Effectiveness of different strategies to mitigate the impacts of projected changes in temperature on sea turtle reproductive output

Abstract

Sea turtles reproduction is influenced by environmental temperature. Projected changes in global temperatures will likely alter their reproductive output (e.g. hatchling sex ratio, hatching success). Concern over the potential impacts from increases in temperature on sea turtle reproductive output has prompted identification of a range of management strategies to mitigate these impacts (e.g. in situ manipulation of incubation temperature using shade, sprinklers). However, little is known about how effective these strategies are at mitigating the impacts of increased temperature. To provide insights into this, we tested the effectiveness of two commonly proposed strategies (sprinkling and shading) to reduce sand temperature and potentially counteract projected impacts of increases on temperature on the northern Great Barrier Reef (nGBR) green turtle population. For this, we compared sand temperature at turtle nest depth (50 cm) under a control environment in the open (100% sunshine) with 5 different treatments: (1) sprinkling during the day (OD) and (2) at night (ON) at an open area, (3) shade, (4) sprinkling during the day (SD) and (5) at night (SN) at a shaded area. Not all strategies reduced the sand temperatures. OD and shading on rainy days increased sand temperature by 0.83 ± 1.20°C and 0.96 ± 0.41°C respectively, when compared to the control. Sand temperature was reduced the most under ON (2.23 ± 0.06°C cooler), and SN (1.43 ± 0.94°C cooler). If the strategies that reduced sand temperature were implemented they would substantially counteract the projected impacts on the nGBR green turtle population. Although potentially effective, it is suggested that they should be implemented when impacts from climate change become direr and more information on the ecological risks associated with the strategies are available