Profile
I am a marine ecologist interested in developing our understanding of current and future animal movements within marine and coastal habitats. I apply that knowledge to the development of appropriate conservation policies for long term protection of species and their habitats. I have been also studying sea turtles in the British Indian Ocean Territory since 2012, working closely with Prof. Graeme Hays from Deakin University and Dr Jeanne Mortimer who is based in the Seychelles.
During 2012-2018, we satellite tracked 35 post-nesting green turtles (Chelonia mydas) using Fastloc-GPS telemetry and recorded a huge range in migrations, from 75 km within the BIOT MPA to >4000 km to distant foraging grounds on the East coast of Africa. Our current work in the Western Indian Ocean, includes use of satellite telemetry to increase our understanding of key nesting and foraging grounds for both green turtles and the critically endangered hawksbill turtle (Eretmochelys imbricata). We are also conducting long-term monitoring of sea turtle nesting and foraging populations in BIOT. This includes long-term records of sand temperature to assess likely sea turtle hatchling sex ratios and hatching success.
Our satellite tracking research in the British Indian Ocean Territory has led to discoveries of extensive seagrass meadows on the Great Chagos Bank at unexpected depths of 25-30 meters, providing critical habitats for juvenile fish populations and foraging green turtles.
Biography
My Project
Other interests
Currently investigating the impacts of plastics on sea turtles and hoping to use results to influence use of plastic in BIOT. Darwin Initiative funded project (2019-2022): Reducing the impacts of plastic on the BIOT natural environment.
My Publications
Fidelity to foraging sites after long migrations
Shimada, T., Limpus, C. J., Hamann, M., Bell, I., Esteban, N., Groom, R. and Hays, G. C. (2020). Fidelity to foraging sites after long migrations. Journal of Animal Ecology
Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago
Mortimer, J.A., Esteban, N., Guzman, A.N and Hays, G.C. (2020) Estimates of marine turtle nesting populations in the south-west Indian Ocean indicate the importance of the Chagos Archipelago. Oryx.
Green turtle diet is dominated by seagrass in the Western Indian Ocean except amongst gravid females
Stokes, H. J., Mortimer, J. A., Hays, G. C., Unsworth, R. K., Laloë, J. O., & Esteban, N. (2019). Green turtle diet is dominated by seagrass in the Western Indian Ocean except amongst gravid females. Marine Biology, 166(10), 135.
Use of long-distance migration patterns of an endangered species to inform conservation planning for the world’s largest marine protected area
Hays, G. C., Mortimer, J. A., Ierodiaconou, D., & Esteban, N. (2014). Use of long‐distance migration patterns of an endangered species to inform conservation planning for the world’s largest marine protected area. Conservation Biology, 28(6), 1636-1644.
Fastloc-GPS reveals daytime departure and arrival during long-distance migration and the use of different resting strategies in sea turtles.
Dujon, A. M., Schofield, G., Lester, R. E., Esteban, N., & Hays, G. C. (2017). Fastloc-GPS reveals daytime departure and arrival during long-distance migration and the use of different resting strategies in sea turtles. Marine biology, 164(9), 187.
Diel and seasonal patterns in activity and home range size of green turtles on their foraging grounds revealed by extended Fastloc-GPS tracking
Christiansen, F., Esteban, N., Mortimer, J. A., Dujon, A. M., & Hays, G. C. (2017). Diel and seasonal patterns in activity and home range size of green turtles on their foraging grounds revealed by extended Fastloc-GPS tracking. Marine biology, 164(1), 10.
Drones for research on sea turtles and other marine vertebrates – A review
Schofield, G., Esteban, N., Katselidis, K. A., & Hays, G. C. (2019). Drones for research on sea turtles and other marine vertebrates–A review. Biological Conservation, 238, 108214.
Male Hatchling Production in Sea Turtles from One of the World’s Largest Marine Protected Areas, the Chagos Archipelago
Esteban, N., Laloë, J. O., Mortimer, J. A., Guzman, A. N., & Hays, G. C. (2016). Male hatchling production in sea turtles from one of the world’s largest marine protected areas, the Chagos Archipelago. Scientific reports, 6, 20339.
New Tools to Identify the Location of Seagrass Meadows: Marine Grazers as Habitat Indicators
Hays, G. C., Alcoverro, T., Christianen, M. J., Duarte, C. M., Hamann, M., Macreadie, P. I., … & York, P. H. (2018). New tools to identify the location of seagrass meadows: marine grazers as habitat indicators. Frontiers in Marine Science, 5, 9.
The Discovery of Deep-Water Seagrass Meadows in a Pristine Indian Ocean Wilderness Revealed by Tracking Green Turtles
Esteban, N., Unsworth, R. K. F., Gourlay, J. B. Q., & Hays, G. C. (2018). The discovery of deep-water seagrass meadows in a pristine Indian Ocean wilderness revealed by tracking green turtles. Marine pollution bulletin, 134, 99-105.
Implications of Location Accuracy and Data Volume for Home Range Estimation and Fine-Scale Movement Analysis: Comparing Argos and Fastloc-GPS Tracking Data
Thomson, J. A., Börger, L. & Christianen, M. J. A., Esteban, N. J., Laloë, J. O., Hays, G. C. (2017). Implications of location accuracy and data volume for home range estimation and fine-scale movement analysis: comparing Argos and Fastloc-GPS tracking data. Marine Biology. 164(10):204.
How Numbers of Nesting Sea Turtles can be Overestimated by Nearly a Factor of Two
Esteban, N., Mortimer, J. A., & Hays, G. C. (2017). How numbers of nesting sea turtles can be overestimated by nearly a factor of two. Proceedings of the Royal Society B: Biological Sciences, 284(1849), 20162581.