Nonrandom, Size- and Timing-Biased Breeding in a Hatchery Population of Steelhead Trout

Abstract:  Hatcheries have been built and operated to buffer salmon and trout populations from overfishing and to compensate for habitat lost or degraded by human activities. These facilities are now so prevalent that in some cases hatchery-produced salmon outnumber salmon produced in the wild. By default, this makes them an important component in the current ecology and evolution of salmonids. Hatcheries differ from natural environments in many ways, and among the most fundamental is the necessity that humans select fish for breeding instead of allowing natural processes of mate choice and competition. We examined the mating system for steelhead trout ( Oncorhynchus mykiss ) at Forks Creek Hatchery in southwest Washington and investigated factors affecting selection of individual steelhead for spawning by the hatchery staff. Despite efforts by the staff to not spawn selectively, data on steelhead spawned over 7 years revealed selection for large adult body size and early reproductive timing and a tendency for size-assortative mating (i.e., large with large). Selection on size was related to selection on reproductive timing because early returning fish tended to be larger than those returning later. To improve the fitness of both hatchery fish destined to spawn in the wild and hatchery fish designated to be spawned in the hatchery, a better understanding of factors associated with the range of reproductive success and mate-choice mechanisms in the wild is vital. This knowledge may then be applied to artificial propagation programs designed for conservation or enhancement.     

Habitat Suitability Models and the Shortfall in Conservation Planning for African Vertebrates

Abstract:  Ongoing loss of biodiversity requires identifying large-scale conservation priorities, but the detailed information on the distribution of species required for this purpose is often missing. We present a systematic reserve selection for 1223 African mammals and amphibians in which habitat suitability models are used as estimates of the area occupied by species. In the framework of the World Conservation Union (IUCN) Global Amphibian Assessment and IUCN Global Mammal Assessment, we collected the geographic range (extent of occurrence) and habitat preferences for each species. We used the latter to build species-specific habitat suitability models inside geographic ranges, and for 181 species we verified the models by comparing suitability levels to presence-absence data collected in the field. We then used the suitable areas as estimators of the area of occupancy and compared the results of systematic reserve selection based on geographic ranges to those based on estimated areas of occupancy. Our results showed that the reserve system would need a 30-100% expansion to achieve minimal conservation targets, concentrated in the tropics, where species richness reaches a maximum. Comparative analyses revealed that using geographic ranges, which overestimate the area occupied by species, underestimates the total amount of area that needs to be conserved. The area selected for conservation doubled when we used the estimated area of occupancy in place of the geographic ranges. This happened because the suitable areas potentially occupied by each species overlapped less than their geographic ranges. As a result, any given protected area contained fewer species than predicted by the analysis of ranges. Because species are more specialized than our estimates of distribution based on extent of occurrence suggest, we propose that this is a general effect in systematic conservation planning.     

2株漂白废水高效降解菌的选育

用含氯漂白废水驯化城市污水处理厂的好氧污泥 ,从中分离出两株高效去除有机氯的菌 ,并对其适应条件进行了研究。结果表明 ,当pH为 7.0、废水浓度为 5 0 %、加入 0 .4g/L葡萄糖、2mL菌液时 ,处理效果较好 ,有机氯的去除率最高可达 74 .8%。     

形率法测算单株立木材积公式选用

单株立木求积,是林业科研和生产的重要内容.本文通过对临武县杉木人工林分590株标准木进行测算研究,发现不同的立木求积式其求积精度有明显差异,由此优选出精度高简便实用的测算公式.     

Female rock shrimp<Emphasis Type="Italic"> Rhynchocinetes typus</Emphasis> mate in rapid succession up a male dominance hierarchy

The dynamics of male-male competition for mates and patterns of female choice depend critically on the social environment. We released newly molted sexually receptive females of the rock shrimp Rhynchocinetes typus in the field and recorded their interactions with males. In the dense aggregations in which these shrimp live, most females were encountered and seized by males within 2 min. Usually, females were first seized by subordinate males, and subsequently taken over by the dominant males. Many females (17 out of 23) had multiple mates during the 10-min observation period, and most of them received spermatophores from multiple males. Males used different mating tactics in accordance with their dominance status: subordinate males often used the sneaking tactic, seizing the female and immediately transferring spermatophores. In contrast, all dominant males used the primary mating tactic; they seized and stimulated the female before transferring spermatophores. Results from previous studies had indicated that females may reduce the fertilization chances of subordinate males by delaying spawning and removing spermatophores. We suggest that this capability in combination with the observed rapid mate succession may enable females to exploit male contest behaviors.Communicated by P. Backwell     

材料结构参数对薄板冲压成形仿真结果的影响

采用不同材料屈服模型及参数对典型冲压过程进行了仿真 ,对仿真结果进行了分析。分析表明材料模型及参数对仿真结果影响至关重要 ,板料的厚度分布及成形极限图对结构参数n和r值很敏感。这对更好的了解不同材料在冲压时的力学行为和进行冲压仿真时怎样合理选择材料模型及参数提供了帮助     

在我区西部大开发的平台上认识和发展循环经济

文章从系统论的科学原理出发，分析和探讨内蒙古工业经济发展模式，即线性经济模式和循环经济模式的不同点。同时指出，走循环经济的道路更符合系统科学的原理，是内蒙古地区参与西部大开发建设的需要，也是实现可持续发展的一个非常重要的途径。     

用固定化生物材料去除水体中的重金属离子

介绍了固定生物法去除水体中的重金属离子的特点 ,生物材料的类型 ,生物材料的选择 ,固定化方法及进行水处理的操作方式。     

A field experimental study of lignin sand stabilizing material (LSSM) extracted from spent-liquor of straw pulping paper mills

A new technique was introduced for sand stabilization and re-vegetation by use of lignin sand stabilizing material(LSSM). LSSM is a reconstructed organic compound with lignin as the most dominant component from the extracts of black-liquor issued by straw pulp paper mills. Unlike the polyvinyl acetate or foamed asphalt commonly used for dune stabilization, the new material is plant-friendly and can be used with virescence actions simultaneously. The field experimental study was conducted since 2001 in China‘s Northwest Ningxia Hui Autonomous Region and has been proved that LSSM is effective in stabilizing the fugitive dunes, making the arenaceous plants survive and the bare dune vegetative. The advisable solution concentration is 2% and the optimal field spraying quantity is 2.5L/m^2 The soil nutrients of the stabilized and greened dune, such as organic matter, available phosphorous and total nitrogen are all increased compared with the control treatment, which is certainly helpful to the growth of arenaceous plants. The technique is worthwhile to be popularized because it is provided not only a new method for desertification control but also an outlet for cleaning contaminants issued from the straw paper mills.     

硝化菌体在胶体材料的微型球状载体内的固定化

硝化处理效率低是制约污水脱氢工艺发展的重要因素，通过硝化菌体在PVA-SbQ与alginate混合胶体材料制作的微型球状载体中的固定，减少了菌体由于污水停留时间过造成的冲洗流失，又较好地处理了养分与氧的输运抑制问题，从而显著地提高了硝化处理效率，对改进污水脱氮工艺提供了有效途径。