bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of new organic carbon and its distribution between autotrophic picoplankton, bacteria, extracellular organic carbon and phytoplankton in an upland lake
Authors: HAPPEY‐WOOD CHRISTINE M. , LUND ANDERS H.
Published: May 2006

Picoplankton community production (0.2–2μm) was investigated over 3 months, June‐September 1991, in Llyn Padarn, a mesotrophic upland lake in north Wales.

 The picoplankton was differentiated into autotrophic algae (<1–3μm) and heterotrophic bacteria (<0.2–1 μm) using differential filtration through a 1 μm pore size Nuclepore filter.

 Efficient separation of these distinct metabolic constituents of picoplankton was obtained. A good correlation (r= 0.81, P < 0.001) was found between physical separation of bacterial and picoalgal cells from fluorescence microscopy and the distribution of heterotrophic metabolic activity between different cell size fractions measured by uptake of 14C‐glucose.

 Picoplankton community production was differentiated into the ‘absolute’ autotrophic production by picoalgae, corrected for overestimation due to retention of bacteria with the picoalgae, and the heterotrophic component, bacterial uptake of ‘extracellular organic carbon’ (EOC), derived from the entire phytoplankton community.

 The heterotrophic contribution to picoplankton community production ranged from 88 to 1%, mean value 55% of total. Autotrophic picoplankton production was dominant in June and July, but in August and September heterotrophic uptake of EOC was the major input to picoplankton community production.

 During the 3 months, the mean contributions to plankton production were autotrophic picoplankton 10.3%, heterotrophic bacterial uptake of EOC 9.7%, EOC in lake water 11.6% and phytoplankton (>3μm) 68.3%.

 Bacteria accounted for about half the picopfankton community production via uptake of EOC. Thus although autotrophic picoplankton were ubiquitous, it is likely that their contribution via primary production to the carbon balance of planktonic environments has been overestimated in previous studies.
Patterns of life history among cyclopoid copepods of central Europe
Authors: MAIER GERHARD
Published: May 2006

Life history characters (body size of adults, egg diameter, egg sac length and breadth) of nineteen species of central European cyclopoid copepods were measured and sexual size dimorphism (adult female length x adult male length−1), relative egg size (egg weight X body weight−1), weight of adult females and of eggs, egg sac shape (egg sac length x egg sac breadth−1), and reproductive effort (clutch weight produced per female weight per day) were calculated to detect trends in life history strategies.

 Typical planktonic species exhibited the lowest reproductive effort. Among planktonic species, the value for egg sac shape increased with clutch size.

 Large species and small species exhibited different trends in life history characters. Large species had larger clutches, larger eggs, and a greater sex size dimorphism than small species. However, small species had a greater relative egg size.

 Large species live in cold water and reproduce during the spring bloom of phytoplankton where the production of large clutches with relatively small eggs is advantageous. Reserves are unnecessary for juveniles because food is abundant. Small species generally are most abundant during the warm season, when conditions are less predictable, and relatively large eggs, possibly provided with reserves, are advantageous.
Trophic interactions and benthic animal community structure in the Colorado River, Arizona, U.S.A.
Authors: SHANNON JOSEPH P. , BLINN DEAN W. , STEVENS LAWRENCE E.
Published: May 2006

1. Cladophora glomerata is the dominant filamentous green alga in the tailwaters of the Colorado River, U.S.A., below Glen Canyon Dam, but becomes co‐dominant with filamentous cyanobacteria, Oscillatoria spp., below the confluence of the Paria River (26km below the dam) where suspended sediments are elevated.

2. Benthic algal assemblages played an important role in the distribution of the amphipod, Gammarus lacustris, in the dam‐controlled Colorado River through Grand Canyon National Park, Arizona. Cladophara and G. lacustris showed a weak positive relationship at ten cobble‐riffle habitats in the Colorado River from Lees Ferry (25km below the dam) to Diamond Creek (362km downstream), while no relationship was found between Oscillatoria and G. lacustris.

3. The relationship between algal substrata and G. lacustris was tested by a series of in situ habitat choice experiments. G. lacustris showed a significant preference for Cladophora (with epiphytes) over Oscillatoria spp., detritus and gravel in treatment pans at Lees Ferry.

4. Epiphytic diatoms (i.e. food) were the overriding determinant of subtratum choice by G. lacustris in laboratory experiments. Gammarus chose the Cladophora/epiphytic diatom community over sonicated Cladophora with few diatoms. The amphipods also chose string soaked in diatom extract over string without diatom extract.

5. Importance of mutualistic interactions in aquatic benthic community structure is discussed.
Effects of single and repeated experimental acid pulses on invertebrates in a high altitude Sierra Nevada stream
Authors: KRATZ KIM W. , COOPER SCOTT D. , MELACK JOHN M.
Published: May 2006

1. We examined responses of aquatic macroinvertebrates to pulsed acidification experiments in twelve streamside channels located in the Sierra Nevada, California. Experiment 1 consisted of a single 8 h acid addition, and Experiment 2 consisted of two 8 h acid additions administered 2 weeks apart. Replicated treatments (four reps/ treatment) consisted of a control (pH 6.5–6.7) and pH levels of 5.1–5.2 and 4.4–4.6. Invertebrate drift was monitored continuously and benthic densities were determined before and after acid addition.

2. Drift responses to pH reduction were: (i) increased drift during acidification in pH 5.2 and pH 4.6 treatment channels, often with depressed post‐acidification drift in treatment channels relative to controls (exhibited by Baetis only). Depressed post‐acidification drift in treatment channels appeared to be due to low benthic densities because a positive relationship between benthic and drift densities was noted for most common taxa; (ii) increased drift rates during acidification only at pH 4.6 (Epeorus, Drunella, Paraleptophlebia, Zapada, and Simulium); (iii) decreased drift at pH 5.2 and/or pH 4.6 relative to control channels (Rhyacaphila and chironomid larvae); (iv) no significant response to acidification (Ameletus, Amiocentrus, Dixa and Hydroporus).

3. A high proportion (45–100%) of acid‐induced drift in Baetis, Epeorus, and chironomid larvae could be attributed to dead, drifting individuals.

4. Except for chironomids, most common invertebrates (i.e. Baetis and Paraleptophlebia) showed reduced benthic densities in treatment relative to control channels after acidification.

5. For sensitive taxa, drift was enhanced and benthic densities reduced by single (Experiment 1) and initial [Experiment 2(a)] acid pulses. Drift responses to a second acid pulse [Experiment 2(b)] were not as pronounced as those to the single or initial acid pulses [Experiments 1 and 2(a)], and the second acid pulse had no additional effect on benthic density.
Ecology of alpine, glacial, high latitude and mountain streams: introduction and synthesis
Authors: WINTERBOURN MICHAEL J.
Published: May 2006

1. This paper provides the introduction to a special issue of Freshwater Biology devoted to papers dealing with aspects of the physical environment and ecology of alpine, glacial, high latitude and mountain streams.

2. Eleven of the sixteen papers were included in a symposium that formed part of the scientific programme of the North American Benthological Society Annual Meeting in Calgary, Alberta, Canada, in May 1993.

3. The contributions are a combination of reviews, overviews and primary research articles that deal with streams and ecological issues in Alaska, Nepal, New Zealand, Switzerland and southern Africa. Important issues considered include environmental consequences of river ice; altitudinal and temporal distributions of stream biota, especially macroinvertebrates; litter processing; and bryophyte production.
Mountain streams in Westland, New Zealand: benthic ecology and management issues
Authors: WINTERBOURN MICHAEL J. , RYAN PADDY A.
Published: May 2006

1. The West Coast of the South Island, New Zealand (Westland) is a region of mountains, forests, high rainfall, and a history of exploitation. The Southern Alps rise to over 3000m in the east of the region, and a narrow coastal plain supports some agriculture and the main centres of population.

2. Stream waters in the Southern Alps are characterized by low concentrations of major ions, and most can be described as calcium—sodium—bicarbonate waters. Brown waters with low pH and high concentrations of dissolved organic carbon are common at low and intermediate altitudes.

3. Many mountain streams and rivers provide physically harsh environments for aquatic biota with their rapidly changing flows and frequent spates. Hydrological factors and low nutrient concentrations limit periphyton standing crops, and biomass of coarse detritus is often low. Invertebrate populations are usually dominated by insect larvae that feed primarily on FROM and stone surface biofilms.

4. Features of the macroinvertebrate stream fauna on the West Coast are the wide range of physicochemical conditions tolerated by many common species, and the numerical dominance of the mayfly Deleatidium (Leptophlebiidae) in many streams. The Plecoptera also exhibit high diversity relative to other parts of the country, and an unusual trend towards terrestrialism is shown by larvae of Gripopterygidae.

5. The West Coast has a long history of coal and gold mining, forestry and farming, activities that have had negative impacts on stream communities and water quality. We discuss some ecological and management issues associated with present day mining practices, and a proposal to take large volumes of alpine stream water for export.
Influence of water abstraction on the macroinvertebrate community gradient within a glacial stream system: La Borgne d'Arolla, Valais, Switzerland
Authors: PETTS GEOFFREY E. , BICKERTON MELANIE A.
Published: May 2006

1. Water abstraction from glacial rivers is an important characteristic of hydroelectric power schemes in Alpine regions. Streams in the Valais region of Switzerland have been particularly affected.

2. Invertebrate distributions are described in La Borgne d'Arolla, a glacial stream with icemelt‐, snowmelt‐ and groundwater‐dominated tributaries. The icemelt‐dominated streams have been affected by abstractions for more than 30 years.

3. The glacial streams contain only Chironomidae(Diamesa), and are devoid of fauna for between 200 and 500 m below the glacier snouts.

4. Immediately below the water intakes the streams are intermittent, flowing only during system purges and high floods, and are devoid of fauna for short distances (<1.5km).

5. Further downstream, abstraction of glacial meltwater increases the importance of snowmelt and groundwater, increasing water temperatures, improving water clarity and increasing the length of krenal/rhithral streams at the expense of kryal streams.

6. A community including Chironomidae, Simuliidae, Baetidae, Nemouridae, Limnephilidae and Chloroperlidae occurs as soon as a permanent flow is maintained by tributary runoff, and the channel becomes stable.

7. A wide range of taxa inhabit snowmelt‐ and groundwater‐dominated tributary streams with stable channels, often at much higher altitudes than the main river. The tributaries provide sources for rapid colonization of the main channel following ice retreat or physical disturbance.

8. Purges and high floods are important disturbances within the main channel. Recovery may be rapid because of drift from tributaries, but sites influenced by frequent disturbances have reduced faunas in comparison to stable channel sites.

9. This study supports the model proposed by Milner & Petts (1994) and shows that deterministic responses of macroinvertebrate communities may be observed to changes of temperature, turbidity, flow regime and channel stability.
Life histories of burrowing mayflies (Hexagenia limbata and H. rigida, Ephemeroptera: Ephemeridae) in a northern Canadian reservoir
Authors: GIBERSON DONNA J. , ROSENBERG DAVID M.
Published: May 2006

1. The life histories and population dynamics of the burrowing mayflies Hexagenia Umbata and H. rigida were examined from 1986 to 1988 in four regions of an impounded lake in northern Manitoba, Canada.

2. Bottom temperatures reached 15–20°C, but ice‐free periods of 4–6 months resulted in annual degree day (dd > 10°C) accumulations of only 210–650 in various regions and years.

3. The life cycles (egg to adult) of both Hexagenia species required 3yr in the three warmest regions studied and 4yr in the coolest area; total dd accumulations to complete the life cycle ranged from 1222 to 1468 dd > 10°C.

4. Fecundity (no. of eggs/) was strongly correlated to body size of subimagos, and subimago size was strongly correlated to length of nymphal exuviae, so field collection of nymphal exuviae could be used to determine both the size and fecundity of the emerging females.

5. Degree day accumulation in the final year before emergence was a better predictor of emergence timing than overall dd accumulations for the life cycle.
Exploitation of sediment bacterial carbon by juveniles of the amphipod Monoporeia affinis
Authors: GOEDKOOP WILLEM , JOHNSON RICHARD K.
Published: May 2006

1. Carbon budget parameters were measured for young‐of‐the‐year Monoporeia affinis in a combined field and laboratory (microcosm) study, designed to quantify the role of sediment bacteria as a carbon source for juvenile amphipods. Special emphasis was placed on the stimulative effects of amphipod activity (foraging, feeding, bioturbation) on sediment bacterial production and abundance by including the carbon thus generated in carbon budget calculations.

2. Amphipod production was clearly higher at lower densities, suggesting strong intraspecific interactions. Negative production was recorded at amphipod densities of 10000 and 20000 ind. m−2. Negative production was not accompanied by a decrease in amphipod total lipid content, however, probably due to the lack of easily mobilized lipids in juvenile amphipods. Amphipod respiration rate was 0.45 μg O2 ind.−1 h−1, or O.15 μg C ind.−1 h−1. Sediment bacterial carbon content averaged 1.31 and 0.90 mg g−1 DW under field and laboratory conditions, respectively.

3. Bacterial carbon was not quantitatively important for Monoporeia. Due to higher bacterial abundance and production in natural, stratified sediment, assimilation of bacterial carbon was highest for the field population, providing 6.3% of the amphipods' carbon requirement. In microcosm populations, bacterial carbon accounted for between 1.7 and 5.2% of overall amphipod carbon demand, increasing with amphipod density and bioturbation.

4. Ingestion rate, rather than the quantity of bacterial carbon in the sediment, was found to limit absorption of bacterial carbon from the sediment.
Monitoring lake recovery from point‐source eutrophication: the use of diatom‐inferred epilimnetic total phosphorus and sediment chemistry
Authors: ANDERSON N.J. , RIPPEY B.
Published: May 2006

1. Diatom and geochemical responses to reduced nutrient loading were followed in a small, monomictic eutrophic lake in Northern Ireland by use of short sediment cores taken c. 15 years after redirection of creamery waste away from the lake.

2. Epilimnetic total phosphorus (TP) concentrations (fig TP 1‐−1) were estimated for the period 1850–1990 using weighted averaging regression and calibration. Background TP levels, inferred using the diatom model, were c. 35μg TP 1‐−1 and increased to >140μg TP 1‐−1 in the late 1960s to early 1970s. Total P concentrations dropped to 80 μg TP 1‐−1 within 5 years of waste diversion (c. 1978–79), but varied between 1980 and 1990 (range 70–140 μg TP 1‐−1), perhaps due to internal loading, occasional continued disposal from the creamery and natural variations in stream P load.

3. Diatom‐inferred TP concentrations were compared with monitored data where available, and the diatom model tended to overestimate TP concentrations by about 25 fig TP 1‐−1. Possible reasons for this are discussed (errors in the diatom model, stratigraphic variability, variability in the monitoring data).

4. Post‐1980 geochemistry profiles (concentrations and accumulation rates) indicated some changes when compared with sediments deposited before 1980, perhaps reflecting the redirection of the creamery waste and reduced productivity of the lake (e.g. reduced calcium deposition). Phosphorus concentrations in the sediments changed very little over the last 150 years and, while sedimentary TP fluxes (g cm−2 yr−1) increase steadily up‐core, they do not record the effluent redirection in the mid‐1970s. There is, however, some indication of a slight lowering of P retention in the most recent sediments (1985–90).

5. The general implications of such an approach to monitoring (i.e. the use of short cores) are discussed and the value of diatom‐inferred TP assessed. Diatom models offer the possibility of determining background TP concentrations and indicate that, despite the redirection of the creamery waste over 15 years ago, the pre‐creamery epilimnetic TP concentrations have not yet been reached.
Co‐inertia analysis: an alternative method for studying species–environment relationships
Authors: DOLÉDEC SYLVAIN , CHESSEL DANIEL
Published: May 2006

Methods used for the study of species–environment relationships can be grouped into: (i) simple indirect and direct gradient analysis and multivariate direct gradient analysis (e.g. canonical correspondence analysis), all of which search for non‐symmetric patterns between environmental data sets and species data sets; and (ii) analysis of juxtaposed tables, canonical correlation analysis, and intertable ordination, which examine species–environment relationships by considering each data set equally. Different analytical techniques are appropriate for fulfilling different objectives.

We propose a method, co‐inertia analysis, that can synthesize various approaches encountered in the ecological literature. Co‐inertia analysis is based on the mathematically coherent Euclidean model and can be universally reproduced (i.e. independently of software) because of its numerical stability. The method performs simultaneous analysis of two tables. The optimizing criterion in co‐inertia analysis is that the resulting sample scores (environmental scores and faunistic scores) are the most covariant. Such analysis is particularly suitable for the simultaneous detection of faunistic and environmental features in studies of ecosystem structure.

The method was demonstrated using faunistic and environmental data from Friday (Freshwater Biology 18, 87‐104, 1987). In this example, non‐symmetric analyses is inappropriate because of the large number of variables (species and environmental variables) compared with the small number of samples.

Co‐inertia analysis is an extension of the analysis of cross tables previously attempted by others. It serves as a general method to relate any kinds of data set, using any kinds of standard analysis (e.g. principal components analysis, correspondence analysis, multiple correspondence analysis) or between‐class and within‐class analyses.
Temporal and spatial environmental variability in the Upper Rhône River and its floodplain
Authors: CELLOT BERNARD , DOLE‐OLIVIER MARIE JOSÉ , BORNETTE GUDRUN , PAUTOU GUY
Published: May 2006

This paper develops a framework of spatial and temporal variability for a habitat typology of the Upper Rhône River (France) and its alluvial floodplain that is based on about 17 years of data collection and analysis. The aim was to provide a scale of spatial‐temporal variability for river habitat templet predictions on trends in species traits and species richness.

In developing this framework, eight physical‐chemical variables were available and could be considered for twenty‐two habitat types: seventeen superficial (surface) and five interstitial (0.5 m below the substrate surface). These habitat types were selected in two areas (Jons and Brégnier‐Cordon) after geomorphological considerations and because of differences in their biological characteristics.

The data sets used were processed by a ‘fuzzy coding’ method using, for each variable, the frequency distribution (by modalities = categories) of all measurements and monthly means over an annual scale. Two tables were produced; the first corresponded to an expression of the total variability, and the second represented an evaluation of the temporal variability.

Each of these tables was analysed by correspondence analysis, which provided factorial scores that were used to calculate, by habitat type and by variable, a total variability and a temporal variability in terms of cumulated variability of factorial scores for the eight physical–chemical variables. The rationale in describing variability from these two tables is that total variability equals temporal variability plus spatial variability. The spatial variability was then determined by the difference between total and temporal variability. From this procedure, a positioning of the twenty‐two habitat types on the spatial and temporal variability axes was obtained.

The estimate of spatial variability did not consider any error term that may have occurred in the above model; it was then tested by an independent assessment of the spatial variability using thirteen variables in nine major habitat types. A high correlation between the two ways of assessing spatial variability (r = 0.85, P < 0.004) underscored the reliability of the spatial variability that was calculated previously.

The river habitat templet obtained for the Upper Rhône and its alluvial floodplain appears to be appropriate to test the predictions on patterns of species traits and species richness in the framework of spatial and temporal variability.
Theoretical habitat templets, species traits, and species richness: fish in the Upper Rhône River and its floodplain
Authors: PERSAT HENRI , OLIVIER JEAN‐MICHEL , PONT DIDIER
Published: May 2006

Recent developments in ecological theory concerned with habitat templets, species assemblages, and life history traits were examined for the riverine fish communities of the Upper Rhône River, France, in the context of spatial–temporal habitat variability. Relationships among species traits, habitat utilization of species, the relationship between species traits and habitat utilization, and trends of species traits and species richness in the spatial–temporal variability of the habitat types were analysed.

Relationships among twelve species traits, and utilization of eight habitats were examined for twenty‐five fish species using correspondence analysis; the relationship between species traits and habitat utilization was investigated by co‐inertia analysis.

Positive relationships among species traits were observed for size, fecundity, and the number of reproductive cycles per individual. However, species were not well differentiated according to the habitat utilization, except for habitats rarely connected with the main channel (i.e. two types of oxbow lakes).

No significant relationship was found between species traits and habitat utilization, nor for either species traits or species richness when examined in the framework of spatial–temporal habitat variability. Only two species traits corresponded (with slight trends) to predictions in a river habitat templet: (i) the number of descendants per reproductive cycle increased along with temporal variability; and (ii) the number of reproductive cycles per individual was either low or high at low temporal variability and intermediate at elevated temporal variability.

The discrepancy between the predictions of the river habitat templet as well as of the patch dynamics concept and the results observed for the fish in the Upper Rhône was explained in terms of scale problems, the evolutionary ecology of the European fish fauna, and the history of the Rhône River.
Theoretical habitat templets, species traits, and species richness: birds in the Upper Rhône River and its floodplain
Authors: BOURNAUD MICHEL
Published: May 2006

To test predictions of the river habitat templet and the patch dynamics concept, twenty species traits and the species richness of eighty‐one bird species were examined in the context of the spatial – temporal variability of ninety‐one sites at Jons, a section of the Upper Rhône River, France.

The basic information was obtained either from the literature (for species traits) or by observation, then structured by a fuzzy coding technique, and examined using multivariate analyses.

The relationships between species traits separated three groups of birds: (i) large species that are long lived, have long breeding cycles, and use open sites to feed, breed, and sing (e.g. Podicipidae, Laridae); (ii) medium‐sized species with intermediate longevities and breeding cycles that use less open sites (e.g. Columbidae, Corvidae); and (iii) small species that are short lived, have short breeding cycles, and use closed sites (e.g. Sylviidae).

The distribution of birds in the floodplain habitats of the river was closely related to the spatial–temporal variability of sites.

No trends in species traits were observed along a gradient of spatial–temporal variability of the sites.

Species richness of birds was relatively constant over the gradient of spatial–temporal variability of the ninety‐one sites, but decreased at low spatial and high temporal variability because of human activities and vegetation changes that occurred at these sites.

These observations on species traits and richness were related to the high mobility of birds (which is a scale phenomenon) and the high intercorrelation between parameters used to determine the spatial and temporal variability of the sites (which makes separation of the spatial from the temporal variability impossible).
Theoretical habitat templets, species traits, and species richness: floodplain vegetation in the Upper Rhône River
Authors: PAUTOU GUY , ARENS MARIE‐FRANCOISE
Published: May 2006

The floodplain vegetation at approximately 100 sites located in nine different habitat types of the Upper Rhône River, France, was surveyed three times over the past 27 years. Information on species traits of the higher plants comprising the Rhône floodplain vegetation was based on studies conducted between Geneva, Switzerland, and Lyon, France.

These data were structured using a ‘fuzzy coding’ technique and then examined using ordination analyses to investigate: (i) relationships among species traits; (ii) habitat utilization; (iii) the relationship between species traits and habitat utilization; and (iv) trends of species traits and species richness in the framework of spatial–temporal habitat variability to test predictions of the river habitat templet and the patch dynamics concept.

Size, number of descendants per reproductive cycle, number of reproductive cycles per individual, and the regeneration potential of an individual were positively related with each other, whereas the degree of attachment to the soil decreased, and the reproductive period shifted from autumn/late summer towards early summer/spring, as size increased.

The habitat utilization by the higher plants of the floodplain revealed a double lateral gradient: the first was from the banks of the temporary waters to terrestrial flats; the second from aggrading pebble to aggrading silt habitats. These gradients were related to gradients in water saturation, oxygen conditions, nutrient loading, and nutrient retention of the soils.

A significant relationship between species traits and habitat utilization was observed for the floodplain vegetation, i.e. plant communities used particular habitat types with a particular set of species trait modalities (= categories).

Patterns of species trait modalities were significantly related to temporal and spatial habitat variability but only modalities of the trait ‘parental care’ conformed to trends predicted from theory.

No trends were observed when species richness of different habitat types was considered in the framework of spatial–temporal habitat variability.

Although the habitats of the Upper Rhône clearly act as a templet for the species traits of the floodplain vegetation, the lack of agreement between observations and predictions on trends in species traits and richness in terms of habitat variability suggest that important elements of theory should be rejected. However, human‐induced changes in these habitats are too recent when compared with the longer time periods required for floodplain vegetation to respond to such changes.
Seasonal dynamics of crustacean zooplankton, heterotrophic nanoflagellates and bacteria in a shallow, eutrophic lake
Authors: JÜRGENS KLAUS , STOLPE GISELA
Published: May 2006

1. The seasonal development of crustacean zooplankton, heterotrophic nanoflagellates (HNF) and bacteria was examined in Grosser Binnensee, a shallow, eutrophic lake in northern Germany. The grazing impact of Daphnia on bacteria and nanoflagellates was estimated from field data on population abundances and from clearance rates obtained in laboratory experiments.

2. The seasonal succession of zooplankton showed distinct peaks of Daphnia magna, cyclopopid copepods, Bosmina longirostris and Daphnia galeata and D. hynlina. The population dynamics of Dapfinia had the strongest impact on all sestonic components. Daphnia maxima coincided with clearwater phases, and were negatively correlated with particulate organic carbon (POC), HNF and phytoplankton. Bacterial abundance was only slightly affected although daphnids were at times more important as bacterial consumers than HNF, as estimated from measured bacterial clearance rates. Other crustaceans (copepods, Bosmina) were probably of minor importance as grazers of bacteria and nanoplankton.

3. HNF abundance varied from 550 ml−1 to more than 30000 ml−1. HNF appeared to be suppressed by daphnids and reached highest densities when copepods dominated the metazooplankton. The variation in HNF abundance was not reflected in the concentration of heterotrophic bacteria, which fluctuated rather irregularly between 5 and 20 ± 106 ml−1. Long filamentous bacteria which were probably resistant to protozoan grazing, however, appeared parallel to the development of HNF. These bacterial cells, although small in number, could comprise more than 30% of the total bacterial biomass.
Stream hydraulics and the distribution of microcrustacea: a role for refugia?
Authors: ROBERTSON ANNE L. , LANCASTER JILL , HILDREW ALAN G.
Published: May 2006

1. The relationship between microcrustacean abundance and flow habitat in three contrasting reaches of a single stream was examined.

2. Three methods of characterizing stream hydraulics (shear stress frequency distributions, Froude numbers and mean reach velocity) showed the same pattern among the three reaches, which were subsequently termed ‘fast’, ‘slow’ and ‘medium’.

3. Distributions of epibenthic microcrustacea matched flow characteristics of the three reaches, being most abundant in the slow reach and least abundant in the fast reach. In contrast, densities of three out of four species of interstitial Harpacticoida did not vary significantly with reach, and none of the parameters measured explained much of their between‐patch variation in density. Hydraulic conditions at the substratum surface may not affect the distribution of species with interstitial habits.

4. Patterns in the abundance of organic matter (a possible food source) were examined. Measures of organic matter were highly correlated with hydraulic variables, with detritus being most abundant in the slow reach and least in the fast reach. Despite their strong response to reach, local densities of most microcrustacea (including many epibenthic species) did not vary with organic matter. Food for detritivorous microcrustacea may not be limiting in this highly retentive stream.

5. There was some evidence to suggest that different numbers of animals were retained in the three reaches during flow disturbances. One reach may function as a ‘flow refugium’. Models illustrating the processes by which lotic organisms may use flow refugia are presented and provide a framework for future empirical and theoretical studies.
Influence of ethanol and ethylene on the seed germination of three nymphaeid water plants
Authors: SMITS A.J.M. , SCHMITZ G.H.W. , VAN DER VELDE G. , VOESENEK L.A.C.J.
Published: May 2006

1. Under anaerobic conditions cold stratified seeds of Nymphaea alba and Nuphar lutea germinated readily and released ethanol (up to 6–7 mM ethanol g‐1 DW), whereas seeds of Nymphoides peltata did not germinate and hardly any ethanol was released (up to 1.5 mM ethanol g‐1 DW). Ethylene release by seeds of Nymphaea, Nuphar and Nymphoides incubated under hypoxic conditions could not be detected.

2. Under aerobic conditions all Nymphaea and Nuphar seeds germinated, but at a lower rate compared with anaerobic incubation. Ethanol release under aerobic conditions was low (1.5–2 mM ethanol g‐1 DW). Under aerobic conditions the seeds of Nymphoides germinated promptly and ethanol release was low (0–0.5 mM ethanol g‐1 DW).

3. Germination of Nymphaea and Nuphar seeds in an ethanol solution (350 mM) was generally stimulated compared with that in water, but no significant effect was recorded if seeds had not received a cold treatment or had been stratified for 8 weeks. Germination of Nymphoides seeds was inhibited in the ethanol solution unless they had received a cold treatment of 12 weeks.

4. Germination of Nymphaea and Nuphar was stimulated by ethylene (5 νg 1‐1) but germination in moist air was lower than under normal submersed conditions. A stimulating effect of ethylene on the germination of Nymphoides seeds was also evident.

5. It is suggested that ethanol and ethylene play an important role in determining niches for germination, contributing to the zonation of these nymphaeids in a water body.
Microcrustacean prey and macroinvertebrate predators in a stream food web
Authors: LANCASTER JILL , ROBERTSON ANNE L.
Published: May 2006

1. The consumption of microcrustacea by two polyphagous predators, larvae of the caddisfly Plectrocnemia conspersa (Curtis) and the alderfly Sialis fuliginosa Pictet, was investigated in an English stream with a well‐known macro‐ and microinvertebrate fauna. Benthic samples were collected in August, November, December and April, and the gut contents of all individuals of both predators were examined.

2. All the microcrustacean groups (Cyclopoida, Harpacticoida, Chydoridae and Ostracoda) were identified in gut contents. Of the ten taxa present in the benthos, all occurred in the diet of P. conspersa; nine were found in S. fuliginosa.

3. Ontogenetic shifts in the diets of both predators were found, and microcrustacea were consumed more frequently by small than large instars.

4. There was little evidence of selective feeding by P. conspersa, whereas ostracods were over‐represented in the diet of S. fuliginosa, compared with benthic relative densities. The Chydoridae were under‐represented in the diet of both predators.

5. The food web of Broadstone Stream is perhaps the most detailed web available for any running water habitat. Increased taxonomic resolution produced marked changes in values of connectance and predator‐prey ratios. Linkage density remained fairly constant at different levels of resolution and were high, indicative of a web of generalist species. Omnivory was pronounced and may be characteristic of donor‐controlled systems where organic detritus is the primary energy base.
Productivities of microbial decomposers during early stages of decomposition of leaves of a freshwater sedge
Authors: NEWELL S. Y. , MORAN M. A. , WICKS R. , HODSON R. E.
Published: May 2006

1. We examined standing‐senescing, standing‐dead and recently fallen leaf blades of Carex walteriana in fens of the Okefenokee Swamp to determine the nature of the microbial decomposers in the early stages of decomposition, measuring both standing crops and productivities ([3H]leucineprotein method for bacteria, [14C]acetateergosterol for fungi).

2. Fungal standing crops (ergosterol) became detectable at the mid‐senescence stage (leaves about half yellow‐brown) and rose to 14–31 mg living‐fungal C g−1 organic mass of the decaying system; bacterial standing crops (direct microscopy) were ± 0.2 mgC g−1 until the fallen‐leaf stage, when they rose to as high as 0.9 mgC g−1.

3. Potential microbial specific growth rates were similar between fungi and bacteria, at about 0.03–0.06 day−1, but potential production of fungal mass was 115–512 μgC g−1 organic mass day−1, compared with 0–22 μgC g−1 day−1 for bacteria. Rates of fungal production were about 6‐fold lower on average than previously found for a saltmarsh grass, perhaps because much lower phosphorus concentratiofis in the freshwater fen limit fungal activity.

4. There was little change in lignocellulose (LC) percentage of decaying leaves, although net loss of organic mass at the fallen, broken stage was estimated to be 59%, suggesting that LC was lost at rates proportional to those for total organics during decay. Monomers of fungal‐wall polymers (glucosamine and mannose) accumulated 2‐ to 4‐fold during leaf decay. This may indicate that an increase found for proximate (acid‐detergent) lignin could be at least partially due to accumulation of refractory fungal‐wall material, including melanin.

5. A common sequence in decaying aquatic grasses is suggested: principally fungal alteration of LC during standing decay, followed by a trend toward bacterial decomposition of the LC after leaves fall and break into particles.
The effects of shoot age on colonization of an emergent macrophyte (Typha latifolia) by macroinvertebrates
Authors: OERTLI BEAT , LACHAVANNE JEAN‐BERNARD
Published: May 2006

1. The colonization and dynamics of epiphytic aquatic macroinvertebrates are described on first‐year and second‐year shoots of an emergent macrophyte (Typha latifolia) in a Swiss pond. Effects of shoot senescence on composition, richness, density and biomass of the macroinvertebrates are quantified.

2. There were two phases of colonization: a short‐term colonization process which corresponded with that usually observed on inert substrates and a longer term colonization process related to the attractiveness of the shoots for the colonizers. In this second process, the older shoots showed a higher attractiveness for most invertebrate taxa.

3. Taxa colonized the shoots at different rates. Rapid colonizers included the limpet Ferrissia wautieri and the mayfly Cloeon dipterum. Conversely, Oligochaeta, Chironomidae and Ceratopogonidae were particularly slow colonizers.

4. The older shoots supported a higher mean annual richness, abundance and biomass of invertebrates. Compared with younger shoots, the older shoots demonstrated a higher carrying capacity for most invertebrate taxa, as is the case for many other freshwater macrophytes.
Tissue accumulation and the moult cycle in juveniles of the Australian freshwater crayfish Cherax destructor
Authors: MUSGROVE R.J.B. , GEDDES M.C.
Published: May 2006

1. This paper investigates moult stage and size‐specific changes in whole body composition during growth in juvenile crayfish in order to better describe the nature of growth and energy use.

2. Composition is described in terms of moult stage and size‐specific wet, dry and ash‐free dry weight, water, carbon, protein nitrogen, non‐protein nitrogen, ash and energy. Dry weight and ash‐free dry weight (AFDW) peaked in the middle and in the later stages of premoult. Both peaks were about 2–2.3 times postmoult weight. Losses in tissue weight during ecdysis were substantial in the smallest crayfish but declined with size. Water was taken up between late premoult and early postmoult. Tissue accumulation occurred primarily between B and D1.3, with further weight gain largely the result of fluid uptake. Ash increased immediately postmoult with a major peak occurring during intermoult. Mean organic carbon varied between 33 and 35.5% of the body and 49% of the exuvia. Chitin varied between 9 and 17% of body AFDW and made up about 50.5% of the exuvia. Protein content varied between 47 and 62% of body AFDW and about 25% of the exuvia. Carbon, chitin and protein were not affected by moult stage but protein declined with ocular carapace length (OCL) in larger crayfish. Mean caloric content varied between 19 and 22 J mg‐1 AFDW depending on size and moult stage. Caloric content increased with OCL during premoult and early intermoult then declined with size until part of the way through premoult.

3. Relationships between protein, chitin and remaining carbon (organic carbon minus chitin) were examined. It is suggested that protein and some carbon are catabolized during the moulting process, possibly to fuel metabolism. Models are presented showing changes in proximate composition over the moult cycle for two sizes of crayfish, and tissue and energy accumulation and loss over a series of moult cycles and sizes from 3.1 mm to 17 mm OCL.
Periodontal disease in a Rubinstein–Taybi syndrome patient: case report
Authors: FREITAS N. M. , IMBRONITO A. V. , LA SCALA C. S. K. , LOTUFO R. F. M. , PUSTIGLIONI F. E.
Published: May 2006

Summary.  Introduction.  Rubinstein–Taybi syndrome (RTS) is a rare disorder affecting 1 of 300,000 people, characterized by growth, mental and motor retardation, small stature, broad thumbs and toes, characteristic face, high‐arched palate, and recurrent respiratory infections.

Case report.  The present report describes the periodontal and immunological status of a 14‐year‐old female patient with RTS. Probing depth, clinical attachment level, bleeding on probing, and radiographic evaluation were performed. Periodontal examination revealed severe attachment loss in incisors and molars and generalized bleeding on probing. Periodontal treatment consisted of scaling and root planing and oral hygiene instructions. Periodontal treatment resulted in resolution of gingival inflammation and pocket depth reductions. The association of periodontal disease and RTS is previously undescribed.

Conclusion.  This case report underscores the importance of periodontal clinical diagnosis and the possibility of successful periodontal treatment in RTS patients.
Rhabdomyosarcoma of the mandible in a 6‐year‐old boy
Authors: DAVIDSON L. E. , SOLDANI F. A. , NORTH S.
Published: May 2006

Summary.  Introduction.  Rhabdomyosarcoma is an aggressive malignant tumour composed of neoplastic mesenchymal cells that infiltrate surrounding tissue structures, making their precise site of origin unclear. Although rare, this is highly aggressive and the most common soft‐tissue neoplasm of the head and neck in children. Regrettably by the time most cases are initially seen, the patients already have large tumours, due to rapid tumour growth and delayed medical consultation.

Case Report.  This report describes a 6‐year‐old presenting with just such symptoms of facial swelling and pain but elicitation of further information and findings, including tooth mobility of 3 days duration, led to prompt referral and early treatment of an embryonal rhabdomyosarcoma.

Conclusion.  General dental practitioners are frequently presented with a child with a swollen face and pain. Experience would suggest a dental abscess to be the most likely cause with treatment as appropriate. However, all swellings in children, should be thoroughly investigated and reviewed as particularly in this age group, tumour growth is rapid while early diagnosis allows successful treatment with multimodality therapy.
Attitudes about dental care among parents whose children suffer from severe congenital heart disease: a case‐control study
Authors: GRAHN K. , WIKSTRÖM S. , NYMAN L. , RYDBERG A. , STECKSÉN‐BLICKS C.
Published: May 2006

Summary.  Objectives.  To examine attitudes and experiences of parents whose children have complex congenital heart disease (CHD) with respect to dental health information and advice, dental care, and service and to compare the results with data from an age‐ and gender‐matched control group without any medical problems.

Setting.  Faculty of Medicine (Paediatric Cardiology and Paediatric Dentistry), Umeå University, Umeå, Sweden.

Sample and method.  Each group comprised parents of 33 children; the children's mean age was 9·4 years. All the cases and the controls resided in the county of Västerbotten, northern Sweden. Data were collected with a questionnaire with 20 joint questions to both groups and four additional questions to the CHD group.

Results.  Of the 20 joint questions, significant differences were displayed in the following areas: the professional group that provided the parents with dental health information and advice (P < 0·01), attitudes to reception at the dental clinic, and experience of sedation before operative dental treatment (P < 0·05). Parents to 11 children with CHD who were patients at a specialist clinic for paediatric dentistry scored the reception at the dental clinic as excellent in nine cases and satisfactory in two, compared to excellent (3), satisfactory (11), decent (4), and poor (4) among those who were patients in general dental practice (P < 0·01). No statistically significant differences in educational level or in parental experience of dental health were noted between the two groups (P > 0·05).

Conclusion.  Children with CHD in northern Sweden mainly receive their dental health information from a physician or a dentist, and healthy children mainly receive information from a dental hygienist indicating that children with CHD are given priority in the dental care system. Parental attitudes to reception in the dental service differed, and parents of healthy children scored the reception at the dental clinic better than parents of children with CHD. It is suggested that children with severe CHD should receive dental care in clinics for paediatric dentistry, particularly at early ages.
Comparison of articaine 4% and lidocaine 2% in paediatric dental patients
Authors: RAM D. , AMIR E.
Published: May 2006

Summary.  Objective.  To evaluate and compare the reaction of children who received local anaesthesia with lidocaine 2% with 1 : 100 000 epinephrine and articaine 4% with 1 : 200 000 epinephrine and to assess the time of the onset, efficacy, duration of numbness of the soft tissues, children's sensation after treatment to both anaesthetic solutions, as well as the occurrence of adverse events.

Samples and methods.  Sixty‐two children (34 girls and 28 boys) aged 5–13 years (mean age 8·4 ± 2·3) from two established paediatric dental clinics who needed similar operative procedures preceded by local anaesthesia were randomly assigned to receive either lidocaine or articaine at their first or second visit. Modified Taddio's behavioural pain scale was used to evaluate pain reaction during injection and treatment. The sensation after injection and treatment was evaluated using the Wong–Baker FACES pain rating scale. Parents recorded the time when the feeling of local anaesthesia in soft tissues disappeared.

Results.  Duration of numbness of soft tissues was significantly longer for articaine (3·43 ± 0·7 h) than for lidocaine (3·0 ± 0·8 h) (P = 0·003). No difference regarding the efficacy of the anaesthesia was observed.

Reaction to pain was similar for both local anaesthetic solutions and no significant difference was found between genders. The efficacy of the anaesthesia was similar for both solutions. The feeling after treatment was similar for both solutions. The rate of adverse effects was similar for the two solutions.

Conclusions.  Articaine 4% with 1 : 200 000 epinephrine is as effective as lidocaine 2% with 1 : 100 000 epinephrine. The effect of numbness of soft tissues was longer lasting with articaine than with lidocaine.