Enriching Artemia nauplii with a high DHA‐containing lipid emulsion: search for an optimal protocol

This study aimed to investigate practical strategies to optimize the use of a high‐docosahexaenoic acid (DHA) lipid emulsion (M70), a product with great potential in live prey enrichments for marine larviculture. Considering its particularly high content in DHA (22:6n‐3), the adequate utilization of the emulsion for Artemia enrichments was evaluated in a series of six experiments. More specifically, the bioencapsulation efficiency of M70 into Artemia nauplii was tested under different experimental conditions of oxygen source, aeration flow, incubation temperature, concentration and dosage, as well as nauplial densities. Our results showed that an optimal utilization of M70 is achieved with incubation temperatures of 28°C, moderate aeration flows and nauplial densities of 300 ind per mL. In addition, the emulsion can be dispensed in the enrichment medium in one single dose of 0.8 g L^?1, with no apparent detrimental effects on its oxidative stability and Artemia nauplii survival during enrichment.     

Stratified sampling in fruit orchards using cluster-based ancillary information maps: a comparative analysis to improve yield and quality estimates

Precision Agriculture - Estimation of yield or other fruit quality parameter is of great interest to farmers to decide on management actions just before harvesting and, in any case, to anticipate...     

Artificial radionuclides in waters of the lower section of the river Ebro (Northeast Spain)

The river Ebro, in Northeast Spain,discharges into the Mediterranean Sea after flowingthrough several large cities and agricultural, miningand industrial areas. The Ascó nuclear power plant(NPP) is located in the lower river section andcomprises two pressurised-water reactor (PWR) units,from which low-level liquid radioactive waste isreleased to river waters under authority control.During the period 1989 to 1993, we carried out 29sampling campaigns in order to determine ³H,⁹⁰Sr, ¹³⁴Cs, ¹³⁷Cs, ²³⁸Pu and^239,240Pu in Ebro river waters at differentlocations, both upstream and downstream from theAscó NPP. ³H, ¹³⁴Cs and ¹³⁷Csactivities showed large variability as they rangedfrom <1.4 to 117±3 Bq L^-1, <0.27 to22±1 mBq L^-1 and <0.36 to 35±1mBq L^-1, respectively. This behaviour, especiallyremarkable for tritium, was due to the detection oftank releases travelling downstream. Thecharacteristic NPP ¹³⁴Cs/¹³⁷Cs ratio wasfound to be 0.61±0.02 (N = 22). In the estuarinearea, ¹³⁷Cs traces from Mediterranean waters wereobserved and relatively enhanced tritium activitiesmight possibly be present due to the accumulation ofactivity in the estuary. ⁹⁰Sr and ^239,240Puactivities were homogeneous both in respect to timeand space, showing mean activities 6.9±0.2 mBq L^-1 (N = 10) and 1.36±0.10 mBq m^-3 (N = 3), respectively. These levels couldonly be attributed to nuclear weapons fallout leachedby continental waters, as the impact from the plantappears to be negligible and no other sources arepresent in the area.     

Plant oils' inclusion in high fish meal‐substituted diets: effect on digestion and nutrient absorption in gilthead sea bream (Sparus aurata L.)

Here, we performed an 11‐week trial to study the effects of four experimental diets on the digestion, nutrient absorption and intestinal histology of gilthead sea bream. The diets were formulated with a low fish meal content (25%) and were rich (75%) in plant proteins. Fish oil (FO) was replaced at 0%, 33%, 66% and 100% by graded levels of a blend of vegetable oils (VO) (diets FO, 33VO, 66VO and 100VO respectively). Protease activity increased in the pyloric caeca (PC) and decreased in the proximal intestine (PI) of the 66 and 100VO groups, while lipase and α‐amylase activities were not modified by VO. The capacity of brush‐border membrane vesicles obtained from PC, PI and distal intestine to absorb amino acids was not modified, but d ‐glucose and linoleic acid absorption diminished when VO was included in the diets. In summary, these results show that when 75% of protein is provided by vegetable sources in the diet of gilthead sea bream, up to 66% of FO can be replaced by a blend of VO without compromising digestive processes. Only the total replacement of VO results in an impaired digestion, with reduced total protease activity and accumulation of lipid droplets in the enterocytes of the PI.     

Dairy Cattle Manure Effects on Soil Quality: Porosity,Earthworms, Aggregates and Soil Organic Carbon Fractions

In the European Union, the maintenance of soil quality is a key point in agricultural policy. The effect of additions of dairy cattle (Bos taurus) manure (DCM) during a period of 11 years were evaluated in a soil under irrigated maize (Zea mays L.) monoculture. DCM was applied at sowing, at wet‐weight rates of 30 or 60 Mg ha⁻¹yr⁻¹ (30DCM or 60DCM). These were compared with a mineral‐N treatment (300 kg N ha⁻¹, MNF), applied at six to eight emerged leaves and with a control (no N, no manure). Treatments were distributed in a randomized block design. Factors analysed were stability against wetting stress disaggregation, porosity, soil organic carbon (SOC) fractions and earthworm abundance, studied eight months after the last manure application. The application rate of 30DCM increased aggregate stability and the light SOC fraction, but not the pore volume, nor the earthworm abundance, compared with MNF. The DCM rates did not result in unbalanced agronomic advantages versus MNF, as high yields (12–16 Mg ha⁻¹ yr⁻¹) were obtained. In Mediterranean environments, the use of DCM should be encouraged mainly because of its contribution to the light SOC fraction which protects dry macro‐aggregates from implosion (slaking) during the wetting process. Thus, in intensive agricultural systems, it protects soil from physical degradation. Copyright © 2016 John Wiley & Sons, Ltd.     

Mobile terrestrial laser scanner applications in precision fruticulture/horticulture and tools to extract information from canopy point clouds

LiDAR sensors are widely used in many areas and, in recent years, that includes agricultural tasks. In this work, a self-developed mobile terrestrial laser scanner based on a 2D light detection and ranging (LiDAR) sensor was used to scan an intensive olive orchard, and different algorithms were developed to estimate canopy volume. Canopy volume estimations derived from LiDAR sensor readings were compared to conventional estimations used in fruticulture/horticulture research and the results prove that they are equivalent with coefficients of correlation ranging from r = 0.56 to r = 0.82 depending on the algorithms used. Additionally, tools related to analysis of point cloud data from the LiDAR-based system are proposed to extract further geometrical and structural information from tree row crop canopies to be offered to farmers and technical advisors as digital raster maps. Having high spatial resolution information on canopy geometry (i.e., height, width and volume) and on canopy structure (i.e., light penetrability, leafiness and porosity) may result in better orchard management decisions. Easily obtainable, reliable information on canopy geometry and structure may favour the development of decision support systems either for irrigation, fertilization or canopy management, as well as for variable rate application of agricultural inputs in the framework of precision fruticulture/horticulture.     

Environmental consequences from the use of sewage sludge in soil restoration related to microbiological pollution

Purpose

This article analyzed the survival of Escherichia coli, total coliforms, and Salmonella spp. in a soil amended with urban sewage sludge due to its potential use in soil rehabilitation and to the risk of microbial pollution.

Materials and methods

The survival of E. coli, total coliforms, and Salmonella spp. was determined in a soil amended with different doses of four different urban sewage sludge based on equivalent nitrogen fertilization of 0, 85, 170, and 340 kg N/ha. After the topsoil/sludge mixtures were made, they were wet to 18% moisture and analyzed for 2 months to determine the presence of bacteria, and then again after 1 year.

Results and discussion

The results indicate that the presence of microorganisms was strongly conditioned by the type of biosolid and the dose applied. Soil moisture diminished as the experiment progressed and seemed to play a role in controlling the presence of the bacteria.

Conclusions

The initial concentrations of bacteria depend on the sewage sludge treatment. The evolution of E. coli had a similar trend as total coliforms, and Salmonella spp. was absent after 8 weeks although a positive presence was detected in some soils after a year. As a conclusion, long periods of time reduce the risk from the presence of pathogens in soils, and the persistence may be closely related to the treatment of sewage sludge and the initial amount of microorganisms in the sewage sludge.