bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevention of sulphide accumulation and phosphate mobilization by the addition of iron(II) chloride to a reduced sediment: an enclosure experiment
Authors: SMOLDERS A.J.P. , NIJBOER R.C. , ROELOFS J.G.M. 
Published: May 2006

SUMMARY1. In an enclosure experiment carried out in a ditch receiving sulphate‐enriched seepage water, iron(II) chloride was added to the sediment. In the sediment pore water of the iron‐treated enclosures sulphide levels decreased to very low values (<1 μmol 1−1) immediately after the iron addition while in the control enclosures sulphide reached values up to 500 μmoll−1.2. The sulphide levels in the sediment pore water were also strongly correlated with temperature. In summer, phosphate mobilization was observed in the non‐treated enclosures while in the iron‐treated enclosures phosphate levels remained low.3. Total phosphate levels increased greatly in the water layer of the non‐treated enclosures, coincident with an algal bloom and increased turbidity. It is suggested that phosphate mobilization in summer is caused by the reduction of iron(III) phosphate complexes and in this high sulphate water body probably also by the reduction of iron(III) by sulphide and the consequential precipitation of iron(II) sulphide.4. Iron addition appeared to prevent sulphide toxicity in Potamogeton acutifolius Link which was planted in the enclosures immediately after iron(II) addition. In the non‐iron‐treated enclosures P. acutifolius plants decayed within a few weeks probably as a result of sulphide toxicity.
Spatial and temporal distribution patterns of drifting pupal exuviae of Chironomidae (Diptera) in streams of tropical northern Australia
Authors: HARDWICK R.A. , COOPER P.D. , CRANSTON P.S. , HUMPHREY C.L. , DOSTINE P.L. 
Published: May 2006

SUMMARY1. Periodic collecting of floating cast pupal cuticles of chironomids (exuviae) in two tropical northern Australian streams demonstrates (i) spatial heterogeneity in species composition across a wide stream, (ii) temporal heterogeneity in the maximum abundance of each species, and that (iii) species accumulate as a function of sample size and duration of sampling,2. Spatial heterogeneity is ascribed to variation in larval microhabitat across the wide stream, combined with short exuvial drift duration and restricted upstream mixing.3. Temporal heterogeneity is ascribed to diel periodicity in adult emergence and, as with spatial heterogeneity, to the short floating life.4. The consequences of spatial and temporal variation for the sampling of exuvial drift are discussed in relation to the objectives of particular programmes. Thus, if the objective is assessment of chironomid species composition for inventory purposes such as faunistics or conservation, the large sample sizes attained by 24‐h sampling are necessary and appropriate. However, for rapid assessment that requires comparable samples at different sites, species numbers may be optimized by temporally and spatially restricted sampling of the maximal emergence period, which in this study is at dusk, or by subsampling from a 24‐h sample.
Species‐specific phytoplankton responses to nutrients and zooplankton manipulations in enclosure experiments
Authors: PÉREZ‐MARTÍNEZ CARMEN , CRUZ‐PIZARRO LUIS 
Published: May 2006

SUMMARY1. In situ enclosure experiments were performed in the mesotrophic Bermejales reservoir to evaluate the algal response to changes in the nutrient supply and in the zooplankton size structure and density in a 2 × 2 factorial design. The experiments were conducted during the spring bloom of nanoplanktonic diatoms in 1989.2. Nutrient enrichment promoted a great increase of phytoplankton biomass indicating a strong nutrient limitation on phytoplankton growth. Total phytoplankton biomass was significantly lower in the Daphina‐added enclosures at a given nutrient level and strong direct an indirect effect of zooplankton on phytoplankton community structure and nutrient availability were observed.3. Most of the nanoplanktonic species were effectively grazed but species with protective coverings and large size colonies were favoured by grazers and small chlorococcales were unaffected probably because of their compensatory high growth rates. The decrease in total biomass imposed by grazers is attributable mainly to the decrease of Cyclotella ocellata, the most abundant species. This taxon suffers two net effects of zooplankton: direct grazing and the indirect decrease of Si availability caused by the growth of C. ocellata which was promoted by P excretion by zooplankton. Indirect effects of grazers on Si availability should, therefore, be taken into account in explaining phytoplankton succession and community structure.4. In this experiment grazers affected considerably the nanoplanktonic community in Bermejales reservoir. The extent which they were affected, however, depended not only on the algal size as a determinant of edibility but also greatly on the specific nutrient requirements and taxonomic features of the algal species.
Food preference of freshwater invertebrates: comparing fresh and decomposed angiosperm and a filamentous alga
Authors: KORNIJÓW RYSZARD , GULATI RAMESH D. , OZIMEK TERESA 
Published: May 2006

SUMMARY1. Fresh and decomposed Mougeotia sp. (a filamentous green alga) and Elodea nuttallii (a vascular plant) were offered as food to three species of aquatic macroinvertebrates (Lymnaea peregra, Asellus meridianus and Endochironomus albipennis) to test: (i) if filamentous algae are preferred to aquatic higher plants (hereafter, called ‘macrophytes’) and (ii), as is known for higher plants, if decomposition also results in greater palatability of filamentous algae.2. Compared with the alga, the macrophyte in both states was of higher nutritional value. Conditioning improved the nutritional value of both food types, but especially of the macrophyte.3. Both fresh alga and fresh macrophyte were eaten little by all animals except A. meridianus feeding upon the macrophyte. Consumption was higher for both plants in their decomposed state. However, L. peregra consumed more decomposed macrophyte than the decomposed alga. Both decomposed plants were eaten most by E. albipennis followed by A. meridianus and L. peregra.4. Digestibility of both plants, but especially of the macrophyte, increased significantly after decomposition. The assimilation efficiencies of all animals on the fresh E. nuttallii were higher than on fresh Mougeotia sp. After decomposition, the efficiency increased significantly only on the alga. Consequently, both decomposed plants were assimilated with similar efficiency by all test animals.5. Amongst aquatic macrophytes, the increase of their consumption and digestibility upon decomposition has hitherto been known only for vascular plants but not for filamentous algae.
The vulnerability of juvenile signal crayfish to perch and eel predation
Authors: BLAKE M.A. , HART P.J.B. 
Published: May 2006

SUMMARY1. We conducted laboratory experiments to determine how juvenile signal crayfish (Pacifastacus leniusculus) responded to two predators with different foraging behaviours (European eel Anguilla anguilla and European perch Perca fluviatilis), and whether these responses affected their vulnerability.2. By accelerating a model predator towards crayfish which had been temporarily blinded, we assessed whether crayfish had to see predators in order to escape. Blind crayfish escaped later than did sighted crayfish attacked in the same manner.3. Both eels and perch elicited similar evasive behaviour when approaching and attacking sighted crayfish. Crayfish usually escaped these initial attacks but perch chased and caught more crayfish than did eels.4. In a third experiment, perch preyed more rapidly on a population of crayfish than did eels. By the end of the experiment, however, crayfish survival rates were similar in response to eel and perch predation.5. Our results show that crayfish are well adapted to evade predatory attacks based on rapid responses to both visual and/or mechanical stimuli. The results also suggest that behaviourally, crayfish are more vulnerable to attacks by perch than by eels. We discuss these findings in relation to other factors that affect the vulnerability of crayfish to these predators.
APPLIED ISSUES Replacement of the native crayfish Astacus astacus by the introduced species Pacifastacus leniusculus in a Swedish lake: possible causes and mechanisms
Authors: BÄCK BJÖRN SÖDER 
Published: May 2006

SUMMARY1. The introduced North American crayfish Pacifastacits leniusculus is currently replacing the native crayfish Astacus astacus in a Swedish lake. Using field data from co‐occurring populations on life‐history traits and population size structure of the two species, this study evaluated possible mechanisms behind the replacement.2. Pacifastacus showed a higher capacity for population increase; the species had a higher individual growth rate, reached sexual maturity at a smaller size and lower age, and had a higher per capita egg production than Astacus.3. A higher frequency of non‐lethal injuries in Astacus suggested the predominance of Pacifastacus in interference interactions. These results support a competitive exclusion hypothesis.4. A dramatic change in relative abundance of the two species in recent years was the result of an almost complete cessation in recruitment of young‐of‐the‐year (YOY) in Astacus. Poor recruitment in Astacus was probably caused by the combined effects of interspecific competition and predation, resulting in increased mortality among YOY Astacus, and by reproductive interference, suppressing the less common species.5. The results support the hypothesis that the observed replacement of Astacus by Pacifastacus is governed by a combination of several interacting mechanisms, of which
APPLIED ISSUES Increasing litter retention in moorland streams: ecological and management aspects of a field experiment
Authors: DOBSON MIKE , HILDREW ALAN G. , ORTON STUART , ORMEROD S.J. 
Published: May 2006

SUMMARY1. The retention characteristics of two moorland streams in mid‐Wales were manipulated for 2 years by the addition of small traps which accumulated detritus. Leaf litter was also added to these essentially treeless streams at regular intervals to simulate natural inputs to a woodland stream.2. Leaf traps retained a significantly higher biomass of detritus ‐ both naturally occurring and added ‐ than either the surrounding stream bed or unmanipulated reference sections. They also supported significantly higher numbers of nemourid, leuctrid, tipulid and elminthid insect larvae.3. Among functional feeding groups, detritivores and, to a lesser extent, predators responded to increased detritus availability. Numbers of mayfly larvae were low in leaf packs, suggesting a negative effect of detritus aggregations on their numbers.4. The taxa which responded positively to increased detrital biomass, particularly stonefly larvae, are known to be tolerant of low pH conditions, whereas those affected detrimentally are generally absent from acid waters. It is proposed therefore that increasing detrital inputs and litter retention in culturally acidified upland streams may serve to increase their invertebrate productivity.
Carotenoid accumulation strategies for becoming a colourful House Finch: analyses of plasma and liver pigments in wild moulting birds
Authors: MCGRAW K. J. , NOLAN P. M. , CRINO O. L. 
Published: May 2006

Summary

Male House Finches (Carpodacus mexicanus) colour their sexually selected plumage with carotenoid pigments, and there has been much interest in the factors that affect their ability to become bright red rather than drab yellow.
There is good support for the notions that health, nutritional condition and total carotenoid intake influence colour expression, but there are also suggestions that acquiring particular types of carotenoids from the diet may be important for developing red plumage.
We used high‐performance liquid chromatography (HPLC) to analyse the types and amounts of endogenous (in plasma and liver) and integumentary (in newly grown feathers) carotenoids in a wild, native population of moulting male and female House Finches from the south‐western United States to determine the carotenoid‐accumulation strategies for becoming optimally colourful.
Four plant carotenoids – lutein, zeaxanthin, β‐cryptoxanthin and β‐carotene – were detected in plasma and liver. However, as was found previously, 11 carotenoids were observed in colourful plumage, with xanthophylls (e.g. lutein, dehydrolutein) predominant in yellow feathers and ketocarotenoids (e.g. adonirubin, 3‐hydroxy‐echinenone) in red feathers. This indicates endogenous modification of ingested carotenoids.
Birds that accumulated more of one type of carotenoid in plasma and liver did not necessarily accumulate more of all other types, suggesting that individuals are not employing a simple ‘more is better’ strategy for coloration. Instead, when forward stepwise regression was used to examine the ability of individual types of carotenoids in plasma and liver to explain variation in red plumage pigments and plumage redness, we found that the lone variable remaining in all models was β‐cryptoxanthin concentration.
This supports the idea that, unlike some other songbirds (e.g. yellow Carduelis finches), there is a specialized biochemical strategy that male House Finches follow to become red and most sexually attractive – to accumulate as much β‐cryptoxanthin in the body as possible. β‐Cryptoxanthin is a less common dietary carotenoid than the typical xanthophylls and carotenes in grains and fruits and may be limited enough in the diet that, to become colourful, House Finches might adopt selective foraging strategies for the most β‐cryptoxanthin‐rich foods.
Further dental treatment needs of children receiving exodontia under general anaesthesia at a teaching hospital in the UK
Authors: KAKAOUNAKI E. , TAHMASSEBI J. F. , FAYLE S. A. 
Published: May 2006

Summary.  Objectives.  The aim of this study was to investigate the subsequent dental treatment needs of children who had dental extractions under general anaesthesia (GA) in 1997 in the Day Case Unit at Leeds Dental Institute (LDI), Leeds, UK, and the reasons for repeat dental GAs (DGAs).Study design.  The authors conducted a retrospective longitudinal analysis.Subjects and methods.  Information collected from hospital records for the 6‐year period following the first DGA included: reasons for the DGA in 1997 and teeth extracted; the number of subsequent DGAs, reasons and treatment; incidents of and reasons for toothache or swelling after 1997; treatment under local anaesthesia (LA) or inhalation sedation (IS) at LDI during the 6 years following the DGA in 1997.Results.  The study population consisted of 484 children, who received GA exodontia at LDI with a mean age of 6·35 years [95% confidence interval (CI) = 6·1, 6·6] and age range of 1–16 years. The most common reason for extractions at the original DGA in 1997 was dental caries, and the mean number of extractions was 4·24 (95% CI = 4·05, 4·43). Primary teeth extractions accounted for 82% of the cases. In total, 143 children (27·5%) had a record of follow‐up treatment at LDI. Of these children, 32% had treatment under LA, 7% under LA and IS, and 15% received preventive care only. The overall repeat rate for DGA was 10·7%, with caries (84%) being the main reason for this. Of the teeth subsequently extracted, 72% were recorded as caries‐free or unerupted at the time of the DGA in 1997.Conclusions.  A large proportion of the follow‐up visits were to treat newly developed dental disease during the 6 years following the DGA in 1997. A more proactive approach towards preventive care may have resulted in the reduction of the development of new dental disease.
Nurses’ and patients’ perceptions of expert palliative nursing care
Authors: Johnston Bridget , Smith Lorraine N. 
Published: May 2006

Aim.  This paper reports a study of the perceptions of patients and nurses of palliative care and, in particular, the concept of the expert palliative nurse.Background.  Palliative care is a growing speciality and is practised globally. There is, however, limited information on patients’ views about palliative care. While the idea of expertise in nursing is not new, few studies have explored the concept of the expert nurse in palliative care. Some evidence exists on palliative nurses’ perceptions of their care, that it is supportive and involves maintaining therapeutic relationships with patients. Facing a terminal illness has been identified as a stressful and fearful experience that affects all aspects of life. It has also been revealed that dying patients may have unmet care needs, mainly in the areas of pain and symptom control, emotional support, and spending time alone.Methods.  A phenomenological study was carried out, using in‐depth interviews and thematic content analysis. A convenience sample of 22 Registered Nurses and 22 dying patients was interviewed in 1996–1997.Findings.  Dying patients had a desire to maintain independence and remain in control. Palliative care nurses experienced both effective and ineffective interpersonal communication, the building of therapeutic relationships with dying patients and attempting to control patients’ pain and distressing symptoms. Patients and nurses agreed that the two most important characteristics of an expert palliative nurse were interpersonal skills and qualities such as kindness, warmth, compassion and genuineness.Conclusion.  Although the study was conducted in the United Kingdom, the findings have relevance for palliative care practice globally in terms of dependence, issues of patient choice, nurses being interpersonally skilled and building therapeutic relationships with patients.
Role discrepancy: is it a common problem among nurses?
Authors: Takase Miyuki , Maude Phillip , Manias Elizabeth 
Published: May 2006

Aim.  This paper reports a study of nurses’ perceptions of the differences between ideal and actual nursing roles, how these perceptions differ according to length of experience and the factors that might contribute to these perceived differences.Background.  The literature suggests that nurses tend to experience role discrepancy or a mismatch between their ideal and actual roles. Although it has been assumed that experienced nurses perceive less role discrepancy than inexperienced nurses, either because the former adjust themselves to their actual practice or because they have the expertise to improve their practice, this assumption has not been tested.Methods.  A survey design was used and the data were collected in 2003. Selected items from the Jefferson Survey of Attitudes Toward Physician–Nurse Inventory and the Staff Nurse Role Conception Inventory were administered to 216 Registered Nurses in Victoria, Australia to measure their perceptions of ideal and actual nursing roles. Data were analysed using a t‐test and regression analysis.Results.  Nurses with more clinical experience rated their ideal and actual nursing roles more positively than those with less experience. However, the results showed that both groups of nurses experienced the same degree of role discrepancy. Both groups perceived strong role discrepancy in the areas of organizational decision‐making and provision of patient education. Experienced nurses also perceived moderate role discrepancy in developing nursing care plans and in the freedom to initiate referrals.Conclusions.  Role discrepancy cannot be resolved by having more clinical experience. While clinical experience enhances nurses’ conceptions of their ideal roles, it can also lead to role discrepancy if there are organizational barriers that prevent nurses from engaging in their ideal roles. It is important to find a way whereby nurses can actualize their ideal views of practice in the current healthcare environment.
Response of bird communities to silvicultural thinning of Mediterranean maquis
Authors: DE LA MONTAÑA E. , REY‐BENAYAS J. M. , CARRASCAL L. M. 
Published: May 2006

Summary

Woodland management should consider biodiversity conservation world‐wide. Landowners in some European Mediterranean regions receive subsidies to thin dense maquis. This practice eliminates most shrubs and saplings while the tallest trees are pruned to produce more open woodland stands. We investigated the impact of this practice on the conservation status of bird communities.
We designed a large‐scale ‘natural experiment’ that included 21 paired thinned and unthinned maquis stands in central Spain. Every stand was sampled by means of five point counts, each consisting of a 50‐m radius plot, in two consecutive years and in winter and spring. The vegetation structure was characterized after bird censuses in 10‐m radius plots that coincided with the centres of the bird point counts. Data analyses were based on repeated‐measures anovas.
Thinning was responsible for a significant increase in species richness, but did not have any effect on total bird density. The average body mass of species in thinned stands was significantly larger than in unthinned, more densely vegetated, stands. The density of ground searchers was indistinguishable in thinned and unthinned stands, whereas the density of foliage gleaners was higher in unthinned stands. The winter density of granivorous species was marginally higher in thinned stands, whereas insectivorous and frugivorous species were marginally more abundant in unthinned stands.
Thinned areas were occupied by higher densities of bird species whose European conservation status is of high concern. Winter density of gamebirds was also higher in thinned stands.
Synthesis and applications. This is the first time that a large‐scale experimental manipulation of habitat structure and vegetation volume has demonstrated the predicted allometric effect of habitat structural complexity on the average body mass of a bird community. Thinning of dense Mediterranean woodland enhanced habitat heterogeneity and suitability for several bird species and increased species richness. It was also beneficial for species of conservation concern and for non‐threatened gamebirds. However, some unthinned patches should be preserved to provide refuge for the few species that are impacted by thinning.