Ichthyo diversity of Jamuna river, Sirajganj, Bangladesh

Abstract

Millions of people depend on Bangladesh's river systems, which are among the most productive and biodiverse in the world. However, fish populations are under risk due to frequent environmental changes, which renders baseline research crucial for conservation. This study examined the seasonal variations of the fish species in the Jamuna River, Bangladesh, over a 12-month period of about 12-months from July 2022 to June 2023. The research aimed to understand how seasonal changes in this large and significant tropical river system affected fish diversity, abundance, and community composition. The Jamuna River, known for its dynamic hydrological conditions and diverse aquatic habitats, provides a unique environment to study the complex interactions between fish species and their environment. Understanding these seasonal patterns of the ichthyo diversity is crucial for maintaining the health and sustainability of fish populations, which are an important resource for local communities and ecosystems. Over the study period, a total of 79 distinct fish species, belonging to 10 orders and 27 families were identified and monitored to determine their abundance across different seasons. The study employed heat maps and diversity indices to analyze seasonal abundance patterns. Heat maps offered a visual representation of the distribution and concentration of species over time, while diversity indices quantified changes in species richness (number of different species), evenness (relative abundance of species), and overall diversity. These analytical tools provided a comprehensive overview of how fish communities varied in response to seasonal changes in the river's flow, temperature, and habitat conditions. The findings revealed clear and distinct seasonal trends in fish abundance. Several species, such as Hyporhamphus limbatus and Xenentodon cancila, were found to be more abundant during the rainy season, which corresponds to the monsoon period in Bangladesh. On the other hand, species such as Setipinna phasa, Chanda nama, Gagata youssoufi were observed to have higher abundances in the dry season, when water levels are lower. The findings from this study underscore the importance of understanding the natural seasonal variability of fish populations. Further research is needed to explore the specific ecological drivers behind these seasonal patterns and to evaluate the long-term impacts of environmental changes on fish communities in the Jamuna River and for developing management and conservation strategies.