Invasive blackberry becomes near-ubiquitous presence on Galapagos Islands

By Elias L. Benarroch

Galapagos Islands, Ecuador, Sep 14 (EFE).- No one knows exactly how or when it arrived on the Galapagos Islands, but the aggressive blackberry has spread far and wide on this Ecuadorian archipelago, poses a threat to flora and fauna and appears to be here to stay.

Found particularly at higher elevations, that plant apparently brought in the 1970s or 1980s to those islands located 1,000 kilometers (620 miles) off Ecuador’s coast has become a veritable menace to endemic species.

“On the (South American mainland) it’s a species in its natural state and has other (species) it competes with, so it doesn’t become so aggressive. But the problem on Galapagos is that when it was introduced it didn’t have any competitors and took over an empty ecological space,” Diego Ortiz, an ecology and molecular biology researcher at Universidad San Francisco de Quito, told Efe.

The coordinator of the “Barcode Galapagos” citizen science project, which for the past year has been collecting samples of soil and water containing the DNA of land and marine species to make an inventory of the flora and fauna of those remote volcanic islands, Ortiz said the blackberry plant completely covers the ground in the areas where it spreads.

“It creates a blanket on the surface and underground that prevents other endemic species from developing,” Ortiz added.

Of the four types of blackberries on Galapagos, the most widespread is “Rubus niveus,” a species native to southern Asia.

It apparently was introduced to the archipelago as an agricultural endeavor when people were unaware of its potential impact and before stringent biosafety measures were put in place to impede the entry of invasive species.

The Charles Darwin Foundation, based on Galapagos’ Santa Cruz Island, says the plant’s seeds remain viable in the soil for at least four years and are disseminated by rodents and birds that eat its fruit.

The biggest problem is the sheer number of seeds the plants produce – up to 7,000 per square meter, according to the Galapagos Conservation Trust.

But their impact on the ecosystem extends far beyond soil “conquest,” agricultural development or the displacement of other species of flora.

The blackberry plants also form a thick barrier for the passage of fauna due to their size (a height of more than 50 centimeters – 20 inches – and width of 120 cm), dense concentration and thorn-covered branches.

Among the affected species are Galapagos tortoises, which are known as “gardeners” because they defecate millions of intact seeds during their slow migration between different areas of the islands and thereby renew the different ecosystems.

“The blackberries obstruct the passage of animals and impede these ecological processes,” Ortiz said.

The researcher said he is aware that at this stage blackberry plants are virtually impossible to eradicate.

“It’s very difficult to combat the blackberry but with the ‘Barcode Galapagos’ project we’re establishing a knowledge base for future controls, studying the soil to see what bacteria are associated with this plant and to learn how we can reduce its impact,” Ortiz said of a plant that has carried out a hostile takeover of that archipelago in a span of just three decades. EFE


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