Aquatic ecotoxicology

Information about the toxicity of heavy metals and organics to aquatic organisms can be obtained from bioassays. These are classified according to the type of response obtained: quantal or continuous, and according to whether individual organisms originate from a single clone or have a tolerance distribution. Basic features of the probit, logit, and Weibull dose-response models for one toxic substance are considered. It is shown that a version of the logit model is complementary to the Monod equation for the growth rate of microorganisms under substrate limitation. Multiple toxicity models can be of the non-interactive or competitive type. The standard water quality criterion for concentration addition is based on the assumption that the toxicants act on similar biological systems, and that the action tolerances for individuals are fully correlated. Pertinent examples of the application of the models for one or several toxic substances are discussed.     

洪泽湖水生植被

本文对洪泽湖水生植被的种群组成、植被类型、演变动态及生物量进行了调查研究。洪泽湖水生植被面积为550km~2,占全湖总面积34.44％,年生产量约211×10~4t(湿重),即相当于4.64×10~(15)J(能量)。另外,本文还对如何调整洪泽湖植被的组成,引进优良品种,合理开发利用水生植物资源,提出了初步意见。     

Aquatic vegetation of Lake Annecy

Aquatic vegetation (macrophytes) of lake Annecy has been studied in summer 1981 by underwater observation. Cartography of the plants has been achieved and compared with earlier studies. Emergent plants have regressed. Submerged vegetation is dominated by Charophyceae.     

龙感湖水生植被

于１９９３年９月对龙感湖水生植被及环境进行了调查研究。龙感湖有水生植物２６科３８属５０种,依据优势种群划分９个群丛,其分布面积２８３．５ｋｍ＾２,占全湖总面积的８９．７％,植被现有年生产力达２１４７７３０ｔ,对渔业生产和生态环境具有十分重要的意义。建议对该湖植被应合理开发利用,如果围网养鱼得到广泛地发展,渔业生产潜力每年可达４１８１．８ｔ。     

Bioindication of Gold by Aquatic Bryophytes

As arsenopyrite is frequently present in auriferous deposits, concentrations of gold were measured in aquatic bryophytes collected from streams in zones of arsenic mineralization in the Polish and Czech Sudety Mountains. Data were compared with analyses of aquatic bryophytes from streams in non As mineralization areas with only background concentrations of Au. The highest contents of Au in bryophytes surpass the background concentration of this element in plants and are found in areas characterized by the presence of arsenopyrites.     

The Production of Hydroxylamine by Aquatic Organisms

In batch tests with Chlorlla pyrenoidosa, Ankistrodesmus falcatus, Coelastrum cambricum and Scenedesmus obliquus it is demonstrated that hydroxylamine as an extracellular product of metabolism is excreted by these algae into water. The hydroxylamine production is proportional to the number of cells and to the physiological state of the algae. A mixed population of aquatic bacteria does not show any hydroxylamine production, the hydroxylamine concentration in the medium of culture of algae being reduced by their presence.     

Aquatic ecotoxicology: Theoretical principles and practical application

Aquatic ecotoxicology is defined as a scientific discipline, studying the properties and behavior of pollutants in aquatic ecosystems, as well as the impact of pollutants on organisms, populations, and communities. The history of evolution and development of this discipline is considered, and its theoretical foundations are formulated. The role of aquatic ecotoxicology in solving practical problems related to the substantiation of the criteria for water quality assessment and standardization of human-induced water contamination is demonstrated.     

Aquatic Heteroptera as indicators for terrestrialisation of floodplain habitats

The distribution of aquatic Heteroptera (Corixidae and Gerromorpha) in three backwater systems of the Austrian Alluvial Forest National Park differing in connectivity to the Danube River was examined at 44 locations between 1999 and 2003. The most common species were Aquarius paludum and Gerris lacustris (Gerridae).Various statistical analyses were used to define the relationship between species occurrence and 15 environmental variables and to test their influences on species distribution. Canonical correspondence analysis suggested that the main environmental gradients were the transitions from water surface richly covered with branches and Lemna and vegetated shoreline, which most species preferred, to open habitats with little shoreline vegetation, which only a few species preferred.This study shows the potential significance of heteropterans as indicator groups for paleopotamic conditions and aquatic habitats with strong terrestrialisation processes.     

Aquatic resources in arid lands: Issues and opportunities

No Abstract.  .     

Aquatic hyphomycetes in hyporheic freshwater habitats of southwest India

The hyporheic zones constitute a major site of storage of organic matter and energy flow in freshwater ecosystems. To complement the studies carried out in North America and Europe, we evaluated the sediment quality and occurrence of aquatic hyphomycetes in coarse particulate organic matter (CPOM; ≥5 mm) and fine particulate matter (FPM; ≤1 mm) in three locations of Kaiga stream and eight locations of Kadra dam of the River Kali in Western Ghats. The pH of sediments of stream and dam was acidic (5.8-6.6) and the average organic carbon of stream sediments was higher than dam sediments (8.6% vs. 3.9%). Among the eight minerals monitored, Fe was highest in all sediments and Ni was below detectable limit in four dam sediments. Spores of aquatic hyphomycetes were directly released from the CPOM fractions of sediments upon bubble chamber incubation, while the FPM fractions produced spores indirectly by colonization of sterile leaf baits followed by bubble chamber incubation. The species richness and diversity in CPOM was higher than FPM in stream as well as dam sediments. The Sorensen's similarity indices between the fungal flora of CPOM in stream (66.7-81.8%) and dam (69.2-88%) locations were generally higher than FPM. The spore output per mg CPOM was between 1215 (dam) and 3384 (stream). The species richness was negatively correlated with Cr (P < 0.01; r = −1.000) of stream sediments, while it was negatively correlated with organic carbon (P < 0.05; r = −0.740) and positively correlated with K (P < 0.05; r = 0.750) of dam sediments. Occurrence and survival of aquatic hyphomycetes in hyporheic habitats of freshwater bodies indicate the importance of such zones as reservoir of fungal inoculum necessary in fundamental functions such as organic matter processing and energy flow. The present study provides baseline data on the sediment quality and fungal composition of stream and dam locations of River Kali of Kaiga region, which will develop as center of industrial activities in future.     

Endocrine Disrupters in the Aquatic Environment: An Overview

Although a relatively new area of environmental research, the field of endocrine disruption has grown very rapidly, and currently many hundreds, perhaps even a few thousand, papers are published annually on the many different aspects covered by the field. As far as endocrine disruption in wildlife is concerned, most attention has been focused on aquatic organisms, for two reasons. Firstly, the aquatic environment receives most of the pollutants intentionally released into the environment, through effluents from wastewater treatment plants, and secondly because many of the best documented examples of endocrine disruption in wildlife are of partially or completely aquatic species. These two reasons are probably not unconnected, of course. Hence, aquatic organisms can receive continuous exposure to endocrine‐disrupting chemicals throughout their lives, albeit usually to low concentrations of these chemicals. Analysis of effluents has identified many of the endocrine‐disrupting chemicals present, and shown that these are both natural and man‐made, and vary greatly in potency. Most attention has been directed to identifying the main estrogenic chemicals, because many of the effects reported in wildlife appear to be a consequence of ‘feminization’ of males. However, chemical analysis of effluents has also demonstrated that chemicals with other types of endocrine activity are present, such as androgens, anti‐androgens, progestagens, etc. The effects (if any, of course) of such chemicals on aquatic organisms are unknown, and largely uninvestigated, presently. Much of the biological research has centred on the effects of estrogenic chemicals, especially to fish. These effects, such as elevated vitellogenin concentrations and intersexuality, have to date been studied almost exclusively at the level of the individual, and hence whether endocrine‐disrupting chemicals cause population‐level consequences is largely unknown (the undeniable effects of TBT on molluscs, leading to local extinctions, being the exception). It is my opinion that rather too much of the recent research has not advanced our understanding of endocrine disruption a great deal, and we are probably not much further forward now than we were five years or so ago. It is surely time to tackle some of the outstanding, unresolved issues, such as the impact of endocrine disruption at the population level, and the issue of how organisms respond when exposed to complex mixtures of endocrine active chemicals. Such research will not be easy, and will require multidisciplinary teams, including people with expertise in areas not yet involved in the field of endocrine disruption, such as mathematical modellers. However, until such research is done, it will not be possible to decide how important an issue endocrine disruption is to wildlife, and how that importance compares to the other factors adversely affecting wildlife, such as habitat loss, climate change, and the introduction of exotic species and novel diseases.