盐度对透明溞存活、生长和繁殖的影响

采用试验生态学方法,在恒温(20±1)℃条件下,研究盐度变化对透明溞存活、生长和繁殖的影响。试验结果显示,透明溞的24 h和48 h半致死盐度分别为4.16和2.67,安全盐度为0.36。透明溞的产前发育期和有效积温随盐度上升而增加;体长增长率随盐度的升高先升后降,存活时间和内禀增长率随盐度的升高而下降。盐度对透明溞生存、生长及繁殖的影响显著(P<0.05),0.5盐度组的透明溞壳刺长显著大于对照组。研究结果表明,透明溞为嫌盐种,对盐度耐受性低。透明溞可作为水产经济动物开口饵料、水体盐碱变化的指示生物,对水环境监测具有重要意义。     

Kinetics of 110mAg, 60Co, 137Cs and 54Mn Bioaccumulation from Water and Depuration by the Crustacean Daphnia Magna

As part of a research program on the transfer withinfreshwater ecosystems of the radionuclides present inthe weakly radioactive liquid effluents from nuclearpower stations, this article presents an assessment ofthe dynamics of zooplankton contamination from water.The experiments were carried out on young pre-adultdaphnids, placed at a density of 250 individualsL^-1, in 0.45 m filtered river water. Inorder to maintain the radionuclide contamination at ahigh level and to limit alterations in the chemicalcharacteristics of the medium, the water was reneweddaily. The dynamics of contamination were described bya one (¹³⁷Cs) or a two compartmental model(^110mAg, ⁶⁰Co and ⁵⁴Mn), taking intoaccount the fluctuations of the radionuclideconcentration in the water, as well as the growth rateof the daphnids. The contamination levels weredescribed by the steady state value of theconcentration factor, which was 2870 mL g^-1 wetweight, 320 mL g^-1 wet weight, 265 mL g^-1wet weight and 30 mL g^-1 wet weight, for^110mAg, ⁵⁴Mn, ⁶⁰Co and ¹³⁷Cs,respectively. During the depuration phase,radioactivity decrease in daphnids was a very fastphenomenon indicating that radionuclide adsorption tothe surface was the major process involved in thecontamination of daphnids. The two correspondinghalf-lives of the depuration kinetics were 10 min and7 d, 20 min and 1 d and 3 hr and 1.5 d for⁶⁰Co, ^110mAg and ⁵⁴Mn, respectively.The loss of ¹³⁷Cs was characterised by a singlehalf-life of 0.3 d.     

多氯联苯（PCB_（153）与PCB_（28））对大型溞的毒性效应研究

选用大型溞作为受试生物,探讨多氯联苯（PCB153与PCB28）对浮游动物的急性和慢性毒性反应,初步评价多氯联苯（PCBs）对浮游动物的毒害效应。急性毒性试验中,PCB28和PCB153对大型溞的48h-LC50分别为27.08μg·L-1和579.16μg·L-1。实验表明,大型溞对PCB28的敏感性高于对PCB153的敏感性。慢性毒性试验显示,PCB28和PCB153对大型溞的生长、生殖均有不利影响,PCB28的影响表现为随浓度的升高,生长和生殖抑制效应加强;PCB153对大型溞生长的影响表现为随浓度升高而抑制效应增强,但其对大型溞的繁殖则表现为低浓度抑制而高浓度促进的现象虼耍团ǘ榷嗦攘剑≒CB153、PCB28）长期暴露的潜在毒性和高浓度多氯联苯的急性毒性在环境生态安全研究中值得高度关注。     

无鱼和贫营养条件下水盔形溞对浮游动物群落结构的影响

为了解无鱼条件下贫营养水体中大型枝角类盔形溞(Daphnia galeata)的种群动态及其对浮游动物群落结构的影响,于2010年3月5日至4月18日在流溪河水库进行围隔试验,设置1个对照组和3个处理组,每个处理有3个重复。对照组(C)为用孔径约2 mm的网过滤后的水库水抽入围隔,试验组抽入过滤后的水库水后添加高、中、低密度(H,M,L)的盔形溞,对照组和试验组添加的盔形溞密度梯度分别为0、0.3、0.6、1.0个/L。无鱼条件下盔形溞种群快速形成高峰,但随后由于食物限制又快速下降。盔形溞高密度种群的建立对轮虫种群产生了显著影响,试验开始后轮虫受到盔形溞抑制而密度下降。在试验后期,食物数量下降,盔形溞密度下降并维持在较低的密度,而大型桡足类中的舌状叶镖水蚤(Pyllodiaptomus tunguidus)密度增加,显示了竞争优势。由于大型围隔试验对浮游动物操作的可重复性较差,个别围隔中出现了透明薄皮溞(Leptodora kindti),也对盔形溞种群及浮游动物群落结构产生了影响。     

废弃农药厂污染场地浅层地下水生态毒性诊断研究

选择大型溞、斜生栅藻、发光菌为试验生物,对某废弃农药厂污染场地4个不同区域土壤剖面浅层地下水编号为CP01、CP02、CP03、CP04的4种水样进行了急性毒性试验,同时对水样进行了化学分析。结果表明,4种水样对大型溞的24h-EC50分别为0.29%、5.12%、0.83%、1.99%;对斜生栅藻的96h-EC50分别为11.04%、50.44%、12.21%、41.66%;对费舍尔弧菌的发光抑制率分别为95%、66%、88%、75%。化学检测结果表明,CP01中的主要污染物为苯系物与少量烷烃、烯烃类多种物质,CP02中的污染物质只有少量二氯甲烷与1,2-二氯乙烷两种物质,CP03、CP04中的主要污染物为苯系物与烷烃多种物质。毒性试验结果与化学检测结果具有较好的相关性,3种试验生物的毒性效应结果相一致。该研究方法简单快速,可以用于污染场地水样污染毒性诊断,快速筛选出敏感区域,同时提供污染物质的联合毒性基础数据,为场地进一步危害识别与风险评估提供依据。     

Evaluation of a Multi-species Test System for Assessing Acute and Chronic Toxicity of Sediments and Water to Aquatic Invertebrates: Effects of Pentachlorophenol on Daphnia magna and Chironomus prasinus (6 pp)

Background, Aims and Scope   Single-species toxicity tests are currently used as main tools for assessing effects in ecological risk assessments. Nevertheless, in higher-tier evaluations, alternative ecotoxicological methods can be required. Alternative methods should cover more realistic exposure conditions and/or additional species or endpoints. Water/sediment systems can be considered for covering additional exposure routes. A typical feature of water/sediment systems is the modification of exposure levels with time. The simultaneous exposure of different species within the same system can cover differences in sensitivity and relevance of exposure routes. The aim of this study was to develop a water/sediment test that could detect relevant effects on two selected species and explore the relevance of sediment and waterborne exposure routes. This alternative method may provide relevant information facilitating the design of microcosm and mesocosm studies.Methods   A multi-species water/sediment system was designed using two invertebrates: Chironomus prasinus a benthic detritivore invertebrate and Daphnia magna a pelagic filtering invertebrate was designed. Seven static water/sediments systems were built up: two controls and five treatments where sediments were spiked with NaPCP at nominal concentrations of 1.25, 2.5, 5, 10 and 20 mg/kg, respectively. Each system contained caged and free (unrestrained) Daphnia magna organisms to consider differences in the exposure route (through sediment and/or water column) and Chironomus prasinus organisms. Fate and partitioning of PCP within the water/sediment compartments were assessed. Acute (lethality) and chronic effects (reproduction) for Daphnia magna were monitored after 48 h and 16 days of exposure, respectively. Adult emergence and oviposition success of Chironomus prasinus were monitored at the end of test (16 days).Results and Discussion   Mortality and reproduction inhibition of Daphnia magna occurred at the two higher doses, corresponding to maximum measured PCP water concentrations of 1.95 and 0.746 mg/l, respectively. Chironomus prasinus was less sensitive to PCP than Daphnia magna. Concentrations inhibiting reproduction and provoking almost 100% adult mortality in D. magna only reduced slightly the emergence and reproduction of chironomids. The experimental design focussed on suitability of the system for assessing simultaneously assessing effects on D. magna and C. prasinus instead of calculations of toxicity endpoints for PCP. The results indicate that this experimental design can be useful to the field of sediment/aquatic toxicity testing, particularly through the comparison with single- species results. Assessment of relative contribution of two exposure routes for Daphnia magna and complementary chronic endpoints derived from two different species can be achieved. Another advantage is that differences in reproduction strategies of selected species (sexual vs. parthenogenetic) should permit one to detect mechanisms of action associated to with endocrine disrupters.Conclusion   The feasibility of a two-species test built-up in an artificial sediment/water system has been demonstrated. This experimental design represents a cost/effective test which can assess effects through water and sediment pathways and incorporates several relevant chronic endpoints in a single assay. Recommendation and Outlook   By building on the experience gained, improvements for further test designs are discussed. Test validation with a set of model chemicals will contribute to address the effectiveness of the test developed as comparing compared to single- species tests.     

三种除草剂对大型溞Daphnia magna存活、生长和繁殖的影响

为了制定除草剂在水环境中的允许浓度和排放标准,参照美国公共卫生协会等编著的《水和废水标准检验法》以及我国制定的大型溞Daphnia magna毒性测定方法,进行了丁草胺、吡嘧磺隆、苄嘧磺隆 3种稻田常用除草剂对大型溞的21 d慢性毒性试验。结果发现:随着除草剂浓度的升高,大型溞的产前发育期、产幼间隔期均缩短,每胎产幼数量先增加后减少;丁草胺各浓度处理组中,内禀增长率(rm)在0.157 2~0.314 0 d-1之间,变化较大;吡嘧磺隆各个浓度组的rm相对平稳, 为0.206 6~0.276 8 d-1;大型溞在苄嘧磺隆处理组中的rm比在其他两种除草剂中的高,为0.334 1 ~0.397 1 d-1。在丁草胺处理组中,大型溞的日生殖量较少,低于吡嘧磺隆和苄嘧磺隆处理组。     

不同脂肪源饲料培育的大型蚤对中华绒螯蟹仔蟹发育和变态的影响

2003年5月20日至6月22日,研究了不同脂肪源饲料培育的大型潘对中华绒螯蟹发育和变态的影响。采用纯酵母（酵母组）、酵母添加10％豆油（豆油组）和酵母添加10％鱼油（鱼油组）三组饲料培养的大型潘作为大眼幼体发育到仔蟹Ⅳ期的生长和蜕壳的饵料。实验期间水温为室温,温度为20～24℃。结果表明,鱼油组培养的大型潘能显著地加速仔蟹发育阶段变态时间（缩短蜕皮周期）,促进生长。其次为豆油组。酵母组最差。其加速变态的效果在仔蟹I期发育变态到Ⅱ期就显著表现出来。此外,鱼油组,豆油组与酵母组相比,相应仔蟹期的规格较大。脂肪酸组成分析显示,仔蟹脂肪酸的组成在一定程度上,反映了其摄食不同脂肪源饲料培育的大型滔的脂肪酸组成。鱼油组的仔蟹具有相对高的EPA,DHA和HUFA的百分组成,而豆油组培育的仔蟹由于大型潘中含有较高含量的C18：2,而致使仔蟹的C18：2具有最高含量。实验证实,饵料中高HUFA的含量,能显著促进仔蟹的生长和变态。PUFA,特别是C18：2对仔蟹变态和成活也有一定的促进作用。     

Control of ecosystem state in a shallow,brackish lake: implications for the conservation of stonewort communities

• 1. The alternative stable states hypothesis for the behaviour of shallow lake communities requires switches to transform clear-water macrophyte-dominated communities to turbid algal-dominated ones. Such switches have rarely been demonstrated experimentally. This study shows the role of rising salinity as such a switch while contributing a solution to the conservation problems of an important nature reserve.
• 2. Hickling Broad changed from a clear-water, charophyte-dominated lake to a turbid, phytoplankton-dominated lake in the early 1970s, probably owing to guanotrophication by gulls and to increased salinity from more intensive pumping of the agricultural land that separates its main inflow from the nearby North Sea. Following a decline in nutrient loading as the gull flock moved away, the plants began to return during the 1980s and 1990s. In 1998/99, the water cleared and charophytes, including some very rare species, were abundant.
• 3. This was welcome to conservation bodies, but the vigorous growth precluded competitive sailing and there were conflicts with the local sailing club. The plants, however, began an irregular decline in 2000, though nutrient loadings and other conventional chemical drivers have remained steady.
• 4. Our hypothesis was that the unstable nature of the plant community was linked to high salinity, and that if salinity were lowered there would be vigorous and reliable growth, enabling annual cutting of plants to allow sailing races. In an experiment using mesocosms, salinities straddling the current values in the Broad led to declines in plant biomass, macrophyte species richness and macrophyte Shannon–Weaver diversity through increased release of phosphorus from the sediments, increased algal turbidity and reduction of zooplankton grazer activity.
• 5. Stabilization of the plant community of Hickling Broad would be achieved by a reduction of present salinities by about 20%. This would be possible by use of existing Environmentally Sensitive Area (High Level Environmental Stewardship) arrangements or diversion of some pumped drainage water to the sea. There remain some uncertainties about the future of the area because of rising sea levels.

Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of plant oligosaccharides derived from dragon fruit on growth,reproduction and survival of freshwater crustacean Daphnia magna

The freshwater crustacean Daphnia is widely used as live food for ornamental fish. To increase production, food supplementations are required when culturing Daphnia. Here, we aimed to clarify the effects of plant oligosaccharides derived from dragon fruit (DFO) on growth rate, egg production, number of first clutch juveniles and survival of Daphnia supplemented with five different concentrations of DFO, that is 0, 1, 3, 9, 27 mg/L. The results showed the growth and reproduction of Daphnia were enhanced when supplemented with DFO. Growth rate of Daphnia supplemented with 9 mg/L DFO was the highest among all treatments. The time that Daphnia produced the first clutch eggs was shorter in high concentration of DFO (3, 9, 27 mg/L). The number of juveniles in the first clutch increased in treatments of higher concentration of DFO (3, 9, 27 mg/L). These results suggest that plant oligosaccharides derived from dragon fruit increase growth and fecundity of Daphnia. Survival rates of Daphnia were 100% except for the treatment supplemented with 27 mg/L of DFO in which the survival rate was reduced to 87%. To our knowledge, this is the first functional evidence demonstrating that oligosaccharides derived from dragon fruit enhance growth and fecundity of Daphnia.