The UK’s 14 Overseas Territories – many of them small, remote islands like St. Helena – are home to a variety of plant and animal species found nowhere else in the world. This makes them highly vulnerable to biological invasions that could lead to the extinction of their endemic species and irrevocably change their unique ecosystems.
Now, a team of researchers from the UK Center for Ecology & Hydrology (UKCEH) and Durham University, together with communities on the Overseas Territories, has assessed thousands of potential invasive species in order to estimate which are most likely to arrive and pose threats to the Territories within the next decade. Their findings could guide authorities, conservation ecologists, and the wider public to prevent these species from becoming established and causing ecological and economic damage.
“These Territories are exceptionally biodiverse. St Helena, for example, has over 400 invertebrates found nowhere else in world – it is simply unique. We hope that this study draws attention to these Overseas Territories and the inspiring people on them who are working so hard to protect their incredible wildlife and habitats,” said study senior author Helen Roy, an ecologist at UKCEH.
The analysis revealed that Gibraltar and St. Helena are threatened by biological invasion from the greatest number of species. While St. Helena is most at risk from invasion of plant species, the Falkland Islands and Tristan da Cunha are endangered by the most marine species. One of the species that could pose a threat to many of the Overseas Territories is the green mussel (Perna viridis), which can travel around the world on boats and ships, and form dense colonies in places where it establishes, outcompeting native species by reducing levels of phytoplankton. Other invasive species that pose a significant threat to many Territories include the little fire ant (Wasmannia auropunctata), the brown rat (Rattus norvegicus), and the mesquite tree (Prosopis juliflora).
“Preventing the introduction of invasive non-native species is key, because management of species that have established and spread is often extremely expensive and, in some cases, there are no options available. We hope that this list will help inform action, including supporting biosecurity activities, to safeguard the wildlife in these precious places,” Roy concluded.
The study is published in the journal Conservation Letters.
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