bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Limnological Reconnaissance of the Lough Erne System, Ireland
Authors: Gibson C. E. , Foy R. H. , Fitzsimons A. G. 
Published: February 2007

AbstractThe Lough Erne System (Northwest Ireland) consists of two linked eutrophic lakes. Phosphorus input budgets suggested mean catchment exports of 30–62 kg total P km−2 a−1, resulting in a heavy P loading to the small upper lake. The export of soluble P is related to the human population density in the catchment. Although complex in outline, the upper lake has similar phytoplankton populations throughout, but the populations in the simpler shaped lower lake differ quantitatively and qualitatively from place to place. This is probably due to differences in mixed depth. A chlorophyll a map of the surface water of the lower lake, obtained by fluorometry, showed the relationship between algal biomass and depth of water.
Field Investigations and Model Simulation of the Dynamics of Zooplankton Populations in Fresh Waters
Authors: Horn Wolfgang , Benndorf Jürgen 
Published: February 2007

AbstractThe main parameters characterizing the dynamics of a population were determined by field investigations at the Saidenbach reservoir and by means of an ecological model. The results obtained by both methods involving totally different procedures were in good agreement. The gross growth rates obtained by both methods ranged up to 0.14 d−1, and the net growth rates vary between 0.1 d−1 and 0.2 d−1. Field investigations revealed zooplankton mortality rates during summer of about 0.1 compared with 0.08 d−1 for the model. Comparison of the two methods shows how practical investigations may be improved and gives a better insight into the dynamics of zooplankton populations in waters.
Spatial Pattern of a Free‐Living Marine Nematode Community off the Coast of Peru
Authors: Nichols Jean Ann 
Published: February 2007

AbstractThe numerical abundance and biomass of free‐living marine nematodes from sandy sediment off the coast of Peru (water depth 40 m) was similar to that reported from other areas. Dispersion chi‐square analysis indicated that three species were aggregated, while the remaining species were randomly distributed throughout the samples. The most reasonable hypothesis is that variation in size of individual pore spaces is the mechanism controlling the distribution of the aggregated species.
Feeding Habits of Diaptomus ashlandi and Diaptomus sicilis in Lake Michigan
Authors: Bowers James A. 
Published: February 2007

AbstractThe herbivorous habits of Diaptomus ashlandi and Diaptomus sicilis were studied at a nearshore station in Lake Michigan. Filtering and feeding rates were measured from December 1975 to October 1976. Feeding was measured from the change in concentration in three size fractions of chlorophyll a. D. ashlandi fed only on particles in the smallest size class, while the larger D. sicilis consumed particles in all three size fractions. During the isothermal period (winter and spring), the feeding rates of both species were proportional to temperature or chlorophyll concentration. D. sicilis preferentially ingested particles in the largest size class, when this size class increased significantly during the spring bloom. During the summer the highest feeding rates of D. ashlandi occurred in the epilimnion. The highest feeding rates of D. sicilis were in the metalimnion, where large particles in a subsurface chlorophyll maximum were available for consumption. These results indicated the importance of the depth distributions of herbivores and phytoplankton for feeding.
Production of Urea by Bacterial Decomposition of Organic Matter Including Phytoplankton
Authors: Satoh Yasuhiro 
Published: February 2007

AbstractA concentrated colony of Fragilaria crotonensis collected from the surface water of Lake Suwa, which is one of the typical eutrophic lakes in Japan, and organic matter contained in untreated surface water from the same lake were subjected to aerobic decomposition by bacteria in a dark room at a temperature of 20 ± 3 °C. An exponential increase of urea with time was recorded in both of the experiments. The apparent rate constants of urea production were calculated to be 0.083 day−1 for decomposition of F. crotonensis and 0.051 day−1 for decomposition of the organic matter contained in the untreated surface water.This study suggests that urea production by bacterial decomposition of organic matter, including phytoplankton, may be an important source of urea in natural waters under certain conditions.
Occurrence and Distribution of Stony Corals in the Gulf of Cariaco, Venezuela
Authors: Antonius Arnfried 
Published: February 2007

AbstractOccurrence and distribution of stony corals (Milleporina and Scleractinia) in the Gulf of Cariaco were investigated quantitatively using skin‐diving methods. Unusual temperature conditions due to cold upwelling limit coral growth to a depth of 15 m. A clear vertical zonation of species was observed, with five zones, in order of increasing depth, dominated by Porites porites, Millepora complanata, Siderastrea siderea, Dichocoenia stokesi, and Solenastrea hyades.Twenty‐one species of scleractinians and three species of hydrocorals have so far been found in the gulf. Of the total area covered by corals, over 50% is inhabited by Siderastrea siderea, Millepora spp., and Porites porites. A horizontal zonation of the littoral was established based on species composition and density of the coral cover.
Abundance and Distribution of Benthic Macroinvertebrates near Little Egg Inlet, New Jersey, from 1972 to 1974
Authors: Garlo Elizabeth V. 
Published: February 2007

AbstractBenthic collections taken during a 34 month period from Little Egg Inlet, New Jersey were dominated by haustoriid amphipods and collections from a nearshore ridge/swale formation were dominated by ampharetid and capitellid polychaetes. Polychaetes were most abundant at the swale station where density was 2.4 to 17.5 times higher than at other stations. Changes in species composition and density were influenced by increases in the silt/clay component of the sediment which was influenced by depth, bottom topography, and exposure to currents.
Seasonal Cycles of Zooplankton and Related Phytoplankton Development in Three Shallow, Mesotrophic Lakes in Northern Canada
Authors: Moore James W. 
Published: February 2007

AbstractThe primary goal of this study was to assess the importance of food in regulating densities of zooplankton in 3 northern Canadian lakes, where algal availability was low compared to temperate zone water bodies. Collections were made every 2 weeks during the summer and monthly during the winter from April 1978 to April 1979. Since the lakes were similar in most respects, including nannoplankton density, net phytoplankton density, temperature, depth, oxygen concentration and phosphorus levels, the seasonal cycles of the main species (Keratella cochlearis, Kellicottia longispina, Polyarthra remata, Polyarthra vulgaris, Cyclops spp., Diaptomus spp.) were generally similar throughout the study area. Changes in the densities of herbivorous species were poorly correlated with fluctuations in nannoplankton and net plankton availability, implying that food did not limit development. Although predatory copepods, particularly Cyclops spp., were abundant, they also had no measurable impact on the main species. It was therefore concluded that temperature controlled the seasonal cycles and the ultimate population size of most zooplankters.
Correlation Between Urea and Other Chemical and Biological Parameters in Waters of Lake Suwa, Japan
Authors: Satoh Yasuhiro , Okino Tokio , Aoyama Kanzi 
Published: February 2007

AbstractThe vertical profiles of chemical and biological parameters, including urea concentration, have been measured periodically since February of 1977 at a central station in Lake Suwa, which is one of the typical eutrophic lakes in Japan. The seasonal trend in the standing stock of urea in the central water column, together with the ratio of urea versus total inorganic nitrogen in the euphotic zone from 12 March, 1977 to 25 July, 1978, are presented. The possible importance of bacterial decomposition of dead phytoplankton as a urea source in natural waters is demonstrated by this study. At times, a highly significant correlation between the vertical profile of urea and vertical distributions of other chemical and biological parameters which were also measured was found. An apparent in situ utilization of urea by phytoplankton is suggested on the basis of vertical profiles of urea and other chemical and biological parameters.
Population Dynamics of the Polychaetous Annelids of an Intertidal Habitat in Upper Old Tampa Bay, Florida
Authors: Dauer Daniel M. 
Published: February 2007

AbstractFollowing an extensive red‐tide induced mass mortality of the benthic macrofauna of a sandy intertidal habitat, the population dynamics of the polychaete species were studied. Detailed studies of the 12 most abundant species are presented. Data concerning total population levels, reproduction, recruitment, distribution within the intertidal zone, and gut content analyses are integrated in order to explain the observed spatial and temporal patterns of distribution and abundance. Potential competive interactions for food are considered to be the most important factor for explaining the observed ecological patterns. The polychaete species studied are divided into three trophic guilds: an omnivorous guild that feeds predaciously and as non‐selective deposit feeders, a surface feeding guild consisting of species usually considered to be selective surface deposit feeders, and a subsurface feeding guild usually considered as non‐selective infaunal deposit feeders. Within and between guild interactions are discussed.
Seasonal Divergence of Bosmina Morphs
Authors: Nilssen Jens Petter , Halvorsen Gunnar , Melåen Jan G. 
Published: February 2007

AbstractSeasonal occurrence and vertical distribution of two sympatric Bosmina morphs were investigated in two oligotrophic, deep fjord‐type lakes. Bosmina obtusirostris and B. lacustris displayed similar ecology, but B. obtusirostris exhibited more eggs per clutch. B. obtusirostris is probably the most viable of the two morphs when fish predation is relaxed, while B. lacustris exhibits an advantage with increasing fish and invertebrate predation. This has important consequences for habitat selection of the two morphs. B. obtusirostris and B. lacustris are most probably two phenotypes of a polymorphic species.
A Brine Seep at the East Flower Garden Bank, Northwestern Gulf of Mexico
Authors: Bright Thomas J. , Larock Paul A. , Lauer Ray D. , Brooks James M. 
Published: February 2007

AbstractDissolution of Triassic‐Jurassic, intrusive salt deposits within 150 m of the sea floor produces a hypersaline brine seep (∼200 0/00) at 71 m water depth on the East Flower Garden Bank. The anoxic, sulfide‐rich brine supports large populations of sulfur oxidizing bacteria. Toxic effects of the brine on surrounding epifauna, infauna and fishes are limited to the brine and a very narrow surrounding zone. Leafy algae, coralline algae, foraminifers, sponges, bryozoans, anemones, polychaetes, sipunculids, amphipods and pelecypods live on the hard substratum within 2 cm of the brine‐seawater interface. Sixty meters from the brine outflow, at dilutions of 50 to 1, the carbonate sand harbors polychaetes, ostracods, nematodes, amphipods, tanaidaceans, isopods, copepods, pelecypods and gastropods. Certain species of fish momentarily enter the brine and brine‐seawater mixtures.
Studies on the Primary Production of Phytoplankton in Suraha Lake (Ballia, India)
Authors: Singh Shree Ram , Swarup Krishna 
Published: February 2007

AbstractThe paper describes the seasonal variation in the rate of phytoplankton primary production in Suraha Lake – a large shallow water body – in relation to certain physico‐chemical parameters and the abundance and composition of the phytoplankton over a period of two years.
Chromatic Adaptation of the Planktonic Blue‐green Alga Oscillatoria redekei VAN GOOR and its Ecological Significance
Authors: Kohl Johannes‐Günter , Nicklisch Andreas 
Published: February 2007

AbstractNatural populations and culture strains of Oscillatoria redekei isolated from the same lakes exhibit a great variety of phycoerythrine/phycocyanine ratios even under the same growth conditions. Cytophotometric and spectrophotometric determinations of the phycoerythrine and phycocyanine contents of different strains after exposure to blue‐green and orange‐red light, respectively, suggested that chromatic adaptation of O. redekei takes place both at cellular and population level. This wide intraspecific diversity is considered at least one reason for competitiveness in highly eutrophic lakes.
Euglenophyta of Bangladesh. I. Genus Trachelomonas EHR.
Authors: Islam A. K. M. Nurul , Muniruzzaman Kh. 
Published: February 2007

AbstractA total of 55 taxa belonging to Trachelomonas (Euglenophyta) are reported from Bangladesh. Of these, 5 varieties (Tr. allorgei var. madaripurense, Tr. anguste‐ovata var. ellipsoidea, Tr. armata var. rangpurense, Tr. hispida var. subcoronata, Tr. asymmetrica var. crenulata) and one forma (Tr. anguste‐ovata fa. minor) are described as new to science.
Phosphorus and Nitrogen Budgets of Barton Broad and Predicted Effects of a Reduction in Nutrient Loading on Phytoplankton Biomass in Barton, Sutton and Stalham Broads, Norfolk, United Kingdom
Authors: Osborne P. L. 
Published: February 2007

AbstractBarton, Sutton and Stalham Broads are shallow, man‐made lakes formed in mediaeval times when peat excavations were flooded. Recently, a once diverse submerged macrophyte flora has, in most broads, been replaced by large phytoplankton populations. This change has been attributed to increased nutrient loadings. The seasonal cycles of chlorophyll α, nitrogen and phosphorus in the three broads are described and the inputs of nitrogen and phosphorus to Barton Broad are budgeted. A reduction in the phosphorus loading is recommended as the best method of restricting phytoplankton populations in these broads. An equation relating phosphorus loading, flushing rate, mean depth and retention coefficient to mean standing phosphorus concentration is used to predict the reduction in phosphorus loading required to limit phytoplankton populations and permit the re‐establishment of submerged macrophytes.
Reversibility of Man‐Induced Eutrophication. Experiences of a Lake Recovery Study in Sweden
Authors: Ryding Sven‐Olof 
Published: February 2007

AbstractRecovery of polluted lakes is a complicated process involving many factors. Different lake rehabilitation techniques and former experiences with advanced wastewater treatment and sewage diversion are reviewed. The response in water quality after a nutrient reduction may vary significantly, despite a lowering of the phosphorus concentration in the lake. The different factors influencing the process, such as climatic fluctuations, the growth‐limiting effect of nutrients and phosphorus release from the sediments, are discussed, based on examples from a lake recovery study in Sweden carried out in 30 lakes. Due to various interrelationships between physical characteristics and biological mechanisms involved, and to significant fluctuations in these factors from one year to the next, it is difficult to generalize and to forecast the actual response of a certain water body to a reduced nutrient input. Unfortunately, too many monitoring programmes aimed at elucidating the effects of remedial efforts are not designed in such a manner that relevant information can be obtained about the nutrient load — lake response relationships. Ways for optimizing and increasing the predictive power of inventory studies and monitoring programmes are discussed.
Light Climate and Metabolism of Nitella flexilis (L.) AG. In the Bottom Waters of Oligotrophic Lake Grane Langsø, Denmark
Authors: Nygaard Gunnar , Sand‐Jensen Kaj 
Published: February 2007

AbstractThe irradiance reaching Nitella at 11.5 m depths was almost the same during three years: 1000 cal cm−2 year−1 PAR, or 2.2% of the surface irradiance PAR. Green light (500–600 nm) constituted most (62–88%) of the irradiance on Nitella. Net photosynthesis by Nitella was linearly correlated to irradiance. Nitella had a positive oxygen balance from mid‐May to late September and a minor negative one at other times. The annual turnover of biomass was potentially high, and the dark‐respiration was very important in the metabolic balance. The contribution of Nitella to total autotrophic production and to oxygen conditions in the hypolimnion is discussed.
A Note on the Variability of the Diatom Cyclotella meneghiniana (KÜTZ.) after Isolation from the Natural Environment
Authors: Benndorf Jürgen , Egerer Gabriele 
Published: February 2007

AbstractA pure culture strain of Cyclotella meneghiniana (KÜTZ.) isolated from the hypereutrophic Bautzen reservoir (March 1980) developed from the typical Cyclotella‐shape to cells with an extremely prolonged pervalvar axis and a small diameter after five months growing under pure culture conditions. This change is interpreted as a consequence of the complete absence of grazing pressure as a selection factor. Since the cell surface/volume ratio showed a singificant increase (3.0) in comparison with the natural population (1.8), it is assumed that the culture strain has also changed with respect to physiological criteria. The conclusion is drawn that investigations of pure cultures for ecological purposes should be restricted to freshly isolated strains.
Losses of Total Phosphorus from Watersheds Influenced by Various Human Activity
Authors: Popovský Jiří 
Published: February 2007

AbstractIn territories without settlements, major livestock production or industry, and from territories devoted to row‐crop agriculture (diffuse pollution sources), the annual mean concentrations of total phosphorus compounds in waterways were found to be 17 to 43 μg · 1−1 P. Where there are point or hybrid pollution sources in watersheds, the annual average concentrations vary from 56 to 410 μg · 1−1 P. It was found that annual average total phosphorus concentration values obtained from three‐week sampling intervals can be used to show the presence of diffuse, hybrid and point pollution sources. The main sources of the high and permanent total phosphorus concentrations were densely populated areas, industrial works, agriculture, inadequately managed farms and disposal sites for solid and liquid wastes.
Factors Controlling the Seasonal Variation of Nitrate in Lake Erken
Authors: Boström Bengt 
Published: February 2007

AbstractThe seasonal variation of the nitrate concentration in the mesotrophic Lake Erken is markedly regular and shows some important differences compared with that of phosphate. Nitrification occurs mainly at the sediment surface. Nitrate accumulates when the nitrification‐denitrification sequence is broken at a time when the nitrate assimilation is small. This occurs in Lake Erken during autumn turnover.
Overwintering of Invertebrates in a Shallow Northern Swedish Lake
Authors: Danell Kjell 
Published: February 2007

AbstractDuring two winters, the benthic invertebrates in a shallow northern Swedish lake (66 °N) were studied. The lake is ice‐covered for about 200 days a year. Live Lamellibranchiata, Oligochaeta. Hydracarina, Isopoda, Heteroptera, Cole optera and Diptera were found in samples of ice and of frozen lake‐bottom sediments. During the winter in which the bottom froze deepest, a 70–90% decrease in numbers of live Chironomidae larvae was recorded between the autumn and following early spring.
A Microflow Respirometer for Measuring the Oxygen Consumption of Small Aquatic Organisms
Authors: Scharf Eva‐Maria , Oertzen Jöro‐Andreas Von , Scharf Walter , Stave Alfred 
Published: February 2007

AbstractA microrespiration device is decribed which uses a Clark electrode to measure the oxygen consumption or production of small and microscopic aquatic organisms in an open flow system. The construction and working principles of the device, which can measure oxygen consumptions as low as 0.5 nl · h−1, are described. The design of the apparatus permits parallel measurements under identical conditions with a single electrode. The device can be matched to various sizes of animal and oxygen consumption rates by means of specimen chambers of different volumes (6 μl, 35 μl, 140 μl) and a variable water flow rate. The microflow respiration device has been used successfully to measure the respiration of zooplankton and meiobenthos organisms as well as protozoans and has also been used successfully on board a research vessel.
Nitrogen Fixation in the Sediment of Shallow Lake Balaton, a Reservoir and Fishponds
Authors: Oláh J. , Abdel Moneim M. A. , Tóth L. 
Published: February 2007

AbstractFor the in situ measurement of nitrogen fixation in lake sediments, we developed a method which assures the rapid saturation with acetylene of the whole enzyme pool in the sediment and maintains near intact physical, chemical and biological environment at the water‐sediment interface. On the basis of seasonal measurements, the annual nitrogen fixation in the sediment was estimated in four types of shallow water ecosystem: the Keszthely Basin, Lake Balaton: 4.7 g N m−2; Körös backwater reservoir: 6.5 g N m−2; a polycultural fishpond: 0.49 g N m−2; and a liquid manure oxidation fishpond: 0.61 g N m−2. The amount of nitrogen fixed in the sediment of the Keszthely Basin was close to the fixation in the water column, while that fixed in the sediment of Körös backwater reservoir was considerably greater.A multiple regression analysis was made on the basis of synoptic studies on the vertical distribution of nitrogen fixation in the sediment, the pH, Eh, and concentrations of organic N, NH4‐N, NO3‐N, and NO2‐N in the interstitial water. The results indicate that nitrogen fixation is related to the dep, the NH4‐N concentration, and the redox potential. The vertical distribution of nitrogen fixation cannot be explained in every case by the densities and distributional patterns of the Azotobacter and Clostridium populations. No correlation was observed between nitrogen fixation and total organic‐C in lake sediment. A surprisingly close correlation was found between plankton primary production and the sedimentary nitrogen fixation in these lakes (r = 0.85, y = 4.5 X0.85). Short‐term (4 h) in vitro studies revealed a glucose mediated increase of nitrogen fixation, but there was no NH4‐N inhibition detected during this short incubation period.
Macrobenthic Communities of the Lower Chesapeake Bay. III. Southern Branch of the Elizabeth River
Authors: Hawthorne Steven D. , Dauer Daniel M. 
Published: February 2007

AbstractMacrobenthic invertebrates of an industrialized seaport ecosystem were studied seasonally from October, 1977 through July, 1978. Five stations were selected along the Southern Branch of the Elizabeth River, Virginia. The benthic community was dominated by eurytopic species that were not affected by minor to moderate stresses induced by man's activities in the seaport. Caution is required when benthic communities of the lower polyhaline to mesohaline zones of an estuary are used to indicate the effects of anthropomorphic alterations.
Ingestion Rates of Some Daphnia Species in a Shallow Lake (Lake Balaton, Hungary)
Authors: Zánkai Nóra P. 
Published: February 2007

AbstractFiltering rates of three species of Daphnia were studied in situ by the 14C technique during the summer in a lake with a water temperature of 20‐25°C (Lake Balaton, Hungary). The renewal time of gut contents proved to be 3‐5 min in each of the three species whether fed on natural or artificial food. From May to September, filtering rates of D. cucullata, D. hyalina and D. galeata averaged 7.8, 10.3 and 9.2 ml ind.−1 day−1, respectively. Identically long individuals of all three species had almost the same filtering rates in spring, whereas in summer animals of identical weights had similar filtering rates regardless of species because of the length variability of the helmets. The grazing rate of adult filter‐feeding crustaceans is suggested to be approximately 7 % per day.