Department of Zoology

Study of Zooplankton diversity in two selected lakes in Dhaka city, Bangladesh

Sun, 09 Aug 2026 00:00:00 GMT

Study of Zooplankton diversity in two selected lakes in Dhaka city, Bangladesh Sikder, Shilpi Rani Urban aquatic ecosystems are essential components of the urban environment, playing crucial ecological roles such as water purification, habitat provision, and biodiversity support. Despite their immense significance, these ecosystems face numerous challenges due to climate change and anthropogenic pressures. Therefore, this study aimed to investigate the zooplankton diversity in Dhanmondi and Ramna Lakes, two major urban water bodies in Dhaka, Bangladesh, to understand the influence of different environmental parameters and seasonal changes on the abundance and composition of zooplankton between April 2022 and August 2023. Zooplankton were sampled from eight stations per lake during the dry and wet seasons using a 64-μm plankton net, and water quality parameters (temperature, pH, DO, conductivity, salinity, TDS) were measured in situ. Quantitative estimation and identification were conducted using Sedgewick–Rafter counting and standard taxonomic keys. Statistical analyses included ANOVA, correlation, and multivariate regression. A total of 53 taxa were recorded, with 34 taxa in Dhanmondi and 19 in Ramna. Branchiopoda were the dominant group in both lakes (53–55%), while Bdelloidea and Insecta were least abundant. Seasonal variation showed consistently higher dominance of Branchiopoda in both seasons, whereas Bdelloidea and Flagellata remained low. Water quality comparison revealed a significant difference only in TDS (p < 0.001). Correlation analysis showed strong negative relationships between temperature and DO, while regression indicated DO and pH as the main predictors of zooplankton abundance, explaining 36–37% of the variation.This findings are not only vital for preserving biodiversity but also for ensuring the proper management of these two vital urban ecosystems as it revealed the zooplankton community dynamics as well as their seasonal variability. Furthermore, the findings of this study will inform improved conservation and management practices so that the urban lakes continue to thrive and provide essential ecological services. This thesis is submitted for the degree of Master of Philosophy.

Ichthyo diversity of Jamuna river, Sirajganj, Bangladesh

Sun, 09 Aug 2026 00:00:00 GMT

Ichthyo diversity of Jamuna river, Sirajganj, Bangladesh Akter, Mst. Ashifa 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. This thesis is submitted for the degree of Master of Philosophy.

Toxicity of formaldehyde and formalin against the oriental latrine fly chrysomya megacephala (Fabricius,1794) (Diptera:calliphoridae)

Sun, 09 Aug 2026 00:00:00 GMT

Toxicity of formaldehyde and formalin against the oriental latrine fly chrysomya megacephala (Fabricius,1794) (Diptera:calliphoridae) Prodhan, Salwa This thesis is submitted for the degree of Master of Philosophy.

Parasitic health risk associated with ecosan toilet manure, wastewater, and flood -runoff water in and around Dhaka city

Tue, 04 Aug 2026 00:00:00 GMT

Parasitic health risk associated with ecosan toilet manure, wastewater, and flood -runoff water in and around Dhaka city AKTER, TAMANNA Rapid urbanization in Dhaka, Bangladesh, has led to high population density, inadequate sanitation, and increased exposure to parasitic pathogens, posing significant environmental and public health risks. This study investigates the prevalence, spatial distribution, and environmental transmission pathways of parasitic organisms in ecosan toilet manure, wastewater, and flood runoff water, with particular emphasis on ecosan sanitation systems. The research was conducted in two phases (2017–2019 and 2022–2023) to capture temporal and spatial variations in contamination. A mixed-methods approach was applied, combining quantitative laboratory analysis with qualitative field investigations. Standard parasitological techniques, including microscopy, flotation, and concentration methods, were used to quantify helminth eggs (eggs per gram, EPG) and protozoan cysts (eggs per liter, EPL). Qualitative data were collected through focus group discussions (FGDs) and key informant interviews to assess sanitation practices and hygiene behaviors. Results revealed a high level of environmental contamination, with overall parasitic prevalence exceeding 60% across all sample types. The results indicated that eco-san manure from peri-urban wards (Keraniganj and Savar) exhibited the highest helminth egg counts (135 ± 10 and 115 ± 12 EPG, respectively). Wastewater samples from urban slum areas (Kamrangirchar) showed moderate contamination levels (95 ± 9 EPL). In contrast, flood-prone wards (Badda and Demra) recorded significantly higher parasitic loads in runoff water (150 ± 15 and 165 ± 18 EPL, respectively; ANOVA, F = 72.47, p = 0.0136). GIS-based spatial analysis further identified flood-prone areas as major contamination hotspots. Multiple parasite groups were detected, including protozoa, cestodes, and nematodes, with common organisms such as Hymenolepis nana, Ascaris lumbricoides, Trichuris trichiura, Entamoeba spp., and Giardia spp. Due to methodological limitations, some organisms were reported at the genus level or categorized as “parasite-like structures.” Seasonal variation indicated increased contamination during the rainy season due to flooding and enhanced pathogen dispersion. Qualitative findings highlighted limited awareness of safe compost handling, inadequate sanitation practices, and increased exposure risks during flooding events. Overall, parasitic contamination was strongly influenced by sample type, environmental conditions, and human behavior. This study underscores the need for integrated sanitation management, improved ecosan practices, effective wastewater treatment, flood-risk mitigation, and community-based health education to reduce environmental contamination and associated health risks. The adoption of advanced molecular diagnostic techniques is recommended to enhance the accuracy of parasite identification in future research. This thesis is submitted for the degree of Doctor of Philosophy.