STUDIES ON THE ZOOGEOGRAPHICAL CONFIGURATIONS OF THE INLAND FISH HABITATS IN BANGLADESH

Abstract

Conservation of the inland fin fish in Bangladesh has been compromised due to a lack of zoogeographic division and ecofaunal relationship identification. The study attempted to identify finfish fauna, establish ecofaunal relationships, estimate zoogeographic division, and assess the water quality at 13 stations in Bangladesh's 8 major water bodies, i.e., the Brahmaputra and Jamuna River from the Brahmaputra Jamuna River Basin, the Ganges River and Padma River from the Ganges-Padma River Basin, the Hakaluki Haor and Meghna River from the Surma-Meghna River Basin, and the Kaptai Lake and Sangu River from the Basin of Chittagong Region from June 2018 to February 2022. Systematic Index of Freshwater Finfish (SIFF), Grounded Theory or Narrative Analysis, Mapping and Satellite image analyses, Multivariant statistical techniques like Jaccard's dichotomy coefficient, cluster analysis, Non-metric Multidimensional Scaling (nMDS), Principal Component Analysis (PCA), and Water Quality Index (WQI) were used in this investigation. Permutation tests have been conducted to justify the statistical validation and p-value estimation. A total of 193 finfish species belonging to 19 orders, 50 families, and 121 genera were identified from the study areas. These species represent 6 critically endangered, 16 endangered, and 21 vulnerable finfish species. The Brahmaputra River, Jamuna River, Ganges River, Padma River, Hakaluki Haor, Meghna River, Kaptai Lake, and Sangu River represented the alluvial riverine, braided riverine, meandering riverine, dynamic riverine, marsh wetland, estuarine, lacustrine, and mountain stream ecosystems, respectively—distinct fish fauna and characteristics of these eight ecosystems established ecofaunal relationships. The Brahmaputra-Jamuna River Basin, Ganges-Padma River Basin, Surma-Meghna River Basin, and the Basin of Chittagong Region were identified as inland fish zoogeographic zones in Bangladesh. This zonation was based on river and drainage system divisions, finfish faunal dispersion, ecosystem diversity, and distributional dissimilarities of finfish families, genera, species, and endemic species. Significant seasonal fluctuations in water quality have been observed across all study areas. The water quality of eight inland fish habitats was assessed using seven indices, with EC, TDS, alkalinity, and temperature being the principal ones. Policymakers should adopt a conservation plan based on zoogeographic zones. Priority should be given to improving the principal components of water quality and protecting threatened finfish species that inhabit single habitats.