Floodplains of a regulated southern alpine river (Brenno,Switzerland): ecological assessment and conservation options

• 1. The fifth‐order southern alpine Brenno River and its floodplains are severely impaired by embankments, water abstractions and the construction of dams for hydropower generation. The river's annual mean discharge is reduced to 27% of the natural flow and the number of small (50–100 m³ s^?1) and medium‐sized (101–150 m³ s^?1) floods is reduced significantly.
• 2. Lateral hydrological connectivity has decreased strongly as a result of the flow regulation, whereas the significance of vertical connectivity has increased. The remnants of the middle and lower floodplains still contain springbrooks, ponds, and intermittently connected channels, which are all sustained by emerging groundwater.
• 3. Aquatic floodplain habitats can be classified partially by faunal composition. The lotic/lentic gradient appears to be a dominant compound factor structuring invertebrate assemblages when considering all aquatic habitats. The exfiltration of groundwater in conjunction with a reduced lateral connectivity enables the occurrence of many stenotopic species.
• 4. A comparison of present floodplains with those shown on historical maps shows that the fluvial landscape has changed markedly. The proportions of functional floodplain units characterized by autogenic succession and trends to late successional stages (i.e. senescence) have increased.
• 5. Floodplains of the Brenno river are still considered to represent important ecological areas and they are protected by law. Whilst the legislative protection of floodplains is the basis for conservation, this does not include the restoration of driving hydrological processes. An annual release of small‐ and medium‐sized floods could generate a diversity of disturbances, thereby promoting rejuvenation and counteracting senescence.
• 6. Alternative conservation options that circumvent ongoing contracts of water use, though generally promising, are limited because of the operation of hydropower schemes. At present the exfiltrations of groundwater mitigate the impacts of flow regulation on the ecological integrity of the floodplains.

Copyright © 2002 John Wiley & Sons, Ltd.     

部分水产动物性别决定基因的研究进展

继在哺乳动物中发现了性别决定基因SRY后,相关学者还发现了诸如性别连锁基因、芳香化酶基因、锌指结构基因、H—Y抗原、Sox、DMRTl、DMy等许多与性别控制和性腺发育相关的基因,为进一步阐明鱼类性别决定机制提供了基础和手段,但仍存在一些问题有待探索。本文概述了近年来部分水产动物性别决定基因方面的研究动态和进展,并对其应用前景做了简述,以期为系统研究鱼类性别决定机制提供参考。     

酶联免疫法快速检测水产品中硝基呋喃类代谢物、氯霉素及氟苯尼考

应用特异性强的间接酶联免疫法,同时检测4种硝基呋喃类代谢物、氯霉素(CAP)和氟苯尼考(FF),建立快速分析水产品中6种药物残留量的方法.样品用盐酸进行消化,再由乙酸乙酯提取,使用酶联免疫试剂盒进行检测.实验结果显示,6种分析物均在其线性范围内,线性系数均大于0.995.在加标浓度为0.1、0.5和1.5μg/kg的加...     

Susceptibilities of some aquatic ferns to paddy herbicide bensulfuron methyl

Paddy herbicides have the potential to cause adverse effects on non-target plants. Susceptibilities of some aquatic ferns ( Azolla japonica Franch. et Savat., Isoetes japonica A. Braun, Marsilea quadrifolia L. and Salvinia natans All.) and duckweeds ( Lemna minor L. and Spirodela polyrhiza Schleid.) to paddy herbicide bensulfuron methyl (BSM) were evaluated with a 20 day exposure experiment using 200 cm² pots. The BSM concentrations in the surface water of monitoring pots with no plants dissipated exponentially with half lives of 3.5 and 3.9 days at application rates of 15 and 150 g ha⁻¹, respectively. The BSM concentrations in the surface water 1 day after application in the culture pots were comparable among plant species, and were lower than those in the monitoring pots. Bensulfuron methyl reduced the plant growth in all species. I . japonica showed the lowest intrinsic relative growth rate (RGR) and the lowest susceptibility with an effective dose resulting in 50% growth inhibition (ED₅₀) of 21 g ha⁻¹. Except for I . japonica , the RGR of the duckweeds was similar to the ferns, and ED₅₀ for the duckweeds was higher than the ferns. ED₅₀ for Sa . natans , A . japonica and M . quadrifolia were 1.1, 1.8 and 1.2 g ha⁻¹, respectively, which were smaller than 1/20 of the recommended field dose (51–75 g ha⁻¹) and ranged from 1/2 to 1/6 of ED₅₀ for L . minor and Sp . polyrhiza (6.5 and 3.2 g ha⁻¹, respectively). These results suggest that BSM application in paddy fields and its runoff in some localities is expected to have adverse effects on the growth of Sa . natans , A . japonica and M . quadrifolia .     

淮河荆涂峡鲤、长吻鮠国家级水产种质资源保护区 冬季渔业群落多样性研究

使用多种捕捞网具于2014年12月在淮河荆涂峡鲤、长吻鮠国家级水产种质资源保护区的核心区和实验区进行现场调查,利用调查数据对保护区渔获物组成及群落多样性进行研究。现场调查共采集到各类渔业生物33种,包括鱼类28种、甲壳类5种,分别隶属于6目13科31属。保护区渔获物组成以鲤形目物种占优,其物种数、渔获尾数和渔获重量占总渔获物的比例分别为60.61%、50.63%和89.86%。群落结构以淡水定居性物种及杂食性物种占优,优势种为鲤和鲫。保护区渔获物以小型物种占优,体重均值为44.70 g。基于渔获尾数的多样性特征值为:丰富度指数(R)4.6700,信息指数(H')2.9300,优势度指数(D)0.0680,均匀度指数(E)0.5675。克氏原螯虾在保护区内广泛分布,对其入侵性应加以重视。     

4种水生植物除磷效果及系统磷迁移规律研究

[目的]研究不同生态类型水生植物对水体总磷的去除效果及系统磷迁移规律.[方法]选取4种不同生态类型水生植物,分别为漂浮植物凤眼莲、水浮莲和挺水植物香蒲以及沉水植物轮叶黑藻,结合滇池富营养化湖水及底泥,构建静态模拟生长体系.[结果]4种水生植物对富营养化湖水、底泥具有一定的耐受能力.试验80 d后,凤眼莲、水浮莲和香蒲对水体总磷的去除率分别为95.0％、94.3％和92.0％.凤眼莲系统中水体磷浓度大幅度降低,底泥中的磷素逐渐释放,凤眼莲所吸收磷素来源于水体和底泥;水浮莲所吸收磷素主要来源于水体;香蒲鲜质量增加极少,在降低水体总磷浓度的同时,促使底泥总磷含量略微增加,从表观上看,水体为其吸收磷素的主要来源;轮叶黑藻植株部分发生腐烂,对水体总磷的去除率仅为62.9％,低于对照,但对底泥中总磷吸收良好,底泥是其吸收磷素的主要来源.[结论]凤眼莲、水浮莲和香蒲能有效降低水体总磷;凤眼莲和轮叶黑藻能够吸收底泥中的磷素;当水体总磷浓度较低时,底泥中的磷素会释放至水中.     

冬季水生植物分解过程及其对水质的影响研究

通过室内模拟实验,研究太湖3种常见水生植物芦苇(Phragmites australis)、马来眼子菜(Potamogeton malaianus)和荇菜(Limnanthemun nymphoides)冬季分解过程以及对水质的影响。结果表明:芦苇、马来眼子菜和荇菜的快速分解期为前4 d,在这4 d内干物质分别减少了15.9%、12.9%和38.8%;第4~48 d为缓慢分解期,3种水生植物干物质剩余量差异显著(P<0.01)。分解速率k与植物残体内的C/N显著负相关(P<0.01,n=54),与C/P呈显著负相关(P<0.01,n=54)。实验前4 d,植物组水体p H、DO值迅速下降,之后缓慢上升,总体都表现为对照组>芦苇组>马来眼子菜组>荇菜组;实验初期,植物分解向水体中释放大量N、P营养物质,水体TN、TP分别在第2、4 d达到最大,但是其对水质影响具有时效性,实验后期各组水质均无明显差异。     

水产食品特定腐败菌与货架期的预测和延长

Fresh fish and lightly preserved fish products are welcome by the global market, however, they are also among the most perishable food products. The research on specific spoilage organisms (SSO) reveals the spoilage process of aquatic product. This paper reviews the current knowledge (past ten years) on SSO of fresh fish and lightly preserved fish products with particular emphasis on characteristics of SSO and how to apply this concept to determine, predict and extend the shelf life of aquatic product. During storage, the microflora changes owing to different abilities of the microorganisms to tolerate the preservation conditions. SSO is defined as special microorganisms which can increase rapidly during preservation and has the ability to produce off- odours and off- flavours associated with spoilage, and spoilage metabolites. Identification of an SSO relies on comparison of the sensory and chemical characteristics of spoiled product with those of isolates from the spoilage microflora. Generally, the SSO of fresh fish may be a single species or genus, but the ones of lightly preserved fish products will be more complex. One exciting area for use of SSO aims to obtain quantitative knowledge about probable behavior of SSO and their function during the progression of spoilage. Thus mathematical models on the growth of SSO are established to evaluate the quality lost degree of product, which provide a sound information for the rational development of devices to monitor loss of products shelf life. Models for the growth of Pseudomonas spp, S. putrefaciens, P. phosphoreum have been established, and validated for shelf life prediction of seafood successfully. Another application field of SSO intends to develop the techniques to prolong the shelf life of food products by inhibiting SSO targetedly. Targeted inhibition of spoilage bacteria during preservation reduces their growth and results in a significant extension of shelf life in despite of the activity of non - spoilage organisms has not been influenced. Such techniques have been applied in perversion field of fresh fish and lightly preserved fish.     

Aquatic dissipation of the herbicide triclopyr in Lake Minnetonka,Minnesota

A study of the aquatic fate of the triethylamine salt of triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) was conducted in three bays of Lake Minnetonka, Minnesota. Triclopyr is under review by the US Environmental Protection Agency as a selective aquatic herbicide. The primary purpose of this study was to determine dissipation rates of the parent active ingredient, triclopyr, and its major metabolites, 3,5,6‐trichloropyridinol (TCP) and 3,5,6‐trichloro‐2‐methoxypyridine (TMP) in selected matrices including water, sediment, plants, finfish and shellfish. Two 6.5‐ha plots dominated by the weedy species Eurasian watermilfoil (Myriophyllum spicatum L) were treated with triclopyr‐triethylammonum at a rate of 2.5 mg AE liter⁻¹ (2.5 ppm) on 21–23 June 1994. A third 6.5‐ha plot was established as an untreated reference. Water and sediment samples were collected from within the plots and at selected locations up to 1600 m outside of the plots through six weeks post‐treatment for chemical residue analysis. In addition, residue samples were collected from the target and non‐target plants and other non‐target matrices, including game and rough fish, clams and crayfish. All test animals were sequestered in cages located in the center of each plot and samples were collected through four weeks post‐treatment. Half‐lives for dissipation of triclopyr and TCP in water ranged from 3.7 to 4.7 days and from 4.2 to 7.9 days, respectively, with trace amounts of TMP found. Peak triclopyr sediment values ranged from 257 to 335 ng gram⁻¹, with a mean half‐life of 5.4 days, while peak TCP sediment levels ranged from 27 to 65 ng gram⁻¹ (mean half−life = 11.0 days). Trace levels of TMP were detected at one treatment site at one sampling event. Triclopyr and TCP accumulated and cleared from animal tissues proportionately to concentrations in the water (triclopyr dissipation half‐lives <11 days, TCP < 14 days). TMP levels were two to three times higher than those of the other compounds, particularly in visceral tissue. In all cases, residues of these compounds were higher in the inedible portions of the animals, and were usually higher in bottom‐feeding fish species. © 2000 Society of Chemical Industry