The Impact of Shrimp Farm Sludge Discharged on Mangrove forest

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概要

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• The loss of mangrove forest in some countries, including Thailand, is mainly caused by shrimp farming. An extensive survey including interviews, collection of observational and quantitative data was undertaken to investigate the impact of shrimp farm sludge discharged on mangrove forest as well as to explore the mangrove species which showed the greatest potential for restoration in sludge affected areas. The study and site survey funded by Asian Institute of Technology; Bangkok, was chosen at Amphor Pak Phanang of Nakhon Si Thammarat Province, southem Thailand The results show that the average discharge of sludge was 2-3 times per year depending on the number of shrimp croppings. Most of the sludge was discharged by the use of suction pumps while the pond bottom was still wet through pipe-lines into the natural mangrove forest. The thickness of the sludge in each pond before being discharged for each crop was 15-20 cm. It was found that the death of many mangrove trees began at 2-3 years after sludge deposition. Among these, Bruguiera cylindrica showed symptoms at the sludge depth of 25 cm, Lurnnitzera racemosa at 33 cm. and Exceocaria agallocha at 30 cm. At a depth of 40 cm., however most trees were dead. At some locations within the studied area where sludge was no longer deposited, seedlings of Avicennia marina and L. racemosa germinated and grew up to 52-65 cm. at 7 months after the first rain. In addition, if an area was not affected by further sludge deposits, the regrowth of old stumps was possible for some species such as Bruguiera gyrnnorhoza, E. agallocha, L. racemosa. In the sludge affected area, 14 potential mangrove species were planted for the restoration experiment. The results showed that only Rhizophora mucronata and Rhizophora apiculata survived and grew well at three months after planting. The death of many mangrove species under such condition may be due to the anaerobic activity around the root zones, together with the lack of adaptive ability and high soil salinity from newly released sludge.

• 日本マクロエンジニアリング学会の論文

著者

• BAMROONGRUGSA Noparat

  Prince of Songkla University

• Boromtanarat Somsak

  Prince of Songkhla University

• Panichart Sangob

  Nakhon Si Thamrnarat Regional Forest Department

• Kato Shigeru

  Faulty of Engineering, Seikei University

関連論文

• 7. Mangrove Rehabilitation in Abandoned Shrimp Ponds at Nakhon Si Thammarat, Southern Thailand(Abstracts of Papers Presented at the Fall Meeting of the Union, December 2004)
• The Impact of Shrimp Farm Sludge Discharged on Mangrove forest

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