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Coastal wetlands including salt marshes are among the most productive ecosystems on Earth. They are known for improving the quality of coastal water and provisioning coastal fisheries. However, this ecosystem is under potential threat due to urban coastal land reclamation, limited sediment supply, increased nutrient/eutrophication, and sea level rise. Therefore, restoration efforts to protect the degraded salt marsh habitat are considerably increasing worldwide. In this paper, we present an overview of salt marsh restoration techniques and success indicators. Published scientific literature in English language was collected by searching the most relevant keywords from popular search engines, namely, Google Scholar, Scopus, and Mendeley to get the information about salt marsh restoration techniques and success indicators. This study comprehensively reviewed data from 78 peer-reviewed papers. Results indicated that much of the salt marsh was restored through assisted abiotic strategies (e.g., recovery of tidal exchange, managed realignment, and sediment level amendment). A total of 214 indicators were found, spanning over six major ecological attributes such as structural diversity, ecosystem functions, physical conditions, species composition, external exchange, and absence of threat. Author keywords analysis revealed several hotspots for recent research (e.g., 16 s rRNA, fungi, microbial communities, carbon accumulation, and blue carbon). This paper proposes a model for restoring degraded salt marsh, as well as tracking their success. The information presented here will assist the marine ecosystem restoration practitioners in getting a comprehensive understanding of salt marsh restoration success evaluation.

Unraveling planktonic community patterns and their linkage with the surrounding ecology is essential for aquatic resource management. Studies on the tintinnid microzooplankton in most of the marine waters of Malaysian South China Sea (SCS) are scarce though the trophic role of this community is well established. Thus, we aimed to investigate on spatiotemporal pattern of composition, abundance, and biomass of tintinnid, and how this community patterns are regulated with the basic ecological parameters. A total of 46 species were recorded, mostly in southwest monsoon (33 species) during the study period from May 2016 to April 2017. Tintinnopsis was counted as major genera with 19 species, and Tintinnopsis radix, a species that reported as neritic-estuarine origin calculated as the most abundant (11%) in our study. Both the space and time were equally responsible for differences in species richness, diversity, abundance, and biomass. However, species richness variation was not influenced by space–time interaction, whereas we observed season (time) and species size worked as a strong factor in terms of biomass variations. Accordingly, the higher mean abundance (Station 3; 132,116 ind m−3 in southwest monsoon) did not scale up to the bigger mean biomass (Station 4; 1.317 µgC L−1 in Inter-monsoon April). Among the ecological variables, the strongest influence was observed in the tintinnid community by pH, dissolved oxygen and salinity mostly during southwest monsoon around Bintulu-Mukah areas. Similarly, species-specific affinity to pH was also observed by most of the species. In addition, Favella campanula showed affinity to salinity, turbidity, and conductivity, while T. cylindrica and T. gracilis were driven by the temperature and dissolved oxygen. The findings of this research may help to explore comprehensive food web dynamics in future ecosystem studies in SCS region.

This study was carried out to evaluate the population growth and egg ratio of Brachionus rotundiformis by feeding with three different diets, i.e., live microalgae Nannochloropsis sp., Baker’s yeast, and powdered spirulina. A total of nine conical flasks of 1 L volume were divided into three treatment groups for determining the feeding performance for eight consecutive days. Each experimental group was stocked with B. rotundiformis at an initial density of 10 ind. mL−1. Water temperature, pH, salinity, and light were maintained at (24–29) °C, (7.5–8.5), 30 ppt, and 4000 lx, respectively. Feed was provided twice per day at 9:00 AM and 7:00 PM. The highest mean (±SE) population growth of rotifer was achieved at the end of the culture period (on the 8th day) fed live Nannochloropsis sp. (122 ± 12 ind. mL−1), which was significantly higher compared to the Baker’s yeast and powdered spirulina (p 0.05). The highest mean (±SE) egg ratio of B. rotundiformis was observed in the live Nannochloropsis fed group (0.89 ± 0.01) at the end of the rearing period, which was significantly higher than that of Baker’s Yeast and powdered Spirulina fed group (p

Size frequency, length-weight relationships (LWRs), length-length relationships (LLRs), and relative condition factor (Kn) was studied in an estuarine fish the Bengal yellowfin seabream, Acanthopagrus longispinnis (Val.), from Hatiya Island in the Meghna River estuary. Specimens were caught with fixed purse nets of two mesh sizes (0.2 to 0.5 inch and 2.0 to 2.5 inch) from January to March 2020. The total body length of A. longispinnis ranged between 5.8 and 9.3 cm throughout the sampling period. The length-weight relationships for A. longispinnis was highly significant (p < .001), and the adjusted r 2 value was 0.921. The calculated growth coefficient (b) for A. longispinnis was 3.163, which indicated a hyperallometric growth pattern. The length-length equation TL = 1.1384 SL + 0.4899 for unsexed A. longispinnis was highly significant (p = 0.001, r2 = 0.951). There were no significant variations in relative condition factors among the specimens of different length classes (5.5–9.5 cm). No information regarding length-weight or length-length relationships for A. longispinnis was previously reported in FishBase. Our estimated LWR and LLR parameters for A. longispinnis can be useful for management and conservation purposes of this estuarine species.

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One of the most promising economic arenas in the coming decades is the ocean and there are currently numerous initiatives to the ‘blue economy’ discourse that revolves around the argument that small-scale fishers’ livelihoods require greater attention. To synthesize current scientific knowledge and address prevailing research gaps surrounding this discourse, I conduct a scoping review of global literature on the blue economy, blue growth, social equity, and Small-Scale Fisheries (SSF) analyse different international policy papers and national-level blue economy plans. To explore the need for further research, this review focuses on how different aspects of the blue economy risks lead to inequity in the pursuit of ocean sustainability. Based on the initial content analysis, I identify evidence for undermining social equity and justice related to the ocean and find that social equity is often overlooked in national-level blue economy and blue growth initiatives. This overlooking leads to or accelerates processes of coastal and ocean grabbing, displacement, dispossession, and exclusion which strongly impact the livelihoods of marginalized coastal communities, particularly, small-scale fishers in various parts of the world. The collected evidence suggests that there is a missing link between international policy deliberations and national-level implementation plans in the blue economy context. Numerous studies claim that critical re-thinking of policies is required to ensure the sustainability of blue economy trajectories. Unchecked economic growth in the ocean as in other realms can reinforce inequities and unjust and inequitable resource distribution patterns. To pre-empt, mitigate, and resolve likely conflicts, deeper insights are needed to address the impacts of the blue economy and blue growth on coastal livelihoods. I suggest investigating the causes of conflict and further research on how governance responds to sustain small-scale fisheries while embracing the blue economy and blue growth agendas.

Coastal zones are the most dynamic feature of earth surface in which lithosphere, hydrosphere and atmosphere gets into contact with each other. Such dynamic process should be monitored with great importance as a large portion of the world’s population is living along the coastal zones. This paper focuses on delineation of the changes in the coastal land areas of Chittagong in Bangladesh through the shifting of coastline. Chittagong coastal area is around 245 km with an unbroken 125 km gently slopped sandy sea beach in Cox’s Bazar. However, due to both the natural phenomenon and human interventions, coastline in these areas has been changing gradually. These changes have occurred in relation to land biomass, erosion and accretion rate. Therefore, shoreline geometry analysis can help understand such dynamic coastal process. Several satellite images from Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) were used for the long term coastline change analysis. The digital shoreline analysis (DSA) using ArcGIS 10.1, and image rectification, atmospheric correction, edge separation techniques between earth surface and water surface using ENVI software were used in this analysis. DSAS was used as a reliable statistical approach for the rate of coastline change. The result shows that changes in dynamic changes due to erosion and accretion have been impacting the morph-dynamics in the study area. The maximum accession rate was 3.6 km and 1.9 km at different section points and on the contrary the maximum erosion at several section points was 0.37 km and 3.3 km at the time interval of 1989 to 2009 and 2009 to 2014, respectively. Overall, it was found that the area was affected with huge rate of accretion and increase in the landmass of the Chittagong area till the year 2009 but later on till the date of 2014 the erosion rate of the area again increased. The findings of this study can help policy makers to make decisions in delineating new islands emerging at the sea boundary of Bangladesh and planning for better coastal management.

Hydrogen sulfide (H2S) is a toxic pollutant and harmful to human health. Industries such as pulp and paper manufacturing, rayon production, natural gas extraction and refining, and crude petroleum refineries generate waste gas streams with high H2S concentrations. Both physico-chemical and biological methods are used for H2S removal from the gas stream. Biological methods offer several advantages such as environmental friendly, less expensive and require simple operation and maintenance compared to physico-chemical methods. In this study, a hydrophilic hollow fibre membrane (HFM) based bioreactor configuration has been tested for biological H2S removal. Three reactors were fabricated and operated for ~ 3 months where two reactors were used for biological conversion process and the third reactor was used for abiotic process. The effective membrane area of a HFM module used in each reactor was 0.0138 m2. The bioreactors demonstrated efficient gas-liquid mass transfer through the HFM module and achieved ~ 99% removal efficiency with an elimination capacity of ~ 17.0 g m-3 h-1. The H2S flux of the bioreactor was ~ 0.20 g m-2 day-1 which was ~ 9 times higher than the abiotic reactor for an inlet H2S concentration of ~ 0.90 g m-3. The overall mass transfer coefficient value for the biotic process was 17.2 µm s-1 which was ~ 25 times higher than the abiotic process. The bioreactors demonstrated both microbial attached growth on the membrane surface and suspended growth in the liquid phase. Microbial community analysis confirmed the presence of diverse sulfur-oxidizing bacteria at genus level including Acinetobacter, Dechloromonas, Hydrogenophaga, Rhodopseudomonas and Sulfurospirillum. Moreover, the enrichment of other bacterial genera such as ammonia-oxidizing (e.g. Nitrosospira), organic matter degrading (e.g. Trichococcus) and methanogenic (e.g. Methanosaeta) microorganisms demonstrate the diverse microbial ecology of the sludge growing in the bioreactor.

Raw biogas generated in the anaerobic digestion (AD) process contains several undesired constituents such as H2S, CO2, NH3, siloxanes and VOCs. These gases affect the direct application of biogas, and are a prime concern in biogas utilization processes. Conventional physico-chemical biogas purification methods are energy-intensive and expensive. To promote sustainable development and environmental friendly technologies, biological biogas purification technologies can be applied. This review describes biological technologies for both upstream and downstream processing in terms of pollutant removal mechanisms and efficiency, bioreactor configurations and different operating conditions. Limitations of the biological approaches and their future scope are also highlighted. A conceptual framework Driver-Pressure-Stress-Impact-Response (DPSIR) and Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis have been applied to analyse the present situation and future scope of biological biogas clean-up technologies.

Industrial fishing in Bangladesh is operated by wooden trawler (ice trawler) and steel made trawler known as freezer trawler. There is significant lack of valuable information on freezer trawler fishing data though it contributes a remarkable portion in national marine capture fisheries which is not negligible. This study aims to investigate the historical trends in freezer trawler fishing of Bay of Bengal. Data from different sources were compiled and analyzed to complete this study. A total of 91 industrial freezer trawlers were recorded from the deep-sea fishing industry in Bangladesh. 72 of them are fish trawlers and 19 are shrimp trawlers. In 1990, there were only 5 freezer trawlers with a total capacity of 490 ton which increased up to 21,737 ton in 2014 by 91 trawlers. The calculated production of marine capture fisheries by freezer trawlers increased from 2940 ton (1990) to 150113 ton (2014) that is about 1 to 21 % of the FAO landings and 0.5 to 12 % of the reconstructed total national production of marine capture fisheries respectively. A total of 1.83 million ton of fisheries products were captured from the Bay of Bengal in last two decades (1990- 2014). This study output will be helpful as a baseline database of freezer trawler for marine capture fisheries in Bangladesh.Res. Agric., Livest. Fish.3(1): 217-226, April 2016

Youth as a change agent and strong force in social actions can play a significant role in the development process of a society endowed with different socioeconomic problems like inequality, injustice, social violence, violation of human rights, etc. Raising youths’ social awareness, in this regard, is the important point to be considered as a quality pathway to the sustainable development of a society. Now, a society can be more cognizant of social phenomena because its individuals are more connected to each other than before with diverse new media technologies. So, the debate over the role of new media to bring positive changes is drawing the attention of scholars and theorists. Through incorporating primary and secondary data, this study explores to what extent Bangladeshi youths are being aware of social issues within the new media sphere. Both the quantitative measurement and qualitative interpretation had been reciprocally considered in the study. The findings arose from a convenience sample survey on 157 youths inclusive of 11 in-depth interviews with new media users. The study suggests a more critical understanding of new media driven social awareness and has been concluded with some guidelines for the policymakers to use new media for the cognitive functioning of the young generation so that they engage themselves in civic activism.

The main aim of this study was to evaluate the performance of an aerobic biofilter packed with compost for the removal of gas-phase hydrogen sulfide (H2S). After 52 d of operation, the biofilter was re-packed by replacing a certain portion (25%, v/v) of the existing compost with biochar and its performance was tested. The steady and transient performance of the biofilter was evaluated by varying the H2S concentrations from 0.1 to 2.9 g m−3 at an empty bed residence time (EBRT) of 119 and 80 s, respectively. The maximum elimination capacity (ECmax) of the compost and compost + biochar biofilter were ∼19 and 33 g m−3 h−1, respectively, with >99% removal efficiency at an EBRT of 119 s. The compost biofilter showed a quick response to shock loads and the critical load to the biofilter during the shock loading step was ∼81 g m−3 h−1.

Owing to the problem of antibiotic resistance and subsequent reluctance of using antibiotics, probiotics use in aquaculture is becoming popular day by day. One experimental design with 150 days culture period of Macrobrachium rosenbergii was conducted with 3 treatments maintaining stocking density of 02/m2, 03/m2 and 04/m2 in T1, T2 and T3 respectively. Each of the treatments was with 3 replicates where each replicate was segmented into two parts to separate probiotics and non-probiotics based culture system. The higher body weight of 63.7 g was recorded in lower SD of T1 in comparison to lower body weight of 55.7 g and 43.0 g in higher SD of T2 and T3 respectively for probiotics application segments. The average body weight of 55.7 g, 46.7 g and 37 g respectively were found for the same treatments in non-probiotics segments. The average survival rate of 69.3%, 62.7% and 58.3% were recorded in probiotics and 68.3%, 63% and 57.7% respectively in non-probiotics treatments. Average daily growth rate and gross production were found better in probiotics than that of non-probiotics segments in all the treatments. Average daily growth rate of T1 was found 0.41 g and 0.36 g respectively for probiotics and non-probiotics segments. Similarly, for T2 and T3 average daily growth rate were found 0.35 g and 0.27 g for probiotics and 0.30 g, 0.23 g for non-probiotics segments respectively. Gross average production showed better result of 103 g/m2/crop in T2 probiotics treated segment than that of other two results of 87.23 g/m2 and 98.10 g/m2 in T1 and T3 treatments respectively where as 74.62 g, 87.23 g and 84.26 g/m2/crop was recorded in T1, T2 and T3 respectively in nonprobiotics treatments. Abiotic parameters in all segments of 3 treatments were within the optimum ranges for M. rosenbergii culture during the study period.

Discard has long been recognized a serious problem in the world’s oceans affecting not only the non-target species but also entire trophic food chain and habitats thus disrupting marine ecosystem functioning. Due to global declines, species of conservation interest (e.g. sharks, rays, turtles, dolphins) which are crucial for maintaining a healthy ecosystem have become a focus of marine conservation in recent years. Although effort has been made to elucidate the historical trends of discards and, its effects on the marine fisheries worldwide, most of these are based on the data-rich developed countries. This has been largely unexplored in many of the developing countries such as Bangladesh, especially for industrial marine fisheries. Here in this study, we tried to fill this knowledge gap using discard data collected from the bottom and mid-water freezer trawler from the marine water of Bangladesh in the Bay of Bengal. It was revealed that both the bottom and mid-water trawling has the similar level of effect on the number of total discarded species of conservation interest (SOCI) although the number of shark discard was significantly higher in bottom trawling. The historical reconstruction of total discards of SOCI from freezer trawler suggests an increase of over six times between 1990 and 2014. The increasing number of hauls (both in the bottom and mid-water trawl) and the increase in the speed at bottom hauling both have a significant negative effect on SOCI especially shark. We suggest a strong implementation of existing laws, increasing the capacity of surveillance and the monitoring systems as well as improved technological fix such as gear modification can substantially lower the discarded bycatch from Bangladesh marine water.