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.

Dataset describing the growth pattern, amino acid and fatty acid profile of five indigenous marine microalgae species of Bangladesh.

This paper presents the data on the growth pattern, amino acid, and fatty acid profile of five (5) selected indigenous marine microalgae (Chaetoceros sp.; Isochrysis sp.; Skeletonema sp.; Nannochloropsis sp.; and Tetraselmis sp.) of Bay of Bengal, Bangladesh. The microalgae species were cultured in f/2 Guillard's medium with maintaining standard physico-chemical parameters. The growth pattern was determined for all the microalgae as a prerequisite for further necessary experimental works. All the species were mass cultured using the same culture medium and harvested (centrifuging method), and dried (60 â„ƒ for 12 h) at their stationary phase. Finally, the amino acid and fatty acid analyses were performed. In many contexts, the amino acid and fatty acid data showed significant differences (p < 0.05) among these experimental species. However, by understanding these experimental species' nutritional profiles, one can easily choose the desired one that is most appropriate for their intended application.

Abundance and characteristics of microplastics in sediments from the world's longest natural beach, Cox's Bazar, Bangladesh.

This study aimed to provide the first description of the presence, quantity, and diversity of microplastics (MPs) in intertidal sediments from the world's longest natural beach, Cox's Bazar. MPs were extracted from 24 surficial sediment samples through the density separation method, and identification was carried out using a stereomicroscope. Results showed that the abundance of MPs varied from 200 to 378.8 items kg-1 with the mean abundance of 368.68 ± 10.65 items kg-1. Fibers were the dominant (53%) MPs in this study, followed by films (20%) and fragments (12%). The dominant plastic particle color was purple (18%), followed by pink (14%) and red (7%), with shapes that were mainly filamentous (53%) and irregular (41%). The majority (59%) of the MPs measured were 1-5 mm in size, followed by 0.5-1 mm (27%) and <0.5 mm (14%).