Did you know that turtles belong to one of the oldest reptile groups in the world? They beat snakes crocodiles and alligators.
Out of the 7 different species of marine turtle in the world, 6 can be found in Australian waters.
Did you know that turtles belong to one of the oldest reptile groups in the world? They beat snakes crocodiles and alligators.
Out of the 7 different species of marine turtle in the world, 6 can be found in Australian waters.
PROJECT: Using stable isotope analysis to determine foraging groups and the influence of foraging group on reproductive output of loggerhead turtles
RESEARCHERS: David Booth & Collin Limpus
LOCATION: Mon Repos, Queensland
Loggerhead turtles (Caretta caretta) are an endangered species found around Australia and can be identified by their five pairs of plates on their carapace (shell). Although we know the extent of their foraging regions along the Australian coast line, we do not have a good estimate of the relative importance of different foraging groups to the nesting East Coast population.
The most important rookery (nesting site) for loggerhead turtles on the East Coast of Australia is Mon Repos in Queensland, where over 300 loggerhead turtles nest annually.
This project aims to:
1. Identify different feeding groups of female loggerhead turtles nesting at Mon Repo using stable isotope data extracted from skin and blood samples
2. Use the feeding group information to identify if females with distinctly different diets/feeding locations have different size and reproductive output
a. Based on measurements of female carapace size, clutch size (number of eggs in a nest) and the number of hatchlings successfully emerging from a nest
b. Flipper tags will be used to identify individual turtles and the date and precise position of nest laying recorded from previous years.
This information can then be used to inform future management plans of the Australian East Coast nesting population of loggerhead turtles. For example if limited resources are available for conservation strategies, priority should be directed towards regions of relative high density of foraging turtles that have the greatest reproductive output.
DEFINITION:
Foraging: searching for food
Stable Isotope: Stable isotope analysis (SIA) quantifies the stable isotope ratio of elements (typically carbon and nitrogen) that are incorporated into animal tissues, the ratios of which are similar to that of the dietary items consumed (Tieszen et al. 1983 ). Using SIA, information on diet can be inferred by taking small tissue biopsies from sea turtle females when they come ashore to nest. Because different tissue types have different turnover rates, they can be used to infer diet at different times in the past. Skin and blood tissues are most frequently sampled because these can be obtained quickly and with minimal evasion to the animal. Blood plasma has a rapid turnover rate with dietary information reflective of days or weeks, whilst red blood cells reflect diet 2-6 months previously (Hobson & Clark 1993; Hobson 1999) and epidermis diet 6-12 months or more previously (Vander Zan den et al. 2014 ).
REFERENCES
Hobson K.A. & Clark R.G. (1993). Turnover of 13 C in Cellular and Plasma Fractions of Blood: Implications for Nondestructive Sampling in Avian Dietary Studies. The Auk, 110, 638-641.
Tieszen L.L., Boutton T.W., Tesdahl K.G. & Slade N.A. (1983). Fractionation and turnover of stable carbon isotopes in animal tissues: Implications for δ13C analysis of diet. Oecologia, 57, 32-37.
Vander Zanden H., Pfaller J., Reich K., Pajuelo M., Bolten A., Williams K., Frick M., Shamblin B., Nairn C. & Bjorndal K. (2014). Foraging areas differentially affect reproductive output and interpretation of trends in abundance of loggerhead turtles. Mar Biol, 161, 585-598.
PROJECT TITLE: Development of novel screening tools to assess chemically-induced toxicity in sea turtles
RESEARCHERS: Caroline Gaus, Beate Escher and Ling Jin
LOCATION: Laboratory study at University of Queensland
OVERVIEW
Sea turtles, particularly those living in nearshore habitats, are encountering various environmental threats from natural and human influences. Among these, a multitude of chemical pollutants have the potential to impact turtles’ health in a way that, for instance, suppresses their immune function and thus makes them less capable of coping with environmental stressors.
Previous research mainly focused on the adverse effect of a few priority chemical groups out of a broad spectrum of chemicals that turtles can be exposed to. In such sense, we are still far away from fully understanding the population health implications of pollutants, without addressing the combined effect of total pollutant burdens in turtles.
To overcome current limitations associated with chemical extraction (time and cost), the team introduced a simple technique based on a plastic disk made of polydimethylsiloxane (PDMS). Here they immersed coin-sized disks in turtle fat and blood (where many pollutants usually end up in the animal body), leave them in contact and then collect the disk. A portion of the pollutant mixtures present in the turtle fat and blood has then transferred to the disk. The whole process is termed passive sampling. Just as the name suggests a lot of active labour is saved compared to traditional extraction strategies by just passively waiting for the entire range of pollutants to move across.
The next step is to develop the screening tools to evaluate the toxic potential of the pollutant mixtures. Equally exciting, these tools can also be applied to other wildlife species beyond turtles - dugongs, dolphins, whales etc. This research team are now working towards the day when we may send PDMS disks to our dedicated colleagues around the world, who expose the disk to wildlife they are working with, and send it back to test the mixture toxicity.
PROJECT TITLE: Does incubation temperature determine swimming ability of green turtle hatchlings from natural nests?
RESEARCHERS: Dr. David Booth
LOCATION: Heron Island rookery in the southern Great Barrier Reef
OVERVIEW
Listen to Dr Booth’s keynote presentation from the Inaugural Sea World Research & Rescue Foundation Dinner:
This project aimed to demonstrate that the temperature of green turtle (Chelonia mydas) nests influences the quality of hatchlings in terms of locomotor (swimming and crawling) performance.
The highest mortality in sea turtle hatchlings occurs during the period between then they escape the nest and reach off-shore waters and this mortality is directly related to their locomotor performance. Because sea turtle populations around the world are endangered or threatened, active management of sea turtle rookeries (breeding locations) is becoming increasingly common.
The information gained from this project could be used by rookery managers to identify nests that are outside the ideal temperature environments, and these nests moved to better locations in order to increase the number of sea turtle hatchlings reaching the open ocean.
During his study Dr Booth discovered:
The effect of incubation temperature on the morphology and swimming performance of the green sea turtle hatchling.
Behaviour and physiological mechanisms of dispersal in flatback hatchlings.
Surface time/diving behaviour between nesting events in flatback sea turtles near Darwin and Gladstone: implications for conservation and management.
Natural nest temp variation and effect of incubation temp on embryonic development and hatchling quality of green sea turtle eggs
Migration of breeding male loggerhead turtles.
Disease monitoring in marine turtles in South East Queensland waters
A telemetric study of loggerhead turtle migration in southern Queensland.
A telemetric study of loggerhead turtle migration in southern Queensland.
Hatchling productivity in loggerhead turtles in eastern Australia
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