NY
Times 12/18/18 by Nicholas Casey a New York Times correspondent based in
Colombia, and Josh Hamer,a Tmes Photographer traveled 600 miles off the coast
of Ecuador to see how ocean warming is affecting Darwin’s first laboratory.
ALCEDO
VOLCANO, Galápagos — When the clouds break, the equatorial sun bears down on
the crater of this steaming volcano, revealing a watery landscape where the
theory of evolution began to be conceived.
Across
a shallow strip of sea lies the island of Santiago, where Charles Darwin once
sighted marine iguanas, the only lizard that scours the ocean for food.
Finches, the product of slow generational flux, dart by. Now, in the era of
climate change, they might be no match for the whims of natural selection.
In
the struggle against extinction on these islands, Darwin saw a blueprint for
the origin of every species, including humans.
Yet
not even Darwin could have imagined what awaited the Galápagos, where the stage
is set for perhaps the greatest evolutionary test yet.
As
climate change warms the world’s oceans, these islands are a crucible. And
scientists are worried. Not only do the Galápagos sit at the intersection of
three ocean currents, they are in the cross hairs of one of the world’s most
destructive weather patterns, El Niño, which causes rapid, extreme ocean
heating across the Eastern Pacific tropics.
Research
published in 2014 by more than a dozen climate scientists warned that rising
ocean temperatures were making El Niño both more frequent and more intense.
Unesco, the United Nations educational and cultural agency, now warns the
Galapagos Islands are now one of the places most vulnerable to the impacts of
climate change.By Jeremy White
To
see the future of the Galápagos, look to their recent past, when one such event
bore down on these islands. Warm El Niño waters blocked the rise of nutrients
to the surface of the ocean, which caused widespread starvation.
Large
marine iguanas died, while others shrank their skeletons to survive. Seabirds
stopped laying eggs. Forests of a giant daisy tree were flattened by storms and
thorny invasive bushes took over their territory. Eight of every 10 penguins
died and nearly all sea lion pups perished. A fish the length of a pencil, the
Galápagos damsel, was never seen again.
That
was in 1982. The world’s oceans have warned at least half a degree Celsius
since then.
David
J. Anderson, a biologist at Wake Forest University who studies the blue-footed
booby, a seabird, said the ravages of El Niño were a surprise when he began
working on the islands in the 1980s.
“Now
we are wondering, how frequent do these things get? El Niños have a bulldozer
effect,” he said. “And they are happening more and more.”
Though
the Galápagos lie at the heart of the geographic tropics, it’s hard to guess
that, standing on one of the islands, because of a vast current that flows
north from southern Chile. That stream, the Humboldt Current, keeps the islands
cool and rainless most of the year, unusual given that the Equator crosses
through the archipelago. It means the islands are subtropical in climate, a
rare place where penguins and corals exist side by side.
This
cold Antarctic current brings rich nutrients. Fish are abundant. For penguins,
it is a tropical paradise. But sometimes the cool Humboldt Current suddenly
slows.
The
ocean waters start warming rapidly, heating up as much as 2 degrees Celsius, or
3.6 degrees Fahrenheit, within months. Storms begin to strike the islands with
rain and flash floods. And, as if overnight, the Galápagos become warmer: It is
the start of El Niño, Spanish for “the boy child,” a reference coined by
Peruvian fisherman because the changes can occur around Christmas.
“The
Galápagos marine system is analogous to a roller coaster,” said Jon D. Witman,
a professor of biology at Brown University who studies coral ecosystems in the
Galápagos, noting that the spikes of hot temperatures were followed by spells
of falling temperatures, known as La Niña.
The
problem with global warming, Dr. Witman said, is that the baseline from which
these swings occur is rising as the ocean temperatures do. This, as the
intensity and frequency of El Niño is increasing.
Before
he published “Moby Dick,” Herman Melville sailed past the Galápagos and saw the
black marine iguanas clinging to the rocks. They were “that strangest anomaly
of outlandish nature,” he wrote in a literary sketch published in the 1850s.
One
particular anomaly of the marine iguanas offers a clue into what warmer
Galápagos seas may have in store for them.
Martin
Wikelski, an evolutionary biologist at the Max Planck Institute of Ornithology
in Germany, was spending his research seasons off the coast of Genovesa Island
when he noticed something strange in his calculations. When the seas warmed,
the size of the iguanas started to decrease.
“Obviously
an animal can’t shrink, it’s impossible,” he said he initially thought. “But
they looked odd, like frogs where the legs were too long for the body.”
It
turned out the iguanas were in fact becoming much smaller.
Rising
ocean temperatures mean less algae, the main source of food for marine iguanas.
Scientists say they believe that the reptiles may reabsorb parts of their
skeleton in order to decrease their size and increase their chances of survival
on a smaller diet. Stress hormones may trigger the process, but little more is
understood about how the iguanas adapt. Nevertheless, the changes could be
central to their survival as El Niño cycles become more frequent.
Evolution
has led other animals in different directions, which could now prove fatal as
ocean temperatures rise.
On
a recent day on the southern shores of Isabela, the largest island in the
Galápagos Archipelago, a male sea lion howled over a gaggle of pups in a tide
pool. Sea lions and fur seals here have no set breeding season, so males are
constantly on the defense against competitors — a costly vigilance that takes
away from their time to hunt fish.
When
sea temperatures rise, the sardine population around Isabela Island drops. In
the 1982 El Niño, nearly every large adult male fur seal died of starvation.
Most of the sea lion pups born that year died as well because parents couldn’t
feed their young, according to a study by Fritz Trillmich, a behavioral
ecologist.
“It’s
like if our generation didn’t have kids,” said Robert Lamb, a doctoral
candidate in ecology and evolutionary biology at Brown University.
Last
month, the craggy rocks in a cove off the north shore of Isabela Island were strewn
with the bones of a massive fish — tuna, which scientists say they haven’t seen
sea lions eat before.
But
just after dawn on a recent morning there, sea lions chased one large tuna into
the cove, then slaughtered it in the shallows.
Whether
this is simply a new behavior that emerged when populations of smaller fish
grew scarce hasn’t been studied, but the new diet could prove advantageous to
sea lions as El Niños become more frequent.
Other
animals have fewer options to change their diet.
Blue-footed
boobies, birds known for their bright feet and clownish waddle, line the shores
here. But at sea, these specialized fish-eaters soar gracefully above the waves
before plunging into the ocean like competitive divers, scattering the clouds
of fish so they can be picked off individually.The blue-footed boobies once
lived principally on sardines. But for reasons unknown, sardine populations
plummeted in 1997 and the fish remain scarce, forcing the birds to eat other fish.
When sea temperatures rise during El Niño, these other fish also start to
disappear.
“They
basically stop trying to breed,” Dr. Anderson, the Wake Forest biologist, said
of the boobies. He said the pattern had become more frequent in parallel with
El Niños.
Blue-footed
boobies catching fish near Isabela Island.
“One
hundred years from now, I would not be surprised if the blue-footed boobies
were gone” if current trends continue, Dr. Anderson said.
Similar
behaviors are seen in other aquatic birds here. Galápagos penguins, which are
only found on these islands, stop breeding when the water reaches 25 degrees
Celsius, or about 77 degrees Fahrenheit.
Flightless
cormorants starve at their nests because they cannot travel to find food
elsewhere when fish populations drop near the islands.
Flightless
cormorants at their nesting ground on Fernandina Island.
While
warmer temperatures often spell doom for native species that evolved to the
Galápagos’ cool subtropical climate, invasive species flourish.
Forests
of the Scalesia, a giant daisy tree that is unique to the Galápagos, were
already shrinking because of clear-cutting for agriculture in the highlands.
The trees are accustomed to mild weather, so the violent storms that come with
extreme El Niños can flatten their forests. While destructive, storms have long
been part of a natural cycle for these daisy trees, allowing a new generation
to take root after the last.
With
climate change, however, the process is being short-circuited. Below the
Scalesia forests, the seeds of an invasive blackberry wait for the giant daisy
trees to fall. The blackberry plants quickly spread, blocking the next
generation of the trees.
“I’m
afraid if nothing is done about the blackberry, the Scalesia forests will not
recover in the long run,” said Heinke Jäger, an ecologist at the Charles Darwin
Foundation in the Galápagos, referring to repeated blows from El Niño.
Dr.
Jäger noted that an extreme El Niño in 1997 and 1998 was thought to have
coincided with the introduction of the first frog on the islands, Fowler’s
snouted tree frog, which may have helped them thrive. They threaten to wreak
havoc on the island’s insects and other invertebrates.
Another
invasive species that worries scientists is the fire ant, which flourishes in
wetter temperatures and eats the eggs of giant tortoises and attacks the legs
and eyes of adults.
“You
can see them laying one or two eggs and being attacked by the ants,” said
Christian Sevilla, a conservationist at the national park here. “They’re just
throwing off the rest of the eggs as they walk off trying to escape, with the
ants still biting at their legs.”
(Not
without irony, Darwin was a predator of the tortoises well before the ants
were. “The young tortoises make excellent soup,” he wrote in 1839.)
Mr.
Sevilla and other workers at the park are now considering mitigation efforts to
try to protect threatened species from the more frequent El Niño events that
have come with climate change. The park already has a program to breed giant
tortoises in captivity.
But
not all giant tortoises can be bred in a pen. Nor can many of the other
creatures on these islands. As the climate changes, so will the Galápagos.
Posts
