bluuebunny/crossref_metadata_2025_split huggingface dataset:
The abundance and distribution of caddisflies (Insecta: Trichoptera) caught by emergence traps in the ‘Ritrodat’ research area of the Lunzer Seebach (Lower Austria) from 1980 to 1982
Authors: WARINGER J. A. 
Published: May 2006

SUMMARY. 1. Adult Trichoptera were caught during 3 years (1980–82) in the ‘Ritrodat’ research area of the Upper Lunzer Seebach. a mountain brook near Lunz. Lower Austria, using a set of thirty pyramid type emergence traps. During the three collecting periods (112 collecting days) a total of 1810 specimens were caught. The most abundant species were Micrasema minimum McL. (Brachycentridae). Rhyacophila vulgaris Pictet (Rhyacophilidae), and the three Iimnephilid species Potamophylax cingulatus Steph., Allogamus auricollis Pictet and Ecclisopteryx guttulata Pictet.2. In six species (Micrasema minimum, Rhyacophila vulgaris, Atlogamus auricollis, Ecclisopteryx guttulata, Drusus biguttatus Pictet, Chaetopteryx fusca Brauer) the sex ratio was significantly different from 1:1. In Micrasema minimum 422 females were caught but only three males.3. In each year there were peaks in total emergence in early summer and early autumn.4. The length of the emergence period of the most abundant species ranged from 38 days in Micrasema minimum to 210 days in Rhyacophila vulgaris (mean values 1980–82); there was also a difference in the intensity of emergence in these species: the percentage of time required for 50% of the animals to emerge (0%=onset of emergence, 100%= emergence completed) was 16% in Allogamus auricollis but 71% in Rhyacophila vulgaris (mean percentages 1980–82).5. The distribution pattern of individuals per trap was tested against a Poisson distribution; in all three years the distribution was contagious.6. The dry weight of specimens of Drusus biguttatus, Micrasema minimum. Ecclisopteryx guttulata and Wormaldia copiosa McL. was measured and. together with published dry weight values of other species (Malicky, 1976), these data were used to estimate the biomass emerging annually of twenty‐three species of Trichoptera (99.2% of emergence, 1980–82). This was equivalent to 35.3 kJ m−2 in 1981 and 32.5 kJ m−2 in 1982.
An indirect procedure for the estimation of assimilation efficiency of aquatic insects
Authors: PANDIAN T. J. , MARIAN M. PETER 
Published: May 2006

SUMMARY. 1. From forty‐five values reported for twenty species of aquatic insect species, it was found that the nitrogen content (N) of the food was significantly and positively correlated (r=0.97. P<0.001) with assimilation efficiency (Ase).2. Therefore, the Ase of aquatic insects can be predieted, if the nitrogen content of the food is known, using the equation: Ase (%)=9.29+8.82N.
Stream hydraulics as a major determinant of benthic invertebrate zonation patterns
Authors: STATZNER BERNHARD , HIGLER BERT 
Published: May 2006

SUMMARY. 1. Studies on the zonation of benthic fauna in fourteen streams situated in a variety of latitudes from Alaska to New Zealand have been evaluated.2. We suggest that physical characteristics of flow (‘stream hydraulics’) are the most important environmental factor governing the zonation of stream benthos on a world‐wide scale.3. From the source to the mouth of a stream, zones of transition in stream hydraulics' occur, to which the general pattern of stream invertebrate assemblages can be related. In these zones benthic community stability and resilience must be different from those upstream and downstream of the hydraulic transition zones.
Diel activity of a boreal water beetle (Dytiscus alaskanus: Coleoptera; Dytiscidae) in the laboratory and field
Authors: AIKEN R. B. 
Published: May 2006

SUMMARY. 1. The diel activity of Dytiscus alaskanus (Coleoptera: Dytiscidae) was studied by trapping in the field and by direct observation of behaviour (mounting, chasing, grappling, swimming and surfacing) in the laboratory.2. In the field in the number of beetles trapped during the dark hours was approximately fifty‐fold greater than trapped during daylight hours.3. In the laboratory, there was a marked increase in mounting, chasing and grappling when the ambient light level fell below 0.41mm−2. Swimming showed only a slight diel pattern and surfacing none at all.
Colloidal and dissolved organic carbon dynamics in undisturbed boreal forest catchments: a seasonal study of apparent molecular weight spectra
Authors: LOCK MAURICE A. , FORD TIME. 
Published: May 2006

SUMMARY. 1. Colloidal and dissolved organic carbon (CDOC) was monitored in six pristine boreal rivers in Northern Quebec, Canada, using ultrafiltration to obtain apparent molecular weight spectra.2. The concentration and proportional contribution of small (<1K) molecular weight material (potentially microbially labile) and high (0.7μm to 300 K) molecular weight material was not significantly different between streams of order 2–9.3. The dominant component of CDOC (0.7μm to 300 K fraction) was probably derived in streams other than first order, from surface or sub‐surface run‐off, whereas a peak concentration in the <1 K fraction during August was probably due to autochthonous exudates.4. The two first order streams included in this survey had very low CDOC concentrations. However, further work on twelve other first order streams showed that they had high concentrations and we consider that this is the more typical situation. The finding offered a potential explanation for the otherwise anomalous longitudinal CDOC distribution pattern throughout the study area.
The role of fungi in the diet of the amphipodGammarus pulex(L.): an enzymatic study
Authors: CHAMIER ANNE‐CAROLE , WILLOUGHBY L. G. 
Published: May 2006

SUMMARY.1. Sets of tenGammarus pulexfed on controlled diets of sterile alder leaves, or fungal mycelium, or alder leaves incubated for 10 days with an aquatic hyphomycete, were assayed for cellulase, β‐1,3‐glucanase an d chiitinase activity and compared with (a) animals taken directly from the stream, (b) animals starved for 2 days, and (c) enzyme activity in fungal mycelium.2. Gut enzyme activity was compared on natural substrates of sterile leaves, mycelium and inoculated leaves as well as on model substrates.3.G. pulexsecretes an endogenous coupled cellulase system capable of degrading native cellulose in plant cell walls. It also secretes β‐1,3‐glucanase and chitinase capable of degrading fungal cell walls thus affording access for gut enzymes to cell contents.4. Secretion of enzymes active on native cellulose is enhanced on a diet of leaves already partially degraded by fungal enzymes. Gut enzymes extract more reducing sugar from this substrate than from sterile leaves. Specific enzyme secretion is enhanced by the presence in the diet of exposed, accessible substrates. Fungal enzymes do not appear to contribute to the digestive processes ofG. pulex.
Antarctic stream ecosystems: physiological ecology of a blue‐green algal epilithon
Authors: VINCENT WARWICK F. , HOWARD‐WILLIAMS CLIVE 
Published: May 2006

SUMMARY. 1. Several dozen summer meltwater streams are located in the McMurdo Sound region (c. 78°S 165°E) of southern Victoria Land. They are characterized by a highly variable flow regime at diel, seasonal and annual times caleis; wide fluctuations in temperature and nutrient content; and a very simple epilithic community of cyanophytes (Nostoc spp., Oscillatoriaceae), bacteria, fungi and microherbivores.2. The epilithon survives the dark Antarctic winter as dry, frozen mats which provide a large inoculum for growth the following summer. This overwintering assemblage retains a high metabolic capacity and responds rapidly to rehydration.3. In a series of artificial substrate experiments, biomass accumulation rates were generally less than 0.1 In units d−1. Colonization and growth on the substrates was inversely related to the suspended sediment load of the stream. There was also a visual correspondence between per cent algal cover of the natural streambed and the clarity of the streamwater. Sloughing losses may limit community biomass, particularly in the turbid flowing waters.4. During running water conditions the mature communities had very low gross photosynthetic rates per unit chlorophyll (<0,1 μg C (μg chl a.h)−1 and per unit carbon (<0,2 μg C (mg biomass C.h)−1). Respiration was generally a high percentage (up to 92%) of gross photosynthesis, which probably reflected the high population densities of microheterotrophs in the community.5. The floristically simple epilithic mats slowly accumulate to extreme biomass levels (>20 μg chl a cm −2, <20 mg C cm−2). Production rates per unit biomass are low, probably in response to the cold temperatures of the Antarctic stream environment, and the accumulated biomass represents several seasons of growth.
Population ecology of the commensal chironomid Epoicocladius flavens on its mayfly host Ephemera danica
Authors: TOKESHI MUTSUNORI 
Published: May 2006

SUMMARY. 1. Epoicocladius flavens (Diptera: Chironomidae) has a 1‐year life cycle in the River Tud in eastern England. Pupation and adult emergence occurred from the end of May until the beginning of September. Larval growth was rapid during the summer but thereafter almost ceased until the following April.1 Unlike other chironomids, the population density of E. flavens was very stable and remained at around 1000m −2 all through the year.2. Ephemera danica (Ephemeroptera: Ephemeridae), the host of E. flavens, has a 2‐year life cycle. The proportion infested was about 90% for the older host year‐class and less than 30% for the younger year‐class from autumn until the following summer. A rapid increase in infestation occurred during the summer as a result of hatching of the E. flavens eggs. Of those infested, the older year‐class hosts harboured two or three larvae, on average, whereas the younger ones had only one.3. When host year‐classes were treated separately, the frequency distribution of the number of E. flavens per host each month did not depart significantly from a Poisson distribution. Younger instars departed from a Poisson distribution more frequently than older instars.4. The majority of E. flavens larvae attached to the gills of their hosts. As the instars progressed, increasing proportions were found on the thorax, legs and tails. The thorax was the preferred site for fourth instar larvae.5. Enhanced chance of survival, rather than the supply of detrital food particles which collect on the host's body, is considered as an important benefit to accrue to E. flavens from this commensalism.
A field technique for the determination of zooplankton grazing on natural bacterioplankton
Authors: BJøRNSEN PETER KOEFOED , LARSEN JENS BRENNER , GEERTZ‐HANSEN OLE , OLESEN MICHAEL 
Published: May 2006

SUMMARY. 1. A method for the determination of zooplankton community grazing rates on natural populations of bacteria is described.2. Undisturbed zooplankton samples were incubated with 3H‐thymidine‐labelled bac teriioplankton, and animals and their food subsequently separated by size.3. Prehandling of zooplankton by concentration before incubation reduce the grazing rates by a factor ranging from three to four.4. Time series experiments showed that appropriate incubation periods ranged from 40 min at 14°C to 60 min at 10°C.5. Spatial variability in the zooplankton was the main source of the overall standard error. This was considerably reduced by using composite samples.
Fluxes of free amino acids in three Danish lakes
Authors: JøRGENSEN NIELSO. G. 
Published: May 2006

SUMMARY. 1. Heterotrophic assimilation rates and concentrations of dissolved free amino acids (DFAA) were followed during diel studies in the eutrophic Lake Mossø, Lake Esrom and Lake øm in spring and summer in 1982. In all three lakes, three to four fold diel variations in concentrations and assimilation rates were measured. These fluctuations appeared to be iindependent of phytoplankton and bacteria production. Pools of DFAA varied from 380 nM (Lake Mossø) to 2430 nM (Lake ørn), with serine, glycine, alanine and ornithine as dominant free amino acids.2. When similar water samples were incubated in a natural light‐dark cycle or in total darkness, different pools of DFAA were measured in light and dark.3. Decomposition of organic matter or zooplankton activity (rather than e.g. phytoplankton exudates) appear to be responsible for the concentration changes.4. Observed discrepancies between simultaneous concentration changes and assimilation rates are discussed in relation to the applied tracer procedure and the concentration measurements.5. Assimilation of DFAA sustained from 6% to 25% of the bacterial carbon requirement, corresponding to 2–12% of the phytoplankton production in the lakes.
Life history and body size evolution in Holopedium gibberum Zaddach (Crustacea, Cladocera)
Authors: TESSIER ALAN J. 
Published: May 2006

SUMMARY. 1. Body size, development, sheath size and relative egg size were examined in two populations of Holopedium gibberum Zaddach. The populations were chosen because of differences in juvenile versus adult mortality.2. The population subject to food limitation and predation from icthyoplankton (high juvenile mortality) exhibited large size at birth and maturity, large sheath size, and eggs which were relatively large compared to the adult. In contrast, individuals in the population exposed to predation by golden shiner (high adult mortality) were smaller at birth and maturity, had a smaller sheath, and produced relatively small eggs.3. I contrast body size and relative egg sizes of these H. gibberum populations with literature values for all Cladocera, and propose a general hypothesis for the evolution of relative egg size in Cladocera.
The spectral distribution and attenuation of underwater irradiance in Tasmanian inland waters
Authors: BOWLING L. C. , STEANE M. S. , TYLER P. A. 
Published: May 2006

SUMMARY.1. Measurements were made of the attenuation and spectral distribution of downwelling and upwelling photosynthetically‐available radiation (PAR) in all the principal types of natural waters found in Tasmania.2. Most lakes in the State are clear and non‐turbid, with water itself and the low concentrations of gilvin being the principal determinants of the green underwater light climate. Many others are deeply coloured by dissolved and colloidal organic material (gilvin, gelbstoff) which rapidly attenuates short wavelengths, specifying a shallow, predominantly red euphotic zone.3. A spectrophotometric measure of colour, the absorption coefficient at 440 nm, is statistically related to measurements on the platinum scale with good precision.4. Few Tasmanian lakes are turbid but in those that are the underwater light climate is almost identical to that of non‐turbid, humic lakes.5. Reflectance,R, varied with depth but not in the asymptotic way previously encountered. A linear relationship existed between the scattering coefficient,b, and nephelometric turbidity, but not at the approximate 1:1 ratio reported elsewhere.6. Most Tasmanian lakes are oligotrophic or dystrophic and phytoplankton rarely influenced the underwater light field.7. Seasonal variation in optical character is not great in natural lakes and their optical properties and light fields can be used typologically.8. Simple and multiple regression analysis showed that Secchi depth was a poor predictor of euphotic depth but the optical properties and the underwater light field of inaccessible lakes could be reasonably predicted from laboratory measurements made on small water samples, using regressions developed for a wide range of lake types and by reference to the quantaradiometric scans of lakes with comparable optical properties.9. An optical classification of Tasmanian lakes made by cluster analysis agreed reasonably well with one based on edaphic, vegetational and chemical criteria.
The consumption of eggs of the perch, Perca fluviatilis L., by macroinvertebrates in the field
Authors: DIAMOND MARK , WAKEFIELD PHILIP M. 
Published: May 2006

SUMMARY. 1. Perch egg masses, in a late stage of development, were collected from a small stillwater and the composition of the egg masses and the number of invertebrates which colonized them was recorded.2. All of the invertebrates that colonized the egg masses were tested serologically for the presence of perch eggs and the ability of some invertebrates to eat live and dead perch eggs in the laboratory was determined.3. Of the nineteen taxa that colonized the egg masses, only two species of flatworm and three species of caddisfly larva ate perch eggs in the field and, of these, only one genus of caddisfly larva ate live eggs in the laboratory.4. It is concluded that the invertebrates present were not important predators of perch eggs.
Ovipositional behaviour ofSimulium argyreatumandS. variegatumand its relationship to infection by the fungusErynia conica(Entomophthoraceae)
Authors: HYWEL‐JONES N. L. , LADLE M. 
Published: May 2006

SUMMARY.1. At two sites in DevonS. argyreatumandS. variegatumonly oviposited on water‐splashed boulders. The oviposition season was from 15 March to 9 November at Steps Bridge and from 28 March to 7 December at Fingle Bridge. Flies laid eggs only during a brief period after sunset.2. Flies infected with the fungusE. conicareturned to the oviposition sites at the same times as healthy flies, but infected flies appeared to be unable to lay eggs.3. At least 10.9% of healthy flies were found to have infective conidia ofE. conicaon their wings after laying eggs.
The role of fish in the regulation of nutrient cycling in Lake Balaton, Hungary
Authors: TÁTRAI ISTVÁN , ISTVÁNOVICS VERA 
Published: May 2006

SUMMARY. 1. In 1984 an enclosure experiment was carried out in order to elucidate the importance of nutrient supply from fish to phytoplankton during the critical summer period in eutrophic Lake Balaton. One enclosure was stocked with fish and the other left empty.2. Two peaks were recorded in primary production reaching maximum values in the fish enclosure.3. In the enclosure with fish, inorganic nitrogen concentrations increased gradually till the end of the experiment, with ammonia making up the largest component. Lower dissolved phosphorus concentrations in the fish enclosure, with its higher primary production rate, may indicate an intense cycling of this nutrient.4. The biological and chemical changes occurring in the enclosure suggest that bream removal can be an effective tool in water quality control for Lake Balaton.
Respiration studies and population metabolism of the gastropod Theodoxus jordani (Sowerby)
Authors: AL‐DABBAGH KHALID Y. , LUKA JAMAL Y. 
Published: May 2006

SUMMARY. 1. The oxygen consumption of the gastropod snail T. jordani was determined at six different temperatures corresponding to those experienced in the field.2. The respiration rate increasing linearly with increasing tissue weight at all temperatures studied. Regression equations describing the respiration rate‐live weight relationship were significantly different (P<0. 001).3. The respiration rate‐temperature relationship was linear for seven weight classes of the population. The extent of change in the respiration rate with increasing temperature differed between the different weight classes. The Q10 value was highest (2.5) for the smallest weight class and decreased with increasing size.4. The annual respiratory loss by the whole population was estimated to be 334.75 kJ m−2.
The incidence of predation on lake‐dwelling leeches
Authors: YOUNG J. O. , SPELLING S. M. 
Published: May 2006

SUMMARY. 1. Erpobdella octoculata (L.), Glossiphonia complanata (L.) and Helobdella stagnate (L.) were eaten readily by larval and adult dytiscid beetles, larval caddisflies and Sialis, nymphal odonatans and various fish in laboratory experiments.2. A serological technique showed that very few lake‐collected specimens of these predatory taxa, plus triclads, leeches and stone fly nymphs, had been feeding on leeches.3. A literature survey of lake studies on fish diet indicated that usually less than 6% of individuals with gut contents had eaten leeches. Few detailed records of waterfowl feeding on leeches have been documented.4. It is concluded that predation pressure on lake‐dwelling leeches is light, and is more severe from fish than invertebrates, less on populations inhabiting stony shores than in vegetation, and greater on the erpobdellid than the two glossiphoniid species.
Gemmules of Anheteromeyenia ryderi and Heteromeyenia tubisperma (Porifera: Spongillidae) from southern New England undergo diapause
Authors: BAZER LAURENCE J. , FELL PAUL E. 
Published: May 2006

SUMMARY. 1. The annual cycle of the freshwater sponge, Anheteromeyenia ryderi, was studied in a seepage pond in Connecticut. The adult form of the sponge persisted throughout the year, although some specimens at the edge of the pond degenerated by late summer. During the middle of the winter, adult sponges had a simplified tissue morphology with reduced numbers of flagellated chambers.2. Gemmules of A. ryderi were also present during all seasons. Gemmule germination occurred during the spring, and some specimens produced new gemmules by late spring.3. The gemmules of A. ryderi underwent a protracted diapause which was broken under both natural and laboratory conditions by several months exposure to low temperatures (≤5°C).4. The gemmules of Heteromeyenia tubisperma were also shown to undergo diapause, but in this case diapause was broken by a relatively short cold treatment (1 month).
The role of periphyton abundance and quality in the microdistribution of a stream grazer, Helicopsyche borealis (Trichoptera: Helicopsychidae)
Authors: VAUGHN CARYN C. 
Published: May 2006

SUMMARY. 1. A series of laboratory and field experiments was performed to determine if the preference of larvae of Helicopsyche borealis (Trichoptera: Helicopsychidae) for exposed rock surfaces in streams was related to patchiness of periphyton food.2. At low current velocities in the laboratory larvae preferred food‐saturated as opposed to food‐depleted portions of substrata and drifted off the substratum in response to low food levels.3. When offered a choice of three potential foods—a diatom, a green filamentous or a blue‐green filamentous alga—larvae showed no preference.4. Larval densities on artificial subtrata in field experiments were highest in areas of high algal chlorophyll a.5. In laboratory experiments more adults emerged from cultures containing green algae or diatoms than cultures with blue‐green algae or bacteria alone.6. Periphyton quality was not as important as abundance in controlling H. borealis microdistribution. By selecting exposed surfaces of rocks, H. borealis larvae place themselves in the microhabitat most likely to contain both abundant and high quality food patches.
Zooplankton associations in some Ethiopian crater lakes
Authors: GREEN J. 
Published: May 2006

SUMMARY. 1. The zoopiankton associations in five crater lakes in Ethiopia were examined in April 1984. The two least alkaline lakes had the most diverse zoopiankton.2. The large diaptomid copepod Lovenula africana was present in the lakes with alkalinities between 10 and 63 meq l−1, but was absent from Lake Chitu (239 meq l−1).3. The contribution of the zoopiankton to the nocturnal deoxygenation of Lake Aranguadi is negligible.