On the Problem of Assessing the Resistance of Planktonic Community to Adverse Influences

An experimental-analytical method for assessing the vulnerability of aquatic ecosystems under conditions of anthropogenic pollution is considered. Such data are very important for estimating economic damage from accidental environmental pollution and determining the seasons in which industrial activities will be less hazardous in ecological terms. A feasible approach to this problem is based on the study of ecosystem behavior under critical conditions. Phytoplankton, being the main primary producer of organic matter in the aquatic ecosystem, is the key element providing for its stability.__________Translated from Ekologiya, No. 4, 2005, pp. 294–299.Original Russian Text Copyright © 2005 by Domnin, Korsak, Mosharov.     

Ecological and toxicological effects of inorganic nitrogen pollution in aquatic ecosystems: A global assessment

We provide a global assessment, with detailed multi-scale data, of the ecological and toxicological effects generated by inorganic nitrogen pollution in aquatic ecosystems. Our synthesis of the published scientific literature shows three major environmental problems: (1) it can increase the concentration of hydrogen ions in freshwater ecosystems without much acid-neutralizing capacity, resulting in acidification of those systems; (2) it can stimulate or enhance the development, maintenance and proliferation of primary producers, resulting in eutrophication of aquatic ecosystems; (3) it can reach toxic levels that impair the ability of aquatic animals to survive, grow and reproduce. Inorganic nitrogen pollution of ground and surface waters can also induce adverse effects on human health and economy. Because reductions in SO2 emissions have reduced the atmospheric deposition of H2SO4 across large portions of North America and Europe, while emissions of NOx have gone unchecked, HNO3 is now playing an increasing role in the acidification of freshwater ecosystems. This acidification process has caused several adverse effects on primary and secondary producers, with significant biotic impoverishments, particularly concerning invertebrates and fishes, in many atmospherically acidified lakes and streams. The cultural eutrophication of freshwater, estuarine, and coastal marine ecosystems can cause ecological and toxicological effects that are either directly or indirectly related to the proliferation of primary producers. Extensive kills of both invertebrates and fishes are probably the most dramatic manifestation of hypoxia (or anoxia) in eutrophic and hypereutrophic aquatic ecosystems with low water turnover rates. The decline in dissolved oxygen concentrations can also promote the formation of reduced compounds, such as hydrogen sulphide, resulting in higher adverse (toxic) effects on aquatic animals. Additionally, the occurrence of toxic algae can significantly contribute to the extensive kills of aquatic animals. Cyanobacteria, dinoflagellates and diatoms appear to be major responsible that may be stimulated by inorganic nitrogen pollution. Among the different inorganic nitrogenous compounds (NH4+, NH3, NO2-, HNO2NO3-) that aquatic animals can take up directly from the ambient water, unionized ammonia is the most toxic, while ammonium and nitrate ions are the least toxic. In general, seawater animals seem to be more tolerant to the toxicity of inorganic nitrogenous compounds than freshwater animals, probably because of the ameliorating effect of water salinity (sodium, chloride, calcium and other ions) on the tolerance of aquatic animals. Ingested nitrites and nitrates from polluted drinking waters can induce methemoglobinemia in humans, particularly in young infants, by blocking the oxygen-carrying capacity of hemoglobin. Ingested nitrites and nitrates also have a potential role in developing cancers of the digestive tract through their contribution to the formation of nitrosamines. In addition, some scientific evidences suggest that ingested nitrites and nitrates might result in mutagenicity, teratogenicity and birth defects, contribute to the risks of non-Hodgkin's lymphoma and bladder and ovarian cancers, play a role in the etiology of insulin-dependent diabetes mellitus and in the development of thyroid hypertrophy, or cause spontaneous abortions and respiratory tract infections. Indirect health hazards can occur as a consequence of algal toxins, causing nausea, vomiting, diarrhoea, pneumonia, gastroenteritis, hepatoenteritis, muscular cramps, and several poisoning syndromes (paralytic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning). Other indirect health hazards can also come from the potential relationship between inorganic nitrogen pollution and human infectious diseases (malaria, cholera). Human sickness and death, extensive kills of aquatic animals, and other negative effects, can have elevated costs on human economy, with the recreation and tourism industry suffering the most important economic impacts, at least locally. It is concluded that levels of total nitrogen lower than 0.5-1.0 mg TN/L could prevent aquatic ecosystems (excluding those ecosystems with naturally high N levels) from developing acidification and eutrophication, at least by inorganic nitrogen pollution. Those relatively low TN levels could also protect aquatic animals against the toxicity of inorganic nitrogenous compounds since, in the absence of eutrophication, surface waters usually present relatively high concentrations of dissolved oxygen, most inorganic reactive nitrogen being in the form of nitrate. Additionally, human health and economy would be safer from the adverse effects of inorganic nitrogen pollution.     

Ecotoxicological aspects of the tolerance of hydrobionts to acidification of the aquatic environment in the Taiga natural climatic zone

Experimental ecotoxicological studies on the norm of reaction to anthropogenic acidification were performed with representative hydrobionts from aquatic ecosystems of the northern taiga zone. Interspecific, interpopulation, and age-related differences in tolerance to acidity and the significant dependence of this parameter on water pH in natural habitats of corresponding populations were revealed.     

Contamination of fish by organochlorine pesticide residues in the Ouémé River catchment in the Republic of Bénin

In the Republic of Bénin, aquatic ecosystems are subject to poisoning risks due to the inappropriate use of pesticides, such as washing of empty bottles in rivers and using pesticides to catch fish. In some areas, cotton fields are located near riverbanks, increasing the probability of pesticide emission to the river. To assess contamination levels in the Ouémé River catchment area, different fish species were collected from different geographical areas along the river. DDT, its metabolites and isomers were the most frequently identified pesticides in fish flesh, alpha-endosulfan, beta-endosulfan, dieldrin, telodrin, lindane and octachlorostyrene were also detected. Concentrations of pesticide residues in fish ranged from 0 to 1364 ng/g lipid. A preliminary risk assessment indicated that the daily intake of chlorinated pesticides by people consuming fish from the Ouémé River still is rather low and does not present an immediate risk.     

The impact of bacterial larvicidal agent and larvivorous fish on the preimaginal phases of bloodsucking mosquitoes in aquatic ecosystems of Southern Western Siberia

It has been shown that ecological prerequisites for the spread of bloodsucking mosquitoes from different aquatic ecosystems in the south of Western Siberia may be controlled by reducing the density of larval hemipopulations. The bacterial agent Bactiñide is most efficient in open water systems. In ecosystems overgrown with herb-shrub vegetation, an integrated approach should be used, which involves both stocking with belica (Leucaspius delineatus) and application of Bacticide. The development of larvivorous fish in the permanent water systems of the Karasuk-Burlinsk region and Teletskoye Lake basin contributes to elimination of mosquito larvae and, thus, to the improvement of natural environment.     

Role of the Forest Entomofauna in Successional Processes

Participation of the entomofauna in the succession of forest biogeocenoses is analyzed. In stable ecosystems, insects serve as a mechanism providing for long-term ecological stability. In unstable ecosystems, their activities are essentially negative and cause ecosystem degradation.__________Translated from Ekologiya, No. 3, 2005, pp. 227–230.Original Russian Text Copyright © 2005 by Yanovskii.     

Monitoring of environmental heavy metals in fish from Nasser Lake

Lake ecosystems are, in particular, vulnerable to heavy metal pollution. Tilapia nilotica is one of the aquatic organisms affected by heavy metals. Therefore, heavy metals Co, Cr, Cu, Fe, Mn, Ni, Sr and Zn were determined in different tissues of T. nilotica (ages 1, 1.5, 2, 2.5 and 3 years), which include the muscle, gill, stomach, intestine, liver, vertebral column and scales, to assess the fish pollution with heavy metals. In addition, the study was extended to determine these elements in the aquatic plant (Najas armeta), sediment and water of Khor E1-Ramel in Nasser Lake (Egypt). The study showed that of all the fish parts, fish liver accumulated the highest levels of Cu and Zn. Manganese presented in the intestine and stomach in the highest concentration. Scales exhibited the highest levels of Co, Cr, Ni and Sr, while the gill and vertebral column contains the lowest level of the studied elements. Heavy metals in different parts of T. nilotica differ with the fish growth and extraction rate of these elements from sediment, aquatic plant and lake water. Heavy metals under study in the edible parts of the investigated fish were in the safety permissible levels for human uses.     

Mitigation of illegal fishing activities: enhancing compliance with fisheries regulation in Lake Victoria (Kenya)

Overexploitation of living resources severely affects aquatic ecosystems and is among the most serious environmental issues worldwide. Lake Victoria, the second largest fresh water lake in the world, provides food and jobs to almost 30 million people in three African countries and is nowadays facing significant decrease in fish stock due to its unsustainable use. To analyse reasons behind the illegal fishing activities in the Kenyan part of the lake, the survey programme was designed based on a rational choice framework, and data analysis on compliance with fisheries regulatory law was carried out. Selection of explanatory variables to be considered was guided by the “Table of 11”, which is a tool elaborated for the Netherlands’ Ministry of Justice to analyse the regulated community’s behaviour and motivations. Key findings of the study show that existing economic environment and weak enforcement contribute to the low compliance with the fisheries regulations and lead to further degradation of the lake ecosystem.     

Understanding the dynamics of heavy metals in a freshwater ecosystem through their toxicity and bioavailability assay

The current study investigates on correlating the heavy metal contamination, its distribution, and the human health risk associated with all three components of an aquatic ecosystem. For this purpose, water, sediment, and fish samples (three species, notably Notopterus notopterus, Clarias batrachus, and Channa striata) from Deepor Beel were considered, and their heavy metal contamination and distribution were determined. The corresponding health risks were then evaluated for six different heavy metals; Cr, Cd, Fe, Mn, Cu, and Pb. Pb and Mn were found to significantly impact the non-carcinogenic human health risks for the water column. Simultaneously, Cd was considered to possess the highest potential for both carcinogenic and non-carcinogenic health effects in the sediment column. Cd also played a critical role in the fish samples' bioaccumulation factor, with the liver showing the maximum bioaccumulation potential. Furthermore, children were found to have considerably higher effects (both carcinogenic and non-carcinogenic) than adults. Finally, the sediment column was found to substantially contribute to the bioaccumulation factor in the fish biota, compared to the water column. The results of this investigation will thus prove consequential in designing, monitoring and restoring aquatic ecosystems.

     

Chattanooga shale exploitation and the aquatic environment: The critical issues

Early identification of the critical environmental issues arising from new energy technologies is needed to ensure adequate consideration of these issues in all phases of research and development. This study examines the potential hazards to aquatic ecosystems from large-scale exploitation (190,000 Mg/day) of the Chattanooga Shale Formation, an immense reserve of oil shale and uranium in Kentucky, Tennessee, and Alabama. Using existing data on regional ecology, hydrology, mining operations, and raw and spent shale chemistry, we identified two major, related environmental issues: (1) the potential for extensive adverse effects on aquatic communities through degradation of water quality and habitat; and (2) the potential conflict between the requirements for shale exploitation, and the habitat and water quality needs of threatened or endangered species. Specific hazards to aquatic ecosystems include erosion, sedimentation, acid mine drainage, raw and spent shale leachates, and surface disposal of immense quantities of solid wastes. Twelve of 19 federally designated, threatened or endangered fish and mollusks in the shale-bearing region were identified as known or recent inhabitants of the counties believed to be most favorable for the exploitation of shale. Of these, five species occur as single populations or are limited to a single river system. The potential for adverse effects on these species is greatest in the counties near the Tennessee-Alabama state line. Future research needs include physical, chemical, and toxicological characterizations of shale leachates and studies of the transport and fate of leachable contaminants. Such research can provide the guidance necessary to minimize impacts on aquatic communities resulting from extraction, retorting, and disposal of shale.     

Variability of the Integrated Biochemical Index in Fish Exposed to Technogenic Water of Mining and Ore-Processing Works

The hazard presented to aquatic animals by technogenic waters from mining and ore processing works, with an abnormally high potassium content and alkaline pH, was studied in experiments with fish using the integrated biochemical index (IBI) allowing an aggregate estimation of changes in the animal organism. The results showed that the IBI value directly depends on the extent of technogenic pollution, as well as on the species and age of fish.     

Occurrence,fate and ecological risk of five typical azole fungicides as therapeutic and personal care products in the environment: A review

Azole fungicides are widely used to treat fungal infection in human. After application, these chemicals may reach to the receiving environment via direct or indirect discharge of wastewaters, thus posing potential risks to non-target organisms. We aimed to review the occurrence, fate and toxicological effects of some representative household azole fungicides in the environment. Azole fungicides were widely detected in surface water and sediment of the aquatic environment due to their incomplete removal in wastewater treatment plants. These chemicals are found resistant to microbial degradation, but can undergo photolysis under UV irradiation. Due to different physiochemical properties, azole fungicides showed different environmental behaviors. The residues of azole fungicides could cause toxic effects on aquatic organisms such as algae and fish. The reported effects include regulation changes in expression of cytochrome P450-related genes and alteration in CYP450-regulated steroidogenesis causing endocrine disruption in fish. Further studies are essential to investigate the removal of azole fungicides by advanced treatment technologies, environmental fate such as natural photolysis, and toxic pathways in aquatic organisms.     

水文连通性对湖泊生态环境影响的研究进展

水文连通性对湖泊水资源调节、水质净化和生态安全等具有重要作用，但同时也可能带来潜在风险。因而厘清水文连通性对其生态环境的影响规律，对于开展水文连通性修复工作具有重要指导意义。基于广泛的文献调研，介绍了水文连通性的定义与内涵，分别综述了水文连通性对湖泊水文水动力、水质、水生态系统影响的研究进展。在此基础上，总结归纳了水文连通性通过改变水文水动力过程影响生态系统的路径：一是直接改变生境面积、植被格局和生物迁移繁殖特征，二是通过改变水质和沉积物特征而作用于生物的生长发育及其体内污染物累积转化过程。最后，对水文连通性变化的生态环境效应研究进行了展望：(1)加强对垂向连通性的研究以及拓展不同维度连通性耦合转化研究；(2）借助水动力-水质-水生态耦合模型研究水文连通性变化下的生态环境效应；(3）开展水文连通性的生态环境风险研究，并基于生态环境效益和社会经济效益权衡确定适宜的水文连通性。     

Application of the ERICA Assessment Tool to freshwater biota in Finland

In recent years there has been growing international interest in the assessment of doses and risks from ionising contaminants to biota. In this study the ERICA Tool, developed within the EC 6th Framework Programme, was applied to estimate incremental dose rates to biota in freshwater ecosystems in Finland mainly resulting from exposure to the Chernobyl-derived radionuclides ¹³⁷Cs, ¹³⁴Cs and ⁹⁰Sr. Data sets consisting of measured activity concentrations in fish, aquatic plants, lake water and sediment for three selected lakes located in a region with high ¹³⁷Cs deposition were applied in the assessment. The dose rates to most species studied were clearly below the screening level of 10 μGy h⁻¹, indicating no significant impact of the Chernobyl fallout on these species. However, the possibility of higher dose rates to certain species living on or in the bottom sediment cannot be excluded based on this assessment.     

Environmental health impacts of feeding crops to farmed fish

Half of the seafood consumed globally now comes from aquaculture, or farmed seafood. Aquaculture therefore plays an increasingly important role in the global food system, the environment, and human health. Traditionally, aquaculture feed has contained high levels of wild fish, which is unsustainable for ocean ecosystems as demand grows. The aquaculture industry is shifting to crop-based feed ingredients, such as soy, to replace wild fish as a feed source and allow for continued industry growth. This shift fundamentally links seafood production to terrestrial agriculture, and multidisciplinary research is needed to understand the ecological and environmental health implications. We provide basic estimates of the agricultural resource use associated with producing the top five crops used in commercial aquaculture feed. Aquaculture's environmental footprint may now include nutrient and pesticide runoff from industrial crop production, and depending on where and how feed crops are produced, could be indirectly linked to associated negative health outcomes. We summarize key environmental health research on health effects associated with exposure to air, water, and soil contaminated by industrial crop production. Our review also finds that changes in the nutritional content of farmed seafood products due to altered feed composition could impact human nutrition. Based on our literature reviews and estimates of resource use, we present a conceptual framework describing the potential links between increasing use of crop-based ingredients in aquaculture and human health. Additional data and geographic sourcing information for crop-based ingredients are needed to fully assess the environmental health implications of this trend. This is especially critical in the context of a food system that is using both aquatic and terrestrial resources at unsustainable rates.     

Effects of environmental factors on low-molecular-weight peptides of fishes: a review

The present state of knowledge of the influence of heavy metals and some other environmental factors on fish metallothioneins, low-molecular-weight tissue polypeptides, is considered. The ecological-biochemical role of these polypeptides and their involvement in the development of adaptive responses of organs to heavy metal accumulation are demonstrated.Translated from Ekologiya, No. 1, 2005, pp. 48–54.Original Russian Text Copyright © 2005 by Smirnov, Sukhovskaya, Nemova.     

基于层次分析法的城市河流生态修复评估

城市的发展改变了许多河流的自然水文环境，并导致河流生态系统中水质、物理生境和生物完整性下降。评估受损河流水体修复的效果，需要结合物理、化学的参数，以及对生物结构、多样性和过程的影响。构建了包含河流水力、水质、水生生物、河岸带及物理结构5个方面15个指标的城市河流生态修复评估指标体系，运用群组决策的层次分析法(AHP)，确定了各指标的权重，重要性排序前5位依次为：水质污染指数、鱼类IBI、水源补给量、藻类多样性、透明度。并以我国南方城市岐江河整治修复状况为例进行综合评价，结果表明,河流生态系统修复评估结果为可以接受，体现了河流整治工程使河流水质、生态的状况有所改善，但河流生态系统恢复需要较长的周期，修复初期生态系统仍处于受损状态。〖     

Parameters of Ecological Space and Floristic Diversity of Forest Formations in the Northeast of European Russia

The results of studies on transformations of the floristic diversity of forest ecosystems under the effect of human activity in the southern and middle taiga subzones of the Komi Republic are reviewed. It is shown that the change of dominants in the tree layer leads to the formation of specific biotopes and, as a consequence, to changes in floristic complexes and the cenotic roles of species in the lower layers of forest communities. In the study region, the -diversity of forest communities is determined mainly by two environmental factors: soil fertility and acidity. The factor of illumination has only a slight effect on the -diversity of taiga forests, which is especially clear in the group of deciduous forest formations.__________Translated from Ekologiya, No. 3, 2005, pp. 180–185.Original Russian Text Copyright © 2005 by Degteva.     

Physiological mechanisms of degradation of fish populations in acidified water bodies

Disturbances in fish that result from water acidification and related factors are analyzed in the context of generalizations based on the results of experimental and field studies. It is shown that low pH, monomeric aluminum, and other metal ions have an adverse effect on physiological processes in fish and are a major cause of their death in acidified lakes and rivers. The vulnerability of fish to low water pH at different stages of their life cycle and mechanisms of delayed mortality are discussed.