The bioaccumulation of trace elements and heavy metals in aquatic organisms is a critical environmental concern due to its potential impact on ecosystem health and human safety. This study investigated the level of trace elements and heavy metals bioaccumulation in Labeo rohita and Mystus seenghala from the River Jhelum in the district Khushab, Punjab, Pakistan. The concentration of calcium, magnesium, iron, nickel, copper, arsenic, cadmium, zinc, chromium, manganese, cobalt, and lead in the gills, liver, and muscle tissues of these fish was measured using inductively coupled plasma-mass spectrometry. Then, the extent of contamination and its possible health risks were assayed. Our findings indicate significant variations in the elemental and metal concentrations among different organs and between species, reflecting their diverse feeding habits and habitats. The health risk assessment based on the estimated daily intake, estimated weekly intake, maximum permissible intake, target hazard quotient, hazard index or total target hazard quotient, health risk index, and target cancer risk revealed potential risks to human consumers of these fish. This study emphasizes the need for continuous monitoring, as new data and insights are crucial for understanding and mitigating these risks. Strict regulatory measures are also necessary to safeguard public health and preserve the ecosystem of Jhelum River.

Non-steroidal anti-inflammatory drugs (NSAIDs) are increasingly recognized as emerging contaminants in freshwater ecosystems. However, their effects on aquatic invertebrates remain poorly investigated. This study evaluated for the first time both cellular and biochemical responses of the red swamp crayfish (Procambarus clarkii) following a long-term exposure to indomethacin, a widely used NSAID. Specimens were exposed for 28 days to 2.5, 5, and 10 mg/L, and biomarkers indicative of cytotoxicity and oxidative stress were evaluated. Viability of both hemolymph and hepatopancreas cells was assessed using Trypan Blue and Neutral Red assays, while oxidative stress biomarkers, including superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST), and malondialdehyde (MDA), were analyzed in hepatopancreas, gill, and muscle tissues. The results showed that indomethacin exposure induced significant, tissue-specific cytotoxic and oxidative responses. Notably, hepatopancreas cell viability decreased significantly at lower concentrations, with partial recovery at the highest dose, suggesting a possible hormetic effect of the contaminant. Oxidative stress biomarkers exhibited concentration-dependent changes: SOD and MDA levels were significantly altered in the hepatopancreas; GST activity was affected in the gills, and GPx activity increased in muscle at higher concentrations. Haemocyte viability remained unaffected, indicating resilience of circulating cells. The Integrative Biomarker Response-Threshold (IBR-T) index highlighted both hormetic and classical dose-response trends, depending on tissue type. From an ecological perspective, these findings suggest that P. clarkii may tolerate relatively high indomethacin concentrations without systemic oxidative collapse, potentially supporting its persistence and competitive advantage in contaminated habitats. However, the hepatopancreas sensitivity indicates possible sublethal metabolic impairment, which could affect long-term fitness and population dynamics. Overall, this study provides novel insights into the ecotoxicological effects of indomethacin in a keystone invasive species and underscore the importance of tissue-specific biomarker analysis for environmental risk assessment.

High-mountain lakes are freshwater ecosystems situated above the tree line which are known for their remote locations and limited accessibility. These ecosystems host simplified biotic communities primarily concentrated in the littoral zone and dominated by benthic macroinvertebrates that serve as bioindicators of environmental pressures. A two-year monitoring investigation was performed in July 2022 and July 2023 at Nero Lake (Cesana Torinese, Northwest Italy). Five sites along the lakeshore were selected for sampling physicochemical water parameters and macrobenthos. All collected data were analysed to compare trends across years and within specific sites. The results revealed that Nero Lake exhibited consistent macrobenthic communities across the two years studied, but significant differences were observed in its microhabitats. This suggests that substrate type and physicochemical water parameters strongly influence community composition. Chironomidae larvae and Mollusca were the dominant species, showing distinct associations with different substrates and environmental factors from one year to another. These findings contribute to our understanding of the intricate relationships between benthic macroinvertebrates and their environments, highlighting the necessity of detailed, small-scale assessments to comprehend ecosystem dynamics and develop effective conservation strategies.

Microplastic (MP) pollution is an emerging environmental concern, yet its occurrence in remote high-mountain ecosystems remains poorly understood. This study investigated MP contamination in fish from Nero Lake, an alpine lake in northwestern Italy. Between 2023 and 2024, a total of 33 specimens of Salmo trutta, Phoxinus lumaireul, and Salvelinus fontinalis were analyzed. MPs were detected in 84% of specimens in 2023 and in 93% in 2024. Filaments were the predominant particle type, while polyethylene, polypropylene, and polyethylene terephthalate were the most common polymers. In 2024, polyamide was also detected and showed the highest Polymer Hazard Index (PHI = 12.22), indicating a high hazard risk (Grade III) and elevated toxicological potential. Contamination Factor values exceeded 10 in S. trutta, and Pollution Load Index values frequently surpassed 1, both suggesting established contamination. However, the limited number of specimens, particularly for P. lumaireul and S. fontinalis, reduces statistical power and increases the risk of Type II errors. Although no significant interspecific differences in MP counts were observed, results should be interpreted with caution. Larger sample sizes are recommended but remain difficult to obtain in alpine environments. These findings highlight the vulnerability of remote lakes to both local and long-range MP pollution sources.