Don Quijote, the Wallenius Wilhelmsen vessel that regularly calls at Southampton as part of the port's highly successful vehicle import and export trade, is taking part in a vital test programme aimed at improving the marine environment.

It is estimated that at any one time there are up to 7,500 species of micro-organisms in a ship's tank of ballast water which, when discharged, could have a potentially damaging effect on the surrounding ecology.

Now equipment has been installed on Don Quijote which has been designed to cut back on the spread of invasive species from one area to another.

A spokesman for Wallenius Wilhelmsen, a global specialist in the shipping of vehicles, said: "When a vessel discharges ballast water from distant shores, it may release micro-organisms that are hostile to the native marine ecology.

"The result can be devastating to local species and the fishing industry so as part of our efforts to combat these threats, we are currently testing several ballast water treatment methods on our vessel, Don Quijote, to determine which is the most effective.''

One of Wallenius Wilhelmsen's newest vessels, the 57,112-ton Undine, the latest in a series of 11 sister ships ordered during the 1990s, called at Southampton a few days ago.

Delivered from the Daewoo shipyard in Korea in January of last year, Undine is able to carry up to 5,890 cars and has a length of 199 metres.