RESUMO
The southwest coastal belt of Bangladesh is characterized by a fresh and saline water interaction which gives rise to a discrete inter-saline freshwater convergence zone (ICZ). Hydrology and farming along this transition zone is influenced by upstream and downstream abiotic factors including salinity intrusion and water flow. To better understand the changing geography of the transitional ICZ line and the relative influence of these hydrological events on farming therein, the recent study compared relative changes from 2010 to 2014 based on qualitative and quantitative survey work with 80 households of 4 villages (Shobna, Faltita, Badukhali and Rudaghora) from Khulna and Bagerhat district. Contrary to the conventional hotcake climate change induced salinity intrusion the study found a significant decrease in saltwater influx and increased freshwater volume in the ICZ villages, reflecting a seaward movement trend. Farmer perception shifted to low saline and freshwater in many areas where it was high saline and medium saline in 2010. The factual and perceived salinity were varied from 1 ± 0.44 to 2 ± 0.77 ppt in the studied villages. To confront the condition farmer diversified their farming pattern from single crop like either only shrimp or prawn culture to concurrent culture of shrimp-prawn, shrimp, prawn and rice with an increased production of (68-204 kg/ha), finfish (217-553 kg/ha) and dyke crop (92-800 kg/ha). Thus, affecting the socioeconomic condition of the farmer with an increase in average monthly income, reported for the better-off classes in 2014, ranged from 14,300 to 51,667 BDT and for the worse-off ranged from 5000 to 9900 BDT. In contrast, this average monthly income was 9500- 27,000 for better-off and 3875 - 8600 for worse-off classes, reported in 2010. Besides, farming areas (average 17% for better-off and -0.5% for worse-off) and land leasing (average increment rate per ha 50%) also increased among the surveyed farmers, reported in 2014 compared to 2010. In addition, several adaptation strategies like unrefined salt use, change of water use, diversification through prawn, finfish and dyke crops along with traditional shrimp and overall land use change have a positive impact on farmer's economic and nutritional security as well as farming intensity. The study showed a unique attributes of salinity extrusion in micro-level of ICZ line where farmers intensified farming system with indigenous knowledge to secured their livelihoods.
RESUMO
The effects of in-feed probiotics on growth performance, haematological parameters, gut microbial content, and morphological changes to pangasius fish were assessed. The trial had three phases, i.e., larvae to fry (20 days), fry to fingerlings (45 days), and grow-out phase from fingerlings to marketing (90 days). The stocking densities were 400 m-3, 200 m-3, and 12 m-3 for phases 1, 2, and 3, respectively. Phases 1 and 2 were conducted in hapas in the same pond, whereas phase 3 was performed in concrete tanks. The in-feed probiotic was administered at a rate of 0.2 g kg-1 of feed three times per day in phases 1 and 2 only. In phase 3, in-feed probiotics was not applied to any groups. The treated group exhibited higher growth performances (p < 0.05) than the control in all three phases of experiment. The survival % in phase 1 and 2 were found significantly (p < 0.05) higher in treatment groups. This indicates that pangasius nurserers would benefit from using probiotics as a safeguard to increase fry survival to a greater extent. Two haematological parameters including red blood cells (RBC) and white blood cells (WBC) levels were found significantly (p < 0.05) higher in treated groups in phase 2 and 3, while glucose and hemoglobin level were found significantly (p < 0.05) higher in the treated groups during phases 2 and 3, respectively. The gut microbiota content was relatively higher in the treated groups in phase 2 and 3. Histological findings indicate that the use of probiotics during the nursing phases of pangasius induced a positive change in the intestinal morphological structures. The positive impacts of probiotics on the phase 3 confirmed an immediate and long-term growth performance and health of pangasius.
RESUMO
We investigated aquaculture production of Asian tiger shrimp, whiteleg shrimp, giant river prawn, tilapia, and pangasius catfish in Bangladesh, China, Thailand, and Vietnam by using life cycle assessments (LCAs), with the purpose of evaluating the comparative eco-efficiency of producing different aquatic food products. Our starting hypothesis was that different production systems are associated with significantly different environmental impacts, as the production of these aquatic species differs in intensity and management practices. In order to test this hypothesis, we estimated each system's global warming, eutrophication, and freshwater ecotoxicity impacts. The contribution to these impacts and the overall dispersions relative to results were propagated by Monte Carlo simulations and dependent sampling. Paired testing showed significant (p < 0.05) differences between the median impacts of most production systems in the intraspecies comparisons, even after a Bonferroni correction. For the full distributions instead of only the median, only for Asian tiger shrimp did more than 95% of the propagated Monte Carlo results favor certain farming systems. The major environmental hot-spots driving the differences in environmental performance among systems were fishmeal from mixed fisheries for global warming, pond runoff and sediment discards for eutrophication, and agricultural pesticides, metals, benzalkonium chloride, and other chlorine-releasing compounds for freshwater ecotoxicity. The Asian aquaculture industry should therefore strive toward farming systems relying upon pelleted species-specific feeds, where the fishmeal inclusion is limited and sourced sustainably. Also, excessive nutrients should be recycled in integrated organic agriculture together with efficient aeration solutions powered by renewable energy sources.