Abstract
We ascertained that the sedimentation and decomposition of Ulva sp. (Green algae) affect the Manila clam (Ruditapes philippinarum) resources on the basis of the field experiment in the Wajiro tidal flat at Hakata Bay. We also verified the effectiveness of Ulva salvage measures for the preservation of the resources from the calculation of the Ulva growth model.
According to the field investigation of the survival of the Manila clam, it was confirmed that the Manila clam dies when Ulva decomposes under anaerobic condition and sulfides are produced. In 2007, the amount of natural resources of the clam markedly decreased with the decomposition of Ulva. During the sedimentation and decomposition of Ulva, it was found that for the survival of the clam, a net setup on the ground in the shape of a roof is effective. From the result of calculation using Ulva growth model, as well as the quantity of salvage of Ulva, the quantity of decomposed Ulva decreased, when the salvage was started early. It was shown that the early salvage was an effective preservation measure for Manila clam resources.
