Eichhornia crassipes chemical warfare: debate rekindles in Portugal
Cristina Yuste/EFEverde for Lifeinvasaqua.-
The control of the Eichornia crassipes, in which Spain has invested 35 million euros since 2005 and which in Portugal mobilizes equally important economic and human resources, has rekindled the debate in the neighboring country about the convenience of using chemical products.
For the moment, there is no herbicide registered or authorised for use in the aquatic environment, recalls the Guadiana Hydrographic Confederation (CHG), and the natural product patented by the University of Extremadura (Spain) “is not suitable” for the shallot, which it only weakens and leaves floating, which also forces its withdrawal.
Filipe Banha, a researcher at the University of Évora, told EFEverde that in Portugal, the use of chemicals in water is not permitted either, and although this possibility “can be studied in an area where there is no aquatic fauna, the current can carry the glyphosate and generate an impact downstream.
However, “this invasion can be controlled,” he stressed, and in this particular area the rain could wash away a lot of biomass, “although periodic manual collection campaigns would be necessary on the riverbanks.
Use of herbicides
Representatives of economic sectors that depend on riverbanks or waterways in Portugal speak of losses in the millions in areas where the density of the Eichhornia crassipes prevents navigation or fishing and makes it difficult to remove it by mechanical means.
For these professionals, one cannot wait for rain and increased river flow, “one must be proactive” and reach a scientific consensus on the convenience of using chemical products.
The Raia River runs through the municipality of Mora, in the Portuguese Alentejo, a star destination for sport fishing and water sports and whose beautiful river beaches are a key tourist resource for the region’s economy.
Its mayor, Luís Simâo, faces “a problem of great magnitude” due to the invasion by Eichhornia crassipes a few meters away from the municipality, which gradually rises the river.
“We need a scientific entity to advise us on how to fight this plant, which can no longer be removed with machines, and it has been more than proven that there are herbicides on the market that can kill it, although from the environmental point of view, some are more recommendable than others,” he said.
Luis Lucas runs the aquatic activities company Azenhas da Seda, which offers rapids descent on the Raia and has been forced to change its schedule because of the Eichhornia crassipes; “some of our activities used to end here, at the Furadouro dam, and now we have to work further upstream”.
“The Eichhornia crassipes has already overtaken one of the rapids and if it continues to rise we will have a huge problem on the river beach, in the Mora Fluviary and in the very dam that feeds the riverbank and we could lose the business”, he said.
Eichhornia crassipes: an invasive exotic
Eichhornia crassipes is native to South America and, although it was first detected in the Iberian Peninsula in 1987, it was not included in the Spanish catalogue of invasive alien species until 2011, which facilitated its trade and transport without restrictions.
According to the CHG, the plant was widely used as an ornamental species in aquaculture and gardening, so it is most likely that it was deposited in the river by a private individual, although its seeds may also have been mixed with imported rice seeds.
Eichhornia crassipes has been on the European list of invasive alien species since 2016, and its introduction, reproduction, cultivation, transport, purchase, sale, possession or release, whether intentional or through negligence, is expressly prohibited.
It is “a great competitor, no other aquatic plant survives in these conditions of lack of light,” said Filipe Banha, and the lack of oxygen displaces the native fauna in favor of some invasive species that, because of its great capacity for survival, manages to thrive in these conditions.
For José Nuncio, president of the Sorraia Valley Irrigation Association, the only solution is to use chemicals; “if it rained a lot, the water would clean the area and carry the plant downstream, but there would be bulbs left that would return the problem.
Raising awareness to prevent
Felipe Banha has insisted on prevention as the best way to avoid similar situations and prevent the introduction of invasive alien species “through ignorance or accident”.
And in this sense, he has put into value dissemination and awareness initiatives such as Life Invasaqua, a project financed by the European Union, coordinated by the University of Murcia and in which the EFE Agency and various scientific entities from Spain and Portugal participate.
Life Invasaqua is coordinated by the Universidad de Murcia with the participation of 8 partners: EFEverde of the Agencia EFE, UICN-Med, Museo de Ciencias Naturales-Centro Superior de Investigaciones Científicas, Sociedad Ibérica de Ictiología (SIBIC), Universidad de Navarra, Universidad de Santiago de Compostela, Universidad de Évora and Associaçao Portuguesa de Educaçao Ambiental (ASPEA)
About LIFE17 GIE/ES/000515 Life Invasaqua of the EU “Invasive alien species in freshwater and estuarine systems: awareness and prevention in the Iberian Peninsula”
Co-financed by the EU within the framework of the Life initiative and coordinated by the University of Murcia, LIFE INVASAQUA aims to contribute to the reduction of the harmful impacts of INVASIVE ALIEN SPECIES (IES) on biodiversity by raising public awareness, increasing training in the sectors involved and creating tools for an efficient early warning and rapid response system (EWRR) to manage their impact on freshwater and estuary ecosystems.