bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of some caddis larvae (Trichoptera) to different types of substrate in an experimental stream *
Authors: HIGLER L. W. G. 
Published: May 2006

SummaryIn laboratory experiments with full‐grown larvae of three Trichoptera species (Limnephilus rhombicus, Potamophylax rotundipennis and Sericostoma pedemontanum) in an artificial stream, four types of bottom material were provided in combination with various currents. Only L. rhombicus reacted to low current speed (9 cm/sec), moving downstream when a bottom current was present. L. rhombicus and P. rotundipennis showed a distinct preference for pebbles over sand and for coarse pebbles over crushed brick. S. pedemontanum burrowed under pebbles or stones. L. rhombicus showed a distinct tendency to climb onto the dividing gauze or vertical sticks. All three species preferred shaded parts of the experimental stream to the illuminated parts.The results are related to field observations. Limnephilus rhombicus occurs in stagnant and slow‐running waters. Potamophylax rotundipennis is restricted to rather fast‐running streams with a perpetual flow, while Sericostoma pedemontanum occurs in the same type of stream.
Egg production, development and growth in Moina micrura Kurz (1874) (Cladocera: Moinidae)
Authors: MURUGAN N. 
Published: May 2006

SummaryLaboratory observations on the egg production, development and growth in the Cladoceran Moina micrura show that this species has a life span of 13 days during which it produces 6M 8 eggs. Two preadult and eleven adult instars were recorded at a temperature range of 28°–30°C. The rate of egg production calculated on a cumulative basis was found to be lower (a = 1.0368) than that of other tropical species. The embryonic stages in Moina micrura closely resembled other cladoceran species, although with a short development period of 24 h. The total life span, growth rate and the total number of eggs produced in Moina micrura have been compared with those of allied tropical, temperate and arctic daphnids. The significance of this relationship to secondary productivity in tropical ecosystems has been discussed.
Changes in the ecology of the Norfolk Broads
Authors: MASON C. F. , BRYANT R.J. 
Published: May 2006

SummaryThe Norfolk Broads have recently shown a marked loss of both floral and faunal diversity. To detect any recent changes and to provide a baseline for future research, twenty‐eight broads were visited in 1972–73. Samples of aquatic flora and benthic fauna were taken and a number of physical parameters were measured.In the private broads a good inverse correlation between chlorophyll‐a concentration and Secchi disc readings was found, suggesting that phytoplankton was largely responsible for the turbidity of the water. The relationship did not hold for the public broads where erosion and the stirring of sediments by motor launches is intense.Eleven broads were completely devoid of macrophytes. A macrophyte flora was well developed only in Upton and in the five Thurne broads and in these latter there was evidence of a recent loss in diversity. The sudden loss of formerly abundant species of macrophyte has been recorded frequently from the broads. The benthic fauna was poorly developed in most broads and was dominated by Limnodrilus hoffmeisteri and/or Potamothrix hammoniensis. Valvata piscinalis was the only regularly occurring gastropod in the benthos. Most of those broads with a diverse benthic fauna also had an abundant growth of macrophytes.Possible reasons for the recent changes in the ecology of the broads are discussed.
Cyclomorphosis in natural populations of Oscillatoria redekei Van Goor
Authors: GIBSON C. E. 
Published: May 2006

SummaryEvidence is presented of a regular seasonal variation in the filament length of Oscillatoria redekei Van Goor in Lough Neagh. This cycle is not in phase with the seasonal changes of the biomass of the species, but seems to occur in step with the nutrient concentrations. Some possible mechanisms of filament replication are discussed and evidence is presented that mechanical forces are not effective in breaking filaments. The ecological significance of cyclomorphosis in this species is difficult to establish.
Effects of temperature on food ingestion rate and absorption, retention, and equilibrium burden of phosphorus in an aquatic snail, Goniobasis clavaeformis Lea *
Authors: ELWOOD J. W. , GOLDSTEIN R. A. 
Published: May 2006

SummaryThe effects of sublethal temperatures on feeding rates and phosphorus dynamics of a freshwater snail, Goniobasis clavaeformis Lea, were determined and feeding rates were measured at four temperatures. The food source was aufwuchs labelled with radioactive phosphorus. A model was developed to elucidate the results of this type of study. Food ingestion rate increased with increasing temperature up to 14°C and then decreased at temperatures above 14°C. The elimination rate of absorbed phosphorus increased with increasing temperature throughout the entire range of experimental temperatures, 10‐19.3°C. Mean retention times of absorbed phosphorus i n Goniobasis were estimated to be 34, 24, 10, and 6 days at 10, 13.8, 15, and 193°C, respectively. Mean retention time of unabsorbed 32P in the gut of this species as a function of temperature followed the same temperature relationship as that of ingestion rate.The absorption efficiency of phosphorus was estimated to be constant at about 39% for ail experimental temperatures, although the data suggest that the absorption ePRciency may have been related inversely to the rate of gut clearance or directly to the residence time of food in the gut. The equilibrium body load of phosphorus at each experimental temperature was estimated based on concentrations of stable phosphorus in the food source and the kinetics of 32P in Goniobasis. The equilibrium body burden of phosphorus in Goniobasis increased with increasing temperatures up to a maximum at 11–12°C and then decreased at temperatures above 12°C.
The effect of oxidized material on the vertical distribution of freshwater benthic fauna
Authors: KIRCHNER W. B. 
Published: May 2006

SummaryThe vertical distribution of representatives of the benthic groups: Ostracoda, Nematoda, Oligochaeta, Harpacticoida, Cyclopoida, and Chironomidae was determined. All groups had their highest numbers and biomass in the first 2 cm.The downward extent of oxidized material affected the distribution by dispersing the biomass more as seen by the deeper occurrence of groups when the oxidized material increased. Both the nematodes and oligochaetes were found to inhabit the first reduced layer when the oxidized material was less than normal.
Ecological studies on algal‐lysing bacteria in fresh waters
Authors: DAFT M. J. , McCORD SUSAN B. , STEWART W.D.P. 
Published: May 2006

SummaryAlgal‐iysing bacteria are present in five lochs, two reservoirs, one sewage works and five alkaline soils whieh were examined. Nine out of thirty‐six isolates have been studied in detail and all are gram‐negative non‐fruiting myxobaeteria. All are aero‐philic, require a neutral or alkaline pH (optimum 7.0–9.0) for good growth, have temperature optima of 28–37°C, require contact with the host for lysis to oecur, and are so similar in morphology and host range that they all appear to be strains of a single genus. They lyse all bloom‐forming Cyanophyeeae on whieh they have been tested, including species of Anabaena, Aphanizomenon, Gloeotrichia, Microcystis and Oscillatoria. Their abundance is usually correlated direetly with the abundance of Cyanophyeeae in eutrophic waters and it is probable that in most ecosystems the algae and the bacteria co‐exist, although if the equilibrium changes markedly as a result of change in environmental conditions situations may arise where the bacteria may play an important role in the lysis of algal blooms. The available evidence suggests, however, that this is likely to be a rare occurrence in natural ecosystems.
Decomposition of aquatic biota and sediment formation: organic compounds in detritus resulting from microbial attack on the alga Ceratium hirundinella
Authors: CRANWELL P. A. 
Published: May 2006

SummaryTo obtain further evidence of the contribution of autochthonous organic matter to lake sediments, the benzene‐methanol extract of the particulate matter remaining after microbial attack upon an alga, Ceratium hirundinella, during laboratory simulation of natural decomposition processes, has been separated into its components. Comparison of each component with corresponding material isolated from the fresh alga facilitates the recognition of unchanged substances and microbial products in the decomposed sample. Certain common features in the occurrence and distribution of n‐alkanes, alkenes, n‐ and branched/cyclic alkanoic acids, alkenoic and hydroxy acids in degraded algal organic matter and in sediments of productive lakes are believed to indicate a contribution of autochthonous material to the sediment.
Planktonic diatoms and some diatom‐silica relations in a shallow eutrophic Scottish loch
Authors: BAILEY‐WATTS A. E. 
Published: May 2006

SummaryThe species composition of planktonic diatom crops in Loch Leven, Kinross, Scotland varied considerably over the years studied (1968–71) with centric forms predominating. Dense populations were often produced and rates of increase and decrease were high.Relations with dissolved silica did not appear always to be simple; instances occurred during which both diatoms and silica were increasing or decreasing. Moreover, certain rates of increase in dissolved and frustule silica exceeded the rates at which silica flows into the loch even when the inflows appeared to be the only available dissolved silica source.
The substrate bin—a new sampling device for studying diel vertical migratory movements on to and off lake sediments
Authors: HART R. C. 
Published: May 2006

SummaryThe substrate bin, used to study diel migratory movements of the copepod Pseudodiaptomus hessei on to and off bottom interfacial areas is described. It consists essentially of a transparent Perspex box open at its upper end and supported upright within a metal framework. A lid, hinged along one face of the open end of the bin, opens and closes automatically through a simple system of levers as the apparatus is lowered on to or raised off a solid substrate.The apparatus is lowered on to the lake bed where it opens. Diel movements on to or off the shallow layer of bottom substrate enclosed within the bin can be examined by retrieving bins serially at different times.Using this apparatus in conjunction with standard net sampling techniques, clear evidence for an alternation of benthic and pelagic phases during diel cycles was obtained. Notwithstanding an apparent oversampling of the benthic component, the magnitude of which cannot be defined precisely, it is concluded that the apparatus provides a simple and reliable method of sampling.
A portable quantum meter‐spectroradiometer for use in aquatic studies
Authors: UPHOFF GARY D. , HERGENRADER GARY L. 
Published: May 2006

SummaryThis paper describes the design, construction and use of a portable battery‐powered, submersible spectroradiometer. The distribution of energy underwater is determined by measuring successively through six sensors fitted with interference filters which partition the underwater spectrum. This system also contains a quantum sensor which detects the photosynthetically active radiation under water. The instruments’ small size and battery operation make it especially useful for studying small lakes or reservoirs from small boats. Measurements taken from Pawnee and Wagontrain, two of the Salt Valley Reservoirs in eastern Nebraska, are given as examples of the use of the instrument.
Factors influencing phytoplankton growth and succession in Farmoor Reservoir
Authors: YOUNGMAN R. E. , JOHNSON D. , FARLEY M. R. 
Published: May 2006

SummaryWeekly observations were made at the Thames Water Authority's Farmoor reservoir during the development of the spring bloom of phytoplankters from November 1973 to March 1974. Counts were made of the phytoplankters, their fungal parasites and the zooplankters. Analyses were made of those chemical parameters which it was thought might exert an influence on phytoplankton growth. Physical and meteorological measurements were also made.The development and decline of four phytoplankton populations were observed. The growth of Asterionella formosa Hass. was interrupted in December when 43·5% of the cells were parastiized by Zygorhizidium affluens Canter. Stephanodiscus astraea (Ehr.) Grün. and Stephanodiscus hantzschii Grün. were not similarly affected. All three diatoms were apparently limited finally by silica depletion. The desmid, Closterium peracerosum Gay. became 66% parasitized by an undescribed chytrid and declined rapidly.Light, turbulence, zooplankton grazing and nutrients other than silica appeared to be unimportant.
Studies on the Ephemeroptera of a Northumbrian river system
Authors: WISE E. J. 
Published: May 2006

SummaryThe River Coquet is a clean, fast flowing, moderately calcareous river. It is young to mature in development and supports a typical torrential fauna. Marked trends in successional replacement along the river course are confined to the scarce species of Ephemeroptera and the absence of longitudinal zonation in the distribution of some common species is related to the topographical characteristics of the system. A distinct successional trend by one species is attributed to its intolerance to the lower temperatures at high altitudes. Major discontinuities in distribution are found between the Ephemeroptera of the main river and certain tributaries. The paucity of certain otherwise abundant species in one region is related to silt deposition resulting from sand and gravel excavation.
The food ofPlanaria torva(Müller) (Turbellaria‐Tricladida), a laboratory and field study
Authors: REYNOLDSON T. B. , SEFTON A. D. 
Published: May 2006

SummaryThe food of Planaria torva was examined in the laboratory by exposing a range of potential prey to the triclad and observing prey mortality. Under these conditions P. torva fed mainly upon tubificid oligochaetes and gastropods. The former activity was regarded as untypical of the field situation and due to limitations of the laboratory habitat.The food of P. torva was determined in the field by taking monthly samples from October 1967 to May 1969 of a population living in Linlithgow Loch, West Lothian, Scotland. A serological technique was used to examine the gut contents of the field triclads. For reasons explained in the text, the prey organisms tested for serologically were gastropods, oligochaetes (Tubificidae), Asellus and chironomid larvae. Planaria torva fed most extensively on Gastropoda, Asellus was the second main food while Tubificidae and Chironomidae were taken only seasonally and in small numbers. The limited extent of feeding on tubificids supports the laboratory data. Small P. torva gave proportionately fewer positive reactions to the prey antisera than large individuals. This was explained by the fact that small individuals occurred most frequently in the warmer months and took smaller meals; both of these features shorten the detection period of food in the gut and therefore give fewer reactions. The diet of small and large P. torva was similar in the field and showed considerable overlap with that of Dugesia polychroa.The food of Polycelis tenuis, Dendrocoelum lacteum and Dugesia polychroa in Linlithgow Loch was described on an annual basis and the results confirmed earlier observations.
Body length, size of resting eggs and identification of the ephippia of Ceriodaphnia megalops and Ceriodaphnia pulchella
Authors: BOTTRELL HOWARD H. , NEWSOME T. 
Published: May 2006

SummaryThe ephippia of Ceriodaphnia megalops and Ceriodaphnia pulchella are described. Their ephippia may be identified by their size and shape, supplemented by measurement of the length of the resting egg. The ephippia are shed free in the water and float by means of a special area of gas‐filled tissue. Each ephippium contained one ellipsoid resting egg. The length, width and shape of the resting eggs of both species were investigated, and comparisons made with published data of their parthenogenetic eggs. For both species the volume of a resting egg was virtually the same as the volume of a parthenogenetic egg, but the resting egg was more elongated. The shape of resting eggs was linearly related to egg volume on logarithmic axes in a manner similar to that reported for the parthenogenetic eggs of these two species. The linear relationship between total parthenogenetic egg volume and body length reported for these two species did not apply to their resting eggs.
Wind distribution of the egg masses of Chironomus anthracinus (Zetterstedt) (Diptera: Chironomidae) in a shallow, wind‐exposed lake (Loch Leven, Kinross)
Authors: DAVIES B. R. 
Published: May 2006

SummaryA mass emergence of Chironomus anthracinus (Zetterstedt) took place at Loch Leven, Kinross, in late May and early June 1971, leading to a large concentration of egg masses. The distribution of egg masses within the lake was determined on 6 June 1971 and the accumulation of egg masses along wind‐exposed shores, under the influence of a 17–23 km h−1 wind, was noted. Oviposition site selection by the weak flying adults appears to have little importance upon the final distribution of larvae within the lake. Temporary planktonic activity of first instar larvae under the influence of wind‐induced water currents is briefly discussed as a dispersal mechanism in the light of observed egg mass accumulation in the lake.
The numbers, biomass and transport downstream of micro‐crustaceans and Hydra from Cow Green Reservoir (Upper Teesdale)
Authors: ARMITAGE PATRICK D. , CAPPER MARTIN H. 
Published: May 2006

SummaryFluctuations in numbers and biomass of Copepoda, Cladocera and Hydra drifting out of the Cow Green reservoir via the outflow were investigated during the period August 1972‐November 1973. Cladocera, chiefly Daphnia hyalina var. lacustris Sars and Copepoda, were most abundant between July and September, occurring at mean densities of 1278 and 215 m−3 respectively. Hydra was most abundant between August and October at a mean density of 19 m−3. Winter densities of all groups were low and 98% of the total annual output occurred between July and October. An estimated 150 kg (136 kg of Cladocera, 13kg of Copepoda and 1 kg of Hydra) dry weight was released from the reservoir during the year November 1972‐October 1973. During periods of peak abundance about 1–2% of the total fauna drifting out of the reservoir was found 6·5 km below the dam. The effect of reservoir discharge and flow in tributaries of the Tees on this transport downstream is discussed. It is suggested that the micro‐crustaceans and Hydra, even if not fed upon directly, will have considerable influence on the Tees benthos when they settle out and decompose to produce a nutrient‐rich detritus.
Experimental studies on nymphal growth in Leptophlebia vespertina (L.) (Ephemeroptera)
Authors: BRITTAIN JOHN E. 
Published: May 2006

SummaryThe mayfly, Leptophlebia vespertina (L.) was reared at field temperatures in the laboratory. The egg incubation period was 21–26 days. There were seventeen to nineteen nymphal instars. Growth was generally rapid during the first 3½ months and slow thereafter. This change occurred at the same time in both the laboratory and the field population. Temperature is considered to be the major factor regulating this and other changes in growth rate.
Starvation and the size structure of zooplankton communities*
Authors: THRELKELD STEPHEN T. 
Published: May 2006

SummaryThe survival time of zooplankton under conditions of total starvation is expressed as a function of weight‐specific respiration rate and the fraction of initial (pre‐starvation) body weight which may be lost prior to death. Data from the literature on these two components of survival time are used to formulate a general expression of survivorship of zooplankton at 20°C as a function of body weight: t=2·95 w0·25, where t is in days and w is μg dry weight. Survival time data from the literature on 25 marine and freshwater species are compared to this prediction as are new data on Daphnia pulex Leydig, D. magna Straus and Simocephalus serrulatus (Koch). The effects of age‐specific (non‐starvation) mortality are considered; in particular, older individuals of each of these species survive for shorter periods of time than predicted and an interaction between age‐specific and starvation‐induced mortality is proposed. The effects of total and partial starvation on the size structure of zooplankton communities are discussed.
Temporal and spatial distribution of the dinoflagellate Ceratium hirundinella O.F. Müller within a small productive lake
Authors: HEANEY S. I. 
Published: May 2006

SummaryThe growth of Ceratium hirundinella in Esthwaite Water, a small productive lake, was investigated during 1975; the horizontal distribution of the alga was studied on four occasions over a 3‐week period. Measurements of lake temperature, oxygen concentration, and vertical stratification of Ceratium at close intervals of depth, were also made. Lake population estimates from large samples at many stations were compared with small samples at the regular sampling station. On two occasions the means of these samples were significantly different (P<0·01). On one date, the estimate of Ceratium abundance in the lake from the large sample at many stations was more than twice the value obtained from the sample collected at the regular sampling station. The population of Ceratium was contagiously distributed in all the large samples. On 3 days the horizontal distribution showed an increase in Ceratium numbers towards the windward shore of the lake. Very large accumulations of Ceratium were found in the metalimnion, just above the anaerobic hypolimnion, during late afternoon. Possible mechanisms of horizontal pattern development are considered, based on the measurements of the vertical distribution of Ceratium, and meteorological factors. The ecological consequences for Ceratium of vertical and horizontal movements, and its spatial distribution in the lake, are discussed.
Application of underwater light measurements in nutrient and production studies in shallow rivers
Authors: WONG S. L. , CLARK B. , PAINTER D. S. 
Published: May 2006

SummaryDue to fluctuations in water turbidity, river depth and total reflection from one river section to another, plant production is poorly correlated to solar radiation incident on the water surface. A relationship was observed between daily relative photosynthesis and photosynthetically available radiation (PAR) at the plant depth for Cladophora, with a correlation coefficient (r) of 0·73. Therefore, the effect of low light levels can be compensated for when evaluating nutrient‐growth relationships for Cladophora in the field.