August 8, 2011


How Did the Great East Japan Earthquake Affect Ecosystems and Biodiversity?

Keywords: Newsletter 

JFS Newsletter No.107 (July 2011)

The Great East Japan Earthquake that occurred on March 11, 2011 caused tremendous damage to people's lives and the natural environment over a vast area, from the Tohoku region (the northeastern district of Japan) to the Kanto region (the area around Tokyo). A huge number of houses and buildings fell apart, and some 25,000 people lost their lives. Coastal areas including tidal flats, sea grass beds and maritime forests were also devastated. In the meantime, the crippled Fukushima Daiichi Nuclear Power Plant operated by the Tokyo Electric Power Co. (TEPCO) continues to release radioactive substances into the sea, the soil, and the air.

On June 28, 2011, a forum on the impacts of the Great East Japan Earthquake on ecosystems and biological diversity was held, led by the the Ecological Science Working Group, Integrative Biology Committee of the Science Council of Japan. It was based on the awareness that impacts on ecosystems and biodiversity which support primary industries such as agriculture, forestry, and fisheries have hardly been discussed at all, although various surveys and research projects have been conducted on impacts of the earthquake, tsunamis, and radioactive emissions on industry and human health.

This article introduces some excerpts from presentations at this forum that dealt with assessments of the extent of damage to ecosystems and biodiversity and future monitoring to be carried out with local experts.

Professor Keitaro Hara of Tokyo University of Information Sciences led off with a presentation titled "How Did the Great East Japan Earthquake Affect Ecosystems and Biodiversity? -- as seen from the results of satellite image analysis," in which he explained the situation in the affected areas using satellite images. (Here follows information from Prof. Hara's presentation.)

The Tohoku region, the main area affected by the earthquake and tsunami, has a straight coastline north of Miyako in Iwate and an extremely irregular and indented ria coast to the south. Then there are the Sendai plains, and a sand beach south of Ishinomaki, Miyagi. There are some lagoons like Gamou tidal flats, Idoura, and Hiroura dotted between the estuaries of large rivers such as the Kitakami River and the Abukuma River. Agricultural land, such as rice paddies and dry fields, as well as residential areas are located in the plains.

Before the earthquake, Rikuzentakata, Iwate, had a celebrated coastal protection pine forest, but the destruction left nothing but a single pine tree. This tree has become a symbol of the local society's reconstruction. Satellite images show that the tsunami had considerable effects on this area. The Kitakami River region was flooded up to tens of kilometers upstream from the river's mouth, and a vast reed bed there was affected badly. In the Wakabayashi and Miyagino districts of Sendai, coastal protection forests of Japanese black pine suffered catastrophic damage. In Soma, even inland farming areas around Matsukawaura lagoon were flooded.

Particularly in this area, very sensitive ecosystems such as tidal flats and marshes were damaged. Gamou tidal flat that extends around the mouth of the Nanakita River is said to be no longer brackish because of seawater flows that came in after the quake. According to a recent newspaper article, however, a group in Sendai found that creatures that lived there before the disaster are already coming back to the tidal flat.

The areas flooded by seawater suffer extensive salt damage, and must overcome great challenges if they are to again support agriculture and rice cultivation. The Great East Japan Earthquake caused disturbance over an area and on a scale that occurs rarely even over the course of a whole millennium. The Jogan Tsunami was occurred in ninth century in Japan, nearly a thousand years ago. And another 1,000 years before that, there was a tsunami on the same scale during the Iron-Age Yayoi period dating from 300 BC to 300 AD. The impacts of the 2011 Great East Japan Earthquake are as tremendous as those massive tsunamis, and we have not yet fully comprehended the mechanisms and impacts of this large-scale, wide-area disturbance.

The underlying problem behind the fact that we don't know much about the impacts is that we lack basic data. Basic natural environmental conservation studies [conducted by the government] in 1976 show some of the distribution of critical plant communities, but the availability of vegetation maps produced by the current round of basic natural environmental conservation studies is geographically limited. Spatial information technology has been contributing in various ways, including measuring tsunamis and changes in the Earth's crust with global positioning system (GPS), but unfortunately, the operation of "DAICHI," an Advanced Land Observing Satellite (ALOS) reached its scheduled end on May 12 and a replacement is not scheduled. DAICHI continued to send useful data for two months after the earthquake in Tohoku, but one of the major issues is that no data has been collected since then.

Next, Prof. Hiroyoshi Higuchi of Tokyo University introduced some very informative case studies of the Chernobyl nuclear disaster that will be helpful in examining the impacts of the Fukushima nuclear disaster, taken from his book entitled "Impact of Radioactive Contamination over Breeding, Existence and Distribution of Birds? World of Birds 25 years after Chernobyl Nuclear Accident." (Here follows information from Prof. Higuchi's presentation.)

In April 1986, an accident occurred at the Chernobyl Nuclear Power Plant. The crippled number four reactor exploded after melting down, releasing radioactive fallout on a very wide swath across Europe. Even now, no one is permitted to live within a radius of 30 kilometers of the plant. About 100 hot spots, highly polluted local areas, are being found scattered as far as 350 kilometers to the northeast of the plant. Any agricultural or livestock business activity is prohibited in these hot spots.

The explosion at the Chernobyl Nuclear Power Plant discharged a massive amount of radiation into the atmosphere, estimated 5.2 million tera becquerels. The release from the Fukushima Nuclear Power Plant Accident is reported to be 0.77 million tera becquerels, however, the plant is continuing to release less critical amounts of radiation. When we consider that the half-lives of Cesium-137, Strontium-90 and Plutonium-239 as 30 years, 29 years and 24,000 years respectively, we can expect this radioactive contamination to have a significant impact for a long time to come.

A research group called the Chernobyl Research Initiative led by Anders P. Moller and two other scientists is studying the impacts on biodiversity and ecosystems by looking at various biological communities that support spiders, locusts, dragonflies, bees, butterflies, amphibians, reptiles, birds and mammals. All communities exhibit population decrease trends that corresponds to higher radioactive contamination levels. Particularly remarkable trends are seen among birds and mammals.

Swallows were studied to determine the impacts on birds in the highly polluted area of Chernobyl. Among physiological effects, the blood and liver concentrations of antioxidants such as carotenoids, vitamin A and vitamin E were significantly reduced, resulting in increased abnormality of sperm and partial bleaching in impacted populations compared to those in control areas. Decreasing numbers of white blood cells and amounts of immune globulin as well as spleen volume were also observed, implying a decline in immune function.

According to a study on the breeding success and survival rates of swallows in the contaminated area and area more than 200 kilometers away from the Chernobyl plant, the number of non-breeding birds in the contaminated zone population was clearly higher, while egg clutch size, the number of chicks and hatching rate were also predominantly lower. In looking at the link with the radiation dose, the study found that the more contaminated the area was, the higher the percentage of the non-breeding population. Non-breeding birds accounted for 23 percent of the population of swallows in Chernobyl. This is an extremely abnormal condition.

As for the nuclear incident in Fukushima, it will be necessary to conduct impact assessments that consider the degrees of contamination and target various taxa over a wide range of areas. It will be necessary to select the indicator organisms best suited for monitoring and make detailed comparisons in terms of their living, breeding and population dynamics in contaminated and control areas. Impacts on marine ecology were not dealt with in the case of Chernobyl because it is located inland, but it will be needed in Japan's case.

Next, Professor Tohru Nakashizuka gave a presentation on the subject of "How to monitor the ongoing impacts of earthquake disaster damage over the short- and long- terms?" (Here follows information from Prof. Nakashizuka's presentation).

In the recent series of disasters, damage from the tsunami was clearly heavier than damage from the earthquakes themselves, and coastal areas suffered greatly. Coastal zones are one type of ecosystem where biodiversity loss is of great concern in Japan. It is probably more accurate to say this is because they have been weakened by human impacts, rather than from any inherent vulnerability. Indeed, coastal zone ecosystems are more resilient, for example compared to terrestrial forests, because they are constantly exposed to natural disturbances.

The damage to the ecological services of the oceans are also great. The industries and livelihoods of people living in the area, such as fisheries and marine aquaculture, are greatly dependent on the ecosystem services of the oceans, which constitute many of the major characteristics of the area. For example, erosion-control forests have been planted by human beings in expectation of the ecological services provided by such forests, such as protection against tidal surges and sand storms. People in these areas have enjoyed these services for hundreds of years, and their loss greatly matters and has significant consequences for farmers who work the paddy and dry fields in the vicinity.

Some municipalities in the affected areas have started to build houses upland to avoid future potential tsunamis. Large scale housing development will be needed because flat land is scarce in the affected Sanriku region. When such development is carried out, large environmental changes will occur on the water-shed level.

Various groups have already started monitoring. Tohoku University team also started monitoring for mud flat, paddy fields and islets. Summaries of information resulting from these monitoring studies will be needed to establish a framework that can show the whole picture of the disaster.

As for short-term monitoring, onsite research should be conducted and information released. Long-term monitoring should be designed so that it shows the recovery process of when and how the land returns to something close to its former state, while keeping in mind the necessity for monitoring the impacts of changes along with the recovery process.

This article has focused on several of the important points made by some of the presentations. Assessments of the impacts of major earthquakes and related disasters, as well as the processes of recovery and resuscitation, normally take for granted that human lives, jobs and industries are the main if not the only priorities. However, JFS came to a strong realization that we also need to pursue the assessment, recovery, and retrieval of the biodiversity that supports our societies by providing ecosystem services.

Written by Junko Edahiro