Photo : Ministry of the Environment

## 5 Changes in the Natural Environment

The tsunami and other catastrophe situations caused by the Great East Japan Earthquake substantially altered the natural environment on the Pacific coast of the Tohoku region. An analysis of the coastal range inundated by the tsunami (extending from Misawa-City, Aomori Prefecture to Kitaibaraki City, Fukushima Prefecture) and a vegetation map (National Survey on the Natural Environment by the Ministry of the Environment) suggests that most of the inundated lands were either arable (54%, or 25,646 hectares) or urban (30%, or 14,375 hectares). Natural vegetation along the coast was also affected, and includes: (1) Japanese black pine and red pine plantations (5%, or 2,501 hectares); (2) vegetation in marshlands, rivers, and ponds (2%, or 942 hectares); (3) secondary grasslands (2%, or 887 hectares); and (4) dune vegetation (1%, or 657 hectares).

The severity of the impact seems to have varied according to the location. For example, although the overall situation has not yet been fully understood, seaweed or algae beds (including brown seaweed and kelp, which grow directly on bedrock) disappeared in some locations, while other

Photo: Ministry of the Environment

locations suffered virtually no impact. It is thought that seaweed or algae beds such as eelgrass (which grows in sandy areas) disappeared with the impact in most areas and shrunk significantly in others. On the other hand, some eelgrasses have been found that are thought to have sprouted from seeds after the tsunami. There are some areas where fish habitat density in the eelgrass beds is reduced, but there are insignificant changes in the number of species. It is therefore necessary to carry out long-term monitoring of the recovery progress of eelgrass in the coming years.

With 1,000 eelgrass bed monitoring sites, Funakoshi Bay, Iwate Prefecture, was selected for a continuing study by the Ministry of the Environment. The ocean area shown in the photo had been covered with six-meter-tall eelgrass before the tsunami. However, most of it disappeared after

Figure 2-3-2 Change in the Number of Species of Benthic Animals Appearing on Dry Beach along the Pacific Coast in the Tohoku Area

(Left photo taken sometime between 1984 and 1986; right photo taken March 12, 2011.)

Photo: Geographical Survey Institute

the tsunami, leaving scattered eelgrass with heights of a few dozen centimeters.

Mudflat distribution was observed on the southern coasts of Sanriku, particularly in areas where the coastline is deeply indented, in closed sections of the bay, in Matsushima Bay, and on the coast of Sendai Bay. Most of these areas were also damaged by the tsunami, which modified geological formations. Some mudflats continue to change their configuration, while the species composition in others has significantly changed due to modifications in bottom sediment. In addition, some mudflats are no longer above sea level due to sinking caused by the earthquake, and some sand beaches have disappeared or narrowed. The sand beach between this mudflat and the ocean disappeared after the mudflat was buried with earth and sand. The geologic formation of the Gamou Mudflats, in Miyagi Prefecture, is significantly changing even now.

Sanganjima and Hidejima islands off the Sanriku coast are known as breeding grounds for treasured seabirds, including the Madeiran Storm Petrel (designated as critically endangered by the Ministry of the Environment) and the vulnerable Swinhoe's Storm Petrel. Today, seabird breeding is taking place as usual, since the breeding season did not overlap with the earthquake and tsunami, and the breeding grounds suffered virtually no direct effects. However, changes in the feeding environment for these species are expected to be ongoing, making it necessary to carry out careful monitoring in the future to identify the effects on migrant birds and others using the mudflats.

## Section 4 The Situation of Radioactive Contamination and Responses to the Nuclear Power Station Accident

Massive amounts of radioactive materials were released into the environment as a result of the accident that occurred at TEPCO Fukushima Daiichi NPS, and on April 12, 2011, this severe accident was temporary evaluated as being Level 7 by the central government according to the International Nuclear Event Scale (INES).

Japan's government summarized the "Report of the Japanese Government to the IAEA Ministerial Conference on Nuclear Safety – The Accident at TEPCO's Fukushima Nuclear Power Stations" (June 2011) on radioactive contamination caused by the accident at Fukushima Daiichi NPS, and in the same month reported to the Ministerial Conference on Nuclear Safety held at International Atomic Energy Agency (IAEA).

"This nuclear accident has turned out to be a major challenge for Japan," said the report to the IAEA, "with numerous relevant domestic organizations working together to respond to the situation while also receiving support from many countries around the world. The fact that this accident has raised concerns around the world about the safety of nuclear power generation is a matter which Japan takes with the utmost seriousness and remorse. Above all, Japan sincerely regrets causing anxiety for people all over the world about the release of radioactive materials." As the report states, the large-scale environmental contamination brought about by radioactive materials discharged into the environment following the accident is a cause for major concern, not only for our Japanese homeland, but also for countries around the world.

This section primarily describes the response to