Sea grapes or green cavier (Caulerpa lentilifera), a common tropical green seaweed, consisted of polysaccharides to be used as a prebiotic precursor for prevention of pathogens in aquatic animals. The efficiency of polysaccharides extracted from sea grapes for prebiotic properties was conducted by comparing the growth of probiotic bacteria Bacillus subtilis at different concentrations in co-cultured with pathogenic bacteria Vibrio parahaemolyticus, a gram-negative motile bacterium that inhabits marine and estuarine environments throughout the world, causes of violent diseases outbreak in aquatic animals. The experimental research was 4 treatments with 4 replications including control group (LB broth), extracted sea grape enrichment in LB broth at 0.5, 1.0 and 2.7 mg.C/l. The result showed that the highest growth of probiotic bacteria appeared significantly at extracted sea grape in LB broth with 0.5 mg.C/l (1.64×107 ± 6.04×106 cfu/ml). The said concentration was used as benchmark to clarify the pathogenic resistance. The comparison between monoculture of probiotic bacteria and co-culture of probiotic bacteria plus pathogenic bacteria indicated that there was non significantly different in growth of the bacterias. Hence extracted polysaccharides from sea graps (C. lentilifera) had potential to be utilized not only as a growth enrichment of probiotic bacteria but also inhibiting pathogenic bacteria.

This study of community structure of zooplankton in the Inner Gulf of Thailand was initiated in late 2011 in response to a major flood disaster event and continued intermittently to 2018. Six cruises with 13-20 replicate stations/cruise, provided data for contour maps of zooplankton, nutrients, water hydrography, pigments and algae; this manuscript utilized this diverse data set to focus on mesozooplankton. Immediately after the flood, November 2011, mesozooplankton communities were dominated by calanoid copepods with contributions of about 78% of the total. This changed in 2012 to 2018 which the proportion of calanoid copepods was decreased while the other zooplankton such as hydromedusae, polychaete larvae, barnacle nauplii, pelagic shrimp (Lucifer sp. and protozoea) and chaetognaths were increased. The density of mesozooplankton varied between 1.70 x 104 to 1.26 x 106 ind./100 m3 with noticeably high densities near the four river mouths that flow into Inner Gulf. Distribution patterns of mesozooplankton emerged that are likely similar to the long-term patterns of this region which effected by water circulation in the Inner Gulf of Thailand. However, high density of zooplankton in November 2012 and October 2017 appeared along the north-eastern coast and may be related to the availability of food (i.g., algae). Zooplankton abundances in the Inner Gulf of Thailand were significantly correlated with environmental parameters mainly temperature, salinity and food supplies as represented by chlorophyll a concentrations.

Siriwattanarat R, Wongroj W, Ngamniyom A, Vilasri V, Chungthanawong S, Punnarak P. 2024. Fish diversity and environmental factors at the Don Hoi Lot Ramsar Site, Thailand. Biodiversitas 25: 1394-1403. The Don Hoi Lot mudflat, recognized as a Ramsar site, is a globally acclaimed wetland located in the Khlong Khon Sub-district of Samut Songkhram Province, Thailand. This research aims to study fish diversity and environmental variables at the Don Hoi Lot Ramsar Site; fish samples were collected using cast nets (mesh size 1.5 cm and 2.5 cm) and gill nets (mesh size of ¾ inch, 1.5 inches, and 2 inches) by local fisheries from four sampling stations which represented upstream (KK1), midstream (KK2), downstream (KK3), and estuary (KK4) zones in Khlong Khon Bay during January to April 2023. A total of 1,389 fish specimens were collected, representing 36 species belonging to 26 families. Higher diversity in number of species (28-35 species), Shannon index (2.90-2.98), and species richness (10.40-13.11) were found at downstream and estuary stations, while the lowest number of fish species (three species), Shannon index (0.75), and species richness (0.68) were recorded at the upstream station. Similarly, the higher relative abundance of fish (84-173 specimens) was observed at downstream and estuary stations, and the lowest relative abundance (29-50 specimens) was also reported at the upstream station. The blackchin tilapia (Sarotherodon melanotheron Rüppell 1852) was the dominant species at the Don Hoi Lot Ramsar Site during the study periods, followed by the Mozambique tilapia (Oreochromis mossambicus Peters 1852)). Principal component analysis (PCA) further revealed that altitude, temperature, pH, salinity, transparency, ammonia, phosphate and silicate had significant relationships within fish assemblages, whereas nitrite and nitrate were less important in this study. Nonetheless, the rapid expansion of the blackchin cichlid population has had an adverse impact on native fish populations, which could pose a real threat to fish diversity and population, and other aquatic organisms.

Biomonitoring and environmental impact assessment of marine ecosystems are important for the effective management of petroleum platform activity. Eukaryote biodiversity in water and sediment near petroleum platforms in the Gulf of Thailand was surveyed using environmental DNA (eDNA) based on 18S ribosomal DNA variable region 4 (18S rDNA-V4), the full-length 18S rDNA gene (18S rDNA-FL), and cytochrome c oxidase subunit 1 (COI). Water and sediment samples were collected from three platforms. The water sample was also collected from a reference site located farther south, away from the platforms. Both 18S rDNA markers outperformed COI. A total of 1144 and 889 species were found in water and sediment when analyzed by 18S rDNA-V4, and 519 species were found in sediment when analyzed by 18S rDNA-FL. Only 99 species were found in water samples when analyzed by COI. Alpha-diversity (Shannon and Simpson Evenness) indices were significantly different in water (p < 0.05), but not in sediment (p > 0.05). Beta-diversity (PCoA and NDMS) revealed significant species components between different petroleum platforms (p < 0.01). Species distribution revealed biological connectivity between eukaryotes from different platforms suggesting the importance of platforms on ecological impacts. This study also illustrates the possible application of eDNA for monitoring ecological toxicity around petroleum platforms.

Jellyfish polyps can be difficult to identify based on their morphology due to a lack of precise references in Thailand, yet species identification is an important step for management of this marine resource. Here, we pursued a dual approach, morphology and DNA barcoding, to describe the diversity and distribution of jellyfish polyps in two coastal provinces that have various anthropogenic activities e.g., tourism, marine transportations, industrial estate, local fisheries, and aquacultures, that effect on water qualities or provide substrates for polyp settlement. Jellyfish polyps were collected in January, May, and July 2019 to represent the Northeast Monsoon, pre-Southwest Monsoon, and Southwest Monsoon, respectively, from eight stations along coastal areas from Chonburi and Rayong Provinces, eastern Thailand. The jellyfish polyps were sampled from substrates e.g., rocks, ropes, and shells, at sampling sites by scuba diving. Three genera of polyps were identified according to their morphology, while nine genera of jellyfish polyps were identified by their COI gene sequences from 29 individuals. Polyps of the genus Clytia were recorded during the sampling periods at most sampling sites, while the genus Obelia was found mainly at Rayong Province, when identified by both morphological and molecular approaches. These results can be used as part of a suitable management plan about jellyfish issues in Thailand.