GALAPAGOS ISLANDS, Ecuador — Warm morning light reflects on the remains of a natural rock arch near Darwin Island, one of the most remote islands in the Galapagos. In clear, deep blue waters, thousands of creatures (fish, hammerhead sharks, marine iguanas) move in search of food.
The 2021 collapse of Darwin’s Arch, named after the famous British naturalist behind the theory of evolution, was due to natural erosion. But its disappearance highlighted the fragility of a distant archipelago that is under increasing pressure from both climate change and invasive species.
Warming oceans affect the food sources of many of the Galapagos marine animals. Marine iguanas, one of the many species endemic or unique to the Galapagos, have a harder time finding the red and green algae they prefer. Sea turtles struggle to nest in warmer temperatures. Raising young becomes more difficult as the water warms and fewer nutrients are available.
While the Galapagos are known for a multitude of species, their number is not unlimited.
“We have a little bit of everything here, that’s why people say the Galapagos is so diverse, but we have a small amount of everything,” said Natasha Cabezas, a naturalist guide.
The Galapagos have always been sensitive to changes in ocean temperature. The archipelago itself is located where the main ocean currents converge: cold from the south, warm from the north and a cold rising current from the west. Then there’s El Niño, the periodic, natural warming of the Pacific Ocean that affects climate around the world.
While temperatures vary with the season and other natural weather phenomena, ocean temperatures have increased due to human-caused climate change, as the oceans absorb the vast majority of excess heat from the atmosphere. The ocean experienced its warmest decade since at least the 19th century in the past 10 years, and 2023 was the warmest year. The warmest year on record in the ocean.
Winter arrives in the Southern Hemisphere in early June, and the Cromwell Current brings whale sharks, hammerhead sharks, and huge sunfish to the surface. It also provides nutrients to penguins, marine iguanas and sea lions in search of food. As more of those animals come forward this season, scientists are tracking how they fared during a warming planet. Last year’s Child.
El Niño can cause food shortages for some species such as marine iguanas and sea turtles, as warming of the ocean means a decrease in food sources. Scientists observing the species have noted a significant decline in the population 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 the sea lions circle around them like puppies looking for someone to play with.
Iguanas were “one of the species most affected by El Niño last year and are now still recovering,” said Galapagos Conservation Director Jorge Carrión.
While rising ocean temperatures threaten aquatic or marine life, there is a different problem on land. Wild animals (cats, dogs, pigs, goats and cattle, none of them native) are threatening the islands’ unique species.
After the COVID-19 pandemic, many people are abandoning the dogs and cats they wanted to keep them company, Cabezas said.
“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 right now and I don’t know what we are going to do,” she said.
Non-native animals are a special threat to the giant tortoises closely associated with the Galapagos. Turtle numbers 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 wild boar can destroy all the nesting sites in an area,” Carrión said. Park rangers try to visit areas with nesting sites once a day and kill pigs when they find them. But pigs are elusive, Carrión said.
Feral cats prey on baby marine iguanas, and both pigs and cats compete for food with turtles.
If invasive species and warming oceans weren’t enough, there’s the Plastic, 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 that do not have microplastics in their food,” said Carrión.
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