Relationship between the riverine nitrate–nitrogen concentration and the land use in the Teshio River watershed, North Japan

The present research investigated the relationship between nitrate–nitrogen (NO₃–N) in river water and the land use/land cover (hereafter, land use) in the Teshio River watershed located in northern Hokkaido island to understand the effect of human activities such as agriculture, forestry, industry, and urbanization in the drainage basin on the river ecosystem quality and services. River water was sampled at nine points seasonally during a 2-year period and the nutrients concentration was measured. Land use profiles were estimated at two spatial scales, riparian and sub-catchment, for each sampling station. The spatial pattern of water quality in the Teshio River showed increased NO₃–N levels associated with agriculture and urban expansion, and forest reduction in the watershed. Land use at the riparian scale closely reflected that at the sub-catchment scale, which masked the unique riparian buffer effect on the river water condition. The increased agricultural and reduced forest area in the riparian zone, especially in the upper middle reach, could be a possible reason for a decline of ecosystem service for the provisioning of clean water and habitat for aquatic organisms. Measures towards sustainable and more nature-friendly agricultural management are necessary in the area to protect the Teshio River ecosystem and its ecosystem services.     

Dietary patterns and blood levels of PCDDs, PCDFs, and dioxin-like PCBs in 1656 Japanese individuals

The association between dietary patterns and blood dioxin levels has not been fully investigated. The present study population consisted of 755 men and 901 women (aged 15-73 years) living in 90 different areas of 30 prefectures of Japan. Dietary habits were assessed by inquiring about the consumption frequency of 28 foods, food groups and beverages. In addition, the blood levels of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs), and dioxin-like polychlorinated biphenyl (DL-PCBs) congeners were determined by high-resolution gas chromatography/mass spectrometry. The median total toxicity equivalent (TEQ) in the blood, which was calculated on the basis of the toxicity equivalency factors of WHO (2005), was 16 pg TEQ g⁻¹ lipid. Principal component analysis identified five dietary patterns: Healthy diet (high intake of vegetables and fruits); Meat/High fat intake (high intake of meat, meat products, and eggs); Seafood and Alcohol (high intake of fish, shellfish, and alcoholic beverages); Miscellaneous; and Milk products and Alcohol intake (high intake of milk, Milk products, and alcoholic beverages). After adjusting for sex, age, body mass index, and smoking habits, the Seafood and Alcohol pattern scores were significantly related to higher blood levels of total TEQ and PCDDs/PCDFs/DL-PCBs, and the Milk products and Alcohol pattern scores were correlated with higher blood levels of DL-PCBs. More detailed analysis showed that the intake frequencies for alcoholic beverages and seafood were independently and positively associated with total TEQ and the TEQ of PCDFs and DL-PCBs. The association between alcoholic beverage intake and PCDDs was also significant. Analysis of dietary patterns may be useful for identifying the dietary characteristics of individuals with a high dioxin body burden.     

Light acclimation states of phytoplankton in the Southern Ocean, determined using photosynthetic pigment distribution

In high-latitude waters such as the Southern Ocean, the primary production of phytoplankton supports the ecosystem. To understand the photo-acclimation strategy of such phytoplankton within cold environments, the vertical distribution profile of photosynthetic pigments was analyzed in the Southern Ocean. Samples were taken along 110°E during the austral summer, and along 150°E and around the edge of the seasonal sea ice of the Antarctic Continent during the austral autumn. Pigment extraction methods were optimized for these samples. The standing crop of chlorophyll a was larger in the region along the edge of the seasonal sea ice than at sampling stations in open ocean areas. Chlorophyll concentration seemed to be dependent on the formation of thermo- and haloclines along the edge of the seasonal sea ice, but not in the open ocean where such clines are less pronounced. The marker pigments fucoxanthin and/or 19′-hexanoyloxyfucoxanthin were dominant at most sampling stations throughout the water column, while other marker pigments such as alloxanthin were quite low. This indicated that diatoms and/or haptophytes were the major phytoplankton in this area. Comparison of the relative ratio of fucoxanthin with that of 19′-hexanoyloxyfucoxanthin allowed some stations to be characterized as either diatom-dominant or haptophyte-dominant. The relative ratio of xanthophyll-cycle pigments (diadinoxanthin plus diatoxanthin) to chlorophyll a was high in surface waters and decreased gradually with depth. This suggests that near the ice edge during summer in the Southern Ocean, both diatoms and haptophytes acclimate to their light environments to protect their photosystems under high-light conditions.     

Evaluation of the sensitivity of marine microalgal strains to the heavy metals, Cu, As, Sb, Pb and Cd

The sensitivity of nine marine microalgal species (consisting of five divisions and seven genera) to the five heavy metals, Cu(II), As(V), Sb(III), Pb(II) and Cd(II) was studied by using a fluorometric growth-inhibition assay with 96-well microplates. The algal strains studied were Cylindrotheca sp. and the LPP group that respectively characterize aggregating and filamentous types, and Chlorococcum littorale, Chlorococcum sp., Isochrysis galbana, Tetraselmis tetrathele, Heterocapsa sp., Synechococcus sp. and Prasinococcus sp. for types that occur as single cells. A good linear relationship was observed between the chlorophyll a concentration and intensity of chlorophyll fluorescence (485-nm excitation filter and 645-nm emission filter) when the chlorophyll a concentration was within the range of 0.10-5.0 microg ml(-1). A starting cell concentration of 0.10 or 0.25 microg Chl a ml(-1) was therefore selected. In accordance with OECD 201 standard procedures, the IC(50) value (concentration of a metal producing 50% growth inhibition relative to the control) was determined 72 h after adding a heavy metal by using the biomass integral. The microplate toxicity test used in this study is considered to be applicable to diverse algae, not only enumerating species but also hardly enumerating ones.     

Priority areas for conservation of and research focused on terrestrial vertebrates

Effective conservation policies require comprehensive knowledge of biodiversity. However, knowledge shortfalls still remain, hindering possibilities to improve decision making and built such policies. During the last 2 decades, conservationists have made great efforts to allocate resources as efficiently as possible but have rarely considered the idea that if research investments are also strategically allocated, it would likely fill knowledge gaps while simultaneously improving conservation actions. Therefore, prioritizing areas where both conservation and research actions could be conducted becomes a critical endeavor that can further maximize return on investment. We used Zonation, a conservation planning tool and geographical distributions of amphibians, birds, mammals, and reptiles to suggest and compare priority areas for conservation and research of terrestrial vertebrates worldwide. We also evaluated the degree of human disturbance in both types of priority areas by describing the value of the human footprint index within such areas. The spatial concordance between priority conservation and research areas was low: 0.36% of the world's land area. In these areas, we found it would be possible to protect almost half of the currently threatened species and to gather information on nearly 42% of data-deficient (DD) species. We also found that 6199 protected areas worldwide are located in such places, although only 35% of them have strict conservation purposes. Areas of consensus between conservation and research areas represent an opportunity for simultaneously conserving and acquiring knowledge of threatened and DD species of vertebrates. Although the picture is not the most encouraging, joint conservation and research efforts are possible and should be fostered to save vertebrate species from our own ignorance and extinction.     

人口密度对森林火灾发生频率的影响

人类活动是引发森林火灾的主要原因之一，在中国、日本等国家，90％以上的森林火灾是由人为因素引起的。为了量化人类活动对森林火灾的影响，本文基于日本的三级网格系统，对日本全国范围内近年来的森林火灾数据、土地利用率数据和人口密度数据进行了综合分析，研究了人口密度对火灾发生频率的定量影响规律。结果表明：森林火灾发生频率与人口密度之间呈现出幂律关系，经过一步的分析，发现两者之间存在具有边界效应的简单关系，即渐近幂律分布。本文的研究结果对于森林火灾的防治，特别是对于火险的预测具有实用意义。     

小尺度森林火灾的渐近幂律分布

森林火灾系统是一个自组织临界性系统，它的表现之一就是火灾的尺度分布满足幂律规律。然而实际数据分析表明，在尺度最大和最小的两个区域，火灾分布与幂律规律存在较大的差异。对小尺度火灾的偏离现象，研究者通常猜测是由于小面积火灾记录数据遗漏较多造成的，目前尚没有一个理论上的依据，而小尺度火灾的分布规律对大尺度火灾的预测起看关键作用。为了解释这种偏离现象，该文将火灾看作一个生灭过程，并对火灾蔓延和熄灭的机理进行了分析，最终得到了森林火灾分布与火灾尺度的定量依赖关系及其机理。将该文的结果与日本近年来全国范围内的森林火灾统计数据进行了对比，表明该文得到的结果与真实数据得到较好符合，并且成功解释了小尺度森林火灾分布与幂律关系的偏离现象。该研究可望对深入认识火灾系统的自组织临界性和防治火灾具有一定的实际意义。     

Relationship between the growth and survival of larval Pacific bluefin tuna, Thunnus orientalis

We tested the hypothesis that a large body size and rapid growth rate affect the survival of larval Pacific bluefin tuna, Thunnus orientalis (PBT), and analyzed larval growth in relation to environmental conditions. Seven high density larval patches of PBT were tracked with reference buoys in the northwestern Pacific Ocean for 28–171 h in May–June from 2004 to 2008. The otolith radii and daily growth rates of the survivor larvae (collected on later tracking days of each tracking session) tended to be larger and more rapid, respectively, than those of original larvae (collected on earlier tracking days). A large body size was found to positively affect the survival of larval PBT, as did a rapid growth rate, even at an early larval stage (7 days after hatching). Generalized linear modeling showed that the otolith radius was influenced positively by the sea temperature, stratification parameter and food density, while the growth rate was influenced positively by the sea temperature and food density.     

Field identification of ‘types’ A and B of the ascidian Ciona intestinalis in a region of sympatry

The ascidian species Ciona intestinalis is a major model chordate in developmental and evolutionary biology, and an important fouling organism and invasive species. However, genomic investigation has recently revealed the existence of two cryptic species, genetically distinct yet without obvious morphological differences, currently referred to as types A and B. Here, we show that they are externally distinctive in a zone of sympatry in the western English Channel. Examining genotyped specimens, we found that types A and B of C. intestinalis can generally be distinguished by body colour, pigmentation at the distal end of the siphons and the presence or absence of tubercles on the sides of the siphons. Detecting specimens of hybrid descent still requires detailed molecular analysis, but these visual characters in combination will identify living specimens of types A and B with high probability. These differences are shown to be inherited.     

消防第一出动时间的频次分布规律研究

消防队接到火警后第一出动力量及时到达火场展开灭火救援,对有效控制火灾、减少人员伤亡和财产损失有着重要的意义。第一出动时间直接反映了城市灭火救援专业力量的出动响应水平。采用SPSS软件对1995-2003年日本全国城市火灾数据进行分析,发现第一出动时间的频次符合对数正态分布;与部分中国城市火灾统计数据对比后,表明后者符合同样的规律。中国数据对数正态分布的期望值为4.9分钟,其物理意义为消防力量第一出动时间的平均值,与我国消防条例对城镇消防站设置的基本原则相符。