bluuebunny/crossref_metadata_2025 huggingface dataset:
Reflectance spectroscopy of marine phytoplankton. Part 2. A simple model of ocean color1
Authors: Wilson W. H. , Kiefer D. A.
Published: March 2010

Drawing upon principles of reflectance spectroscopy, we present a model of ocean color which consists of two optical components, water and phytoplankton. Diffuse spectral reflectance immediately below the sea surface is calculated from the diffuse absorption and diffuse backscattering coefficients for water and phytoplankton. Coefficients for phytoplankton were determined from measurements with a spectrophotometer of cells grown in the laboratory, coefficients for water calculated from optical measurements made in the oligotrophic waters of the Sargasso Sea. Broad spectral changes in diffuse reflectance of the model ocean were effected by increases in the total absorption and backscattering coefficients of the phytoplankton crop. These spectral changes are a function not only of crop size, but also of the age or physiological state of the cells. The study concludes with a derivation of a dichromatic function for calculating diffuse absorption by the phytoplankton crop from measured values of reflectance in a two‐component ocean and a comparison of the model with field measurements.
Composition of mucus released by coral reef coelenterates1
Authors: Ducklow Hugh W. , Mitchell Ralph
Published: March 2010

Mucus from selected Red Sea coelenterates was analyzed for protein, polysaccharide, lipid, monosaccharides, and amino acids. While the proportions of the macromolecular fractions of the different mucins varied widely, the individual makeup of the component proteins and polysaccharides was more uniform. The appearance and transformation of liquid mucus into mucus floc or web material was revealed by scanning electron microscopy (SEM). Observations on the mucus web‐forming coral Porites astreoides from Barbados suggested that sediment capture is at least partly responsible for the apparent denaturation of secreted mucus and the transformation of liquid mucus into particulate detritus.
Bacterial populations and adaptations in the mucus layers on living corals1
Authors: Ducklow Hugh W. , Mitchell Ralph
Published: March 2010

The external mucus layers of the stony coral Porites astreoides and the soft corals Palythoa sp. and Heteroxenia fuscesens are inhabited by communities of marine heterotrophic bacteria. Population levels of bacteria in coral mucus may be regulated by the self‐cleaning behavior of the host. Bacterial populations in coral mucus respond to stresses applied to the host coral by growing to higher population levels in the mucus, indicating that these are populations of viable organisms closely attuned to host metabolism. Members of these microbial populations utilize the mucus compounds and may play a role in processing coral mucus for reef detritus feeders. One such species, Vibrio alginolyticus, grows rapidly on Heteroxenia mucus, is attracted to dissolved mucus, and possesses a mechanism to maintain itself on the coral surface.
Photosynthesis and growth of Spirulina platensis (Cyanophyta) in an equatorial lake (Lake Simbi, Kenya)1
Authors: Melack John M.
Published: March 2010

A unialgal population of Spirulina platensis (Cyanophyta) was discovered and studied in Lake Simbi (Kenya), a volcanic crater soda lake. Photosynthetic rates of bottled phytoplankton reached 12,900 mg O2·m−3·h−1 and areal rates ranged from 620 to 5,220 mg O2·m−2·h1. Free water changes in dissolved oxygen varied from 2,800 to 12,000 mg O2·m−2·h−1. A principal reason for these exceptionally high rates of photosynthesis was the extraordinary chlorophyll a content of the euphotic zone—200–650 mg Chl a · m−2. Growth rate measurements based on actual weight changes yielded turnover times of 8.9–18.9 h.
Practical curve fitting
Authors: Silvert William
Published: March 2010

Several techniques for estimating parameter values and confidence ranges for nonlinear fitted curves are evaluated and compared. Simple methods for using computers for curve fitting and parameter estimation are described. Alternate methods can be tested with randomized replicate data sets.
Differential predation by the carnivorous marine copepod, Tortanus discaudatus1
Authors: Mullin Michael M.
Published: March 2010

The relative predation by adult, female Tortanus on their own nauplii and on developmental stages of Acartia clausii was determined by offering pairs of prey at several relative and absolute abundances. Predation was most intense on adult Acartia, less so on juvenile Acartia (nauplii and immature copepodites), and least on naupliar Tortanus. There was no evidence of switching.
Nocturnal feeding patterns of Mysis relicta in Lake Michigan, based on gut content fluorescence1
Authors: Grossnickle Nevin E.
Published: March 2010

Fluorometric measurements of the gut contents of Mysis relicta were used to determine the relative amount of pheopigment per animal at 0.5, 3.5, and 6.5 h after sunset. Mysid guts always contained significantly greater relative amounts of pheopigments at 3.5 than at 0.5 h after sunset; changes between 3.5 and 6.5 h after sunset were less consistent. This is taken to indicate that mysids filter feed on phytoplankton throughout their summer diel vertical migrations in Lake Michigan.
Patterns of phosphorus supply and utilization in Lake Washington and Findley Lake1,2
Authors: Richey Jeffrey E.
Published: March 2010

Patterns of phosphorus supply and utilization were investigated for 2 years. In Lake Washington, the phytoplankton bloom began in February or early March, reaching peaks of 2,165 (1974) and 1,885 mg C·m−2·d−1 (1975). Most of the P utilized was from phosphate accumulated in the water, resulting in depletions of soluble reactive phosphorus in the euphotic zone of 260‐12 mg PO4‐P·m−2. Zooplankton excretion supplied phosphate during the later stages of the bloom and in summer. In Findley Lake, the blooms were of shorter duration and reached maxima of 400–711 mg C·m−2·d−1. Phosphate was supplied from fluvial inputs and zooplankton excretion, with little accumulation (10–50 mg PO4‐P·m−2). Comparison of the measured rate constants for turnover (ki) with the constants expected for photosynthesis (ke) showed P flux patterns. In Lake Washington, ki varied from <0.05·h−1 in winter to 5–10·h−1 during summer stratification, whereas ke was comparable during prebloom and early‐bloom periods and only about 0.1·h−1 in summer. In Findley Lake, ki (2.9–5.3·h−1) was always >ke (0.05·h−1). Only after phosphate depletion did the usual pattern of rapid uptake and release occur. Nutrient addition and isotope partitioning experiments suggested that the divergence of ki and ke reflected a stressed physiological condition of the algae that prevented incorporation and promoted compensatory rapid turnover of phosphate.
Chroococcoid cyanobacteria in the sea: A ubiquitous and diverse phototrophic biomass1
Authors: Johnson Paul W. , Sieburth John McN.
Published: March 2010

In the photic zone of the open sea, procaryotic cells with an ultrastructure typical of chroococcoid cyanobacteria and similar sized populations of autofluorescent bacteria (0.5–1.0 × 1.0 µm) were observed at concentrations usually between 103–104 cells per ml. The ubiquitous ultrastructural type was an orange‐autofluorescing, phycoerythrin‐containing cyanobacterium amenable to culture. Two other morphological types which have not been cultured occur sporadically in larger concentrations, one apparently favoring deeper water. These phototrophs can account for about 20% of the total bacterioplankton biomass and from 6 to 15% of the total microbial plankton. These cells may play a significant role in oceanic primary productivity.
Body size patterns in arctic and temperate zooplankton1
Authors: Dodson Stanley I.
Published: March 2010

Do zooplankton species occur in discrete associations of large and small species? In 36 arctic tundra ponds near Barrow, Alaska, there were 21 examples of a large species association, 9 of a small association, and 6 intermediate associations. Statistically, the species do show evidence of nonrandom association. The literature of comparative examples is used to investigate the significance of intermediate species associations in the arctic ponds and elsewhere. Intermediates are found to occur, and in some cases make up a high proportion of the observed cases. Distinct associations are the result of a constellation of the proper chemical, physical, and biological factors and, for that reason, distinct associations are expected to be uncommon.
Organic carbon export from upland and forested wetland watersheds1
Authors: Mulholland Patrick J. , Kuenzler Edward J.
Published: March 2010

Export of organic carbon per unit runoff from five small, eastern North Carolina watersheds with considerable swamp drainage was severalfold higher than the export rates from upland watersheds reported in the literature. This reflects the higher concentrations of organic carbon, especially dissolved forms, in swamp waters and is probably attributable to increased contact time between water and organic debris as well as to concentration effects of high evapotranspiration in swamps.
Sulfate reduction in a New England salt marsh1
Authors: Howarth Robert W. , Teal John M.
Published: March 2010

Sulfate reduction rates were measured for 2 years in the peat of a salt marsh by a radiotracer technique. Rates are high throughout the peat, from the surface to more than 20 cm deep. The integrated annual rate is about 75 mol SO42−·m−2·yr−1, the highest yet reported for any natural ecosystem. Sulfate reduction accounts for the consumption of 1,800 g org‐C·m−2·yr−1, about equal to net primary production in the marsh. Respiration using other electron acceptors (such as oxygen or nitrate) is much less important. Sulfate reduction rates in the peat of the salt marsh are probably high for at least three reasons: the belowground production of Spartina alterniflora provides a large, annual input of organic substrates over a depth of some 20 cm; sulfate is rapidly resupplied to the peat in infiltrating tidal waters, so that sulfate depletion never limits the rate of reduction; and sulfide concentrations remain below toxic levels. The stable pyrite (FeS2) is a major end product of sulfate reduction in the marsh peat while iron monosulfide (FeS) is not. If the incorporation of 35S into pyrite were not measured, the [35S]SO42− reduction measurements would greatly underestimate the true rate of sulfate reduction. Pyrite acts largely as a temporary store of reduced sulfur, with seasonal changes in its concentration.
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.
Primary production of algae growing on natural and artificial aquatic plants: A study of interactions between epiphytes and their substrate1
Authors: Cattaneo A. , Kalff J.
Published: March 2010

Epiphytes that grew on Potamogeton richardsonii were similar to those Krowing on morphologically similar plastic plants in both biomass (as Chl a) and primary production per unit area, over the growing seasons of 1976 and 1977. Alkaline phosphatase activity, an indicator of P limitation, was always higher for epiphytes on artificial substrates, which suggests that real plants transfer a small amount of nutrient to their epiphytes. However, specific production of the epiphytes (production per unit of Chl) was not significantly different on the two substrates. These similarities give little support to the hypothesized symbiosis or competition between plant and epiphytes. The living plants appear to be a neutral substrate for algal growth.
Light stimulation of phosphate uptake in natural assemblages of phytoplankton
Authors: Reshkin Stephan J. , Knauer George A.
Published: March 2010

The light dependence of phosphate uptake by phytoplankton was investigated in natural assemblages incubated in a flow‐through deck incubator with neutral density screens used to attenuate light to desired levels. The relationship found approximates the Michaelis‐Menten kinetic function commonly used in algal nutrient uptake studies. Light half‐saturation constants, corrected for dark uptake, ranged from 11.3–18.3% of incident light and are comparable in some instances to those found for light‐dependent nitrate and ammonium uptake.
Acidification and other chemical changes Halifax County lakes after 21 years
Authors: Watt W. D. , Scott D. , Ray S.
Published: March 2010

Sixteen of 23 lakes sampled in 1955 show no sign of significant physical alterations within their drainage basins over a 21‐year interval, so that chemical changes in these lakes can be assumed to reflect changes in atmospheric inputs. In all 16, the pH levels have declined, with greater declines in the higher pH (near neutrality) lakes. After correction for sea‐salt input, concentrations of sodium, magnesium, calcium, potassium, and sulfate show no significant change. Sulfate and hydrogen ions are significantly correlated and both show significant regressions on distance from the major sulfur‐emitting industrial sources in the Halifax area. Although the area as a whole may be subject to an influx of acid pollutants via long distance atmospheric transport, for lakes near Halifax the high acid levels are largely due to local pollution.
The relation between pore water chemistry and benthic fluxes of nutrients and manganese in Narragansett Bay, Rhode Island
Authors: McCaffrey Richard J. , Myers Allen C. , Davey Earl , Morrison George , Bender Michael , Luedtke Nile , Cullen Douglas , Froelich Philip , Klinkhammer Gary
Published: March 2010

Benthic fluxes of dissolved nutrients and manganese from biologically disturbed, relatively unpolluted sediment in Narragansett Bay, Rhode Island, have been measured. Analyses of the vertical gradients of chemical species dissolved in pore waters and the uptake of 22Na from the overlying water permits evaluation of the contribution of biological advection and molecular diffusion to the transport of dissolved materials across the sediment‐water interface. The activity of bottom‐dwelling organisms appears to be about as important as molecular diffusion in most cases. The sum of the independently estimated contributions by both mechanisms is in good agreement with integrated benthic fluxes measured in situ. Sulfate and oxygen oxidize comparable amounts of organic matter in these sediments.
Planktonic blue‐green algae: Production, sedimentation, and decomposition in Lake Mendota, Wisconsin
Authors: Fallon Robert D. , Brock Thomas D.
Published: March 2010

During two annual phytoplankton cycles (1976, 1977), growth, primary production, and sedimentation were measured in Lake Mendota. Blue‐green algal blooms developed after lake stratification in a succession of dominant genera. Aphanizomenon and Anabaena normally dominated early populations with Microcystis becoming more important by midsummer. Periodic declines in blue‐green algal standing crop could be accounted for by a combination of epilimnetic decomposition and sedimentation. For Aphanizomenon and Anabaena, decomposition appeared to be primarily important, whereas sedimentation accounted for more of the decline of Microcystis. Estimates for annual sediment accumulation obtained by correcting the observed sedimentation rates for resuspension agreed fairly well with values calculated from coring data. For the period of blue‐green algal dominance, about 57–67% of the organic carbon was lost from particles during sedimentation due to decomposition. Further decomposition occurred at the sediment surface so that only about 11% of the original organic material was more or less permanently buried. Amounts of blue‐green algal volume, particulate chlorophyll, and particulate phosphorus measured in the traps also indicated that significant decomposition had occurred during sedimentation.
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.
Determination of the solubility of ferrous sulfide in a seasonally anoxic marine basin
Authors: Davison W. , Heaney S. I.
Published: March 2010

Iron(II) and sulfide data are presented for a seasonally anoxic marine basin. An operational solubility product, pKnbssp = aFe2+ · ahs‐/(H+)* = 2.76–3.04, is calculated and found to be consistent with values for seasonally anoxic freshwater systems and with the laboratory values for amorphous ferrous sulfide. These results show that the solubility is not affected by ionic strength and that in such dynamic systems no appreciable aging of the solid phase is apparent.
The effect of environmental origin on the response of marine diatoms to chemical stress1
Authors: Murphy Lynda S. , Belastock Rebecca A.
Published: March 2010

Seventeen clones of the marine diatoms Thalassiosira pseudonana and Skeletonema costatum show a wide range of sensitivity to the chemical stress of an industrial waste. Eight clones are of oceanic origin and nine are neritic. Of the neritic clones, three are from heavily polluted estuaries and six from relatively unpolluted waters. There were no correlations with latitude or distance from shore in the oceanic clones nor with temperature regime or salinity in the neritic ones. The three clones from heavily polluted waters were much less sensitive to the waste than were the other neritic clones, which came from relatively clean water. These were slightly less sensitive than were the oceanic clones, but there was considerable overlap in the responses of these two groups. For these 17 clones, a recent history of environmental pollution had at least as much influence on clonal sensitivity to chemical stress as did the long term stability, or lack of it, of the environment from which they were first isolated.
Radioactively labeling of natural assemblages of bacterioplankton for use in trophic studies1
Authors: Hollibaugh J. T. , Fuhrman J. A. , Azam F.
Published: March 2010

Natural assemblages of marine bacteria are labeled with [3H]thymidine, most of which is incorporated into the bacterial DNA. The method circumvents the problem of loss of label during short term feeding experiments. Highly labeled assemblages of bacteria thus obtained allow the measurement of grazing by microzooplankton with clearance rates as low as 1 µl · individual−1 · d−1.
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.
Benthic and atmospheric contributions to the nutrient budgets of a soft‐water lake1
Authors: Kortmann Robert W.
Published: March 2010

Steady state, in situ incubation, and empirical phosphorus models were used to quantify the fluxes of nutrient and redox active materials in Dunham Pond. Benthic flux contributions were about 16 and 45% of the annual silica and ammonia budgets. Labile dissolved organic nitrogen is used by the lake system while refractory dissolved organic nitrogen is being produced. The phosphorus retention estimate based on aerial water loading predicted spring phosphorus concentration and loading more accurately than that based on the phosphorus budget. Atmospheric contributions of phosphorus and dissolved nitrogen account for 25 and 10% of the respective annual budgets.
Photosynthesis and coccolith formation: Inorganic carbon sources and net inorganic reaction of deposition1
Authors: Sikes C. Steven , Roer Robert D. , Wilbur Karl M.
Published: March 2010

The concept that the formation of CaCO3 coccoliths functions as a photosynthetic adaptation for the use of bicarbonate is evaluated in the coccolithophorids Coccolithus huxleyi and Cricosphaera carterae by two new methods. In the first, carbon fixation is measured at 10‐s intervals in the first 2 min after addition of 14CO2 and H14CO3− to buffered cultures; this method exploits the relatively long half‐time for the hydration or dehydration of dissolved CO2. In the second, shifts in pH and alkalinity resulting from carbon fixation by cells growing in liquid culture are assessed to indicate fluxes of CO2 and HCO3− into cells and these values compared to measurements of 14C incorporation in photosynthesis and carbonate deposition. The data are interpreted in terms of one of several net inorganic reactions of deposition considered. In this reaction, CO2 is the substrate of photosynthesis and HCO3− is the form of carbon supplied to the calcification site. CO2 resulting from carbonate deposition supplements the CO2 from the medium that diffuses into cells as a source of carbon for photosynthesis.
Extracellular release of carbon by marine phytoplankton; a physiological approach1
Authors: Mague T. H. , Friberg E. , Hughes D. J. , Morris I.
Published: March 2010

The production of soluble, 14C‐labeled organic material from H14CO3− by cultures and natural populations of marine phytoplankton has been examined with particular attention to experimental technique. Extracellular release is a normal function of healthy cells, is closely related to photosynthetic rate, and is a minor component (up to 5 µg C · liter−1 h−1) of total primary productivity in coastal waters. Time‐course studies and chemical cell‐fractionations indicate that newly synthesized organic 14C is distributed among various cell polymers and the extracellular medium from a rapidly labeled, soluble intracellular pool of small molecules. The rate of supply of carbon to this pool may determine the relative rate of release. Extracellular 14C appearing during transient light shock may preferentially arise from rapidly mobilized polysaccharide and is not simply the result of cell lysis.
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.
RNA concentration of zooplankton: Relationship with size and growth1
Authors: Bdmstedt Ulf , Skjoldal Hein Rune
Published: March 2010

The relationship between RNA concentration and dry weight (W) of zooplankton from the Korsfjord, western Norway, was best described by a power function, [RNA] = aWb. Dry weight explained about 75% of the intraspecific and 43% of the interspecific variation in RNA concentration. The intraspecific regression slope (average −0.74) was significantly steeper than the multispecific slope (−0.33). Published data on growth rate of zooplankton from Korsfjorden and other areas revealed a pattern with dry weight similar to that for RNA concentration, with an interspecific regression slope of −0.32. Combining the interspecific regressions of growth rate and RNA concentration vs. dry weight gives a relationship between growth rate (k, coefficient of daily exponential growth) and RNA concentration (µg·mg dry wt−1), k ·103 = 0.795 × [RNA], which can be used to estimate the average growth rate of macrozooplankton samples with RNA concentrations between 3 and 70 µg·mg dry wt−1.
Effect of nitrogen source and growth rate on phytoplankton‐mediated changes in alkalinity1
Authors: Goldman Joel C. , Brewer Peter G.
Published: March 2010

Continuous cultures of the marine chrysophyte Dunaliella tertiolecta were grown on four nitrogen sources: NO3 NO2−, NH4+, and urea. Alkalinity changes were consistent with a simple stoichiometric model in which OH production is balanced by NO3− and NO2− uptake, H+ production is balanced by NH4+ uptake and no change occurs when the uncharged species urea is assimilated. Neither the influent N concentration nor the growth rate had any effect on the 1:1 stoichiometry between N uptake and alkalinity change. These results preclude the possibility of excretion of an organic acid (e.g. glycolic acid) stronger than carbonic acid. However, excretion of a weak organic acid or a salt of a strong organic acid cannot be ruled out. In general, the results are consistent with the notion that excretion of glycolic acid by healthy marine phytoplankton cells is minimal.
Results of a primary productivity study as affected by the type of glass in the culture bottles1
Authors: Worrest Robert C. , Brooker Deborah L. , Van Dyke Henry
Published: March 2010

Radiocarbon uptake by Thalassiosira pseudonana was used to compare the effect of bottle type on primary productivity. Three types used in primary productivity studies were considered: standard soda‐lime bottles, commercial Pyrex bottles, and quartz bottles. Transmittance within the ultraviolet region (e.g. 290–320 nm) varied significantly (quartz > Pyrex > Wheaton “800” glass). Measurements of radiocarbon uptake in the three bottle types under white fluorescent lamps alone (4.48 W·m−2 [380–700 nml) were not significantly different. However, when combined with the sunlamp/filter system (0.74 W m−2 [290–320 nm]), there was a significant difference in productivity. The environmentally significant ultraviolet portion of the solar spectrum should be considered when culture bottles are selected for in situ primary productivity studies.
On the determination of Ca2+ ion concentration in seawater
Authors: Krumgalz Boris S. , Holzer Rella
Published: March 2010

A calcium‐sensitive electrode is used to detect the end point in determining calcium in seawater by complexometric titration with EGTA. The values of calcium concentration of standard seawater thus determined agree well with published data. The method is applied to a study of the calcium distributiun of a station in the Mediterranean Sea at various depths.
Stratification of aerobic methane‐oxidizing organisms in Lake Mendota, Madison, Wisconsin1
Authors: Harrits Susan M. , Hanson Richard S.
Published: March 2010

The microflora responsible for methane oxidation are stratified in a narrow band in the thermocline of Lake Mendota where dissolved oxygen is low during summer. Oxygen sensitivity of growth of these organisms or of methane oxidation cannot account for their absence from the epilimnion because oxygen does not inhibit either process under in situ conditions at concentrations exceeding those measured in natural samples. The dissolved inorganic nitrogen content of samples where methane oxidation rates were highest was >1 mg·liter−1 in summer 1977. We could not obtain evidence of in situ nitrogen fixation although enrichment cultures grew on nitrogen‐free media and fixed 15N2. Nitrite was present at the position in the water column of maximum methane oxidation; this suggests that methanotrophic bacteria co‐oxidized ammonia. The distribution of methanotrophs in the lake indicated that their position in the water column at each time of year was determined by the concentration profiles of oxygen and methane. Methane oxidation in summer depletes the methane in the epilimnion and the absence of oxygen in the hypolimnion precludes growth of the organisms there. At other times of year the rates of oxidation of methane seem to be determined by the concentration of methane in the water. The rate of oxidation of methane by a sample was increased by additional methane when the in situ concentration was <5 µM.
Ingestion rate decrease as the stimulus for sexuality in populations of Moina macrocopa1
Authors: D'Abramo Louis R.
Published: March 2010

The stimulus for the switch from asexual to sexual reproduction in populations of Moina macrocopa americana is an abrupt decrease in ingestion rate caused by a rapid reduction in the amount of available food. When nearly constant ingestion rates are maintained, through the addition of either nutritive or nonnutritive particles, asexual females do not produce any male or sexual female progeny. The stimulus seems to be physical in nature. Sexuality in the Cladocera can be attributed to a variety of environmental variables, all of which can significantly reduce ingestion rates.
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.
Silicon content of five marine plankton diatom species measured with a rapid filter method1
Authors: Paasche E.
Published: March 2010

The silicon content of five species of marine planktonic diatoms grown in laboratory culture was measured by a method involving soda hydrolysis of cells collected on polycarbonate filters. An increase in the temperature or light intensity during growth resulted in an increase in the Si content in some species and a decrease in others. The magnitude of these changes depended on whether the results were expressed as pg Si·cell−1, pg Si·µm−2 cell surface area, or pg Si per pg C.
The annual cycle of plankton diatom growth and silica production in the inner Oslofjord1
Authors: E. Paasche , I. Ostergren
Published: March 2010

Concentrations of amorphous particulate silica (biogenic silica) in the uppermost layer of the inner Oslofjord, Norway, varied between 2 and 324 µg Si·liter−1 over a 1‐year period in 1977–1978. Most of the silica was present in frustules of living or dead diatoms but there was always a certain amount (up to about 50 µg Si·liter−1) in a form that could not be recognized under the microscope. Silica was produced mainly during three large blooms of Skeletonema costatum in February–March, May, and June. At the peak of the June bloom, there was up to 20 times more Si present as diatom silica than as dissolved orthosilicic acid. Uptake experiments in June indicated depletion times of dissolved Si as short as 3 h. Although the S. costatum cells were less heavily silicified in May and June than in February–March, they showed no morphological signs of a drastic Si shortage.
Characterization of organic nitrogen in natural waters: Its molecular size, protein content, and interactions with heavy metals
Authors: Tuschall J. R. , Brezonik P. L.
Published: March 2010

The nitrogenous organic matter from two freshwater lakes and from the filtrate of a unialgal culture of Anabaena sp. was characterized chemically and evaluated for metal complexation ability. Proteinaceous matter was isolated from acidified samples by cellulose cation exchange columns and eluted with a basic salt solution. Isolated proteinaceous matter accounted for 14–34% of the original dissolved organic nitrogen. Gel permeation chromatography and ultrafiltration methods used to separate dissolved organic nitrogen into various size fractions yielded differing results, but most of the organic nitrogen had apparent molecular weights between 10,000 and 50,000 daltons. The copper‐complexing capacity of the proteinaceous matter was determined by differential pulse anodic stripping voltammetry. Conditional stability constants, which represent the mixed stability of all nonlabile ligands in the sample, ranged from 1.6 × 106 to 1.3 × 107 for the three samples.
The effects of transect direction on observed spatial patterns of chlorophyll in Lake Tahoe1
Authors: Abbott Mark R. , Powell Thomas M. , Richerson Peter J.
Published: March 2010

Horizontal transects of fluorescence measurements have been used extensively to investigate phytoplankton patchiness. Variance spectra have been calculated from these data, thus quantifying spatial heterogeneity as a function of length scale. Analysis of such fieldwork and associated theoretical investigations is based on the assumption that horizontal patchiness is isotropic. Three transects done in Lake Tahoe (California‐Nevada) in different directions on the same day resulted in variance spectra that were significantly different from each other. The possibility of windrows appears consistent with the spectra. Although the exact cause of the differences is unclear, the results do violate the assumption of isotropic horizontal phytoplankton patterns.
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.
Grazing patterns of copepods in the upwelling system off Peru
Authors: Boyd Carl M. , Smith Sharon L. , Cowles Timothy J.
Published: March 2010

The amount of food eaten by copepods of three genera (estimated from chlorophyll and pheophytin in the guts of the animals) was measured to determine the depth and also the time of day of the maximum and minimum intensity of feeding. Copepods were taken with a large volume (800 liters min−1) pumping system at five depths (0–85 m) and twelve sampling intervals (every 4 h) at three stations in the Peruvian upwelling system. Results indicate that Eucalanus could withstand periods of 12 h in anoxic layers, but Calanus and Centropages tended to be found in waters having more than 0.8 and 0.2 ml O2·liter−1, that in situ filtration rates could be derived which were in accord with filtration rates obtained from laboratory studies, that individuals of the three genera migrated in and out of the 5‐m surface layer when food was abundant but did not show a coherent diurnal vertical migration when food was scarce, and that the three genera maintained different feeding strategies which were amplified when food was scarce. The results are consistent with the concepts of resource allocation and separation of niches by species.
Natural feeding rates of Centropages typicus females in the New York Bight1
Authors: Dagg M. J. , Grill D. W.
Published: March 2010

Based on measurements of the removal rate of small particles from natural seawater, the ingestion rate of adult females of the copepod Centropages typicus is almost always less than maximal. A survey of particle concentrations in the New York Bight indicated that the concentrations used in our feeding experiments were representative of concentrations encountered by this species. In addition to the particle removal method, a gut fluorescence method was used to calculate natural ingestion rates of phytoplankton particles. Comparable rates resulted from both methods. We believe that for this organism, ingestion rates are closely related to food quality because the range of natural food concentrations is rather narrow.
Population structure and in situ division rates of Ceratium in oligotrophic waters of the North Pacific central gyre1
Authors: Weiler C. S.
Published: March 2010

Species composition and division rates were examined for a population of the dinoflagellate genus Ceratium from oligotrophic waters of the North Pacific central gyre. Division rates of Ceratium were high relative to those in other oceanic regions despite the low nutrient levels. Doubling times were calculated to be 5.2–7.5 days for the genus and ranged from 4.0 to 9.2 days among the 10 most abundant species. Fifty‐one species of Ceratium were identified, and their rank order of abundance was remarkably constant over the largest temporal and spatial scales examined (9 months and 755 km). Ceratium's relatively high division rate coupled with its consistently low abundance supports the conclusion from other data that steady state conditions are approximated in this environment.
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.
Organic particle and aggregate formation resulting from the dissolution of bubbles in seawater1
Authors: Johnson Bruce D. , Cooke Robert C.
Published: March 2010

Small bubbles when dissolved in filtered and unfiltered seawater produce minute particles that can remain dispersed or aggregate to form larger particles. The formation of each type of particle has been recorded photographically, and the relationship between initial bubble radius and particle size is presented.
On the diel variation of copepod pigmentation
Authors: Hairston Nelson G.
Published: March 2010

Diel studies of copepods in four Rhode Island ponds failed to show any cyclic variation in pigmentation. Three of four cases of apparent cycles reported by other investigators are not statistically verifiable.
Phosphate interference in the cadmium reduction analysis of nitrate1
Authors: Olson Robert J.
Published: March 2010

Phosphate at 2.5 µM may decrease the Cd‐Cu reduction of NO3− by 10% and at 25 µM by 40%. This interference is gradual and reversible, depends on the age of the reductors and reagents, and is difficult to correct for.
Sampling sea surface films: A laboratory evaluation of techniques and collecting materials1
Authors: Van Vleet Edward S. , Williams Peter M.
Published: March 2010

Fourteen techniques for sampling the sea surface microlayer were compared for their collection efficiencies and the degree to which they may preferentially adsorb lipid, protein, and carbohydrate material in the films collected. 3H:14C ratios in doubly labeled surface films generated in the laboratory show that widely disparate results for the chemical nature of in situ films can be obtained depending on the collection device and its compositional material. Stainless steel and Nitex screens exhibit a strong preferential adsorption of lipid material which can only be removed by rinsing in solvent. Filters yield a more representative sample than screens and are better sampling devices when small quantities of film material are needed. Collection efficiencies of slides and prisms are much lower than those of screens or filters.
A note on the Hynes method1 of estimating secondary production
Authors: Menzie Charles A.
Published: March 2010

A two‐stage method is proposed for estimating production by the Hynes method. The approach involves first estimating the total number of individuals that developed into each size category and then calculating the losses in numbers between size categories and estimating production as the sum of biomass lost between successive size categories. The method avoids use of the average cohort concept which has led to some confusion with regard to the Hynes method.
Temperature structure and water chemistry of the caldera Lake Öskjuvatn, Iceland1
Authors: Ólafsson Jón
Published: March 2010

The caldera Lake Öskjuvatn, 217 m in depth, developed after an eruption in 1875. From 1921 to 1926 volcanic eruptions also affected the lake. Deuterium measurements indicate meteoric origin of the water and 6.3% evaporation from the lake. The lake is cold but temperature measurements at one location revealed strong thermal activity at 80‐m depth; in the deepest part of the lake an inverse temperature gradient and static instability were observed, which suggests convective mixing. The concentration of dissolved solids is high and the distribution of major components uniform. High concentrations of silica (110 mg·liter−1) and major cations (Na, Ca, K) are indicative of reactions with hot lavas that have flowed into and built up in the lake. A low chloride: sulfate ratio, 0.05 by weight, reflects the relative abundance of sulfur and chlorine in the emanations of the volcano. Dissolved oxygen, pH, manganese, and zinc show variations with depth which may be explained as resulting from emanations of H2S and CO2 from the lake bottom and hydrothermal leaching. Limited biological observations suggest a strongly oligotrophic condition and sparse phyto‐ and zooplankton.
Pathways of carbon assimilation in phytoplankton from the Antarctic Ocean1
Authors: Smith A. E. , Morris I.
Published: March 2010

The assimilation of [14C]bicarbonate into the major end‐products of photosynthesis was measured at five stations in the Southern Ocean. Under conditions of low light intensity and low temperature (<0°C) phytoplankton incorporated as much as 80% of the fixed carbon into lipid, with insigificant incorporation into protein. At higher temperatures (>0°C) and higher light intensities incorporation into lipid accounted for <20% of the fixed carbon, the synthesis of polysaccharide and (to a lesser extent) protein being more prominent. Populations showing high rates of incorporation of 14C into lipid have high PC:Chl ratios, high PC:PN ratios, and low C‐specific rates of 14C assimilation. All populations were dominated by diatoms. High concentrations of nitrate, phosphate, and silicate argue against the concept of nutrient limitation. This pattern of photosynthesis differs from that observed in many other parts of the oceans. It is suggested that the prominent synthesis of lipid is a response to extremely low temperatures and is enhanced by the additional stress of low light intensities.