Yet another possible man-made disruption of nature has been reported from Kyushu’s Ariake Sea. This major nori (seaweed) cultivation area appears all but dead. Not only has output dropped sharply, the plant has also discolored. The abnormal growth of phytoplankton has created a serious shortage of nutrients for the seaweed, turning its color from deep black to light yellow.

Hardest hit are the nori growers in the four prefectures on the coast — Fukuoka, Saga, Kumamoto and Nagasaki. According to local fishery associations, output in early January was only 77 percent of what it was a year earlier in Kumamoto, about 70 percent in Saga and Nagasaki, and slightly above 50 percent in Fukuoka. At a recent auction in Kumamoto, the low-quality crop that had attracted no buyers the last time was put on sale again because there was no fresh harvest.

It is not yet clear exactly what has caused such damage to the nori in the Ariake Sea. But while the answer, or answers, must await an official survey, the finger is being pointed at the reclamation project in Isahaya Bay at the mouth of Ariake. Local fishermen warn that Ariake will become a “dead sea” unless the flood-control dikes on the bay are opened to restore the regular ebb and flow of the tide. Some 6,000 fishermen and harvesters riding more than 1,000 boats rallied off the bay late last month, demanding that the floodgates be opened.

In April 1997 the central government sealed off 3,500 hectares of wetland by closing the dikes, but the declared objectives — farmland development and flood control — were never fully explained. The project was widely criticized for threatening the ecosystem of the bay, which was once called the “womb of the Ariake Sea.” Four years on, that fertile tideland is dried up and the project is again coming under critical scrutiny.

The Ministry of Agriculture, Forestry and Fisheries, now conducting a field survey, leaves open the possibility that the gates might be opened for more detailed and extensive research, depending on the survey results. The Liberal Democratic Party has also suggested the need to restore the tideland. Key members of the three coalition parties have visited the area for a firsthand inspection.

The ministry is planning to wind up its preliminary survey in March and begin more elaborate studies in April. The political parties, alert to public sentiment, appear positive about opening the gates. But it is the government, particularly the agriculture ministry, that has the final say. The official line is that judgment must await until the surveys establish that bay reclamation is responsible for the damage to nori crops.

Local fishery associations hope the government will decide to open the gates as soon as possible. But bureaucrats directly involved with the project appear to be extremely cautious. They suggest it is unlikely that the current ad-hoc survey will produce enough evidence to determine before the end of March whether the gates should be opened. Implicit here is a desire to put off the moment of decision for as long as possible, for unlocking the dikes, whatever the reason, would cause considerable delays in the reclamation project.

The most urgent priority now, however, is to find out whether there is really a causal relationship between crop damage and bay reclamation. For that, it may be necessary to open the gates before, not after, the surveys are completed. Moreover, delays would give everyone involved, including government and prefectural authorities, time to re-examine the project from a broader perspective. Already the date of completion has been moved back six years to fiscal 2006 because of various problems in farmland development, such as the soft ground and potential crop damage from saline residues.

Isahaya Bay reclamation was not included in the list of public-works projects selected for review last autumn. Few people realized at the time, however, that Ariake’s ecology was already beginning to deteriorate. The nori seaweed, it seems, is not the only thing damaged by the project. For example, the harvest of “tairagi” fan shells — a prized specialty — has dwindled since the gates were closed, and so have the fish catches off Nagasaki’s Shimabara. A survey by a Nagasaki University professor of marine biology finds that the velocity and direction of the tide in Ariake have changed significantly since the dikes were shut down and that the numbers of benthos in the area have declined sharply.

The annual harvest of nori from the Ariake Sea exceeds 40 billion yen, making up about 40 percent of the national output. The crippling damage to the seaweed and other forms of marine life in the area is a clear warning of an ecological disaster in the making. Something must be done to stop it and restore health to the dying sea.

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