Occurrence of microplastics in fish gastrointestinal tracts belongs to different feeding habits from the Bangladesh coast of the Bay of Bengal.

The Bay of Bengal (BoB) is home to a range of commercially important species with different food habits and feeding features. Microplastic (MP) contamination in the fish of BoB, like in many other marine environments, is a significant environmental concern. The study aimed to investigate the presence of microplastics (MPs) in the gastrointestinal tracts (GITs) of selected commercial marine fishes from the Bangladesh coast of the BoB. Six fish species (Escualosa thoracata, Tenualosa ilisha, Johnius belangerii, Trichiurus lepturus, Planiliza parsia, and Mystus gulio) were investigated (n = 120) following hydrogen peroxide digestion, and floatation (saline solution) protocols. After analyses, a total number of 696 MPs (dimension 0.3 to 5 mm) were identified. Moreover, the highest occurrence of MPs in fish GITs was found in planktivorous fish (average of 7.7 items/individual), followed by omnivorous (average of 5.2 items/individual), and carnivorous fish (average of 4.6 items/individual) (p < 0.001). However, planktivorous E. thoracata showed the highest number of MPs per g of GIT (average of 30.99 items/g GIT), whereas T. ilisha showed the lowest count (average of 0.77 items/g GIT). Different types of MPs (fibers (19 to 76%), fragments (6 to 61%), films (8 to 35%), microbeads (0 to 5%), and foams (0 to 2%)) were also observed. In terms of the color of MPs, the transparent, black, green, and blue types were the most common. Polymers were found as polyethylene (35 to 43%), polyethylene terephthalate (28 to 35%), polyamide (20 to 31%), and polystyrene (0 to 7%). The study provides a significant incidence of MPs in fish from the Bangladesh part of the BoB, which is very concerning. Therefore, long-term research is indispensable to ascertain the variables affecting the presence of MPs in fish, their origins, and their potential effects on the BoB fisheries. Stringent policies on plastic use and disposal should be strongly urged in this coastal region.

Acidification scenario of Cox's Bazar coast of the Bay of Bengal, Bangladesh and its influence on fish larvae abundance.

Ocean acidification is caused mainly by atmospheric carbon dioxide stored in the ocean. Ocean acidification is considered a major threat to aquatic life, and how it influences the abundance of marine fish larvae is still unclear. This research was designed to measure the current ocean acidification scenario of the Cox's Bazar coast of the Bay of Bengal, Bangladesh, and its probable influence on the abundance of fish larvae. Three research stations were selected: Bakkhali river estuary, Naf river estuary, and Rezu Khal. Monthly sampling was done, and larvae sample was collected from the surface water column (depth: 0.5 m) using a bongo net. Water parameters such as temperature, salinity, total alkalinity, and pH were determined using laboratory protocol. The seacarb package of the R programming language was used to determine ocean acidification factors. The Bakkhali river estuary showed the highest partial carbon dioxide (143.99 ± 102.27 µatm) and the lowest pH (8.27 ± 0.21). A total of 19 larvae families were identified, and the highest larval count was found in Rezu Khal (390 larvae/1000 m3), while the lowest was found in the Bakkhali river (3 larvae/1000 m3). Clupeidae, Myctophidae, and Engraulidae comprised more than 50% of the identified larvae. Blenniidae, Carangidae, Clupeidae, Engraulidae, and Gobiidae were found in all three seasons. Most of the larvae families showed the highest mean abundance under less pCO2. A negative correlation was observed between larvae and acidification factors such as pCO2, HCO3-, and dissolved inorganic carbon (DIC). The study revealed that acidification parameters of the Cox's Bazar coast were not in an acute state for the aquatic organisms' survival, but fish larvae abundance could be declined with raises in the partial carbon dioxide. The results of this study may aid in developing a management plan for conserving Bangladesh's marine and coastal fish.

Floating raft culture of Gracilariopsis longissima for optimum biomass yield performance on the coast of Cox's Bazar, Bangladesh.

Seaweed cultivation is an eco-friendly method and attracts growing interest which needs a multi-criteria approach for its sustainability. In our present study, an economically significant red alga, Gracilariopsis longissima was cultured using a floating raft method on the coast of Cox's Bazar, Bangladesh for a period of 90 days from January to March 2022. The effects of different factors such as rope materials, culture type, raft shape, seeding intensity, harvesting phase and water depth on the biomass yield production of G. longissima were evaluated during a 90-day culture period. The biomass yield production and daily growth rate (DGR% day-1) were estimated to evaluate the possibilities of G. longissima cultures in a floating raft culture method. The range of biomass yield production (3.03-13.37 kg/m2) and DGR (3.08-4.72% day-1) is satisfactory in the floating raft culture method. Different water quality variables, the seasonal appearance of epiphytic algae and a cost-benefit analysis of seaweed culture were also performed. A total of eight epiphytic algal species were recorded, which resulted in major challenges for the growth of Gracilariopsis. The per month income for a seaweed farmer was estimated to be US$175.17 for 20 rafts. Our research concluded that farming of G. longissima in the floating raft method could be successfully performed from January to March on the coast of Cox's Bazar.

Microplastics pollution in the river Karnaphuli: a preliminary study on a tidal confluence river in the southeast coast of Bangladesh.

Bangladesh is a deltaic country in Asia, and its riverine systems ultimately drain into the Bay of Bengal. Plastic is a severe environmental issue for coastal-marine ecosystems due to the indiscriminate usage and discarding of plastic items in the upstream river that eventually find their route into the Bay of Bengal. Microplastics (MPs) are widespread pollutants in almost all environmental compartments, including aquatic environments. This study aimed to quantify and understand the distribution of microplastics in surface water and sediments of the river Karnaphuli, a tidal confluence river adjacent to the Chattogram seaport city of Bangladesh, a highly inhabited and industrial area on the southeast coast of the Bay of Bengal. A manta trawl net (300-µm mesh size) was used to collect surface water samples, while an Ekman dredge was used to collect sediment samples. The concentrations of microplastics in the surface water of the river Karnaphuli during late monsoon, winter, and early summer were recorded to be 120,111.11, 152,222.22, and 164,444.44 items/km2, respectively, while in sediments, those were recorded to be 103.83, 137.50, and 103.67 items/kg, respectively. A higher abundance of microplastics was observed in downstream surface water (228,888.88 items/km2) and sediments (164.17 items/kg). Smaller sizes (0.3 to 0.5 mm) of microplastics were predominant, fibers or threads were the frequent types, and black was the most common color in the river Karnaphuli. The Fourier transform infrared analysis revealed that polyethylene terephthalate (surface water: 22%, sediments: 19%), polyamide (surface water: 15%, sediments: 13%), polyethylene (surface water: 12%, sediments: 18%), polystyrene (surface water: 13%, sediments: 11%), and alkyd resin (surface water: 13%, sediments: 10%) were the most prevalent polymers in the river Karnaphuli. Moreover, there was a moderate positive correlation between MPs abundance in surface water and sediments. Therefore, improved long-term research (in different seasons with horizontal and vertical monitoring) is necessary in order to accurately determine the flux of microplastics from the river Karnaphuli to the Bay of Bengal.

Knowledge, attitudes, and practices on food safety and hygiene of wet and dry fish handlers in Cox's Bazar, Bangladesh.

This study aimed to provide the very first description of the current scenario of knowledge, attitudes, and practices (KAP) concerning the food safety and hygiene subjects among wet fish handlers (WFHs) and dry fish handlers (DFHs) in Cox's Bazar, Bangladesh. Data collection was performed through the application of face-to-face interviews with 234 WFHs and 258 DFHs. The overall score of the correct answer assessed components was 55.95% and 57.05% in WFHs and DFHs, respectively. Among the different knowledge categories, both the respondents showed the highest positive response in the time, temperature, and quality control category and the lowest positive responses noted in the foodborne disease occurrence category. For attitudes, obtained results showed positive attitude with a mean score of 37.82 ± 4.28 and 35.58 ± 5.48 for WFHs and DFHs, respectively. The WFHs gained a mean score of 23.08 ± 4.24 for practices, and the score was 22.78 ± 4.47 in the case of DFHs. A positively significant correlation coefficient (r s) was observed among fish handlers' KAP of 0.326-0.584. Although the association between the three levels was acceptable, several food safety principles and hygiene practices remained unsatisfactory. These findings highlighted the need for rapid action to enhance food safety and hygiene KAP through an intensive training program to assure the production of safe fisheries products for human consumption.

Data on growth, productivity, pigments and proximate composition of indigenous marine microalgae isolated from Cox's Bazar Coast.

Data on growth, productivity, pigments and proximate composition of the four different indigenous marine microalgae (isolated from Cox's Bazar Coast) were collected to compare the growth performance, pigments and nutritional composition. Chlorella sp., Nannochloropsis sp., Tetraselmis sp. and Chaetoceros sp. are the four different marine microalgae. Growth curve was determined as the prerequisite to identify the stationary phase for each of the isolated microalgae. Data on growth curves were collected in terms of cell density and optical density to observe the growth rates and division per day. Isolated species were mass cultured in commercial culture medium. When the culture reached at stationary phase, microalgae were extracted to determine productivity, pigments, and proximate composition. The data of productivity (volumetric, areal and lipid productivity), pigments (Chlorophyll a, b, c, carotenoids, and phycobiliproteins), and proximate composition (protein, lipid, and carbohydrate) were significantly (p < 0.05) different among the four different microalgae. Therefore, this data will contribute to the selection of potential microalgae species through proper characterization for vast industrializations.