bluuebunny/crossref_metadata_2025_split huggingface dataset:
Handling of coarse and fine particulate organic matter by the aquatic insects Paraleptophlebia gregalis and P. temporalis(Ephemeroptera: Leptophlebiidae)
Authors: MATTINGLY ROSANNA L. 
Published: May 2006

SUMMARY 1. Paraleptophlehia gregalis and P. temporalis were abundant throughout a flow‐controlled section of stream that contained large quantities of fine particulate organic matter (FPOM; 0.45 μm to 1 mm in diameter), and in upstream and downstream areas.2. In laboratory studies, Paraleptophlebia spp. fed and grew on FPOM and CPOM (coarse particulate organic matter; greater than 1 mm in diameter); growth rate was not related to the particle size of food. In addition, these animals were able to survive and grow on various sizes of faecal material produced by shredders.3. Paraleptopblehia spp. consumed relatively large amounts (0.16±0.09 mg per mg animal dry mass) of detrital material daily.4. The mayflies had short gut content passage times (2–3 h) and low efficiencies of conversion of ingested food to body substance (0.08±0.07%). They egested relatively small, amorphous faeces,5. The overall pattern exhibited by Paraleptophlebia spp. involved rapid processing and partial recycling, through relatively simple alimentary tracts, of large amounts of detrital material from a wide range of sources.
Resource utilization, overlap and temporal dynamics in a guild of mountain stream insects
Authors: RADER RUSSELL B. , WARD JAMES V. 
Published: May 2006

SUMMARY 1. Resource utilization was quantified for six mayfly (Ephemeroptera) and one caddis (Trichoptera) species comprising a lotic scraper/collector‐gatherer guild across three niche dimensions (temporal, trophic and spatial). Based on trophic differences and inferred microspatial utilization, the members of this guild separated into two groups: (1) cryptic detritivores and (2) exposed algivores.2. Each species demonstrated a slow seasonal univoltine life cycle except for Epeorus longimanus (Eaton) and Baetis iricaudatus (Dodds) which were fast seasonal univoltine and multivoltine, respectively.3. Temporal sequencing of periods of peak resource utilization were not demonstrated by the members of this guild. A null analysis indicated that periods of peak resource utilization were aggregated.
Short‐term movements of chalk‐stream invertebrates
Authors: PEARSON R. G. , JONES N. V. 
Published: May 2006

SUMMARY 1. Trays of gravel were implanted for 24 h periods in several chalk streams. The trays were variously modified to monitor colonization from different sources, particularly drift (D), other downstream movements (DSM), upstream movements (USM), and all sources combined (ALL).2. The abundance of invertebrates in the streams was high (maximum of 717 per 0.04 m2) and colonization of the trays was extensive, especially by Gammarus pulex, the predominant species in all but one of the streams (maximum number of individuals of G. pulex per tray: for D, 473; for DSM, 462; tor USM, 286; and tor ALL, 639). In some cases benthic densities were achieved in the trays in the 24 h exposure period, and in most cases any one source of colonization could provide benthic densities in a few days.3. Patterns of movement differed between species, between size classes of G. pulex, and between sites for particular species. No one source of colonization could be regarded as generally predominant although downstream movements in total (D + DSM) usually far exceeded USM. DSM was usually an important source of colonization.4. The extent and direction of movement appeared to be determined by local factors and were explained in terms of the high densities of invertebrates and the current and substratum characteristics of each site.5. Estimates of the relative importance of different sources of colonization varied greatly according to the criteria used in determining proportions.
Competition for perches between larval damselflies: the influence of perch use on feeding efficiency, growth rate and predator avoidance
Authors: CONVEY PETER 
Published: May 2006

SUMMARY. 1. In an investigation of perch use by two species of larval damselfies, Coenagrion puella (Linn.) and Ischnura elegans (van der Linden), larvae spaced out on a grid of vertical cocktail sticks, in the absence of food, to a greater extent than expected from a random model. Spacing was the result of direct interaction between larvae, and was not related to the level of hunger of the larvae over a 10 day starvation period.2. Prior ownership of a perch was not a predictor of success in conflicts between larvae of the same instar. In contests between different instars larger larvae were more likely to win conflicts. Some small larvae appear to remain undetected in the presence of larger conspecifies.3. At one level of food availability, perch ownership did not influence growth rate or mortality of C. puella or I. etegans. However, it did allow greater prey capture success rate.4. Coenagrion puella larvae showed more movement in the absence of perches both in terms of actual distance moved and amount of swimming activity. The amount of swimming activity was reduced by addition of a predator (sticklebacks. Gasterosteus aculeatus or Pungitius pungitius) to the tank both in the absence and presence of an alternative food supply for the fish. Duration of individual swimming bouts was unaffected.5. Sticklebacks attacked C. puella larvae significantly more often in the absence of perches, with a strong bias towards swimming larvae.6. It is proposed that the major advantage of perch possession to C. puella larvae is in the reduction of predation as a consequence of the reduction in larval movement.
Modern diatom assemblages in Central Mexico: the role of water chemistry and other environmental factors as indicated by TWINSPAN and DECORANA
Authors: METCALFE S. E. 
Published: May 2006

SUMMARY. 1. Modern diatom samples, for which physical and chemical environmental conditions were recorded, were collected from forty‐seven sites across Central Mexico2. The results of the diatom counts were analysed using the clustering program TWINSPAN and the ordination program DECORANA.3. Results from ‘Laguna Zacapu and associated sites’ showed that where water chemistry varies little between sample sites the effects of habitat are emphasized. This data set highlighted the problems of looking for modern analogues where anthropogenic disturbance is great.4. TWINSPAN results from the ‘Other Sites’ data set suggested possible changes in diatom assemblages with chemical composition. The DECORANA analyses, however, again seemed to emphasize habitat.5. In the context of this study, bottom sediment samples appeared to provide the most useful picture of ‘average’ conditions and to be the best source of analogues for the interpretation of fossil assemblages.
Epilithic bacteria in an acid and a calcareous headstream
Authors: GOULDER R. 
Published: May 2006

SUMMARY. 1. Environmental variables and epilithic bacteria on small stones were monitored during summer and winter in Burbage Brook and the River Lathkill, two headstreams in the Derbyshire Peak District.2. Burbage Brook was usually near‐neutral in summer, but acid in winter; the River Lathkill was circumneutral throughout the year.3. In summer, epilithic bacteria showed few between‐stream differences. In winter, however, total bacteria, colony‐forming units, per cent chromogenic colony‐forming units, per cent viable bacteria, Vmax for glucose mineralization and Vmax/bacterium were all significantly less in the acid Burbage Brook.4. Inhibition of epilithic bacteria in Burbage Brook was also observed when pH fell to a low level during a summer spate.5. Multiple‐regression analysis confirmed that epilithic bacteria were less successful at low pH but also suggested that pH was not the only environmental variable to influence epilithic bacteria. Especially notable were positive relationships with density of epilithic chlorophyll a and temperature in Burbage Brook and with chlorophyll a in the River Lathkill.
Natural community bioassays to determine the abiotic factors that control phytoplankton growth and succession
Authors: van DONK E. , VEEN A. , RINGELBERG J. 
Published: May 2006

SUMMARY. 1. The successional patterns of the dominant phytoplankton species in Lake Maarsseveen (The Netherlands) were very similar in 1980 and 1981. In December/January the diatoms Stephanodiscus hantzschii Grun., Stephanodiscus astraea (Ehr.) Grun. and Asterionella formosa Hass. dominated the algal community (A. formosa had several further population increases during the year). Fragilaria crotonensis Kitt. came to dominance in March/April, followed by the chrysophyte Dinobryon divergens Imhof and the diatom Cyclotella comta (Ehr.) Kütz in May/June. A second appearance of D. divergens was observed in July/August, followed in 1980 by F. crotonensis and a third small increase of D. divergens. In both years S. astraea and S. hantzschii started to grow again in November/December. Cryptophyceae and Chlorophyta were present throughout the year, but did not show a distinct succession.2. Natural community bioassays, performed under natural light and temperature conditions in a newly developed outdoor bioassay apparatus, showed that phosphate was the major nutrient limiting the growth rate of the phytoplankton. From January till June, during the decline in phosphorus concentration, the diatoms became successively phosphate limited in the sequence: S. hantzschii, S. astraea, F. crotonensis, A. formosa and C. comta. Light limitation was probably the major cause of the relatively late start of F. crotonensis in early spring.3. D. divergens, increasing after the diatoms from June till September, was stimulated by the addition of a chelator (EDTA). The chelator might stimulate the formation of trace metal species favouring their uptake (e.g. iron).4. The patterns of succession of the diatoms observed from January till June and from July till December were to a large extent symmetrical. The controlling factors followed opposite trends: declining phosphorus concentrations with increasing irradiance from winter till spring and increasing phosphorus concentrations with decreasing irradiance from summer till late winter.
Planktonic bloom‐forming Cyanobacteria and the eutrophication of lakes and rivers
Authors: STEINBERG CHRISTIAN E. W. , HARTMANN HELGA M. 
Published: May 2006

SUMMARY. 1. Eutrophication of water bodies involves the enrichment of plant nutrients, often followed by significant shifts in the phytoplankton towards Cyanobacteria. When comparing different aquatic systems, even with similar nutrient contents and in the same climatic region, inverse deductions are not valid; i.e. (a) the presence of Cyanobacteria does not necessarily indicate eutrophic conditions, or (b) eutrophic or even poly‐trophic conditions do not necessarily support cyanobacterial development.2. Above a threshold of 10 μg 1−1 total phosphorus, the development of Cyanobacteria can be described by physical factors, such as water column stability. By characterizing different forms of turbulence, the presence or absence of Cyanobacteria in lakes and rivers can be predicted.3.When the turbulence of the water column is rather low, as it is in sheltered or meromictic lakes, Cyanobacteria can build up dense populations. In nutrient poor systems, species of Oscillatoria and (seldom) Aphanizomenon are dominating.4.If the turbulence of the water column is high (mixing depth much greater than euphotic depth) or the mixing pattern is irregular, as in slowly flowing or regulated rivers, Cyanobacteria are outcompeted.5. In the presence of frequent or permanent turbulence, but with mixing depths lower or not much greater than the euphotic zone (as it is the case in shallow, unstratified lakes, mostly eutrophic or even hypertrophic), Cyanobacteria can outgrow normally dominant r‐strategists under conditions of low N:P ratios, high water temperatures, pH >9.0 or low light availabilities.6. If turbulence is comparatively great (10 to $15 m) and stable for a longer period of time, some cyanobacteria are able to adapt.7. Our statements are discussed on the basis of physiological characteristics.
Effects of temperature and food quality on life‐history parameters in Parameletus chelifer and P. minor (Ephemeroptera): a laboratory study
Authors: SÖDERSTRÖM OLLE 
Published: May 2006

SUMMARY. 1. Growth rate of Parameletus minor was greatest between 10.8 and 19.8°C, survival rate peaked at 5.9°C, developmental time was shortest at 14.6°C, and adult size and fecundity reached maximum values between 5.9 and 10.8°C. Growth rate of P. chelifer was greatest between 14.6 and 19.8°C, survival rate peaked at 5.9°C, and developmental time was shortest at 14.6°C. A large adult size was found at 10.8°C, and highest fecundity between 10.8 and 14.6°C.2. Food quality significantly affected growth rate, developmental time, adult size and fecundity of both species. Both P. chelifer and P minor attained highest growth rate, largest adult size and highest fecundity when the C/N ratio of food was 5.95. Developmental time was shortest at a C/N ratio between 5.95 and 12.8.3. Nymphs of P. chelifer had a higher temperature ‘optimum’ for growth than nymphs of P. minor. Growth rate of nymphs of P. chelifer reared on detritus from a seasonal stream (C/N ratio 12.8) was about 3 times that of nymphs reared on detritus from a river margin (C/N ratio 20.9). The corresponding growth rate difference for nymphs of P. minor was only about 1.5.4. When all life‐history parameters are taken into consideration, P. chelifer had a higher temperature ‘optimum’ than P. minor.
A comparison of zooplankton production estimates obtained from three commonly used methods and a computer simulation program
Authors: KING C. R. 
Published: May 2006

SUMMARY 1. Zooplankton production in a eutrophic reservoir was estimated by three common methods.2. Estimates of daily production from the growth increment method and the birth and death rate versions of the biomass turnover method were poorly correlated (r=0.58–0.60). Estimates of daily production rates from the above two versions of the biomass turnover method were strongly correlated (r=0.90).3. The mortality rate version of the biomass turnover method is illogical and yields anomalous results.4. The growth increment method assumes steady state conditions and zero deaths within each stage and hence calculates potential production for each stage.5. Estimates from a new computer simulation (PROD) were strongly correlated with (r=0.92) but lower than those from the growth increment method. Estimates from PROD were more poorly correlated (r=0.78) with those from the biomass turnover method.6. There is a strong need for improved methods for estimating secondary production; computer based methods would seem to be the most promising.
Effects of temperature on the rate of development of eggs of a planktonic water mite, Piona exigua
Authors: BUTLER MARGARET I. , BURNS CAROLYN W. 
Published: May 2006

SUMMARY. 1. The eggs of a planktonic, predatory water mile Piona exigua Viets were reared in the laboratory at constant temperatures ranging from 10°C to 280C. Egg development rates increased with increase in temperature.2. Five models describing the effect of temperature on egg development times were fitted to the data.3. The variances of the egg hatching times at each temperature differed widely, but these variances were not made more equal by In‐transformation.4. A simple power curve, fitted to the raw data, accounted for ≥.97% of the variation in the data. Two further models, both of which included a third parameter, provided a better fit at the temperature extremes.5. Close examination of the patterns of variance at difference temperatures may provide information relating to the pattern of emergence of aquatic poikilotherms.6. At temperatures below 230C. eggs of Piona exigua developed more rapidly than eggs of Piona constricta, from Heney Lake. Quebec (Riessen, 1982)
Classification of water beetle assemblages in arable fenland and ranking of sites in relation to conservation value
Authors: FOSTER G. N. , FOSTER A. P. , EYRE M. D. , BILTON D. T. 
Published: May 2006

SUMMARY. 1. Water beetles were recorded from 157 sites around the Wash, England, in 1986. Most sites were ditches in arable land. Eight main types of water beetle assemblage were identified by multivariate analysis. The habitats of these assemblages were characterized by measurement of a range of physical and chemical factors.2. Of the 130 species recorded, four are listed in the British Red Data Book and a further thirty‐five are rated as Nationally Notable. Records from 1904 to 1938 for the same area indicate that only three species have been lost in the subsequent period of intensification of water management and arable farming. A rich water beetle fauna can thus survive in drainage systems in arable fen.3. Vegetation management was important in maintaining the ‘species quality score’, proposed as a measure of conservation value, of larger ditches but management reduced the species quality of one type of assemblage associated with smaller ditches. One type of assemblage was found only in ditches subject to management.
Heterotrophic bacterioplankton production and grazing mortality rates in an Ethiopian rift‐valley lake (Awassa)
Authors: GEBRE‐MARIAM ZINABU , TAYLOR WILLIAM D. 
Published: May 2006

SUMMARY. 1. Heterotrophic bacterioplankton growth and production rates were estimated in a tropical lake by various methods. Mean growth rates, determined by tritiated thymidine incoporation into DNA, frequency of dividing cells and increase in cell density varied between 0.013 and 0.014 (with a range of 0.006–0.026) h−1 corresponding to bacterial production of 1.16–1.22 (0.34–3.63) mg C m−3 h−1.2. Heterotrophic bacterial production estimated from oxygen and inorganic carbon consumption in the dark were compared with these values. The oxygen method gave similar results, while values from dark carbon uptake were as much as 2.5 times higher.3. Although the different estimates of rates of bacterial production showed different patterns, the existence of spatial (vertical) and temporal (diel and seasonal) variation was demonstrated. Bacterial production was 13–41% of the net primary production and 10–30% of gross primary production.4. Bacterial grazing mortality rate was estimated from size‐fractionation and metablic inhibitor experiments. Average grazing rates were between 0.34 and 3.77 mg C m−3 h−1 corresponding to 76–120% of the mean bacterial production rate. Organisms 1–12 μm in size, possibly mainly ciliates. were implicated as important bacterial grazers.
Floating meadow epiphyton: biological and chemical features of epiphytic material in an Amazon floodplain lake
Authors: ENGLE DIANA L. , MELACK JOHN M. 
Published: May 2006

SUMMARY. 1. Quantities and the chemical composition of epiphyton on the roots of floating aquatic macrophytes were measured in Lake Calado, an Amazon floodplain lake. Growth of epiphytic algae following physical disturbance and losses of epiphyton due to grazing and storms were investigated.2. Deposition of silt from invading river water decreased chlorophyll and nutrient content (%C, %N, %P) of epiphyton during rising water. N:P ratios of epiphyton indicated that proximity to the river increased supplies of phosphorus. Attached algal biomass per unit root tissue was higher overall during the falling water period, when light was greater, storms less frequent, and new host plant tissue produced more slowly.3. Epiphytic algal biomass at the margins of floating meadows exceeded that of the phytoplankton in the open water on a per unit area basis. Increases in attached algal chlorophyll ranged from two‐ to ten‐fold over 1 week. Artificial denudation of roots was followed by rapid regrowth of attached algae, leading, after I week, to four‐fold increases in chlorophyll over the pre‐denuded state.4. Wind‐blown macrophytes experienced an episodic loss of 70% of epiphytic material in less than 1 h. Particulate material lost from roots grazed by snails included root tissue and contained significantly more carbon than material lost from ungrazed roots.
Life history and habitat use of Norwegian brown trout (Salmo trutta)
Authors: JONSSON BROR 
Published: May 2006

SUMMARY. 1. Brown trout (Salmo trutta) life history and habitat use were studied in two Norwegian rivers: the Vosso river system, western Norway, and the Søre Osa, eastern Norway.2. Age‐groups were partly segregated in feeding habitats, the youngest fish living mainly in running water and in the littoral zone of lakes, the older fish also exploiting pelagic waters and deeper epibenthic habitats. In a population with free access to and from the sea, some individuals smoltified and became sea‐run migrants, performing yearly migrations to the coastal sea, whereas others stayed as freshwater residents throughout their entire life span.3. Within local populations, females were larger and less variable in size than males. This was partly because females matured at an older age than males, partly because the sexes tended to exploit feeding habitats with different food and growth Conditions. Within age‐groups, females were more pelagic and migrated more than males, whereas males were more confined to running water and epibenthic areas than females. In the pelagic zone, males were more abundant in near‐surface water, and females more abundant in deeper areas. When exploiting the same feeding areas, the two sexes grew at the same rate. There therefore appears to be a connection between feeding habitat and the reproductive ecology of brown trout.
Assessing the status of British wild brown trout, Salmo trutta, stocks: a pilot study utilizing data from game fisheries
Authors: GILES N. 
Published: May 2006

SUMMARY. 1. This paper describes an analysis of results from a questionnaire (Giles, 1987) which requested information on the status of game fish stocks (especially wild brown trout Salmo trutta L.) from those Game Conservancy members who own or manage fisheries. Also included are data arising from fishery log book records which are used to indicate trends in brown trout catch per unit effort (CPUE) over past decades.2. The key finding from questionnaire returns was the widespread reporting of apparent declines of wild brown trout stocks in a total of twenty‐seven sites throughout Britain. The affected waters are geographically widespread from the south‐west of England through southern and south‐east England, south Wales, northern England and Scotland including the Western Isles. Suspected stock declines of migratory (sea) trout, salmon Salmo salar L. and grayling Thymallus thymallus L. were also reported. Where brown trout occur alone, a significantly higher proportion of questionnaire returns recorded a stock decline compared with fisheries containing both brown and rainbow trout Salmo gairdneri Richardson.3. Trout catch records from a small selection of differing fishery types are presented and the value of such data in fish stock assessment is discussed.
Habitat patchiness and macrobenthic community structure in an upland stream in temperate Victoria, Australia
Authors: BARMUTA L. A. 
Published: May 2006

SUMMARY. 1. Patterns of co‐occurrence of benthic macroinvertebrates across different habitat patches were monitored for 1 year at one site on the Acheron River, Victoria.2. There was a gradual transition in community structure between erosional and depositional habitat extremes. The correspondence between faunally defined sample groups and habitats was not exact.3. Seasonal changes in community pattern were demonstrated only for erosional habitats. Again the transition was gradual rather than abrupt and contrasted sharply with data from more severe hydrological regimes.4. Most of the community pattern was conferred by a minority of the species present. These species generally had special requirements that apparently could be satisfied only by being confined to the surface layer of sediments.