Toxicity and bioaccumulation of chromium in some freshwater fish

Chromium (Cr) is a common pollutant of freshwater bodies in India, and is frequently detected in high concentrations in edible fish. Bioassays were carried out in the laboratory to determine acute the toxicity and pattern of accumulation of Cr in three species of freshwater fish. The 96-h LC₅₀ value of Cr for Labeo bata, Puntius sarana, and Catla catla was found respectively as 7.33, 10.37, and 31.61 mg/L. Concentrations of Cr in water, sediments, and fish, during a period of 28 d of exposure to 0, 0.73, and 2.19 mg/L of Cr, varied with exposure period, concentration of Cr, presence of weed, and species of fish exposed. Polynomial regressions obtained by drawing polynomial curves revealed that the aquatic weed Eichhornia crassipes prevented gradual decrease of Cr concentrations in water, but reduced the accumulation of Cr in L. bata and Catla catla. However, the effect of the weed on Puntius sarana was not apparent. The pattern of Cr deposition on sediments was also inconsistent. To explain interactions between environment and fish in a very precise manner, polynomial and multiple regression curves were simultaneously used. When polynomial curves were replaced by multiple regression curves, it was revealed that the aquatic weed E. crassipes could reduce Cr accumulation in Puntius sarana also.     

Water cytotoxicity and dioxins bioaccumulation in an Egyptian delta wetland ecosystem

Manzala Lake, as one of the main Egyptian wetland ecosystems, is facing risks of pollution. An in vitro cytotoxicity test using a mammalian cell line was employed to determine the toxicity of multiple pollutants in the water and Tilapia zillii fish sampled from the lake. The concentrations of seven polychlorinated dibenzo-p-dioxins and ten polychlorinated dibenzofurans were investigated in water and muscle of the fish in 2014. Cytotoxicity testing showed that the percentage inhibition of cell viability in the studied sites ranged between 56.16% and 83.22%. Dioxin analysis indicated that the average concentrations of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran and 1,2,3,4,6,7,8,9-octachlorodibenzofuran were higher than the toxic equivalence quotients (TEQs) set by the World Health Organization (WHO) in all water and fish muscle samples; however, the average concentration of 2,3,7,8-tetrachlorodibenzofuran was higher only in fish muscle samples. The bioaccumulation factor (BAF) ranged dramatically between 2 and 58.5 for the detected dioxins. Adverse human health effects through the consumption of fish are not expected, because dioxin levels in fish muscle are deemed safe for human consumption. Implementation of a strategic multidisciplinary action plan is strongly recommended to sustain this delta wetland ecosystem.     

Zooplankton cultivation and prawn seed-production in an artificial ecosystem

The cultivation experiments were conducted in two parts: (1) zooplankton cultivation in a heterogeneous system as fundamental research (Experiment I); (2) prawn seed-production in a homogeneous system as applied research (Experiment II). In Experiment I, several types of apparatus were designed in order to study a feedback system for cultivation of zooplankton (Brachionus plicatilis andTigriopus japonicus). A 550-1 round transparent tank was used for reserve culture, A 150-1 zigzag stream unit was made of vinyl plates, and connected with the reserve culture tank. In both cases, the water was re-circulated 20 times a day by an airlift pump. A tower-decomposer tank and two blowing cultivators were specially designed for promoting energy-flow. During a 140-day experiment, total wet weight of feed and harvest were 4817 g of yeast and 4308 g of zooplankton, respectively. The rate of food conversionwas 89.4% in terms of wet weight and 33.6% in dry weight. In Experiment II, a 2500 m³-hatchery tank with movable aerators and airlift circulation systems was contructed to maintain an artificial ecosystem for rearing of the prawnPenaeus japonicus. Feeding rate in the 2500 m³-tank was 10.8% lower than that in the 200 m³-tank, but growth rate in the former was 10.6% higher than in the latter.     

淡水水域富营养化及其治理

简要介绍了淡水水域富营养化的成因与危害,近年来我国淡水水域富营养化现状,以及水域富营养化的主要预防与治理措施。     

Changes in functional biodiversity in an invaded freshwater ecosystem: the Moselle River

The spread of non-indigenous species and the decline of autochthonous ones are leading to a homogenization of freshwater fauna in terms of systematic units, but the functional consequences are poorly documented. We studied the peculiar case of the lower, French section of the Moselle River where 20 invertebrate species have been introduced since 1854, with a rate increasing exponentially with time. Dredge sampling performed in 1994, 1996, 2000 and 2001 at four sampling stations allowed for an evaluation of faunal changes in terms of composition, structure and function. During this period, no structural changes were recorded in spite of multiple, new and successful introductions. The evaluation of functional modifications was based on a typology of taxa exhibiting homogeneous biological/ecological traits. Functional diversity, measured as the diversity of taxa distribution among functional groupings, revealed a significant increase between 1994/1996 and 2000/2001 because those species that were over-represented during the former period reached more equilibrated densities during the latter. The major, indirect implications of these functional changes are discussed.     

Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams

The biodegradation, photolysis, and adsorption of pentachlorophenol (PCP) in outdoor, aquatic environments were examined with man-made channels built by the U.S. Environmental Protection Agency at a field station on the Mississippi River near Monticello, Minn. Four channels were used, each channel being approximately 520 m long and receiving river water that flowed through the channels for about 10 h before reentering the river. The channels were dosed continuously during the summer of 1982 with various concentrations of PCP (approximately 0, 48, 144, and 432 micrograms/liter). We monitored the biotic and abiotic degradation of PCP in these channels for approximately 16 weeks. Photolysis of PCP was rapid at the water surface, but greatly attenuated with depth. Depending on sunlight conditions, photolysis accounted for a 5 to 28% decline in initial PCP concentration. Adsorption of PCP by sediment and uptake by biota accounted for less than 15% and probably less than 5% in unacclimated water. Microbial degradation of PCP became significant about 3 weeks after the initiation of dosing and eventually became the primary mechanism of PCP removal, accounting for a 26 to 46% (dose-dependent) decline in initial PCP. Most of the PCP-mineralizing microorganisms that developed in the channels were either attached to surfaces (e.g., rocks and macrophytes) or associated with surface sediments. Total bacterial numbers (direct microscopic counts) in the various channels were not affected significantly by PCP concentrations of micrograms per liter. Numerous strains of bacteria able to grow at the expense of PCP were isolated from the adapted channels. The experiments reported here will help predict the responses of flowing aquatic ecosystems to contamination by biocides such as pentachlorophenol.     

Biodegradation and photolysis of pentachlorophenol in artificial freshwater streams.

The biodegradation, photolysis, and adsorption of pentachlorophenol (PCP) in outdoor, aquatic environments were examined with man-made channels built by the U.S. Environmental Protection Agency at a field station on the Mississippi River near Monticello, Minn. Four channels were used, each channel being approximately 520 m long and receiving river water that flowed through the channels for about 10 h before reentering the river. The channels were dosed continuously during the summer of 1982 with various concentrations of PCP (approximately 0, 48, 144, and 432 micrograms/liter). We monitored the biotic and abiotic degradation of PCP in these channels for approximately 16 weeks. Photolysis of PCP was rapid at the water surface, but greatly attenuated with depth. Depending on sunlight conditions, photolysis accounted for a 5 to 28% decline in initial PCP concentration. Adsorption of PCP by sediment and uptake by biota accounted for less than 15% and probably less than 5% in unacclimated water. Microbial degradation of PCP became significant about 3 weeks after the initiation of dosing and eventually became the primary mechanism of PCP removal, accounting for a 26 to 46% (dose-dependent) decline in initial PCP. Most of the PCP-mineralizing microorganisms that developed in the channels were either attached to surfaces (e.g., rocks and macrophytes) or associated with surface sediments. Total bacterial numbers (direct microscopic counts) in the various channels were not affected significantly by PCP concentrations of micrograms per liter. Numerous strains of bacteria able to grow at the expense of PCP were isolated from the adapted channels. The experiments reported here will help predict the responses of flowing aquatic ecosystems to contamination by biocides such as pentachlorophenol.     

Fungicide-induced declines of freshwater biodiversity modify ecosystem functions and services

Although studies on biodiversity and ecosystem function are often framed within the context of anthropogenic change, a central question that remains is how important are direct vs. indirect (via changes in biodiversity) effects of anthropogenic stressors on ecosystem functions in multitrophic-level communities. Here, we quantify the effects of the fungicide chlorothalonil on 34 species-, 2 community- and 11 ecosystem-level responses in a multitrophic-level system. At ecologically relevant concentrations, chlorothalonil increased mortality of amphibians, gastropods, zooplankton, algae and a macrophyte (reducing taxonomic richness), reduced decomposition and water clarity and elevated dissolved oxygen and net primary productivity. These ecosystem effects were indirect and predictable based on changes in taxonomic richness. A path analysis suggests that chlorothalonil-induced reductions in biodiversity and top-down and bottom-up effects facilitated algal blooms that shifted ecosystem functions. This work emphasises the need to re-evaluate the safety of chlorothalonil and to further link anthropogenic-induced changes in biodiversity to altered ecosystem functions.     

淡水生态系统中的TOP—DOWN效应与生物多样性保护

淡水生态系统中高营养级类群可以对低营养级类群产生强烈的影响,最终导致整个生态环境的改变,这一现象被称作下行（ｔｏｐｄｏｗｎ）效应。本文对ｔｏｐｄｏｗｎ的含义特别是鱼类所产生ｔｏｐｄｏｗｎ效应的结果进行了阐述,提出了ｔｏｐｄｏｗｎ效应还表现在当原来生态系统中的高营养级类群缺少时,也会造成生态系统结构与功能发生变化的观点。最后,根据淡水生态系统ｔｏｐｄｏｗｎ效应的特点,认为在淡水生态系统的生物多样性保护中,应注意高营养级类群的保护和谨慎地对待引种问题     

观光木人工林生态系统碳储量及其分布格局

在生物量调查的基础上,对南亚热带27年生观光木(Tsoongiodendron odorum)人工林生态系统的碳储量及分配格局进行了研究.结果表明:观光木人工林生态系统植被层生物量为101.26 t · hm-2,乔木层生物量占86.90％;观光木的各器官碳素含量在426.5～496.9 g·kg-1,大小排序为:树干＞枝条＞枯枝＞根兜＞粗根＞树叶＞中根＞树皮＞细根.观光木人工林生态系统总碳储量为180.49 t·hm-2,其中0～80 cm土壤层碳储量是植被层的2.67倍;乔木层年净固碳量为3.07 t·hm-2·a-1,并主要以地上部分为主.     

基于供需平衡的北京地区水生态服务功能评价

水生态系统的服务功能受到人类活动的严重胁迫和剧烈影响,对水生态服务功能的人类占用和胁迫效应进行研究具有重要意义.本文采用水当量方法,计算了1998-2007年北京地区人类活动对水生态服务功能的占用当量,并结合水资源供给量评价了人类活动对水生态系统的胁迫效应.结果表明：1）北京地区近10年人类活动的水当量超过其供给量的5～17倍;2）不同生态服务功能类型的水当量排序为：水环境净化>水资源供应>水生境维持>水安全调蓄;3）在时间序列上,水当量超过供给量的倍数呈先升后降的趋势,1999年的占用量超过其供给量的倍数最大.该研究揭示了北京地区人类活动对水生态系统服务的占用量远超过其可供给量,造成该地区水资源的过度占用,进而占用和影响其他地区的水生态服务功能.     

Pb tolerance and bioaccumulation by the mycelia of Flammulina velutipes in artificial enrichment medium

Mushrooms have the ability to accumulate high concentrations of heavy metals, which gives them potential for use as bioremediators of environmental contamination. The Pb²⁺ tolerance and accumulation ability of living mycelia of Flammulina velutipes were studied in this work. Mycelial growth was inhibited when exposed to 1 mM Pb²⁺. The colony diameter on solid medium decreased almost 10% compared with the control. Growth decreased almost 50% when the Pb²⁺ concentration increased to 4 mM in the medium, with the colony diameter decreasing from 80 mm to 43.4 mm, and dry biomass production in liquid cultures decreasing from 9.23±0.55 to 4.27±0.28 g/L. Lead ions were efficiently accumulated in the mycelia. The amount of Pb²⁺ in the mycelia increased with increasing Pb²⁺ concentration in the medium, with the maximum concentration up to 707±91.4 mg/kg dry weight. We also show evidence that a large amount of the Pb²⁺ was adsorbed to the mycelial surface, which may indicate that an exclusion mechanism is involved in Pb tolerance. These results demonstrate that F. velutipes could be useful as a remediator of heavy metal contamination because of the characteristics of high tolerance to Pb²⁺ and efficient accumulation of Pb²⁺ ions by the mycelia.     

Isolation of hexavalent chromium resistant bacteria from industrial saline effluents and their ability of bioaccumulation

The mixed cultures has been isolated from industrial saline wastewater contaminated with chromium(VI), using enrichment in the presence of 50 mg l⁻¹ chromium(VI) and 4% (w/v) NaCl at pH 8. In this study, the molasses (M) medium was selected a suitable medium for the effective chromium bioaccumulation by the mixed cultures. Eleven pure isolates obtained from mixed cultures and some of them showed high bioaccumulation in the M media containing about 100 mg l⁻¹ chromium(VI) and 4% NaCl. The strain 8 (99.3%) and 10 (99.1%) were able to bioaccumulate more efficient than the mixed culture (98.9%) in this media. But the highest specific Cr uptake was obtained by the mixed cultures followed by strain 8 and 10 with 56.71, 33.14 and 21.7 mg g⁻¹, respectively. Bioaccumulation of chromium(VI) ions by the strain 8 growing in the media with chromium(VI) and NaCl was studied in a batch system as a function of initial chromium(VI) (86.6–547.6 mg l⁻¹) and NaCl (0, 2, 4, 6% w/v) concentrations. During all the experiments, the uptake yield of the strain 8 was highly affected from NaCl concentrations in the medium at high initial chromium(VI) concentrations. But at low chromium(VI) concentration, strain 8 was not affected from NaCl concentrations in the medium. The maximum uptake yield were obtained in the M media with 2% NaCl as 98.8% for 110.0 mg l⁻¹, 98.6% for 217.1 mg l⁻¹, 98.6% for 381.7 mg l⁻¹ and 98.2% for 547.6 mg l⁻¹ initial chromium(VI) concentrations. The strain 8 tolerated a 6% (w/v) NaCl concentration was able to bioaccumulate more than 95% of the applied chromium(VI) at the 97.6–224.4 mg l⁻¹ initial chromium(VI) concentrations. The results presented in this paper was shown that these pure and mixed cultures might be of use for the bioaccumulation of chromium(VI) from saline wastewater.     

淡水生态系统服务及其评价指标体系的探讨

对淡水生态系统的重要性及生态系统服务的内涵进行了阐述,指出了当前淡水生态系统服务研究的不足;认为淡水生态系统服务的正常发挥离不开一个健康的生态系统,但少有将两者结合的综合研究,而这样的研究又是必要的。水资源应明确包括水量、水质、水能和水生生物四大要素,以此为基础,对淡水生态系统服务及其评价指标体系进行了论述,并简要介绍其评价方法。文章还对国内相关研究的思路及其技术路线进行了探讨。     

Seasonal habitat use of three predatory fishes in a freshwater ecosystem

Hydrobiologia - To understand the spatiotemporal overlap in the habitat use of sympatric predators, we studied longitudinal activity and reservoir section and depth use of pike (Esox lucius),...     

Toxicological investigations in an artificial ecosystem. A progress report on copper toxicity towards algae and daphniae

Summary 1. It is suggested that the toxicological investigation of marine pollution should aim at studying, in long-term experiments, transport and accumulation in food chains and the influence of secondary stress on these phenomena.2. A laboratory set-up is described with algae, micro-crustaceans and fishes as an artificial food chain kept in continuous-flow systems.3. Preliminary results with copper as the toxic agent are given withChlorella pyrenoidosa andDaphnia magna as the experimental organisms.4. It is shown that in toxicity experiments assessed by mortality and generation size, continuous-flow tests are more discriminating and sensitive towardsD. magna than static tests. Reproduction is the more sensitive measure. A concentration of 56 p.p.b. copper is limiting for the development of daphniae.5. A concentration of about 1000 p.p.b. copper is limiting for the development ofC. pyrenoidosa. Copper is accumulated in its cells about 4000 to 5000 x.6. If fed with algae cultured in copper-containing media, it is found thatD. magna is inhibited at concentrations of 560 p.p.b. copper in the algal medium. It is concluded that poisoning by way of food in this case appears to be less efficient than poisoning directly by way of dissolved copper in the medium.7. Provisional calculations, taking into account the rate of feeding, suggest that the actual amount of copper becoming available to the daphniae by way of food is slightly higher than that by direct absorption from the medium.

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Toxikologische Untersuchungen in einem künstlichen Ökosystem. Ein Fortschrittsbericht über die Giftigkeit von Kupfer gegenüber Algen und Daphnien

Kurzfassung Eine toxikologische Forschungsarbeit über Probleme der Meerwasserverschmutzung sollte langfristige Experimente anstellen, die sich mindestens über eine Generation der Testorganismen erstrecken, sowie Transport und Anhäufung von toxischen Stoffen möglichst bei den Species untersuchen, die zusammen eine Nahrungskette bilden. Erwünscht wäre auch die Feststellung der Auswirkung zusätzlicher Belastungen (zum Beispiel Hunger, Hitze, Radioaktivität, Säure oder Basen, Mangel an O₂). Dieser Versuchsbericht beschreibt die Einrichtung eines Labortestsystems, mit dem die beiden erstgenannten Ziele angestrebt bzw. verwirklicht werden. Für die Dauerflußexperimente wurde eine künstliche Nahrungskette geschaffen, die aus einzelligen Algen, kleinsten Schalentieren und Fischen bestand, so daß jede Gruppe in das Experiment eingeschaltet wurde. Einige Ergebnisse werden berichtet. In einem Vergleich von Experimenten mit stehendem Wasser, zwischendurch erneuertem Wasser und von Kulturen im Durchfluß mitDaphnia magna wird gezeigt, daß Versuche unter Dauerfluß ein besseres und empfindlicheres Verfahren darstellen im Vergleich zu den beiden anderen Verfahren. Als Anhaltspunkte für die Beurteilung der Ergebnisse werden Sterblichkeit und Vermehrungskapazität zugrunde gelegt. Gerade letztere unterliegt am stärksten der Giftwirkung. Die verwendete AlgeChlorella pyrenoidosa speicherte in ihren Zellen erhebliche Kupfermengen. BeiDaphnia magna war die Konzentration, welche Wachstum verhinderte, etwa 56 p. p. b. Dagegen vertrugChlorella pyrenoidosa Konzentrationen bis 1000 p. p. b. WennDaphnia magna mit Algen gefüttert wurden, die in kupferhaltigen Medien gewesen waren, so starben sie nur, wenn die Medien 560 p. p. b. enthielten. Es scheint also, daß — trotz der Akkumulation von Kupfer in diesen Algen — eine Vergiftung durch Nahrung weniger wirksam ist als die direkte Vergiftung durch Kupfer im Medium. Die Futtermenge muß gleichfalls berücksichtigt werden. Provisorische Kalkulationen zeigen, daß die in der einzelnenDaphnia nachweisbare Kupfermenge beim Futterexperiment etwas höher ist.

     

Structure and temporal variation of trematode and gastropod communities in a freshwater ecosystem.

The infro- and component community dynamics of digenetic trematodes in a freshwater gastropod community were examined over a 33-month period. The gastropod and trematode communities were composed of 17 and 10 species respectively. A total of 9,831 snails was collected; among them, 192 belonging to 14 species were infected by larval trematodes. The size of infected snails was significantly greater than that of healthy ones, and the increase of prevalence with size/age was interpreted as related to the increased probability of ultimately becoming parasitized. The trematode community was rich in allogenic species, but the most frequent trematode (cercariaeum) was autogenic and generalist (a range of 12 snail host species). There was a significantly positive relationship between the frequency of trematode species in the community and the number of first intermediate host species. A great temporal heterogeneity occurred in the prevalence of the snails, mainly attributed to the great temporal fluctuations of snail host populations and the variability of freshwater ecological conditions. The data on the occurrence of larval trematodes in 14 host species over the 33-month study allowed indicate a significant negative correlation between the abundance of gastropods and the prevalence of trematodes.     

Faunal structure of Japanese freshwater fishes and its artificial disturbance

The hierarchical structure of areas of endemicity of freshwater fishes in the Japanese Archipelago was analyzed using parsimony analysis of endemicity (PAE) and its modification. Supporting the results of previous studies, the present analysis, which includes species, subspecies, intraspecific monophyletic lineages, and/or hypothetical ancestors, revealed the uniqueness of the local ichthyofauna in northeastern Hokkaido, large changes in ichthyofauna across the Fossa Magna region, central Honshu, and some additional new patterns. A split network analysis was used to represent the complex relationships among local faunas in the archipelago and also in East Asian regions. Artificially disturbed fish faunas have recently lost part of their original endemic areas, producing a remarkable ??homogenization?? among local faunas (+9.0% in Jaccard??s similarity coefficient). The majority of this homogenization can be explained by introduction of domestic species (+8.6%), especially from Lake Biwa, the largest lake in Japan.     

Structural phase diagrams of animal communities in assessment of freshwater ecosystem conditions

A phase diagram method, using indices of biological diversity, was applied to describe the dynamics of zooplankton and fish community structure in natural and experimental conditions. The phase diagram is constructed in the coordinates H and dH × dt^–1, where H is the index of diversity of the community. The method reveals zones of steady state of a community and demonstrates community dynamics in undisturbed and disturbed conditions. Analysis of zooplankton dynamics in a fishless pond showed that in the absence of disturbances the community enters a zone of steady state (around dH × dt^–1=0) and stays in it for a long time. Under the action of disturbances (e.g. oxygen depletion for fish, influence of heavy metals for zooplankton) the community leaves the steady state zone. The greater the disturbance, the more the system deviates from steady state.