Sea turtles--Florida

Antibiotic resistance is a growing concern due to the improper use of antibiotics. Not only is antibiotic resistance increasingly occurring in human populations, but it appears to be spreading in wildlife populations too due to drug overuse and misuse in medicine, farming, and industrial settings, and the subsequent release into watersheds. This project examined the prevalence of antibiotic resistant bacteria in the hindgut microbiome of green (Chelonia mydas) (n=60) and loggerhead (Caretta caretta) (n=57) sea turtles. Hindgut swabs were cultured for gram negative bacteria and exposed to 6 antibiotics. 83.3% of samples were resistant or intermediately resistant to at least one antibiotic, and 27.7% of samples were resistant or intermediately resistant to three antibiotics. This study provides more information regarding the relationship between turtle characteristics and the presence of antibiotic resistance in the hindgut of Florida sea turtles, as well as examine the types of bacteria found in the hindgut.

The reproductive behavior of migratory organisms is difficult to characterize as
the mating behavior can be difficult to observe. For some species, one sex can be readily
observable, but the other may remain hidden, confounding attempts to assess population
demographics. For such species, it can be difficult to determine the sex ratio of the
population. Without accurate accounts of the numbers of males and females, conservation
methods may be insufficient and their performance unclear. Alternative methods of
measuring sex ratios therefore must be used to estimate the number of individuals and
assess breeding behavior. Here I identified breeding sex ratios (BSR) measured using
paternity analysis of offspring through exclusion analysis to quantify the numbers of
males contributing. Here I discuss the mating behavior of three species of marine turtle
that nest in southern Florida: the loggerhead (Caretta caretta), the leatherback (Dermochelys coriacea), and the green sea turtle (Chelonia mydas) at three beaches
(Boca Raton, Juno Beach, and Sanibel Island) from 2013-2017; over 400 nesting females
were identified and genotyped and almost 7,000 hatchlings were collected and
genotyped. Females from all three species successfully mated with more than one male in
all years analyzed demonstrating multiple paternity of clutches. For loggerheads, many
male genotypes were identified, suggesting that females likely mate en route to their
nesting grounds, inducing a male-biased BSR. Examination of females that were sampled
more than once per season (repeats), evidence of sperm storage was found for all nests
and some turtles might mate in between nesting events. Leatherback females displayed a
higher rate of multiple paternity than was previously published for other Caribbean
nesting sites; I hypothesize that this result may be due to a mainland nesting beach effect.
The leatherback BSR over all years was approximately 1:1, and one male was identified
fathering than two different females’ nests (polygyny). For green turtles, multiple
paternity was found and there was evidence of polygyny. Across all three species,
evidence for indirect benefits of mating multiply (hatching success or larger hatchlings)
was weak or not supported. Together, the four studies contribute to the overall body of
reproductive behavior studies.

The beaches of Boca Raton, Florida serve as a rookery site for three species of sea turtles, all of whom are considered either federally threatened (loggerhead) or endangered (green turtle, leatherback). At this beach, nest security was though to be compromised by both human visitors and increasing mammalian predators populations. Since 1988, the City has employed the use of square wire cages to protect the nests from both factors. Cage effectiveness was questioned due to high predation rates, despite caging. Evaluations to determine the effectiveness of this method were conducted. Pairs of caged (control) and uncaged (experimental) nests were established in zones reflecting high/low traffic and high/low predator attacks and monitored on a daily basis. Following emergence, nest fate comparisons were made. Decoy cages were used to determine predator efficiency. Data suggest that cages are not needed in areas of low traffic or predator attacks. Additional data suggest that cages actually attract, rather than deter, mammalian predators.

Caging of sea turtle nests has used by City of Boca Raton's sea turtle conservation program to deter terrestrial predators and reduce human disturbance. The juxtaposition of nest cages and artificial lighting may pose serious threats to hatchlings. I addressed possible negative effects of cages on sea turtle hatchlings' seafinding abilities and potential "cage-trapping" under natural and artificially illuminated conditions. Cages did not effect hatchling orientation on artificially illuminated or dark beaches. Hatchlings did not experience any delay in cage escape on dark beaches, but a significant number were trapped inside the cages on artificially illuminated beaches. The highest incidence of trapping occurred on nights surrounding a new moon. Disoriented hatchlings exited cages either after city lighting was reduced (past midnight) or as natural levels of illumination increased shortly before sunrise. When cages were darkened all turtles escaped but many still exhibited signs of disorientation.

Although the red imported fire ant (Solenopsis invicta ) is known to kill sea turtle hatchlings, little research has focused on sub-lethal effects of ant attacks on hatchlings emerging from nests. Sea turtle hatchlings of two species (Caretta caretta and Chelonia mydas) exposed to fire ants during incubation and emergence were collected on Juno Beach, Florida. Hatchlings were maintained for ten days in a common saltwater outdoor pool at the Marinelife Center, Juno Beach. Hatchlings showing pustules diagnostic of S. invicta stings were compared to non-stung controls in terms of survival, growth (mass and SCL) and initial crawling strength. Loggerhead hatchlings showed a significant decrease in survival, growth, and crawling strength when stung by fire ants. In contrast, no significant differences were seen in the survival, growth, and crawling strength of green turtle hatchlings when stung by fire ants.