Microplastic contamination in edible marine fishes from the upper Gulf of Thailand.

Seafood consumption is a major source of microplastic exposure for humans. Here, we demonstrated microplastic contamination in marine food fishes from the upper Gulf of Thailand. Microplastics were found in gastrointestinal tracts of 46.9 % of fishes sampled, with a mean concentration of 1.6 ± 0.5 pieces per fish or 0.04 ± 0.01 pieces/g of fish tissue. Demersal fishes had higher contamination rates than pelagic fishes. Fibrous-type and blue-colored materials were the most abundant microplastics, while the most common polymers were polyester and polyethylene. No associations between microplastics and histopathological changes were detected. Estimated daily microplastic exposure for human marine fish consumers was 0.03 to 0.1 pieces per person. Although we expect a low risk of microplastic contamination in fish muscle because of very low calculated transfer rates, we recommend continuing surveillance, including evaluations of contamination in the food chain to ensure future seafood safety in this region.

Microplastic-Contaminated Feed Interferes with Antioxidant Enzyme and Lysozyme Gene Expression of Pacific White Shrimp (Litopenaeus vannamei) Leading to Hepatopancreas Damage and Increased Mortality.

Microplastic pollution can interfere with aquatic animal health and nonspecific immunity, increasing the potential for pathogen infection in crustaceans. However, the long-term effects of microplastics on crustacean immunity are less understood, especially regarding their toxicity in Pacific white shrimp (Litopenaeus vannamei). Effects of high-density polyethylene microplastics (HDPE-MPs) in feed on the mortality rate, hepatopancreas, and nonspecific immune system gene expression of Pacific white shrimp are presented. The LC50 at day 28 of HDPE-MP exposure was determined as 3.074% HDPE-MP in feed. A significant upregulation of the superoxide dismutase (SOD) and glutathione peroxidase (GPx) genes was observed in shrimp that were fed with 0.1 and 0.5% of HDPE-MP; then, they were downregulated significantly, except for the SOD gene expression of shrimp fed with 0.1% of HDPE-MP. The lysozyme (LYZ) gene was upregulated significantly in shrimp that were fed with 0.5, 1, and 3% HDPE-MP for 7 days and downregulated significantly in HDPE-receiving groups for at least 14 days. Significant histopathological changes in the hepatopancreas were observed in the treatment groups. The histopathological score of each lesion was correlated with the increase in HDPE-MP concentration. This study shows that the ingestion of HDPE microplastics can alter the expression of nonspecific immune system genes and damage the hepatopancreas in Pacific white shrimp.

Using biomimicry and bibliometric mapping to guide design and production of artificial coral reefs.

Worldwide, artificial reefs are being installed to simultaneously attract recreational divers and protect deteriorating natural reefs. This study uses a bibliometric review of artificial coral reefs to identify five clusters as gate criteria for artificial reef design. These clusters enable the conceptualization and testing of artificial reefs for optimum integration of sociotechnical requirements, biological integrity, and ecological marine health. The five clusters are: (1) applications, solutions, and performance; (2) management, technology, and science; (3) calcification, biomineralization, chemistry, and ocean acidification; (4) coral species survival, mortality, and photosynthesis; and (5) artificial reef development, and coral and fish recruitment. The six biomimicry design stages are: define, biologize, discover, abstract, emulate, and evaluate. The 3D printing and hard corals design attracted a large number of planula larvae and different inhabitant corals, and a high species diversity in the surrounding waters. Practical implications include biomimicry-based means for coral reef restoration and recreational ecosystem services.

Epizootic of multi-centric, squamous cell carcinomas in populations of Indo-Pacific humpbacked dolphins Sousa chinensis in Thai waters.

Over the span of several years, 3 Indo-Pacific humpbacked dolphins died and were necropsied in Thailand. These 3 animals were all captive-bred at Oasis Sea World (Chanthaburi, Thailand), and displayed similar macroscopic progressive cutaneous lesions diagnosed as squamous cell carcinomas. In 2 of the 3 animals, necropsy revealed a severe fibrinosuppurative tracheitis and pneumonia secondary to metastasis of a cutaneous squamous cell carcinoma which extended from the head throughout the trunk and flippers. The tumors were characterized by coalescing botryoid masses with severe areas of cutaneous erosion, ulceration and necrohemorrhagic dermatitis. There was evidence of metastasis to the lungs and hilar lymph nodes. Necropsy of the third animal revealed similar progressive cutaneous squamous cell carcinomas but without evidence of metastasis. DNA molecular analysis of homogenized neoplastic tissue was conducted using polymerase chain reaction for both herpesvirus and papillomavirus in 2 of the 3 cases. In the first case, the tissues were positive for a herpesvirus alone, and this was phylogenetically classified as an alphaherpesvirus. This new herpesvirus has been tentatively named Sousa chinensis alphaherpesvirus. The second animal was negative for this novel herpesvirus and the third was not analyzed. In addition to the captive population, there is photographic evidence from 2 separate wild populations of Indo-Pacific humpbacked dolphins in the Gulf of Thailand, of a macroscopically identical proliferative and ulcerative process suspected to be squamous cell carcinomas.