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Author: search.filters.author.Klangnurak, WanladaSubject: search.filters.subject.Thailand

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    Occurrence of microplastics in Russell’s snapper (Lutjanus russellii) and associated prey species in the Central Gulf of Thailand
    (2025-02-01)
    Klangnurak, Wanlada
    ;
    Prachumwong, Siriluk
    ;
    Alfonso, María Belén
    ;
    Nakano, Haruka
    ;
    Chavanich, Suchana
    Microplastic (MP) contamination in fish may occur via their feeding behavior and ingestion of contaminated prey. This study investigated the presence of MPs in the predator Lutjanus russellii (Russell’s snapper) and its prey along the Chumphon coast of the Central Gulf of Thailand. Stomach contents of L. russellii were analyzed to identify its prey species. Prey species were then sampled from the same geographical area as the predator specimens for subsequent MP analysis. The dietary habits of L. russellii classify it as a generalist carnivore, consuming a diverse range of food items, including zooplankton, crustaceans, and small fish. No significant correlation was observed between MP abundance and the weight or length of the predator fish (general linear model, p > 0.05). Black and red fibers were the predominant MP types in both predator and prey, though MP sizes varied among the sampled species. In predator stomachs, the most common polymers were acrylonitrile butadiene styrene (ABS; 26.32%), polyethylene terephthalate (PET; 21.05%), and polyester (PES; 10.53%). Conversely, prey samples were dominated by PES (17.58%), PET (15.38%), and ABS (13.19%). Notably, similarities in MP characteristics (shape, color, average size, and certain polymer types) were observed between L. russellii and Portunus sp. The detection of smaller PET fibers in L. russellii compared to Portunus sp. (Mann–Whitney U-test, p ≤ 0.05) suggests the transfer of MPs to L. russellii through the ingestion of hard-shelled crustacean prey. This study underscores the importance of examining predator–prey interactions to better understand MP contamination pathways in marine ecosystems, particularly in regions like the Gulf of Thailand, where plastic pollution is prevalent. Further research is required to assess the long-term ecological implications of MP transfer within marine food chains.
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    DNA-based species identification of shark fins traded in thai markets
    (2023-08-01)
    Klangnurak, Wanlada
    ;
    Arunrugstichai, Sirachai
    ;
    Manopawitr, Petch
    ;
    Krajangdara, Tassapon
    Shark fins are among the most highly prized seafood products in the world with massive consumption in Asia over the past several decades. The demand for shark fins is a major driver of the enormous population declines of elasmobranchs that are generally vulnerable to overexploitation. This study aims to better understand the species composition of shark fin products in Thailand and their conservation statuses by using DNA-based species identification. Various types and sizes of shark fins were collected from 4 locations in Thailand. DNA barcoding method based on a fragment of the cytochrome c oxidase subunit I (COI) gene was applied to species identification. Fins from at least 15 shark species were found from Thailand’s markets. The spottail shark (Carcharhinus sorrah) and the night shark (Carcharhinus signatus) were the two dominant species presented in this study. 34% of identifiable samples are the species that have not been record in this region. 62% of species detected from the fin samples are categorized under the threatened categories of IUCN Red List. Species composition reported in shark fin products potentially helps indicate the appropriate conservation action and increases awareness from monitoring the trade in elasmobranch products.
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    Mitochondrial DNA Analysis Suggests Invasion of Thailand Coast by a Single Species of Dreissenidae, Mytilopsis sallei
    (2021-09-01)
    Klangnurak, Wanlada
    ;
    Wangkulangkul, Kringpaka
    In 2001, a species of false mussel was recorded in coastal areas in southern Thailand. In 2008, established populations were reported in several estuaries and lagoons. Based on shell morphology, the bivalve was identified as a non-native species belonging to Dreissenidae. To date, populations have been observed in five locations in southern Thailand on both the Andaman and Gulf of Thailand coasts. The variation in shell morphology within and between these locations led us to question whether specimens in different locations belonged to different species. We used morphometric techniques to investigate variation in shell characteristics among the five locations and mtDNA (COI) analysis to investigate genetic variation. Shell characteristics varied among locations; the shell morphology of specimens from some locations on the Andaman coast appeared to be similar to that of specimens from the Gulf coast. Most specimens had long, prominent apophyses, but in some specimens they were rounded and not prominent. In spite of the high variation in shell morphology, molecular analysis indicated that all COI gene sequences of the specimens examined are nearly identical and belong to a single species, Mytilopsis sallei. Phylogenetic analyses also revealed the monophyly of 25 sequences between our specimens and other M. sallei sequences from GenBank, with high bootstrap support. Our recent findings suggest that the name M. sallei should be applied to the false mussel in southern Thailand. However, this merits confirmation with analysis using other molecular markers, and more specimens should be included.
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    Screening for microplastics in marine fish of Thailand: the accumulation of microplastics in the gastrointestinal tract of different foraging preferences
    (2020-07-01)
    Klangnurak, Wanlada
    ;
    Chunniyom, Suwaree
    Microplastics in marine organisms are nowadays considered a worldwide phenomenon. An action plan needs to establish to solve this marine pollutant. It requires multidisciplinary information, including the accumulation of data on microplastics in marine biota. The research of microplastic ingestion in the marine environment and organisms of Thailand is limited. As a result, this study was conducted to evaluate the accumulation of microplastics in marine fish from Thailand and to investigate whether the different foraging mechanisms of fish impact the occurrence of microplastics in their gastrointestinal tract. A total number of 361 demersal fish and 131 pelagic fish were investigated. The collected microplastics were counted according to their shape and color. Their polymer type was identified by FT-IR for the first time in fish from Thailand. Moreover, microplastics ingestion sorted by fish size was noted. The number of ingested microplastics in this study was relatively low compared to other locations. There was no significant difference in the number of microplastics ingested between demersal and pelagic fish (p = 0.132). Microplastic fibers were the dominant shape found in both demersal (82.76%) and pelagic fish (57.14%). The most common polymer type was polyamide in both demersal (55.17%) and pelagic fish (50.00%). The dominant microplastics color in both demersal and pelagic fish was red (31.03% and 28.57%, respectively). Microplastics ingestion along different fish sizes fluctuated. This study provides evidence to fill a gap of research relating to microplastic ingestion by fish from Thailand.