The Effect of Thermal Variance on the Phenotype of Marine Turtle Offspring

Abstract

Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.

Influence of incubation temperature on sea turtle hatchling quality

“…The combination of these laboratory and field studies reveal that at cool temperatures (<27 °C), self-righting, crawling and swimming ability decrease, are at a maximum at intermediate temperatures (28-32 °C), and decrease again at hot temperatures (>32 °C). Hatching success in field nests also decreases at hot nest temperatures (Matsuzawa et al 2002;Maulany et al 2012b;Horne et al 2014). These observations suggest that the relationship between incubation temperature and hatchling locomotor performance can be envisaged as a classic U-shaped performance reaction norm where peak performance occurs over an "optimal" range of temperatures (28-32 °C), and performance decreases at temperatures below and above this optimal range (Fig.…”

“…Nest temperature data from sea turtle nesting beaches indicate that mean nest temperatures are typically in the 29-32 °C range, which is in the optimal developmental range, but temperatures can approach 34 °C and above during the last week of incubation when metabolic heat produc-tion is greatest (e.g. Glen et al 2003;Booth & Freeman 2006;Chu et al 2008;LeBlanc et al 2012;Maulany et al 2012a;Horne et al 2014). Hence, if global air temperatures rise by 2-3 °C within the next 50 years (ICPP 2013), and sand temperature at incubation beaches rise by this amount, sea turtle nest temperatures at current nesting beaches will enter the range that results in highly female-biased hatchling sex ratios, decreased nest emergence success, and decreased hatchling locomotor performance.…”

The true depth of the Mediterranean plastic problem: Extreme microplastic pollution on marine turtle nesting beaches in Cyprus

“…Marine turtle nesting success is strongly influenced by extrinsic factors during egg development (McGehee, 1990;Ackerman, 2002;Warner, 2014). In particular, temperature influences the duration and success of development and determines the sex of offspring (Ackerman, 2002;Horne et al, 2014;Hays et al, 2017). High microplastic abundance within sand in turtle nests could impact hatching success and skew hatchling sex ratios (Cooper and Corcoran, 2010;Nelms et al, 2016).…”

A Preliminary Study of Using Some Nest Characteristics as Indicators for the Size of Green Turtle (Chelonia mydas) Hatchlings

“…Reducing the predictor parameters in the univariate analysis did not improve the results but instead, resulted in worse performing models with overall F-test results having higher p values (results not shown). [15] who found that hatchling mass for loggerhead sea turtles on Alagadi beach in northern Cyprus was not significantly influenced by CS and ND. While one nest characteristic, i.e.…”