Ocean Currents.
Story
by Florence Verspecht
This story begins far, far away in the middle of the North Pacific Ocean, somewhere between Japan and Hawaii. It is January the 10th, 1992, and Baby Turtle is floating here some days after she was born. A storm has begun, wild winds and raging seas, with waves so high it looks like there are hills and mountains of water around her. But Baby Turtle is not afraid because she is safe in the water and the big waves just make the day more fun!
Through the howling winds and noise of the breaking waves Baby Turtle hears an unfamiliar sound, a low heavy droning noise that seems like it comes from everywhere at once. Under the water it is difficult to know which direction a sound is coming from. Suddenly Baby Turtle sees an enormous monster appearing above the waves!! But this is not a monster, this is a big ship, filled with many metal containers, each of them 13 meters long. And the containers are filled with many different things that are sold from Hong Kong in China and taken 10,500 kilometres across the seas destined for Tacoma, Washington, in the United States of America.
Suddenly a big wave hits the 'bow' of the ship, which is the front end, and the containers on it start to rock and roll around. Baby Turtle watches in awe as she sees some of the containers start to slip and tumble from the ship. She sees 1, then 2, then another 2, then 4 more, then another 3 containers fall from the ship into the dark churning waters below. Twelve containers!! But what is this? One of the containers has been knocked so badly against the others, and against the ship that it has opened up. Now there are hundreds, no, thousands! of colourful things spilling out into the water. A sea of colour surrounds Baby Turtle. Red ones, blue ones, yellow ones and green ones. And they are all floating happily along, just like Baby Turtle is. The colourful floating things are made of plastic, and they are toys, bath toys, that is why they float. The red ones are shaped like beavers, the green ones look like frogs, the yellow ones are toy ducks and the blue ones are shaped just like Baby Turtle herself, in the shape of a turtle!
This is amazing, there are 28,800 bright, shiny, new plastic toys floating around, all still attached to their cardboard packaging. This packaging will soon be gone as it gets wet and the sea water starts to degrade it. With time the sun will bleach the little toys and they will lose their colours. The red and yellow ones will become white, and the green and blue ones will look faded and weathered. As the ship steams further and further away from Baby Turtle, onwards to its destination in America, the sound of the engines become more and more dim. Baby Turtle looks around her and she has never seen so much colour at once in her short life! The storm is beginning to die out now, but there are still very big 'swell' waves, which are waves created by the storm, and these waves will travel many kilometres until they come to a shore where they can break. The waves and wind and rough waters are causing the toys to spread out and they become a bigger and bigger splash of colour in the blue ocean.
Baby Turtle and the colourful toys are being swept along eastwards, in the same direction as the ship, towards the west coast of America. The reason that Baby Turtle is moving along so quickly with the bath toys is because she is caught in a current. A current is a movement of water, a bit like a river running within the ocean. And the river of water can be hotter or colder than the surrounding water. The current that Baby Turtle is in is a lovely warm surface current and is about 24 degrees Celcius. Because warm water is lighter than cold water it floats over the top of the colder water. The name of this current is the 'Kuroshio' current, which is a Japanese word for 'Black Tide'. It is a strong current, moving about 2 meters per second, and Baby Turtle is being pulled along faster and faster now that she is right in the middle of it. The current is 100 kilometres wide and comes all the way from the coast of Japan, and flows all the way into the North Pacific towards the icy cold waters of the Arctic.
The toys are still bobbing along with her and Baby Turtle soon discovers that they are not alone in the current. There are many fish in this current too! The fish in the Kuroshio current make it very important for the countries that it passes along the way. This is because humans go out in fishing boats and catch the fish using nets or long fishing lines and they earn money from selling the fish. Right now Baby Turtle is curious to see so many fish in the current. Wow, there is a school of sardines, and a school of anchovy! Look at them move, they all go the same way at once, and all turn together as well. It seems like they think together, but really they all just react to each other very quickly. When one fish moves a bit to the left, its neighbour straight away moves to the left a bit too, and so this passes through the whole school until they have all moved left. So when Baby Turtle dives down into their midst, the first anchovy moves away and the movement is passed along so that all the anchovies move away! She dives again, but this time she dives right into the middle of the school from above they all scatter. Gee, they are quick! For days and days, then months and months, Baby Turtle is carried along with the Kuroshio current, and sees many different fish that are swept along with her to the east. And on the surface there are still thousands of colourful toys keeping her company.
After a few months Baby Turtle finds that she and the toys have come to a split in the current, like a 'fork in the road'. Part of the current is going south, to her right, and the other part of the current is going north, to her left. The part that is going north is flowing near the coast of Alaska, and is the 'Alaskan' current. It will be cold if she goes north, but there will be so much to see! If she goes south, it is with the 'Californian' current and this will be much warmer but will take her back to where she began after some time. What a hard decision! Go left, and do something daring, something new, something that might be cold and hard, or go right and stay warm, but end up back where she began? Baby Turtle does not have long to decide, for the current is flowing fast and she is at the fork right now. What would you do??
Baby Turtle makes a decision. Although about 20,000 of the bath toys that she has shared her journey of several months with are turning south, the safe route, she decides that she will travel north with the smaller group of about 8,800 toys and go to new and exciting places. Phew! What a decision. But Baby Turtle is sure of herself, and confident in the choice she has made. Besides, it would be too late now to go the other way, and she has to see this journey through to the end. Although it is much colder, heading north is very exciting for Baby Turtle and she is pleased to see so many new and exotic things.
The currents that Baby Turtle has travelled with are formed in an interesting way. When something moves, for example if you throw a ball, there is a force that makes it move. Different forces push the water and work together to make the water move, so that it becomes a current. Firstly there is the force of the Earth turning, and this is called the 'Coriolis' force. When Baby Turtle is north of the equator (the line that divides the northern and southern hemispheres), the Coriolis force pushes her to the right. If she had gone south, with the bigger group of bath toys, then the Coriolis force would have pushed her to the left. Second, there is the force from the wind that blows over the top of the water, and this is called a 'friction' force. It moves anything on the surface very quickly, but the deeper you go in the water, the less it can affect you. There is also a force because of the water in the surface being warmer and moving to stay over the colder water at the bottom. Last there are the currents that are created by the tides and these happen because of the pull of the gravity of the moon on the water of the Earth. The biggest currents in the oceans, like the one that Baby Turtle is in, are called 'gyres' and they are very important for the weather and climate that we experience on Earth.
Baby Turtle is getting very cold now! The water is only 4 degrees Celcius and not very nice for sea turtles. Of course the cold water does not bother her plastic companions! She has been in the Alaskan current for a while, and it is November, 1992, 10 months since she joined the plastic toys on their journey through the North Pacific ocean. But there is no turning back, and she must go on with the toys, still riding along with the Subpolar Gyre, now going west towards Russia. She stays with the current, even though it is cold and hard work, and sometimes she regrets her decision to go north. But finally, more than a year after she left, the current finally reaches the east coast of Russia and turns south, to the warmer waters once again. Baby Turtle has had such an adventure! And now she is heading back to the east again, towards America. It is the end of the year 1994 when Baby Turtle comes to another split in the current, this time one part is heading straight to the icy Arctic, and the other part straight to America. Baby Turtle takes a look at the current heading north and knows that she does not want to endure such cold again for a while, even though it was a great adventure. So she takes the current towards America, and soon enough she is in the warm Californian waters.
While Baby Turtle is travelling towards the coast of America, some of her plastic toy companions head north to brave the waters of the Arctic. They reach the Arctic in 1995, and spend 5 years stuck in the ice. Lucky that Baby Turtle did not go north for she would have been frozen! The toys that make it through the ice in the Arctic travel east to the Atlantic ocean, and by the year 2000 some of them have made it to the other side of America, the east coast. A few of them even travel in a current that takes them to the place where the Titanic sank! It is a great journey for the bath toys, but by now they are spread all over the oceans, and many have gone their separate ways, just like Baby Turtle. We will leave Baby Turtle here, in the warm waters off the coast of California, and we will hope that she has many more adventures!
Science concepts
How ocean currents are created, where they go and why they are important.
Following the actual drift of the plastic toy spill of 1992-2008.
Moral concepts
Importance of making decisions, sometimes taking the hard road, sometimes the easy road.
Activity
1. Labelling the different oceans and continents on the world map provided. Drawing in the journey that Baby Turtle and the bath toys made on the map, and labelling the currents.
2. Discussing the importance of currents for fishing, oil spills, pollution and carbon transport.
| ocean_currents_worksheet.pdf |
| File Size: | 102 kb |
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| ocean_currents_worksheet.doc |
| File Size: | 228 kb |
| File Type: | doc |
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