bluuebunny/crossref_metadata_2025_split huggingface dataset:
Downstream increase in the abundance and heterotrophic activity of suspended bacteria in an intermittent calcareous headstream
Authors: GOULDER R. 
Published: May 2006

SUMMARY. 1. Concentration of total bacteria, and heterotrophic activity (as turnover rate for glucose assimilation), in the water of an intermittent spring‐fed calcareous headstream, increased with distance from the source to 1600 m.2. This increase was gradual rather than stepwise and might be due to release of bacteria from submerged vegetation and the stream bed, and to input of terrestrial bacteria with groundwater.3. The increment per unit length of stream was greatest in summer when aquatic vegetation was most abundant and discharge was low.4. When the stream was partly dry, isolated peaks of suspended bacteria occurred and there was no regular downstream increase.5. A lesser spring which upwelled into a natural basin consistently contained more suspended bacteria than the principal source, which was an artificial culvert.
Spine development in the rotifer Keratella cochlearis: induction by cyclopoid copepods and Asplanchna
Authors: STEMBERGER R. S. , GILBERT J. J. 
Published: May 2006

SUMMARY. 1. Spine development in a clone of unspined Keratella cochlearis was promoted by a water soluble factor released by the copepods Tropocyclops prasinus and Mesocyclops edax and by the predatory rotifer Asplanchna priodonta. Between 9 and 55% of K. cochlearis populations cultured in predator‐conditioned media responded to the inducing chemical.2. The K. cochlearis form possessing a posterior spine of medium length was much less susceptible to predation by small Tropocylops and Asplanchna than the form lacking the posterior spine. These predators consistently selected the unspined form over the spined form when offered equal densities of each. However, both spined and unspined forms were equally susceptible to predation by large Mesocyclops.3. The phenotypic variation of offspring produced from induced unspined Keratella females encompassed much of the variation reported for the taxon in North America. These morphotypes are similar to the variation of forms reported for the K. cochlearis tecta series known from Europe. We suggest that the North American morphotypes be identified in studies of this species because the presence of the posterior spine can greatly affect predator selectivity.
Particulates and the cycling of lead in Ullswater, Cumbria
Authors: EVERARD MARK , DENNY PATRICK 
Published: May 2006

SUMMARY.

Ullswater has been affected by former lead mining in the catchment area. This paper investigates how lead in the lake is re‐distributed within the littoral zones. Concentrations in the lake water are low. Particulates including phytoplankton, seston and gelatinous ooze overlying lead‐enriched sediments can have values from 1.3 to >6.0 and 26 mg Pb g‐1 dry weight respectively.
During turbulent conditions, contaminated phytoplankton, settled algae and some of the gelatinous ooze are brought into near‐homogenous suspension within the water column. In calm conditions, settlement of particulates occurs and a rate‐zonal distribution results such that, in a vertical column of water, the finer particles in the upper layers have lower concentrations of lead per unit volume of water than the lower layers.
In non‐turbulent conditions the particles which settle on all submerged surfaces form a tenuous layer termed ecton. Aufwuchs becomes coated by ecton but the latter is readily re‐suspended by disturbances. The intimate contact, and the similarity of concentrations of lead in Aufivuchs and ecton from any one sample, suggests that metal flux occurs between the two. It is concluded that the variety of particulates which comprise the ecton distribute lead during turbulence. In calm conditions the ecton settles on all submerged surfaces and provides a mechanism for transfer of lead into the littoral food web.
The production of hemoglobin by small pond Daphnia pulex: intraspecific variation and its relation to habitat
Authors: ENGLE DIANA L. 
Published: May 2006

SUMMARY.

Hemoglobin production was measured for two populations of Daphnia pulex, one from a temporary pond (GR Pond) and one from a permanent pond (Rash Pond). Surface water in Rash Pond remains high in oxygen, while by late summer very little oxygen remains in GR Pond. Hemoglobin synthesis was induced in the laboratory by artificial oxygen deficiency.
Reproductive state influenced the level of hemoglobin in Daphnia. Females with parthenogenesis eggs had higher total body hemoglobin than ephippial females. Clutches laid by pale Daphnia immediately before exposure to low oxygen conditions were aborted. Offspring produced by hemoglobin‐rich females later in the treatment survived.
Hemoglobin production was higher for Rash Pond Daphnia. Visual predators exist in GR Pond, but are absent in Rash Pond. Also, Daphnia are smaller in GR Pond. Visual predation may have selected against high levels of hemoglobin in the temporary pond. Thus oxygen availability in nature is not necessarily a good predictor of hemoglobin production by Daphnia.
Feeding behavior was altered in low oxygen conditions. Browsing was dominant in low oxygen treatments while Daphnia in control treatments filtered algae normally. Browsing may increase access to sedimented iron necessary for hemoglobin synthesis.
Rates of ammonia release from sediments by chironomid larvae
Authors: TÁTRAI ISTVÁN 
Published: May 2006

SUMMARY. 1. Microcosms of Lake Balaton mud and sterilized sand and aerated water were used to evaluate ammonia increments in the overlying water as influenced by chironomid density and temperature. In the two approaches, the effects of sediment disturbance and metabolic excretion of chironomids were measured.2. The activity of larvae increased the ammonia content of the overlying water at temperatures above 10°C. A rise of temperature to 20°C resulted in a 5–20‐fold increase in ammonia release in both systems with chironomids.3. At 10°C combined effects of sediment disturbance and of excretion produced lower release rates than did excretion rates alone (mud‐water v. sand‐water treatments). At higher temperatures (15 and 20°C) release rates of ammonia by sediment disturbance plus excretion were higher than excretion rates alone. Ammonia excretion contributed significantly to the total release at each temperature.4. Metabolic mineralization of nitrogen compounds appears to be an important mechanism contributing to nitrogen regeneration from aerobic lake sediments. High N:P ratio (14:1) of chironomid excretion materials supports this interpretation.
Advective effects of a reservoir flood on zooplankton abundance and dispersion
Authors: DIRNBERGER JOSEPH M. , THRELKELD STEPHEN T. 
Published: May 2006

SUMMARY. 1. The diel vertical distribution and abundance of zooplankton in the Red River arm of Lake Texoma, Oklahoma‐Texas, U.S.A., were examined between 25 January and 26 June 1982.2. During periods of low river inflow, zooplankton vertical patchiness was related to wind stress. Zooplankton did not maintain distinct vertical patches under strong mixing.3. In mid May heavy rainfall in the drainage basin increased discharge from the Red River and reduced water retention time in the reservoir. The Red River water mass entered the lake as a turbid, surface overflow plume. During this period of flooding most zooplankton populations declined and the distributions of remaining individuals deepened. Greatest population losses occurred between 0 and 7m, depths where most zooplankton had been concentrated prior to the flood.4. A model of population dynamics based on depth specific rates of water exchange between the lake and the Red River, estimated from conductivity changes through time, accounted for the general pattern of change in zooplankton abundance and vertical dispersion.
The life history of the minnow Phoxinus phoxinus (L.) in a productive stream
Authors: MILLS CHRIS A. 
Published: May 2006

SUMMARY. 1. In the River Frome, Dorset, this small cyprinid spawned from mid‐April to early August and consequently some 0 group minnows did not develop scales until the following spring.2. Most I group fish formed a summer hyaline band on their otoliths in a edition to the normal winter band.3. Life‐span was short with a winter age‐structure of 67% 0 group, 32% I group and 1% II group fish with mean fork lengths of 29, 55 and 73 mm respectively.4. In June, substantial numbers of I group fish reached reproductive size (50mm) and thereafter progressively replaced II group fish in the spawning shoals. Few II group males survived beyond June, few females beyond August.5. Only half of I group minnows reached matutity. These were usually fish which had reached 30mm by the previous winter. Very few of these large I group fish survived to spawn the following year.6. This differential mortality, together with the loss of condition and disappearance of II group fish during spawning, may indicate the cost of an extended high level of reproductive effort.7. In this productive environment the life history of the minnow more closely resembles that of the small sympatric species Cottus gobio and Noemacheilus harhatulus than it does that of sympatric cyprinids.
Colonization of rivers and canals in Great Britain by Dugesia tigrina(Girard) (Platyhelminthes: Tricladida)
Authors: WRIGHT J. F. 
Published: May 2006

SUMMARY. 1. Prior to 1975 Dugesia tigrina, an Americati immigrant triclad, was known from only a few flowing water sites in Great Britain. Since then it has been found in a large number of lowland rivers and canals in England and Wales, and in 1985 it was reported from the lower reaches of the River Tweed in Scotland.2. This note gives the recorded distribution of D. tigrina up to the end of 1985 (115 10 km squares now occupied) and summarizes the environmental conditions at a subset of twenty‐five sites where D. tigrina occurs.3. Information on the native triclads at sites recently colonized by D. tigrina is used as a basis for speculating on the rivers most vulnerable to the future spread of this species.4. Possible methods of dispersal of D. tigrina and the features which make it a successful colonist are discussed.
Population dynamics and production of Sialis lutaria L. (Megaloptera) in the Danish River Suså
Authors: MOTHIVERSEN TORBEN , THORUP JENS 
Published: May 2006

SUMMARY. 1. Populations of Stalls lutaria L. were sampled quantitatively at about monthly intervals during 3 years at two localities in the macrophyte rich River Suså, Denmark.2. The life cycle was univoltine. The larvae hatched in June‐July, and the initial S. lutaria population densities varied between 10 and 370 ind. m−2. These differences were probably due to extreme variations in stream discharge during the period of recruitment, high velocities preventing the small swimming larvae from reaching the sediment.3. The S. lutaria rate of elimination varied between 0.11 and 1.47% d−1at the two localities. The high rate of elimination was possibly due to fish predation.4. The growth rates varied between 0.54 and 15% d−1. Growth rates differed between localities and years.5. Numbers of potential prey organisms were not higher in sample units with S. lutaria than in sample units without S. lutaria. Numbers of leeches, which were potential competitors, did not differ significantly in sample units with and without S. lutaria.6. Production of S. lutaria varied between 0.16 and 2.49 g ash free dry weight m−2 y−1, and the P/B̄ ratios varied between 3.0 and 7.3 y−1. The P/B̄ ratios increased significantly with increasing rate of elimination.
Seasonal variation in diet of Chironomus plumosus (L.) and C. anthracinus Zett. (Diptera: Chironomidae) in mesotrophic Lake Erken
Authors: JOHNSON RICHARD K. 
Published: May 2006

SUMMARY. 1. Microscopic gut content analysis of Chironomus plumosus (L.) and C. anthracinus Zett. collected from 18m depth in mesotrophic Lake Erken. revealed significant seasonal differences between the two species.2. C. plumosus dietary constituents showed greater seasonal variation than those of C. anthracinus, with diatom contribution to the gut contents reflecting temporal changes in the phytoplankton.3. Overall the percentage of gut content constituted by detritus, algae, animal remains, and inorganic matter averaged 96%, 4%, 0.4% and 0.03% for C. plurnosus and 97%, 3%, 0.6% and 0.03% for C. anthracinus.4. Coefficients ot dietary overlap for non‐detrital foods decreased markedly from August to September. During this period the proportion of centric diatoms in the guts of C. plumosus increased by 94% while no marked changes were noted in C. anthracinus.5. C. ptttmosus ingested more diatoms than C. anthracinus, especially during diatom blooms in spring and autumn. These results are consistent with the known differences in feeding behaviour between these two speeies.
The ordination and classification of macroinvertebrate assemblages in the catchment of the River Wye in relation to environmental factors
Authors: ORMEROD S. J. , EDWARDS R. W. 
Published: May 2006

SUMMARY. 1. Macroinvertebrates were sampled from three habitats at forty‐five sites in the catchment of the Welsh River Wye. Species assemblages were ordinated by DECORANA. classified by TWIN‐SPAN and related to physico‐chemical factors using correlation and multiple discriminant analysis respectively.2. DECORANA axis 1 was correlated with pH or total hardness, whilst axis 2 correlated with slope or distance from source. TWINSPAN groupings were also related to hardness and, to a lesser extent, slope. Assemblages at soft‐water sites (<15gm−3 CaCO3) were composed mostly of Plecoptera but at hard‐water sites, even at high slope (>10 m km−1), the fauna was dominated numerically by Ephemerop‐tera, net‐spinning Trichoptera, Mollusca and Crustacea.3. We suggest that our data do not support the River Continuum Concept unless there are modifications to allow for multiple gradients.
Seasonal variation in the filament morphology of the freshwater diatom Melosiragranulata(Ehrenb.) Ralfs
Authors: DAVEY MARTIN C. 
Published: May 2006

SUMMARY 1, The seasonal changes in filament dimensions and the occurrence of separation valves in a population of Melosira granulata(Ehrenb.) Ralfs were investigated in a eutrophic lake in southern England. Experiments were carried out in culture to study the effects of various environmental factors on the diatom's morphology.2. Major blooms of M. granulataoccurred from September to October, coinciding with an increase in mean filament length brought about by the high growth rate of the diatom. This increase was controlled by a reduction in the frequency of separation valve production. A similar increase in filament length occurred in rapidly growing cultures.3. The population was lost from the epilimnion when thermal stratification occurred. Immediately prior to this the population consisted of short filaments.4. The mean filament length was greatest during occasional summer blooms and was again controlled by a reduction in the frequency of separation valve production. This appeared to be a response to the reduced nutrient concentration in the lake. This is supported by similar morphological changes in low nutrient cultures.5. Increases in the filament length of the diatom were accompanied by increases in the diatom's sinking velocity. The length increase thus ensured its rapid return to the sediment, after summer growth periods, where the cells could be replenished with nutrients.
Book Reviews
Authors: VINER A. B. 
Published: May 2006

Book Review in this Article: Paine, A.I.(1986) The Ecology of Tropical Lakes and Rivers. John, D.M. (1986) The Inland Waters of Tropical West Africa Smart, M.M., Lubinski, K.S. & Schnick, R.A. (Eds) (1986) Ecological Perspectives of the Upper Mississippi River Skreslet, S. (Ed.) (1986) The Role of Freshwater Outflow in Coastal Marine Ecosystems Kristiansen, J. & Andersen, R.A. (1986) Chry‐ sophytes: Aspects atid Problerrts. Munawar, M. & Tailing, J.F. (Eds) (1986) Seasonality of Freshwater Phytoplankton: a Global Perspective—Developments in Hydrobiology Neboiss, A. (1986) Atlas of Trichoptera of the SW Pacific‐Australian Region Reuss, J.O. & Johnson, D.W. (1986) Acid Deposition and the Acidification of Soils and Waters Davies, B.R. & Walker, K.F. (Eds) (1986) The Ecology of River Systems Rowland, A.P. (Ed.) (1987) Chemical Analysis in Environmental Research Shaw, S.A. & Muir, J.F. (1987) Salmon: Economics and Marketing
Late Holocene flooding in the Ecuadorian rain forest
Authors: FROST IAN , MILLER MIKE C. 
Published: May 2006

SUMMARY 1. The stratigraphy, radiocarbon chronology, sedimentary pigment, and cation records of sediment cores from four lakes in the Ecuadorian rain forest show that regional flooding occurred from about 1300 to 800 ‘BP. Each core contains a stratum of alluvial clay, silt and sand overlain by lacustrine deposits of peat, gyttja or clayey gyttja. Radiocarbon dates show that the onset and termination of the alluvial event was synchronous across the sites. Short‐term, possibly regional, flooding occurred at each of the sites at least once since the major flood.2. A core from Anangucocha, a black‐water lake, records the geoche‐ mical signature of white‐water incursion during this flooding interval. Sedimentary pigments show that aquatic production at Anañgucocha was low during the lotic interval but rose sharply and remained high within the modern lake period.3. The Amazon's dynamic river system may have been an important force in promoting and maintaining high floral and faunal diversity.
The effects of water depth and density on the growth of a unionid clam*
Authors: HANSON JOHN MARK , MACKAY WILLIAM C. , PREPAS E. E. 
Published: May 2006

SUMMARY. 1. Unionid clams from Narrow Lake, Alberta, were collected to quantify the natural variation in growth, to assess the natural variation in abundance, age and size distribution, and growth with water depth in the lake, and to conduct in situ experiments to directly test the effects of water depth (temperature) and clam abundance on clam growth.2. The unionid clam, Anodonta grandis simpsoniana, showed wide variation in length at a given age. There were no significant differences in growth between clams collected at 1,3, 5, and 7m depths in the lake despite marked differences in water temperature. The wide variation in clam biomass within each depth zone may have masked possible effects of water depth.3. The effect of water depth and variation in clam density on clam growth was tested directly by stocking clams into small enclosures at densities equivalent to 50, 150, 250, 350 and 450g m‐2 (live weight) at each of 1, 3, 5 and 7 m depths in Narrow Lake (each depth and abundance treatment in triplicate). A uniform sandy substrate was used in all enclosures to eliminate any possible effect of substrate type on growth.4. Mortality was negligible (0.9%) during the experiment. Clam density had no significant effect on clam growth which suggests that clam growth was not food limited in the lake.5. Clams reared at 7 m grew more slowly than clams reared at 1, 3 and 5 m. Clams reared at 5 m grew more slowly than clams reared at 1 and 3m. Growth of clams reared at 1 and 3m did not differ. These differences in growth were strongly correlated with the measured differences in water temperature between depths.6. Migration between depths probably accounts for the lack of a depth effect on clams growing in the natural habitat.
A note on Lake Goang, an unusual acid lake in Flores, Indonesia
Authors: GREEN J. , KRAMADIBRATA HASIANA 
Published: May 2006

SUMMARY. 1. Lake Goang has a pH of 2.5. Associated with this low pH are high concentrations of sulphate, chloride, iron and aluminium. There are no fish in the lake.2. A single species of Heterococcales was found in the phytoplankton.3. The zooplankton consists of one species of rotifer and a stalked species of Vorticella.4. The shallow water fauna consists of two species of nematodes, at least two larval Diptera, one trichopteran, a zygopteran, a small crab (Sundatelphusa) and a cyclopoid copepod (Paracyclops).5. During January an oily slick appears and is deposited as asphalt around the shore of the lake.
Interspecific and intraspecific variations in egg hatching for British populations of the stoneflies Siphonoperla torrentium and Chloroperia tripunctata (Plecoptera: Chloroperiidae)
Authors: ELLIOTT J. M. 
Published: May 2006

SUMMARY 1. The objective was to compare variations in egg hatching between the two species (interspecific variations) and between populations of the same species (intraspecific variations). There were significant interspecific, but not intraspecific, differences in female size, adult life‐span, egg production, hatching success, incubation periods and hatching periods.2. The optimum temperature for hatching success within the range 3.8–22.1°C in the laboratory and the range over which at least 50% of the eggs hatched were lower for Chloroperia tripunctata (Scopoli) (8.5°C, 4.2–17.3°C) than for Siphonoperla torrentium (Pictet) (12.8°C, 6.1–19.4°C). Few eggs hatched at 22.r°C.3. The relationship between incubation period (d days) and water temperature (T°C) was given by: d=1219/T1.368 for S. torrentium, d=253/T0.459 for C. tripunctata. Both equations successfully predicted incubation periods for eggs placed in a stream. The period over which eggs hatched was much longer for C. tripunctata than for S. torrentium at all temperatures.4. The shorter incubation period (at r>5.6°C) and shorter hatching period for S. torrentium ensure that larvae of this species are already growing when eggs of C. tripunctata start to hatch, but the prolonged hatching period of the latter species ensures a long period of larval recruitment to the population. These differences in egg hatching may reduce competition between the two closely‐related species.
Influence of environmental conditions on the ovarian cycle and serum chemistry of Cyprinus carpio in the Dal lake, Kashmir (India)
Authors: FIDA SHAHNAZ , QADRI M. YASEEN , SIDDIQI MAQSOOD 
Published: May 2006

SUMMARY 1. The study presents adaptive and acclimatory changes observed in Cyprinus carpio communis L with respect to ovarian cycle and serum levels of electrolytes, calcium, total proteins and albumin as a consequence of wide temperature and sunshine variation in the natural environment of Dal lake in Srinagar, Kashmir (India).2. The atmospheric temperatures in Srinagar show well‐defined seasonal and diurnal variations. During the period of study, the mean monthly average temperature in summer (June‐August) was 24°C whereas in winter (December‐February) it fell to 3.6°C. The total hours of sunshine during the winter months were about half of those found in summer.3. Under local thermal and photo conditions the fish was found to spawn once a year compared to biannual spawning in tropical chmates.4. A significant decrease was found in serum sodium, potassium and chloride concentrations during the months of January and February when the mean minimum atmospheric temperatures reached −2.5°C and −l.2°C respectively.5. The serum calcium levels showed a marked increase during the period corresponding to ovarian maturity and spawning of fish.6. A significant rise in total serum protein concentration was induced by decreased environmental temperatures. Serum albumin levels were found to exhibit a sharp fall coinciding with the spawning period.