Flood disturbance effects on benthic diatom assemblage structure in a semiarid river network

Disturbances such as floods and droughts play a central role in determining the structure of riverine benthic biological assemblages. Extreme disturbances from flash floods are often restricted to part of the river network and the magnitude of the flood disturbance may lessen as floods propagate downstream. The present study aimed to characterize the impact of summer monsoonal floods on the resistance and resilience of the benthic diatom assemblage structure in nine river reaches of increasing drainage size within the Gila River in the southwestern United States. Monsoonal floods had a profound effect on the diatom assemblage in the Gila River, but the effects were not related to drainage size except for the response of algal biomass. During monsoons, algal biomass was effectively reduced in smaller and larger systems, but minor changes were observed in medium systems. Resistance and resilience of the diatom assemblage to floods were related to specific species traits, mainly to growth forms. Tightly adhered, adnate and prostrate species (Achnanthidium spp., Cocconeis spp.) exhibited high resistance to repeated scour disturbance. Loosely attached diatoms, such as Nitzschia spp. and Navicula spp., were most susceptible to drift and scour. However, recovery of the diatom assemblage was very quick indicating a high resilience, especially in terms of biomass and diversity. Regional hydroclimatic models predict greater precipitation variability, which will select for diatoms resilient to bed‐mobilizing disturbances. The results of this study may help anticipate future benthic diatom assemblage patterns in the southwestern United States resulting from a more variable climate.     

美国长期生态研究计划三十年:特点、效果与启示——以弗吉尼亚海岸带保护区为例

为观测和理解长时间与大范围尺度的生态变化,美国自然科学基金会于1980年启动了长期生态研究计划(LTER),30年来在站点建设、科学研究和社会服务等方面取得了巨大成就.本文将美国LTER的成功经验归纳为5个特点,即:研究网络、研究主题和数据兼容的系统性,项目时间与研究尺度的长期性,资金来源与研究内容的灵活性,国际、人文、方法与机构合作方面的拓展性,数据和教育的共享性;并以弗吉尼亚海岸保护区(VCR)为案例展示其实施效果.在此基础上提出对我国长期生态研究的建议,包括加强组织建设,建立完整网络并增强站际合作,重视数据的质量、管理和分享,增强多学科研究,扩大公共影响等.     

美国生物医药产业竞争力分析与启示

进入生物经济时代以来,以生物医药产业为代表的生物技术产业正在引领人类新一波技术产业革命。我国针对生物医药产业作出的战略部署已经取得了明显成效,但与美国等生物医药强国相比仍有较大的竞争差距。采用波特钻石模型构建了生物医药产业国际竞争力理论分析框架,以美国为例分析其生物医药产业在要素状况、企业结构和竞争、需求条件、相关及支持性产业、政府和发展机会六个方面的竞争优势,并基于此提出了我国发展生物医药产业的政策建议,从而为我国生物医药产业发展提供政策参考。     

Human-wildlife competition and the passenger pigeon: Population growth from system destabilization

The relatively small number of passenger pigeon bones found in prehistoric sites in the eastern United States is at variance with the tremendous population recorded between the seventeenth and nineteenth centuries: It is argued that, prior to European contact, the population of passenger pigeons was small due to human-wildlife competition over tree nuts. This competition restricted the pigeon's access to food and limited its prehistoric population. When this competitive network was disrupted by European colonization, the availability of food for the pigeon increased. The enormous population that then emerged represents an outbreak population precipitated by enrichment in food and space. The structure of the prehistoric food web in the forests of the eastern United States is diagrammed, and the process leading to the growth of the passenger pigeon population described.     

Preliminary Observations on the Nature,Taxonomic Composition,Distribution, Behaviour and Nutrient Requirements of the “Unusual” Algal “Jellies” of Oguta Lake in Southeastern Nigeria

Preliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue-green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control measures outlined.     

Coastal Exploitation, Land Loss, and Hurricanes: A Recipe for Disaster

Southern Louisiana occupies a dynamic landscape, marked by coastal wetlands interrupted by both natural and human-made levees, and vulnerable to both the Mississippi and Atchafalaya rivers and major storms coming off the Gulf of Mexico. It is also a region into which, for centuries, exiled and threatened populations have moved and found refuge. Systematic and dramatic changes along the entire reach of the Mississippi River coupled with activities within the region's wetlands such as levee construction, canal dredging, and petroleum extraction have contributed to both pollution and extensive coastal land loss. In this article, I discuss the recent hurricanes in light of the relationship between Louisiana and the rest of the United States and the environmental and community degradation that has occurred along the coast. I focus on petroleum development, the most recent and extensive natural resource to shape southern Louisiana's wealth and economy.     

Managing Global Atmospheric Change: A U.S. Policy Perspective

There are several air pollution issues that concern the international community at the regional and global level, including acid deposition, heavy metals, persistent organic pollutants, stratospheric ozone depletion, and climate change. Governments at the regional and global levels have entered into various agreements in an effort to deal with these problems. This paper deals with two major global atmospheric change issues: stratospheric ozone depletion and climate change. The focus is on the policy responses of the United States to these global issues. The United States has signed and ratified international agreements to deal with both problems. The Vienna Convention and the Montreal Protocol on Substances that Deplete the Ozone Layer have led to an effort in both developed and developing countries to phase out ozone depleting substances. The United Nations Framework Convention on Climate Change (UNFCCC) has been signed and ratified by over 180 countries. The UNFCC contained no binding targets and timetables for emissions reductions. The Kyoto Protocol (1997) to the UNFCCC did contain targets and timetables for reductions of greenhouse gases on the part of developed countries. The United States has signed but not ratified the Kyoto Protocol. The United States has experienced some movement to reduce greenhouse gas emissions on the part of various levels of government as well as the private sector. The policy process is constantly informed by scientific research. In the case of stratospheric ozone depletion and climate change, much of this work is carried out under the auspices of international scientific panels. From a policy perspective, there is a great deal of interest in the use of indicators for assessing the scope and magnitude of these problems, both for fashioning policy responses as well as assessing the impact of adopted programs to reduce ozone depleting substances, and potentially, greenhouse gases. This paper will discuss some of the indicators used for stratospheric ozone depletion and climate change.     

Feeding of the Snailfish Careproctus roseofuscus in Pacific Waters of the Northern Kuril Islands and Southeastern Kamchatka

The paper describes the feeding of two phenotypically different forms of the snailfish Careproctus roseofuscus (Scorpaeniformes, Liparidae) from the Pacific waters of the northern Kuril Islands and southeastern Kamchatka. The diet in the first form is comprised of actiniae. The second form mostly feeds on fish eggs and the amphipod Metopa majuscula Gurjanova. The second form is supposed to be confined to the biocenosis of Ophiopholis aculeata + Spongia.     

Patterns of co-occurrence among arboreal marsupials in the forests of central Victoria,southeastern Australia

Abstract Patterns of co-occurrence were examined among the suite of species of arboreal marsupials that inhabit the montane ash forests of the Central Highlands of Victoria, southeastern Australia. The data used in our analyses were counts of different species of arboreal marsupials derived from stagwatching surveys of 152 sites throughout the Central Highlands region. Our work investigated both the number of species that tend to occur together, as well as identity of the taxa in such associations. A total of eight different species of arboreal marsupials were recorded from field surveys of montane ash forests: Leadbeater's Possum (Gymnobelideus leadbeateri), Sugar Glider (Petaurus breviceps), Yellow-bellied Glider (Petaurus australis), Greater Glider (Petauroides volans), Mountain Brushtail Possum (Trichosurus caninus), Feathertail Glider (Acrobates pygmaeus), Common Ringtail Possum (Pseudocheirusperegrinus), and Eastern Pygmy Possum (Cercartetus nanus). Large assemblages of taxa were rare and no sites supported the full array of species of arboreal marsupials– the maximum number of species recorded on a given 3 ha site was five. The results of our analyses indicated that if any one species of arboreal marsupials was present at a site, then on average 1. 5 other taxa will co-inhabit that site. The exception was the Common Ringtail Possum. When this species was detected, few other arboreal marsupial taxa tended to be recorded with it. Principal Co-ordinates Analysis showed that although combinations of animals comprised of either Mountain Brushtail Possum, Leadbeater's Possum, or Greater Glider were often recorded, there were no strong patterns in the identities of co-occurring taxa. This finding, together with the result that most taxa in these forests typically co-occurred with one or two other species, indicates that none of the arboreal marsupials inhabiting the montane ash forests of the Central Highlands of Victoria would be a good surrogate for (or ‘indicator’ of), the presence of the suite of other species in the assemblage.     

Whole exome sequencing,in silico and functional studies confirm the association of the GJB2 mutation p.Cys169Tyr with deafness and suggest a role for the TMEM59 gene in the hearing process

The development of next generation sequencing techniques has facilitated the detection of mutations at an unprecedented rate. These efficient tools have been particularly beneficial for extremely heterogeneous disorders such as autosomal recessive non-syndromic hearing loss, the most common form of genetic deafness. GJB2 mutations are the most common cause of hereditary hearing loss. Amongst them the NM_004004.5: c.506G > A (p.Cys169Tyr) mutation has been associated with varying severity of hearing loss with unclear segregation patterns. In this study, we report a large consanguineous Emirati family with severe to profound hearing loss fully segregating the GJB2 missense mutation p.Cys169Tyr. Whole exome sequencing (WES), in silico, splicing and expression analyses ruled out the implication of any other variants and confirmed the implication of the p.Cys169Tyr mutation in this deafness family. We also show preliminary murine expression analysis that suggests a link between the TMEM59 gene and the hearing process. The present study improves our understanding of the molecular pathogenesis of hearing loss. It also emphasizes the significance of combining next generation sequencing approaches and segregation analyses especially in the diagnosis of disorders characterized by complex genetic heterogeneity.