Estimating survival rates of quagga mussel (Dreissena rostriformis bugensis) veliger larvae under summer and autumn temperature regimes in residual water of trailered watercraft at Lake Mead, USA

摘要

On 6 January 2007, invasive quagga mussels [Dreissena rostriformis bugensis (Andrusov, 1897)] were discovered in the Boulder Basin of Lake Mead, Nevada, a popular site for recreational boating in the southwestern United States. Recreational watercraft are considered a primary vector for overland dispersal of quagga mussel veliger larvae between water bodies. Thus, effective decontamination of veligers in residual water carried by trailered recreation boats is critical to controlling this species’ spread. The survival rate of quagga mussel veligers was measured during exposure to environmental temperature conditions mimicking those experienced in the residual water of trailered vessels during warm summer and cooler autumn months in the semi-arid southwestern United States. Under warm summer conditions, quagga mussel veligers survived approximately five days while under cooler autumn conditions they survived 27 days. When tested under autumn temperature conditions veliger survival times increased with increased level of larval development. The results suggested a greater likelihood of veliger transport in the residual water of trailered watercraft during autumn months. The results indicated that presently recommended vessel quarantine times to kill all externally attached juvenile and adult dreissenid mussels prior to launching in an uninfested water body should be increased to generate 100% veliger mortality in residual water unable to be fully drained from the internal areas of watercraft.