Andaman Sea Coast Of Thailand Research Articles

Coral recruitment and recovery after the 2004 Tsunami around the Phi Phi Islands (Krabi Province) and Phuket, Andaman Sea, Thailand

The 2004 tsunami left a discontinuous pattern of destruction in the reefs along Andaman Sea coast of Thailand. Here, a comparative assessment of coral recruitment was carried out to assess differences in recovery between damaged and undamaged sites in near-shore fringing reefs 1 and 3 years after the tsunami. Settlement plates showed high frequencies of coral spat after 4 months (<17 spat tile−1) in both, damaged and undamaged locations. Field surveys carried out 3 years after the tsunami on natural substrate confirmed that tsunami damage did not suppress recruitment in damaged sites relative to no impacted controls. New and stable settlement space along with unabated larval supply supported post-tsunami recruit densities up to 7.2 m−2 year−1. Mean recruit densities were found at the level of post-storm situations with rapid recovery success, suggesting that the duration of disturbance, degree of sorting and, hence, stability of coral rubble is a key determinant of recruitment success. Low regeneration success of some species e.g. branching acroporids and rebounding tourism industry at sites like Patong and partly around the Phi Phi Islands (dense carpets of filamentous algae) led to the assumption of selectivity and eventually to an alternation of the coral community even though live coral cover might be recovered soon.

Temporal changes in benthic communities of seagrass beds impacted by a tsunami in the Andaman Sea, Thailand

Seagrass beds are susceptible to various natural and human-induced disturbances. Disturbances affect not only seagrasses, but also the abundance and diversity of associated macrofaunal communities. The Andaman Sea coast of Thailand was heavily affected by the tsunami of December 26, 2004. To examine its impact on seagrass macrofaunal communities, we compared the abundance, diversity and taxa composition by quantitative samplings in 2001 (before the tsunami) and in 2005 and 2006 (after the tsunami). Macrobenthic animals and sediments were collected from vegetated and nonvegetated areas of two sites that had received different levels of tsunami disturbances. A large decline in abundance and diversity was observed in the nonvegetated areas after the tsunami, whereas an increase was observed in the vegetated areas. The magnitude of decline and subsequent recovery of abundance and diversity of macrobenthic animals in nonvegetated areas were similar between the two sites, suggesting that their temporal changes were not solely related to the magnitude of the tsunami disturbance. Similarity of the benthic animals differed greatly between 2001 and 2005–2006 at the nonvegetated areas, whereas it varied less among the 3 years at the seagrass-vegetated areas. This study demonstrated that the presence of seagrass vegetation alters the patterns of temporal variation in macrofaunal assemblages and subsequent recovery processes following a tsunami.

Post-tsunami rehabilitation of fish cage farms on the Andaman coast of Thailand

A post-tsunami rehabilitation of cage culture along the Andaman Sea coast of Thailand was carried out in five provinces (Ranong, Phang-nga, Krabi, Trang and Satun) from September 2007 to February 2008. Based on the survey conducted, the money compensated subsequently used to buy materials for cage re-construction and cage repair accounted for 28.1% of the total, and to buy seed, feed and chemicals for culture operations, 15.8%. A surprising finding is that 56.1% of compensated money was used for other purposes. The analysis showed that the quality and quantity of equipment, seeds and feeds invested in aquaculture farms were increased in comparison with the pre-recovery period. Importantly, the farm area, growth rate, amount of product and revenue were improved during the post-tsunami rehabilitation period. Additionally, the area and quality of houses, household consumption, household infrastructures, health care and education were also improved. The satisfaction level of cage farmers in regard to the recovery programs was high (weigh average index = 3.88). The results from this study showed that the net economic profit (NEP) achieved was 41,030.49 baht/crop (33.9 baht = 1 US$) for sea bass culture, while NEP for grouper culture was 59,529.98 baht/crop. The result from the present study indicated that the economic value of cage culture farms was profitable. However, the seed shortage, high cost of trash fish, disease outbreak and marketing were among key problems and constraints encountered. In this study, we also found that the knowledge about fish marketing and culture techniques was poor. Therefore, technical, marketing and financial support are required for the future.

Tsunami Impacts on Biodiversity of Seagrass Communities in the Andaman Sea, Thailand: (1) Seagrass Abundance and Diversity

Evaluation of the impact of a catastrophic disturbance on biodiversity is often difficult due to a lack of sufficient quantitative data on biological communities prior to the disturbance. Since 2001, we have been monitoring the abundance and biomass of seagrass and its associated animal community along the Andaman Sea coast of Thailand, an area that was hit by a tsunami originating in the Indian Ocean on Dec. 26, 2004. To quantitatively evaluate the effects of the disturbance on the biodiversity of the seagrass community we carried out a comparative analysis of seagrass species diversity and abundance based on pre-/post-disturbance data at several seagrass beds at Kuraburi, northern Phang-nga (most-affected region) and Trang (less-affected region). Species diversity, coverage and biomass of seagrass declined greatly after the tsunami at one seagrass bed (Thung Nang Dam) in Kuraburi. The effect of the tsunami was less obvious at two other beds a few kilometers away from Thung Nang Dam, and at the seagrass beds in Haad Chao Mai National Park in Trang (located ca. 200km south of Kuraburi), where temporal change before and after the tsunami was the least obvious. A steady decline in biomass was observed in the three seagrass beds that had not been severely affected by the tsunami, possibly associated with other types of disturbance such as river discharge. Analyses revealed that the effect of the tsunami on seagrass ecosystems was highly variable even on small spatial scales, and that other factors causing disturbance to the seagrass beds are important factors of the observed temporal variation.

Effects of landforms on tsunami flow in the plains of Banda Aceh, Indonesia, and Nam Khem, Thailand

Mapping on high-resolution satellite images and in the field shows differences in landforms and characteristics of tsunami flow on two contrasting coastal plains following the giant earthquake on December 26, 2004: the plain of Banda Aceh on the northern tip of the Sumatra island, Indonesia, and the Nam Khem plain in the Andaman Sea coast of Thailand. The landforms of the Banda Aceh coastal plain are characterized as deltaic lowland with tidal plains in the western and central parts, and strand plain with beach ridges in the eastern part. The run-up tsunami flow invaded areas about 3–4 km from the coast. Strong tsunami flow severely damaged the tidal plain and the landforms along the coast except coastal dunes in the east. Most of the landforms except sand dunes along the coast had almost no effect on the protection against the tsunami, but the higher micro-landforms such as beach ridges and natural levees prevented the flow of the tsunami from its invasion into the inland near the end of tsunami inundation. The tsunami inundation spread out over the entire Nam Khem coastal plain with an average depth of 4–5 m. The direction of run-up flow was almost perpendicular to the coastline, whereas backwash flow directions were controlled by topography. Backwash flow was concentrated in the lower portions of the plain, for example in small stream channels. Wedge-shaped channels in the lower parts of the streams were formed due to the concentration of backwash flow. The existence of the swales between parallel beach ridges corresponds well with the distribution of thick tsunami deposits. Coastal erosion of the plain was caused by the direct attack of tsunami waves, and the lower reaches of small rivers were eroded by strong backwash flow.

Biogeographical implications of mitochondrial DNA variation in the Bockadam snake (Cerberus rynchops, Serpentes: Homalopsinae) in Southeast Asia

AbstractAim The biogeography of Southeast Asia has been greatly affected by Pleistocene sea‐level changes and the consequent alteration of coastline and land mass configurations. We investigated the effect of these Pleistocene events on genetic divergence in Cerberus rynchops, the Bockdam, an Asian water snake (Homalopsinae) associated with tidal mudflats and coastal mangrove forests in Southeast Asia.Location Localities for the Cerberus included the Andaman sea coast of Thailand, Sumatra, and Borneo (Sunda Shelf localities), the Philippines and Sulawesi, and from northern Australia (Sahul Shelf).Methods We analysed mtDNA sequences (12 s, 16 s, and cyt b) from seven C. rynchops populations (twenty‐six specimens), from two specimens of Cerberus microlepis (a freshwater species known only from Lake Buhi in the Philippines), and from one Enhydris enhyris (Schneider), another homalopsine used as an outgroup.Results We found a strong correlation between genetic divergence and geographical distance (r = 0.922, P &lt; 0.001) and the biogeographic history of the region. Cerberus rynchops populations from the Sunda Shelf localities, the Philippines, Sulawesi and C. microlepis from the Philippines were genetically similar (mean divergence = 2.1%, range = 0.7–2.8%) compared to the C. rynchops population from northern Australia (mean divergence from all other Cerberus populations = 6.6%, range = 6.0–7.3%). This divergence was comparable to that observed between the E. enhydris outgroup and all Cerberus populations (mean distance = 7.3%, range = 6.8–8.6%).Main conclusions These findings suggest a relatively high degree of movement and gene flow among Sunda Shelf localities, the Philippines, and Sulawesi (biogeographic region west of Weber’s Line) and isolation of the northern Australian (Sunda Shelf) Cerberus. Taxa will be differentially affected by these Pleistocene sea level changes dependent on their physiology and ecology. We discuss how the dispersal of the coastal, saltwater tolerant C. rynchops would have been affected by changing configurations of Pleistocene coastlines and the implications of these results for the systematics of Cerberus.