No abstract

International audienceClimate warming often leads to shifts in the strength and sign of agonistic interactions among species, which in turn may change their distribution ranges. Notwithstanding the ubiquity of this phenomenon, there is scant literature about how interspecific agonistic behaviour changes with altered thermal regime, especially for invasive species such as three widespread North American crayfishes in Europe (Orconectes limosus, Procambarus clarkii and Pacifastacus leniusculus). * We conducted a laboratory study to analyse some descriptors of agonistic behaviour in fighting dyads of similarly sized males of the three species' combinations, both at 20 °C (the current maximum water temperature in the study area, central France) and 27 °C (the maximum expected in the next 80 years under the more pessimistic IPCC greenhouse gas emission scenario). * The results showed significantly different responses to warming by the three crayfishes. At 27 °C, O. limosus spent more time motionless and P. leniusculus was more often the subordinate, independent of the opponent. On the contrary, the agonistic strategy of P. clarkii did not change with temperature: when engaged in fighting, this species outcompeted both O. limosus and P. leniusculus. * Caution should be taken when extrapolating laboratory studies to the field, but these results, combined with outputs of previous modelling exercises, suggest that European catchments will become dominated by P. clarkii with climate warming. Ultimately, this might lead to impoverished biodiversity, simplified food webs and altered ecosystem services

Key-words:Procambarus clarkii, fish-ponds, mark-recapture, population size estimationThe red swamp crayfish, Procambarus clarkii, was discovered in 2007 in the "Parc naturel régional (PNR) de la Brenne" (France). Ten colonized sites have been identified in the park to date, including two new sites discovered in 2011. The present study aims at establishing a protocol suitable for estimating the population size of P. clarkii by the use of a Capture-MarkRecapture (CMR) technique in a chain of five connected fish-ponds. Results show different cohorts of individuals among seasons and fish-ponds. However, trapping effort was not efficient enough to obtain an accurate estimate of the population size of this species in a fish-pond larger than 2−3 ha. On the other hand, the adopted protocol appeared useful to assess, in smaller fish-ponds, the effect of intensive trapping and other control methods on P. clarkii populations. RÉSUMÉEstimation de la taille de populations d'écrevisse de Louisiane (Procambarus clarkii) dans des étangs de pisciculture (Brenne, Central France)

No abstract