Sedimentary History of Trace Metals Over the Past Half-Century in Songkhla Lake, Western Coast of the Gulf of Thailand: Anthropogenic Impacts and Contamination Assessment

Coastal lagoons are among the most vulnerable and economically significant ecosystems on Earth. Songkhla Lake, connected with the Gulf of Thailand, is the second largest lake in Southeast Asia and supports the development of the fishery, transportation, and tourism industries in southern Thailand. With increasing anthropogenic disturbances, the lake is facing acute ecological problems and further research is needed. Here, we provide 55-year record of grain size, color reflectance, magnetic susceptibility, total organic carbon, total nitrogen, and trace element (As, Hg, Pb, Cr, Ni, Cu, and Zn) concentrations of sediment core SKL8-2 collected from Songkhla Lake. These records reveal a three-stage sedimentary and input history of trace metals under anthropogenic effects: 1) From 1964 to 1982, it was a natural terrigenous input period with a relative reduction environment when the channel connecting Songkhla Lake and the Gulf of Thailand was closed. 2) Trace metal concentrations, organic carbon content, b* value, and magnetic susceptibility changed abruptly in 1982. During 1982–2000, the sources of trace metals were more complex than during 1964–1982 and mainly came from urban wastewater, industrial effluent, and fishery discharge. 3) From 2000 to 2019, contamination signals of Pb, Hg, As, Zn, and Ni emerged in the first decade because of the rapid development and poor sewage treatment around nearby cities.

Age and growth estimates from three hard parts of the spotted catfish, Arius maculatus (Actinopterygii: Siluriformes: Ariidae), in Songkhla Lake, Thailand’s largest natural lake

The spotted catfish, Arius maculatus (Thunberg, 1792), is a euryhaline fish that is economically important in the Indo-West Pacific. Population dynamics studies and stock assessments of this species have focused on marine stocks, but not those from fresh water. In this study, the age and growth of A. maculatus were, therefore, investigated for the inland stock in Songkhla Lake, Thailand. A total of 213 individuals ranging between 35 and 238 mm TL were used. The length–weight relation indicated positive allometry of this population. Three hard parts (otolith, dorsal- and pectoral-fin spines) were used for aging. The marginal increment ratio confirmed that an annulus was deposited once a year in all three hard parts. All of the samples were aged between 0+ and 6+ years. Verification of age estimates from three readers showed that the otolith was the most suitable part for age estimation. Three growth models (von Bertalanffy, Gompertz, and logistic) were applied in the study. The von Bertalanffy model best described the growth of this fish in Songkhla Lake. The obtained asymptotic length was 290.87 mm TL and the relative growth rate parameter was 0.166 year–1. Our results will be applied as inputs for fish stock assessment models. The obtained growth parameters also can serve as a reference for A. maculatus stocks elsewhere.

Microcystis Sp. Co-Producing Microcystin and Saxitoxin from Songkhla Lake Basin, Thailand

The Songkhla Lake Basin (SLB) located in Southern Thailand, has been increasingly polluted by urban and industrial wastewater, while the lake water has been intensively used. Here, we aimed to investigate cyanobacteria and cyanotoxins in the SLB. Ten cyanobacteria isolates were identified as Microcystis genus based on16S rDNA analysis. All isolates harbored microcystin genes, while five of them carried saxitoxin genes. On day 15 of culturing, the specific growth rate and Chl-a content were 0.2–0.3 per day and 4 µg/mL. The total extracellular polymeric substances (EPS) content was 0.37–0.49 µg/mL. The concentration of soluble EPS (sEPS) was 2 times higher than that of bound EPS (bEPS). The protein proportion in both sEPS and bEPS was higher than the carbohydrate proportion. The average of intracellular microcystins (IMCs) was 0.47 pg/cell on day 15 of culturing, while extracellular microcystins (EMCs) were undetectable. The IMCs were dramatically produced at the exponential phase, followed by EMCs release at the late exponential phase. On day 30, the total microcystins (MCs) production reached 2.67 pg/cell. Based on liquid chromatograph-quadrupole time-of-flight mass spectrometry, three new MCs variants were proposed. This study is the first report of both decarbamoylsaxitoxin (dcSTX) and new MCs congeners synthesized by Microcystis.

Creative Tourism in Songkhla Lake Basin

Songkhla Lake Basin has a long history of at least 6,000 years and has a wide variety of tourism resources including nature, history, beliefs, culture and various traditions of the local people. It covers 3 provinces, the whole area of Phatthalung, 12 districts of Songkhla and 2 districts of Nakhon Si Thammarat Province. It has an area of approximately 8,727 square kilometers. There are many tourist attractions because the basin has a long history through different eras, natural, historic, ancient sites, and the culture of the local people. In 2018, both Thai and foreign tourists visited Songkhla and Phatthalung, which is the main area of Songkhla Lake Basin. The total number of tourists that came was 7,628,813 and 1,641,841 and an income of 68,252.64 and 3,470.96 million baht was generated from each province, respectively (Ministry of Tourism and Sports, 2020). Although Songkhla Lake Basin has various tourist attractions, the promotion of tourism with the involvement of government agencies in the past mainly focused on promoting tourism along with the tourist attractions rather than encouraging tourists to experience and learn the culture of the people living in the area; the culture that reflects the uniqueness of the people in the south. This study, therefore, aims to find creative tourism activities in SLB in order to increase the value of tourism resources, create tourism activities that are aligned with the resources available in the community and increase the number of tourists in the area. Data for this study were collected using a secondary source of data collection method. It was done through a literature review of related documents, texts, magazines, and research which focus on Songkhla Lake Basin as a guideline for designing tourism activities. The field survey was done through twelve community-based tourism sites in SLB to find creative tourism activities. Data on each activity were collected in detail by interviewing the tourism community leaders and the local people. Content analysis was used to describe the individual open-ended questions by focusing on the important issues and the information obtained was presented as a narrative. Keywords: Songkhla Lake Basin, Creative Tourism, Local Wisdom

Songkhla Lake Sebagai Wisata Favorite Di Thailand

Makalah ini merupakan hasil laporan Foreign Case Study untuk syarat publikasi ilmiah di Sekolah Tinggi Pariwasata Ambarrukmo Yogyakarta dengan Judul Songkhla Lake Sebagai Wisata Favorite Di Thailand.