bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the macro‐invertebrate fauna of Cow Green reservoir (Upper Teesdale) in the first five years of its existence
Authors: ARMITAGE PATRICK D. 
Published: May 2006

SUMMARY. The development of marginal (shore‐line), sub‐littoral (3–6 m) and profundal (15–18 m) fauna was followed using timed collections in shallow water and artificial substrata in deeper regions.The reservoir started filling in July 1970 and was close to top water level in the autumn of that year. Samples in the marginal zone contained drowned terrestrial organisms and some Cladocera (Chydoridae) in February 1971 but by October, Chironomidae and Oligochaeta became abundant and micro‐crustaceans (copepods and cladocerans) formed about 98% of the total catch. Peak densities of micro‐crustaceans in the marginal zone were reached in the summer of 1971, but chironomids and oligochaetes were most abundant in the second year after filling. The numbers of marginal zone animals were greatest at the most sheltered site, and lowest at a site on the windward shore. At a stream mouth the rheophilic fauna present in April 1971 was replaced with limnophilic organisms (Chironomidae and Tubificidae) by September 1971.In the sub‐littoral, Hydra, Enchytraeidae, Orthocladiinae Tanytarsini and oribatoid mites were the most abundant taxa, whereas Naididae, Hirudinea, Ostracoda, Gammarus pulex, Chironomini and Pisidium spp. were numerous in the profundal zone.Total faunal numbers and biomass were greatest in the profundal zone in all years. The highest annual mean estimate of biomass in the sub‐littoral was 3.07 g (wet wt)m−2 in the second year after filling, thereafter both numbers and biomass fell. In the profundal the maximum biomass (about 29 gm−2) was observed in the third and fourth years after filling. An estimate of total standing crop of benthic organisms below the drawdown limit, made in July 1974, gave a figure of about 43 tonnes, wet weight.Biomass estimates at Cow Green were compared with those in eighteen other reservoirs and were found to be high especially in relation to those from other upland areas.
An analysis of seasonal dynamics of a mixed population of Daphnia, and the associated cladoceran community
Authors: ALLAN J. DAVID 
Published: May 2006

SUMMARY. The dynamics of a mixed population of Daphnia(D. ambigua and D. parvula) are analysed over 9 months in a small eutrophic lake. A spring peak of D. ambigua occurred shortly after ice break‐up. Decline of D. ambigua coincided with a high occurrence of sexual reproduction, the appearance of D. parvula which did not become abundant, and a substantial increase in Ceriodaphnia quadrangula. A third cladoceran, Bosmina longirostris, was abundant before and after the period of numerical dominance by D. ambigua, but declined to very low numbers coincident with the increase in D. ambigua.Estimates of egg hatching rate at various temperatures demonstrate that these three cladocerans have different rate responses to temperature, and that seasonal succession of species is predictable from temperature alone. The importance of temperature versus species interactions in controlling species succession is discussed.
The phased division of the freshwater dinoflagellate Ceratium hirundinella and its use as a method of assessing growth in natural populations
Authors: HELLER M. D. 
Published: May 2006

SUMMARY. The nocturnal phasing and partial synchrony of cell division in Ceratium hirundinella was investigated on four occasions for dense planktonic populations in a small productive lake (Esthwaite Water). The population growth rates deduced from the proportion of cells dividing per day are compared with the rates of increase of cell density in the lake. The maximum proportion of Ceratium cells found dividing at any time was 5.8 ± 1.0%, and the time of optimum division was 03.00 hours G.M.T. The daily rate of division during the main phase of population increases was similar to that deduced from the overall population increments at that time, although during the week of collection the increase had apparently ceased temporarily. On the other three occasions, either increase of cell numbers had ceased or the population was declining, but a continued low rate of division (c. 3% day−1) was found.The nocturnal division of Ceratium in Esthwaite Water is compared with the division phasing of dinaflagellates described from elsewhere. Some general problems associated with the derivation of estimates of population growth rate from division frequency are also considered.
The effect of current velocity and sediment on the drift of the mayfly Ephemerella subvaria Mcdunnough
Authors: CIBOROWSKI JAN J. H. , POINTING P. J. , CORKUM LYNDA D. 
Published: May 2006

SUMMARY. Experiments conducted in an artificial stream showed that significantly more nymphs drifted from an inorganic substrate at a mean current velocity of 28.5 cm s−1 than at 18.5 cm s−1. Drift density, however, was not affected. Disproportionately large numbers of nymphs drifted while current velocities were being increased from 18.5 to 28.5 cm s−1.Both drift numbers and drift density were greater in turbid water, after the addition of large amounts of inorganic sediment, than under clear‐flowing conditions during dark periods but not in the light. The interaction of increasing current velocity and sediment levels resulted in a significantly greater number of drifting nymphs under lighted conditions.Minor spates which do not seriously disturb the stream bed may initiate significant increases in macroinvertebrate drift.
A technique for predicting in‐stream flow requirements of benthic macroinvertebrates
Authors: GORE JAMES A. 
Published: May 2006

SUMMARY.
A total of 225 benthic samples was taken at various riffles along the Tongue River in Montana during three separate weekly intervals in 1975. For each sample, depth, current velocity, substrate microprofile, turbulence (Froude number), and the number and kind of species present were considered.The conditions of highest faunal diversity were 75–125 cm/s current velocity at 20–40cm depth. The optimum condition appeared to be 76 cm/s at a depth of 28 cm over medium cobble substrates.The centroids for optimum conditions of depth and current velocity for thirty‐six common macroinvertebrates are also presented.Representative diagrams of the tolerance ranges of some common invertebrate species are presented. Rhithrogena hageni Eaton was chosen as the indicator species since its tolerances closely matched those of the highest community diversity. The presence of Rhithrogena in future samples would indicate maintenance of adequate flow conditions for the present benthic community.A method for applying these data to produce a minimum flow recommendation is discussed. If the optimum conditions can be plotted on composite hydrologic maps of depth and velocity in riffle areas at various discharges, one can predict the discharge at which the optimum conditions are eliminated and, thus, the recommended minimum discharge.
Water quality and the occurrence of Chironomus riparius Meigen (Diptera: Chironomidae) in a stream receiving sewage effluent
Authors: GOWER A. M. , BUCKLAND P. J. 
Published: May 2006

SUMMARY.
The effects of a sewage effluent in Moat Brook, Staffordshire, were determined from regular collections of water and biological samples from directly comparable stations above and below the sewage outfall.The eutrophic conditions below the outfall result in the replacement of Polypedilum laetum by Chironomus riparius (except in the spring) as the dominant member of the Chironominae. Continuous recruitment of first instar larvae to the population of C. riparius in summer and autumn results in much overlap of generations, but emergence trap captures suggest at least five generations in the year.The usefulness of C. riparius as an indicator of enriched conditions in lotic ecosystems should be considered in relation to oviposition behaviour and the occurrence and seasonal variation in density of the adults and aquatic stages (including the more conspicuous third and fourth instar larvae).
Observations on the biology of the perch, Perca fluviatilis, in the River Stour, Dorset
Authors: MANN R. H. K. 
Published: May 2006

SUMMARY.
Opercular bones from 323 perch from the River Stour were used for age and back‐calculated growth determinations. Annuli were formed during May at the beginning of the growth period. Growth was minimal from October to April. Female perch grew faster than males, and the growth rates of both sexes were higher than those observed in most other European waters. Spawning occurred during late April and early May; male gonads began development in August and had attained their maximum weight in September, but the ovaries developed gradually from August until April. Immature perch had an annual cycle of condition with a maximum in June‐July and a minimum in December‐January. The condition of mature males and females was affected by the gonad cycle. The fecundity of Stour perch is expressed by the formula: log egg number = 2.40 log length (mm) ‐ 1.34.Approximately 25% of males were mature at age I and all were mature at age II, whereas most females did not spawn until age III. Ephemeroptera nymphs and minnow fry constituted the bulk of the diet of 0‐group perch; Ephemeroptera nymphs, minnow fry and Corixidae were the most numerous items in I group perch, whereas older perch contained Corixidae and a wider range of fish prey species, although minnows were the most numerous of these.
Benthic macroinvertebrates of a fluctuating reservoir
Authors: KASTER J. L. , JACOBI G. Z. 
Published: May 2006

SUMMARY.
Benthic macroinvertebrate distribution, abundance, and composition were observed in a fluctuating (7.7 m) central Wisconsin, U.S.A., reservoir during 1973–74. Chironomidae and Oligochaeta represented 98% of the total fauna by number. The chironomid, Chironomus plumosus, and an oligochaete, Limnodrilus, each averaged 36% of the total benthic biomass. Annual mean numbers and biomass in areas exposed to air, exposed to ice cover, or remaining inundated were 3025/m2 (1.8g/m2), 4311/m2 (4.5g/m2), and 8558/m2 (16.0 g/m2), respectively. A substantial portion of the benthic fauna was stranded and subsequently decreased rapidly in drying and frozen substrates exposed to air. Total benthic numbers and biomass were greatest immediately below the drawdown limit.Recolonization required 3 months (mid‐March to mid‐June, 1974) to attain pre‐drawdown values for numbers and biomass, and subsequently both were greater after reinundation than before the substrate was exposed. Recolonization of areas exposed to the air was greater in substrates containing large amounts of organic matter than in sandy areas containing little organic matter. Sorting and transportation of sediments redistributed organic materials from the regulated zone to below the drawdown limit, and macrophytes were eliminated from the regulated zone. When compared to other reservoirs and lakes, the density of benthos in the Big Eau Pleine Reservoir is neither high nor low. However, when compared with non‐fluctuating reservoirs the number of Ephemeroptera, Plecoptera, Trichoptera, Amphipoda, and Gastropoda was low.
Limnological studies of Lake Wisdom, a large New Guinea caldera lake with a simple fauna
Authors: BALL E. , GLUCKSMAN J. 
Published: May 2006

SUMMARY.
Lake Wisdom is of interest because it is large and deep, has oxygen throughout, and yet, apparently as a result of its recent formation, its biota has some surprising lacunae. It is nearly circular and fills the central caldera of Long Island, Papua New Guinea (5° 20′ S, 147° 6′ E). Its maximum length is 13.4 km, and area approximately 95 km2. A bathymetric map of the lake to depths of 300 m has been constructed from fathometer transects. Repeated soundings in the deeper parts gave depths of about 360 m. The surface of the lake is approximately 190 m above sea‐level and water samples from the deepest part of the lake are fresh, so the basin is apparently sealed. The lake level shows annual fluctuations of c. 1.0 m.Limnological information has been collected during seven visits to Lake Wisdom over the period 1969–76. The surface temperature of the lake was constant at 28°C throughout this period and the temperature falls very gradually to 26–27°C at 60 m, except for a relatively rapid drop of approximately 1°C from 10 to 20 m. One of the most unusual features is the relatively high oxygen concentration in the deepest parts of the lake. Living chironomid larvae and molluscs were collected from the bottom in depths of 360 m. Light penetration in the lake varies greatly depending on the amount of rainfall and the volcanic activity of Motmot, a secondary cone within the lake.The biota of Lake Wisdom is rather simple. There is a low standing crop of phytoplankton. Benthic algae are abundant and diverse although they cover only a limited area because of the depth of the lake. There are no vascular aquatic plants. The pelagic fauna consists of two species of Cladocera and one species of notonectid. There is one species of sponge, four species of molluscs, and a small number of species of aquatic insects including Hemiptera. Odonata, and the larvae of chironomids, mayflies, a caddisfly, and a pyralid moth. Water birds, including ducks, grebes and waders, are fairly numerous. The lake also contains one or more crocodiles.
Feeding and growth of Asellus aquaticus (Isopoda) on food items from the littoral of Windermere, including green leaves of Elodea canadensis
Authors: MARCUS J. H. , SUTCLIFFE D. W. , WILLOUGHBY L. G. 
Published: May 2006

SUMMARY.
In the laboratory, Asellus aquaticus devoured intact green leaves from growing shoots of the aquatic macrophyte Elodea canadensis. In four collections of A. aquaticus on Elodea in a lake (Windermere), c. 20% of the specimens contained in their guts fragments of green Elodea leaves; this material and pieces of oak (Quercus) were identified from characteristic leaf hairs. Some specimens had also eaten the filamentous alga Oedogonium. Fluorescence microscopy is a useful aid for screening invertebrates that may have eaten living plant tissues.Immature A. aquaticus, with an initial mean body length of c. 3 mm, wet weight c. 1 mg, were grown through sexual maturity over a 49‐day period at 15°C in a series of twenty‐two experiments (six to twelve isolated specimens in each experiment) comparing growth rates on different foods, including instances where no food was given. Animals were fed on a variety of items collected from the littoral of Windermere, plus some laboratory cultures of algae and bacteria. The highest mean specific growth rate (5.8% day−1) was obtained on young Elodea leaves mechanically shaken to remove epiphytes. Other diets yielding fast growth rates (3.7–5.3% day−1) were young growing leaves of Elodea with few epiphytes and older green and brown living leaves covered with a thick growth of epiphytic algae, epiphytic algae removed from Elodea, plastic imitation Elodea immersed in the lake until covered with attached algae, epilithic algae on stones, Oedogonium, and decaying oak leaves. Slower growth (1.3–2.2% day−1) and poorer survival was obtained on the following: a pure culture of the bacterium Sphaerotilus natans; cultured bacteria from lakewater; the filamentous algae Cladophora and Stigeoclonium both with and without epiphytes; faecal matter from Asellus; freshly killed Asellus; lake sediment. Some growth (mean = 0.7% day−1) and 50% survival for 21 days occurred in ‘starved’ animals kept in filtered, sterilized lakewater. Better survival and slightly faster growth (1.0–1.5% day−1) occurred in ‘starved’ animals kept in filtered and unfiltered lakewater.Growth of A. aquaticus was also experimentally determined from birth in animals fed on young green Elodea leaves and on decaying oak leaves. On both diets, growth was curvilinear and approximately exponential from birth to sexual maturity reached at c. 2mg wet weight in 46–60 days at 15°C. In older specimens the relative growth rate gradually fell over a period of 50 days, representing a more linear phase of growth during sexual maturity.
A simple water and plankton sampler
Authors: BLAKAR INGGARD ARNE 
Published: May 2006

SUMMARY.
A lightweight, free‐flushing water and plankton sampler constructed of readily available, inexpensive material is described. Easily interchangeable tubes of varying volumes allow sampling flexibility. The sampler is activated by a messenger and is shut by two plastic funnels. For analyses in highly stratified waters, the sampler can be adjusted into the horizontal position. Several samplers may be tripped in series. The sampler has proved a versatile and reliable instrument in ecological studies.The tripping mechanism may also be used to release reversing thermometers and closing nets.
Growth and population studies on Tilapia galilaea in Lake Kinneret
Authors: LANDAU RUTH 
Published: May 2006

SUMMARY.
Between 1967 and 1977, catches of Tilapia galilaea in Lake Kinneret fell from an annual average of about 200 tonnes to a low of 70 tonnes in 1974, and then returned to their former level. Total yearly mortality (Z) was estimated at 1.84 between 1970 and 1976. Assuming a natural mortality (M) of 0.94, total stock size averaged 300–700 tonnes in that period, while recruitment averaged < 0.7–3 million per year. Three broods hatched in years of relatively high water levels (1970, 1971 and 1972) yielded especially low recruitment.The Von Bertalanffy growth coefficient (K) was estimated at 0.67, and final length (L∞) at 25–36cm total length. First year's growth, 23–152mm, was closely related to final length, which appeared to be affected by genetic variation in the population. Yearly fluctuations in size distribution were attributed to changes in the proportions of fast‐ and slow‐growers, as well as in the abundance of year‐classes. Recruitment to the fishery, at 17–20cm, occurred between ages l+and3+.The highest growth rates for age‐1 T, galilaea, 1–2% mean weight per day, occurred in April and May, the Peridinium season. However, only a small proportion of age‐1 fish reached marketable size by July, when their food supply began to diminish. During the autumn months, there was hardly any length increment, and all T. galilaea became lean, especially the age‐0 group. It is surmised that recruitment of stocked fish could be increased by introduction in December and by use of fingerlings which are potentially able to grow to marketable size in less than two seasons.
Diel emergence patterns of lotic Chironomidae
Authors: WARTINBEE DAVID C. 
Published: May 2006

SUMMARY.
Six channels were constructed in various parts of two riffles from which chironomid exuviae were collected every 3 h for three 24‐h periods in July 1974. Diel emergence patterns were calculated for twelve abundant species and six different patterns were observed. Krenosmittia cf. camptopheleps and Cordites had their major emergence pulse during peak light periods and it is proposed that high or increasing light intensity is a cue for their emergence. Stempellinella cf. brevis begins its emergence in the morning and continues until after darkness. Increasing and high water temperatures are suggested as the emergence cue since emergence tracks water temperatures with little apparent effect of light. Parametriocnemus sp. and Polypedilum (Tripodura) sp. begin emerging in late evening and continue into early daylight hours. These patterns indicate low and decreasing water temperatures as the emergence cue with little apparent effect of light. Corynoneura sp. and Thienemanniella sp. emerged primarily during daylight hours with a minor pulse in the morning and the major pulse in late afternoon. It is proposed that the emergence cue is simply the presence of light and that water temperature determines how many individuals are able to prepare for emergence and respond to the cue. Rheotanytarsus cf. exiguus and Tanytarsus (Sublettea) coffmani have major emergence peaks just after sunset and minor pulses in the morning hours. Changes in light are proposed as their emergence cue with water temperatures determining the number of individuals able to respond to that cue. Eukiefferiella discoforipes gr. sp. and Nilotanypus sp. emerge continuously throughout daylight and darkness hours, showing no obvious pattern.
A comparison of the gut contents of two co‐existing lake‐dwelling Naididae (Oligochaeta), Nais pseudobtusa and Chaetogaster diastrophus
Authors: McELHONE M. J. 
Published: May 2006

SUMMARY.
The gut contents of Nais pseudobtusa and Chaetogaster diastrophus, two co‐existing littoral‐dwelling Naididae (Oligochaeta), differed over a period of one and a half years due to strong selection by C. diastrophus for specific diatom genera, Cymbella spp. and Navicula spp. In contrast, N. pseudobtusa showed less selection and the gut contents consisted mainly of detritus, diatoms and mineral particles. These differences in the food niche are likely to contribute to the co‐existence of the two species in this habitat.Seasonal changes in the relative abundance of diatom genera in the habitat greatly influenced the gut contents of N. pseudobtusa; however, these changes had less influence on those of C. diastrophus. This and the highly selective nature of the gut contents of C. diastrophus suggests that the two species have different feeding strategies. It is suggested that C. diastrophus actively seeks out certain diatom genera in preference to other food items, while the unseslective gut contents of N. pseudobtusa are more typical of an opportunist feeder.
Nutrient budgets and the regulation of nutrient concentrations in a small sub‐arctic lake in northern Sweden
Authors: JANSSON MATS 
Published: May 2006

SUMMARY.
A 5‐year study was made of the hydrology and water chemistry in the watershed of Lake Stugsjön, a small lake in the sub‐arctic region of northern Sweden. Of the total yearly runoff, 80% occurs during the spring thaw in May and June and largely regulates the nutrient loading. The ice‐free period of the lake is June—October. Atmospheric deposition of nitrogen and phosphorus was among the lowest recorded anywhere, in spite of which it accounts for approximately half of the total summer nutrient loading. Dry fall‐out made up the major part of the total atmospheric deposition of nitrogen and phosphorus during the summer.Conductivity measurements showed that the major constituents were not influenced by processes within the lake.The nitrogen concentration in the lake during the summer was probably regulated by benthic algae which assimilated inorganic nitrogen from the sediments and released organic nitrogen to the lake water.Phosphorus loading and water temperature in combination showed a clear relationship with the mean concentration of chlorophyll‐α during the ice‐free period.