Global Research Trend on Dissolved Oxygen as a Water Quality Indicator

Abstract

Dissolved oxygen (DO) is a fundamental indicator of water quality and a key regulator of biological, chemical, and physical processes in coral reef ecosystems. This study investigates global research trends on dissolved oxygen from 2000 to 2025 using a comprehensive bibliometric approach. A total of 738 publications from 276 sources were analyzed through performance metrics and science mapping techniques, including co-occurrence networks, thematic mapping, and conceptual structure analysis. Results reveal a significant increase in scientific output, with an annual growth rate of 12.73%, reflecting growing attention to ocean deoxygenation and its ecological impacts. Dissolved oxygen is identified as an integrative parameter linking ecosystem metabolism, including photosynthesis and respiration, with environmental stressors such as ocean acidification, climate change, and nutrient enrichment. Thematic evolution indicates a transition from organism-level studies to ecosystem-scale and multi-stressor frameworks, where DO is increasingly examined alongside coral bleaching, eutrophication, and reef degradation. Keyword and cluster analyses highlight the dominance of climate-related drivers, while DO remains an emerging but rapidly developing research focus. Conceptual mapping further demonstrates the role of DO in connecting physiological processes with large-scale biogeochemical dynamics. Despite its growing importance, gaps persist in understanding spatial and temporal variability, threshold responses, and interactions with other stressors. The findings emphasize the need for high-resolution monitoring, interdisciplinary research, and integration of DO into coral reef management strategies. Overall, dissolved oxygen is reaffirmed as a critical metric for assessing ecosystem health, resilience, and future trajectories of coral reefs in a rapidly changing ocean.