Journal of Fisheries and Environment

Leaching and Fluorescence Characteristics of Dissolved Organic Matter Released from Common Consumer Plastics

2025-05-15T11:05:02+07:00

Plastic pollution poses increasing risks to wildlife, human health, and aquatic ecosystems, acting as a source and vector of dissolved compounds. This study investigated the leaching and fluorescence characteristics of dissolved organic matter (DOM) from three common consumer plastics: polypropylene (PP), low-density polyethylene (LDPE), and polyethylene terephthalate (PET). Plastics were incubated under simulated light or dark conditions for 21 days, and dissolved organic carbon (DOC) and fluorescent DOM (FDOM) were measured to quantify leaching amounts and characterize DOM quality. Our results showed that PP released the highest DOC concentrations, while LDPE and PET showed much lower levels. By day 21, average DOC leaching from PP, LDPE, and PET was 10.50, 1.62 and 0.53 mg C·m^-2 of plastic surface, respectively. Corresponding leaching rates were 4.02, 0.56 and <0.10 mg C·m^-2·d^-1. In contrast to differences in DOC quantity, the FDOM of all plastics exhibited similar spectral features, with a major tryptophan-like peak at 295–305 nm excitation and 335–340 nm emission, and a minor peak at 235–254 nm excitation and 335–340 nm emission. These fluorescence signals suggest that plastic-derived DOM is bio-labile and potentially influenced by additives. Overall, the results confirm that common consumer plastics are a reactive source of DOM that may alter carbon cycling and microbial processes in aquatic environments. We suggest that both plastic type and additives likely affect DOM leaching behavior, with implications for understanding the broader ecological impacts of plastic pollution.

Evaluation of Spray-Dried Porcine Plasma for Growth Performance, Production Yield, Immune Responses, and Total Vibrio Counts in Pond-Reared Giant Tiger Prawn (Penaeus monodon)

2025-08-11T09:09:54+07:00

Spray-dried porcine plasma (SDP) is a protein-rich feed ingredient derived from animal blood with potential health benefits. This study evaluated the effects of dietary SDP on growth, survival, and immune responses in pond-reared giant tiger prawn (Penaeus monodon). Six earthen ponds in a commercial farming system in Prachuap Khiri Khan Province, Thailand, were stocked with postlarvae at a density of 750,000 shrimp·ha^-1 (75 shrimp·m^-2). Three ponds received a standard commercial diet (Control group), while the other three ponds were fed a pelleted diet containing 4.5% SDP (SDP group) for 30 days (days 30–60 post-stocking), after which all ponds were fed a standard diet until harvest. The inclusion of SDP improved feed conversion ratio (FCR) compared with the control group. Shrimp fed the SDP diet showed significant (p<0.05) increases in immune parameters and reduced total Vibrio counts in both the hepatopancreas and intestine. Unexpectedly, an outbreak of acute hepatopancreatic necrosis disease (AHPND) occurred on day 80, affecting all control ponds and one SDP pond, while the other two SDP ponds remained AHPND-negative. This suggested a potential protective effect of SDP. Although the AHPND outbreak limited conclusive assessment of growth and production, the observed improvement in FCR, immunity, and in Vibrio reduction indicates that dietary SDP may enhance shrimp health under farm conditions.

Assessment of Eutrophication in Middle-Lower Chao Phraya River (2020–2022)

2025-06-24T14:40:50+07:00

This study investigated eutrophication in the Chao Phraya River from 2020 to 2022, focusing on ten monitoring stations between Ayutthaya and Samut Prakan. Distinct seasonal dynamics associated with the monsoon were observed. During the wet season (May–November), agricultural and urban runoff elevated BOD, suspended solids, and nutrient concentrations. In contrast, during the dry season (December–April), reduced freshwater discharge intensified salinity intrusion. Hypoxic conditions, with dissolved oxygen (DO) frequently dropping below 2 mg·L⁻¹ near the river mouth. Nutrient enrichment–particularly dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP)–was strongly associated with phytoplankton blooms, especially near the salinity front where chlorophyll-a concentrations peaked. Nutrient levels increased downstream, driven by untreated discharges from urban, agricultural, and industrial sources. Wastewater nitrification increased nitrate levels, while nitrate overall comprised 41.36% of the total DIN. Peaks in phosphate and total dissolved phosphorus (TDP) followed agricultural runoff, notably in November 2020. Principal component analysis (PCA) revealed clear spatial distinction between middle and lower river stations, with the lower section characterized by elevated nitrogen, phosphorus, and chlorophyll-a concentrations. The AARL-PC Score (a trophic state index) supported these findings, showing consistently high trophic scores in downstream stations indicative of eutrophic conditions, particularly during June and July 2020. Overall, the results indicate a worsening ecological condition compared to historical records and highlight the urgent need for integrated pollution control and sustainable river basin management to protect this tropical urban river.

Dietary Resin Acids Oil Enhances Immunity, Stress Response, and Intestinal Integrity in Juvenile Red Tilapia (Oreochromis niloticus x Oreochromis mossambicus) Challenged with Aeromonas hydrophila

2025-08-29T16:31:03+07:00

The effects of dietary resin acid oil (RAO; Progres®, AB Vista, UK) on intestinal integrity, stress response, and immunity of red tilapia (Oreochromis niloticus x Oreochromis mossambicus) were evaluated during an Aeromonas hydrophila immersion challenge. The experiment followed a completely randomized design (CRD) with three treatments and three replicates. A total of 90 red tilapia (14.65–15.07 g) were randomly distributed into nine aquaria and fed diets containing RAO at 0 ppm (control), 350 ppm (R350), and 700 ppm (R700) three times daily for two weeks. Dietary RAO supplementation significantly reduced serum cortisol and markedly increased hemoglobin concentrations compared to the control (p<0.05). Hemoglobin levels in the control, R350, and R700 groups were 3.92±0.10, 4.29±0.02, and 4.38±0.10 g·dL^-1, respectively. Corresponding cortisol levels were 131.90±27.90, 64.74±3.99, and 63.55±8.66 μg·mL⁻¹, with RAO groups showing values less than half that of the control (p<0.05). Intestinal Aeromonas counts were significantly lower in R700 group (6.06±0.43 CFU·mL^-1) than in the control (7.20±0.09 CFU·mL^-1) and the R350 groups (7.02±0.14 CFU·mL^-1) (p<0.05). Histological analysis revealed that the RAO-fed fish exhibited longer intestinal villi and reduced tissue degeneration in both the intestine and liver under pathogen stress. These findings demonstrate that dietary RAO at 350–700 ppm improves the stress response and protects intestinal and hepatic tissues of red tilapia. Therefore, RAO shows promise as a natural alternative for disease management in aquaculture.