Propagation Characteristics of Ulva sp. and Laver in the Yatsu Tidal Flats in Inner Tokyo Bay

Abstract

The Yatsu Higata wetland is one of the most significant tidal flat areas remaining in Japan. Although the site was officially recognized as an important wetland for migratory bird species in 1993 when it was registered as the Ramsar Convention, the extraordinary growth of Ulva sp. (sea lettuce) in recent years has severely impacted the ecology of the area and has resulted in the widespread death of benthic organisms such as clams and sandworms. Conversely, the crop of laver has decreased along the periphery of the tidal flat area.. This study examined the underlying causes of the increase and decrease in the crops of Ulva sp. and laver populations in the field, respectively. In addition, numerical simulations were performed to estimate the flow movement of Ulva sp. circulating in the inner Tokyo Bay area.