bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlates of habitat favourability for benthic macroinvertebrates at five stream sites in an Appalachian Mountain drainage basin, U.S.A.
Authors: MILLER CLARK 
Published: May 2006

SUMMARY.

Based on monthly samples taken over a 1‐year period, average density (individuals m‐2). average standing biomass and annual production of benthic macroinvertebrates were estimated at five sites within an Appalachian Mountain drainage basin. Two sites were on first order streams and differed from the three second order sites: they were smaller and more shallow and they were depressed in pH and chemical richness.
Patterns of abundance of individual taxa, of higher taxonomic groups and of functional (feeding) groups differed according to whether abundance was measured as density, as standing biomass or as annual production. Standing biomass was chosen as the measure of macroinvertebrate abundance because available evidence indicates that only standing biomass is consistently, positively correlated with survivorship, and thus with habitat favourability.
Two non‐insect taxa (the crayfish Cambarus and the snail Leptoxis carinata) dominated standing biomass at each site. Consequently, differences among sites in total macroinvertebrate standing biomass and differences within and among sites in standing biomass of functional groups were determined by differences in estimated standing biomass of these two taxa. Differences in estimates of crayfish standing biomass were consistent with an explanation based on the availability of refuges created by large substrate particles. The abundance of L. carinata appeared to be controlled primarily by water chemistry and possibly secondarily by predators. A number of insect taxa exhibited patterns of standing biomass consistent with hypotheses based on effects of annual depth‐flow regimes. Hypotheses based on differences in food resource and on competition appeared, in general, to be inconsistent with observed patterns of macroinvertebrate abundance.
Contrary to predictions of the River Continuum Concept, the shredder functional group in the Guys Run drainage and in other temperate woodland streams was found to be a minor part of total macroinvertebrate standing biomass. Further, in a majority of small forested stream sites studied to date, standing biomass of grazers has been determined to be greater than that of shredders.
Periodical citations in aquatic entomology and freshwater benthic biology
Authors: RESH VINCENT H. 
Published: May 2006

SUMMARY.

Periodicals cited and frequency of periodical citation were examined for two aquatic entomology textbooks published in 1984 (The Ecology of Aquatic Insects, Resh & Rosenberg, eds.; An Introduction to the Aquatic Insects of North America, Merritt & Cummins, eds.) and a bibliography of freshwater benthic biology [published by the North American Benthological Society (NABS) in 1984]. These results were then compared with periodicals cited in Wetzel's (1983) Limnology textbook and with analyses of literature citations in limnology and entomology.
In the aquatic entomology and benthic biology sources, eighteen‐twenty journals each contained ≥1% of total citations and fourteen‐twenty‐eight journals (3.3–5.3% of all journals cited) contained 50% of total citations; however, over one‐half (51.7–57.8%) of the journals contained only a single citation.
In the limnology sources examined, thirteen‐seventeen journals contained ≥1% of total citations, twenty‐four‐fifty‐nine journals (4.3–17.8% of all journals cited) contained 50% of total citations, and 54.5–58.5% of the journals contained a single citation.
Core lists of journals (≥1% of total citations) in Resh & Rosenberg and NABS closely agreed with core lists used for Aquatic Sciences and Fisheries Abstracts.
Based on analysis of 1684 papers published in seven journals from 1975 to 1984, 48% of papers published on aquatic entomology and freshwater benthic biology topics dealt with descriptive studies of macroinvertebrate life histories of bionomics.
Population dynamics of the freshwater dinoflagellate Ceratium hirundinella in the largest shallow lake of Central Europe, Lake Balaton, Hungary
Authors: PADISÁK JUDIT 
Published: May 2006

SUMMARY.

Horizontal distribution, long‐term (1933–82) and short‐term (day‐to‐day) changes in abundance, vertical stratification and circadian rhythm of the freshwater dinoflagellate Ceratium hirtmdinella were studied in Lake Balaton, the largest shallow lake of Central Europe.
The lowest abundance was consistently found in those areas of the lake which had the strongest currents.
The density of C. hirundinella seemed to be, at least in those parts of the lake above the level of fertility considered oligotrophic, insensitive to changes in trophic conditions; only its relative contribution to total biomass decreased with increased enrichment.
During the day the bulk of the population stayed at a level in which the light intensity was between 126 and 440 μE m‐2 s‐1 PAR.
Shredder abundance and leaf breakdown in an Appalachian Mountain stream
Authors: BENFIELD E. F. , WEBSTER J. R. 
Published: May 2006

SUMMARY.

Breakdown rates of dogwood (Cornus florida L.), red maple (Acer rubrum L.) and white oak (Quercus alba L.) leaves were investigated at two first‐order and two second‐order sites in an Appalachian Mountain stream.
Leaves exposed in mesh bags were sampled on eight occasions over a 207 day period and breakdown rates were compared using an exponential decay model.
There was a consistent ranking in leaf breakdown rate within each site, i.e. dogwood > red maple > white oak, and all species broke down faster at second‐than at first‐order sites.
Our data suggest that differences in species‐specific leaf breakdown rates were largely a function of shredder abundance on the leaves.
A note on ‘stomaching’ for the quantitative sampling of epiphyton
Authors: BOWKER D. W. , van TEUTEM W. , FRY J. C. 
Published: May 2006

SUMMARY. 1. Methods for the quantitative removal of epiphyton from Cladophora glomerata were compared.2. Stomaching for 3–5 min effected maximum epiphyte release. Agitation for up to 40 min in water or hydroiysing solutions of hydrochloric acid or F.A.A. removed significantly fewer epiphytes.3. Stomaching is recommended as a new, simple, quick and effective method for quantitative epiphyton sampling.
Temperature, oxygen and heat‐budgets of six small western Irish lakes
Authors: ALLOTT N. A. 
Published: May 2006

SUMMARY. 1. Temperature and oxygen were examined in six small western Irish lakes (areas 2–110 ha) in 1981, 1982 and 1984.2. The four deeper lakes (&#x007a;̄= 6–11m) stratify stably in the same manner as some well‐known stratifying lakes in Britain. Windiness (due to proximity to the ocean) seems generally to be reflected in the lakes by the presence of a sharp thermo clinic. Considerable variation in the pattern of stratification occurs from year to year.3. Two shallow lakes (&#x007a;̄= 4.1 and 2.7m) stratify only in periods of warm, calm weather.4. Annual heat‐budgets range from 4.1 kcal cm−2 to 13.7 kcal cm−2. There is a strong linear relationship between mean‐depth and annual heat‐budget.5. Oxygen depletion is severe in the more productive lakes.
A regression technique for the estimation of epiphytic invertebrate populations*
Authors: DOWNING JOHN A. 
Published: May 2006

SUMMARY. 1. A regression method is proposed for the estimation of populations of epiphytic invertebrates. Small samples of macrophytes and attached animals are taken by gentle enclosure. Regression analysis is used to relate the number of animals collected to the macrophyte species composition and ibiomass in these small samples. These relationships estimate the number of organisms of each taxon per unit mass of each macrophyte species. Areal population density is estimated by multiplication of macrophyte mass‐specific invertebrate density by standing macrophyte biomass.2. The regression method yields population density estimates several times greater than the best of current methods for several fauna. Differences are most pronounced for active organisms such as water mites, amphipods, cladocerans, copepods, lepidopterans, ostracods, and trichopterans.3. Precision levels obtained using the regression method are comparable to other techniques. The regression technique automatically provides estimates of macrophyte species‐specific colonization density and the abundance of organisms swimming among macrophytes in littoral areas.
Periphyton communities in a pristine mountain stream above and below heavy metal mining operations
Authors: DENISEGER J. , AUSTIN A. , LUCEY W. P. 
Published: May 2006

SUMMARY. 1. Changes in species composition of the periphyton on introduced substrates were determined in an oligotrophic mountain stream subject to long‐term heavy metal contamination.2. At the upstream control site, the numerically most abundant taxa were Bacillarioph yta i(Achnanlhes minutissima, Achnanthes microcephala and Achnanthes linearis) as well as, in summer, the Chlorophyta (Mougeotia spp. and Ulothrix subtilissima).3. At the downstream contaminated site the periphyton community was totally dominated by Bacillariophyta throughout the sampling period. A, minutissima and A, microcephala were co‐dominants during spring. Seasonal succession patterns did not parallel those at the upstream site. Chlorophyta were virtually absent and A. minutissima comprised 94% of the community during summer.4. Species diversity, species evenness and dissimilarity index were utilized to detect differences in species composition, abundance and number. Slight differences were found in spring samples while summer samples indicated major differences between sampling sites.
Life cycle, growth, mortality and production of Ephemerella major Klapalek (Ephemeroptera) in a trout stream in Belgium
Authors: ROSILLON DOMINIQUE 
Published: May 2006

SUMMARY. 1. The life cycle of Ephemerella major Klapalek in a chalk trout stream in Belgium took 1 year. Emergence was highly synchronized with a flight period from mid‐May to mid‐June. Tiny nymphs occurred from June to late August.2. The mean instantaneous growth rate was high in autumn (3.6% wet wt day−1), very low from November to February (0.8% wet wt day−1) and high until emergence (2.3% wet wt day−1); short day length seemed to be the major factor reducing growth rate during winter.3. Mortality was close to zero during winter and 1.4—1.7% day−1during other seasons. Total mortality from egg to adult was 99.6%.4. The annual production was about 9g wet wt m−2 year−1 and the annual P/B̄ ratio was 7.5. There was good agreement between the production values estimated by four methods. Production rate was highest in May (13 mg wet wt m−2 day−1) and zero in February.
The flora, fauna and water chemistry of Tagimaucia crater, a tropical highland lake and swamp in Fiji
Authors: SOUTHERN W. , ASH J. , BRODIE J. , RYAN P. 
Published: May 2006

SUMMARY. 1. Tagimaucia crater lake and swamp are located at an altitude of 820m in Taveuni, Fiji (lat. 16°S; long. 179°56'W). Rainfall exceeds evaporation in all seasons and residence time for water in the shallow lake (2.5–5.5 m deep) is only 4 days.2. Dissolved ion concentrations are low (conductivity 14–18μScm−lat 25°C), and the water is slightly acidic (pH 5.0–6.5 at 25°C), Median total phosphorus (0.5 gm−3) and total nitrogen (3.3gm−3) are moderately high and probably represent dissolved and suspended organic matter. Median chlorophyll a concentrations (2.5 mg−3) were low and indicate low phytoplankton productivity.3. The swamp vegetation is dominated by Lepironia articulate (Retz.) Domin and algae which form floating sedge peat islands, and Pandanus taveuniensis St John and other small trees where alluvium and colluvium are infilling the margins of the crater. The surrounding slopes are forested.4. The fauna of the lake and swamp are low in both diversity and abundance. The only aquatic vertebrates observed were Anguilla eels and cane toads, Bufo marinus L., and the only bird was the swamp harrier, Circus approximans approximate Peale. A variety of aquatic insects were observed but crustaceans and other invertebrate taxa were scarcely recorded.5. Although the swamp and lake are otherwise undisturbed, several recently introduced plants and animals have been recorded.
The estimation of crop evacuation rates in Chaoborus larvae (Diptera: Chaoboridae) using natural prey
Authors: GIGUÈRE L. A. 
Published: May 2006

SUMMARY. 1. Crop evacuation rates were estimated for the first time in Chaoborus larvae, using natural prey.2. Fourth instar C. americanus Matheson digested copepods (Diaptomus leptopus S.A. Forbes) 48.7% faster than daphnids (Daphnia rosea Leydig) of similar size; meal size did not significantly affect the instantaneous rate of digestion (IRD) within each prey type. Prey specific IRD has not been reported before for zooplankton.3. Prey specific differences in IRD require the use of natural prey when digestion experiments are to be used to estimate natural rates of food consumption of animals.
Geochemical aspects of aqueous iron, phosphorus and dissolved organic carbon in the humic Lake Tjeukemeer, The Netherlands
Authors: DE HAAN H. , DE BOER T. 
Published: May 2006

SUMMARY. 1. The main source of P, Fe and DOC in the humic Lake Tjeukemeer is superfluous water pumped from surrounding peaty polders. Most particulate P is intracellular but almost all particulate Fe is abiotic.2. The size and molecular weight of the P, Fe and DOC (mainly fulvic acids (FA)) were determined by ultrafiltration and Sephadex G‐100 gel filtration. Throughout the year most dissolved P and Fe was in colloids >35 nm with apparent molecular weight between 30,000 and 150.000. The bulk of FA occurred in particles <35nm.3. Calculating the atomic ratios of P, Fe and organic C in the different size classes revealed that Fe‐FA chelates are a minor species of the Fe pool. Less than 10% of the fulvic acids occurred as Fe‐FA chelates.4. Based on their apparent size and molecular weight, the Fe‐FA chelates are colloidal aggregates, probably with the formula Fen‐1(FA)n.5. About 50% of the dissolved P had the same size as the Fe‐FA aggregates. These aggregates were only noticeable in winter when humus‐rich polder water was flushed through the lake. During the rest of the year the dissolved Fe and P consisted mainly of acid‐labile inorganic colloids which might have been organically coated.
Resource‐mediated demographic variation during the midsummer succession of a cladoceran community
Authors: THRELKELD STEPHEN T. 
Published: May 2006

SUMMARY. 1. The midsummer succession of cladoceran zooplankton in Lake Texoma was examined by demographic characterization of lake populations and a parallel set of life table experiments in which the dominant cladoceran species were raised on naturally occurring lake phytoplankton at lake temperatures. Diaphanosoma leuchtenbergianum occurred throughout the study period (mid June‐mid August 1981) but Daphnia parvula, D. galeata mendotae and Ceriodaphnia lacustris were rarely detected after 15 July.2. Analyses of size structure and size‐specific fecundity of the cladoceran populations showed that (1) size structure shifted to smaller individuals in mid July, (2) size‐specific fecundity was relatively constant in the smaller size classes and was constant or declined in larger females of each species, and (3) size at maturation did not vary significantly during the study of any population.3. Individual growth rates of the two Daphnia species and Ceriodaphnia in the life table experiments were significantly lower in mid July when populations were declining and when size structure of each population was more dominated by smaller Individuals. The reduction in individual growth rates was short‐lived in the life table experiments; growth rates returned to pre‐decline levels by the end of July.4. Two effects of temporary reductions in individual growth rates when size‐specific fecundity and size at maturation are constant are (1) that size structure is temporarily shifted to smaller individuals, and (2) the potential rate of population growth is reduced because of delays in reproduction. Because data on size structure and size‐specific fecundity are commonly used to evaluate the relative effects of predators and resource changes on populations it is noteworthy that erroneous conclusions about the mechanism of population decline may be reached when individual growth rates vary.
Nutrient limitation of Myriophyllum spicatum growth in situ
Authors: ANDERSON M. ROBIN , KALFF JACOB 
Published: May 2006

SUMMARY. 1. The hypothesis that the submersed macrophyte biomass in natural weedbeds is nutrient limited was tested in situ by an enrichment experiment.2. The response of Myriophyllum spicatum was significant and positive for N‐enrichment, resulting in a 30–40% increase in biomass over controls. There was no response to phosphorus or to potassium enrichment.3. Plant length and number of shoots per rephcate were also significantly increased by nitrogen additions but again showed no response to phosphorus and potassium.4. Water depth differences were also found to affect the plant responses in some cases.5. The macrophyte response to fertilization was similar to that recorded for emergent macrophytes and terrestrial crops but much smaller than for phytoplankton.
Spatial and temporal variation in the diet of a predaceous stonefly (Plecoptera: Perlodidae)
Authors: WALDE SANDRA J. , DAVIES RONALD W. 
Published: May 2006

SUMMARY. 1. Spatial and temporal variation in the diet of the univoltine predatory stonefly, Kogotus nonus, was studied over 3 years in a small Alberta stream to determine whether the relative abundance of prey types in the diet of Kogotus reflected relative prey densities in the stream and whether the variation in absolute feeding rate was related to either prey or predator density.2. The seasonal shift from sole utilization of Orthocladiinae to inclusion of Baetis in the diet could not be attributed to seasonal changes in prey density, but was probably related to predator size and ability to handle very active prey. Most of the spatial variation in diet could be related to differences in background prey densities, but very high densities of Baetis caused the predator to specialize on this prey.3. Feeding rate on Baetis. as assessed by per capita gut contents, showed a seasonal shift from a positive correlation with Baetis density in winter to a negative relationship with predator density in spring. This suggested that feeding by small Kogotus is a function of prey density. while feeding by later instars is influenced by between predator interactions such as interference.
Relations between suspended bacteria, epiphytic bacteria and submerged vegetation over the spring growing season in a calcareous headstream
Authors: RIMES CARRIE A. , GOULDER R. 
Published: May 2006

SUMMARY. 1. Quantitative observations on suspended bacteria, epiphytic bacteria and submerged vegetation, in a calcareous headstream in North Humberside, were made at regular intervals from January to June 1984.2. Downstream increase in concentration of suspended bacteria was observed along a 135 m richly‐vegetated section but not over a 150 m vegetation‐free section, hence there was measurable drift loss of bacteria only from within the vegetated section.3. The total number of epiphytic bacteria within the vegetated section was estimated from the density of epiphytic bacteria per unit dry weight of submerged vegetation and the total dry weight of submerged vegetation.4. The total number of epiphytic baeteria within the vegetated section decreased frtim 2.5 × 1015 in January to 0.8 × l015 March before increasing to 4.7 × 1015 by June. This pattern was related to deerease and subsequent increase in density of epiphytic bacteria per unit dry weight of vegetation. The total dry weight of submerged vegetation inereased throughout the study period.5. The daily drift loss of bacteria from the vegetated section averaged 53% (range 9–132%) of the total epiphytic bacteria, a loss rate which might reasonably be supported by the epiphyte population.6. The dimensions and volume of suspended bacteria increased, between the source and the downstream limit of the vegetated section, to resemble those of epiphytic bacteria.7. The results suggested that released epiphytic bacteria might largely be the source of suspended bacteria in this headstream.
Regulation of damseifly populations: the effects of weed density on larval mortality due to predation
Authors: THOMPSON DAVID J. 
Published: May 2006

SUMMARY. 1. The effects of weed detisity oti the predalion of damseifly larvae by Notonecta were investigated iti a laboratory experimetit.2. In the absence of weeds. Notonecta exhibited a Type 2 functional response, but this changed to a Type 3 response as weed density increased. Consideration is given to the possible significance of these results for the regulation of field populations of damseifly larvae.
Does ionic strength affect the configuration of aquatic humic substances, as indicated by gel filtration?
Authors: DE HAAN H. , JONES R. I. , SALONEN K. 
Published: May 2006

SUMMARY. 1. The effect of ionic strength on the configuration of aquatic humic substances was studied by gel filtration and dialysis of water from small. Finnish forest lakes of varying colour.2. Sephadex gel filtration of water from the most humic lake gave similar elution profiles of UV absorbance and dissolved organic carbon (DOC). Gel filtration of unconcentrated samples from all three lakes under natural conditions of ionic strength (I = 1.7 × 10−4) and pH (5.5–6.0) gave similar fractionation of humic substances, despite their widely differing colour (30–350 mg Pt l−1) and DOC (5–25mg C l−1).3. Increasing the ionic strength by two orders of magnitude caused considerable retardation on the Sephadex columns of the humic substances, suggesting a decrease in their molecular size and/or shape.4. Dialysis experiments strongly indicated that ionic strength‐induced changes in the configuration of the aquatic humic substances are indeed real. Hence it is probable that the elution behaviour of aquatic humic substances on Sephadex gels has previously been wrongly attributed to ionic strength‐dependent interactions between the gel and the humic substances.