bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation of light and daily integral rates of photosynthesis attained by planktonic algae1
Authors: Megard R. O. , Combs W. S. , Smith P. D. , Knoll A. S.
Published: March 2010

The daily integral rate of photosynthesis attained by planktonic algae in Lake Minnetonka, Minnesota, conforms to an equation for a rectangular hyperbola proposed by Bannister. The rate depends on the concentration of chlorophyll a in the mixed layer and also upon two kinetic parameters that are analogous to the kinetic constants in equations for reactions catalyzed by enzymes. One parameter is an upper limit, ψ, that would be attained by very dense populations, and the other is a concentration of chlorophyll, c', at which attenuation of photosynthetically active radiation (PhAR) by the algae equals background attenuation by the water. The parameters were evaluated with the same statistical procedures used to evaluate the kinetic constants for enzyme reactions.

The limit, ψ, for the daily integral rate in this lake would be about 0.5 mol O2·m−2·d−1 Observed daily rates are usually <0.7 ψ, because chlorophyll in the water usually intercepts <70% of the radiant energy. Coefficients for the attenuation of PhAR by chlorophyll,, and by the water, were estimated from the linear regression of the total attenuation coefficient, ε, on chlorophyll concentration. The estimate of εc is 0.022 ± 0.005·m−1·(mg Chl·m−3)−1. Background attenuation, εw, affects integral photosynthesis in the same way as a competitive inhibitor affects enzyme reactions: it is a constituent of c′ = εw/εc which, together with chlorophyll concentration, determines the fraction of underwater PhAR intercepted by planktonic algae.
Nutrient dependence of primary productivity in lakes1
Authors: Smith Val H.
Published: March 2010

An analysis of growing season measurements of daily primary productivity, chlorophyll, water chemistry, and transparency from 58 north temperate lakes shows a strong correlation between volumetric rates of photosynthesis, chlorophyll, and nutrients. Mean daily rates of photosynthesis per unit volume euphotic zone, v̄, are correlated with mean chlorophyll concentration (r2 = 0.80). The mean daily rate of photosynthesis at optimal depth, Āopt, is highly correlated with mean total P(r2 = 0.95), and with mean total N(r2 = 0.91). In contrast, integral rates of photosynthesis are linked less tightly to nutrient concentration because of their simultaneous dependence on transparency. The Dillon‐Rigler phosphorus loading model is extended to predict volumetric rates of photosynthesis (v̄ and Ā̄opt) in lakes where the N:P balance indicates control by phosphorus (N:P ⩾ 13).
Two phases of the phytoplankton community in the Baja California upwelling1
Authors: Estrada Marta , Blasco Dolors
Published: March 2010

The method of principal component analysis has been applied to quantitative data on 60 species of phytoplankton from the cruises MESCAL I and MESCAL II. Dinoflagellatc dominance in the phytoplankton was associated with upwelling of water of relatively low salinity and lower nutrients from below the minimum salinity core of the California Current. Diatom dominance was related to upwelling of deeper saline and high nutrient water from the California Undercurrent.
Effects of temperature on the swimming of salps (Tunicata, Thaliacea): Implications for vertical migration1
Authors: Harbison G. R. , Campenot R. B.
Published: March 2010

Salps swim by means of rhythmic contractions of the circular body muscles. In most species, these contractions are regular. At constant temperature, the pulsation rate is inversely related to body length for hand‐collected animals. Such a relationship is not seen with trawl‐collected salps. When temperature is lowered experimentally, marked differences are seen in the response of individual species. The pulsation rates of Pegea confederata, Cyclosalpa polae, and Salpa cylindrica are greatly depressed and cease altogether at low temperatures (response type I). For Pegea socia, Cyclosalpa pinnata, Cyclosalpa affinis, and Salpa maxima, the pulsation rates are usually greatly depressed, but do not cease, even at extremely low temperatures (response type II). The pulsation rates of Salpa fusiformis and Salpa aspera are largely insensitive to changes in temperature (response type III). Evidence from net sampling suggests a relationship between these response types and vertical and horizontal distribution patterns. Salps showing response type I are found only in tropical and subtropical surface waters; those showing response type II are more widely distributed or are found in temperate waters; and those showing response type III are vertical migrators. Thus, differences in the temperature response provide clues as to the differing modes of life available to salps in the open sea.
Effects of temperature and fasting on the rate of sinking of Hydra oligactis1
Authors: Schroeder Lauren Alfred , Reeder Patricia S.
Published: March 2010

Sinking rates of Hydra oligactis Pallas reared at 10°, 15°, and 25°C were determined in a water column at 10°, 21°, and 26°C after fasting intervals ranging from 24 to >500 h. The rearing temperature (Tr), water temperature during sinking (Tw), duration of fasting (Ft), and body conformation (Hc) (i.e. body length, tentacle length, and tentacle orientation) all significantly correlated with sinking rate. The linear regression model: sinking rate (cm·s−1) = 0.684 − 0.0323Hc − 0.00055Ft − 0.00959Tr + 0.00711Tw accounted for 85% of the observed variability.

Hydra density (g·cc−1) was inversely related to rearing temperature and decreased from 1.030 g·cc−1 for animals reared at 10°C and 1.025 for those reared at 25°C to a plateau of 1.017 g·cc−1 for both rearing temperatures after 200 h and 80 h of fasting for hydras reared at 10° and 25°C. Hydra size also was inversely related to rearing temperature ranging from >100 µg (dry wt) per single hydra at 10°C to 30 µg dry wt at 25°C. Hydra size decreased with fasting to <10 µg dry wt. Changes in hydra density and surface area:volume ratio account for 80 and 97% of the change in sinking rate of fasting hydras reared at 10°C and 25°C.

Hydras are especially susceptible to planktonic existence during spring and fall turnover and may become dispersed throughout lakes, but during summer stratification the increased sinking rates would significantly reduce the potential for their lateral transport in the epilimnion.
Midultraviolet (UV‐B) sensitivity of Acartia clausii Giesbrecht (Copepoda)1
Authors: Karanas James J. , Dyke Henry Van , Worrest Robert C.
Published: March 2010

The sensitivity of all life stages of laboratory‐cultured Acartia clausii to various fluences of UV‐B radiation was evaluated. Organisms were irradiated on a rotating turntable beneath FS40 sunlamps and “deluxe white” fluorescent lamps. Copepods were randomly assigned to treatments utilizing a randomized complete block design. Least‐squares regression analysis was performed between surviving fraction and fluence for all treatments administered to each age group and also between the offspring:survivor ratio and fluence for treatments administered to the oldest age group, which was composed of equal numbers of males and females. Results indicated an inverse relationship between surviving fraction and UV‐B exposure. Reproductive capability of the surviving organisms was also negatively affected.
Ultraviolet radiation and phytoplankton photosynthesis1
Authors: Lorenzen Carl J.
Published: March 2010

The effect of present‐day levels of ultraviolet radiation (290–320 nm) on 14C incorporation by natural phytoplankton populations was measured. There is a statistical relationship between dosage and reduction of 14C uptake. This effect could be detected throughout a significant portion of the euphotic zone, but the major effect is restricted to the upper portions of the euphotic zone. Overall, its effect on present‐day estimates of oceanic production is minimal. Similarly, potential effects of elevated UV‐B levels striking the surface of the sea, resulting from perturbations of the ozone layer, are restricted to the upper few meters of the water column.
Assessment of sediment trap collection efficiency
Authors: Hargrave Barry T. , Burns Noel M.
Published: March 2010

Theoretical considerations of the effects of turbulence around and within sedimentation traps show that the aspect ratio (height:mouth opening) of the traps is important in determining particle retention. Collection efficiency and comparative measures of deposition per unit area in traps of various design were independent of this ratio in cairn water, but an asymptotic relation of increased collection efficiency with higher aspect ratio existed under nonstagnant conditions. Turbulent mixing in a water column could be assessed by comparisons of deposition in collectors exposed simultaneously but having different aspect ratios.
Methanogenic activity in plankton samples and fish intestines A mechanism for in situ methanogenesis in oceanic surface waters
Authors: Oremland Ronald S.
Published: March 2010

When plankton samples were incubated anaerobically with a cysteine‐sulfide reducing agent, pronounced methane evolution occurred. This activity was inhibited by air, CHCl3, C2H2, and 2‐bromoethanesulfonic acid. Adding [14C]CO32− resulted in accumulation of [14C]CH4. Portions of the digestive tracts of three fishes were incubated in methanogenic media, and two of the samples showed the presence of methanogenic bacteria.
A modified procedure for determining [14C]CO2 produced by respiration in water or sediment samples1
Authors: Brown Keith A.
Published: March 2010

Poor recovery of radioactivity when determining [14C]CO2 respired by microbes can be overcome by substituting 2‐ethanolamine for 2‐phenylethylamine to absorb [14C]CO2 and by increasing the solubility of absorbed [4C]CO2 in the scintillation solution with 2‐ethoxyethanol.
Water and nutrient transport via groundwater from Ward Valley into Lake Tahoe1
Authors: Loeb Stanford L. , Goldman Charles R.
Published: March 2010

The amount of groundwater transported from the Ward Valley watershed into Lake Tahoe during the 1975 water year was 4.1 × 106 m3. This was 16% of the water volume carried by Ward Creek and 10% of the total precipitation within the watershed during the same period. Of the total nutrient loading of Lake Tahoe from the Ward Valley watershed, groundwater contributed 49% of the total nitrate‐nitrogen and 44% of the total soluble phosphorus loads. Groundwater may be a significant source of water and dissolved nutrients for Lake Tahoe, particularly in the littoral zone.
Acid precipitation: Measurement of pH and acidity1
Authors: Galloway James N. , Cosby Bernard J. , Likens Gene E.
Published: March 2010

The pH and acidity of precipitation are difficult to measure accurately because of the low ionic strength of the samples. Use of measured pH to estimate hydrogen‐ion concentration may err by as much as 50% if activity coefficients, junction and streaming potentials, and non‐Nernstian behavior of the electrode system are ignored. The magnitude of the individual errors is assessed and procedures for measuring pH and acidity to reduce the total error to ±5% are recommended.
In defense of grain density autoradiography
Authors: Hans W. Paerl , Elisabeth Ann Stull
Published: March 2010

A high degree of correlation was found between the techniques of grain density and track autoradiography in a study of natural phytoplankton communities. Because it becomes increasingly difficult to distinguish tracks from closely grouped silver grains with increasing exposure times, the track method is often restricted to the most photosynthetically active species. Grain density autoradiography enables comparisons of the activity of species with a wide range of metabolic intensity.
Availability to Scenedesmus quadricauda of different forms of phosphorus in sedimentary materials from the Great Lakes1
Authors: Williams J. D. H. , Shear H. , Thomas R. L.
Published: March 2010

Sedimentary materials from eroding bluffs, suspended solids in streams, and lake bottom sediments from Lakes Ontario and Erie were cultured with the alga Scenedesmus quadricauda (Turp.) de Brébisson in modified Rodhe’s medium with the sediments as the sole source of P. P uptake by the algae was related to the amount of nonapatite inorganic phosphorus in the sediments. Apatite phosphorus was not used, and the bluff samples, in which over 90% of total P was in this form, did not support algal growth. The nonapatite inorganic P fraction was highly correlated with the amounts of inorganic phosphorus extracted by three standard techniques for estimating “available P” (extraction by NaOH and nitrilotriacetic acid solutions and by H‐resin) and cell uptake equaled NaOH‐extractable inorganic P in several instances. Uptake of P by the cells varied from 8 to 50% of total P and from 38 to 83% of nonapatite inorganic P when measured directly. Organic phosphorus in the sediments was not utilized by the algae. Percentage utilization of total P was in general highest when total P concentration in the sediments was itself high.
Buffering of silica and phosphate in a turbid river1
Authors: Mayer Lawrence M. , Gloss Steven P.
Published: March 2010

The buffering of riverine dissolved silica and phosphate by sorption reactions between the aqueous phase and suspended sediment is examined with the turbid Colorado River system as a model. Concentrations are found to lie in a range predicted from laboratory sorption experiments with natural sediments and waters. Phosphate is probably highly buffered by suspended sediment during river flow while silica is not. Silica appreciably affects phosphate sorption reactions but not vice versa. Increased temperature results in higher silica but lower phosphate concentrations as a result of sorption. The buffering action of suspended sediments is largely complete within a few hours and is approximately proportional to the concentration of suspended sediment.
The influence of adsorption on the rates oi n degradation of arsenic species in sediments1
Authors: Holm Thomas R. , Anderson Marc A. , Stanforth Robert R. , Iverson Dennis G.
Published: March 2010

A model to describe the rates of microbially mediated transformations is presented along with a simple numerical method for kinetic computations in complex systems. The model is tested against the results of arsenic demethylation experiments assuming first‐order kinetics and Langmuir adsorption. There is agreement between theory and experiment.
Groundwater transport of a salt tracer through a sandy lakebed1
Authors: Lee David Robert , Cherry John A. , Pickens John F.
Published: March 2010

In an investigation of groundwater advection and dispersion in a lakebed, a vertical zone of salt solution was injected between 1.7 and 3 m beneath the shoreline and entered the lake through a large area of lakebed at a reduced concentration. Migration of the tracer pulse and flux to the lake were monitored over a 7‐ × 8‐m area of lakebed by measuring the electrical conductance of water collected from sampling points beneath the lakebed and from seepage meters on the lakebed. The tracer moved horizontally, curved gently upward, and entered the lake through an area of 17 m2—an area 5.7 times larger than the initial cross‐sectional area of the tracer zone. Seepage flux through the sediment‐water interface declined exponentially with offshore distance and averaged 240 m3·yr −1 per meter of shoreline.

Results showed that prediction of solute flux from onshore zones of groundwater contamination requires consideration of dispersion (mixing) and the ratio of horizontal to vertical permeability (Kh:Kv). Numerical simulations showed that with increasing Kh:Kv, tracer‐ or contaminant‐entry areas on the lakebed extend over larger areas and are displaced farther offshore. A Kh:Kv of 10 matched the field observations. An analytical model indicated that the observed reduction in peak concentration (a decline to 31% of the initial value over a 6‐m flow path) would result from values of longitudinal dispersivity as small as 1 cm.
Copper complexation by siderophores from filamentous blue‐green algae1
Authors: McKnight Diane M. , Morel Francois M. M.
Published: March 2010

From our experimental evidence that iron limitation greatly increases the extracellular concentration of strong copper‐complexing agents in cultures of Anabaena flos‐aquae and Anabaena cylindrica, and that the iron‐algal exudate complex is much more stable than the copper complex, we conclude that strong copper‐complexing agents released by filamentous blue‐green algae are siderophores. Further experiments demonstrate that siderophore excretion is not a mechanism by which blue‐green algae overcome the toxic effects of micromolar copper additions. From estimates of concentrations of iron, copper, and siderophores in iron‐limited blue‐green algal blooms, it is predicted that the copper‐siderophore complex is the major copper species. The copper‐siderophore complex is probably not toxic and its presence in freshwaters may be advantageous to cyanophyte populations.
Evidence for algal heterotrophy in Lake Tahoe, California‐Nevada1
Authors: Vincent Warwick F. , Goldman Charles R.
Published: March 2010

Significant differences in the uptake of 14C organic compounds between light and dark bottle incubations of water were recorded from Lake Tahoe. The response to light did not occur in situ below the maximum depth of inorganic carbon photoassimilation and was completely inhibited by a photosynthetic inhibitor. Dark acetate uptake in the deep euphotic zone (ca. 90–150 m) was strongly inhibited by a eucaryotic inhibitor. Microautoradiographic analysis showed that two species of green algae in Tahoe were capable of acetate transport at labeled substrate additions within previously determined ambient limits; in axenic culture these two species grew heterotrophically on acetate. Activities of key enzymes of the major inducible pathway for acetate assimilation were high per unit ATP in the region of the water column where acetate uptake was light stimulated. These data strongly support the hypothesis of heterotrophically active phytoplankton populations at the bottom of the euphotic zone.
Methane addition to an arctic lake in winter
Authors: Welch H. E. , Rudd J. W. M. , Schindler D. W.
Published: March 2010

The possible usc of buried pipelines to transport natural gas (≃99% methane) through the Canadian arctic prompted us to study some of the dynamics of methane metabolism in an arctic lake at 63°38'N lat. The two basins of the lake were separated during winter 1977–1978 by a curtain and 300 kg of methane was dissolved into one side, to a maximum of 120 µM · liter−1 or 0.7 M· m−2. Oxidation occurred throughout the water column but the highest rates were at or nearthe sediment surface. High phosphate and nitrate additions did not stimulate oxidation. The sediments generated methane naturally and winter concentrations in undisturbed lakes were 0.2–1.0 µM·liter ‘. The added methane disappeared at a slow, steady rate of 1.89 mM · m−2· d−1 or 0.32 µM · liter 1· d−1 from February to June. The oxygen depletion rate of the entire experimental basin was 0.244 g· m−2· d−', compared with 0.210 in the control basin, and was not measurably affected by artificially added methane; a winter pipeline rupture would therefore probably not result in severe oxygen depletion in downstream lakes. These and other results were not expected based upon our knowledge of methane dynamics in temperate lakes.
Mixing processes on the Atlantic continental shelf, Cape Cod to Cape Hatteras
Authors: Fischer Hugo B.
Published: March 2010

Data from moored current meters and airborne and satellite observations are used in conjunction with analyses of shear flow dispersion to estimate the dispersion of dissolved substances in the Middle Atlantic Bight during unstratified periods. The long‐shelf dispersion coefficient is estimated to be of the order of 104−105 cm2·s−1, and the cross‐shelf dispersion coefficient of the order of 3 × 105 cm2·s−1 at midshelf. The cross‐shelf estimate is a factor of 10 less than previous ones, which were based on the assumption that the cross‐shelf flux of freshwater is equal to the inflow from tributary rivers within the bight itself.
Effects of hunger and season on the feeding behavior of Calanus pacificus1
Authors: Runge Jeffrey A.
Published: March 2010

Clearance rates were determined for starved and previously fed females of Calanus pacificus grazing on single sizes and mixtures of sizes of unicellular diatoms. Starved females fed at higher rates than previously fed animals, even at low food concentrations. In experiments with starved Calanus grazing on mixtures of sizes of diatoms, clearance rates increased progressively with increasing cell size and the clearance rate on any cell size was independent of the relative availability of that size. However, starved Calanus removed diatoms of different sizes from the water at different relative efficiencies from continuously feeding females. Because C. pacificus females migrate vertically and are undoubtedly accustomed to a diurnal variation in the availability of food, experiments incorporating a period of starvation may reflect more accurately their feeding behavior in the field. The observations were made in several seasons and include strong seasonal changes in the maximum clearance rate which appear to be associated with the timing of the spring bloom of phytoplankton in the main basin of Puget Sound.
Trace elements in acantharian skeletons1
Authors: Brass G. W.
Published: March 2010

The celestite (SrSO4) skeletons of acantharians may be an important transport vector for several trace metals, extracting them from surface water and releasing them at the depth of the oxygen minimum‐nutrient maximum. Iron and lead seem to be incorporated as particles while copper and zinc may be lattice cations in the celestite. Removal rates from the surface water are estimated to be 40, 92, 39, and 34 ng · cm−2 · yr −1 for Cu, Fe, Zn, and Pb.
Calculation of the in situ pH of seawater1
Authors: Culberson Charles H.
Published: March 2010

The in situ pH at oceanic temperatures and pressures is calculated from the exact solution to the cubic equation relating total inorganic carbon dioxide to total alkalinity. The method does not require iteration. The equations for calculating pH from the partial pressure of carbon dioxide and the total alkalinity are also given.
Dependence of mean spectral extinction coefficient of phytoplankton on depth, water color, and species
Authors: Atlas David , Bannister T. T.
Published: March 2010

From published absorption spectra of algae (green, blue‐green, and diatoms) and from published data describing spectral irradiance as a function of depth in blue, green, and blue‐green waters, values of the mean spectral extinction coefficient k̅c (m2·mg−1 Chl a) of the algae were calculated. For all three algal types, k̅c has nearly the same value (0.014±0.002) at the surface. For all three types, k̅c increases with depth in blue water, decreases with depth in green water, and changes relatively little in blue‐green water. The largest variation occurs with the green alga, k̅c ranging from 0.005 at depth in green water to 0.021 or more at depth in blue water.
Some relationships between stream benthos and substrate heterogeneity
Authors: Williams D. Dudley
Published: March 2010

Baskets filled with stones, to give four different degrees of heterogeneity, were placed in a stream and made available for colonization by benthic invertebrates. No difference resulted in the total numbers and weights of animals colonizing; 26% of the species, however, showed clear substrate preferences, 35% showed slight preferences, and 39% showed none. The last group made up most of the benthic invertebrate biomass. A high quantity of detritus accumulated in each substrate, and this may account for the similar densities of detritivores collected on all four substrates.
Advective control of nutrient dynamics in the epilimnion of a large reservoir1
Authors: Gloss Steven P. , Mayer Lawrence M. , Kidd David E.
Published: March 2010

Silica, nitrate, total and dissolved phosphorus, and conductivity were measured during spring and summer in Lake Powell, Utah‐Arizona. Phytoplankton productivity was also determined. Conductivity is used as a tracer for delineating the advective influence of inflows from the Colorado and San Juan Rivers on nutrient delivery and distribution in the reservoir. High spring runoff (1,000–2,000 m3·s−1) enters the lake essentially as an overflow and dominates the nutrient cycle in the epilimnion. The interaction of advective nutrient delivery and high turbidity controls the distribution of phytoplankton productivity and nutrient depletion.
Recent sedimentation and its relationship with primary productivity in four western Washington lakes1
Authors: Birch Peter B. , Barnes Robert S. , Spyridakis Dimitris E.
Published: March 2010

Studies of sedimentation processes in four western Washington lakes reveal up to sixfold variations in sedimentation rates over the past 130 years of settlement in the region. These variations in sedimentation can be linked with known changes in land use in the watersheds, especially logging, which appears to have accelerated erosion.

Contemporary deposition of phosphorus into profundal sediments is positively correlated with phytoplankton productivity in the four lakes. If a similar relationship existed in the past when sedimentation rates of phosphorus were different, then increases in primary productivity from twofold to fourfold could have occurred in three of the lakes since about 1840.
The relative contribution of aquatic macrophytes and their epiphytes to the production of macrophyte beds1
Authors: Cattaneo A. , Kalff J.
Published: March 2010

The epiphyte contribution to the total production of Lake Memphremagog macrophyte beds changed in a predictable fashion with the season, the morphology of the macrophytes, the depth of the bed, and the trophy of the water. In the mesotrophic portion of the lake, epiphytes fixed more carbon than the macrophytes only at the beginning and end of the growing season, whereas under more eutrophic conditions they did so even during summer.
In situ feeding behavior of Sagitta elegans and Eukrohnia hamata (Chaetognatha) in relation to the vertical distribution and abundance of prey at Ocean Station “P”1
Authors: Sullivan Barbara K.
Published: March 2010

The feeding behavior and diet in nature are described for two species of chaetognaths in an open ocean community. Sagitta elegans lives and feeds primarily in the upper water column (0–25 m) and the vertical distribution of this species may be explained primarily by its requirement of high prey densities. Eukrohnia hamata apparently needs less food and is found mainly below the mixed layer with a vertical distribution restricted by temperature. The same prey species, those with the highest densities at Station “P,” make up the diet of both chaetognaths, although Eukrohnia eats significantly more small prey. The major prey of juvenile chaetognaths (numerical frequency) are small cyclopoid copepods, a group frequently overlooked in plankton surveys. These species also comprise 41% of the diet of older chaetognaths, which prey in addition on stage V copepodites of the largest copepods. It is suggested that the development of larval chaetognaths depends on abundant, small prey but that older chaetognaths can handle prey of a very wide spectrum of sizes.
The diffusion coefficients of sulfate, ammonium, and phosphate ions in anoxic marine sediments1
Authors: Krom Michael D. , Berner Robert A.
Published: March 2010

The diffusion coefficients of sulfate, ammonium, and phosphate ions were determined directly in the laboratory by placing two samples of homogenized, anoxic mud from Long Island Sound in contact with one another across a planar interface. After 141 h concentration profiles were determined and from them, values of effective diffusion coefficients (which incorporate the effects of adsorption) were calculated. Correction of these values for adsorption, using independently determined linear adsorption constants for the same sediments, gave the following values (× 10−6 cm2· s−1, 20°C, errors ±2σ): Ds(SO4), 5.0±1.2; Ds(NH4), 9.8±2.0; Ds(PO4), 3.6±1.1. These values agree well with values calculated for the same sediments from estimates of formation factors plus data for diffusion coefficients at infinite dilution.
Volatile liquid hydrocarbons in waters of the Gulf of Mexico and Caribbean Sea1
Authors: Sauer Theodor C.
Published: March 2010

Concentrations of volatile liquid hydrocarbons (VLH), C6−C14 hydrocarbons, were determined in 1977 in coastal, shelf, and open‐ocean surface waters of the Gulf of Mexico and Caribbean Sea. In open‐ocean, nonpetroleum‐polluted surface water, VLH concentrations were 60 ng·liter−1 while in heavily polluted Louisiana shelf and coastal water values reached ≈500 ng·liter−1. Caribbean surface samples had very low concentrations, ≈30 ng·liter−1. The relationship between anthropogenic gaseous hydrocarbons and VLH was approximately linear. Aromatic VLH accounted for 60–85% of the total VLH in surface waters. Cycloalkane concentrations were <1.0 ng·liter−1 in open ocean water, 60–100 ng·liter−1 in polluted water (20% of total VLH). Alkanes were ≈15 ng·liter−1 in open ocean water, 40 ng·liter−1 in polluted water. The concentrations of five major VLH compounds (aromatics) in water samples—benzenc, toluene, ethylbenzene, m‐, p‐xylenes, and o‐xylene (called BTX)— were sufficient to predict the total VLH. The empirically determined relationship is VLH(ng·liter−1) = 1.42 BTX (ng·liter−1); r = 0.96.

Subsurface VLH concentrations in samples of polluted waters collected from depths of 50 in were only 35–40 ng·liter−1 below surface concentrations. Open ocean subsurface samples had concentrations of only ≈30 ng·liter−1 at 30–50‐m depths, comparable to those of Caribbean surface water.
The role of methane in internal carbon cycling in Lake Mendota during summer stratification
Authors: Fallon R. D. , Harrits S. , Hanson R. S. , Brock T. D.
Published: March 2010

The rate of methane formation and evasion was estimated during summer stratification from methane profiles and the rate of methane oxidation measured with 14CH4. Organic carbon sedimentation was measured with sedimentation traps. For the deep‐water sediments of Lake Mendota, about 54% of the organic carbon sedimented returns as methane. Methane oxidation at the thermocline is a much more significant process in Lake Mendota than in Lake 227 during summer stratification, apparently because of the higher eddy diffusivity in Lake Mendota, with concomitant transfer of oxygen and nutrients to the zone where methane oxidation occurs.
Biologically effective dose transmitted by culture bottles in 14C productivity experiments1
Authors: Smith Raymond C. , Baker Karen S.
Published: March 2010

Culture bottles used for “C productivity experiments transmit different amounts of ultraviolet radiation depending on their glass composition. A quantitative assessment of the spectral irradiance penetrating three commonly used glass types has been made. By assuming a biological efficiency for photoinhibition, the biologically effective dose within each type of bottle can be quantitatively calculated. The biologically effective dose is reduced about 6% by quartz bottles, 13% by Pyrex bottles, and 22% by Wheaton glass bottles at the water surface. These effects become smaller with increasing depth in in situ measurements.
Size‐selective predation, light transmission, and oxygen stratification: Evidence from the recent sediments of manipulated lakes1
Authors: Kitchell Jennifer A. , Kitchell James F.
Published: March 2010

In an experiment maintained since 1951, half of a divided lake was limed, resulting in a significantly expanded euphotic zone. In both basins native fish were removed and rainbow trout introduced. Quantitative analysis of zooplankton remains preserved in the sediments of both lakes provides evidence of the selectivity of a visually dependent predator at natural and enhanced transparency and oxygen concentrations.

The sediment record effectively documents the known manipulations and the expected responses. In the control lake, no significant changes in zooplankton species composition, species dominance, or size‐frequency distribution are recorded. In the alkalized lake, a succession in zooplankton dominance from Daphnia pulex to Daphnia rosea to Bosmina is recorded, as is a reciprocal change in mean size of D. pulex and D. rosea. The relative position of the thermocline with respect to the oxygen minimum barrier and the light transmission curve accounts for the observed differences in selective predation intensity.
Distribution of oxygen in marine sediments measured with microelectrodes1
Authors: Revsbech Niels Peter , Sorensen Jan , Blackburn Thomas Henry , Lomholt Jens Peter
Published: March 2010

Membrane‐covered platinum electrodes with a tip diameter of 2–8 µm were used for an amperometric assay of dissolved oxygen in marine sediments. The oxygen profile extended to 3–5‐mm depth in nonilluminated sediment; even at high light intensities and at low temperatures it did not extend below 10‐mm depth in a homogeneous sandy sediment. Oxygen profiles recorded during light‐dark cycles were used to estimate the rates of oxygen production and consumption and also to calculate the apparent diffusion coefficient for oxygen in the sediment. Apparently macrofaunal activity, rather than molecular diffusion and water turbulence, was important for the occasional transport of oxygen into deeper layers and thus for the provision of oxidized conditions (positive redox potential) down to 5–10 cm below the sediment surface.
The egg production of a marine planktonic copepod in relation to its food supply: Laboratory studies1
Authors: Checkley David M.
Published: March 2010

Egg production by Paracalanus parvus, a particle‐grazing copepod, was investigated in relation to its food supply. The concentration of available food (P) and the rates of ingestion (I) and egg production (B) were measured simultaneously at intervals of 6 h to 2 d for periods of 2–10 d. Concentration, chemical composition (carbon and nitrogen), and species of phytoplankton were experimental variables.

Egg production was related to the food ingested during the previous day. For one food type, I and B were rectilinear functions of P. The average maximum rates of ingestion and egg production were 1.1 µg N·female−1·d−1 and 53 eggs·female−1·d−1, equivalent to specific rates of 1.5 and 0.37·d−1. B was proportional to I below a critical ingestion rate, Ic, and independent of I above Ic. For I <Ic, the gross efficiency of egg production (B ·I−1) in terms of nitrogen was 0.37 while in terms of carbon it was a hyperbolic function of the ratio of C:N in the food, ranging between 0.41 (C:Nfood = 4.0) and 0.15 (C:Nfood = 11). For I >Ic, B·I−1 declined in terms of both carbon and nitrogen.

These results, together with the ratio of C:N in particulate matter in the sea off southern California, suggest that nitrogen (hence protein) potentially limits egg production by adult female Paracalanus and that ingested carbon is used inefficiently.
Nutrient‐ and light‐limited growth of Thalassiosira fluviatilis in continuous culture, with implications for phytoplankton growth in the ocean1
Authors: Laws Edward A. , Bannister T. T.
Published: March 2010

The marine diatom Thalassiosira fluviatilis was grown in a continuous culture system at 20°C on a 12:12 L:D cycle over a series of nutrient‐ and light‐limited dilution rates. Bannister’s theoretical model describing nutrient‐saturated growth gave an excellent fit to the light‐limited data. A simple extension of the model allows description of nutrient‐limited growth as well. Dark carbon loss rates were in the range 10–20% of daytime production rates at dilution rates ⩾0.25 d−1. The relationship between Chl a:C ratios and dilution rate was linear under nutrient limitation and independent of the type of limiting nutrient. Productivity indices under nutrient limitation were found to be a hyperbolic function of dilution rate. N:C ratios were linearly correlated with dilution rate under both light and nutrient limitation, but with the regressions having opposite signs.
Oxidative polymerization of dissolved phenols by soluble and insoluble inorganic species1
Authors: Larson Richard A. , Hufnal John M.
Published: March 2010

Transition metal oxides (MnO2, ZnO, CuO) and cations (Mn2+, Fe3+) promoted the polymerization of dissolved catechol (1,2‐dihydroxybenzene) and other catechol and pyrogallol derivatives. The manganese species were the most efficient. Colored polymers were formed from catechol much more rapidly in stream waters than in deionized water buffered to the same pH. Addition of sediments or clays increased polymerization; addition of EDTA or lowering the pH reduced it. Ultrafiltration or autoclaving of the stream water samples had no significant effect. The mechanism appears to incorporate an activation of dissolved O2 to a more reactive species, probably •OH.
Windpower time series above a temperate lake
Authors: Stauffer Robert E.
Published: March 2010

A computer model of windpower flux was developed for Lake Mendota, Madison, Wisconsin, based on 3‐h wind speeds and estimates of above‐lake bulk Richardson number, and then was applied to the period 1 April–31 October (1966–1975). Fifteen years (1962–1976) of hourly records were also analyzed for Simcoe, Ontario (Lake Erie Basin).

Expected power varies diurnally during all seasons, in phase with, or lagging slightly behind the solar cycle. The diel amplitude is about 46% of the expected daily mean. At both Simcoe and Madison, the expected daily power above an ice‐free lake attains a broad maximum of 12–14 × 105 ergs·cm−2·d−1 in winter and early spring, drops sharply in late April, and shows a broad summer minimum of 3–4 × 105 ergs·cm−2·d−1 during July–August. The autocorrelation functions for both spring windpower and daily insolation show evidences of periodicity of about 7 days, probably related to synoptic‐scale cold front passages. Following the front, with its characteristic wind directional shift from SSW to NNW, a characteristic calm develops accompanied by intense solar radiation.

The spring power histogram features a median value about half of the mean, because of the high probability of observing very low windpower coupled with a very long tail on the frequency distribution. Low power also shows a strong clustering tendency in spring, because of both the strong inversion conditions in that season and the period of about 7 days in the synoptic‐scale weather shifts.
Role of advective terms in tidally generated residual circulation
Authors: T. S. Murty , F. G. Barber , J. D. Taylor
Published: March 2010

Through the use of a numerical model, the role of the nonlinear advective terms in tidally generated residual circulation is explicitly demonstrated. This type of motion has been neglected in computations of dispersion and spreading of surface contaminants.
Growth cycles and nutrient‐limited photosynthesis in phytoplankton1
Authors: Stross R. G.
Published: March 2010

Net plankton, nannoplankton, and three individual species from Lake George, New York, were tested for nutrient limitation. Short term measurements of 14C uptake at light saturation, combined with pre‐enrichment, revealed a time‐of‐day dependence for the demonstration of nutrient‐limited rates of photosynthesis. Enrichment with phosphate not later than the early night of day 0 increased photosynthetic capacity of the assemblage on the day following. The net plankton was more responsive and reacted to phosphate only. The three individual species were most responsive. The time specificity in reaction to, and effectiveness of, enrichment is interpreted as further evidence of endogenously regulated daily cycles of growth in phytoplankton.
Detection of prey by Calanus pacificus: Implications of the first antennae1
Authors: Landry M. R.
Published: March 2010

Calanus pacificus, normally regarded as a passive filter‐feeding copepod, displays active predatory behavior when fed with copepod nauplii. Larger nauplii are selectively preyed upon, even though they are better able to avoid capture than small nauplii. The involvement of the first antennae in the remote detection of motile prey is suggested by the experimental result that amputation of the antennae sharply reduces predatory feeding rates without affecting filter feeding.
The relationship between egg size and naupliar size in the calanoid copepod Diaptomus clavipes Schacht1,2
Authors: Cooney John D. , Gehrs Carl W.
Published: March 2010

A direct positive relationship was demonstrated between egg size and naupliar size in the calanoid copepod Diaptomus clavipes Schacht. Number of eggs per clutch and total clutch volume were inversely associated with measures of egg and naupliar size (egg volume, maximum egg length, naupliar volume, and maximum naupliar length). Thus, small clutches with large eggs give rise to large nauplii.
Fluorescence: absorbance ratios—a molecular‐weight tracer of dissolved organic matter1
Authors: Stewart Arthur J. , Wetzel Robert G.
Published: March 2010

Naturally occurring dissolved humic materials were fractionated according to molecular weight by dialysis and gel permeation chromatography. Components of higher molecular weight (>3,500) absorbed strongly at 250 nm but fluoresced weakly, while humic fractions of lower molecular weight fluoresced intensely per unit absorbance. With appropriate precautions, fluorescence: absorbance ratios may be useful in delineating seasonal and depth distribution patterns of dissolved humic materials of low and high molecular weight.
Analysis of organic carbon in marine sediments1
Authors: P. N. Froelich
Published: March 2010

A method is presented for measuring organic carbon in both carbonate‐rich and carbonate‐poor marine sediments. Samples are sonicated with phosphoric acid to remove carbonates. The spent acid supernatant is analyzed for dissolved organic carbon, the solid residue for total carbon; their sum yields the organic carbon content of the sample. The technique is free from carbonate interferences, involves no losses due to acid solubilization, and has excellent precision (better than ±0.02% Corg) and accuracy (better than ±2%).
A sampler for cohesive sediment in the benthic boundary layer1
Authors: Bryant R. , Williams D. J. A. , James A. E.
Published: March 2010

A sampling apparatus for collecting sediment suspensions from the benthic boundary layer has been developed and tested. Samples are collected in evacuated pressure‐resistant bottles by activation of solenoid valves used to release the vacuum. The behavior of the apparatus with respect to water velocity is assessed from direction and inclinometer sensors attached to its main frame. The apparatus has been tested at a depth of 30 m in the Bristol Channel in water velocities of 1–2 m·s−1. Profiles of suspended sediment in the boundary layer are derived from gravimetric analysis of the samples collected.
Release and cycling of nutrients between planktonic algae and herbivores1
Authors: Lehman John T.
Published: March 2010

Efforts to quantify nutrient release by zooplankton in situ are usually complicated by simultaneous uptake of the nutrients by phytoplankton. Either separating the animals from their food or severely concentrating the zooplankton assemblage before measuring nutrient release introduces biases. Results are reported from experimen ts in which uptake and regeneration of nutrients were measured simultaneously in an intact alga‐herbivore assemblage. Short term responses to perturbations of both nutrients and zooplankton were followed and grazing rates as well as the nutrient fluxes quantified. Magnitudes of uptake and recycling depend on the nutritional status of the algal cells, with nutrient‐deficient cells displaying faster rates of uptake and lower rates of remineralization than nutrient‐sufficient cells for both phosphate and ammonia. The recycled nutrients are rapidly sequestered by the algae and contribute substantially to growth rates of the cells.
Aggregation of organic matter by pelagic tunicates1
Authors: Pomeroy Lawrence R. , Deibel Don
Published: March 2010

Three genera of pelagic tunicates were fed concentrates of natural seston and an axenic diatom culture. Fresh and up to 4‐day‐old feces resemble flocculent organic aggregates containing populations of microorganisms, as described from highly productive parts of the ocean, and older feces resemble the nearly sterile flocculent aggregates which are ubiquitous in surface waters. Fresh feces consist of partially digested phytoplankton and other inclusions in an amorphous gelatinous matrix. After 18–36 h, a population of large bacteria develops in the matrix and in some of the remains of phytoplankton contained in the feces. From 48–96 h, protozoan populations arise which consume the bacteria and sometimes the remains of the phytoplankton in the feces. Thereafter only a sparse population of microorganisms remains, and the particles begin to fragment. Water samples taken in or below dense populations of salps and doliolids contained greater numbers of flocculent aggregates than did samples from adjacent stations.
The concentration and isotopic fractionation of gases dissolved in freshwater in equilibrium with the atmosphere. 1. Oxygen
Authors: Benson Bruce B. , Krause Daniel
Published: March 2010

Equations and tables are presented from which accurate values can be obtained, in any of several sets of units, for the concentration of oxygen dissolved in freshwater in equilibrium with the atmosphere from 0° to 40°C and 0.5 to 1.1 atm. The y are based on values for the Henry coefficient of oxygen, ko, which have an estimated accuracy of 0.02%. Equations are derived which relate ko to equilibrium concentrations in natural waters. The equations include corrections for molecular interactions in the vapor phase. Uncertainty about the best way to correct for these interactions limits the estimated accurracy of the derived values to about ± 0.07% at 0°C and 0.04% at 40°C, but the new results are much more accurate than values from the UNESCO tables. Within their random errors, previous measurements agree very well with the new results. Under equilibrium conditions, and between 0° and 60°C, the per mil difference between the 34O2:32O2 abundance ratio in the dissolved gas and the air is given by δ = −0.730 + (427/T), where T is in kelvin and the standard deviation is <0.02‰.
The areal hypolimnetic oxygen deficit: An empirical test of the model1
Authors: Cornett R. J. , Rigler F. H.
Published: March 2010

The areal hypolimnetic oxygen deficit (AHOD) model was tested by examining the relationship between rates of hypolimnetic oxygen depletion and three measures of lake trophic status. Measurements of AHOD were positively correlated with the measured total phosphorus concentration and with annual 14C pelagic primary production and inversely correlated with mean summer Secchi depth. Because each of the correlations between AHOD and trophic status explained <45% of the observed variation in A HOD values, other factors must also influence the AHOD of a lake. Significant amounts of the residual variation were explained by including the mean depth of the lake and mean hypolimnetic temperature as additional independent variables in a multiple regression analysis. A lake with a thicker or warmer hypolimnion had a higher AHOD than a lake with a shallow or colder hypolimnion. The AHOD model was developed to eliminate the influence o f lake morphometry on interlake comparisons of hypolimnetic oxygen depletion, but it does not do this and a new model must be developed.