Assessment of benthic diversity and estuarine ecological quality is becoming increasingly important. Estuaries are not only highly productive and variable environments, but they are also areas of high anthropogenic perturbations. In this study, benthic macrofauna were sorted, identified and analyzed from a freshwater-dominated tropical estuary along the Bay of Bengal to assess their community structure, distribution and functional guilds, and to uncover the environmental drivers influencing their distributional patterns. Results revealed that the studied physio-chemical variables (DO, pH, alkalinity and temperature) were significantly varied (p < 0.05) among the sites. Capitella sp. was dominant (18%) of the forty morphospecies recorded, indicating organic richness of the area. The ANOVA results revealed that macrobenthic density differed significantly (p < 0.01) between the study locations, and diversity indices (Shannon diversity index, H′) also differed significantly (F_4,12 = 5.89; p = 0.02). The benthic density decreased from the head to the mouth, which could be related to salinity fluctuations and large freshwater discharges. Upstream sites were completely segregated from downstream and mid-estuarine sites, according to cluster analysis (CA). The SIMPER results clarified the site grouping pattern, showing that Mysis-1 spp., Capitella spp. and Nephtys-1 were the most significant contributors. From the communities, five functional trophic groups were identified where deposit feeders were the most dominant (66.44%). Most of the macrobenthos had strong positive correlations with DO (r = 0.92) and water temperature (r = 0.86) and a negative correlation with soil pH (r = −0.28), per correlation and CCA analyses. Individually, soil pH (r = 0.88) and alkalinity (r = 0.898) showed strong positive correlation with Capitella sp. and Chironomus sp.2. The above results indicate that macrobenthos of this estuary do not follow the usual pattern of spatial distribution, and they are structured by DO, alkalinity and soil pH. In addition, dominance of some pollution indicator species (Capitella sp. and Chironomus sp.) and deposit feeders indicates a poor ecological condition of the estuary.

Aims: The study was carried out to understand the current status of used drugs and chemicals in fish hatcheries and farms in Feni district, Bangladesh. Methodology: Data were collected by pre-defined questionnaire interview, personal contact with farm and hatchery owners, and representatives of pharmaceutical companies by market survey. Results: Twelve different groups of chemicals were being used for disease treatment and fish health management. Traditionally used chemicals were Lime, Salt, Potash (KMnO4) and Melathion. Although Malachite green hazardous to human health, it was widely used in hatcheries. Geotox, JV Zeolite, Amoxy fish, Megavit Aqua, Square aqua premix, Orgavit, Pure Oxy, Vitamin gel, O2-Marine etc. were widely used new chemicals. Renamycin was the most widely (36% farmer) used antibiotic followed by Oxysentin 20%, Orgamycin15% and Otetra vet power 50. Conclusion: Nearly all farmers did not apply chemicals and drugs at proper doses because they thought the higher the doses applied the more and rapid will be the action. It was found that manufacturers and retailers of the products often neglected to provide farmers with necessary information regarding active ingredients and relevant instructions for safe and efficient use of aqua-drugs and chemicals. Recommended use of chemicals apparently brings good result but indiscriminate use of chemicals can be extremely detrimental to fish and our environment as well as to us and therefore, all of us should be aware of the proper use of chemicals.

The study was conducted to assess the impact of traditional jute retting process on the fish health and fish biodiversity in the six upazilas of Chandpur district, Bangladesh. Data were collected from respondents through face to face interviews and focus group discussions. All of the jute farmers in the study ...