A nutrient biotic index (NBI) for use with benthic macroinvertebrate communities

Aquatic macroinvertebrates have been among the principal biological communities used for freshwater monitoring and assessment for several decades, but macroinvertebrate biomonitoring has not incorporated nutrient measures into assessment strategies. Two nutrient biotic indices were developed for benthic macroinvertebrate communities, one for total phosphorus (NBI-P), and one for nitrate (NBI-N). Weighted averaging was used to assess the distributions of 164 macroinvertebrate taxa across TP and NO₃⁻ gradients and to establish nutrient optima and subsequent nutrient tolerance values. Both the NBI-P and NBI-N were correlated with increasing mean TP and NO₃⁻ values (r = 0.68 and r = 0.57, respectively, p < 0.0001). A three-tiered scale of eutrophication for TP and NO₃⁻ (oligotrophic: ≤0.0175 mg/l TP, ≤0.24 mg/l NO₃⁻, mesotrophic: >0.0175 to ≤0.065 mg/l TP, >0.24 to ≤0.98 mg/l NO₃⁻, eutrophic: >0.065 mg/l TP, >0.98 mg/l NO₃⁻) was also established through cluster analysis of invertebrate communities using Bray–Curtis (quantitative) similarity. Significant differences (p < 0.0001) were detected between median NBI-P and NBI-N scores among the three trophic states. Therefore, the nutrient biotic indices (NBIs) appear to accurately reflect changes in stream trophic state. Multimetric water quality assessments were also used to identify thresholds of impairment among the three trophic states. Hodges-Lehman estimation indicated that the greatest change in assessment results occurred between the mesotrophic and eutrophic states. The eutrophic state also represented the highest percentage of overall impairment. Therefore, the suggested threshold for nutrient impairment is the boundary between mesotrophic and eutrophic (0.065 mg/l TP and 0.98 mg/l NO₃⁻). The corresponding NBI-P score (6.1) and NBI-N score (6.0) for this threshold incorporate predictive capabilities into the NBIs. The NBI and index score thresholds of impairment will provide monitoring programs with a robust measure of stream nutrient status and serve as a useful tool in enforcing regional nutrient criteria.     

Influence of nutrient supply on growth,carbohydrate, and nitrogen metabolic relations in Typha angustifolia

Performance of Typha angustifolia, a species common in European wetlands, was studied in connection with wetlands eutrophication. Cultivation in a sand culture was used to follow the effect of nutrient availability per se and to study, in detail, both aboveground as well as belowground organs (rhizomes and roots) of the plant in contrast to the possibilities of field study. A complex study of growth, carbohydrate, and nitrogen metabolic relationships, with respect to tissue age, was done in plants growing in nutrient solutions that differed in their levels of N and P (oligotrophic: 0.026 mM N and 0.001 mM P; eutrophic: 2.635 mM N and 0.0999 mM P; hypertrophic treatment: 9.539 mM N and 0.999 mM P).In contrast to the poor growth of Typha plants under the oligotrophic treatment, Typha coped best under the eutrophic treatment. Further increase in nutrient availability to the hypertrophic treatment did not result in additional stimulation of growth, but instead some negative reactions appeared. Changes in the growth and allocation of biomass, in favour of shoots and including rhizomes (as compared with roots) with increasing nutrient availability, were accompanied by an increase in N allocation and content of non-structural carbohydrates in these tissues. Detailed biochemical analysis revealed significant differences between tissues of different ages. These characteristics probably reflect the physiological potential of this species for their successful spreading in natural eutrophic habitats. Moreover, a decrease in the C/N ratio, decreasing proportion of starch/soluble sugars ratio, increasing proportion of hexoses/sucrose ratio (taking into account the type and tissue age of plant organs), with increasing nutrient availability, indicate high metabolic activity of the tissues at the stage of maximum growth.     

Changes in physicochemical and biological factors during regime shifts in a restoration demonstration of macrophytes in a small hypereutrophic Chinese lake

Shallow, eutrophic lakes are usually characterized by a turbid state devoid of submerged vegetation subject to human-induced eutrophication. In most cases, it is rather hard to restore a vegetated clear state due to reduced resilience caused by a blend of complicated factors. In this study, we successfully reestablished a plant community in a small hypereutrophic lake over a certain period. In winter and spring with transparency of >55 cm and temperature of <20 °C, a submerged stands bed formed gradually under strong human interventions. The reestablished plant bed displayed obvious seasonal succession and prolonged the clear-water stage until July 2005, when it collapsed. The regime shift to a turbid state was mainly attributed to the decreasing biomass of stands bed and mechanical damage brought about by the elimination of Spirodela polyrhiza, increasing water temperature, P concentration as well as periphyton biomass, etc. The reestablishment also changed the aquatic ecosystem greatly. A ‘clear-water’ stage was characterized by higher NO₃^?–N, NH₄⁺–N, electrical conductivity, transparency and TN/TP level and more cladocerans (mainly Daphnia pulex), while the turbid state was characterized by higher temperature, chlorophyll a and TP level and more abundant rotifers. It is thus viable to restore submerged macrophytes in such lakes in winter and spring, when transparency is relatively high while temperature and water level are low. Nevertheless, to obtain a long-term, vegetated clear state, control of internal nutrient loading by means of obstruction, purification, dredging or solidification, is extremely necessary since nutrients play an important role in regime shifts as evidenced by the present case, too.     

Enhancing the value of nitrogen from rapeseed meal for microbial oil production

Rapeseed meal, a major byproduct of biodiesel production, has been used as a low-cost raw material for the production of a generic microbial feedstock through a consolidated bioconversion process. Various strategies were tested for the production of a novel fermentation medium, rich in free amino nitrogen (FAN): commercial enzymes (CEs) (2.7 mg g^?1 dry meal), liquid state fungal pre-treatment (LSF) using Aspergillus oryzae (4.6 mg g^?1), liquid state fungal pre-treatment followed by fungal autolysis (LSFA) (9.13 mg g^?1), liquid state pre-treatment using fungal enzymatic broth (EB) (2.1 mg g^?1), but the best strategy was a solid state fungal pre-treatment followed by fungal autolysis (34.5 mg g^?1).The bioavailability of the nitrogen sources in the novel medium was confirmed in fed-batch bioreactor studies, in which 82.3 g dry cell L^?1 of the oleaginous yeast Rhodosporidium toruloides Y4 was obtained with a lipid content of 48%. The dry cell weight obtained was higher than that obtained using conventional yeast extract, due to a higher total nitrogen content in the novel biomedium. The fatty acids obtained from the microbial oil were similar to those derived from rapeseed oil.     

Estimation of the long-term nutrient budget and thresholds of regime shift for a large shallow lake in China

In this study, we apply an integrated empirical and mechanism approach to estimate a comprehensive long-term (1953–2012) total nitrogen (TN) and total phosphorus (TP) loading budget for the eutrophic Lake Chaohu in China. This budget is subsequently validated, firstly, by comparing with the available measured data in several years, and secondly, by model simulations for long-term nutrient dynamics using both Vollenweider (VW) model and dynamic nonlinear (DyN) model. Results show that the estimated nutrient budget is applicable for further evaluations. Surprisingly, nutrient loading from non-point sources (85% for TN and 77% for TP on average) is higher than expectation, suggesting the importance of nutrient flux from the soil in the basin. In addition, DyN model performs relatively better than VW model, which is attributed to both the additional sediment recycling process and the parameters adjusted by the Bayesian-based Markov Chain Monte Carlo (MCMC) method. DyN model further shows that the TP loading thresholds from the clear to turbid state (631.8 ± 290.16 t y⁻¹) and from the turbid to clear state (546.0 ± 319.80 t y⁻¹) are significantly different (p < 0.01). Nevertheless, the uncertainty ranges of the thresholds are largely overlapped, which is consistent with the results that the eutrophication of Lake Chaohu is more likely to be reversible (74.12%) than hysteretic (25.53%). The ecosystem of Lake Chaohu shifted from the clear to turbid state during late 1970s. For managers, approximately two-thirds of the current TP loading must be reduced for a shift back with substantial improvement in water quality. Because in practice the reduction of loading from a non-point source is very difficult and costly, additional methods beyond nutrient reduction, such as water level regulation, should be considered for the lake restoration.     

Effect of follicular wave synchronization on in vitro embryo production in heifers

Aiming to achieve the ideal time of ovum pick-up (OPU) for in vitro embryo production (IVP) in crossbred heifers, two Latin square design studies investigated the effect of ovarian follicular wave synchronization with estradiol benzoate (EB) and progestins. For each experiment, crossbred heifers stage of estrous cycle was synchronized either with a norgestomet ear implant (Experiment 1) or a progesterone intravaginal device (Experiment 2) for 7 d, followed by the administration of 150 μg d-cloprostenol. On Day 7, all follicles >3 mm in diameter were aspirated and implants/devices were replaced by new ones. Afterwards, implant/device replacement was conducted every 14 d. Each experiment had three treatment groups. In Experiment 1 (n = 12), heifers in Group 2X had their follicles aspirated twice a week and those in Groups 1X and 1X-EB were submitted to OPU once a week for a period of 28 d. Heifers from Group 1X-EB also received 2 mg EB i.m. immediately after each OPU session. In Experiment 2 (n = 11), animals from Group 0EB did not receive EB while heifers in Groups 2EB and 5EB received 2 and 5 mg of EB respectively, immediately after OPU. The OPU sessions were performed once weekly for 28 d. Therefore, in both experiments, four OPU sessions were performed in heifers aspirated once a week and in Experiment 1, eight OPU sessions were done in heifers aspirated twice a week. Additionally, during the 7-d period following follicular aspiration, ovarian ultrasonography examinations were conducted to measure diameter of the largest follicle and blood samples were collected for FSH quantification by RIA. In Experiment 1, all viable oocytes recovered were in vitro matured and fertilized. Results indicated that while progestin and EB altered follicular wave patterns, this treatment did not prevent establishment of follicular dominance on the ovaries of heifers during OPU at 7-d intervals. Furthermore, the proposed stage of follicular wave synchronization strategies did not improve the number and quality of the recovered oocytes, or the number of in vitro produced embryos.     

Decomposition processes in soil of a healthy and a declining Phragmites australis stand

Decomposition processes were investigated in the soil of a declining, more eutrophic and a healthy, less eutrophic freshwater reed (Phragmites australis (Cav.) Trin. ex Steudel) stand in the littoral zone of Rožmberk fishpond, Czech Republic. Soil and pore water were sampled five times from April to October 1998. Chemical properties, CO₂ production in oxic and anoxic conditions, CH₄ production, denitrifying enzyme activity (DEA) and bacterial biomass were measured under laboratory conditions in suspensions prepared from homogenised soil samples. The more eutrophic West stand was more anaerobic than the East stand, with lower redox potential, lower pH and with a higher amount of organic acids, mainly acetic and lactic acid. Mean seasonal concentrations of total nitrogen in pore water, nitrogen of amino acids and proteins, and reducing sugars were all higher in the soil at the more eutrophic stand. Higher nutrient status and more reduced conditions at the more eutrophic stand were accompanied by (i) a limitation of aerobic microbial activities (CO₂ production in oxic conditions: 0.35 versus 0.54 μmol CO₂ cm⁻³ h⁻¹); lower DEA (4.0 versus 20.2 nmol N₂O cm⁻³ h⁻¹) and a lower proportion of bacteria that were active in aerobic conditions; (ii) by a prevalence of anaerobic over aerobic microbial processes; (iii) by a higher rate of methanogenesis (15.0 versus 11.5 nmol CH₄ cm⁻³ h⁻¹) and (iv) by an overall lower rate of microbial processes as compared to less eutrophied stand. The shift from aerobic to anaerobic microbial metabolism, and a coinciding restriction of metabolic activities at the more eutrophic stand are indicative of an elevated oxygen stress in the soil, associated with accumulation of metabolites toxic to both the micro-organisms and the reed. Possible links between eutrophication, decomposition processes in the soil and reed decline are discussed.     

A novel MODIS algorithm to estimate chlorophyll a concentration in eutrophic turbid lakes

A novel approach was developed to estimate phytoplankton biomass in eutrophic turbid lakes, using MODIS bands designed for land and atmospheric studies. The Baseline Normalized Difference Bloom Index (BNDBI) uses the difference of remote-sensing reflectance (Rrs, sr⁻¹) at 555 nm (band 4) and 645 nm (band 1) after baseline correction using bands at 469 nm and 859 nm: (Rrs′(555) − Rrs′(645))/(Rrs′(555) + Rrs′(645)). BNDBI takes advantage of the Chl-a’s absorption minimum near 572 nm and absorption maximum near 667 nm. Using data from Lake Chaohu, the index showed a strong relationship with Chl-a concentrations in conditions that would normally saturate more sensitive ocean-color sensors. Extensive field measurements were used to calibrate and validate the algorithm with unbiased root-mean-square-error (URMSE) of 47.9% when compared to in situ Rrs data. A reduced sensitivity to atmospheric effects was accomplished by using a baseline correction approach, anchored at 469 nm and 859 nm to correct the radiances at 555 nm and 645 nm. Radiative transfer simulations showed that the algorithm can be applied directly to MODIS Rayleigh-corrected reflectance (Rrc) after adjusting algorithm coefficients (URMSE uncertainty of 56.4% for MODIS Rrc data) for Chl-a concentrations <1000 μg L⁻¹. Comparative analyses showed that the index was resistant to changes in turbidity and organic matter concentrations. Theoretical simulations, image comparisons and spectral analyses demonstrated that the index was robust in a range of complex atmospheric and surface conditions, with different aerosol types, optical thickness (τ_a555), solar/viewing geometry, sun glint and thin clouds. A comparison with other MODIS and MERIS Chl-a algorithms for turbid waters showed that BNDBI provided consistent results with the advantage of using MODIS wavebands that remain unsaturated in high turbidity conditions. The BNDBI opens new possibilities to explore bio-optical dynamics in turbid eutrophic lakes using data from a range of satellite sources.     

Soil bacterial community structure and physicochemical properties in mitigation wetlands created in the Piedmont region of Virginia (USA)

Wetland creation is a common practice for compensatory mitigation in the United States. Vegetation attributes have been used as a quick measure of mitigation success in most post-creation monitoring, while little attention has been paid to soils that provide the substrate for flora and fauna to establish and develop. Created wetland soils are often found not indicative of ‘hydric soil’ with a lack of development of physicochemical properties (i.e., bulk density, moisture content, and carbon and nitrogen contents) comparable to those in natural wetlands. Moreover, soil bacterial communities are rarely examined though they are integrally involved in biogeochemical functions that are critical for ecosystem development in created wetlands. We analyzed soil physicochemistry and profiled soil bacterial community structure using amplicon length heterogeneity polymerase chain reaction (LH-PCR) of 16S ribosomal DNA in three relatively young wetlands (<10 years old) created in the Piedmont region of Virginia. We examined the data by site and by specific conditions of each site (i.e., induced microtopography and hydrologic regime). Multidimensional scaling (MDS) and analysis of similarity (ANOSIM) showed clear clustering and significant differences both in soil physicochemistry (Global R = 0.70, p = 0.001) and in soil bacterial community profiles (Global R = 0. 77, p = 0.001) between sites. Soil physicochemistry (Global R = 1, p = 0.005) and bacterial community structure (Global R = 0.79, p = 0.005) of soils significantly differed by hydrologic regime within a wetland, but not by microtopography treatment. A significant association was found between physicochemistry and bacterial community structure in wetland soils, revealing a close link between two attributes (ρ = 0.39, p = 0.002). C/N (carbon to nitrogen) ratio was the best predictor of soil bacterial community patterns (ρ = 0.56, p = 0.001). The diversity of soil bacterial community (Shannon's H′) differed between sites with a slightly higher diversity observed in a relatively older created wetland, and seemed also fairly determined by hydrologic regime of a site, with a relatively dry site being more diverse.     

Embryo production in superstimulated llamas pre-treated to inhibit follicular growth

Llamas are monotocous and the length of their gestation period varies between 342 and 350 days. Thus the average number of offspring any female can produce throughout her reproductive life is very limited to spread a desired genome. The multiple ovulation and embryo transfer (MOET) technique allows an alternative to this limitation and reduces the generation interval. The objective of this study was to evaluate embryo recovery in superstimulated llamas which had previously been hormone-treated to inhibit follicular growth. A total of 50 female llamas were monitored daily via rectal palpation and ultrasound and divided according to their ovarian follicular growth into four phases. The females in each phase were then randomly divided into two groups: A (n = 20) received a single dose of 1 mg of estradiol benzoate (EB) on the first day of the treatment + 100 mg of progesterone (P4) i.m. for 5 days with 5 animals per phase and B (n = 20) received 1 mg EB at onset + 150 mg P4 i.m. for a period of 5 days with 5 animals per phase. Group C (n = 10) or control did not receive any prior hormonal treatment and the females were in follicular phase I. All groups were monitored daily and, in the presence of ovarian follicles smaller than the dominant size at the end of treatment, all were superstimulated with 1000 IU eCG. For plasma progesterone concentration recording, daily blood samples were collected from days ?1 to 5 in the treated females in Group A and B. No significant differences were observed regarding the inhibition of follicle growth and in the plasma progesterone concentrations between Group A and B. The ovarian response to superstimulation was 56.2%, 71.4% and 90%, with the average number of dominant follicles produced per female being 4.4 ± 0.9; 4.8 ± 0.7 and 4.6 ± 0.6 in Groups A, B and C, respectively. The embryo recovery rate was 77.7%; 90% and 66.7% and the average number of embryos recovered per female was 2.9 ± 0.9; 2.6 ± 0.9 and 2.4 ± 0.8 for Groups A, B and C, respectively. In Groups A and B, the static follicular phase (III) seemed to be ideal for initiating the assisted reproductive technique of MOET. Although prior administration of P4 + EB seems to have no effect on the number of females that responded to the superstimulation treatments, the number of embryos recovered showed a tendency to be higher when ovarian follicle growth inhibition was performed beforehand.     

Signal transduction and amplification in a circadian oscillator: Interaction between two colored noises

The signal transduction and amplification in a Neurospora circadian clock system is studied by using the mechanism of internal signal stochastic resonance (ISSR). Two cases have been investigated: the case of no correlations between multiplicative and additive colored noises and the case of correlations between two noises. The results show that, in both cases, the noise-induced circadian oscillations can be transduced with the phenomenon of internal signal stochastic resonance (ISSR). However, the correlation time and intensity of an additive colored noise play different roles for the ISSR, driven by multiplicative colored noise, while the correlation time and intensity of multiplicative colored noise hardly influence the ISSR driven by additive colored noise. In addition, the ISSR can be amplified or suppressed at an appropriate range of the correlation intensity between two colored noises. The fundamental frequency of noise-induced circadian oscillations is hardly shifted with the increment of the intensity and correlation time of colored noises, which implies that the Neurospora system could be resistant to colored noises, exhibit strong vitality and sustain intrinsic circadian rhythms.     

Retrieval of phycocyanin concentration from remote-sensing reflectance using a semi-analytic model in eutrophic lakes

With the rapid development of the economy in recent years, massive algal (blue-green algae in particular) blooms have often observed in Chinese eutrophic lakes. The concentration of the cyanobacterial pigment phycocyanin (PC), an accessory pigment unique to freshwater blue-green algae, is often used as a quantitative indicator of blue-green algae in eutrophic inland waters. The purpose of this study was to evaluate the semi-analytic PC retrieval algorithm proposed by Simis et al. and to explore the potential to improve this PC algorithm so that it is more suitable for eutrophic lakes, such as Taihu Lake. In this paper, we recalculated the correction coefficients γ and δ to calculate the absorptions of chlorophyll-a at 665 nm and the absorptions of phycocyanin at 620 nm in terms of in situ measurements and observed that the values of these coefficients differed from the values used by Simis et al. and Randolph et al. The two coefficients are site dependent due to the different bio-optical properties of lakes. We also observed that the specific PC absorption at 620 nm a_pc*(620) decreases exponentially with an increase in PC concentrations. Therefore, a non-linear power–function of a_pc*(620), instead of a constant value of a_pc*(620) as used by Simis et al., was proposed for our improved PC retrieval algorithm in Taihu Lake, yielding a squared correlation coefficient (R²) of 0.55 and a root mean square error (RMSE) of 58.89 μg/L. Compared with the original PC retrieval algorithm by Simis et al., the improved retrieval algorithm has generally superior performance. In evaluating the limitation of the PC retrieval algorithms, we observed that the ratio of the total suspended solids to phycocyanin can be used as a primary measure for retrieval performance. Validation in Dianchi Lake and an error analysis proved that the improved PC algorithm has a better universality and is more suitable for eutrophic lakes with higher PC concentrations.     

Analyse comparative de 3 logiciels de reconstruction itérative de tomoscintigraphie monophotonique myocardique

ObjectiveThis study makes a comparative analysis of the quality reconstruction of three software: 2D ordered subset expectation maximisation (2D OSEM), 3D ordered subsets expectation maximisation (Flash 3D) and Wallis.Patients and methodsThe data from myocardial scintigraphy acquisitions of 50 patients (38 men and 12 women; average age 61 ± 9 years) were successively reconstructed using three myocardial perfusion SPECT algorithms (Flash 3D, OSEM 2D and Wallis). Different combinations of iterations and subsets were considered. For Wallis, only the cut-off frequency was considered. The image's quality was assessed by determining the maximum contrast and the signal to noise ratio.ResultsThe Wallis software provided a higher signal to noise ratio compared to Flash 3D and OSEM 2D at stress and rest. The Wallis signal to noise ratio increased by a factor 1.93 (P = 0.0010) and 2.28 at stress (P = 0.0009); 1.50 (P = 0.0011) and 2.84 at rest (P = 0.0024) compared to respectively Flash 3D and OSEM 2D. Flash 3D provided better signal to noise ratio than OSEM 2D at stress and at rest. The difference in medians and interquartile ranges of the signal-to-noise ratio in post-stress were 22 % and 54 %, respectively between Flash 3D and OSEM 2D. At rest, the difference between the two methods in signal to noise ratio was 32 % ± 0.,29.ConclusionWallis algorithm was improve image quality with better signal to noise ratio compared to the reference method of Siemens Flash 3D. For both Flash 3D and OSEM 2D methods, the combination with 8 subsets and 12 iterations provided the best contrast and signal to noise ratio.     

Predominance of terrestrial organic matter in sediments from a cyanobacteria- blooming hypereutrophic lake

Although an understanding of the quantity and quality of sedimentary organic matter (SOM) pools is necessary to design sound environmental management strategies for lacustrine systems, the characterization of organic matter sources and the assessment of their relative contributions to eutrophic and inland lake sediments remain insufficient. In this study, the contribution of potential organic matter sources to sediments in shallow and hypereutrophic lake Taihu, China was assessed on the molecular level using source-specific fatty acid biomarkers. The results indicated that SOM was composed mainly of terrestrial plants with a maximal contribution of 45.3 ± 2.4% to the total organic carbon, which accounted for approximately 66% among the determined organic matter sources. Evidence suggests the terrestrial plants remained in a fresh state in surface sediments: the correlation (R² = 0.62, p < 0.05) between bacterial and terrestrial plant carbon was strong. On the other hand, aquatic plant and bacterial carbon contributed 5–15% to the total organic carbon, which was followed by the faint contribution (<5% of total organic carbon) of algae-derived organic carbon including cyanobacteria, diatoms, and dinoflagellates. The results provided details of the contributions of SOM sources, illustrating the usefulness of fatty acid biomarkers in discriminating organic matter sources within lake environments. Although organic matter sources of sediments varied in spatial and temporal patterns, the strong correlation between terrestrial plant and total organic carbon (R² = 0.60, p < 0.05) indicates that terrestrial plants were the dominant source in lake sediments.     

Biomonitoring potential of a Caryophyllaeid tapeworm: Evaluation of Adenoscolex oreini infection level and health status in three fish species of the genus Schizothorax across eutrophication and pollution gradients

Endoparasitic infections vary significantly across altered aquatic ecosystems, making these organisms ideal for the biomonitoring of degraded environments. To assess the biomonitoring potential of the Caryophyllaeid tapeworm Adenoscolex oreini and the possible impact of water quality on fish species, a study was carried out in three lakes with marked eutrophication and pollution gradients. The A. oreini infection level in three host fish species of the genus Schizothorax and corresponding fish health status were determined. The pattern of cestode infection varied significantly in the three fish species across the pollution gradient. The prevalence of infection in two fish species (Schizothorax esocinus and S. curvifrons) was significantly greater (P < 0.05) in the eutrophic lake than in the reference lake, whereas in S. niger, the maximum was reached in the hypereutrophic lake. The estimated marginal mean intensity and other infection indices varied significantly (P < 0.05) across the inter- and intra-pollution gradients of lakes. Multivariate statistical analysis results revealed maximum cestode infection in the eutrophic lake. An altered seasonal pattern was observed in the highly stressed lake. The gonadosomatic index (GSI) and condition factor values were significantly greater in fish collected from the reference lake than in those collected from the other lakes. A significant negative relationship between GSI and cestode prevalence was observed in the hypereutrophic lake as compared to least eutrophic lake. These findings indicate that infection indices of the Caryophyllaeid tapeworm and health attributes of fish can act as surrogates for the environmental quality of deteriorated lentic water bodies of the north-western Himalayan region, which is currently undergoing environmental degradation.     

Effect of the metal dilution on the thermal and light-induced spin transition in [FexMn1−x(bpp)2](NCSe)2: When T(LIESST) reaches T1/2

The thermal and light-induced spin transition in [Fe_xMn_1?x(bpp)₂](NCSe)₂ (bpp = 2,6-bis(pyrazol-3-yl)pyridine) has been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and exhibit the light-induced excited spin state trapping (LIESST) effect at low temperature. For each mixed-crystal system, the thermal spin transition temperature, T_1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T_1/2 decreases with the metal dilution while T(LIESST) remains unchanged, suggesting that the two interconversion processes are controlled by different factors; i.e. the photomagnetic properties are governed at the molecular scale and the thermal spin crossover regime is affected by both the ligand field and crystal packing effects. For highly metal-diluted complex with x < 0.2, it is found that when T_1/2 reaches the T(LIESST), the complex remains HS on the whole range of temperature.     

The tempo-spatial variations of phytoplankton diversities and their correlation with trophic state levels in a large eutrophic Chinese lake

Lake Chaohu is one of the most eutrophic lakes in China. Research on this lake's seasonal and spatial variations in phytoplankton diversity is needed to understand the distribution of eutrophication, as well as to find appropriate comprehensive biodiversity indices to assess the eutrophication status of the lake. The present study indicated that the Margalef index of all samples was as low as 0.799 ± 0.543 in summer (August 2011) and as high as 1.467 ± 0.653 in winter (February 2012). The Margalef index of the river samples had a high mean value and substantial variation compared with the lake samples. The Peilou index of the lake samples was higher than that of the river samples in summer and autumn (November 2011) but lower than that of the river samples in winter. In spring (May 2012), the Peilou index of the western samples was lower than that of the eastern samples. The spatial distribution of the Shannon–Wiener index was more similar to that of the Peilou index in autumn and winter, while in spring and summer, the spatial distribution was affected by both species richness and evenness. High eutrophication levels occurred in the western lake in spring and summer, whereas high levels occurred in the eastern lake, especially in the middle of the lake, in autumn and winter. The total trophic state index (TSI) in all samples exhibited a significant negative correlation with the Margalef (r = −0.726) and Peilou (r = −0.530) indices but a significant positive correlation with the Shannon–Wiener (r = 0.654) index. The partial correlation analysis results implied that these phytoplankton biodiversity indices could serve as synthetic ecological indicators to assess the eutrophication condition of Lake Chaohu.     

Effects of temperature on purification of eutrophic water by floating eco-island system

The effects of temperature on pollutant removal of two plant species (Oenanthe javanica D.C. and Nasturtium officinale) were evaluated using simulated microcosms of the floating eco-island system (FEIS). Both the planted FEIS (P-FEIS) and the non-planted FEIS (NP-FEIS) dramatically decreased NH₄–N concentration in the hypereutrophic water at low (10 °C), medium (22 °C), and high (35 °C) temperatures, and to a greater extent for the P-FEIS and at medium temperature. The NO₂–N concentration was effectively decreased from 0.23 to 0.01 mg/L after 4 d treatment with the P-FEIS at all the three temperatures, but was slightly increased in the NP-FEIS at low temperature. The P-FEIS could decrease NO₃–N concentration in the eutrophic water over 1–3 times depending on temperature, with greater decrease at high temperature. The remove of total P (TP) reached 78%, on average, with the FEIS treatment for 4 d at all temperatures, which was over three times greater than those with the NP-FEIS at low temperature. The removal rates of Chla, COD_Mn, and BOD₅ by the P-FEIS from the hypereutrophic water were, on average, 70%, 85%, 83% at 22 °C and 35 °C, respectively, while over 1–2 times smaller at 10 °C. More effective removals of Chla, COD_Mn, and BOD₅ (over 1–2 times) were noted with the P-FEIS than those with the NP-FEIS. N. officinale showed more efficiency in removing ammonium and TN at low temperature, and BOD₅ at medium and high temperatures, as compared to O. javanica. Whereas O. javanica could more effectively decrease Chla at 22 °C and 35 °C and COD_Mn at 10 °C than N. officinale after 4 d treatment. Higher dissolved oxygen concentration and pH was found in the FEIS with N. officinale than that with O. javanica D.C. The results imply that plant eco-island system had remarkable purification ability to remove pollutants from hypereutrophic water, and mixed planting of O. javanica D.C. with N. officinale on the FEIS may enhance nutrient removal and water quality improvement of eutrophic water bodies, especially at low temperature season.     

Kinematic analyses of trunk stability in one leg standing for individuals with recurrent low back pain

This prospective study examined normalized stability differences based on dominance side and visual feedback. Subjects with low back pain (LBP) (n = 26; 9 men, 17 women) and without LBP (n = 28; 11 men, 17 women) participated in this study. All subjects were asked to maintain single leg standing balance with the contralateral hip flexed 90° for 25 s. The outcome measures included normalized holding duration and stability. The combined rotation (R_xyz) was also calculated to compare the upper and lower thorax and lumbar axes relative to the core spine axis. The holding duration was significantly different between groups (T = ?2.21, p = 0.03). The subjects without recurrent LBP (control group) demonstrated longer hold duration times (24.60 ± 4.2 s) than the subjects with recurrent LBP (21.2 ± 7.1 s). For the normalized hold duration, there was a significant difference between groups based on visual input (F = 7.13, p = 0.009). There was also a significant difference in standing stability based on visual input (F = 93.93, p = 0.0001) and trunk area (F = 101.51, p = 0.0001). In addition, the normalized stability was significantly different based on dominance and visual input (F = 11.28, p = 0.002). Therefore, trunk stability could prompt an uncoordinated bracing effect with poor proprioception from injury to passive structures or due to interference of pain during central processing of information in subjects with recurrent LBP.     

Enhanced ethanol production by continuous fermentation in a two-tank system with cell recycling

An experimental method for producing ethanol continuously was designed and tested with a cell-recycling two-tank system, which was composed of two fermentors, each of which was individually equipped with a settler for recycling flocculent yeast. This system was effective for the continuous fermentation of ethanol from sucrose at high cell-recycling (r = 0.8–0.9) and dilution (up to 0.48 h^?1) rates. The system has several advantages; the high cell concentration in the fermentors and relief of substrate and product inhibition. Thus, the enhanced productivity using this continuous fermentation with the two-tank cell-recycling system was significantly higher compared with that of the batch fermentation. The results indicate that increased recycling ratios caused an increase in biomass concentration and subsequently, product concentration in the tank. The ethanol productivity increased with the dilution rate, but higher dilution rates could render increasing amounts of sugar unconverted. Continuous fermentation with the sugar feed concentration of 160 g/l at r = 0.9 and dilution rate of 0.2 h^?1 achieved the highest productivity with less than 2% of the unconverted sugar in the product steam. Under the same cell recycling ratios a productivity range of 6.9–7.5 g/l h^?1 could be achieved with feeding concentrations of 80–200 g/l, while batch fermentation at these sugar concentrations led to productivities of 3.85–4.48 g/l h^?1.