Status of seagrass in Thailand

In Thailand, there are many important seagrass beds in both the Gulf of Thailand and  The Andaman Sea such as Ao Thung Kha-Sawi, Chumporn Province, Ao Khung Kraben, Chantaburi Province, Ko Talibong, Trang Province, Ko Sriboya-Ko Pu, Krabi Province, Ko Prathong and around Phang Nga Province and Ban Pakhlok, Phuket Province (Yamarunpattana and Paokanta, 2007). In Thailand, 12 seagrass species are found along the coast of 17 coastal provinces, i.e., Chonburi, Rayong, Chantaburi, Trat, Chumporn, Surat Thani, Nakhon Si Thammarat, Pattalung, Songkhla, Pattani, Narathiwat, Ranong, Phang Nga, Phuket, Krabi, Trang and Satun. Meanwhile, 11 species are found in The Andaman Sea, except Ruppia maritima, which only found in the Gulf of Thailand. According to the survey and monitoring of seagrass beds in Thailand in 2011, it found that the total seagrass area was 118,665 rai distributing in The Andaman Sea and the Gulf of Thailand with 86,100 rai and 32,565 rai, respectively. The total number was more than previous data which found only 93,000 rai since many areas were further investigated using high technology equipments and having more additional data of finding new seagrass beds, for example, the seagrass beds in Kuraburi, Phang Nga Province, where Halophila decipiens were found in the mouth of a canal and abundantly covered in shallow water.  This illustrates that Halophila decipiens is not only found in deep water with good quality, but also in shallow water with poorer quality. Naturally, the species composition and density of seagrasses in Thai Waters are seasonally changed and varied by each area. Seagrass can be recovered although they have impacts from natural disasters such as waves, monsoons, and storms or human interferences because of its structure, called rhizomes that are merged and connected altogether and having more strongness and  tolerance to environmental factors Besides, there are some seagrass areas that require further survey and monitoring even if these areas are small. These data are useful for future management of marine and coastal resources. Status of seagrass can be concluded by each areas as follows;   Status of seagrass in the Eastern Gulf of Thailand The total of seagrass area was 11,958 rai consisting 9 seagrass species which are dominated by Halodule uninervis, Halophila ovalis, Halophila decipiens and Enhalus acorides. The important seagrass areas were in Ao Ma Kham Pom and Mu Ko Man, Phang Rat Estuary of Rayong Province, and Ao Khung Kraben of Chantaburi Province, which have a total area of 332 rai and 6,407 rai, respectively. The seagrass beds in the Eastern Gulf of Thailand were in fair to good conditions.   Status of seagrass in the Upper Gulf of Thailand The previous report indicated that seagrasses were only found at the mouth of canal Bang Kra Noi and Bang Kra Yai, Phetchaburi Province, with the total area of 10 rai. Only Ruppia maritime was only one species found in aquaculture ponds. At the present, these areas are included as part of Sirindhorn International Environmental Park.   Status of seagrass in the Central Gulf of Thailand The total seagrass area is 18,995 rai. There are ten species dominated by Enhalus acorides, Halophila ovalis and Halophila beccarii. The important seagrass areas were in Ao Thung Kha-Sawi of Chumporn Province with the area of 6,650 rai. The seagrass areas in Ao Bandon, Ko Pha Ngan, and Ko Samui of Surat Thani with the area of 6,200, 1,900 and 2,300 rai, respectively. Overall, the seagrass beds were in fair to good conditions except some areas, which were affected by sediments generated from coastal development such as Ko Samui and Ko Pha Ngan, and the seagrass in these areas might faced with the long term impacts.   Status of seagrass in the Lower Gulf of Thailand The total area of seagrass was 1,612 rai. There were nine seagrass species, dominated by Halodule uninervis, Halophila ovalis Halophila decipiens and Enhalus acorides. The important seagrass areas were about 680 rai in Ao Pattani and Ko Ta Rai, and 75 rai of seagrass beds found in Nakhon Si Thammarat. Overall, the seagrass beds were in naturally poor condition with the coverage of 60%   Status of seagrass in the Upper Part of The Andaman Sea The total area of seagrass was 34,885 rai and there are eleven species, dominated by Enhalus acorides, Halophila ovalis and Cymodocea serrulata, especially Halophila beccarii was mostly found in Ao Bang Ben of Ranong Province and Tung Nang Dam of Phang Nga Province. The important seagrass areas were in Ao Bang Ben with the area of 1,261 rai, Tung Nang Dam with the area of 2,420 rai, Ko Prathong and its vicinity of Phang Nga Province with the area of 17,251 rai and Ao Pa Klog of Phuket Province with the area of 1,905 rai. The seagrass beds were in fair to good conditions. The seagrass areas in this zone were abundant with seagrass resources and marine organisms including economic organisms and marine endangered species, i.e., dugongs, sea turtles and dolphins. In some areas where the coasts were developed such as Ko Phuket, seagrass beds are affected from sediment accumulation and discharge of domestic wastewater.   Status of seagrass in the Lower Part of The Andaman Sea The total area of seagrass is 51,215 rai, it is considered as the largest seagrass bed in Thailand. There are eleven seagrass species, dominated by Enhalus acorides, Halophila ovalis and Cymodocea serrulata. Most seagrass areas were in Krabi and Trang Provinces. The large and important areas of seagrass beds were Ko Sri Boya, Ko Talibong, and Ko Muk with the areas of  15,923 rai, 7,306 rai and 8,148 rai, respectively. The seagrass beds were in good condition and abundant with marine organisms in seagrass, including economic organisms and marine endangered species, i.e., dugongs, sea turtles and dolphins.

Table  Status of seagrass on coastal Thai Waters

Zone

Province

Area(rai)

Status

Dominant species

Cause of degradation

Eastern Gulf of Thailand Chonburi 614 Fair condition Halophila decipiens Halophila minor Halodule uninervis Dam, pier, and resort construction around Ao Sattahip resulting in decrease of seagrass in the areas
Rayong 332 Fair condition - naturally poor condition Enhalus acorides Halophila ovalis Local fishery, seasonal change
Chantaburi 6,407 Good condition Halodule uninervis Wastewater from aquaculture farming
Trat 4,605 Fair condition – poor condition from threats Enhalus acorides Halodule uninervis Natural Change
Middle Gulf of Thailand Chumporn 8,535 Fair condition Halophila beccarii Change by nature
Surat Thani 10,460 Good condition Halophila ovalis Halophila beccarii Enhalus acorides - High sediment from nature such as Laem Hin Ngam and Laem Yai - Human activities such as coastal development
Lower Gulf of Thailand Nakhon Si Thammarat 75 Naturally poor condition Enhalus acorides Thalassia hemprichii Small seagrass areas may be seasonally changed
Pattalung 460 Poor condition from threats Halophila beccarii Halodule pinifolia Natural Change
Songkhla 343 Naturally poor condition Halophila beccarii Halodule pinifolia Halodule uninervis Natural Change
Pattani 680 Naturally poor condition Halophila beccarii Halophila ovalis Halodule uninervis Ruppia maritima Dredging activity for fishery  pier construction  
Narathiwat 54 Poor condition from threats Halophila beccarii Halodule uninervis Natural change
Upper The Andaman Sea Ranong 1,290 Fair condition Halophila beccarii Halophila decipiens Halodule uninervis Sediment from coastal development
Phang Nga 29,076 Good condition - Naturally poor condition Cymodocea serrulata Halophila beccarii Halophila ovalis Enhalus acorides Natural movement of sand bar, destructive fishing gear (trawl nets, push nets) and erosion from Tsunami
Phuket 4,519 Good condition - Naturally poor condition Enhalus acorides Cymodocea serrulata   High sedimentation from human activity such as marine mining, fishery by trawl nets and push nets, some wastewater from aquaculture and erosion from Tsunami
Lower The Andaman Sea Krabi 31,205 Good condition - Naturally poor condition, some area poor condition from threats Halophila ovalis Halodule pinifolia Cymodocea serrulata   Impact from nature, sediment from coast and push nets fishery
Trang 17,985 Good – fair condition Enhalus acorides Halophila ovalis   Push nets catch grouper, large beach seines, sediment from coast and erosion from Tsunami
Satun 2,025 Naturally poor condition Syringodium isoetifolium Enhalus acorides No problems of degradation found
Source: Department of Marine and Coastal Resources (2012b) Remark        Criteria for determining seagrass condition                     Poor condition from thread refers to the coverage of seagrass with lower 25 %                     Naturally poor condition refers to the coverage of seagrass with 25 %                     Fair condition refers to the coverage of seagrass with 26-50 %                     Good condition refers to the coverage of seagrass with 51-75 %