Integrated macrobenthic TITAN, AMBI, and M-AMBI indices for assessment of marine ecological quality in the East China Sea

Abstract

Macrobenthic species are effective indicators of marine environmental stress, making them valuable for ecological assessments. This study collected data on macrobenthos and environmental factors in the East China Sea (ECS) during 2019–2020. Through Threshold Indicator Taxa Analysis (TITAN), 21 indicator species were identified, with annelids being the most abundant. A critical dissolved oxygen (DO) threshold (DO <3.71 mg/L) was identified, revealing hypoxic conditions at about 10 % of sites. Depth significantly influenced species distribution, with responses clustering around 50 m. DIN and chlorophyll-a exhibited low thresholds, while TP showed a wider range. The AZTI Marine Biotic Index (AMBI) indicated slightly disturbed ecological conditions, while Multivariate AZTI's Marine Biotic Index (M-AMBI) reflected good overall quality. AMBI provided a broad baseline of ecological health through long-term community responses, while TITAN captured dynamic responses of species to localized environmental pressures. The combination of these three macrobenthic indices complemented each other's limitations, enhancing the comprehensiveness of the assessment, and the findings highlight the importance of integrating these indices to improve marine ecosystem management and provide early warning signals for environmental changes, offering valuable guidance for future conservation and restoration efforts.