bluuebunny/crossref_metadata_2025 huggingface dataset:
A detailed vertical profile of sterols in the Sargasso Sea1,2
Authors: Gagosian Robert B.
Published: March 2010

Detailed vertical profiles from the Sargasso Sea show that several sterols, e.g. brassicasterol, appear to be produced and consumed in the upper 1,000 m of the water column. A few, e.g. cholesterol, were found in the entire 4,500‐m water column and may represent more resistant organic compounds.

Several mechanisms may introduce sterols into the deep sea. Vertical fluxes of organic particles from the surface appear to control delivery of sterols to the middepth waters of the Sargasso Sea, However, some other process, e.g. physical transport (viz horizontal advection and diffusion), resuspension of sediments, or in situ deep water biological production and consumption controls deep water sterol distribution. Detailed profiles of ancillary data (e.g. POC, total particulate matter, and hydrography) must complement detailed profiles of specific organic compounds to identify the transport mechanisms to the deep sea.
Aliphatic hydrocarbons in sediments of Lake Washington1
Authors: Wakeham Stuart G. , Carpenter Roy
Published: March 2010

The distribution of aliphatic hydrocarbons in sediments from several locations in Lake Washington have been determined by gas chromatographic, radiocarbon, and stable carbon isotope analyses. Most surface sediments contain an average of about 1,400 µg g‒1 dry wt total aliphatic hydrocarbons, of which about 10 µg g‒1 are n‐paraffins. Gas chromatograms of these hydrocarbons and radiocarbon ages of about 18,000 years B.P. for the aliphatic hydrocarbon fraction suggest the presence of a large component of petroleum hydrocarbons. By contrast, sediments at depth in the sediment column and deposited before about 1880 contain only about 30 µg g‒1 total aliphatics and about 5 µg g‒1 n‐paraffins. These hydrocarbon levels are believed to represent the aged natural background concentrations in Lake Washington. A number of cores analyzed in detail show an increase in hydrocarbon levels after 1880, which corresponds to the start of a period of growth for the adjacent metropolitan area.
The relation of energy and organic carbon in aquatic invertebrates1
Authors: Salonen Kalevi , Sarvala Jouko , Hakala Ilpo , Viljanen Maija‐Liisa
Published: March 2010

The physical and nutritional energy values of aquatic invertebrates were studied in relation to organic carbon content. The ratio of energy content to the weight of organic carbon increased with increasing carbon. The dependence is described in regression equations which permit prediction of the energy content with an accuracy of about ±5% (P > 0.95). Even the use of the mean conversion factor of 46 kJ g‒1 organic carbon yields considerably more accurate results than the use of a general conversion factor for ash‐free dry weight.
An inexpensive thermistor flowmeter for aquatic biology1
Authors: LaBarbera Michael , Vogel Steven
Published: March 2010

A new thermistor flowmeter can measure current speeds from 0.2 to 50 cm s‒1 with a spatial resolution of 0.1 cm and a response time of 200 ms. The output of the meter approximates a logarithmic function of the ambient water velocity. The flowmeter itself has a low power consumption and the output can be stored on magnetic tape using a battery‐powered cassette recorder, making possible a continuously recording portable or self‐contained underwater unit.
Significance of predator influence on composition of Bosmina spp. populations1
Authors: Stenson Jan A. E.
Published: March 2010

Comparisons between Bosmina coregoni and Bosmina longirostris in fish stomachs and net plankton showed a larger mean size in the stomachs and a clear preference for the larger species, B. coregoni. Vertebrate and invertebrate predators may influence distribution and numeric relations between the two species.
A model of plankton patchiness
Authors: Riley Gordon A.
Published: March 2010

A model is proposed suggesting how the interaction of diel migration with tides and residual drift can lead to cyclical variations in the rate of drift of zooplankton. This in turn varies the length of time that a so‐called “mesoscale” patch of zooplankton will be associated with any given parcel of surface phytoplankton, and resulting differences in grazing pressure can produce phytoplankton patchiness. The latter may then stimulate the development of patchiness in zooplankton, producing the well known inverse relation between the two populations.
Morphometric changes in Asterionella formosa colonies under phosphate and silicate limitation1
Authors: Tilman David , Kilham Susan Soltau , Kilham Peter
Published: March 2010

Steady state ponulations of Asterionella formosa show a marked dependence of the number of cells per colony on growth rate under both phosphate and silicate limitation. At high steady state growth rates the cells per colony average 8. Under phosphate limitation, the number of cells per colony decreases with decreasing steady state growth rate in a linear manner to less than 2 cells colony−1 at very low growth rates. Under silicate limitation, the number of cells per colony increases with decreasing steady state growth rate in an approximately exponential manner to over 20 cells colony−1 at very low growth rates.
Particulate transport of radionuclides 14C and 55Fe to deep waters in the Pacific Ocean
Authors: Lai D. , Somayajulu B. L. K.
Published: March 2010

Observations during 1969–1971 indicate that radionuclides 14C and 55Fe in particulates in Pacific Ocean waters 28–31° N, 119–121° W up to depths of 2,500 m were transported from the surface within a short time (<10 yr). The mean downward sinking rates for 55Fe 14C are deduced to be 0.5 ✕ 10−3 and 2.5 ✕ 10−3 cm s−1. The appreciably faster transport of 14C is consistent with the fact that the mean size calculated for biogenic calcareous particles transporting 14C is larger than that for the 55Fe‐labeled particles.
Light and dark uptake of nitrate and ammonium by large oceanic dinoflagellates: Pyrocystis noctiluca, Pyrocystis fusiformis, and Dissodinium lunula1
Authors: Bhovichitra Mahn , Swift Elijah
Published: March 2010

In 4‐h experiments, N‐depleted cells of Pyrocystis and Dissodinium species took up NO3− and NH4+ at almost equal rates both day and night when preconditioned on 12 : 12 LD cycle at light intensities sufficient to saturate division (42–67 µEin m−2 s−1).Pyrocystis fusiformis but not Pyrocystis noctiluca took up NO3 at a high rate when grown at 3 µEin m−2 s−1. There was no increase in the concentration of NH4+ within the large vacuoles of Pyrocystis cells during uptake of NH4+, but both NO3 and NH4+ were accumulated in the vacuole when external NO3− was supplied. In contrast, inorganic N did not accumulate in Dissodinium lunula cells during either NO3− or NH4+ uptake. Nutrient‐replete cells of P. noctiluca, P. fusiformis, and D. lunula stored in their vacuoles as inorganic N ca. 30, 5, and 2% of their cellular‐N requirements.
Transport of diatom frustules by copepod fecal pellets to the sediments of Lake Michigan1
Authors: Ferrante J. G. , Parker J. I.
Published: March 2010

Zooplankton fecal pellets expelled near the surface of lakes provide a mechanism for removal of diatoms to deeper water. Scanning electron micrographs show that copepod fecal pellets, collected from Lake Michigan, contained fractured specimens of 21 species of diatoms. Few intact diatoms were observed and many frustules were reduced to small fragments during ingestion by the copepods. The peritrophic membrane surrounding the pellets is composed of polysaccharides, one of which is chitin. This membrane is broken down by bacterial decomposition in 6–14 days as the pellets settle at an average velocity of 4.7 m d−1. As a result, pellets released near the surface in water more than 70 m deep do not transport diatom fragments directly to the sediment. In a large proportion of Lake Michigan the transport of diatoms to the sediments via pellets originating near the surface is unlikely, since about 60% of the lake is >70 m deep.
Some effects of patchy food environments on copepods1
Authors: Dagg Michael
Published: March 2010

Laboratory determinations of the time taken for copepods to starve to death and of the effects of discontinuous food availability on egg production are used to demonstrate that different species are adapted to different scales of patchiness in their food environment. Acartia tonsa and Centropages typicus depend on constant food availability and are therefore sensitive to small scales of patchiness whereas Pseudocalanus minutus and Calanus finmarchicus can physiologically remove themselves from such small‐scale variability. The success of these organisms in the natural environment may be related to the length of time that layers of food exist in the water column.
The importance of light in the initiation of the 1972‐1973 winter‐spring diatom bloom in Narragansett Bay1
Authors: Hitchcock Gary L. , Smayda Theodore J.
Published: March 2010

In 1972–1973 the winter–spring phytoplankton maximum in Narragansett Bay was delayed until late February; it usually occurs in December. Incident light intensity levels relative to the 15‐year mean were unusually low until mid‐January and increased thereafter through February. Inception of the bloom in mid‐January occurred shortly after the estimated in situ intensity of 40 ly d−1 was attained—the critical intensity suggested by Riley required to initiate the spring bloom in temperate coastal waters. Low incident and in situ light intensity, rather than temperature or, as in previous years, a relaxation of grazing pressure, appeared to cause the unusually late bloom inception during 1972–1973.
Bioassay of lower Narragansett Bay waters during the 1972‐1973 winter‐spring bloom using the diatom Skeletonema costatum1
Authors: Hitchcock Gary L. , Smayda Theodore J.
Published: March 2010

Samples collected biweekly from lower Narragansett Bay from December 1972 through March 1973 were bioassayed with Skeletonema costatum at nine different enrichments with nutrients equivalent to f/25‐Tris medium. In early December growth rates were low in all treatments relative to complete enrichment; thereafter there was no evidence of nutrient limitation until late February. During this period of the winter–spring bloom growth was limited by the omission of NO3, SiO3, and PO4; deletion of vitamins and trace metals was less important. The addition of EDTA alone increasingly suppressed growth as the bloom developed; lysis was observed during late March.
Observations on Pyrodinium bahamense Plate, a toxic dinoflagellate, in Papua New Guinea
Authors: Maclean J. L.
Published: March 2010

Pyrodinium bahamense, a dinoflagellate causing paralytic shellfish poisoning, is widely distributed through Papua New Guinea waters. Some similarities and differences in behavior of the species in Papua New Guinea and other oceans are noted.
Further transition states of the Baja California upwelling ecosystem1,2
Authors: Walsh John J. , Whitledge Terry E. , Kelley James C. , Huntsman Susan A. , Pillsbury R. Dale
Published: March 2010

Measurements were made of wind, surface circulation, hydrography, nutrients, and phytoplankton and zooplankton rate processes in a time series at 27°N during April 1973. A string of current meters and a towed acoustic body were also used to assess the distribution of subsurface currents and red crabs. The seasonal onset of upwelling had already occurred. Diatoms were initially the dominant primary producers. Two perturbations of the upwelling state were observed in response to relaxation of the winds. A comparison of this study with a preceding one in March 1972 indicates that the rate of upwelling, the nutrient content, and the phytoplankton specific growth rate were about the same in both years. The total productivity and biomass of the phytoplankton were less in 1973, implying that greater grazing stress was associated with a switch from smaller dinoflagellates to larger diatoms. Local temporal variability of upwelling off Baja California is postulated to have led to the replacement of clupeids by the red crab, Pleuroncodes planipes, as a facultative herbivore.
Effects of polymeric charge variations on the proton‐metal ion equilibria of humic materials
Authors: Wilson Donald E. , Kinney Patrick
Published: March 2010

Except for specific molecular weights, humic materials have many of the chemical and physical characteristics of enzymes. Thus modified equations from the biochemical literature can provide a theoretical description of proton‐metal ion interactions on humic substances. For a given ionizable group type, the members of the group are chemically identical within experimental error, and the observed variations in dissociation of humic acid and bonding strength of metal ion as a function of pH are quantitatively related to the electrostatic interaction between the cationic species and the negatively charged humic polyion. This approach allows experimental determination of intrinsic constants for dissociation of acid and formation of metal ion, i.e. equilibrium constants which are independent of all electrostatic effects. The intrinsic constants obtained for a few humic materials are compared to those of possible monomeric units. In addition, the intrinsic constants have been coupled with other experimental parameters to predict the concentration of metal ion bound to humic materials as a function of pH.
Solubility behavior of apatites in seawater1
Authors: Atlas E. , Pytkowicz R. M.
Published: March 2010

The solubilities of apatites of varying compositions were measured as a function of pH in seawater at 10° and 25°C. Wide ranges of solubilities were observed; at pH = 7.4 they ranged from 0.4 to 11 µM PO4‐P liter−1, depending on the nature of the samples. Results are interpreted in terms of complex coatings formed on the surface of the apatites.
Comparison of lake phytoplankton models and loading plots1
Authors: Thomann Robert V.
Published: March 2010

The log‐log plot of areal nutrient loading rates and depth of lakes is derived from dynamic phytoplankton model equations. When phytoplankton biomass is the relevant variable, it is not possible to predict biomass directly from the plots. The intercept of such plots is a complex interaction of biomass, detention time, total phosphorus, and sinking rate. Only under an assumption of constant ratio between biomass and total nutrient can the biomass be extracted from the intercept. Simplified plots of lake eutrophication should be used for predictive purposes with caution.
Excretion of organic matter by marine phytoplankton: Do healthy cells do it?1
Authors: Sharp Jonathan H.
Published: March 2010

It is widely accepted that marine phytoplankton lose appreciable photoassimilated carbon into seawater as organic compounds; the phenomenon is usually referred to as excretion. Two lines of evidence for excretion are found in the literature: measurements in field studies of “organic 14C” in productivity experiments and the appearance of organic matter in laboratory culture filtrates. Laboratory experiments and a literature review lead to the suggestion that the evidence for excretion is marred by two procedural artifacts, inadequate assessment of control blanks in the 14C field measurements and the results of cultural shock in laboratory studies. Evidence of extensive excretion by phytoplankton is not good.
Changes in carbon, nitrogen, adenosine triphosphate, and chlorophyll a in decomposing Thalassia testudinum leaves
Authors: Knauer George A. , Ayers Allyson V.
Published: March 2010

Fresh Thalassia leaf discs were allowed to decompose for 52 days in a continuous flow system. On a per disc basis, C decreased by 57% over the course of decomposition. N changed only slightly during the first 31 days but dropped to <50% of initial values during the final stages. Changes in ATP content of leaf discs were not linear with time; a rapid initial decrease was followed by a slower loss. C and ATP were significantly correlated in a linear manner throughout the experiment. Total C : N ratios decreased slightly over the first 31 days (avg = 17.0) but tended to increase during days 36–52. In contrast, living C (from ATP) : N ratios tended to decrease throughout the experiment, averaging 4.1 during days 36–52.
Size distribution and activity of marine microheterotrophs1
Authors: Azam F. , Hodson R. E.
Published: March 2010

Natural populations of marine heterotrophic microorganisms in a variety of water masses were size fractionated with Nuclepore filters in a range of pore diameters of 0.1–8 µm. About 90% of the heterotrophic assimilation of 3H‐labeled substrates (d‐glucose, acetate, and l‐serine) was by organisms that pass through 1‐µm filters; essentially all heterotrophic activity was by organisms passing through 5‐µm filters. The 1‐µm filterable fraction contained bacteria and, in some seawater samples, microflagellates. About 90% of the microbial heterotrophic activity in the seawater samples examined was due to those microorganisms (presumably bacteria) that arc unattached to larger particulate material.
Primary production, mineralization, and sedimentation in the euphotic zone of two Swiss lakes
Authors: Bloesch J. , Stadelmann P. , Bührer H.
Published: March 2010

Phosphorus and nitrogen concentrations, phytoplankton, bacteria, detritus, primary production, and sedimentation have been investigated over a year in two Swiss lakes of different trophic state. Inflow and outflow of the lakes were calculated, as well as the eddy diffusion of P and N from the metalimnion into the epilimnion, and from these data a balance of the epilimnetic phosphorus and nitrogen cycle was drawn up. Different methods of calculation all suggested a high intensity of the internal nutrient cycle in the epilimnion. By means of autolysis, destruction, and excretion, about 35–75% of the nitrogen and 55–85% of the phosphorus needed for the measured primary production can thus be regenerated.
Vitamin B12 in Lake Washington, USA: Concentration and rate of uptake1
Authors: Parker Michael
Published: March 2010

The concentration of vitamin B12 in the surface water of Lake Washington was measured by bioassays and the rate of vitamin uptake by adding 57Co‐labeled B12 to samples of surface waters. The concentration of vitamin B12 in the lake water decreased by 60% from late winter to summer, while the rate of uptake increased 16‐fold and turnover time decreased from 50 days to 1 day. The uptake process could be described by the Michaelis‐Menten equation. Regression analyses suggested that the standing crops of blue‐green algae and detritus were most important in affecting the concentration of vitamin B12, but that the standing crops of diatoms and “other” algae affected the rate of uptake most. A hypothesis formulated to explain the necessary coincident variation in rates of vitamin B12 input and output assumes indirect coupling, via detritus, between algal utilization and bacterial production of vitamin B12; it was tested against data from this and other studies.
Solar Lake (Sinai). 1. Physical and chemical limnology1
Authors: Cohen Yehuda , Krumbein Wolfgang E. , Goldberg Moshe , Shilo Moshe
Published: March 2010

In Solar Lake, a basin at the edge of the sea filled with brine and shielded from the wind, a pycnocline builds up in September due to seepage of seawater to the surface. Solar heating produces a mesothermic temperature curve with a maximum up to 60.5°C at 2.5–3‐m depth and decreasing temperatures toward the bottom (40°C at 5 m). The temperature profile together with a supply of nutrients from seepage leads to the development of several bacterial plates and a benthic cyanobacterial bloom. A rapid development of anoxic conditions with up to 39 ppm H2S, a decrease in pH from top to bottom (8–6.9), redox potential gradients (+390 to −185 mV), and extremely pronounced light absorption are observed during the period of stratification which lasts from Sepember to July. With increasing solar energy, the seawater supply no longer compensates for the evaporation rate of 3.0 m yr−1 and the mesothermy becomes unstable. During a short period of holomixis, lasting from 4–13 weeks, the temperature is 27°C throughout the water column. The sediments of Solar Lake preserve a record of the last 4,600 years from the conditions of a marine lagoon to the development of the limnological cycle presented here.
Solar Lake (Sinai). 2. Distribution of photosynthetic microorganisms and primary production1
Authors: Cohen Yehuda , Krumbein Wolfgang E. , Shilo Moshe
Published: March 2010

The seasonal and vertical distributions of sulfur photosynthetic bacteria and cyanobacteria in Solar Lake, and their contribution to primary production, are described. During stratification, separate plates of the phototrophic sulfur bacteria Chromatium violescens and Prosthecochloris sp. develop. A bottom cyanobacterial bloom consisting of Oscillatoria spp. and Microcoleus sp. develops H2Sconcentrations up to 39 ppm and under light conditions down to 0.5% of surface light. The occurrence of a cyanobacterial bloom in the hypolimnion is explained by the facultative anoxygenic photosynthesis of Oscillatoria limnetica. Primary production is extremely high during stratification and reaches a maximum of 8,015 mg C m−2 d−1, 91% of which is produced in the metalimnion and hypolimnion. The overall annual production (59.09 g C m−2 yr−1) is low, owing to extremely low primary production in the epilimnion throughout stratification and in the whole column during holomixis. Stagnant conditions in a shallow body of water exposed to high irradiation leads to an inverse productivity profile.
A time‐dependent model of the lake‐averaged, vertical temperature distribution of lakes1,2
Authors: Tucker W. A. , Green A. W.
Published: March 2010

A model for predicting the time‐dependent vertical thermal structure of lakes is presented. Radiative heating with depth, mixing induced by the surface wave field, and turbulent energy exchanges arc included as lake‐averaged processes. The model was designed to be applicable to a wide range of lake sizes. Comparison of predictions with horizontally averaged observations from Lake Ontario during IFYGL and unaveraged (local) observations from Llyn Cwellyn, Wales, show good agreement.
Rhizosolenia mats1
Authors: Harbison G. Richard , Madin Laurence P. , Swanberg Neil R. , Biggs Douglas C. , Hulburt Edward M. , McAlister Vicki L. , McCarthy James J.
Published: March 2010

Two species of diatoms, Rhizosolenia castracanei and Rhizosolenia shrubsolei, coexist by living together in relatively large mats (4 cm diam). The relative proportion of the two species is variable. In the North Atlantic Ocean, Rhizosolenia mats appear to be limited in distribution to the central and southern Sargasso Sea. Mats are probably of little significance in the overall primary productivity of the ocean. Since euphausiids and copepods have been observed clinging to the mats and eating them, the mats may be of ecological significance to certain species of zooplankton.
Hydrolysis of Cu(II)1
Authors: Vuceta Jasenka , Morgan James J.
Published: March 2010

A major difficulty in predictions of the chemical behavior of Cu(II) with respect to complexation, adsorption, and precipitation processes in natural waters is a lack of convincing equilibrium data for the second hydrolysis equilibrium: Cu2+ + 2H2O ⇌ Cu(OH)2(aq) + 2H+, *β2. A choice of the magnitude of the equilibrium constant is proposed on the basis of potentiometric titrations of CuCl2 solutions followed by means of a copper ion‐selective electrode. A value of *β2 of ≃ 10−14 (25°C) is in agreement with the experimental data in dilute solutions (I = 10−3).
Stoichiometric models for nutrient regeneration m anoxic sediments1
Authors: Berner Robert A.
Published: March 2010

The overall C:N:P stoichiometric composition of organic matter undergoing decomposition during sulfate reduction in anoxic sediments cannot be correctly deduced from pore water chemistry unless corrections for differential diffusion and adsorption are made. This paper presents a method for making these corrections, based on steady state diagenetic modeling of pore water data and estimates of diffusion coefficients, adsorption constants, and rates of sedimentation. For a sediment site in Long Island Sound, calculations indicate that ignoring differential diffusion and adsorption results in deduced nitrogen and phosphorus contents in decomposing organic matter which are too low by a factor of 2. Further calculation suggests that the effects of differential adsorption cannot be neglected in most other sediments that undergo appreciable adsorption.
The effect of ambient oxygen concentration on filtering and respiration rates of Daphnia galeata mendotae and Daphnia magna1
Authors: Heisey Dennis , Porter Karen G.
Published: March 2010

The filtering and respiration rates of Daphnia magna and Daphnia galeata mendotae were measured in oxygen concentrations ranging from air saturation to near zero, using animals that had lived in air‐saturated conditions so that facultative hemoglobin synthesis was not initiated. Daphnia magna’s filtering and respiration rates are independent of oxygen concentrations above 3.0 mg liter−1; below this, rates decline rapidly. Daphania galeata mendotae’s filtering and respiration rates exhibit’ a linear dependence on oxygen concentrations. It is suggested that D. magna’s relatively greater tolerance of low oxygen concentrations is due largely to its higher basal levels of hemoglobin. Daphnia may often be oxygen limited in nature.
Observations of small‐scale spatial patterns in phytoplankton populations1
Authors: Harris G. P. , Smith R. E. H.
Published: March 2010

The temporal and spatial distribution of phytoplankton in a shallow eutrophic marsh was studied by means of horizontal and vertical transects. Biological and chemical data showed patchiness on scales from centimeters to meters. Many of the parameters showed correlations between mean square and variance and displayed skewed distributions. Wind speed was correlated with mean horizontal chlorophyll content and the coefficient of variation of chlorophyll in the vertical dimension. Phytoplankton populations were dominated by a single species of Cyclotella. Diversity index calculations showed a small reduction of community diversity at high Cyclotella abundances. The patchiness is explained by the fact that the samples were taken in a mixing zone beween two distinct water masses, one more eutrophic than the other.
In vivo fluorescence determinations of phytoplankton chlorophyll a
Authors: Slovacek Rudolf E. , Hannan Patrick J.
Published: March 2010

The in vivo fluorescence yield of chlorophyll a in Chlorella pyrenoidosa is shown to vary with the availability of nitrate, trace elements, and with the presence of mercury. The fluorescence yield of Phaeodactylum tricornutum also varies with culture conditions and comparisons of Cyclotella nana and Chaetoceros galvestonensis show a species‐dependent variation. Both types of yield fluctuations are eliminated when photosynthetic electron transport is blocked by adding 3‐(3,4dichlorophenyl)‐1,1‐dimethylurea (DCMU) to phytoplankton: the in vivo fluorescence yield becomes maximal and a constant function of cellular chlorophyll a, regardless of growth conditions or of the species examined. Preliminary observations of samples from the Caribbean Sea also indicate a constant in vivo fluorescence yield in the presence of DCMU.
Temperature effects on phytoplankton growth in continuous culture1
Authors: Goldman Joel C.
Published: March 2010

Temperature has a strong influence on the chemical composition of marine phytoplankton. A common characteristic of several species is a minimum nutrient content (as nitrogen or carbon) per cell at the temperature optimum for cell division, with increasing cellular biomass at lower and higher temperatures. Hence, cell division and nutrient uptake rates are uncoupled with respect to temperature. This raises doubts concerning the role of temperature in phytoplankton ecology and the predictive value of existing models of kinetic growth and uptake.
Comparison of techniques for the measurement of zooplankton filtration rates1
Authors: Hargis Jack R.
Published: March 2010

The filtration rate of Acartia clausii Giesbrecht was measured by Coulter counter, fluorometric determinations of chloropyhll a concentrations, and by a carbon‐14 radiotracer method. Two‐way analysis of variance with replication gave no significant differences between these techniques (P > 0.05). The Coulter counter is the technique of choice because it provides additional information on size‐selective grazing and permits direct conversions from cell volume to carbon content.
A method for quantitatively assessing the infaunal community in coral rock1
Authors: Brock Richard E. , Brock Julie H.
Published: March 2010

Acid dissolution with previous Formalin preservation allows virtually total recovery of the infaunal community in coral rock, making quantitative studies possible. Most groups remain readily identifiable following this treatment. Coral rock samples from gradients of sewage and stream stress suggest a decrease in numbers and biomass with distance from the perturbation.
Hydrocarbon budgets for Lake Washington1
Authors: Wakeham Stuart G.
Published: March 2010

Fluxes of hydrocarbons through Lake Washington show that urban stormwater runoff and river runoff are the major sources of petroleum hydrocarbons to the lake. Sedimentation is the primary removal process for these hydrocarbons.
Application of gel filtration chromatography to evaluation of organo‐metallic interactions in natural waters1
Authors: Means Jeffrey L. , Crerar David A. , Amster James L.
Published: March 2010

Gel filtration chromatography (GFC) has been used to isolate metal‐bearing soluble organic fractions from selected river samples and from mildly contaminated groundwaters around a radioactive waste disposal trench. These two independent tests suggest that GFC can be used to quantitatively evaluate organo‐metallic associations in natural waters. In addition to discriminating between total inorganic and organic modes of solution transport, the method can elucidate the role of different molecular weight organic fractions in trace metal mobilization.
Phosphate uptake from phosphomonoesters by phytoplankton in the Chesapeake Bay1
Authors: Taft Jay L. , Loftus Michael E. , Taylor W. Rowland
Published: March 2010

Phosphomonoester concentrations were 0 to 0.09 µg‐atom liter−1 in Chesapeake Bay from December 1972 to December 1973. Alkaline phosphatase activity associated with natural phytoplankton assemblages indicated the cells’ potential to utilize the monoesters as a phosphorus source. However, ecological interpretation of alkaline phosphatase activity data is complicated by the necessity to increase the monoester concentration in order to measure enzyme activity fluorometrically. The half‐saturation constant (K3) was 0.31 for 3‐0‐methyl fluorescein hydrolysis by a natural phytoplankton assemblage and 0.75 µM for glucose‐6‐PO4 by a nanoplankter in culture, and maximum velocities (Vm) were 3.2 and 6.4 nm (µg Chl a h)−1. In one experiment with a natural phytoplankton assemblage, organisms in the 0.8–5‐µm, size range comprised 78% of the plant biomass and were responsible for 70% of the phosphorus uptake from glucose‐6‐PO4 when size fractionation preceded experimental incubations. Phosphomonoesters may contribute to phytoplankton phosphorus nutrition during much of the year, but are in greatest demand in spring in Chesapeake Bay.
Prey detection in the Chaetognatha: Response to a vibrating probe and experimental determination of attack distance in large aquaria1
Authors: Feigenbaum David , Reeve M. R.
Published: March 2010

The benthic Spadella schizoptera and the planktonic Sagitta hispida both attacked a fine vibrating glass probe over a broad range of frequencies after being starved for 1–3 days. The response curve for S. schizoptera had a peak at 30 Hz and was similar in shape but far broader than that found by prior workers for Spadella cephaloptera. Sagitta hispida responded differently, with a peak response at 150 Hz and no apparent preference among lower frequencies. It also had a strong (37%) response to nonvibrating lateral sweeps.

Neither species would attack the probe at a distance >3 mm. This extremely short attack distance was confirmed, for S. hispida, in a 50‐liter aquarium by a series of feeding experiments, the results from which were applied to a simple model. Sagitta hispida starved for 1 day searched 2,667 mm3 min−1 and had an attack distance of 0.88 mm. These experimental data were used to determine the ability of S. hispida to sustain itself nutritionally in its natural environment.
Determination of microbial activity of estuarine detritus by relative rates of lipid biosynthesis1
Authors: White David C. , Bobbie Ronald J. , Morrison Susan J. , Oosterhof Darlene K. , Taylor Cecile W. , Meeter Duane A.
Published: March 2010

Microorganisms colonizing allochthonous detritus (live oak leaves) incubated in a north Florida estuary show metabolic activity that can be assayed reproducibly by the incorporation of [32P]H3PO4 and [1‐14C] sodium acetate into the lipids in a 2‐h period without introducing subculture bias. Relatively uncolonized live oak leaves show only about 1% of the biosynthetic capacity of leaves incubated in the estuary for 1 week. Lipid synthesis is proportional to time for at least 2 h and also to detrital mass. Random sampling from pooled portions of many leaves greatly reduces the variance of activities from individual leaves.

Rates of phospholipid synthesis paralleled the total extractable ATP and the alkaline phosphatase activity during a 6‐week incubation of live oak leaves in Apalachicola Bay. Rates of 14C incorporation into lipids paralleled the respiratory and the α‐d‐mannosidase
Effects of N:P atomic ratios and nitrate limitation on algal growth, cell composition, and nitrate uptake 1
Authors: Rhee G‐Yull
Published: March 2010

Scenedesmus sp. was grown in chemostats at a fixed growth rate (µ) in an inorganic medium with nitrogen to phosphorus atomic ratios (N:P) ranging from 5 to 80, to investigate the effect of double nutrient limitation. There was no additive or multiplicative effect of the two nutrient limitations: below the optimal cell N:P of 30, growth was determined solely by N limitation and above 30, by P limitation. Cell N remained constant up to the optimal ratio and increased linearly with N:P above it. The level of cell P was high at low N:P (N‐limited state) but decreased rapidly until N:P approached the optimal and remained constant at a low level at high N:P (P‐limited state).

Protein was the major fraction in which excess N accumulated under P limitation. Cell free amino acids were a constant proportion of cell N at all N:P ratios. RNA concentration was the same regardless of N:P, its level being determined by µ independent of the type of limiting nutrients. Cell carbon (C) concentration was higher in the P‐limited than in the N‐limited state. The C fixation rate per unit chlorophyll a, however, was constant under both P‐ and N‐limited states because the variation in chlorophyll a content was similar to that of C.

The apparent maximum uptake rate for nitrate (V) in N‐ and P‐limited cultures decreased with increasing cell N or N:P. In N‐limited cultures the half‐saturation constant (Km) also decreased at higher cell N or N:P. The variation of V appeared to be affected by the level of free amino acids.
Kinetics of algal transient phosphate uptake and the cell quota concept 1
Authors: Brown Edward J. , Harris Robin F.
Published: March 2010

Dissolved inorganic orthophosphate (P1) uptake rates (v) were determined as a function of total cell phosphorus content (Q) in P1 perturbed axenic batch cultures of Selenastrum capricornutum and Nostoc sp. The results showed an inverse relationship between v and Q for both organisms. These findings are used to relate the cell quota concept of nutrient limited, steady state microbial growth kinetics to nutrient uptake kinetics observed in perturbed batch cultures.
Continuous culture of marine diatoms under silicon limitation. 3. A model of Si‐limited diatom growth 1
Authors: Davis Curtiss O. , Breitner Norman F. , Harrison Paul J.
Published: March 2010

A biochemically based model for simulating silicon‐limited diatom growth has been developed in which silicic acid uptake is described by Michaelis‐Menten kinetics. Utilization of silicon within the cell is a function of silicon available in internal pools, while growth is a function of silica in the frustule. Uptake is frequently limited by the rate of silicon utilization within the cell. That rate may be set by the enzymes, or more likely one key enzyme, which regulates the process of frustule formation. Alternatively, some other factor such as light or another nutrient may limit growth, and this in turn may limit silicon utilization within the cell and silicic acid uptake.

The model was designed specifically to simulate steady state and transient behavior of a Si‐limited diatom population growing in a chemostat. Comparison of simulations and actual chemostat results indicate that it is a realistic representation of diatom response under these conditions.
Dissolved silica in pore waters of Lakes Ontario, Erie, and Superior sediments
Authors: Nriagu Jerome O.
Published: March 2010

The distribution of dissolved silica in pore waters from Lakes Ontario, Erie, and Superior sediments is not directly related to the deposition of diatomites from the overlying water. It is proposed that silica concentrations in the pore waters are controlled by dissolution of ferroaluminum silicate, Al1−xFe1−x3+(SiO2)x(OH)6(1−x). The cryptocrystalline complex is formed in the sediments by the reaction of biogenic silica with aluminum and ferric oxyhydroxides or by the hydrolysis of clay minerals.

A massive episodic flux of biogenic silica to the sediments follows the crash of diatom blooms. Most of the biogenic silica is however dissolved in the water column or at the sediment‐water interface; a small fraction is fixed permanently in the sediments as the cryptocrystalline complex. Budget calculations show that regeneration of silica from Ontario and Erie sediments far exceeds annual input from external sources.
Mechanisms of hydrogen sulfide release from coastal marine sediments to the atmosphere
Authors: Hansen Marianne Hartmann , Ingvorsen Kjeld , Jøgensen Bo Barker
Published: March 2010

In two shallow, coastal areas in Denmark the rates of H2S release were directly measured by continuously collecting the gas over a known area. Peak emission rates of up to 0.30 and 6.7 mmol H2S m−2 h−1 were found with a diurnal average of 0.063 and 1.58 mmol H2S M−2 h−1. The release mainly takes place at night since photosynthetic microorganisms efficiently oxidize the sulfide during the day. Only traces of H2S escape through a stagnant layer of oxic water 10 cm deep. The rate of H2S release is compared to the diurnal changes in light, temperature, Eh, pH, O2, and H2S at the sediment surface and with the rate of sulfate reduction within the sediment.
Natural radon and phosphorus as limnologic tracers: Horizontal and vertical eddy diffusion in Greifensee
Authors: Imboden D. M. , Emerson S.
Published: March 2010

Two‐dimensional interpretation of monthly measurements of natural radon‐222 at different stations in Greifensee, Switzerland, results in hypolimnetic vertical and horizontal eddy diffusion coefficients (Kz and Kx) of 0.2–0.05 and 1,000–100 cm2 s−1 during the stagnation period in 1975. Application of the one‐dimensional and three‐dimensional horizontally well mixed models to the data from the midlake station produces errors of about a factor of two in the vertical eddy diffusion coefficient. With the hypolimnion mixing information, Kz in the thermocline is estimated to be 0.025 ± 0.015 cm2 s−1 by using dissolved phosphorus as a quasi‐conservative tracer.

The eddy diffusion coefficients calculated are in good agreement with those which would be predicted by empirical methods. The results when applied to phosphorus cycling indicate that P reflux from the hypolimnion and thermocline in eutrophic Greifensee is of the same magnitude as external inputs during the months of maximum photosynthesis.
Wind‐driven, steady flows in Lake Superior 1
Authors: Lien S. L. , Hoopes J. A.
Published: March 2010

The wind‐induced, steady state circulations in Lake Superior were investigated by use of both mathematical and physical models. The mathematical model was developed from the equations of motion, assuming a homogeneous lake, negligible nonlinear accelerations, constant Coriolis force, hydrostatic pressure distribution, negligible horizontal turbulent shear stresses, and constant vertical eddy viscosity. With these assumptions, the equations of motion were solved analytically to give expressions for the velocities in terms of position in lake, wind stress, water surface slopes, depth, vertical eddy viscosity, and bottom condition (i.e. no‐slip or slip). Water surface slopes were obtained from a numerical solution to the vertically integrated equations of motion, expressed in terms of a mass transport stream function and subject to appropriate wind stress and inflow‐outflow conditions. Two‐ and three‐dimensional velocity fields were obtained for uniform and curl wind stress distributions, for constant (average) and actual (variable) depth conditions, and for slip and no‐slip on bottom.

Laboratory experiments on the wind‐generated circulation were conducted in a rotating, vertically distorted model of Lake Superior. Surface current patterns were obtained for steady, westerly winds that were constant in magnitude (uniform) over the lake and that had a constant curl (speeds decreased linearly from south to north) over the lake. The laboratory circulation patterns are in reasonable agreement with results from the numerical model.
Phosphorus loadings to lakes and some of their responses. Part 1. A new calculation of phosphorus loading and its application to 13 New York lake 1
Authors: Schaffner W. R. , Oglesby R. T.
Published: March 2010

Changes are proposed in ways of expressing phosphorus loadings to lakes. A composite species of phosphorus (the sum of soluble reactive, soluble unreactive, and that potentially desorbable from particulate matter) is substituted for the total P used by most investigators. Loadings are expressed as the amount added annually to a volume equivalent to that of the epilimnion, for stratified lakes, and to lake volume for those that are unstratified, rather than to surface area or to total volume regardless of mixing depth. These alterations in calculating loading result in values that more closely approximate the supply of phosphorus available for uptake by the phytoplankton community.

Procedures followed in estimating the phosphorus contributed to lakes from various sources are critically discussed, with particular emphasis on that from human populations and runoff from rural lands. Phosphorus loss coefficients are given for the latter. Loadings to 13 New York lakes are calculated. The principal effects of using the composite form of phosphorus and loading to the mixed zone rather than total P and areal loading are to de‐emphasize the effects of agriculture and to emphasize phosphorus input to shallow lakes.
Use of fluorescence microscopy for quantifying phytoplankton, especially filamentous blue‐green algae 1
Authors: Brock Thomas D.
Published: March 2010

Lake water samples were stainedwith primuline and filtered on black membrane filters. The phytoplankton were visualized under wet mount at high magnification. For filamentous blue‐green algae of indefinite lengths, volumes were estimated from counts of the numbers of crosses that filaments made with a grid placed in the ocular. Identification of algae on the filters was relatively easy and the method was amenable to rapid counting with large volumes of water.
Fulvic acid interferences on ATP determinations in sediments 1
Authors: Cunningham H. Wilson , Wetzel Robert G.
Published: March 2010

Organic and cationic inhibitions of ATP determination in sedimentary systems are large. Cationic inhibitions are reversible and can be successfully removed by cation exchange resins or by precipitation with oxalic acid. Acid‐soluble organic compounds (fulvic acids) complex with extracted ATP; 70–80% of the ATP will not react with the luciferin‐luciferase complex. Inhibitions by the fulvic acid are not reversible. When combined with other metabolic parameters, ATP concentrations provide a good estimate of the metabolic activity of a community.
Radiocarbon uptake: Its relation to net particulate carbon production 1
Authors: Peterson Bruce J.
Published: March 2010

Organic carbon budgets for mixed cultures of lake phytoplankton indicate that [14C]CO2 uptake overestimates net particulate carbon production. The overestimate is slight (10–20%) for rapidly increasing assemblages, but ranges to severalfold for nutrient‐poor, slow‐growing cultures. A rationale is presented for estimating the yield of particulate carbon for natural assemblages from data on biomass and 14C uptake.
The effect of growth curve and sampling regime on instantaneous‐growth, removal‐summation, and Hynes/Hamilton estimates of aquatic insect production: A computer simulation 1
Authors: Cushman R. M. , Shugart H. H. , Hildebrand S. G. , Elwood J. W.
Published: March 2010

Hypothetical populations of aquatic insects were periodically sampled, using a computer model, to estimate production by the instantaneous‐growth, removal‐summation, and Hynes/Hamilton methods. These estimates were compared with the production values calculated from the daily growth of all individuals in the populations. The removal‐summation method yielded the most accurate estimates for a variety of growth curves and sampling regimes and appeared to be the least sensitive to violations of the growth assumptions of the method.
An in situ study of the productivity and population dynamics of five freshwater planktonic diatom species
Authors: Knoechel R. , Kalff J.
Published: March 2010

In situ carbon fixation rates were determined through track autoradiography for Asterionella formosa Hassall, Fragilaria crotonensis Kitton, Melosira italica Ehrenberg, Synedra radians Kützing, and Tabellaria fenestrata Kützing during their wax and wane in a small lake. Photoinhibition of primary production was much stronger than predicted from culture studies, while temperature effects were minimal. Despite the severity of photoinhibition, long term cell growth was maximal at or near the surface for all species. The general magnitude of cell growth was determined primarily by the maximum photosynthetic rate which, for at least one species, was in turn strongly correlated with precipitation (as a measure of nutrient loading). Epilimnetic cell division was mildly light limited except for M. itadica and S. radians, each of which had a relatively high saturation intensity. Population fluctuations were correlated quite strongly with estimates of sinking rather than cell growth; sinking was in turn correlated with death. Changes in abundance of these diatom populations were thus largely the result of variables loss rates.
Spatial distribution of phytoplankton species in chlorophyll maximum layers off southern California 1
Authors: Reid F. M. H. , Stewart E. , Eppley R. W. , Goodman D.
Published: March 2010

The phytoplankton species assemblages of the chlorophyll maximum layer and the surface layer were compared in March 1976 at several stations off southern California. The assemblages in the two layers were quite different in the southern inshore part of the study area but were similar offshore and in Santa Monica Bay to the north. In both layers the assemblages changed more abruptly offshore than alongshore and gave the impression of elongate bands of phytoplankton oriented parallel to shore. Principal component analysis resolved two axes which accounted for the preponderance of the variability of species abundances. Component I consisted of several dinoflagellate and one coccolithophorid species, component II of several diatom species and the pigmented ciliate Mesodinium rubrum.