bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of Aquatic Fungi. XXVI. Hyphomycetes in the River Supraśi in Various Seasons of the Year with Reference to Environmental Conditions
Authors: Czeczuga Bazyli , Orłowska Mirosława 
Published: February 2007

AbstractThe authors investigated the aquatic mycoflora and the environmental factors at two sites of the River Supraśl on the occurrence of various aquatic Hyphomycetes.At the stations investigated the presence of 56 aquatic Hyphomycetes species was noted. The foam of both site I and site II contained more species than did the water collected at these sites. Most of the aquatic Hyphomycetes found at the sites studied are common fungi quite frequently found in different kinds of water bodies. On the other hand 17 species have been comparatively seldom encountered up to date.
Limnological Studies in a Tropical Man‐Made Lake (Lagartijo Reservoir) Venezuela
Authors: De Infante Aida Gonzáles , Infante Otto 
Published: February 2007

AbstractThe purpose of this study was to evaluate the present limnological conditions of Lagartijo reservoir (North central Venezuela) and to compare them with conditions reported in early studies. Lagartijo reservoir supplies an important part of the water demand for Caracas city and wide fluctuations on water volume occur annually.Relevant physical, chemical and biological data were obtained from three sampling stations between July 1990 and April 1992. The reservoir was permanently stratified with a well defined thermocline. The main tributary (Lagartijo river), with a temperature about 6° C colder than the surface temperature of the reservoir, flows through the hypolimnion producing distinct chemical and biological properties. The average of the daily integral phytoplankton photosynthesis was 1550 mg C m−2 d−1. The present annual average of the net photosynthetic activity is about 40% lower than the reported for 1970 and corresponds to an apparent decrease in phytoplankton biomass and to the reduction of the euphotic zone. Photosynthetic activity was higher for the wet season than for the dry season. Actual chlorophyll a concentration in the euphotic zone averages 4.9 μg l−1. Abundance of zooplankton was significantly decreased in comparison to 1976. Mean zooplankton biomass (dry weight) for the upper 10 m layer was 596 μg l−1. Copepods accounted for most of this biomass, followed by cladocerans and rotifers. For the first time, a freshwater medusa (probably Craspedacusta sowerbyi) was collected from Venezuelan waters.
Comparative Limnology of Four Cuban Reservoirs
Authors: Laiz Orlando , Quintana Isabel , Blomqvist Peter , Broberg Anders , Infante Aida 
Published: February 2007

AbstractFour Cuban reservoirs (Higuanojo, Tuinicu, Lebrije and Zaza) in the Sancti Spiritus province were studied in 1988–1989. The study was based on monthly samples of physical, chemical and biological components of the pelagic ecosystem.The reservoirs were warm‐monomictic with more or less complete water mixing during the dry season and stable stratification during the wet season when inflow of water was highest. The mixing event was very important in regulating the biology and chemistry of the reservoirs. During the stratified period the water was anoxic below 10 m depth and reduced compounds, especially ammonium, accumulated. In the reservoirs with less stable stratification, ammonium was occasionally oxidized and the nitrogen lost to the atmosphere through denitrification. Phytoplankton biomass varied considerably among reservoirs and was not only correlated to total‐P, but also to light, Zooplankton biomass and composition was related to availability of good quality food and to the intensity of fish predation.
Variability and Representativness of Lake Variables
Authors: Håkanson Lars 
Published: February 2007

AbstractThis paper summarizes results from extensive field work in 95 Swedish lakes. It discusses four years (1986–1989) of monthly data on pH, Secchi depth, temperature, alkalinity, total‐P, conductivity, Fe, Ca, hardness and colour. These variables vary both temporally and areally. The focus here is on such variations and patterns in variations, and how to express lake‐typical values, not for specific sites and sampling occasions, but for entire lakes and longer periods of time (months‐years). This is of importance in monitoring and validating models. A definition of total variability (TV), expressing variability between adjacent months within the year, and between the same month for different years, is presented. Selected results: An important pattern emerges for total‐P with marked increases in TV during the summer and minimum values in winter. The pattern for colour shows lower TV during summer and higher TV during fall. The TV‐values for pH are low and stable thoughout the year and no clear seasonal pattern can be seen. A seasonal pattern exists for conductivity, alkalinity, hardness, and Ca with higher TV during spring. The results concerning the variability within and between lakes show that the greatest differences exist for conductivity and Fe; the smallest (except temperature) for pH and alkalinity.
Characteristics of the Summer Hydrological Regimen and Chlorophyll Distribution in the Volga River Reservoirs
Authors: Litvinov A. S. , Mineeva N. M. 
Published: February 2007

AbstractField observations on chlorophyll content and hydrological parameters such as temperature, dissolved oxygen and conductivity profiles, Secchi disk transparency and water color were carried out at 5 reservoirs of the Mid and Lower Volga River during August 1990 and 1991. Principal Component Analysis distinguished four classes from 46 sampling points based on the hydrological regimen and phytoplankton development.
Description of the Immature Stages of Three Nearctic Species of the Genus Berosus Leach (Coleoptera: Hydrophilidae)
Authors: Archangelsky Miguel 
Published: February 2007

AbstractEgg cases, larvae, and pupae of Berosus corrini Wooldridge 1964, Berosus hoplites Sharp 1887, and Berosus pugnax LeConte 1863, are described and illustrated with line drawings. Bionomic and behavioral observations of larvae and adults are included. Keys to different instars of B. hoplites and B. pugnax larvae are provided.
Limnology of a Warm Hypertrophic Wastewater Reservoir in Israel I. The Physical Environment
Authors: Juanico Marcelo 
Published: February 2007

AbstractThis paper deals with stratification in a small reservoir (50 000 m3volume, 5.5 m depth) receiving wastewater with a BOD of 80 mg/1 during the winter in order to irrigate agricultural areas during the dry summer. The reservoir goes through three partially overlapping annual cycles: solar radiation, water temperature and reservoir operation. It presents both permanent (deep) and ephemeral (shallow) stratification during the summer in spite of the strong breeze, due to both thermal and biogenic chemical gradients. There are stratified and non‐stratified wastewater reservoirs in Israel. Stratification in hypertrophic impoundments seems to depend also on parameters derived from the chemical composition of hypertrophic waters. (e. g., turbidity, biogenic gradients, wind/water friction coefficient, viscosity).
Colonization, Succession and Environmental Conditions of the Macrozoobenthos in a Regulated, Polyhumic Reservoir, Western Finland
Authors: Koskenniemi Esa 
Published: February 2007

AbstractThe colonization and succession of the macrozoobenthos in a polyhumic, winter‐regulated reservoir, Lake Kyrkösjärvi in Western Finland (62° 45′N, 22°48′E, A = 6.4 km2at summer HW, zmean= 2.5 m and zmax= 7 m) was studied from its filling in 1981 until 1989 (in 1981–83, 1986 and 1989). The zoobenthos was sampled over the whole reservoir bottom using qualitative and quantitative methods during three open‐water seasons and winter samples were taken in the regulated and submerged areas during the maximum draw down (2 m) in March‐April.Colonization during the first summer revealed two phases. The first phase featured dominance of actively swimming and adult‐dispersing taxa. The second phase was characterized by a mass occurence (high abundance and biomass) of chironomids (Chironomus, Glyptotendipes) and the isopodAsellus aquaticus. Asellusoriginated in a small bog pond in the northern outlet basin, and it was the dominant zoobenthic species during the study period. The species ofChironomus, most of them pool inhabitants of natural waters, succeeded each other.In the later study years, when the zoobenthos at the sites was determined more by habitat (spatially) than by the succession (temporally), the reservoir bottom could be divided into three areas: a) deep areas, ≧3 m, with an increasing occurrence of lacustrine species (eutrophic or dystrophic), b) shallower organic bottoms, ≦ 2 m, with many pool‐inhabiting and eurytopic species, and c) some eroded areas in the shallow littoral, ≦ 0.5 m, where lacustrine species became common.Water‐level regulation in winter killed only a small proportion of the fauna in the organic‐rich peatland and forest bottom areas representing the majority of the regulated zone. Hence, the regulated areas had almost everywhere high abundance and biomass values throughout the year, deviating from the results found by other authors in strongly regulated lakes, which have maximum values just below the draw down limit.
The Influence of Pack Size and Position, Leaf Type, and Shredder Access on the Processing Rate of Atherosperma moschatum Leaves in an Australian Cool Temperate Rainforest Stream
Authors: Campbell Ian C. , Enierga Gina M. , Fuchshuber Lilian 
Published: February 2007

AbstractFactors affecting the processing rate of packs of southern sassafras (Atherosperma moschatum) leaves were investigated in an Australian cool temperate rainforest stream pool. Processing rate was strongly influenced by pack weight fitting a linear inverse relationship. Processing was not significantly (p>0.05) affected by whether the packs were placed on bricks or free on the stream bed. Free packs, but not packs on bricks, were processed more rapidly near the bank than in midstream (p = 0.050). Packs placed in 300 μm mesh bags, with one side unsealed were processed at the same rate as packs attached to bricks or free on the stream bed, but packs in sealed 300 μm mesh bags were processed significantly more slowly (p<10−4). Abscissed leaves were processed significantly more slowly than fresh leaves (p<10−5) and at a rate not significantly different to leaves sealed in mesh bags (p = 0.197). There was no consistent pattern of difference between processing rates in summer and winter. The results indicate that the size of litter packs may be a more important factor in influencing processing rate estimates than the method of attachment of the packs. The slow rate of processing of abscissed leaves compared with fresh leaves indicates that they were at most, slightly influenced by stream shredders. The absence of a consistent pattern of difference between summer and winter processing rates is consistent with the results of previous litter processing studies from southeastern Australia although no clear causal factor can be identified.
Comparison of Community Structure of Soft‐Bottom Macrobenthos of the Newport Submarine Canyon, California and the Adjoining Shelf
Authors: Maurer Don , Robertson George , Gerlinger Thomas 
Published: February 2007

AbstractCommunity structure of soft‐bottom macrobenthos from Newport Submarine Canyon, California, was compared to that on the adjoining shelf. Four hypotheses involving sediment characteristics, community structure, benthic feeding types and seasonal population fluctuations were posed. Results indicated that there were statistically significant differences between the canyon and adjoining shelf. Although there were differences in sediment geochemistry between the canyon and shelf, sediment type played the major role influencing differences in community structure and feeding. Operation of a shelf outfall has not demonstrably changed the canyon soft‐bottom macrobenthos for at least 16 years and probably closer to 27 years.
A Review on Effect‐Dose‐Sensitivity Models for Aquatic Ecosystems.
Authors: Håkanson Lars 
Published: February 2007

AbstractEffect‐dose‐sensitivity (EDS) models for entire ecosystems, like lakes and defined coastal areas, ought to play a paramount role for environmental sciences and management. The aim of EDS‐models is to provide quantitative predictions relating operationally defined ecological effect parameters to compatible dose and sensitivity parameters. Empirically validated EDS‐models provide a tool to simulate ecosystem effects of practically feasible remedial measures. The main objective of this paper is to give a compilation of existing EDS‐models for aquatic ecosystems. The aim is not to repeat derivations and equations but to present some basic components of EDS‐models, their presuppositions and applicability. Since, at present, there exist EDS‐models for mercury, radiocesium and phosphorus in lakes and nutrients (N and P) in coastal areas, this compilation can be rather short. To the best of the authors knowledge, there exist no EDS‐models (that meet the criteria given in this work) for other types of ecosystems (like forests, agricultural land, urban areas, etc.) or for other types of contaminants (like metals, acidifying substances, halogenated toxins, etc.). Another aim is to clarify the difference between traditional mass‐balance models (i.e., dynamic models) and ecometric (i.e., statistical/empirical models) EDS‐models, and to give examples of EDS‐models based on both these modelling approaches, and techniques (dimensionless moderators) to link these two ways of modelling. The paper also gives examples of the practical use of EDS‐models. A new ecometric EDS‐model for nutrients in coastal areas, where the oxygen concentration of the bottom water is used as an effect parameter, is presented. The idea with this part is also to give the steps in the ecometric derivation of EDS‐models.
The Stratification of Pools in the Alluvium of the River Lužnice
Authors: Pithart David , Pechar Libor 
Published: February 2007

AbstractThe stratification of two shallow and small pools, situated in a floodplain ecosystem, was investigated.A new methodological approach was applied. The parameter called summarized chemical and biological stratification (SCB), was derived from basic limnological parameters in order to evaluate the global intensity of chemical and biological stratification and to compare it with a thermal one.Three situations were described when the seasonal courses of thermal and SCB stratification were compared: 1. Both SCB and thermal stratification are present. 2. The water column is homogeneous — there is no stratification in the pool. 3. SCB stratification is present, but the water is homoiothermic. The thermal stratification is very unstable because of the small volume of the pools and frequent floods. The SCB stratification is of higher stability and it may persist in a homoiothermic water column. In comparison with temperate deep lakes, the thermal stratification does not play such an important role in initiating the chemical and biological stratification. The surface/volume ratio and the depth in the pools are lower, which cause the “bottom‐initiated” quick renovation of stratification even in homoiothermic water.The differences in oxygen regime, volume and localization of both investigated pools cause the differences in stratification patterns. Frequent oxygen depletions in one of the pools increase the intensity of stratification and influence its character. The anaerobic conditions lead to steeper gradients of basic nutrients, pH, alkalinity and water color.The occurrence of a unique phytoplankton community (Cryptophyceae) is probably closely related to the described stratification patterns.
On Paradicranophorus aculeatus ((NEISTWESTNOVA‐SHADINA, 1935) with Remarks on All Other Species of the Genus (Rotifera: Dicranophoridae)
Authors: Koste Walter , Yan Zhuge 
Published: February 2007

AbstractIn 1934, the rotifer Paradicranophorus aculeatus was discovered by Neistwestnova‐Shadina in the River Oka near Murom (Russia). She described it as a Dicranophorus species. In 1958, the rheophilic rotifer was rediscovered in the Polish River Grabia by Pawlowski. This paper reports a third occurence in three samples from the Yun Nan Luoxiao River in China, allowing additional studies of this rare species.
Demographic Modelling in the Analysis of Population Dynamics of Deep‐Sea Macrobenthos
Authors: Gage John D. 
Published: February 2007

AbstractA flexible graphics simulation approach, combining graphics simulation with nonlinear parameter optimisation, is described for estimating likely growth and survivorship from size frequencies measured in samples of deep‐sea benthic invertebrates. Relationships between patterns in size structure, such as bimodal size distributions, are shown to result from limited combinations in values of growth and mortality parameters. Although it is possible to fit demographic models to such size data by optimising goodness‐of‐fit of model frequencies to those observed, the outcome may be dependent on assumptions of a stable age structure from year to year. Simulation studies show that populations with relatively low values of the von Bertalanffy growth‐rate constant K and of survivorship, which show year‐to‐year variability in level of recruitment, will display strongly varying adult size structure at an inter‐annual timescale. Those with high K and high adult surivorship. and which typically show a bimodal distribution of size frequencies, will be much more resilient to such changes. However, high adult survivorship in a relatively long‐lived species will result in relatively stable adult age structure even when K, and the probability for any recruitment at all, is low. The implications of these findings are discussed in terms of contrasting models developed for populations of the deep‐sea ophiuroids Ophiura ljungmani and Ophiomusium lymani, and of the deep‐sea echiniod Echinus affinis. in samples from permanent stations in the Rockall Trough, northeastern Atlantic.
Hatchling Size and Aspects of Biology in the Deep‐Sea Amphipod Genus Eurythenes (Crustacea: Amphipoda)
Authors: Thurston Michael H. , Bett Brian J. 
Published: February 2007

AbstractRecords attributed to Eurythenes gryllus are discussed in the light of described morphological variation, and the existence of a third species in the genus is postulated. The presence of five pairs of oostegites in E. gryllus, a character almost unique among the Amphipoda, is confirmed. Brooding females of E. gryllus and E. obesus, captured in deep midwater hauls in the eastern North Atlantic Ocean, are reported for the first time. The 120 mm E. gryllus female carried 237 hatchlings (mean length 11.13 mm) and the 48 mm E. obesus female 47 hatchlings (mean length 7.99 mm). Hatchlings showed variability in size and bodily proportion, and measurements of individual body segments could not be used to predict overall length. Despite this variability, no evidence for more than one instar was found. The hatchlings of E. gryllus are established as a hitherto unrecognized instar in this species. Egg size for E. gryllus and E. obesus is predicted. The biological consequences of the absolute and relative size of hatchling in the two species, and the depths of capture of the E. gryllus female, are discussed.
Deep‐Sea Macrobenthic Communities at Contrasting Sites off Portugal, Preliminary Results: II Spatial Dispersion
Authors: Lamont Peter A. , Gage John D. , Tyler Paul A. 
Published: February 2007

AbstractSmall‐scale, biogenic processes are thought to be important in creating a mosaic of microhabitats that allow co‐existence of the large numbers of rare species found in deep‐sea sediments. However, the large‐scale effects of hydrodynamic disturbance seem likely to be important in high‐energy settings on the deep‐sea bed. This is investigated by examining spatial dispersion patterns in the macrobenthic populations at two deep‐sea sites off Portugal. The widely differing conditions of sediment disturbance at the two sites are related to differences in macrobenthic species diversity and dominance.Closely grouped, transponder‐mapped, replicate box core samples, each divided into 25 “vegematic” subcores permitted analysis of dispersion patterns at two spatial scales at each site. One site was located on the Tagus Abyssal Plain (TAP), and the other in the nearby Setubal Canyon (SC) where ripple bedforms indicate vigorous bed flow, probably with a tidal periodicity. Greater aggregation at the scale of tens of metres is indicated from the observed numbers of SC species per box core being wide underestimates of the value predicted by rarefaction of the pooled total compared to those from TAP. Variance/mean ratios for individual species of bivalves and tanaids indicated more aggregation in spatial distribution between box cores from SC than from TAP. Dispersion chi‐square analysis also indicated more non‐randomness at SC between box cores than for the TAP cores. However, low faunal abundances in the TAP samples render the results of analyses for this site somewhat inconclusive and therefore the trend indicating less aggregation at TAP compared to SC must be regarded as weak for the groups examined. Analyses of the distribution of tanaids, and bivalves at a 100 × 100 mm subcore scale showed no convincing significant departure from random expectation, but low abundances in these groups reduces the sensitivity of the tests applied. Between‐core aggregation detected at SC may reflect habitat variation resulting from the varying depth within the area of sampling, while within‐core patchiness could be influenced by the ripple bed forms on the sediment.
Nematode Biomass Spectra at Two Abyssal Sites in the NE Atlantic with a Contrasting Food Supply
Authors: Vanreusel Ann , Vincx Magda , Bett Brian J. , Rice Anthony L. 
Published: February 2007

AbstractAbundance and biomass sizes spectra of nematodes have been investigated at two contrasting abyssal sites in the NE Atlantic. The northern site is situated on the Porcupine Abyssal Plain where there is evidence for a high, seasonal input of organic matter derived from the overlying water column. The southern site is the oligotrophic station of the French EUMELI programme off Mauritania and is characterized by low primary productivity in the overlying water column and consequently by a lower organic input to the deep‐sea floor. Low nematode density and total biomass in the surficial centimetre of the sediment at the EUMELI site (89 ind/10 cm2, 8.52 μg wwt/10 cm2), in contrast to the PAP site (254 ind/10 cm2, 54.16 μg wwt/10 cm2), supports a presumed lower food supply to this area. Similary, mean individual nematode body weight is significantly smaller at the oligotrophic EUMELI site (0.0241 μg dwt) compared to the PAP site (0.0511 μg dwt), which supports the hypothesis that mean nematode body size is correlated with food availability. However, differences are much less obvious when comparing geometric mean biomasses and median individual body sizes. The abundance size spectra for the two localities diverge appreciably only in the upper quartile. The differences in mean individual body weights are caused by the relatively greater abundance of larger nematodes at the more eutrophic PAP site.