Nutritional Contribution of Biofloc within the Diet of Growout and Broodstock of Litopenaeus vannamei,Determined by Stable Isotopes and Fatty Acids

The relative contributions of feed sources were determined through the isotopic signal (δ¹³C and δ¹⁵N) and fatty acid profile of feed items, shrimp muscle, and eggs of Litopenaeus vannamei reared in a biofloc system. In the growout phase, the isotope analysis showed the biofloc particle size class ≥250 μm contributed 55–100%; size ≥50 < 250 μm contributed 0–22%; and artificial feed contributed 0–45%. Principal component analysis applied to fatty acid profiles showed that biofloc ≥250 μm and artificial feed were the most important items in shrimp growout. For the egg production, isotope analysis suggested that the most important feed sources according to their relative contributions were polychaetes (0–100%), followed by artemia biomass (0–86%) and semi‐moist feed (0–66%), with lower contributions from squid, mussel, and the muscle of L. vannamei broodstock that had been cultured in biofloc. In terms of fatty acids, the most important items were artemia, polychaetes, and semi‐moist feeds. This work clarified the importance of feed sources for shrimp during culture in biofloc systems and during reproduction. Analysis of stable isotopes and fatty acids can be successfully used to trace the assimilation of nutrients during the nutrition of shrimp.     

Validating a Time Series of Annual Grass Percent Cover in the Sagebrush Ecosystem

We mapped yearly (2000–2016) estimates of annual grass percent cover for much of the sagebrush ecosystem of the western United States using remotely sensed, climate, and geophysical data in regression-tree models. Annual grasses senesce and cure by early summer and then become beds of fine fuel that easily ignite and spread fire through rangeland systems. Our annual maps estimate the extent of these fuels and can serve as a tool to assist land managers and scientists in understanding the ecosystem’s response to weather variations, disturbances, and management. Validating the time series of annual maps is important for determining the usefulness of the data. To validate these maps, we compare Bureau of Land Management Assessment Inventory and Monitoring (AIM) data to mapped estimates and use a leave-one-out spatial assessment technique that is effective for validating maps that cover broad geographical extents. We hypothesize that the time series of annual maps exhibits high spatiotemporal variability because precipitation is highly variable in arid and semiarid environments where sagebrush is native, and invasive annual grasses respond to precipitation. The remotely sensed data that help drive our regression-tree model effectively measures annual grasses’ response to precipitation. The mean absolute error (MAE) rate varied depending on the validation data and technique used for comparison. The AIM plot data and our maps had substantial spatial incongruence, but despite this, the MAE rate for the assessment equaled 12.62%. The leave-one-out accuracy assessment had an MAE of 8.43%. We quantified bias, and bias was more substantial at higher percent cover. These annual maps can help management identify actions that may alleviate the current cycle of invasive grasses because it enables the assessment of the variability of annual grass ? percent cover distribution through space and time, as part of dynamic systems rather than static systems.     

Understanding stakeholders’ opinions and preferences for non-native pet trade management in Florida

There is growing recognition of the link between the non-native pet trade and the introduction and establishment of invasive species due to the release and escape of non-native pets. However, it is unclear whether participants in the pet trade recognize the magnitude of this invasion risk. Successful mitigation of the pet trade invasion risk requires stakeholder support for, and participation in, regulations. We conducted 29 interviews in Florida to investigate key stakeholders’ opinions about the pet trade invasion risk and the effectiveness of potential regulations to mitigate this risk. Respondents framed the effectiveness of regulations in terms of their feasibility. Respondents also identified lack of trust and the existence of an adversarial relationship among stakeholder groups as major barriers to managing the pet trade invasion risk. Compliance with regulations may be improved if policy makers and managers utilize participatory decision-making to engage stakeholders in management of this risk.     

Native and exotic seed dispersal by the stone marten (Martes foina): implications for the regeneration of a relict climactic forest in central Portugal

The stone marten (Martes foina) is a carnivorous mammal that often consumes fleshy fruits, thus potentially promoting seed dispersion. The present study was developed in Bussaco National Forest, central Portugal, and aimed to assess the potential role of the stone marten in dispersing native and exotic plants in different forest landscape types. Seeds from stone marten scats and fleshy fruits were collected monthly and were thereafter identified and sowed in a nursery, following a randomized experimental setup. Plant emergence was monitored fortnightly. Generalized linear models were used to test for differences in time and success of emergence between seeds from scats and fruits of 3 native species (Rubus ulmifolius, Arbutus unedo and Celtis australis) and 1 exotic plant species with invasive behavior (Prunus laurocerasus). Fruit consumption by the stone martens significantly increased and accelerated the germination of the native R. ulmifolius but had no effect on the other 2 native species or on the invasive species. This suggested that stone martens contribute to gene flow and forest regeneration by dispersing native plant seeds. However, although the germination was not enhanced in the invasive species, the preference of stone martens for these fruits may potentially contribute to the proliferation of P. laurocerasus. Our study represents a contribution to better understanding the fauna and flora interactions, enabling for a more conscious and effective decision‐making in forest management.     

Opportunities for investment into small ruminant breeding programmes in Brazil

The social contribution of goat and sheep industries is very important to many Brazilian families mainly in semi‐arid regions of the country. However, the productive chains of these two species in Brazil are unorganized and ultimately informal. On the other hand, there is potential for growth and development to which an upscaling of breeding programmes will be essential. Historically, many attempts to structure these programmes have been unsuccessful. Inadequate understanding of how to achieve genetic improvement often leading to distributing unsuitable exotic genetics among the producers is one of the reasons for the failure. Another important factor is related to the sources of funding and the priorities for the use of funds. According to the experience and the state of the art in Brazil, the priorities for funding must be in the characterization of the different systems and animal genetic resources, organization of information collection procedures and national databanks, training of technicians and producers and development of system to enable animal evaluation.     

母兔腹腔镜辅助微创卵巢子宫切除术

母兔卵巢子宫摘除术为异宠临床诊疗中常见的手术之一,本手术为使用腹腔镜辅助,配合电凝刀进行母兔卵巢子宫摘除微创手术。手术麻醉采用右美托咪定诱导麻醉,气管插管后给予异氟烷混合纯氧吸入麻醉进行维持麻醉。利用气腹仪充入CO2提供腹腔内可进行手术的操作空间,使用腹腔镜配合电凝刀在动物腹腔内电凝及切断双侧卵巢血管及韧带,并牵引卵巢子宫至体外结扎子宫颈。手术平均用时30 min,术后平均5 min恢复自主意识,手术创口为三个大约5 mm的切口,术后预后良好。     

肥料中氮源类型对结球甘蓝产量及生物学产量的效应

通过肥料中氮源类型即有机和化学氮的配比试验,研究了６种肥料处理对结球甘蓝生物学产量和商品产量的影响,比较了不同肥料处理下干物质积累规律,并开展了结球甘蓝的储存试验。结果表明：当氮源同时来源于化学肥料和有机肥料时,结球甘蓝的商品产量、生物学产量及干物质积累量均较高,经济系数及耐储性能也有明显改善。     

土壤侵蚀与非点源污染预测控制

土壤侵蚀与非点源污染百两大重要的环境问题。讨论了这两个问题的定量化预测与控制措施,并阐述了它们的相互关系。这有望进一步推进中国水土保持学科领域的研究内容。     

The dietary regime of detritivorous fish from the River Jacaré Pepira, Brazil

The diet of detritivorous fish was analysed at four distinct habitats in a tropical river during the wet and dry seasons. Two methodologies were used to determine the diet of the fish: (1) the direct analysis of the stomach contents; and (2) the use of stable carbon isotopes. Both methods indicated food partitioning among the fish. The stomach contents showed what the fish had ingested when captured and the ¹³C isotope indicated what it had assimilated over a long period of time. The ¹³C isotope suggested the existence of sectional differences in the feeding of the detritivorous fish along the river. Plants employing the C₄ photosynthesis pathways seem to have little influence on the diet of these fish. This method proved to be more appropriate for the detection of the main food sources of the captured fish.     

基于MaxEnt预测未来气候条件下钻叶紫菀在中国的潜在适生区

钻叶紫菀Symphyotrichum subulatum是一级恶性入侵植物,其传播速度快,繁殖能力强,严重影响本地草本植物多样性。本研究利用生态位模型MaxEnt和地理信息系统软件ArcGIS,根据收集的钻叶紫菀分布点和环境变量,预测目前气候条件和未来气候变化情景下钻叶紫菀在中国的潜在适生区,并推测环境变量对钻叶紫菀适生区的影响。结果表明,钻叶紫菀的潜在适生区主要位于亚热带湿润型气候大区的低海拔区域,其中高适生区的分布范围为21°～40°N,主要位于广东、福建、江西、江苏、湖南、湖北、四川东南地区和安徽东北地区等。影响钻叶紫菀潜在适生区分布的关键环境变量为最干旱月份降水量、最湿润月份降水量、10月平均温度、3月最高温度、8月最低温度和6月太阳辐射量。在未来气候变化情景SSP126、SSP245、SSP370和SSP585条件下,钻叶紫菀的低、中和高适生区面积占比将分别增加3.54%、4.80%、5.73%和3.29%。整体而言,未来气候变化有利于钻叶紫菀适生区的扩张。到21世纪中叶,钻叶紫菀的高适生区呈现向高海拔地区和中高纬度(具体为由南向北和西北方向)扩张的趋势。钻叶紫菀适生区分布范...