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Study identifies 66 alien plant and animal species that pose greatest threat to European biodiversity

Golden mussel © Nicolas Olejnik

Northern Snakehead © George Berninger Jr., appears on Commons Wiki

Plant and animal species that would pose a threat to biodiversity should they arrive in the European Union have been identified in a research project, which a University of Sussex academic was a part of.

From an initial list of 329 alien species recently published by the EU, scientists have derived and agreed a list of eight species considered to be very high risk, 40 considered to be high risk, and 18 considered to be medium risk.

Dr Alan Stewart, Reader in Ecology, was part of the study led by Professor Helen Roy of the UK’s Centre for Ecology and Hydrology. While Dr Stewart focused on insect and other terrestrial invertebrate species, others from across Europe and funded by the European Commission focused onplants, marine species, freshwater invertebrates and vertebrates.

Dr Stewart said: “All of these species have caused significant problems in other parts of the world and many have the capacity to induce radical changes in the structure and composition of whole ecological communities.”

A total of 43 researchers from across Europe were involved in the study which used a horizon-scanning approach to derive a ranked list of potential invasive species. Using this procedure, they worked collaboratively to reach consensus about the alien species most likely to arrive, establish, spread and have an impact on biodiversity in the region over the next decade.

The approach is unique in the continental scale examined, the breadth of taxonomic groups and environments considered, and the methods and data sources used.

The study, to be published in the journal Global Change Biology on 13th December, identified the following eight species as those that pose the highest risk:

  1. Channa argus. The northern snakehead is a species of fish native to southern and eastern China but is now also widely distributed in Japan within shallow, marshy ponds and wetlands, where it preys on native fish species.
  2. Limnoperna fortunei. The golden mussel is native to China and south-eastern Asia but became established in Hong Kong in 1965, and Japan and Taiwan in the 1990s. Subsequently, it invaded the United States and South America. It alters native fauna with an impact on the freshwater food web.
  3. Orconectes rusticus. The rusty crayfish, native to the United States but now found in Canada, is a large and aggressive species of freshwater crayfish, which is more successful in deterring attack from predators than other crayfish and therefore outcompetes native species.
  4. Plotosus lineatus. The striped eel catfish is native to the Indian Ocean but was first recorded in the Mediterranean in 2002 and subsequently spread rapidly along the entire Israeli coast. This venomous catfish now inhabits all sandy and muddy substrates contributing to species declines through competition and displacement.
  5. Codium parvulum. This green seaweed native to the Indo-Pacific Ocean and subsequently described from the Red Sea, has since been recorded off the northern shores of Israel in the Mediterranean and along the Lebanese coast. It is considered an ecosystem engineer, altering the structure and functionality of ecosystems.
  6. Crepidula onyx. The onyx slipper snail is native to the southern coast of California and northern Pacific coast of Mexico. It is now widespread and considered highly invasive in Asia where it has been reported from Korea, Japan and Hong Kong. Slipper snails are sedentary filter-feeders and change native ecosystems.
  7. Mytilopsis adamsi. The black striped mussel described from the Pacific coast of Panama is a brackish species that invaded the Indo-Pacific Ocean during the 1900s and has reached Fiji, India, Malaysia, Taiwan, Japan, and Australia. In some of these coastal areas the species completely dominates since it can survive extreme environmental conditions.
  8. Sciurus niger. The fox squirrel native to eastern and central North America, competes for resources with the native Western gray squirrel (S. griseus) and Douglas squirrels (Tamiasciurus douglasii).

Professor Helen Roy of the Centre for Ecology & Hydrology said: “Preventing the arrival of invasive alien species is the most effective way of managing invasions.

“Predicting which species are likely to arrive and survive in new regions involves considering many interacting ecological and socio-economic factors including climate but also patterns of trade. 

“Our collaborative approach involving experts spanning many disciplines has been critical to achieve the ranked list of alien species that pose the greatest threat to European biodiversity.”

In 2014, Dr Alan Stewart was involved in a previous study that conducted horizon scanning for invasive alien species with the potential to threaten biodiversity in Great Britain specifically.

Within just a few years, seven out of the ten species identified had arrived.

Dr Stewart said: “It’s important to remember that not all of the species listed in this new study will necessarily arrive in the EU, and if they do, not all of them will necessarily become a problem. 

“However, we have to consider the implications if they do, and think about potential coping strategies.

“Many of these species are likely to arrive due to human activity and globalisation. For instance, we found that many marine species are most likely to arrive in ships’ ballast water, while terrestrial invertebrates are most likely to arrive through international trade in plants or in packaging.”


By: Stephanie Allen
Last updated: Thursday, 13 December 2018

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