A 2021 breakthrough study has uncovered the key to life in one of the most biodiverse places on the planet, and why it needs to be protected, now more than ever.
Writer: Ericka Mejía Farias
Editor: Natalia Sanchez
Artist: Lucie Gourmet
Biodiversity, or the biological variety of life on Earth, is important for the sustainability of all organisms on the planet, including humans. According to Conservation International, there are only 36 key biodiversity hotspots on the planet, and while these hotspots cover only 2.4% of Earth’s land, they account for around 60% of all its animal species.
The South American country of Ecuador is known to be one of the most biodiverse places on Earth, and is home to the Galápagos Islands. These volcanic islands are 1,000 km off the Ecuadorian mainland and are known to have a harsh, dry, inhospitable environment. And yet, the Galápagos are classified as a biodiversity hotspot. This strange paradox has stumped scientists for centuries, until now.
A 2021 breakthrough study by the UK National Oceanography Centre and the Galápagos Science centre used a high-resolution computer model of ocean circulation around the Galápagos archipelago to finally uncover the secret to its unprecedented biological success: wind. More concretely, the presence of nutrient-rich algae that comes from a cold-water upwelling in the surrounding ocean caused by key seasonal winds.
The study discovered that northward-flowing winds along the meridian facilitate mixing of the upper layers of the ocean in the Galápagos region. This wind-driven upwelling of water allows the colder, nutrient-rich deep ocean water to rise and displace the warmer nutrient-deficient surface water, increasing nutrient supply for the phytoplankton, or algae, located in the light-receiving top ocean layers.
This critical upwelling occurs primarily along the western coast of the Galápagos archipelago, particularly during dry seasons. The study found that the shape and location of the Galápagos islands are crucial for these wind-ocean interactions; by blocking the westward-flowing south equatorial ocean current, the western coasts create density fronts that predispose the area to wind-driven upwelling. Moreover, the northward winds are responsible for driving the Humboldt current, which brings cold Antarctic waters to displace the warmer waters in the region.
The phytoplankton that benefit from this upwelling are a key food source for many of the animals found in and around the Galápagos. The presence of this algae is believed to have led to the migration of many land and marine animals to the Islands from the Ecuadorian mainland and surrounding ocean. Algae served as the main food source for krill, which were eaten by sea birds that flew from mainland Ecuador. Krill-eating iguanas and other reptiles arrived in style by sailing on floating logs, whilst penguins from Antarctica and Argentina likely took the Humboldt current. Marine animals came from nearby waters, drawn by the abundance of algae-eating fish and crustaceans.
Furthermore, the harsh conditions of the Islands have caused many of these land and sea animals to adapt through natural selection, further diversifying the animal population. Hence, this western area of seasonal wind-driven upwelling is heavily responsible for the creation and maintenance of one of the most biodiverse places on the planet.
So why does this matter? The Galápagos are one of the largest UNESCO World Heritage Sites on the planet and have the highest levels of endemism on the globe, meaning that the majority of its local species cannot be found anywhere else in the world. These animals are at an acute risk of extinction, which would result in irreplaceable losses to our planet; indeed this was sadly the case with the last Pinta Island tortoise, the late Lonesome George. So, understanding the wind and ocean forces that maintain this biodiversity is crucial for improving conservation efforts.
Unfortunately, industrial fishing fleets have also exploited this seasonal phenomenon and currently focus their fishing activities in this area of upwelling. Overfishing is one of many threats to the wonderful biodiversity of the Galápagos Islands along with pollution, human colonisation, the introduction of invasive animal species, and climate change. Climate change in particular has caused an increase in El Niño phenomena, which decrease density fronts and result in weaker winds in the area; this directly reverses the Galápagos upwelling, increasing water temperatures and depleting algae populations, thereby killing off many endemic species.
Conservation of these islands is essential, which is why there have been calls on Ecuador’s current president to expand the Galápagos marine reserve, in order to protect more species from industrial fishing. There are also global initiatives to slow global warming, which has been negatively impacting the cold upwellings needed for the survival of the Galápagos.
Now, more than ever, we need to come together to harness this new scientific knowledge to help conserve such an invaluable piece of biodiversity, because, in the words of Sir David Attenborough, “if we take care of nature, nature will take care of us”.