The effect of tube trap structure on sampling efficacy and accuracy for golden mussel, Limnoperna fortunei

抄録

The study was conducted to identify the effect of different types of tube traps on the sampling efficacy and accuracy for invasive golden mussels, Limnoperna fortunei (Dunker, 1857), at four sites in Japan. The traps consisted of PVC tubes (diameter: 5.5 cm; length: 20 cm) inside which a PVC plate was fixed horizontally as settlement substrate, and we examined two trap characteristics: mesh covering at the tube ends (present or not) and substrate texture (even or uneven). Mesh covering had a negative effect (P<0.001) and uneven substrate had a marginally positive effect (P=0.08) on mussel settlement density. A positive relationship was found between larval and settlement density in traps without mesh. These results imply that the most effective type of tube trap had no mesh covering and used uneven substrate. The settlement density of the mussels was also examined on several surfaces of the tube trap and the rope used to suspend the trap. The mussel density on the rope was higher than that on the PVC plates and tubes. The best correlation between settlement density and larval density occurred on the outside of the PVC tubes.