by: Jake Velasquez
Exactly two months after we started our fundraiser for Hawaii Wildlife Fund, we've hit our first massive milestone: With over $400 raised, we can finally purchase the very first TurtleSense Nest Sensor! To stay updated on our progress, check out the donation thermometer in our announcement post - It's updated daily! Over the past few weeks, we've had quite a few questions regarding exactly what the nest sensors are, what they look like, and why they're important. Now is the time to find out!
Why sensing turtles is important
When they find out about our donations to Hawaii Wildlife Fund, the question most people ask first is, "Why?"
According to NerdsWithoutBorders, the team behind the design and construction of the TurtleSense Nest Sensor, sea turtle populations have declined by as much as 95% in the past century due to human activity. Humans have polluted the ocean, destroyed habitats on land, and inadvertently captured sea turtles in trawling nets. Hawaii Wildlife Fund is working to rebuild sea turtle populations, and the most effective way of doing this is by protecting the extremely vulnerable hatchlings as they emerge from their sandy nests and crawl toward the breaking waves.
In order to do their job, volunteer groups and other personnel need to be present when the hatchlings emerge from the sand. The problem is that they do not know when this will happen: The sea turtles can hatch any time in a six week window, starting 50 days after the eggs are laid. When it occurs, all 100-150 hatchlings suddenly boil out of the sand in one mass and dash into the surf.
With today's technology (that is to say, volunteers with flashlights), the National Park Service is forced to rope off any nest sites discovered on the beach, and closely monitor them starting 50 days after the eggs are buried. Each nest site is guarded until the hatchlings emerge, or until 100 days have elapsed and the site is considered non-viable. Sectioning off a part of the beach for such a long stretch of time creates multiple problems, including conflicts with people ignorant of the issue who try to fight for "space" purely for recreational use, as well as issues relating to vehicular movement. Rarely mentioned is the scale of things: Sometimes there just are not enough people to monitor all of the sites.
Helping baby sea turtles, WITH SCIENCE!
The goal of TurtleSense is to build a device that removes the need of people patrolling nests and standing guard. This is done by building a sensor with the means to detect movement down in the nest, meaning the hatchlings are preparing to boil out, and a way for it to signal to the outside world so that personnel can come and assist the turtles as they eventually emerge.
The TurtleSense circuit board - This is cast in a ping pong ball mold and placed in the nest.
All of the sensor designs and software code will be published online and available for use worldwide. The circuit board contains a microprocessor, an accelerometer capable of measuring movement in 3 axes (as well as gravity), and a transceiver chip. With this sensor, it's possible to change the timeframe spent monitoring turtles from 50 days to just a few days, saving potentially hundreds of labor hours.
The sensors themselves are the result of multiple revisions and strenuous testing. The current sensor is part of the team's Phase Two, and the result is a cutting-edge device capable of measuring multiple jolts per second, then sending out text messages alerting team members that a nest is getting ready to boil.
What's in a turtle sensor
The entire TurtleSense project actually consists of two distinct pieces: The sensor assembly itself that lives in the nest, and the Communication Tower, which houses the battery pack, cell phone board, GPS antenna, and other hardware used to drive the sensor.
The sensor assembly, cast in the white ball, senses jolt events from the surrounding hatchlings
The Comm Tower is built into a 3" PVC pipe and contains all the necessary hardware to power the sensor and communicate with the outside world
The sensor measures jolt results at a blinding speed, registering up to 400 events per second. From there, the data is sent to the sensor's processor, where the data is analyzed and used to build a profile. A new profile is built every 15 seconds to 6 minutes. Since it's not possible to beam data under wet, salty sand, the Comm Unit is built into a tall tube that projects up from the sand. The data received by the Unit is uploaded at least once per day, and as quickly as every hour. For power, the entire assembly is run off 8 rechargeable AA batteries, which is sufficient to run the unit for months. Since cellular communication uses the most power, the cellular module is only powered up for a few minutes each day.
To track multiple sites, the team also built in GPS functionality and a hand-held receiver to test and register the sensors in the field. The receiver can verify the sensor is functional, check for proper cell phone reception, set time and date, and register the location of the sensor units via GPS. Due to its small size, the receivers can be carried by park personnel and used on daily beach walks.
The hand-held receiver is the best way to test the sensors before final installation, as well as log their location via GPS
When a new nest is found, it's excavated and the eggs are counted. Then, the sensor is placed among the eggs, the receiver is attached and the location of the nest is registered, and the nest is carefully buried. The location of the sensor's cable end is marked with a stake. Later, the large Comm Unit, now sealed in a large PVC pipe and planted in a block of concrete for stability, is dug into the sand nearby and attached to the sensor. At this point, it's considered fully operational.
Great! It sounds like everything is good, so why do they need help?
Sensing turtles far in the future
The entire project is sponsored, and they rely on donations to fund everything. They are also deep in the initial testing phase. In the recent past, they've had the opportunity to do their first major hardware revision, which led to the Phase Two test cycle. That cycle was successful, and they're now preparing for Phase Three.
As NerdsWithoutBorders reports, success with TurtleSense could have widespread effect, "More effective international protection will be available, since the protection resources can be concentrated close to the hatch date instead of being stretched over six weeks. With a tighter hatching schedule, the public would have the opportunity to observe the hatchlings heading for the sea, an observation available only randomly now. This would improve the public support of the turtles. Much of the research on sea turtle eggs and hatchlings in the world could benefit from more accurate predictions of the hatch date. For example, studies that require capturing hatchlings for research could be done with much greater efficiency. Also, the sensor/cell network could be adapted for measurements of other species, including birds. Given its modest cost and energy efficiency (long battery life), it may have other uses in environmental studies."
All photos credit NerdsWithoutBorders