Abstract
An artificial tidal flat was created in 2007, to compensate for the loss of a natural tidal flat, at Okinosu, Tokushima City. However, five years after its creation, it was found that the ecological conditions in the artificial habitat of benthic animals differed vastly from those in the natural habitat, and that the abundance of benthic animals was much lower in the artificial tidal flat.
We propose that a “sinking event” is responsible for this phenomenon. Furthermore, we have determined that this sinking event is caused by bioturbation of ghost shrimp Nihonotrypaea japonica. Here, we undertook experiments to clarify the effect of N. japonica on the tidal-flat ecosystem. N. japonica generated coarse sediment grain sizes and decreased the abundance of benthic diatoms. Treatment with N. japonica exclusive led to a low-biodiversity assemblage—it is possible that, in places where N. japonica dominates, there is an increase in the abundance of only the organisms that parasitize N. japonica nests.