A laboratory investigation of microbe-inducing CdCO<Subscript>3</Subscript> precipitate treatment in Cd<Superscript>2+</Superscript> contaminated soil

Background, aim and scope  

This paper discusses a method investigating the reduction of free heavy metal cation contents in soil through the use of microbe-inducing precipitate (MIP).     

Effects of inter-varietal diversity,biotic stresses and environmental productivity on grain yield of spring barley variety mixtures

Varietal seed mixtures tend to increase and stabilize crop yields, yet their application is sparse. Large-scale cultivation of variety mixtures may require a better understanding of how inter-varietal interactions and their interaction with the environment may influence the grain yield of variety mixtures relative to their component varieties. For this purpose, six variety mixtures of spring barley and 14 component varieties were grown in each of 17 trial environments. A total of 28 observed and a priori plant characteristics, including grain yield, disease severity and weed competitiveness, were derived for each component variety in each trial. The relationship between inter-varietal diversity of each characteristic and the mixing effect on grain yield was analysed. Additionally, various types of yield stability were estimated and compared among mixtures and component varieties. One mixture out-yielded all of its component varieties in almost half of the trial environments. Inter-varietal diversity in grain yield potential correlated significantly with mixing effect, as did straw length diversity when weighted with weed pressure. The grain yields of most mixtures were more stable across environments than their component varieties when accounting also for the general response to environmental productivity. Hence, most mixtures adapted slightly better to environmental productivity and were less sensitive to environmental stress than their component varieties. We conclude that the efficacy of variety mixtures may be enhanced by mixing relatively high-yielding varieties differing in responsiveness to environmental productivity.     

Changes in organic carbon content and its physical and chemical distribution in paddy soils cultivated under different fertilisation practices

Purpose

Chemical protection facilitates soil organic carbon (SOC) sequestration and stabilisation due to a strong chemical binding with mineral surfaces and metal ions (e.g. iron [Fe], aluminium [Al] and calcium [Ca]). However, there is not much information regarding the role of chemical protection in SOC stabilisation in paddy soils, particularly in terms of the specific forms of organo-mineral complexes such as Fe-, Al- and Ca-bonded OC.

Materials and methods

We sampled paddy soils at the 0–20 cm soil layer from a long-term field experiment (initiated in 1981) conducted under humid subtropical conditions in China, which has five fertilisation treatments (i.e. control treatment without fertiliser [CK], chemical fertiliser only [CF], green manure [GM], Straw and Manure) with equivalent nutrient inputs (i.e. N, P₂O₅ and K₂O at the rates of 135–67.5–135 kg ha^?1, respectively, for both early and late rice) except CK. We determined the chemical binding forms of SOC and the associated soil properties in the particulate fraction (PF, >53 μm) and the mineral-associated fraction (MAF, <53 μm), which were obtained using a low-energy ultrasonic dispersion procedure, of a paddy soil in the long-term fertilisation experiment.

Results and discussion

Iron- and Al-bonded OC (Fe/Al-OC) was the dominant fraction and made up 55–70% of the total SOC in the paddy soil, while Ca-bonded OC (Ca-OC) was only a minor fraction (<4%). The Fe/Al-OC was mainly allocated in the MAF (52–67%), indicating that the chemical protection of SOC occurred mostly in the finer particle fractions. Long-term application of organic amendments increased the contents of bulk SOC by 27–34% (P < 0.05), of Fe/Al-OC by 9–16% and of Ca-OC by 35–83% (P < 0.05), whereas the sole application of chemical fertiliser had no significant effects on SOC contents of the paddy soil compared with the treatment without fertiliser inputs. Both amorphous Fe and Al extracted by ammonium oxalate (Fe_ox and Al_ox) showed significant correlations with Fe/Al-OC (r = 0.52 and 0.78, respectively), but Al_ox appeared to have a greater influence on C stabilisation in the paddy soil.

Conclusions

These results demonstrated that the dominant chemical binding forms of SOC in the paddy soils were Fe/Al-OC and amorphous Fe/Al oxyhydrates, especially amorphous Al, contributed mostly to the chemical stabilisation of SOC.

     

Differential effects of age-structured common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis>) stocks on pond invertebrate communities: implications for recreational and wildlife use of farm ponds

Sustainable development of common carp Cyprinus carpio pond fisheries in Europe postulates their multifunctional use, integrating exploitation of aquaculture resources with recreational services and maintenance of high levels of local biodiversity. Age classes of farmed carp are grown separately and pond ecosystems may be differently affected by different ontogenetic stages of fish. To examine these relationships, a study was conducted on spring and summer diet of carp, invertebrate abundance and community structure, and water quality characteristics in ponds stocked with three carp age classes in SE Poland. With the exception of young-of-the-year fish in spring, benthic dipterans prevailed in the diets of all carp age classes and their consumption increased from spring to summer. Zooplankton featured in the diet of carp only in spring. Medium- and large-sized cladocerans predominated among microcrustaceans found in the guts of one- and two-year-old carp. Consequently, in summer, total biomass of medium- and large-sized cladoceran grazers was substantially lower in ponds stocked with older-age fish than in ponds used for production of 1-summer-old fingerlings. The relatively sparse submerged vegetation cover and low water transparency in ponds with older fish stocks compared to ponds with young-of-the-year carp indicate a transition to a turbid water state mediated by a trophic cascade mechanism in the presence of older-age fish. Densities of water-column macroinvertebrates decreased with the age of carp in the ponds. These results suggest that non-aquaculture use of carp ponds should be diversified according to their environmental quality. Fingerling rearing ponds are more suitable for environmentally friendly multifunctional use than ponds with older stocks.     

Feasibility of Locating Leakages in Sewage Pressure Pipes Using the Distributed Temperature Sensing Technology

The cost effective maintenance of underwater pressure pipes for sewage disposal in Austria requires the detection and localization of leakages. Extrusion of wastewater in lakes can heavily influence the water and bathing quality of surrounding waters. The Distributed Temperature Sensing (DTS) technology is a widely used technique for oil and gas pipeline leakage detection. While in pipeline leakage detection, fiber optic cables are installed permanently at the outside or within the protective sheathing of the pipe; this paper aims at testing the feasibility of detecting leakages with temporary introduced fiber optic cable inside the pipe. The detection and localization were tested in a laboratory experiment. The intrusion of water from leakages into the pipe, producing a local temperature drop, served as indicator for leakages. Measurements were taken under varying measurement conditions, including the number of leakages as well as the positioning of the fiber optic cable. Experiments showed that leakages could be detected accurately with the proposed methodology, when measuring resolution, temperature gradient and measurement time were properly selected. Despite the successful application of DTS for leakage detection in this lab environment, challenges in real system applications may arise from temperature gradients within the pipe system over longer distances and the placement of the cable into the real pipe system.     

Intraspecific growth variation among rainbow trout and brook trout: impact of initial body weight and feeding level

This study describes growth variation within groups of salmonids and the relation to initial fish weights and feeding levels. PIT-tagged rainbow trout (RT) and brook trout (BT) of start weight 120–170 g were reared in separate tanks for 9 weeks. Both species were fed each day either a high ration close to satiation (H) or half of this ration (L). Four experimental groups (RT-H, RT-L, BT-H, BT-L) were studied with regard to their propensity to increase weight in accord with their initial weight. The slope of the regression line between initial weights (g) and weight increases for individuals in each tank in each period was applied as indicator for this propensity (termed “slope”). All calculated slopes in the experiment were positive which indicates the general ability of weighty fish to gain more weight than smaller individuals. The average slope during all 9 weeks was 2–4 times higher for RT-L (5.91) than for all other groups (RT-H: 1.50, P < 0.01; BT-H: 1.76, P < 0.01 and BT-L: 2.88, P < 0.05), indicating the particular propensity of large RT to gain weight when feed was restricted. Overall, ration level had large impact on slopes (H: 1.63, L: 4.39, P < 0.01), while this was not the case for species (RT: 3.71, BT: 2.32, P > 0.05). The magnitude of slopes decreased over time (weeks 0–3:4.27, weeks 3–6:3.02 and weeks 6–9:1.74, P < 0.05). The observed differences in weight gains between experimental groups were reflected in differences in coefficients of variations (CVs) for body growth. RT had larger body weight (BW) CVs compared to BT (0.257 vs. 0.206, P < 0.01) indicating more uneven feed share among RT than among BT in general. RT-L had significantly higher BW CVs than all other groups (0.300 vs. 0.184–0.229, P < 0.01). The observed differences in weight gains enhance size variations in terms of higher CVs, and this may have implications for feeding tactics in aquaculture where large size variations in groups may be disadvantageous to fish farmers.     

Effect of body size and sub-optimal water quality on some hemato-immunological parameters of spotted babylon snail <Emphasis Type="Italic">Babylonia areolata</Emphasis>

Cellular and humoral effectors are imperative for the innate defense mechanisms of invertebrates, including the spotted babylon snail Babylonia areolata, a marine gastropod belonging to the family Buccinidae. In this study, we have investigated the influence of body size [5–8 g (small), 10–12 g (medium) and 15–17 g (large)], and culture waters of varied quality [natural seawater, low salinity, low alkalinity, high total ammonia nitrogen (TAN) and artificial seawater] on some hemato-immunological parameters [total hemocytic counts (THC), hemolymphatic glucose, total protein concentration, phenoloxidase (PO), agglutinating and lysozyme activity] of the snail. Growth performance measures and survival of test snails were also evaluated after rearing them in culture water of varied quality. Body size did not influence most parameters assessed, except that the lysozyme and PO activities of medium and large-size snails were higher than those of the small-size snails. Sub-optimal culture water quality affected hemato-immunological factors, growth and/or survival of the spotted babylon snail. Seawater with low salinity, low alkalinity and a high TAN level caused decreased THC, hemolymphatic glucose, and PO activity; increased lysozyme activity; and clearly retarded growth of the snail. The snails held in artificial seawater could not survive after 4 weeks, suggesting the lack of certain essential factors necessary for their survival.     

Estimation of genetic parameters for growth traits of Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis> using an animal model

To estimate genetic parameters of growth traits in Japanese flounder Paralichthys olivaceus, full-sib and half-sib families were produced in three consecutive years at the Beidaihe Central Experiment Station in China. Each year 8–28 families were produced. The body weight, body length and body depth at 180, 240, and 360 days of age were measured for 5,224 individuals. Four animal models were used to examine the phenotypic variation of growth traits and were compared using the likelihood ratio test. The results showed that estimates for additive genetic effect heritabilities varied greatly depending on the model, trait and age. The maternal effect had a significant impact on phenotypic variation only for body depth at 180 days of age, which explained 49% of the phenotypic variance. The ratio of full-sib effect to phenotypic variation ranged from 0.09 to 0.22. Growth traits all exhibited low heritability (0.13–0.39), indicating that there is the potential for family selection breeding for these traits in Japanese flounder. Using the full model with the fixed, full-sib family, additive and maternal genetic effects, genetic correlations among the three traits for fish of the same age were estimated to be more than 0.80. Generally, the genetic correlations gradually increased as age increased.     

Response of European seabass (<Emphasis Type="Italic">Dicentrarchus labrax</Emphasis>) to canola oil diets: effect on growth performance,fish health and liver and intestine histomorphology

This study was undertaken to assess the effects of feeding European seabass (Dicentrarchus labrax) canola oil-added diets on growth, health status and liver and intestine histomorphology. Seabass (56.18 ± 0.16 g initial body weight) were fed one of three fish meal-based diets with ~48 % crude protein and ~16.0 % lipid, combining fish oil (FO) and canola oil (CO) for 12 weeks. The diets contained: zero (control, CTRL), 45 (CO50) or 63 (CO70) g CO kg^?1 assigned in triplicates to three dietary groups. The results indicated that neither dietary oil type (FO or CO) nor CO level adversely affected (P > 0.05) the growth, feed utilization or major blood constituents’ composition as an indicator of the overall health status of fish. Despite the CO diets influence on head kidney macrophage activity being unappreciable (P > 0.05), there was a reducing trend with an increase in CO level incorporation. The CO70 diet induced a minor fat infiltration in hepatocytes and leucocytes infiltration, hyperplasia of the basal nuclei and supranuclear vacuolization of the enterocytes of the distal intestine. The present observations suggest that it is possible to incorporate up to 63 g CO Kg^?1 in the feed for European seabass juveniles without major negative effects on growth, health status or liver and intestinal histomorphology.     

Quantifying the respective and additive effects of nectar plant crop borders and withholding insecticides on biological control of pests in subtropical rice

Conservation biological control avoids the need for mass releases of costly agents and the risks associated with introducing exotic agents by promoting existing natural enemies. This is done by alleviating insecticide-induced mortality and by manipulating the habitat to provide resources such as nectar, but there is a dearth of information on the relative and interactive effects of these two approaches. Here we used a large-scale factorial experiment with plots comprised of entire fields to test the effects of, and interactions between, withholding insecticides and planting borders of sesame (Sesamum indicum) on natural enemies and pests over 2 years. We used yellow sticky traps, sweeping netting and sentinel bait plants to monitor natural enemies and pests in the canopy and basal zones of the rice crop. Numbers of rice planthopper egg parasitoids and lepidopterous egg parasitoids in the rice canopy, as well as planthopper parasitism rates, were significantly greater in plots that were unsprayed and bordered by sesame, and scarcest in sprayed crops without sesame. Spraying of sesame-bordered crops gave parasitoid numbers similar to sprayed crops without sesame. Spiders in the canopy were significantly reduced in numbers by spraying, but there was no main effect of sesame borders. This study demonstrates that withholding insecticides and sowing nectar plant borders each have measurable as well as additive benefits on in-crop densities of ecosystem service providers responsible for predating and parasitising pests but the identity of the natural enemy determines the impact of these management practices.