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- Title
- Breeding sex ratios of three imperiled marine turtles nesting in southern Florida.
- Creator
- Lasala, Jacob, Hughes, Colin, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Sound assessment of the status of a threatened or endangered organism depends on understanding key aspects of behavior throughout its life history. Sometimes organisms can be difficult to observe and key aspects of behavior may not be accessed directly. Alternative assessment techniques include using molecular markers to identify fundamental relationships among males and females. In the context of assessing the status of imperiled populations’ sex ratios, population size and the relatedness...
Show moreSound assessment of the status of a threatened or endangered organism depends on understanding key aspects of behavior throughout its life history. Sometimes organisms can be difficult to observe and key aspects of behavior may not be accessed directly. Alternative assessment techniques include using molecular markers to identify fundamental relationships among males and females. In the context of assessing the status of imperiled populations’ sex ratios, population size and the relatedness of the individuals are important metrics. Environmental sex determination directs developing marine turtle sex so that primary sex ratios depend upon weather and climate; those sex ratios are estimated by proxies. Adult population sizes are inferred from numbers of females nesting on the beach, but numbers of males are unknown. Male breeding population size can be estimated from subtracting maternal genotypes from genotypes of offspring exclusion analyses. The resulting adult sex ratios differ greatly from those estimated for hatchlings. To refine current adult sex ratios in ways that are relevant to production of future generations and add to our understanding of effective population size we compare the breeding sex ratios the number of males and females contributing to a population of three species of sea turtles nesting in southern Florida. We will use the same genetic data to measure relatedness of the female nesters and the male contributors and describe how that relates to genetic flow and population structure.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005893
- Format
- Document (PDF)
- Title
- Experimental assessment of moisture effects on loggerhead sea turtle sex ratios.
- Creator
- Lolavar, Alexandra, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Nest sand temperature strongly influences development of sea turtle embryos and sex differentiation; however in nature eggs experience temperature along with other environmental factors. We tested the hypothesis that moisture effects sea turtle hatchling sex ratios. We studied the relationships among moisture, temperature, and loggerhead Caretta caretta sex ratios in an experimental study. Eggs were incubated in sterile nest sand in the laboratory under different moisture regimes to test the...
Show moreNest sand temperature strongly influences development of sea turtle embryos and sex differentiation; however in nature eggs experience temperature along with other environmental factors. We tested the hypothesis that moisture effects sea turtle hatchling sex ratios. We studied the relationships among moisture, temperature, and loggerhead Caretta caretta sex ratios in an experimental study. Eggs were incubated in sterile nest sand in the laboratory under different moisture regimes to test the role of humidity at a constant incubation temperature. Incubator temperature was set at 29.4 degrees C, a temperature that is slightly above the temperature that should yield a 1:1 sex ratio. Nest moisture was maintained by daily DI water treatments and high relative humidity was maintained with the aid of a mist humidifier throughout incubation. All hatchlings were collected, raised for several months and sexed laparoscopically to establish sex ratios for each treatment. The experimental treatments tested the effects of i very high moisture, ii moisture with potential for evaporative cooling, and iii moisture added at average rain temperatures plus the potential for evaporative cooling. The nests were expected to produce a moderate female bias if moisture played no role. We found 87-96 males across all experimental treatments. Our results support our hypothesis. High moisture conditions can produce shifts in developmental response from that expected based on temperature alone.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005897
- Format
- Document (PDF)
- Title
- Using an immunohistochemical approach to identify the sex of marine turtles.
- Creator
- Tezak, Boris, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Marine turtles exhibit temperature-dependent sex determination (TSD). During critical periods of embryonic development, the nest’s thermal environment directs whether an embryo will develop as a male or a female. At warmer sand temperatures the nest tends to produce female-biased sex ratios. The rapid increase of global temperature highlights the need for a clear assessment of effects on sea turtle sex ratios. However, identifying hatchling sex ratios at rookeries remain coarse estimates due...
Show moreMarine turtles exhibit temperature-dependent sex determination (TSD). During critical periods of embryonic development, the nest’s thermal environment directs whether an embryo will develop as a male or a female. At warmer sand temperatures the nest tends to produce female-biased sex ratios. The rapid increase of global temperature highlights the need for a clear assessment of effects on sea turtle sex ratios. However, identifying hatchling sex ratios at rookeries remain coarse estimates due to the lack of any external gender markers. We rely mainly upon laparoscopic procedures to verify a hatchling sex; however, in some species, morphological sex can be ambiguous even at the histological level. Recent studies using immunohistochemical techniques identified that red-eared slider (Trachemys scripta) embryos over-expressed a particular cold-induced RNA binding protein in the ovaries in comparison to the testes. This principle allows the distinction between females and males. We developed a variation of this technique and successfully identified the sexes of loggerhead sea turtle (Caretta caretta) hatchlings, as confirmed by standard histological and laparoscopic methods that reliably identifies the sex in this species. Next, we tested a more challenging species, the leatherback turtle (Dermochelys coriacea), which retains many neotenic features. The morphology of leatherback hatchling gonads remains difficult to interpret, particularly when dead-in-nest hatchlings and embryos are the source tissues. In summary, this new and more efficient technique enhances our ability to investigate and identify baseline hatchling sex ratios, a critical progression in assessing global climate change on sea turtle populations.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005915
- Format
- Document (PDF)
- Title
- A Bird’s Eye View: Assessing Sea Turtle Presence in Florida’s Gulf Stream and Coastal Waters.
- Creator
- Bovery, Caitlin M., Wyneken, Jeanette, Graduate College
- Abstract/Description
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Assessing the presence or absence of marine turtles in an open system poses both observational and analytical challenges due to the migratory nature of marine turtles and their use of large current systems. Concentrations can shift as turtles shift between oceanic and neritic stages and migrate between breeding and foraging grounds. We conducted standard aerial surveys monthly from 2011-2012 to capture seasonal snapshots of sea turtle presence. Each survey covered the area from a northern...
Show moreAssessing the presence or absence of marine turtles in an open system poses both observational and analytical challenges due to the migratory nature of marine turtles and their use of large current systems. Concentrations can shift as turtles shift between oceanic and neritic stages and migrate between breeding and foraging grounds. We conducted standard aerial surveys monthly from 2011-2012 to capture seasonal snapshots of sea turtle presence. Each survey covered the area from a northern boundary near West Palm Beach, Florida 26°43′N to a southern boundary near Miami, Florida 25°40′N, USA with transects up to 20-50 km offshore. 218 turtles were observed during the course of this study 2011: n 79; 2012: n 139. We summarize our sightings by season: Winter December-February, Spring March-May, Summer June-August, and Fall September-November to examine trends in presence of sea turtles. A variety of sizes were observed throughout the year, indicating the presence of several life stages of marine turtles in Florida’s waters during all four seasons. While it is understood that marine turtles use the waters off the eastern coast of Florida, here we document the magnitude of the shift in turtle presence each season throughout two years and where the turtles occur most frequently. Our assessment of marine turtles in the waters off of southeast Florida provide valuable metrics describing the in-water biology of these turtles and for the first time, provide a quantitative assessment of annual and inter-annual fluctuations in presence in the major current and along our coast.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005804
- Format
- Document (PDF)
- Title
- Comparison of growth patterns in three species of juvenile sea turtles.
- Creator
- Pate, Jessica Hope, Salmon, Michael, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Sea turtles are most vulnerable to predators during early growth when they are small and relatively defenseless. Predation risk might be reduced by evolving effective behavioral as well as morphological defenses. Loggerhead Caretta caretta and green turtle Chelonia mydas neonates hide in weed lines. They also become wider faster than they increase in length, a pattern of positive allometry that may function to minimize the time during growth when they are vulnerable to gape-limited predators....
Show moreSea turtles are most vulnerable to predators during early growth when they are small and relatively defenseless. Predation risk might be reduced by evolving effective behavioral as well as morphological defenses. Loggerhead Caretta caretta and green turtle Chelonia mydas neonates hide in weed lines. They also become wider faster than they increase in length, a pattern of positive allometry that may function to minimize the time during growth when they are vulnerable to gape-limited predators. Virtually nothing is known about how young leatherbacks grow which might reduce their vulnerability to predators. To find out, we reared 30 hatchlings from 10 nests in the laboratory for up to 14 weeks, post-emergence. Once weekly, each turtle’s body proportions straight line carapace length, SCL; straight line carapace width, SCW were measured to yield an observed pattern of growth. That observed growth pattern was compared to an expected pattern in which the turtles retained their hatchling proportions as they grew larger isometric growth. We found that all of the leatherbacks showed allometric growth as their SCW increased more rapidly than their SCL. Thus as they grew, leatherbacks became proportionally wider, though this growth was not as pronounced as seen in loggerheads and green turtles. We also modeled vulnerability to gape-limited predators. Leatherbacks, like loggerhead and green turtles, were less vulnerable to predation when growing allometrically. These results provide insight into a little know sea turtle life stage and aids in understanding how morphology in early development may reduce predation risk.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005846
- Format
- Document (PDF)
- Title
- Getting hooked: a study to better understand sea turtle longline by catch.
- Creator
- Warraich, Natasha, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Loggerhead and leatherback sea turtles are often caught as longline bycatch in fisheries worldwide. These species of sea turtle differ greatly in life history, morphology, and the ways they are hooked. Leatherbacks tend to be “foul hooked,” externally in the shoulder or flippers, while loggerheads tend to be hooked in the mouth or they swallow the bait so that hooking is internal esophagus or stomach. The numbers of loggerheads and leatherbacks caught decreased after changes in gear, bait and...
Show moreLoggerhead and leatherback sea turtles are often caught as longline bycatch in fisheries worldwide. These species of sea turtle differ greatly in life history, morphology, and the ways they are hooked. Leatherbacks tend to be “foul hooked,” externally in the shoulder or flippers, while loggerheads tend to be hooked in the mouth or they swallow the bait so that hooking is internal esophagus or stomach. The numbers of loggerheads and leatherbacks caught decreased after changes in gear, bait and time of sets. However the proportion of leatherback mouth hookings increased while foul hooking decreased. We described and compared prey approach and attack behavior of both species in the presence and absence of visual targets. Waterborne squid and jellyfish odors were used to elicit feeding behavior in the two species. Visual targets were necessary to elicit biting. Loggerheads approach their prey with the mouth wide open, have exceptionally good aim and usually bite their intended target. This accuracy is consistent with the mouth and internal hooking. Leatherbacks frequently overshoot, miss their intended target then have to re-approach the target multiple times before making contact. Leatherback feeding behavior is disrupted easily if the body or flippers are touched during prey approach. This reapproach behavior may make leatherbacks more prone snagging on lines rigged with J-hooks. The shift by some fisheries to circle hooks, which are less prone to snagging, by give the leatherbacks multiple chances to attack the bait and ingest it without getting hooked externally.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005861
- Format
- Document (PDF)
- Title
- How many males are there? An examination of operational sex ratio within marine turtle nesting populations in southern Florida.
- Creator
- Lasala, Jacob, Wyneken, Jeanette, Graduate College
- Abstract/Description
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Characterizing a species mating system is integral to understanding its natural history and is critical to the development of effective conservation strategies. A mating system is typically described by examining a single population and subsequently drawing inferences on the whole of the species. Variation among populations and gaps in understanding of a species often are revealed when studies are compared between several locations. The majority of available marine turtle mating system data...
Show moreCharacterizing a species mating system is integral to understanding its natural history and is critical to the development of effective conservation strategies. A mating system is typically described by examining a single population and subsequently drawing inferences on the whole of the species. Variation among populations and gaps in understanding of a species often are revealed when studies are compared between several locations. The majority of available marine turtle mating system data stem from nesting females or hatchlings scurrying off the beach. This practice left glaring holes in the understanding of these imperiled organisms in particular with respect to males. We use exclusion paternity analysis to compare the genotype of a nesting female with genotypes from a subset of her offspring and deduce male genotypes to identify and count the number of males contributing per clutch. Loggerheads Caretta caretta, green turtles Chelonia mydas and tleatherbacks Dermochelys coriacea are protected species with spatially and temporally overlapping nesting beaches. The genotypes of the three species nesting in southern Florida will be compared among clutches to define mating systems. Additionally, we will provide the first measure of operational population size for both males and females in southern Florida. Finally, by comparing results from several beaches, the interconnectedness of rookeries through male-mediated gene flow will be determined as well as the relatedness of males. Our approach to establishing the mating systems of hard-to access-life stages will have strong conservation value in strengthening the demographics that form the core of species assessment and management.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005155
- Format
- Document (PDF)
- Title
- From salps to sea turtles: mercury and selenium in leatherback sea turtles (Dermochelys coriacea).
- Creator
- Perrault, Justin R., Wyneken, Jeanette, Miller, Debra L., Graduate College
- Date Issued
- 2011-04-08
- PURL
- http://purl.flvc.org/fcla/dt/3164679
- Subject Headings
- Leatherback turtle, Mercury --Toxicology, Selenium
- Format
- Document (PDF)
- Title
- New paternity analyses may confound current population models for loggerhead sea turtles (caretta caretta).
- Creator
- Lasala, Jacob, Harrison, J. S., Williams, K., Frick, M, Rostal, D. C., Wyneken, Jeanette, Graduate College
- Date Issued
- 2013-04-12
- PURL
- http://purl.flvc.org/fcla/dt/3361944
- Subject Headings
- Loggerhead turtle, Caretta caretta, Polyandry, Population Dynamics
- Format
- Document (PDF)
- Title
- Feeding behavior of loggerhead (caretta caretta) and leatherback (dermochelys coriacea) sea turtles: a model to understand bycatch.
- Creator
- Warraich, Natasha, Wyneken, Jeanette, Graduate College
- Date Issued
- 2013-04-12
- PURL
- http://purl.flvc.org/fcla/dt/3361369
- Subject Headings
- Leatherback turtle, Loggerhead turtle, Feeding behavior in animals, Bycatches (Fisheries)
- Format
- Document (PDF)
- Title
- Spatial and temporal distributions of sea turtles within the Florida Current and surrounding waters and their implications for oceanic energy development.
- Creator
- Bovery, Caitlin M., Wyneken, Jeanette, Graduate College
- Date Issued
- 2013-04-12
- PURL
- http://purl.flvc.org/fcla/dt/3361275
- Subject Headings
- Sea turtles, Florida Current, Sea turtles--Conservation
- Format
- Document (PDF)