Maternal Health Status Correlates with Nest Success of Leatherback Sea Turtles (<em>Dermochelys coriacea</em>) from Florida

<div><p>Of the seven sea turtle species, the critically endangered leatherback sea turtle (<em>Dermochelys coriacea</em>) exhibits the lowest and most variable nest success (i.e., hatching success and emergence success) for reasons that remain largely unknown. In an attempt to identify or rule out causes of low reproductive success in this species, we established the largest sample size (n = 60–70 for most values) of baseline blood parameters (protein electrophoresis, hematology, plasma biochemistry) for this species to date. Hematologic, protein electrophoretic and biochemical values are important tools that can provide information regarding the physiological condition of an individual and population health as a whole. It has been proposed that the health of nesting individuals affects their reproductive output. In order to establish correlations with low reproductive success in leatherback sea turtles from Florida, we compared maternal health indices to hatching success and emergence success of their nests. As expected, hatching success (median = 57.4%) and emergence success (median = 49.1%) in Floridian leatherbacks were low during the study period (2007–2008 nesting seasons), a trend common in most nesting leatherback populations (average global hatching success = ∼50%). One protein electrophoretic value (gamma globulin protein) and one hematologic value (red blood cell count) significantly correlated with hatching success and emergence success. Several maternal biochemical parameters correlated with hatching success and/or emergence success including alkaline phosphatase activity, blood urea nitrogen, calcium, calcium∶phosphorus ratio, carbon dioxide, cholesterol, creatinine, and phosphorus. Our results suggest that in leatherbacks, physiological parameters correlate with hatching success and emergence success of their nests. We conclude that long-term and comparative studies are needed to determine if certain individuals produce nests with lower hatching success and emergence success than others, and if those individuals with evidence of chronic suboptimal health have lower reproductive success.</p> </div

Synopsis of hematologic values for leatherback sea turtles from the literature (Atlantic Ocean) and this study.

a<p>PCV = Packed cell volume, RBC = Red blood cells, WBC = White blood cells.</p>b<p>2007 season only.</p>c<p>Deem et al. (2006); nesting females.</p>d<p>Innis et al. (2010); combined data from directly captured and entangled male and female leatherbacks (not significantly different) from Georgia, USA and Massachusetts, USA.</p>e<p>Estimated from blood cell counts.</p>f<p>Significant difference between directly captured (D, n = 11) and entangled (E, n = 7) leatherbacks.</p>g<p>Significant difference between male and female leatherbacks.</p>h<p>Monocytes (%) = ±SD: Directly captured = 2±1 (n = 11), Entangled = 7±8 (n = 7), Male = 1±2 (n = 9), Female = 4±5 (n = 4); Range: Directly captured = 0–5, Entangled = 0–13, Male = 0–5, Female = 1–11.</p

Least-squares linear regression results for health parameters and date of nesting encounter.

a<p>ALKP = Alkaline phosphatase, BUN = Blood urea nitrogen, CO₂ = Carbon dioxide, Corr = Correlation, PCV = Packed cell volume, RBC = Red blood cell, WBC = White blood cell.</p>b<p>Log transformed.</p>c<p>Rank regression.</p

Synopsis of plasma biochemical data for leatherback sea turtles from this study (Florida).

a<p>ALT = Alanine aminotransferase, ALKP = Alkaline phosphatase, AST = Aspartate aminotransferase, BUN = Blood urea nitrogen, Ca∶P = Calcium∶phosphorus ratio, CK = Creatine kinase, LDH = Lactate dehydrogenase.</p>b<p>2008 season only.</p>c<p>2007 season only.</p

Synopsis of plasma protein electrophoretic values for leatherback sea turtles from the literature and this study.

a<p>Deem et al. (2006); nesting females.</p>b<p>Reported as alpha-1 and alpha-2 proteins. The two fractions were added for comparative purposes.</p>c<p>Innis et al. (2010); combined data from directly captured and entangled male and female leatherbacks from Georgia, USA and Massachusetts, USA (not significantly different).</p>d<p>Total protein determined by a clinical chemistry analyzer, not by refractometry.</p>e<p>Means of males and females were reported separately, but were not significantly different.</p

Least-squares linear regression results for health parameters and HS and ES.

a<p>ALKP = Alkaline phosphatase, BUN = Blood urea nitrogen, Ca∶P = Calcium∶phosphorus ratio, CO₂ = Carbon dioxide, Corr = Correlation, HS = Hatching success, ES = Emergence success, RBC = Red blood cell.</p>b<p>Using rank regression.</p>c<p>0% hatching and emergence success nests removed from statistical tests (subsequently discussed).</p

Map of the nesting beach extending across Juno Beach and Jupiter Beach, Florida, USA.

<p>Map of the nesting beach extending across Juno Beach and Jupiter Beach, Florida, USA.</p