Sean Williamson

Sean Williamson
Monash University (Australia) · School of Biological Sciences, Clayton

Doctor of Philosophy

About

23
Publications
4,797
Reads
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109
Citations
Citations since 2017
19 Research Items
104 Citations
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Introduction
Hi, my research focuses on three broad areas of ecophysiology, spatial ecology, and conservation science and planning. I completed my BSc at the University of Wollongong and University College Cork. I then completed a PhD at Monash University. Following my PhD, I worked for Upwell Turtles (NGO) as a research scientist for one year. Since 2019, I have been a postdoc at Monash and Florida Atlantic University working on conservation, spatial ecology and physiology of turtles, sharks and crocodiles.
Additional affiliations
July 2021 - July 2022
Florida Atlantic University
Position
  • Postdoctoral Fellow
Description
  • I was a Postdoc working with Prof. Jeanette Wyneken in the Marine Science Laboratory at FAU. My research focuses on ecophysiology, spatial ecology, and conservation science and planning for marine megafauna (turtles, sharks, rays and crocodiles). I am also coordinating and managing the Glenn W. and Cornelia T. Bailey Marine SEA Scholars who conduct outreach for the Marine Science Laboratory.
March 2019 - July 2021
Monash University (Australia)
Position
  • Postdoctoral Scientist
Description
  • Worked on a project funded by the Fisheries Research and Development Corporation which is aimed at causing behavioural change of recreational fishers during capture and handling of sharks and rays. Planned and delivered a workshop on the development of best-practice capture and handling guidelines for sharks and rays in recreational fisheries. Designed and conducted surveys of recreational fishers. Conducted extension activities to educate and enable behavioural change in fishers.
January 2012 - January 2013
University of Wollongong
Position
  • Research Assistant
Education
April 2013 - January 2018
Monash University (Australia)
Field of study
  • Biology
February 2007 - February 2012
University of Wollongong
Field of study
  • Double Major (Biology and Environmental Science)

Publications

Publications (23)
Article
Full-text available
Hypoxia within the oviducts maintains embryonic arrest in turtles at the pre-ovipositional stage, which expands the timeframe over which nesting can occur without compromising embryo survival. The arrest can be extended post-oviposition through incubation of eggs in hypoxia. We determined whether crocodilian embryos have this same capacity. We also...
Book
Full-text available
This report summarises the outcomes of a workshop on; prioritisation of species, identification of best-practice capture and handling, design of post-release survival (PRS) studies, and development of effective communication campaigns, for developing positive behavioural change in recreational fishing of Sharks and Rays. This report summarises key...
Article
Full-text available
The cryptic 'lost years' of sea turtles challenge conservation efforts due to unknown movements and habitat utilisation of young life stages. Behavioural information strengthens dispersal and habitat utilisation models estimating unidentified movements. In this study, leatherback hatchlings were actively tracked with miniature acoustic tags off the...
Article
Full-text available
For sea turtles, like many oviparous species, increasing temperatures during development threaten to increase embryonic mortality, alter offspring quality, and potentially create suboptimal primary sex ratios. Various methods are being implemented to mitigate the effects of climate change on reproductive success, but these methods, such as breeding...
Article
Full-text available
After gastrulation, oviductal hypoxia maintains turtle embryos in an arrested state prior to oviposition. Subsequent exposure to atmospheric oxygen upon oviposition initiates recommencement of embryonic development. Arrest can be artificially extended for several days after oviposition by incubation of the egg under hypoxic conditions, with develop...
Technical Report
Full-text available
A consortium of recreational fishing advocates, fisheries managers, and marine scientists from Monash University, Victorian Recreational Fishing Peak Body (VRFish), Flinders University, and the Victorian Fisheries Authority collaborated to create best-practice capture, handling, and release guidelines for recreational fishing of sharks and rays. Th...
Article
Full-text available
Green turtle ( Chelonia mydas ) embryos are in an arrested state of development when the eggs are laid, but in the presence of oxygen, arrest is broken and development resumes within 12–16 h. However, the precise oxygen level at which embryos break arrest and continue development is not known. To better understand the impact of oxygen concentration...
Presentation
Full-text available
The East Pacific subpopulation of leatherback sea turtles (Dermochelys coriacea) is Critically Endangered as a result of historic unsustainable egg harvest and ongoing fisheries bycatch. Despite extensive and sustained conservation efforts, the most optimistic prediction is that the subpopulation will be functionally extinct by 2080. While populati...
Poster
Full-text available
The Eastern Pacific Leatherback Population (EPLB) is considered critically endangered and current model projections predict functional extinction by 2080. The known key threats are; primarily, fisheries bycatch of adult and sub-adults, and secondarily, reduced hatchling output from nest loss. The Laúd OPO network has developed an action plan to att...
Poster
Full-text available
The East Pacific subpopulation of leatherback sea turtles (Dermochelys coriacea) is Critically Endangered as a result of historic unsustainable egg harvest and ongoing fisheries bycatch. Despite extensive and sustained conservation efforts, the most optimistic prediction is that the subpopulation will be functionally extinct by 2080. While populati...
Technical Report
Full-text available
The green turtle population nesting on Raine Island faces numerous threats including sea level rise and high mortality of nesting females. These threats have resulted in large investments in infrastructure and beach re-profiling on Raine Island. However, the largest threat facing this population is likely to be climate change, because nest temperat...
Technical Report
Full-text available
In July 2020, the Conservation Planning Specialist Group (CPSG) of the International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC) was enlisted by the international non-profit sea turtle conservation organization, Upwell, to design and facilitate a two-step decision making process to inform conservation efforts for the C...
Article
Full-text available
Quantifying early life movements is essential to understanding migratory pathways and habitat use that can impact individuals’ success later in life. To gauge how neonatal movements set the stage for later habitat use, we tracked neonate leatherback turtles (n= 94) with acoustic tags from Pacuare, Costa Rica, in 2016 and 2018. We analyzed movements...
Article
Full-text available
Early-stage turtle embryos, immediately after oviposition, are very small (<5 mm diameter), hindering research on the initial period of embryonic development. For example, assessing whether turtle eggs had been fertilized and contained a viable embryo at oviposition, especially under field conditions, is complicated by the microscopic size of embry...
Article
Full-text available
Sea turtle species in the genus Lepidochelys exhibit an unusual behavioural polymorphism, nesting in both aggregations and solitarily. Aggregated nesting events, termed ‘arribadas’, involve hundreds of thousands of females congregating at a single nesting beach over a few days to oviposit their eggs. Aggregate and solitary nesting behaviours are as...
Thesis
Full-text available
Crocodilian and turtle eggs are laid at an early stage of embryonic development. In turtles, embryonic development arrests at the gastrula stage within the mother’s oviducts. Arrest is maintained by low oxygen availability in the oviduct and is broken upon exposure to normoxia at oviposition. It provides flexibility in the reproductive schedule, wi...
Article
Relocation of turtle eggs for research or conservation purposes is associated with significant risk, because they are prone to movement-induced mortality resulting from damage to embryonic membranes. Hypoxic incubation of eggs after oviposition maintains embryos in pre-ovipositional embryonic arrest and delays development. Whether or not this exten...
Article
Full-text available
Turtle embryos enter a state of arrested development in the oviduct, allowing the mother greater flexibility in her reproductive schedule. Development recommences once eggs transition from the hypoxic oviduct to the normoxic nest. Significant mortality can occur if turtle eggs are moved between 12 h and 20 d after oviposition, and this is linked to...
Article
Full-text available
We determined reference ranges for hematology and serum biochemistry in 39 free-ranging freshwater crocodiles ( Crocodylus johnstoni ). Animals were captured from Windjana Gorge in Western Australia and physically restrained for blood sampling from the supravertebral vein. No significant sex differences were found. Four animals were infected with a...
Article
Full-text available
Phenotypic plasticity of organ size allows some animals to manage fluctuations of resource quality or availability. Here, we examined the phenotypic plasticity of the gastrointestinal tract of king quail (Coturnix chinensis) in a diet-fibre manipulation study. Quail were offered either a control low-fibre (high-quality) food (8.5% neutral-detergent...
Article
Full-text available
Summary Using layer hens, Gallus gallus domesticus, we compared the digestive capabilities of birds on a low-fibre diet (LF, 8.49% neutral detergent fibre; NDF), with those fed a high-fibre diet balanced for energy and protein to match the LF diet (high fibre balanced, HFB; NDF = 15.61%) and those fed a high fibre unbalanced (HFU) diet (NDF = 16.68...

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Projects

Projects (5)
Project
I seek to better understand how incubation temperature affects early embryonic growth in sea turtles. By incubating loggerhead turtle eggs at different temperatures, I aim to establish for the first time that cooler eggs take longer to 'break' from their natural state of arrested development than eggs in warmer nests. This is an important gap in our knowledge of how reptiles may respond to climate change.
Project
We collect acoustic tracking data to assess hatchling dispersal and movements of juvenile turtles (e.g. leatherbacks, green, hawksbill). Our findings help to elucidate the role that ocean circulation plays in dispersal. Project sites include Pacuare, Costa Rica, Machalia, Ecuador, and Bahia Jiquilisco, El Salvador.
Project
Despite full protections at index nesting beaches to eliminate poaching, and ongoing efforts to reduce bycatch, this critically endangered population continues to decline. Upwell enthusiastically supports all interventions advocated by the Eastern Pacific Leatherback Conservation Network (LaudOPO) to promote population recovery by reducing mortality from fisheries bycatch, protecting nesting beaches and increasing hatchling production, and promoting and strengthening implementation of regional actions through existing networks and instruments. We are also examining conservation success stories on recovery of other critically endangered species that have used ex-situ measures to overcome high mortality in early life stages until wild populations stabilize. Upwell is soliciting input from sea turtle conservation experts and conducting a population viability assessment in concert with international experts and collaborators, to assess whether ex-situ measures could potentially augment existing interventions to save East Pacific leatherbacks from extirpation.