Jahangir Sarker

REVIEW OF THE SCIENTIFIC PAPER STRENGTHS: * COMPREHENSIVE SCOPE: * The review covers a wide range of toxic metals/metalloids (As, Cd, Hg, Pb, Cr, Ni) in meat across multiple African countries, providing a broad perspective on contamination risk...

Certain benthic polychaetes, such as species within the genus Namalycastis, are employed in the diet of gravid shrimps in aquaculture due to their amino acids and highly unsaturated fatty acid content, enhancing the quality of gravid shrimp. Despite its importance in the rapidly developing shrimp culture industry, the population parameters of this economically valuable species are unknown. Therefore, the present study examines the population parameters of Namalycastis fauveli to assess its occurrence, growth, recruitment, exploitation level, and stock status in Bangladesh. Monthly samplings of N. fauveli and environmental variables were collected from five sites of the Cox’s Bazar coast using a square-shaped mud corer with a 0.093 m² (or 1.0 ft²) mouth opening from August 2020 to July 2021 to measure or estimate. Within the 8.0–30.0 cm depth range of the intertidal zone, polychaete samples were collected from the sediment. The results showed negative allometric growth (b < 3), but there was a significant L–W relationship (p < 0.05, r² = 0.43 to 0.94). The estimated L_∝, K, and ϕ were 22.05 cm, 0.99 year⁻¹, and 2.69, respectively, while total mortality (Z) was 4.56 year⁻¹. It was calculated that the fishing mortality and capture probability proportionally increased with the total length at a certain age. Recruitment mostly occurred in October and March, and temperature had a greater impact than salinity. The evaluated exploitation level (E = 0.57) indicated that the stock was overexploited. Thus, the above results provide some valuable information for shrimp farmers and stakeholders, as well as for policymakers in the move towards restoration, species conservation, and efficient management of N. fauveli natural stocks.

Aquaculture expanded to a great extent in Bangladesh through the conversion of agricultural lands due to high profitability resulting in land-use conflicts. The present study is the first initiative to elucidate the impacts of aquaculture on agricultural farms of greater Noakhali (Noakhali, Feni, and Lakshmipur), Bangladesh. Soil and water samples were drawn from 240 selected farms from fish farms (FF), near land (NL), distance land (DL), and control sites. Soil and water quality parameters were analysed following standard methods. A pre-coded structured questionnaire-based interview of farmers was performed from July 2017 to March 2018. Organic matter, organic carbon, total nitrogen, and pH (soil and water) of FF showed significant influence on its surrounding agricultural lands but sulfur, boron, and potassium did not show such kind of influence in all three districts. Total fish production and gross profit were found higher in large fish farms (32.19 MT/year and 238.24%) compared to medium and small fish farms. NL's total crop production and gross profits also showed the same pattern but DL’s showed the opposite pattern. Aqua farms negatively impacted agriculture in terms of cropping patterns but showed an increasing rate for HYVs (High Yield Variety) of rice in greater Noakhali.

Seasonal changes in feeding habits of hilsa (Tenualosa ilisha) were studied monthly in 2019 in the upper Meghna estuary, Bangladesh, through gut content analyses. Tychoplanktonic diatoms followed by copepods were abundant in all months and size groups of hilsa. The inverse relationship between niche breadth and relative length of the gut revealed hilsa consume a variety of food at their early stages while their feeding habit changes towards diatoms during the adult stage with the development of gill rakers. Young hilsas prefer mostly tychoplanktonic diatoms (Aulacoseira sp., Triceratium sp., Nitzschia sp., Synedra sp., and Coscinodiscus sp.) and copepods (Pseudodiaptomus sp.). However, adult hilsas rejected Aulacoseira sp. during their spawning season. Ingested sand grains correlated with tychoplankton, revealing their food value from epipelic microalgae and bacteria clinging to them and epibenthic foraging by young hilsas. Thus, this study revealed that young hilsas primarily feed on tychoplanktonic diatoms and copepods from water and near bottom of the upper Meghna estuary during January to June while later stages with the development of gill rakers allow hilsas to feed on planktonic diatoms. Epibenthic feeding needs to be considered more fully in evaluating the biology of hilsa and, perhaps, other clupeids, and in evaluating possible human impacts on this foraging habitat.

Halda is a 98 km-long tidal freshwater river of Bangladesh, which has a unique feature since it is the only natural breeding ground and the sole source of fertilized eggs of Indian Major Carps globally. The present study firstly summarizes the impact of environmental stressors to understand phytoplankton abundance, community, and their diversity in Halda River, Bangladesh. Environmental data as seasons (Winter, Monsoon), water depths, temperature, pH, Salinity, dissolved oxygen, and nutrients were collected and analyzed from the Halda River in January 2019 and August, 2020. Thirty-four phytoplankton genera, comprising five classes, were identified from the Halda River, Bangladesh. A two-way ANOVA was performed to analyze the effect of Monsoon and Winter on the physicochemical and biological parameters. It revealed that there was a statistically significant ((F9, 160)= 34.999, p= 0.0) interaction between Monsoon and Winter on the observed parameters. The water temperature (F 125.31, Fcrit 4.130, p= 0.0) and nutrients (F 11.118, Fcrit 2.322, p= 0.0) revealed significant change in the phytoplankton concentrations in the Halda River. As of the temperature and nutrients, water depths also significantly (F 1.790, Fcrit 1.719, p= 0.0) affect the phytoplankton communities in the Halda River showing the highest and lowest cell density in the surface and bottom water, respectively.

Hilsa shad (Tenulosa ilisha) is Bangladesh’s most important single-species fishery that contributes to 11% of total catch and employment for millions of people. However, heavy metals (HMs) toxicity in the edible organs of T. ilisha and their plausible public health threats have received weak attention. To provide insights on this issue, we determined, using ICP-MS, the concentration of Zn, Cu, Cr (VI), Pb, and Cd in the edible organs of five different sizes of T. ilisha and the surface water collected from the Padma–Meghna River confluence, Chandpur (Bangladesh). Multivariate analysis indicated that T. ilisha gills and liver contained higher HMs than muscle, and the surface water was below the safety limits. The study revealed that only Cr crossed the safety limits and bioaccumulated in the smaller-sized gills and liver. To assess the public health risks, target hazard quotient (THQ), total THQ (TTHQ) and carcinogenic (CR) risks were calculated. Only Cr imposed non-carcinogenic risks to consumers, while TTHQ showed higher chronic health risks. There was no CR risk measured for consumers, except for the largest-sized gills for children. Randomly positive relations between HMs and sizes were found; whereas, consistently positive relations were found among the tissue types. The outcomes of our study may aid policymakers in managing pollutants, especially the Cr sources in the greater Chandpur regions.

Marine fish is a major source of Omega-3 fatty acids (Eicosapentaenoic acid, EPA andDocosahexaenoic acid, DHA), which are now recognized worldwide as a key factor in human health. Thepresent study was conducted to depict the status of marine fish consumption in three districts (namely Feni,Lakhsmipur, and Noakhali) of greater Noakhali district, Bangladesh using a questionnaire survey in 240households during the month of May-June, 2018. Almost all the households (96%; n=230) consumed marinefishes. Price, availability, presence of inter-muscular bones, and characteristic fishy smell were the majorbarriers to marine fish consumption in the studied area. The average quantity of fresh and dried marine fishconsumed was 53.35 g/capita/day and 3.71 g/capita/day, respectively in greater Noakhali. Marine fresh fishconsumption in the three districts differed significantly (p<0.001). The highest (80.20±32.72 g) and thelowest (40.02±27.90 g) amount of marine fresh fish consumption were observed respectively, in Lakhsmipurand Feni district and the highest (4.19±7.47 g) and the lowest (3.47±4.87 g) amount of dried marine fishconsumption were observed respectively, in Feni and Noakhali district. About 32% of consumers consumedmarine fresh fish 3 to 6 times in a week whereas 46% of consumers consumed dried fish once in a month.Consumers belonging to high-income households consume more marine fish (57.11 g) than the low-incomehouseholds (49.33 g). Harpadon nehereus, Tenualosa ilisha, Otolithes cuvieri, Polynemous paradiseus, Mugilcephalus, Oxyurichthys microlepis, and Sillago domina were among the most frequently consumed marinefishes in the studied areas. About 76% of respondents perceived eating marine fish was good for health.Increased availability, lower price and creating awareness on health benefits may lead to increasing marinefish consumption among local people in the region.

The present study assessed the water quality parameter insights from phytoplankton and nutrientregimes of the Shitalakhya River based on three sampling stations. The ranges of water temperature,transparency, dissolved oxygen, pH, TDS, phosphate-phosphorus, nitrite-nitrogen, nitrate-nitrogen, andsilicate were 27.86±0.249 °C to 29.83±0.612 °C, 42.33±0.471 to 31.33±0.942 cm, 6.35±0.232 to5.88±0.066 mg/L, 7.62±0.008 to 7.52±0.018, 63.33±4.714 to 40±8.164 mg/L, 0.52±0.020 to0.34±0.016 mg/L, 0.06±0.012 to 0.01±0.004 mg/L, 0.12±0.008 to 0.05±0.004 mg/L, and 0.12±0.004to 0.07±0.001 mg/L respectively. The values of transparency, TDS, nitrite, nitrate, and silicate variedsignificantly while other parameters showed non-significant (p>0.05) among three stations. The results alsoindicated the presence of 27 genera belonging to five major groups- Bacillariophyceae (9), Chlorophyceae(8), Euglenophyceae (5), Dinophyceae (3), and Cyanophyceae (2). The dominant phytoplankton group wasthe Bacillariophyceae (38%), followed in order by Chlorophyceae (26%), Euglenophyceae (19%),Dinophyceae (12%), and Cyanophyceae (5%). Shannon-Weiner species diversity index (H?) ranged from 2.31to 2.99 (phytoplankton) indicating the water body is moderately polluted. Overall, maximum density(46.66×103 cells L-1) of phytoplankton was observed at S2 followed by S3 (35.23×103 cells L-1) and S1(20.95×103 cells L-1). The fluctuation of the physico-chemical parameters and phytoplankton density of theriver could be attributed to the high influx of nutrients into the river as a result of discharging nutrient reachwater from. Monitoring of these activities within the river and education on the wise use of the water isrecommended.