Decoding ecosystem health: by integrating ecological indicators and trophic modelling of a tropical micro-tidal...

Estuaries are critical interfaces between marine and fluvial environments, making them exceptionally vulnerable to natural and human impacts. This study applied an Ecosystem Mass-Balance model to analyze the structure and function of the food web in the Chettuva estuary, a small, micro-tidal system on India's southwest coast known for its dense mangroves, clam, and fish resources. The model included 17 functional groups, revealing that commercially valuable species like mullets, clams, and shrimps had the highest ecotrophic efficiencies, indicating they are the most intensely exploited and utilized groups. Network analysis suggests the Chettuva estuary has a relatively simple food web structure, characterized by a connectance index of 0.38 and a system omnivory index of 0.23. The low Finn's cycling index (1.95%) signifies limited material recycling, suggesting the ecosystem is currently unstable and highly vulnerable to disturbances. However, a moderate ascendency (56.24%) suggests the system retains a significant capacity for recovery. The results from the Chettuva model were compared with nine other tropical estuarine models to provide a broader assessment of structural and functional characteristics within Indian estuaries. This trophic analysis serves as a vital reference for developing informed management strategies aimed at maintaining ecosystem stability and supporting sustainable fisheries.