Seagrass conservation in a dynamic tidal creek system: Balancing creek stability and nutrient loads for sustainable...

Conservation and restoration of seagrass habitats in the coastal blue carbon ecosystem is gaining attention worldwide due to its carbon dioxide sequestration ability. The present study investigates the impact of various environmental stressors on the growth of tropical seagrasses, specifically Halophila Ovalis and Halodule Uninervis, across different phases of geomorphological transformation in a tidal creek along the meso-tidal western Bay of Bengal. Evaluating seagrass growth pattern under various scenarios such as open creek (OC), close creek at the initial phase and final phase (CCI & CCF), and reopen creek (ROC) conditions, the study reveals that the CCF phase of the creek condition exhibits distinct environmental conditions, including lower pH, salinity and dissolved oxygen, coupled with higher nutrient concentrations. While the increased concentrations of total suspended solids, chlorophyll-a, phytoplankton biomass, and total organic carbon surpassed the environmental limits. Subsequently, chlorophyll-a, phytoplankton biomass, and total organic carbon were positively correlated with nutrient levels during the CCI. Halophila Uninervis and Halophila Ovalis biomass was higher in the close creek system and significantly decreased from the initial to later phase due to the biomass of phytoplankton on epiphytes and seagrass shoots. Model estimated stability of the tidal creek mouth resulted in an influx of gross volume of seawater 0.904 × 10⁵ m³ by dredging to widen the creek mouth by 15.5 m over the existing mean width, keeping mean creek depth unchanged. The study reflects sustainable management of maintaining the stability of creek mouth ecosystems to facilitate effective seagrass-bed management for further implication of regional significance and carbon sequestration.