Reconstruction of food conditions for Northeast Atlantic bivalve species based on Dynamic Energy Budgets

Required assimilated energy to support observed growth was reconstructed for four common bivalve species (Mya arenaria, Cerastoderma edule, Mytilus edulis and Macoma balthica) from various Northeast Atlantic coastal areas, along the species distributional range. The approach applied was based on the Dynamic Energy Budget (DEB) theory whereby observed growth patterns in the field, in combination with prevailing temperatures, were used to reconstruct the average food intake experienced in the field scaled to the maximum possible. For all species, results suggest food limitation over the range of locations. In general, reconstructed food intake indicated better conditions for C. edule compared to the other species, while M. edulis presented the lowest food conditions in all the areas. Despite the indications for a latitudinal trend in primary production, no clear pattern or relationship between reconstructed food conditions and latitude was observed suggesting that any trend may be overruled by local conditions.     

The vulnerabilities of agricultural land and food production to future water scarcity

Rapidly increasing populations coupled with increased food demand requires either an expansion of agricultural land or sufficient production gains from current resources. However, in a changing world, reduced water availability might undermine improvements in crop and grass productivity and may disproportionately affect different parts of the world. Using multi-model studies, the potential trends, risks and uncertainties to land use and land availability that may arise from reductions in water availability are examined here. In addition, the impacts of different policy interventions on pressures from emerging risks are examined.Results indicate that globally, approximately 11% and 10% of current crop- and grass-lands could be vulnerable to reduction in water availability and may lose some productive capacity, with Africa and the Middle East, China, Europe and Asia particularly at risk. While uncertainties remain, reduction in agricultural land area associated with dietary changes (reduction of food waste and decreased meat consumption) offers the greatest buffer against land loss and food insecurity.     

专家系统和神经网络相结合用于钻进过程安全监控

提出了把专家系统和神经网络混合起来使用的新方法, 这种方法可以克服专家系统和神经网络单独使用时的缺陷。以钻进过程的安全监控为例, 研究了这种方法在确定性和不确定性条件下的使用步骤及效果。     

13C/12C比值在海洋生态系统营养关系研究中的应用──海洋植物的同位素组成及其影响因素的初步探讨

于１９９３年２月－１９９５年５月,采用生物显微镜鉴定并计数和高温氧化的方法,对崂山湾海洋植物的种类组成及其有机碳同位素组成的季节性变化作了５个季度月的研究。结果表明,该区网采浮游植物全年以硅藻为主,甲藻在夏季也可成为优势种之一,浮游植物的碳同位素组成在夏季较重,冬季和春季较轻,并与海水温度有弱的正相关性。     

Seasonal Response of Planktonic Foraminifera to Surface Ocean Condition: Sediment Trap Results from the Central North Pacific Ocean

The fluxes of planktonic foraminifera (calcareous shell producing zooplankton) were examined in order to clarify temporal and regional variations in production in the upper ocean in relation to hydrographic conditions. Three time-series sediment traps were deployed in the central North Pacific along 175°E for about one year, beginning in June 1993. Trap sites were located in the subarctic, the transition, and the subtropical water masses, from north to south. The southernmost site was under the influence of the transition zone in January to May. Both temporal and regional fluxes of planktonic foraminifera showed large variations during the experiment. In the subarctic water mass, high total foraminiferal fluxes (TFFs) and high organic matter fluxes (OMFs) were observed during summer to fall, suggesting that food availability is the most important factor for the production of planktonic foraminifera. Furthermore, low TFFs during winter were ascribed to low food availability and low temperatures. The OMFs and TFFs correlated well and increased rapidly after the disruption of the seasonal thermocline during winter, peaking in late February to early March in the transition zone. In the subtropical water mass, both OMFs and TFFs remained low due to lower productivity under oligotrophic conditions. In general, TFFs show a positive correlation with OMFs during the trap experiment, suggesting that food availability is one of the factors controlling the production of planktonic foraminifera in the central North Pacific. Relatively low TFFs during summer to fall in the subtropical water mass may be caused by the thermal structure of the upper ocean. Low SST possibly reduces the production of foraminifera during winter in the subarctic region.     

基于集群技术的“天地图”运行支持环境设计

在分析基于互联网的地理信息在线服务特点和网站服务质量需求的基础上,对服务器高可用性、负载均衡技术与构建方式、调度算法进行了讨论,给出了天地图网站高可用性服务器集群和负载均衡服务器集群的设计模型,描述了相关的设备部署、调度算法和健康性检测等方面的设计内容;同时,讨论了文件和关系型数据库服务器集群的具体应用.     

Snowmelt velocity predicts vegetation green-wave velocity in mountainous ecological systems of North America

The timing of spring initiates an important period for resource availability for large trophic webs within ecosystems, including forage for grazing animals, flowers for pollinators, and the higher trophic levels that depend on these resources. Spring timing is highly variable across space, being influenced strongly by the departure of snow cover (i.e. snowmelt timing, in locations with a seasonal snowpack), climate, weather, elevation, and latitude. When spring timing occurs along a gradient (e.g. spring arriving later in higher elevations of mountainous terrain), the organisms that rely on spring resources often migrate to maintain an optimal position for spring resources – a phenomenon known as ‘surfing the green wave.’ While this behavior has been observed by tracking animals, there have been no studies to quantify the green wave as a movement across space and time. Furthermore, considering that snowmelt timing has moderate power to explain green-up timing for a given location, we ask the question: does snowmelt velocity predict green wave velocity? Here, we introduce the first continental maps of snowmelt and green wave velocity for North America from 2001 to 2016 as derived from the MODIS MCD12Q2 phenology dataset. We show that both snowmelt and green wave velocities are influenced strongly by topography, including slope and aspect. Furthermore, we quantify the relationships between snowmelt and green wave velocities according to three variables: direction, speed, and distance traveled. We conclude that mountainous ecoregions, such as the western North American cordillera, have the highest correspondence between snowmelt and green wave velocities, compared to flatter regions such as the Great Plains and tundra. This work will be of interest to wildlife ecologists, biologists, and land managers who seek to conserve migratory animals and the ecosystems that support them.     

Modelling the influence of environmental factors on the physiological status of the Pacific oyster Crassostrea gigas in an estuarine embayment; The Baie des Veys (France)

It is well known that temporal changes in bivalve body mass are strongly correlated with temporal variations in water temperature and food supply. In order to study the influence of the year-to-year variability of environmental factors on oyster growth, we coupled a biogeochemical sub-model, which simulates trophic resources of oysters (i.e. phytoplankton biomass via chlorophyll a), and an ecophysiological sub-model, which simulates growth and reproduction (i.e. gametogenesis and spawning), using mechanistic bases. The biogeochemical sub-model successfully simulated phytoplankton dynamics using river nutrient inputs and meteorological factors as forcing functions. Adequate simulation of oyster growth dynamics requires a relevant food quantifier compatible with outputs of the biogeochemical sub-model (i.e. chlorophyll a concentration). We decided to use the phytoplankton carbon concentration as quantifier for food, as it is a better estimator of the energy really available to oysters. The transformation of chlorophyll a concentration into carbon concentration using a variable chlorophyll a to carbon ratio enabled us to improve the simulation of oyster growth especially during the starvation period (i.e. autumn and winter). Once validated, the coupled model was a suitable tool to study the influence of the year-to-year variability of phytoplankton dynamics and water temperature on the gonado-somatic growth of the Pacific oyster. Four years with highly contrasted meteorological conditions (river inputs, water temperature and light) 2000, 2001, 2002 and 2003, were simulated. The years were split into two groups, wet years (2000 and 2001) and dry years (2002 and 2003). Significant variability of the response of oysters to environmental conditions was highlighted between the four scenarios. In the wet years, an increase in loadings of river nutrients and suspended particulate matter led to a shift in the initiation and the magnitude of the phytoplanktonic spring bloom, and consequently to a shift in oyster growth patterns. In contrast, in the dry years, an increase in water temperature—especially during summer—resulted in early spawning. Thus, the gonado-somatic growth pattern of oysters was shown to be sensitive to variations in river loadings and water temperature. In this context, the physiological status of oysters is discussed using a relevant indicator of energy needs.     

Trophic relationships on a fucoid shore in south-western Iceland as revealed by stable isotope analyses, laboratory experiments, field observations and gut analyses

Rocky shores in the North Atlantic are known for their zonation patterns of both algae and animals, which can be expected to greatly affect food availability to consumers at different height levels on the shore. We tested the hypothesis that consumers would feed on the most abundant suitable food source in their surroundings. In total 36 species/taxa of common primary producers and consumers were sampled for stable isotope analyses from a sheltered fucoid shore at Hvassahraun in south-western Iceland. A selection of these species was also collected seasonally and from different height levels. Feeding experiments, field observations and gut analyses were also conducted. Our results were in good overall agreement with pre-existing knowledge of trophic relationships in the rocky intertidal. Consumers often appeared to be assimilating carbon and nitrogen from the most common diet in their immediate surroundings. The predator Nucella lapillus was thus feeding on different prey at different height levels in accordance with different densities of prey species. When tested in the laboratory, individuals taken from low on the shore would ignore the gastropod Littorina obtusata, uncommon at that height level, even when starved, while individuals from mid-shore readily ate the gastropod. This indicated that some kind of learned behaviour was involved. There were, however, important exceptions, most noteworthy the relatively small contribution to herbivores, both slow moving (the gastropod L. obtusata) and fast moving (the isopod Idotea granulosa and the amphipod Gammarus obtusatus) of the dominant alga at this site, Ascophyllum nodosum. The recent colonizer Fucus serratus seemed to be favoured. Selective feeding was indicated both by isotope signatures as well as by results of feeding experiments. Seasonal migrations of both slow and fast moving species could partly explain patterns observed.     

平衡剖面技术在新疆焉耆盆地断裂和圈闭研究中的应用

简要地介绍了平衡剖面技术的基本原理及在新疆焉耆盆地断裂演化和圈闭研究中的应用。借助该项技术确定了盆地内断裂发育的时空关系及性质,指出盆地内中、新生代的断裂发育过程中有早缓晚骤、早正晚逆（ 反转） 的特征,认为盆地内的构造圈闭主要有两个形成时期,即侏罗纪末的燕山运动时期和第三纪末的喜山运动时期,并且前者形成的圈闭有效性要好于后者。