Today, about 5,000 different coral species live in the world’s waters. Many people think coral reefs are found only in warm, shallow waters. But about half of coral species live in cold, deep waters. Many also form mesophotic reefs, in depths of about 100 to 500 feet. Reefs can stretch out for hundreds or even thousands of miles. The world’s largest reef is Australia’s Great Barrier Reef. It is about 1,400 miles long and can be seen from space.
Aerial view of the Great Barrier Reef. Although many people realize the value of coral reefs, human activity is a direct threat to them.
Over the last 50 years, about half of the known coral reefs have died. Some scientists think the ones still left might die before the end of the 21st century. Some coral reefs are lost because of building along shorelines. Pollution in many forms, from plastic garbage to human waste, can also damage reefs.
A major concern today is climate change. When humans burn certain fuels, carbon dioxide and other gases enter the air. Over time, these gases have caused temperatures across the planet to rise. Ocean temperatures are rising too. This is also killing off some coral reefs.
Warmer waters kill the algae most corals need to live. As the reefs die, they lose their color and turn white. This process is called bleaching. Climate change has also increased the acid levels in the water. Higher acid levels damage reefs.
Some reefs face threats from species that are not native to their waters. Fish such as lionfish can eat algae that the reefs need to live. Or they eat other fish that help get rid of the kind of seaweed and algae that’s harmful to the corals.
The effort to protect the coral reefs goes on around the world. Scientists study why some coral reefs can survive harsh conditions and some can’t. To collect samples, they have several tools. Some are hi-tech, like remote-controlled robots and minisubs that can go down thousands of feet. But at times, scientists use simple snorkeling equipment to carry out their work.
Back in their labs, some researchers grow corals. Then they transplant them onto rocks or other hard surfaces underwater to try to create new reefs.
Scientists who study marine life are working hard every day to make sure the world’s coral reefs survive the many threats they face.
WORLD MAP OF CORAL REEFS
The red areas show where the world’s major known coral reefs are located. The yellow, green, and blue colors show the temperatures of the oceans. The darker the color, the warmer the water is.
GLOSSARY
algae (AL-jee) —
small plants without roots or stems that grow in water or on damp surfaces
autonomous (aw-TAH-nuh-muhss) —
able to control oneself; autonomous robots are not operated remotely by a person
carbon dioxide (KAHR-buhn dy-AHK-syd) —
a colorless, odorless gas that people and animals breathe out
climate change (KLY-muht CHAYNJ) —
a significant change in Earth’s climate over a period of time
colony (KAH-luh-nee) —
a large group of animals or creatures that live together in the same area
cylinder (SI-luhn-duhr) —
a shape with flat, circular ends and sides shaped like a tube
extinct (ik-STINGKT) —
no longer living; an extinct animal is one that has died out, with no more of its kind
marine biology (muh-REEN bye-AH-luh-jee) —
the study of creatures and plants that live in the oceans
mesophotic (MEE-zoh-fowh-tik) —
native (NAY-tuhv) —
a species that lives and grows naturally in a particular region
patch reef (PACH REEF) —
a small area of coral reefs
scuba (SCOO-bah) —
swimming underwater with the help of special breathing equipment; scuba stands for self-contained underwater breathing apparatus
snorkel (SNORE-kuhl) —
a tube used to let a person breathe underwater
sonar (SOH-nar) —
a device that uses sound waves to find underwater objects; sonar stands for sound navigation and ranging
submersible (suhb-MURS-uh-buhl) —
a small vessel used under water, usually for research
super coral (SOO-puhr KOR-uhl) —
coral that can survive extreme conditions and rapid changes in their environment
transplant (TRANS-plant) —
to move a living thing from one area to another
tsunami (tsoo-NAH-mee) —
a gigantic ocean wave caused by an undersea earthquake, landslide, or volcanic eruption
winch (WINCH) —
a lifting device in which a cable winds around a revolving drum
OTHER PATHS TO EXPLORE
In one path, you deal with an encounter with a shark. What would you do if you were seriously injured by a shark? Would that deter you from working to help save coral reefs?
In another path, you spend time on a research ship. If you could take a research ship to anywhere in the ocean, where would you go and what would you study?
The health of coral reefs and ocean pollution are both serious problems. Which do you think is more important, and what type of work would you prefer to do to help? Why?
READ MORE
Mattern, Joanne. Submarines and Submersibles. Vero Beach, FL: Rourke Educational Media, 2019.
Raij, Emily: Climate Change and You: How Climate Change Affects Your Life. North Mankato, MN: Capstone Press, 2020.
Topacio, Francine. Creatures of a Colorful Coral Reef. New York: PowerKids Press, 2020.
INTERNET SITES
Basic Information About Coral Reefs
epa.gov/coral-reefs/basic-information-about-coral-reefs
Corals and Coral Reefs
ocean.si.edu/ocean-life/invertebrates/corals-and-coral-reefs
Coral Bleaching
climatekids.nasa.gov/coral-bleaching/
Saving the World’s Coral Reefs
coral.org/coral-reefs-101/coral-reef-ecology/coral-polyps/
INDEX
Atlantic Ocean, 10
AUVs, 18-19, 21, 22-24, 25-26, 27
bleaching, 13-14, 36, 81, 102
Carrie Bow Cay, 7-9, 47, 73, 86
climate change, 9, 101, 102
CTDs, 52-53, 55
Great Barrier Reef, 14, 99
Hawaii, 10, 71, 73, 77, 85
Kaneohe Bay, 71, 73
lionfish, 56-58, 60-61, 62-63, 64, 102
marine biology, 8
Pacific Ocean, 10, 13, 84
Palau, 13-14, 19, 36
patch reefs, 80, 81, 83
Philippines, the, 13
pollution, 9, 10, 71, 78, 86, 88, 100
ROVs, 18, 49, 51, 56-58, 59-61, 62, 64-65, 65, 102
scuba diving, 15, 28, 30-31, 36-38, 40, 41, 43, 44-45, 75, 78, 81-82, 83, 89, 90-91, 92, 95-96
seaweed, 56, 75-76, 102
Singapore, 71-72, 86, 88
snorkeling, 15, 16, 75, 102
submersibles, 30-31, 32, 33, 35, 42, 48, 56-58, 66, 68, 69, 102
super coral reefs, 71-72, 73-74, 78, 80, 81-82, 85
tsunamis, 84, 85
You Choose Books are published by Capstone Press, an imprint of Capstone.
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Copyright © 2021 by Capstone. All rights reserved. No part of this publication may be reproduced in whole or in part, or stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission of the publisher.
Library of Congress Cataloging-in-Publication data is available on the Library of Congress website.
ISBN 978-1-4966-9597-0 (library binding)
ISBN 978-1-4966-9705-9 (paperback)
ISBN 978-1-9771-5393-7 (eBook PDF)
ISBN 978-1-9771-5721-8 (eBook)
Summary: Pollution, climate change, and overfishing are killing the world’s coral reefs. But you can help! Navigate through three different stories in this ecological rescue mission.
Photo Credits
Dreamstime/Colin Moore, 59; Getty Images: GIANRIGO MARLETTA, 79, Miami Herald, 50; Newscom: Howard Lipin, 42, Yang Guanyu Xinhua News Agency, 90; Science Source: David Vaughan, 26, Jessica Wilson, 106-107; Shutterstock: Afanasiev Andrii, 54, Andrey Armyagov, cover, (top), 1 (t), aquapix, 29, Dan Logan, 46, Ethan Daniels, 12, 100-101, 104-105, Ian Scott, 93, Karel Bartik, 96, Keat Eung, 63, Kristina Vackova, 34, Lewis Burnett, 70, muratart, 20, Ocean Image Photography, 74, rangizzz, cover (b), backcover (t), 1 (b), 4, S.Bachstroem, 67, SARAWUT KUNDEJ, 17, Simon Dannhauer, 6, superjoseph, 98, UnderTheSea, 39, Vlad61, 83, Vorayooth Panakul, 87
Artistic elements: Shutterstock: Natali Snailcat
Editorial Credits
Editor: Michelle Parkin; Designer: Bobbie Nuytten; Media Researcher: Kelly Garvin; Production Specialist: Katy LaVigne
All internet sites appearing in back matter were available and accurate when this book was sent to press.