed to at least about 75% of incubation duration. This factor explained nearly 50% of variation in metabolic heating. Metabolic heating was also significantly correlated to clutch size. Given that clutch size within the Mediterranean is largest in Zakynthos loggerheads, we conclude that metabolic heating can be ignored in the estimate of hatchling sex ratios in Mediterranean loggerhead populations. These results thus provide the basis for a feasible monitoring of hatchling sex ratios in the loggerhead sea turtle in the Mediterranean. © 2006 Elsevier B.V. All rights reserved.10aCaretta caretta10aHatchling sex ratio10aMediterranean10aMetabolic heating10aReptilia10aTemperature-dependent sex determination1 aZbinden, J.A.1 aMargaritoulis, D.1 aArlettaz, R.  uhttps://icgf.myspecies.info/content/metabolic-heating-mediterranean-loggerhead-sea-turtle-clutches