BIOCHEMICAL RESPONSES OF AQUATIC ORGANISMS TO EMERGING ENVIRONMENTAL CONTAMINANTS: IMPLICATIONS FOR ECOSYSTEM HEALTH AND SUSTAINABILITY

Abstract

The occurrence of emerging environmental contaminants is being observed more frequently in aquatic environments, which can cause biochemical, developmental, endocrine, physiological, and reproductive effects on aquatic species. It is necessary to know the differences between toxicant classes and biological effects types for ecological health evaluation and sustainable environmental management. This study evaluated biochemical responses of aquatic organisms to emerging environmental contaminants by comparing toxicity thresholds across contaminant categories, life stages, and biological endpoints. A quantitative secondary analysis was conducted using an ecotoxicological dataset containing contaminant exposure and biological response records for fish species. After data screening, 491 observations were retained. The lowest observed adverse effect concentration (LOAEC) was used as the primary toxicity endpoint and log₁₀ transformed before analysis. Descriptive statistics, Kruskal–Wallis tests, post-hoc pairwise comparisons, bootstrap confidence intervals, and principal component analysis were applied. Hormone-related contaminants were the most represented group, while developmental, endocrine, and physiological responses were the dominant biochemical endpoints. Toxicity thresholds differed significantly among contaminant categories, life stages, and biochemical response categories. PFAS and plasticizers showed comparatively lower median toxicity thresholds, suggesting greater biological sensitivity. Early life stages exhibited lower thresholds than adults, indicating increased vulnerability during development. Principal component analysis indicated that hormone-related and developmental response pathways contributed to major patterns of variability. The emerging chemicals have different biological impacts on aquatic species, where toxicity depends on the category of contaminant, life stage of the organism, and type of endpoint being studied. Combining toxicity levels and biological impacts would enhance aquatic risk assessment.