bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Distribution of Perkinsus marinus in Gulf Coast Oysters: Its Relationship with Temperature, Reproduction, and Pollutant Body Burden
Authors: Wilson Elizabeth A. , Powell Eric N. , Craig M. Alison , Wade Terry L. , Brooks James M. 
Published: February 2007

AbstractOysters from 48 Gulf of Mexico sites were examined for presence and infection intensity of the endoparasite, Perkinsus (= Dermocystidium) marinus (Mackin, Owen and Collier, 1950) as part of NOAA's Status and Trends Mussel Watch Program. Prevalence exceeded 75% at 25 sites. Infection intensity did not vary with sex or reproductive stage. Latitude, total polynuclear aromatic hydrocarbon (PAH) content and industrial and agricultural land use significantly affected the parasite's distribution. PAH and pesticide concentrations were latitudinally dependent, suggesting an impact of spawning frequency on uptake and depuration. P. marinus analysis complements the use of pollutant body burden for determining change in environmental quality because it responds differently than pollutant body burden to the biology and ecology of the oyster.
Results to the Ecology of Endangered Species of Fish and Cyclostomes from Three Streams of Northern and Central Germany
Authors: Spiess Hans‐Jürgen , Waterstraat Arno 
Published: February 2007

AbstractResearch into endangered species of fish and cyclostomes, as well as their living environment, are prerequisite to determining species protection measures.Relevant ecological research was carried out in three streams in the trout and grayling region; the environmental conditions were recorded, and the populations characterised.Consequently the following suggestions for the protection of the streams dealt with in this research can be made.
Spatial and seasonal distribution of heterotrophic bacteria in pond water and sediments under different management practices
Authors: Jana B. B. , De U. K. 
Published: February 2007

AbstractPopulation densities and generation time of heterotrophic bacteria were estimated in water and sediments of fish ponds used for polyculture, monoculture and traditional systems of fish farming over a period of two and a half years. Spatial differences in microbial densities in the ponds were related to the organic loadings of the farm site and farm management. A number of environmental factors such as nitrogen, dissolved organic carbon, bicarbonate and phosphate of water were found to be responsible for the seasonal changes of heterotrophic bacteria in these ponds.
Immigration of Young Eels to the Skagerrak‐Kattegat Area 1900 to 1989
Authors: Hagstrom Olle , Wickström Håkan 
Published: February 2007

AbstractThe decline in recruitment of glass eels, elvers and young yellow eels to the Skagerrak‐Kattegat area in Sweden was demonstrated by catch data from trawl hauls at sea (IKMWT) and from eel ladders in two rivers emptying in the Kattegat. A long term decline since the 1940's was indicated and the same short term decrease as observed in other European countries during the 1980's was proved.
Observations on the Silver Eel Migrations of the Burrishoole River System, Ireland, 1959 to 1988
Authors: Poole W. Russell , Reynolds Julian D. , Moriarty Christopher 
Published: February 2007

AbstractThe eel migrations in Burrishoole, Ireland, have been studied from 1959 to 1988. Numbers of eels in the catches have decreased. The mean length of male eels has increased by 16.5% and females by 27.6%. Total weight of catch has not been affected by the drop in numbers. A change in sex ratio from 94.5 % males in 1962 to 37.5% in 1988 has also occurred. A decrease in elver recruitment into freshwater and a change in the environmental status of the system are discussed as being possible reasons for these changes.
A Proposal Regarding the Source of Nutrition of Leptocephalus Larvae
Authors: Westeberg Håkak 
Published: February 2007

AbstractThe large size, transparency and peculiar dental configuration of leptocephalus larvae can be interpreted as adaptations to a diet of large, transparent and soft food items. It is suggested that gelatinous zooplancton, in particular the discarded house of the Appendicularia or Larvacea, is their main food. Calculations show that an ingestion rate of the order of magnitude 10 houses/ hour is sufficient to sustain an eel larva.
Optimization of Weaning Elvers in a Closed Cycle System: Preliminary‐Results
Authors: Bronzi P. , Zaffignani P. 
Published: February 2007

AbstractReplicated tests to study the best combination of environmental conditions were carried out with a total of about 200 kg of glass eels of the Thyrrenian sea. Conditions tested were; stocking density, feed formulation, form of feed, grading frequency, cage and tank dimensions and protection of rearing units. Production and survival rates are reported, as well the size — class distribution at the beginning and at the end of the rearing period and the component chart of percentages of different size classes.
Short Note on a Culture Experiment on Monthly Captured Glass Eels from the Rio Minho, Portugal
Authors: Weber Michael , Antunes José Carlos 
Published: February 2007

AbstractA recycling system combining biofiltration and hydroponics was used for rearing glass eels. Growth rates varied between 0.1 and 1.4% of body weight per feeding day. A large range of mortalities (9.4—93 %) after two months was mainly due to ectoparasitic infections.
Interrelations between Microcystis and Cladocera in the highly Eutrophic Lake Kasumigaura, Japan
Authors: Hanazato Takayuki 
Published: February 2007

AbstractThe zooplankton community in the highly eutrophic Lake Kasumigaura was investigated and its relation to a bloom of Microcystis was analyzed. The zooplankton community was dominated by small cladocerans, whose biomass and production became highest in summer, when Microcystis bloomed. The high cladoceran production is considered to depend on the production of colonial Microcystis, because the production of nannoplankton was apparently too low to ensure the cladoceran production. Microcystis cells were unsuitable as food for the cladocerans inhabiting Lake Kasumigaura, but became utilizable when decomposed. Decomposed Microcystis may be the main food for Cladocera in the lake in summer. High water temperatures occurring in summer probably promoted decomposition of the Microcystis, leading to increased production of the small cladocerans.
Strain‐specific Influence of Microcystis Aeruginosa on Food Ingestion and Assimilation of some Cladocerans and Copepods
Authors: Henning Manfred , Hertel Heino , Wall Henry , Kohl Johannes‐Günter 
Published: February 2007

AbstractIngestion rates where estimated for daphnids, Cyclops spp. and Bosmina (Eubosmina) coregoni thersites fed hepatotoxic and non‐toxic M. aeruginosa either separate or mixed with the readily available food alga Ankistrodesmus falcatus. The ingestion rates of hepatotoxic strains of M. aeruginosa are very low compared with those of A. falcatus or non‐toxic M. aeruginosa HUB 5‐3 fed to Daphnia magna or D. longispina. However, a close relationship between ingestion rate of different M. aeruginosa strains and their toxicity could not be observed. Addition of the toxic strain M. aeruginosa HUB 5‐2‐4 reduces the ingestion rates of A. falcatus progressively due to increased food rejection by D. magna. Additionally, the assimilation efficiency of M. aeruginosa HUB 5‐2‐4 is two times lower compared with A. falcatus and M. aeruginosa HUB 5‐3 leading to strong starvation.
The Influence of Extracellular Algal Products on the Surface Tension of Water
Authors: Nägeli Astrid , Schanz Ferdinand 
Published: February 2007

AbstractBy means of laboratory experiments and field investigations in Lake Zürich, the influence of extracellular algal products on the surface tension of water was investigated. Of interest to us was the question of whether a reduction in the surface tension, i.e. surface pressure, is dependent on (i) algal species or phytoplankton and phytoneuston community, (ii) the growth phase of the species or community concerned, and (iii) the abundance or concentration of phytoplankton and phytoneuston biomass. A dependence was ascertained in the case of the first two points. The laboratory experiments showed that extracellular products originating from diatoms give rise to a distinctly higher surface pressure than those originating from green and blue‐green algae; and that the change in surface pressure occurs during the later part of the stationary algal growth phase. In Lake Zürich, high values of surface pressure were measured at the time of the collapse of the diatom bloom, and comparatively low values during the period of dominance of the blue‐green alga Oscillatoria rubescens in the winter months. Changes in surface pressure established during the course of a year can thus be explained partly in terms of the phytoplankton and phytoneuston succession.
Besonderheiten bei der Ermittlung der Primärproduktion in der Elbe aus Sauerstoff‐Ganglinien. Some Particularities in Estimating Primary Productivity in the River Elbe Using Oxygen Time Curves
Authors: Böhme Michael 
Published: February 2007

AbstractThe phytoplanktonic primary production was estimated in the River Elbe (average flow 325 m3/s) byODUM's twin and single curve analysis of changes in the oxygen content (1‐ and 2‐ SGA). The results were affected by the severe and varying waste water load and the non‐uniform conditions along the upstream river stretch.It is shown how the gross primary productivity was corrected by using the photosynthesis‐light‐relationship. At favourable measuring sites, single curve analysis gives similar values asODUM's twin curve method. But they scatter more when applied to establish the photsynthesis‐light‐relationship.
Characterization of Brackish Coastal Waters of Different Trophic Levels by Means of Phytoplankton Biomass and Primary Production
Authors: Wasmund Norbert , Kell Volkbert 
Published: February 2007

AbstractInvestigations on phytoplankton have been carried out in Baltic coastal waters, which are widely separated from the sea. Corresponding to their distance to the sea they differ in their trophic level. Annual phytoplankton production and a mean biovolume of 100‐200 g C · m−2 and 2‐10 mm−3 · 1−1 respectively were found for the mesotrophic level, of 200‐400 g C · m−2 and 10‐20 mm3 · 1−1 for the eutrophic level, and of 400‐600 g C · m−2 and over 20 mm3 · 1−1 for the polytrophic level.In the course of nearly two decades of investigation a slight increase of phytoplankton biovolume, but no increase of primary production was recorded. Some changes in species composition are to be recognized in Greifswalder Bodden, if old literature is compared with recent data. In the Darss‐Zingst boddens a shift from Cyanobacteria dominance towards Chlorophyceae dominance has appeared for at least 5 years. This was on account of the disappearance of Gomphosphaeria pusilla, which is thought to be an indicator species of the mesotrophic level.
Influence of Eutrophication on Bacteria in Two Fjords of the Western Baltic
Authors: Gocke Klaus , Rheinheimer Gerhard 
Published: February 2007

AbstractLongitudinal transects in the Schlei Fjord (Kiel Bight) revealed strong increases of microbiological parameters from the entrance towards the landlocked end of the fjord. In the inner part up to 14 × 106 bacteria ml−1 (microscopical count), 77 × 10−1 saprophytic bacteria ml−1 (plate count) and a thymidine incorporation rate of 0.436 nmol 1−1 h−1 were observed. The data were compared with earlier results from the same system and those from the nearby located Kiel Fjord. The observations indicate a very high degree of eutrophication in the Schlei Fjord and a lesser one in the Kiel Fjord. The significance of total bacterial numbers and numbers of saprophytic bacteria as indicators for eutrophication and contamination is discussed.
Seasonal Variation in the Biomass of Zooplankton in Two Shallow Coastal Water Inlets Differing in their Stage of Eutrophication
Authors: Heerkloss R. , Schnese W. , Adamkiewicz‐Chojnacka B. 
Published: February 2007

AbstractThe seasonal zooplankton dynamics of two coastal water inlets differing in their stage of eutrophication are compared. There are no clear differences between the two waters with respect to calanoid copepods, but they differ appreciably in terms of rotifer biomass. In the more eutrophic water the latter show a pronounced mass development in July which is absent in the less eutrophic water. It is concluded that bacterio‐detritivorous rotifer species are an important regulative factor of the ecosystem which compensates for productivity increases by intensifying heterotrophic destruction.
Autotrophic Picoplankton in Freshwater Ecosystems: The View from the Summit
Authors: Stockner John G. 
Published: February 2007

AbstractA brief overview of the state‐of‐the‐art of freshwater autotrophic picoplankton (APP) is given as an introduction to this special issue of Internationale Revue der gesamten Hydrobiologie. Some questions that have arisen from research over the past decade are re‐evaluated in light of new information reported here. These include: 1.) what is the average abundance of autotrophic picoplankters along a nutrient gradient in freshwater?; 2.) how diverse and what are the major components of the APP community in freshwater?; 3.) what is the origin of colonial forms of picoplankton?; 4.) what is the significance of prokaryotic and eukaryotic picoplankton in pelagic systems?; and 5.) how important is grazing in APP population regulation? New questions are proposed and an outlook for possible future research is offered.“Creating a theory … is rather like climbing a mountain, gaining new and wider views, discovering unexpected connections between our starting point and its rich environment. But the point from which we started still exists and can be seen, although it appears smaller and forms a tiny part of our broad view gained by mastery of the obstacles on our adventurous way up”
Determination of Eubacterial and Cyanobacterial Size and Number in Lake Baikal Using Epifluorescence
Authors: Boraas Martin E. , Bolgrien David W. , Holen Dale A. 
Published: February 2007

AbstractChroococcoid cyanobacteria, (mean size = 0.79 μm, likely Synchetocystis limnetica Popovsk) and total eubacteria (mean size = 0.33 μm), from Lake Baikal, USSR, were enumerated using epifluorescence microscopy and sized with image analysis. Bacterial densities ranged from 0.44 · 106 cells ml−1 at 250 m to 2.3 · 106 cells ml−1 at the surface. Mean eubacterial abundance was 1.3 · 106 cells ml−1. Cyanobacterial densities were more variable, ranging from 0.42 · 104 cells ml−1 at 250 m to 9.8 · 104 cells ml−1 at the surface, with a mean abundance of 2.7 · 104 cells ml−1. The cyanobacteria, in particular, occurred in clusters resembling “marine snow”. Our results indicate that Lake Baikal picoplankton size and density are similar to other large lakes but may have a more diverse community structure than in other large oligotrophic lakes.
Seasonal Changes in Chlorophyll‐containing Picoplankton Populations of Ten Lakes in Northern England
Authors: Hawley G. R. W. , Whitton B. A. 
Published: February 2007

AbstractKey features of photosynthetic picoplankton populations were compared during 1988 in ten lakes in northern England ranging from oligotrophic to slightly eutrophic; two of the three eutrophic lakes were shallow and lacked a thermocline. Measurements were made at 0.5 m depth of temperature, total chlorophyll a, chlorophyll‐containing picoplankton cell density, mean picoplankton cell volume and percentage of phycoerythrin‐rich cells in the total picoplankton population. All lakes showed maxima for total chlorophyll concentration and picoplankton cell density in mid‐ to late summer. The maximum value for picoplankton density ranged from 3.4 × 103 (Esthwaite Water) to 1.3 × 106 cells ml−1 (Ennerdale Water).There was a significant negative relationship (p < 0.05) between log10 of maximum picoplankton cell density and maximum total chlorophyll, the latter being taken as an indicator of lake trophic status. The ratio of maximum to minimum picoplankton density during the year in a particular lake ranged from 39 to 2360 and showed no obvious relationship to lake type. Overall, the seasonal range in picoplankton density was about one order of magnitude greater than the range in total chlorophyll a, but there were considerable differences between lakes.Phycoerythrin‐rich picoplankton as a percentage of total picoplankton reached a maximum in summer in all lakes. Values were always very low (<5%) in the two shallow eutrophic lakes, but reached 97% and over in the four most oligotrophic lakes. In two of the oligotrophic lakes, Wast‐water and Ennerdale Water, phycoerythrin‐rich picoplankton was a major component of the summer phytoplankton biomass.
Occurrence, Dynamics and Production of Picoplankton in Hungarian Shallow Lakes
Authors: Vörös Lajos , Gulyás Pál , Németh József 
Published: February 2007

AbstractPhototrophic picoplankton were detected in 105‐106 cells/ml concentrations in seven water bodies of differing chemistry and trophic level. Dominant picoplankters were, at all sites, coccoid cyanobacteria of 0.8‐1.2 μm dimensions, exhibiting red or yellow autofluorescence. Apart from the effects of water temperature their quantitative dynamics were significantly influenced by the nitrogen supply and the herbivorous zooplankton (Cladocera). Their maximum contribution to the total planktonic primary production was about 50%, both in mesotrophic and hypereutrophic environments. However during the bloom of filamentous nitrogen‐fixing blue‐greens their role became negligible. In phytoplankton communities the significance of picoplankton is overestimated several times, when based on the cell count, while it is underestimated on the basis of biomass. The most useful characteristics of phytoplankton size groups was the total surface area of their cells.
Carbon‐14 Uptake by Picoplankton and Total Phytoplankton in Eight New Zealand Lakes
Authors: Petersen Richard 
Published: February 2007

AbstractEight New Zealand lakes were surveyed for 14C uptake by phytoplankton as a function of light intensity. The results support the view that the photosynthetic picoplankton is an important contributor to primary productivity in oligotrophic lakes but is relatively unimportant in more eutrophic lakes. A comparison of carbon uptake vs. light intensity characteristics (P vs. I) of the picoplankton size class vs. that of the total phytoplankton community supports the view that the picoplankton size class may be adapted to utilization of dimmer light.
Diel Division Cycle and Growth Rates of Synechococcus in Lakes Huron and Michigan1
Authors: Fahnenstiel Gary L. , Patton Tyrone R. , Carrick Hunter J. , McCormick Michael J. 
Published: February 2007

AbstractA clone of Synechococcus isolated from Lake Huron and natural populations of Synechococcus from lakes Huron and Michigan were studied in 1989 to examine the diel division cycle and to provide estimates of the in situ growth rate based on the frequency of dividing cells (FDC) method. Cultured populations of Synechococcus exhibited a consistent diel division pattern with a midday/afternoon (1100–1800 h) peak in the percent of dividing cells. The maximum percent of dividing cells varied among cultures (8‐27%) and was related to the growth rate. A small fraction of dividing cells (3‐5%) remained throughout the dark period, suggesting that some cells were arrested in the doublet stage prior to division. The duration of division (td) ranged from 2.6‐4.9 h, with a 3.7 h mean for cultures with growth rates ≥0.34 d−1 but increased to 8 h at a lower growth rate of 0.20 d−1.The diel division pattern for natural populations was very similar to the laboratory clone; an afternoon peak (1400‐2100 h) in dividing cells and a small fraction of dividing cells (2‐5%) remained during the dark period. The maximum percent of dividing cells for natural populations ranged from 6‐10%. In situ growth rates, determined from the FDC and assuming a constant td of 3.7 h, ranged from 0.30‐0.42 d−1. The FDC method may provide accurate estimates of in situ growth, particularly in environments where the growth rate is >0.34 d−1, but in lakes Huron and Michigan where growth rates can be lower and td values may increase, FDC‐growth rates must be viewed with caution.
The Nitrogen Cycle in Lough Neagh, N. Ireland 1975 to 1987
Authors: Gibson C. E. , Smith R. V. , Stewart D. A. 
Published: February 2007

AbstractResults from thirteen years of weekly observations are presented on the nitrogen cycle in Lough Neagh. The data comprised catchment and atmospheric inputs, output via the outflow and calculated losses by sedimentation and denitrification. Nitrate‐nitrogen in the rivers is the dominant input fraction and the nitrate loading has increased over the period observed. 52 % of the input N sediments to the lake bottom, but 65 % of this is lost by denitrification. In spite of increasing nitrogen inputs, the summer soluble nitrate concentrations have decreased due to uptake by a perpetual crop of the cyanobacterium Oscillatoria agardhii GOMONT.
Growth of Bream, Abramis brama L., in Two Outside Basins of Different Trophic State of Lake Balaton
Authors: Dauba Francis , Biró Péter 
Published: February 2007

AbstractAge‐composition, size‐distribution, length/weight relationships and growth both in length and weight of bream stocks were studied on fishes collected in NE and SW basins of Lake Balaton during 1982/83. Stocks consisting of 10 to 12 age‐groups were observed at the two lake areas. The linear growth and weight‐gain in the SW‐basin were annually faster than in the NE‐basin, however, the growth of bream in Lake Balaton was slow as compared to that observed 10 years ago. Parallel with progressive eutrophication, the density of bream stocks increased by some 5–10 % especially at hypertrophic lake areas (SW) and consequently their growth was transformed to densitydependent. In the appearance of strong year‐classes some cyclicism could be observed especially in the SW‐basin.
Zu den Ursachen der unterschiedlichen pH‐Empfindlichkeit von Gammarus pulex L., G. fossarum KOCH (Amphipoda) und Aselus aquaticus L. (Isopoda)
Authors: Rupprecht Rainer 
Published: February 2007

AbstractBy means of ion chromatography the extensive and significantly higher loss of ions of G. pulex and G. fossarum in acid water (pH 3.0) as compared to neutral water is proved. While cations are being accumulated in the water, some ions (Na+, Cl−) leave the hemolymph in important percentage, others increase highly after being set free from the cells (K+ and Ca2+). The loss of cations with Asellus aquaticus in acid water (pH 3) is clearly lower than with Gammarus, and it is not significantly higher than when the animals are put into neutral water.
Herbivores and the Spatial Distributions of the Phytoplankton III. Estimating the Number of Good Foraging Places
Authors: Wirick Creighton D. 
Published: February 2007

AbstractDuring critical periods, the survival of a herbivorous zooplankter or ichthyoplankter may depend upon the animal encountering food in excess of a critical concentration. During such times, the value of the animal's habitat is related to the relative number of places where food exceeds the critical concentration. CHEBYSHEV'S mathematical inequality gives a nonparametric upper bound for the probability that a place selected at random from a habitat will contain such excess food. The probability is proportional to the sum of the variance and mean squared of the food distribution, which is also a measure of the habitat's value to the animal.