HOBO Data Loggers Aid Sea Turtle Preservation in Malaysia

Outdoor, Water
On Tioman Island, the Juara Turtle Project uses HOBO data loggers to link egg incubation temperature with size and fitness of sea turtle hatchlings.

Home to one of the planet’s most pristine coral reefs and a flourishing ecosystem, Malaysia’s Tioman Island is also home to the Juara Turtle Project (JTP), a non-governmental organization that’s been focused on sea turtle conservation for more than a decade. Working extensively with the community to inform, educate, and develop sustainable practices to counteract threats to the environment, the JTP relies on hundreds of volunteers from far and wide to increase its conservation efforts. 

Only seven species of sea turtles exist in the world, four of which were once found in Malaysia – Leatherback, Green, Hawksbill, and Oliver Ridley sea turtles. It’s been 15 to 20 years since Leatherback and Oliver Ridley turtles have been found to nest on Tioman Island, however, so now only two species – the Hawksbill and Green – remain, with Green turtles being the most common, on Tioman Island and worldwide. Today, all sea turtles found in Malaysia’s waters are listed as endangered or critically endangered by the International Union for the Conservation of Nature (IUCN).

While natural threats to the sea turtle population are undeniable, those that are driving sea turtles toward extinction are all caused by humans. These  threats include egg harvesting for consumption, accidental capture by the commercial fishing industry, entanglement in debris such as discarded plastic netting materials, the ingestion of plastics and microplastics, loss of habitat due to increased tourism and development in coastal areas, harmful algal blooms, marine pollution that affects food sources, and light pollution, which can disorient sea turtle hatchlings on their way to reach the ocean, causing them to wander the beach where they often die of dehydration or predation.      

With its mission to protect what’s left of the nesting sea turtle population on Tioman Island and raise awareness of the devastating global issues that affect these beautiful and highly-endangered species, the JTP works tirelessly to assess and preserve the island’s sea turtle nesting areas and boost the turtle egg survival rate. Ongoing efforts include: beach monitoring, which involves one or more volunteers/staff members conducting morning and night beach patrols, either on foot or by boat, to check for turtle activities and collect data on the nesting turtle population; hatchery management, involving the careful transference of eggs from a turtle nest to a reproduction of the original nest located in the safe environs of a hatchery; hatchling release to the ocean after a two-month incubation period; and excavation of nests to determine success rates and to evaluate why some eggs failed to hatch.    

More recently, the JTP began deploying Onset HOBO Pendant data loggers at various beach and hatchery nest locations to record changes in temperature during incubation periods and better understand how nest temperature influences newborn turtles’ survival. At each monitoring location, one HOBO Pendant data logger is buried in the middle of an egg clutch (about 70 cm deep), one is buried near the top of the nest (about 10 cm deep), and two are deployed next to the nest, to compare temperature fluctuations with and without eggs.

The loggers record temperature every hour for two months. Then the temperature data are downloaded from the loggers and analyzed with respect to hatchling shell size (length and width) and fitness (the time they spend to turn around when placed upside down). Data collected from these rugged, waterproof HOBO loggers also provides important information about hatchlings sex ratio, as increased incubation temperature can result in a sex ratio imbalance that reduces reproduction opportunities and decreases the genetic diversity of the species. Monitoring results have shown lower temperatures and greater temperature fluctuations closer to the surface of the sand, and high temperatures deeper inside the nest, providing information about the metabolic heat of the turtle eggs.  

Using all of its resources, including low-tech methods like beach patrols and high-tech methods like temperature data logging, and with the help of about 400 volunteers a year, the Juara Turtle Project plans to continue to protect and promote the sea turtle population on Tioman Island, and, ultimately, throughout the world. If you’re interested in helping, you only have to commit to a four-night stay, and no previous experience with sea turtles is required. Check out the JTP website’s volunteer page for more information.

And check out Onset’s website to learn about Bluetooth-enabled HOBO Pendant and TidbiT loggers