bluuebunny/crossref_metadata_2025_split huggingface dataset:
Historic Trends in Lake Michigan Silica Concentrations
Authors: Schelske Claire L. 
Published: February 2007

AbstractHistoric data on soluble silica in the offshore waters of Lake Michigan were compiled and analyzed to determine whether the data supported a decrease in silica concentration which had been hypothesized previously on the basis of other studies. Although the data base was limited and no data were obtained for offshore waters (depths >40 m) prior to 1954, the available data support the conclusion that the silica concentration decreased rapidly after 1954. The thesis is developed that rapid silica depletion occurred in the 15‐year period from 1954 to 1969 when the winter maximum concentration decreased from approximately 4.4 to 1.4 mg SiO2 · 1−1 and the summer minimum decreased from approximately 2.2 to <0.2 mg SiO2 · 1−1. The decrease in silica concentration is attributed to increased production and sedimentation of diatoms that resulted from increased anthropogenic phosphorus loading. Total phosphorus in offshore waters was probably <10 μg P · 1−1 during the period of rapid silica depletion. The rapid decrease in silica concentration with relatively small phosphorus enrichment demonstrates that the tight coupling of biological and geochemical processes drastically affected the biogeochemistry of silica in a large, aquatic system within a relatively short period of time.
Activity of the Respiration Electron Transport System (ETS) Different Size Particles as a Measure of Carbon Losses from Primary Producers
Authors: Rai Hakumat 
Published: February 2007

AbstractIn situ ETS‐activity of size‐fractionated natural phytoplankton communities was studied to determine the relative rate of respiration of different size fractions. Different lakes of varying trophic levels were examined. This study suggested that <35 μm organisms are the major contributes of respiratory‐enzyme activity to the total community respiration. The results of this study indicate that half or more of the losses of primary productivity in different particle sizes are from respiratory activity. The data collected during this research on the photosynthetic rates and P/R ratio of different size particles give better information than primary productivity alone on community metabolic rates for evaluating productivity measurements.
Diurnal Variation in Feeding and Assimilation Rates of Planktonic Rotifers and its Possible Ecological Significance
Authors: Arndt Hartmut , Heerkloss Reinhard 
Published: February 2007

AbstractThough rotifers play an important role in many pelagic ecosystems, there is a lack for studies on diurnal variations in feeding behaviour. Diurnal feeding rhythms of estuarine populations of Brachionus plicatilis and Keratella cruciformis f. eichwaldi and a pond population of K. cochlearis were investigated using 14C‐Chlorella and 14C‐labelled natural bacteria populations, respectively, as a tracer food during in situ experiments. A 51Cr/14C double tracer technique was used to determine Assimilation efficiencies.All species had about two times higher feeding rates during day than during dark hours. There was a tendency for higher values during the afternoon. No trend was found regarding diurnal changes in assimilation efficiency.Diurnally segregated niches between microphagous daytime active rotifers and nighttime active crustacean populations in pelagic ecosystems are demonstrated and their ecological significance with special regard to changes in food quality and predation pressure is discussed.
Phosphorus Load‐Concentration Relationship in Lake Dal, a High Altitude Marl Lake in the Kashmir Himalayas
Authors: Ishaq Mohammed , Kaul V. 
Published: February 2007

AbstractThe relationship between phosphorus concentration and estimated phosphorus load in Lake Dal—a marl lake—is described for the past decade. The concentration of this element in the lake system remained constant during this period although the P load increased by about 40 %. This phenomenon is discussed in connection with various P‐removal mechanisms operating in the lake system.
Factors Controlling the Planktonic Community in the Shallow‐Lake of Créteil, France
Authors: Lacroix Gérard , Boët Philippe , Garnier Josette , Lescher‐Moutoué Françoise , Pourriot Roger , Testard Paul 
Published: February 2007

AbstractA two‐year study on the seasonal pattern of plankton was performed in a shallow, polymictic, eutrophic lake.Autogenic successions typical of stratified lakes did not occur. Only small edible algae developed throughout the two years and Cyanophyceae rarely appeared, and did not bloom. Algal sequences depended on wind‐induced periodic mixing of water.The seasonal pattern of Rotifers varied greatly from year to year and some species depended on sporadic increases of algae. In contrast, the seasonal pattern of microcrustacea was more regular. Resting stages played an important role in zooplankton development in this variable environment.Successful fish reproduction depended a great deal on climatic conditions. The changes from year to year in predation pressure from young fish appeared to be an important factor controlling zoo‐plankton structure.
Seasonal Fluctuation in Species Composition of Aquatic Hyphomycetous Flora in a Temperate Freshwater Stream of Central Himalaya, India
Authors: Mer G. S. , Sati S. C. 
Published: February 2007

AbstractThe frequency of occurrence and seasonal periodicity of aquatic hyphomycetes in a temperate freshwater stream of Central Himalaya were studied. The number of aquatic hyphomycetes species was found to vary inversely with temperature (r= −0.499; not significant), which explained 25 % of the variability. There were two maxima, one in spring and the other in autumn. On the basis of their occurrence, the species observed have been categorised into three groups. Constant species were Campylospora chaetocladia, Flagellospora penicilloides, Lemonniera aquatica and Tetracladium marchalianum.
Field and Laboratory Studies on some Photosynthetic Bacteria in Aswan High Dam Lake. II. Isolation and Identification of Purple Non‐sulfur Bacteria (Rhodospirillaceae)
Authors: Shoreit A. A. M. , Ahmed A. M. , Shabeb M. S. A. 
Published: February 2007

Abstract485 isolates were recorded from different localities between summer 1984 and spring 1985. These isolates comprise five different genera with eight different species of purple non‐sulfur bacteria‐ Rhodopseudomonas was the most common genus at all sites and was represented by three species. R. acidophila, R. blastica, R. palustris. Rhodomicrobium was the second in frequency and was represented by R. vannielli only. This species was only recorded for khor sites. Rhodocyclus was represented by two species, R. gelatinosus and R. tenuis. Rhodobacter and Rhodospirillum were represented by one species each, Rhodobacter capsulatus and Rhodospirillum rubrum. Khor sites were richer in number of isolates and genera of purple non‐sulphur bacteria than the main body of AHDL. Some species were more common in winter and spring while others predominate in summer and autumn.
Enclosure Experiments with Low‐dose Additions of Phosphorus and Nitrogen in the Acidified Lake Njupfatet, Central Sweden
Authors: Blomqvist P. , Olsson H. , Olofsson H. , Broberg O. 
Published: February 2007

AbstractExperiments involving low‐dose additions of phosphate, ammonium, nitrate and ADP, one by one and in combination, were performed in small (350 litre) in‐situ enclosures in a moderately acid (pH 5.4) lake. Before manipulation, all large filter‐feeding animals were removed by filtration. Phytoplankton responded to the nutrient additions only when both phosphorus and nitrogen were added, thus indicating a close balance between phosphorus and nitrogen limitation in the system.Variation of the inorganic nitrogen‐source resulted in species‐specific responses by phytoplankton. With ammonium as the nitrogen source Merismopedia tenuissima was favoured, regardless of whether this species was dominant in the phytoplankton community at the beginning of the experiment or not. With nitrate as nitrogen source Peridinium inconspicuum, which was never particularly common at the beginning of the experiments, was favoured. No other species of phytoplankton present in the bags was able to outcompete these two species as long as inorganic nutrients were added. With ADP as phosphorus source together with nitrate, a third species, Dictyosphaerium cf. botrytella, was favoured and reached dominance. The zooplankton community remaining in the bags, dominated by rotifers and calanoid nauplii, did not respond to the fertilization‐induced increases in the total biomass of phytoplankton.
Preliminary Observations on the Nature, Taxonomic Composition, Distribution, Behaviour and Nutrient Requirements of the “Unusual” Algal “Jellies” of Oguta Lake in Southeastern Nigeria
Authors: Nwadiaro C. S. 
Published: February 2007

AbstractPreliminary observations were made between October 1982 and May 1983 on the nature, taxonomic composition, spatial distribution, buoyancy behaviour and nutrient requirements of some unusual planktonic algal “jellies” in Oguta Lake in Southeastern Nigeria. These “jellies” are macroscopic, blue‐green algal masses whose excessive mucilage of high consistency acts as substrata for other epiphytic components viz. diatoms and green algae. They are more abundant in the lentic areas of the lake, undergo diurnal vertical movements and have their growth enhanced by spikes of nitrogen and phosphorus salts into their aquatic medium. The effects of these “jellies” on the ecology and general water use of the lake are discussed. Speculations on the reasons for their occurrence are given and possible control measures outlined.
Planktonic Luminous Bacteria of Vellar Estuary, South India
Authors: Ramesh A. , Venugopalan V. K. 
Published: February 2007

AbstractDistribution of planktonic luminous bacteria in relation to environmental parameters was investigated at two stations located in the Vellar Estuary. Luminous microflora showed a pronounced seasonal cycle with very low counts during monsoon months followed by an increase in post monsoon and peak counts during summer. The population density of these procaryotes was remarkably high ranging from 3.5 to 33.1 colony forming units per ml. They constituted 2.1 to 52.1 % of the total bacterial counts. Salinity appeared to govern the distribution of luminous procaryotes as their counts corresponded well with fluctuations in salinity. Taxonomic affiliation of the isolates revealed predominance of Vibrio harveyi. Vibrio fischeri and Photobacterium leiognathi exhibited sparse distribution.
Bacterioplankton and Phytoplankton Populations in a Rapidly‐Flushed Eutrophic Reservoir
Authors: Perry Sue A. , Perry William B. , Simmons George M. 
Published: February 2007

AbstractDensities of bacterioplankton and phytoplankton were studied in relation to water retention time, temperature, nutrient concentrations, and other variables in a eutrophic montane reservoir (Bluestone Lake, West Virginia, U.S.A.). Weak temperature stratification occurred occasionally during the summer, but the reservoir did not become anaerobic. Water retention times were short (3.9 to 9.7 days between June and December), and differences in flushing rate within that range were important in regulating phytoplankton populations. Green algae and planktonic diatoms were dominant in summer during periods when water residence times were shorter. The occurrence of blue‐green algal blooms in fall was related to increased water residence times. Retention time was highly correlated with the percent composition of phytoplankton represented by Anabaena spp. and Microcystis sp. (r=0.898, p<0.001). Advective effects limited phytoplankton biomass when retention time was shortest, but were not as important when retention times were longer. Peaks in bacterial densities often coincided with decreases in viable algal cell densities, so bacterioplankton were less directly related to retention time.
Phosphorus Budget for Dal, a Himalayan Lake
Authors: Ishaq Mohammed , Kaul V. 
Published: February 2007

AbstractThe P‐budget of Dal Lake in Kashmir is described for a 12 month period. The lake is characterized by high P‐loading (7.5 g · m−2 a−1) and had high P‐retention (retention coefficient 0.32). P‐loading in the lake showed positive and negative relations with flushing rate and P‐retention respectively. A negative relation was similarly found existing between flushing and P‐retention. The roles of various biotic and abiotic factors in the P‐budget of the lake are described.
Uptake of Mineral Particles byBiomphalaria glabrata(Say.) (Pulmonata, Mollusca) and its Importance for Growth Rate and Egg Production
Authors: Schmölder Ute , Becker Wilhelm 
Published: February 2007

AbstractThe ingestion of mineral particles byBiomphalaria glabratais proved and the importance of these particles in the diet of the snails is investigated. The number of particles ingested rises with the size of the snails and they are retained in quantity in the alimentary tract when an adequate supply is not provided. The size of grit found in the gut differs widely from the mixture offered. Mineral particles are ingested actively and selectively.Quantitative investigations comparing snails cultured with and without sand showed a slight advantage concerning growth and reproduction for snails cultured with sand.
The Significance of Zooplankton in the Cycling of Phosphorus in Lakes of Different Trophic Categories
Authors: Gutelmakher Boris L. , Makartseva Elena S. 
Published: February 2007

AbstractThe species composition, number, biomass and phosphorus excretion rate (PER) of zooplankton (Crustacea and Rotatoria) in 8 mesotrophic and eutrophic lakes were studied. PER were calculated using specific expenditures on metabolism estimated from the oxygen uptake, phosphorus content in zooplankton and field observations of number and biomass of planktonic Rotatoria and Crustacea. The zooplankton biomass and PER increased from mesotrophic to eutrophic lakes. The values of PER were compared with primary production and spring phosphorus concentration. The relative significance of zooplankton in phosphorus cycling declined with increasing trophic category of lakes.
A Natural Phosphate Source for Lake Waccamaw, North Carolina, USA
Authors: Cahoon Lawrence B. , Kucklick John R. , Stager J. Curtis 
Published: February 2007

AbstractA limestone outcrop along the north shore of Lake Waccamaw, North Carolina, is found to contain ca. 0.1 % phosphate by weight. Weathering processes have probably driven steady inputs of phosphate from this source throughout the lake's history, accounting for its near eutrophic state. The sediments of Lake Waccamaw are enriched with phosphate, particularly in the littoral zone near the outcrop. Chemical and biological processes apparently remove phosphate from solution rapidly, making detection of a soluble phosphate signal near the outcrop difficult. Management of nutrient inputs and water quality in Lake Waccamaw requires consideration of the effects of this in‐lake source of phosphate. Other sources of phosphate, particularly in the lake's drainage basin, may be less important than previously thought.
The Usefulness of Various Numerical Methods for Assessing the Specific Effects of Pollution on Aquatic Biota
Authors: Heckman Charles W. , Kamieth Heino , Stöhr Manfred 
Published: February 2007

AbstractThe data obtained during an extensive multidisciplinary investigation of a polluted harbor basin in Hamburg were analyzed in various ways in order to determine which statistical methods are easiest to interpret and permit the most accurate evaluations. The methods analyzed include the species deficit, index of species similarity, and saprobity index, as well as the more complex cluster and gradient analyses, which revealed a variety of relationships among the biotic communities at the various sampling sites and some ecological tolerance limits of various species. The shortcomings of numerical indices for characterizing water bodies are discussed. It is suggested that biostatistical methods are much more valuable for the empirical evaluation of data than for artificially classifying ecosystems.
Proximate Composition and Nutrient Elements in the “Unusual” Algal “Jellies” of Lake Oguta in Southern Nigeria
Authors: Nwadiaro Chukwuemekanim , Idabor Peter 
Published: February 2007

AbstractThe proximate composition, nutrient and trace elements of the planktonic algal “jellies” of Lake Oguta in Southern Nigeria, are provided as guides to their utilization and control, using flood (rainy) and dry season samples. These “jellies” are an unusual, macroscopic planktonic algal community in the lake, made up mostly of blue‐green algae (Microcystis, Anabaena, Chroococcus) with some green algae (e. g. Spirogyra) and pennate diatoms (e.g. Navicula) rather epiphytic on the mucous jellies of the blue‐green algae. Water content was high (98.2% mean, range 97.5‐99.5%). Ash, protein and fat had values of 41.7 (39.0‐46.2%), 16.9 (15.6‐19.4%), and 2.0 (1.7‐2.1%) respectively. Crude fibre and carbohydrates were high (25.8% and 12.4%). The levels of phosphorus and nitrogen were rather high, so were the major cations whose order of dominance (Ca > K > Mg > Na) differed from that of the lake water. Macronutrients increased in their concentrations during the rainy flood season while the reverse was the case with the micronutrients. Diagenesis of the endogenic minerals rather than anthropogenic factors are thought to be the reason for the seasonal changes in the ionic concentrations. Possible uses of the algal jellies are discussed as well as their control options.
The Distribution of Mercury in the Sediments of Eight Saskatchewan Lakes
Authors: Merkowsky Alan T. , Hammer U. Theodore , Huang P. Ming 
Published: February 2007

AbstractEight lakes located in the southern half of Saskatchewan were sampled in May and June, 1987, to determine the concentration and spatial distribution of mercury in their surface sediments. Katepwa and Buffalo Pound lakes had maximum total mercury sediment concentrations of 0.158 and 0.100 μg · g−1 dry weight respectively, while in the other six lakes the mercury concentration was never greater than 0.04 μg · g−1 dw. Despite this difference in mercury concentration in the sediments of the lakes, walleye sampled from them have high mercury concentrations exceeding 0.5 μ · g−1 (wet weight).
Seasonal Variation in Community Structure of Macrobenthic Invertebrates in Sandy Beaches of Jordan Coastline, Gulf of Aqaba, Red Sea
Authors: Ismail Naim S. 
Published: February 2007

AbstractTwo Jordanian sandy beaches, one at the northern end and the other at the southern end near the Saudi‐Jordanian border, were examined during November 1984 to October 1985. Sediments of the South station were made of coarser sand than the North station. In general, low organic carbon and calcium carbonate levels were found at both stations. A total of 15839 animals representing 45 taxa were collected from both stations. Major differences in community structure were found between the two stations. An average density of 7981/m2, 39 taxa. an average diversity value of 1.78 and an evenness of 0.37 were characteristic of the South station. Lower number of taxa (39) and density (818/m2) were found on the North station. However, the average diversity (3.18) and evenness (0.74) were higher. Using the biological index value of MCCLOSKEY (1970), the archiannelid Saccocirrus sp. was the most dominant species at the South station and the bivalve Tellina perna at the North station.
The Assessment of Size‐class Proportions and Fisheries Mortality of Eel Using Various Catching Equipment
Authors: Berg R. 
Published: February 2007

AbstractSamples of approximately 11,000 eels were used to analyse the size class composition of the eel stock in Lake Constance (Bodensee). The main statistical approach was to separate a ‘stock dependent fraction’ within the length frequency distributions obtained from three different traps and two electrofishing methods.From the calculated size class proportions an average total mortality of 28.5% was estimated for eels bigger than 50 cm opposed to 26% total mortality for the unfished part of the population.
Re‐evaluation of Present Eel Stocking Practices in Czechoslovakia; Production of Advanced Fry
Authors: Peňáz Milan , Vostradovský Jiří 
Published: February 2007

AbstractThe authors have tested and recommend the rearing of eel fry until June when there are optimum conditions for stocking in open waters. Glass eels were fed either with traditional natural feeds (spleen, plankton, whitefish eggs) or exclusively with dry compound feeds for trout (EWOS, TROUVIT, VELAZ) and a special compound feed prepared by ourselves that is enriched by germ cells of Streptococcus faecium.
Short Note on the Effects of Cadmium on the Gill of the Glass Eel (Anguilla anguilla)
Authors: Gony Sylviane 
Published: February 2007

AbstractFreshwater‐adapted glass eels have been exposed to cadmium (5 mg/l) for 3 days and then transferred in clean water for 28 days. Perturbations occurred very early (after 2 hrs only of exposure to cadmium) and concerned mainly the respiratory epithelium: the epithelial cells were very swollen and they showed an important dilation of the endoplasmic reticulum and nuclear membrane. After the decontamination period, signs of recovery appear. Perturbations of osmo‐regulatory and respiratory processes are suggested.
The Distribution of Small Larvae of Anguilla sp. Related to Hydrographic Conditions 1981 between Bermuda and Puerto Rico
Authors: Tesch F.‐W. , Wegner G. 
Published: February 2007

AbstractOn a section between Bermuda and Puerto Rico, in March/April 1981 Anguilla sp. larvae abundance and hydrographic conditions were studied. The small larvae (<7 mm Tl) occurred south of 30° N at the subtropical thermal front and showed peak abundance at 26° N. At 23° N larvae of all size groups became less abundant. North‐south extention of the spawning area was greater than described in the literature. A considerable net avoidance of the larvae during daylight hauls was observed. Lengths of both Anguilla species increased from the north to the peak abundance area in the south and for A. anguilla also from east to west. Patches with about the fifty fold larvae abundance compared with the surrounding area could be identified. Deeper occurrence of the smallest larvae (Tl = 4 and 5 mm) compared with older larvae, found in earlier studies could be stated.
Anguillicola in Dutch Eelfarms; Current State
Authors: Kamstra A. 
Published: February 2007

AbstractAnguillicola crassus was introduced into Dutch eelfarms by infected stocking material originating from inland fisheries. Within farms, suitable intermediate hosts for transmission of the parasite are available and uninfected stock becomes rapidly infected. In farming situations, only very heavy infections with the parasite can cause significant damage to fish, mainly by secondary infections. Treatment of fish infected with A. crassus is possible with L‐Levamisole as a bath treatment or mixed with the feed, which results in complete immobilisation of the nematode. Transmission of the infection within farms can be controlled by keeping populations of copepods low. This can be accomplished by avoiding accumulations of organic matter within systems and/or control with chemical means. It can be stated that Anguillicola crassus does not pose the threat to intensive eel culture it once seemed to be.
Limnology of a Sewage Polluted Lake: The Lower Lake (Bhopal, India)
Authors: Valecha V. , Valecha R. , Bhatnagar G. P. 
Published: February 2007

AbstractSeasonal and vertical distribution of temperature, pH, dissolved oxygen, free CO2, alkalinity, nitrate, phosphate and phytoplankton have been studied at the deepest point of the Lower Lake, Bhopal from September 1979 to August 1981. Stratification was noticed in almost all the parameters. Bottom was frequently anoxic. The dominant groups among phytoplankton were Chlorophyceae, Cyanophyceae and Bacillariophyceae.