Distribution of trace metals in channel sediment: a case study in South Atlantic coast of Spain

Recently, Sancti Petri channel on the southwestern (SW) part of Iberian Peninsula has been experiencing urban, industrial, and vehicular expansion. Until recently, there have been only few published reports documenting the pattern of metal accumulation in this estuarine sediment. In the present study, trace metals such as Cu, Zn, Ni, Mn, Pb, Co, Cd, As, and Hg concentrations were analyzed from 69 sediment samples collected from 23 sampling sites of the Santi Petri channel. The magnitude of trace metal accumulation found as the following trend: Mn > Zn > Cu > Pb > Ni > Co > As > Cd > Hg. Spatial distribution pattern demonstrated overall decreasing trend of trace metal from Cadiz Bay mouth to the open ocean mouth, clearly correlative to the presence of anthropogenic inputs. Results of the principle component analysis (PCA) revealed that sediment metal chemistry of Sancti Petri channel is mainly regulated by the concentrations of Pb, Cu, Zn, and Ni; possible sources of those were from vehicular-related emissions. Pollution load index (PLI) and geo-accumulation index (I geo ) indicated overall low values. The study will stimulate improvement of our understanding regarding the pattern of accumulation of metals in the coastal sediments, and the recorded values of metals in the present study can be used as suitable reference for future studies

Legacy metal contamination is reflected in the fish gut microbiome in an urbanised estuary

Estuaries are critical habitats subject to a range of stressors requiring effective management. Microbes are gaining recognition as effective environmental indicators, however, the response of host associated communities to stressors remains poorly understood. We examined microbial communities from seawater, sediments and the estuarine fish Pelates sexlineatus, in Australia\u27s largest urbanised estuary, and hypothesised that anthropogenic contamination would be reflected in the microbiology of these sample types. The human faecal markers Lachno3 and HF183 were not detected, indicating negligible influence of sewage, but a gradient in copy numbers of the class 1 integron (intI-1), which is often used as a marker for anthropogenic contamination, was observed in sediments and positively correlated with metal concentrations. While seawater communities were not strongly driven by metal contamination, shifts in the diversity and composition of the fish gut microbiome were observed, with statistical links to levels of metal contamination (F2, 21 = 1.536, p \u3c 0.01). Within the fish gut microbiome, we further report increased relative abundance of amplicon sequence variants (ASVs; single inferred DNA sequences obtained in sequencing) identified as metal resistant and potentially pathogenic genera, as well as those that may have roles in inflammation. These results demonstrate that microbial communities from distinct habitats within estuarine systems have unique response to stressors, and alterations of the fish gut microbiome may have implications for the adaptation of estuarine fish to legacy metal contamination

Integrated floating cage aquageoponics system (IFCAS): An innovation in fish and vegetable production for shaded ponds in Bangladesh

Farmer participatory action research was carried out from July to December 2013 to design and construct a technology known as IFCAS (integrated floating cage aquageoponics system) for growing fish and vegetables in shaded ponds in the Barisal region of Bangladesh under the EU funded ANEP (Agriculture and Nutrition Extension Project). Here the terms aqua, geo and ponics means pond water, pond mud/soil and cultivation, respectively. Producing and regularly harvesting fish in shaded ponds and growing vegetables on surrounding dykes for household consumption was constrained. To overcome the difficulties, an IFCAS (3.66 m × 2.44 m = 9 m2) was set in each of 9 shaded ponds – 5 highly shaded ponds (HSP) and 4 moderately shaded ponds (MSP) – in which GIFT tilapia strain (Orechromis niloticus) was stocked at the rate of 100 m−3 cage. In the ponds, carp species (Catla catla, Labeo rohita, Cirrhinus cirrhosus and Cyprinus carpio) were stocked at the ratio of 1:2:2:1, and at the rate of 14,820 ha−1. Tilapia were fed floating feed and the carp were fed with supplementary feed. Vegetables were grown on the IFCAS scaffold, and tilapia were grown in the net-cage constructed underneath. Women members of HSP households participated fully in the action research in the production of vegetables and fish in IFCAS. Participating households started consuming vegetables and tilapia from IFCAS within 1.5 and 1 month of the start of the experiment, respectively. Average fish consumption of 20 kg household−1 was recorded within four months, of which more than 50% was tilapia from IFCAS. Overall fish and vegetable production was higher in MSP as compared to HSP. A financial analysis showed the benefit-cost ratio of IFCAS was >1, indicating the investment efficiency of IFCAS for farmers

Economic Viability and Seasonal Impacts of Integrated Rice-Prawn-Vegetable Farming on Agricultural Households in Southwest Bangladesh

Integrated aquaculture is an efficient method to address food scarcity and land resources. This study analysed the impacts of integrated rice–prawn–vegetable farms (RPVF) compared with conventional rice farms (CRF) on farming households in southwest Bangladesh, in terms of cropping pattern, financial profitability and viability, and cash-flow. Data were collected through face-to-face recall interviews from farmers of CRF and RPVF. For RPVF, farmers cultivated diverse produce in the wet season, such as prawn/shrimp, carps in reservoirs and vegetables on dikes, and boro rice with vegetables in the dry season, whereas only rice was cultivated in both seasons for CRF. The annual hectare−1 net revenue from integrated RPVF was USD 2742.7, 3.6 times higher than for CRF (USD 756.6). RPVF had a higher undiscounted benefit–cost ratio (BCR) of 1.58 as compared with 1.34 for CRF. Net Present Value (NPV) and discounted BCR show that the integrated RPVF has higher potential and profitability than CRF. Year-round vegetable production and selling have resulted in a smooth cash-flow in integrated RPVF. Authorised extension agencies, such as the Department of Fisheries and Department of Agricultural Extension collaboratively can promote RPVF in other potential parts of Bangladesh, through which farmers can benefit year after year by investing farm income for the same farm and envisage food security

Economic Viability and Seasonal Impacts of Integrated Rice-Prawn-Vegetable Farming on Agricultural Households in Southwest Bangladesh

Integrated aquaculture is an efficient method to address food scarcity and land resources. This study analysed the impacts of integrated rice–prawn–vegetable farms (RPVF) compared with conventional rice farms (CRF) on farming households in southwest Bangladesh, in terms of cropping pattern, financial profitability and viability, and cash-flow. Data were collected through face-to-face recall interviews from farmers of CRF and RPVF. For RPVF, farmers cultivated diverse produce in the wet season, such as prawn/shrimp, carps in reservoirs and vegetables on dikes, and boro rice with vegetables in the dry season, whereas only rice was cultivated in both seasons for CRF. The annual hectare−1 net revenue from integrated RPVF was USD 2742.7, 3.6 times higher than for CRF (USD 756.6). RPVF had a higher undiscounted benefit–cost ratio (BCR) of 1.58 as compared with 1.34 for CRF. Net Present Value (NPV) and discounted BCR show that the integrated RPVF has higher potential and profitability than CRF. Year-round vegetable production and selling have resulted in a smooth cash-flow in integrated RPVF. Authorised extension agencies, such as the Department of Fisheries and Department of Agricultural Extension collaboratively can promote RPVF in other potential parts of Bangladesh, through which farmers can benefit year after year by investing farm income for the same farm and envisage food security