bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biological Studies of the Pearl Spot Etroplus suratensis (Pisces, Cichlidae) from three Different Habitats in Sri Lanka
Authors: Costa H. H. 
Published: February 2007

AbstractThe morphometry, feeding habits and reproductive biology of Etroplus suratensis, an indigenous cichlid food fish, were studied for a period of one year on specimens from three different habitats in Sri Lanka. The morphometric studies implied that the length weight relationships are curvilinear. Macrophytic fragments formed the most important component of food, although detritus, diatoms, and animal matter are also ingested. First sexual maturity is attained in the length ranges 8.0‐9.0 cm in females from brackish water habitats. Fecundity ranged from 700‐3900 eggs in mature specimens. The wide range of the gonadosomatic index suggests that spawning occurs several times during the year.
A Study on the Macro‐Zoobenthos and the Physico‐chemical Characteristics of the Bottom of Bakhira Lake, Uttar Pradesh, India
Authors: Pandey K. , Shyam Radhey , Prasad Sant , Chaudhry H. S. 
Published: February 2007

AbstractBakhira Lake is the largest man‐made lake of Eastern Uttar Pradesh. It is utilized for Boro (coarse paddy) cultivation, irrigation and fishing by poor village farmers. Hydrographical features, qualitative and quantitative composition of the macro‐zoobenthos, and the physico‐chemical characteristics of the bottom water and sediment were studied from October 1976 to April 1977.Molluscs, insects, ostracods, annelids, nematodes and crustaceans are the main groups of zoobenthos. Molluscs together with insects dominate the benthic fauna (95.2 to 96.4% of numbers). The benthic density varied from 273 to 517 individuals/m2. Average density of macro‐zoobenthos is more or less inversely related to the total alkalinity of the bottom water. Molluscs showed a positive correlation to temperature and a negative correlation to insect density.
How Currents on Different Sides of Substrates in Streams Affect Mechanisms of Benthic Algal Accumulation
Authors: Stevenson R. Jan 
Published: February 2007

AbstractBenthic diatom accumulation rates and diversity were monitored for 32 days in five habitats where current conditions were different. After 32 days, diatom abundance in a sheltered habitat where eddies occurred over substrates was over eight times the abundance in a habitat that was exposed directly to the main flow of the stream (about 30 cm/sec). Diatom immigration rates and species richness of diatom taxocenes were negatively related to exposure; whereas, diatom reproduction rates, death rates and relative abundances of the eight dominant diatom species were not related to the small differences in current velocity that occurred. During the 32‐day colonization period diatom immigration rates increased, species richness of diatom taxocenes increased and evenness of species abundances decreased. Species composition of diatom taxocenes shifted from a numerical dominance by fast immigrators to dominance by fast reproducers during the 32‐day colonization.
Interactions between Light Situation, Depth of Mixing and Phytoplankton Growth during the Spring Period of Full Circulation
Authors: Horn Heidemarie , Paul Lothar 
Published: February 2007

AbstractInvestigations lasting several years at the artificial Lake Saidenbach have shown that, due to the poor light situation expressed in terms of average daily radiation (Riley 1957), mean daily exposure (Reynolds 1973), extinction depth and the ratio zmis/zeu, no mass development of the phytoplankton should actually occur during the spring complete circulation. In practice, however, the period of complete circulation of the water in spring is not only a prerequisite for, but often also the factor causing, the mass development (usually Asterionella formosa). The poor light situation and the fact that the vertical phytoplankton profile shows significant differences between the plankton concentrations at different depths indicate that the spring complete circulation does not represent a complete recirculation, and thus mixing, of the water down to the bottom but involves only episodic and local partial recirculations interspersed with periods of relatively slight turbulence. The actual mixing depth during this period of complete circulation is therefore obviously less than the mean depth of the water concerned, which is commonly assumed to equal. This permits the algae in the upper layers to grow. Respiratory losses of the phytoplankton at greater depths probably remain slight due to their adaptation to low light intensities in winter.
Development and Use of an Aquatic Micro‐Ecosystem as a Test System for Toxic Substances. Properties of an Aquatic Micro‐Ecosystem IV
Authors: Kersting Kees 
Published: February 2007

AbstractExperiments were performed using several modifications of a micro‐ecosystem made up of three subsystems connected by a unidirectional flow of recirculating water. The three subsystems represent roughly the trophic levels of autotrophs (algae), herbivores (Daphnia magna), and decomposers (sandfilter with bacteria). The particle concentration was determined weekly, using a Coulter Counter, and the Daphnia population was counted. At regular intervals, the species composition of the algae was determined. The changes in the algal concentration and Daphnia population are described, and the different modifications are discussed.In several micro‐ecosystems, the herbicide dichlobenil was introduced once or several times, and in one micro‐ecosystem, the herbicide diuron was added. The response of the micro‐ecosystems is discussed. For the periods without a toxic substance present, a normal operating range is suggested in relation to which the response of the systems to the introduced herbicide is discussed.Besides the separate analysis of the data, the algal concentrations and the Daphnia numbers were correlated to each other. This was done by regression analysis and according to a dynamic system approach. In both cases, the effect of herbicides was better discerned than in the separate analysis of the data. In the dynamic systems approach, a normalized ecosystem strain was defined as a parameter to measure effects of stress on the ecosystem level.
Comparison of Plankton‐Water Chemistry Relationships in Three Acid Stressed Lakes in Nova Scotia, Canada
Authors: Blouin Anthony C. , Lane Patricia A. , Collins Terrance M. , Kerekes Joseph J. 
Published: February 2007

AbstractA field program was conducted in 1980 and 1981 on three lakes in Kejimkujik National Park, Nova Scotia, to study plankton‐water chemistry relationships in a region of potential acid precipitation stress. Among lake and between year comparisons were made.The three study sites represent two different types of lakes. Kejimkujik Lake (pH 4.8) and Pebbleloggitch Lake (pH 4.5) are both high‐colored, dystrophic acid lakes. Beaverskin Lake is a clear, oligotrophic lake which is not as acidic (pH 5.4).The phytoplankton of Kejimkujik Lake was dominated by diatoms, while Pebbleloggitch Lake was dominated by chlorophytes and chrysophytes, and Beaverskin Lake was dominated by cyanophytes. Kejimkujik Lake had the highest total algal cell volume per liter, and Pebbleloggitch Lake the lowest.Rotifer populations composed the majority of the zooplankton communities, while the crustacean zooplankton were dominated by the acid‐tolerant copepod Diaptomus minutus. Kejimkujik Lake had the lowest zooplankton biomass and Pebbleloggitch Lake the highest zooplankton biomass per m3. A pattern of highest algal density in Beaverskin Lake, but highest zooplankton density in Pebbleloggitch Lake emerged in both years. This is likely an effect of abundant, but unsuitable food (blue‐green algae) in Beaverskin Lake and important detrital food resources in Pebbleloggitch Lake in both years.Multiple regression analysis of water chemistry variables with plankton species produced many significant effects, but failed to show clear patterns. Cause and effect relationships in aquatic ecosystems are poorly delineated by such techniques.
Composition and Productivity of the Benthic Macroinvertebrate Community of a Subtropical Reservoir
Authors: McCullough Jack D. , Jackson Douglas W. 
Published: February 2007

AbstractPhysical‐chemical conditions, phytoplankton productivity, community structure and productivity of the macroinvertebrate benthic community were determined during 1976–77 in a subtropical reservoir. Physical‐chemical results revealed high nitrate and phosphate concentrations with highest values in the riverine segment. Large phytoplankton populations were present during most of the year. Phytoplankton productivity was high, producing an annual mean of 87 mg C · m−3 · h−1 (12 hours light day). High turbidity in the riverine segment limited phytoplankton productivity during winter and spring. Macrobenthos was dominated by chironomids (Chironomus, Procladius, Coelotanypus and Tanypus) and oligochaetes (Limnodrilus). The annual mean benthic population was estimated at 1,626 · m−2 with a mean dry weight of 0.66 g · m−2. Mean benthic species diversity was 1.80. A lacustrine‐riverine community gradient was revealed. Benthic productivity was 6.8 g · m−2 · yr−1 (dry weight) with a P: B ratio of 10. A low correlation was observed between benthic and phytoplankton productivity, and between phytoplankton standing crop and benthic macroinvertebrate numbers throughout the reservoir. Algal food supplies had little impact on the benthic community which was composed predominately of species which fed mostly on organic detritus. Stressful conditions caused by low dissolved oxygen concentrations probably inhibited development of the benthic community throughout the reservoir during summer months, while high sedimentation rates limited development in the head waters.
The Effects of Hydraulic Dredging to Control Oyster Drills on Benthic Macrofauna of Oyster Grounds in Delaware Bay, New Jersey
Authors: Ismail Naim S. 
Published: February 2007

AbstractThis study describes the extent and nature of the effects of hydraulic dredging to control oyster drills (Urosalpinx cinerea and Eupleura caudata, Family Muricidae, Order Neogastropoda) on benthic macrofauna and sediments of the oyster grounds in Delaware Bay, New Jersey. The immediate effects of hydraulic dredging were reductions in numbers of species as well as in total numbers of animals on the three oyster grounds selected. However, oyster drills were most affected. Benthic populations have recovered three to ten months after dredging. The sediments of the dredged grounds can be described as muddy sands. Immediately after dredging, additional mud was brought up from subsurface layers which reduced the median grain size on Ground 154 test plot. On Ground 515 test plot, however, there was a slight loss in the mud which increased the median grain size.
Competition and Population Time Lags in Bosmina (Cladocera, Crustacea)
Authors: Matveev Vladimir 
Published: February 2007

AbstractThe competition between Bosmina coregoni and B. longirostris was studied by culturing of mixed and isolated populations in lake water. While interaction was detectable between the two species, they were capable of coexisting for at least 124 days. The pattern of predominance was found to depend on initial frequencies. The ratio of B. coregoni to B. longirostris in the pelagic zone of a mesotrophic lake could be explained on the basis of competition between either species. Birth, death, and population growth rates proved to be delayed functions of stock density, as was borne out by cross‐correlation analysis of experimental population dynamics. Time lag estimates for all three rates varied for different phases of population oscillation. For accurate assessment of time lags, the phases of monotonous changes in density should have been separated from one another. The time lag estimated for the rate of population growth in mixed cultures was significantly higher for the superior competitor (B. coregoni). This estimate may well be predicted as an arithmetic mean value cf time lag estimates for birth and death rates. The duration of population growth (or decline) was correlated to the time lag of the death rate, whereas the amplitude was not correlated to any time lag at all.
Influence de la spéciation du cuivre sur les populations phytoplanctoniques naturelles de la rivière du Saguenay, Québec, Canada Influence of Copper in Various Forms on Natural Phytoplanktonic Populations from the Saguenay River, Quebec, Canada
Authors: Thompson Patsy‐Ann , Cǒté Raynold 
Published: February 2007

AbstractIn 1981, experiments to study the toxicity of copper in its ionic, complexed (to humic acid) and adsorbed (on cellulose fibers from a local paper mill) forms on species composition, standing crop, and photosynthesis of phytoplankton were conducted in chemostats with natural aggregations composed mainly of either green algae or of diatoms from the Saguenay River. In the aggregations of green algae, the rates of primary production were more strongly inhibited by copper than were the chlorophyll a concentrations, whereas the cell numbers, standing crop and rates of primary production of the diatoms were all strongly inhibited by copper.
Application of Videomicroscopy to the Study of Interstitial Fauna
Authors: Farris Richard A. , O'Leary Daniel J. 
Published: February 2007

AbstractThis paper deals with a method of employing videomicroscopy in the study of meiofauna. The apparatus is inexpensive, easy to use, and offers a high degree of resolution. Accurate measurements of the specimen can be made directly from the video monitor screen. With the addition of a videocassette recorder, live footage can be recorded for analysis, correspondence, or as an aid in teaching.
A Comparison of the Zooplankton in Two Newfoundland Bays with Differing Influences from Major Currents
Authors: Davis Charles C. 
Published: February 2007

AbstractQuantitative zooplankton samples were obtained at four regular stations and one irregular station in Placentia Bay, Newfoundland between mid June 1974 and mid May 1976. Sampling was attempted fortnightly as regularly as weather conditions and competition from other ship users would allow. The results are compared with those obtained and previously published in a similar study from Conception Bay, Newfoundland in 1977 to 1978. There was a greater diversity of species in Placentia Bay, and for most species the numbers/m3 were greater. The two bays are influenced by somewhat different current systems, and climatic conditions are a little milder and foggier in Placentia Bay. The same species were common in both bays, with copepods usually being the most important.Among copepods, two of the most important species namely Pseudocalanus sp. and Oithona similis were less abundant in Placentia Bay, but this was offset by a greater abundance of Temora longicornis.A few of the problems that require further investigation are outlined.
Estimation des paramètres fondamentaux de la dynamique d'un estuaire à marées. On the Dynamics of a Tidal Estuary: Estimation of the Principal Factors
Authors: Douvillé Jean‐Luc , Riaux Catherine 
Published: February 2007

AbstractIn order to obtain a better understanding on the relationship between salt and fresh‐water masses in an estuary on the Northern Brittany coast, a study on the tidal dynamics has been carried out. A simple model for the calculation of the mean current velocities is proposed taking into account the estuarine topography, tidal parameters and river discharge. The model also estimates the Richardson, Froude and Reynolds estuarine numbers. These can be used in further studies on the particle transport in this estuary.
Field and Laboratory Studies on Nile Phytoplankton in Egypt. II. Phytoplankton
Authors: Ahmed Ahmed M. , Mohammed Ahmed A. , Heikal Medhat M. , Zidan Mohammed A. 
Published: February 2007

AbstractVariations in chlorophyll a concentration and in qualitative and quantitative counts of Nile phytoplankton were followed at Assiut from September 1980 to September 1982. Chlorophyll a concentrations usually correlated well with phytoplankton density. The total phytoplankton exhibited higher counts in spring and summer than in autumn and winter. While diatoms exhibited the highest counts, green algae contributed more genera to the phytoplankton community.
Influence de quelques paramètres du milieu d'incubation sur la survie d'alevins de saumon atlantique, Salmo salar L., en ruisseau expérimental. Influence of some Environmental Parameters upon Survival during Embryonic Development of Atlantic salmon, Salmo solar L., in an Experimental Stream Channel
Authors: Marty Claude , Beall Edward , Parot Giles 
Published: February 2007

AbstractThe effect of some environmental parameters of the redd (substrate composition, interstitial dissolved oxygen concentration) upon survival of Atlantic salmon embryos was studied in a large artificial stream channel. Batches of 3000 eyed eggs were buried 0.25 m deep in the gravel substrate of 8 different channel sections, where natural or artificial sediment deposition took place. Upon emergence, fry were captured in drift nets or by electrofishing. Survival varied from 32 to 94 % in the different sections. It was strongly affected by volume of sediment less than 10 mm in particle size and more particularly by the fraction less than 0.2 mm, the main component of natural sediment deposition. Survival was less strongly determined by oxygen concentration variations except for values less than 2 mg/l obtained in the section with highest sediment deposition. Available volume of interstitial void space appeared to be crucial for good survival during larval development.
Bacterial Activity in a Reservoir Determined by Autoradiography and its Relationships to Phyto‐ and Zooplankton
Authors: Šimek Karel 
Published: February 2007

AbstractIn the drinking water reservoir Římov (Southern Bohemia) bacterioplankton was studied during 1983. Special attention was given to the relationships between parameters of bacterial abundance, total and individual activity. Bacterial counts and biomass was assessed and autoradiographic determinations of the proportion of active bacteria incorporating thymidine (Th) and mixture of amino acids (AA) and total uptake rate of AA were made over a year in the surface layer and during summer stratification from the thermocline and 15 m depth. Specific activity of metabolically active bacteria (SAMAB) and specific activity per unit of biomass (SAUB) were negatively correlated with counts of metabolizing cells and with bacterial biomass, respectively. Total and individual heterotrophic activity and counts of bacteria coincided with the changes of phytoplankton biomass, whereas bacteria incorporating Th were more tightly correlated with primary production. The most significant relation of metabolically active bacteria was found to cladoceran biomass. Thus, this part of heterotrophic bacterial activity seems to be stimulated by leakage of dissolved organic matter from phytoplankton being disrupted and incompletely digested by cladocerans rather than from healthy photosynthetizing cells.
Investigation into Seasonal Growth of Branchiostoma lanceolatum off Heligoland, According to Data by Courtney (1975)
Authors: Sager Günther , Gosselck Fritz 
Published: February 2007

AbstractValues of length growth of Branchiostoma lanceolatum off Heligoland were gained in 1962–63 by COURTNEY (1975a, b) over six age groups comprising about 800 individuals. Growth, generally was found to stop when sea water temperatures fell below 10 °C. Stagnation for at least six months could be observed as a result. COURTNEY gave a graph for length development in consecutive age groups by connecting clusters of points by straight lines, for lack of more adequate methods not available at that time.In a review, tests are recalled for the mathematical representation of growth with seasonal variations. Initial work was done by URSIN (1963), followed by CLOERN and NICHOLS (1978). These authors tried to introduce temperature to the PÜTTER/BERTALANFFY function of length growth, in a direct or indirect way. SAGER (1982) extended this idea regardless of the growth function proper. In a first step, the modification holds for seasonally restricted growth just down to momentary stagnation (SAGER, 1983a, b). The second step (SAGER, 1984a) allows for stagnation over several months and is suitable for approximation of the COURTNEY values, which is performed by nonlinear regression.Results show fully satisfying coincidence, as manifested in numerical and graphical displays. Moreover, the growth rate or growth velocity has been calculated and is plotted graphically. Complete description of growth development, according to the COURTNEY samples, has been achieved by a function with only five parameters.
Modifications of the Ekman Sampler
Authors: Håkanson Lars 
Published: February 2007

AbstractMany types of sediment samplers have been designed for specific purposes and for sampling in different aquatic environments. The objective of this technical note has been to introduce two specific improvements of the traditional Ekman grab sampler, which is a well‐known apparatus for sampling of soft sediments, especially in bottom faunistic contexts. The two new modifications concern the automatic closing mechanism. The jointed quadrant and the jointed, hooked axis, both made of brass, provide a much handier and more reliable operation than, e.g., the traditional automatic mechanism.
Community Metabolism in Tropical Undrainable Rural Fish Ponds
Authors: Oláh J. , Sinha V. R. P. , Ayyappan S. , Purushothaman C. S. , Radheyshayam S. 
Published: February 2007

AbstractThe process of community metabolism including primary production and community respiration in eighteen undrainable rural fish ponds in India was quantified using the diurnal oxygen curve method. A considerable portion of the gross primary production that was in the moderate ranges, was consumed for the community respiration. Negative, and low positive values of net primary production indicated the significance of the allochthonous supply in these organic enriched systems. The low values of sediment respiration signified the reduced condition of stagnating sediment acting as energy trap.
Evolution de la composition en acides gras d'un phytoplancton lacustre (Lac Pavin, France)
Authors: Bourdier Gilles , Amblard Christian 
Published: February 2007

Fatty Acid Composition of Lacustrian Phytoplankton (Pavin Lake, France)Fatty acid composition of lacustrian phytoplankton was established during a study carried out on Lake Pavin (France) from May to September 1981.Fatty acid spectra point out even numbers of carbon atoms (ranging from 14 to 22) and in particular unsaturated fatty acids preponderance. In addition, the occurrence of some unsaturated fatty acids is directly linked to phytoplankton taxonomic composition, but also to physiological state of the cells. Lastly, the main types of phytoplankton populations differ in the degree of unsaturation of their total fatty acids.
Relationship between Number of Eggs, Brood Weight, and Female Body Weight in Crustacea
Authors: Ivanova Marina B. , Vassilenko Stella V. 
Published: February 2007

AbstractRelationships between number of eggs (Ng), brood weight (Wg), and body length (L) and weight (W) of females were studied for 16 orders and suborders of Crustacea. The study was based on the authors' observations in the inland waters of the European USSR, in the coastal regions of the fareastern and northern seas and data from V. V. KUZNETSOV (preserved in archives). An extensive literature was also used. The equations describing the relationships (Ng=f(L) and Wg=f(W) are calculated for some species and high taxons. On the average for the superclass (excluding the order Notostraca) the Wg/W ratio appeared to be 0.16. This ratio is markedly different for species of Notostraca. It is supposed that this difference is due to the high metabolic rate of Notostraca.