Assessment of Spatial-Temporal Patterns of Nutrient Dynamics in Batapady Mangrove Ecosystem, Southwest India

Abstract

This study examines the seasonal and spatial variability of nutrient concentrations in the Batapady mangrove ecosystem (Dakshina Kannada, India), based on monthly surface water sampling from five stations between October 2023 to June 2024. Four key nutrients ammonia-nitrogen (NH₃-N), nitrite-nitrogen (NO₂-N), nitrate-nitrogen (NO₃-N), and phosphate-phosphorus (PO₄-P) were measured alongside environmental parameters including salinity, pH, dissolved oxygen (DO), biological oxygen demand (BOD), and temperature. NH₃-N and PO₄-P exhibited peaks during the summer (NH₃-N 85.15 µg-at/l at S1), while NO₃-N concentrations were highest during early post-monsoon. Nutrient levels and BOD, DO, and salinity were found to be significantly correlated by Spearman correlation analysis, which shows that nutrient release and retention are influenced by hydrological fluctuations and redox conditions. Spatial differences between stations reflected anthropogenic activities and variable flushing. Our findings demonstrate the vulnerability of small, fragmented mangrove stands to nutrient surges and underscore the need for targeted management interventions. Incorporating these monitoring insights into long-term nutrient management will help safeguard mangrove health and ensure estuarine water quality under growing human pressure.