Seaweed farming for food and nutritional security,climate change mitigation and adaptation,and women empowerment:A review

Seaweed is a promising marine macroalgae of the millennium,providing various ecological,social,and economic benefits.At present,seaweed production reached 35.8 million t from farming,accounting for 97%of global seaweed output,with a world market of US$11.8 billion.Seaweeds are an excellent source of nutritious human food because of their low lipid content,high minerals,fibers,polyunsaturated fatty acids,polysaccharides,vitamins,and bioactive compounds.Many seaweed sub-products offer unique properties to develop various functional foods for the food processing industries.In the perspective of climate change mitigation,seaweed farms absorb carbon,serve as a CO_(2)sink and reduce agricultural emissions by providing raw materials for biofuel production and livestock feed.Seaweed farming system also helps in climate change adaptation by absorbing wave energy,safeguarding shorelines,raising the pH of the surrounding water,and oxygenating the waters to minimize the impacts of ocean acidification and hypoxia on a localized scale.Moreover,it contributes substantially to the sustainable development of the economic condition of coastal women by providing livelihood opportunities and ensuring financial solvency.This review paper highlights the significance of seaweed farming in global food and nutritional security,mitigation and adaptation to global climate change,and women empowerment within a single frame.This review paper also outlined the major issues and challenges of seaweed farming for obtaining maximum benefits in these aspects.The main challenges of making seaweed as a staple diet to millions of people include producing suitable species of seaweeds,making seaweed products accessible,affordable,nutritionally balanced,and attractive to the consumers.Various food products must be developed from seaweeds that may be considered equivalent to the foods consumed by humans today.Lack of effective marine spatial planning to avoid user conflicts is vital for expanding the seaweed farming systems to provide aquatic foods and contribute globally for mitigation and adaptation of climate change impacts.Hence,women’s empowerment through seaweed farming is primarily constrained by the lack of technical knowledge and financial resources to establish the coastal farming system.All the information discussed in this paper will help to understand the critical needs for large-scale seaweed farming for climate resilience mariculture,potentials for global food security,and future research on various aspects of seaweed farming and their diverse utilization.

Characterization of geometry and depleting carrier dependence of active silicon waveguide in tailoring optical properties

Changes in refractive index and the corresponding changes in the characteristics of an optical waveguide in enabling propagation of light are the basis for many modern silicon photonic devices. Optical properties of these active nanoscale waveguides are sensitive to the little changes in geometry, external injection/biasing, and doping profiles, and can be crucial in design and manufacturing processes. This paper brings the active silicon waveguide for complete characterization of various distinctive guiding parameters, including perturbation in real and imaginary refractive index, mode loss, group velocity dispersion, and bending loss, which can be instrumental in developing optimal design specifications for various application-centric active silicon waveguides.

Multivariate morphometric investigation to delineate species diversity and stock structure of mud crab Scylla sp. along the coastal regions of Bangladesh

Despite the importance of mud crab species(genus Scylla)in both coastal aquaculture and artisanal fisheries,knowledge of the species diversity and stock structure of mud crab population for their sustainable management across the coastal region of Bangladesh remains obscure.Therefore,the present study was conducted to delineate the diversity and stock structure of mud crab species based on the 24 morphometric length measurements and 27 morphometric ratios data collected from the three coastal regions(Chittagong,Cox’s Bazar and Bagerhat)of Bangladesh.Based on the taxonomic keys,majority of the species(about 82.4%)were identified as S.olivacea,while the remaining(about 17.6%)was S.serrata.In consistent to our preliminary analysis,both the univariate proportion and multivariate analysis of the collected morphometric lengths and ratios data also distinctly divided the mud crabs population into two multivariate spaces as S.serrata and S.olivacea.For the further analysis of the stock structure of these two species,data were subjected to the univariate ANOVA,multivariate ANOVA,Canonical Variate Analysis(CVA),and Principal Component Analysis(PCA)according to their collection sites.Scatter plots of CVA scores between CV1 and CV2 and PCA scores between PC1 and PC2 showed that the individuals of both species clearly made clusters into three multivariate spaces with minimum overlaps according to their collection sites.In morphometric traits Linear Discriminant Function Analysis(LDFA),the average percentage of correctly classified(PCC)into the original groups of the S.olivacea and S.serrata was 100%.For stock discrimination,the average PCC into their original groups of collection sites were 100%and 99%for the S.olivacea and S.serrata,respectively.Finally,dendrogram based on the Euclidean distances consistently separated S.olivacea and S.serrata and stock structures similar to other multivariate analyses.In conclusion,our study shows that S.olivacea is the dominant mud crab species and S.serrata is the minor one,and the stock discrimination of each species should be considered in the management and conservation policy of these species along the coastal region of Bangladesh.