Microplastic pollution mainly emanates from terrestrial sources but studies of plastic contamination in freshwater ecosystems remain limited. Consumption of freshwater fish is widespread throughout all regions of Southeast Asia. Contamination of microplastics in fish is an important issue which leads to human health risk. Common freshwater fish in the Chi River, Thailand were caught by local fishermen and investigated for abundance, size, color and shape of microplastics. Eight fish species were investigated. Results showed that 72.9% of the collected fish were polluted with microplastics at mean abundance of 1.760.97 particles per fish and was no significant difference of abundance between species. Percentage occurrence of microplastics was highest in omnivorous fish Puntioplites proctozysron (86.7%) with the most common size of microplastics ingested by fish at over 0.5 mm (47.5%), of which 56.9% were blue color and 86.9% were fiber shaped. Results revealed that fishing nets and fish cages were major sources of microplastic contaminants in the Chi River.
Microplastic pollution has been identified as a potential threat to the aquatic environment and humans globally, with widespread occurrence in ecosystems, including reservoirs that constitute a key role in ecosystem services for humans. However, the evaluation of microplastic pollution in reservoirs is limited, especially in inland fishing ground reservoirs. The spatial and temporal distributions of microplastics in surface water and sediment at 13 stations of the Ubolratana Reservoir, Thailand, were assessed during the wet and dry seasons. The abundance and morphological characteristics of the microplastics were identified and classified by color, shape, size and polymer type. Microplastic abundance in surface water and sediment ranged between 25 and 3363 particles/m3 and 6 and 81 particles/kg, respectively. Seasonal variations impacted microplastic abundance in surface water, while tourism activity in the reservoir also influenced the abundance and morphological characteristics of microplastics. A microplastic risk assessment showed that the pollution load index reached extremely high levels in surface water during the dry season in tourist areas. The results provide a database to assess the risk of microplastic contamination and to monitor plastic pollution in lentic ecosystems, including preserving the health of aquatic habitats.
ABSTRACT:The coral reef ecosystem in the Andaman sea was studied by monitoring aquatic environmental conditions and reef condition from years [2005][2006][2007][2008][2009]. Following the Asian tsunami in December 2004, the ammonium-nitrogen concentration in the surface water in Ranong province ranged from 8.45-14.08 µM, while in Phang Nga area, it was between 9.99 and 25.11 µM. Mean sea surface temperatures in Ranong and Phang Nga were 30.6 ± 0.4°C during the dry season. The growth rate of Acropora spp. in Chong Khat bay, Surin Marine National Park, was 1.0 cm/month during the first 5 months after the tsunami. After this five-month period, corals, especially Acropora spp., showed signs of recovery but then faced extensive bleaching in May 2005. Three years after the tsunami, the coral reefs in deep water areas could grow and recover rapidly although they faced serious bleaching while coral reefs in the shallower waters were in a poor condition after serious bleaching in May 2005. This phenomenon revealed that the mass mortality of corals in shallow waters was enhanced by high seawater temperature and high turbidity due to phytoplankton blooms. Overall results indicate that the relationships between environmental conditions and coral reef status in the Andaman sea is an issue of great concern and coastal corals may gradually degrade in the near future unless action is taken to alleviate coastal environmental problems.
Spicule network patterns inside the body of a nudibranch play an important role in supporting the soft body of the nudibranch. These patterns can also be one of the indicators for prediction of the phylogenetic affinity of the nudibranch. Specimens of the nudibranch (Phyllidia varicosa) were collected from Koh Phi Phi and neighbouring islands in Krabi. The spicule network in the mantle of the central notum looked like a net, whilst at the edge of the mantle it appeared as a radial line crossing the body. The spicules in the nudibranch foot were interlaced and were perpendicular to the body length. A study of the spicule contents by indirect examination indicated that the CaCO3 content in the central notum, mantle edge, and foot was 460 ± 20, 462 ± 20, and 469 ± 20 mg/g dry weight, respectively. The spicule content in the various body regions did not differ significantly (p = 0.7). The relationship between total weight of the spicule network (TW) and whole body dry weight (WB) was estimated as TW = 0.446WB (R 2 = 0.9994).
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