2014 Volume 27 Issue 3 Pages 41-50
ABSTRACT : An artificial tidal flat in Okinosu, Tokushima City, was created to compensate for the loss of a natural tidal flat; however, the ecological conditions of the benthic assemblage in the artificial habitat differ extensively from those in the natural habitat. In particular, the mud snail Batillaria cumingi, which dominated the lost habitat overwhelmingly, were found to be rare in the created habitat. In a previous study, we found that the amount of available food for B. cumingii (i.e., diatoms) was significantly lower in the artificial habitat; therefore, we enclosed the snails in both habitats and compared their growth rate to test a “food-limiting hypothesis.” However, we found no significant difference in growth rates or the abundance of food items between the two habitats. It is notable that significantly higher mortality and disappearance rates were observed for the snail only in the created habitat during the experiment. However, our additional experiment showed that the empty shells at the surface sank into the sediment significantly in the created habitat. Thus, we regard a “sinking event” as the main reason for the absence of the mud snail in the created shore.
