bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limnological Characteristics of Two Eutrophic and Four Mesotrophic Lakes in West‐central Florida
Authors: Dawes Clinton J. , Cowell Bruce C. , Gardiner William E. , Scheda Sandra M. 
Published: February 2007

AbstractLimnological characteristics of six subtropical lakes were monitored to determine the factors which regulate chlorophyll α concentrations and phytoplankton standing crops. Most physical chemical variables showed non‐significant differences with depth but differences between lakes often were large. Phytoplankton blooms occurred throughout the year and there were marked differences between the hypereutrophic and mesotrophic lakes in chlorophyll α concentrations, standing stocks, and dominant species. Densities of total zooplankton and rotifers in the hypereutrophic lakes were 3‐ to 6‐fold greater than in the mesotrophic lakes. Regression models for chlorophyll α and total phytoplankton cell volume were calculated for each lake and for all lakes combined, but R2 values and numbers of shared variables tended to be low indicating the need for additional variables and more frequent sampling.
Eurycercus glacialis in Ireland (Cladocera, Chydoridae)
Authors: Duigan Catherine , Frey David G. 
Published: February 2007

AbstractThe taxon Eurycercus glacialis of Western Europe has been discovered living in the turloughs (tuar loch = dry lake) of Western Ireland. Only four populations were found during three field excursions, but because of the multitude of these waterbodies in the region, there must be many populations present. Turloughs are mainly periodic waterbodies occupying depressions in the drift overlying limestone. Most of them dry every year, and the bottoms are then used for grazing cattle. This periodicity prevents the establishment of fish populations, which would rapidly eliminate the cladoceran by size‐selective predation. Only one of the many populations known from Western Europe survives in the presence of fishes. A species of the glacialis group in Newfoundland (not yet described), which is the southernmost known location of E. glacialis sens. lat. in the world, occurs commonly with salmonid or gasterosteid fishes, but this is a completely different species. Scanning electron micrographs of E. glacialis and E. lamellatus in Western Europe will aid in understanding their morphological differences.
Influence of Seiche‐Generated Light Field Fluctuations on Phytoplankton Growth
Authors: Paul Lothar 
Published: February 2007

AbstractPhytoplankton, owing to the periodic ascent and descent caused by internal seiches, is exposed to experiential fluctuations in light intensity. The increase in light intensity associated with its ascent towards the surface is greater than the decrease caused by its descent. A simple mathematical model is used to derive relationships showing that 1) the mean light intensity in an epilimnion influenced by internal waves is not more than 6.1% lower than in a stationary system and 2) in the meta‐ and hypolimnion of lakes of low transparency (i.e. with a high extinction coefficient) internal seiches of large amplitude increase the mean light intensity by several orders of magnitude. This can produce a many‐fold increase in the depth of the euphotic zone. The mean rates of photosynthesis of phytoplankton in the meta‐ and hypolimnion increase particularly at the antinodes of the waves. Internal seiches evidently may play an important role in causing plankton patchiness and in the presence of photosynthetically active phytoplankton at depths far below the 1% light limit.
Phytoplankton Analysis in Lake Sat Tal (U.P.), India
Authors: Pant M. C. , Joshi Archana 
Published: February 2007

AbstractSpecies composition and periodicity of phytoplankton were studied in relation to various physico‐chemical parameters over a period of 18 months in the two basins of Lake Sat Tal. Taxonomic analysis led to 54 species. Phytoplankton density in the euphotic zone ranged from 0.33 × 105 to 4.12 × 105 cells I‐1 in the western basin (WB) and 1.31 × 105 to 6.05 × 105 cells I‐1 in the eastern basin (EB). The dinoflagellates (Peridinium willei, P. cinctum, Gymnodinium fuscum) which were relatively insignificant concerning number reached very high values concerning biomass, contributing 89 % and 92 %, respectively, to the total phytoplankton standing stock. Various factors as rainfall, light, temperature, organic matter, nutrients (particularly PO4‐P), silicate, were observed to play an important role in the periodicity of phytoplankton. Similarity coefficients revealed that the algal population was not very homogenous all the year round with similarities between consecutive samples ranging from 16 % to 77 % in WB and 21 % to 76 % in EB.
Feeding Ecology of the Allochthonous Feeder Rasbora daniconius (HAMILTON) (Cyprinidae – Teleostei)
Authors: Kumar K. Prem , John P. A. 
Published: February 2007

AbstractSeasonal fluctuations in the dietary components of Rasbora daniconius inhabiting a perennial eutrophic pond have been studied on the basis of analyses of the gut contents over a period of one year from 1980 to 1981. Modified Points method was adopted for the quantitative estimation of the dietary items. Gut analysis revealed that the fish is predominantly an allochthonous feeder subsisting mainly on terrestrial Hymenoptera and Coleoptera. Flowers and seeds also formed part of the dietary composition of the fish. Allochthonous fauna were preferred at all the stages of the growth of the fish. Females have a greater preference for terrestrial Coleoptera and the males for Formicidae. The feeding intensities of three different length groups and both sexes were also ascertained. This revealed that June, July, October and November are the most intensive feeding periods of R. daniconius. Older and mature fishes were found to be more active feeders than juveniles.
Vergleichende Emergenzstudien an einem naturnahen und einem naturfernen Abschnitt des Fließgewässersystems der Fuhlenau in Schleswig‐Holstein
Authors: Böttger Klaus , Holm Uwe , Mikowski Karol 
Published: February 2007

Comparison of Insect Emergence from Natural and Artificially Modified Sections of a Stream, the Fuhlenau, in Schleswig‐HolsteinThere are no detailed reports in the literature concerning the relationships between the degree to which artificial conditions along a stream have replaced natural ones and the zoobenthos colonization. The ecological effects of mechanical disturbances from channelization, maintenance, or similar activities are given as causes of reductions in individual abundances and species diversity. The ecological effects are essentially more complex and should be determined separately for each of the individual taxa. The conclusions are based on emergences recorded in traps during a six month period from May to October.
Reaeration of Oxygen in Shallow, Macrophyte Rich Streams: I – Determination of the Reaeration Rate Coefficient
Authors: Thyssen Niels , Erlandsen Mogens , Jeppesen Erik , Ursin Christian 
Published: February 2007

AbstractThe rate coefficient K2 for the exchange of oxygen between flowing water and the atmosphere (reaeration) has been studied in six Danish streams covering a relatively wide range of hydraulic conditions, pollutional loading, and macrophyte abundance. 103 K2‐measurements were performed in 1978–85.82 measurements were obtained applying 5 different indirect methods all balancing the sources and sinks of stream dissolved oxygen under conditions of normal operation of the system (3 methods) and under artificial depletion of the oxygen concentration of the stream water by addition of sodium sulphite (2 methods). 21 K2‐values were determined directly applying a gaseous tracer (krypton‐85) for reaeration.Guidelines for selecting a proper method to determine K2 knowing macrophyte biomass and loading characteristics of the particular stream are provided.
Aquatic Ecosystem Characterizations by Biotic Indices
Authors: Guhl Walter 
Published: February 2007

AbstractThe suitability of various biotic parameters for the quality characterization of bodies of water was assessed with the aid of three real world examples which were furthermore characterized physically and chemically.A number of biotic indices such as the Wright and Tidd index and the Chandler biotic score proved unsuitable since they take only parts of the biocenoses into account.All diversity indices, e.g., the Simpson and the Shannon index, proved inadequate as well since elements essential for the description of a biocenosis are lacking.The saprobity index proved fully useful and correct for the biological characterization of bodies of water. Similarity indices such as the Sørenson index may furnish valuable additional information.
The Influence of Crustacean Zooplankton on the Size Structure of Algal Biomass and Suspended and Settling Seston (Biomanipulation in Limnocorrals II)
Authors: Uehlinger U. , Bloesch J. 
Published: February 2007

AbstractIn a limnocorral (LC) experiment performed in mesotrophic Lake Lucerne, Switzerland, a control LC containing a planktonic community similar to that in the lake was compared with a LC where the large zooplankton had been removed by filtration at the beginning of the experiment. The herbivorous zooplankton (mainly Daphnia galeata and D. hyalina) reduced algal biomass and primary production, however did not influence the size structure of the phytoplankton and the relative amount of different size classes contributing to the total primary production. Likewise, the seston (POC and PP) concentrations were diminished without changes in particle size composition. Since herbivorous zooplankton transform smaller particles into larger particles (fecal aggregates) through their grazing activity and thus enhanced particle formation owing to coagulation and microbial activity, sedimentation losses of POC and PP were increased in the LC with zooplankton. The importance of planktonic and sestonic particle size structure in aquatic ecosystems is stressed, as the smallest algae (< 12 μm) contributed 80 % of the primary production, which is in contrast to the 33 % contributed to the total POC sedimentation by this particle size class.
Macrobenthic Distribution within the Sediment along an Estuarine Salinity Gradient
Authors: Dauer Daniel M. , Ewing R. Michael , Rodi Anthony J. 
Published: February 2007

AbstractThe distribution of the macrobenthic infaunal community within the upper 25 cm of the sediment was studied at 16 stations in the lower Chesapeake Bay. Stations were located from the tidal freshwater to the polyhaline zone of major tributaries (James, York and Rappahannock Rivers) and in the polyhaline portion of the lower bay mainstem. Profiles for total number of individuals, total ash‐free dry weight biomass and species encountered with depth were calculated. Except for the deep dwelling bivalve, Macoma balthica, tributary macrobenthic communities had a shallow depth distribution compared to the mainstem sites which were found in generally coarser sediments in the higher salinity region of the estuary.
Approche discriminante de contributions de différents échelons microplanctoniques aux mesures globales d'ETS dans des échantillons de mer. b. Bacteria
Authors: Romano Jean‐Claude , Laborde Pierre , Mimura Toru , de Souza‐Lima Yolanda 
Published: February 2007

Discriminating approach of various microplanktonic‐stage contributions to whole electron transport system (ETS) measurements in sea‐water sampless. b. BacateriaData obtained from cultures of natural bacterial populations were applied to various water samples in order to determine both the phytoplanktonic and bacterial contributions to whole ETS water‐sample measurements. The bacterial part was estimated both by cell enumerations and HPLC muramic‐acid measurements and the phytoplankton contribution by enumeration and chlorophyll levels. An appropriate first‐order equation is adequate to low carbon content samples but must be corrested for highly organic loaded samples in order to obtain a better adjustment between the sum of the “estimated” phytoplanktonic and bacterial ETS and the really‐measured ETS concentrations in the water samples.
Oxygen Budget of a River Rich in Submerged Macrophytes (River Zschopau in the South of the GDR)
Authors: Müller J. , Weise G. 
Published: February 2007

AbstractThe oxygen budget of the river Zschopau, a flowing water typical of hilly areas in the south of the GDR, was investigated in regard of seasonal variations in the activity of submerged macrophytes. Oxygen concentrations were continuously measured in the river by means of electrodes. Seasonal activity patterns of Ranunculus penicillatus, the dominant macrophyte in the river stretch investigated, were found by laboratory experiments.The oxygen budget was obtained by measuring CO2 concentrations by infrared gas analysis (IRGA) and CO2 and O2 concentriations by means of electrodes.
Growth of Tubifex tubifex Müller (Oligochaeta, Tubificidae) under Various Trophic Conditions
Authors: Finogenova N. P. , Lobasheva T. M. 
Published: February 2007

AbstractGrowth of Tubifex tubifex on highly caloric activated sludge and poor in organic matter natural silt was experimentally studied. The relationship between oxygen consumption rate, weight, and caloric value of T. tubifex body in culture on activated sludge was determined to calculate the growth efficiency (K2 = P/P + R). The growth rate has been determined, and models of T. tubifex growth are given under various trophic conditions conforming to results of the experiment. Somatic growth, generative growth and life span of this species were compared on the basis of the experiments and literature. Acceleration of growth and prolongation of life under conditions of caloric food and delay of these processes in silt poor in organic matter have been established and measured. T. tubifex was found to have advantages as compared to other tubificid species in response to increasing amounts of nutrient food in waters polluted by organic matter and, therefore, to produce abundant populations under these conditions.
Toxicity of an Anionic Detergent to the Spawn and Larvae of Anurans (Amphibia)
Authors: Plötner J. , Günther R. 
Published: February 2007

AbstractSeveral experiments were performed to test the toxicity of FIT, a washing‐up and general cleaning liquid containing about 10 % sodiumalkanemonosulfonate (industrial name E 30) to spawn and larvae of anura. The LC50 values for spawn were between 1.62 × 10−3 % (Rana dalmatina) and 4.97 × 10−3 % (Rana temporaria). The sensitivity of anuran larvae depends on the concentration and duration of exposure to the detergent as well as on the developmental and differentiation stage of the organisms. The toxicity of FIT is not due solely to the alkanesulfonate it contains, but results from the joint action of the surfactant, polyphosphates and solvents.The results indicate that detergents may be harmful to the amphibian fauna of Central Europe.
Seasonal Variations in some Physical and Chemical Properties of Water from an Undisturbed African Tropical Catchment Area (Guma Valley, Sierra Leone)
Authors: Mtada Obed S. M. 
Published: February 2007

AbstractFour perennial streams in a completely forested area were investigated. The water cooled and warmed up during both the rainy and dry seasons. The chloride content of the water varied according to rainfall. Dissolved solids were relatively high (20 mgl−1) at the start of the rainy season due to leaching but they were diluted with increased volume of flow. Dissolved gases and BOD5 varied according to discharge and total suspended solids content. All the other chemical species likewise were subject to seasonal variations.
Interrelations between phytoplankton, submerged macrophytes, black swans (Cygnus atratus) and zooplankton in a shallow New Zealand lake
Authors: Mitchell S. F. , Hamilton D. P. , Macgibbon W. S. , Nayar P. K. B. , Reynolds R. N. 
Published: February 2007

AbstractDifferent features of the limnology of Tomahawk Lagoon, a shallow, hypertrophic New Zealand lake were studied for varying periods between 1964 and 1986. Surveys in 10 years revealed a strong positive correlation between the winter black swan population and the biomass of macrophytes which in turn in a shorter study was inversely related to the abundance of phytoplankton. A regression model was developed relating the winter maximum swan population to phytoplankton productivity in the previous summer. The model worked well for another very shallow lake, but less well for a third lake with a mean depth greater than the feeding reach of swans.No general mechanism could be established for suppression of phytoplankton when macrophytes were abundant, though the effect was large. Suppression of macrophytes in other years is attributed to shading by phytoplankton. The decline of one algal bloom was related to nitrogen deficiency followed by intense zooplankton grazing. Another was ended by the optical effects of a large flood‐borne silt inflow and flushing of phytoplankton. Empirical models relating chlorophyll a to phosphorus or nitrogen, and zooplankton biomass to chlorophyll a or phosphorus do not work well for this lake, and the general problems of modelling shallow highly eutrophic lakes are discussed.
Comments on the manna model
Authors: Walker I. 
Published: February 2007

AbstractWANGERSKY and WANGERSKY'S (1980, 1981, 1983) Manna models on algal patchiness and competition are essentially stochastic models. Analysis of their phase‐spatial properties, however, reveals complementary, deterministic features: interspecific competition is relatively ineffective because of the high degree of compartmentalization of resource supply and consumption; the probability of consumption in a given place at a given time is largely independent of the rate of consumption in other places.
A Long Term Study of the Phosphorus Cycle in Lough Neagh, Northern Ireland
Authors: Gibson C. E. , Smith R. V. , Stewart D. A. 
Published: February 2007

AbstractEleven years of weekly observations on the phosphorus cycle in Lough Neagh are analysed. The data comprised inputs, outputs and lake concentrations of the soluble and particulate phosphorus fractions. It is shown that the particulate phosphorus input quickly sediments to the bottom and the particulate phosphorus in the lake is largely made up of phytoplankton. The average phosphorus retention in the lake was 34 %, similar to the particulate phosphorus input. Climate has a big influence on the phosphorus input and sediment release, both of which varied two‐fold. A simulation model suggested that suppression of sediment P release would reduce lake winter phosphorus concentrations by an average of 29 %.
The Significance of the Internal Nutrient Load to Hypertrophic Shallow Waters
Authors: Uhlmann Dietrich , Guyderitz Thomas 
Published: February 2007

AbstractIn two carp ponds with a long water residence time, the seasonal changes in concentration and internal mass‐flow of inorganic nutrients have been estimated together with oxygen production PN of phytoplankton and community respiration. The results were compared with the findings from laboratory microcosms (LM) with a high recycle rate between a) euphotic and b) aphotic + sediment compartment. In the LM's, a dark period of at least 12 hours was necessary for optimum remobilization of CO2, PO− and NH. Very high values of PN were measured even if external nutrient sources were missing. Low nutrient concentrations could be compensated by high vertical fluxes. A cycle of nocturnal mixing and of thermal stratification with anoxia at the mud water interface which increases nutrient regeneration seems to be the principal mechanism which maintains very high PN in hypertrophic shallow waters.
The Biogeography of Cladocera (Crustacea) in Tropical Australia
Authors: Timms B. V. 
Published: February 2007

AbstractNinetysix species of Cladocera, comprising 8 Sididae, 50 Chydoridae, 17 Macrothricidae, 5 Moinidae, 2 Bosminidae, and 14 Daphniidae, occur in tropical Australia. Of this number 38% are cosmopolitan including so‐called cosmopolitan species, 13.5% are circumtropical, 13.5% occur as well innear by countries, and 35% are endemic. North Queensland is a major area of speciation. Species richness varies from north to south and from wetter coastal areas to the drier inland. Major factors influencing richness and distribution are the relative proportion of floodplain billabongs in an area, coupled with rainfall reliability. The most common species include Alonella clathratula, Chydorus nr. pubsecens, Macrothrix triserialis, Oxyurella singalensis, Ephemeroporus nr. barroisi, Dadaya macrops, Diaphanosoma sarsi, Ceriodaphnia cornuta, and Dunhevedia crassa.
An Experimental Analysis of the Acid Sensitivity of the Common Planktonic Rotifer Keratella cochlearis
Authors: Havens Karl , Decosta John 
Published: February 2007

AbstractAn in situ mesocosm experiment was performed at neutral pH Lake O'Woods, West Virginia, to assess the impacts of acidification on the common planktonic rotifer Keratella cochlearis. This rotifer is typically replaced by K. taurocephala during the acidification of North American lakes. Despite a rapid pH reduction in this experiment (from 7.0 to 4.8 in 14 days), the abundance, mean body length and egg ratio of K. cochlearis did not decline in the acid treatment as compared to the untreated control. These results support the hypothesis that K. cochlearis is acid‐tolerant, and suggest that its disappearance from acid lakes is the result of biotic interactions within the plankton, rather than the result of toxic effects of altered water chemistry.
Chlorophyll Concentrations in Relation to Environmental Parameters in Different Situations in Shoal Lake (Manitoba‐Ontario)
Authors: Pip Eva 
Published: February 2007

AbstractSeasonal and local chl a fluctuations were examined at two depth ranges in Shoal Lake, a productive Precambrian Shield system. Water residence time in the study area was short, without permanent summer stratification. Chl a fluctuations were significantly correlated with total molybdenum reactive phosphorus (MRP) and total inorganic nitrogen (TIN), but the types of relationships were different for the two nutrients. Chl a was also significantly positively correlated with total alkalinity and temperature, and inversely correlated with oxygen and light. MRP and dissolved organic matter appeared to be more important for near‐bottom chl than for surface chl. Principal component analysis identified 4 major dimensions in which the different locations could be compared in terms of seasonal chl a fluctuations.
Biological Assessment of the Water Quality in South‐Holland (The Netherlands)
Authors: Klapwijk Sjoerd P. 
Published: February 2007

AbstractA hydrobiological study was carried out to elaborate the water quality classification system of CASPERS & KARBE (1966, 1967) for the larger stagnant bodies of water in the western part of the Netherlands. Significant correlations have been established between different physical and chemical parameters and phytoplankton community structures such as diversity and saprobity. From this a proposal is developed to quantify the water quality classes in CASPERS & KARBE'S scheme on parameters measuring the bioactivity, oxygen regime and phytoplankton community structure. The scheme is now incorporated in the practical water quality assessment in North‐ and South‐Holland both for routine monitoring as well as for special water quality studies.