Comparison of isotope-based linear and Bayesian mixing models in determining moisture recycling ratio

Stable water isotopes are natural tracers quantifying the contribution of moisture recycling to local precipitation,i.e.,the moisture recycling ratio,but various isotope-based models usually lead to different results,which affects the accuracy of local moisture recycling.In this study,a total of 18 stations from four typical areas in China were selected to compare the performance of isotope-based linear and Bayesian mixing models and to determine local moisture recycling ratio.Among the three vapor sources including advection,transpiration,and surface evaporation,the advection vapor usually played a dominant role,and the contribution of surface evaporation was less than that of transpiration.When the abnormal values were ignored,the arithmetic averages of differences between isotope-based linear and the Bayesian mixing models were 0.9%for transpiration,0.2%for surface evaporation,and–1.1%for advection,respectively,and the medians were 0.5%,0.2%,and–0.8%,respectively.The importance of transpiration was slightly less for most cases when the Bayesian mixing model was applied,and the contribution of advection was relatively larger.The Bayesian mixing model was found to perform better in determining an efficient solution since linear model sometimes resulted in negative contribution ratios.Sensitivity test with two isotope scenarios indicated that the Bayesian model had a relatively low sensitivity to the changes in isotope input,and it was important to accurately estimate the isotopes in precipitation vapor.Generally,the Bayesian mixing model should be recommended instead of a linear model.The findings are useful for understanding the performance of isotope-based linear and Bayesian mixing models under various climate backgrounds.

Comparative Study of Salinity Tolerance an Oceanic Sea Skater, <i>Halobates</i><i>micans</i>and Its Closely Related Fresh Water Species, <i>Metrocoris</i><i>histrio</i>

This study aims, first, to examine the limit for tolerance to lower salinity by an oceanic sea skater, Halobates micans, and , second, to make it clear whether exclusively fresh water Halobatinae species, Metrocoris histrio has salinity tolerance. Adults of H. micans were collected using Neuston Net from the starboard side of R/V MIRAI on a fixed station at 8°S, 80°E, whereas those of M. histrio were collected from a small pond filled with a spring fresh water in Kochi (33°N, 133°E), Japan. Time in survival was measured in starved condition under several salinity conditions: 0‰, 2‰, 4‰, 6‰, 8‰, 9‰ and 10‰ for H. micans;0‰, 5‰, 10‰, 12.5‰, 15‰ for M. histrio. Half of adults were in coma due to lower salinity under 10‰ and time in survival was less than 10 hours under less than 4‰ for H. micans. Time in survival was half at 5‰ of 80 hours on average at 0‰ as a control and less than 10 hours at 10‰ or higher salinity for M. histrio. Relatively flexible osmo-regulation ability by H. micans would be related to wide variety of salinity condition of surface oceanic water, whereas very limited tolerance even to lower salinity of 5‰ may be permitted by the no chances to be exposed to brackish water in natural habitats of M. histrio. This study showed that salinity tolerance of Halobatinae species would reflect, directly, the salinity condition of their habitats.

Recent Advances in Japanese Fisheries Science in the Kuroshio-Oyashio Region through Development of the FRA-ROMS Ocean Forecast System: Overview of the Reproducibility of Reanalysis Products

To address various fisheries science problems around Japan, the Japan Fisheries Research and Education Agency (FRA) has developed an ocean forecast system by combining an ocean circulation model based on the Regional Ocean Modeling System (ROMS) with three-dimensional variational analysis schemes. This system, which is called FRA-ROMS, is a basic and essential tool for the systematic conduct of fisheries science. The main aim of FRA-ROMS is to realistically simulate mesoscale variations over the Kuroshio-Oyashio region. Here, in situ oceanographic and satellite data were assimilated into FRA-ROMS using a weekly time window. We first examined the reproducibility through comparison with several oceanographic datasets with an Eulerian reference frame. FRA-ROMS was able to reproduce representative features of mesoscale variations such as the position of the Kuroshio path, variability of the Kuroshio Extension, and southward intrusions of the Oyashio. Second, using a Lagrangian reference frame, we estimated position errors between ocean drifters and particles passively transported by simulated currents, because particle tracking is an essential technique used in applications of reanalysis products to fisheries science. Finally, we summarize recent and ongoing fisheries studies that use FRA-ROMS and mention several new developments and enhancements that will be implemented in the near future.

Comparison of temperature preference for habitat among three species of oceanic sea skaters,Halobates micans,H.germanus and H.sericeus

The main purpose of this study is to investigate temperature preference for habitat of three species of oceanic sea skaters, Halobates micans, H. germanus and H. sericeus. For each of the three species, we examined the relationship between population density and surface water and air temperatures in the sampling sites during three science cruises in the tropical to temperate zone of the Pacific Ocean. A higher density of H. micans was observed in sites with higher water and air temperatures at 28℃?- 30℃?than that at site with lower temperatures of 23℃?- 28℃. A higher density of H. germanus was observed in sites with extremely high temperatures of 29.6℃?and 30℃?than that in sites with moderately high temperatures of 28℃?- 29℃?in the Pacific Ocean, while a relatively high density was observed in sites with a wide range of temperatures from 24℃?- 30℃?in the southern hemisphere Pacific Ocean. The relatively low temperature preference of 23℃?- 28℃?exhibited by H. sericeus may be related to its size as the smallest among the three species and its relatively wide latitudinal distribution ranging up to 40?N.

关于黄海深部构造的地球物理认识

利用黄海海区重磁观测数据,以最新的地震层析成像和浅层反射地震探测结果作为约束,并利用小波分解、纹理特征图像处理等手段,对研究区进行了地球物理场特征分析、岩石物性总结、断裂信息提取和磁性基底埋深反演计算,同时对南黄海海域三条剖面进行了广义逆重磁数据拟合反演和地震P波速度成像.根据地球物理数据的各种处理结果,提出在南黄海西部存在一条串珠状地球物理线性构造带,并将这条NNW向断续延伸的构造带称之为南黄海西缘断裂带.该断裂带延伸长,断裂两侧前新生代地层差异较大,有可能是造成陆区和南黄海南部盆地区前新生代油气远景差异的原因之一.文中得到南黄海磁性基底埋藏分布具有"中间浅四周深"的分布特征,与地震层析成像结果相吻合.磁性基底的局部起伏和局部构造的边界断层共同控制了前新生代残留盆地的格架和残余厚度分布,反映出"区域控制局部,深层约束浅层"的规律.

方向分布对三维聚焦波浪波面特性影响研究

波浪聚焦被认为是产生极限波浪的重要机理之一,近年来受到普遍重视。通过高阶谱方法,引入造波边界建立数值计算模型,模拟聚焦波浪在不同方向分布时的产生和聚焦过程,研究波浪的方向分布对聚焦波浪的波面、波峰最大值、聚焦点的偏移、波面参数及频谱的影响。研究结果表明波浪方向分布越窄,波浪的非线性影响越强、波面越陡,波峰值、聚焦点的偏移和波面特征参数都越大;同时方向分布对波浪聚焦前后的能量具有很大的影响。

日本凋毛藻(Griffithsiajaponica)硫氧还蛋白基因及其编码的蛋白特征

从日本凋毛藻的表达序列标记 EST库中筛选到 2 条全长的编码硫氧还蛋白的 cDNA序列,分别命名为GjTRX1和GjTRX2。将这2条基因编码的蛋白序列与其它藻类(包括酵母)进行比较,结果表明不同物种及同一物种间TRX的相似性都较差,除GjTRX2编码的蛋白序列外,所有蛋白在活性位点序列 WCGPC处都完全保守。推测GjTRX1属于细胞质内分布的硫氧还蛋白。GjTRX1序列推导的蛋白二级结构单元与以往报道的传统上保守的TRX的二级结构单元类型一致,但是顺序有所不同。

The arms race between Magnaporthe oryzae and rice: Diversity and interaction of Avr and R genes

Rice blast disease, caused by Magnaporthe oryzae, threatens global food security. The rice blast pathosystem is a longstanding model system for understanding plant-microbe interactions. In order to elucidate the coevolution of the host and pathogen, and provide the appropriate methods for preventing or controlling rice blast disease, researchers have focused on the evolution of virulence factors and resistance genes. Thus far, more than 30 rice blast resistance（R） genes and 12 avirulence（Avr） genes have been cloned. This review summarizes the cloned rice blast R genes, cloned Avr genes of M. oryzae and the interaction between them. This discussion also considers some of the major unanswered questions concerning this pathosystem and the opportunities for future investigations.

Analysis of influencing factors on fine sediment flocculation in the Changjiang Estuary

Based on the test data in dynamic water and static water, the main factors, which influence the fine sediment flocculation, are analyzed with a gray model method of correlation theory. It is shown that the main influencing factors are water temperature, settling time, salinity, grain size, sediment concentration and current velocity according to the correlation coefficients. Among them, the salinity and the sediment grain size are critical type influencing factors (CrTIF); the settling time, the sediment concentration and the velocity are continuous type influencing factors (CoTIF); and the water temperature has the characteristics of both. When the critical values of CrTIF are reached or exceeded, the fine sediments will be flocculated, but values of CrTIF will not influence the settlement strength of floes. The influence of CoTIF is continuous. The values of the CoTIF will not only influence the occurrence of flocculation but also the settlement strength of the floes.

An improved ion-exchange/diffusion method for ～(15)N isotope tracing analysis of nitrate in surface waters from watersheds

An improved method,suitable for collecting nitrate from surface waters in the watershed for 15 N isotope tracing analysis,was developed on the basis of the anion exchange coupled with diffusion through systematic simulation and comparison experiments.The results showed that the nitrate could be separated and enriched from the waters efficiently by using the improved method.Being simple and practical in operation principle and procedures,cost-economic,and highly efficient in nitrate separation/enrichment,the method met the requirements of δ 15 N mass spectrum analysis and would lay a foundation for the application of 15 N isotope tracing approach to the research on non-point source pollution in watershed.

A Robust and Economical Underwater Stereo Video System to Observe Antarctic Krill (Euphausia superba)

In situ characterization of krill morphometry, behaviour and orientation is not yet routinely feasible, yet is critical to understanding swarm characteristics. A first step is to measure individual and aggregation behaviour. We report on successful use of a robust, low-cost underwater stereo video camera system to observe live Antarctic krill (Euphausia superba) in aquaria. The application of photogrammetry techniques allows animal length, orientation and three-dimensional position to be calculated from stereo video camera observations. Initially, we tested the efficacy of the stereo system by observing synthetic targets of known length and orientation to obtain estimates of measurement error. We found that on average the stereo camera system underestimated length by 0.6 mm and vertical tilt angle by +0.34°(head up), but that photogrammetric measurements of 100 randomly selected krill lengths were not significantly different from measurements of 100 randomly caught krill measured physically. During our investigation, we analysed three krill behavioural metrics: swimming speed, tortuosity, and vertical orientation under three behavioural states (undisturbed, feeding, and escape). We found that swim speed and tortuosity significantly increased when animals were feeding or exhibiting an escape response, but vertical orientation was not significantly different across states. Our investigation demonstrates that low-cost stereo video cameras can produce precise measurements that can be used for monitoring krill behaviour and population structure.

The impact of Kuroshio water on the source water of the southeastern Taiwan Strait:numerical results

Model output from a Pacific basin-wide three-dimensional physical-biogeochemical model during the period of 1991 to 2008 was used to investigate the impact of Kuroshio water on the source water of the southeastern Taiwan Strait. Based on the characteristic salinities of both Kuroshio water and the South China Sea water, a Kuroshio impact index （KII） was designed to measure the degree of impact. The KII correlates significantly with the northeast-southwest component of wind stress, but the former lags the latter by approximately two months. The correlation coefficient between them increases from 0.267 4 to 0.852 9, with a lag time increasing from 0 to 63 days. The impact of Kuroshio Water is greater in winter and spring than in summer and autumn. At the interannual time scale, E1 Nifio and La Nifia events play an important role in impacting the KII. During E1 Nifio events, more Kuroshio water contributes to the source water of the southeastern Taiwan Strait. Conversely, during La Nifia events, less Kuroshio water contributes to the source water.

Analysis and Evaluation of the Global Aerosol Optical Properties Simulated by an Online Aerosol-coupled Non-hydrostatic Icosahedral Atmospheric Model

Aerosol optical properties are simulated using the Spectral Radiation Transport Model I~）r Aerosol Species （SPRINTARS） coupled with the Non-hydrostatic ICosahedral Atmospheric Model （NICAM）. The 3-year global mean all-sky aerosol optical thickness （AOT） at 550 nm, theAngstr/Sm Exponent （AE） based on AOTs at 440 and 870 nm, and the single scattering albedo （SSA） at 550 nm are estimated at 0.123, 0.657 and 0.944, respectively. For each aerosol species, the mean AOT is within the range of the AeroCom models. Both the modeled all-sky and clear-sky results are compared with observations from the Moderate Resolution Imaging Spectroradiometer （MODIS） and the Aerosol Robotic Network （AERONET）. The simulated spatiotemporal distributions of all-sky AOTs can generally reproduce the MODIS retrievals, and the correlation and model skill can be slightly improved using the clear-sky results over most land regions. The differences between clear-sky and all-sky AOTs are larger over polluted regions. Compared with observations from AERONET, the modeled and observed all-sky AOTs and AEs are generally in reasonable agreement, whereas the SSA variation is not well captured. Although the spatiotemporal distributions of all-sky and clear-sky results are similar, the clear-sky results are generally better correlated with the observations. The clear-sky AOT and SSA are generally lower than the all-sky results, especially in those regions where the aerosol chemical composition is contributed to mostly by sulfate aerosol. The modeled clear-sky AE is larger than the all-sky AE over those regions dominated by hydrophilic aerosol, while the＇opposite is found over regions dominated by hydrophobic aerosol.

Decadal Changes in Climatological Intraseasonal Fluctuation of Subseasonal Evolution of Summer Precipitation over the Korean Peninsula in the mid-1990s

Decadal changes in the subseasonal evolution and the phase-locked climatological intraseasonal fluctuation of summertime rainfall over the Korean Peninsula before and after the mid-1990s are investigated.The activity and the migration speed of the monsoon rain band over the East Asian region are altered in the recent decade,resulting in the drier conditions in late spring and the earlier onset of Changma.In early August when a climatological monsoon break was clear in the earlier decade,the precipitation has increased dramatically with a meridional coherency.The response to the enhanced convection over the South China Sea and southeastern China provides a favorable condition for more precipitation in early August through the changes in moisture transport and tropical cyclone passage.

Fractional crystallization processes of magma beneath the Carlsberg Ridge(57°–65°E)

Fractional crystallization of basaltic magma at variable depths influences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs),especially at slow-spreading mid-ocean ridges.The Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian Ocean.In this study,we conducted petrological,geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°-65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB geochemistry.Our results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment;such heterogeneity may be ubiquitous beneath the Carlsberg Ridge.Mantle heterogeneity may be caused by the enriched components resulting in the"DUPAL"anomaly,whereas the effect of pyroxenite on mantle heterogeneity is negligible.The parental melts experienced crystallization of olivine,plagioclase and clinopyroxene prior to eruption,which played a significant role in the major and trace element variations in MORBs from the Carlsberg Ridge.The liquid lines of descent(LLDs),deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar,demonstrate that clinopyroxene joined the olivine and plagioclase cotectic.The over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma chambers.The calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.

Seasonal Dynamics of Nutrient Loading and Chlorophyll A in a Northern Prairies Reservoir, Saskatchewan, Canada

Harmful algae blooms have become an increasing concern in context with the safety of water resources around the globe;however, little is known about the dynamics and specific causes of such blooms in the prairie ecozone in North America. The aim of this study was to research the nitrogen (N) and phosphorous (P) content and nutrient limitation (defined as N and P limitation) of growth of cyanobacteria in a northern prairies reservoir (Lake Diefenbaker [LD], SK, Canada). A combination of concentration balance analysis for N and P, controlled bioassays with the natural consortium of phytoplankton or defined monocultures of cyanobacteria, and satellite imagery was applied to address this aim. The current trophic status of Lake Diefenbaker is one of moderate eutrophication. Primary production in the lake is P-limited, and N did not represent a limiting factor for algal production. There was no significant increase in TP con- centrations between the upper and lower portions of the reservoir, indicating that most of the phosphorus in LD comes from upstream sites in Alberta. Anabaena circinalis, a species that has the potential to seriously degrade lake ecosys- tems, was identified as the predominant cyanobacteria in LD. Together with the fact that TP influxes into the reservoir primarily originate from upstream sources, these results suggest the need for remedial measures in the upstream reach of the South Saskatchewan River. Satellite imaging represented a promising approach in support of monitoring for po- tential algal blooms in LD;however, due to limited sensitivity and issues associated with atmosphere interference this methodology should only be used in combination with in situ water quality monitoring. In summary, while this study indicated that Lake Diefenbaker is potentially at risk with cyanobacteria blooms (some of which such as Anabena sp. that can produce toxins) during late summer and fall, development of clear causal relationships and risk assessment strategies is currently limited due to lack of monitoring data and programs.

Seasonal dynamics of meiofaunal distribution in the Dagu River Estuary, Jiaozhou Bay, China

Sediment samples were collected in the intertidal zone of the Dagu River Estuary, Jiaozhou Bay, China in April,July and October 2010 and February 2011 for examining seasonal dynamics of meiofaunal distribution and their relationship with environmental variables. A total of ten meiofaunal taxa were identified, including free-living marine nematodes, benthic copepods, polychaetes, oligochaetes, bivalves, ostracods, cnidarians, turbellarians,tardigrades and other animals. Free-living marine nematodes were the most dominant group in both abundance and biomass. The abundances of marine nematodes were higher in winter and spring than those in summer and autumn. Most of the meiofauna distributed in the 0–2 cm sediment layer. The abundance of meiofauna in hightidal zone was lower than those in low-tidal and mid-tidal zones. Results of correlation analysis showed that Chlorophyll a was the most important factor to influence the seasonal dynamics of the abundance, biomass of meiofauna and abundances of nematodes and copepods. CLUSTER analysis divided the meiofaunal assemblages into three groups and BIOENV results indicated that salinity, concentration of organic matter, sediment sorting coefficient and sediment median diameter were the main environmental factors influencing the meiofaunal assemblages.

Inferring the Tree of Life of the order Cypriniformes, the earth＇s most diverse clade of freshwater fishes： Implications of varied taxon and character sampling

The phylogenetic relationships of species are fundamental to any biological investigation, including all evolutionary studies. Accurate inferences of sister group relationships provide the researcher with an historical framework within which the attributes or geographic origin of species (or supraspecific groups) evolved. Taken out of this phylogenetic context, interpretations of evolutionary processes or origins, geographic distributions, or speciation rates and mechanisms, are subject to nothing less than a biological experiment without controls. Cypriniformes is the most diverse clade of freshwater fishes with estimates of diversity of nearly 3,500 species. These fishes display an amazing array of morphological, ecological, behavioral, and geographic diversity and offer a tremendous opportunity to enhance our understanding of the biotic and abiotic factors associated with diversification and adaptation to environments. Given the nearly global distribution of these fishes, they serve as an important model group for a plethora of biological investigations, including indicator species for future cli-matic changes. The occurrence of the zebrafish, Danio rerio, in this order makes this clade a critical component in understanding and predicting the relationship between mutagenesis and phenotypic expressions in vertebrates, including humans. With the tremendous diversity in Cypriniformes, our understanding of their phylogenetic relationships has not proceeded at an acceptable rate, despite a plethora of morphological and more recent mo-lecular studies. Most studies are pre-Hennigian in origin or include relatively small numbers of taxa. Given that analyses of small numbers of taxa for molecular characters can be compromised by peculiarities of long-branch attraction and nodal-density effect, it is critical that significant progress in our understanding of the relationships of these important fishes occurs with increasing sampling of species to mitigate these potential problems. The recent Cypriniformes Tree of Life initiative is an effort to achieve this goal with morphological and molecular (mitochondrial and nuclear) data. In this early synthesis of our understanding of the phylogenetic relationships of these fishes, all types of data have contributed historically to improving our understanding, but not all analyses are complementary in taxon sampling, thus precluding direct understanding of the impact of taxon sampling on achieving accurate phylogenetic inferences. However, recent molecular studies do provide some insight and in some instances taxon sampling can be implicated as a variable that can influence sister group relationships. Other instances may also exist but without inclusion of more taxa for both mitochondrial and nuclear genes, one cannot distinguish between inferences being dictated by taxon sampling or the origins of the molecular data.

Locomotor activity rhythm in the Japanese eel Anguilla japonica elvers

Under artificial LD cycles （6, 12, 18 L）, the elvers of Japanese eel, Anguilla japonica, showed a 24 h cycle of locomotor activity rhythm being most active at light transitions ： the eels＇ activity rose to a primary peak after lights-off, followed by a quiescent period during which they buried into the shelters or lying motionlessly on sand for most of the time, and then reached a secondary peak before lights-on. Elvers could resynchronize their activity rhythm with a new photo cycle within 4 d. Moreover, their activity level at dark phase significantly increased as the light period was prolonged ： higher activity levels during shorter dark period. However, the elvers did not display clearly the existence of a circadian rhythm under constant light or dark conditions. The timing of daily activity rhythm evidenced in the Japanese eels may occur through the action of the LD cycles with a weak participation of an endogenous circadian system. In all the LD cycles, over 99% of the activity occurred in the dark phase, indicating that the eels were always nocturnally active no matter what time of day it might be. Under 12 L conditions, the eels＇ activity level and the time outside sand were significantly elevated both at light and dark phases as temperature increased from 10 - 15 to 20 - 25 ℃. The activity rhythm pattern （ i. e. , two peaks occurring around light transitions） did not apparently change among temperatures. However, in contrast with the primary activity peaks immediately after lights-off at 20 and 25 ℃, the timing of the primary peaks at 10 and 15 ℃ showed a latency of a few hours following lights-off, indicating the inhibiting effect of low temperature on the eels＇ activity.