bluuebunny/crossref_metadata_2025_split huggingface dataset:
Costs and consequences of superparasitism in the polyembryonic parasitoidCopidosoma koehleri(Hymenoptera: Encyrtidae)
Authors: KEASAR TAMAR , SEGOLI MICHAL , BARAK ROI , STEINBERG SHIMON , GIRON DAVID , STRAND MICHAEL R. , BOUSKILA AMOS , HARARI ALLY R. 
Published: May 2006

Abstract1. Polyembryonic wasps provide dramatic examples of intra‐specific developmental conflict. In these parasitoids, each egg proliferates into a clonal lineage of genetically identical larvae. If more than one egg is laid in a host (superparasitism), individuals of different clones may compete for food resources.2. In the polyembryonic encyrtidCopidosoma koehleri, one larva per clone can differentiate into a sterile soldier. It is shown that soldiers are always females, and that they attack intra‐specific competitors.3. Research hypotheses were that (a) clones that develop in superparasitised hosts suffer heavier mortality than clones that develop in singly parasitised hosts, and (b) female clones cause higher mortality to their competitors than male clones, hence larval survival is lower in superparasitised hosts that contain females than in male‐only broods.4. The potential frequency of superparasitism inC. koehleriwas manipulated by varying parasitoid–host ratios and exposure durations.5. As parasitoid densities and exposure durations increased, the frequency of superparasitism rose, brood sizes increased, but the number of hosts that completed development was reduced. The number of offspring per parasitoid female decreased with increasing parasitoid–host ratios. Offspring size and longevity were inversely correlated with brood size. As superparasitism rates increased, fewer all‐male broods were produced. Male–female broods were female‐biased, suggesting selective killing of males by female soldiers. All‐female broods were significantly smaller than all‐male broods at high parasitoid densities only, possibly reflecting aggression among soldiers of competing clones.6. The results support the working hypotheses, and suggest that female larvae outcompete males in superparasitised hosts.
Observations on some aquatic Actinomycetes of streams and rivers
Authors: WILLOUGHBY L. G. 
Published: May 2006

SummaryActinomycetes of the family Actinoplanaceae, especially Actinoplanes, are readily isolated from the flowing waters of local rivers and streams and it seems clear that such lotic environments are favoured for colonization by these organisms. In this contribution evidence is produced that part at least of this activity can be ascribed to the utilization of wood as a growth substratum. Some other aquatic Actinomycetes of less certain affinity were also shown to be capable of growth on wood, under the conditions of pure culture.
The ecology of newt tadpoles
Authors: AVERY R. A. 
Published: May 2006

SummaryFood consumption of newt tadpoles caught during July and August was estimated as C=34W1·11±0·12 where C is food consumption in milligrams wet weight/day and W is the live weight in grams.Well‐fed tadpoles assimilated the food with an efficiency of 90–6%, but at low rates of feeding, the efficiency fell. Gross growth efficiency was about 35 % at maximum rations.
Factors affecting the distribution of some Phryganeaeid (Trichoptera) in Malham Tarn, Yorkshire
Authors: BRAY R. P. 
Published: May 2006

SummaryThis paper describes a distribution problem involving Agrypnetes crassicornis and Phryganea obsoleta (Trichoptera : Phryganeidae) in Malham Tarn, Yorkshire. The only suitable habitat for their larvae is the offshore vegetation, chiefly Chara delicatula, but owing to the specialized egglaying behaviour of this family and the absence of other sites, the eggs of Agrypnetes crassicornis are laid on the exposed rocky shoreline. The situation with Phryganea obsoleta differs in that the emergence of Potamogeton spp. provides new oviposition sites away from the shore. Investigations on both species however have provided further support for an hypothesis which postulates the importance of wind‐induced water movements in rapidly dispersing newly hatched insect larvae to the favourable habitats in deep water.
Vertical migration of Chaoborus flavicans in a Scottish loch
Authors: GOLDSPINK C. R. , SCOTT D. B. C. 
Published: May 2006

SUMMARYThe pattern of diel vertical migration of Chaoborus flavicans larvae in a shallow Scottish loch varies according to the instar and, in third and fourth instars, according to the season.The planktonic phase of the migration is not exclusively concerned with predation, the larvae feeding at least equally actively in the benthos. Although there is no conclusive evidence as to the role of vertical migration in Chaoborus flavicans, it has some of the characteristics of an epideictic display.Upward and downward locomotion can be induced experimentally in a plankton wheel by manipulating light intensity alone. However, the responses are complex and there is a great deal of individual variation, suggesting that additional factors are involved.
On a new genus of freshwater hoplonemertean from Campbell Island
Authors: MOORE JANET , GIBSON RAY 
Published: May 2006

SummaryA new freshwater hoplonemertean from Campbell Island, to the south of New Zealand, i s described and named Campbellonemertes jolinsi gen. et sp. nov. The morphology of this tiemertean relates it with the family Prosorhochmidae and the occurrence of this form, the second freshwater prosorhochmid genus from the Antipodes, strongly supports an earlier hypothesis on the evolution of freshwater hoplonemerteans.
Bacterial dynamics in two high‐arctic lakes
Authors: MORGAN KEITH C. , KALFF JAPP 
Published: May 2006

SummaryThe heterotrophic planktonic bacteria in two high‐arctic lakes were studied by direct microscope count and the enzymatic uptake of 14C labelled glucose which generally conformed to Michaelis‐Menten kinetics. Bacterial numbers and activity in oligo‐trophic Char Lake ranged from 0.1 to 2.0×10−3 bacteria/l and a maximum uptake velocity (Vmax) of 1.8 × 10−3μg glucose l− h−1. Nearby Meretta Lake received waste water from the Department of Transport Base at Resolute and this eutrophication was reflected in higher bacterial numbers of 2‐80 × 108/1 and Kmax of 0.1 × 10−1‐7.5 × 10−1 fig glucose l−1 h−1 The Kmax per cell in Char Lake was 3 × 10−11μg glucose l−1 h−1 and changed little between the period of solid ice cover in May and ice‐free conditions in August. Bacterial cycles could not be related to phytoplankton cycles in either lake. Comparison of kinetic data from several lakes suggests a relationship between the bacterial uptake rate of glucose and phytoplankton production. Both bacterial numbers and activity in Char Lake may be very close to the minima to be expected in undisturbed freshwater environments.
Etude expérimentale de Tincubation des oeufs de Baetis rhodani Pictet
Authors: BENECH V. , VIGNES J. C. 
Published: May 2006

SummaryThe eggs of Baetis rhodani were collected from natural conditions just after laying and incubated at different constant temperatures (from 7‐5°C to 27‐5°C) with a constant photoperiod. The incubation period was shorter at higher temperatures up to 25°C (8 days); above this eggs no longer hatched. The slowest development (determined by extrapolation) was at about 3°C (theoretically 130 days). The hatching period was always very short (about 3‐5 days). Fewer eggs hatched at higher temperatures.
La Fecondité de Baetis rhodani Pictet
Authors: BENECH V. 
Published: May 2006

RésumeLa fécondité de Baetis rhodani Pictet a étéétudiée sur tout un cycle saisonnier dans le lissurage, ruisseau du Sud‐Ouest de la France.La variation de la fécondité suit celle de la taille; les femelless les plus grandes sont les plus fécondes et pondent les plus gros oeufs. Le maximum est atteint en hiver; le minimum estival résulte à la fois d'une diminution du nombre d'ovarioles et d'ovules produits par ovariole.Des lignes de régression ont étéétablies entre la fécondité et plusieurs mensurations larvaires et adults, elles ont permis de calculer chaque mois le potentiel de reproduction de la population d'après des prélèvements quantitatifs de larves au dernier stade.Une relation nombre d'oeufs pondus‐‐‐numbre de larves au dernier stade qui en sont issues a fourni a base d'une estimation de la production de la génération printanière en utilisant la méthode de la courbe d'Allen. La part prise par les jeunes stades non capturables dans la production de cette cohorte a été calculée è partir de cetteestimation.SummaryThe fecundity of Baetis rhodani throughout a seasonal cycle is measured and the production by the spring generation is calculated from the figures obtained. Females of B. rhodani cannot be identified with certainty and therefore they were not cauht wild but bred from mature nymphs in the laboratory. Various measurements were made(Fig. 1). Eggs range in number from 4500 in February and March to 200 per female in July. This decrease coincides with a diminution in size and a rise in temprature (Fig. 2). In summer there are about 200 fewer ovarioles per female and production per ovariole is about half what it is early in the year. Smaller females produce not only fewer eggs but also smaller eggs (Fig. 3).The relation between certain dimensions and number of eggs is found to remain close (Table 4), and it is therefore possible to predict how many eggs will be laid per square metre from a quantitative sample of full‐grown nymphs that have been measured (Table 6). Continuous sampling and measuring therefore make it possible to calculate the number of eggs at the beginning of a given generation and the number of adults that ultimately emerge. Calculation of production is based on the assumption that mortality follows the Allen curve (Fig. 10). It is shown that the very small nymphs, ignored in many other calculations of production could contribute up 18% to the total production of the spring generation.
An ecological investigation of the Portneuf River, Idaho: a semiarid‐land stream subjected to pollution
Authors: WAYNE MINSHALL G. , ANDREWS DOUGLAS A. 
Published: May 2006

SummaryThe Portneuf River (mean monthly discharge near mouth 1.4‐15.4 m3/s) in southeastern Idaho, U.S.A., flows through an area of reduced precipitation (approx. 33 cm/year) and is dependent on underground aquifers and snowmelt runoff from the surrounding mountains for its water. The stream was examined at ten locations, distributed over its 156‐km course, during the period 1967‐1971. The Portneuf River is shown to have undergone a number of changes from its natural state as evidenced by alterations in water quality and the distribution of benthic invertebrates along the stream course. Of particular interest are changes brought about by the use of the stream for irrigation and by runoff from agricultural lands, factors whose effects are magnified by the semiarid conditions of the region and by poor soil‐conservation practices. However, the stream also is affected by wastes from a sewage‐treatment plant, phosphate‐processing operations, and an assortment of scattered urban sources. Benthic invertebrates were collected during all four seasons by means of artificial substratum samplers and during summer and autumn by a qualitative dip‐net technique. In general, the samplers were more effective in obtaining a representative picture ofthe fauna. However, neither procedure alone gave as much information as the combined results. The artificial substratum collections are not believed to be representative of the usual effects of stream devvatering by irrigation withdrawal in as much as the samplers provide refugia for the benthos during the periods of reduced habitat.
Diurnal changes in dissolved organic and inorganic carbon and nitrogen in a hardwater stream
Authors: MANNY B. A. , WETZEL R. G. 
Published: May 2006

SummaryOrganic and inorganic carbon and nitrogen parameters were sampled simultaneously at 6 h intervals over a diurnal period at seven stations in a small hardwater stream in southern Michigan. Concentrations and budget values (kg/day) varied up to 10‐fold at individual stations and between stations. The most constant parameters were total dissolved organic carbon and nitrogen. The most variable parameter was particulate organic carbon.Significant changes were noted in all parameters as the stream passed through different stream‐side habitats. Budget values facilitated interpretation of these changes over time between stations. High variability in the concentration values was introduced by large allochthonous inputs of dissolved organic matter (DOM) and water alternately adding to or diluting parameters. Distance from upstream terrestrial DOM sources, DOM residence time, the pulsed nature of DOM inputs and biological utilization of DOM have important effects on the quality and quantity of DOM that enters recipient lakes and rivers. The importance of ground‐water flux and DOM content is stressed. The DOM input and turnover within hardwater streams appears t o be in rapid, dynamic equilibrium.
A new method for establishing a permanent laboratory culture of Chironomus riparius Meigen (Diptera: Chironomidae)
Authors: CREDLAND PETER F. 
Published: May 2006

SummaryA new technique for the establishment of a permanent laboratory culture of Chirono‐mus riparius is described. Larvae and pupae were reared in plastic tanks containing tap water, filamentous algae and a commercially prepared fishfood. The tanks were aerated, maintained at a constant temperature of 24°C and subjected to a constant lighting regime of 13 h of light followed by 11 h of darkness. Adults flew freely in a modified handling box, mated, and oviposited on strips of filter paper placed in the plastic tanks containing the aquatic stages. It has proved unnecessary to change the water or medium, which has saved both time and effort. Moreover, larvae established themselves in ail parts ofthe alga, and therefore more could be kept in each tank than when, as in previous methods, they are provided only with a substratum on the floor of the container.
Surface nitrogen and plankton in Skaha Lake, British Columbia (Canada)
Authors: FINDLEY DAVIS L. , FINDLEY DIANE I. , STEIN JANET R. 
Published: May 2006

SummaryThis study (1970–71) of an oligotrophic lake subject to cultural enrichment indicates the presence of complex interrelations between plankton and nitrogen levels in surface waters. Generally inorganic nitrogen was high in the winter (0.4–0.5 ppm) and Iow in summer (less than 0‐1 ppm). However, in late July and August a large increase in nitrogen (1.5 ppm) was recorded. This correlated with the Gloeotrichia echinulata J. E. Smith ex P. Richt. bloom (Cyanophyceae) and the increase in nitrogen fixation, or nitrogenase activity (measured as acetylene reduction). It was calculated that the cyanophyte bloom could have contributed a minimum of 2350 kg nitrogen to the lake in August 1970 which is c. 62% of the nitrate‐nitrogen occurring at any time.
Lakes of south‐western Uganda
Authors: DENNY PATRICK 
Published: May 2006

SummaryThe vegetation of Lake Bunyonyi, a high altitude lake in Kigezi, S.W. Uganda, is described. The lake had two distinct plant communities. In the shallow sheltered bays and inflows extensive floating swamps of Cyperus papyrus L. and Cladium janiaicen. se Cranz. existed. On the steep, exposed shores there was only a narrow band of vegetation, dominated by firmly rooted Phragmites australis (Cav.) Steud., usually with papyrus behind. Floating‐leaved Potamogeton and Nymphaea sometimes occurred outside the emergent species, and submerged species, including Ceratophyllum demersum L. grew down to 8 m. The pattern of vegetation, and the contribution of floating islands to the distribution of plants in the lake is discussed. Susceptibility to fragmentation, and distribution by wind are thought to be major factors governing the pattern.Oxygen proflies measured at the fringe of swamps indicated that the swamps did not cause appreciable deoxygenation of the water.
Observations on the vertical distribution of the benthos in a Malaysian stream
Authors: BISHOP JOHN E. 
Published: May 2006

SummaryAn apparatus is described wbich is capable of sampling tbe bentbic fauna to a depth of 50 cm by providing a natural substrate for colonization. Tbe results obtained from an area of visually uniform sediments demonstrate that stream animals occur in significant numbers deep in tbe bottom sediments and that, at most, only about half tbe bentbos lives in tbe upper 10 cm usually ‘quantitatively’ sampled in stream surveys. The significance of a deep‐living fauna in regulating community density, in recolonizing denuded areas and in optimizing utilization of available food resources is discussed.
Gastropod associations within Malham Tarn, Yorkshire
Authors: CALOW P. 
Published: May 2006

SummaryA survey of gastropod species associations was undertaken in one locus, i.e. Malham Tarn, Yorkshire. This ranged through both the major weed beds and the rocky shores. A semiquantitative analysis, in terms of both presence‐absence and relative abundance indices, suggested a clear distinction between the snail fauna present in the weed beds and that on the rocky shores, and also indicated a separation of faunas within these two major habitat types. The latter was closely correlated with degree of exposure. From this, and other evidence, it was suggested that wind, via wave action, may be a critical determinant of both the qualitative and quantitative aspects of biocoenotic structure in large bodies of fresh water.
The fine structure of the periphyton of Chara sp. and Potamogeton natans from Wytham Pond, Oxford, and its significance to the macrophyte‐periphyton metabolic model of R. G. Wetzel and H. L. Allen
Authors: ALLANSON B. R. 
Published: May 2006

SummaryThe fine structure of the periphyton of Chara sp. from Wytham pond, Oxford, is examined using transmission and stereoscan electron microscopy. As a result of this investigation the structural proximity of each periphyte component as required by Wetzel and Allen's metabolic model of macrophyte‐periphyton interaction is amply confirmed. The application of stereoscan electron microscopy to a study of feeding in periphyton consumers is also examined.
Studies on mountain streams in the English Lake District
Authors: SUTCLIFFE D. W. , CARRICK T. R. 
Published: May 2006

SummarySodium and potassium in streamwater were measured over a period of 2 years, and concentrations of other major ions were occasionally monitored. The supply of sodium, potassium and calcium in rainfall was measured over a period of 1 year. A tentative budget is given for annual income and output of sodium, potassium and calcium in the Duddon catchment. Sodium and potassium concentrations in streamwater were independent of stream discharge; both ions displayed an annual cycle of high concentrations in winter and low concentrations in summer. The input of sodium was dependent on rainfall, wind direction and wind speed; 40% of the annual supply in rain was precipitated in the autumn. Sodium income in rainfall during the remaining 9 months of the year was insufficient to balance the output in streamwater. Annual income of potassium in rainfall was equal to annual output in streamwater. But potassium was retained on the catchment during spring and summer and was slowly released to the streams in autumn and winter. Only about 10% of the annual calcium output was derived from atmospheric sources.
Vertical distribution and abundance of Ceriodaphnia quadrangula (O. F. Muller) (Crustacea, Cladocera)
Authors: SMYLY W. J. P. 
Published: May 2006

SummaryDistribution and abundance of C. quadrangula (O. F. Muller) has been studied in two small lakes in the southern part ofthe English Lake District. Esthwaite Water (maximal depth 15 m) was sampled from 1958 to 1969 and Blelham Tarn (maximal depth 12 m) from 1961 to 1963. Samples in both lakes were taken with a 5‐1 water bottle at a fixed station in deep water.No difference in vertical distribution between day and night samples was observed. The majority of individuals were located below 7 m in Esthwaite Water and above 8 m in Blelham Tarn. The seasonal cycle in the open water was from May to December with maximal abundance in September and October. Males and ephippial females regularly appeared in early October, irrespective of population density, water‐temperature or the time of the overturn.
Calorific, chemical and physical values of potential duck foods
Authors: DRIVER E. A. , SUGDEN L. G. , KOVACH R. J. 
Published: May 2006

SummaryCalorific values of thirty‐three species of aquatic invertebrates, representing various life stages, from small prairie wetlands are given. The values for twenty‐seven species are new to the literature. Percentage crude protein for fifteen species and the amino acid composition for eleven taxa are presented. The majority of the species dealt with are eaten by waterfowl.
On the food of Chironomus costatus (Chironomidae: Diptera) from a shallow freshwater pond in South India
Authors: ALFRED J. R. B. 
Published: May 2006

SummaryA study has been made of the feeding of Chironomus costatus in a temporary fresh‐water pond in South India. It was found that, irrespective of the size of the larvae, the food composition was the same. The larvae were non‐selective feeders in that the organisms enumerated in the water were also found in the gut.
Diurnal stratification, photosynthesis and nitrogenfixation in a shallow, equatorial Lake (Lake George, Uganda)
Authors: GANF G. G. , HORNE A. J. 
Published: May 2006

SummaryFrom a series of experiments and measurements covering one 24‐h period in Lake George the diurnal patterns of photosynthesis, nitrogen‐fixation and stratification are described. The thermal cycle shows three distinct phases of isothermy, intense stratification and mixing. During stratification the surface water temperature reached 36°C, whereas the bottom temperature remained at 25°C. The phytoplankton are evenly distributed at dawn, sink out during the day and tend towards an even redistribution as thermal stratification breaks down. Depth‐time profiles of oxygen concentration and pH values showed that intense photosynthetic and respiratory activity occurred. The shortness of the predominant limnological cycle is thought to be instrumental in restricting species fluctuations.Changes of total CO2 concentration in situ within the euphotic zone indicated that 2.25 g C/m2.12 h were photosynthetically fixed during daytime. From changes of in situ oxygen concentration, gross photosynthesis was estimated to be 12 g O2/m2.12 h and net particulate production over 24 h as zero.Photosynthetic activity was also measured with the i^C and oxygen techniques by enclosing algal samples in light and dark bottles. The patterns of activity recorded by the two methods were similar, although quantitatively the oxygen method gave rather higher values than did the method. Daily gross photosynthesis was estimated as 15.56 g O2/m2.12 h and 4.5 gC/m2.12 h. These figures are compatible with one another and with the production estimates calculated from Tailing's model of integral daily photosynthesis.The balance between respiration and photosynthesis is described as a function of the underwater light climate and the relative rate of respiration. Both the experimental and theoretical approaches suggest that the column 24‐h net particulate production is an extremely small percentage of gross photosynthesis.Nitrogen‐fixation was measured using both the 15N2 and the acetylene reduction techniques. The day‐long incubation of the 15N2 experiment showed that 11 mg N/m2.day were fixed. The series of shorter acetylene reduction experiments gave a value of 58 mg N/m2.day. The acetylene technique showed relatively high nitro‐genase activity at very low light intensities. The 15N2 results indicated little N2‐fixation at low light intensities. The differences between the two techniques are discussed.Gross photosynthesis estimates calculated from seven different methods run simultaneously are compared. The figures show reasonable agreement, but since the gaseous environment in the euphotic zone is particularly suitable for photo respiration the values are not considered reliable estimates of phytoplankton photosynthesis.