bluuebunny/crossref_metadata_2025_split huggingface dataset:
A silica budget for Lough Neagh 1970–1972
Authors: DICKSON E. L. 
Published: May 2006

SummaryIn this study of the Lough Neagh catchment a relationship has been sought between the loads of dissolved and total silica and the flow of each of the six inflowing rivers. Two of these rivers‐the Main and Six Mile Water‐carry a higher ratio of dissolved to total silica than do the remaining four rivers due to the geology of the catchment. The multiple regressions of loads in tonnes against river flows in cubic metres show a linear relationship for dissolved but not for total silica. The explanation for this non‐linearity has been sought in the river proaies, where the fall for the last 30 m varies from 5 to 25 km depending on the river. The rivers Main and Six Mile Water are the steepest, and linear relationships were obtained in their regressions while the shallowest profile was found in the Blackwater where non‐linearity in the multiple regression was obtained.In Lough Neagh the dissolved silica content was gradually reduced from early winter through to springtime by diatom growth and a balance has been drawn up for this utilization. This reduction also compares with the quantity in the diatom crop at maximum based on cell volume measurements. The summer build up of the dissolved silica content of the lough has been shown to be greater than the quantity contributed by the inflowing rivers from late spring to autumn and the data show that the recycling of silica from some 65% of the frustules from the spring crop after its collapse would account for the summer increase.
Weight of food and time required to satiate brown trout, Salmo trutta L.
Authors: ELLIOTT J. M. 
Published: May 2006

SummaryBrown trout of different weights (range 8‐358 g) were fed to satiation at fifteen different water temperatures (range 3.8–21.6°C. Both the weight of the trout (Wg) and the water temperature (T°C) affected the maximum weight of food (Q mg) consumed in a meal, and the relationship between the three variables was well described by a multiple regression equation which can be used to estimate the value of Q (with 95% confidence limits) for trout of different weights at different temperatures between 3.8°C and 21.6°C. The satiation time (with 95% confidence limits) can also be estimated from a multiple regression equation for trout of different weights at temperatures between 6.8°C and 18.1°C. Estimates from the multiple regression equations were applicable to a wide range of food organisms with the exception of larvae ofTenebrio molitor (mealworms). Appetite (measured by voluntary food intake) varied with temperature and was greatest between 13.3°C and 18.4°C. From comparisons with the results of other workers, it was concluded that the maximum amount of food consumed in a meal may provide sufficient calories for both the daily metabolic requirements and the daily maintenance requirements of a trout at temperatures between 3.8°C and 18.4°C, but not at temperatures above 18.4°C.
Critical notes on a proposed method to estimate production
Authors: ZWICK PETER 
Published: May 2006

SummaryTo estimate annual production, Hamilton (1969) initially calculated mean losses/sample, as did Hynes (1961) and Hynes & Coleman (1968). While the latter failed to convert these means to annual production, Hamilton has overcome this problem by assuming a population at equilibrium. Then, production may be calculated by multiplying mean losses with the number of classes through which specimens can grow. The method was claimed to be suitable for unidentified material and not to depend strongly on growth patterns; both claims are refuted here. The main objection is that for calculations, populations must be divided into fractions. While equilibrium might be acceptable for an entire population, it is not for any of its fractions. The particular conversion factor therefore has no justification and the method becomes inapplicable.
Food of the New Zealand trichopterans Hydrobiosis parumbripennis McFarlane and Hydropsyche colonica McLachlan
Authors: CROSBY T.K. 
Published: May 2006

SummaryThe food of the larvae of two New Zealand Trichoptera, Hydrobiosis parumbripennis and Hydropsyche colonica, was investigated between March and November 1971 at the Wainui Valley Stream, Canterbury, New Zealand. Most samples were collected from an experimental channel constructed in the stream in 1970. The first three instars of H. parumbripennis were mainly detrital feeders, whereas the two later instars were exclusively carnivorous. In contrast, H. colonica was omnivorous. The main prey taken by H. parumbripennis were larvae of a simuliid, Austrosimulium tillyardianum, Chironomidae (subfamily Orthocladiinae), and an ephemeropteran, Deleatidium sp. The first three instars appeared to select chironomids in preference to simuliids, whereas the converse was true for the final two instars. The main prey taken by H. colonica was A. tillyardianum. The size of prey and the mean number of prey found per larva of H. parumbripennis increased with each instar. Forage ratios indicated that H. parumbripennis were eating A. tillyardianum at the same relative frequency as their abundance in the fauna, but that the chironomids and Deleatidium sp. were being preferentially selected as prey. Cased caddis larvae were avoided as food items, as was the mollusc Potamopyrgus antipodarum. Although H. parumbripennis was the most important predator of A. tillyardianum in the stream, it is considered that it has little effect on the simuliid population.
The distribution and habitat separation of three corixids (Hemiptera: Heteroptera) in western Colorado
Authors: DODSON VIRGINIA E. 
Published: May 2006

SummaryThree species of Corixidae (Hemiptera : Heteroptera) were studied in thirty montane, sub‐alpine, and alpine ponds in Western Colorado. Callicorixa audeni Hung, had the widest altitudinal range (2800‐3400 m). Cenocorixa bifida Hung, was most common in montane ponds. Arctocorisa lawsoni Hung, was found only above 3100 m. C. audeni was significantly associated with C. bifida and A. lawsoni. Habitat selection was studied in two montane (2900 m) and one alpine (3480 m) pond. C. audeni utilized both mud and emergent sedges as perching and feeding sites, occurring more frequently in the sedges in the montane ponds. C. bifida was confined to the mud. In the alpine pond, A. lawsoni was most abundant on the mud; C. audeni occurred equally on the mud and in the sedges. All three species preferred shallow water (less than 0·5 m). A. lawsoni occupied deeper water more often than C. audeni. In substrate selection experiments C. audeni occupied emergent sedges more than C. bifida, confirming field observations. C. bifida occurred in sedges in the aquaria, but not in the montane ponds, suggesting that an interspecific interaction may be excluding C. bifida from the sedges in nature.
A pneumatic grab for obtaining large, undisturbed mud samples: its construction and some applications for measuring the growth of larvae and emergence of adult Chironomidae
Authors: MURRAY T. D. , CHARLES W. N. 
Published: May 2006

SummaryA description is given of the construction and operation of a pneumatic grab taking samples of mud 0.25 m2 in area, which can be removed without disturbance. These are of value in a variety of studies, and examples are given of their use for maintaining enclosed benthic populations and for measuring the emergence of adult Chironomidae.
Seasonal changes of Bosmina (Crustacea, Cladocera) in Frains Lake, Michigan: laboratory observations of phenotypic changes induced by inorganic factors
Authors: KERFOOT W. CHARLES 
Published: May 2006

SummaryIn Frains Lake, individuals of the species Bosmina longirostris decrease relative mucro and antennule lengths during the spring and summer, and increase them again during the fall. The cyclomorphosis involves both embryonic and post‐embryonic events, since the relative sizes of parts in neonates and the relative growth rates of parts in later instars change seasonally. Antennules grow during winter, but may even regress during summer. Mucrones show an opposite pattern, growing maximally during late summer and fall.The kinds of cyclomorphotic changes in Bosmina suggest evolutionary adjustments to two principle types of predators: visual vertebrates and blindly grasping invertebrates. While laboratory experiments implicate temperature and turbulence as proximate factors in the cyclomorphotic changes, some unknown factor (or factors) also appears necessary to stimulate the magnitude of responses observed in nature.
Periphyton production and grazing by chironomids in Alderfen Broad, Norfolk
Authors: MASON C. F. , BRYANT R.J. 
Published: May 2006

SummaryThe standing crops of periphyton were measured on dead Typha stems and glass rods in a small, eutrophic lake from February to November. Chironomid larvae were also counted on the Typha stems; very few were present on the glass rods. The standing crop of periphyton on the Typha stems fell from 1.8 mg cm−2 in early April to nearly zero in November. On the glass rods the periphyton reached a peak of 1.93 mg cm−2 in late May and 1.94 mg cm−2 in July, thereafter falling to a steady level of 1.6 mg cm−2. The population of chironomids showed a peak in late May and then declined. The alimentary canals of chironomids collected fromTyphastems contained diatoms and filamentous algae so it appeared that chironomids were grazing down the periphyton. Chironomids moved on to theTyphastems in spring and returned to the mud in autumn. The periphyton is a richer source of essential amino acids than the mud, so that a movement from mud to reedstems in spring may increase the rates of growth and metamorphosis of the larvae.A crude production estimate gave a net primary production of periphyton of 170 mg dry wt m−2 day−1; the periphyton, however, would have contained bacteria and many small animals as well as algae.
Downstream drift of invertebrates in a river in southern Ghana
Authors: HYNES J. D. 
Published: May 2006

SummaryThe results of quantitative sampling of the drifting invertebrates from a riffle area in the upper reaches of the Pawmpawm River in the forest of Ghana are presented. The observations were made once a month during 14 months, April 1970 to May 1971, and also on a daily basis for 3 weeks. Changes in numbers and composition of the animals drifting were examined in relation to the volume of water flowing and the current; there appeared to be two distinct drift phenomena, ‘true’ and ‘background’ drift. The animals belonging to each of these two components are discussed in relation to their response to light, to diurnal fluctuations in total drift and to the phases of the moon. There was a peak drift activity after sunset in those animals which are affected by light, e.g. Centroptilum, Austrocaenis, Chironomidae, Simulium. It is concluded that drift may be simply a function of the activity patterns of the insects.
Chemistry and biology of the South Winterbourne, Dorset, England
Authors: CASEY H. , LADLE M. 
Published: May 2006

SummaryChanges in discharge and chemical composition are related to biological and physical conditions at eight sites on the South Winterbourne from the source to the confluence with the River Frome. The results show a complex pattern of discharge with nitrate peaks at high discharge values. Mean phosphate values varied from 34·2 μg l−1 (at the source) to 164·6 μg l−1.The Winterbourne has a rich flora of algae and higher plants of which the annual sequence is influenced by the flow regime and the effects of human interference by cutting and removal of plants and addition of nutrients. The fauna has much in common with permanent chalk streams but temporary flow conditions favour insects having prolonged resting stages or those which are able to colonize quickly from other areas when flow commences. Many non‐insect groups particularly snails, are able to withstand relatively long dry periods.
Biomass and energy transfer by a specialized predator of aquatic snails
Authors: ECKBLAD JAMES 
Published: May 2006

SummaryThe predatory larvae of Sepedon fuscipennis (Diptera: Sciomyzidae) feed only on aquatic pulmonate snails. Under laboratory conditions these larvae utilized ingested snail tissue more efficiently when a lower snail biomass was ingested at lower snail densities. The adaptive value of this response to fluctuating prey availability is suggested.
The colonization of squares of plastic suspended in midwater
Authors: MACAN T. T. , KITCHING ANNETTE 
Published: May 2006

Summary(1) A flat substratum hung in midwater is colonized rapidly by a number of species normally found in vegetation. Some have been recorded consistently, a greater number occasionally, but only a few have not been recorded at all. Evidently most species are moving round frequently, even those, such as snails and case‐building caddis‐larvae, that cannot swim. (2) It seems likely from this that the identity of the plant cover has less influence on the structure of a community than some have thought. (3) A comparison of flat sheet, pleated sheet and artificial Littorella suspended in midwater makes possible certain statements and deductions. (i) Leptophlebia, Enallagma and chironomid larvae are more numerous on artificial Littorella; their natural habitat is within the vegetation cover. (ii) Cloeon, Cyrnus and Holocentropus are as numerous on the sheets or more numerous than in the artificial vegetation; they inhabit the surface of the plant cover where Cloeon is protected by its speed, and where the polycentropopids, protected by their nets, can trap both the true plankton and the Cladocera which feed in the vegetation. (iii) The foot of a snail and the suckers of a leech are most effective on a flat surface, which also provides a good feeding place for a snail. The higher numbers of Lymnaea and Erpobdella on the pleated compared with the flat sheets indicates the importance of cover for these two animals. (4) Flat plastic sheets hanging in the illuminated zone would improve the production of fish a little, pleating the sheets would improve it a little more, and best results would come from hanging something with a greater resemblance to natural vegetation.
Observations on the superficial sediment temperatures of some lakes in the southeastern United States*
Authors: LEWIS WILLIAM M. 
Published: May 2006

SummaryTemperatures of the water column and upper 5 cm of sediment were monitored over a yearly cycle in two South Carolina lakes. Occasional supportive data were also obtained for several lakes in north central Florida. Plans are given for a new type of sediment‐interface sampler that is useful in obtaining detailed temperature or chemical profiles extending from the sediment surface upward. The sampler was used in the investigation to demonstrate the thermal microstratigraphy near the mud surface.The deep‐water (16 m) temperature for the larger of the two South Carolina lakes changes seasonally from 10·5°C in February to 18·0°C in July. The smaller, shallower (11 m) lake follows an almost identical seasonal cycle but is always 4·0°C cooler because the larger lake receives a heated effluent that has a long‐term effect on hypolimnetic temperatures. In both lakes the uppermost sediments are warmer than the overlying water by an average of 0·1 to 1·0°C during the warming period. Heat accretion near the bottom continues but is slower after stratification, probably due to the relatively low temperature (density) differential between water layers in these warm lakes. Cooling in deep water begins long before breakdown of stratification and is apparently caused by cold density currents from the shallows. The coldest water is located in a thin layer just over the sediment. There is evidence from one of the South Carolina lakes and from the Florida lakes that when the density flows begin they at first flow over a warmer water layer that is more dense due to a high electrolyte content derived from the sediment.There is a slight deep water warming in all of the lakes when stratification breaks down. After destratification, the deep water is cooled by turbulence rather than density flows. The surface sediments at this time are consistently warmer than the hypolimnion and remain so through the cooling period. There is strong evidence from one Florida lake that turbulence mixes the upper 3 cm of sediment during the isothermal period.It is concluded that the sediment‐water interface of a warm lake will in general experience greater heat flux than that of a comparable cold lake during the periods of temperature maximum and minimum. Conversely, there is likely to be less heat flux during the warming and cooling periods of warm lakes than of cold lakes. Several expected differences in seasonal patterns of temperature and water movement in the deep water of warm and cold lakes are discussed.
Nitrogen nutrition of Myriophyllum spicatum: uptake and translocation of 15N by shoots and roots
Authors: NICHOLS DALE S. , KEENEY DENNIS R. 
Published: May 2006

SummaryIntact Myriophyllum spicatum plants were grown in compartmentalized containers in a growth room so that the roots were separated from the shoots by a watertight partition. Nitrogen 15N was added to the water or sediment to trace the uptake of inorganic N by the plant shoots or roots. Myriophyllum spicatum is capable of taking up inorganic N through both roots and shoots. Plant N requirements can apparently be met by root uptake alone. However, when about 0·1 mg/l of NH4‐N were present in the water, foliar uptake supplied more N to the plants than did root uptake. Foliar uptake of NH4‐N was found to be several times faster than that of NO3‐N when both forms of N were present in the water. Only about 1% of the N taken up by the roots was subsequently released to the water through the foliage.
The distribution of the freshwater Malacostraca in the area of the Mersey and Weaver River Authority
Authors: HOLLAND D. G. 
Published: May 2006

SummaryFreshwater Malacostraca distribution data acquired through the routine biological work of a river authority is of general scientific interest. The distribution of Asellus aquaticus and Gammarus pulex is related to pollution and natural factors. Although widespread in the area, both species are absent from an extensive part of the major river system. A. meridianus appears to be less successful in competition with A. aquaticus and is comparatively scarce, being mostly limited to isolated pools. The distribution of Crangonyx pseudogracilis in canals and static waters is also related to pollution and natural factors. Orchestia cavimana, a semi‐terrestrial amphipod, is shown to be an overlooked species which is common in canals.
The inland distribution of brackish‐water Gammarus species in the area of the Mersey and Weaver River Authority
Authors: HOLLAND D. G. 
Published: May 2006

Summary(1) Many inland saline waters exist in Cheshire and South Lancashire mostly in association with the Cheshire Salt Field.(2) The presence of brackish‐water Gammarus species in this area has been known for many years but has never previously been fully documented.(3) The saline waters are described in detail.(4) The distribution of three species of Gammarus in all these waters is also described.(5) Theories are put forward to explain the presentday distribution of the species in relation to the possible points of entry into the area.
A trap for capturing planktonic chironomid larvae
Authors: DAVIES BRYAN R. 
Published: May 2006

SummaryThis paper describes the construction and field operation of a trap designed to investigate the movements of larval Chironomidae in the open water of lakes. Although the trap was designed to be multidirectional, with six trapping bottles, only two directional components, vertical and horizontal, could be distinguished. This led to examination of three bottles only during later field studies, namely bottle 1 facing into the current, bottle 5 facing the substrate and bottle 6 facing the surface of the lake. Some results are presented and trap operation and sampling efficiency discussed.A major advantage of the trap is its use as a long term accumulator of planktonic organisms as opposed to traditional spot sampling techniques which tend to miss the less numerous plankters.
Temperature dependence of food intake, ammonia excretion and respiration in Ceriodaphnia reticulata (Jurine) (Lake Kinneret, Israel)*
Authors: GOPHEN MOSHE 
Published: May 2006

SummaryThe abundance of Ceriodaphnia reticulata (Jurine) in Lake Kinneret is restricted every year to the period March to June with a peak in May. The most constant parameter accompanying the peak is temperature with a range of 20–22° C. An attempt was made to clarify whether the estival high average temperatures observed in the epilimnion of this lake (27–28° C) could explain the decrease of the Ceriodaphnia population.Three physiological parameters: food intake, ammonia excretion and respiration rates, were measured experimentally at three temperatures (15, 22 and 27° C). The dry weight of individuals of the winter and summer populations were measured, and the percentages of egg‐bearing females in the populations were calculated.It was found that temperature increase accelerates the rates of ammonia excretion and food ingestion. The acceleration was greater in the lower temperature range (15–22° C) than in the higher one (22–27° C). Conversely, the enhancing of respiration rate is higher in the upper temperature range. The resulting deficit of energy at high temperatures causes a reduction in body size and a significant diminution of egg production, which leads to a progressive decline of the population.
Chironomid communities in small prairie ponds: some characteristics and controls
Authors: DRIVER E. A. 
Published: May 2006

SUMMARY. In a study of small prairie ponds in Central Saskatchewan, chironomid diversity was dependent on the stage of development of the plant community within a moisture gradient. Changes in the moisture regime affect the plant community directly, which in turn influences the diversity of the chironomid community. Rapid or complete water level reduction in a pond maintains a very simple chironomid community, three to ten species, and a simple plant community of two to three dominant species. Increased water levels eliminate emergent and submergent plants, thereby eliminating those chironomid species which live in association with the plants. Pond morphometry (mean depth, maximum depth, surface area) and water chemistry (pH and bicarbonate) showed positive relationships with chironomid diversity. The precise nature of these relationships was not determined.Chironomid diversity increases gradually from very temporary ponds to permanent ponds, therefore, chironomids can be used as indicators of pond permanency.