bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Zoobenthos‐Gesellschaften des Piburger Baches (Ötztal, Tirol). The Zoobenthos Assemblages of Piburger Bach (Oetztal, Tyrol)
Authors: Kownacka Marta , Margreiter Gerhard 
Published: February 2007

AbstractPiburger Bach is a short, spring‐fed lake affluent. The macrozoobenthos of this stream has been studied both qualitatively and quantitatively. More than 15,000 specimens of invertebrates, including all developmental stages of insects, were collected; a high proportion of these was identified to the genus or species level. The spatial and temporal distribution of various taxa as well as their quantitative contribution to the total macrobenthos are discussed. Confidence limits of the data are considered.
The Measurement of Groundwater Discharge into a Lake by a Direct Method
Authors: Lock Maurice A. , John Peter H. 
Published: February 2007

AbstractAn apparatus is described which allows groundwater discharge through lake beds to be measured directly. On transects at right angles to‐the shore‐line of Lake Taupo, New Zealand, discharges Mere found to decrease rapidly with distance from the shore. The potential use of this technique in the construction of nutrient budgets for lakes is outlined.
Experiments with Large Enclosures in a Fertile, Shallow, Brackish Lake, Hickling Broad, Norfolk, United Kingdom
Authors: Leah R. T. , Moss Brian , Forrest D. E. 
Published: February 2007

AbstractEvents in the plankton community of a 120 ha, shallow (1.2 m), brackish lake have been studied with the help of two watertight enclosures, each of which isolated about 300 m3 of water and its underlying sediment. Analyses of soluble reactive phosphorus, total phosphorus, ammonia‐N, nitrate‐N, silicate‐Si, chloride, photosynthetic pigments, phytoplankton and zooplankton counts are reported and are related to inputs of nitrogen and phosphorus into the lake from adjoining basins and the catchment, and to the hydrologic regime. The inputs of phosphorus are budgeted and a very large roost of black‐headed gulls appears to provide most of the phosphorus supply. The results are discussed with reference to the eutrophication of the lake and decline of aquatic macrophytes which have occurred in the past ten years.
The Saline Lakes of Saskatchewan III. Chemical Characterization
Authors: Hammer U. T. 
Published: February 2007

AbstractThe salinity of Saskatchewan saline lakes varies up to 342%0. Highly saline lakes are widely distributed. Some reach saturation at high summer temperatures but salt precipitation occurs on cooling. Saline lakes tend to increase in salinity with time but the greatest changes occur in the shallow more saline lakes.The lakes are dominated by sodium, magnesium and sulphate. The cation sequences are dominated by sodium or magnesium while calcium and potassium are proportionally much smaller. Chloride or bicarbonate‐carbonate are secondary to sulphate among the anions. Ion sequences tend to be characteristic of certain physiographic regions. Lake types were magnesium (sodium) sulphate, sodium sulphate and sodium (magnesium) sulphate in order of abundance of lakes.Phosphorus and ammonia were high in concentration but nitrate and silica were scarce. The lakes were all alkaline between pH 7.8 and 9.8.The evolution of closed saline lakes is briefly discussed.
The Upper Limit of Phytoplankton Production as a Function of Nutrient Load, Temperature, Retention Time of the Water, and Euphotic Zone Depth
Authors: Uhlmann Dietrich 
Published: February 2007

AbstractIn laboratory models of sewage ponds operated on a semicontinuous‐flow basis, the net primary production II of the phytoplankton was measured by harvesting the suspended matter both from the outflow and the bottom of the vessels at daily intervals. The maximum value of II was as high as 50 mg dry weight/l day (corresponding to 20 mg C/l day). With the nutrient load L kept ad a constant level, the steady state phytoplankton biomass x decreased with decreasing water residence time t in accordance with the dropping inflow concentration of the nutrients. On the other hand, at 20 °C no higher x was yielded at t=40 than at t=5 days. This result obviously has to be attributed to a substantial increase in grazing rate with progressing t at the temperature level of 20 and 30 °C. In this connection extremely low magnitudes of II may result despite optimum levels of nutrient supply, radiation and temperature.The highest estimates of II hitherto measured and recorded in the literature relate to the euphotic zone depth (zeu in m) as follows:
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The Diatoms, Productivity and Morphometry of 43 Lakes in New York State, U.S.A
Authors: Shero Brian R. , Parker Michael , Stewart Kenton M. 
Published: February 2007

AbstractDiatoms were examined in surface sediments collected from 43 lakes throughout New York State to determine the interrelationships among the abundances of various diatom taxa,' lake productivity and lake morphometry. Diatom ratios, including the A/C, C/P and five new quotients, were not well correlated with lake productivity, probably because of the diversity of the taxa which they employ. The abundance of individual genera or combinations of genera were better indicators of productivity. Cyclotella was the best single indicator of productivity being most abundant in low productivity lakes. Several fairly distinct diatom associations were identified by correlations between all possible pairs of diatom taxa. Finally, lake productivity was found to be significantly correlated with morphometry, being highest in small/shallow lakes.
The Crustacean Zooplankton of Grasmere Before and After a Change in Sewage Effluent Treatment
Authors: Smyly W. J. P. 
Published: February 2007

AbstractThe limnetic crustaceans of Grasmere, a small lake in the English Lake District, were studied from February 1969 to December 1970 (23 months) and from January to December 1975. These observations were made before and after a change in sewage effluent treatment effected in May 1971. Planktonic species, except for one cladoceran, were more abundant in the second than the first period, while hypolimnetic and profundal forms either became less abundant or modified their life‐style in conjunction with a developing hypolimnetic oxygen‐deficit.
Influence of the Season and of Preservation Methods on Wet‐ and Dry Weights of Larvae of Chironomus plumosus L
Authors: Landahl C. C. , Nagell B. 
Published: February 2007

AbstractPreservation in 70% ethanol or 4% formaldehyde solution resulted in the leaching of ca. 30% arid ca. 10% dry matter, respectively. Subsequent soaking in water considerably increased leaching. The percent ratio of dry weight to live weight decreased during the summer from ca. 15% in June to ca. 11 % in September for the fourth instar larvae. The results indicate that formaldehyde can chemically react with the larvae, thereby increasing their dry weight. The dry weight of the gut content was ca. 4% of the total dry weight.
On the Food of the Air‐breathing Catfish, Clarias batrachus (LINN.) Occurring in Wild Waters
Authors: Thakur Nirmal K. 
Published: February 2007

AbstractThe paper describes the food of Clarias batrachus (LINN.) occuring in derelict and swampy waters of the Bihar region of the Indian subcontinent. The study revealed that the early post‐larval stage is exclusively planktophagous while in the late post‐larval stage it starts including larger organisms in its diet. Juvenile stage is predominantly insectivorous. Though adults have a wide range of food preference, the insect material forms by far the most important source of their food. The fish did not appear to possess enough sense to sort out edible from non‐edible forms. March and September are the peak periods of relatively intensive feeding. The intensity of feeding in relation to the size of the fish showed that the average weight of food/g weight of the fish decreases with increasing weight of the fish.
The Characteristics of a Temperate Eutrophic, Dimictic Lake (Lake Mikołajskie, Northern Poland)
Authors: Kajak Zdzisław 
Published: February 2007

AbstractGross primary production equals 3160 kcal Xm−2 ×yr−1, 38% coming from the littoral. The efficiencies of both nonpredatory and predatory zooplankton production are high. The production of phytoplankton is expended mostly for sedimentation in April, for grazing by zooplankton in June, heterotrophic respiration and cumulation of dissolved and particulate organic matter in August—September and sedimentation in late autumn. Almost total elimination of zooplankton is done by predators, mostly invertebrates. About 10% of autochthonically produced plus allochthonic matter is annually removed from cycling, mostly as permanent bottom deposits. The annual load of phosphorus is 3 times higher than the permissible VOLLENWEIDER'S level. About 70% of phosphorus load, but only two percent of its reserve in the lake is annually removed from cycling. Progressing eutrophication resulted in several times increased phytoplankton biomass, decrease of phytoplankton P/B and share of nannoplankton, increase of decomposition in epilimnion, etc, during 10 years. Inspite of this, pelagic community in spring still has rather mesotrophic than highly eutrophic character. Increased eutrophication due to human impact (deforestation, agriculture, erosion) is also seen in bottom deposits since the 15th century.
Trophic Changes in Reservoirs; An Hypothesis Using Phosphorus Budget Models
Authors: Ostrofsky Milton L. 
Published: February 2007

AbstractCurrent empirical models used to predict phosphorus concentration from loading, retention and discharge data assume a phosphorus load which is constant in time. Such models are clearly inappropriate in relation to reservoirs. In a study of several lakes and a reservoir in western Labrador, the phosphorus budget model was found to be an excellent predictor of phosphorus concentration in the natural lakes, but seriously underestimated phosphorus concentration in the reservoir.Since leaching of nutrients from inundated soils and vegetation is generally considered to be the cause of trophic changes in reservoirs, a time dependent “leach loading” component was built into the steady state phosphorus budget model. This component not only allowed the budget to be balanced, but allowed the estimation of leaching coefficients describing the rate of phosphorus loss from submerged soils and vegetation. Using literature data from other reservoirs, the modified model predicted phosphorus dynamics consistent with other observed trophic status indicators.
Distribution and Fractionation of Arsenic in Selected Fresh Water Lake Sediments
Authors: Huang Pan M. , Liaw Wen K. 
Published: February 2007

AbstractThe distribution and nature of the As‐bearing components of the sediments of selected fresh water lakes in Saskatchewan, Canada, were studied. The total As contents ranged from 2.7 to 13.2 ppm As and were found to be present in both colloidal and non‐colloidal fractions of the lake sediments. The proportion of the As bound to carbonates, organic matter and sesquioxides accounted for 12 to 74% of the total As of the sediments. The remaining As was apparently associated with apatite and silicates. The data indicate that the bulk of As in the lake sediments resides in sesquioxidic components and apatite. The release of As from the lake sediments would thus be affected by the stability of these As‐bearing components in a series of particle size fractions. Furthermore, based on information on the geographical distribution of As in the lake sediments, land erosion and agricultural runoff appear to be contributing significantly to the As concentration in lake sediments. It is thus suggested that close attention should be paid to land management and soil conservation to prevent further enrichment of As in lake sediments and to curtail the subsequent As contamination of the food chain.
Plankton Biogeography of the Indian Ocean
Authors: Krishnamurthy K. , Naidu W. Damodara , Santhanam R. 
Published: February 2007

AbstractKnowledge of plankton biogeography for the Indian and adjacent seas is necessary for an understanding of the regional characteristics and changes in the plankton composition. Some of the plankters will serve as good biogeographical indicator species. Some phytoplankters and tintinnids among zooplankton are promising for use as such labels for the presence of different waters in the Porto Novo (Coromandel coast, Bay of Bengal) region. A biogeographical classification of the local phytoplankton and peculiarities in the distribution of some rare tintinnids occurring there are discussed.
Some Factors Influencing the Diversity and Species Composition of Benthic Invertebrate Communities in Twenty Arctic and Subarctic Lakes
Authors: Moore James W. 
Published: February 2007

AbstractThe factors influencing the density, diversity and species composition of benthic invertebrate communities in 20 lakes in the Canadian arctic and subarctic were determined during 1975, 1976 and 1977. Despite small differences in nutrient and phytoplankton levels among the lakes, there was a strong positive correlation between these parameters and the density and diversity of the communities. Other factors, including maximum summer water temperature, lake depth and surface area had little overall effect on the communities. The densities of 2 ultra‐oligotrophic chironomids (Heterotrissocladius oliveriandMicropsectracf.groenlandica) increased markedly in cold deep lakes. However the abundance of the majority of species, most notablyProcladius denticulatus, Tanytarsussp., andStictochironomussp., was not effected by temperature. Other species, (Pontoporeia affinis, Monodiamesa bathyphilaandDicrotendipes nervosus) were probably restricted in their northern distribution by temperature. Surface area usually had little effect on the densities of all common species.
Winter Anomalies of Seston, Phytoplankton and Cations in a Colorado (U.S.A.) Alpine Flowage Lake
Authors: Heermann Scott J. 
Published: February 2007

AbstractYear‐round changes of phytoplankton, organic and inorganic seston, and dissolved and suspended concentrations of Ca, Mg, Na, K, Fe, Mn, Zn, and Cu were studied and correlated in Long Lake, an ultra‐oligotrophic alpine flowage lake of northcentral Colorado, U.S.A. Dissolved cation levels for Ca, Mg, Na, K, Mn, and Fe, both sestonic fractions and phytoplankton densities reached and sustained a maximum during April and May under heavy cover of ice and snow, and a minimum during open‐season from mid‐June to mid‐October. Rates of monthly water renewal varied greatly with a low of 0.28 turnovers in April and a high of 15.37 turnovers in June. Massive flushing in June and July reduced dissolved Fe levels to <0.060 mg/l from a typical maxima >8.0 mg/l in April and May. Tests for linear correlation between the various cations, sestonic fractions and phytoplankton showed in most cases positive and significant (p <.05) relationships. For most dissolved Fe and Mn pairings with phytoplankton and seston exceptionally significant (p < 0.001) relationships were observed.
Some Problems in the Estimation of Chlorophyll‐a and Phaeopigments from Pre‐ and Post‐acidification Spectrophotometrie Measurements
Authors: Moed Jan R. , Hallegraeff Gustaaf M. 
Published: February 2007

AbstractThe rate of conversion of chlorophyll‐a to phaeophytin‐a in dilute acid organic solvents is markedly pH‐dependent. The widely used spectrophotometric measurement before and after acidification to discriminate between chlorophyll‐a and phaeopigments is applicable only between pH 2.6—2.8. At higher pH the reaction proceeds slowly and occasionally may be incomplete. At lower pH complicating reactions may occur, such as breakdown of certain carotenoid pigments causing (time‐dependent) increase of background absorption, and formation of di‐cations of phaeophytin with spectral characteristics different from the usually obtained mono‐cations of phaeophytin. Consequently, it is stressed to control carefully the acid concentration, the water content of the solvent, and the amount of MgCO3 used in the filtration procedure. In general, for the purpose of spectrophotometric acidification experiments, acidification by dilute hydrochloric acid added to organic solvents containing 10—20% water, and omission of MgCO3 would be preferable.On the basis of observed complications in the red part of the absorption spectrum of the pigment extract, it is recommended to use the above stated pH‐range.
Beiträge zur Morphologie und Entwicklung des Semipoljes Amvrakia (Limni Amvrakia), Westgriechenland. Contributions to the Morphology and Development of the Semipolje Lake Amvrakia (Limni Amvrakia), Western Greece
Authors: Verginis S. , Leontaris S. 
Published: February 2007

AbstractLake Amvrakia is judged by the authors to be a semipolje. Chalky formations 1—5 m above present water level indicate that formerly the level was higher.
Composition and Distribution of Caspian Fauna in the Light of Modern Data
Authors: Mordukhai‐Boltovskoi Philaret D. 
Published: February 2007

AbstractThe composition of the Caspian fauna is considered in the light of modern data. The number of autochthonous species known for the Caspian Sea has now reached 435 and the Caspian species in the Pontoazov basin and Lake Aral number 178 and 41 species, respectively, i. e. 25–30% more than stated in the lists in my previous review (1960, 1964). The distribution of the Caspian fauna outside the Caspian Sea is discussed and it is shown that the ranges of many species have diminised owing to unfavourable conditions. However, in some species, especially mysids, the ranges have become substantially larger on account of their artificial acclimatization.
The Size‐Depth Relationship in Deep Ocean Animals
Authors: Polloni Pamela , Haedrich Richard , Rowe Gilbert , Hovey Clifford C. 
Published: February 2007

AbstractIn response to Thiel's (1975). hypothesis that the food‐limited deep sea is a small organism habitat, further data on average size of individuals representing various deep‐sea taxa are presented. Our data were gathered with trawls and box corers between 200 and 5000 meters, in the western North Atlantic. For echinoderms, decapods and macrofauna there appears to be no steady, logarithmic decline in size with increasing depth, but fishes are bigger – deeper.
Résultats de la mission Hydratlante I du N. O. Jean Charcot (au large des côtes atlantiques françaises). 2. Pigments phytoplanctoniques
Authors: Travers Marc 
Published: February 2007

AbstractResults of Hydratlante I Cruise of R. V. Jean Charcot (off the Atlantic French Coast). 2. Phytoplankton PignientsMeasurements of phytoplankton pigments have been made at all levels and stations prospected during Hydratlante I. In neritic as well as oceanic waters, the chlorophyll a content of seston was low: only 0.07–0.08 mg · m−3 at 5 and 20 m; maximum average value at 50 m: 0.14 mg · m−3. The chlorophyll a content of phytoplankton cells averages 6.2 pg but varies greatly with population density. The plant carotenoids, relatively more abundant than chlorophyll, average 0.7 mg · m−3 at 5 m; 0.9 at 20 m and 1.2 at 50 m. Pigment distributions seem to be largely dependent on thermal structure and nutrient concentration. They are also more or less strongly correlated with water transparency, rate of 14C fixation and organic seston content. Comparisons with previous results in the same area reveal a rather good agreement.
Glucose in Freshwater of Central Amazon Lakes: Natural Substrate Concentrations Determined by Dilution Bioassay
Authors: Rai Hakumat 
Published: February 2007

AbstractA bioassay method has been employed to measure concentrations of glucose in the Central Amazon lakes. Michaelis‐Menten enzyme kinetics parameters from the 14 bioassay measurements were made during this study. Concentrations of glucose found in Lago Tupé (10–485 μg/1)., Lago Cristalino (8–393 μg/1). and Lago Janauari (1‐485 μg/1). are greater than anticipated. The bioassay method is applicable in determining concentrations of glucose in freshwater of the Central Amazon.
A Comparison of Methods for the Estimation of Phytoplankton Primary Production
Authors: Salonen Kalevi , Holopainen Anna‐Liisa 
Published: February 2007

AbstractThe primary productivity of phytoplankton in several lakes with different trophic status was estimated by radiocarbon and dissolved inorganic carbon (DIG). consumption methods. On an average, the direct DIC consumption method with light and dark bottles yielded 46% higher results than the radiocarbon method. The exact nature of the difference is obscure, but it is suggested that greater attention should be paid to heterotrophic consumption during the experiment than has been done in previous studies, as this is intimately linked with primary production.The liquid scintillation and Geiger Müller (GM). counts resulted in similar estimates of primary productivity when the radioactivity of the stock NaH14CO3‐solution for the GM method was determined by the biological method of Steemann Nielsen. This and the fairly close agreement of the results with those of the DIC consumption method indicate that the radiocarbon method is equally useful in estimating primary productivity in lakes ranging in status from oligotrophic to very eutrophic.
Experimentelle Untersuchungen zur Anpassung von Fungiiden (Scleractinia, Fungiidae). an unterschiedliche Sedimentations‐und Bodenverhältnisse.
Authors: Schuhmacher Helmut 
Published: February 2007

AbstractExperiments on Adaptations to Sedimentation and Substrate in Fungiid Corals (Scleractinia, Fungiidae)Experimental evaluation of the sediment rejecting behaviour in fungiid corals shows: a). sediments easily slide off from cupolate coralla; b). some flat corals inflate the polyp to get rid off sediments; c). in most species sediments are entangled in mucus and removed by ciliary action. However mucus production is limited by the number of functioning mucous cells.During continuous stress by weighting sediments the tissue overlying the septal ridges gets cut and worn off. Damage instantly occurs in species with sharp septa, but relatively late in those with broad septa. Even minute tissue remains are capable of regenerating trophozoids attached to the old skeleton. Species which endure only low sedimentation rates, are mainly confined to hard bottoms (e.g. reef slope).
Assimilation by Aquatic Oligochaeta
Authors: Brinkhurst Ralph O. , Austin Merelene J. 
Published: February 2007

AbstractAquatic oligochaetes selectively ingest material from sediments given as food. Determinations of the quantity of organic material presented, left in the residue, and voided as feces enabled estimation of assimilation. These figures were not significantly different from those obtained by summing growth as observed in the experiment with respiration determined independently. Short term experiments yield estimates of assimilation of 77 to 181 cals/g dry wt/day, long term experiments yield an estimate of 232 cals/g dry wt/day, both for mixed populations of Tubifex tubifex and Limnodrilus hoffmeisteri.
The Horizontal Distribution of Baltic Epi‐ and Metalimnic Zooplankton Species
Authors: Sandström Olof 
Published: February 2007

AbstractThe horizontal distribution of epi‐ and metalimnic zooplankton species in the northern region of the Bothnian Sea was studied in July and August 1975. The distribution was determined by vertical sampling with plankton nets at randomly selected stations in two areas (4 and 8 km2). Most species were clearly nonrandomly distributed in these two sampling areas. Horizontal patchiness within areas of a few km2 could be shown by grouping closely adjacent stations according to similarity or difference in average values. At the individual stations, there were only a few cases where any marked deviations from randomness were found. The age distributions of copepods differed in different parts of the areas. This is thought to be an important factor for the creation of patchiness.