bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of a Green Alga in the Precipitation of Calcite and the Coprecipitation of Phosphate in Freshwater
Authors: Hartley A. M. , House W. A. , Callow M. E. , Leadbeater B. S. C. 
Published: February 2007

AbstractThe precipitation of calcite from a calcium bicarbonate solution, similar in ionic strength to natural hardwaters, was observed in a series of experiments utilizing an automated culture apparatus. Seeded growth experiments, using calcite seed crystals, were performed at a range of phosphate concentrations to observe inhibitory effects. These experiments demonstrated a linear relationship of increasing inhibition with increasing initial phosphate concentration. A further series of experiments was performed in which an actively photosynthesizing culture of a unicellular green alga (Chlorococcum sp.) was added to the culture vessel in order to initiate precipitation. Experiments to observe spontaneous precipitation, occurring in the absence of both seed and alga additions, were carried out to compare with precipitation rates in the algal experiments. A control experiment was also performed to investigate whether precipitation occurrred in algal cultures maintained in darkness. The carbonate site mechanistic model, developed for calcite precipitation in abiotic conditions, was used to analyse the results of the algal experiments and found to be applicable.
Die Entwicklung des Makrozoobenthon der Oberen Elbe in den Jahren 1988 bis 1994
Authors: Mädler Konrad 
Published: February 2007

AbstractAfter a remarkable reduction of the waste load of the upper part of the River Elbe, a significant restoration of the macrobenthic communities appeared in the last years. The number of found macro‐benthic taxa raised up from 30 to 55 with an increasing proportion of sensitive species. The biological water qulity assessment shows a decrease in the saprobic index from 2.96 in 1988/89 to 2.18 in 1994.
The Adhesive Organ of Larval Pike Esox Lucius L., (Pisces)
Authors: Braum E. , Peters N. , Stolz M. 
Published: February 2007

AbstractNewly hatched pike laryae swim by lateral movements of the trunk. The swimming path is directed upwards. They do not avoid obstacles but interrupt any movements immediately when colliding a substrate. Paired cement glands in rostro‐nasal position excrete an elastic connection between larva and the touched substrate. Larvae spend yolk sac stage in a motionless position.The glands were studied by scanning electron microscope, by lightmicroscope and transmission electron microscope. The organs consist of two rostro‐lateral areas which have a striking sculptured surface.The glandular cells are of the high prismatic type with basic nuclei and granulae in the apical parts. The granulae are already reduced in size and number after hatching against the prehatching stage. This indicates an early secretory activity before an attachement occured.There are grounds to consider mainly two ecological aspects in favour of pike larvae attached to substrates. One is the distance from the bottom water layers which are often characterized by oxygen deficiency and low water currents. Because pike larvae develop their gills later the gas exchange occurs with the body surface. Favourable water circulation normally exists in some distance from sediment and improves the respiration.The second aspect is governed by immobility and pigmentation which camouflage larvae against predators.
Autecology of Monhystera paludicola De Man, 1880 – Seasonal, Bathymetric and Vertical Distribution of a Free‐living Nematode in an Oligotrophic Lake
Authors: Traunspurger Walter 
Published: February 2007

AbstractThe autecology of Monhystera paludicola (n = 3766 individuals), a dominant nematode of Lake Königssee, was studied throughout the year 1986. The species comprised 2341% of all nematodes in the littoriprofundal and profundal. Mean yearly biomass was highest at 10 m depth (149 pg/lOO cm2, fresh weight). Abundance peaked twice a year in the littoral (winter and summer) and once in deeper regions (winter). The main reproductive period is the winter. Morphometric data (n = 658) revealed sexual dimorphism in size, body shape and weight. There was considerable water depth and time dependent variation in sex ratios. The proportion of individuals in the top sediment layer increased with water depth. Juveniles and adults were partially segregated in the sediment column. M. paludicola appears to undergo vertical migrations.
The Role of Small Wetlands in Catchment Management: Their Effect on Diffuse Agricultural Pollutants
Authors: Raisin Gregory Wallace 
Published: February 2007

AbstractDespite extensive interest in natural wetlands and their use in waste‐water technology, little is known about how effective they are for the control of diffuse agricultural pollution. The impact of a small upland wetland located along a drainage line on different storm generated discharge events and resultant downstream nutrient loads over a two year period was assessed. Results for individual events indicated that the relationship between this wetland and its catchment was variable. An annual nutrient budget was determined for this wetland for the period March 1994 to February 1995. The wetland retained 9.7 kg yr−1 (20.5 kg yr−1) of nitrogen and 1.5 kg yrl (±0.1 kg yr−1) of phosphorus which represented 23% of the nitrogen and 38% of the phosphorus that flowed from this catchment. It is concluded that this form of wetland has a role in strategic catchment management for the interception of nutrients flowing from diffuse agricultural sources.
Response of Photosynthesis Models to Light Limitation
Authors: Wallace Brett B. , Hamilton David P. , Patterson John C. 
Published: February 2007

AbstractAn investigation into the effect of time step on a common photosynthesis algorithm reveals that the predicted phytoplankton production and biomass depend strongly on the length of the time step. This time step dependence is due to the assumption that a light limitation factor derived from integrating the irradiance over the time step is equivalent to the integrated light limitation factor over the time step. This subtle inaccuracy in defining the factor for light limited phytoplankton production produces a substantial difference in the biomass estimates derived from the two models. To illustrate the difference, the light limitation factor integrated over the time step is implemented in the one dimensional water quality model DYRESM‐WQ. The new version of DYRESM‐WQ is used to simulate chlorophyll N concentrations in Prospect Reservoir, New South Wales. These results are compared to concentrations predicted using the original algorithm. The comparison shows that the new algorithm for phytoplankton production is relatively insensitive to time step, which decreases the difficulty of calibrating the model for chlorophyll a.
On Soil Rotatoria from a Lithotelma near Halali Lodge in Etosha National Park in N‐Namibia, South Africa
Authors: Koste Walter 
Published: February 2007

AbstractA soil sample out of a dried rockpool (lithotelma) on a dolomit hill in the Etosha National Park, Namibia, was investigated for possible occurence of rotifers. Besides a numerous and rich microfaunae, e.g. Zooflagellata, Rhizopoda. Acari, Nematoda, Tardigrada and Copepoda, 24 rotifers were found. Until today, four so far unknown Bdelloidea could be described: Dissotrocha decembullata n. sp., Dissotrocha hertzogi aculeata n. ssp., Otostephanos jersabeki n. sp. and Philodina foissneri n. sp.
Seasonal and Interannual changes of chemical characteristics and phytoplankton in a mountain lake of the Eastern Italian Alps (Lake Calaita, Trentino)
Authors: Salmaso Nico , Decet Fabio 
Published: February 2007

AbstractMeasurements at Lake, Calaita, a small mountain lake located at 1605 m. a.s .l. in a metamorphic catchment area in the south of the Trentino Region (Northern Italy), have revealed great seasonal variations in the chemical characteristics and phytoplankton community during the ice free period in 1992 and 1993. The acidity present in wet precipitations (H+, NH4+) was neutralised within the drainage basin by mineral dissolution which led to an increase of basic cations and alkalinity in the runoff. The dilution during periods of higher discharge, e.g. in spring and autumn, resulted in low values of alkalinity (up to 60 μeq 1−1), pH (mostly <6.7) and conductivity (<8 μS cm−1, 20°C). In summer, the decrease in runoff caused higher alkalinity (>10 μeq 1−1), pH (6.9–7.4) and conductivity values (up to 30 μS cm−1). The phytoplankton showed a major development in summer (with biovolume values of up to 7000 mm3 m−3), two different taxa being dominant in 1992 (Oocystis cf. lacustris) and 1993 (Synedra sp.). Unpredictable climatic conditions have a strong influence on the physical stability of the lake, which makes it more difficult to explain the evolution of the phytoplankton community as opposed to deeper lakes.
Temporal changes of a macrobenthic assemblage in Evros Delta (North Aegean Sea)
Authors: Gouvis N. , Kevrekidis T. , Koukouras A. 
Published: February 2007

AbstractMonthly samples of the macrobenthic fauna were collected during February 1983‐February 1984, in a coastal lagoon of Evros Delta (North Aegean Sea), characterized by a very strong monthly fluctuation of temperature and salinity. 3 groups of samples were distinguished, the first including those taken during the spring months, the second, those taken during summer and autumn, and the third, the samples of winter months. All the above samples were homogeneous concerning number of species, species richness (Margálef index) and evenness, but not as far as species diversity (Shannon‐Wiener index) is concerned. The monthly variation of the total number of individuals and total biomass was significant, with highest values in spring, beginning of summer and autumn. Most months, polychaetes dominating, having the highest relative abundance and wet biomass. The 8 dominating species, which had a cumulative dominance of about 93%, showed strong monthly variation of abundance and biomass.
The functional response of copepodid stages to adult of Parabroteas sarsi (copepoda, calanoida)
Authors: Vega Marina Patricia A. 
Published: February 2007

AbstractP. sarsi is a carnivorous calanoid commonly found in South Andes lakes. Feeding experiments were carried out in order to analyze the functional response of P. sarsi (copepodid IV to adult) on different cladoceran prey. Predation rates increased with increasing prey density up to maximum (type II) in almost cases. The highest attack coefficients were obtained when P. sarsi adults were fed with the smaller prey (C. dubia juvenile and B. longirostris). The ingestion rates of copepodid IV and CV were smaller than for the adults. The ingested biomass as a proportion of predator biomass (Be/Bp) showed an inversal relationship with the predator length. The maximum Be/Bp ratio, in both sex of P. sarsi, was achieved with C. dubia adult, the intermediate‐sized prey.
Species richness of microcrustacea in subterranean freshwater habitats. Comparative analysis and approximate evaluation
Authors: Rouch Raymond , Danielopol Dan L. 
Published: February 2007

AbstractAmong terrestrial biomes the groundwater domain is generally considered to be a species poor environment. This view results, mainly, from the large geographic scale faunistic surveys (tens and hundreds of kilometres) and the traditionally coarse spatial scale (i.e. macroscale level) of ecological analysis. This view has been challenged by Margalef (1993) who suggests that high diversities are to be expected in the subterranean environment comparable to those found in the deep sea because of environmental similarities, e.g. low energetic resources.During the last twenty years long‐term ecological research on much smaller scales, i.e. metres to hundred metres for interstitial media, a mesoscale approach, or kilometre size for karst systems was carried on. Long‐term projects on limnic subsurface systems have shown that the species richness (SR) of the microcrustacea (Harpacticoida, Cyclopopoida, Ostracoda) is much higher than previously considered. Details on Harpacticoida of the alluvial bedsediments of a Pyreneean brook, the Lachein, and on Ostracoda of the alluvial sediments of the Danube plain (the phreatic zone), near Vienna, are presented. The SR values of the interstitial microcrustacea obtained through investigations at a mesoscale level are comparable to those of karstic and/or surface freshwater benthic water systems; they are lower than those of the deep‐sea data sets for equivalent crustacean groups at a similar scale of investigation.From the data presented we infer the following points: (a) The subterranean waters are much more rich in species than earlier accepted, at least for some organismic groups like the microcrustacean copepods and ostracods. (b) Hence, to describe the still unknown fauna it is appropriate to sample the subsurface waters at an ecological scale. (c) Only studies during long‐term ecological projects and with intensive, quantitative, sampling programmes allow a correct evaluation of the subterranean faunal diversity. (d) The species richness of a given subsurface site is strongly dependent on the structure of the habitats and the functioning of the underlying ecosystems. (e) Finally we consider the rationale for the protection of the subterranean faunal diversity.
Occurrence of cyanobacterial blooms in the baltic sea in relation to environmental conditions
Authors: Wasmund Norbert 
Published: February 2007

AbstractCyanobacterial blooms occur regularly in summer in central parts of the Baltic Sea. They are mainly composed of Aphanizomenon sp. and Nodularia spumigena. Both species have almost similar ecological requirements and can roughly be considered a uniform functional group.In order to identify factors that might favour bloom development, water quality data from monitoring programmes were compared with bloom distribution.A salinity from 3.8 to 11.5 PSU proved important for the spatial distribution of the bloom development. The bloom's onset was triggered by temperatures approximating 16°C provided that global radiation was > 120 W/m2 (daily mean) and wind speed was < 6 m/s. Nutrient concentrations decreased immediately before the bloom.The bloom's development ceased with poor weather conditions characterized by low irradiation or high wind speed.
The genus Thermocyclops (Crustacea: Copepoda) in Uzbekistan (Central Asia)
Authors: Mirabdullayev Iskandar M. , Kuzmetov Abdulahmed R. 
Published: February 2007

AbstractFive Thermocyclops species were found in Uzbekistan: T. crassus, T. dybowskii, T. rylovi, T. taihokuensis, and T. vermifer. The last species has been for the first time recorded in the region. The data on morphology, variability and distribution of these species in Uzbekistan are given. A key to determine to the five species is proposed.
Trace metal bioaccumulation in soft‐bottom macrobenthos from the San Pedro Shelf, California
Authors: Maurer Don , Gerlinger Thomas , Robertson George , Nguyen Hai 
Published: February 2007

AbstractThe relationship between sediment trace metals (Ag, Cd, Cr, Cu, Ni, Pb, Zn) and bioaccumulation in tissue of macrobenthos (Parvilucina tenuisculpta, Tellina spp., Macoma spp., Pectinaria californiensis, Nephtys spp., Glycera spp., Metasychis sp., Euphilomedes spp., and Ampelisca spp.) was described from 1975 to 1985 on the San Pedro Shelf, California. Results indicated that: 1) sediment trace metals were elevated at an ocean outfall station; 2) tissue trace metals were never statistically higher at the outfall compared to a reference station except for Zn in Macoma spp.; 3) there were a few statistically significant associations (r) between tissue and sediment metals, but no consistent trends emerged; 4) peak tissue metal concentrations occurred more frequently in the winter than in the summer.
Light adaptation of the phytoplankton diatom Phaeodactylum tricornutum under conditions of natural light climate
Authors: Müller Anna‐Maria , Wilhelm Christian 
Published: February 2007

AbstractCells of Phaeodactylum tricornutum were precultured under axenic conditions in a full medium and then exposed to natural light conditions at various depths in the eutrophic lake „Meerfelder Maar”︁ (Eifel, FRG) for several days. After exposition the cells were characterized with respect to growth parameters, photosynthetic performance and xanthophyll cycle pigments. In order to test the resistance of the cells grown at different depths against photostress, the cells were illuminated with photoinhibitory light. The variable chlorophyll a‐fluorescence and the oxygen quantum yield at a non‐saturating light intensity were simultaneously measured after photostress and subsequent recovery. The xanthophyll cycle pigments and the content in α‐tocopherol were monitored during photostress to get molecular information about the physiological reasons of light‐stress resistance. The data give evidence that cells grown close to the surface show a faster decline in photosynthetic performance and a more efficient recovery than cells from lower depths. There is clear indication that under natural conditions when the light is fluctuating between optimal, sub‐ and supraoptimal intensities the photostress resistance is much higher than under conditions of the absence of light stress. The molecular basis for light stress resistance seems to be the pool size and the conversion kinetics of the xanthophyll cycle pigments and the capacity of the oxygen‐scavenging system. The effect of in‐situ light adaptation is discussed with respect to the assessment of the potential of the primary production.
Demography of a population of Moina micrura kurz (Crustacea: Cladocera) in a temporary pond, peninsula of paraguaná, Venezuela
Authors: López Carlos , Theis Solange 
Published: February 2007

AbstractA population of M. micrura Kurz from a shallow, muddy and temporary pond, located in Peninsula of Paraguaná, western Venezuela, was studied from filling to drying phase. Population density, age structure, fecundity, and length of females, were determined. This population showed a low population density (< 50 ind/1), a low and density‐dependent fecundity (mean eggs/adults = 1.3; mean clutch size = 2.1 eggs + embryos), and low juveniles to adults ratio (0.71). No significant correlation was detected between mean clutch size and mean body length of ovigerous females. Our results suggest effects of food limitations, and fish predation on demographic parameters of this population. Still, in unfavourable conditions, some demographics features associated to opportunistic species were evident.
Longitudinal zonation and life cycles of macrozoobenthos in the Mauerbach near Vienna, Austria
Authors: Baumgartner A. , Waringer J. A. 
Published: February 2007

AbstractA total of 12277 benthic invertebrates were caught from November 1990 to October 1991 at the Mauerbach, a first to fourth order forest brook near Vienna, Austria, using a Surber sampler and a hand net. Five taxa comprised 96.6% of the catch: Diptera larvae (45.6%), Amphipoda (37.6%) and larvae of Ephemeroptera (6.4%), Plecoptera (5.3%) and Trichoptera (1.7%).Mean values of macrozoobenthos density ranged from 39514 specimens m−2 at upstream sampling site 5 in December to only 286 specimens m−2 at sampling site 3 in May, shortly after a severe flood.Based on benthic invertebrate population structure, sites 5 and 6 (situated near the source) were clearly separated from the downstream sites 1 to 4. At upstream sites, shredders comprised up to 71.7% of the total, whereas at downstream sites collectors were most abundant. In addition, the proportion of eucrenal species decreased from 12% at site 6 near the source to only 2% at site 1 near the mouth.Among the insect species studied in detail, most were univoltine except Ephemera danica (Ephemeroptera) and Sericostoma personatum (Trichoptera), which had a two‐year life cycle.
Additions to the Lecane fauna (Rotifera: Monogononta) of Thailand
Authors: Sanoamuang La‐Orsri , Segers Hendrik 
Published: February 2007

AbstractLecane superaculeata. n. sp. is described from three localities in Thailand. It resembles the small, cosmopolitan L. aculeata (Jakubski, 1912) but is distinguished by its larger size and conspicuous anterolateral spines. Additional records of some recently described Thai Lecane species and comments on Oriental endemics are presented L. eswari Dhanapathi is newly recorded for the country.
First Record of the Gobioid Fish Eleotriodes wardii Playfair (Pisces: Eleotridae), from the Central Indian Ocean
Authors: Venkateswarlu T. , Rao Kaza V. Rama 
Published: February 2007

AbstractThis species was previously reported only from its type locality (Zanzibar). In 1975 a specimen was collected near Madras at a depth of 15–25 m. A description of the species along with a drawing is provided.
Chemical Studies of Superficial Sediments in Lake Lilla Ullevifjärden
Authors: Ryding Sven‐Olof , Borg Hans 
Published: February 2007

AbstractMany sampling stations are preferable in sediment investigations. With a basis of only single samples an unequivocal determination of the lake's sediment character is hard to obtain. Knowledge of the morphometrical conditions is an advantage, as in steeply sloping parts great changes in concentrations can occur. However, even unexpected distribution patterns can emerge and a map of horizontal distributions in sediments can never be looked upon as completely reliable. The traditional sediment picture (based on dry weight) with increasing concentrations of several elements with depth can often give a false impression of the distribution of amounts per volume wet sediment with maximum values in somewhat shallower parts which, from an ecological point of view, should be the important one.
The Chemical Composition of Four Regions on a Summer Day in Lake Lacawac, Pennsylvania
Authors: Cowgill U. M. 
Published: February 2007

AbstractThis paper is devoted to the varying concentrations of 49 elements found in the water from three littoral sites and one pelagic site, sampled over a five hour period, in Lake Lacawac. These elements were detected in concentrated water samples by use of X‐ray emission and optical emission spectroscopy. The elemental concentrations of the four sampling sites differed. Statistical analyses were used to estimate how chemical mixing proceeded in the surface waters of the lake. Results from a previous study of the chydorid Cladocera living in the sediments beneath the water sampling sites indicated that the more organic sediments contained more individuals than the sandy sediments. The chemical concentration of the water followed the same distribution as did the organisms.
Le Phytoplancton de l'Estuaire moyen du Saint Laurent en amont de l'Ile‐aux‐Coudres (Québec). The Phytoplankton of the Upper St. Lawrence Estuary (Québec)
Authors: Cardinal A. , Cardinal A. , Bérard‐Therriault L. 
Published: February 2007

AbstractThe authors give here a qualitative and quantitative description of the phytoplancton in the brackish waters of the St. Lawrence Upper Estuary (Québec). The very high observed concentrations are the responsibility of fresh‐water forms: Skeletonema subsalsum, Melosira binderana, Diatoma elongatum, Asterionella formosa, Fragilaria crotonensis, F. capucina, Cyclotella striata, Melosira islandica, Ankistrodesmus falcatus and Scenedesmus quadricauda; 193 species are listed in an appendix.
Effet de divers sels alcalins sur la croissance et la nutrition minérale de Lemna minor L
Authors: Strauss René 
Published: February 2007

AbstractLemna minor L. was grown in aseptic culture solutions. With sodium chloride or lithium chloride in the solution, the plant increased in yield. Tolerance of Lemna minor to relatively high level of sodium explains the presence of this plant in brackish waters. A low quantity of potassium is required for optimal growth.Sodium was added to nutrient solutions as chloride or sulphate. At equivalent levels the sodium content of the plant was somewhat higher under sulphate salinity.