Wyneken, Jeanette

Of the seven sea turtle species, the critically endangered leatherback sea turtle (Dermochelys coriacea) 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.

Assessment and management of sea turtle populations is often limited by a lack of available
data pertaining to at-sea distributions at appropriate spatial and temporal resolutions.
Assessing the spatial and temporal distributions of marine turtles in an open system poses
both observational and analytical challenges due to the turtles’ highly migratory nature. Surface
counts of marine turtles in waters along the southern part of Florida’s east coast were
made in and adjacent to the southeast portion of the Florida Current using standard aerial
surveys during 2011 and 2012 to assess their seasonal presence. This area is of particular
concern for sea turtles as interest increases in offshore energy developments, specifically
harnessing the power of the Florida Current. While it is understood that marine turtles use
these waters, here we evaluate seasonal variation in sea turtle abundance and density over
two years. Density of sea turtles observed within the study area ranged from 0.003 turtles
km-2 in the winter of 2011 to 0.064 turtles km-2 in the spring of 2012. This assessment of
marine turtles in the waters off southeast Florida quantifies their in-water abundance across
seasons in this area to establish baselines and inform future management strategies of
these protected species.

As global temperatures increase throughout the coming decades, species ranges will shift. New combinations of abiotic
conditions will make predicting these range shifts difficult. Biophysical mechanistic niche modeling places bounds on an
animal’s niche through analyzing the animal’s physical interactions with the environment. Biophysical mechanistic niche
modeling is flexible enough to accommodate these new combinations of abiotic conditions. However, this approach is
difficult to implement for aquatic species because of complex interactions among thrust, metabolic rate and heat transfer.
We use contemporary computational fluid dynamic techniques to overcome these difficulties. We model the complex 3D
motion of a swimming neonate and juvenile leatherback sea turtle to find power and heat transfer rates during the stroke.
We combine the results from these simulations and a numerical model to accurately predict the core temperature of a
swimming leatherback. These results are the first steps in developing a highly accurate mechanistic niche model, which can
assists paleontologist in understanding biogeographic shifts as well as aid contemporary species managers about potential
range shifts over the coming decades.