Dr. Jaimie Dick presented his predictions at the British Ecological Society's Winter Meeting at the University of Birmingham on Friday (January 5).

Dr. Dick's results indicate that the voracious shrimp, Dikerogammarus villosus, will have a severe impact on the areas it invades, causing local extinctions and reducing biodiversity.

It has already invaded the Netherlands and other parts of western Europe, driving out both the native shrimp, Gammarus duebeni, and previously successful invaders such as the North American G. tigrinus.

Dr. Dick studied the impact of D. villosus on a wide range of aquatic species through a series of microcosm experiments in which he set up three types of large aquarium: the first with no shrimps, the second containing the native G. duebeni and the third with D. villosus.

His results show that the invader is a much more deadly predator than the native shrimp, perhaps partly due to its much larger and more powerful mouthparts.

Compared with the native G. duebeni, Dr. Dick found that D. villosus killed and maimed much larger numbers of the aquatic species in its tanks, including water hoglice, blue-tailed damsel flies, fish leeches and water boatmen.

D. villosus kills its victims by biting and shredding them. According to Dr. Dick, "Unusually, water hoglice were killed and eaten without having moulted and thus become soft-bodied, and water boatmen, despite being winged and hard-bodied, were preyed on by D. villosus and often severely bitten."

Unlike G. duebeni, which did not harm the fish leeches or damsel flies in its tanks, D. villosus killed and ate them in large numbers. D. villosus is a particularly successful invader because it can tolerate changes in water temperature, oxygen levels and salinity, is not fussy about what it eats and breeds rapidly.

The Ponto-Caspian region -- made up of the Caspian, Black and Azov sea basins -- is an invasion "hot spot," and many species from the area have already invaded parts of western Europe as well as North America.

The invaders are being transported around the world on board international shipping, where they stow away in ballast water taken on board in the Ponto-Caspian and are discharged thousands of miles away.

The British Ecological Society is a learned society, a registered charity and a company limited by guarantee. Established in 1913 by academics to promote and foster the study of ecology in its widest sense, the Society has 5,000 members in the UK and abroad.

(Editor's Note: The abstract of this paper is available on the web at this URL.)

[Contact: Dr. Jaimie Dick, Becky Allen]

07-Jan-2001