Sea Environment in Yokohama

Before the high economic growth, coastal fisheries and seaweed cultivation were active in the sea of Yokohama, and the scenery of seaweed drying was seen in various places.
Later, during the period of high economic growth, the close relationship between the sea and rivers and people's lives was lost, and at the same time, the water quality deteriorated due to the inflow of domestic wastewater and industrial wastewater.
The water quality of Yokohama Port has improved significantly due to the development of public sewers and regulations on factory drainage, but in recent years it has been flat, and issues such as red tide, an oxygen sea area, and odor generation remain.

Red tide is a phenomenon in which seawater discolors due to abnormal growth of plankton. When the ocean is polluted and nutrients such as phosphorus and nitrogen increase in the sea, plankton increases abnormally due to temperature and other effects. Seawater may turn reddish brown or orange due to the growth of plankton, and sometimes turn blue-green. This kind of plankton is called red tide plankton.