Are thermal barriers "higher" in deep sea turtle nests?

Area of Science:

• Marine Biology
• Ecology
• Climate Change Biology

Background:

• Species' thermal tolerances are shaped by habitat temperature ranges.
• Daniel Janzen's hypothesis suggests high climatic uniformity creates barriers to animal movement.
• Sea turtle eggs experience thermal stability influenced by nesting depth.

Purpose of the Study:

• To assess the relationship between thermal uniformity and thermal tolerance in sea turtle nests.
• To understand how thermal barriers affect embryo mortality in different sea turtle species.

Main Methods:

• Compared thermal uniformity and tolerance in nests of three sea turtle species.
• Defined 'high' thermal barriers as small thermal changes having large effects, and 'low' as the opposite.
• Analyzed nesting depth's effect on mean temperature and fluctuation.

Main Results:

• Deeper nests exhibited lower mean temperatures and less fluctuation.
• Leatherback turtle nests (deepest) showed higher thermal barriers, with increased embryo mortality at lower high temperatures.
• Embryo mortality rose as temperatures approached the upper transitional range for sex determination in leatherback and olive ridley turtles.

Conclusions:

• Thermal barriers vary significantly among sea turtle species based on nesting depth.
• Climate warming impacts on embryo mortality will likely differ across sea turtle populations.
• Population resilience to climate change may depend on the balance between temperatures producing females and those causing embryo mortality.