Dr Belinda Gallardo, chief scientist of the Ecological Restoration Research Group at the IPE-CSIC, has spent 12 years studying the perfect storm that is the combined effect of biological invasions and climate change. She is an advocate of ecological restoration, which seeks to restore ecosystems in a holistic way. And she has a positive message: prevention and early detection work. But action is needed. And now.
The childhood of Belinda Gallardo (Soria, 1982) was marked by Mount Valonsadero, the Pita beach, and the canyon of the river Lobos. And also conversations with her uncle about the countryside and meteorology. She remembers her visit to Ordesa National Park (Huesca), at the age of 17, as a kind of revelation. It was there that she knew she wanted to study environmental sciences, which she did at the University of Salamanca. Then came her thesis on the ecological restoration of rivers, at the Pyrenean Institute of Ecology (IPE-CSIC), where she would eventually obtain her position as head scientist in 2020.
As usual, she has travelled a long way in her scientific career: a postdoctoral contract at the Department of Zoology of the University of Cambridge, where she started working on aquatic invasive species with David Aldridge; then back to Spain to join Montserrat Vilà’s group at the Doñana Biological Station (CSIC). “She is one of the world’s leading experts on biological invasions,” Gallardo recalls. And finally, a Ramón y Cajal contract, “an almost indispensable requirement to stabilise scientific work.”
“There is a lack of coordination between administrations and with the scientific community. Invasive species don’t understand jurisdictions or borders and they continue to spread while we clarify our positions.”
Dr Gallardo is chief scientist of the Ecological Restoration Research Group at the IPE-CSIC and coordinates the group of the same name born from the collaboration between the CSIC and the University of Zaragoza. For 12 years she has been studying the perfect storm that is the combined effect of invasive species and climate change. “They are not independent phenomena; they feed off each other,” she says. The increased frequency of major storms and floods contributes to the spread of the common reed (Arundo donax), which has replaced the original riparian forest of poplar and tamarisk; it has very little soil retention capacity, so it is washed away by flooding, aggravating its consequences. Just as the tropicalization of the Mediterranean favours the expansion of species from the Red Sea, such as lionfish and rabbitfish, which devastate the native fauna.
“Particularly worrying is the spread of aquatic plants that affect water supply, such as the water hyacinth in the Guadiana River. And also pyrophytic terrestrial plants such as eucalyptus, cat’s tail, Pennisetum and pampas grass, which produce dry biomass that is easily flammable, and regenerate quickly after a fire, dominating recently burned areas,” says Gallardo. “We are entering a vicious circle in which climate change favours the transport and establishment of invasive species, which in turn exacerbate the effects of climate change,” she warns, noting the paradox: while the most vulnerable native species are unable to cope with climate change, invasive species “are doing wonderfully well.” Her group has found that they can spread 100 times faster because of their high tolerance, their ability to feed on whatever is available, and because people move them, deliberately or accidentally.
“Research careers are long, uncertain and often precarious, but they are becoming increasingly diversified. One can do a doctoral thesis and then choose various pathways: technical, public outreach or project management.”
For Gallardo, throwing in the towel and letting the invading organisms take over is not an option because of their unexpected effects. Nor can they simply be eradicated, which is a losing strategy in the long run. “They often grow back.” The solution, she says, is ecological restoration, which aims to restore the ecosystem in a comprehensive way, strengthening its ability to resist new invasions. It requires cooperation, communication and awareness-raising, both between countries and internally. “In Spain we have a good legal framework, but we need to improve coordination between administrations and with researchers,” she says.
According to the report by the Intergovernmental Panel on Biodiversity and Ecosystem Services (IPBES), there are more than 37,000 species established outside their native range in the world; they are growing at a rate of 200 new species every year; they are involved in 60% of the extinctions of native species, especially on islands; and they cause economic costs of $423 billion a year.
“Only about 3,500 alien species are highly damaging. The Spanish Catalogue of Invasive Species lists about 200,” says Gallardo. “In most cases, they accumulate in disturbed areas of low value, favoured by the lack of competitors and predators and the abundance of nutrients from human activities,” she explains. But they move and end up in areas of high ecological value.
“We want to apply new technologies such as AI to the collection, curation and study of aquatic invasive species. We have just been awarded an innovative European project (GuardIAS), through which I hope to make progress in this area.”
A study led by IPE-CSIC and published in Nature Communications analyses the exposure of European habitats to the impact of 94 invasive animal and plant species, and identifies critical regions for conservation. It predicts an increase of between 22% and 132% in the areas affected in Europe, although its conclusion gives cause for some optimism: impact hotspots—which combine high ecological value with high exposure to the most damaging invasive species—represent a small fraction. “These are the areas where we have the most to lose, and where we urgently need to focus our monitoring and management efforts,” says Gallardo.
The expert argues that the problem is another consequence of globalisation and is therefore unstoppable, but she does not believe that all is lost: “Prevention and early detection plans work.” In a recent paper published in Nature Ecology & Evolution entitled “Curbing the major and growing threats from invasive alien species is urgent and achievable”, IPBES report coordinator Helen E. Roy describes biological invasions as an urgent but manageable problem. “Our research suggests that the areas of high ecological value affected are still limited, but are expected to increase in the future. Now is the time to act,” stresses Gallardo.
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