东南太平洋智利竹筴鱼栖息地指数的比较研究

根据2000~2007年度东南太平洋智利竹筴鱼的商业捕捞数据,结合海洋环境数据(SST,SSA,SSHG以及等温层深度),运用4种关联建模方法计算其栖息地指数,并使用Surffer 8.0软件绘制出HSI的空间分布图。通过2008年度的捕捞数据进行验证,结果表明4种模型的结果存在明显差异:采用算术平均法和几何平均法时,主要产量分布在0.6HSI0.9的区域;采用最大值法时,主要产量集中在0.8HSI1.0的区域;采用最小值法时,主要产量分布在0.3HSI0.6的区域。通过4种模型的验证结果比较,本文认为算术平均法和几何平均法能较好地反映东南太平洋智利竹筴鱼的中心渔场位置以及分布特征。     

淀山湖湖水氮与叶绿素的时间格局转变研究

采用STARS（sequential t-test analysis of regime shifts）,以淀山湖湖水中TN、NH3-N、Chl-a和SD为指标,研究了淀山湖湖水氮与叶绿素在1991-2006年间的格局转变规律,分析了转变前后氮与叶绿素的格局特点。结果得出：1991-2006年间,淀山湖湖水中NH3-N和TN含量均存在两种格局,一次转变,发生转变的时间均在2000年;格局转变前NH3-N平均含量为0.649 mg•L-1,转变后为2.014 mg•L-1,是转变前的3.1倍;湖水TN的平均含量格局转变前为2.550 mg•L-1,转变后3.726 mg•L-1,是转变前的1.5倍。淀山湖湖水中Chl-a含量和SD也均存在两种格局,转变均发生在2001年。格局转变前湖水中Chl-a平均含量9.341ug•L-1,转变后19.713ug•L-1,是转变前的2.1倍;湖水SD在转变前平均62 cm,转变后降低为43 cm。2000年的格局转变指数（RSI）2.185,其中NH3-N的RSI 1.038,TN的1.147;2001年的RSI为1.341,其中Chl-a的0.318,SD的为1.023。     

Association of red‐mark syndrome with a Rickettsia‐like organism and its connection with strawberry disease in the USA

Red‐mark syndrome (RMS), a disease seen mostly in rainbow trout, Oncorhynchus mykiss, is of unknown aetiology. The research presented here indicates the presence of an intracellular bacterium in RMS‐affected fish. A positive reaction was observed using immunohistochemistry (IHC) with skin lesions, liver, kidney and spleen of affected fish sampled from several locations within the United Kingdom using two different polyclonal antisera raised against Piscirickettsia salmonis. The same reaction was also seen with a number of different anti‐P. salmonis monoclonal antibodies (MAbs). A disease with similar clinical signs to RMS, referred to as strawberry disease (SD), has been reported in the USA. A Rickettsia‐like organism (RLO) has recently been associated with SD based on analysis of 16S rDNA sequences. Using the same panel of anti‐P. salmonis antibodies used to screen the RMS samples, similar staining was obtained in tissue of SD‐affected fish by IHC. A polymerase chain reaction (PCR) using RLO‐specific primers was also performed on RMS‐affected fish from the United Kingdom, and the samples were positive for the RLO 16S rRNA sequence. These findings suggest that the same aetiological agent may be responsible for RMS in the United Kingdom and SD in the USA.     

基于NAPA软件的渔业船舶完整稳性分析

为验证NAPA软件在渔业船舶应用上的可行性和采用船舶静力学原理计算完整稳性的精确性,根据南海海域49.5 m金枪鱼延绳钓船的特定作业工况,分别采用NAPA软件和表格进行计算。计算结果表明,两种计算方法的偏差在2%左右,能够满足工程应用的精度要求。对气象衡准计算,分别采用了渔业船舶规则和国际海事组织(IMO)规则,由于算法不同,其偏差较大。通过比较发现,渔业船舶规则对气象衡准的要求高于IMO规则的要求。在没有条件使用大型船舶计算软件,且船舶处于平浮状态时,采用船舶静力学原理的计算结果是精确的。采用了船舶静力学原理并建立了NAPA计算模型,通过实例计算表明,NAPA软件具有在渔业船舶应用上的可行性和采用船舶静力学原理计算完整稳性的精确性,该结论可为船舶设计人员选取不同计算方法时提供参考依据。     

Potential for reintroduction of lake sturgeon in five northern Lake Michigan tributaries: a habitat suitability perspective

• 1. Conservation and rehabilitation efforts for lake sturgeon Acipenser fulvescens throughout the Great Lakes include the re‐establishment of self‐sustaining stocks in systems where they have been extirpated.
• 2. Information on the suitability of potential lake sturgeon habitat in tributaries is important for determining their capacity to support lake sturgeon stocking and to develop system‐specific rehabilitation strategies.
• 3. Geo‐referenced habitat information characterizing substrate composition, water depth, and stream gradient were applied to a life‐stage specific lake sturgeon habitat suitability index in a geographic information system to produce spatially explicit models of life‐stage specific habitat characteristics in five northern Lake Michigan tributaries from which lake sturgeon have been extirpated.
• 4. Habitat models indicated that high quality lake sturgeon spawning and staging habitat comprised 0 to 23% and 0 to 9% of the available habitat, respectively, whereas high quality juvenile lake sturgeon habitat was relatively ubiquitous throughout each river and comprised 39 to 99%.
• 5. Comparison of these data to lake sturgeon habitat availability in Lake Michigan tributaries currently supporting populations indicated that spawning and staging habitats may limit the ability of these systems to support spawning. Efforts to re‐establish lake sturgeon populations in these systems should consider the creation of spawning and staging habitat to increase reproductive and recruitment potential prior to the initiation of stocking efforts.

Copyright © 2007 John Wiley & Sons, Ltd.     

A stochastic approach for analysis of the influence of white spot disease, zootechnical parameters, water quality, and management factors on the variability of production of shrimp Litopenaeus vannamei cultivated under intensive commercial conditions

We investigated the variability of shrimp Litopenaeus vannamei production by incorporating stochastic elements into deterministic stock models and determined the contribution that white spot disease, zootechnical parameters, water quality, and alternative management strategies have on variability. The model was calibrated for intensive shrimp cultivation in the State of Nayarit, Mexico. Mean annual production increased as a consequence of improved management from 8000 kg ha⁻¹ to 22,000 kg ha⁻¹ when cultivation was not affected by the disease and from 3200 kg ha⁻¹ to 10,400 kg ha⁻¹ when the disease affected production. When simultaneously considering both cases, mean annual production increased from 6300 kg ha⁻¹ to 16,800 kg ha⁻¹. White spot disease was a major factor determining variability of production. Shrimp production was particularly sensitive to levels of dissolved oxygen when management was inadequate, while final weight and mortality rate of shrimp were more sensitive when management improved. Water temperature and salinity had intermediate importance, and mortality caused by the disease and the time when mortality occurred had intermediate or low relevance. Improving management increased shrimp production and diminished variability. The duration of cultivation and stocking density were the most important management variables controlling variability of production when cultivation was affected by the white spot disease. When the disease was not present, pond size and duration of cultivation were the main factors affecting production. Starting time of aeration had relatively lower importance in determining variability, while the stochastic values of dissolved oxygen, in contrast, became most important. These results call for studies on improving aeration management to reduce variability of dissolved oxygen in ponds.     

农业可持续发展指标体系构建

农业是国民经济的基础,我国作为农业大国有必要对农业可持续发展评价和指标体系构建进行探讨。针对当前农业发展所处阶段,对我国农业可持续发展及其影响因素作出客观的解释和理论概括,以农业可持续发展理论分析为基础,论述了可持续发展农业指标体系的基本要素及其构建的基本原则、方法、设计框架和指标选择标准,以构建符合我国国情的农业可持续发展评估指标体系。     

南昌梅岭“951224”森林火灾发生与火险天气分析及预防措施

分析了江西南昌梅岭地区发生森林火灾的火险天气条件，并提出了宣传教育、建立各种有效防火制度、严格控制火源、开展绿色防火工程、黑色防火工程、化控防火工程、加强林火预测预报、建立防火池八大预防措施。     

Exploratory trials on reinforcement of veld with legumes in the south‐eastern transvaal highveld

Abstract

The feasibility and potential of reinforcing veld with legumes in the south‐eastern Transvaal highveld was assessed in a number of trials during the period 1974–84. Experience was gained with regard to methods of establishment, adaptation of legumes to the local environment, responses to fertilization, especially with lime and superphosphate, and the reaction of legumes to fire and grazing. In all, 17 legumes were involved, including the genera Coronilla, Desmodium, Glycine, Lespedeza, Lotus, Macroptilium, Medicago, Neoto‐nonia, Trifolium and Vigna. Only Coronilla varia (crownvetch) showed a satisfactory degree of persistence. However, crownvetch is slow to establish, is intolerant of waterlogging and has a relatively high requirement for lime and phosphate. Considering these features, and the probability of undesirable changes in grass species composition in reinforced veld, it is recommended that intensification be achieved through development of improved pastures for use in conjunction with veld, rather than by means of veld reinforcement.