Abstract
We here report impacts of the 2011 great earthquake and tsunami on water quality and eelgrass beds in Matsushima Bay which locates on the coast of Miyagi Prefecture. The water quality of the bay was deteriorated due to severe damages of a sewage plant, but recovered rapidly after temporary repairs and start of primary treatment. This highlights that the temporary measure was significantly effective to improve the water quality deterioration caused by the disaster. Meanwhile, eelgrass beds of Matsushima Bay were severly damaged by the tsunami, and their total area decreased significantly. Even 2 years after the tsunami, eelgrass beds had not recovered. Our analysis based on a Habitat Suitability Index model indicates that the significant gound subsidence and consequent increase of water depth potentially hamper recovery of eelgrass beds in the bay. The recovery process of eelgrass beds in the bay needs to be monitored taking account of effects of other factors potentially affecting the competition between phytoplankton and eelgrass (e.g., nutirents, turbidity).
