bluuebunny/crossref_metadata_2025 huggingface dataset:
Cave Fauna of Bermuda
Authors: Sket Boris , Iliffe Thomas M.
Published: February 2007

Sea‐level pools are found in most of Bermuda's known caves. Although the terrestrial fauna of the caves is sparse, a rich aquatic fauna inhabits the pools. While many of the marine cave animals are more or less regular immigrants from open littoral habitats, a number of new species have been discovered, including blind and probably subterranean ones. Zoogeographical connections exist between Bermuda's cave fauna and those of the West Indies and the Mediterranean.
Primary Productivity and Activity Coefficients of the Phytoplankton of a Mesotrophic Soft‐Water Lake (Piburger See, Tirol, Austria)
Authors: Rott Eugen
Published: February 2007

Phytoplankton primary production was measured using the14C method once per month from 1973 through 1976 as part of an intensive ecosystem study of a small eutrophic soft‐water lake, under restoration since 1970. Relationships among phytoplankton production, species composition, chlorophyll a content, bacteria, zooplankton and a variety of abiotic environmental factors have been studied. Productivity normally showed one peak in spring and another in summer, whereas a minimum was reached under the ice cover in February or March. Maximum production rates in the depth profile ranged from 3 to 144 mg C · m−3· d−1, integral production from 6 to 510 mg C · m̄−2· d−1. Species of Cyanophyceae, Dinophyceae, Chlorophyceae and Chrysophyceae dominated alternately and showed significant differences in the level and variation of photosynthetic activity. Maximum activity was observed in summer. A high biomass increase during late winter and spring despite low primary productivity resulted from the immigration of the dominant blue‐green alga,Oscillatoria limosa, from the sediment. Energy efficiency increased not only with depth in the light‐limited parts of the euphotic zone but at all depths during bad weather conditions and during the decrease of irradiance in autumn.
Photosynthetic Efficiency in Lawson's Bay on the East Coast of India
Authors: Rao D. V. Subba
Published: February 2007

Seasonal variations in the efficiency of utilization of radiant energy by phytoplankton photosynthesis in a tropical embayment followed the same pattern as that of primary production. showing that incident radiation did not limit phytoplankton production. Peak values in primary production and photosynthetic efficiency coincided with periods of nutrient enrichment caused either by upwelling during the southwest monsoon or by run‐off during the northeast, monsoon. A world‐wide comparison of published data on photosynthetic efficiencies in different latitudes showed that higher efficiency is achieved in the tropics, where the values are similar to those observed on phytoplankton cultures. Based on the maximum efficiency of photosynthesis attained, three regimes can be recognized in tropical waters: 1) regions of upwelling with a maximum of 6%,. 2) coastal bays with 0.7%, 3) oceanic regions with 0.24%.
The Nature of Selected Prairie Lake and Stream Sediments
Authors: Oscarson Dennis W. , Rogers J. Scott , Huang Pan M. , Liaw Wen K.
Published: February 2007

The mineralogy and related chemistry of selected lake and stream sediments from the upper Qu'Appelle River basin in southern Saskatchewan, Canada, was examined. The principal crystalline clay minerals present in the colloidal fractions of the sediments are smectite, vermiculite, kaolinite, mica, quartz, and feldspar. The cation‐exchange capacity of the sediments varies from 16.3 to 28.8 meq/100 g, and the pH ranges from slightly acid to mildly alkaline. The hydrous oxides of Al, Fe, Mn, and Si are present in significant quantities in both the colloidal and noncolloidal fractions of the sediments; this is significant because these oxides likely exert the dominant chemical control on the movement of many nutrients and pollutants in aquatic environments. Calcium and Mg carbonates comprise a significant fraction of the sediments. Most of the C in the sediments is in the organic form; the organic C content varies from 1.2 to 6.0%. Because crystalline clay minerals, poorly ordered sesquioxides, and organic matter play a vital role in the retention and cycling of nutrients and pollutants in aquatic environments, a knowledge of the nature and properties of sediments is fundamental to efforts to preserve and improve the quality of natural water systems.
The Mechanics of Penetration by the Fruit of Bidens cernua L (Compositae) into the Cephalic Region of Cyprinids
Authors: Heckman Charles W.
Published: February 2007

The dry, indehiscent fruit of Bidens cernua L. occasionally becomes deeply embedded in the head and jaws of small cyprinids. The tips of the fruit spines are equipped with a set of three barbs. If a fish comes into contact with one of the many such fruits that fall into the water during autumn, one of the barbs can easily penetrate the skin. When the tip of the barb becomes anchored beneath a scale or small bone, movements of the fish will tend to cause the fruit to rotate around that point, forcing the tip of the spine into the flesh by a lever action with a mechanical advantage of about 50. Barbs on the shaft allow the spine to work deeper but prevent its extraction, even when the fruit becomes entangled among submerged plants. Such attachments, which lead to the death of the fish, occur regularly, but not enough fishes are affected to cause serious problems for aquaculturists. The possibility that the decomposing fishes provide nitrogen sources for the sprouting plants is discussed.
Relationship between Chlorophyll‐α Concentration and Phytoplankton Biomass in Several Reservoirs in Czechoslovakia
Authors: Desortová Blanka
Published: February 2007

Parallel determinations of phytoplankton biomass and chlorophyll‐α concentration were carried out on five reservoirs. Highly significant positive correlations between phytoplankton biomass values and chlorophyll‐α values were found. The possibility of finding a conversion factor linking these two parameters is discussed. The chlorophyll content per unit phytoplankton biomass encountered during the period of study in all reservoirs varied between 0.14 and 3.41% of fresh weight. The influence of light intensity, nutrient concentration and species composition on chlorophyll content per unit phytoplankton biomass is considered.
The Physico‐Chemical and Planktonic Response of an Algicide — Treated Shallow Mountain Lake in Arizona
Authors: Schwartz Steven S. , Blinn Dean W. , Johnson Glen
Published: February 2007

The physico‐chemical and planktonic response and recovery of a shallow mountain lake in Arizona was closely monitored for a 2 1/2 year period following treatment with an algicide. The influential role blue‐green algal blooms exert on seasonal and annual lake dynamics was most obvious once nuisance populations were temporarily removed from the system. Differential sensitivity between algal species was observed. Cryptomonad flagellates were least sensitive to algicide treatment and were dominant during periods when dissolved organic materials appeared to increase. The effect of rotenone application on blue‐green bloom species is discussed.
Inhibitory and Toxic Effects of Blue‐green Algae on Daphnia
Authors: Lampert Winfried
Published: February 2007

The effects of the planktonic blue‐green algae, Aphanizomenon gracile, Synechococcus elongatus, and Microcystis aeruginosa, on survival, growth, and food uptake of Daphnia pulicaria were determined. Synechococcus and Aphanizomenon were unsuitable food when offered alone, but did not affect the daphnids negatively when mixed with Scenedesmus. Microcystis was the only one found to be toxic. In pure suspensions of this blue‐green, the daphnids did not survive more than 48 hours; they lived a little longer if Scenedesmus was supplied additionally. Growth was markedly reduced when only 50 μg carbon/l of Microcystis was added to the normal Scenedesmus food. It ceased at a concentration of 250 μg C/l. This can be explained by the reduction of food uptake. Very small quantities of Microcystis (10 μg C/l) present in the normal food caused a significant reduction of the filtering rate. Filtering inhibition was associated with the cells. Filtrate of Microcystis suspensions was not effective. Thus, the daphnids must ingest the blue‐green cells in order to become toxified. Dual‐labelling experiments showed that Microcystis cells are filtered from the medium by Daphnia with the same efficiency as Scendesmus and are not rejected. Toxicity of Microcystis is considered to be an effective defence mechanism against grazing pressure.
Coral Bioerosion at Enewetak: Agents and Dynamics
Authors: Highsmith Raymond C.
Published: February 2007

Significant differences were found in the extent to which massive coral species at Enewetak are excavated by boring organisms:Goniastrea retiformis, 7.9%;Porites lutea, 2.5%; andFavia pallida, 1.2%.

While polychaetes constituted the most abundant and diverse group of coral associates, clionid sponges accounted for approximately 70–80% of skeletal damage. Clionid boring rates are initially very high but burrowing ceases when a particular burrow size (˜0.6 cm) or distance from the surface (≦2 cm) is reached.

Most coral skeletal excavation occurs within 2 cm of a dead surface. Therefore, bioerosional damage to corals depends primarily on the amount of skeletal surface not covered by live coral tissue. Damage to skeletons is inversely correlated with colony size but is not correlated with coral growth rates or water depth. Massive corals have a potential escape in size from catastrophic bioerosion.

Models relating 1) coral growth forms to skeletal density and stability in currents, 2) resistance of coral skeletons to breakage by water movement and suspended rubble, and 3) dead surface area on coral heads to bioerosional damage and consequent probability of detachment from the substrate, are proposed.
Phytoplankton and Nutrients in Goat Island Bay, New Zealand
Authors: Taylor F. J.
Published: February 2007

A quantitative study of the phytoplankton and nutrients in Goat Island Bay, northern New Zealand, was carried out at two stations of depths 7 m and 20 m in 1966‐69. There were significant differences in the concentrations of the phytoplankton at the two stations, the deeper station having, in general, higher concentrations than the shallower.

Low phytoplankton standing crops were found in winter when the increased run‐off from the land resulted in lower salinities, higher turbidity, and higher dissolved silicate levels. The spring growth of diatoms was dominated by small diatoms (Cylindrotheca closterium, Leptocylindrus danicus, Nitzschia pseudoseriata, Phaeodactylum tricornutum, and Rhizosolenia delicatula). Occasionally it was dominated by a population of large centric diatoms (Chaetoceros spp., Coscinodiscus spp., Thalassiosira spp.), but these appeared to be found in a separate water mass which entered the bay and displaced the resident water mass. A third water mass entered the bay in spring and was characterised by the coccolithophore Emiliana huxleyi and a lower temperature.

During the summer diatoms dominated the phytoplankton population, but were replaced by dinoflagellates for a short period in autumn.
Invertebrate Sampling in the Substratum of an Experimental Recirculating Stream
Authors: Welton J. Stewart , Ladle Michael , Bass Jon A. B. , Chapman Kevin
Published: February 2007

In order to determine the efficacy of sampling benthic invertebrates to a depth of 100 mm as compared with 200 mm, the gravel substratum of an experimental recirculating stream was sampled to both depths. Except for 6 taxa which were significantly more numerous in the shallower samplers, there was no significant difference between the densities determined from the two depths.
Phytoplankton and Epiphyte Development and Their Shading Effect on Submerged Macrophytes in Lakes of Different Nutrient Status
Authors: Sand‐Jensen Kaj , Søndergaard Morten
Published: February 2007

The annual mean light intensity at the depth limit of the Littorella vegetation was 24–33% of the subsurface light intensity, despite large variations in each attenuation component (lake water, phytoplankton, and epiphytes). In oligotrophic, silicate‐poor lakes, the light attenuation above the submerged vegetation was dominated by the water itself, which accounted for 65–72% of the total attenuation. Phytoplankton and epiphytes were equal in importance to each other. In oligotrophic, silicate‐rich lakes and lakes receiving a nitrogen supply above background level, the epiphytes were more abundant, accounting for about 50% of the light attenuation. In one lake with a high nutrient supply, the epiphytes were responsible for 86% of the light attenuation.

A new method of measuring the effect of shading by the epiphytic community on submerged macrophytes is presented. The light attenuation caused by the phytoplankton and the epiphytes was investigated and related to the depth distribution of the submerged angiosperm, Littorella uniflora.

It is shown that the biomass of the epiphytes increased more than the biomass of the phytoplankton in response to an external or internal nutrient loading. Shading by epiphytes is of decisive importance for the depth distribution of Littorella at increasing nutrient supply.
Toxic Blue‐green Algae Water Blooms Found in some Lakes in the German Democratic Republic
Authors: Henning Manfred , Kohl Johannes‐Günter
Published: February 2007

From 1977 to 1979 plankton samples were taken from 6 lakes in the German Democratic Republic (GDR) during water blooms and examined for their toxicity to homothermal animals. Microcystis aeruginosa, Aphanizomenon flos‐aquae, Anabaena spiroides, and Oscillatoria redekei were dominant in the samples. With the exception of Oscillatoria redekei the algae tested had toxic effects on mice after intraperitoneal injection. The rate of survival of the test animals was particularly low when the algae were disintegrated by ultrasound or freeze‐drying prior to injection, this indicating the endogenic character of the toxins. Water blooms of Microcystis aeruginosa taken from Lake Pehlitzsee (Eberswalde District) showed the highest toxicity with an LD30 as high as 45 and 43.7 mg/kg, respectively. Injection of the lyophilized cells of Aphanizomenon flos‐aquae brought about the same symptoms in the test animals as in the case of Microcystis, but the LD30 was 200 mg/kg.
The Re‐establishment of Meromixis in Hemlock Lake, Michigan, After Artificial Destratification
Authors: Fast Arlo W. , Tyler Peter A.
Published: February 2007

The limnological characteristics of meromictic Hemlock Lake, Michigan, are outlined. The changes brought about by artificial destratification, and those accompanying re‐establishment of meromixis, are then described. A mechanism for the return of meromixis is suggested, and its events compared with an analogous case in a Tasmanian reservoir.
A Thiobios Does Exist ‐ Gnathostomulid Domination of the Canyon Community at the East Flower Garden Brine Seep
Authors: Powell Eric S. , Bright Thomas J.
Published: February 2007

A community of organisms dominated by gnathostomulids has been discovered at the East Flower Garden Brine Seep. This discovery clearly demonstrates that specialized communities of micro‐metazoans exist in and below sulfide‐dependent chemoclines. The term thiobios should be retained to describe these communities.
The Manna Effect: The Structure of Benthic Populations
Authors: Wangersky Peter J. , Wangersky Charles P.
Published: February 2007

The effects of randomness of food supply on the composition of a model community with a single trophic level was studied by the use of a Monte Carlo model. Many of the features of benthic communities, including co‐existence of many species in apparent species mosaics, can be seen to be responses to the random food distribution. Measures of diversity and species dominance may actually be indirectly indicating rate of food supply.
Phytoplankton Losses due to Zooplankton Grazing in a Drinking Water Reservoir
Authors: Horn Wolfgang
Published: February 2007

Phytoplankton losses due to zooplankton grazing in the Saidenbach drinking water reservoir were calculated on the basis of laboratory experiments and field studies. The dependence of grazing rate and filtering rate on phytoplankton concentration, temperature and other factors is described.
Paleolimnology of Two Shallow Lakes in Central Alberta, Canada
Authors: Forbes J. R. , Hickman M.
Published: February 2007

An interpretation of postglacial change in water quality and productivity has been made for two shallow lakes in Central Alberta, Canada, namely Hastings Lake (longitude 113° 00′ W; latitude 53° 30′ N) and Lac Ste. Anne (longitude 114° 21′ W; latitude 53° 41′ N). Erosion rates around Lac Ste. Anne have remained constant. Similarly productivity has changed little although macrophytes contributed more to total production during the early stages. Hastings Lake has responded more sensitively to changes in the balance of precipitation and evaporation. From 5500 to 4000 year B. P. it was shallower than at present. Productivity during this early phase was less but macrophytes and allochthonous organic matter (i. e., leaf litter) probably contributed a greater proportion of the organic influx. After water levels rose productivity increased remaining steady until 2500 year B. P. when a slight decline occurred. Throughout the high water period oxygen depletion has not been serious. Any period of reducing conditions has been brief. Productivity has never been nutrient‐limited. Elevation of the lake surface increased potential volume for production and reduced turbulent resuspension of bottom sediments permitting greater light penetration, and enhanced algal production. Difference between the sedimentary record of these two lakes, as well as the two basins of Hastings Lake, demonstrates the individualistic responses of basins and lakes to climatic events.
Determination of the Limiting Plant Nutrient in the Water of Lake Balaton by Algal Assay Procedure
Authors: Dobolyi Elemér , Ördög Vince
Published: February 2007

Algal assays were performed on water samples taken from different sites in Lake Balaton. Selenastrum capricornutum was used in the test to determine the primarily limiting plant nutrient. The results of supplementary nutrient additions to the bottle tests were evaluated by cell counts. The tests have indicated phosphorus as growth rate limiting, and in two cases as biomass limiting plant nutrient, but periodic occurrences of nitrogen limitation cannot be excluded.
Revision of the Genus BosminaBAIRD, 1845 (Crustacea, Cladocera)
Authors: Lieder Ulrich
Published: February 2007

The genus Bosmina can be differentiated into four subgenera: 1. Bosmina s. str. BAIRD, 1845, 2. Eubosmina SELIGO, 1900, 3. Neobosmina LIEDER, 1957, and 4. Sinobosmina LIEDER, 1957. Subgeneric discrimination is based upon several features of the females (postabdominal claw, serration of the mucro, patterns of the lateral head pores) and, mainly, upon certain differences in the morphology of the male (postabdomen and, according to LILLJEBORG 1900, BURCKHARDT 1924 and KOŘINEK 1971, the first leg). The distribution of the Bosmina subgenera throughout the world varies: Bosmina s. str. is distributed worldwide (except for Australia?), Eubosmina is holarctic, Neobosmina has been found in Africa, the neotropical zone, Australia and Oceania, and Sinobosmina occurs in East and South‐East Asia.
Qualitative and Quantitative Interactions between Microphytobenthos and Herbivorous Meiofauna on a Brackish Intertidal Mudflat
Authors: Admiraal Wim , Bouwman Lukas A. , Hoekstra Leo , Romeyn Karin
Published: February 2007

Micro‐ and meiofauna are the predominant consumers of diatoms on a brackish intertidal mudflat. The impact of grazing on the benthic diatom populations was studied by field observations and feeding experiments on a few abundant members of the community. Only small fractions of the microphytobenthic biomass and production are converted by herbivores. A hypothesis is presented explaining the growth kinetics and productivity of diatom populations and the inefficient transfer of carbon into herbivore foodchains. Data on feeding rate and population dynamics of the nematode species, Eudiplogaster pararmatus, are discussed in view of the seasonal succession of edible diatom species.
The Recovery of the Biotic Community in a Lotic Freshwater Habitat after Extensive Destruction by Chlorine
Authors: Heckman Charles W.
Published: February 2007

The recovery of a temperate zone biotic community in a lotic freshwater habitat after acute chlorine poisoning was nearly completed in four months (May to September). This was facilitated by the water flow, which rapidly removed the toxic residues of the chlorine and transported organisms from the intact community upstream into the impoverished habitat. The first aggregation in the ditch after the chlorine was eliminated consisted of survivors, including members of species that failed to produce new generations. These were joined by pioneer species of the families Simuliidae and Chironomidae, the larvae of which appeared in massive numbers. This aggregation was displaced by a more diverse fauna as the macroflora and microbiota re‐established themselves, providing food and anchorage for the invertebrates. The populations of large fishes are slowest to return because a considerable amount of time is required for the migration and growth of the recruits. While the chronic intoxication of a habitat produces changes in community structure, an acute poisoning is followed by a nearly complete restoration of the original biota, the recovery time being determined by the proximity of recruits for resettlement.
Pelagic Diatom Populations in Lentic Freshwater Microcosms
Authors: Harte John , Levy Donald , Rees John T.
Published: February 2007

Three experiments, involving simultaneous monitoring of selected biological and chemical parameters in 50 l laboratory microcosms and the epilimnia of their parent reservoirs, were carried out from the autumn of 1978 to the winter of 1980. Experiments lasted 8‐13 weeks, their aim being to ascertain degree of similarity between laboratory and field systems. Microcosm dynamics, specifically diatom dynamics, most closely paralleled that found in reservoirs during late spring and early summer, a time of thermal stratification. During winter months when thermal stratification was absent or less pronounced, microcosm diatom populations diverged significantly from reservoir populations within 24 days. It is inferred that microcosm design and operating conditions have a major bearing on microcosm usefulness for environmental assessment.
Introgression as a Factor in the Evolution of Polytypical Plankton Cladocera
Authors: Lieder Ulrich
Published: February 2007

The genera Bosmina and Daphnia offer considerable taxonomical difficulties due to the existence of a very great number of different races. An attempt has been made to understand this phenomenon mainly as the result of introgressive processes.
Selective Predation in Freshwater Zooplankton Communities
Authors: Greene Charles H.
Published: February 2007

The impact of selective predation in freshwater zooplankton communities is examined with special emphasis on the ecological and evolutionary consequences for the prey. The behavioral interactions between predators and prey are reviewed, and the general patterns in age‐ and size‐selective predation are derived in a semi‐quantitative model. The final section explores the life history adaptations that zooplankton have evolved in response to these different patterns of selective predation.
The Manna Effect: Paradox of the Plankton
Authors: Wangersky Peter J. , Wangersky Charles P.
Published: February 2007

A Monte Carlo model of a multi‐species community with a single trophic level, with nutrients supplied randomly in space and time, demonstrates an irreducible variability in species number and composition. Competition between closely similar species does not necessarily proceed to the elimination of the less efficient species because the variability in food supply becomes a more important factor in survival than does even a fairly large difference in efficiency.
Production and Ecology of Benthic Chironomid Larvae (Diptera) in Lake Hayes, New Zealand, a Warm‐monomictic Eutrophic Lake
Authors: Graham Alan A. , Burns Carolyn W.
Published: February 2007

The distribution and abundance of larval chironomids in Lake Hayes were studied from December 1973 to March 1975. The mean annual production of the two dominant species, Chironomus zealandicus and Chironomus sp. a, was 29.2 g m−2 dry weight which is approximately 4.3 % of the average annual phytoplankton production in the lake. A high annual P/B ratio of 18.5 is consistent with the multivoltine life cycle of C. zealandicus. Larval chironomid production in the second summer when Anabaena blooms were absent was only one quarter of that in the first summer and is consistent with the hypothesis that the production of benthic chironomids in Lake Hayes is closely linked to that of the phytoplankton through the sedimentation of autochthonous organic matter.
The Possible Importance of Primary Amino Nitrogen in Nitrogen Regeneration by Coastal Marine Sediments in Buzzards Bay, Massachusetts
Authors: Christensen John P. , Rowe Gilbert T. , Clifford Charles H.
Published: February 2007

To investigate the role of primary amino nitrogen (PAN) in nitrogen regeneration by marine sediments, the distribution and fluxes of PAN in organic‐rich coastal sediments off Massachusetts (USA) were investigated. Decreases with depth in the sediment of total organic carbon, organic nitrogen, and PAN contents indicate that organics with C to N ratios of about 6, such as primary amines, are selectively consumed. Near the sediment surface, dissolved PAN (DPAN) accumulates and supports a large DPAN flux into the water column and this flux greatly exceeds the inorganic nitrogen flux. Consumption of C, N, and PAN was investigated using diagenetic equations describing their exponentially decreasing distributions with depth and which included the effects of sediment mixing, sediment accumulation, and consumption, considered to be a first‐order reaction rate. Calculations showed that the reaction rate constant for PAN was between 5.1 and 26.1 times faster than that for the utilizable organic N and the depth‐integrated consumption of PAN accounted for between 8.6 and 43.9% of the N disappearance rate. These ranges are estimated when sediment accumulation dominates over sediment mixing (the lower values) and when mixing dominates over accumulation (the upper values). Although the magnitude of D is unknown, these calculations indicate that PAN, which comprises less than 2% of the organic N, has an important role in sedimentary nutrient dynamics because of its enhanced reactivity.
The Seasonal Relationship Between Meroplankton and Megabenthos on Georges Bank, Gulf of Maine, Northwest Atlantic
Authors: Maurer Don , Toner Richard C.
Published: February 2007

A broad based environmental study of Georges Bank included samples of zooplankton and dredge samples of megabenthos for four seasons. The purpose of this account is to examine the seasonal relationship between meroplankton and megabenthos.

Mean densities of meroplankton were relatively high at shallow near shore stations and the central Bank and low at deeper stations. Densities were highest in the summer and lowest in the winter for major taxa. For megabenthos the number of species, relative abundance and relative biomass was also highest in the summer and lowest in the winter. Dominant megabenthos provided year round occupants and seasonal pulses. Year round occupants and seasonal peaks of some megabenthos facilitate year round foraging by demersal finfish enhancing the general production of the Bank. It was concluded that Georges Bank megabenthos was part of a broad ranging continental shelf, sand bottom fauna extending at least from Gaspe Bay to the offing of Chesapeake Bay.
Etude préliminaire des effets de la mise en eau du Réservoir de LG‐2 (Territoire de la Baie James, Québec) sur le seston grossier et le zooplancton des rivières et des lacs inondés
Authors: Pinel‐Allout Bernadette , Méthot Ginette
Published: February 2007

Preliminary Study of the Effects of Impoundment of LG‐2 Reservoir (James Bay Territory, Quebec) on the Net Seston and the Zooplankton of Impounded Rivers and Lakes

The effects of impoundment on the biomass of net seston and zooplankton in lakes and rivers of Northern Quebec were investigated from 1978 to 1980, before, during and after the completion of LG2 Reservoir on the River La Grande (53° 54′ N, 76° 78′ W). In lotic stations, a 41–77% decrease in net seston was observed due to sedimentation of mineral particles (36–80 mg/m3 in 1978 to 10–21 mg/m3 in 1979). The ratio of organic to total seston increased from an average of 0.18 before the impoundment to 0.65 after. The flooding phase brought about a trophic upsurge; the biomass of the zooplankton increased by one to two orders of magnitude at the various sites; the greatest increases occurred in the central stations near the dam, the smallest in the upper stations near the inflow. In lake stations, no significant difference between years could be detected; the mean zooplankton biomass for all three years ranged from 6.59 mg/m3 to 34.34 mg/m3. Spatial variations between lakes were however significant. Results are compared with those in other natural lakes in Canada and reservoirs in the United States. Comparative examination of phytoplankton biomass before and after impoundment of LG2 Reservoir suggests that bacterioplankton and allochthonous organic material are key elements in the pelagic food chain after impoundment.
Abundance and Community Structure of Limnetic Zooplankters in Kumaun Lakes, India
Authors: Sharma P. C. , Pant M. C.
Published: February 2007

The zooplankton compositions in the limnetic zones of two subtropical lakes, the Nainital and the Bhimtal (U.P., India) were more or less similar in terms of species composition. Numerically, zooplankters were abundant during the thermal stratification (summer‐autumn) period and scarce during the over‐turn (winter). The density of the zooplankton population reported from the eutrophic Lake Nainital was higher than in the oligotrophic Lake Bhimtal. Among the three groups studied copepods dominated over cladocerans and rotifers in both the lakes. The Shannon Weaver diversity was higher for Lake Bhimtal than for Lake Nainital. The community structure has also been discussed on the basis of crustacean species.
The Effects of Sampling Intervals on Phytoplankton Growth and Loss Values Derived from Seasonal Phytoplankton Biomass Variations in an Artificial Lake
Authors: Horn Heidemarie
Published: February 2007

Detailed vertical phytoplankton sample series with a good resolution were taken every 3–4 days for almost two years from the artificial Lake Saidenbach. The intervals between samplings were systematically increased by regularly “ignoring” certain samples so that six different annual curves based on different sampling frequencies were obtained to describe phytoplankton variations in the course of the year from a single time series. In this way it was possible to study the effect of the interval between samplings on the results of phytoplankton studies and on the rates of change and turnover calculated from the biomass. The results show that the maximum rates of change and turnover values yielded by half‐weekly samplings are some 20–30% higher than those yielded by weekly samplings. Sampling intervals smaller than 3–4 days yield not much increased rates of change and turnovers. This implies that short term changes in the phytoplankton are more accurately detected by half‐weekly samplings. It is therefore suggested that, depending on the nature and objectives of the investigations, sampling intervals of 3–4 weeks are sufficient for the winter, but during the growth period (spring to autumn) samples should be taken at least once a week or fortnightly.
Prolongation of Postembryonic Development in Experimental and Natural Cladoceran Populations
Authors: Romanovsky Yuri E.
Published: February 2007

One of the methods for determining the duration of postembryonic development is the calculation method suggested by Gras and Saint‐Jean (1978) for populations with continuous reproduction and stable age distribution. After inserting time‐weighted means for instantaneous birth rates into the formula, it is possible to calculate the growth rates of the juveniles during each interval between obersvations for a non‐stationary population. Estimated values were in a good agreement with those obtained from computer‐constructed populations and determined directly from a natural cladoceran population. The duration of postembryonic development in cladoceran populations increases significantly during periods of food depletion caused by filtering activity of herbivorous zooplankton. This physiological response together with the decrease in age‐specific fecundity permits effective regulation of population abundance through the birth rate.
A Mathematical Submodel for the Planktonic Rotatoria in the Ecosystem of the Barther Bodden (Southern Baltic Sea)
Authors: Vietinghoff Ulrich , Hubert Marie‐Luise , Heerkloss Reinhardt , Arndt Hartmut , Schnese Werner
Published: February 2007

Of the rotifers inhabiting the shallow eutrophic Barther Bodden, the pelagic species feeding on fresh detritus comprising dead diatoms and green algae are of particular importance in terms of biological production. The submodel presented here refers only to this functional group (Filinia longiseta, Brachionus quadridentatus and Keratella cochlearis). The biological situation, the working hypotheses, the equation system, the measured values and coefficients used and the wiring diagram are given. The curves obtained with the model are shown in detail and tested against various criteria. Agreement between the model curves and the measured data is good.
Measurements of some Groups of Microbial Populations with Special Reference to Denitrification in Water and Sediments of Fish Farming Ponds under Mono‐ and Polyculture Systems
Authors: Jana B. B. , Patel G. N.
Published: February 2007

The spatial and seasonal distribution of some groups of bacteria as well as the rates of denitrification (natural and potential) have been investigated in water and sediments of four fish farming ponds under monoculture, traditional and polyculture systems in India. Marked differences in the monthly means of bacteria were found to exist in these fish ponds depending upon their trophic statuses. The seasonal changes of bacteria are discussed in relation to the variation of environmental factors.
A Quantitative Comparison of Two Zooplankton Sampling Methods, a Plankton Trap and a Towed Net, in the Baltic
Authors: Kankaala Paula
Published: February 2007

A comparison between a large plankton trap with a capacity of 23 litres and a modern towed net was made in the course of zooplankton production studies in the Baltic. On the average, the net efficiency was 75% of that of the trap. Both methods were equally efficient in catching naupliar stages of copepods. The net efficiency was especially low during the zooplankton maximum for adult copepods and cladocerans (41 and 51%, respectively), probably due to the active avoidance of the net by fast swimming species. The net was only about 66% as efficient as the trap for catching rotifers. This difference is probably caused by the loss of small and softbodied forms through the mesh. Only about 65% of the total zooplankton biomass retained in the trap was collected by the net. Net sampling is not recommended for quantitative zooplankton studies.
Manipulation of the Pelagic Food Web by Stocking with Predacious Fishes
Authors: Benndorf Jürgen , Kneschke Helmut , Kossatz Kathrin , Penz Eckhard
Published: February 2007

Two water bodies, which are quite different with respect to nutrient load and hydrophysical conditions, are used to perform long‐term experiments in the whole water on the manipulation of the pelagic food web. Experimental water 1: Bautzen Reservoir (Dresden County, GDR); hypereutrophic, mean depth=7.4 m; extremely exposed to wind. Experimental water 2: Small pond in a former quarry (Dresden County); mesotrophic; mean depth=7.0 m; extremely protected against wind. Only the results of Experiment 2 are given in detail. Experiment 1 is not yet finished.

Experimental water 2 was investigated in 1979 and 1980 when no predatory fish species were present, and in 1981 after introduction of predators (mainly Salmo gairdneri). The response of the ecosystem can be summarized as follows: (1) The biomass of the zooplankton‐eating fish (mainly Leucaspius delineatus) decreases rapidly. (2) The biomass of the herbivorous zooplankton increases to nearly 400%. (3) This finding reveals that the dense population of an invertebrate predator (Chaoborus flavicans) is not able to compensate for the feeding pressure of the small fish. But the intensive feeding activity of the young larvae of Chaoborus leads to a strong increase (200 to 300%) in the mean individual body size of the crustaceans during late summer and autumn, which supports the “balanced predation hypothesis”. (4) The remarkable enhanced grazing pressure of the herbivorous zooplankton on the phytoplankton does not exert any effect on the total phytoplankton biomass. This result is interpreted as a consequence of growth limitation of the algae due to low nutrient (Fe, P) supply in that mesotrophic water body. But the phytoplankton composition does reveal a strong response to the enhanced grazing pressure. The Secchi depth increases as a consequence of this change in the phytoplankton composition.

The conclusion is drawn that, when using biomanipulation as a means of water quality management, it is obviously necessary to take into account the complex interrelationships between fish stocks, predacious invertebrates, herbivorous zooplankton, phytoplankton as well as nutrient load and hydrophysical processes in the particular water.
Organic Carbon in a Eutrophic Fishpond
Authors: Blažka Pavel , Procházková Lidmila
Published: February 2007

Accumulation of dissolved organic carbon (DOC) was studied in a eutrophic pond and in cultures of Scenedesmus abundans. Samples of pond water and media were treated with a cation exchanger in Na cycle and chromatographed on Sephadex G 25 and G 10. — UV spectra of the peak fractions were recorded. In the pond about half of the organic carbon is in fractions with an apparent molecular weight (AMW) of 500–1000, while in the algal medium (after cultivation) most of organic carbon has an AMW of about 120. These and spectral data did not suggest that aromatics and compounds with conjugated double bonds were major organic constituents of DOC.
A posteriori Investigation of Spatial Arrangements in Gnathostomulida and Copepoda
Authors: Farris Richard A. , Lindgren Eric W.
Published: February 2007

Copepods at MHTL and gnathostomulids from MHTL to sublittoral sands were studied in 162 samples from Tucker's Town Cove beach, Bermuda. Species were analyzed for mean density (X̄), mean crowding (
equation image
), and patchiness (
equation image
/X) using Lloyd's a posteriori statistic for mean crowding. Diversity was computed using the Shannon‐Wiener Index (H′). Copepoda were found to be nearly three times more abundant than Gnathostomulida at the MHSL site. 74% of the copepods were found in the surface cm of sediment while 87% of the gnathostomulids were located between 1–4 cm deep and within the RPD layer. Similar gnathostomulid distributions were found at MSL and sublittorally. Mean density and mean crowding were highly variable for the numerically dominant species in each group, whereas patchiness was relatively constant with values ranging between
equation image
/X̄ = 1.50 to 2.73 for P = 0.05. Such consistency in patchiness between two diverse taxa having distinctly different vertical distributions may suggest that there exists an optimum degree of patchiness for interstitial fauna and that the optimum values may lie within a range similar to that of the numerically dominant Copepoda and Gnathostomulida. Overall patchiness was slightly higher in the gnathostomulids and in the rarer species as predicted by Lloyd's statistic. Diversity was higher in the Copepoda, attributable primarily to species richness.
Potential Mobility of Phosphorus in Different Types of Lake Sediment
Authors: Boström Bengt
Published: February 2007

The fractional composition and potential mobility of sediment phosphorus was investigated in a number of Swedish lakes with different characteristics. Differences between sediments regarding P release patterns in laboratory experiments with varying pH and redox conditions could largely be explained by differences in the fractional composition of the sedimentary P. Sediments from sewage‐loaded lakes contained considerably more loosely adsorbed P than unpolluted lakes. P release was redox‐sensitive and strongly favoured by high pH values in sediments with a high content of aluminium and iron‐bound P. Other sediments released primarily organic and loosely adsorbed P, and in such cases less P was released and redox and pH conditions had less effect. Comparisons with P release rates determined by mass balance calculations were made.
The Seasonal Succession of Epiphytic Communities within an Equisetum fluviatile L. Stand in Lake Pääjärvi, Southern Finland
Authors: Kairesalo Timo
Published: February 2007

The seasonal succession of epiphytic communities on Equisetum fluviatile was controlled both directly and indirectly by the macrophyte. Decaying macrophytic material supported rich algal growth and biomass accumulation in spring and early summer. Emergence of the macrophytes severely reduced underwater light availability, and the epiphytic algal biomass declined rapidly as a result of both lower photosynthetic activity of the epiphytic algae, and more intensive grazing by invertebrate herbivores. Epiphytic N: P ratios were lower than those in the water around suggesting that either the water was not the only source of phosphorus for the epiphytic algae or the algae took phosphorus up selectively from the water. Low epiphytic C: N ratios suggested a high potential nutritional value for herbivores.
Studies on the Feeding of Coregonus pollan (Thompson) Alevins and Fry in Lough Neagh
Authors: Dabrowski K. , Murawska E. , Terlecki J. , Wielgosz S.
Published: February 2007

Pollan alevins and fry were collected in the open lake between March and July. Fish were measured in total length, upper (Uj) and lower (Lj) jaws and weighed. The gape‐height was calculated according to two different formulae. For the examined fish the relationship between total length (Lt) and gape‐height (D) was found to be D=0.092 Lt—0.306. The size of food in the gut content was measured, and this increased during fish growth, but amounted to 13.2–26.0 % of D. In the first food of pollan alevins, nauplii and copepodites dominated, but after the alevins had reached 20 mg, copepods appeared to be more frequent food items. In the middle of May, Daphnia longispina was found in the food of pollan fry with an individual weight over 45 mg. Benthic invertebrate fauna were taken after the fish weighed more than 1.4 g. Chironomus anthracinus and Chironomus sp. larvae were among the food item dominants.
Effects of Altered Light and Feeding Regimes on the Zooplankton Feeding Capability of Hydra viridis
Authors: Clayton William S.
Published: February 2007

The effects of light regime, feeding regime and tentacle number on the zooplankton feeding capability of Hydra viridis were tested in the laboratory. Feeding was measured by exposing Hydra to a known volume of Artemia salina nauplii and recording the number captured and ingested. In all cases there was a correlation between the number of Artemia captured and the number ingested. H. viridis with 7 tentacles captured and ingested more Artemia than Hydra with 6 tentacles. However, changes in light and/or feeding regimes did not alter the number of tentacles/Hydra. Varying light and feeding regimes altered the number of Zoochlorellae/cell and Hydra growth rate. There was no effect on the number of Artemia captured or ingested and no effect on the percent ingestion of captured Artemia. These data suggest that, under these conditions, zooplankton feeding by H. viridis is independent of nutritional history.
The Filtering Rates of Four Herbivorous Crustaceans on Nannoplankton and Net Plankton Fractions in an Acid Lake in West Virginia
Authors: Janicki Anthony , Decosta John
Published: February 2007

Four experiments were conducted in Cheat Lake, West Virginia, to determine the filtering rates of zooplankton on the size fractions of phytoplankton in an acid lake. The results showed that Bosmina longirostris filtered significantly more net plankton than nannoplankton. Results for other species were not consistent in the size fraction selected. The dominance of Peridinium inconspicuum may have made the nannoplankton fraction unavailable as food for Bosmina.
Limnology of the Kern River (Southern California)
Authors: Hill Gary , Rai Hakumat
Published: February 2007

The Kern River, in Southern California, was studied for twenty months. Geological and morphological effects on water chemistry were noted. Chemically, the Kern River is a Ca‐Na‐HCO3 system with an average total filterable residue of 100 mg/l. Primary production in Kern River water was limited by nitrates and, occasionally, by phosphates. Planktonic biomass was highest in February–March and Melorisira granulata was the dominant species. Chlorophyll ‐α averaged 4.17 μg/1. Radioactivity was low. Carbon forms were influenced by runoff with labile carbon being associated with the saprobic bacteria (r = +0.90). Three habitat types of flora were encountered. Total fish potential was largely restricted to man‐made Lake Isabella.
Metabolic Similarity of Palaemon Populations from Different Brackish Waters (Short Note)
Authors: von Oertzen Jörg‐Andreas
Published: February 2007

The oxygen consumption rates (standard metabolic level) of three Palaemon adspersus populations from Fjords in the Belt Sea (Baltic) with different salinity regimes and of Palaemon elegans from the Black Sea measured under summer temperature conditions in a flow‐through respirometer are almost identical. A possible interpretation of these findings from the evolutionary standpoint and its practical importance for research into brackish water environments is briefly discussed.
Studies on the Genus Vaucheria (Xanthophyceae) in Iraq
Authors: Islam A. K. M. Nurul
Published: February 2007

Eight species of Vaucheria from southern Iraq, V. dichotoma, V. sessilis, V. erythrospora, V. verticillata, V. hamata, V. woroniniana, V. synandra, and V. longicaulis were studied and described. All but V. sessilis and V. longicaulis are recorded for the first time from Iraq.
Scaling of Microcosms and the Dimensional Analysis of Lakes
Authors: Uhlmann Dietrich
Published: February 2007

In this contribution, different possibilities for designing and operating microcosms have been reviewed. Examples of geometrical and of physiological similarity between systems of different sizes and the corresponding scaling functions have been considered. The simulation of the community metabolism (% BOD removal) of waste treatment lagoons by means of microcosms and the selection of proper similarity criteria yielded results which reasonably corresponded to the data directly measured in existing full‐scale ponds and dealt with in the literature. The change in phytoplankton primary productivity per unit volume of the epilimnion with change in mean depth of a variety of lakes to be expected from dimensional analysis was found to be in good agreement with empirical data recorded in the literature.
Selenium Requirement of the Dinoflagellate Peridinopsis Borgei (Lemm)
Authors: Lindström Kåre
Published: February 2007

An indispensable dependence on selenium (Se) was established for the dinoflagellate Peridinopsis Borgei (Lemm.) Lemm. The alga regularly blooms in semi‐meromictic lakes close to the Baltic Sea. A vitamin B12 requirement is indicated for the alga as well as increased levels of micronutrients. A culture medium specifically designed for P. Borgei is presented.