Look out for Aliens beneath the waves!

An army of marine species, alien to UK coastal waters, have hitchhiked around the globe thanks to activities such as aquaculture, recreational boating and shipping. The 'Marine Aliens' consortium is now appealing for help from the British public to hunt down and identify these invaders, reports Jeremy Garwood.

The 'Marine Aliens' consortium is a collaboration of five UK research institutes and university departments whose overall objective is to provide information on invasive species biology and distribution. Their aim is to protect indigenous species and ecosystems from the impacts of various non-native marine invaders. However, this requires a better understanding of the rates and methods of alien dispersal, and how they impact on the local environment. This is why the public are now being asked to help detect and halt the spread of these unwanted newcomers.

"While exotic plants and animals like rhododendrons and grey squirrels are obvious in the British Isles, beneath the waves a hidden invasion of non-native species is taking place around our shores," says Professor Maggs from Queen's University, Belfast. "Many marine aliens have left their natural enemies behind and may compete with native species, with potentially disastrous consequences for aquaculture, tourism and other marine activities."

However, by reporting what they see to marine scientists, everyone can deal with this "biosecurity" threat, especially those who use a boat or visit estuaries and the seashore.

Biological invasions in the marine environment occur when organisms move beyond their natural range, arriving in completely new territories where they impact upon indigenous species, producing significant changes in the composition of the native community. In UK waters, about 60 established non-native marine species have been identified, most of which are also invading other European coasts.

Although the problem of invasive species has existed on a global scale for millennia, it has only really gained attention during the last twenty years. Historically, natural barriers such as rivers, oceans and climatic conditions, have provided the isolation essential to allow unique species and ecosystems to evolve but globalisation and growth in commercial trade and tourism have rendered these natural barriers ineffective. Consequently, species have been able to travel vast distances to new habitats where they can become 'biological pollution'.

Some invasive species can have a detrimental effect on the environment into which they are introduced. These effects can range from the displacement of native plants and animals as a result of competition for space, light and food, to a more direct effect where some introduced species actually prey on local wildlife. 'Alien invasions' are the second most important threat to loss of biodiversity after habitat destruction.

The Marine Aliens study is particularly concentrating on the spread and risks posed by seven alien species, three algae ("Green sea fingers", "Wireweed" and "Wakame"), a "leathery sea squirt", the "Japanese skeleton shrimp", "Chinese mitten crab" and Perophora japonica, a "colonial sea squirt". All of these non-native species originate from coasts around Japan, Korea and North China, and were transported by ships, whether in ballast water or as hull fouling. A guide on the Marine Aliens website (www.marlin.ac.uk/marinealiens) helps the public identify these non-native species. If the reporting system functions well, it will highlight new invasions and monitor the spread into new areas.

Nevertheless, there is also a need to develop measures to control these alien species and to limit human activities linked to their introduction and spread. Hence, the need to raise public awareness and understanding of the issues and to provide advice to organisations that are responsible for implementing Biodiversity Action Plans and who try to protect scheduled species and manage marine-protected areas. .