bluuebunny/crossref_metadata_2025_split huggingface dataset:
Embryonic development, larval growth and life cycle of Coenagrion puella (Odonata: Zygoptera) from an Austrian pond
Authors: WARINGER J. A. , HUMPESCH U. H. 
Published: May 2006

SUMMARY. 1. Newly‐laid eggs of Coenagrion puella (L.) from a pond near Herzogenburg (Lower Austria) were kept at constant water temperatures (range c.3.5°C to c.28°C)in the laboratory. Hatching success varied with temperature; no eggs hatched below 12°C and nearly all hatched at c.l6°C. Hatching time decreased with increasing temperature and the relationship between the two variables within the range 12–28 °C was well described by a power law. The length of the hatching period was less than 12 days. Hatching times estimated from the power‐law equations and those obtained in the field experiments were similar. Therefore both the hatching time and the length of the hatching period in the field could be estimated from the laboratory data for the range 12–28°C.2. The maximum number of instars from egg to imago was 11; the average body length increment (mm) per moult was proportionately constant at c.26% and Dyar's rule was applicable. The interval between moults decreased with increasing temperature up to the seventh instar and the relationship between the two variables within the range 12–28°C was well described by a power law. The moulting interval for instars 8–11 ranged from 23 to 48 days and was relatively independent of temperature. No moulting occurred at temperatures below 12°C.3. Larval growth was logistic in the laboratory and variations in mean logistic growth rate (range 0–2.5% length day−1) were related to mean temperature with no growth at temperatures <12°C. Larval growth rates in pond experiments were similar to those estimated from laboratory data, and therefore the regression equations obtained from the laboratory experiments are probably applicable to larval growth in the field.4. Information on the life cycle of C. puella is briefly reviewed and it is concluded that C. puella from the pond near Herzogenburg has an univoltine life cycle.
Assay for biologically available phosphorus using proteolytic Aeromonas hydrophila
Authors: RATSEP A.I. , SJOGREN R. E. 
Published: May 2006

SUMMARY. 1. A simple and inexpensive assay was developed to determine the amount of biologically available phosphorus (BAP) present in freshwater.2. BAP was measured by using Aeromonas hydrophila in a proteolytic assay system in which the release of the chromogen from an insoluble azure dye derivative of hide powder (HPA) was determined spectrophotometrically. The time necessary to hydrolyse 50% of the HPA was found to be directly dependent on the amount of BAP present. BAP within the range 2–250 μg 1−1 phosphate‐phosphorus was detected.3. Our data suggest that the application of this assay for the measurement of BAP in freshwater offers the potential of monitoring the biological response of a freshwater ecosystem to phosphorus.
Spatial variations in the water quality of Lough Erne, Northern Ireland, on the basis of surface sediment diatom analysis
Authors: BATTARBEE RICHARD W. 
Published: May 2006

SUMMARY. 1. Constrained cluster analysis of thirty‐five surface sediment diatom assemblages shows that Lough Erne, a complex multi‐basin lake in Northern Ireland, can be sub‐divided into four main zones.2. All areas of the lake system have planktonic diatoms typical of eutrophic lakes but the lack of small Stephanodiscus species in zone 4 suggests that this area of the system is least productive.3. Surface sediment diatom assemblages can be used to assess spatial variations in complex lake systems and can thereby be used as a guide to the choice of sites for water quality monitoring and sediment coring.
The relationship between food particle size and larval size in Simulium noelleri Friederichs
Authors: WOTTON R.S. 
Published: May 2006

SUMMARY. 1. In a laboratory experiment, larvae of Simulium noelleri were fed on polystyrene latex microspheres of a range of diameters from 5 to 100 μm.2. Examination of the particle size distribution in the water used in the experiment showed those <13μm to be the most numerous (87% of all particles present). Particles of this size made up 57±2% (mean ±SE)of the total of those in the gut of larvae.3. Comparison of particle composition in the gut contents and the water of the experiment, using Jacob's index of electivity, showed that larvae of all sizes filtered proportionally fewer of the particles <13 μm and more of those >13μm.4. As larvae increased in size they became better able to filter the largest particles present (>52μm in diameter) and less well able to filter the smallest particles (<13μm in diameter).5. Gut retention time was longer in larger larvae.6. The biology of S. noelleri, which inhabits lake outlets in high population densities, is considered in the light of these findings.
Adenylate energy charge in streambed sediments
Authors: KAPLAN LOUISA , BOTT THOMAS L. 
Published: May 2006

SUMMARY.

The adenylate energy charge (ECA) of microbial communities from streambed sediments was measured during three different seasons, under experimental manipulation and in culture.
The ECA values of sediments (x±S.E.) in the autumn, winter and spring were low and constant; 0.22±0.03 (n=12), 0.32±0.04 (n= 12) and 0.28±0.03 (n=6) respectively.
A 5 h exposure of sediments to an algal lysate at 3.0–4.0°C and a 48 h exposure of sediments to tryptone‐yeast extract at 8.0–18.0°C failed to increase ECA even though respiration increased 3.7‐fold during the latter exposure.
The cellular ECA of a bacterial monoculture, sampled in log phase, was 0.90±0.10 (n=3), but cxtracclluhir AMP depressed the total culture ECA to 0.21±0.01 (n=4).
Attempts to isolate extracellular AMP from the interstitial waters of sediments were unsuccessful.
The data suggest that under natural conditions ECA is of limited use as a monitor of subtle changes in the physiological state of microbial communities in streambed sediments.
Uptake of phosphate and inorganic nitrogen by a sediment‐algal system in a subarctic lake
Authors: BJÖRK‐RAMBERG SUSANNA 
Published: May 2006

SUMMARY.

The uptake of phosphate and inorganic nitrogen by sediment and phytoplankton was studied under natural conditions (1977) and during lake fertilization with phosphorus and nitrogen (1978–79) in Lake Gunillajaure, a small, stratified, subarctic lake in northern Sweden. The experiments were performed in situ in plexiglass cylinders, to which additions of nutrients were made, and the uptake followed by consecutive sampling and analysis of the water phase.
Additions of HgCl2 to the experimental vessels reduced the phosphate uptake to the sediment to less than 10% and it could therefore be concluded that the sediment uptake was mainly of biological nature.
Dark assimilation was 30–40% of that in light. Since light clearly stimulated the sediment uptake the epipelic algae were probably responsible.
The phosphate uptake to the sediment could be described by Michaelis‐Menten kinetics and the calculated constants (Vmax, ks) were very alike in 1977 and 1978 but appeared to have increased in 1979.
The sediment uptake of ammonium and nitrate was very slow indrcating that the epipelic algae were not nitrogen starved.
Even though the epipelic algae had a potential for efficient uptake of phosphorus, the phytoplankton took up 92–96% of the phosphate added to the lake on each fertilization occasion due to the relatively large water volume in the epilimnion in relation to the bottom area available for the epipelic algae.
Aspects of nitrogen fixation in Lough Neagh. II. Competition between Aphanizomenon flos‐aquae, Oscillatoria redekei and Oscillatoria agardhii
Authors: RIDDOLLS ANTHEA 
Published: May 2006

SUMMARY.

The effect of nutrient availability on the growth of natural samples of Lough Neagh plankton (Aphanizomenon flos‐aquae, initial innoculum 0.98 mm3 l‐1, Oscillatoria redekei, 2.52 mm3 l‐1 and Oscillatoria agardhii, 4.96 mm3 l‐1) was studied, using ecologically realistic conditions of temperature (15°C), nitrate‐N (<0.35g m‐3) and orthophosphate‐P (<0.55g m‐3), in which the combinations –N–P, –N+P, +N–P, and +N+P were used.
After 8 days A. flos‐aquae had become dominant in treatments lacking N. After 12 days with N available the mean yields of O. redekei (37.7 mm3 l‐1) and O. agardhii (10.82 mm3 l‐1) were significantly greater (P=5%) than their respective yields (3.6 and 2.6 mm3 l‐1) in the absence of N. Somewhat surprisingly the mean yield of A. flos‐aquae when N was present (0.15 mm3 l‐1), was significantly less (P=5%) than in the absence of N (13.26 mm3l‐1).
The relative rates and duration of growth, the availability of P and N, and heterocyst frequency as an index of nitrogen fixation are considered in relation to the seasonal succession and dominance of these three principal cyanophyte members of the Lough Neagh phytoplankton.
Distribution, biomass and production of the freshwater mussel, Hyridella menziesi (Gray), in Lake Taupo, New Zealand
Authors: JAMES M. R. 
Published: May 2006

SUMMARY.

A study of the distribution, biomass and production of the freshwater mussel Hyridella menziesi (Gray) was carried out at six sites in Tapuaeharuru Bay, Lake Taupo, New Zealand.
H. menziesi is common in the littoral zone, with clean sand and angle of slope being the most important environmental variables measured which are positively associated with mussel density. These variables are related to the accumulation of fine material which can clog the filtering mechanism of mussels. The angle of slope may also influence the movement and supply of food.
Density (5.6 m‐2), biomass (2.8 g dry weight shell free tissue m‐2) and potential production (0.50 g dry weight shell free tissue m‐2 yr‐1) are high compared to values found for mussels from other oligotrophic lakes.
The age structure of Hyridella suggests recruitment has declined in recent years. A periodicity in generations is proposed.
The organization of macroinvertebrate communities in the major tributaries of the LaTrobe River, Victoria, Australia
Authors: MARCHANT R. , METZELING L. , GRAESSER A. , SUTER P. 
Published: May 2006

SUMMARY.

Seventeen sites were each sampled six times over 2 years for macroinvertebrates. A range of physicochemical variables was also measured to determine which factors were related to the distribution of species.
Numerical classification of the faunal data indicated that four groups of sites or communities were distinguishable: lowland sites; sandy upland sites; cobble upland sites from the northern catchment; cobble upland sites from the southern catchment.
Multiple discriminant analysis and multiple regression analysis demonstrated that particle size of the sediment, concentration of dissolved ions and altitude were the physicochemical features that were most strongly associated with changes in the faunal distribution.
Abundances of shredders and predators did not vary between the site groups while those of scrapers, gatherers and filterers did: scrapers were most abundant at cobble sites while gatherers and filterers were least abundant on sand and increased in abundance downstream. The distribution of the feeding groups showed some similarity with that predicted by the River Continuum Concept, but the fact that the shredders did not decrease in abundance downstream was a notable difference.
Abundance of the total fauna at a site was inversely related to the amount of benthic organic matter. This feature is contrary to the pattern usually reported from rivers in the northern hemisphere.
The role of lipids as feeding stimulants for shredding aquatic insects
Authors: CARGILL AUSTEN S. , CUMMINS KENNETH W. , HANSON BOYD J. , LOWRY ROBERT R. 
Published: May 2006

SUMMARY.

Caddisflies (Trichoptera) that shred leaf detritus preferentially ingested lipid‐coated detritus during the last larval in star. This is the interval when these insects accumulate the triglyceride reserves necessary for metamorphosis and reproduction. Early in star larvae, which do not accumulate lipids, showed no preference for any lipids. This behaviour indicates food selection based on changing nutritional needs.
Pure unsaturated 18‐ and 20‐carbon fatty acids, either as free acids or triglycerides, were most strongly preferred. Crude lipid and the neutral lipid fraction from aquatic hyphomycete fungi, an important component of aquatic leaf detritus, were also preferred.
Tipula abdominalis (Diptera: Tipulidae) did not prefer any lipids during the last instar.
Spatial variations in and controls on the calcite saturation index in Acton Lake, Ohio
Authors: GREEN WILLIAM J. , CANFTELD DONALD E. , STEINLY BRUCE A. 
Published: May 2006

SUMMARY.

Acton Lake is a small, hardwater, eutrophic reservoir located in the southwestern corner of Ohio. Over a period of 5 weeks in mid‐summer 1979, water samples were collected from the lake and its streams and analyzed for seven major ionic species and for temperature, dissolved O2, pH and conductivity. Geochemically the waters are characterized by high calcium and bicarbonate concentrations.
Data obtained on all samples were used to compute calcite saturation indices (SI) and to map the spatial distribution of this function throughout the system. The saturation indices were corrected for activity and ion pairing effects and yet are still to our knowledge among the highest values reported for a natural water.
The good correlations obtained between the SI and both the pH and dissolved oxygen clearly indicate that biological activity is the dominant control on the degree of saturation in this largely isothermal lake. To account for the extreme departure from chemical equilibrium, it is proposed that dissolved organic matter may be poisoning freshly formed calcite surfaces and preventing them from serving as effective nucleation centers.
Formation of thermal stratification in a small temperate lake
Authors: SZUMIEC MARIA ANNA 
Published: May 2006

SUMMARY.

The origin of vertical temperature stratification in Erstwhile Water (Lake District, Cumbria, England) was observed.
At the first stage of the spring warming of the whole water column some discontinuity in the vertical temperature distribution appears in the surface and bottom layers.
Persistent summer stratification occurred for the first time at the lee end of the lake immediately after a change of wind direction, when the cumulative potential energy deficit dominated the cumulative kinetic energy by about 110‐8 Jcm‐2.
The results show the importance of the proper choice of initial conditions in computations of total energy, as well as the necessity to consider the spatial distribution of potential and mechanical energy responsible for the summer stratification in the lake.
The effects of vegetation removal by grass carp and herbicides on the water chemistry of four Florida lakes
Authors: SMALL JAMES W. , RICHARD DAVID I. , OSBORNE JOHN A. 
Published: May 2006

SUMMARY.

Four lakes in central Florida each received a different weed control treatment consisting of herbicide and/or different stocking ratios of grass carp (Ctenopharyngodon idella Val.).
Submersed vegetation was eliminated by grass carp within 6 months In Lake Orienta and within 14 months in Clear Lake. Because Little Lake Fairview, treated with herbicide and a smaller stocking ratio of grass carp, retained abundant vegetation levels over the first two study years, grass carp which had been introduced initially were replaced with a greater number of fish at the beginning of the third year. Submersed vegetation was subsequently eliminated in this lake within LO months. Aquatic vegetation was reduced but not eliminated in Lake Mann which was treated with herbicide only.
Where macrophytes were removed there tended to be increased bottom dissolved oxygen, higher and more stable total alkalinity values, increased turbidity, lowered transparency, higher specific conductivity and increased chlorophyll levels. Significant increases in pH were probably due to low water levels resulting from a severe drought rather than weed control. Low water also affected specific conductivity. Annual means for nutrients did not differ significantly between years in the four lakes.
Feeding efficiencies of Chironomus plumosus (L.) and C. anthracinus Zett. (Diptera: Chironomidae) in mesotrophic Lake Erken
Authors: JOHNSON RICHARD K. 
Published: May 2006

SUMMARY.

Absorption efficiencies of nitrogen and carbon in two Chironomus species found dominating in the profundal zone of mesotrophic Lake Erken were determined gravimetrically.
Absorption efficiencies for C. plumosus showed greater seasonal variation than those of C. anthracinus, with low efficiencies coinciding with the summer dominance of flagellate phytoplankton and with high C:N ratios.
Overall mean absorption efficiencies (±SE) for carbon and nitrogen, respectively, were 26.8% (±1.9) and 29.3% (±1.9) for C. plumosus, 24.6% (±1.7) and 28.1% (±1.8) for C. anthracinus.
Significant differences were found to exist between the C: N ratios of the superficial 2 cm sediment layers and those of Chironomus anterior midgut contents.
C. anthracinus appears to be a deposit feeder ingesting particulate matter scraped from the recently deposited surface sediments. The greater seasonal variation found in the absorption efficiencies of C. plumosus, together with the lower C:N ratios, support the contention that this species is a filter feeder with the nutritional quality of ingested matter depending primarily on pelagic inputs.
Limnological investigations on the Rosetta branch of the Nile. II. Seasonal variations of nutrients
Authors: SAAD MASSOUD A H. , ABBAS MAHDI H. 
Published: May 2006

SUMMARY.

Nitrate tended to be low in the estuarine region compared with the freshwater stretches and seasonally was low in October. Nitrite broadly showed patterns similar to NO3 but at lower values.
Reactive phosphate and silicate tended to be much higher in fresh compared with saline stretches and was high in January.
These changes are broadly interpreted in relation to river discharge and the seasonality of phytoplankton although other, and as yet unstudied, causes will probably be found to be involved.
Fine‐layer depth relationships of lakewater chemistry, planktonic algae and photosynthetic bacteria in meromictic Lake Fidler, Tasmania
Authors: BAKER ALAN L. , BAKER KATHLEEN KROMER , TYLER PETER A. 
Published: May 2006

SUMMARY.

Use of a multi‐column thin‐layer pneumatic sampler and modified analytic procedures has enabled resolutions of chemical and biological strata at 2.5 or 5.0 cm depth intervals. Examination of meromictic Lake Fidler, Tasmania, indicates the presence of a thin, intense stratum of bacteriochlorohyll d in the upper monimolimnion, associated with a discrete stratum of Chlorobium cf. limicola at the microaerobic interface between the oxygenated and sulphide‐rich zones.
Algae included small populations of Chlorophyceae, Chrysophyceae, Bacillariophyceae and Cryptophyceae. Bacteria included microaerophils and obligate anaerobes, pigmented and colourless, in well‐defined strata in the upper monimolimnion. A population of the microcrustacean Calamoecia tasmanica tasmanica was present in the mixolimnion. Chaoborus larvae were concentrated within the Chlorobium layer.
The chemical profile of Lake Fidler was stable, with a chemocline constant in position relative to the lake bottom. The surface water levels rose and fell through a distance of 1m in conjunction with heavy rainfall in the rainforest, and with river level variation, but had no measurable effect on the absolute position of the chemocline. Marked heterogeneity of dissolved substances at depths in the vicinity of bacteria suggested endogenous influence on pH and gelbstoff (‘gilvin’ in Australia).
Downwelling light attenuation was influenced primarily by gelbstoff (‘gilvin’) in the mixolimnion, with only red light (peak at 700 nm) measurable below 2 m. Light was absorbed mainly by Chlorobium in the monimolimnion, and was unmeasurable deeper than 3 m.
The absorption spectrum of the bacteriochlorophyll d in vivo, with a maximum absorbance at 721 nm, corresponds with the available downwelling light penetrating the mixolimnion to the Chlorobium layer.
The retrieval of material from the surface micro layer with screen and plate samplers and its implications for partitioning of material within the micro layer
Authors: ESTEP K. W. , MAKI J. S. , DANOS S. C. , REMSEN C. C. 
Published: May 2006

SUMMARY.

The surface micro layers of two small ponds in Wisconsin were sampled over several years using screen and plate samplers. These devices performed identically for dissolved substances but for particulate material the glass plate sampler produced values 4 times those obtained with the screen.
These differences in sampling efficiency are probably the result of the failure of the screen sampler to release all of the particulate material it has collected and also to differences in the partitioning of dissolved and particulate material within the micro layer.
Results suggest that particulates are concentrated at the air‐water interface and that there is a four‐fold dilution with subsurface water in the screen samples when compared to the plate samples. Dissolved material, in contrast, is concentrated in a thicker layer below the surface mono layer, resulting in equal sampling efficiency with the plate and screen samplers.
Predator‐prey ratios in communities of freshwater invertebrates: the role of enemy free space
Authors: JEFFRIES M. J. , LAWTON J. H. 
Published: May 2006

SUMMARY.

The ratio: number of predator species/number of prey species is reviewed using comprehensive faunal lists for a range of freshwater habitats in Britain and North America. Prey species are defined as detritivores, herbivores and fungivores; predators eat metazoan animals as the main component of their diet. Our data refer only to invertebrates.
The numbers of predators and prey species are apparently very closely correlated in freshwater communities (r=0.84, In transformed data), with an average ratio of predators to prey of 0.36. The average ratio of predators to prey changes from 0.48 in small (species‐poor) collections to 0.29 in large (species‐rich) collections.
We suggest that an approximately constant ratio of predators to prey may be generated by: (a) the number of predator species being a function of the number of broad classes or kinds of prey; and (b) the number of prey species being constrained by competition between prey for ‘enemy free space’, i.e. species that are too similar are unable to coexist with shared predators.
A 25,000‐year history for Lake Victoria, East Africa, and some comments on its significance for the evolution of cichlid fishes
Authors: STAGER J. C. , REINTHAL P. N. , LIVINGSTONE D. A. 
Published: May 2006

SUMMARY. 1. Microfossil and X‐ray analyses of sediment cores from Lake Victoria. East Africa, reveal a history of dramatically shifting environmental conditions over the last 25,000 years.2. The diatom record of a 10 m core collected from beneath 66 m of water at an offshore station extends the known history of the lake 10,000 years beyond the published records from Pilkington Bay and Damba Channel, and shows that maximal late Pleistocene aridity occurred between 15,000 and 13,000 bp. Lack of precipitated carbonates in the offshore sediments suggests that the lake remained relatively dilute throughout the period of record.3. There is no evidence that the lake level fell low enough to confine fishes to refugia in small isolated ponds or around river mouths.