Burrowing activity of Procambarus clarkii on levees: analysing behaviour and burrow structure

The North American crayfish Procambarus clarkii is considered among the most invasive freshwater species. However, burrowing behaviour and the possible impact of P. clarkii on levees have not yet been studied in depth. To assess shape, volume and structure of its burrows and the associated behaviour, experiments were conducted introducing two size-matched adult crayfish into an artificial setup and video-recording their behaviour for 96 h. At the end of each replicate, casts of excavated burrows made with polyethylene foam were retrieved. Crayfish (n = 40) dug 17 burrows, six of which having an enlarged terminal chamber. The average excavated levee volume of burrows was 1.9% (0.00528 m(3); 5.0256 l) +/- 0.86% of the total volume with a maximum of 4% (0.0109 m(3); 10.9 l) and the chambers (mean volume of 0.9 +/- 0.6 dm(3)) contributed to up to 50% of the excavated volume. No significant difference between sexes was found for any observed behaviour. Our study also demonstrated how P. clarkii female and male behaviours are similar for burrowing activity. As a result, we quantify the potential pressure exerted by the red swamp crayfish on levees and lastly highlight the observation of cooperating burrowing behaviour of male and female individuals in this species.