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Providing evidence to improve practice

Individual study: Evaluating stakeholder awareness and involvement in risk prevention of aquatic invasive plant species by a national code of conduct

Published source details

Verbrugge L.N., Leuven R.S., Van Valkenburg J.L. & van den Born R.J. (2014) Evaluating stakeholder awareness and involvement in risk prevention of aquatic invasive plant species by a national code of conduct. Aquatic Invasions, 9, 369-381


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Parrot’s feather: Reduction of trade through legislation and codes of conduct Control of Freshwater Invasive Species

A replicated, randomized, before-and-after trial between 2010 and 2012 in the Netherlands (Verbrugge et al. 2014) reported that the implementation of a code of conduct reduced the trade of aquatic plants banned from sale (group that included parrot’s feather Myriophyllum aquaticum). The number of batches of banned species found per store visited was higher in 2010 (prior to the implementation of the code of conduct; 0.72 batches/store visited), than in 2011 and 2012 (after the implementation of the code of conduct; 0.03 batches/store visited). Results were not subject to statistical tests. Number of addresses selling aquatic plants visited was 133 in 2010, 107 in 2011 and 76 in 2012. In addition to parrot’s feathers, species banned in the Netherland and counted during the study included Crassula helmsii, esthwaite waterweed Hydrilla verticillata,  floaring pennywort Hydrocotyle ranunculoides, water primrose Ludwigia grandiflora, creeping water-primrose Ludwigia peploides and variable-leaf watermilfoil  Myriophyllum heterophyllum. The code of conduct aimed to reduce the introduction and spread of invasive aquatic plants and was developed in partnership between the government and the horticulture sector.

(Summarised by Ricardo Rocha)