Ecological Modelling and Indicator Assessment of Seasonal Fish Diversity in Bhaluka Beel, West Bengal: Integrating GAM, RDA, and CCA Approaches

Understanding seasonal fish diversity in floodplain wetlands is crucial for effective conservation and management. This study assessed the fish assemblage structure of Bhaluka Beel, a monsoon-influenced floodplain wetland in Nadia District, West Bengal, India, using integrated ecological modelling approaches. Fish diversity was quantified across pre-monsoon, monsoon, and post-monsoon seasons alongside key physicochemical parameters, including temperature, dissolved oxygen, pH, free CO2, alkalinity, and hardness. Generalized Additive Models (GAMs) revealed that temperature and free CO2 negatively influenced Shannon-Weaver, Margalef's, and Pielou's indices, whereas pH exerted a positive effect. Species richness peaked post-monsoon, coinciding with stabilized water conditions after flood events. Multivariate ordination using Redundancy Analysis and Canonical Correspondence Analysis highlighted distinct seasonal community structures and identified dissolved oxygen and pH as key environmental drivers. Pre-monsoon indicator species included Puntius ticto, Clarias batrachus, and Heteropneustes fossilis. Functional guild analysis demonstrated a diverse assemblage of omnivores, carnivores, herbivores, and planktivores occupying pelagic, littoral, and benthic niches. The coexistence of tolerant and sensitive species reflects both ecological resilience and potential vulnerability to environmental stressors. This integrated modelling framework provides a robust tool for evaluating seasonal biodiversity patterns in tropical wetlands and offers practical insights for fishery management, biodiversity conservation, and water quality monitoring under monsoon-driven hydrological regimes.