Original subtitles

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ANNOUNCER: WHEN YOU SEE THIS SYMBOL YOU KNOW YOU'RE

WATCHING TELEVISION THAT'S EDUCATIONAL AND INFORMATIONAL.THE MORE YOU KNOW ON NBC.

DYLAN: I'M DYLAN DREYER.

JOIN ME ON AN EXPLORATION OF THE MOST UNIQUE NATURAL

CITIES ON EARTH LOCATED JUST BENEATH THE CRYSTAL

OCEAN WAVES.

WE'RE ON AN ADVENTURE THROUGH CORAL REEFS AROUND

THE GLOBE TO DISCOVER THE BREATHTAKING MARINE LIFE

THAT CALL THEM HOME.

FROM THE OCEAN'S SMALLEST CREATURES TO THE LARGEST

FISH IN THE SEA, WE'LL COME FACE-TO-FACE WITH

ANIMALS THAT DEPEND UPON CORAL REEFS TO SURVIVE AND

REVEAL IMPORTANT CONNECTIONS OUR TWO WORLDS

SHARE.

DYLAN: CORAL REEFS ARE FOUND IN LESS THAN.1

PERCENT OF THE WORLD'S OCEANS, YET THEY PROVIDE

THE HOME FOR MORE THAN 25 PERCENT OF ALL THE MARINE

SPECIES.

THINK ABOUT THAT.

CORAL REEFS ARE ONE OF, IF NOT THE MOST IMPORTANT

ECOSYSTEM ON EARTH, YET WE HUMANS ARE ONLY JUST

BEGINNING TO FULLY UNDERSTAND CORAL REEFS AND

THE VITAL ROLE THEY PLAY IN THE HEALTH OF OUR

PLANET.

OUR STORY BEGINS ON A SMALL ISLAND IN THE

PACIFIC OCEAN.

DYLAN: IN 1946, IN THE WATERS AROUND THE REMOTE PACIFIC

ISLAND OF BIKINI, CORAL REEFS WERE DEMOLISHED AND

PULVERIZED BY THE TEST EXPLOSIONS OF MULTIPLE

NUCLEAR BOMBS.

MAN: THE BOMB IS AWAY.

AND THIS WAS A BLAST RECORDED FROM A CAMERA

TOWER ON BIKINI.

THE TOWERING CLOUD COLUMN ROSE TO A HEIGHT OF ALMOST

EIGHT MILES.

DYLAN: SINCE RADIOACTIVE FALLOUT CONTAMINATED THE

ISLAND, THE REEFS OF BIKINI WERE LEFT TO THEIR

OWN DEVICES WITH NO HUMAN CONTACT FOR OVER 50 YEARS,

BUT IN THAT TIME, SOMETHING WONDERFUL

HAPPENED; THE REEFS RETURNED...

... THE REEFS OF BIKINI ARE A TESTAMENT TO THE

RESILIENCE OF NATURE, BUT THE REEFS OF THE WORLD NOW

FACE A FAR GREATER THREAT.

THINK OF A REEF AS A CITY, A CITY BENEATH THE SEA.

LIKE OUR CITIES, REEFS OFFER SUSTENANCE AND

SHELTER FOR THEIR DIVERSE COMMUNITIES.

THEY PROTECT AN INCREDIBLE VARIETY OF CREATURES, BUT

OUR CITIES ARE ALTERING THE CHEMISTRY OF THE

OCEAN, THE VERY CHEMISTRY THE REEFS RELY UPON.

DYLAN: CORAL COMES IN SO MANY DIFFERENT SHAPES AND

FORMS.

FOR YEARS, PEOPLE WERE CONFUSED AS TO WHETHER IT

WAS A ROCK FORMATION OR A PLANT.

IN FACT, CORAL REEFS ARE COLONIES OF THOUSANDS OF

TINY ANIMALS CALLED POLYPS, EACH COLONY

SHARING A COMMUNAL SKELETON.

LIVING WITHIN THE CORAL POLYP IS A KIND OF ALGAE.

LIKE A PLANT, THE ALGAE ABSORBS THE SUN'S ENERGY

AND PASSES IT INTO THE CORAL.

DYLAN:IN THIS WAY, CORAL CAN GET AS MUCH AS 90 PERCENT

OF ITS ENERGY FROM SUNLIGHT...

... BUT JUST AS WE NEED MORE THAN ENERGY TO BUILD OUR

CITIES, WE NEED BRICKS AND MORTAR, STONE,

AND CEMENT.

THE REEF'S BUILDING BLOCKS ARE THE CARBON, CALCIUM,

AND OTHER MINERALS DISSOLVED IN SEA WATER OR

TRAPPED IN ORGANIC MATTER.

THEY ABSORB THESE ELEMENTS AND CREATE CALCIUM

CARBONATE.

IT'S NOT UNLIKE THE WAY WE GROW OUR BONES AND

FINGERNAILS.

IT'S AN ORGANIC FACTORY, USING THE SUN'S ENERGY AND

CARBON TO BUILD THE REEF CITIES.

CORAL REEFS RIVAL TROPICAL RAINFORESTS FOR THEIR

WEALTH AND VARIETY OF LIFE.

IF WE LOOK CLOSER, WE SOON REALIZE HOW ALIEN, HOW

BEAUTIFUL THESE CITIES REALLY ARE.

DYLAN: NUDIBRANCHS, THE SLUGS OF THE SEA, ARE JUST

ONE OF AN INCREDIBLE NUMBER OF CREATURES

THAT DEPEND UPON THE REEF.

THEY COME IN AN AMAZING ARRAY OF SHAPES AND

COLORS, AND THEY'RE NO BIGGER THAN YOUR LITTLE

FINGER.

DYLAN: FLATWORMS HAVE NO RESPIRATORY ORGANS.

THEY ABSORB OXYGEN AND EXPEL CARBON DIOXIDE BY A

PROCESS OF DIFFUSION, SO THEIR BODIES ARE PAPER

THIN.

DYLAN: ELSEWHERE ON THE REEF, CLOWNFISH SHELTER WITHIN

THE POISONOUS TENTACLES OF A GIANT SEA ANEMONE.

UNLIKE OTHER REEF FISH, THEY ARE IMMUNE TO THE

ANEMONE'S STING.

AWAY FROM THIS PROTECTION, A CLOWNFISH MIGHT QUICKLY

BE DEVOURED BY PREDATORS.

IN RETURN, THE CLOWNFISH EATS THE ANEMONE'S WASTE

AND LEFTOVERS, AND BY BEING FIERCELY

TERRITORIAL, IT EVEN HELPS WARD AWAY THE ANEMONE'S

PREDATORS.

THIS IS ONE OF THE REEF'S MANY EXAMPLES OF

SYMBIOSIS, A RELATIONSHIP BETWEEN TWO DIFFERENT

CREATURES THAT BENEFITS EACH OF THEM.

CORAL REEFS SUPPORT OVER ONE QUARTER OF THE WORLD'S

MARINE SPECIES, AND THAT INCLUDES A VAST ARRAY OF

MOLLUSKS.

THERE ARE MORE SPECIES OF MOLLUSKS THAN ALL SPECIES

OF BIRD, REPTILE, AND MAMMAL COMBINED.

DYLAN: GROOMING MAY HAVE BECOME SOMETHING OF A

RITUAL IN OUR CITIES.

WE EVEN USE A FORM OF GROOMING THAT DIRECTLY

MIMICS LIFE ON THE CORAL REEF.

CLEANING STATIONS ATTRACT MUCH LARGER ANIMALS TO THE

SHALLOW WATERS OF THE REEFS.

SMALL FISH OPERATE THE STATIONS.

THEY GROOM THE LARGER ONES BY NIBBLING AWAY PARASITES

OR DEAD SKIN.

THESE MANTA RAYS APPROACH THE REEF AT HIGH TIDE IN

SEARCH OF THE CLEANING STATION.

IT'S A PREDICTABLE TIMETABLE THAT CAN ATTRACT

OTHER VISITORS.

DYLAN: CORAL REEFS ARE OFTEN REFERRED TO AS THE

RAINFORESTS OF THE SEA BECAUSE THEY ARE ONE OF

THE MOST DIVERSE ECOSYSTEMS ON THE PLANET,

BUT CORAL REEFS ARE DISAPPEARING FIVE TIMES

FASTER THAN RAINFORESTS, AND THERE ARE A LOT FEWER

OF THEM TO START WITH.

REEF HABITATS ARE CRITICAL TO A HEALTHY OCEAN AND

NEED OUR IMMEDIATE PROTECTION.

DYLAN: COMING UP NEXT, WE'LL TRAVEL TO THE SOUTH

PACIFIC AND EXPLORE CORAL REEFS LIKE NONE OTHER ON

EARTH, AND LATER, WE'LL DISCOVER HOW THE FORGOTTEN

RELICS OF WAR HAVE BEEN RECLAIMED BY THE OCEAN, AS

A NEW CORAL REEF TAKES HOLD.

DON'T GO AWAY.

THE JOURNEY CONTINUES NEXT.

ANNOUNCER: WE'LL BE RIGHT BACK TO THE MORE YOU KNOW ON NBC.

.

ANNOUNCER: WE NOW RETURN TO THE MORE YOU KNOW ON NBC.

DYLAN: WELCOME BACK TO "JOURNEY".

I'M DYLAN DREYER.

HUMAN BEINGS LIKE TO CONCENTRATE INTO CITIES,

AND MARINE LIFE LIKES TO CONCENTRATE INTO CORAL

REEFS.

BOTH ENVIRONMENTS HAVE TRANSFORMED OUR PLANET,

REEFS OVER MILLIONS OF YEARS, AND OUR MODERN

CITIES IN MERELY HUNDREDS OF YEARS.

AS OUR CITIES SPRAWL AND EXPAND, IT'S POSSIBLE TO

SEE THEM FROM SPACE, BUT CORAL CITIES ARE SOME OF

THE LARGEST STRUCTURES ON THE PLANET, AND THEY'RE

ALSO VISIBLE FROM SPACE.

DYLAN: CORAL GROWS AND BUILDS UPON ITS OWN SKELETAL

REMAINS IN WHICHEVER DIRECTION WILL GIVE IT

LIGHT AND WARMTH.

AS A RESULT, REEFS CAN TAKE MANY DIFFERENT FORMS.

THEY FOLLOW COASTLINES.

THEY SURROUND RISING OR FALLING MOUNTAINS.

THEY CAN BECOME ATOLLS AROUND SUNKEN PEAKS.

REEFS OFFER PROTECTION FOR THE ISLANDS WITHIN,

SHELTERING THEM FROM THE RAVAGES OF THE OPEN SEA.

THROUGHOUT TIME, REEFS HAVE CREATED THESE

SHELTERING CITIES BENEATH THE SEA IN TUNE WITH THE

SLOW-MOVING GEOLOGY OF OUR PLANET, AND THEY HAVE

HELPED SHAPE IT.

AS SEA LEVELS CHANGE, EXPOSED REEFS QUICKLY TURN

TO STONE.

OUTCROPS BECOME ROCK ISLANDS, OR OVER TIME THEY

BECOME CLIFFS OR MOUNTAINS.

LIMESTONE FORMATIONS ALL OVER THE WORLD WERE MAINLY

CREATED BY REEF BUILDERS.

REEF LIMESTONE EVEN COVERS THE EXTERIOR OF THE EMPIRE

STATE BUILDING.

FIVE HUNDRED MILES EAST OF THE PHILIPPINES, ANCIENT

REEFS HAVE CREATED AN ARCHIPELAGO OF ROCK

ISLANDS.

SOME OF THE ISLANDS HAVE FORMED MARINE LAKES

COMPLETELY CUT OFF FROM THE SURROUNDING OCEAN.

THE LAKES HAVE TRAPPED WHOLE POPULATIONS OF

JELLYFISH, UNIQUELY SEPARATING THEM FROM THE

OPEN SEA AND THEIR PRINCIPLE PREDATORS, SO

THEY NO LONGER NEED THEIR STING.

THEY SIMPLY DRIFT AROUND THE LAKE, TRACKING THE

SUN, JUST AS DEPENDENT UPON ITS ENERGY AS THEIR

RELATIVES ON THE REEF, THE CORAL POLYPS.

CORAL ATOLLS CREATE CALM LAGOONS WITHIN THE CIRCLE

OF THE REEF, A PERFECT ENVIRONMENT FOR MANGROVE

FORESTS.

JUST A FEW SPECIES OF TREES MAKE UP THESE DENSE

FORESTS.

THEY'VE ADAPTED TO THE HIGH DENSITY OF SALT IN

THE WARM, SHALLOW WATERS.

MANGROVES HARBOR NURSERIES FOR A VARIETY OF MARINE

LIFE.

JUVENILE LEMON SHARKS SHELTER WITHIN THE

MANGROVES, WHERE THERE IS ALSO AN AMPLE SUPPLY OF

FOOD, VENTURING FURTHER AWAY FROM THE MANGROVE

ROOTS AS THEY GROW IN SIZE.

WHEN THE SHARKS REACH 12 TO 15 YEARS OF AGE, THEY

LEAVE THE MANGROVES AND THE LAGOONS BEHIND TO

ASSUME THEIR ROLE IN A COMPLEX INTERLOCKING FOOD

CHAIN THAT CONNECTS THE CREATURES OF THE REEF TO

THE CREATURES OF THE OPEN SEA.

REEF FISH TEND TO GROW SLOWLY AND LIVE LONGER

THAN OCEANIC FISH, BUT THEIR EGGS ARE SPAWNED

DIRECTLY INTO THE OPEN SEA WITH A LESS THAN ONE

PERCENT CHANCE OF SURVIVAL.

THE OCEAN'S GREATEST FOOD SOURCE IS A TINY CREATURE

CALLED PLANKTON.

PLANKTON DRIFTS FREELY IN THE WATER, SWEPT AWAY BY

THE CURRENTS FLOWING IN AND AROUND THE REEFS.

IT'S HERE THAT FEEDING STATIONS FORM.

MANTA RAYS AND HUGE SHOALS OF FISH GATHER AT THESE

STATIONS TO FILTER THE PLANKTON AND NUTRIENTS

FROM THE WATER AS IT FLOWS THROUGH THE CHANNEL.

THE WHALE SHARK IS ONE OF THE LARGEST FILTER FEEDERS

TO VISIT THE REEF, AND IT'S THE LARGEST FISH IN

THE SEA.

AT 40 FEET LONG AND WEIGHING OVER 20 TONS,

IT'S AMAZING THAT THE LARGEST SPECIES IN THE

REEF ARE SUPPORTED BY THE SMALLEST.

COMING UP NEXT, CARBON IS AN ESSENTIAL BUILDING

BLOCK FOR LIFE, BUT TOO MUCH CARBON CAN DESTROY

DELICATE HABITATS AROUND THE GLOBE.

WE'LL SHED SOME LIGHT ON A GROWING THREAT WHEN

"JOURNEY" CONTINUES.

ANNOUNCER: WE'LL BE RIGHT BACK TO THE MORE YOU KNOW ON NBC.

.

ANNOUNCER: WE NOW RETURN TO THE MORE YOU KNOW ON NBC.

DYLAN: THE EFFECTS OF CORAL REEFS EXTEND FAR

BEYOND THEIR BORDERS.

CORAL REEFS ATTRACT ANIMALS FROM THE DISTANT

CORNERS OF THE OCEAN AND PROMOTE HEALTHY ECOSYSTEMS

ABOVE AND BELOW THE WAVES, BUT CORAL REEFS AROUND THE

GLOBE ARE THREATENED EVERY DAY BY HUMAN POLLUTION,

AND MANY OF THE WORLD'S PRECIOUS CORAL REEFS ARE

DISAPPEARING BEFORE OUR EYES.

EVERY SECOND, WE PUMP HUNDREDS OF TONS OF CARBON

DIOXIDE INTO THE ATMOSPHERE IN OUR

UNQUENCHABLE THIRST FOR ENERGY.

A THIRD OF THAT CARBON DISSOLVES INTO THE OCEAN.

CARBON IS AN ESSENTIAL BUILDING BLOCK OF LIFE.

IT IS LOCKED IN ROCKS, BURIED IN FOSSILS,

CIRCULATED IN THE ATMOSPHERE, DISSOLVED IN

THE OCEAN.

THE TRANSITION FROM ONE FORM OF CARBON TO ANOTHER

CAN TAKE MILLIONS OF YEARS OR CAN BE BURNED IN AN

INSTANT.

AS CO2 DISSOLVES IN SEA WATER, THE OCEAN BECOMES

MORE ACIDIC.

EVERY AQUARIUM KEEPER KNOWS THAT THE PH VALUE,

THE MEASUREMENT OF WATER'S ACIDITY, IS VITAL TO THE

HEALTH OF ANY FISH TANK.

SO, IT'S EASY TO UNDERSTAND THAT A CHANGE

ON A GLOBAL SCALE WOULD HAVE A CATASTROPHIC EFFECT

ON LIFE IN THE OCEANS.

AS THE SEA BECOMES MORE ACIDIC, ANY CREATURE THAT

ABSORBS CARBON TO MANUFACTURE A NEW SHELL, A

NEW SKELETON, OR A NEW CORAL STRUCTURE FINDS IT

MORE AND MORE DIFFICULT.

IN THE YEARS SINCE THE INVENTION OF SCUBA GEAR,

TECHNOLOGY HAS TRANSFORMED OUR LIVES, BUT THAT SAME

TECHNOLOGY HAS THREATENED HABITATS ALL OVER THE

WORLD.

THE POLLUTION FROM OUR CITIES, BACTERIA IN OUR

SEWAGE, THE REMOVAL OF MANGROVE FORESTS, EVEN THE

SUN CREAM WE USE TO PROTECT OURSELVES WHILE

SUNBATHING CAN HAVE A HARMFUL EFFECT ON THE

REEFS.

THE ALGAE THAT LIVES WITHIN THE CORAL IS

RESPONSIBLE FOR MUCH OF THE CORAL'S ENERGY AND

ALSO GIVES CORAL ITS COLOR.

WHEN SEA TEMPERATURES RISE, THE ALGAE IS FORCED

TO ABANDON THE CORAL, TAKING WITH IT THE CORAL'S

COLOR.

THIS IS WHAT IS KNOWN AS BLEACHING.

WITHOUT THE ALGAE, THE CORAL CAN DIE OF

STARVATION.

THE IMPACT OF THESE COMBINED THREATS CAN BE

FATAL FOR CORAL, AND MANY REEFS AROUND THE WORLD

HAVE ALREADY BEEN LOST.

REEFS HAVE SO MUCH MORE TO OFFER, AND WE STILL HAVE

SO MUCH TO LEARN, SECRETS TO UNRAVEL.

THEY'RE AS MUCH A POTENTIAL SOURCE OF NEW

BREAKTHROUGHS IN MEDICAL SCIENCE AS THE WORLD'S

RAINFORESTS, YET INCREDIBLY, REEFS ARE

VANISHING FIVE TIMES FASTER THAN RAINFORESTS,

AND THERE IS ANOTHER MUCH GREATER THREAT.

AT NIGHT, THE LIGHT THAT GLOWS FROM OUR CITIES

REQUIRES AN ENORMOUS AMOUNT OF ENERGY, AND

WHERE ENERGY IS CONCERNED, THERE IS ALWAYS A PRICE TO

PAY.

DON'T GO AWAY.

THE JOURNEY CONTINUES RIGHT AFTER THIS.

ANNOUNCER: WE'LL BE RIGHT BACK TO THE MORE YOU KNOW ON NBC.

.

ANNOUNCER: WE NOW RETURN TO THE MORE YOU KNOW ON NBC.

DYLAN: LOSING CORAL REEFS WOULD HAVE A DISASTROUS

EFFECT ON THE OCEAN FOOD CHAIN, MARINE

ENVIRONMENTS, AND FINALLY, YOU AND ME.

IT'S IMPORTANT TO REMEMBER, HOWEVER, THAT

NATURE IS RESILIENT.

CORAL REEFS CAN BE SAVED, AND NEW CORAL REEFS CAN

TAKE HOLD.

IT'S UP TO US.

DYLAN: CORAL SPAWNS ITS EGGS INTO THE SEA.

THE LARVAE DRIFTS ON THE OCEAN CURRENT, SOME

FINDING THEIR WAY BACK TO THE REEF OF THEIR ORIGIN.

OTHERS, HOWEVER, FIND NEW HOMES, NEW ROCKS, NEW

STARTING PLACES.

BY SPREADING TO NEW AREAS AS THE WORLD CHANGES

AROUND THEM, CORAL HAS SURVIVED OVER MILLIONS OF

YEARS.

CORAL WILL TAKE ADVANTAGE OF ANY STRUCTURE.

SO LONG AS THE WATER IS CLEAR AND CLEAN AND HAS

AMPLE SUNLIGHT, THEY'LL CREATE A WHOLE NEW

ENVIRONMENT.

RELICS OF WAR IN THE PACIFIC ARE NOW HOME TO

THE REEF BUILDERS, SLOWLY TRANSFORMING THEM OVER

TIME.

DECOMMISSIONED SHIPS ARE NOW REGULARLY SUNK TO

ENCOURAGE THE DEVELOPMENT OF NEW CORAL REEFS.

EVEN STATUES CAN FORM THE BASIS OF A NEW HABITAT, A

NEW CITY.

ALL OVER THE WORLD, PEOPLE ARE TRYING TO LEND THE

REEF BUILDERS A HELPING HAND, BUT REEFS CANNOT

REBUILD IN AN ACIDIFIED OCEAN.

THE VERY SIMPLE CHEMISTRY WHEREBY CO2 RAISES THE

WATER'S ACIDITY IS UNDENIABLE.

THE CALL FOR CUTTING OUR CARBON EMISSIONS, FINDING

GREENER SOURCES OF ENERGY, GREENER FORMS OF TRANSPORT

BECOMES MORE VITAL THAN EVER.

IT'S THE ONE WAY WE CAN ALL CONTRIBUTE, HOWEVER

INDIRECTLY, TO THE RECOVERY OF THE WORLD'S

OCEANS.

THE REEF BUILDERS WILL RETURN.

THEY WILL CREATE NEW HOTSPOTS OF DIVERSITY IN

THE OCEANS, NEW CITIES BENEATH THE SEA, ONLY IF

WE LET THEM.

PERHAPS WE CAN LEARN FROM THE LESSONS OF BIKINI

ISLAND.

CORAL REEFS HAVE AN AMAZING ABILITY TO

REBUILD, AND THEIR INFLUENCE REACHES FAR

ACROSS LAND AND SEA.

THE LAST REEF IS NOW OUR RESPONSIBILITY, A

RESPONSIBILITY THAT WE CANNOT IGNORE.

DYLAN: DO SOME RESEARCH; GET INVOLVED; FIND OUT

HOW YOU CAN HELP PROTECT AND SAVE CORAL

REEFS AROUND THE GLOBE.

REMEMBER, THE DELICATE AND BEAUTIFUL CORNERS OF OUR

WORLD WILL SURVIVE IF ONLY WE DECIDE THEY SHOULD.

I HOPE YOU'LL JOIN US NEXT TIME FOR ANOTHER AMAZING

JOURNEY.

UNTIL WE MEET AGAIN, SAFE TRAVELS.

♪ MUSIC ♪