bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Combined Effects of Food and Temperature on the Life History Parameters of Brachionus patulusMULLER (Rotifera)
Authors: Sarma S. S. S. , Rao T. Ramakrishna 
Published: February 2007

AbstractThe combined effects of different levels of temperature (15°, 25° and 35°C) and food Chlorella (1,2 and 4 × 106 cells/ml) on the life history parameters (lifespan, life expectancy, net reproductive rate, intrinsic rate of increase, developmental time, and generation time) of a laboratory population of the rotifer Brachionus patulus were investigated. Both food and temperature, independently and in interaction, significantly influenced nearly all the parameters. The reproductive performance was a direct function of the food level, but the magnitude of food effect was temperature‐dependent. The observed temperature × food interaction effects are explained in terms of the energetics of resource apportionment between metabolism and reproduction.
The Microbial Food Web in Eutrophic Shallow Estuaries of the Baltic Sea
Authors: Schiewer Ulrich , Jost Günter 
Published: February 2007

AbstractMicrobial food webs are responsible for the main carbon flow in shallow eutrophic estuaries of the Baltic Sea. Bacteria account for respirative use most of the autotrophic production. Bottom‐up influences are mainly directed to the phytoplankton. Massive increase of phytoplankton biomass has only little effect on the biomasses of the heterotrophic plankton. The investigated ecosystem obviously differs by its high bacteria/non‐bacteria heterotrophs‐relation from other aquatic ecosystems.
Tendencies in the Herring Population Development of the Baltic Sea
Authors: Rechlin Otto K. W. 
Published: February 2007

AbstractDuring the 1960's a change in population structure of Baltic herring started which resulted in the dominance of spring spawners in the entire Baltic since the beginning 1970's. Autumn spawning herring is very rare in the yields of fisheries since. This development has been accompanied by a likely increase of the total stock biomass of herring in the area. Yields of herring fisheries increased remarkable up to 1984, partly as a result of increased fishing effort. Recent developments of stock biomasses point to dependencies on fluctuations of growth rates. Growth is influenced by several environmental factors but is very likely especially dependent on abundance of food and on temperature. Eutrophication of the Baltic Sea increased perhaps the abundance of food for the planktonfeeding herring but it may have been contributing to the depletion of autumn spawning herring via the declining oxygen content of bottom water layers during the past 20 years.
Changes of Structure and Stock in Exploited Fish Communities in Estuaries of the Southern Baltic Coast (Mecklenburg‐Vorpommern, Germany)
Authors: Winkler Helmut M. 
Published: February 2007

AbstractBy means of analyses of catch values of selected fish species possible effects of eutrophication on the estuaries are described. Although the registered stock changes are not only a result of eutrophication a stock increase in pikeperch could be verified at the end of the first half of this century.With progressive eutrophication a great decline of migratory fish stocks took place at the end of the sixties/beginning of the seventies.The decline of eel stocks is not caused by eutrophication. Afterwards pike stocks show an aggravating decline in hypertrophic estuaries which are related to the decline of macrophytes. Baltic whitefish has still kept up its stock level under these conditions.Symptoms for a growing danger of an unexpected disaster are increasing to the whole fish community of extremely polluted waters.
Long‐term Changes in Macrozoobenthos of the Gdańsk Deep
Authors: Zmudziński Ludwik , Osowiecki Andrzej 
Published: February 2007

AbstractThe paper presents an analysis of the bottom fauna occurrence in the central part of the Gdańsk Deep in the past four decades. In 53% of the samples there were not any bottom invertebrates at all and they periodically disappeared in every decade. At the beginning of the study period, Priapuloidea, Bivalvia, Crustacea and Polychaeta were present in the bottom fauna communities, while only the two latter groups occurred towards the end of the period and the hemipelagic polychaete Harmothoe sarsi was often noted as the only species of the macrozoobenthos.
Nitrogen Metabolism in Ecosystems—A New Approach
Authors: Ripl Wilhelm , Feibicke Michael 
Published: February 2007

AbstractUsing the new Energy‐Transport‐Reaction Model, the nitrogen‐cycle is presented in relation to energy flow in a system. This model is applied exemplary to three degraded inland water bodies. The decrease in the density of energy flow in a spatially limited system provides the framework for this model. By this model the N‐cycle can be observed in relation to other abiotic and metabolic processes. The N‐cycle proves to be an important indicator, sensitive to disturbances in the hydrologic cycle. A poorly managed hydrologic cycle will increase resource losses from the watershed, and stimulate the formation of loss processes. The model allows an evaluation of a catchment's management according to its ion losses related to its nitrogen losses. Based on a longterm sustainable function of a catchment the integrity of the system is measured by its degree of closure of material cycles and lack of losses. Moreover, loss‐minimizing management practices can be derived from the model. Planning and management can be directed towards this goal of minimizing losses and evaluated accordingly.
A Study on the Impact of Urban and Industrial Development in the Linggi River Basin, Malaysia. 1. Morphometry and Physical Environment
Authors: Khan I. S. A. Nather 
Published: February 2007

AbstractThe Linggi River Basin is one of the most polluted river basins in Malaysia and drains an area of about 1,399km2 in the state of Negri Sembilan. An extensive multidisciplinary research was carried out to develop a predictive mathematical model to manage the Linggi River basin effectively. This paper reports only the morphometry and other physical environmental conditions of the Linggi River Basin which was carried out between January, 1983 and January, 1984. Topography, vegetation, landuse pattern, general geology and lithology, population distribution and water usage by the people are discussed. In addition, physical information such as air and water temperatures, precipitation, sunshine, discharge, suspended solids and dissolved solids data collected before and after the study period are discussed in detail.
Diurnal Patterns of Mixing Depth and its Influence on Primary Production in a Shallow Lake
Authors: Nixdorf Brigitte , Pagenkopf Wolf‐Gunther , Behrendt Horst 
Published: February 2007

AbstractThe influence of turbulence induced mixing on phytoplankton metabolic processes was investigated by hydrophysical and biological measurements in the eutrophic shallow lake Großer Müggelsee (mean depth = 4.9 m). To trace spatial and temporal changes in the mixing depth, high resolution temperature profiles were recorded and analysed.The vertical transport of algae in the mixed layer was simulated by the lift method, which allows an adjustment of the depth and the velocity of particle movement in a wide range (0.5‐10 cm, 0.03–3 cm · s−1). The results of this dynamic incubation were compared with those of the conventional static incubation.In general, turbulence induced mixing enhances the areal daily primary production. Net oxygen production in cycled bottles is increased up to three times compared to the areal O2‐release of algae which were incubated at a fixed position. This was proved particularly during afternoon incubation indicating the increasing importance of mixing during the course of a day. Changes in the mixing depth have only weak influence on primary production. There is a tendency towards higher O2‐production as the mixing depth increases. Remarkable diurnal changes were observed in community respiration and compensation depth. Furthermore, the influence of photoinhibition, O2‐saturation of the lake water and the diurnal changes in Chl a‐concentration on primary production were measured and discussed.
Denitrification, Nitrificastion and Nitrogen Fixation in Sublittoral Sediments of the South China Sea
Authors: Odintsov Vyacheslav S. , Propp Michail V. , Dultseva Olga A. 
Published: February 2007

AbstractMeasurements of denitrification, nitrification and nitrogen fixation rates were made alongside with measuring of chemical and physical properties in sublittoral sediments of the South China Sea near the coast of Vietnam. Studied sediments were suboxic (Eh was positive as a rule), had 0.18–1.5 % of organic carbon, 0.004–0.135 % of total nitrogen and 3‐12 % of total iron. The numbers of denitrifying and nitrate‐reducing bacteria were as high as millions and hundreds of millions cells per gram wet weight of sediment matter, respectively. The processes of nitrification and denitrification were not spearated spacely. The nitrification was measured in both superficial layer and in a 10‐cm sediment column. There were indirect evidences suggesting possibility of anaerobic ammonium oxidation. Denitrification was detectable in the sediments from two sites of sampling; maximal value was 86.2 μmoles N m−2h−1. The denitrification potential determined at 1 mM nitrate decreased regularly from the upper to lower layers. Its values in the different sediments ranged from 134 to 532 μmoles N m−2h−1. Nitrogen fixation (from 4.8 to 86μmoles N m−2h−1) was close to that found in similar sediments in temperate waters in summer, and was not a significant source of nitrogen. It was comparable with diffusion of ammonium from sedimnts.
The Influence of Environmental Factors and Microhabitat Availability on the Distribution of an Aquatic Oligochaete Assemblage in a Mediterranean River Basin
Authors: Prenda José , Gallardo Alfonso 
Published: February 2007

AbstractSome aquatic oligochaete species, mainly certain naidids and tubificids, are often associated with polluted environments, with high levels of organic matter and oxygen deficit. However, in the stations sampled in the Guadaira river basin, which can be arranged on an axis of organic pollution, the main aquatic oligochaete species (Nais elinguis and Tubifex tubifex) inhabiting these environments do not show a distribution pattern significantly related to the water physico‐chemical characteristics measured. Nor, have we registered any association between these species and any kind of microhabitat, defined here: water current, presence of different types of vegetation, substrate coarseness and presence of anoxic sediments. Paranais litoralis is the exception, being related to areas without water current, located at higher altitudes, with high levels of dissolved organic matter and an anoxic substrate made up of fine particles.These results can be explained by the highly fluctuating nature of Mediterranean ecosystems and by the marked generalist character and ubiquity of the oligochaete assemblage species, able to colonize any kind of environment.
In situ Development of Perch Eggs, Perca fluviutilis L. (Pisces, Percidae) in a Small Eutrophic Lake, Lake Plussee, Holstein, Germany
Authors: Reyes Mario R. Delos , Arzbach Hans‐Hermann , Braum Erich 
Published: February 2007

AbstractNaturally spawned egg strands of perch, Perca fluviatilis L. were sampled from exposed fir trees submerged in Lake Plußsee, Holstein, Northern Germany from April to May 1989. These were incubated in situ and in the laboratory to estimate the viability, development and abnormalities of the embryos. From the in siru incubated eggs 91.6% embryos were viable, the nonviable portion comprising 1.1 % unfertilized eggs, 5.1 % dead and 2.2 % with abnormalities. As compared to the eggs incubated in the laboratory with 84.1 % viable embryos, the nonviable portion consisting 1.1 % unfertilized eggs, 11.3 % dead and 3.5 % with abnormalities. Incubation rate of P. fluviatilis embryos both in situ and laboratory, ranged from 200‐210 ATUs (10°C in situ and 8°C in the laboratory) with incubation period of 20‐27 days from fertilization to 50 % hatching.
A Population of the Sea Anemone Anemonia viridis (FŐRSKAL, 1775) and its Associated Flora and Fauna, in the North Aegean Sea
Authors: Chintiroglou Charis , Koukouras Athanasios 
Published: February 2007

AbstractThe assemblage of Anemonia viridis which is an important component of the photophilic soft algae biocoenosis, has not been adequately studied up to date. The A. viridis assemblage studied, was poor in species number compared to other photophilic soft algae assemblages, possibly because of its peculiar physiology and competition for space. Three age groups of A. viridis were distinguished, two of which (the first and the third) showed significant seasonal variations. The reasons for this are still unclear and may depend on recruitment, competition among small‐sized individuals, predation or other mortality factors, and migration of larger individuals.
Investigations on the Ecology and Fish Fauna of the Mahakam River in East Kalimantan (Borneo), Indonesia
Authors: Christensen Mikkel S. 
Published: February 2007

AbstractWater quality was determined on the Mahakam River floodplain from 1980 to 1987. Five water‐body types were distinguished, i.e. slow‐flowing and faster‐flowing rivers, lakes, small waterbodies and swamps. Water quality in large rivers was stable in the short but not the long term. In all other ecotypes variability was higher, with marked fluctuations being recorded in small waterbodies.A total of 147 indigenous freshwater fish species have so far been identified from the Mahakam. The zoogeographical consequences are discussed.Migratory patterns were inferred for four fish species, Helostoma temmincki, Leptobarbus hoe‐venii, Puntius schwanenfeldii and Thynnichthys vaillanti. Juvenile H. temmincki (< 3 cm SL) migrate at the surface in schools of 40‐80 individuals at speeds of 0.48‐1.08 km · h−1, travelling 3.8‐8.6 km · h−1. Fecundities for P. schwanenfeldii (7,900–16,000 eggs), T. vaillanti (2,900–24,000 eggs) and H. temmincki (6,200–9,100 eggs) were determined.
The Life Histories of Two Temporarily Coexisting, Pond Dwelling Cladocerans
Authors: Maier Gerhard 
Published: February 2007

AbstractInvestigations on the life histories of two cladocerans, Moina brachiata and Daphnia obtusa, in a small, nearly temporary pond in South Germany revealed that M. brachiata is better adapted to fluctuating environmental conditions; the species dominated from May to October. D. obtusa was present in spring and autumn/winter but disappeared completely during the summer months. Both species coexisted for extended periods in spring and autumn; abundance of D. obtusa was generally by an order of magnitute lower. Four periods of low water level were slightly preceded by or coincided with a decrease of clutch size, a decrease of the proportion of egg bearing females indicating that both species suffered from food shortage.Laboratory investigations on life history parameters showed that the two species have different temperature tolerances and preferences. M. brachiata showed its highest reproductive success at 25 and 30°C but died at temperatures <15°C and ≥ 35°C. D. obtusa experienced a broader temperature range (2 to 25°C) but could not withstand temperatures ≥ 30°C. Short term starvation periods (3d) caused the death of M. brachiata females, while D. obtusa soon recovered and reproduced when being refed.M. brachiata is a typical r‐species with early reproduction, rapid development, high population growth rates and a high tendency to produce resting eggs; D. obtusa pursues more the concept of k‐selection.
Study on the Decomposition of Pistia stratiotes L. (Araceae) in Cisne Reservoir, Uruguay
Authors: Sommaruga Ruben , Crosa Dario , Mazzeo Nestor 
Published: February 2007

AbstractA study on the decomposition process of Pistia stratiotes L. was carried out in Cisne Reservoir, Uruguay. For this purpose, leaves and roots were considered separately, and the process was studied in the littoral and the pelagic zone. The litter bag technique was used to estimate dry weight losses at different times. Leaves decomposed faster than roots in both zones. Pistia decomposed faster in the pelagic zone due to better oxygen conditions and a more intensive water movement that removes material from within the bags. Phosphorus, potassium, sodium and magnesium were leached rapidly during the first week. Nitrogen content in the leaves initially increased, reaching its maximum in the littoral zone that coincided with that of bacterial numbers colonizing the litter. The number of macroinvertebrates, dominated by Chironomidae, was low. A rough estimation of the phosphorus impact on the littoral zone associated to the decomposition process shows that after 24 h between 13.9 and 16.8 μg‐at.1−1 have been released to the water.
Seasonal and Long‐term Variability of Nutrients in Lake Müggelsee
Authors: Kozerski Hans‐Peter , Gelbrecht Jörg , Stellmacher Rita 
Published: February 2007

AbstractSeasonal and long‐term variability of the nutrients phosphorus, nitrogen, and silicon were investigated in the eutrophic Lake Müggelsee and its inflow from 1979 to 1990. The lake concentrations were internally controlled during the summer season and by the inflowing river in winter, respectively. The lake acts as a sink of nutrients. 18% of N and 3.5% of P were retained in the 12‐years‐period. Phosphorus retention differed from year to year. The average retention rate of the investigated period was only 4 kgP/d, but in some years it was negative due to strong P‐release from sediment. The P‐retention rate was also influenced by bank filtration (withdrawal for a waterworks).
Postimpoundment Changes in Water Quality and Fish Stocks in Two Large West African Reservoirs (Manantali and Sélingué, Mali)
Authors: Anne J. , Lelek A. , Tobias W. 
Published: February 2007

AbstractThe recently established large reservoirs Manantali on the river Bafing, tributary to the Senegal River and Sélingué, located on the river Sankarani, tributary to the Niger River, have followed similar changes in limnology and fish populations as those established in West Africa 20 to 30 years ago. Basic water parameters, such as oxygen content, pH, electrical conductivity and temperature show seasonal variations largely determined by the changes in wet and dry seasons. Both waterbodies are monomictic, with water mixing taking place in January, the coldest period of the year. Pre‐impoundment forest clearence of the future reservoir bottom in the shallow Sélingué reservoir was carried out only in the proximity of the dam site. In the deeper reservoir Manantali the savanna forest was cleared from an area of about 25 percent, and the tree gallery was cleared along the river. The initial filling of Manantali reservoir was followed by a nearly complete drainage of the reservoir. After refilling some months later, the dissolved oxygen content stayed reasonably high and therefore there was no fish mortality. Also no hydrogen sulphide or a large‐scale spread of noxious aquatic plants developed. At present the fish fauna is dominated by cichlids and pelagic species, i.e. at Sélingué by clupeids. and at Manantali by cyprinids (Leptocypris niloticus). In both reservoirs was the genus Citharinus considerably reduced. At Sélingué reservoir disappeared Protopterus annectens. The fish yield estimate is 27 kg/ha/year for Manantali, and 40 kg/ha/year for Sélingué. Both rerservoirs have recorded a slight increase in electrical conductivity. They both serve as a valuable water resource and fish supply for the Sahel region.
Fisheries in Semi‐Arid Northeast Brazil with Special Reference to the Role of Tilapias
Authors: Gurgel J. J. S. , Fernando C. H. 
Published: February 2007

AbstractThe reservoir fisheries in the semi‐arid Northeast Brazil have been studied based on the data collected by the Department of Action Against Droughts and placed against the background of what is known of similar fisheries in the tropics elsewhere. Of about 60,000 reservoirs in the region, DNOCS controls about 100 reservoirs since 1970. Physical characteristics are provided together with total areas of the reservoirs. Unfortunately very little basic limnological data are available.In all 42 species of fish and crustaceans were introduced into these reservoirs of which only fourteen fish species and one shrimp were successful in establishing self‐propagating populations, others being stocked on a regular basis. The recent stocking ofColossoma macropomumandCyprinus carpioare however unsuccessful in reservoirs.The fish yield of DNOCS controlled reservoirs for 1950–1990 was 112 kg.ha−1(Davies, 1972; Gurgel and Oliveira, 1987). It amounts now to about 20,000 tons annually taking into account incomplete and scaled down reporting of catches. This indicates a total fish catch from 60,000 reservoirs in the Northeast of Brazil of very substantial size.The CPUE and catches of all species and that ofTilapia rendalliandOreochromis niloticusare given together with a discussion of the fisheries and recommendations for management. The total CPUE varied from 18–1,100 kg.ha−1. However, most fishermen are only part‐timers.It appears likely that very substantial yields of fish are being harvested in Northeast Brazil but are under‐reported. Management strategies now in operation in reservoir fisheries are still very pragmatic. With the accumulation of data and generalizations, more viable strategies could be devised.
Low Fish Predation Pressure in the London Reservoirs: I. Species Composition, Density and Biomass
Authors: Kubečka Jan , Duncan Annie 
Published: February 2007

AbstractThe London reservoirs sited in the lower Thames valley form part of a continuously flowing, drinking water supply system and as such have been wholly designed, constructed and operated by man for this sole function. This paper adds some information on the potential impact of the fish populations on the ecology of these relatively deep reservoirs. The fish fauna was studied by night shore seining (to detect inshore fish communities) and acoustically (to detect the offshore fish communities). Ruffe (Gymnocephalus cernuus) and perch (Perca fluviatilis) are the main species capable of reproduction on the steeply sloping concrete walls of the reservoirs. Cyprinids are almost absent in Wraysbury Reservoir whilst in Queen Mary and Queen Elizabeth II reservoirs they are more abundantly represented due to enhanced spawning possibilities associated with inundated marginal terrestrial plants in Queen Mary and the net‐sides of empty fish cages in Queen Elizabeth II reservoir. Fish biomasses of the three London reservoirs studied are low: 6.8 kg/ha in Wraysbury Reservoir, 28.6 kg/ha in Queen Mary reservoir and 45.6 kg/ha in Queen Elizabeth II Reservoir. Coinciding with this is a zooplankton of unusually large‐sized cladocerans, largely daphnids, and high fish growth rates.