MARE researchers confirm for the first time the presence of the Eastern mosquitofish in the Madeira Archipelago
A team of scientists, including MARE researchers Inês Órfão, Manuel Biscoito, João Canning-Clode, and Filipe Ribeiro, has confirmed for the first time the presence of the Eastern mosquitofish (Gambusia holbrooki) in the Madeira archipelago. The results were recently published in the scientific journal BioInvasions Records and represent an important milestone in understanding the threats affecting the archipelago's freshwater ecosystems.
The Eastern mosquitofish, a small freshwater fish native to the east coast of the United States, is currently considered one of the most problematic invasive species worldwide. Introduced in several countries throughout the 20th century with the aim of controlling mosquitoes, this species has spread widely due to its high adaptability and reproductive capacity.
Although there are old reports suggesting its presence in Madeira, this species had never been formally identified. The study, led by Inês Órfão, combined morphological and genetic analyses of specimens collected from artificial urban lakes on the island of Madeira and a section of river in Porto Santo, confirming that it was Gambusia holbrooki.
According to the article, the species has been present in Madeira for several decades, but its arrival in Porto Santo is more recent and may be associated with the accidental escape of fish kept for ornamental purposes, as happened in the Azores archipelago.
It is a generalist omnivorous predator, capable of consuming zooplankton, insect larvae and young fish. Its ability to tolerate environmental variations, combined with a rapid reproductive cycle, can lead to a drastic reduction in native species, altering food webs and compromising the ecological quality of water bodies.
‘Unlike continental regions, freshwater ecosystems have fewer species, some of which are unique and only exist on these islands,’ researcher Inês Órfão points out in an interview with the Público newspaper. ‘If a species affected [by the eastern mosquitofish] is endemic, it may suffer a significant reduction and, in extreme cases, lead to its extinction.’
The eradication of invasive species in island ecosystems is a complex process that requires continuous investment. The research team stresses that preventing new introductions and early detection of dispersal hotspots are the most effective strategies.
The study also highlights the importance of awareness campaigns on the accidental or deliberate introduction of exotic fish into lakes, streams and other bodies of water, a practice that continues to contribute to the spread of invasive species in Portugal.
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Written by Patrícia Carvalho