Interspecific differences in egg production affect egg trace element concentrations after a coal fly ash spill

Area of Science:

• Comparative physiology
• Ecology
• Environmental toxicology

Background:

• Maternal transfer of trace elements to offspring occurs during egg production in oviparous vertebrates.
• Egg trace element concentrations can reflect dietary intake and stored reserves, varying with reproductive strategies.
• Turtles, with slow, synchronous egg production, are expected to have uniform egg trace element levels, unlike birds with sequential egg production.

Purpose of the Study:

• To test if stinkpot turtle (Sternotherus odoratus) clutches have lower variability and higher repeatability in trace element concentrations (barium, selenium, strontium, thallium) compared to tree swallows (Tachycineta bicolor).
• To investigate the influence of egg production synchronicity and resource acquisition on interspecific differences in egg trace element variability.
• To assess trace element levels in eggs from a coal ash-impacted site.

Main Methods:

• Comparative analysis of barium, selenium, strontium, and thallium concentrations in eggs from stinkpot turtles and tree swallows.
• Statistical assessment of variability and repeatability of trace element concentrations within clutches for both species.
• Examination of potential laying order effects on trace element concentrations in tree swallow eggs.

Main Results:

• Stinkpot turtle clutches exhibited significantly lower variability and higher repeatability for all four trace elements compared to tree swallow clutches.
• Mean concentrations of barium, selenium, strontium, and thallium were significantly higher in stinkpot turtle eggs than in tree swallow eggs.
• Laying order significantly influenced trace element variability in tree swallow eggs, but not in stinkpot turtle eggs.

Conclusions:

• Interspecific differences in egg production rate and resource utilization influence egg trace element variability.
• Turtles' slow, synchronous egg formation leads to more consistent maternal transfer of trace elements than birds' rapid, sequential egg formation.
• Environmental factors, such as coal ash spills, can impact egg trace element concentrations, with species-specific differences in accumulation patterns.