bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutrient and particulate fluxes in a salt marsh ecosystem: Tidal exchanges and inputs by precipitation and groundwater 1
Authors: Valiela Ivan , Teal John M. , Volkmann Suzanne , Shafer Deborah , Carpenter Edward J. 
Published: March 2010

Waterborne nutrients enter Great Sippewissett Marsh through groundwater, rain, and tidal flooding. The ebb of tidal water removes nutrients. During summer, uptake by marsh biota leads to net import of nutrients. The increased export of ammonium in August may be due to leaching from senescent marsh plants. There is a net annual export of ammonium, nitrate, nitrite, dissolved organic (DON) and particulate (PN) nitrogen, particulate carbon (PC), and phosphate. Ammonium, DON, and PN are the major forms of nitrogen exported. Nutrient concentrations in coastal and marsh water are correlated, and marsh exports could contribute substantially to nutrient supplies of coastal waters.Groundwater entering the marsh provides primarily NO3‐N and DON. Nutrient inputs through precipitation consist primarily of DON, NO3‐N, and NH4‐N. Particulate materials in rain have a high C:N ratio, contributing little to enrichment of the nitrogen‐limited salt marsh. Groundwater carries over 20 times the amount of nutrients brought in by rain. The nitrogen provided by both sources is more than enough to support annual plant growth. Inputs of nitrogen by groundwater arc therefore important to the nitrogen economy of a salt marsh.About half the dissolved inorganic nitrogen brought into the marsh by groundwater is converted to and exported as PN. The marsh thus transforms the nitrogen that would have been used by primary producers into a form suitable for consumers such as shellfish. Large amounts of apparently refractory DON enter the marsh in groundwater and similar amounts are exported by tides. PC exported to coastal water is equivalent to 40% of the net annual production of Spartina alterniflora, the dominant marsh plant.
The density and speed of sound of Orca basin waters1
Authors: Millero Frank J. , Lo Surdo Antonio , Chetirkin Peter , Guinasso Norman L. 
Published: March 2010

The composition of samples of waters collected in the Orca depression (Gulf of Mexico) above and below the seawater‐brine interface was characterized by measuring chlorinity (Cl) and salinity (S). The ratio of S:Cl = 1.6823 in the brines, compared with 1.6817 calculated from composition data. Densities and sound speeds of the waters were measured at 15°, 25°, and 35°C and the results fit to chlorinity functions. The standard deviations in density are ≈60 × 10−6 g·cm−3, in sound speed ≈1.2 m·s−1. These standard errors are about 6 times larger than the precision of the measurements and are due to errors in determining Cl and to changes in the brine composition across the interface.Conductivity, density, and sound speed were measured in weight‐diluted brine samples and the results used to calculate the relationship of evaporation salinity (Sevap) to salinity calculated from measurements on standard seawater. The differences in Sevap and S determined from properties of standard seawater are caused by hydration changes in the major constituents.The measured brine densities were compared with values calculated by using an additivity method and the known composition of the waters and agree to within ±280 × 10−8 g·cm−3 over the temperature range measured.
Nutrient‐determined dominance in multispecies chemostat cultures of diatoms1
Authors: Mickelson Michael J. , Maske Helmut , Dugdale Richard C. 
Published: March 2010

Thalassiosira gravida was rapidly displaced from ammonium‐limited chemostats at moderate (D = 0.03·h−1) and low (D = 0.01·h−1) dilution rates by Skeletonema costatum or Chaetoceros septentrionalis. Reduced temperature or reduced light did not favor Thalassiosira. Chaetoceros displaced Skeletonema at D = 0.03·h−1 but the two species coexisted at D 0.01·h−1. A brief temperature increase triggered changes in population densities in chemostats with coexisting species, leading to an increase in the less abundant species. Reduced turbulence did not change the pattern of coexistence.Nutrient‐dependent growth‐rate kinetics for the three species were deduced from rates of displacement in competition experiments and from published uptake kinetic and chemical composition data. The kinetics deduced by the two methods were qualitatively similar. Nutrient kinetics apparently do not explain the survival of natural populations of T. gravida in the field. On the basis of these results, a nutrient‐based functional group of phytoplankton is defined to include S. costatum and C. septentrionalis and exclude T. gravida.
The effect of organic nitrogen supplement on the utilization of different sources of detritus1
Authors: Tenore Kenneth R. , Hanson Roger B. , Dornseif Bruce E. , Wiederhold Craig N. 
Published: March 2010

A particulate organic nitrogen supplement was added to two detrital materials (red macroalga Gracilaria foliifera and marsh grass Spartina alterniflora) and its effect on their utilization by the polychaete Capitella capitata was investigated with isotope tracer techniques.With the decay‐resistant Spartina, added nitrogen had no effect on the oxidation or the net incorporation of Spartina carbon by the worms. With easily decomposable Gracilaria detritus there was an exponential increase in both oxidation and net incorporation with increasing nitrogen. Added organic nitrogen had no effect on the microbial biomass associated with Spartina detritus but resulted in an increase with Gracilaria detritus.Nitrogen enrichment by microbial activity is not the only regulator of nutritional value of detritus to macroconsumers. The extent to which the substrate can be broken down and utilized by associated microbes and macrodetritivores also influences the nutritional quality of detritus to macroconsumers.
Settling behavior of natural aquatic particulates1
Authors: Chase Robert R. P. 
Published: March 2010

The validity of Stokes Law as an approximation to the drag force on sediments (organic‐mineral aggregates) from lacustrine and marine environments was examined under controlled laboratory conditions. The settling characteristics of aggregates in the size range of 5–500 µm were inconsistent with a Stokesian assumption. Experiments with distilled, organics‐free, and natural waters indicated that aggregate behavior is altered by the presence of naturally occurring surface coatings, solution electrolytes, and dissolved organic substances.Although rotational effects appear unimportant, the above factors combine to produce a reduction in overall nonlinear skin friction which is manifested by up to an order of magnitude increase in velocity over the predicted value for an aggregate of mean dimension (∼28.5 µm).
Effects of nutrients and temperature on decomposition of Myriophyllum spicatum L. in a hard‐water eutrophic lake1
Authors: Carpenter Stephen R. , Adams Michael S. 
Published: March 2010

Temperature, phosphorus, and nitrogen were investigated as possible factors influencing decay of Myriophyllum spicatum shoots. In laboratory experiments, nitrogen enrichment significantly increased decay rates while phosphorus enrichment did not. Similar increases in decay rate per unit of added nitrogen occurred whether nitrogen was provided as nitrate or was present as additional tissue nitrogen. Exponential decay coefficients depended on temperature with a Q10 of about 3.Predictions of decay rates during litter bag experiments were based on laboratory responses of decay rate to temperature and initial nitrogen concentration of the shoots. Observed decay rates correlated closely with predictions, demonstrating the usefulness of temperature and shoot nitrogen content in explaining variations in decay rates in Lake Wingra. However, predictions underestimated decay rates. Possible explanations for the discrepancies include slow establishment of the detrital microflora, lower nitrogen availability, and absence of animals in the laboratory incubations.
Reflectance spectroscopy of marine phytoplankton. Part 1. Optical properties as related to age and growth rate1
Authors: Kiefer D. A. , Olson R. J. , Wilson W. H. 
Published: March 2010

The optical properties of two species of marine phytoplankton were characterized by application of principles of reflectance spectroscopy. Suspensions of Thalassiosira pseudonana from batch cultures and Monochrysis lutheri from continuous cultures were placed in a spectrophotometer for measurements of diffuse spectral transmittance and reflectance. These measurements yielded values for the diffuse absorption coefficiant, a*(λ), and diffuse backscattering coefficient, b*(λ), two parameters that can be applied to calculations of the effect of phytoplankton crop size on ocean color spectra.Results show that the absorption and scattering properties of a cell suspension contain information related not only to cell concentration but also to cell age or growth rate. Most important, in batch culture the ratio a*(λ):b*(λ) decreases with age once the plateau phase has been reached, and in continuous culture the ratio of absorption to backscattering coefficients is roughly proportional to the specific growth rate of the cells. Such changes in a*(λ): b*(λ) are larger at the red absorption maximum of chlorophyll a than in the blue, where accessory pigments also contribute to the absorption coefficient.
Properties of the seawater‐air interface. Dynamic surface tension studies1
Authors: Dragcevic Dj. , Vukovic M. , Cukman D. , Pravdic V. 
Published: March 2010

The properties of the seawater‐air interface were studied by laboratory measurement of the dynamic surface tension of seawater and of samples of artificial seawater on which films of oleic and stearic acid were spread. A commercially available, automatic recording apparatus was used, consisting of a modified Langmuir trough with motor‐driven surface wiper blades, a Wilhelmy plate surface tension electric microbalance, and a recorder.Comparison of the shape of the dynamic surface tension‐surface area curves of original seawater samples with those of artificial ones showed that the “expanded‐” type surface film, produced by surface spreading of oleic acid, serves as an adequate model of conditions at the real seawater‐air interface. This model and its surface tension dynamics could be used, in addition to chemical analytical data, as a quantitative measure of the state of the seawater‐air interface and its role in controlling the transport of gases and other soluble materials between the atmosphere and the oceans.
The shape and swimming technique of Bosmina longirostris1
Authors: Zaret Robert E. , Kerfoot W. Charles 
Published: March 2010

High‐speed motion pictures have enabled us to study the swimming movements of Bosmina longirostris. These small cladocerans swim using antennal movements which superficially resemble those of a human breaststroke. The time taken for each stroke is relatively constant, and the movements of the antennae during a stroke are nearly invariant. Thus, the animals vary their average speed mainly by varying the interval between strokes.In the absence of antennal forces, a Bosmina body would move broadside. Forces produced by the antennae of a swimming Bosmina constrain the body to move edgewise. The shape of the body is not the shape which minimizes drag. The orientation and shape of the body may reflect opposing selection for reducing drag and the ability of predators to find Bosmina and for the ability of predators to manipulate Bosmina.
Vertical diffusion rates determined by tritium tracer experiments in the thermocline and hypolimnion of two lakes1,2
Authors: Quay P. D. , Broecker W. S. , Hesslein R. H. , Schindler D. W. 
Published: March 2010

Vertical diffusion rates (K(Kz) were determined by measuring for several weeks the vertical spread of an injection of tritiated water into the thermoclines and hypolimnia of Lake 227 and Lake 224 in the Experimental Lakes Area (ELA) of northwestern Ontario. Kz values of 5×10−5 and 8×10−4 cm2· s−1 were determined from the tracer experiments in the thermoclines of L227 and L224; in the hypolimnia, similar Kz determinations of 1.7×10−3 and 1.8×10−2cm2·s−1 are 20−30 times greater than the thermocline rates. Vertical diffusion rates of heat were determined over the same time and depth intervals as the tracer experiments. In each lake, heat is diffusing vertically faster than mass in the thermocline and at more equal rates in the hypolimnion. The low Kz values and the greater diffusion rate of heat than mass (tritium) indicate that molecular diffusion is important in determining the rate of vertical transport in the thermoclines of these highly stratified lakes.Vertical eddy diffusion rates (Kz') determined by the tracer experiments show an inverse proportionality to the static stability of the water column (N2), such that Kz′ ∝ (N2)−0·8. However, Kz′ values determined by measuring the hypolimnetic heating rates of eight ELA lakes (including L227 and L224) and three lakes outside ELA indicate that Kz′ ∝ (N2)−0.44. These observations suggest that in the absence of large shear where Kz′ < 10−2cm2 · s−1 the vertical diffusion rates of mass and heat show different inverse correlations to the static stability of the water column.
Sterols in decomposing Spartina alterniflora and the use of ergosterol in estimating the contribution of fungi to detrital nitrogen1
Authors: Lee Cindy , Howarth Robert W. , Howes Brian L. 
Published: March 2010

Changes in concentrations of free sterols in decomposing Spartina alterniflora indicate that this marsh grass may be a significant source of sterols, primarily sitosterol, to tidal waters. These tidal waters may then transport the sterols (adsorbed to particulate matter) to nearby coastal sediments.Estimates of bacterial and fungal biomass in the detritus show that the living cells of these microbes account for only a minor part of the relative increase in nitrogen observed during decomposition. Biomass was estimated by direct counts for bacteria and by measuring the concentration of ergosterol—a sterol specific to fungi.
Physiology of carbon photoassimilation by Oscillatoria thiebautii in the Caribbean Sea1
Authors: Li W. K. W. , Glover H. E. , Morris I. 
Published: March 2010

Surface populations of Oscillatoria thiebautii (Gom.) Geitler in the Caribbean Sea are exposed to photoinhibiting irradiances throughout most of the 12‐h light period. Oxygen inhibition of carbon assimilation at high irradiance suggested that photoinhibition was partly due to photorespiration.The pattern of carbon flow into the major end products of photosynthesis appeared to be the same for a given photosynthetic rate regardless of irradiance level. At one station, enhanced relative rates of protein synthesis were observed at low rates of photosynthesis. At another station, this effect was not observed but the proportion of 14C in polysaccharide was low while that in metabolites was high. On the basis of previous findings, colonies at the second station were interpreted to have been in a nutritionally poor state. The rates at which intracellular macromolecular pools approached saturation seemed to depend on the rate of photosynthesis.Diel estimates of in situ carbon photoassimilation rates and dark carbon loss rate lead to an estimate of carbon doubling time for surface Oscillatoria populations of 18 days.
Availability of detritus of different types and ages to a polychaete macroconsumer, Capitella capitata1
Authors: Tenore Kenneth R. , Hanson Roger B. 
Published: March 2010

In chambers containing detritus from periphyton, Gracilaria foliifera (red seaweed), or Spartina alterniflora (marsh grass) aged for various periods we compared total microcosm carbon oxidation, microbial biomass (total adenylates), and net incorporation of detritus by Capitella capitata. Oxidation of periphyton and Gracilaria‐derived detritus was higher (3%·d−1) and peaked (at 5–30 days) earlier than Spartina‐derived detritus (1%·d−1 at 190 days). The ratio of worm production to total detrital oxidation in the chamber (P:O)— the efficiency with which the detritus‐based system produces macroconsumers‐was lower for decay‐resistant detritus and increased with aging for all types.Maximum microbial biomass coincided with maximum detrital oxidation. Changes in the ratio of microbial biomass to detrital oxidation (A:O)—a relative measure of the degradability and efficiency of conversion of detritus into microbial biomass—followed those of P:O.
Glucose exchanges in a salt marsh‐estuary: Biological activity and chemical measurements1
Authors: Hanson Roger B. , Snyder James 
Published: March 2010

Spatial changes in concentrations and uptake rates of glucose in a Spartina alterniflora salt marsh estuary (Duplin River, Sapelo Island, Georgia) were determined to assess the source and fate of glucose in the system. Concentrations were highly variable along the length of the river and over several tidal periods, with high values (5–20 µg·liter −1) in March and low values (1–10 µg·liter −1) in August. Glucose was rapidly cycled in the headwaters as indicated by uptake rates and turnover times. Respiration of added [14C]glucose was relatively constant within the system and temporally.Two striking features of this system were a glucose gradient from Doboy Sound (high glucose) water toward the transitional zone (low glucose) and another one from the headwaters (high glucose) toward the transitional zone, and a decrease in activity in the 3‐µm size fraction from Doboy Sound toward the transitional zone and an increase in activity from this zone toward the headwaters. Conclusions based on various hydrological and biological time scales indicate that glucose exchange associated with the tides (i.e. glucose mixing between zones) is small compared to recycling within the system.
Grazing and predation of the grass shrimp Palaemonetes pugio1
Authors: Morgan Mark D. 
Published: March 2010

The grass shrimp Palaemonetes pugio did not significantly consume live sea grass (Halodule wrightii), but assimilation of the attached epiphytes was quite significant. Salinity changes from 11–33‰ had no effect on the amount of epiphytes assimilated but increasing the temperature from 14°–30°C exponentially increased the epiphyte consumption rate. The assimilation rate per unit body weight declined significantly for shrimp ranging from 6 to 54 mg dry weight (11–24‐mm total length). Total assimilation of epiphytes increased with shrimp size up to 25–30 mg, after which it leveled off or declined. Assimilation efficiencies averaged about 83% and were not affected by changes in temperature and salinity.Small shrimp (11–15 mm) did not prey on mysids but larger ones (19–22 mm) did. The maximum consumption rate was six mysids per shrimp per day and was attained at a mysid density of about 400·m−2. Halodule without epiphytes did not provide a refuge for the mysids, but the addition of epiphytes as an alternative food significantly reduced the predation pressure.
1,2
Authors: Pastorok Robert A. 
Published: March 2010

Laboratory experiments on prey selection by Chaoborus larvae show that predator choice as well as differential encounter rates with prey determine the composition of the diet. As the larval crop and midgut become filled with food during a feeding bout, the predator avoids eating some available Daphnia and specializes on Diaptomus. After 3 days of starvation at 15°C, the gut system is empty and Chaoborus attacks prey indiscriminately. Then, daphnids are overrepresented in the diet because the predator encounters them more frequently than copepods of equal size. Daphnia swims about twice as fast as Diaptomus and “encounters” a stationary “electric eye” at twice the rate measured for cop epods. The strike efficiency of larvae for encountered prey is the same for both species.Since feeding selectivity is inversely proportional to larval hunger state, prey selection varies with the abundance of prey and season. In general, larvae collected during autumn have lower feeding rates and are more selective than larvae collected during summer. When food increases, previously opportunistic larvae may become selective within a few hours; but satiated larvae take several days to relax their preferences under a lowered food regime.
Developing a multivariable prognostic model for pancreatic endocrine tumors using the clinical data warehouse resources of a single institution
Authors: Anagnostou Valsamo , Hartvigsen Gunnar , Hripcsak George , Weng Chunhua , Botsis Taxiarchis 
Published: March 2010

Summary
Objective: Current staging systems are not accurate for classifying pancreatic endocrine tumors (PETs) by risk. Here, we developed a prognostic model for PETs and compared it to the WHO classification system.
Methods: We identified 98 patients diagnosed with PET at NewYork-Presbyterian Hospital/Columbia University Medical Center (1999 to 2009). Tumor and clinical characteristics were retrieved and associations with survival were assessed by univariate Cox analysis. A multivariable model was constructed and a risk score was calculated; the prognostic strength of our model was assessed with the concordance index.
Results: Our cohort had median age of 60 years and consisted of 61.2% women; median follow-up time was 10.4 months (range: 0.1-99.6) with a 5-year survival of 61.5%. The majority of PETs were non-functional and no difference was observed between functional and non-functional tumors with respect to WHO stage, age, pathologic characteristics or survival. Distant metastases, aspartate aminotransferase-AST and surgical resection (HR=3.39, 95% CI: 1.38-8.35, p=0.008, HR=3.73, 95% CI: 1.20-11.57, p=0.023 and HR=0.20, 95% CI: 0.08-0.51, p<0.001 respectively) were the strongest predictors in the univariate analysis. Age, perineural and/or lymphovascular invasion, distant metastases and AST were the independent prognostic factors in the final multivariable model; a risk score was calculated and classified patients into low (n=40), intermediate (n=48) and high risk (n=10) groups. The concordance index of our model was 0.93 compared to 0.72 for the WHO system.
Conclusion: Our prognostic model was highly accurate in stratifying patients by risk; novel approaches as such could thus be incorporated into clinical decisions.
Sites of Memory or Aids to Multiculturalism? Conflicting Uses of Jewish Heritage Sites
Authors: Clark David 
Published: March 2010

The immediate postwar in Europe was characterised by collective amnesia concerning where Jews had lived prior to the Holocaust. By the 1970s and mid-1980s, there was a revival of interest in residential areas, synagogues and cemeteries connected with a Jewish past, right throughout Europe, including former communist countries in the 1990s. This resulted in much renovation and the attempt to provide new uses for such sites as museums and cultural centres. My paper focuses on the shift in emphasis from the need to preserve such sites as places of memory to an increasing concern with other issues. Such issues range from tourism promotion to the promotion of multiculturalism. This emphasis on preparing the younger generation for a future in a new multicultural state provides much of the motivation for central and local government to lend support to such initiatives, whether in Sweden, Germany or Italy, for instance. The paper focuses on the Jewish Museum in Bologna, where I conducted fieldwork between 1999 and 2002. The study illustrates the mix of policy objectives involved, such as heritage preservation, urban regeneration, cultural policy and educational objectives. The theoretical discussion seeks to combine Clifford's notion of the museum as a contact zone (Clifford, 1997) with Foucault's notions on discourse formation (Foucault, 1972). In the process, the analysis of the museum's political economy extends beyond the four walls of the museum into the adjoining space of the ghetto and the city.