bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Interactional Decision Support Applications for E-Participation in Smart Cities
Authors: Ortner Erich , Mevius Marco , Wiedmann Peter , Kurz Florian
Published: August 2016

Nowadays, the number of human to application system interactions is dramatically increasing. For instance, citizens interact with the help of the internet to organize meetings spontaneously. Furthermore, standards such as Business Process Model and Notation (BPMN) and the Decision Modeling Notation (DMN) allow the creation of graphical models to document the (interaction) processes. Moreover, simulations and automations can be set up to encounter new technical challenges. Smart Cities aim at enabling their citizens to use these digital services. However, looking beyond technology, there is still a significant lack of interaction and support between “normal” citizens and the public administration. This article introduces an approach, which describes the design of enhanced interactional applications for decision support in Smart Cities based on Dialogical Logic process patterns. The authors demonstrate the approach with the help of a use case concerning a budgeting scenario as well as a summary and outlook on further research.
Intuitionistic Group Decision Making to Identify the Status of Student's Knowledge Acquisition in E-Learning Systems
Authors: Goyal Mukta , Tripathi Alka , Yadav Divakar
Published: August 2016

Learner's performance evaluation in an E-learning environment is a multi-criteria decision problem and important to personalize the sequence of learning concepts according to their knowledge level. Crisp responses, leads uncertainty in the evaluation process due to successful guesses or choosing a more probable answer. Analysis of learner's response to a complex/subjective questions needs more effort. Moreover, due to uncertainty and imprecise nature of learner, traditional methods are inadequate to assess, how much time he has spent on studying the learning contents and also the number of backtracking he followed. This paper proposes an intuitionistic fuzzy multicriteria decision making that investigates the use of an intuitionistic fuzzy technique for order preference by similarity to ideal solution (TOPSIS method) for the evaluation of student in an E-learning environment. Synthetic data are created for the criteria's that affect the student evaluation in E-learning domain and thereafter results are evaluated.
Chance Hypotheses Testing
Authors: Sampath S. , Renitta L. Pephine
Published: August 2016

This paper considers the problem of testing hypotheses about hybrid distributions which are models representing situations where impreciseness (explained through fuzzy measure) and randomness (explained through probability measure) coexist. A criterion similar to the Neyman-Pearson criterion is proposed for testing a simple chance null hypothesis against a simple chance alternative hypothesis. The suggested criterion has been applied for testing hypotheses about hybrid triangular Bernoulli distribution and hybrid Poisson distribution. Optimal properties of the resulting tests have also been investigated.
Analysis of urbanization trends in the greater Colombo area from 1956 to 1994 using air photos
Authors: Majid Malik
Published: August 2016

No abstract available
Towards place-sensitive urban interventions: an examination of the significant characteristics of place in selected urban nodes in Colombo
Authors: Rajapakse Amanda , Dayaratne Ranjith
Published: August 2016

"Place" is a concept that has received recent attention among architects, planners and urban designers. It is seen as a useful concept to examine and to be employed for planned interventions in the built-environment. Place is a spatial entity as well as a social-psychological entity. Its characteristics therefore are intertwined with these aspects. What are the .significant refinements of these characteristics that will elevate the quality of places and transform them to memorable cherished places? This was a research question that prompted an inquiry into the urban spaces whereby an attempt was made to recognize and emphasize the significant characteristics of place that will enable place-sensitive planned interventions in the city. The study based in Colombo examined in detail the characteristics of two selected places that mark them special and significant. The study proposes a theoretical construct of those characteristics that must be enhanced in planned interventions.
Innovations in the construction industry: problems and potentials
Authors: Kulatilake Prasanna
Published: August 2016

Innovation is the means by which an industry progresses taking either big leaps or gradual development. However, the construction industry, compared to other industries such as chemical, electronic, automobile etc, is rather ill equipped for innovations and records a little progress in its main streams of activities; design and construction. While innovation in design may take place even on a project by project basis, in the main stream of construction this seems notably absent.In this context, the objective of this paper is to discuss such aspects that may arise at various levels within the construction industry and suggest possible remedial measures. In doing so, the study evolves into three major phases. At the outset, the term innovation is defined in general terms and then in relation to applicability in the construction sector. The need for innovation in the present day context is highlighted. The key issues related to innovation within the context of the structure of the construction industry and the related external factors are discussed at the subsequent stage. The third and the final phase outlines the possible measures that could be adopted in order to overcome such drawbacks as well as to induce the culture of innovation within the construction industry.In this Study, an attempt has been made to capture the scenario in general, as the issue of innovation in the construction sector is common to almost any country situation. The recommendations too are made general, which could however be adopted to suit the specific situation where appropriate. Although the situation of Hong Kong has been taken into discussion for illustrations, the issues raised are common to the Construction Industry in many parts of the world.
An analysis of the changing character of an urban street: a case study of the Galle road, Colombo
Authors: Fernando Nisha
Published: August 2016

Analyses of the perceptible character of an environment are often vague and implicit. In urban contexts, visual elements are recognized as key attributes of the environmental character. This paper is based on a research study that investigated the environmental character within an explicit conceptual framework, which included several visual as well as nonvisual attributes. People's interactions with the environment, by means of various activities and settings, contribute significantly to the character of an urban space. Non-visual sensory elements, such as smell or sound, also contribute largely to the perception and evaluation of the ambience of an urban environment. Culture is the overarching concept and it plays an important role in the type of activity, the choice of settings, and the presence/absence of multi-sensory elements. Taking Galle Road, Colombo, a key urban street in Colombo and an example of the Sri Lankan urban cultural landscape, the present study considered activity systems, systems of settings, and multi-sensory elements as key attributes of the perceptible character. It focused specifically on a comparison of how the character changes al different points along the street, from the Lotus Road intersection at Galle Face to the Dehiwela Bridge. The methodology involved unobtrusive participant observations, place-centered behavioral mapping, systematic field notes, and photographic documentation. The findings showed that there are seven distinct sections of Galle Road that display different characters. Furthermore, these different sections, distinguished on" the basis of how people use the street and the resultant multi-sensory qualities, do not coincide with various zones and divisions as outlined by a recent development proposal for the Galle Road.
Teaching architecture as an intervention in thinking: the Moratuwa experiment revisited
Authors: Dayaratne Ranjith
Published: August 2016

Apart from Architecture itself, architecture students learn many other things during their course of studies, both factual and otherwise. This is indeed unique since most other disciplines may not be able to claim the same about their courses of study. Obviously, as a student, one may acquire knowledge unrelated to the subjects they study in the process of maturity and growing up in every discipline, but most academics would not necessarily consider it a great achievement that their students have learned nothing in their discipline but other things during the course of study. In one year of studies in architecture at the University of Moratuwa in Sri Lanka in fact, quite the contrary was happening and the students took great pride that they are not leaning architecture perse, at least in one year of their 6 year course. A recent research uncovered that the students believe they learned a great deal of 'thinking' but very little in architecture. This paper examines a student evaluation of the teaching / learning practice that prevailed in the 5m year studio in 1998 at the Department of Architecture at the University of Moratuwa, which is a part of a programme known as the Moratuwa Experiment and discusses its impact upon the students' thinking.
Stategies for equity & sustainability in urban transportation in third world mega-cities
Authors: Emmanuel Rohinton
Published: August 2016

The conventional approach to transportational problems has been building more and better highways. However, contrary to popular and academic expectations, more and better transportation technologies have led to an increase in time spent in transportation all over the world. In this paper we therefore propose mechanisms for equitable and sustainable transportation strategies, particularly for third world urban agglomerates. The solution proposed here is not an equitable distribution of more transport power, but a reduction in the need for it. It is argued that a ceiling on per capita energy use by means of design strategies for speed reduction is necessary to promote healthier urban transportation. Strategies for urban design alternatives that achieve this end are proposed.
Rational use of glass in tropical urban climatic conditions
Authors: Perera L. S. R. , Wickramasinghe Naomi
Published: August 2016

Glass is a common material used in buildings, mainly for penestration purposes. Although the physical properties and performance data of the wide variety of glass can be easily obtained from technical literature, their performances under specific environmental conditions are not commonly known. While the technical literature presents performance data under laboratory conditions, the same under ambient conditions are not available. However, the post application performance of glass largely depends on the external environmental conditions. This paper attempts to understand the performance of popularly used variety of glasses under tropical urban climatic conditions of Sri Lanka. It presents the' findings of an experiment conducted under ambient conditions, using a scaled model of a typical office building.
Archetypes, patterns & computer applications in architecture
Authors: Emmanuel Rohinton
Published: August 2016

No abstract available
Construction work and the worker: comparative study of craft & mass scale technologies in building construction
Authors: Rameezdeen Raufdeen , Pathirage Chaminda
Published: August 2016

During the twentieth century the construction industry, ifs products and technology have changed drastically. Studies carried out on the same or equivalent products of construction have showed clear differences in the nature of technology used in the production process. The construction industry is inherently labour intensive and many challenges arise through a need to maintain a skilled and competitive workforce. Two distinct forms of construction, the ancient craft-oriented form and modern mass scale form are commonly deployed within the construction industry. This comparative study, in respect of these two technologies, upon the nature of work and the worker, has revealed some differences in number of parameters such as skills, experience, supervision, rules and regulations, autonomy, deference and aggression. For these parameters there is a close relationship between the nature of work and the worker personality. Craft workers have more autonomy, which result in more skill, experience and responsibility in the work process. The dominating personality traits of deference and aggression in Mass Scale technology facilitate more management influence through supervision and rules and regulations.
Cost modelling for roofing material selection
Authors: Perera R. S. , Fernando U. L. A. S. B.
Published: August 2016

During recent decades new building techniques have been developed and many new materials have been introduced to the construction market. The material market has become more profitable for contractors and construction material producers than for the client.Not having being a functional and performance oriented roofing material selection system, domestic clients are in a very tight situation when selecting a suitable roofing material according to their requirement, without they being misled from sales exaggerations.This paper elaborates preparation of a cost model which can be used for selection of roofing materials for domestic purposes, giving adequate consideration on cost and some other performance factors. Cost comparison of roof covering, ceiling and insulation materials those are available in the Sri Lankan market are investigated along with the other performance factors of materials. Further, the current status of the roof construction and design in the Sri Lankan context is also explained
El vídeo en la ‘prensa’ digital española: 2010-2015
Authors: Mayoral Sánchez Javier , Abejón Mendoza Paloma , Morata Santos Montserrat
Published: August 2016

El uso de vídeos en los cibermedios ha cobrado una gran importancia durante los últimos años. Esas piezas son fundamentales para ganar la atención de los lectores en los medios digitales. Metodología: Este trabajo examina, a través de un análisis de contenido clásico, la producción audiovisual de cinco medios digitales españoles de referencia entre los años 2010 y 2015. Se estudian los géneros, los formatos, las estructuras, el tipo de producción y los contenidos de los vídeos. Resultados y conclusiones: La producción audiovisual de los cibermedios, tras una etapa de crecimiento sostenido, se ha estancado en los últimos años. Además los vídeos analizados se alejan de la narrativa audiovisual clásica. En primer lugar, por la influencia de la poderosa producción externa, que aporta piezas totalmente ajenas a los criterios periodísticos clásicos. En segundo lugar, como resultado de una producción propia que busca originalidad y nuevas fórmulas narrativas.
GYNANDROMORPHISM IN THE CHYDORID CLADOCERA1
Authors: Frey David G.
Published: August 2016

A population of Pleuroxus in Lake Balaton, Hungary, formerly designated as P. balatonicus, is here considered to be a dwarf variety of P. uncinatus, in which the males resemble the females in their general morphology rather than being strongly dimorphic and in which the large females have lost the prominent teeth at the posterior‐ventral angle of the shell, although these arc present in males and in smaller (younger) females. Although large dimorphic males occasionally occur in the population, bisexual reproduction apparently is accomplished primarily by the smaller sex‐intergrade males. The mechanism whereby diploid female Cladocera product diploid males by parthenogenesis is as yet unknown.
AN OBSERVATION ON MARINE SEDIMENTATION RATES DURING THE PLEISTOCENE
Authors: Goldberg Edward D.
Published: August 2016

The following events appear to have occurred simultaneously (within the experimental errors of the age measurements) around 100,000 years ago: the last high stand of sea level; the temperature peak of the last interglacial stage; and a change in the rates of sedimentation in certain open ocean deposits. The sedimentation rates were greater during the warm interglacial period than during the cooler glacial periods.
THE ECTOLOGY OF MARGAREE SALMON
Authors: Huntsman A. G.
Published: August 2016

Ectology deals with the role of the environment in determining what organisms there will be. In discovering how salmon respond to what they face (their biapocrisis), the outstanding variables considered are light, temperature, and current; traditional ideas of salmon behavior have been ignored. With such knowledge, it is shown how the local and temporal conditions determine what Margaree River salmon are found where and when. Their large number is attributed to the availability and suitability of the Northeast Margaret River system on the border of high tableland. When smolts, the young are carried downstream to settle in more or less deep water along the course of the estuarial outflow. After a variable number of years, they cease feeding and wander to and fro, to be caught in nets or to become concentrated near the estuary mouth where river influence is greatest, but lack of steady estuarial outflow greatly delays their entrance. Salmon ascend the Northeast Margaree River during subsidence of freshets and offer good angling. The large Lake Ainslie reduces freshet action in the Southwest Margaree so that salmon fail to ascend it until spawning time.
SOME CONSEQUENCES OF THE DECOMPOSITION OF ORGANIC MATTER IN LAKE NITINAT, AN ANOXIC FJORD1
Authors: Richards Francis A. , Cline Joel D. , Broenkow William W. , Atkinson Larry P.
Published: August 2016

Observations in Lake Nitinat, an anoxic fjord on Vancouver Island, British Columbia, indicate that the large accumulations of ammonia, carbonates, phosphates, silicates, and sulfides in the deep water are the result of oxidative and fermentative decomposition of organic matter of planktonic origin, the reduction of sulfate ions, hydrolytic or other non‐oxidative release (in the case of silicates), and the solution of carbonates (which also increases the alkalinity). Ammonia, sulfides, and silicates accumulate in the sulfide zone in direct proportion to each other, but some of the phosphate is probably released from the organic matter earlier than the other components, and some of the phosphate may be precipitated onto the bottom. Methane was observed in the anoxic waters, suggesting that some decomposition takes place by anaerobic fermentation. The concentrations of ferrous and sulfide ions are probably controlled by the solubility of ferrous sulfide. The vertical distribution of sulfides can be described by a mathematical model that can be simplified to one dimension because horizontal advective and diffusive terms can be neglected.
ON THE DETERMINATION OF THE ACTIVITY IN 14C‐AMPOULES FOR MEASURING PRIMARY PRODUCTION
Authors: Nielsen E. Steemann
Published: August 2016

A biological method for measuring the activity in 14C‐ampoules is described. All 14CO2 is assimilated by Chlorella and the activity of the algae is measured. The new technique gives results substantially (31%) lower than the values obtained by the original BaCO3 technique but seems to be in accordance with other techniques recently developed. When the new technique for measuring the activity of the ampoules is used, the 14C method and the oxygen method give identical results. Skeletonema costatum was used as the test organism.
RESIDUAL DRIFT ALONG THE BOTTOM ON THE CONTINENTAL SHELF IN THE MIDDLE ATLANTIC BIGHT AREA1
Authors: Bumpus Dean F.
Published: August 2016

Plastic and brass sea‐bed drifters have been used to investigate residual drift along the bottom on the continental shelf in the Middle Atlantic Bight area.
MEASUREMENTS OF DIURNAL CHANGES IN BIOLUMINESCENCE FROM THE SEA SURFACE TO 2,000 METERS USING A NEW PHOTOMETRIC DEVICE1
Authors: Clarke George L. , Kelly Mahlon G.
Published: August 2016

At stations in the western and central North Atlantic Ocean, the transparency was found to change with depth in the upper 300 m and to be very high in the strata below. Using 3 photomultiplier photometers, the rate of light diminution during the sunset period was shown to be essentially the same at the surface, 100, and 300 m. Using a newly designed light‐tight agitator, which pumps water past the window of the deep‐sea photometer, luminescent flashing was recorded from the surface to depths as great as 2,000 m in both day and night tests. Some luminescence was detected at all depths during the day at certain stations. At night, Flashing increased very greatly in the upper 50 m, considerably at 200 m, and somewhat at intervening depths. Changes in luminescence with depth, sometimes abrupt, occurred at widely varying levels between 40 and 85 m at different stations, usually near the thermocline, and always associated with vertical temperature changes. Netting placed over the intake of the agitator showed that most of the luminescent organisms in the upper few hundred meters were smaller than 0.24 mm. Additional tests with the unrestricted photometer indicated that much of the luminescence recorded at greater depths was from larger animals.
CERTAIN ECOLOGICAL ASPECTS OF POLLEN DISPERSION IN LAKE TAHOE (CALIFORNIA‐NEVADA)1
Authors: RICHERSON PETER J. , MOSHIRI GERALD A. , GODSHALK GORDON L.
Published: August 2016

The pollen dispersion and its dissemination pattern in Lake Tahoe was investigated to determine its role in the nutrient budget of the lake. Pollen was sampled during summer 1968 from tubs placed around the lake and from lake water down to 150 m. Pinus pollen reached its peak of abundance later in the season than Abies. The nitrogen and phosphorus of the pollen deposited during one season is negligible in the total annual nutrient budget of the lake. Total dry weight contributed by pollen also constitutes an insignificant percentage of the annual 14C primary productivity of the lake. In small, subalpine or alpine lakes with more limited nutrient inflow, pollen may contribute more significantly to the annual nitrogen and phosphorus budgets.
WEIGHT, SIZE, AND CHEMICALC OMPOSITION OF SOME FRESHWATER ZOOPLANKTERS: DAPHNIA HYALINA( LEYDIG)1
Authors: BAUDOUIN M. F. , RAVERA O.
Published: August 2016

Size, dry weight, ash, and concentration of C, H, N, P, and Ca of Daphnia hyalina from Lago Monate (northern Italy) have been investigated. The concentration of the elements varies with age of the individuals. Eggs have the maximum concentration of C and H, the new‐born of P, and the young of N. No seasonal variation was observed for individuals of the same size.
PRODUCTION AND DECOMPOSITION OF ORGANIC MATTER IN A BAY OF THE JAPAN SEA DURING THE WINTER DIATOM BLOOM
Authors: Sorokin Yu. I. , Konovalova I. W.
Published: August 2016

The winter bloom of diatoms studied under the ice of a bay in the Japan Sea consisted mainly of species of Thalassiosira and Chaetoceros, having a low temperature optimum (9°C) for photosynthesis and a low optimum of illumination (2 klux). Photosynthesis proceeded to 8–15 m in water under the ice at −1.8°C. The cause of the bloom is related to optimal illumination and nutrient supply during this period. Microbial biomass was sufficiently high to sustain the normal feeding on zooplankton. Thus, an active process of biological production takes place there even in winter at subzero temperature.
Kinetic control of dissolved phosphate in natural rivers and estuaries: A primer on the phosphate buffer mechanism1
Authors: Froelich Philip N.
Published: August 2016

The primary mode of interaction of dissolved phosphate with fluvial inorganic suspended particles is via a reversible two‐step sorption process. The first step, adsorption/desorption on surfaces, has fast kinetics (minutes–hours). The second step, solid‐state diffusion of adsorbed phosphate from the surface into the interior of particles, has slow kinetics (days–months) and is dependent on the time history of the previous surface sorption and the chemistry of the solid diffusional layer. Natural clay particles with a surficial armoring of reactive iron and aluminum hydroxyoxides resulting from chemical weathering of rocks and soils have a high capacity for absorbing phosphate in the second step and for maintaining low “equilibrium phosphate concentrations” in solution. Extrapolation of laboratory sorption and extraction experiments with natural soils and suspended sediments to the environment suggests that the phosphate concentrations of unperturbed turbid rivers (SPM > 50 mg liter−1) are controlled near the dynamic equilibrium phosphate concentration of their particles (EPC0 = 0.2–1.5 µM) and that fluvial suspended particles “at equilibrium” contain up to 10 µmol‐P g−1 that is desorbable. Release of this phosphate from particles entering the sea produces the characteristic shape and magnitude of input profiles of dissolved phosphate observed in unperturbed estuaries. On a global scale, fluvial particulates could transport from 1.4 to 14 × 1010 mol yr−1 of reactive phosphate to the sea, some 2–5 times more than that in the dissolved load alone.
New methods for using diatoms and chrysophytes to infer past pH of low‐alkalinity lakes
Authors: Charles Donald F. , Smol John P.
Published: August 2016

Distributions of both diatoms and chrysophytes (Mallomonadaceae) are clearly correlated with pH in low‐alkalinity lakes. Their siliceous remains are well preserved in lake sediments and have been used to infer long‐ and short‐term acidification trends. Until now, however, only diatoms have been used quantitatively.

We describe new methods for inferring past pH in lake water using diatoms alone, chrysophytes alone, and the two together. We developed the equations with multiple regression analysis of diatom and chrysophyte assemblage data and pH measurements for 47 Adirondack lakes (pH range, 4.7–7.8). Correlations of measured vs. calculated values of pH yield r2 values of 0.70–0.94 and standard errors of 0.13–0.35 pH unit. The best predictive equations, especially for acidic lakes (pH < 5.5) incorporate both diatoms and chrysophytes. Major advantages of using chrysophytes in addition to diatoms in paleoecological studies are that chrysophytes are more sensitive at lower pH values (<5.0) than diatoms, are nearly all planktonic, represent a different phycological group, can be counted on the same slides as diatoms, and can be counted faster because there are fewer taxa. Stratigraphic diatom and chrysophyte data for two lake sediment cores are used to evaluate the equations. These methods are widely applicable in studies of cultural and natural acidification of low‐alkalinity lakes in many regions of the world.
Nitrogen cycling rates and light effects in tropical Lake Maracaibo, Venezuela
Authors: Gardner Wayne S. , Cavaletto Joann F. , Bootsma Harvey A. , Lavrentyev Peter J. , Troncone Federico
Published: August 2016

Isotope dilution experiments with 15NH4+ were conducted in Lake Maracaibo, Venezuela, to examine potential N turnover rates and light effects and to examine the hypothesis that nutrient dynamics are biologically driven in this tropical, hypcreutrophic lake. Ammonium and nitrate concentrations were both <l µM as compared to particulate N concentrations of 9–29 µM N. Chlorophyll (Chl) levels ranged from 2.5 to 22 µg liter−1. Numbers and biomass of bacteria ranged from 1.0 to 9.1 × l06 cells ml−1 and 45 to 138 µg C liter−1 and those of heterotrophic nanoflagellates (HNAN) ranged from 0.5 to 3.5 × 103 cells ml−1 and 2.3 to 17.5 µg C liter−1, respectively. Highest Chl concentration and microbial abundance occurred in a region affected by sewage discharge from the city of Maracaibo. Potential ammonium uptake rates in near‐surface waters ranged from about 1 µM h−1 to 8 µM h−1. Chlspecific uptake rates were highest in central regions that were dominated by chroococcoid cyanobacteria. Ammonium regeneration rates ranged from near detection to 2 µM h−1 and correlated significantly with the ratio of HNAN to bacterial biomass, likely reflecting the degree of bacterivory. The high ratio of potential turnover rates to ambient ammonium concentrations suggests that internal recycling is a major nutrient supply process in the lake. Incubation bottle characteristics (e.g., light intensity, spectral quality, or possibly headspace differences) apparently affected potential uptake rates, which were relatively low in polystyrene bottles and in quartz tubes. Uptake rates were lower in screened polystyrene bottles than in screened polypropylene syringes, with different spectral characteristics, even though total‐light attenuation was similar (45% vs. 53%).
Trace element signatures in otoliths record natal river of juvenile American shad (Alosa sapidissima)
Authors: Thorrold Simon R. , Jones Cynthia M. , Campana Steven E. , McLaren James W. , Lam Joseph W. H.
Published: August 2016

The elemental composition of fish otoliths may represent a permanent record of the environmental conditions an individual has experienced as trace elements, incorporated into the growing surface of the otolith, reflect the physical and chemical characteristics of the ambient water. We tested the utility of trace element signatures in otoliths as natural tags of the river of origin of juvenile American shad (Alosa sapidissima) collected from the Connecticut, Hudson and Delaware Rivers in August and October 1994. Four elements (K, Mn, Sr, and Ba) showed significant variability among sites within rivers in August, although only Mg showed a significant site effect by October. Four elements (Mg, Mn, Sr, and Ba) differed significantly among rivers in both months. Linear discriminant functions based on the trace element signatures classified fish to their natal river with ~90% accuracy in both August and October collections. The discriminant function generated from the August data was able to classify fish collected in October successfully with better than 80% accuracy. On the basis of our findings, the river of origin of adult fish could be accurately determined by quantifying the trace element composition of the juvenile portion of their otoliths.
The role of surface‐active carbohydrates in the formation of transparent exopolymer particles by bubble adsorption of seawater
Authors: Zhou Jian , Mopper Kenneth , Passow Uta
Published: August 2016

Experiments were performed to examine the role of surface‐active polysaccharides in the formation of transparent exopolymer particles (TEP) by bubble adsorption in seawater. Filtered (1.0 µm, 0.45 µm) and ultrafiltered (0.1 µm, 100 kDa, and 10 kDa) seawater samples were bubbled in a glass foam tower. The neutral sugar composition, concentration of TEP, and concentration of surface‐active carbohydrates in generated foam samples were determined. Three different surface seawater samples (Monterey Bay, California; Shannon Point, Anacortes, Washington; and East Sound, Orcas Island, Washington) were used in the experiments. Significant concentrations of pre‐existing and new TEP were extracted into foam by bubble adsorption. Newly generated TEP accounted for 28–52% of the TEP collected in the foam samples by bubbling 1.0‐µm‐filtered samples. Neutral sugar composition analyses of foam samples derived as a function of bubbling time indicated that two types of surface‐active carbohydrates were extracted by bubble adsorption: highly surface‐active carbohydrates, which were extracted initially, and less surfaceactive carbohydrates. As in our previous mesocosm study (Mopper et al. 1995), highly surface‐active polysaccharides were enriched in deoxysugars (fucose and rhamnose), whereas the less surface‐active polysaccharides and residual (bubble‐stripped) water were glucose rich. In addition, the highly surface‐active fraction was strongly enriched in covalently bound sulfate. The concentrations of TEP and surface‐active carbohydrates that were extracted into the foam both decreased sharply with decreasing filter size used to filter samples prior to bubbling, in agreement with theoretical considerations. The results of this study suggest that bubble adsorption of sulfate‐rich surface‐active carbohydrates is an important pathway for the formation of TEP in surface waters, especially during algal blooms.
Lipid metabolism of the Antarctic euphausiid Thysanmssa macrura and its ecological implications
Authors: Hagen Wilhelm , Kattner Gerhard
Published: August 2016

The lipid biochemistry of one of the dominant Antarctic euphausiids, Thysanoessa macrura, was investigated in the Weddell Sea. Ontogenetic stages from furciliae to adults were collected during all seasons. Total lipid contents of these stages ranged from 5.5% to 60.5% of dry mass, with minimum levels in late winter/early spring (October/November) and maximum levels in autumn (April/May). Accordingly, wax esters, the primary storage lipid in T. macrura, also varied seasonally and reached a mean value of 66.6% of total lipid in autumn. Although lipid reserves are used partly for overwintering, the adults invest considerable amounts of these stores in reproductive processes such as gonad maturation, egg production, and mating in late winter prior to the vernal phytoplankton bloom. Total lipids were dominated by the fatty acids 16:0, 20:5(n‐3), and 22:6(n‐3), the principal components of the phospholipids. Other important fatty acids were 14:0 and 18:1(n‐9), which together with 16:0 prevailed in the wax esters. The alcohol moieties of the wax esters consisted of >90% of the isomers 18:1(n‐9) and 18:1(n‐7) and of 20:1 (n‐9). The dominance of 18:1 alcohols in T. macrura is unique among marine plankton. All fatty acids and alcohols exhibited linear relationships with increasing total lipid mass and with total lipid content, irrespective of the developmental stage, sex, region, or season. The fatty acids 16:0, 14:0, and 20:5(n‐3) and the two 18:1 fatty alcohol isomers had the highest accumulation rates, which explains their seasonal dominance in the lipid‐rich specimens. T. macrura has developed quantitative and qualitative energetic adaptations to cope with the pronounced seasonal variability in feeding conditions and reproductive requirements.
Picoplankton population dynamics in coastal waters of the northwestern Mediterranean Sea
Authors: Jacquet Stéphan , Lennon Jean‐François , Marie Dominique , Vaulot Daniel
Published: August 2016

High‐frequency sampling of surface picoplanktonic populations was performed in Villefranche Bay (northwestern Mediterranean Sea) during the first week of July 1996. The evolution of abundance and cell parameters were monitored once per hour by flow cytometry for these populations: Synechococcus cyanobacteria, photosynthetic picoeukaryotes, and heterotrophic bacteria plus Prochlorococcus. Some parameters, such as the right‐angle light scatter of Synechococcus and picoeukaryotes, or the red chlorophyll fluorescence of picoeukaryotes, exhibited a very clear 24‐h diel periodicity. For other parameters, such as Synechococcus red chlorophyll fluorescence, it was necessary to perform a Fourier analysis to establish a major 24‐h period unambiguously. This analysis also revealed that some other parameters, however, such as the cell concentration, right‐angle light scatter, and red chlorophyll fluorescence of picoeukaryotes, or the red chlorophyll and orange phycoerythrin fluorescence of Synechococcus, had a period of 17–18 h, corresponding to the inertial frequency at this latitude. The cell cycle of Synechococcus, sampled twice per hour, was synchronized with the daily light cycle, allowing an estimate of their growth rate, which averaged 0.95 d−l (SD = 0.16, n = 7). Its large day‐to‐day variability was related to the duration of the interval between the maxima of S and G2 phases that ranged from 2 to 3.5 hours. Generally, the division rate was depressed on sunny days, The loss rate of Synechococcus was in general lower than the division rate and appeared to follow the evolution of the latter with a 1‐d lag, as if grazers or viruses adapted very rapidly to changes in division rates. Over the period of study, concentrations of Synechococcus and other bacteria were significantly correlated (r2 = 0.60, p < 0.01, n = 340), suggesting the possibility of a common controlling factor for these populations, e.g., phosphorus or grazing.
In situ aggregate analysis camera (ISAAC): A quantitative tool for analyzing fine‐grained suspended material
Authors: Knowles S. C. , Wells J. T.
Published: August 2016

The ISAAC (in situ aggregate analysis camera) system was developed to provide quantitative analysis of finegrained suspended material in waters of inner‐coastal, estuarine, fluvial, and lacustrine environments with suspended sediment concentrations (SSC) up to 200 mg/liter. Light from strobes is collimated by physically treated Plexiglas prisms, producing a well‐defined volume of illumination (VOI) in front of a 35mm camera mounted in an underwater camera housing. Particles within the VOI are in focus. Using a measured scale factor, researchers can measure suspended particle number, size, shape, and volume concentration. A submersible pump collects water from the depth of each photograph, allowing laboratory analysis of filtered suspensate. The present system, which is easily modified to meet specific field conditions, illuminates a 70.0 mm × 46.9 mm × 17.5 mm volume of water and documents particles ˜10 µm in diameter and larger. We use a 2,700‐dot‐per‐inch scanner to convert photo negatives to digital 256‐graytone images. In‐house software is used to classify particle morphology within 1/4 ϕ size classes, from ˜20–4,000 µm. Conversion of the ISAAC system to digital or video camera technology would allow real‐time data collection and analysis. In situ photographic data from the Elbe, Hudson, and Columbia River estuaries, as well as several coastal environments in North and South Carolina, illustrate the utility of the system for particulate concentrations ranging from — 2 to 200 mg/liter. A random composite sample from these data reveals that virtually all particles may form larger aggregates, characterized by an average equivalent spherical diameter (ESD) of ˜300 µm, with <10% of the aggregate volume in suspension containedwithin aggregates <50 µm in diameter. Aggregates larger than 2 mm ESD have been observed in < 1% of the over 1,000 photographs taken, supporting suggestions in the literature that the Kolmogorov microscale of turbulent eddies limits the growth of suspended aggregates.
Evidence for eutrophication of the Irish Sea over four decades
Authors: Allen J. R. , Slinn D. J. , Shummon T. M. , Hurtnoll R. G. , Hawkins S. J.
Published: August 2016

The Irish Sea is showing early signs of eutrophication extending offshore, beyond localized inshore effects, according to an unusually long time series of measurements taken in the central Irish Sea. Background levels of dissolved inorganic forms of nitrogen and phosphorus have risen substantially over the last 30 to 40 years. This rise has coincided with a significant rise in phytoplankton biomass, measured as chlorophyll a, during the late spring bloom. Contrary to trends in other coastal seas, the increase in N and P was not accompanied by a decline in silicate; in fact, a small but significant increase in Si was noted in autumn and winter. This may be related to the well‐mixed conditions over much of the Irish Sea. However, the common assumption that there are no anthropogenic sources of dissolved Si may not be valid in this area and requires further consideration.
Climatic warming and regime shifts in lake food webs—some comments
Authors: Jeppesen Erik , SØndergaard Martin , Jensen Jens Peder
Published: August 2016

#N/A
Sedimentation of acantharian cysts in the Iceland Basin: Strontium as a ballast for deep ocean particle flux, and implications for acantharian reproductive strategies
Authors: Martin Patrick , Allen John T. , Cooper Matthew J. , Johns David G. , Lampitt Richard S. , Sanders Richard , Teagle Damon A. H.
Published: August 2016

Acantharian cysts were discovered in sediment trap samples from spring 2007 at 2000 m in the Iceland Basin. Although these single‐celled organisms contribute to particulate organic matter flux in the upper mesopelagic, their contribution to bathypelagic particle flux has previously been found negligible. Four time‐series sediment traps were deployed and all collected acantharian cysts, which are reproductive structures. Across all traps, cysts contributed on average 3–22%, and 4–24% of particulate organic carbon and nitrogen (POC and PON) flux, respectively, during three separate collection intervals (the maximum contribution in any one trap was 48% for POC and 59% for PON). Strontium (Sr) flux during these 6 weeks reached 3 mg m−2 d−1. The acantharian celestite (SrSO4) skeleton clearly does not always dissolve in the mesopelagic as often thought, and their cysts can contribute significantly to particle flux at bathypelagic depths during specific flux events. Their large size (~ 1 mm) and mineral ballast result in a sinking rate of ~ 500 m d−1; hence, they reach the bathypelagic before dissolving. Our findings are consistent with a vertical profile of salinity‐normalized Sr concentration in the Iceland Basin, which shows a maximum at 1700 m. Profiles of salinity‐normalized Sr concentration in the subarctic Pacific reach maxima at ≤ 1500 m, suggesting that Acantharia might contribute to the bathypelagic particle flux there as well. We hypothesize that Acantharia at high latitudes use rapid, deep sedimentation of reproductive cysts during phytoplankton blooms so that juveniles can exploit the large quantity of organic matter that sinks rapidly to the deep sea following a bloom.
Molybdenum—nitrogen co‐limitation in freshwater and coastal heterocystous cyanobacteria
Authors: Glass Jennifer B. , Wolfe-Simon Felisa , Elser James J. , Anbar Ariel D.
Published: August 2016

Molybdenum (Mo) is essential for the biological assimilation of inorganic nitrogen (N). We compared Mo requirements for N2‐fixation in two species of filamentous heterocystous cyanobacteria (HC) to test the hypothesis that coastal HC require higher Mo concentrations than freshwater HC. This expectation follows from the fact that Mo is more concentrated in seawater (~ 105 nmol L−1) than in most freshwaters (< 20 nmol L−1). Contrary to this hypothesis, we found that both strains maintained N2‐fixation for 30 d at 10 nmol L−1. Mo concentrations < 1 nmol L−1 induced N‐limitation in both species, as indicated by increased C:N ratios and decreased nitrogenase expression and activity. This response took time to induce, likely due to high‐affinity molybdate uptake by both species. Measurable N2‐fixation persisted in the coastal strain (Nostoc sp. CCMP 2511) for at most 12 d; 3 d were required for chlorophyll a concentrations to fall below those of Mo‐replete cultures. An additional 7 d and 11 d, respectively, were required for N2‐fixation rates and chlorophyll levels to decline in Mo‐limited freshwater cultures (Nostoc sp. PCC 7120). When Mo was high (> 1 µmol L−1), the freshwater strain exhibited considerable Mo storage (> 100 µmol mol−1 Mo: C) whereas cellular Mo remained < 10 µmol mol−1 Mo:C in the coastal strain. The high Mo content and extended time required for N2‐fixation to decrease in the freshwater strain could be due to expression of the gene mop, which encodes a putative molybdate‐storage protein. This study suggests the importance of Mo storage in freshwater HC.
Control of nitrous oxide emission from Chironomus plumosus larvae by nitrate and temperature
Authors: Stief Peter , Polerecky Lubos , Poulsen Morten , Schramm Andreas
Published: August 2016

Aquatic invertebrates that ingest large numbers of bacteria produce substantial amounts of the greenhouse gas N2O because of incomplete denitrification in their anoxic gut. We investigated the influence of two key environmental factors, temperature and NO3− availability, on N2O emission from larvae of Chironomus plumosus in field and laboratory experiments. Larvae collected from lake sediments emitted between 2 and 73 pmol N2O ind.−1 h−1 during the warm season, but took up maximally 227 pmol N2O ind.21 h21 during winter. Larvae kept in laboratory microcosms emitted between 14 and 122 pmol N2O ind.−1 h−1, and N2O uptake was never observed. For both types of larvae, the rate of N2O emission was stimulated by temperature (when the NO3− concentration in the water column was higher than 25–50 µmol L−1) and by NO3− (when the temperature was higher than 4–10°C). Modeling based on experimentally determined ventilation parameters and sedimentary O2 and NO3− turnover rates predicted that NO3− concentrations inside the burrow and in the sediment surrounding the burrow fluctuated and were on average lower than those in the water column. In contrast, NO3− concentrations measured in the gut and hemolymph of the microcosm‐incubated larvae were at least as high as in the water column. This suggests that N2O emission from C. plumosus larvae is controlled by NO3− availability in the water column, but is decoupled, by a hitherto unknown mechanism, from NO3− present in the immediate surroundings of the larva.
Distribution, morphology, and formation of pockmarks in Lake Constance, Germany
Authors: Wessels Martin , Bussmann Ingeborg , Schloemer Stefan , ter Michael Schlü , dere Volker Bö
Published: August 2016

Pockmarks are well known in the marine environment but almost unreported from limnic systems. In Lake Constance we investigated pockmarks near the mouth of the main tributary, Alpine Rhine River, using sediment cores and hydroacoustics (sidescan sonar, subbottom profiler, horizontal scanning sonar, multibeam echo sounder). The maximum dimension of an individual pockmark is about 16 m in diameter and 3‐4‐m deep, often with a round shape. Most pockmarks are located on top of morphological high points such as sediment waves or shoulders of old channels in front of the Alpine Rhine River. They are collapse structures formed when a reservoir of biogenic methane rapidly empties into the water column. Ebullition of gas very often was observed, indicating that biogenic methane still migrates toward pockmarks.
The interplay between short‐term, mild physicochemical forcing and plankton dynamics in a coastal area
Authors: Romero Estela , Peters Francesc , Guadayol Òscar
Published: August 2016

Two intensive surveys were conducted in the coastal waters of Barcelona (northwest Mediterranean) to assess short‐term variations of biological parameters in relation to environmental conditions. Surveys lasted 1 week, with three to four samplings per day, and were carried out in autumn and spring. Rather than exploring extreme events, we aimed to study the effects of regular low or moderate perturbations, such as meteorological fronts, on the dynamics of the system. We focused on two attributes: wave height, as a proxy for mechanical energy entering the system, and nutrient inputs, whose variability in total load and relative composition is a central characteristic of coastal areas. The effects of the temporal coupling or uncoupling of both factors were examined. Sudden nutrient fluxes uncoupled from water motion tended to favor bacteria and heterotrophic nanoflagellates, while their concurrence with some water column mixing shaped a favorable scenario for large autotrophs. Ultimately, these two distinct biological responses pointed toward two main disturbance scenarios: episodes of nutrient enrichment uncoupled from mixing, mostly related to episodic water spills from the nearby city that contributed to high relative loads of ammonium and organic compounds; and episodes of increased wind caused by passing weather fronts that promoted some water column mixing and the entrainment of nutrients from bottom sediments or from adjacent water masses.