bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forests and the temperature of upland streams in Wales: a modelling exploration of the biological effects
Authors: WEATHERLEY N. S. , ORMEROD S. J. 
Published: May 2006

SUMMARY. 1. Daily temperature data from six streams in upland Wales were used to explore the thermal effects of afforestation on stream ecology. The data were linked to published biological models to simulate fish and invertebrate development.2. Mean daily temperatures in forest streams were lower than those of moorland streams in spring and summer, and higher in winter. These spatial comparisons were supported by the results of experimental bank‐side clearance at a forest site, where there was evidence that stream temperatures fell in winter and rose in spring following treatment.3. Simulations indicated that brown trout (Salmo trutta) could weigh over 30% more by the end of their second growing season in a moorland compared with a forest stream. Several species of insects showed slower simulated egg development at forest sites. For two ephemeropteran species simulated nymphal growth was also retarded, suggesting significant alterations to the life cycle. Two plecopteran species were affected only slightly by the different temperature regimes.4. Overall, the simulations suggested that afforestation, by reducing summer temperatures, could lead to marked reductions in rates of development of some invertebrates and fish.
The turbulent boundary between water science and water management
Authors: CULLEN PETER 
Published: May 2006

SUMMARY. 1. It is common to observe friction between limnologists and the managers of water resources. This is often a result of misunderstandings about the cultures within which each works.2. There are a number of ways that science can contribute to effective management of water resources, but limnologists must appreciate that there are value questions which are not the sole prerogative of science to answer.3. Managers often misunderstand science and expect it to deliver a truth that is non‐arguable. They fail to understand the very process of science demands no such truths, so that assumptions, methods and conclusions can always be challenged.4. One way to bridge this boundary is to develop the scientific broking role. Another is to do better and more relevant science. Ways of doing both are discussed.
Toxicity of a soluble peptide from Microcystis sp. to zooplankton and fish
Authors: PEÑALOZA R. , ROJAS M. , VILA I. , ZAMBRANO F. 
Published: May 2006

SUMMARY.

A soluble cell fraction lethal to Daphnia magna was isolated by the disruption of net phytoplankton from eutrophic Aculeo Lake. The phytoplankton of this lake is dominated by Microcystis sp.
The soluble fraction was also lethal to common native zooplankton, including the rotifers Keratella sp., Trichocerca similis, the copepod Boeckella sp., and the cladoceran Chydorus sphaericus. In addition, a partially purified soluble component of the lethal fraction caused the death of the fish Gambusia affinis.
The specific toxicity of the soluble fraction from phytoptankton varied four‐ to six‐fold seasonally with peaks during periods of warm temperature.
Our results suggest that releases of a toxic peptide from Microcystis sp. may be the cause of massive fish kills at the study site, Aculeo Lake.
Species distributions and shell characteristics of Pisidium (Mollusca: Bivalvia) in the Colorado Front Range: the role of abiotic factors
Authors: SAUNDERS JAMES F. , RUNG GEORGE W. 
Published: May 2006

SUMMARY.

Forty lakes in the Colorado Front Range were sampled to examine the relationship between water chemistry and the distributions and shell characteristics of Pisidium species. Alkalinity, pH, and dissolved organic carbon contributed most to the classification of lakes according to the dominant Pisidium species. Alkalinity was also strongly correlated with mean clam weight for populations of P. casertanum, the most common of the five species collected.
Historical evidence shows a reduction in the number of lakes occupied by clams and a constriction in the distributions of certain species. These changes have occurred mainly in lakes that now have low alkalinity.
A role for acidification is suggested because the recorded changes in distributions have occurred during the last 20 years, coincident with a general decline in alkalinity in waters of the Front Range.
A quantitative study of mortality at emergence in the damselfly Pyrrhosoma nymphula (Sulzer) (Zygoptera: Coenagrionidae)
Authors: GRIBBIN SIMON D. , THOMPSON DAVJD J. 
Published: May 2006

SUMMARY.

Emergence of the damselfly Pyrrhosoma nymphula was studied over three seasons in two ponds in northern England.
Numbers emerging were significantly negatively correlated with temperature and atmospheric pressure.
Overall mortality at emergence was 28%. of which predators (largely birds, ants and spiders) accounted for 22% and climatic factors 6%.
Daily mortality estimates were significantly positively correlated with precipitation.
There was no evidence of density dependent mortality at emergence.
The food and daily food consumption of lacustrine 0+ perch, Perca fluviatilis L.
Authors: TREASURER JAMES W. 
Published: May 2006

SUMMARY.

The diet and daily food consumption (Ct) of 0+ perch were investigated in two shallow Scottish lakes.
The first food comprised the rotifer Keratella sp., Volvox sp., copepod nauplii and stage I copepodites of Cyclops strenuus abyssorum Sars. Larger copepodites and adults of C. s. abyssorum and Diaptomus gracilis Sars were consumed as larvae grew and cladocerans were also eaten by larvae >11 mm. The diet of juveniles included a wider range of cladocerans and benthic invertebrates. Cannibalism was not observed among 0+ perch.
The range of food items taken by larvae increased with length, and the size of food particles ingested was governed by jaw gape which was linearly related to fish length.
Larvae fed during daylight hours with feeding maxima in midmorning and the evening.
The arithmetic (constant) rate of evacuation R of the digestive tract of larvae was 0.59—1.16% of body weight h−1 and exponential R was 0.21–0.33% h−1. Daily Ct calculated using an arithmetic model was 14.2–23.4% body weight at water temperatures of 12.5–18.2°C, and 23.9–40.3% utilizing an exponential method. For larvae of 9 mm. this was 46 μg dry weight day−1 and 148 by an exponential model. Food conversion efficiency was 37–72% (arithmetic model) and 21–45% (exponential model).
Macroinvertebrate size‐distributions of two contrasting freshwater macrophyte communities
Authors: HANSON JOHN MARK 
Published: May 2006

SUMMARY.

Macroinvertebrates (>0.1 mg, fresh weight) were collected every 2 weeks for 18 weeks from weedbeds dominated by either the macroalga Chara or rooted plants (mostly Isoetes sp., Potamogeton filiformis, Nuphar variegatum and Myriophyllum exalbescens) in Narrow Lake, Alberta, Canada. Significant differences in total biomass, taxonomic composition, and size‐structure of the macroinvertebrate community were found between the two weedbed types.
Total biomass of macroinvertebrates in the Chara beds (seasonal mean 26.4 g m−2) was consistently higher than in the rooted‐plant weedbeds (seasonal mean 7.6 g m−2).
The macroinvertebrate community of the Chara beds was dominated by chironomids, anisopterans, gastropods and sphaerid clams whereas amphipods dominated the community in the rooted‐plant weedbeds.
On average, the proportion of total biomass in the various size‐classes (biomass size‐spectrum) of the macroinvertebrate community in Chara beds varied very little between 1 and 512 mg. In rooted plant weedbeds, the spectrum showed a strong peak in the 4–8 mg size‐class, a weak peak in the 32–64 mg size‐class, and proportionately low biomass in the 128–256 mg and 256–512 mg size‐classes. The slope of the normalized size‐spectrum for the macroinvertebrate community of the Chara beds (‐0.89) was significantly different from that of the rooted plant community (‐1.11). The biomass of large organisms (>64 mg) was 10 times greater in the Chara beds than in the rooted‐plant weedbeds.
The species composition of aquatic macrophyte beds can greatly influence the abundance, taxonomic composition, and size‐structure of the littoral zone macroinvertebrate community. Therefore, any changes in plant species composition of weedbeds, through introduction of exotic plant species or introduction (or loss) of an efficient grazer (e.g. crayfish), have the potential to alter greatly the structure of the macroinvertebrate community in a lake, with unknown consequences to fish and waterfowl dependent upon these prey.
Indirect effects of fish predation on calcite supersaturation, precipitation and turbidity in a shallow prairie lake
Authors: HANSON MARK A. , BUTLER M. G. , RICHARDSON J. L. , ARNDT J. L. 
Published: May 2006

SUMMARY.

We tracked calcite saturation and seston composition during 1987 and 1988 in a shallow, hardwater prairie lake, 1 year before and 1 year after a lake‐wide fish removal. We also measured the contribution of calcite to turbidity during 1988.
In both years calcite saturation increased rapidly after all ice had thawed and peaked during mid‐late summer with the mineral saturation index of calcite (SI) sometimes exceeding 30.
Removal of calcite from lake seston by gentle acidification of unfiltered water samples showed suspended calcite to be an important source of lurbidity in this lake.
The lake‐wide fish removal produced detectable changes in the annual cycle of calcite saturation and precipitation. Increased grazing by Daphnia galeata and Daphnia pulex apparently reduced calcite saturation during early summer by suppressing the phytoplankton, and lowering the demand for CO2.
Lower calcite precipitation, as well as direct removal of calcite by Daphnia grazing, probably contributed to the improvement in water transparency observed after the fish kill.
Transported material in a small river with multiple impoundments
Authors: PALMER ROBERT , O'KEEFFE JAY 
Published: May 2006

SUMMARY.

The transport of particulate material in a multiply‐impounded southern African river was studied from source to mouth over a period of 2 years during base flow conditions.
More than 95% of the dissolved and particulate material in transport was ultra fine (<80 μm). We conclude that too much emphasis has been placed on coarse material (>1 mm) in theories of river ecosystem functioning.
The ratio of CPOM:FPOM (1000–4000:250–1000 μm) in transport decreased with increasing stream order as a result of inputs of FPOM from pollution sources and from plankton blooms discharged from reservoirs.
The downstream effects of impoundment depended largely on the type of release and the quality of the inflowing water: surface‐releasing reservoirs in the clean, upper reaches of the river had the least effect on transported material. A polluted surface‐release impoundment in the mid‐reaches of the river converted the particle size spectrum of the river from small (<80 μm) to large (250–1000 μm). Bottom‐released water carried high concentrations (36–190 g m3) of small (<5 μm) and largely inorganic (86–93%) material.
The distance required for zooplankton densities to reduce by 95% was between 4 and 8 km downstream of an impoundment, except below a polluted impoundment where zooplankton densities took 32–35 km to reduce by 95%.
Most of the downstream changes in transported organic matter in the Buffalo River are due to inflows of agricultural and urban effluent. These disturbances to the river cause greater perturbations than do the impoundments.
Density—body size allometry does not exist in a chironomid community on Myriophyllum
Authors: TOKESHI MUTSUNORI 
Published: May 2006

SUMMARY.

It has been proposed that population density is allometrically related to body size for a wide range of animal species. An interesting question is whether this applies to species within a specific community or trophic guild, thus constituting a ‘pattern’ of community structure.
Density‐body size allometry can be translated into the relationship between population biomass (B) and population density (N). If the regression coefficient b in log B = a + b log N approximates 1, there is no allometric relation between density and body size.
Data from an epiphytic chironomid community show b∼1, thus indicating that no density‐body size allometry exists in this community.
Biomass is less equitably distributed than numbers among species in this and many other communities.
There is some difficulty in extending the logic of the density‐body size allometry to many invertebrate communities, where body size is a strongly time‐dependent, variable trait.
Cellulose digestion and metabolism in the freshwater amphipod Gammarus pseudolimnaeus Bousfield
Authors: CHAMIER ANNE‐CAROLE 
Published: May 2006

SUMMARY.
1. Weight‐specific respiration and feeding rates of Gammarus pseudolimnaeus were inversely related to body weight at 12°C, the temperature of the stream from which they were collected.2. At this temperature animals could digest about a third of ingested, purified 14C‐cellulose. In animals greater than 20 mg live weight, about 38% of ingested cellulose was metabolized; animals smaller than 20 mg metabolized about 28%.3. Respired CO2 from cellulose metabolism was 33–47% of measured uptake of C2 in animals greater than 20 mg live weight and approximately 25% in smaller animals.4. Ability to digest cellulose would be of nutritional benefit to Gammarus feeding on any plant material, but would be of particular advantage in the spring/summer period when fine detritus is the main foodstuff.
Tolerance and resistance to thermal stress in juvenile Atlantic salmon, Salmo salar
Authors: ELLIOTT J. M. 
Published: May 2006

SUMMARY.
1. The chief objective was to construct a thermal tolerance polygon for juvenile Atlantic salmon, Salmo salar L., using fish from four groups and two populations: two age groups from one population (0+, 1+ parr from River Leven), two size groups from the other population (slow and Fast growing 1+ parr from River Lune).2. Fish were acclimated to constant temperatures of 5, 10, 15, 20, 25 and 27°C; then the temperature was raised or lowered at 1°C h−1 to determine the upper and lower limits for feeding and survival over 10 min, 100 min, 1000 min and 7 days. As they were not significantly different between the four groups of fish, values at each acclimation temperature were pooled to provide arithmetic means (with SE) for the thermal tolerance polygon.3. Incipient lethal levels (survival over 7 days) defined a tolerance zone within which salmon lived for a considerable time; upper mean incipient values increased with increasing acclimation temperature to reach a maximum of 27.8±0.2°C, lower mean incipient values were below 0°C and were therefore undetermined at acclimation temperatures <20°C but increased at higher acclimation temperatures to 2.2±0.4°C. Resistance to thermal stress outside the tolerance zone was a function of time; the ultimate lethal level (survival for 10 min) increased with acclimation temperature to a maximum of 33°C whilst the minimum value remained close to 0°C. Temperature limits for feeding increased slightly with acclimation temperature to upper and lower mean values of 22.5±0.3°C and 7.0±0.3°C.4. In spite of different methodologies, values in the present investigation are similar to those obtained in previous, less comprehensive studies in the laboratory. They also agree with field observations on the temperature limits for feeding and survival. Thermal tolerance polygons are now available for eight species of salmonids and show that the highest temperature limits for feeding and survival are those recorded for juvenile Atlantic salmon.
Lethal and sub‐lethal effects of acid, aluminium and lime onGammarus pulexduring repeated simulated episodes in a Welsh stream
Authors: McCAHON C. PETER , POULTON MADELINE J. 
Published: May 2006

SUMMARY.1. A soft‐water stream in upland mid‐Wales was dosed with sulphuric acid, aluminium sulphate and limestone slurry to produce a zone of aluminium at low pH. and one of aluminium, low pH and added lime.2. Three episodes of 24‐h duration were induced, each separated by a 12‐h inter‐dosing period, and the responses of the crustaceanGammarus pulexmonitored throughout.3.G. pulexparasitized by the acanthocephalanPomphorhynchus laeviswere significantly more sensitive than unparasitized individuals.4. Liming significantly reduced mortality during dosing but postexposure deaths were greatest for animals which had been exposed in the time zone.5. The disruption of precopulalory behaviour inG. pulexwas rapid and liming did not mitigate this response.
Rates of gastric evacuation in piscivorous brown trout, Salmo trutta
Authors: ELLIOTT J. M. 
Published: May 2006

SUMMARY.
1. The dry weight of food remaining in the stomachs of piscivorous trout decreased exponentially with time. Gastric evacuation rates increased exponentially with increasing temperature but were unaffected by predator size, meal size or type of fish prey.2. Mathematical models were developed to estimate both the rate and time for the gastric evacuation of different meal sizes (expressed as dry weight), and were applicable to piscivorous trout of different sizes (length range 10–32 cm) feeding on trout fry or sticklebacks at different temperatures (range 5–18°C).3. The wet weight of food in the stomachs also decreased exponentially with time, but evacuation rates both increased with temperature and decreased with increasing meal size; the latter relationship occurred because relative rates of water loss from a meal also decreased with increasing meal size. Use of wet or dry weights can therefore lead to different conclusions about the effect of meal size on evacuation rates.4. When piscivorous trout were fed three consecutive meals of varying size, the models predicted the total dry weight of food left in the stomach, but not the weight remaining for each individual meal. Interactions between meals led to an increase in evacuation rates for meals consumed early in the series and a decrease in evacuation rates for later meals.5. Evacuation rates for piscivorous trout were compared with those for trout feeding on invertebrates in an earlier study, and were close to those for caddis larvae as prey, higher than those for mealworms and lower than those for a variety of invertebrate prey. Although a great deal is now known about the daily food intake and growth rates of trout feeding on invertebrates, there is little comparable information for piscivorous trout.
Longitudinal variation in recolonization rates of macroinvertebrates along an upland river in south‐eastern Australia
Authors: MARCHANT R , LAKE P.S. , DOEG T.J. 
Published: May 2006

SUMMARY.
1. Recolonization rates of benthic invertebrates were estimated at five sites in the catchment of the Acheron River, in spring (October) and in summer (January), The sites ranged from those that experience short floods and high shear stress at the streambed (upstream sites) to those that experience prolonged floods and low shear stress (downstream sites). We hypothesized that these differences should affect recolonization rate.2. In October, absolute rates of recolonization of taxa (number of taxa 0.05 m−2 d−1) onto 1‐m2 patches of substratum, which had been raked to remove fauna, did not vary between the three sites studied, nor did the relative rates of recolonization of taxa (absolute rate/mean number of taxa in control samples, which were taken from adjacent undisturbed patches of substratum). Absolute rates of recolonization of individuals (number of individuals 0.05 m−2 d−1) were proportional to the mean number of individuals in control samples; relative rates of recolonization of individuals (absolute rate/mean number of individuals in control samples) did not vary between sites.3. In January, absolute rates of recolonization either of taxa or individuals were positively correlated with the mean densities of taxa or individuals in control samples; relative rates did not vary between the four sites studied.4. We conclude that the benthic invertebrate communities at the various sites do not adapt to variations in flooding regime by altering relative recolonization rates. Absolute recolonization rates are directly proportional to the prevailing number of taxa or individuals at a site.
Changes in structure and composition of an assemblage of Hydroporus species (Coleoptera: Dytiscidae) along a pH gradient
Authors: JULIANO STEVEN A. 
Published: May 2006

SUMMARY.
1. Patterns of total abundance and species relative abundances in an assemblage of predatory dytiscid beetles of the genus Hydroporus were examined along a pH gradient within a ditch in north‐cast England.2. During spring, total abundance of adult Hydroporus was greatest at the less acidic (pH 5.6–6.2) upstream sites, whereas total abundance of larval Hydroporus was greatest at the more acidic (pH 4.5) downstream sites. Both adults and larvae were more abundant in samples from the edge than from the middle of the ditch.3. Species number and evenness did not differ along the pH gradient.4. Species relative abundance patterns varied along the pH gradient, with particular species dominating at different sites. However, relative abundances of species changed discontinuously along the pH gradient.5. Comparison of species abundance patterns along this pH gradient with published patterns of presence/absence among bodies of water with different pH revealed that species relationships with pH are often not consistent. Possible sources of this inconsistency are: geographic variation in species' pH preferences; complex responses of individual species to many factors in addition to pH; or random variation among sites due to colonization and extinction history.6. The overall results suggest that pH is not the only, or even the most important, factor influencing Hydroporus populations and assemblage organization.
Influence of food quality on growth and reproduction in Daphnia
Authors: GROEGER ALAN W. , SCHRAM MARK D. , MARZOLF G. RICHARD 
Published: May 2006

SUMMARY.
1. Growth and reproduction were measured for Daphnia pulex (Leydig) fed Scenedesmus obliquus (Turp.) Kutz. grown with nitrogen‐sufficient and nitrogen‐deficient media. The incorporation of carbon into the body of D. pulex was traced using 14C‐labelled algae and biochemical fractionation.2. Scenedesmus cultured on N‐defkient media allocated more carbon to lipid and less to protein than when cultured on N‐sufficient media.3. In a short‐term feeding experiment, Daphnia accumulated more lipid when fed N‐deficient algal cells high in lipid content than when fed algae grown on N‐sufficient media that were lower in lipid.4. Animals grew faster and produced larger broods when fed algae grown on an N‐sufficient medium over an 8‐day period. Daphnids fed N‐deficient algae had higher quantities of body lipid, suggesting it was not a lack of energy which limited their growth and reproduction.5. Daphnia fed algae grown on N‐deficient media allocated more lipid to eggs, and their offspring lived longer under starvation conditions.