Why so little news from our traveling turtles? Here's a behind-the- scenes peek at the real life challenges scientists face while conducting research.
As you know, the use of satellite telemetry with sea turtles is new method of research and is highly experimental. Dr. Standora and his colleagues are receiving regular signals from the turtles' transmitters but the readings are of poor quality. Only rarely can the turtles' latitude and longitude be determined. We've listed the few good readings he's received in the past 2 weeks below.
This is a common problem scientists have encountered when using telemetry with sea turtles. At the recent sea turtle conference in South Carolina scientists discussed this and have come to a fascinating, though inconclusive explanation. Here are the clues: The transmitter is towed behind the turtle on a 6 foot tether. (If you look closely at the leatherback photo on the Journey North map you can see the tow line.) The readings indicate that the transmitter is partly submerged and that the antenna may be broken. The satellite can only read signals clearly when the turtle comes up to breathe and the transmitter bobs on the surface. How did the antennae break out in the open ocean? The scientist think SHARKS may be responsible! Sharks might be attracted to the transmitter's electric field and attack it. While this is a frustrating situation for all of us, it could be worse. How would you like to be the turtle with a disoriented shark nipping at you? (Don't worry they don't eat leatherbacks.)
Here are the latest readings:
Turtle #1111 Latitude Longitude February 25 0.366 N 93.483 W February 26 0.242 N 94.180 W
Turtle #1112 Latitude Longitude February 26 7.124 N 84.500 W March 2 5.491 N 86.009 W
Dr. Standora thinks #1112 nested once again before returning heading out to sea. If you compare the routes of each turtle what do you notice?
Ask the Expert Dr. Standora has finally come up for air after reading all your great questions. We sent him ten pages in all! Here is his first round of answers. He couldn't resist asking YOU a few questions. Please respond to: jnorth@informns.k12.mn.us
From Dr. Standora:
"Wow! What a lot of great questions."
"I'll try to answer a few at a time. First some information on the satellite system. The satellite which receives the signal from the turtle is in a polar orbit. Each revolution takes 101 minutes."
CHALLENGE QUESTIONS
1) Where would be the best place to locate a transmitter to be sure of getting the greatest number of signals? (What two points will the satellite pass over every revolution?)
2) Where on the planet would you be most likely to miss a signal?
"We can only afford to track two turtles at a time because the transmitters are very expensive. The ones we use cost $4,200 each. We also have to pay $11 each day the satellite receives a signal. That's a lot of money but it is still cheaper than renting a ship and crew to track an animal. With a satellite system we can track more than one animal at a time. With conventional biotelemetry techniques we would have to have one ship for each animal because the turtles don't travel together. World wide there are approximately 2,000 transmitters operating."
"To save on battery power we only have the transmitters turned on one- third of the time (eight hours per day). Also, the radio waves don't travel well through salt water so the system doesn't attempt to transmit when submerged. What this means to us is that three things must happen simultaneously for us to get a signal. First, the turtle must be at the surface, second, the time of day must be during the transmitter on time, and third, the satellite must be in the proper part of its orbit. Now you can understand why we haven't been getting a lot of signals. As described above, those that we do get are of poor quality."
Answers to Dr. Standora's Last CHALLENGE QUESTION:
Dr. Standora asked, "On February 20th turtle #1111 entered a part of the world that was visited by a famous 19th Century naturalist. Who was the famous scientist and what theory is he known for?"
From MASSACHUSETTS: Hi Dr.Standora, Charles Darwin gathered data for "Origin of Species", etc. He is known for his theory of Evolution. From investigators at pbrown@idea.uml.edu Patrick-Consentino School
From NEBRASKA: Hello from the 4th grade class in Henderson Nebraska. We are extremely excited to participate in Journey North. We believe the answer to the challenge question is: Charles Darwin is the famous 19th century naturalist and his theory is evolution. However, we are not allowed to study many of Darwin's theories. We did notice that there is an island known as Isla Darwin around the Galapagos. Rod Diercks rdiercks@esu6.esu6.k12.ne.us
From NEW YORK: This is Cameron Khani's answer to Mr.Standora's challenge question. Darwin showed that living things commonly produce many more offspring than are necessary to replace themselves. The earth can not possibly support all these organisms, and so they must compete for much necessities as food and shelter. Their lives also are threatened by animals that prey on them, by unfavorable weather, and by other environmental conditions. This was Charles Darwin's theory "Survival Of The Fittest". Cameron Khani, Mrs. Berger's Class K12ROBZJ@vaxd.hofstra.edu
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