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Turtle Sense

Cell phones for Sea Turtles -- creating an extremely low powered remote data recorder and sensor for monitoring wildlife.

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This project was created on 08/05/2014 and last updated 6 days ago.

This very low powered, inexpensive system is designed to monitor the nests of endangered sea turtles. Designed to withstand a harsh ocean beach environment, an ultra low powered motion sensor and microprocessor is encased in a small plastic egg. This "Smart Sensor" - buried in the sand on top of a nest - measures, records and evaluates motion and temperature for several months. The Smart Sensor is attached by cable to a cell phone board which sends regular reports on the activity in the nest. The goal is to predict hatching dates from motion of the embryo in the egg or from motion of the egg as the hatchlings cut through the leathery egg or both. Hatching occurs on some unpredictable date over a six 6 week span. This uncertain time period creates lengthy protection methods which conflict with other uses of the beach area. Turtle Sense hopes to narrow the protection window to just a few days, free up the beaches, and encourage eco-tourism while helping protect the baby turtles.

The sea turtles found in the waters of Cape Hatteras National Seashore are protected by the U.S. Endangered Species Act, an extremely powerful law, that must be followed and administered by the National Park Service (NPS). While the NPS must protect the Seashore’s nesting sea turtles, the NPS also is obligated to uphold it’s mission and make the Seashore available to people for “enjoyment, education, and inspiration.” As the popularity of the Seashore has grown, it has become increasingly difficult for the NPS to meet its obligations to both people and sea turtles. The goal of Turtle Sense is to help people and sea turtles share the beaches of the Seashore in a way that benefits both humans and sea turtles.

Today, when a sea turtle nest is found on a Seashore beach, a small enclosure is built around the nest to keep pedestrians and vehicles away. About 50 to 55 days later the nest closure is expanded, often closing the beach to vehicular traffic. Because there is no reliable way to predict when tiny turtles will emerge from their nests near the duneline and parade to the surf, closures can sometimes last for more than a month. 

Turtle Sense system design

The Smart Sensor (the right half of the diagram above) uses an accelerometer to record changes in acceleration up to 400 times per second.  The readings are analyzed by the microprocessor to produce a profile summary of the forces acting on the sensor.  A new profile is created every 15 seconds to six minutes. Because it is not possible to transmit data from underneath wet salty sand, a set of summaries are uploaded to a separate Communications Unit (the left half of the diagram) at least once a day and as often as every hour.  The Comm Unit and the Smart Sensor are connect by Cat5e Shielded cable, which is typically about 20 feet (6 meters) long, but can be much, much longer if needed.  The Comm unit is controlled by another microprocessor which controls the communication with the Smart Sensor and also controls a plug-in cellular communications board.  Cellular communication uses the bulk of the power needed by the system, so its power supply is powered down when communication is not needed.  It is typically only powered up for a few minutes each day.  The entire device is powered by a battery pack of 8 rechargeable AA NiMH cells.  This is enough power to run the system for many, many months.

In order to keep track of multiple nesting sites, we also created a hand-held communications device that is used to test the sensors, check for good cell phone reception, and register the date and GPS location of the nesting sites.  Since this device is small and portable, it can be carried along with Smart Sensors on the daily beach patrols of park personnel.  When nests are found, they are excavated and the eggs are counted.  At that time, a Smart Sensor is placed on top of the nest, and it is connected to the hand-held device to register the nest.  Testing and registering the sensor just takes a few minutes.  Then the cable is buried, with its 9-pin Molex connector sealed in a plastic pill bottle.  The location of the end of the cable is marked with a stake.

After a few days or weeks, a larger comm unit is brought to the nest site and connected to the sensor.  This Comm unit is housed in sealed PVC pipe in a foundation of concrete. The comm unit enters a sleep mode if no sensor is plugged in. It powers up fully when a Smart Sensor is connected, and starts sending reports.

Detailed reports are regularly uploaded to a server on the Internet.  These text file reports are readable by humans and machines.  Eventually, there will be a web based interface for controlling the parameters of the system and viewing data.  If we are successful, an automated system will accurately predict hatching events and send alerts of pending hatching to wildlife managers, researchers and the general public.  To...

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  • 2 × ***COMPLETE BOMs ARE IN THE LIST OF LINKS*** The links are labeled "Custom Smart Sensor BOM" and "Custom Communicator BOM".
  • 1 × Smart sensor custom circuit board (1" X1") Components include TI MSP430FR5739 processor, ADXL 362 motion sensor and ADM 3491 transceiver. See "Custom Smart Sensor BOM" link in left column.
  • 1 × Communications custom circuit board (3.2" X 1.5") components include TI MSP430FR5739 processor, headers for cell phone board, power supplies, analog switches, and ADM 3491 transceiver. See "Custom Communicator BOM" link in left column.
  • 1 × Janus plug-in M2M cell phone boards 5 interchangeable boards that are certified to work with different telecoms around the world -- NOTE! This 3rd party board is not open source.
  • 1 × Cell phone antenna Penta band with right angle SMA connector
  • 1 × Sheilded underground cat 5 cable Connects buried sensor to communications unit -- RF transmission through wet salty sand is not possible. Cable can be several hundred feet long if needed.
  • 2 × 9 pin Molex connectors with gold contacts Male and Female Connects the cable from the egg to the communications units. The communications units can be connected several weeks after the sensor egg is placed in a nest
  • 1 × Epoxy coating for smart sensor board after fabrication Coated to make it water proof - see assembly instructions. Tap Plastics "Easy Cast" two part epoxy resin
  • 1 × Flexible silicon turtle egg mould Made from casting a ping-pong ball - see assembly instructions. Tap Plastics "Platinum" silicone two part mold making material
  • 1 × Polyurethane quick cast liquid (about 40cc) For creating the cast "egg" sensors and securing the molex connectors to the cables - see assembly instructions. Tap Plastics "Quik-Cast" two part polyurethane casting resin

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Project logs
  • User interface

    7 days ago • 0 comments

    We want to make Turtle Sense as simple to use as possible.  So at the most basic level, setting it up, you just plug the connector coming from the turtle egg Smart Sensor into the connector attached to the communications tower.  The device, which has been asleep, wakes up and starts collecting data and sending out reports.  When you unplug the devices they go back to sleep until the next time.

    But that is just the surface of how we plan to have users interact with the device.   We made these units for use by the National Park Service, but they are just the representatives for a much bigger group of users: Wildlife managers, researchers, eco-tourists, fisherman, and the general public.

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  • Future options

    7 days ago • 0 comments

    The 2015 Turtle season will be over in a couple of months.  We will have collected data from more than a dozen nests, and have been fairly successful in accomplishing what we set out to do this season.  But we still have a long way to go.  We need to automate the process of predicting nests and create a fully functional web-site for managing the process that also lets the public and researchers see the results.  At the same time we have to perfect our design so that it is as close to 100% reliable as we can make it.  Here's our thinking about the next phase of the project.

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  • Hatching or Ghost Crabs?

    11 days ago • 0 comments

    We've completed the monitoring of 5 nests so far. One sensor failed in a nest (bad connections). 8 nests are being monitored currently, and another 4 are awaiting a spare communications unit to free up. So we should have data from about 17 nests to evaluate. Using our theory about hatching, which we are now calling the "popcorn" theory, we were able to predict several boils.  The popcorn theory is that the turtle eggs are like popping corn in boiling oil.  When they heat up they start to jiggle a little and then they all start to pop at once.  When you hear the popping quiet down you know it is ready to pour everything out of the pot.  So we theorize that the turtles are all programmed to listen for things to quiet down after hatching, and that way they know that it is time to leave the nest.

    Popping (hatching) shows up in our data a few days (3-5) before the turtles pour (boil) out of the nest.  The sensors are sending 240 records in each report, and each report is phoned in every 4 hours.  So each record is a profile of what happened each minute of the day.  We can see how many readings there were in about 25 ranges of acceleration from .001 G to about 4 G.  We've arranged these ranges logarithmically because we did not know  what values we'd be getting.  We thought there would be a huge dynamic range between background noise that and the motion of hatching turtles hitting the sensors.  It turns out the dynamic range is not that large -- about 4:1 .  In future versions we can design our data collection to get more resolution in the ranges that we are recording.

    To graph the data, we integrate all the readings during each minute's report to get a single numerical value.  This value corresponds roughly to the energy from the motions recorded.  We can graph the data versus time to see what is happening.  It looks like this:

    Looking at the graph,  you can see that things are really popping starting around day 68.   Then everything gets real quiet for a few hours on day 72.  That was just before the boil.  So when we see the graph look like an earthquake on a seismograph we figure things are going to boil in about 4 days.  This is a pretty good method of making a prediction.

    Except for one thing.  Do you see the spike around day 60 and again on day 65?  We think these spikes are from ghost crabs.  Ghost crabs are a main predator of sea turtle eggs.  They make quite a commotion in the nest when they are feeding on sea turtle eggs.  Some nests don't have them, so there are no spikes until the eggs are hatching.  But some nests have lots of them.  If the crabs find the nest early on, they return over and over.  They probably bring their family and friends and feast on eggs.

    So now we have to collect more data, and hopefully learn how to distinguish between the hatching of sea turtles and an orgy of crabs feasting on sea turtles.  One member of our team, Tom Zimmerman, is working on using machine learning techniques to do just that.

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Samuel Wantman wrote 2 months ago null point

We are measuring the temperature in the nest. In our situation, we only have official permission to install a single sensor in the nest. Our hope is to use the temperature data with the motion readings to refine our estimations on the total incubation period. It seems that the effect of global warming on the sex of sea turtles is a hot button topic. As soon as our design stabilizes, we will be making units available at cost for researchers around the world. We will also be looking for people to help test our units on GSM networks outside of the US, as we hope to make the device compatible with cell phone networks all over the world. We will also be encouraging researchers to expand on our software so that it is applicable for other uses with sea turtles and with many other egg-laying species.

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jlbrian7 wrote a month ago null point

I don't think her work dealt with global warming. Apparently it is not known with certainty what temperature ranges produce males and what produce females. I think it is hard to know what impact climate change has when you don't have a reliable baseline.

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jlbrian7 wrote 2 months ago 1 point

My wife was awarded a Fulbright to study the arribada in Costa Rica. She wanted me to see if I could build a data logger that would capture the temp at different depths of the nest, and once they hatched they would sex the turtles. Ultimately I could not do it cost effectively, but I could nearly compete with the consumer products because they can be pricey for what they wanted to accomplish. If you are interested I can see if she can suggest some white papers.

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