Effects of cage netting colour and density on the skin pigmentation and stress response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801)

The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these laboratory‐based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on‐farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin^® Pink, BASF) at 0 or 39 mg kg^?1 for 42 days. Skin colour was measured using the CIE (black–white), (green–red), (blue–yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher ) than snapper held in black cages; however, values were not as high as previous laboratory‐based studies in which snapper were held in white plastic‐lined cages. Snapper fed astaxanthin displayed significantly greater and values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg^?1 astaxanthin for 44 days before transferring to black or white plastic‐lined cages at 14 (low), 29 (mid) or 45 (high) kg m^?3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness () was greater in snapper transferred to white plastic‐lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg^?1 for approximately 6 weeks and transferring snapper to white plastic‐lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling.     

Association mapping reveals loci associated with multiple traits that affect grain yield and adaptation in soft winter wheat

Genome-wide association studies (GWAS) are useful to facilitate crop improvement via enhanced knowledge of marker-trait associations (MTA). A GWAS for grain yield (GY), yield components, and agronomic traits was conducted using a diverse panel of 239 soft red winter wheat (Triticum aestivum) genotypes evaluated across two growing seasons and eight site-years. Analysis of variance showed significant environment, genotype, and genotype-by-environment effects for GY and yield components. Narrow sense heritability of GY (h ²  = 0.48) was moderate compared to other traits including plant height (h ²  = 0.81) and kernel weight (h ²  = 0.77). There were 112 significant MTA (p < 0.0005) detected for eight measured traits using compressed mixed linear models and 5715 single nucleotide polymorphism markers. MTA for GY and agronomic traits coincided with previously reported QTL for winter and spring wheat. Highly significant MTA for GY showed an overall negative allelic effect for the minor allele, indicating selection against these alleles by breeders. Markers associated with multiple traits observed on chromosomes 1A, 2D, 3B, and 4B with positive minor effects serve as potential targets for marker assisted breeding to select for improvement of GY and related traits. Following marker validation, these multi-trait loci have the potential to be utilized for MAS to improve GY and adaptation of soft red winter wheat.     

Synthetic Aperture Radar (SAR) images improve habitat suitability models

Context

The ability to detect ecological networks in landscapes is of utmost importance for managing biodiversity and planning corridors.

Objectives

The objective of this study was to evaluate the information provided by a synthetic aperture radar (SAR) image for landscape connectivity modeling compared to aerial photographs (APs).

Methods

We present a novel method that integrates habitat suitability derived from remote sensing imagery into a connectivity model to explain species abundance. More precisely, we compared how two resistance maps constructed using landscape and/or local metrics derived from AP or SAR imagery yield different connectivity values (based on graph theory), considering hedgerow networks and forest carabid beetle species as a model.

Results

We found that resistance maps using landscape and local metrics derived from SAR imagery improve landscape connectivity measures. The SAR model is the most informative, explaining 58% of the variance in forest carabid beetle abundance. This model calculates resistance values associated with homogeneous patches within hedgerows according to their suitability (canopy cover density and landscape grain) for the model species.

Conclusions

Our approach combines two important methods in landscape ecology: the construction of resistance maps and the use of buffers around sampling points to determine the importance of landscape factors. This study was carried out through an interdisciplinary approach involving remote sensing scientists and landscape ecologists. This study is a step forward in developing landscape metrics from satellites to monitor biodiversity.

     

Arsenate Displacement from Fly Ash in Amended Soils

Arsenic (As) is the biggest environment contaminant in most of the soils where fly ash is applied. Usually, it is not mobile and strongly adsorbed on to soil particles. However, in gypsum and phosphorus amended soils As may be much more mobile. A study in repacked columns was conducted to determine whether or not As becomes mobile when Ca(H₂PO₄)₂and CaSO₄are used as leaching solutions, and to compare the competitive interactions between PO₄-AsO₄and SO₄-AsO₄. Arsenic concentration in leachate was found to be approximately ten times greater when Ca(H₂PO₄)₂was used to leach the columns as compared to CaSO₄. A maximum concentration of 800 μg As L^-1was found in the leachate in this case, which is much higher than the groundwater limit of 50 μg L^-1for drinking water established by the United States Environmental Protection Agency. In fly ash, the portion of arsenate non-specifically adsorbed is believed to be much lower than that of specifically adsorbed. Sulfate anions were able to displace only non-specifically adsorbed arsenate. In this case the concentration of As in leachate was found to be within acceptable limits. On the other hand, phosphate can compete with arsenate for all available adsorption sites, non-specific and specific. Phosphate displacement of both forms of arsenates increases As mobility in both control and fly ash treatments.     

利用ECMWF再分析数据验证PRECIS对中国区域气候的模拟能力

本文利用1979～1983年的ECMWF再分析数据作为准观测侧边界条件驱动Hadley气候预测和研究中心的区域气候模式系统PRECIS，验证PRECIS对中国区域的气候模拟能力。选择典型的观测站点北京模拟的日最高，最低气温、太阳短波总辐射和月均降水量与观测结果进行直接比较，显示：PRECIS具有很强的模拟地面气候季节变化的能力。全国740个台站的观测与模拟值的统计分析表明：尽管模拟的最高，最低气温在0℃附近有一‘锯齿’状的偏差，PRECIS能够很好地模拟全国范围最高，最低气温的型态分布特征；从全国范围看，模拟的降水值偏高，但显示出很强的模拟极端降水事件的能力；模拟的地面太阳短波总辐射与全国122个台站的观测结果的比较显示：PRECIS模拟的辐射值偏高，全国范围内约高22％。因此，当应用PRECIS输出结果进行气候变化的影响评价时，需要对模式的输出结果进行订正。     

Kinetics of soil microbial uptake of free amino acids

 Amino acids and proteins typically form the biggest input of organic-N into most soils and provide a readily available source of C and N for soil microorganisms. Amino acids can also be taken up directly by plant roots, providing an alternative source of available soil N. However, the degree to which plants can compete against the soil microbial population for amino acids in soil solution remains poorly understood. The aim of this study was to measure the rate of microbial uptake of three contrastingly charged ¹⁴C-labelled amino acids (glutamate^1–, glycine⁰, lysine^0.9+) over a wide concentration range (0.1–5 mM) and in two contrastingly managed soils varying in their degree of erosion, organic-C content and microbial biomass. Amino acid uptake was concentration dependent and conformed to a single Michaelis-Menten equation. The mean maximum amino acid uptake rate (V _max) for the non-eroded (control) soil (high organic-C, high biomass) was 0.13±0.02 mmol kg^–1 h^–1, while half maximal uptake occurred at a concentration (K _m) of 2.63±0.07 mM. Typically, V _max was fourfold lower and K _m twofold lower in the eroded soil (low available organic-C, low biomass) compared to the non-eroded (control) soil. Amino acid substrate concentration had little effect on the proportion of amino acid utilized in catabolic versus anabolic metabolism and was similar for both. While the results obtained here represent the summation of kinetics for a mixed soil population, they indicate that amino acid uptake is saturated at concentrations within the millimolar range. Because the affinity constants also were similar to those described for plant roots, we hypothesized that competition for amino acids between plants and microbes will be strong in soil but highly dependent upon the spatial distribution of roots and microbes in soil. Received: 2 March 2000     

Carotenoid changes of intact watermelons after storage

Watermelon contains lycopene, a red carotenoid pigment that has strong antioxidant properties. The lycopene content of watermelon is substantial, contributing 8-20 mg per 180 g serving. There are no reports on carotenoid changes in whole watermelon during storage. Three types of watermelon, open-pollinated seeded, hybrid seeded, and seedless types, were stored at 5, 13, and 21 degrees C for 14 days and flesh color, composition, and carotenoid content were compared to those of fruit not stored. Watermelons stored at 21 degrees C had increased pH, chroma, and carotenoid content compared to fresh fruit. Compared to fresh fruit, watermelons stored at 21 degrees C gained 11-40% in lycopene and 50-139% in beta-carotene, whereas fruit held at 13 degrees C changed little in carotenoid content. These results indicate that carotenoid biosynthesis in watermelons can be affected by temperature and storage.     

Impacts of lost fishing gear on coral reef sessile invertebrates in the Florida Keys National Marine Sanctuary

The Florida Keys coral reef ecosystem supports multimillion-dollar commercial and recreational fisheries. The ecological effects caused by fishing gear that is lost when cut or broken after snagging on the bottom is a growing concern to managers and scientists. Few data exist, however, to assess the impacts of lost fishing gear to benthic organisms and habitat structure. In this study, 63 offshore coral reef and hard-bottom sites were surveyed during 2001 to quantify the impacts of lost fishing gear to coral reef sessile invertebrates. Lost hook-and-line fishing gear accounted for 87% of all debris (N=298 incidences) encountered and was responsible for 84% of the 321 documented impacts to sponges and benthic cnidarians, predominantly consisting of tissue abrasion causing partial individual or colony mortality. Branching gorgonians (Octocorallia) were the most frequently affected (56%), followed by milleporid hydrocorals (19%) and sponges (13%). Factors affecting the impacts of lost fishing gear include sessile invertebrate density, the density of lost fishing gear, and gear length. While lost hook-and-line fishing gear is ubiquitous in the Florida Keys, less than 0.2% of the available milleporid hydrocorals, stony corals, and gorgonians in the habitats studied are adversely affected in terms of colony abrasions and partial mortality.     

Improved detection of Mycobacterium tuberculosis and M. bovis in African wildlife samples using cationic peptide decontamination and mycobacterial culture supplementation

In South Africa, mycobacterial culture is regarded as the gold standard for the detection of Mycobacterium tuberculosis complex (MTBC) infection in wildlife even though it is regarded as “imperfect.” We compared a novel decontamination and mycobacterial culture technique (TiKa) to the conventional mycobacterium growth indicator tube (MGIT) system using known amounts of bacilli and clinical samples from MTBC-infected African buffaloes (Syncerus caffer), white rhinoceros (Ceratotherium simum), and African elephants (Loxodonta africana). Use of the TiKa-KiC decontamination agent on samples spiked with 10,000 to 10 colony forming units (cfu) of M. bovis (SB0121) and M. tuberculosis (H37Rv) had no effect on isolate recovery in culture. In contrast, decontamination with MGIT MycoPrep resulted in no growth of M. bovis samples at concentrations < 1,000 cfu and M. tuberculosis samples < 100 cfu. Subsequently, we used the TiKa system with stored clinical samples (various lymphatic tissues) collected from wildlife and paucibacillary bronchoalveolar lavage fluid, trunk washes, and endotracheal tube washes from 3 species with known MTBC infections. Overall, MTBC recovery by culture was improved significantly (p < 0.01) by using TiKa compared to conventional MGIT, with 54 of 57 positive specimens versus 25 of 57 positive specimens, respectively. The TiKa mycobacterial growth system appears to significantly enhance the recovery of MTBC members from tissue and paucibacillary respiratory samples collected from African buffaloes, African elephants, and white rhinoceros. Moreover, the TiKa system may improve success of MTBC culture from various sample types previously deemed unculturable from other species.