Silent Disruption: Mechanistic Pathways of Microplastic Toxicity in Aquatic Organisms

Aquatic ecosystems are increasingly at risk from microplastic contamination, which has a wide range of toxicological impacts on creatures at different trophic levels. The purpose of this study is to thoroughly summarise the most recent research (2013–2024) underlying the toxicity of microplastics to aquatic life, with a focus on disturbances to the body immune, respiratory, reproductive system, genetic makeup, and behaviour, and to clarify the cellular and molecular processes, with a focus on oxidative stress induction, endocrine interference, immunological dysregulation, and transgenerational effects.Major scientific databases such as PubMed, Scopus, Web of Science, Google Scholar, and Elsevier were used in the process for a structured literature review. Peer-reviewed research focusing on experimental or observational evidence of microplastic-induced biological impacts in aquatic organisms was one of the inclusion criteria. Non-English articles, non-empirical findings, and studies that just addressed environmental distribution without biological assessment were not included. Mechanistic biomarkers (such as ROS production and antioxidant enzyme regulation), reproductive metrics, behavioural endpoints, and exposure pathways were all taken into consideration while extracting the data.The Findings exhibit that microplastics affected immunological responses, interfered with mitochondrial function, clogged respiratory structures like gills, disrupted endocrine signalling pathways, and caused oxidative stress through the overproduction of reactive oxygen species. Potential transgenerational consequences are suggested by reproductive deficits, such as decreased gamete quality, decreased fertility rates, and developmental abnormalities, in conjunction with epigenetic alterations. Ecological effects are amplified by behavioural changes that impact food, predator avoidance, and locomotion. Limitations include limited long-term field-based studies, heterogeneity in experimental methods, and variance in particle size. The Future perspective of this study will be to emphasise the necessity of multigenerational studies, sensitive biomarker development, standardised methodology, and integrative ecological risk assessments, and to preserve aquatic biodiversity and ecosystem stability, stronger Microplastics; Toxicity; Aquatic Organisms; Physiological disruption, Behavioural Modification; Environmental Pollution.