Red swamp crayfish (Procambarus clarkii) has increasingly become a high-value freshwater product in China. During the intensive cultivation, excessive ammonia exposure is an important lethal factor ...of crayfish. We investigated the toxic effects and mechanisms of ammonia on crayfish at two different developmental stages. A preliminary ammonia stress test showed a 96-h LC50 of 135.10 mg/L and 299.61 mg/L for Stage_1 crayfish (8.47 ± 1.68 g) and Stage_2 crayfish (18.33 ± 2.41 g), respectively. During a prolonged ammonia exposure (up to 96 h), serum acid phosphatase and alkaline phosphatase showed a time-dependent decrease. Histological assessment indicated the degree of hepatopancreatic injury, which was mainly characterized as tubule lumen dilatation, degenerated tubule, vacuolization and dissolved hepatic epithelial cell, increased with exposure time. Enhanced malondialdehyde level and reduced antioxidant capacity of hepatopancreas were also observed. The mRNA expression and activity of catalase and superoxide dismutase showed an initial up-regulation within 24 h, and then gradually down-regulated with the exposure time. In the post-treatment recovery period, the Stage_2 crayfish exerted a stronger antioxidant and detoxification capacity than that of the Stage_1 crayfish, and thus quickly recovered from the ammonia exposure. Our findings provide a further understanding of the adverse effects of ammonia stress and suggest guidelines for water quality management during crayfish farming.
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•The stage-dependent sensitivity of P. clarkii to ammonia was investigated.•Hepatopancreatic damages were characterized by lumen dilatation and vacuolization.•The Stage_2 crayfish exhibited a stronger antioxidant and detoxification capacity.
Assessing the potential impacts of different land management practices helps to identify and implement sustainable watershed management measures. This study aims to assess a change in soil erosion ...rate under different land management practices in the Gilgel Abay watershed of the upper Blue Nile basin, Ethiopia. The Revised Universal Soil Loss Equation (RUSLE) model that was adapted to the Ethiopian highlands context was employed to estimate the rate of soil erosion. The impact of land management practices on soil erosion was estimated for three scenarios, which were baseline, intensive cultivation, and extensive cultivation scenarios. At the baseline scenario, the mean annual soil erosion was estimated at ~32.8 t ha−1yr−1, which is equivalent to a loss of ~13.66 Mt yr−1 from the entire watershed. While the rate of soil erosion reduced to ~11.3 t ha−1yr−1 during the implementation of intensive cultivation management practice, which reduced the total soil loss in the watershed by 65%. On the other hand, under the extensive cultivation scenario, the mean annual soil erosion rate increased to ~34.4 t ha−1yr−1. The findings suggest that implementing agricultural intensification management practices can significantly reduce soil erosion in the watershed.
Extensive cultivation, Intensive cultivation, Land managements, RUSLE, Scenarios, Soil erosion; Agricultural soil science; Environmental analysis; Environmental assessment; Environmental hazard; Environmental management.
This article examines global agrifood chains from a perspective that links economic activity to sociocultural transformations in the social sphere—often categorized as private and independent of the ...economic domain. Specifically, the study examines the relations established between recruitment policies, work, and sexuality in the intensive cultivation of strawberries in Andalusia, Spain. Taking a feminist political economy and intersectional approach, the ethnographic analysis centers on sexuality in socio-labor spaces in the context of the policies to recruit quotas of women from their home countries on temporary contracts. The analysis starts by exploring the way that the changing recruitment criteria of the Spanish temporary farmworker program define the ideal woman worker and how sexuality is constructed in social representations and relations. The analysis then shows how the sexualization of temporary women workers from eastern Europe is constructed through comparisons of the various groups of workers (Polish, Romanian, Romani, Moroccan, and Andalusian). In the final section, the study examines the articulation of contradictory representations of sexuality and behavior with systems of control.
Hermawan B, Suhartoyo H, Sulistyo B, Murcitro BG, Herman W. 2020. Diversity of soil organic carbon and water characteristics under different vegetation types in northern Bengkulu, Indonesia. ...Biodiversitas 21: 1793-1799. Organic carbon and water characteristics are important soil properties that can easily degrade following the conversion of forest to cultivation land, but their levels of degradation depend on successive vegetation types after deforestation. The research aimed to evaluate the spatial diversity of soil organic carbon (SOC) and water characteristics on sites with annual and cash crops, as well as natural vegetation types. Forty-two undisturbed and disturbed soil samples were collected at 0-10 and 10-20 cm depths from plantation areas (rubber and oil palm), rice fields, shrub land, and grassland in Mukomuko, North Bengkulu, and Central Bengkulu Regencies of Bengkulu Province, Indonesia. Vegetation types were observed, and soil water characteristics were determined using a pressure plate apparatus unit from undisturbed soil samples, while SOC and particle-size distribution were analyzed from disturbed soil samples. The uppermost 10 cm soil layers were dominated by organic-C intervals of more than 3.0% while the 10-20 cm depths had intervals of less than 3.0%. Soils under oil palm and rice production had higher SOC of above 6.0% and water availability at the field capacity of 0.4-0.6 g g-1, particularly at 0-10 cm depths, while those under rubber and grass had a lower status of measured variables, particularly at 10-20 cm depth. There was a strong relationship (R2 = 0.63) between the soil organic carbon and water availability among study soils, suggesting the possibility to predict potential soil water deficits from organic matter status.
In olive (Olea europaea L.) traditional methods of genetic improvement have up to now produced limited results. Intensification of olive growing requires appropriate new cultivars for fully ...mechanized groves, but among the large number of the traditional varieties very few are suitable. High-density and super high-density hedge row orchards require genotypes with reduced size, reduced apical dominance, a semi-erect growth habit, easy to propagate, resistant to abiotic and biotic stresses, with reliably high productivity and quality of both fruits and oil. Innovative strategies supported by molecular and biotechnological techniques are required to speed up novel hybridisation methods. Among traditional approaches the Gene Pool Method seems a reasonable option, but it requires availability of widely diverse germplasm from both cultivated and wild genotypes, supported by a detailed knowledge of their genetic relationships. The practice of "gene therapy" for the most important existing cultivars, combined with conventional methods, could accelerate achievement of the main goals, but efforts to overcome some technical and ideological obstacles are needed. The present review describes the benefits that olive and its products may obtain from genetic improvement using state of the art of conventional and unconventional methods, and includes progress made in the field of in vitro techniques. The uses of both traditional and modern technologies are discussed with recommendations.
Physicochemical parameters of water and survival rate, growth, and body composition of the Malaysian prawn Macrobrachium rosenbergii were recorded and evaluated for six months in two nursery rearing ...systems: biofloc and traditional cultivation. The study was conducted in a shade house (300 m... , plastic mesh, 90% shade) in four rectangular ponds (20 m... ). Stocking was at 37 prawns m... (0.025 g... ) and fed twice daily with a commercial diet. Daily temperature, dissolved oxygen, pH, NH3-N, NO3-N, NO2-N, and turbidity were recorded daily and the weight and length of the prawns were recorded each month. Water quality parameters were similar in both treatments, except transparency, which was significantly higher under traditional cultivation (36.10 ± 2.06 cm... ) compared with the biofloc system (7.01 ± 1.52 cm... ) at the end of the study. Survival rate was > 85% under both treatments, but final size was significantly higher in the biofloc system (11.54 ± 1.87 g... , 15.18 ± 8.27 cm... ) than in the traditional system (10.67 ± 2.26 g... , 12.57 ± 7.89 cm... ). Protein (51.19%) and lipid (13.84%) content in harvested prawns was significantly higher in the biofloc system, which we ascribe to the nutritional contribution of complementary food. The results strongly suggest that the biofloc nursery system is a profitable alternative for locations where climatic and water restrictions do not allow traditional prawn cultivation and also contributes to sustainable use of water and improved nutritional quality of the prawns. (ProQuest: ... denotes formulae/symbols omitted.)
Heavy metals are environmental pollutants which threatens human health and natural ecosystem. These affect the quality of soil and water and it can be transferred to human body while consuming ...agricultural crops and drinking water. Intense cultivation has been resulted in accumulation of heavy metals and trace elements due to the excess use of agrochemical substances for obtaining better yield in Sri Lanka. The usage of agrochemicals leads to loss of originality of soil, water and food with bioaccumulation. This study aimed to find out the effect of fertilizer and pesticides on grape yard, water, leaves and grape fruits. The samples from water, soil and plant materials were collected in intensive cultivated areas in Jaffna and tested for heavy metal contamination. The concentrations of Zn, Ni, Cu, As, Pb, Mg and Al in soils varied from 7.5 to 61.4, 0.4–48.3, 3.6–20.3, 0.56–3.56, 3.1–11.6, 108–957, 0.1–3.6 mgkg−1 respectively. Assessed ecological risk indicated that soil was moderately contaminated by Pb and Cu. While considering toxic effect of heavy metals in soil was classified as the moderate degree based on their intensities. The content of metals in fruit samples varied such as Zn from 0.2 to 1.9 mgkg−1, Ni from 0.05 to 0.2 mgkg−1, Cu from 0.3 to 1.3 mgkg−1, As and Pb less than 0.05 mgkg−1. The concentrations of tested metals were found in negligible amount in water. Most of the accumulated metals are mainly concentrated in the leaves of the grape tree than in the fruit. The findings of this study can be applied in the adoption of measures to reduce the usage of metals that generate toxicological effect in the grape cultivated ecosystem of Northern part of Sri Lanka.
In March 2015, Sri Lanka's then-President Maithripala Sirisena launched the Toxic Free Nation Movement as a long-term solution to a mysterious form of kidney disease (CKDu) now endemic in the ...island's dry zone. As part of this strategy, in 2016 the movement worked with farmers in north-central Sri Lanka to cultivate indigenous rice varieties without agrochemicals. Yet, within a year, 80 percent of farmers who experimented with indigenous and organic rice farming had switched back to some form of agrochemically intensive cultivation. In this article, I examine farmers' narratives of why this happened, demonstrating how the movement's conceptualization of agricultural harm often missed the forms of accounting most salient for residents themselves. Instead, through their testimonies, residents track how polyvalent relationships with agrarian toxicity mediate (1) vulnerabilities to simple reproduction squeezes, (2) reliance on grain fungibility, and (3) strong but bittersweet attachments to dry zone agrarian landscapes. As a consequence, I document how residents respatialize their knotted relationships to agrarian toxicity to include moments of what I call "agrichemical kinship." I argue that this optic helps us grasp the ways in which agrochemicals simultaneously erode and enable modes of social reproduction against a backdrop of rural stagnation. Following feminist scholars of toxicity, this article not only reveals intimate, yet undertheorized, connections between the field of toxic geographies and the concept of social reproduction but also dashes hopes of any simple equation between banning agrichemical inputs and enacting health in the wake of CKDu.
Carbon and nitrogen contents, as well as their chemical fractions (humic acid - HAF, fulvic acid - FAF, humin - HUM) and particle-size fractions (particulate organic carbon - POC, mineral-associated ...organic carbon - MAOC) of organic matter were evaluated in areas cultivated with yerba mate (Ilex paraguariensis) with 35 (E35) and 45 (E45) consecutive years of cultivation, in addition to a native forest area (NF), taken as reference. The soils of the study area were classified as Cambissolo Háplico (Inceptisol). Soil samples were collected at depths of 0.0-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.40 cm. A completely randomized design in split plots (3 areas and 4 depths) with 4 replicates was used. The E45 area, due to the longer cultivation time and the addition of organic fertilizer, had higher TOC, N and POC contents in comparison to the E35 area, with similar values of these attributes being observed in the forest area at some depths. The most stable carbon fractions (MAOC and HUM) did not vary between cultivated areas (E35 and E45); however, there were reductions of 25 and 14% (HUM 0-5 cm) and 12 and 21% (MAOC 5-10 cm) in these fractions, respectively, in comparison to the native forest. There was no difference between the evaluated areas for FAF, but HAF values were higher in the native forest area than in the cultivated areas.
The results of studies of an intensive culture of a new species of bentoplanktonic diatom
N. shiloi
(Lee, Reimer et McEnery) Round, Hallsteinsen et Paasche 1999 isolated from the Black Sea are ...presented. Detailed descriptions are provided of the methods used to isolate the species into an algologically pure culture and its morphological and taxonomic features under light and electron scanning microscopy. The biochemical and production characteristics were also studied including the ability of the strain to accumulate fucoxanthin (
Fx
) and polyunsaturated fatty acids (PUFA) in laboratory conditions. During the exponential growth phase, the specific culture growth rate was µ = 0.8 1/day, and the maximum productivity
P
= 0.46 g dry weight/(L day). The accumulation of PUFAs in the biomass of
N. shiloi
reached 67.39 mg/g dry weight of algae. The
Fx
concentration in the biomass at the beginning of the stationary growth phase was 10 mg/g dry weight. The fairly high rate of
Fx
biosynthesis in microalgae cells, as well as the composition of fatty acids of the Black Sea strain, makes it possible to classify
N. shiloi
as a promising object in biotechnology.
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