Paula Frasson / InaturalistThe common water hyacinth reduces fish populations by blocking sunlightPaula Frasson / Inaturalist
The water hyacinth (Pontederia crassipes), an aquatic plant commonly found in the South American basins of the Amazon River and the Rio de la Plata, is the most widespread invasive species in the world, according to a report by the UN’s Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). In Lake Victoria, East Africa, the plant blocks sunlight and prevents oxygenation of the water, annihilating populations of tilapia, an important fishing resource. In addition to exporting species, the Americas also suffer invasions. “One example is Limnoperna fortunei — the golden mussel,” says Ricardo Pinto Coelho, a retired biology professor from the Federal University of Minas Gerais, now the owner of RMPC Meio Ambiente Sustentável and the only Brazilian on the IPBES panel of experts. “In Brazilian waters, these mussels cause problems for aquaculture and the functioning of industrial operations when they become encrusted in refrigeration systems.” Another example: the mosquito Aedes aegypti, originally from Africa, transmits the viruses that cause dengue, Zika, and other diseases. The report states that human activities have resulted in the spread of more than 37,000 species of plants, animals, and microorganisms, playing a central role in 60% of global extinctions. In 2019, the global economic cost of invasive species exceeded US$423 billion annually (ipbes.net, September 4).
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