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A total of 53 invasive alien marine species have found their way to life in the Galapagos Islands (Ecuador), which is ten times more than what scientists previously thought. This is reflected in a study carried out by researchers from the Smithsonian Research Center Environmental and Williams College (United States), as well as the Charles Darwin Foundation (Ecuador), and published in the journal Aquatic Invasions .
The work documents 53 species of marine animals introduced into the Galapagos, a site included in the Unesco World Heritage List and one of the largest marine protected areas on Earth . Previously, scientists only knew about five invasive species.
“This increase in exotic species is a surprising discovery, especially because in this initial study only a small fraction of the Galapagos Islands were examined,” says Greg Ruiz, co-author of the work and marine biologist at the Smithsonian Center for Environmental Research.
James Carlton, professor emeritus of the Maritime Studies Program at the Williams College-Mystic Seaport, notes that this is “the largest documented increase in exotic species in any tropical marine region in the world.”
The Galapagos are located in the equatorial Pacific about 972 kilometers west of Ecuador. Famous for the visit of Charles Darwin in 1835, the islands have been recognized for their extraordinary biodiversity, but transit has exploded with its popularity. Not in vain, in 1938 there were barely more than 700 people living in the archipelago, when now more than 25,000 people live, and almost a quarter of a million tourists arrive on the islands every year.
Carlton and Ruiz began their study in 2015 together with Inti Keith, of the Charles Darwin Foundation. They carried out field studies on two of the largest islands in the Galapagos (Santa Cruz and Baltra), where they hung spring settlement plates one meter under water to see which species would grow in them. They also collected samples of mangrove roots, floating docks and other debris and searched the scientific literature for previous records of marine species on the islands.
The team documented 48 additional non-native species in the Galapagos. Most of them (30) were new discoveries that might have survived unnoticed on the islands for decades. Another 17 were species that scientists already knew lived in the Galapagos, but before they were believed to be native. A last species, the briozoo Watersipora subtorquata , was collected in 1987 but has not been identified so far.
Arrival in boats
Ascidiaceans, marine worms and bryozoans constitute the majority of non-native species. Almost all of them probably arrived inadvertently on ships from tropical seas around the world. Some of the most disturbing discoveries include the bryozoan Amathia verticillata , known for fouling fishing lines and rigs and killing seagrass, and the mussel Leiosolenus aristatus , which researchers have already seen piercing Galapagos corals.
“This discovery restores the way we think about what is natural in the ocean around the Galapagos and the impacts they can have on these high-value conservation areas,” says Carlton.
To reduce future invasions, the Galapagos already have one of the strictest biosecurity programs in the world . International vessels that enter the Galapagos Marine Reserve can anchor only in one of the main ports, where divers inspect the ship. If they find any non-native species, the boat is asked to leave and clean the hull before returning to be subjected to a second inspection.
Expansion of the Panama Canal
Even so, the risks remain high. The expansion of the Panama Canal in 2015 can lead the Indo-Pacific lionfish – a major predator in the Caribbean – to the Pacific coast of Central America. Once there, it could reach the Galapagos, where the probability of its success would be very high. Another possible arrival is the Indo-Pacific snowflake, which has already caused the widespread death of native corals in the South American continent.