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Fish Physiological Responses to Environmental Stressors

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A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Ecotoxicology".

Deadline for manuscript submissions: 5 June 2026 | Viewed by 5450

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Special Issue Editor

Dr. Jun Wang

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Guest Editor

College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China
Interests: fish; plankton; physiology; toxicology; osmoregulation

Special Issue Information

Dear Colleagues,

Aquatic ecosystems face escalating threats from diverse environmental pollutants, jeopardizing ecological stability and sustainability. As vital bioindicators and keystone species, fish exhibit high sensitivity to contaminants. These contaminants disrupt critical physiological processes (neuroendocrine, metabolic, immune, and reproductive functions) of fish, potentially leading to oxidative stress, DNA damage, and population decline. Understanding such cross–scale interactions is critical for predicting ecosystem-level risks.

This Special Issue seeks to advance interdisciplinary research at the nexus of physiological ecology and environmental toxicology. We invite original studies addressing:

Mechanistic toxicity pathways: Molecular/cellular drivers of physiological dysfunction (e.g., oxidative stress, genomic instability, endocrine disruption).
Bioaccumulation and trophic transfer: Contaminant fate across biological hierarchies.
Ecophysiological adaptation: Resilience mechanisms at individual/population levels.
Emerging threats: Ecological risks of novel pollutants (nanomaterials, antibiotic resistance genes).

Dr. Jun Wang
Guest Editor

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Keywords

fish ecotoxicology
physiological disruption
oxidative stress biomarkers
ecological risk assessment
bioaccumulation dynamics
endocrine disruption
population changes

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Published Papers (4 papers)

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Research

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13 pages, 4260 KB

Open AccessArticle

Physiological Responses and Post-Exposure Recovery of the Hepatopancreas in Nile Tilapia Following Copper Exposure

by Xueyi Wu, Wenqi Xie, Zhengfan Chen, Ziyi Jiang, Jiazhe Jiang, Lei Xie and Yongpu Zhang

Toxics 2026, 14(5), 412; https://doi.org/10.3390/toxics14050412 - 9 May 2026

Viewed by 734

Abstract

Copper is a common pollutant in aquatic environments. Excess copper in water can enter aquatic organisms through respiration, feeding, and adsorption, thereby exerting serious adverse effects on their health. In this study, NEW Genetically Improved Farmed (GIFT) Nile tilapia (Oreochromis niloticus L.) was used to explore the effect of copper on the hepatopancreas and post-exposure recovery. Acute exposure was simulated via an intraperitoneal injection of 3.75 mg Cu²⁺/kg body mass, while physiological saline injections served as the control. Samples were collected on days 1, 7, 14, and 21 post-exposure to evaluate growth performance, histopathological changes, antioxidant enzyme activities, and the expression of oxidative stress-related genes in the hepatopancreas. The results show that body length and mass increased within 21 days of the injection and copper exposure did not significantly affect fish growth. On day 1 after copper injection, numerous vacuoles appeared in hepatopancreatic tissues. On day 14, congestion and obvious hepatic sinusoids were observed. However, on day 21, the tissue structure showed gradually recovery. Compared to the control group, superoxide dismutase (SOD) activity was significantly higher in the exposed group on days 1, 14, and 21, and SOD gene expression was significantly elevated on day 21. Catalase (CAT) activity was significantly higher on day 7, and the expression of the CAT gene increased significantly on days 1 and 21. Glutathione peroxidase (GSH-Px) activity decreased significantly on day 7, whereas GPX gene expression increased significantly at the same time point. No significant difference in acetylcholinesterase (AChE) activity was observed during the experiment. In conclusion, copper administered via intraperitoneal injections induced significant activation of the antioxidant defense system and histopathological damage in the hepatopancreas of tilapia. Although tissue damage gradually recovered over time, the activation of the antioxidant defense system partially persisted. Ultimately, copper exposure did not significantly affect growth indicators such as body length and mass. These results advance our understanding of copper toxicity in farmed fish and provide a scientific reference for safe aquaculture production. Full article

(This article belongs to the Special Issue Fish Physiological Responses to Environmental Stressors)

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11 pages, 1921 KB

Open AccessArticle

An Exploratory Investigation into the Effects of Methanol and Ethylene Glycol on the Growth and Development of Medaka (Oryzias melastigma) and Yellowstripe Goby (Mugilogobius chulae)

by Zhenxiong Yang, Minxia Zhang, Tongfei Xu, Shasha Qi, Lu Tang, Juan Guo, Chuqian Lu and Shaobo Ma

Toxics 2026, 14(5), 380; https://doi.org/10.3390/toxics14050380 - 29 Apr 2026

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Abstract

This study aimed to investigate the acute and chronic toxic effects of two thermodynamic inhibitors (methanol and ethylene glycol) widely used in deep-sea oil and gas operations on two typical marine fish species, the medaka (Oryzias melastigma) and the yellowstripe goby (Mugilogobius chulae), to assess their potential ecological risks in marine environments. The 96-h median lethal concentration (LC₅₀) was determined through acute toxicity tests. A 56-day chronic toxicity test was conducted to evaluate the effects on fish growth (body length) and the antioxidant defense system, specifically the activities of superoxide dismutase (SOD) and catalase (CAT). The results revealed marked species-specific differences. In terms of acute toxicity, medaka exhibited exceptionally high sensitivity to ethylene glycol (LC₅₀ 15.77 g/L), while the yellowstripe goby showed greater tolerance (LC₅₀ 22.17 g/L). Chronic exposure led to concentration-dependent growth inhibition in both species, and medaka showed significantly higher mortality than yellowstripe goby. Under methanol exposure, medaka exhibited significantly higher mortality (30–45%) than yellowstripe goby (5–20%). When exposed to ethylene glycol, medaka showed markedly high mortality (55–85%), while yellowstripe goby mortality remained below 15%. At the molecular level, both chemicals induced oxidative stress, but the response patterns of the antioxidant enzymes (SOD and CAT) were species-specific, indicating differences in toxic mechanisms and detoxification capacities. Methanol and ethylene glycol pose non-negligible ecotoxicological risks to marine fish, and the toxicity intensity is influenced by species specificity, exposure concentration, and the effectiveness of the antioxidant defense system. This study emphasizes that environmental risk assessments for such chemicals must fully account for species differences and sublethal effects, providing critical scientific evidence for formulating precise environmental safety standards for marine hydrocarbon exploitation. Full article

(This article belongs to the Special Issue Fish Physiological Responses to Environmental Stressors)

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17 pages, 3272 KB

Open AccessArticle

Assessing the Kynurenine–Tryptophan Ratio (KTR) and CYP1 Activity in Longnose (Catostomus catostomus) and White Suckers (Catostomus commersonii) Exposed to Petroleum-Derived Contaminants from the Alberta Oil Sands Region

by Laiba Jamshed, Amrita Debnath, Amica Marie-Lucas, Thane Tomy, Gregg T. Tomy, Tim J. Arciszewski, Mark E. McMaster and Alison C. Holloway

Toxics 2025, 13(10), 862; https://doi.org/10.3390/toxics13100862 - 11 Oct 2025

Viewed by 1013

Abstract

In the Alberta Oil Sands Region (AOSR), environmental stressors linked to oil sands industrial activity may have significant and species-specific impacts on local wildlife. This study evaluated the kynurenine–tryptophan ratio (KTR) as a potential biomarker for environmental exposure in longnose suckers (Catostomus catostomus) and white suckers (Catostomus commersonii) collected from various locations within the AOSR. The relationship between KTR and CYP1 enzyme activity (ethoxyresorufin-O-deethylase; EROD) was assessed alongside biometric indices, including gonadosomatic index (GSI), hepatic somatic index (HSI), and fat content. Both species exhibited increased EROD activity when exposed to oil sands natural deposits and potential industrial activity, indicating significant polycyclic aromatic compound (PAC) exposure. However, KTR changes were species-dependent: longnose suckers showed an inversely proportional relationship between KTR and EROD, while white suckers displayed a directly proportional correlation. Longnose suckers downstream of both municipal waste and industrial activity exhibited significant increases in GSI and fat content, with KTR varying more consistently by location rather than sex, suggesting that KTR may be a more reliable marker for location-based exposure. Species-specific differences in KTR and EROD relationships may be influenced by the distinct environmental requirements of each species, and their differing sensitivities to environmental conditions, including temperature, turbidity and flow conditions, during sampling periods. These findings illustrate the complexity of interpreting environmental biomarkers in wildlife and emphasize the need to consider ecological requirements and environmental conditions. Further research is necessary to validate this biomarker across different years and conditions and enhance its application in environmental monitoring and conservation efforts. Full article

(This article belongs to the Special Issue Fish Physiological Responses to Environmental Stressors)

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Review

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38 pages, 861 KB

Open AccessReview

Impacts of Microplastics on the Early Life Stages of Fish: Sources, Mechanisms, Ecological Consequences, and Mitigation Strategies

by Imran Ullah, Haotian Chen, Jun Wang, Hashmi Kaiser, Abdallah A. Basher, Jiajia Li and Xuexia Zhu

Toxics 2026, 14(1), 27; https://doi.org/10.3390/toxics14010027 - 26 Dec 2025

Cited by 6 | Viewed by 1962

Abstract

Microplastics represent an emerging threat to aquatic environments and organisms, as they infiltrate water systems, are ingested by marine species, and cause physical harm, endocrine disruption, and bioaccumulation up the food chain, potentially impacting biodiversity and human health. Aquatic ecosystems face considerable harm from microplastic pollution because fish in the early developmental stages, including embryos, larvae, and juveniles, are more susceptible due to their immature physiological and detoxification systems. This review aims to comprehensively explore the impacts of microplastics on the early life stages of fish. Aquatic environments receive primary and secondary MPs from urban runoff and industrial waste, together with degraded plastics, which affect fish embryos and larvae via direct ingestion, surface adhesion, and trophic transmission pathways. The physical impact of MPs causes digestive tract blockages that reduce hatching success and create developmental problems in fish organs, but chemical toxicity develops from plasticizers, heavy metal leaching, and pollutant adsorption, which causes oxidative stress, endocrine disruption, and metabolic dysfunction. Survival rates decrease because exposure causes fish to perform poorly during swimming activities and make limited efforts to avoid predators. The small dimensions and high chemical reactivity of MPs increase their bioavailability, which promotes tissue penetration and leads to accumulation at different levels of the food chain. This comprehensive review emphasizes that we need to establish uniform detection protocols, long-term exposure research, and effective strategies to control MP pollution. The resolution of these difficulties remains essential for protecting fish populations, as well as for protecting biodiversity and minimizing seafood contamination risks to human health. Full article

(This article belongs to the Special Issue Fish Physiological Responses to Environmental Stressors)

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