Impact of biological invasions in Europe

In the Science article Will threat of biological invasions unite the European Union? Philip E. Hulme, Petr Pyšek, Wolfgang Nentwig and Montserrat Vilà write:

Even the crudest estimate of total known monetary impact of alien species in Europe is close to €10 billion (about U.S. $13 billion) annually (European Commission, Towards an EU Strategy on Invasive Species; COM(2008) 789, EC, Brussels 2008). This figure is an underestimate, as potential economic and environmental impacts are unknown for almost 90% of the alien species found in Europe.

I checked Towards an EU Strategy on Invasive Species and this report refers to another report [Kettunen, M., Genovesi, P., Gollasch, S., Pagad, S., Starfinger, U. ten Brink, P. & Shine, C. 2008. Technical support to EU strategy on invasive species (IS) - Assessment of the impacts of IS in Europe and the EU (Final module report for the European Commission). Institute for European Environmental Policy (IEEP), Brussels, Belgium. 40 pp. + Annexes, May 2008, (DG ENV contract)] that I am unable to find using Google and searching the IEEP. But the summary in Towards an EU Strategy on Invasive Species indicates that the €10 billion is not the "total known monetary impact of alien species in Europe" but only their costs (such as eradication and control, agricultural and forestry damage, loss of commercial fisheries, damage to infrastructure and damage to human health). Total impact should include the benefits of invasive species.

Costs of a specific agency such as [the proposed] European Centre for Invasive Species Management, if run on a budget similar to European Centre for Disease Prevention and Control's, would amount to less than 0.5% of the annual cost of biological invasions in Europe but could bring much greater dividends to the European economy and environment.

Could.

[Update: Rodolphe E. Gozlan and Adrian C. Newton make the same point.]