bluuebunny/crossref_metadata_2025_split huggingface dataset:
Qualitative and Quantitative Interactions between Microphytobenthos and Herbivorous Meiofauna on a Brackish Intertidal Mudflat
Authors: Admiraal Wim , Bouwman Lukas A. , Hoekstra Leo , Romeyn Karin 
Published: February 2007

AbstractMicro‐ and meiofauna are the predominant consumers of diatoms on a brackish intertidal mudflat. The impact of grazing on the benthic diatom populations was studied by field observations and feeding experiments on a few abundant members of the community. Only small fractions of the microphytobenthic biomass and production are converted by herbivores. A hypothesis is presented explaining the growth kinetics and productivity of diatom populations and the inefficient transfer of carbon into herbivore foodchains. Data on feeding rate and population dynamics of the nematode species, Eudiplogaster pararmatus, are discussed in view of the seasonal succession of edible diatom species.
The Recovery of the Biotic Community in a Lotic Freshwater Habitat after Extensive Destruction by Chlorine
Authors: Heckman Charles W. 
Published: February 2007

AbstractThe recovery of a temperate zone biotic community in a lotic freshwater habitat after acute chlorine poisoning was nearly completed in four months (May to September). This was facilitated by the water flow, which rapidly removed the toxic residues of the chlorine and transported organisms from the intact community upstream into the impoverished habitat. The first aggregation in the ditch after the chlorine was eliminated consisted of survivors, including members of species that failed to produce new generations. These were joined by pioneer species of the families Simuliidae and Chironomidae, the larvae of which appeared in massive numbers. This aggregation was displaced by a more diverse fauna as the macroflora and microbiota re‐established themselves, providing food and anchorage for the invertebrates. The populations of large fishes are slowest to return because a considerable amount of time is required for the migration and growth of the recruits. While the chronic intoxication of a habitat produces changes in community structure, an acute poisoning is followed by a nearly complete restoration of the original biota, the recovery time being determined by the proximity of recruits for resettlement.
Pelagic Diatom Populations in Lentic Freshwater Microcosms
Authors: Harte John , Levy Donald , Rees John T. 
Published: February 2007

AbstractThree experiments, involving simultaneous monitoring of selected biological and chemical parameters in 50 l laboratory microcosms and the epilimnia of their parent reservoirs, were carried out from the autumn of 1978 to the winter of 1980. Experiments lasted 8‐13 weeks, their aim being to ascertain degree of similarity between laboratory and field systems. Microcosm dynamics, specifically diatom dynamics, most closely paralleled that found in reservoirs during late spring and early summer, a time of thermal stratification. During winter months when thermal stratification was absent or less pronounced, microcosm diatom populations diverged significantly from reservoir populations within 24 days. It is inferred that microcosm design and operating conditions have a major bearing on microcosm usefulness for environmental assessment.
Selective Predation in Freshwater Zooplankton Communities
Authors: Greene Charles H. 
Published: February 2007

AbstractThe impact of selective predation in freshwater zooplankton communities is examined with special emphasis on the ecological and evolutionary consequences for the prey. The behavioral interactions between predators and prey are reviewed, and the general patterns in age‐ and size‐selective predation are derived in a semi‐quantitative model. The final section explores the life history adaptations that zooplankton have evolved in response to these different patterns of selective predation.
The Manna Effect: Paradox of the Plankton
Authors: Wangersky Peter J. , Wangersky Charles P. 
Published: February 2007

AbstractA Monte Carlo model of a multi‐species community with a single trophic level, with nutrients supplied randomly in space and time, demonstrates an irreducible variability in species number and composition. Competition between closely similar species does not necessarily proceed to the elimination of the less efficient species because the variability in food supply becomes a more important factor in survival than does even a fairly large difference in efficiency.
Production and Ecology of Benthic Chironomid Larvae (Diptera) in Lake Hayes, New Zealand, a Warm‐monomictic Eutrophic Lake
Authors: Graham Alan A. , Burns Carolyn W. 
Published: February 2007

AbstractThe distribution and abundance of larval chironomids in Lake Hayes were studied from December 1973 to March 1975. The mean annual production of the two dominant species, Chironomus zealandicus and Chironomus sp. a, was 29.2 g m−2 dry weight which is approximately 4.3 % of the average annual phytoplankton production in the lake. A high annual P/B ratio of 18.5 is consistent with the multivoltine life cycle of C. zealandicus. Larval chironomid production in the second summer when Anabaena blooms were absent was only one quarter of that in the first summer and is consistent with the hypothesis that the production of benthic chironomids in Lake Hayes is closely linked to that of the phytoplankton through the sedimentation of autochthonous organic matter.
The Possible Importance of Primary Amino Nitrogen in Nitrogen Regeneration by Coastal Marine Sediments in Buzzards Bay, Massachusetts
Authors: Christensen John P. , Rowe Gilbert T. , Clifford Charles H. 
Published: February 2007

AbstractTo investigate the role of primary amino nitrogen (PAN) in nitrogen regeneration by marine sediments, the distribution and fluxes of PAN in organic‐rich coastal sediments off Massachusetts (USA) were investigated. Decreases with depth in the sediment of total organic carbon, organic nitrogen, and PAN contents indicate that organics with C to N ratios of about 6, such as primary amines, are selectively consumed. Near the sediment surface, dissolved PAN (DPAN) accumulates and supports a large DPAN flux into the water column and this flux greatly exceeds the inorganic nitrogen flux. Consumption of C, N, and PAN was investigated using diagenetic equations describing their exponentially decreasing distributions with depth and which included the effects of sediment mixing, sediment accumulation, and consumption, considered to be a first‐order reaction rate. Calculations showed that the reaction rate constant for PAN was between 5.1 and 26.1 times faster than that for the utilizable organic N and the depth‐integrated consumption of PAN accounted for between 8.6 and 43.9% of the N disappearance rate. These ranges are estimated when sediment accumulation dominates over sediment mixing (the lower values) and when mixing dominates over accumulation (the upper values). Although the magnitude of D is unknown, these calculations indicate that PAN, which comprises less than 2% of the organic N, has an important role in sedimentary nutrient dynamics because of its enhanced reactivity.
The Seasonal Relationship Between Meroplankton and Megabenthos on Georges Bank, Gulf of Maine, Northwest Atlantic
Authors: Maurer Don , Toner Richard C. 
Published: February 2007

AbstractA broad based environmental study of Georges Bank included samples of zooplankton and dredge samples of megabenthos for four seasons. The purpose of this account is to examine the seasonal relationship between meroplankton and megabenthos.Mean densities of meroplankton were relatively high at shallow near shore stations and the central Bank and low at deeper stations. Densities were highest in the summer and lowest in the winter for major taxa. For megabenthos the number of species, relative abundance and relative biomass was also highest in the summer and lowest in the winter. Dominant megabenthos provided year round occupants and seasonal pulses. Year round occupants and seasonal peaks of some megabenthos facilitate year round foraging by demersal finfish enhancing the general production of the Bank. It was concluded that Georges Bank megabenthos was part of a broad ranging continental shelf, sand bottom fauna extending at least from Gaspe Bay to the offing of Chesapeake Bay.
Etude préliminaire des effets de la mise en eau du Réservoir de LG‐2 (Territoire de la Baie James, Québec) sur le seston grossier et le zooplancton des rivières et des lacs inondés
Authors: Pinel‐Allout Bernadette , Méthot Ginette 
Published: February 2007

Preliminary Study of the Effects of Impoundment of LG‐2 Reservoir (James Bay Territory, Quebec) on the Net Seston and the Zooplankton of Impounded Rivers and LakesThe effects of impoundment on the biomass of net seston and zooplankton in lakes and rivers of Northern Quebec were investigated from 1978 to 1980, before, during and after the completion of LG2 Reservoir on the River La Grande (53° 54′ N, 76° 78′ W). In lotic stations, a 41–77% decrease in net seston was observed due to sedimentation of mineral particles (36–80 mg/m3 in 1978 to 10–21 mg/m3 in 1979). The ratio of organic to total seston increased from an average of 0.18 before the impoundment to 0.65 after. The flooding phase brought about a trophic upsurge; the biomass of the zooplankton increased by one to two orders of magnitude at the various sites; the greatest increases occurred in the central stations near the dam, the smallest in the upper stations near the inflow. In lake stations, no significant difference between years could be detected; the mean zooplankton biomass for all three years ranged from 6.59 mg/m3 to 34.34 mg/m3. Spatial variations between lakes were however significant. Results are compared with those in other natural lakes in Canada and reservoirs in the United States. Comparative examination of phytoplankton biomass before and after impoundment of LG2 Reservoir suggests that bacterioplankton and allochthonous organic material are key elements in the pelagic food chain after impoundment.
Abundance and Community Structure of Limnetic Zooplankters in Kumaun Lakes, India
Authors: Sharma P. C. , Pant M. C. 
Published: February 2007

AbstractThe zooplankton compositions in the limnetic zones of two subtropical lakes, the Nainital and the Bhimtal (U.P., India) were more or less similar in terms of species composition. Numerically, zooplankters were abundant during the thermal stratification (summer‐autumn) period and scarce during the over‐turn (winter). The density of the zooplankton population reported from the eutrophic Lake Nainital was higher than in the oligotrophic Lake Bhimtal. Among the three groups studied copepods dominated over cladocerans and rotifers in both the lakes. The Shannon Weaver diversity was higher for Lake Bhimtal than for Lake Nainital. The community structure has also been discussed on the basis of crustacean species.
The Effects of Sampling Intervals on Phytoplankton Growth and Loss Values Derived from Seasonal Phytoplankton Biomass Variations in an Artificial Lake
Authors: Horn Heidemarie 
Published: February 2007

AbstractDetailed vertical phytoplankton sample series with a good resolution were taken every 3–4 days for almost two years from the artificial Lake Saidenbach. The intervals between samplings were systematically increased by regularly “ignoring” certain samples so that six different annual curves based on different sampling frequencies were obtained to describe phytoplankton variations in the course of the year from a single time series. In this way it was possible to study the effect of the interval between samplings on the results of phytoplankton studies and on the rates of change and turnover calculated from the biomass. The results show that the maximum rates of change and turnover values yielded by half‐weekly samplings are some 20–30% higher than those yielded by weekly samplings. Sampling intervals smaller than 3–4 days yield not much increased rates of change and turnovers. This implies that short term changes in the phytoplankton are more accurately detected by half‐weekly samplings. It is therefore suggested that, depending on the nature and objectives of the investigations, sampling intervals of 3–4 weeks are sufficient for the winter, but during the growth period (spring to autumn) samples should be taken at least once a week or fortnightly.
Prolongation of Postembryonic Development in Experimental and Natural Cladoceran Populations
Authors: Romanovsky Yuri E. 
Published: February 2007

AbstractOne of the methods for determining the duration of postembryonic development is the calculation method suggested by Gras and Saint‐Jean (1978) for populations with continuous reproduction and stable age distribution. After inserting time‐weighted means for instantaneous birth rates into the formula, it is possible to calculate the growth rates of the juveniles during each interval between obersvations for a non‐stationary population. Estimated values were in a good agreement with those obtained from computer‐constructed populations and determined directly from a natural cladoceran population. The duration of postembryonic development in cladoceran populations increases significantly during periods of food depletion caused by filtering activity of herbivorous zooplankton. This physiological response together with the decrease in age‐specific fecundity permits effective regulation of population abundance through the birth rate.
A Mathematical Submodel for the Planktonic Rotatoria in the Ecosystem of the Barther Bodden (Southern Baltic Sea)
Authors: Vietinghoff Ulrich , Hubert Marie‐Luise , Heerkloss Reinhardt , Arndt Hartmut , Schnese Werner 
Published: February 2007

AbstractOf the rotifers inhabiting the shallow eutrophic Barther Bodden, the pelagic species feeding on fresh detritus comprising dead diatoms and green algae are of particular importance in terms of biological production. The submodel presented here refers only to this functional group (Filinia longiseta, Brachionus quadridentatus and Keratella cochlearis). The biological situation, the working hypotheses, the equation system, the measured values and coefficients used and the wiring diagram are given. The curves obtained with the model are shown in detail and tested against various criteria. Agreement between the model curves and the measured data is good.
Measurements of some Groups of Microbial Populations with Special Reference to Denitrification in Water and Sediments of Fish Farming Ponds under Mono‐ and Polyculture Systems
Authors: Jana B. B. , Patel G. N. 
Published: February 2007

AbstractThe spatial and seasonal distribution of some groups of bacteria as well as the rates of denitrification (natural and potential) have been investigated in water and sediments of four fish farming ponds under monoculture, traditional and polyculture systems in India. Marked differences in the monthly means of bacteria were found to exist in these fish ponds depending upon their trophic statuses. The seasonal changes of bacteria are discussed in relation to the variation of environmental factors.
A Quantitative Comparison of Two Zooplankton Sampling Methods, a Plankton Trap and a Towed Net, in the Baltic
Authors: Kankaala Paula 
Published: February 2007

AbstractA comparison between a large plankton trap with a capacity of 23 litres and a modern towed net was made in the course of zooplankton production studies in the Baltic. On the average, the net efficiency was 75% of that of the trap. Both methods were equally efficient in catching naupliar stages of copepods. The net efficiency was especially low during the zooplankton maximum for adult copepods and cladocerans (41 and 51%, respectively), probably due to the active avoidance of the net by fast swimming species. The net was only about 66% as efficient as the trap for catching rotifers. This difference is probably caused by the loss of small and softbodied forms through the mesh. Only about 65% of the total zooplankton biomass retained in the trap was collected by the net. Net sampling is not recommended for quantitative zooplankton studies.
Manipulation of the Pelagic Food Web by Stocking with Predacious Fishes
Authors: Benndorf Jürgen , Kneschke Helmut , Kossatz Kathrin , Penz Eckhard 
Published: February 2007

AbstractTwo water bodies, which are quite different with respect to nutrient load and hydrophysical conditions, are used to perform long‐term experiments in the whole water on the manipulation of the pelagic food web. Experimental water 1: Bautzen Reservoir (Dresden County, GDR); hypereutrophic, mean depth=7.4 m; extremely exposed to wind. Experimental water 2: Small pond in a former quarry (Dresden County); mesotrophic; mean depth=7.0 m; extremely protected against wind. Only the results of Experiment 2 are given in detail. Experiment 1 is not yet finished.Experimental water 2 was investigated in 1979 and 1980 when no predatory fish species were present, and in 1981 after introduction of predators (mainly Salmo gairdneri). The response of the ecosystem can be summarized as follows: (1) The biomass of the zooplankton‐eating fish (mainly Leucaspius delineatus) decreases rapidly. (2) The biomass of the herbivorous zooplankton increases to nearly 400%. (3) This finding reveals that the dense population of an invertebrate predator (Chaoborus flavicans) is not able to compensate for the feeding pressure of the small fish. But the intensive feeding activity of the young larvae of Chaoborus leads to a strong increase (200 to 300%) in the mean individual body size of the crustaceans during late summer and autumn, which supports the “balanced predation hypothesis”. (4) The remarkable enhanced grazing pressure of the herbivorous zooplankton on the phytoplankton does not exert any effect on the total phytoplankton biomass. This result is interpreted as a consequence of growth limitation of the algae due to low nutrient (Fe, P) supply in that mesotrophic water body. But the phytoplankton composition does reveal a strong response to the enhanced grazing pressure. The Secchi depth increases as a consequence of this change in the phytoplankton composition.The conclusion is drawn that, when using biomanipulation as a means of water quality management, it is obviously necessary to take into account the complex interrelationships between fish stocks, predacious invertebrates, herbivorous zooplankton, phytoplankton as well as nutrient load and hydrophysical processes in the particular water.
Organic Carbon in a Eutrophic Fishpond
Authors: Blažka Pavel , Procházková Lidmila 
Published: February 2007

AbstractAccumulation of dissolved organic carbon (DOC) was studied in a eutrophic pond and in cultures of Scenedesmus abundans. Samples of pond water and media were treated with a cation exchanger in Na cycle and chromatographed on Sephadex G 25 and G 10. — UV spectra of the peak fractions were recorded. In the pond about half of the organic carbon is in fractions with an apparent molecular weight (AMW) of 500–1000, while in the algal medium (after cultivation) most of organic carbon has an AMW of about 120. These and spectral data did not suggest that aromatics and compounds with conjugated double bonds were major organic constituents of DOC.
A posteriori Investigation of Spatial Arrangements in Gnathostomulida and Copepoda
Authors: Farris Richard A. , Lindgren Eric W. 
Published: February 2007

AbstractCopepods at MHTL and gnathostomulids from MHTL to sublittoral sands were studied in 162 samples from Tucker's Town Cove beach, Bermuda. Species were analyzed for mean density (X̄), mean crowding (
equation image
), and patchiness (
equation image
/X) using Lloyd's a posteriori statistic for mean crowding. Diversity was computed using the Shannon‐Wiener Index (H′). Copepoda were found to be nearly three times more abundant than Gnathostomulida at the MHSL site. 74% of the copepods were found in the surface cm of sediment while 87% of the gnathostomulids were located between 1–4 cm deep and within the RPD layer. Similar gnathostomulid distributions were found at MSL and sublittorally. Mean density and mean crowding were highly variable for the numerically dominant species in each group, whereas patchiness was relatively constant with values ranging between
equation image
/X̄ = 1.50 to 2.73 for P = 0.05. Such consistency in patchiness between two diverse taxa having distinctly different vertical distributions may suggest that there exists an optimum degree of patchiness for interstitial fauna and that the optimum values may lie within a range similar to that of the numerically dominant Copepoda and Gnathostomulida. Overall patchiness was slightly higher in the gnathostomulids and in the rarer species as predicted by Lloyd's statistic. Diversity was higher in the Copepoda, attributable primarily to species richness.
Potential Mobility of Phosphorus in Different Types of Lake Sediment
Authors: Boström Bengt 
Published: February 2007

AbstractThe fractional composition and potential mobility of sediment phosphorus was investigated in a number of Swedish lakes with different characteristics. Differences between sediments regarding P release patterns in laboratory experiments with varying pH and redox conditions could largely be explained by differences in the fractional composition of the sedimentary P. Sediments from sewage‐loaded lakes contained considerably more loosely adsorbed P than unpolluted lakes. P release was redox‐sensitive and strongly favoured by high pH values in sediments with a high content of aluminium and iron‐bound P. Other sediments released primarily organic and loosely adsorbed P, and in such cases less P was released and redox and pH conditions had less effect. Comparisons with P release rates determined by mass balance calculations were made.
The Seasonal Succession of Epiphytic Communities within an Equisetum fluviatile L. Stand in Lake Pääjärvi, Southern Finland
Authors: Kairesalo Timo 
Published: February 2007

AbstractThe seasonal succession of epiphytic communities on Equisetum fluviatile was controlled both directly and indirectly by the macrophyte. Decaying macrophytic material supported rich algal growth and biomass accumulation in spring and early summer. Emergence of the macrophytes severely reduced underwater light availability, and the epiphytic algal biomass declined rapidly as a result of both lower photosynthetic activity of the epiphytic algae, and more intensive grazing by invertebrate herbivores. Epiphytic N: P ratios were lower than those in the water around suggesting that either the water was not the only source of phosphorus for the epiphytic algae or the algae took phosphorus up selectively from the water. Low epiphytic C: N ratios suggested a high potential nutritional value for herbivores.
Studies on the Feeding of Coregonus pollan (Thompson) Alevins and Fry in Lough Neagh
Authors: Dabrowski K. , Murawska E. , Terlecki J. , Wielgosz S. 
Published: February 2007

AbstractPollan alevins and fry were collected in the open lake between March and July. Fish were measured in total length, upper (Uj) and lower (Lj) jaws and weighed. The gape‐height was calculated according to two different formulae. For the examined fish the relationship between total length (Lt) and gape‐height (D) was found to be D=0.092 Lt—0.306. The size of food in the gut content was measured, and this increased during fish growth, but amounted to 13.2–26.0 % of D. In the first food of pollan alevins, nauplii and copepodites dominated, but after the alevins had reached 20 mg, copepods appeared to be more frequent food items. In the middle of May, Daphnia longispina was found in the food of pollan fry with an individual weight over 45 mg. Benthic invertebrate fauna were taken after the fish weighed more than 1.4 g. Chironomus anthracinus and Chironomus sp. larvae were among the food item dominants.