Molluscs and biodegradable pollution in rivers: proposal for a scale of sensitivity of species

Malacological surveys and physico-shemical water analysis have been carried out at one hundred and sixty stations in France, distributed accross five major catchment areas. The relationships between six of the variables: dissolved oxygen, BOD₅, ammonia nitrogen, nitrites, Kjeldhal nitrogen and orthophosphates can be considered as indicators of biodegradable pollution and the populations of forty eight species of molluscs have been studied using correspondence analysis. A scale of sensitivity of these to this type of pollution is presented.     

Ecological studies on reovirus pollution of rivers in Toyama Prefecture

Reoviruses (reos) were isolated from river water in various areas of Toyama Prefecture. The frequency of reo isolation was higher in the river water, the basin of which has a larger human population. The degree of river contamination with reo paralleled that with the Escherichia coli group of organisms, and reos were frequently isolated from sewage, too. The high antibody-positive (greater than or equal to 1:8 or greater than or equal to 1:10) rates against reos in humans and other animals tested (swine, cattle, and field rodents) indicated their wide-spread infection with reos. These results suggested that the major source of reos present in the river water may be the excretion by humans and other animals, especially the former. Survival experiments in which reos were added into the filtered or centrifuged river water and kept at various temperatures, revealed that reos survived for more than 3 years at 5 C. In the field experiment where reos suspended in cellophane tubes were kept in an agricultural water stream in winter (water temperatures below 10 C), they survived for 6 months until the water temperature rose above 20 C in summer.     

Viral pollution of the rivers in Toyama City

Viral pollution of the river water in Toyama City was surveyed during the two-year period from July 1979 to July 1981, and the ecology of viruses in the river water is discussed. Virus isolation from the river water samples, or from the water squeezed from cotton pads that were immersed in the stream for 3 days, was carried out by the "filter adsorption/elution" method. River waters were found to be contaminated with various species of enteric viruses, that is, poliovirus, echovirus, coxsackievirus, adenovirus, and reovirus. Poliovirus was isolated during the period immediately after the oral administration of polio vaccine, and coxsackie B virus was frequently isolated all year around. The enterovirus concentration in the river water was significantly high with a maximum of five plaque-forming units of coxsackie B2 virus per 250 ml. The species and type distribution of enteroviruses isolated from the river water coincided well with that of viruses isolated from inhabitants of Toyama Prefecture, with the exception of reovirus which was the largest population of virus species in the river water.     

Process and formulation variables in the preparation of injectable and biodegradable magnetic microspheres

The aim of this study was to prepare biodegradable sustained release magnetite microspheres sized between 1 to 2 μm. The microspheres with or without magnetic materials were prepared by a W/O/W double emulsion solvent evaporation technique using poly(lactide-co-glycolide) (PLGA) as the biodegradable matrix forming polymer. Effects of manufacturing and formulation variables on particle size were investigated with non-magnetic microspheres. Microsphere size could be controlled by modification of homogenization speed, PLGA concentration in the oil phase, oil phase volume, solvent composition, and polyvinyl alcohol (PVA) concentration in the outer water phase. Most influential were the agitation velocity and all parameters that influence the kinematic viscosity of oil and outer water phase, specifically the type and concentration of the oil phase. The magnetic component yielding homogeneous magnetic microspheres consisted of magnetite nanoparticles of 8 nm diameter stabilized with a polyethylene glycole/polyacrylic acid (PEG/PAA) coating and a saturation magnetization of 47.8 emu/g. Non-magnetic and magnetic microspheres had very similar size, morphology, and size distribution, as shown by scanning electron microscopy. The optimized conditions yielded microspheres with 13.7 weight% of magnetite and an average diameter of 1.37 μm. Such biodegradable magnetic microspheres seem appropriate for vascular administration followed by magnetic drug targeting.     

Concentration and annual accumulation values of heavy metals in lake sediments: Their significance in studies of the history of heavy metal pollution

The first part of the paper discusses the significance of using either concentration or accumulation values for expressing the results of investigations of lake sediment cores aimed at studying the history of heavy metal pollution. Neither the values for heavy metal concentration in the lake sediment, whether expressed per gram dry sediment or per gram soluble (organic) sediment, nor the values for their total annual accumulation per unit area of the lake bottom, can, on their own, provide an accurate picture of past pollution conditions, but when considered in combination they render a fairly reliable and detailed interpretation. The second part of the paper deals with Pb, Cd and Hg analyses of cores of varved sediments from several lakes in N. Sweden. Pb and Cd pollution increased during the second half of the 19th century. In most lakes, Hg pollution seems first to have started during the 20th century. Marked increases in both concentration and accumulation of heavy metals took place during the 20th century. For recent decades, the estimated accumulation rates of heavy metals from anthropogenic sources are: Pb 0.5–1.5 µg cm^–2 yr^–1, Cd 15–30 ng cm^–2 yr^–1 and Hg 1–2 ng cm^–2 yr^–1, Higher values were recorded in lakes affected by local emissions.     

Extraction and physico-chemical characterization of a versatile biodegradable polysaccharide obtained from green algae

During the last years, considerable attention has been given to different marine organisms, like algae, as potential sources of valuable materials. The continuous demand for novel materials and technologies is high and research on the underexploited marine green algae, including its polysaccharidic part—ulvan, has increased accordingly. In this research work, a novel method for extraction of ulvan from green algae is proposed and demonstrated successfully. Different characterization techniques were employed to characterize the isolated algal polysaccharide, namely, on what concerns its thermal trace and crystallinity. Upon heating, ulvan behaves as a non-meltable polysaccharide that is thermally stable before degradation at 220 °C. Ulvan is semi-crystalline in nature and possesses high hygroscopic features, as revealed in this research work. Due to its properties, ulvan can be considered, pure or modified, as a versatile biodegradable polymer for different applications, including tissue engineering and regenerative medicine.     

Comparative studies of skeletal soluble matrices from some Scleractinian corals and Molluscs

The soluble organic matrices extracted from aragonitic skeletons of five Scleractinia and two Molluscs were analyzed using FTIR spectrometry, HPLC and 2-D gel electrophoresis. All these methods show that scleractinian and molluscan matrices are different. Both matrices are acidic with poorly separated molecular weights. The scleractinian matrices are highly glycosylated, whereas the molluscan matrices are not as shown by stains in 2D-electrophoresis. These results were in accordance with earlier data: high S contents in Scleractinia skeletons and low S contents in Mollusca shells. These results confirm the control of the morphology and the chemical composition of aragonite biocrystals in various taxa.     

Using diatom life-forms and ecological guilds to assess organic pollution and trophic level in rivers: a case study of rivers in south-eastern France

The European Union’s Water Framework Directive has set a target of achieving good ecological status for all aquatic environments in Europe by 2015. In order to determine the quality of aquatic environments, biological indicators such as diatoms are often used. However, biotic diatom indices can be difficult and time consuming to use because of complexity of species determination. We investigated whether the biological traits of diatoms in rivers (life-forms, size classes and ecological guilds) could be used to assess organic pollution and trophic level. We worked on a data set comprising 315 diatom species, determined at 328 river stations of south-east France and a variety of parameters. The abundances of some biological traits differed significantly between the different organic pollution and trophic levels, particularly stalked diatoms, and the motile and low-profile guilds.     

Assessing the ecological values of rivers: an application of a multi-criteria approach to rivers of the South Coast Region,Western Australia

There is a growing awareness that in the light of increased threats, Australia’s freshwater ecosystems of highest value need to be protected. This implies that a consistent and comprehensive system for the classification of freshwater systems in terms of their ecological values is required for conservation planning. Despite earlier steps taken to develop appropriate methodologies for prioritising Australian waterways for protection, there is, as yet, no nationally agreed method for prioritising waterways in Australia based on their ecological values. Using the core criteria of naturalness, representativeness, diversity, rarity and special features, this paper describes the development of a framework of criteria, indicators and measures for the identification of high conservation value aquatic ecosystems, and trials this system by undertaking a comparative assessment of the ecological values of river systems in the South Coast region, Western Australia. A total of 33 river systems located in two aquatic bioregions were successfully ranked according to their ecological value, confirming that the development and implementation of a relatively simple system for assessing ecological values of Australian rivers shows promise, and that core criteria identified previously in the literature provide a good starting point for assessing ecological values of Australian aquatic ecosystems.     

Lack of oxygen and low pH as limiting factors for Gammarus in Hessian brooks and rivers

During two decades (1968–1988) the occurrence of Gammarus was studied in Hessian running waters draining some 7700 km² of the Fulda-Eder-basin and two adjacent areas. About 1530 sites were sampled, most of them in 1968, 1978, 1981/82 and 1985, which made comparisons possible, primarily with respect to space, but partly also to time. After consideration of the relief of the landscape, geological conditions, and water-quality in the neighbourhood of human settlements, lack of oxygen (due to organic pollution) and low pH (souring) can be recognized as the most important factors which influence and alter natural distribution patterns of Gammarus fossarum, G. pulex and G. roeseli. Both vanishing and recovering populations were observed in the course of twenty years.     

Copper and zinc in Elodea canadensis from rivers with various pollution levels

The anthropogenic impact of xenobiotics contributes to environmental risk for the aquatic environment and thus, must be controlled. Elodea canadensis, a cosmopolitan aquatic macrophyte with an important role in the ecology of many littoral zones, may provide an integrated record of pollution. Therefore, it was interesting to investigate the accumulation of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in this species and in water and bottom sediments collected from rivers with various levels of contamination. Of these rivers one control and one polluted was selected for the collection of E. canadensis for an experiment to compare the ability of this species to accumulate Cu and Zn. These elements were supplemented at concentrations (mg L⁻¹) of 0.01, 0.02, 0.03, 0.05, 0.08 and 0.14 as CuSO₄·5H₂O, and 0.4, 0.6, 0.9, 1.4, 2.03 and 3.04 as ZnSO₄·7H₂O and in a mixture containing (mg L⁻¹) 0.01Cu + 0.4Zn, 0.02Cu + 0.6Zn, 0.03Cu + 0.9Zn, 0.05Cu + 1.4Zn, 0.08Cu + 2.03Zn and 0.14Cu + 3.04Zn. After the experiment, E. canadensis from the polluted river contained significantly higher Cu and Zn concentrations when applied separately and also significantly higher Cu and Zn concentrations when applied as a mixture compared to the control river. These higher concentrations in E. canadensis from the polluted river were found in all combinations in the experiment. Thus, E. canadensis habituated in polluted sites to the exposure, and long-term influence of elevated metal levels appeared to be better adapted, and it also exhibited a higher increase in biomass than plants from the control river in all the experimental Cu and Zn solutions. Younger leaves of E. canadensis were more resistant to the effects of Cu and Zn than older leaves. Both Cu and Zn negatively affected the cell structure of older leaves, although the influence of Cu on plasma membrane integrity and chloroplast distribution was stronger than that of Zn. The influence of the Cu + Zn mixture on E. canadensis resulted in less pronounced cell disintegration than the influence of Cu added separately.The explanation of differences in the E. canadensis biomass increase and metal concentrations under the binary Cu and Zn impact needs further examination.     

The relationship between alien crustaceans and pollution in Croatian large rivers: implications for biological monitoring

Hydrobiologia - Peracarid crustaceans contribute to the homogenization of macroinvertebrate communities as one of the most important group of aquatic invaders. This study investigated the...     

Development and practical application of limiting values for the phosphate concentration in surface waters in the Netherlands

Summary To counteract eutrophication it is important to possess sufficient information (1) on the relationship between the content of nutrients and the algal biomass, and (2) on the cycling of nutrients in lakes.A comparative study of a large number of surface waters in the Netherlands has demonstrated that it is possible to derive a relationship between the nitrogen and phosphorus concentrations and the upper limit of the chlorophyll concentration, averaged over the summer season.For the authority in charge of water quality it is essential to know how far the phosphorus loading must be reduced to attain the desired phosphate concentration. The results of an extensive study of the nutrient budgets of Lake Wolderwijd-Nuldernauw over the period 1976–1979 demonstrate that in certain cases a relative high phosphate concentration can occur (approx. 0.30 mg/l) in spite of a low external phosphorus loading (approx. 0.7 g P/m² year). Such high concentrations can be explained by the continuous presence of a bloom of blue-green algae and the release of phosphate from the aquatic sediments during the summer. In such lakes it is necessary to take additional measures, such as flushing with water poor in algae and phosphates, or, where necessary, the removal of aquatic sediment rich in phosphate.     

Matrix Proteins in the Outer Shells of Molluscs

The shells of molluscs are composed mainly of calcium carbonate crystals, with small amounts of matrix proteins. For more than 50 years, they have attracted attention for their unique mechanical and biological properties. Only recently, however, have researchers begun to realize that it is the matrix proteins that control the formation of calcium carbonate crystals and play key roles in their extraordinary properties, despite the fact that matrix proteins comprise less than 5% of the shell weight. This article reviews the matrix proteins identified to date from the shells of molluscs, their structural characteristics, and their roles in shell formation. Some suggestions are given for further investigation based on the summary and analysis.     

Introduction to the studies of pollution in the Oslofjord

Summary 1. The Oslofjord penetrates inland over a distance of about 60 nautical miles from the open Skager-Rak to the capital city of Norway. At the town of Drøbak, about 2/3 up the fjord, there are a series of obstacles to a free exchange of water, the main passage being a channel about 300 m wide with a sill depth of 19 m. Inside Drøbak, the fjord consists of two wider basins, Vestfjorden and Bunnefjorden with depths down to 164 and 160 m. The area of the inner fjord is 191 km²; it holds about 9.4×10⁹ m³ of water. The discharge of freshwater is about 800 million m³ per year, polluted by a population of 700 thousand and considerable industry.2. Faunistic studies were made byO. F. Müller in the 18th, M. andG. O Sars in the 19th century, while more extensive hydrobiological studies were initiated byJ. Hjort andH. H. Gran about 1900. They were subsequently extended through participation of the staffs of biological institutes of the University of Oslo, especially from the early thirties, when the importance of the pollution for the biology of the inner fjord had become well documented.3. In 1953 the situation had become so alarming that the authorities of the city of Oslo were warned that the use of the fjord as recipient for the city sewage had detrimental effects which required their attention and that more comprehensive studies were needed. The Norwegian Institute of Water Research (NIVA) was asked to plan and direct the cooperative investigations which have been carried out in the years 1962 to 1965. The Institute of Marine Biology of the University of Oslo and the Geophysical Institute of the University of Bergen participated in these studies.4. This summer the results were reported to the supporting authorities in a general report, edited byK. Baalsrud, Director of NIVA, and in 20 special reports by participating scientists.

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Einführung in die Untersuchungen über die Verunreinigung im Oslofjord

Kurzfassung Der Oslofjord erstreckt sich etwa 100 km in nördlicher Richtung vom Skagerrak bis nach Oslo. Bei Drøbak, etwa auf dem zweiten Drittel des Weges nach Oslo, gibt es eine Reihe von Hindernissen, die einem ungehinderten Austausch der Wassermassen im Fjord entgegenstehen. Der wichtigste Durchlaß ist nur etwa 300 m breit und hat eine Wassertiefe über der Schwelle von 19 m. Hinter Drøbak besteht der Fjord aus zwei Becken, dem Westfjord und dem Bunnefjord, die Tiefen von 164 m beziehungsweise von 160 m aufweisen. Der Fjord hinter Drøbak hat eine Fläche von 191 km²; die Wassermenge beträgt nach Berechnungen 9,4 Milliarden m³. Der jährliche Zufluß an Süßwasser, das durch Abwässer von ca. 700 000 Menschen und einer bedeutenden Industrie verunreinigt wird, beträgt etwa 800 Millionen m³. Studien über die Fauna wurden im 18. Jahrhundert vonO. F. Müller und im 19. Jahrhundert von M. undG. O. Sars vorgenommen. Ausgedehntere Untersuchungen wurden um 1900 vonJ. Hjort undH. H. Gran begonnen. Seit Anfang der dreißiger Jahre sind diese Untersuchungen von den biologischen Instituten der Universität Oslo weitergeführt worden. 1953 wurde die Situation hinsichtlich der Verunreinigung des Fjords alarmierend. Die Behörden der Stadt Oslo wurden davon unterrichtet, daß umfassendere Untersuchungen notwendig seien, um die Folgen, die dadurch entstehen, daß der Fjord als Auffangbecken für die Abwässer der Stadt dient, zu erforschen. Das norwegische Institut für Wasserforschung NIVA (Norsk institutt for vannforskning), wurde gebeten, diese Untersuchungen vorzubereiten und zu leiten. Im Juni 1967 konnte das Institut seinen allgemeinen Bericht sowie 20 Spezialberichte über dieses Forschungsprojekt, das in den Jahren 1962 bis 1965 bearbeitet worden war, vorlegen.

     

长江中下游湖泊软体动物的多样性及分布现状

长江中下游流域是我国淡水贝类多样性最为集中的地区,然而由于人类活动的影响,淡水贝类已成为高度濒危的类群。为有效保护淡水贝类的多样性,我们于2003年6月-2005年5月对长江中下游流域13个水体软体动物的多样性及分布进行了调查。共采集到软体动物69种(中国特有种42种),隶属于腹足类9科14属29种和瓣鳃类5科17属40种。其中,蚌科和田螺科是种类数最多的两个科,分别占总种类数的50.7%和14.5%。不同类型湖泊软体动物种类数的差别较大。通江湖泊所占种类数相对丰富,尤其是适应流水的种类,如河螺属、短沟蜷属及蚌科的种类。大型通江湖泊鄱阳湖和洞庭湖软体动物的种类数和特有种数分别66种和40种,分别占总种类数和总特有种数的95.7%和95.2%。阻隔水体所占种类数相对较少,种类数为4-19种。与历史资料相比,长江中下游湖泊软体动物的种类数和特有种数均减少50%左右,且多数种类的分布范围也明显缩小。造成贝类资源衰退的可能原因主要是江湖阻隔所引起的整个江湖复合系统栖息地和水文情势的改变,其他的人为活动如过度捕捞、围垦及废污水的过度排放等也可能是其中的重要原因。     

Geomorphology variables predict fish assemblages for forested and endorheic rivers of two continents

Stream fishes are restricted to specific environments with appropriate habitats for feeding and reproduction. Interactions between streams and surrounding landscapes influence the availability and type of fish habitat, nutrient concentrations, suspended solids, and substrate composition. Valley width and gradient are geomorphological variables that influence the frequency and intensity that a stream interacts with the surrounding landscape. For example, in constrained valleys, canyon walls are steeply sloped and valleys are narrow, limiting the movement of water into riparian zones. Wide valleys have long, flat floodplains that are inundated with high discharge. We tested for differences in fish assemblages with geomorphology variation among stream sites. We selected rivers in similar forested and endorheic ecoregion types of the United States and Mongolia. Sites where we collected were defined as geomorphologically unique river segments (i.e., functional process zones; FPZs) using an automated ArcGIS‐based tool. This tool extracts geomorphic variables at the valley and catchment scales and uses them to cluster stream segments based on their similarity. We collected a representative fish sample from replicates of FPZs. Then, we used constrained ordinations to determine whether river geomorphology could predict fish assemblage variation. Our constrained ordination approach using geomorphology to predict fish assemblages resulted in significance using fish taxonomy and traits in several watersheds. The watersheds where constrained ordinations were not successful were next analyzed with unconstrained ordinations to examine patterns among fish taxonomy and traits with geomorphology variables. Common geomorphology variables as predictors for taxonomic fish assemblages were river gradient, valley width, and valley slope. Significant geomorphology predictors of functional traits were valley width‐to‐floor width ratio, elevation, gradient, and channel sinuosity. These results provide evidence that fish assemblages respond similarly and strongly to geomorphic variables on two continents.     

Peripheral Actions of the SCPs in Aplysia and Other Gastropod Molluscs

The SCPs are a family of neuropeptides found in many gastropodspecies. Two SCPs with similar sequences have been characterizedin Aplysia. These peptides are potent modulators of centraland peripheral synapses. They also enhance ongoing contractileactivity in spontaneously active tissues such as heart and gut.Their distribution in central ganglia suggests that their predominantrole is in the regulation of feeding behavior. There is goodevidence that the identified SCP-containing neurons, B1 andB2, provide the major central regulation of gut motility duringfeeding through the release of the SCPs from their terminalsin gut. The SCPs have also been localized to motor neurons thatinnervate buccal muscles which generate biting and swallowingmovements. In many of these neurons, the SCPs have been shownto coexist with conventional transmitters such as ACh, or otherpeptides such as FMRFamide. The SCPs appear to be released alongwith conventional transmitters from these neurons to modulatethe effectiveness of the conventional transmitter. In all cases,the SCPs cause an enhancement of the amplitude of contractionsproduced by motor neuron stimulation. The precise mechanismsunderlying this effect vary from muscle to muscle. All of theeffects of the SCPs are mediated by increased cAMP levels intarget tissue. At many sites of action, serotonin produces actionsthat are qualitatively similar to those of the SCPs. This islikely to involve a convergence at the level of the adenylylcyclase. In addition to these peripheral effects, the SCPs alsohave multiple central effects on feeding and other behaviorsin gastropods.