Impacts of Tourism on Marine Debris and Microplastic Detection at Samui Island, Southern Thailand

[EN] We investigated types, amounts and sources of marine debris and microplastics, and compared how tourism, by means of different levels of beach cleanup, affecting them. We collected marine debris and microplastics at three beaches based on frequencies of beach cleanup: high (Chaweng Beach), intermediate (Lamai Beach) and no beach cleaning (Hua Thanon Beach). Marine debris was counted from a ground survey using the applied Trash Free Sea® data card and the International Coastal Cleanup (ICC) method. Microplastics with a size larger than 1 mm were examined and photographed using a clip-type mobile phone microscope. The Clean Coast Index (CCI) was used for the assessment of beach cleanliness. Over 95% of the marine debris was plastic, and microplastics were ubiquitous, which calls for classification of the plastics as hazardous materials. Hua Thanon Beach had the highest (CCI> 20) (extremely dirty), followed by Lamai Beach (2-5 CCI) and the least CCI was at Chaweng Beach (CCI<2) (clean beach). This is because the popular tourism beach (Chaweng Beach) had the highest beach cleaning frequencies even during the 3-month lockdown of the covid-19 situation. This rapid-survey method could be developed and applied for a citizen-science project on the survey of marine debris and microplastics and on monitoring the condition of our beaches.We thanks Mr. David Chang for manuscript preparation, Miss Fahsai Thai-on, Miss Nittaya Jaerem, Miss Hawa Phoonpherm, Miss Kanchanid Panjareon, Miss Chanunchida Phitchayanitinai, students and teachers from Samsenwittayalai School for helping with field work. This work was supported in part by Samsenwittayalai school and the Center of Excellence for Ecoinformatics, Walailak University.Horpet, P.; Jaroensutasinee, M.; Jaroensutasinee, K. (2021). Impacts of Tourism on Marine Debris and Microplastic Detection at Samui Island, Southern Thailand. En Proceedings INNODOCT/20. International Conference on Innovation, Documentation and Education. Editorial Universitat Politècnica de València. 145-153. https://doi.org/10.4995/INN2020.2020.11870OCS14515

Climatic Factor Differences and Mangosteen Fruit Quality between On- and Off-Season Productions

The objective of this study was to investigate the differences in climatic factors and fruit quality between on- and off-season production periods. Climate, soil, and mangosteen measurements were all studied during on- and off-season production. We chose 40 mangosteen trees and observed flowering and fruit set rates over two production periods. The results showed that the number of flowers per branch, the number of fruits per branch, the circumference of fruits, and the fruit weight were higher during the on-season mangosteen production period than during the off-season mangosteen production period. However, the number of edible pulp segments, peel thickness, percentage of translucent flesh, and fruit gumminess were lower in the on-season mangosteen production period than in the off-season mangosteen production period. The percentage of fruit scars did not differ between the on- and off-season mangosteen production periods. When compared to the on-season mangosteen production period, there was lower relative humidity, soil moisture at 120 cm depth, and leaf wetness at 15 cm above ground during the off-season mangosteen production period; however, there was higher air temperature, soil moisture, and soil temperature at all four depth levels. Doi: 10.28991/ESJ-2023-07-02-020 Full Text: PD

Factors Affecting Population Density and Mound Distribution of Mud Lobsters, Thalassina spp.

This study is the first to investigate factors affecting population density and mound distribution of mud lobsters, Thalassina spp., in Southern Thailand. Mud lobsters are essential for nutrient cycling and maintaining mangrove ecosystems through their bioturbation activities. This study was conducted by establishing three transect lines in a 5×350 m2area beginning 100 m from the edge of the river towards inland and composed of six subplots with 50-m intervals (i.e., 100, 150, 200, 250, 300, and 350-m subplots). Numbers of mounds were recorded, and mound height and diameter basal area in each subplot were measured. Soil samples were collected, and moisture, grain size distribution, and pH were measured. The results showed that soil grain size was mostly less than 250 μm with an average soil pH of 4.48. The mound density and mound height increased with increased distance from the river (i.e., 267 mounds per hectare at 100 m increased to 1,734 mounds per hectare at 350 m from the river edge) and with decreased soil moisture (72.6% to 65.9%). This indicated that the mud lobsters preferred to build more and higher mounds farther away from the river edge, where they were less affected by the tide and the soil was drier. Findings also indicated that mud lobsters used resource partitioning to reduce intraspecific competition. This study is the first to show that mounds associated with prop roots had greater heights than mounds without prop roots nearby. Doi: 10.28991/ESJ-2024-08-01-012 Full Text: PD

Government Policy Influence on Land Use and Land Cover Changes: A 30-Year Analysis

This study investigated land use and land cover (LULC) patterns and changes in the Bandon Bay area of Thailand from 1991 to 2021 using satellite imagery, the first comprehensive effort to assess historical LULC trends over the past 30 years and forecast future LULC scenarios using the CA-Markov model for 2031, 2041, and 2051. Results showed the predominant LULC during 1991-2001 was the abandoned paddy fields, and during 2006-2021 was the oil palm plantations. During 1991-2001, the abandoned paddy fields changed significantly, with a net gain of 59.28 km2. From 2001-2011 and 2011-2021, the oil palm plantations experienced the most crucial change, with a net gain of 292.94 km2 and 70.06 km2. In 2031, 2041, and 2051, the LULC was predicted to be oil palms, shrimp farms, mangroves, and urban and built-up lands. The LULC changes were consistent with the government policies implemented and indicated government policy as a driving force in LULC dynamics on Bandon Bay area forestry, aquaculture, and agriculture, particularly on oil palm cultivation. Government management and regulation on land use is crucial for reducing the expansion of agricultural areas, especially oil palm plantations and aquaculture areas, to mitigate negative impacts on the Bandon Bay ecosystem. Doi: 10.28991/ESJ-2024-08-05-06 Full Text: PD

The effect of bubble nest size on sexual selection in wild Siamese fighting fish

The effect of bubble nest size was tested on male contest and female preference in wild Siamese fighting fish, Betta splendens Regan, a sexually dimorphic fish that exhibits paternal care. Females presented with two potential mates of different bubble nest areas did not prefer larger bubble nest males. Larger bubble nest males were not more successful in male contests. There were no differences in fighting duration. Comparing agonistic behaviour between large and small bubble nest males, there were no differences between these two males concerning any agonistic behaviours during fighting

The Effects of Different Types of Intruders on the Level and Characteristics of Territorial Defence Response of Domesticated Male Siamese Fighting Fish

This study investigated the effects of types of intruders on the level and types of male aggressive acts at different stages of the egg guarding period in domesticated fighting fish (Betta splendens). The degree of aggressiveness was measured at two reproductive phases in response to three types of intruders: male, female and female that had laid eggs. The nest-holding males displayed the same level of aggressiveness towards intruders before and after the hatching of eggs. Male intruders elicited the highest number of aggressive acts followed by female, and mated female intruders. The highest incidence of gill cover erection, biting, and tail beating by nest-holding males was directed towards male intruders whilst female and mated female intruders were subject to lower and lowest incidence of these aggressive acts respectively. However, female intruders were attacked and chased most frequently and mated female intruders comparatively less frequently whereas male intruders were least subject to these types of aggression

Metapopulation and its applications in conservation biology

Metapopulation, originally pioneered by Levins, refers to a series or set of local populations, each existing on a patch of suitable habitat that is separated from other occupied patches by unsuitable terrain. Each population has its own relatively independent dynamics. The long-term persistence and stability of the metapopulation arise from a balance between population extinction and recolonisation. Although metapopulation concepts are not commonly fit to real world conditions and there are still questions about the generality of metapopulation dynamics and the applicability of metapopulation models to specific problems in conservation, they have contributed significant insights into conservation and have inspired field studies focused on collecting key data on demography and movement. Moreover, metapopulation concepts have had positive effects in conservation research, especially, as interest in metapopulation dynamics has prompted renewed research concerning dispersal capacities that is extremely valuable in understanding population structure. Therefore, metapopulation concepts replace the island biogeography concepts that have been used in the past for decades

Numerical Study of Principal Tidal Constituents in the Gulf of Thailand and the Andaman Sea

This study examined numerical principal tidal constituents in the Gulf of Thailand and the Andaman Sea. The principal tidal constituents (K1, O1, M2 and S2) were calculated using a Harmonic method. These constituents were used to estimate the Form Factor (F). The simulated results from the Harmonic method were compared with the Moon phase in a 31-days cycle to verify our Harmonic model. We used observed water level data from 21 stations in the Gulf of Thailand and the Andaman Sea from both Hydrographic and Marine Departments. The tide types composed of (1) diurnal, (2) mixed with predominantly diurnal and (3) mixed with predominantly semidiurnal at 15 stations at the Gulf of Thailand coastline and semidiurnal at six stations of the Andaman Sea coastline. The Moon phase influenced tidal constituents in all stations, except the following 8 stations: Ko Prap (Surat Thani), Pakpanang (Nakhon Si Thammarat), Songkhla, Paknam Pattani (Pattani), Paknam Bangnara (Narathiwat), Paknam Ranong (Ranong), Ao Tublamu (Phangnga) and Paknam Krabi (Krabi) stations

Simulation of Dam Break Flow Using Quasi-Molecular Modelling

We developed a new method based on quasi-molecular modelling to simulate dam break flow. Each quasi-molecule was a group of particles that interacted in a fashion entirely analogous to classical Newtonian molecular interactions. The tank had a base length of 58.4 cm. A water column with a base length of 14.6 cm and a height of 29.2 cm was initially supported on the right side by a vertical plate drawn up rapidly at time t = 0.0 s. The water fell under the influence of gravity acting vertically downwards. The numerical results were validated by quantitative comparison with a previous study. The predicted height and leading edge of the water column corresponded very well with experimental measurements from a previous study. Therefore, our new method based on quasi-molecular modelling showed its ability to adequately simulate a free surface problem