Predicting climate warming effects on green turtle hatchling viability and dispersal performance

Ectotherms are considered highly sensitive to rapid climate warming because environmental temperature profoundly governs their performance, fitness and life history. To protect vulnerable species, it is imperative we... [ view full abstract ]

Ectotherms are considered highly sensitive to rapid climate warming because environmental temperature profoundly governs their performance, fitness and life history. To protect vulnerable species, it is imperative we understand the nature and extent of these effects. Yet, while several modelling approaches currently predict thermal effects on some aspects of life history and demography, none consider how temperature simultaneously affects developmental success and offspring phenotypic performance, two key attributes that are needed to comprehensively understand species responses to climate warming. We developed a stepwise, individual-level modelling approach linking biophysical and developmental models with empirically derived performance functions to predict the effects of temperature-induced changes to offspring viability, phenotype and performance, using green sea turtle hatchlings as an ectotherm model. In endangered sea turtles, successful development and dispersal away from natal beaches are determinants of early life-cycle survival, and key to overall population dynamics. Under conservative and extreme warming, our model predicted large effects on performance attributes key to dispersal, as well as notable reductions in offspring viability. Forecast sand temperatures produced smaller, weaker hatchlings, which were up to 40% slower than at present, albeit with increased energy stores. Conversely, increases in sea surface temperatures modestly aided swimming performance. These results show that climate warming has the potential to significantly affect ectotherm traits in ways that disrupt key life history stages. Our exploratory study highlights the need for further development of integrative individual based modeling frameworks to better understand the complex outcomes of climate change for ectotherm species. Such advances could better serve ecologists to highlight the most vulnerable species and populations, encouraging prioritization of conservation effort to the most threatened systems.