bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abatement of acidification in mining lakes in Germany
Authors: Klapper Helmut , Geller Walter , Schultze Martin 
Published: June 2006

AbstractOpen‐cast lignite mining has exposed formerly anaerobic layers to the air. Pyrite and marcasite are oxidized to sulfuric acid and iron sulfate, which later hydrolyses to iron hydroxide. When the pit is refilled with groundwater, its pH is 2–3. These geogenically acidified mining lakes are brown, with high iron content. Biological conditions differ greatly from those in most natural lakes and resemble those in sulfur‐acidic lakes impaired by acid rain. The usability of these fish‐free lakes is also restricted for recreational purposes.Neutralization with lime is expensive. The iron‐buffered water has a high base buffering capacity stabilizing at pH 2–4. The complex of potential measures for neutralization comprises: the revegetation of the waste heaps, the hydrological regime and coupled transport processes, the selection of suitable filling water and in‐lake technologies. Desulfurication takes place with sulfidic binding of iron and natural neutralization under locally anaerobic conditions in the reclaimed overburden heaps, in the deep water of mining lakes, in macrophyte stands and in the sediments.Anaerobic conditions should be established within the lakes during stratification periods: in the hypolimnion of eutrophic or the monimolimnion of meromictic lakes. Acidic lakes often are not sufficiently productive to achieve deep‐water oxygen depletion. Measures to increase the stability of stratification may be necessary, for example by installation of barriers to establish an environment suitable for biological neutralization. Carbon sources for microbial desulfurication may be added artificially or autochthonically produced by primary producers. Therefore, a controlled eutrophication may be useful in the initial filling stages of acidic mining lakes.
Chenderoh Reservoir, Malaysia: The conservation and wise use of fish biodiversity in a small flow‐through tropical reservoir
Authors: Ali Ahyaudin B. 
Published: June 2006

AbstractChenderoh Reservoir on the Perak River, Malaysia, is a small tropical reservoir. Being a flow‐through reservoir, the water‐level management and retention time of the reservoir are dependent on the water management schemes of the three upper reservoirs. The fish biodiversity in the reservoir is relatively higher than that shown by areas downstream of the reservoir. Most species found in the downstream area are‘r’strategists in contrast to those in the reservoir where‘K’strategist species are more abundant. Biodiversity is higher in the reservoir possibly due to the higher number of niches available through the inundation of the shoreline and the creation of various coves and bays. There is, however, a reduction in biodiversity in the reservoir over time. This reduction could be due to environmental perturbation caused by land‐use activities along the shoreline of the reservoir. Although the fish standing stock is relatively low, small artisanal fisheries exist in the reservoir supporting the local communities. In order to maintain sustainability of the fisheries, the local fishers have been practising community‐based management since the early 1980s and prior to the official enactment of the Perak State Fisheries Riverine Rules. In general, because of the sensitivity of tropical reservoirs to environmental perturbation as well as limited living space created by the existence of a permanent thermocline, tropical reservoirs should be properly managed so as to protect and maintain their biodiversity and sustainability through wise use of the aquatic resources.
The invasive capacity of water chestnut as shown in the management of a natural population in Lago di Candia
Authors: Galanti G. , Esposito A. Topa 
Published: June 2006

AbstractThe growth and production of the annual floating‐leaved water chestnut (Trapa natans) were studied during summer 1993 at three sites at Lago di Candia (Northern Italy). These sites were subjected to different levels of harvesting from 1986 to 1992. Site USD was the unharvested control site; site 30S was harvested in alternate years (1987, 1989 and 1991); site 30D was harvested every year from 1986 onwards (except 1989) and moreover was sown during 1990, 1991 and 1992 with 8, 4 and 4 seeds/m2, respectively. Despite differences in seed density in the sediment, reflecting different harvesting and sowing practices, neither the biomass of water chestnut nor the fruit production were statistically different in the three sites although the production of buds, flowers and fertilized ovaries was higher at site 30D. In this site, where the plant density was four times lower, water chestnut increased the number of rosettes per plant two to fourfold. This productivity increased the population's invasive capacity. In Lago di Candia, water chestnut grows to 3 m in depth and it competes successfully with hornwort (Ceratophyllum demersum) in the littoral zone.
Using generalized additive models for prediction of chlorophyll a in Lake Okeechobee, Florida
Authors: Lamon E. Conrad , Reckhow Kenneth H. , Havens Karl E. 
Published: June 2006

AbstractLong‐term eutrophication data collected by the South Florida Water Management District at eight stations in the pelagic region of Lake Okeechobee since 1980 were combined with those from littoral region stations collected since 1986. These data were supplemented by those collected by the University of Florida in conjunction with the Lake Okeechobee Ecosystem Study. Generalized additive models (GAM) were fit to the chlorophyll a response for each of five previously documented‘ecological zones’, each using the same predictor variables for comparison between zones. Significant nonlinear increasing relationships between log10 TP and log10 chlorophyll a were found for littoral and near littoral regions of the lake, which change to decreasing at certain (high) levels of log10 TP. This change to a decreasing function suggests light limitation associated with high TP levels due to particle resuspension. The error distribution of the GAM compare favourably to those of linear models. The relationship of the chlorophyll a response to the predictors used in the GAM appear similar for littoral and near littoral regions, as they do for north pelagic and central pelagic ecological zones, with intermediate shapes of these functions found in the transition zone between these two groups.
Limnological regionalization of Mexico
Authors: Alcocer Javier , Escobar Elva 
Published: June 2006

AbstractMexico, with its unique northwest‐southeast horn‐like shape, attains its largest continental area toward the northwest. It spans more than 15° of latitude and longitude. Two‐thirds of its territory lie 800 m or more above sea‐level. The relief, dominated by mountains, is rugged. Climate is varied and includes arid, steppe‐like, temperate and tropical lands, with a general trend of increasing aridity north of the Trans‐Mexican Volcanic Belt. Such a heterogeneous physiographic‐climatic scenario leads to a wide diversity of epicontinental aquatic resources, with a general trend of increasing water availability south of the Trans‐Mexican Volcanic Belt. Nonetheless, Mexico scarcely holds 0.1% of the worlds’inland aquatic resources. In order to characterize, plan, and manage aquatic resources of so extensive an area, it is important to undertake a limnological regionalization. Considering the hydraulic, climatic, geographical and geological attributes of Mexico, a lake inventory and regionalization is provided to improve knowledge of the extent of Mexican limnological resources.
Causes and effects of the water‐level rise in the Caspian Sea
Authors: Shayegan Jalal , Badakhshan Amir 
Published: June 2006

AbstractThe level of water in the Caspian Sea has risen by 2 m in the last fifteen years and is continuing to rise. Fluctuation in the level of this lake has been observed in the past, but its present rate of rising is without precedent. The probable causes of such a high rate of increase in the level are explored and listed. The adverse economic impact on agricultural, civil, recreational and commercial activities on the shore of Iran are considered and ways to combat the problem are discussed.
Lessons from practical application of an ecosystem approach in management of the Laurentian Great Lakes
Authors: Hartig John H. , Thomas Richard L. , Iwachewski Edward 
Published: June 2006

AbstractThe Canada–United States Great Lakes Water Quality Agreement calls for the use of a systematic and comprehensive ecosystem approach (i.e. accounting for interrelationships among water, air, land, and all living things, including humans, and involving all user groups in comprehensive management) in water resource planning, research, and management. This Agreement further calls for the public to be consulted in all management actions. Remedial action plans (RAP) are being developed and implemented to restore uses in degraded areas of the Great Lakes and lakewide management plans (LaMP) are being developed and implemented to restore uses in open lake waters. These planning processes represent practical application of ecosystem approach theory. Lessons from practical experiences with Great Lakes RAP and LaMP include: an ecosystem approach can result in eliminating overlap and increasing efficiency; there can be positive effects from opening up decision‐making processes through meaningful public participation; priority should be placed on reaching agreement on problems and priorities; identification of key actions and delineation of sequencing, timeframe, and responsibilities is essential to ensure accountability; there is a need for a step‐wise approach to use restoration and demonstration of incremental progress; emphasis should be placed on planning cooperatively and sharing responsibilities for programme delivery; governments should provide resources to factilitate multi‐stakeholder decision‐making processes; spatial and temporal scale issues must be addressed; management actions should be treated as experiments; coupling of research and management has proven time and again to be cost‐ and ecosystem‐effective; and emphasis should be placed on measuring and celebrating progress for continuous improvement.
Shoreline marshes of Okanagan Lake: Are they habitats of high productivity, diversity, scarcity and vulnerability?
Authors: Northcote Thomas , Northcote Heather 
Published: June 2006

AbstractAbundance and diversity (number of taxa) of planktonic and epibenthic invertebrates were examined between October and December 1994 in a small shoreline marsh of southwestern Okanagan Lake, British Columbia, and compared to adjacent shoreline that was (i) slightly modified by human activity, and (ii) heavily modified by riprap placement. Planktonic and epibenthic invertebrate abundance and diversity was several‐fold higher in the shoreline marsh habitat, intermediate in the slightly modified shoreline habitat, and lowest in the riprap shoreline. A mid‐1930 survey of Okanagan Lake reported that only 9% of its shoreline had rooted aquatic vegetation, so historically the lakeshore marshes were scarce. Currently, only small vestiges of such habitat remain in a 42 km stretch of its southwestern shoreline where 80% of this length has been altered by various development activities: 41% by lakeshore housing and cottages, 27% by lakeshore road riprap, and 12% by parks, swimming beaches and other recreational developments.
Lake environments along the coast of Tamilnadu, India, delineated by IRS‐IA satellite data
Authors: Radhakrishnan N. , Elango L. 
Published: June 2006

AbstractIndian Remote Sensing Satellite (IRS‐IA) LISS I and LISS II data were studied to delineate major lake environments along the east coast of Tamilnadu, India. IRS‐IA satellite data were useful in delineating the spatial extent of lacustrine water‐bodies, their probable origin and regional setting, and their influence on the local environment. A few water‐bodies (i.e. Pulicat, Kalveli and lakes along the Vedaranniyam coast) were selected for particular study. They are the result of marine transgression during the late Cretaceous, and form an integral part of neotectonic and land‐building activities of the area. This study explains the relationship between lakes and coastline configuration, and is significant in understanding the lake environment and its subsequent role in coastal zone management
The growth, nitrogen fixation and nutrient removal capacity of Azolla in polluted water
Authors: Shiomi Nobuyuki , Kitoh Shunji 
Published: June 2006

AbstractThe growth and nitrogen fixation of Azolla filiculoides cultured in polluted pond water and two types of secondary effluent were investigated. The gradual decreases in the growth and acetylene reduction activity (ARA) of the plants in pond water were due mainly to a phosphorus deficiency. In the secondary effluent, ammonium was an important factor limiting growth and ARA. Azolla plants were screened for tolerance to ammonium ion on the basis of their growth on the medium with or without ammonium. Azolla nilotica was the most sensitive species of all, followed by A. rubra. Azolla pinnata van pinnata was the most tolerant one. Nutrient removal capacities by 10 Azolla strains in batch culture were examined. The highest capacities and the growth were found in May for all Azolla strains. In August and December, Azolla strains showed poor growth and low nutrient removal capacities.
Optical investigations of Estonian and Finnish lakes
Authors: Arst H. , Mäekivi S. , Kutser T. , Reinart A. , Blanco‐Sequeiros A. , Virta J. , Nõges P. 
Published: June 2006

AbstractSixteen lakes in Estonia and five lakes in Finland were investigated during 1992–95, using mainly optical methods. A total of 14 expeditions were undertaken, but the number was different for each lake. Vertical profiles of solar irradiance (spectral and integral), temperature and dissolved oxygen in the water column were measured, and Secchi disk depths were determined. Chlorophyll a and suspended matter concentrations were determined in the laboratory from water samples. Spectrophotometrical processing of the water samples (unfiltered and filtered water) was carried out to describe the beam attenuation coefficient spectra and to determine the spectral influence of yellow substance in the water. Passive optical remote sensing measurements were made from on board a boat. The data obtained show a rather high variability in water characteristics, although the lakes investigated are situated in the same climatic region. Several lakes receive human impact, and this has led to a decrease in water transparency and an increase in eutrophication. Despite rather low values for attenuation depth in lakes, water quality can be estimated using optical remote sensing data.
The use of field enclosure experiments to study the effect of pesticides on lake phytoplankton
Authors: Abdel‐Hamid Mohammad I. , Källqvist Torsten , Hessen Dag O. , Berge Dag 
Published: June 2006

AbstractAn outdoor enclosure experiment was carried out to study the effect of some selected pesticides on phytoplankton of Lake Omdalsvann, Norway. The experiment lasted 2 weeks during 1990 July/August). The pesticides tested were chlorosulfuron (herbicide), propiconazole (fungicide), dimethoate (insecticide) and glyphosate (herbicide). The pesticides were tested at three concentration levels (1 μg L−1, 10μg L−1 and 100μg L−1) of their active ingredients. Samples for phytoplankton analysis were collected twice each week. The species richness differed greatly among the experimental bags. All treatments resulted in a significant (P < 0.05) decrease in species number compared with the results of the control. At the same time, great differences did exist in algal biomass in response to different pesticides tested. The pattern of biomass deviation from control (positive or negative) and magnitude (significant or non‐significant, at P= 0.05) were mainly dependent on toxicant type, concentration and the exposure time. Shannon‐Wiener diversity indices ranged between 2.69 and 2.76. The index values decreased significantly at all pesticide treatments with lowest values usually recorded 2 days after adding the pesticides. The biomass of some natural algal taxa varied quite independently not only to the different pesticides but also to their concentrations; a finding which supports the concept of species‐dependent variation in algal sensitivity to chemicals. In situ toxicity testing seems to be a reliable protocol to generate more realistic data necessary for environmental protection.
Protection and management of anthroposaline lakes in Romania
Authors: Bulgǎreanu Valentin A. C. 
Published: June 2006

AbstractAnthroposaline lakes in Romania are used mostly for therapeutic purposes because of their high salinity and the sapropelic muds these contain. These are managed and protected within their‘perimeters of protection’. The special use of these lakes requires the maintenance of standards (biological, chemical, limnogenetical, limnogeological, morphometrical) which may be different from global recommendations for freshwater and saline (but non‐therapeutic) lakes.
Growth factors controlling periphyton production in a temperate reservoir in Patagonia used for fish farming
Authors: Baffico Gustavo D. , Pedrozo Fernando L. 
Published: June 2006

AbstractIn the early stages of pollution it is not always possible to detect contamination by chemical parameters as some components of the biota react more rapidly to inputs of pollutants. The purpose of this work is to determine the importance of nutrient inputs as a control of growth of the periphyton community and to evaluate the feasibility of using changes in the periphyton community to monitor the effects of contamination from fish farms. Wastes derived from fish farming in the Alicura Reservoir changed the nutrient concentrations of the sediment just below the fish cages and decreased the nitrogen: phosphorus (N:P) ratio to below 1. This situation stimulated the development of cyanophytes and increased the total algal biomass as a consequence of higher nutrient availability. In laboratory bioassays, diatoms dominated the periphyton community at high N:P (>4) and Si:P (> 1000) ratios, while cyanophytes were dominants at low N:P and Si:P (< 10) ratios. These results suggested that not only the N:P ratio controls periphyton composition, because in the reservoir (where N:P ratio was always low) the periphyton was dominated by diatoms as a result of the presence of extremely high Si:P ratios (3000‐5000). These results suggest that periphyton is a powerful tool for detecting the first signs of contamination.
The current problems of Lake Baikal ecosystem conservation
Authors: Kozhova Olga M. , Silow Eugene A. 
Published: June 2006

AbstractThe greatest world reservoir of fresh water, the unique Lake Baikal, is at risk from anthropogenic influence. Three stages of economic activity in the lake region can be distinguished: (i) poor economic uses, (ii) increase of economic uses after the construction of the hydropower station dam on the outflow of the lake, and (iii) intensive increase of economic activity, characterized by the intensive use of mineral fertilizers, transportation, log rafting, growth of population around Baikal, mass development of tourism, the construction of the Baikal‐Amur railroad and pulp combines. Chemical and biological pollution of the lake, fishing and hunting, the state of coasts and protected areas are discussed. The regions most affected are listed. The greater long‐term influence is an increase in the mineralization of tributary waters due to forest cutting and land cultivation. Though the influence does not cause a decline in water quality, the properties of the Baikalian water in local sites of pollution can significantly differ from their initial state. The quality of water, however, is within the limits of requirements for fresh drinking water.
Implications of compensatory and additive mortality to the management of selected sportfish populations
Authors: Allen M. S. , Miranda L. E. , Brock R. E. 
Published: June 2006

AbstractThe compensatory mortality hypothesis postulates that a population's total mortality remains unchanged at low to intermediate exploitation rates because natural mortality decreases to compensate for reduced density, whereas the additive mortality hypothesis postulates that any increase in exploitation mortality results in an increase in total mortality. Fishing and natural mortality rates have generally been assumed to be additive rather than compensatory. We reviewed mortality estimates for some prominent sportfish populations to identify evidence for compensatory or additive mortality. For largemouth bass Micropterus salmoides, total annual mortality increased with annual exploitation suggesting additive mortality. For crappies Pomoxis nigromaculatus and P. annularis, annual exploitation did not seem to affect annual mortality at low to moderate annual exploitation, but annual mortality increased with annual exploitation as it increased beyond 40%, conforming to the compensatory mortality hypothesis. Northern pike Esox lucius mortality estimates revealed no relation between annual mortality and annual exploitation, and highly variable annual mortality for a given annual exploitation. Evidence from the literature suggests that mortality of northern pike may be compensatory for fish smaller than 40 cm total length, but additive for larger fish. Because compensatory natural mortality reduces the managers’ability to control annual mortality, we suggest that further consideration of the compensatory mortality hypothesis be given to species that have shown variable mortality responses to reductions in annual exploitation.
Planktonic interactions with an austral bias: Implications for biomanipulation
Authors: Burns Carolyn W. 
Published: June 2006

AbstractThe conceptual model of trophic structure in a typical north temperate lake that underlies attempts at biological manipulation to improve water quality is reviewed in relation to the trophic structure and community composition of planktonic food webs in New Zealand and Australian lakes. New Zealand's relatively simple food webs are characterized by an absence of obligate piscivores and few vertebrate and invertebrate planktivores; manipulation of fish stock to improve water quality has not been attempted. The largest crustacean zooplankton in Australasia, and potentially the most effective grazers of phytoplankton, are Daphnia carinata and calanoid copepods (Boeckella spp.). Their potential capacities to remove algae and colonial cyanobacteria (Microcystis, filamentous forms) from waterways are discussed in relation to colony size and concentration, toxicity, selectivity, and digestibility. The potential of D. carinata to suppress rates of increase in phytoplankton biomass may be lowered by its sensitivity to crowding and starvation, and its susceptibility to predation by fish. Decisions to use biomanipulation as a management tool to improve water quality should be based on the results of a whole lake study and take into consideration relevant obligations to preserve the biodiversity of native species, and curb the spread and dominance of exotic species. Programmes that are based on reductions in biomass of planktivorous fish should be complemented by control of nutrient loads (integrated management).
Volga‐Kama cascade reservoirs and their optimal use
Authors: Avakyan A. B. 
Published: June 2006

AbstractReservoirs of the Volga‐Kama cascade, one of the largest cascades in the world, are described, with special attention to environmental problems. Measures for the improvement of the ecological situation in the river basin are analysed. A concept of water area regionalization, planning and engineering organization of water‐bodies, previously advanced as the basic principle of rational development of natural water resources, is presented.