Somatic Growth and Maturity for Four Species of River Cooter Including , , , and .

is a genus of commonly occurring freshwater turtles with limited growth information across their long lifespans. We used 11,361 mark-recapture events to estimate the somatic growth rates of , , , and from freshwater springs and developed a Bayesian growth model to estimate the species-specific, site-specific, and individual effects on growth. We corroborated evidence for fast juvenile growth and slower adult growth in but found uncommonly fast growth rates, with turtles doubling or tripling in size in the first year.

Age-specific growth and maturity estimates for the flatback sea turtle (Natator depressus) by skeletochronology.

To address a major knowledge gap for flatback sea turtles (Natator depressus), a species endemic to Australia and considered 'Data Deficient' for IUCN Red List assessment, we present the first-ever skeletochronology-derived age and growth rate estimates for this species. Using a rare collection of bone samples gathered from across northern Australia, we applied skeletochronology and characterized the length-at-age relationship, established baseline growth rates from the hatchling to adult life stages, and produced empirical estimates of age-at- and size-at-sexual-maturation (ASM, SSM). We analyzed humeri from 74 flatback sea turtles ranging in body size from 6.

Stable isotope discrimination factors and between-tissue isotope comparisons for bone and skin from captive and wild green sea turtles (Chelonia mydas).

Rationale: The ecological application of stable isotope analysis (SIA) relies on taxa- and tissue-specific stable carbon (Δ C) and nitrogen (Δ N) isotope discrimination factors, determined with captive animals reared on known diets for sufficient time to reflect dietary isotope ratios. However, captive studies often prohibit lethal sampling, are difficult with endangered species, and reflect conditions not experienced in the wild.

Methods: We overcame these constraints and determined the Δ C and Δ N values for skin and cortical bone from green sea turtles (Chelonia mydas) that died in captivity and evaluated the utility of a mathematical approach to predict discrimination factors.

Intrapopulation variability in the timing of ontogenetic habitat shifts in sea turtles revealed using δ N values from bone growth rings.

Determining location and timing of ontogenetic shifts in the habitat use of highly migratory species, along with possible intrapopulation variation in these shifts, is essential for understanding mechanisms driving alternate life histories and assessing overall population trends. Measuring variations in multi-year habitat-use patterns is especially difficult for remote oceanic species. To investigate the potential for differential habitat use among migratory marine vertebrates, we measured the naturally occurring stable nitrogen isotope (δ N) patterns that differentiate distinct ocean regions to create a 'regional isotope characterization', analysed the δ N values from annual bone growth layer rings from dead-stranded animals, and then combined the bone and regional isotope data to track individual animal movement patterns over multiple years.

Effects of demineralization on the stable isotope analysis of bone samples.

Rationale: The sampling of sequential, annually formed bone growth layers for stable carbon (δ(13)C values) and nitrogen (δ(15)N values) isotope analysis (SIA) can provide a time series of foraging ecology data. To date, no standard protocol exists for the pre-SIA treatment of cortical samples taken from fresh, modern, bones.

Methods: Based on the SIA of historical bone, it is assumed that fresh bone samples must be pre-treated with acid prior to SIA.

Age and residency duration of loggerhead turtles at a North Pacific bycatch hotspot using skeletochronology.

For migratory marine animals, like sea turtles, effective conservation can be challenging because key demographic information such as duration of life stages and exposure to spatially explicit threats in different habitats are often unknown. In the eastern Pacific near the Baja California Peninsula (BCP), Mexico, tens of thousands of endangered North Pacific loggerhead sea turtles () concentrate at a foraging area known to have high rates of fishery bycatch. Because stage survivorship of loggerheads in the BCP will vary significantly depending on the number of years spent in this region, we applied skeletochronology to empirically estimate residency duration in this loggerhead hotspot.