bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental studies of physical factors affecting seston transport in streams1
Authors: Webster J. R. , Benfield E. F. , Golladay S. W. , Hill B. H. , Hornick L. E. , Kazmierczak R. F. , Perry W. B.
Published: April 2010

We conducted three series of experiments in laboratory and natural streams to evaluate effects of various physical factors on seston (particulate organic matter) retention, entrainment, and transport. Results of laboratory experiments showed that substrate characteristics were important in determining retention of all sizes of seston. Retention increased with roughness and substrate complexity. During simulated storms in laboratory streams, seston concentrations were not generally correlated with discharge. However, we found strong correlation between seston concentration and the rate of increase in discharge during rising hydrographs, and, after peak discharge, seston concentration dropped exponentially independent of discharge. Simulated storms conducted in a natural stream channel supported those findings. Results of these experiments and published field studies suggest that existing sediment transport models have little application to seston transport in small streams primarily because of limited availability of seston. During baseflow, seston transport depends on the rate of biological particle generation and retention characteristics of the streambed. Seston transport during storms depends on the rate of increase in discharge, streambed retention, and the availability of particulate organic material on the streambed.
Short‐term changes in the biology of a Gulf Stream warm‐core ring: Phytoplankton biomass and productivity1
Authors: Hitchcock Gary L. , Langdon C. , Smayda T. J.
Published: April 2010

Temporal changes in chlorophyll a and primary production were followed in a Gulf Stream warm‐core ring as it underwent an interaction with the Gulf Stream and a subsequent wind event. As the physical events altered the structure of the mixed layer, Chl a within the euphotic zone increased from about 10 to 42 mg m−2 while productivity rates increased from 140 to >2,400 mg C m−2 d−1. Carbon‐specific growth rates in Ring 81‐D derived from ATP‐C biomass and 14C productivity rates increased fivefold. Nanoplankton (<20 µm) initially accounted for nearly 90% of the total Chl a biomass in ring surface waters, although there was a subsurface maximum of net‐plankton Chl a near the base of the euphotic zone before the wind event. After the wind event, Chl a was uniformly distributed throughout the mixed layer and net plankton accounted for an increased proportion of total Chl a standing stock and productivity. In the peripheral high velocity region and the surrounding Slope Water, phytoplankton standing stocks and productivity rates were less than the maximum values found at ring center. Our observations indicate that phytoplankton standing stock and productivity within a warm‐core ring can increase rapidly in response to physical processes on the event time scale.
A study of the extraction conditions of sedimentary humic acids to estimate their true in situ sulfur content
Authors: Francois R.
Published: April 2010

Precautions are necessary to extract the humic acid fraction from anoxic marine sediments without artificially raising its sulfur content. Elemental sulfur and free sulfides must be removed from the sample before proceeding with alkaline extraction. Also, the extent of sulfur contamination from coextracted pyrite and greigite must be estimated. In my procedure the sediment samples were freeze‐dried immediately after their extrusion under a nitrogen atmosphere onboard ship. Humic substances were extracted by 0.5 N NaOH after removal of elemental sulfur from the dried sediment with benzene, which also removed the lipid materials. Humic acids were precipitated from the alkaline solutions by acidification to pH 2 with HCl. The formation of elemental sulfur by the oxidation of H2S produced by decomposition of coextracted acid‐volatile sulfides was minimized by precipitating humic acids under a vigorous stream of nitrogen. Precipitates were freeze‐dried and their elemental composition determined. Subsequently, samples were treated with a freshly prepared CrCl2 solution, and the amount of H2S produced was measured to estimate the sulfur contribution of coextracted pyrite and greigite.
Temperature and velocity microstructure caused by swimming fish1
Authors: Farmer David D. , Crawford Gregory B. , Osborn Thomas R.
Published: April 2010

Simultaneous acoustic and microstructure measurements obtained from a submarine showed a rapid increase in turbulent dissipation coincident with its passage through water vacated by a school of fish. The effect is attributed to the wake left by part of the school as it moved out of the submarine’s path. Avoidance behavior of this type also occurs in the vicinity of free‐fall microstructure probes; it is suggested that microstructure profiles may include such biological sources of turbulence when taken in waters having substantial aggregations of fish.
Algal cell size and the maximum density and biomass of phytoplankton1
Authors: Agusti Susana , Duarte Carlos M. , Kalff Jacob
Published: April 2010

The maximum density that algal cells can reach in culture varies as the −1.27 power of the cell volume. This size‐dependent density boundary results in a size‐dependent biomass boundary, with the maximum biomass changing as the −0.32 power of cell volume. The existence of size‐dependent maximum biomass and density appears to be the consequence of algal self‐shading, the efficiency of light absorption by algae, and their effect on light absorption being dependent on cell size. The size‐dependent density and biomass boundaries are comparable to the qualitatively similar boundary described by the −3/2 power rule for higher plants.
Advantages to microbes of growth in permeable aggregates in marine systems1
Authors: Logan Bruce E. , Hunt James R.
Published: April 2010

Highly porous microbial aggregates occur in a variety of environments ranging from marine snow in oceans to flocs in biological reactors. For permeable aggregates undergoing gravitational settling or subjected to fluid shear, predicted velocities of intra‐aggregate flow range from 1 to 100 µm s−1. Estimation of intra‐aggregate velocities requires specification of the aggregate size, porosity, and permeability, as well as a mean fluid shear rate characterizing the fluid turbulence. We have examined substrate removal by microorganisms in permeable aggregates with an analysis of mass transfer. The overall uptake by bacteria in aggregates can be up to 60% greater than uptake by dispersed bacteria. In general, a model of substrate uptake based on advective transport is more appropriate than a model based on diffusive transport for cells in large, permeable aggregates that utilize substrates with diffusivities <10−6 cm2 s−1.
Experimental study of size‐selective phytoplankton grazing by a filter‐feeding cichlid and the cichlid's effects on plankton community structure1
Authors: Drenner Ray W. , Hambright K. David , Vinyard Gary L. , Gophen Moshe , Pollingher Utsa
Published: April 2010

In laboratory experiments, feeding rates of small (40–61‐mm standard length, SL) and large (98–143‐mm SL) Galilee Saint Peter’s fish (Tilapia galilaea) on phytoplankton and zooplankton increased as a function of particle size, leveling off when particle size exceeded 6–10 µm. Fish had high feeding rates on zooplankton, the large dinoflagellates Peridinium cinctum and Peridinium elpatiewsky, and a few nanoplankton, but most species of nanoplankton were consumed at lower rates.

To examine community‐level effects of the fish, we conducted two 7‐d outdoor tank experiments with six fish‐density treatments ranging from 0 to 400 g m−3. Crustaceans, rotifers, and Peridinium spp. declined as functions of fish density, but nanoplankton abundance was highest at intermediate fish densities. Suppression of Peridinium spp. by fish resulted in a reduction of total chlorophyll and gross primary production.
Boundary‐layer and internal diffusion effects on phosphorus fluxes in lake periphyton1
Authors: Riber Hans H. , Wetzel Robert G.
Published: April 2010

Phosphate uptake kinetics of periphyton were evaluated by addition of carrier‐free radiophosphate under controlled laminar flow conditions. In most cases, excluding only poorly colonized substrata, tracer fluxes were found to be limited by boundary‐layer mass transfer. Tracer flux could be described as a power function of flow velocity and as a negative power function of distance from the leading edge of the communities, as expected from mass transfer calculations. Observed deviations from theoretical functions were interpreted as effects of community patchiness and of internal water flow in the periphyton matrix. Phosphate turnover by periphyton in suspension was within the range of values for lake plankton, when related to biomass. Kinetic calculations based on these turnover measurements indicated that internal recycling of phosphate and recycling from the boundary layer, rather than external uptake, accounted for most phosphate turnover within intact periphyton films. This situation is likely typical under oligotrophic conditions. Boundary‐layer thickness was within the range of published estimates from littoral systems. The results indicate that chemical conditions within periphyton communities differ considerably from the immediate surroundings and that boundary‐layer development is a key factor affecting the metabolism of periphyton communities.
A whole‐core squeezer for interfacial pore‐water sampling1
Authors: Bender Michael , Martin William , Hess Jennifer , Sayles Fred , Ball Lary , Lambert Claude
Published: April 2010

The “whole‐core squeezer” is a simple pore‐water sampler designed for millimeter depth resolution near the sediment‐water interface. Various tests have been done to determine how accurately true gradients are reproduced by whole‐core squeezing. Tracer studies show that any mixing associated with squeezing does not smear the profiles by more than a few millimeters. Benthic fluxes of SiO2 calculated from interfacial concentration gradients resolved with the whole‐core squeezer in San Clemente Basin are in good agreement with “bell‐jar” values measured with the benthic chambers of a bottom lander. Oxygen profiles determined with the whole‐core squeezer are very similar to values determined with an oxygen microelectrode. These comparisons confirm that interfacial gradients and (by calculation from models) fluxes of O2, NO3−, SiO2, and other particle‐unreactive ions and molecules can be determined with the instrument. On the other hand, the composition of squeezed pore waters is very susceptible to rapid alteration by solid‐solution reactions. Therefore the method is not suitable for determining pore‐water profiles of trace metals and other particle‐reactive chemicals.
An experimental mesocosm study of residual and contemporary effects of an omnivorous, filter‐feeding, clupeid fish on plankton community structure1
Authors: Threlkeld Stephen T. , Drenner Ray W.
Published: April 2010

We conducted three changeover experiments in large outdoor tanks to evaluate the persistence of effects of an omnivorous, filter‐feeding, clupeid fish (Dorosoma cepedianum) on plankton community structure in different seasons. The experimental design included four prechangeover treatment combinations of Dorosoma and a zooplanktivorous atherinid fish, Menidia beryllina (neither, one, or both fishes present). At the changeover, we moved Dorosoma from half of the tanks containing Dorosoma to half of the tanks previously lacking Dorosoma. Enhancement of phytoplankton by Dorosoma in the prechangeover period was a persistent effect in the December–February and July‐September changeover experiments. In the April–June experiment, phytoplankton responded primarily to the postchangeover Dorosoma treatments and showed few residual effects. Zooplankton effects of Dorosoma were not persistent. Menidia enhanced phytoplankton in the April–June experiment only, even though it reduced crustacean zooplankton in all three changeover experiments. Seasonal differences in effects on phytoplankton by Menidia and between residual and contemporary effects of Dorosoma appear to be related to the presence of large‐bodied Daphnia in the April–June experiment.
Phytoplankton population dynamics and the fate of production during the spring bloom in Auke Bay, Alaska1
Authors: Laws Edward A. , Bienfang Paul K. , Ziemann David A. , Conquest Lytha D.
Published: April 2010

Primary production rates and the concentrations and vertical fluxes of phytoplankton pigments were measured in Auke Bay, Alaska, on a twice‐weekly basis over a period of 56 d spanning the 1985 spring bloom. Application of a slightly modified version of the Welschmeyer‐Lorenzen equations yielded growth rates that were in excellent agreement with the ratio of primary production to particulate carbon in the water column. These results suggest that the assumption in the Welschmeyer‐Lorenzen model that chlorophyll a is converted to pheopigments with an efficiency of about 66% as a result of zooplankton grazing is probably close to the truth in this system. Of the primary production that occurred during the study period, about 40% was lost from the euphotic zone due to the sinking of viable cells and 58% was lost due to zooplankton grazing. Only about 1.5% of the primary production remained in the euphotic zone in the form of additional phytoplankton biomass at the end of the study. Herbivorous zooplankton were estimated to be assimilating at least 58% of the phytoplankton carbon they ingested—a conclusion in reasonable agreement with previously published laboratory studies. Although phytoplankton biomass in this system appears to be limited by the supply of nitrate, phytoplankton growth rates seem to be limited by either irradiance or temperature.
Observations and a model concerning the translational velocity of a photosynthetic marine dinoflagellate under variable environmental conditions1
Authors: Kamykowski Daniel , McCollum Steven A. , Kirkpatrick Gary J.
Published: April 2010

The movement of a representative photosynthetic marine dinoflagellate, Gyrodinium dorsum, was videotaped on a temperature‐gradient plate, in a single‐chambered, water‐jacketed cuvette and in a six‐chambered, light‐gradient, water‐jacketed cuvette. The tapes were analyzed with intercalibrated manual or computer‐assisted techniques. The swimming ability of G. dorsum varied in response to changes in temperature, light intensity, and buoyancy. A FORTRAN computer model combined mathematical formulations describing these empirical responses and some assumed covariation to predict the instantaneous translational velocity of G. dorsum. After the model was verified with an independent data set collected from the single‐chambered, water‐jacketed cuvette, it was used to simulate imposed diel vertical migrations in thermally stratified coastal water. The translational velocity of G. dorsum varied about 3‐fold in response to the imposed environmental variation. This modulation of the translational velocity of a photosynthetic marine dinoflagellate can combine with variability of the physical motion spectrum to affect the temporal and spatial occurrence of the organism and the suitability of its growth conditions.
Nitrate release by Caribbean reef sponges1,2
Authors: Corredor Jorge E. , Wilkinson Clive R. , Vicente Vance P. , Morell Julio M. , Otero Ernesto
Published: April 2010

Two coral reef sponges were examined in situ off Puerto Rico for fluxes of dissolved inorganic nitrogen. Chondrilla nucula, a ubiquitous Caribbean sponge with cyanobacterial symbionts, releases large amounts of nitrate [600 nmol N g‒1 (dry wt) h‒1; 4,000 µmol N m‒2 h‒1. Since C. nucula covers a mean of 12% of the substratum, it potentially contributes between 50 and 120% of the nitrogen required to sustain reef productivity. Anthosigrnella varians, a common sponge with zooxanthellae symbionts releases lesser amounts of nitrate [19 nmol N g‒1 (dry wt) h‒1; 20 µmol N m‒2 h Although A. varians may cover between 1.2 and 11% of the reef substratum, the potential contribution is <1% of the nitrogen required for reef productivity. These release rates for C. nucula are comparable to those reported for nitrogen fixation in reef environments and in excess of rates reported for nitrate production by other reef substrata. Large populations of non‐photosynthetic symbiotic bacteria are considered to nitrify amino nitrogen to nitrate and the differences are attributed to the size of bacterial populations and the nature of photosynthetic symbionts.
Fast‐response oxygen sensor for a free‐fall CTD
Authors: Atkinson M. J.
Published: April 2010

A new, solid‐state, multiple‐component cathode, three‐electrode oxygen sensor has been adapted for use on a free‐fall CTD. Semipermeable membranes are not required for the sensor, giving it a very fast response time. The sensor is flow sensitive but with adequate control of the drop‐speed of the CTDO and appropriate electronic filtering, a vertical sampling resolution of 5 cm can be achieved. Changes in oxygen concentration of 3 µM (0.067 mg liter‒1) can be detected.
Precise shipboard determination of dissolved oxygen (Winkler procedure) for productivity studies with a commercial system1
Authors: Oudot Claude , Gerard Robert , Morin Pascal , Gningue Itaf
Published: April 2010

An automatic system of dissolved oxygen titration based on a potentiometric endpoint detector is described. The equipment is a simple commercial apparatus that can be used by a relatively unskilled operator. The C.V. of the oxygen measurement is 0.1% The titration is quick (3–5 min) and suitable for field studies of phytoplankton production and related subjects.
Discoveries and testable hypotheses arising from Coastal Zone Color Scanner imagery of southern Lake Michigan1
Authors: Mortimer C. H.
Published: April 2010

CZCS (Coastal Zone Color Scanner) images, confined mainly to the southern basin of Lake Michigan during the warm‐up phases of 1979, 1980, and 1981, have furnished tools for synoptic reconnaissance of the wind‐perturbed transition of the thermal regime in large basins from the winter to summer condition (including front formation and upwelling events), the coupling of phytoplankton growth with that transition, the intermittent mobilization and surface transport of sediment resuspended by storms, and the extensive temporary trapping of river‐derived dissolved organic matter (gelbstoff) between the shoreline and the offshore‐migrating thermal front. Intermittent resuspension of particles and variable inputs of gelbstoff, which occur in many coastal waters, render inapplicable the CZCS algorithms successfully used in ocean studies for atmospheric correction and for quantification of phytoplankton chlorophyll. That disappointment notwithstanding, there is a favorable match of the coverage and scene‐revisit frequency of the CZCS and the space and time scales of significant features of the above‐listed processes. The observed pattern changes shed new light on the above processes and generate several testable conjectures. These relate to whole‐basin sediment transport, coastal upwelling of near‐bottom sediment suspensions, and frontal hydrodynamics and its coupling with phytoplankton distributions.
Density‐dependent predation of early instar Chaoborus feeding on multispecies prey assemblages1
Authors: Moore Marianne V.
Published: April 2010

Prey selectivity and predation rates by second‐instar Chaoborus punctipennis feeding on a three‐species rotifer assemblage were determined in a laboratory experiment. Chaoborus became less selective at the two highest of five total prey densities which ranged from 180–2,880 prey liter−1. This change in selectivity seemingly contradicts optimal foraging theory, but may have occurred because Chaoborus used different search tactics at different prey densities. When feeding on rotifers, Chaoborus exhibited a type 2 functional response and achieved predation rates among the highest reported for an aquatic invertebrate predator. Chaoborus predation rates were high primarily because of rapid handling times (ingestion and digestion) which were quantified with Holling’s disk equation and direct observations. Digestion was particularly rapid with crop evacuation times as brief as 15–30 min for a food bolus of soft‐bodied Synchaeta pectinata. The use of functional response experiments for determining Chaoborus predation rates is recommended over the application of digestion time to crop contents of field‐collected Chaoborus, because crop passage time of Chaoborus is variable.
The seasonal variation of dimethyl sulfide and dimethylsulfoniopropionate concentrations in nearshore waters1
Authors: Turner Suzanne M. , Malin Gillian , Liss Peter S. , Harbour Derek S. , Holligan Patrick M.
Published: April 2010

Concentrations of biogenic dimethyl sulfide (DMS) in seawater around mainland Britain in winter and summer (1985) ranged from 1 to 1,100 ng S (DMS) liter−1. The mean winter DMS concentration was 4 ng S (DMS) liter−1 compared with the mean summer concentration of 220. Analyses of phytoplankton species composition in summer indicate that the main sources of DMS were coccolithophores, various dinoflagellates including the bloom species Gyrodinium aureolum, and certain unidentified taxa of small flagellates. Concentrations of dimethylsulfoniopropionate (DMSP), the precursor of DMS, were measured in 53 of the summer samples, and its mean concentration was about an order of magnitude greater than that of DMS. Particulate (>0.2 µm) and dissolved fractions of DMSP were operationally resolved, with the latter showing the stronger correlation with DMS.

Preliminary estimates for the areal and temporal average flux of sulfur (DMS) from the North Sea to the atmosphere during summer are of the order of 103 µg S m−2 d−1, a 60‐fold increase over winter flux. Biogenic emission in summer is equivalent to about 16% of the spatially averaged anthropogenic emission from Europe.
Sulfate reduction in the presence of low oxygen levels in the water column of the Cariaco Trench1,2
Authors: Hastings David , Emerson Steven
Published: April 2010

Precise and closely spaced alkalinity and total inorganic carbon measurements from the water column of the Cariaco Trench indicate an intense zone of sulfate reduction within the oxic waters above the O2‐H2S interface. The chemical data suggest that sulfate reduction occurs in the presence of low oxygen levels. The resulting sulfide is subsequently oxidized to S0. Although it is not clear whether or how these processes are coupled, the kinetics of redox reactions above the oxic‐anoxic interface modify the chemical distributions expected from the normal constraints of chemical equilibrium.
Effects of fertilization and planktivorous fish (yellow perch) predation on size distribution of particulate phosphorus and assimilated phosphate: Large enclosure experiments1
Authors: Mazumder A. , McQueen D. J. , Taylor W. D. , Lean D. R. S.
Published: April 2010

Nutrients, planktivorous fish (1 + yellow perch), or both were added to eight large enclosures in a 2 × 2 factorial design. The size distributions of particulate phosphorus (PP) and assimilated 32PO43− and PO43− turnover times were determined from June through August by filter fractionation. The amount of PP >200 µm (mesoplankton) increased with fertilization and decreased with addition of fish, but the amount of PP in nanoplankton (3–20 µm) and large picoplankton (1–3 µm) showed opposite results. Fertilization and addition of fish had interacting effects on the PP in microplankton (20–200 µm). Microplankton phosphorus was higher with fish in unfertilized enclosures and lower with fish in fertilized enclosures. Slopes estimated from the relationship between the proportion of PP retained and the logarithm of filter size were used to characterize the size spectra of plankton and were lower with fertilization and steeper with addition of fish. They were negatively correlated with PO43− turnover time, reflecting that plankton communities dominated by small cells were more nutrient limited. The slope parameter was also significantly correlated with water clarity (Secchi depth) and algal biomass (Chl a), but particle size distribution contributed to water clarity independent of biomass or pigment concentration. This slope parameter can be used as a convenient indicator of plankton size spectra and trophic interactions in freshwater ecosystems.
A simple, reliable, and inexpensive pore‐water sampler1
Authors: Jahnke Richard A.
Published: April 2010

A simple technique for extracting pore water from sediment cores has been developed. The overall concept of this procedure is to gently pressurize an intact sediment subcore, forcing the pore fluids to be expelled through sampling ports located at specific depths in the core barrel wall. Although this technique does not necessarily improve the integrity of the sample obtained for most solutes, it is much easier to perform than previously reported procedures. Because this technique does not require the sediments to be sectioned into sampling intervals before pore‐water extraction, it is rapid and eliminates the need for walk‐in cold vans, specialized equipment such as sediment squeezers, high‐speed centrifuges and gimbals, and glove bags (for sampling anoxic sediments).
Estimation of absorption coefficients of scattering suspensions using opal glass
Authors: Bannister T. T.
Published: April 2010

Previously, the algal absorption product (absorption coefficient at wavelength times cuvette depth) was estimated as Dλ − D750, the difference in optical densities of a suspension, measured against water in opal glass cuvettes. Such estimates are subject to “cuvette error” dependent on dimensions and materials of the cuvettes and to “A error” due to inadequacy of 750 nm as a reference wavelength. Monte Carlo calculations were performed to assess cuvette error; then limits of the combined cuvette and λ errors were explored. With cuvettes and suspensions used previously, the combined error was usually ±10% (10–20% at 440 nm), not 100% as supposed in a recent publication. Cuvette error is minimal in cubical cuvettes with black sidewalls, but substantial λ error may still occur. Both errors are avoided in a method using two pairs of opal cuvettes.
Copper complexation in the Northeast Pacific
Authors: Coale Kenneth H. , Bruland Kenneth W.
Published: April 2010

Copper titrations were conducted at sea with differential pulse anodic stripping voltammetry to examine the degree to which copper was associated with organic ligands. Greater than 99.7% of the total dissolved copper in surface waters of the central Northeast Pacific shallower than 200 m was estimated to be associated with strong organic complexes. Below 200 m, increasing proportions of inorganic or labile copper species were observed. At middepths (1,000 m), about 50–70% of the total dissolved copper was in the organically complexed form. Whereas total copper varies by a factor of only three from the surface to middepths (0.6–1.8 nM), copper complexation gives rise to extremely low cupric ion activities in surface waters ({Cu2+} = 1.4 × 10−14 M) and higher values at middepth ({Cu2+} = 10−11 M)—a variation of three orders of magnitude. Two classes of copper‐binding ligands were found to be responsible for this complexation: an extremely strong ligand class [log K′cond (Cu′) = 11.5] at low concentrations (∼ 1.8 nM) which dominated copper complexation in the surface waters and decreased with depth, and a weaker class of ligands [log K cond(Cu′) = 8.5] at higher concentrations (8–10 nM) which was observed throughout the water column and showed no apparent structure in its vertical distribution. These findings have significant implications concerning the toxicity and bioavailability of copper in open ocean systems.
Methylamine uptake by zooxanthellae‐invertebrate symbioses: Insights into host ammonium environment and nutrition
Authors: D'Elia Christopher F. , Cook Clayton B.
Published: April 2010

Cnidarians with endosymbiotic algae (=zooxanthellae) take up dissolved inorganic nutrients from seawater, but neither the physiological mechanisms nor the effect of host nutrition on transport kinetics is known. We used the NH4+ analogue [14C]methylamine ([14C]MA) to examine these aspects of NH4+ uptake by a sea anemone (Aiptasia pallida) and a coral (Madracis decactis).

Both intact symbioses and isolated zooxanthellae took up [14C]MA. In anemones, uptake rates per algal cell increased with time after feeding. Uptake rates for isolates from hosts unfed for 7– 10 d were linear for at least 200 min, slightly light‐dependent, and conformed to Michaelis‐Menten kinetics (Ks = 68 µM; V = 3.8 mol 10−18 cell−1 s−1). Isolates from well‐fed hosts took up [14C]MA much less rapidly at all concentrations tested and did not exhibit saturable uptake kinetics. NH4+ competitively inhibited [14C]MA uptake by isolated algae (inhibition constant = 4.0 µM) and reduced [14C]MA uptake by intact symbiotic anemones. We hypothesize that [14C]MA (and by analogy NH4+) uptake occurs by a “depletion‐diffusion” mechanism in intact symbiotic anemones with zooxanthellae maintaining very low intracellular [14C]MA and NH4+ concentrations in host tissue and that [14C]MA uptake kinetics will be useful in evaluating the nutritional status of corals and similar symbiotic associations under field conditions.
Food web structure on Georges Bank from stable C, N, and S isotopic compositions
Authors: Fry Brian
Published: April 2010

A combination of stable isotopic measurements was used to study food web structure of Georges Bank, an important northwestern Atlantic fishing ground. Particulate, invertebrate, and fish samples were analyzed to test δ13C, δ15N, and δ34S measurements as trophic‐level indicators in offshore systems. Neither sulfur nor carbon measurements proved valuable. Sulfur isotopic compositions showed little change with trophic level, and an apparent diversity of phytoplankton carbon isotopic inputs at the base of the food web complicated use of δ13C to estimate trophic position. Nitrogen isotopic distributions were, however, robust measures of trophic position and showed four broad trophic levels; unsampled large top carnivores may represent a fifth trophic level.
The design and use of a hydraulic potentiomanometer for direct measurement of differences in hydraulic head between groundwater and surface water
Authors: Winter T. C. , LaBaugh J. W. , Rosenberry D. O.
Published: April 2010

The hydraulic potentiomanometer described herein consists of a potentiometer connected to a manometer by a flexible tube. The device is used to directly measure the direction of seepage as well as the hydraulic‐head difference between groundwater and surface water. The device works most effectively in sandy materials. For accurate measurements the device must be free of air leaks.
Interannual variation in seasonal predation: Its origin and ecological importance1
Authors: Hairston Nelson G.
Published: April 2010

Between‐year variation in the springtime mortality of the copepod Diaptomus sanguineus is quantified using 8 yr of data from a single population in Bullhead Pond, Rhode Island. The mortality is ascribed to increased fish feeding activity when the water warms. The timing of the onset of predation and its intensity are quantified using the seasonal dynamics of adult copepod sex ratio. Females are more vulnerable to predation than males, and the slope of a plot of sex ratio vs. time is >0 when the fish begin to influence the copepod population. The magnitude of the slope is an index of predation intensity.

The annual onset of predation and its intensity are each significantly correlated with fish density, and fish density is a function of pond volume. Pond volume fluctuates between years, driving the dynamics of this predator‐prey interaction. Annual variation in pond volume is related to groundwater level, which in turn is related to annual rainfall. Groundwater and rainfall records from the USGS and NOAA permit estimates of the extent of variation in springtime copepod mortality over a 38–45‐yr period.
Analyzing population dynamics of zooplankton1
Authors: Taylor Barbara E.
Published: April 2010

Demographic analyses of zooplankton populations are commonly based on an exponential population growth model and a birth rate calculated from the ratio of eggs per female, an approach originally developed by W. T. Edmondson. The birth rate estimates are reliable when departures from the assumptions about exponential growth are moderate. Death rates are calculated as the difference between birth and growth rates and are less reliable because they incorporate errors of both components. These demographic analyses are most accurate during periods of stable or slowly changing conditions. Computer simulations were used to examine the effects of sampling and counting efforts on confidence limits for the rate estimates in homogeneous and patchy environments.
Primary productivity, nutrients, and transparency during the early onset of eutrophication in ultra‐oligotrophic Lake Tahoe, Califomia‐Nevada1
Authors: Goldman Charles R.
Published: April 2010

For more than half a century, the trophic status of water bodies has been of interest to limnologists and oceanographers alike. This report demonstrates the close, inverse relationship between 14C‐estimated primary productivity and transparency during the earliest stages of cultural eutrophication. As the population in the Tahoe basin has rapidly increased, Lake Tahoe has been characterized by an increase in primary productivity that has averaged 5.6% yr‒1 for the last 28 yr. There has been a concomitant decline in transparency of 0.37 m yr‒1. During winter months when transparency is highest, the average annual loss has been slightly greater (0.40 m yr‒1). The average annual Secchi depth has decreased by 7 m during the last 19 yr of intensive monitoring. There has also been a significant increase in the light extinction coefficient. Photosynthetic efficiency has increased while there has been a gradual shrinkage of the euphotic zone. During the same period the total NO3‐‐N content of the lake has increased significantly, but total P content has not. Lake Tahoe primary production has become increasingly P sensitive during the last decade as N has accumulated in the system. A gradual increase in the N:P may prove to be a general evolutionary characteristic of oligotrophic lakes during the earliest stages of eutrophication. The importance of long‐term studies in detecting gradual change that may be masked by considerable interannual variability is particularly evident from this study.
Defensive spines: Inverse relationship between coefficients of variation and size1
Authors: Kerfoot W. Charles
Published: April 2010

Coefficients of variation for spine lengths are not constant over a range of mean values, but show an inverse relationship with sample means. The nearly hyperbolic relationship is evident in selection experiments, in seasonal samples from a single lake, and in widely dispersed geographic samples. The observed inverse relationship could indicate an interesting developmental property (e.g. that smaller, rudimentary spines are more variable than larger functional ones) or could reflect one of several possible statistical artifacts or properties.

Detailed examination of Bosmina suggests that the strong inverse trend arises from a combination of biological and statistical properties; it is not an artifact of measurement error, although measurement error contributes to inflation of small values. Small spines are inherently more variable than longer spines, and the latter have more uniform component parts. Moreover, there are several alternative arrangements of components that sum to the same length and hence that achieve nearly equivalent fitness value. These alternative arrangements lower part‐whole correlations within the population.

The two statistical properties that contribute to observed trends include a version of the central limit theorem and measurement error. The percentage variation of a character which is the sum of a number of randomly varying parts will be considerably less (roughly as the inverse square root of the number of parts) than the mean percentage variation of the parts themselves. Thus a statistical property of large numbers contributes to the observed inverse trend. In addition, coefficients of variation as fractions are especially sensitive to measurement error, so that precise measurements are recommended for small defensive spines.
Saprophytic Mycotic Infections of the Nose and Paranasal Sinuses
Authors: Kameswaran Mohan , Raghunandhan S
Published: April 2010

The kingdom of fungi is ubiquitous and omnipresent, having prevailed over the tides of time, over numerous decades by adapting to various methods of survival in the susceptible host including humans. Saprophytic fungi derive nutrition from dead and decaying organic matter, with the capacity to flare up in virulence, provided the right opportunity especially when the host immunity is compromised (as in prolonged steroid therapy, diabetes, HIV infection, tissue transplant recipients) or if there is a breech in a vital barrier permitting deeper tissue penetration (postsurgical or post-traumatic). Hence, knowledge about the saprophytic fungal elements dwelling within the nose and paranasal sinuses is paramount for Otolaryngologists worldwide, in order to accurately diagnose and effeciently manage such intriguing cases. This article provides a broad overview of the various opportunistic fungi in rhinology, and highlights the principles of diagnosis and protocols in management.
Rhinocerebral Mycosis: Combined Modality Protocol
Authors: Kalsotra Gopika
Published: April 2010

Rhinocerebral mycosis is an invasive fungal infection which occurs primarily in the paranasal sinuses and progresses to involve the brain and/or the orbit. It is commonly seen in immunocompromised individuals and can be most effectively treated if diagnosed early, when it is limited to the nasal cavity and the paranasal sinuses. Even though it is acceptable that surgical debridement in combination with antifungal therapy can lead to high rate of cure, the surgical approach for intracranial extension is still a subject of debate. Twenty-four cases of rhinocerebral mycosis managed at our institute are discussed, regarding presenting complaints and management.
Pain Management in Patients with Head and Neck Carcinoma
Authors: Ghei Aditi , Khot Sharmila
Published: April 2010

Pain is one of the feared effects of advancing cancer and can affect a vast majority of head and neck cancer (HNC) patients. HNC's have a devastating impact on patient's lives as both disease and treatment can affect the ability to speak, swallow and breathe due to involvement of the aerodigestive tract. The etiology of pain in this subgroup of patients could be as a result of direct tumor progression, nerve root compression or as a result of the treatment modalities including surgery radiotherapy and chemotherapy. Pain experienced could be nociceptive or neuropathic. A thorough initial and ongoing assessment of the patient is essential for diagnosis and planning the treatment bearing in mind its modification during treatment. Treatment involves a comprehensive approach which is centred around systematic pharmacotherapy, and supplemented by a range of therapeutic interventions and physical and behavioral approaches. In this article we discuss the incidence, etiology, assessment and treatment of this challenging problem using current modalities.
Management of Head and Neck Cancer: Surgical and Nonsurgical
Authors: Pradhan Sultan , Hakeem Arsheed Hussain
Published: April 2010

It is right time to review the management of head and neck squamous cancer (HNSC) because of fundamental changes in both diagnostic and therapeutic modalities. Head and neck cancer affects area highly associated with the individual's.

identity and can produce profound alteration in appearance, speech, and swallowing. Due to morbidity, disfigurement and problems of disease control clinicians used to have lot of reservations in treating complex HNSC cases. The field has taken a new vigor by incorporating important basic advances in understanding of cancer, new modalities of treatment and management of functional deficits. Although much progress has been made in understanding the molecular genetics of HNSC for novel diagnostic and therapeutic interventions, they are still far to go before becoming standard of care for head and neck cancer.
Low Birth Weight and First Week Neonatal Mortality in a Tertiary Level Hospital in Bangladesh
Authors: Khatun Sabera , Hossain Fawzia , Chowdhury Afroza
Published: April 2010

Objectives

The incidence of low birth weight babies and the perinatal morbidity and mortality is inter-related. An understanding of the risk factors can help us to reduce their incidence and studying their management and outcome could help us to evolve optimal management strategies. The aim of the study was to find out the incidence of low birth weight and first week neonatal mortality rate.

Methods

The gestational age of the babies were determined and a comparison of the prenatal mortality ratio was done among vaginal and cesarean deliveries. During the study period all the patients irrespective of their gestational age admitted for delivery were recruited for the prospective analysis. Their gestational age, mode of delivery, birth weight and outcome were collected in a preformed data-sheet.

Results

During the study period there were 2689 deliveries at BSMMU and among them 301 were low birth weight (LBW), rest were normal birth weight babies. Forty-eight from low birth weight and seven from normal birth weight babies died within first-week of delivery. The LBW babies were grouped in to three groups according to their birth weight, 1-1.5 kg = group one, 1.6-2 kg = group two, 2.1- 2.4 kg = group three. It was found that 70% babies of group I, 40% of group II and 17% of group III were in the gestational age of 28-34 weeks. On the other hand 30% babies of group I, 60% of group II and 83% of group III were in the gestational age of 35-40 weeks. 79.36% of group I, 6.67% of group II and 0.63% of group III died within 7 days of birth.

Conclusion

Significant difference (p value < 0.001) was observed in first-week neonatal mortality among normal and low birth weight babies. Therefore, it can be concluded that birth weight and gestational age is an important determining factor for early neonatal death.
The Use of Phage Display in Neurobiology
Authors: Bradbury Andrew R.M.
Published: April 2010

Phage display has been extensively used to study protein‐protein interactions, receptor‐ and antibody‐binding sites, and immune responses, to modify protein properties, and to select antibodies against a wide range of different antigens. In the format most often used, a polypeptide is displayed on the surface of a filamentous phage by genetic fusion to one of the coat proteins, creating a chimeric coat protein, and coupling phenotype (the protein) to genotype (the gene within). As the gene encoding the chimeric coat protein is packaged within the phage, selection of the phage on the basis of the binding properties of the polypeptide displayed on the surface simultaneously results in the isolation of the gene encoding the polypeptide. This unit describes the background to the technique, and illustrates how it has been applied to a number of different problems, each of which has its neurobiological counterparts. Although this overview concentrates on the use of filamentous phage, which is the most popular platform, other systems are also described. Curr. Protoc. Neurosci. 51:5.12.1‐5.12.27. © 2010 by John Wiley & Sons, Inc.
Efficient Delivery of Antibody Into Living Cells Using Hemagglutinating Virus of Japan (HVJ) Envelope
Authors: Kondo Yoshitaka , Miyata Keizo , Kato Fuminori
Published: April 2010

This unit describes a novel method for antibody delivery into living cells using HVJ (hemagglutinating virus of Japan) envelope, an inactivated Sendai virus particle. Curr. Protoc. Immunol. 89:2.16.1‐2.16.12. © 2010 by John Wiley & Sons, Inc.
Molecular Analysis of Genetic Markers for Non‐Hodgkin Lymphomas
Authors: Sholl Lynette M. , Longtine Janina
Published: April 2010

Molecular analysis complements the clinical and histopathologic tools used to diagnose and subclassify hematologic malignancies. The presence of clonal antigen‐receptor gene rearrangements can help to confirm the diagnosis of a B or T cell lymphoma and can serve as a fingerprint of that neoplasm to be used in identifying concurrent disease at disparate sites or recurrence at future time points. Certain lymphoid malignancies harbor a characteristic chromosomal translocation, a finding that may have significant implications for an individual's prognosis or response to therapy. The polymerase chain reaction (PCR) is typically used to detect antigen‐receptor gene rearrangements as well as specific translocations that can be supplemented by fluorescence in situ hybridization (FISH) and karyotype analysis. Curr. Protoc. Hum. Genet. 65:10.14.1‐10.14.25 © 2010 by John Wiley & Sons, Inc.
Comprehensive High‐Throughput Arrays for Relative Methylation (CHARM)
Authors: Ladd‐Acosta Christine , J. Aryee Martin , Ordway Jared M. , Feinberg Andrew P.
Published: April 2010

DNA methylation (DNAm) is a term used to describe the heritable covalent addition of a methyl group to cytosines at CpG dinucleotides in mammals. While methods for examining DNAm status at specific loci have existed for several years, recent technological advances have begun to enable the examination of DNAm across the genome. In this unit, we describe comprehensive high‐throughput arrays for relative methylation (CHARM), a highly sensitive and specific approach to measure DNA methylation across the genome. This method makes no assumptions about where functionally important DNAm occurs, i.e., CpG island or promoter regions, and includes lower‐CpG‐density regions of the genome. In addition, it uses a novel genome‐weighted smoothing algorithm to correct for CpG density and fragment biases present in methyl‐enrichment or methyl‐depletion DNA‐fractionation methods. It can be applied to studying epigenomic changes in DNAm for normal and diseased samples. Curr. Protoc. Hum. Genet. 65:20.0.1‐20.0.19. © 2010 by John Wiley & Sons, Inc.
Microstructural Characterization of Lamellar Features in TiAl by FIB Imaging
Authors: Peter Dennis , Eggeler Gunther , Wagner Martin Franz‐Xaver
Published: April 2010

A novel experimental procedure is introduced to determine phase fractions and the distribution of individual phases of TiAl‐based two‐phase alloys using the focused ion beam (FIB) technique. Two γ‐titanium aluminide alloys with a fine‐grained duplex and a nearly lamellar microstructure are examined. The special FIB‐based preparation procedure results in high contrast ion beam‐induced images for all investigated alloys and allows to quantify the phase contents easily by automated microstructural analysis. Fine two‐phase structures, e.g. lamellar colonies in γ‐TiAl, can be imaged in high resolution with respect to different phases. To validate the FIB‐derived data, we compare them to results obtained with another method to determine phase fractions, electron back‐scatter diffraction (EBSD). This direct comparison shows that the FIB‐based technique generally provides slightly higher α2‐fractions, and thus helps to overcome the limited lateral resolution near grain boundaries and interfaces associated with the conventional EBSD approach. Our study demonstrates that the FIB‐based technique is a simple, fast, and more exact way to determine high resolution microstructural characteristics with respect to different phase constitutions in two‐phase TiAl alloys and other such materials with fine, lamellar microstructures.