The Galapagos Islands and many of their unique creatures are at risk from warming waters

Saltwater succulents grow near the water on Bartolome Island, Ecuador in the Galapagos Islands on Friday, June 7, 2024. (AP Photo/Alie Skowronski)

GALÁPAGOS ISLANDS, Ecuador (AP) — Warm morning light reflects off the remains of a natural rock arch near Darwin Island, one of the most remote in the Galapagos. In the clear, deep blue water, thousands of creatures — fish, hammerhead sharks, marine iguanas — move in search of food.

The 2021 collapse of Darwin’s Arch, named after the famed British naturalist behind the theory of evolution, was caused by natural erosion. But its demise underscored the vulnerability of a remote archipelago under increasing pressure from climate change and invasive species.

Warming oceans are affecting the food sources of many Galapagos marine animals. Marine iguanas—one of several species endemic, or unique, to the Galapagos—are having a harder time finding the red and green algae they prefer. Sea turtles are having a harder time nesting in warmer temperatures. Raising young becomes more difficult as waters warm and nutrients become scarce.

Although the Galapagos Islands are known for their wide variety of animal species, their numbers are not unlimited.

“We have a bit of everything here – that’s why people say the Galapagos is so diverse – but we have a small amount of everything,” says Natasha Cabezas, a naturalist guide.

The Galapagos have always been sensitive to changes in ocean temperature. The archipelago itself lies at the confluence of major ocean currents — cool from the south, warm from the north, and a cold upwelling current from the west. And then there’s El Niño, the periodic and natural warming of the Pacific Ocean that affects weather worldwide.

Although temperatures fluctuate with the season and other naturally occurring climate events, ocean temperatures have been rising due to human-caused climate change, as oceans absorb the vast majority of excess heat in the atmosphere. The ocean experienced its warmest decade since at least the 1800s over the past 10 years, and 2023 was the ocean’s warmest year on record.

In early June, winter begins in the Southern Hemisphere, and the Cromwell Current brings whale sharks, hammerheads and giant sunfish to the surface. It also provides nutrients for penguins, marine iguanas and sea lions searching for food. With more of those animals showing up this season, scientists are keeping track of how they fared in the warming El Niño of the past year.

El Niño can cause food shortages for some species, such as marine iguanas and sea turtles, because the warmer ocean means fewer food sources. Scientists who monitor the species have noticed significant declines in population numbers during El Niño events.

Marine iguanas swim like snakes through the water from rock to rock as waves crash against the shore of Fernandina Island. They cling to the underwater rocks to feed on the algae that grows there, while sea lions circle around them like puppies looking for someone to play with.

The iguanas were “one of the species most affected by El Niño last year and are still recovering,” said Jorge Carrión, director of the Galapagos Conservancy.

While rising ocean temperatures threaten life in the water or at sea, there is another problem on land. Wild animals — cats, dogs, pigs, goats and cattle, none of which are native — are threatening the islands’ unique species.

According to Cabezas, many people are abandoning their dogs and cats after the COVID-19 pandemic, wanting to keep them company.

“If you don’t take care of them, they become a problem and now it’s a shame to see dogs everywhere. We have a big problem now, I don’t know what to do,” she said.

The non-native animals pose a special threat to the giant tortoises that are closely associated with the Galapagos. The tortoises declined dramatically in the 19th century due to hunting and poaching, and authorities have worked to protect them from humans. It has been illegal to kill a giant tortoise since 1933.

“In one night, a feral pig can destroy all the nesting sites in an area,” Carrion said. Park rangers try to visit nesting areas once a day and kill the pigs if they find them. But the pigs are elusive, Carrion said.

Feral cats feed on the young of marine iguanas, and both pigs and cats compete with the turtles for food.

As if invasive species and warming oceans weren’t enough, there’s also plastic that’s a widespread problem in the world’s oceans. A recent study reported microplastics in the bellies of Galapagos penguins.

“There are no animals in the Galapagos Islands that do not have microplastics in their food,” Carrión said.

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