Aerial audiograms for juvenile green sea turtles (<i>Chelonia mydas</i>).

<p>Spectrum level background noise is represented the dotted line (dB re: 20 μPa/√Hz).</p

Underwater audiograms for juvenile green sea turtles (<i>Chelonia mydas</i>) in terms of pressure.

<p>“A” denotes the use of anesthesia when recording auditory evoked potentials. The hearing sensitivity of L4 was measured twice, with and without anesthesia (mean calculation uses the mean of these two measurements). Spectrum level background noise is represented by the dotted line (dB re: 1 μPa/√Hz).</p

Underwater pressure thresholds (dB re: 1 μPa-rms) for individual juvenile green sea turtles (<i>Chelonia mydas</i>), and mean thresholds for all turtles combined.

<p>Frequencies tested with no detected auditory evoked potential response are presented with > “highest sound pressure level presented” (dB re: 1 μPa-rms).</p

Juvenile green sea turtle (<i>Chelonia mydas</i>, L4) underwater (A) and aerial (B) input-output functions of auditory evoked potential level (μV) as a function of stimulus sound pressure level.

<p>Juvenile green sea turtle (<i>Chelonia mydas</i>, L4) underwater (A) and aerial (B) input-output functions of auditory evoked potential level (μV) as a function of stimulus sound pressure level.</p

Comparison of mean (± 1 SD) underwater and aerial audiograms for juvenile green sea turtles (<i>Chelonia mydas</i>) in terms of pressure (A) and intensity (B).

<p>Comparison of mean (± 1 SD) underwater and aerial audiograms for juvenile green sea turtles (<i>Chelonia mydas</i>) in terms of pressure (A) and intensity (B).</p

Underwater auditory evoked potential waveforms recorded from a juvenile green sea turtle (<i>Chelonia mydas</i>, L4), and corresponding stimuli levels in response to an underwater signal of 300 Hz.

<p>Underwater auditory evoked potential waveforms recorded from a juvenile green sea turtle (<i>Chelonia mydas</i>, L4), and corresponding stimuli levels in response to an underwater signal of 300 Hz.</p

2048-point fast Fourier transforms of recorded auditory evoked potentials (presented in Fig 1) showing a peak at twice the frequency presented (600 Hz).

<p>Threshold level is presented in black (92 dB re: 1 μPa-rms).</p

Aerial pressure thresholds (dB re: 20 μPa-rms) for individual juvenile green sea turtles (<i>Chelonia mydas</i>), and mean thresholds for all turtles combined.

<p>Frequencies tested with no detected auditory evoked potential response are presented with > “highest sound pressure level presented” (dB re: 1 μPa-rms).</p

Female-Bias in a Long-Term Study of a Species with Temperature-Dependent Sex Determination: Monitoring Sex Ratios for Climate Change Research

<div><p>Alterations have occurred and continue to manifest in the Earth’s biota as a result of climate change. Animals exhibiting temperature dependent sex determination (TSD), including sea turtles, are perhaps most vulnerable to a warming of the Earth as highly skewed sex ratios can result, potentially leading to population extinction resulting from decreased male recruitment. Recent studies have begun to quantify climate change impacts to sea turtle populations, especially in terms of predicting effects on hatchling sex ratios. However, given the inherent difficulty in studying sex ratios at this life stage, a more accurate assessment of changes in population sex ratios might be derived by evaluating the juvenile portion of foraging aggregations. We investigated the long-term trend in sex ratio of a juvenile loggerhead (<i>Caretta caretta</i>) sea turtle population inhabiting Pamlico and Core Sounds, North Carolina, USA. We used plasma testosterone reference ranges measured using radioimmunoassay (RIA) to assign sex for 959 turtles and confirmed sex assignment of a subset (N = 58) of the sampled turtles through laparoscopic examination of their gonads. Our results demonstrate that for this particular population of loggerheads, sex ratios (3Females:1Male) had not significantly changed over a 10 year period (1998–2007), nor showed any significant difference among 5-cm straight carapace length (SCL) size classes. Ultimately, these findings provide a basis for comparison with future sex ratios, and highlight the importance of establishing similar long-term studies monitoring secondary, rather than primary, sex ratios, so that needed mitigation measures to climate change impacts can be implemented.</p></div

Number of females, males, percentage females (95% confidence intervals) and χ2 values across size classes (straight carapace length) for juvenile loggerheads (<i>Caretta caretta</i>).

<p>Number of females, males, percentage females (95% confidence intervals) and χ2 values across size classes (straight carapace length) for juvenile loggerheads (<i>Caretta caretta</i>).</p