bluuebunny/crossref_metadata_2025_split huggingface dataset:
The consumption of rainbow trout (Salmo gairdneri Richardson) eggs by macroinvertebrates in the field
Authors: BROWN ANDREW F. , DIAMOND MARK 
Published: May 2006

SUMMARY. 1. Perforated boxes containing live, dead or no eggs of the rainbow trout, Salmo gairdneri Richardson, were buried in a natural spawning redd in a stream in North Wales for the duration of the natural incubation period.2. A significant difference (P<0.001) was found between the mean number of invertebrates colonizing perforated boxes containing live eggs, dead eggs and no eggs.3. The number of eggs retrieved from boxes originally containing dead eggs decreased as the number of invertebrates colonizing the boxes increased.4. Using a serological method of prey identification it was demonstrated that Leuctra hippopus (Kempny), Gammarus pulex (L.) and Ptychopter‐idae sp. scavenged on trout eggs in the field.5. There was some evidence that Rhyacophila dorsalis (Curtis) and Diura bicaudata (L.) preyed on trout eggs, but in view of their scarcity, it is suggested that they were a minor mortality factor.
Distribution of macro‐invertebrates in a ditch in relation to the vegetation
Authors: SCHEFFER MARTIN , ACHTERBERG ADRIAAN A. , BELTMAN BOUDEWIJN 
Published: May 2006

SUMMARY. 1. Quantitative fauna samples were taken from four differently structured vegetations in a ditch on three dates in the summer of 1980.2. Cluster analysis of twenty‐four samples showed that the vegetation pattern is probably the main factor in determining the spatial distribution of non‐benthic macro‐invertebrates in the ditch. Temporal heterogeneity arising from changes in the macro‐invertebrate fauna during the summer, however, appeared to be of at least the same magnitude as the observed spatial heterogeneity. Different vegetation types differed considerably in total faunal density. Species that are taxonomically related tend to have a similar distribution in the ditch.
Hatching time and growth of Nemurellapictetii (Plecoptera: Nemouridae) in the laboratory and a Lake District stream
Authors: ELLIOTT J. M. 
Published: May 2006

SUMMARY. 1. Nemurella pictetii Klapæplek took 2 years to complete its life cycle in both the laboratory and a small stream in the English Lake District.2. Hatching time (days after oviposition for 10%. 50% and 90% of the eggs to hatch) and hatching period (days between dates for 10% and 90% hatched) decreased with increasing water temperature in the laboratory, and the relationships were well described by a power‐law. Estimates of the mean time for 50% hatching in the stream varied between 16 and 31 days after oviposition. depending on temperature.3. Larval instars numbered fifteen for males and seventeen for females with a constant ratio of 1.18 between successive instars (conformed with Dyar's rule). Larval growth was exponential at four constant temperatures in the laboratory; mean instantaneous growth rates were 0.40±0.01% day−1 at 5.9°C, 0.43±0.01% day−1 at 8.2°C, 0.46±0.01% day−1 at 12. 1°C. 0.56±0.02%day−1 at 19.8°C. No larvae survived after instar XI at 19.8°C.4. Larval growth was exponential in the stream and was scarcely affected by variations in water temperature (range 4.2 ‐14.0°C); mean growth rates for three year‐classes were 0.41±0.02, 0.43±0.08, 0.54±0.05% day−1. Their similarity to laboratory growth rates under optimum conditions suggests that the availability of resources, such as food and space, was not restricting growth in the stream.
Diel and seasonal physico‐chemical fluctuations in a small natural West African lake
Authors: HARE LANDIS , CARTER JOHN C. H. 
Published: May 2006

SUMMARY. 1. The waters of Opi Lake were very dilute (15–24 μS cm−1at 25°C) and somewhat acid (pH 6.0–6.5), probably a result of the highly leached lateritic soils in its small drainage basin.2. Annual minimum water temperatures were recorded during the early dry season, not during the rainy season as has been observed in most other West African water bodies. This was attributed to the influence of the Harmattan winds on the lake and the absence of pronounced rainy season flooding, as might occur in reservoirs.3. A diel cycle of daytime thermal stratification and complete or near‐complete night‐time destratification occurred throughout the year.4. During the dry season, when prevailing winds were strong and lake depth shallow, night‐time destratification was accompanied by deep circulation. In the rainy season, when prevailing winds were weak and lake depth was greatest, deep vertical circulation apparently did not take place, as evidenced by anoxia in near‐bottom waters. This is the reverse of the pattern seen in many tropical lakes.
The microdistribution of some lotic insect predators in relation to their prey and to abiotic factors
Authors: MALMQVIST BJÖRN , SJÖSTRÖM PER 
Published: May 2006

SUMMARY. 1. The microdistribution of three species of insect predators in a Swedish stream was assessed using a multivariate statistical approach. Both abiotic factors and factors pertaining to the prey community were included in the analysis.2. The factors most strongly correlated to the distribution of large Dinocras cephalotes were the densities of case less caddis larvae (Wormaldia sp. and Hydropsyche siltalai) and the median weight of stonefly prey. For small D. cephalotes, the density of H. siltalai and the percentage of moss cover were most important. Isoperla grammatica showed a significant correlation to blackfly density. Rhyacophila nubila occurred predominantly in patches with high prey biomass and with high densities and median weight of case less caddis larvae.3. It was concluded that the quantity and quality of the prey, such as size, availability and species, influenced the predators’microdistribution. The distributional pattern differed between species of predators and was probably related to their different hunting strategies.
Reproductive phenology in Dendrocoelum lacteum (Turbellaria) in South Sweden
Authors: HERRMANN JAN 
Published: May 2006

SUMMARY.

L 266 degree‐days, above a threshold of 1.0°C, were required for cocoons from the triclad Dendrocoelum lacteum to hatch. The relation is described by ln D=6.12–1.17 1nr (D=number of days, T= temperature).
Laboratory and field cocoon deposition reached a maximum in late April; peaks of hatchling occurrence were 2 weeks later. The number of hatchlings per cocoon and eocoon viability declined as spring proceeded. Cocoon deposition ceased in June, coincident with regression of the reproductive organs of the adults.
Newly hatched triclads in the field are thought to avoid stones for their first weeks.
It is suggested that the earlier and more abundant offspring production in South Sweden than in Britain could be attributed to differences in spring temperature conditions.
Changes in the concentrations of short‐chain carboxylic acids and gases during decomposition of the aquatic macrophytes, Lemna paucicostata and Ceratophyllum demersum
Authors: STERRY P. R. , THOMAS J. D. , PATIENCE R. L. 
Published: May 2006

SUMMARY.

Samples of two species of aquatic macrophytes, Lemna paucicostata and Ceratophyllum demersum, with which snail hosts of schistosomes are commonly associated, were homogenized, together with their epiphytic flora, and allowed to decompose in closed systems for up to 42 days.
After 10 days of incubation it was found that populations of rod and coccoid shaped bacteria had greatly increased. Fermentation proceeded only to the acid forming stage and no methane was produced.
Despite the differences in the morphologies, habitats and epiphytic flora of the two species, it was found that the short chain carboxylic acids, acetate, propanoate, butanoate and hydrogen were the major end products of microbial decomposition in both cases. There was also some oxygen production from photosynthetically active zones within the homogenates. Most of the accumulation profiles for the acids conformed to logistic growth curves, whereas the hydrogen values fluctuated.
The reasons for the biochemical changes, the differences between the patterns of decomposition in Lemna and Ceraiophyllum. and the ecological relevance of the results to the plants, micro‐organisms and the snails are discussed.
Effects of copper on production of periphyton, nitrogen fixation and processing of leaf litter in a Sierra Nevada, California, stream
Authors: LELAND HARRY V. , CARTER JAMES L. 
Published: May 2006

SUMMARY.

Production of periphyton, nitrogen fixation and processing of leaf litter were examined in an oligotrophic Sierra Nevada stream and the responses of these processes to copper (2.5, 5 and 10μg 1‐1 CuT [total filtrable copper]; approximately 12, 25 and 50 ng 1‐1 Cu2+) were determined.
Autotrophic and total production were estimated from 3‐week accumulations of biomass on artificial substrates. Mean autotrophic production in the control ranged from 0.22 to 0.58 mg C m‐2 h‐1 in summer‐autumn 1979, but declined to 0.08–0.28 mg C m 2 h‐1 after peak discharge in summer 1980, apparently due to phosphorus‐limited growth. Total production in the control ranged from 0.30 to 0.82 mg C m‐2 h ‐1 in summer‐autumn 1979 and from 0.16 to 0,68 mg C m ‐2 h ‐1 in 1980. Mean autotrophic productivity, estimated by l4C‐bicarbonate uptake in daylight, ranged from 0.30 to 2.8 mg C m‐2 h‐1.
Autotrophic productivity was reduced by 57–81% at 2.5μg 1‐1 CuT, 55–96% at 5μg 1‐1 CuT, and 81–100% at 10μg 1‐1 CUT, Heterotrophic productivity (based on dark 35S‐sulphate uptake) was inhibited to a lesser extent (28–63% at 2.5μg 1‐1 CuT, 24–84% at 5μg 1‐1 CuT, and 67–92% at 10μg 1‐1 CuT), The inhibition of autotrophic and heterotrophic productivity persisted through the year of exposure. Production in stream sections previously exposed to 2.5 and 5μg 1‐1CuT increased to control levels within 4 weeks after dosing, but remained depressed for more than 7 weeks after exposure to 10μg 1‐1 CuT.
The specific rate of photosynthesis (mg C mg chlorophyll a‐1 h‐1) of mature periphyton communities declined at all test concentrations of copper, but the rate for periphyton on newly‐colonized surfaces did not change. The species composition of benthic algae shifted during exposure to an assemblage more tolerant of copper. Achrtanthes minutissima and Fragilaria crotonensis were the primary replacement species on newly‐colonized surfaces.
The nitrogenase activity of blue‐green algae was low. with controls ranging from 2.4 to 12 nmol C2H2 m‐2 h‐1. Nitrogenase activity was inhibited during the initial weeks of exposure by 5 and 10μg 1‐1 CuT. However, after 9 months of exposure, control and copper‐treated sections did not differ.
The rate of processing of leaf litter, estimated by microbial respiration and nutrient quality of litter of resident riparian woodland taxa, was inhibited at all test concentrations of copper.
Density gradient centrifugation (DGC) in Percoll for isolation and characterization of Oscillatoria spp. from Tjeukemeer
Authors: BLOEM J. , MOED J. R. 
Published: May 2006

SUMMARY.

A high degree of separation was achieved in isolating Oscillatoria redekei and O. agardhii separately from Tjeukemeer seston by density gradient centrifugation (DGC) in Percoll. When diatoms were abundant, however, a pre‐incubation in settling cyhnders was applied to obtain an optimal separation of O. redekei from diatoms.
One major band dominated by O. redekei was formed in the gradients. O. agardhii showed a varying distribution over three different bands and its banding pattern seemed to be related to the centrifugation resistance of its gas vacuoles and the turgor pressure.
Pigment ratios of O. agardhii were not affected by DGC in Percoll.
Acclimation of stream‐bed heterotrophic microflora: metabolic responses to dissolved organic matter
Authors: KAPLAN LOUIS A. , BOTT THOMAS L. 
Published: May 2006

SUMMARY.

Studies were performed to assess the acclimation of the stream‐bed heterotrophic microflora to sources of dissolved organic matter (DOM) typical of its environment and microfloral responses to pulses of DOM.
Microcosm measurements of dissolved organic carbon (DOC) uptake, dissolved oxygen uptake. ATP concentration and epitluorescence microscopic counts (EMC) were performed using stream‐bed sediments and heterogeneous dissolved organic matter (DOM) sources.
Three study sites included an undisturbed woodlot spring seep, a small stream traversing a cattle pasture and a larger stream draining a catchment used for silage crops, pastures and woodlands.
The DOM sources were cold water extracts of forest floor leaf litter, bovine manure, the green alga Ulothrix and jewel weed (Impaliens capensis L.) leaves.
DOC uptake occurring in 2.5–5.0 h incubations indicated an acclimation of the microflora at each site to DOM sources generated by surrounding land use.
The sediment microflora from the larger stream did not readily metabolize bovine manure DOM and the latter was used in an acclimation experiment.
A minimum of 48 h of cumulative exposure to bovine manure DOM at 15–20°C were required to yield measurable changes in sediment microbial activity of sediment microbial biomass.
The same microflora retained an ability to readily metabolize the added DOM source after 72 h of exposure to unamended stream water.
The time frame of microfloral responses during acclimation indicated that changes leading to the metabolism of a DOM source were initially enzymatic and eventually involved growth and selection for specific decomposers within the microbial community.
We conclude that in order to utilize naturally occurring pulses of carbon and energy, stream‐bed heterotrophs must be already enzymatically prepared, induced, when the pulse occurs.
Thermal and chemical stratification and mixing in a small tropical reservoir, Solomon Dam, Australia
Authors: HAWKINS PETKR R. 
Published: May 2006

SUMMARY.

The patterns of distribution of temperature, dissolved oxygen, and filterable iron in the water mass of Solomon Dam were determined at about 30 day intervals over a 2.5 year period (1981–83).
The thermal stratification, and resultant chemical differentiation of the epilimnion and hypolimnion, was the dominant limnological feature of the reservoir. A pronounced thermoline was present for most of the year and, during the stratified phase, diurnal circulation appeared to be the main mechanism for maxis.
Evidence for the presence of an internal seiche, a phenomenon commonly associated with stratified water bodies, was also observed.
An annual overturn in June‐July coincided with the minimum in solar radiation. The ‘wet’ season (January‐March) caused either partial or complete circulation depending on the volume of the reservoir and the rate of inflow. In 1982 the lake circulated once, fitting the warm monolithic pattern, but in 1983 there were two circulations, the first resulting from flood inflows.
The study illustrated the inappropriate nature of a thermally derived classification scheme for a small reservoir.
The larval diet of three anisopteran (Odonata) species
Authors: BLOIS CATHERINE 
Published: May 2006

SUMMARY.

Comparisons between larval diets of three anisopteran species (Anax imperator, Aeshna cyanea and Libellula depressa) showed that their food intake changed depending on: (1) predator species, (2) time of year, and (3) developmental stage.
Although this last factor is not so important, the mean size of prey items and the range of prey species eaten by Auax imperator and Aeshna cyanea larvae increased with predator size.
Comparisons between prey availability and diets indicated differential selectivity by these predators.
Patterns of macroinvertebrate colonization on fresh and senescent alder leaves in two Michigan streams
Authors: STOUT R. JEAN , TAFT WILLIAM H. , MERRITT RICHARD W. 
Published: May 2006

SUMMARY.

Communities of invertebrates colonizing senescent autumn and fresh summer alder leaves (Alnus rugosa) were compared. Leaf packs for each treatment were placed in two hardwater streams in the Upper Peninsula of Michigan in late summer and early autumn. One stream has a cobble‐bottom and the other a sand‐bottom and both receive fresh leaf inputs by beaver fellings.
Fresh leaf packs remained intact after 26 days immersion, but thereafter were processed faster than were the autumn leaf packs in both streams.
In the cobble‐bottom stream taxon richness (S), numbers of individuals and biomass were higher on fresh than on autumn leaves.
Fresh leaves in the sand‐bottom stream supported a more diverse (H'), richer (S) and more equitably distributed (J') insect fauna than did the autumn leaves.
We discuss the simultaneous lack of fresh leaf loss and the presence of more complex insect communities on those leaves during the first 26 days of the study. Invertebrates in both mid‐latitude heterotrophic streams and in tropical lowland wet forest streams may rely on fresh leaf inputs, which have received little attention.
Limnological investigations on the Rosetta branch of the Nile. I. Environmental conditions
Authors: SAAD MASSOUD A. H. , ABBAS MAHDI H. 
Published: May 2006

SUMMARY.

Seasonal and local variations of some environmental conditions in the Rosetta branch of the River Nile are reported. The lowest air and water temperatures were recorded in January (winter) and the highest in July (summer). Slight decrease in water temperatures with depth is related to solar heating and mixing processes. The pH values, averaging between pH 7.5 and 8.2, showed seasonal changes which, in the main, may be related to photosynthesis.
The seasonal average chlorosity values showed very wide variation, due to fluctuations in the discharge rate of the River Nile and its effect on the estuarine sea water. Sharp increase in chlorosity values with depth at the estuarine stations was produced by the less dense river water, flowing over denser tongues of sea water. In January, however, the maximum discharge flushed out the sea water.
Minimum oxygen saturation values occurred in January and the highest values of dissolved organic matter were obtained in July. Both of these will be shown in a later publication to be related to phytoplankton abundance. Increase in dissolved organic matter near the bottom was common and is interpreted as due to the more complete decomposition of descending dead organisms and the release of organic matter from the bottom deposits.
The macroinvertebrate fauna of an acid‐stressed headwater stream system in the Adirondack Mountains, New York
Authors: SIMPSON K. W. , BODE R. W. , COLQUHOUN J. R. 
Published: May 2006

SUMMARY.

The Silver Run system in the Adirondack Mountains of New York includes three first‐order streams with very different pH regimes: one moderately acidic (pH 5.8‐7.2), the others much more so (pH generally 4.4‐5.0)
The less acidic (acidophilic) site yielded a relatively diverse, well balanced fauna, with at least 10% each of midges, mayflies, stoneflies and elmid beetles. Ephemerella funcralis (Ephemeroptera) and Oulimnius latiusculus (Coleoptera) were dominant in this community. They appear to be among the most acid‐tolerant species of their respective families and may become abundant under moderately acidic conditions. Their absence or low abundance in the more acidic tributaries of the Silver Run system suggests that they arc eliminated as acidification intensifies, These species therefore may he useful indicators of advancing acidification.
The more acidic (acidobiontic) communities contained fewer Hum half as many taxa as the acidophilic communities, contained few elmid beetles or mayflies, and were heavily dominated In stoneflies. Leuctra feiruinea and Isopecrla sp. were dominant, comprising.56‐86% of the individuals. Other common constituents included black flies (Simuliumn gouldingi and S. venustum) and the caddisfly Rhyacvphila fuscula.
Macrophyte‐gastropod associations: observations and experiments on macrophyte choice by gastropods
Authors: LODGE DAVID M. 
Published: May 2006

SUMMARY.The abundance and microdistribution of thirteen gastropod and ten macrophyte species were monitored over 2 years in a 1 ha shallow eutrophic pond near Oxford, England. While areas of allochthonous leaf litter supported a depauperate and nondistinctive gastropod fauna, three different macrophyte habitats supported more diverse and distinctive assemblages of gastropods.Most gastropod species were clearly more abundant (number m‐2pond bottom) on one macrophyte type than on other substrates. One exception, the limpetAcroloxus lacustris(Linn.) was abundantion both the water lilyNymphaea albaL. and on emergent macrophyles.Planorbis vortex(Linn.) was associated with graminoid emergent macropytes, especiallyGlyceria maxima(Hartm.) Holmberg, whileLymnaea peregra(Mull.) was associated with submersed macrophytes, perhaps more particularly withElodea canadensisMichx.The association of, 4.lacuxtriswithN. albaand emergent macrophytes is perhaps explained by constraints of the morphology of the limpet requiring a relatively broad smooth substrate for attachment and locomotion.The reason for the associations ofP. vortexwith G.maxima, and ofL. peregrawithE.canadensisare less obvious. Experiments giving each snail species a choice between the two macrophytes showed thatP. vortexregularly exhibited a preference for G.maximabut failed to reveal substrate selection byL. peregra.Neither snail species affected the macrophyte choice of the other. The results suggested thatL. peregradid not behave naturally in experiments.The preference for G,maximabyP. vortexwas not affected by prior conditioning of the plant by the snail, but was affected by the emergent nature of G.maximaand by the presence/absence of a natural periphyton assemblage and associated detritus.The distribution ofA. lacustrisis probably determined by the physical structure of the substrate, while that ofP. vortexis determined by the presence and quality of epiphytic periphyton‐detritus. The observations and experiments withL. peregrareported here leave the reasons for its distribution in doubt.
Diel feeding ecology of the nymphs of Aeshna multicolor and Lestes unguiculatus (Odonata)
Authors: JOHNSON JAMES H. 
Published: May 2006

SUMMARY.

Diel feeding periodicity and diet composition of nymphs of Aeshna multicolor and Lestes unguiculatus were examined at 6 h intervals in a small pond. Feeding intensity of A. multicolor increased from 06.00 hours to approximately 18.00 hours whereas food intake by L. unguiculatus was uniformly high between 12.00 and 18.00 hours. Feeding of both species was reduced during the night.
Diel variation in diet composition was substantial in each species. Chironomid larvae were the major prey (48.9%) in the diet of A. multicolor. Zooplankton, mainly cladocerans (42.0%) and ostracods (21.1%), were the principal prey of L. unguiculatus. Detritus composed a substantial portion of the diets of both species.
Diet overlap (Cλ) at each 6 h interval was high (0.43–0.72) when detritus was included in the calculation and was low (0.48–0.54) when detrital material was omitted.
Effects of phosphorus and nitrogen enrichment on the yield of some strains of Stigeoclonium Kütz. (Chlorophyceae)
Authors: de VRIES PIERRE J. R. , de SMET STEPHAN J. M. , van der HEIDE JOOP 
Published: May 2006

SUMMARY.

The combined effect of nitrate and phosphate concentrations on the yields of five selected strains of Stigeoclonium is demonstrated in a synthetic medium as well as in natural waters.
Increase of yield after addition of one nutrient depends on the concentration of the other. A graphic growth model based on the experiments in synthetic medium is presented, which allows prediction of yields at different combinations of nitrate and phosphorus concentrations.
In general, yields in natural waters before and after addition of nitrate and/or phosphate agree with the model. In some cases, other limiting factors appear to be involved.
The possible effects of nitrogen and phosphorus limitation on the phosphorus and nitrogen metabolism of the alga are discussed.
Neither an exponential model (Baule‐Mitscherlich) nor a hyperbolic model adequately describe the interaction demonstrated between nitrogen and phosphorus limitation.