Toxicity of Pesticides to Fecundity,Hatchability and Survival of Young Snails of Lymnaea acuminata

The effects of carbaryl and phorate on the fecundity and hatchability of the snail Lymnaea acuminata, the survival of young snails were studied. It was observed that the fecundity of Lymnaea acuminata was reduced only at the 11.00 mg/l concentration of carbaryl and phorate, whereas a time- and dose dependent reduction in the hatchability of exposed eggs and the survival of young snails was observed.     

Effects of heavy metals on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus (Powys)

The effects of Cu, Cd, Zn and Cr on the survival and feeding behaviour of the sandy shore scavenging gastropod Nassarius festivus were compared. The 96-h LC₅₀ for Cu, Cd, Zn and Cr were 0.36, 1.52, 1.76 and 36.9 mg l⁻¹, respectively. Four sublethal concentrations of each metal plus a control were prepared and the snails were exposed to experimental solutions for 96 h. Feeding behaviour was studied after the snails were starved for five days. As compared with the control, the number of individuals feeding was significantly reduced by exposure to 0.05 mg l⁻¹ Cu, 0.2 mg l⁻¹ Zn, 0.5 mg l⁻¹ Cd and 5 mg l⁻¹ Cr. The time spent feeding was greater for individuals exposed to greater concentrations of Zn and Cd but no effect was found for Cu and Cr. Chemoreception of food was studied by placing the snails at a fixed distance of 15 cm from the bait. The success rate of reaching the bait was less for individuals exposed to Cr but no effect was found for Zn, Cu or Cd. The time required for an individual to reach the bait decreased as the concentration of Zn increased. In contrast, a longer time was required for individuals exposed to Cr whereas the effect of Cd and Cu was insignificant. The potential of using feeding behaviour and chemoreception in contaminant evaluations is discussed.     

Molluscicidal Activity of Euphorbiales against the Snail Indoplanorbis exustus

Mortality caused to the snail Indoplanorbis exustus by the latices of four species of plants belonging to the family euphorbiaceae has been reported. This snail is the vector of the liver fluke Fasciola hepatica and Fasciola gigantica. It was found that very low concentrations of the latex were effective in killing the snails. The order of toxicity of the four plants was E. royleana > E. antisyphilitica > E. lactea cristata > J. gossypiifolia. The toxic activity of these plants was marginally lost after extraction by organic solvents. The toxic effect of all the plants was both dose and time dependent. It has been suggested that the latex of these plants may eventually find use as molluscicides in the field.     

Malathion induced biochemical alterations in the liver of the fingerlings of Channa punctatus (BL.)

The effect of a sublethal concentration of malathion (95% E. C.) on the nucleic acids (DNA, RNA) and protein content in the liver of fingerlings of Channa punctatus, a freshwater murrel was investigated. 10 days of exposure brought non-significant alteration (P < 0.05) neither in the nucleic acids nor in protein content. However, significant quantitative decline in the liver's RNA (P < 0.01) and protein (P < 0.001) but not in the DNA content was observed after 20 days of exposure. Possible causes for such decline have been discussed.     

Adsorption of Thallium(I) Ions Using Eucalyptus Leaves Powder

Using batch method, the adsorption of thallium(I) ions from aqueous solutions on eucalyptus leaves powder, as a low cost adsorbent, was studied. The effect of various modification of considered adsorbent on the adsorption percentage of Tl(I) is an important feature of this study. The results showed that the unmodified and acidic modified adsorbent are the poor adsorbents for the Tl(I) ions while basic modified adsorbent is a suitable adsorbent. Also, the effect of some experimental conditions such as solution initial pH, agitation speed, contact time, sorbent dosage, temperature, particle size, and thallium initial concentration was studied. The results showed that the adsorption percentage depends on the conditions and the process is strongly pH‐dependent. The satisfactory adsorption percentage of Tl(I) ions, 81.5%, obtained at 25 ± 1°C. The equilibrium data agreed fairly better with Langmuir isotherm than Freundlich and Temkin models. The value of q_m that was obtained by extrapolation method is 80.65 mg g^?1. Separation factor values, R_L, showed that eucalyptus leaves powder is favorable for the sorption of Tl(I). The negative values of ΔH⁰ and ΔS⁰ showed that the Tl(I) sorption is an exothermic process and along with decrease of randomness at the solid–solution interface during sorption, respectively.     

三峡水库十年生态调度(2011—2020年)期间下游沙市江段产漂流性卵鱼类自然繁殖变化

2011—2020年,三峡水库共开展了14次促进坝下江段四大家鱼自然繁殖的生态调度试验,于每年5—7月在长江中游沙市江段开展鱼类早期资源调查研究,旨在掌握生态调度实施以来产漂流性卵鱼类自然繁殖的响应变化,评估生态调度对长江中游鱼类自然繁殖的贡献。十年间共采集到鱼卵35种,其中典型产漂流性卵鱼类有25种,主要种类包括贝氏?(Hemiculter bleekeri)、鯿(Parabraims pekinensis、银鮈(Squalidus argentatus)、草鱼(Ctenopharyngodon idellus)、鲢(Hypophthalmichthys molitrix)、翘嘴鲌(Culter alburnus)和花斑副沙鳅(Parabotia fasciata);鱼卵群落多样性指数H、均匀度指数E和稳定性指数ICV在年际间呈现先降低后升高的变化趋势,优势度指数D恰好相反,变化拐点出现在2017年,表明2017年以来群落多样性趋于增加,群落结构趋于稳定;产漂流性卵鱼类繁殖规模总体呈先减少后增加变化,有8个类群的繁殖规模逐年增加,鱼类繁殖高峰频次逐渐升高,大规模繁殖出现的时段逐渐延长...     

光照对海菜花(Ottelia acuminata)种子萌发、幼苗生长及生理的影响

为研究滇池海菜花衰退消亡的原因,探讨其恢复的可能性,通过模拟实验研究了光照对海菜花种子萌发和幼苗生长及生理的影响.结果表明光照强度对海菜花种子萌发的影响不显著;光照强度显著影响海菜花幼苗的生长,其中71.8%和91.5%遮光条件下海菜花的平均叶片长度、叶片宽度和株高均显著高于无遮光和97.6%遮光条件下其平均叶片长度、叶片宽度和株高,平均生物量显著高于97.6%遮光条件下其平均生物量;实验中期不同光照条件下,海菜花叶片叶绿素a含量差异显著,其中71.8%遮光条件下海菜花叶片叶绿素a含量显著高于无遮光和97.6%遮光条件下其含量;光照强度对海菜花叶片过氧化物酶活性影响不显著.富营养化导致的水体透明度低、光照强度弱不影响海菜花种子萌发,但影响了海菜花的生长发育和生理特性,进而可能影响了海菜花的繁殖,这可能是滇池海菜花消亡的原因之一.因此恢复海菜花必须提高水体透明度,改善光照强度.     

The Impact of Snail (Bellamya aeruginosa) Bioturbation on Sediment Characteristics and Organic Carbon Fluxes in an Eutrophic Pond

A mesocosm experiment was conducted for 32 days in an eutrophic pond to study the effects of the bioturbation of the freshwater snail, Bellamya aeruginosa, on the benthic environment and to further understand cycling of organic carbon in water containing algal blooms. Chlorophyll‐a (chl‐a), phaeopigment, and organic matter contents of sediment, sediment oxygen consumption (SOC), and dissolved organic carbon (DOC) fluxes were determined on day 1, 16, and 32, respectively. The SOC decreased on day 16 and increased on day 32 significantly with the increase in snail density. DOC fluxes showed a net sediment uptake in all enclosures throughout the experiment. DOC fluxes in the high and mid density treatments were lower than those of the control. The concentrations of chl‐a and phaeopigment in the sediment increased significantly with snail density, indicating that the presence of snails reduced the biomass of phytoplankton. The results suggest that freshwater snails, B. aeruginosa, could influence the algal biomass (chl‐a) of small water bodies by their bioturbation effects on sediment characteristics and the fluxes of organic carbon.     

Dark induced reproductive inhibition of Daphnia carinata during the 1995 solar eclipse

Population of Daphnia carinata exposed to different times on the day showed sharp inhibition of reproduction (measured different life table data) on the day of solar eclipse as compared to pre- and post-eclipse days. Sudden fall of water temperature and abrupt change to darkness as prevailed during the solar eclipse were responsible for inhibition of reproduction in Daphnia carinata. Cold and dark induced reproductive inhibition was also confirmed in a simulated experiment mimicing eclipse reduction in light and temperature.     

基质类型对耳萝卜螺(Radix auricularia)-苦草(Vallisneria spiralis)牧食关系的影响

沉水植物和螺类都是水生生态系统的重要组成部分,两者的牧食关系也是水生食物网中重要的一环,而不同的基质类型可能会影响两者的生长和改变沉水植物对螺类牧食的防御策略.以耳萝卜螺（Radix auricularia）和苦草（Vallisneria spiralis）为对象,研究基质类型、螺类牧食对沉水植物的生长及防御策略的影响,以及基质类型及沉水植物对螺类生长和生理特征的影响.研究发现,螺类牧食和基质类型对苦草生长和元素特征具有显著的影响,存在螺类牧食时,泥沙基质和沙基质苦草的相对生长速率显著降低,泥沙、沙和泥基质苦草地上生物量分别减少了67.74%、58.58%和17.84%,根冠比分别升高了177.51%、217.23%和1.44%;且泥沙基质中苦草的叶片数显著低于无牧食组.不同基质类型下,牧食对苦草总碳含量无显著影响,但泥和泥沙组中,螺类牧食使苦草的总氮含量均显著降低,碳氮比均显著升高;沙基质下,螺类牧食使苦草总酚含量显著降低.基质类型对螺类的形态特征（除壳宽外）、生长及元素含量均无显著影响.总体来看,基质类型对耳萝卜螺牧食和苦草防御策略具有一定程度的影响,但对螺类的生长及元素特征基本无影响.本研究可以为牧食理论的研究提供基础数据支持,也可为沉水植被恢复、水生生态系统稳定提供参考,但基质类型对螺草牧食关系的长期影响,仍需进一步深入研究.     

Reproductive traits of the freshwater shrimp Caridina fossarum Heller, 1862 (Decapoda, Caridea, Atyidae) in the Ghomp-Atashkedeh spring (Iran)

In the present study, some biological traits of Caridina fossarum reproduction are studied in the Ghomp-Atashkedeh spring (Fasa, Shiraz, Iran), for the first time. This Iranian endemic freshwater species was studied from April 2007 to March 2008. Minimum sexable size (MSS) and absolute or relative size at the onset of maturity (SOM and RSOM) in terms of carapace length (CL) was found to be 2.4 mm, 4.3 mm and 55%, respectively. Sex ratio showed variations on a monthly basis. Sex reversal is a possible scenario for C. fossarum because the size-specific sex ratio revealed a reverse pattern. Based on the proportions of ovigerous females, the main breeding season was determined to be from April to August, demonstrating a peak during early spring. There is a period of extended recruitment at water temperatures above 20 °C. The size at which 50% of females are mature was estimated at CL = 5.03 mm from the proportion of ovigerous females during the breeding season. The pleopodal egg number varied from 3 to 75 eggs per female with a mean value 34.39 ± 14.27. The results showed that although there is a significant relationship between carapace length CL and pleopodal egg number, it is not the most important factor affecting potential fecundity in C. fossarum due to the low values of slope (= 1.51) and determination coefficient (= 0.052).     

Effects of elevated CO2 on the reproduction of two calanoid copepods

Some planktonic groups suffer negative effects from ocean acidification (OA), although copepods might be less sensitive. We investigated the effect of predicted CO₂ levels (range 480–750 ppm), on egg production and hatching success of two copepod species, Centropages typicus and Temora longicornis. In these short-term incubations there was no significant effect of high CO₂ on these parameters. Additionally a very high CO₂ treatment, (CO₂ = 9830 ppm), representative of carbon capture and storage scenarios, resulted in a reduction of egg production rate and hatching success of C. typicus, but not T. longicornis. In conclusion, reproduction of C. typicus was more sensitive to acute elevated seawater CO₂ than that of T. longicornis, but neither species was affected by exposure to CO₂ levels predicted for the year 2100. The duration and seasonal timing of exposures to high pCO₂, however, might have a significant effect on the reproduction success of calanoid copepods.     

Demographic parameters and mixis of three Brachionus angularis Gosse (Rotatoria) strains fed on different algae

Rotifers are one of the smallest metazoans, served as perfect material for evolution theories and excellent food resources to larva in aquaculture. Population dynamics of rotifers help to optimize culture conditions, and to understand selection of asexual and sexual reproduction types. We described population dynamics of three Brachionus angularis strains using the life table method, with three types of food. The following demographic parameters were analyzed: intrinsic rate of increase (r), net reproductive rate (R₀), generation time (T), average lifespan (L), and the total percentage of mictic females in the offspring. The results showed that there were significant effects of strain on the parameters except for R₀. However, the food type significantly affected r, R₀, T, and the total percentage of mictic females in the offspring. Demographic parameters differed among strains, showing the possible adaptation to local niches. In comparison to Chlorella pyrenoidosa, Scenedesmus obliquus served more nutrition to enlarge population size, and more mixis was induced in rotifer populations fed on it.     

Vergleichende Untersuchung der Diäten vonLymnaea auricularia undL. peregra (Gastropoda: Basommatophora) im Zürichsee

Two very similar species of freshwater snails,Lymnaea auricularia andL. peregra coexist in Lake Zürich. We examined their diets to determine possible differences. Microscopic analysis of stomach and hind gut contents revealed no marked differences between the diets of the two snail species collected from the same substrate. However, in both species we found significant differences between the composition of the substrate and that of the stomach contents, using discriminant analysis. We conclude that both species of snails feed preferentially on patches of favourable food supply and that their diets overlap almost totally. The coexistence of the two species under these conditions suggests that food does not limit their density in the area studied.     

基于生物水文响应模型的刺激四大家鱼繁殖生态调度目标量化方法研究——以三峡水库为例

为了改善生态调度效果,提高生态调度实践成功率,采用医学领域适用性广、准确性高、直观性强的受试者工作特征曲线法(receiver operating characteristic, ROC),以三峡水库为例,提出了一套基于生物水文响应模型的刺激四大家鱼繁殖生态调度目标量化方法,包括涨水事件界定及生态水文指标选择、鱼类自然繁殖事件及有效繁殖响应界定、生物-水文响应模型构建与多指标判别优选等多个环节。运用三峡水库运行后2013—2019年(除2016年)6年47场次宜昌江段的涨水事件和24次四大家鱼有效繁殖响应的实际观测数据构建模型并量化三峡水库生态调度目标。结果表明:(1)依据初始流量Q₀、洪峰流量Q_peak、流量总增长量Q_sum和流量日增长率dQ这4个指标所建立的单指标生物-水文响应模型具有较好判别四大家鱼自然繁殖对水文条件是否响应的能力;(2)各评价指标Q₀、Q_peak、Q_sum、dQ的最佳阈值分别为14960 m³/s、19610 m³/s、4050 m³/s及1405 m³/(s·d);单指标模型性能排序为dQ＞Q_peak＞Q_sum＞Q₀;(3)依据dQ或Q_peak的指标组合方式建立的多指标生物-水文响应模型综合性能最佳。结果表明,ROC模型方法结果形式简单、预见性强,据此量化生态调度目标,可为其他流域、水库的鱼类繁殖响应判别和水库生态调度方案制定提供参考借鉴。     

Influence of IHSS Standard and Reference Materials on Copper and Mercury Toxicity to Vibrio fischeri

The reduction in light emission of the marine bacterium Vibrio fischeri used in the standard Microtox^® bioassay was measured for the metals copper and mercury. The concentration at which the light emission was reduced by 50% (EC₅₀) was determined to be (3.43 ± 0.83) μmol/L for Cu²⁺ and (0.66 ± 0.01) μmol/L for Hg²⁺. The reduction of the toxicity of these metals by humic and fulvic acids were studied using IHSS Standard and Reference Materials. Copper toxicity was reduced 17...20% by the soil and peat fulvic acids and 9...20% by the aquatic fulvic acids. While there appeared to be little difference in the reduction of Cu toxicity by fulvic acids from soils, peats, or aquatic systems, Hg toxicity was reduced 3.6...7.3% by the soils and peats, while aquatic fulvic acids reduced Hg toxicity 14...16%. Soil fulvic acids appear to have significantly less capacity to reduce Hg toxicity than Cu toxicity. Humic acids had much higher reductions of Cu toxicity (44...124%) compared to the fulvic acids, with little difference between aquatic and soil or peat humic acids, 44...124% and 67...100%, respectively. However, humic and fulvic acids, regardless of origin, had approximately the same effect on Hg toxicity with 3.5...16% reduction by fulvic acids and 8...20% reduction by humic acids. Unlike the fulvic acids, no clear trend was observed relative to origin of the humic acids. There was no correlation between percent reduction of Cu or Hg toxicity by the organic compounds and copper binding capacity (CuBC), C/N ratio, or carboxyl content of the materials. Examination of natural organic matter (NOM) isolated by reverse osmosis techniques from three water sources had reductions of both Cu and Hg toxicity that were most similar to the Suwannee River and Nordic fulvic acids.     

Copper (II) Speciation in a Freshwater Ecosystem

Results of chemico-biological experiments in a natural water body with the use of model systems with Cu (II) introduced in them at different proportions of its chemical forms (natural and simulated) in the solution. The model forms used in the experiments were Cu complexes with benzyl- and hexadecylmalonic acids, simulating low-molecular dissolved organic substances. The experimental conditions were chosen based on a preliminary calculation using WATEQ–4f program. The complexes of Cu with hexadecylmalonic acid are found to be absorbed by suspensions and removed into bottom sediment more actively than other Cu forms. The toxicity of introduced Cu for the phyto- and zooplanktonic communities is found to depend on the concentration of Cu²⁺ aqua-ions in the solution, in the presence of which the higher concentrations of complexes with malonic acids do not exert their toxic effect.     

Influence of a Xenobiotic Mixture (PCB and TBT) Compared to Single Substances on Swimming Behavior or Reproduction of Daphnia magna

Aroclor 1254, a technical PCB mixture (polychlorinated biphenyls) and TBT (tributyltinchloride) are environmental pollutants that cause a broad spectrum of acute toxic and chronic effects in aquatic animals. In this paper, the sensitivity of Daphnia magna to chronic exposure to mixed xenobiotics was evaluated under laboratory conditions. The results show that xenobiotic mixtures (50 % each of the single compounds) were more toxic than individual xenobiotics alone. By measuring behavioral parameters of animals, it becomes evident that exposure to single xenobiotics significantly affects daphnids: exposure led finally to a rapid decrease in mean swimming activity and also caused changes in preferred swimming depth, with daphnids preferring the upper layers of aquaria. The mixture altered the swimming behavior even more strongly compared to the group stressed by single chemicals. Finally, all daphnids sank to the bottom of the aquaria, still alive, but inactive at the end of the exposure period. In addition, we investigated the reproductive capacity (number of newborn per female and day). PCB did not affect the number of newborn significantly, TBT‐stress led to an evidently decreased number of young daphnids and the xenobiotic mixture decreased reproduction even more. In conclusion, we found significant effects of the single compounds as well as approximately additive (swimming behavior) and synergistic (reproduction) effects of the chemical mixture on daphnids indicating the possibility of dramatic ecological consequences of the occurrence of mixed xenobiotic substances in the aquatic environment.     

Studies on the Toxieity of Pulp and Paper Factory Wastes to the Fish Notopterus Notopterus (PALLAS)

Studies are performed on the toxicity for 24, 48, 72 and 96 hours in the static test with dilutions of 10 … 32 vol.% of wastewaters from the pulp and paper production as well as of the mixed wastewater. The pulp waste shows the highest toxic effect, the LC₅₀ of the three types of wastewater being between 15 and 27% in dependence on the test conditions. A general increase of the toxic effect is caused by a rise in temperature from 26 °C to 36 °C and an increase of the pH value from 7.5 to 8.2. The increase of the oxygen concentration from 5.2 to 7.2 mg/1 results in a reduction of the toxicity of the pulp and mixed wastes, the size of fishes having a significant effect only for the pulp waste. Concentrations of wastes of 6 … 9% may be regarded to be harmless for long periods of time.