Benthic communities and biodiversity in Thai mangrove swamps

1995 Fiscal Year Final Research Report Summary

• Project/Area Number: 07041121
• Research Category: Grant-in-Aid for international Scientific Research
• Allocation Type: Single-year Grants
• Section: Field Research
• Research Institution: Tohoku University
• Principal Investigator: NISHIHIRA Moritaka Tohoku University, Graduate School of Science Professor, 大学院・理学研究科, 教授 (80004357)
• Co-Investigator(Kenkyū-buntansha): PAPHAVASIT N チュラロンコン大学, 海洋学部, 準教授 ; NAKASONE Yukio University of the Ryukyus, 教育学部, 教授 (60044913) ; SHIKANO Shuichi Tohoku University, 大学院・理学研究科, 助手 (70154185) ; SUZUKI Takao Tohoku University, 大学院・理学研究科, 助手 (10124588) ; NITTHARATANA Paphavasit Chulalongkorn University
• Project Period (FY): 1995
• Keywords: mangrove swamp / benthos / biodiversity / haitat / mud flat / Thailand

Research Abstract

1.Field studies were conducted at Klong Kone mangrove swamps in Samut Songkhram Province, Thailand. Following a general survey of the mangrove swamps, we set a transect line along a water channel and selected 6 stations for detailed samplings from mud flat to landward fringe of the mangrove forest. The sediments were composed of sand and silt-clay roughly in the same proportions at all the stations. Organic matters in the sediments inside the forest were higher than those in the mud flat.
2.We studied the benthic fauna by quantitative and qualitative samplings. In the outer mud flat and the transplanted area, ocypodid crab, bivalves and polychaete worms were major components. In the central parts of the forest, gastropods, polychaetes, ocypodid and sesarmid crabs were prominent. In the landward fringe of the forest, erobid snails were abundant.
3.In the quantitative samples, we found a total of 63 species and an average density of 578 individuals per m^2. There was a general tendency for both species richness and number of individuals to decrease from mud flat to the inner part of the forest. However diversity index showed the opposite trend.
4.We had planned to study recolonization process of the discarded mangrove swamps by benthic animals. However, we could not find appropriate places for such a study at this time.
5.For population studies of some economically important animals, we have selected a cockle (Anadara). For the monitoring work of cockles, we collected the cockles from the culture cages 6 months after set-up. In the mud flat, cockles were still alive but their density was low. For the stations in the forest, however, most of the cockles had died.
For the studies of colonization processes of the barnacles, we collected plastic poles to which barnacles had settled at several different environments.