bluuebunny/crossref_metadata_2025 huggingface dataset:
A Quantitative Study of the Comparative Distribution of Non‐parasitic Leeches and Triclads in the Stony Littoral of British Lakes
Authors: Young J. O. , Ironmonger J. W.
Published: February 2007

For each of the three species of leeches and four species of triclads inhabiting the stony littoral of 100 British lakes of diverse trophic status, numbers, biomass and mean weight were correlated against a wide range of physical, chemical and other variables. Very few significant correlations were found between the various biological variables and the non‐chemical variables. Significant, positive correlations were obtained for all leech and triclad variables against all of the chemicals, with the exception of Erpobdella octoculata numbers, Helobdella stagnalis mean weight and all of the Polycelis nigra variables which did not correlate with any. Relationships between biological variables and calcium content are given special consideration. Over the range of lakes investigated, total triclad numbers exceeded leech numbers but the reverse was usually true for total biomass. Correlations between the various leech and triclad variables are examined.
Energy Flows in Populations and Communities of Aquatic Animals
Authors: Alimov A. F.
Published: February 2007

The energy assimilated by single individuals of aquatic animals throughout their life times and by populations and communities of aquatic animals during the growth season has been studied with due regard for the definitive weight of the single individual and the mean biomass of populations and communities. Energy assimilated throughout life by invertebrates of different systematic positions, definitive size and life duration is about 2.5 times as high as the energetic content of their definitive mass. The energy flow in populations of benthic animals is about 5 times as high as the seasonal average biomass, and in populations of planktonic animals it is 40 times as high. The energy flow in bottom communities is almost 10 times and in planktonic ones 35 times as high as the average seasonal biomass of communities. Specific production (P/B coefficient per 24 h) for communities of bottom animals was 0.013 per 24 h. The average value of the K2 coefficient (net growth efficiency) calculated for an individual's life time is about 0.4 in populations of bottom animals, the K2 for vegetation seasons is 0.26, and for communities it is 0.2 (per vegetation season). Increasing complexity of the biological systems is accompanied by an increase in the specific energy flow and a decline in the efficiency of food energy utilization for production.
Macrobenthic Communities of the Lower Chesapeake Bay. II. Lynn‐haven Roads, Lynnhaven Bay, Broad Bay, and Linkhorn Bay
Authors: Tourtellotte Gary H. , Dauer Daniel M.
Published: February 2007

Based on 96 grab samples at 16 sites the composition and distribution of macrobenthic fauna were examined in a small coastal basin of lower Chesapeake Bay. Normal classification analysis of dominant species produced five site groups. Site groups were divided into clean sand sites, fine sand sites with varying amounts of silt‐clay, and mud sites. Dominant species of the clean group were primarily restricted to this sediment type, while the dominant species of the other groups were widespread in the study area.
Oxygen Consumption and Dissolved Inorganic Nutrient Production in Marine Coastal and Shelf Sediments of the Middle Atlantic Bight
Authors: Florek Robert J. , Rowe Gilbert T.
Published: February 2007

The benthic oxygen demand and inorganic nutrient release have been investigated in the coastal zone of the Mid‐Atlantic Bight of the United States using in situ and ship‐board incubations to estimate fluxes across the sediment‐water interface. Oxygen demand ranged from ca. 70 ml m−2 hr−1 nearshore in warm (25°C) muddy sediments to ca. 4 ml m−2 hr−1 in cold (6°C), coarse‐grained sediments offshore. Ammonium ion flux was out of the sediments in all but 4 of 29 incubations, while nitrate was often found to be utilized within or on the sediments, decreasing in 10 of 29 incubations. Those locations with fluxes of nitrate out of the sediment had concentrations in the pore water that were generally high, sometimes up to several mM l−1. Nitrate fluxes were always well below those of ammonia, even where high almost equivalent concentrations of both NH4 and NO3 were found at the same locale.

On George's Bank only 13 % of total N demand by the phytoplankton was estimated to be supplied by the benthos, whereas in New York Bight the supply amounted to 42 % of the demand. This difference can be attributed to higher pelagic biological and advective (mixing and upwelling) inputs to George's Bank compared to the relatively well stratified New York Bight in late summer and autumn.
Sensitivity of Lakes to Inorganic Enrichment Stress ‐ Some Results of Experimentally Induced Fertilization
Authors: Hillbricht‐Ilkowska Anna , Zdanowski Bogusław
Published: February 2007

The introduction of P and N loads exceeding 4‐14 and 1‐2 times, respectively, the amount of these nutrients stored in the waters of four lakes (dystrophic and eutrophic, stratified and unstratified) resulted in stronger, two‐phased changes in Ptot standing stock and in rather insignificant and non‐directed changes in Ntot in all lakes. In the waters there was the immediate increase of Ptot followed by a decrease (together with a decrease in the N : P ratio) but the final level was still higher than in the control. In the top layer of off‐littoral sediments there was a temporary accumulation of nutrients followed by their release to a level significantly lower than that in the control year. Visible changes in the nutrient content and total biomass of above‐ground parts of macrophytes were noted only in the lake which was previously highly dystrophic, after it had been limed. This lake reacted strongest to the P load, and the release of nutrients from its deposits started simultaneously with fertilization. It is hypothesized that the reduction in the N : P ratio in the lake waters was mainly responsible for the lack of assimilation of further doses of P and that the acceleration of denitrification process caused by the higher overall lake productivity was responsible for the stabilization and removal of the N load. The activation of bacterial decomposition in the sediments due to the increase in lake productivity and sedimentation rate was considered as the probable reason for the acceleration of the nutrients release from the top layers of the sediments and their further physical transport to deeper layers.
The Natural History of a Nearctic Temporary Pond in Ontario with Remarks on Continental Variation in such Habitats
Authors: Williams D. Dudley
Published: February 2007

The seasonal succession of members of the invertebrate community of a temporary vernal pond in southern Ontario is described. Although succession was essentially continuous, 5 faunal groups are suggested, based on time of appearance and duration of active forms in the pond. Some species were found during virtually the entire aquatic phase, while others completed their life cycles in only 2‐3 weeks. Analysis of growth rates revealed many different patterns between species and groups. Analysis of community structure in terms of trophic status indicated shifts which coincided with the seasonal occurrence of the pond's potential food resources. Comparison of this fauna with that of a similar pond on Vancouver Island, British Columbia (some 2,400 km to the west) showed many similarities in niche occupancy, including 6 species in common. The biological characteristics leading to the success of these cosmopolitan species in temporary aquatic habitats is discussed.
Birth and Death Rates of a Littoral Filter Feeding Microcrustacean, Sida crystallina (Cladocera), in Cochran Lake, Michigan
Authors: Fairchild G. Winfield
Published: February 2007

Population changes of Sida crystallina, a filter feeding microcrustacean which attaches to aquatic macrophytes, were examined in Cochran Lake, Michigan during June and July, 1979. Population estimates were derived from organisms present in 10 samples of leaves of the water lily Nymphaea odorata collected every 3 days.

Population densities of Sida responded both to food and predation by fish. Declines in average clutch size were associated with decreasing phytoplankton biomass and the increasing dominance of colonial green and blue‐green algae, but were not significantly influenced by the densities of invertebrates on the plants. Largemouth bass fry (Micropterus salmoides) dramatically reduced the numbers of Sida and altered the age structure of the population in late June.
Studies on Stabilization Ponds for Domestic Sewage in India
Authors: Rao A. V.
Published: February 2007

For one year a single cell stabilization pond, T. T. Nagar, Bhopal (August, 1968 to July, 1969) and series stabilization ponds, Shahpur, Bhopal (January, 1969 to December, 1969) were studied. Climatological conditions in Bhopal were favourable for the treatment of sewage in stabilization ponds. There was a considerable reduction in BOD, total nitrogen, phosphate, coliforms and enterococci during the process of treatment. The reductions were highest in series ponds. Studies on diurnal variations showed that highest pH, dissolved oxygen, algal cell number and lowest alkalinity values occurred around 4.00 p.m. Algal flora present in the single cell pond consisted of 31 species representing 27 genera. In the series ponds 33 species belonging to 30 genera and 37 species belonging to 33 genera were recorded for the primary and secondary ponds, respectively.
Standardgewichte der Copepoden in der Pommerschen Bucht. Standard Weights of the Pomeranian Bay Copepods
Authors: Chojnacki Juliusz
Published: February 2007

The length weight relationship was determined for Pseudocalanus minutus elongatus, Temora longicornis, Acartia bifilosa, and Acartia longiremis caught in the Pomeranian Bay (Baltic Sea). To determine the weights of the individuals a geometrical method was used and the formula.
Studies on Chaetophoraceae from Southern Iraq
Authors: Islam A. K. M. Nurul , Haroon A. K. Yousuf
Published: February 2007

Cloniophora macrocladia (NORDST) BOUR. var. macrocladia, Stigeoclonium curvirostrum SKUJA, St. fasciculare KÜTZ. var. glomerata (HAZEN) ISLAM and St. stagnatile (HAZEN) COLLINS fa. are reported from Iraq.
The Spatial and Temporal Distribution of Epipelic Algae in a Shallow Eutrophic Prairie‐parkland Lake, Alberta, Canada
Authors: Jenkerson C. G. , Hickman M.
Published: February 2007

Investigations were conducted upon the epipelic algal community of a shallow eutrophic lake in central Alberta, Canada. The lake was Hastings Lake (longitudes 112° 50′ and 113° 00′ W; latitudes 53° 15′ and 53° 50′ N). The epipelic algae displayed both spatial and temporal distributions for species composition, standing crop as well as productivity.In situcross incubation experiments showed the potential photosynthetic viability of epipelic algae living below the 1% irradiance level.
The Natural Feeding and Resource Partitioning of Erpobdella octoculata L. and Erpobdella testacea SAV. in Lake Esrom, Denmark
Authors: Dall Peter C.
Published: February 2007

The natural feeding and competitive interactions between populations of Erpobdella ostoculata and Erpobdella testacea were investigated in Lake Esrom, Denmark, during 1979/80. Statistical analysis revealed that the size of the leeches was the main factor involved in resource utilization. Size‐specific feeding included differences in the numerical composition of diets and the size of individual prey. Five weight classes of Erpobdella spp. were distinguished. The number of prey per leech increased from 1.63‐2.84 for the first to the fifth weight class, whereas diversity in feeding averaged 1.71 prey per leech. Quantification of competitive interactions indicated that the temporal differences in weight class composition of the two species were sufficient to explain coexistence, although both species have an annual life cycle, and neither species showed taxonomic food refuges.
Estimates of Microbial Populations Involved in the N Cycle and their Activity in Water and Sediments of Fish Farming Ponds under Mono and Polyculture Systems in India
Authors: Jana B. B. , Roy S. K.
Published: February 2007

The population sizes of ammonifying, protein mineralizing, nitrogen fixing and nitrifying bacteria, and the rates of ammonification and nitrification (natural and potential) were measured in water and sediments of four fish ponds being used for traditional, mono‐ and polyculture systems of fish farming. Spatial differences in the microbial density in these ponds were related to the fish culturing practices adopted. The seasonal variation of ammonifying bacteria was found to be positively correlated with the NH4‐N level in the water. The natural and potential capacity to generate both nitrite and nitrate in these water bodies was strongly correlated with the concentrations of the different forms of inorganic nitrogen present. The rates of NO2‐N and NO3‐N formation occurring in these fish ponds were directly proportional to the amount of dissolved oxygen and pH of the environment, respectively.
The Proportion of Empneuston and Total Atmospheric Inputs of Carbon, Nitrogen and Phosphorus in the Nutrient Budget of a Small Mesotrophic Lake (Piburger See, Austria)
Authors: Psenner Roland
Published: February 2007

Litter and wet traps were employed to determine the inputs of coarse organic matter (empneuston), total organic carbon, total nitrogen and phosphorus through dry fallout and precipitation to a soft‐water, mesotrophic lake. The dispersal of airborne material over the lake surface was investigated, and a method for the calculation of total input was developed. The component of the particulate matter larger than 1 mm contained the largest proportion of organic carbon, while the dissolved and the fine particle (smaller than 1 mm) fractions made greater contributions to the inputs of nitrogen and phosphorus compounds. The importance of the large particle fraction of the airborne organic matter in the lake's nutrient budget during the autumnal fall of litter was confirmed. However, the maximum total airborne input seems to occur during spring and summer. The input of phosphorus compounds through the atmosphere to small forest lakes is large compared to that from other sources. Airborne material accounts for 39% of the total phosphorus loading.
Prehistoric pH Trends in Kejimkujik Lake, Nova Scotia
Authors: Delorme L. Denis , Esterby Sylvia R. , Duthie Hamish
Published: February 2007

Kejimkujik Lake in Nova Scotia has an average pH of 4.8 and receives wet precipitation with a weighted mean pH of 4.62. The lake is situated in a drainage basin where organic rich soils and bogs rest upon poorly buffered igneous and metamorphic rocks. Fossil diatoms from a sediment core reveal that since 21.7cm the pH trend has been to a lower pH. The flora of the lake between 13.0 and 10.7cm indicate a climatic change to a dryer period followed by a return to a more moist and humid climate. Colonization by European settlers, around 1850 A.D. drastically altered the pH of Kejimkujik Lake through deforestation and burning of lumbering refuse. The effect of potassium hydroxide, by leaching potassium from wood ash, on the lake continued to 2.2cm (about 1950) when the acidity began to drop to lower more normal levels. The overriding effect on the lake appears to have been the presence of organic soils and bogs which have contributed organic acids to the system since at least 21.7cm.
Primary Production Characteristics of a Himalayan Lake in Kashmir
Authors: Wanganeo Ashwani
Published: February 2007

Lake Manasbal is the only valley lake in the region with a true thermal stratification during summer. Seasonal and annual rates of carbon fixation in the water column by plankton populations were related to physical and chemical parameters on specific days. The temporal and spatial changes showed the strong influence of nutrients on the primary production. No significant dependence of carbon uptake on either phytoplankton density or biomass was determined. The overall production pattern during the study period was definitely bimodal, with one minor peak in spring (719.3 mgC m−2 day−1) and a major one in summer (1496.2 mgC m−2 day−1 in June). The study also revealed that nannoplankton was responsible for 69% of the primary production.
Bag Experiments on the Effect of Phosphorus and Base Additions on the Algal Biomass and Species Composition of an Acid Lake
Authors: Wilcox Gerald R. , Decosta John
Published: February 2007

Bag experiments were conducted to determine the effect of neutralization and phosphorus additions on phytoplankton in a lake acidified by mine drainage. Neutralization and phosphorus additions caused a lag of several days before algal growth occurred.
Dégradation d'acides aminés à l'interface eau‐sédiment réconstitué d'une lagune méditerranéenne (Golfe du Lion)
Authors: Daumas R. , Gadel F. , Cahet G. , Dinet A.
Published: February 2007

Degradation of Amino Acids at a Simulated Water‐sediment Interface of a Mediterranean Lagoon Environment, Golfe du Lion

The degradation of two 14C and 3H labelled amino acids at the simulated water‐sediment interface of a Mediterranean lagoon was studied.

The four day experiments included the respiratory activity measurement and the study of incorporation processes of the radioactivity in specific organic fractions of the 14C arginine. After active mineralization occurred during the first day, the radioactivity in the acid‐soluble fraction decreased and polycondensed products were progressively incorporated. The radioactivity of the 3H lysine was included mainly in the acid soluble fraction.

The nature of the substrate, and the reducing conditions in the environment affect the radioactivity distribution in the organic fractions.

The identification of amino acids in the acid‐soluble and base soluble fractions shows that the labelled arginine and lysine and other amino acids in the acid soluble and base soluble fractions shows that the labelled arginine and lysine released from the initial compounds are important quantitatively.
Production and Distribution of the Microphytobenthos in the Sediment of Lake Mikolajskie
Authors: Wasmund Norbert
Published: February 2007

Chlorophyll‐α concentration, algal biomass and photosynthetic activity decrease with increasing sediment depth. Chlorophyll‐α and biomass minima were found at the sediment surface on several occasions. This may be due to the removal of algae by wave action or vertical migrations of the algae in the sediment. By comparing stations with different degrees of exposure it was shown that wave action affects the size of the benthic populations. The epipsammic microphytobenthos is an important primary producer in the littoral zone of Lake Mikolajskie.
Le phytoplancton des étangs de Berre et Vaïne (Méditerranée Nord‐occidentale)
Authors: Kim Ki‐Tai , Travers Marc
Published: February 2007

Phytoplankton of the Etang de Berre and Etang de Vaïne (N.W. Mediterranean)

The phytoplankton in the brackish Etang de Berre and Etang de Vaïne was studied regularly at 12 stations for two years. The recent diversion of the Durance River into the Etang de Berre has effected a fundamental change in this formerly marine environment, which has had a great impact on its plankton populations. A total of 182 taxa were identified, including 111 Bacillariophyceae, 44 Chlorophyceae, and 15 Cyanophyceae. The most abundant species are small freshwater algae, mainly Chlorophyceae, since the salinity is generally less than 3 0/00. However, during summer and fall, as well as in waters near the bottom, the salinity can reach 15 0/00 and marine diatoms are predominant.

Because the nutrients in the environment are constantly replenished, phytoplankters are always numerous, ranging in abundance between several million to several hundred million per liter. There is a somewhat irregular seasonal cycle. The average density is about 108 cells/1 in the Etang de Berre, and about double that amount in the Etang de Vaïne. Differences in phytoplankton abundance and composition at the various stations or at various depths are slight.
Phytoplankton Distribution in the Coastal Area Subject to the Impact with the Tiber River Outfall
Authors: Puddu A. , Arfi R.
Published: February 2007

The taxonomic composition and geographical distribution of phytoplankton in the coastal zone surrounding the River Tiber mouth were investigated in twelve surveys from April 1978 to September 1979. Ninety phytoplankton species were identified from 168 samples. Diatoms were clearly the dominating species, accounting for more than 95 per cent of total phytoplankton.— Principal Component Analysis was utilized to analyse the total information obtained.—The direct impact on the coastal environment of River Tiber water and its considerable nutrient load were seen as providing a permanent potential for the development of less structured phytoplankton communities. Heterogeneity of local hydrological conditions and fluctuations in the river's impact, lead to a virtually constant instability in the neritic environment near the Tiber River outfall.
Limnology of a Sewage Polluted Tank in Central India
Authors: Unni K. Sankaran
Published: February 2007

The limnology of a sewage polluted pond was studied from 1978 to 1981. Stratification of temperature, dissolved, oxygen, conductivity, pH, alkalinity and chloride was recorded. The surface stratum down to 0.5 m was supersaturated throughout the year. The pond recorded a permanent water bloom dominated by Anacystis during the summer months. This was followed by Anabaena and Anabaenopsis during winter. The growth of Chlorococcales was retarded due to intraspecific competition, self‐shading and low carbon dioxide levels though the waters were nutrient rich. Before the summer overturn, accumulation of calcium bicarbonate produced temporal meromixis. In general, a reduction in the number of zooplankters was recorded.
Assessment of Components Controlling Phytoplankton Photosynthesis and Bacterioplankton Production in a Shallow, Alkaline, Turbid Lake (Neusiedlersee, Austria)
Authors: Dokulil Martin
Published: February 2007

Various aspects of phytoplankton photosynthesis were investigated between 1968 and 1980 in Neusiedlersee, Austria, a shallow (z̄ = 1.3 m), well mixed lake with much turbidity resulting from frequent resuspension of inorganic sediment particles. The influences of the great environmental variability on biomass, photosynthesis and phytoplankton production were determined and discussed with respect to the increasing nutrient concentrations in the lake. Investigations of bacterioplankton biomass and production revealed their importance for nutrient regeneration and as food for large zooplankton populations. The results are compared with those from several other shallow lakes, and an attempt is made to identify characteristics to distinguish the different types.
Faunistische Untersuchungen im hyporheischen Interstitial des Flusses Mur (Steiermark, Österreich)
Authors: Kirchengast Michael
Published: February 2007

Faunistic Investigations of the Hyporheic Interstitial of the River Mur (Styria, Austria)

Two distinct sections of the River Mur (Styria, Austria), one almost unpolluted and the other heavily polluted by domestic and industrial waste waters, were investigated for two years. Faunistic, hydrographic, and ecological investigations were carried out at the river bottom, including particularly the hyporheic interstitial zone. All species found were investigated qualitatively and quantitatively, and ecological factors are stressed. The composition of the fauna of the unpolluted area differs markedly from that in the polluted section.
Form Variations in the Rotifer Brachionus calyciflorus Pallas from a Perennial Impoundment in India
Authors: Sharma Surya Prakash , Saksena Devendra Nath
Published: February 2007

All three classical forms of Brachionus calyciflorus Pallas viz., calyciflorus, dorcas and amphiceros were recognised in the impoundment. The form amphiceros was most abundant, and its occurrence is attributed to the presence of Asplanchna brightwelli in the tank. Euglena viridis appears to be the preferred food of B. calyciflorus in this impoundment.
Influence of Water Hyacinth Cover on the Physico‐chemical Characteristics of Water and Phytoplankton Composition in a Reservoir near Jaipur (India)
Authors: Gopal B. , Trivedy R. K. , Goel P. K.
Published: February 2007

Water hyacinth (Eichhornia crassipes (Mart.) Solms.) invaded a eutrophic reservoir receiving domestic sewage near Jaipur (India) during 1975 and gradually developed a complete thick cover over the whole water body during Sept.–Oct. 1978. The physico‐chemical characteristics of the water and the phytoplankton composition were studied during Sept. 1977–Sept. 1979 by fortnightly sampling. The changes observed during the second year of study are ascribed to the water hyacinth cover. The important changes were: lowering of water temperature, pH, dissolved oxygen content and nitrate nitrogen, and increase in total alkalinity, free carbon dioxide, chemical oxygen demand, ammonia nitrogen, sulphides, calcium, magnesium and phosphate phosphorus. The changes in the phytoplankton were both qualitative and quantitative. The green algae, particularly the species of Ankistrodesmus, Chlorella, Crucigenia and Selenastrum, increased considerably and replaced the blue‐green algae, of which Oscillatoria and Microcystis disappeared totally. The densities of several other taxa changed significantly.
Attraction of Fish to Mercury Vapour Light and Its Application in a Generating Station Forebay
Authors: Haymes Gerard T. , Patrick Paul H. , Onisto Lawrence J.
Published: February 2007

Laboratory and field tests were conducted to determine the effectiveness of filtered mercury vapour lights in attracting fish with possible utilization in a fish conserving scheme at an electrical generating station. In laboratory tests, alewife demonstrated an attraction to the mercury vapour light which was associated with an increase in swimming activity. This response was maintained over a 48‐hour period. When the filtered mercury vapour lights were utilized in association with a fish pump in the Nanticoke Generating Station forebay, juvenile gizzard shad and smelt were attracted to the pump area. Although there was variation with time of day, tubidity and lighting array; the results suggested that the number of fish passing through the pump increased when the mercury vapour lights alone or when the mercury lights in association with a white strobe light were employed.
Acanthostoella norvegica(Daday) in Insular Newfoundland Waters, Canada (Protozoa: Tintinnina)
Authors: Davis Charles C.
Published: February 2007

The seasonal and vertical distributions ofAcanthostomella norvegicaare described from two fjord‐like bays in insular Newfoundland, Canada. Resting spores are figured and described.
Spectral Analysis of the Automatically Recorded Data from Slapy Reservoir, Czechoslovakia
Authors: Nesmêrák I. , Straškraba M.
Published: February 2007

The data for solar radiation (S), air temperature (Ta), surface water temperature (Tw) and pH recorded at 0.5 hr intervals at Slapy Reservoir were subject to spectral analysis. The complete series covered the month of July 1978, where three characteristic sections were distinguished, of which one was characterized by low variations, more irregular values and a slowly decreasing trend and another with high and regular variations as well as a steeply increasing trend. These sections were analysed separately in addition to the complete series. The period of 24 hrs was most important and represented forS,Taand pH 60, 38 and 18 % of the total variances, respectively. The deterministic periodic component represented 65–95 % of the total variance. The cross‐correlation and cross‐covariance between selected pairs of variables suggested lags of up to 4.5 hrs, the longest lag being observed forTwandS. An autoregressive model of the interrelation between the signals was formulated.
Hydrology and Changes in the Nutrients and Phytoplankton Levels in Goat Island Bay, Northern New Zealand
Authors: Taylor Nigel J. , Taylor F. J.
Published: February 2007

A survey of the phytoplankton and nutrient levels in Goat Island Bay, northern New Zealand was carried out in 1981–82 and the data compared with an earlier survey in 1966–69. The contribution of nutrients from the inflowing creek was also measured. The only significant change was a doubling of the dissolved nitrate levels in the sea, which appeared to be related to increased nitrate levels in the freshwater creek. It is suggested that the increase is due to an increase in the farming and recreational use of the catchment area.

The standing crops of phytoplankton in the bay showed no correlation with nutrient levels, but there were significant correlations with the radiation received.
Etudes expérimentalles sur la sensibilité du phytoplancton d'eau douce aux variations de salinité dans le fjord du Saguenay (Estuaire du St‐Laurent), Canada Experimental Studies on the Susceptibility of Freshwater Phytoplankton to Variation of Salinity in the Fjord of Saguenay (St. Lawrence Estuary), Canada
Authors: Cloutier Sylvain , Cǒté Raynald
Published: February 2007

The Saguenay Fjord is characterized by very high run‐offs. The annual flow varies between 1.2 and 4.2 × 103 m3 . s−1. During the summer the surface salinity shows a sharp horizontal gradient (from 1 0/00 to 20 0/00). The surface phytoplankton, mainly freshwater and even some euryhaline species is submitted to salinity stress. Continuous culture experiments were conducted to study the susceptibility of this freshwater phytoplankton under different salinity conditions. Some pennate diatoms (dominant group) are found as relatively tolerant to salinity. Microflagellates have been found to be resistant to salinity up to 26 0/00. Chlorophyll concentrations and rates of primary production of those organisms are as high as those of the control.
Qualitative Analysis of the Pelagic Foodwebs of Three Acid‐impacted Lakes in Nova Scotia, Canada
Authors: Lane Patricia A. , Blouin Anthony
Published: February 2007

Loop analysis is a qualitative network technique which is useful for delineating pelagic foodwebs and for predicting production relationships. Loop models were fitted to data sets for three lakes in Kejimkujik National Park, Nova Scotia. Using qualitative correlation signs, there was 80–89 percent agreement of model predictions and data values. Individual networks were integrated by summarizing linkages between pairs of variables. The resultant core network is a three‐layered structure with 5 nutrient, 4 algae, 1 detritus and 10 zooplankton variables. The phytoplankton components utilize different types of nutrient complexes in each lake. Bluegreen algae have a special relationship to ammonia in Beaverskin Lake. Crustacean zooplankton consume phytoplankton directly whereas rotifers are connected to the foodweb via the detrital pool.

In contrast to the multivariate statistical results reported by Blouin et al. (1984), loop analysis furnished some robust evidence of the inherent structure in these plankton communities. Qualitative methodology also helps identify casual pathways in the ecological networks. The analysis illustrated which links are oscillating the most and which are expected to remain resilient with increasing perturbation. The models suggest several aspects of these communities that could be verified experimentally.
Photosynthetic Activity of Dominant Algal Species in Eutrophic Shallow Lake (Großer Müggelsee, Berlin) Investigated by Microautoradiography
Authors: Nixdorf Brigitte
Published: February 2007

The photosynthetic activity of dominant phytoplankton in eutrophic shallow lake was investigated by the autoradiographic method in 1979 and 1980. It was shown by light and dark field microscopy that all species of Cyanophyta (Oscillatoria redekei, Oscillatoria agardhii, Aphanizomenon flos‐aquae) were characterized by a continuously high uptake of NaH14CO3. Similarly high photosynthetic activity was observed during the occurrence of Cryptomonas sp. and nanoplankton. Contrary to these observations, diatoms showed remarkably high portions of photosynthetically inactive biomass when their development was abundant. The reasons for this discrepancy between high biomass of diatoms and relatively low primary production (measured by the 14C‐method and autoradiography) are discussed.
A Compositional and Structural Analysis of Phytoplankton in Lake Khurpatal, (U.P.), India
Authors: Pant M. C. , Jaiswal Sudha , Sharma A. P.
Published: February 2007

The phytoplankton community in Lake Khurpatal (Kumaun Himalya), India, was analyzed in relation to physico‐chemical variables. Phytoplankton biomass ranged from 2.7 to 20.0 g m−3 in the euphotic zone of the lake. Dinoflagellates monopolized the algal community with a mean annual contribution of 94.5 % to the total phytoplankton biomass. The community coefficient used to quantify the seasonal changes in algal population reflected the fact that successional episodes were not very significant, the percentage similarity among the consecutive algal samples ranging from 47.8 to 89.9 %. The phytoplankton community was characterized by low species richness, low equitability and species diversity. Various ecological characteristics of the community are discussed and the phytoplankton biomass is also compared with that of some tropical and temperate lakes.
The Influence of Photo‐inhibition on the Estimation of Daily Production Computated from Photosynthesis‐light Response Curves Determined in an Incubator
Authors: Vermij Steven G. , Flik Ben J. G. , Rijkeboer Machteld
Published: February 2007

A model is presented which describes the influence of inhibition on photosynthesis as a function of time and light intensity. The model parameters can be estimated from p vs I curves determined by means of an incubator. Daily production computed with the model is compared with that calculated using a model based on a time independent description of photosynthesis‐light response curves. To do this, a hypothetical case study was used, in which the influence of turbulent mixing and recovery from inhibition was also investigated.
Shade‐adapted Algae beneath Ice and Snow in the Northern Bothnian Sea
Authors: Müller‐Haeckel Agnes
Published: February 2007

The winter‐spring phytoplankton flora in the coastal waters of the northern Bothnian Sea consists mainly of marine cold water species even adapted to low light. These dinoflagellates and diatoms seem to be selectively promoted by the seven months of low light and water temperature. They are able to grow during this period of subsaturated light and have their abundance maxima around ice‐break. Solar radiation measured under ice and snow cover was in the same order of magnitude as the compensation points of some of the species. In summer, these algae species vanish from the water, and surely survive in the form of inactive life stages.
Clearance Rates of Crustacean Macrofiltrators: The Nature ofin situRate Depressions in a Fertilized Oligotrophic Lake in the Kuokkel Area, Northern Sweden
Authors: Persson Gunnar
Published: February 2007

Lake seston labelled by14CO2,14C‐acetate and32‐PO4in parallel was used in zooplankton feeding experiments and checked for size distribution of the labelled particulates. Thein situexperiments were made to find out if depressedEudiaptomusandHolopediumclearance rates, in an artificially fertilized lake where seston was dominated by μ‐algae, were due to low retention of such algae.

Addition of a labelled reference alga (Chlamydomonassp.) was used to find out if high food concentrations (above the Incipient Limiting Concentration) or toxins caused the depressions. Clearance rates mostly ranked highest for CO2‐labelled seston followed by32P and14C‐acetate labelled seston, reflecting approximately the size distributions of the labelled food. Clearance rates for the added reference alga were high and similar in the fertilized lake and in an oligotrophic reference lake.

It was concluded that the detected “rate depression” could be explained purely by poor retention of small particles (passive size selection) by the crustaceans studied, but that active food selection offers optional explanations to the experimental results.
Photosynthetic Production of a Brackish Water Community of Chara tomentosa L. and its Dependence on Environmental Conditions
Authors: Libbert Eike , Walter Thomas
Published: February 2007

Net photosynthesis and dark respiration of a natural Chara tomentosa community were continuously recorded. There is a close correlation between net rate of photosynthesis and variations in the PhAR flux under water. The net photosynthesis fluence Px correlates with the PhAR fluence Ix, but the quotient Px/Ix varies seasonally, apparently as a consequence of variations in chlorophyll content following long‐range changes in radiation fluence. No influence of temperature, salinity or pH on net photosynthesis was detected, but water temperature stimulates dark respiration and consequently diminishes net primary production.
Dynamics of the Pikeperch, Stizostedion lucioperca (L.), in Lake Balaton
Authors: Biró Péter
Published: February 2007

The pikeperch populations inhabiting three distinct water areas of Lake Balaton differ in regard of growth. Due to stock depletion, pikeperch in the NE‐basin of the lake grew considerably faster than ten years ago. The annual rate of growth in length (von Bertalanffy's K) varied between 0.09 and 0.19. The specific rate of growth in length (GL) ranged from 0.16 to 0.23 and that of growth in weight (GW) from 0.52 to 0.69. Length and age‐structures of the stocks differed significantly between different areas and years, but the overwhelming majority of the stocks consisted of age‐groups IV–V (98.2–99.3%). From NE to SW, the rates of survival were 34, 29 and 70%, respectively. These differences, and the differences in growth resulted in changes in the productive capacity of the stocks. The ratios of production and biomass were 59% (NE‐basin), 63% (central basin) and 39% (SW‐basin), respectively. The magnitudes of production varied inversely. The 50% retention lengths of the seine nets used in Lake Balaton were 35.0, 35.7 and 42.5 cm with weights of 572, 655 and 1019 g, respectively.
Peculiarities of Philodina roseola (Ehrbg.) (Rotatoria, Bdelloida) – Growth and Reproduction under Various Temperature Conditions
Authors: Lebedeva L. I. , Gerasimova T. N.
Published: February 2007

Most investigations dealing with rotifer reproduction have been performed with populations and not with individuals. At the same time the variations in the growth and reproduction rates of rotifers are of considerable interest. This paper presents the results of investigations carried out by culturing individuals of Philodina roseola during the lifespan of an individual under different temperature conditions ranging from 9 to 35 °C. The paper presents curves showing the growth in length and weight, the periods of maximum growth rate and the maximum sizes of Philodina as affected by temperature conditions. The reproduction rate is investigated at the same time. The variation in egg evolution duration, in duration of the reproductive period and in the egg laying rate are shown under all the conditions investigated. The data serve as a basis for estimating the effect of temperature on the productivity of Philodina roseola.
Simulations in a Plankton Model
Authors: Hendrickson William H. , Reddy Karri S. B. , Shar Albert O.
Published: February 2007

A technique for analyzing the stability of a zooplankton, phytoplankton, nutrient interaction model is described. This is an extension of a two‐dimensional predator‐prey model, incorporating a nutrient food source. In this study difference equations, rather than differential equations, are used to simulate the system since the systems are more easily studied in this formulation. Using only a few reasonable constraints on the system, a remarkable stability is obtained.
An Analysis of the Biotic Community in a Kumaun Himalayan Lake, Nainital (U. P.), India
Authors: Pant M. C. , Sharma A. P. , Sharma P. C. , Gupta P. K.
Published: February 2007

A comprehensive study of phyto‐ and zooplankton and macrozoobenthic components in Lake Nainital showed that species richness was high for plankton and low for macrozoobenthos. The algal biomass was dominated by greens (54 %) and blue‐greens (31 %), the zooplankton population by copepods (84 %), and the macrozoobenthic community by a Tubifex‐Chironomus association constituting≥95 % of the annual number of the macrobenthic invertebrates. Respiration (807.5g C m−2 year−1) surpassed gross production (630.5 g C m−2 year−1). The mean annual ratio between phyto‐ and zooplankton biomass is 3.3 and between phytoplankton and herbivores it is 4.6. If biomass is treated as a measure of crude production, the relationship among the three trophic levels suggests that herbivory is inefficient while carnivory is efficient, because part of the primary production remains unutilized by dominant herbivorous zooplankters, whereas Mesocyclops leuckarti, the sole carnivore, feeds efficiently on rotifers and juveniles of other copepods. The low diversity of different biotic components and the P/R ratio of less than 1 perhaps suggest that the lake is passing through the stage of heterotrophic succession.
Chemical and Microbiological Processes as Regulators of the Exchange of Substances between Sediments and Water in Shallow Eutrophic Lakes
Authors: Ryding Sven‐Olof
Published: February 2007

It is generally believed that excessive P release from lake sediments, i. e. internal P load, is only a problem in deep lakes with stagnant anaerobic bottom waters. However, substantial amounts of P can also be released from sediments in shallow, well‐mixed lakes. The dynamics and magnitude of P release from sediments in these types of lakes are affected primarily by physical factors, such as seasonal variations in water temperature and year‐to‐year differences in water renewal. These factors, in turn, induce chemical and microbiological processes which regulate the exchange of substances between sediments and water. The fractional distribution of sedimentary P and the chelating capacity of the water are also important factors that can provide insights to the processes involved and their quantitative impact on the P status in shallow, eutrophic lakes.
Results Regarding the Food of the Planktic Crustaceans Daphnia hyalina and Eudiaptomus gracilis
Authors: Horn Wolfgang
Published: February 2007

The graph of maximum filtering and grazing rates versus particle size shows that Daphnia hyalina is a microfiltrator and Eudiaptomus gracilis is a macrofiltrator. In contrast to Eudiaptomus gracilis, Daphnia hyalina is also able to utilize larger bacteria (c. 1 μm3) as a food source.
Juvenile Anadromous Atlantic Salmon of Three Lakes of Newfoundland
Authors: Pepper V. A. , Oliver N. P. , Blundon R.
Published: February 2007

Anadromous Atlantic salmon parr (Salmo salar) were captured from three Newfoundland lakes. Yearling and 2 year parr were captured most often in shallow water <2 m deep around lake perimeters and were not abundant at greater depths. The 3+ and 4+ parr age groups were rarely found inshore (<2 m) but were captured in deeper offshore areas. Though the parr population in one deep lake was too small to be estimated by mark‐recapture, estimates of the yearlings plus 2+ age groups in two shallower lakes were 55 and 63 parr ha−1. respectively. No under yearlings were found in lake habitats. Parr density in the three study lakes varied inversely with mean lake depth. Lacustrine parr growth rate was greater than or equal to that of stream dwelling parr. It is concluded that some shallow lakes of Newfoundland provide major rearing areas for juvenile anadromous Atlantic salmon.
Some New and Rare Freshwater Algae from Iraq
Authors: Nurul Islam A. K. M.
Published: February 2007

One new species of Sphaeroplea (S. bourrellyii Islam), and six taxa, hitherto unrecorded from Iraq, namely, Dichotomosiphon tuberosus (A. Br.) Ernst, Johannesbaptistia pellucida (Dickie) Taylor & Drouet, Microcoleus chthonoplastes Thuret ex Gomont, M. lacustris (Rab.) Farlow, Gloeotrichia longiarticulata G. S. West, and Ammatoidea (?) normanni W. & G. S. West are described and illustrated.
A Bloom of the Planktonic Diatom, Cerataulina pelagica, off the Coast of Northeastern New Zealand in 1983, and its Contribution to an Associated Mortality of Fish and Benthic Fauna
Authors: Taylor F. J. , Taylor N. J. , Walsby J. R.
Published: February 2007

A bloom of Cerataulina pelagica dominated the sea area off the north‐east coast of New Zealand for three months in the summer of 1982–83, and has been related to unusually calm conditions associated with an unusually low Southern Oscillation Index. Deaths of benthic shellfish during the bloom were attributed to anoxia induced by the bacterial decay of the diatom cells. Death of bony fish caught on long‐lines was attributed to anoxia and the clogging of the gills with mucilage produced by the diatoms.
Evolution des populations bactériennes dans les sédiments des marais maritimes de l'Ile Grande pollués par I'Amoco Cadiz Evolution of Bacterial Populations in Salt Marsh Sediments of Ile Grande Polluted by Amoco Cadiz
Authors: Vacelet Eveline , Mille Gilbert
Published: February 2007

Microbial investigations on heterotrophic bacteria (MPN counts, adenylates charge, growth rate and enzymatic activities) and hydrocarbon utilizing microorganisms (MPN counts) were carried out during three years in the salt marshes of Ile Grande. The aim was to follow their recovery after oil pollution.

Oil degradation is related to bacterial activity (depending on site, depth in the soil, redox level and hydrocarbon concentrations). The results for the three years show a significant enhancement of the microflora during the first year (corresponding to removal of n. alkanes) followed by a decrease in bacterial activity which persisted for over two years. The activity of the heterotrophic bacterial population is deeply disturbed compared with unoiled sites, and these shifts remain detectable three years after oiling. This study does not modify our previous estimation regarding the recovery of the salt marshes.
Food Size Spectra and Species Replacement within Herbivorous Zooplankton
Authors: Hessen Dag Olav , Nilssen Jens Petter , Eriksen Tone Oksum
Published: February 2007

The relationship between two commonly co‐occurring filter‐feeders; Bosmina longirostris and Eudiaptomus gracilis at different nutrient levels, was investigated in bag experiments in Lake Gjersjøen. At the start of the experiment, the numerical relationship between Bosmina and Eudiaptomus was less than 1 : 10, but during the experimental period, a strong increase in Bosmina and a corresponding decrease in Eudiaptomus and medium‐sized algae (5–25 μm) was observed. The shift from Eudiaptomus to Bosmina was probably due to strong competition on mediumsized algae while Bosmina in addition may utilize smaller algae and bacteria, not available to Eudiaptomus. Their coexistence in the lake at much lower densities is probably due to a strong selective fish predation, suppressing Bosmina.

Daphnia longispina, not naturally occurring in the lake, showed strong competitive abilities in a fish‐free bag.
Fatty Acids in Lipids from Particulate Organic Matter in a Eutrophic Lake, Lake Nakanuma, Japan
Authors: Miyazaki Tatsuo , Irie Junko , Ogawa Yoshio , Ichimura Shun‐Ei
Published: February 2007

The depth profiles and seasonal abundance of fatty acids in lipids from the particulate organic matter in the eutrophic Lake Nakanuma, Japan, were closely related to both photosynthetic activity and the distribution of phytoplankton. The changes in the relative proportions of the fatty acids suggest that their synthesis is directly related to the photosynthetic activity of phytoplankton.