bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent changes in molluscan species diversity of a large tropical lake (Lago de Peten, Guatemala)1
Authors: Covich Alan
Published: March 2010

The relative and absolute shifts in abundance of five species of freshwater gastropods appear to reflect widespread changes in the drainage basin around Lago de Peten. Fluctuations in the number of shells deposited in 3.7 m of lake sediments are not directly correlated with changes in preserved organic matter or major cations (calcium, magnesium, and sodium), but some long term trends are documented. Two types of changes in molluscan species composition occur: abrupt oscillations in the numbers of individuals in two species (Tryonia exigua and Cochliopina infundibulum) and gradual increases in three others (Pyrgophorus coronatus, Biomphalaria havanensis, and Stenophysa spiculata). Mechanisms producing these changes appear to be major fluctuations in nutrient inflow and sedimentation rates. These factors probably influence competitive interactions among the gastropods; indirect effects may have altered vulnerability of the mollusca to predators. The controlling variable for nutrient inflow and rates of siltation seems to be extensive deforestation by ancient and modern Mayan agriculturalists.
Primary production, standing stock, and export of organic matter in a Mohave Desert thermal stream1
Authors: Naiman Robert J.
Published: March 2010

The water of a thermal artesian stream (Tecopa Bore) in the Mohave Desert near Death Valley, California, issues from the ground at 47.5°C and cools 8–12°C before leaving a study area 300 m long. Growth occurs year round because of the high water temperature. Pupfish are the dominant herbivores; acquatic invertebrates are rare.

The 11,065 kcal m−2 annual input of energy to the biological system is totally accounted for by autochthonous primary production. About 718 kcal m−2 of organic matter is stored within the system in the form of algal mats and detritus and has a turnover time of about 23 days. The bulk of the annual primary production (81%) is channeled into respiration and decomposers; 9% is lost as dissolved organic carbon and 4% as drift of particulate organic matter. Pupfish (Cyprinodon nevadensis amargosae) feed on algae and detritus, ingesting 17% (1,878 kcal m−2 yr−1) of the annual primary production, of which 119 kcal m−2 yr−1 is deposited in growth.
Alkalinity changes generated by phytoplankton growth1
Authors: Brewer Peter G. , Goldman Joel C.
Published: March 2010

Continuous cultures of three marine phytoplankton species, Phaeodactylum tricornutum, Dunaliella tertiolecta, and Monochrysis lutheri, were monitored for changes in alkalinity of the culture medium resulting from NO3− and NH4+ uptake. Uptake of NO3− caused an increase in alkalinity, whereas uptake of NH4+ produced a decrease. These results are consistent with the type of schematic equation proposed by Redfield, Ketchum, and Richards for photosynthetic assimilation of inorganic nitrogen, in which NO3− uptake is balanced by OH− production and NH4+ uptake leads to H+ generation. These reactions suggest active uptake of nitrogen species by microbes. We have been unable to demonstrate the exact stoichiometry of this relationship, and the role of P uptake in the alkalinity change is unclear. An offset in the data, functionally equivalent to the production of some strong acid, may be due to reactions on the walls of the vessel, active uptake of cations, or extrusion of H+ ions by the growing cells.
Hamilton Harbor: Periodicities of the physicochemical process
Authors: Palmer Mew D. , Poulton Donald J.
Published: March 2010

The dynamics of water motion in the Burlington Ship Canal and Hamilton Harbor at the western end of Lake Ontario have been studied with digitally recording meters for current, pH, O2, and conductivity. Water movements and chemistry were strongly influenced by lake and harbor oscillations which produced temporary displacements of the thermocline in both the harbor and canal due to internal waves, along with complex flow regimes including two‐ and three‐layer systems in the canal.

Mean mass exchanges in the ship canal were 11 × 104 kg s−1 in each direction. This mass exchange is important in maintaining harbor water quality and providing the necessary dissolved oxygen.
The secretion of lipids by the freshwater phytoflagellate Ochromonas danica1,2
Authors: Billmire E. , Aaronson S.
Published: March 2010

Ochromonas danica secretes lipids into its culture medium equal to about 8% of the cellular dry weight. About two‐thirds of the secreted lipid is neutral lipid made up of an unknown, sterols, free fatty acids, pigments, and sterol esters in diminishing quantity; a third is complex lipid including sulfolipids, glycolipids, and phosphatides in diminishing quantity. The predominant fatty acids secreted are C16 : 0, C18 : 0, C18 : 1.
Contribution of bacteria to standing crop of coastal plankton1
Authors: Ferguson R. L. , Rublee P.
Published: March 2010

Water samples were collected from coastal waters near Cape Lookout, N.C., during March 1975 for direct count of bacteria and for adenosine triphosphate (ATP) analysis. Bacteria averaged 6.6 × 105 cells ml−1 and 0.09 µ3 cell−1. Bacterial carbon was 4 to 25% of the ATP estimate of total plankton carbon.
Difficulties with ATP measurements in inshore waters1
Authors: Sutcliffe W. H. , Orr E. A. , Holm‐Hansen O.
Published: March 2010

When inshore waters are filtered for microbial biomass determinations, the amount of ATP recovered in the extracts is directly proportional to the volume filtered up to about 0.5 liter. With sample volumes of 1–3 liters, there is an apparent loss of ATP which can amount to 10–50% of that originally present. This loss is not due to cell lysis during filtration, but rather seems related to adsorption phenomena associated with the load of detrital or sedimentary material in suspension. When working in inshore waters it is therefore advisable to determine if such an inflection point occurs for ATP loss and to use smaller sample volumes if necessary to ensure against any loss of ATP. There is no such loss of ATP from open ocean samples.
Inorganic nitrogen uptake by marine phytoplankton under in situ and simulated in situ incubation conditions: Results from the northwest African upwelling region1
Authors: Slawyk G. , MacIsaac J. J. , Dugdale R. C.
Published: March 2010

Ammonium and nitrate uptake by euphotic zone populations of marine phytoplankton were compared under in situ and simulated in situ incubation conditions. The in situ values from all depths were generally higher than those from deck incubators, but the source of the difference was not identified.
Acetylene reduction by coral skeletons
Authors: Crossland C. J. , Barnes D. J.
Published: March 2010

Acetylene reduction was measured in coral tissues, coral skeletons, and reef sediments. Light‐stimulated acetylene reduction activity was associated with the skeleton rather than coral tissues or surface macroalgae. Activity in fine sediments was little affected by light.
Recovery of 14C‐CO2 at high flow rates from a CHN analyzer1
Authors: Taft J. L.
Published: March 2010

A simple method is described for efficiently absorbing 14C‐CO2 from helium carrier gas flowing at rates up to 1 liter min−1. The CO2 trap can be coupled to a CHN analyzer to recover organic 14C from freeze‐dried seawater.
A free vehicle for measuring benthic community metabolism1
Authors: Smith K. L. , Clifford C. H. , Eliason A. H. , Walden B. , Rowe G. T. , Teal J. M.
Published: March 2010

A free vehicle respirometer (FVR) which measures the oxygen consumption of benthic communities in situ to abyssal depths consists of a structural aluminum tripod supporting a two‐command acoustic release‐transponder, an oxygen monitoring unit, a glass sphere flotation array, and a time lapse camera system. An acoustic signal actuates the first command mode. This releases the oxygen monitoring unit. Settlement is monitored by the camera system. After measurements lasting 1 to 5 days, the second acoustic command releases the descent weight, and the free vehicle is brought to the surface by the flotation array and recovered.

Preliminary results obtained with the FVR at 5,200 in in the northwest Atlantic suggest that benthic community respiration decreases three orders of magnitude from values measured at shallow shelf depths.
A bottom sediment trap for recent sedimentary deposits1
Authors: Hakanson Lars
Published: March 2010

A bottom trap for collection of recent sedimentary deposits has been constructed and field tested. The technique provides material, deposited within a known time span, unaffected by bioturbation in the upper biologically active sediment layer. The trap has an area of 1,541 cm2 and an edge height of 5 cm. Before retrieval, a lid is lowered onto the trap. The apparatus is easy to handle and has yielded representative values for the rate of deposition.
Effects of light and ammonium on nitrate uptake by two species of estuarine phytoplankton
Authors: Bates Stephen S.
Published: March 2010

The incident light intensity, preconditioning light history, and the presence or absence of ammonium affected the rate of nitrate uptake by a chlorophyte and Skeletonema costatum isolated from the Hudson estuary. In the absence of ammonium, shade‐adapted cells reached the highest maximum velocity of nitrate uptake (Vmax). Skeletonema costatum had a lower half‐saturation constant for light (KLT) than the chlorophyte and reached a greater Vmax. In the presence of ammonium, nitrate uptake was depressed at all light intensities, but more in shade‐adapted than in sun‐adapted cells of both species, and more in S. costatum than in the chlorophyte. The Vmax for ammonium was greater in shade‐adapted than in sun‐adapted cells. Since nitrate and ammonium uptake were related to the Chl a content of the cell, energy for uptake was probably derived primarily from photosynthesis in the light but may also be derived from respiration since substantial dark uptake was observed, especially in S. costatum.
ATP in Lake Kinneret: Indicator of microbial biomass or of phosphorus deficiency?1
Authors: Cavari Benzion
Published: March 2010

The C : ATP ratio in Lake Kinneret water fluctuates from 200 : 1 to 5,000 : 1. The most dramatic variations of the ratio were observed during the bloom of Peridinium in the lake (February to May). Moreover, the ratio showed large changes with depth: it is maximal in the upper 2 m and declines rapidly below this layer. During the rest of the year, the ratio approaches the common value of 250 : 1. Complementary experiments on P‐starved Peridinium cells suggest that the high in situ values of the ratio during the bloom are related to low amounts of phosphorus available in the lake. However, these high values do not signal the end of the Peridinium bloom which, in the cycle observed, persisted 3 months after the highest measured value of the ratio. The data raise the possibility of using ATP determination as an indication of nutrient limitation in the natural aquatic environment. In addition, they confirm that ATP determination can serve as an assay for bacterial biomass determination in the hypolimnion where almost no phytoplankton or zooplankton exist.
Vertical distribution of sulfur species in benthic algal mats1
Authors: Doemel William N. , Brock Thomas D.
Published: March 2010

Methods are described for measuring the concentration and vertical distribution of sulfide, elemental sulfur, and sulfate in benthic mats consisting of blue‐green algae and photosynthetic bacteria. For visualizing microzonation of sulfide production, cores of the mat are placed in ferrous ammonium sulfate agar and incubated for 24 h. Zones of sulfide production are then revealed as black bands of ferrous sulfide of varying thickness. For quantitative measurement, cores are cut into segments, extracted, and assayed by colorimetric methods. Sulfide formation never occurs in the top 3 mm of the mat and occurs mainly in a thick rather diffuse zone between about 3–10 mm, below which extremely thin laminae of sulfide production are seen. The techniques reported should have wider utility and are especially useful in revealing location of reducing conditions within stratified mats.
Production and dynamics of experimentally enriched salt marsh vegetation: Belowground biomass1
Authors: Valiela Ivan , Teal John M. , Persson Norma Y.
Published: March 2010

Root growth increased during the early growing season in Spartina alterniflora salt marsh plots. While fertilization with nitrogenous fertilizer did not affect initial growth, a marked decrease in root biomass followed the spring peak particularly where nutrient doses were highest. A sharp reduction in roots occurred in enriched areas covered by Spartina patens, although, as with S. alterniflora, aboveground biomass increased. Roots disappeared during autumn leaving rhizomes as the only part of the plants to overwinter. The maximum standing crop for roots was 0–2 cm deep, for rhizomes 2–5 cm. Net annual underground production was calculated from annual increments in dead matter belowground. Total production, underground and aboveground, exceeds that of any marine vegetation, ranging from 3,900 to 6,600 g m‒2 yr‒1 in S. alterniflora areas and 3,200 to 6,200 g m‒2 yr‒1 in S. patens areas. Fertilization increased production particularly aboveground where dead plant parts are subject to export.
Airborne litterfall as a source of organic matter in lakes1
Authors: Gasith A. , Hosier A. D.
Published: March 2010

An evaluation of the importance of airborne litterfall as a source of organic matter in lakes is suggested, based on tho input of the airborne litterfall relative to the contribution from autochthonous primary production and the ratio of the shoreline to the lake area. The results suggest that airborne litterfall could be important (at least 10% of phytoplankton production) in oligotrophic and very small eutrophic lakes. This evaluation may be useful in studies of organic matter budgets of aquatic systems to indicate whether airborne litterfall may be potentially important as a source of carbon and should be directly measured.
Uranium and thorium decay series nuclides in plankton from the Caribbean1
Authors: Kharkar D. P. , Thomson J. , Turekian K. K. , Forster W. O.
Published: March 2010

Zooplankton (predominantly calanoids and cyclopoids) from the Caribbean were analyzed for 238U, 234U, 232Th, 228Th, 228Ra, 226Ra, 210Pb, and 210Po. The concentration factor in the zooplankton relative to seawater is highest for 210Po. 210Pb and 228Th have similar concentration factors and are comparable (when normalized to 226Ra) to reported fiber‐scavenging experimental data on 210Pb and 234Th. The dominant transport agent for 210Po and 210Pb from the mixed layer to depth cannot be unmodified zooplankton debris.
Particle‐size modification by two size classes of the estuarine copepod Acartia clausi1,2
Authors: O'Connors Harold B. , Small Lawrence F. , Donaghay Percy L.
Published: March 2010

Two distinct size classes of Acartia clausi were allowed to graze on two different‐sized species of the chain‐forming diatom Thalassiosira. Both copepod size classes dismembered the larger T. gravida chains, producing a high frequency of smaller particles when T. gravida was in high concentrations. In low particle concentrations of T. gravida, the production of small particles was obscured by ingestion. Some particle dismembering might have occurred with the smaller T. nordenskioldii, but the effect also was masked by ingestion. Such particle modification might require a re‐examination of past grazing data.

Particle volume ingestion was plotted as a function of particle volume concentration. At high particle densities, both large and small A. clausi could ingest greater volumes of the large T. gravida particles than the smaller T. nordenskioldii particles. At low particle volume densities, both size classes of copepod ingested similar volumes of both diatoms. Large A. clausi ingested greater food volume than small A. clausi, except at the very lowest food volume density (where ingestion was similar). Great variability in the ingestion data occurred as a result of copepod collections in different seasons of different years, and the use of single grazing coefficients is discussed in the light of this variability.
Accommodation of Daphnia pulex to altered pH conditions as measured by feeding rate1
Authors: Kring R. Lynn , O'Brien W. John
Published: March 2010

The maximal feeding rate of cladoceran populations occurs at or near the temperature and pH at which the animals were raised, suggesting that cladocerans may be able to alter their maximal feeding rates upon prolonged exposure to different conditions. Feeding rates of a population of Daphnia pulex collected from water of pH 7.7 to 7.9 and cultured in water of the same pH and pH 6.5 to 6.6 were measured over a wide range of pH conditions. Within 6 weeks to 2 months of exposure to the lowered pH, the population was able to feed maximally at the new pH.
Dissolved fatty acids in seawater from a fringing reef and a barrier reef at Grand Cayman1
Authors: Meyers Philip A.
Published: March 2010

The concentration of dissolved fatty acids decreased in seawater as it flowed across a windward barrier reef at Grand Cayman. No comparable changes were observed over a leeward fringing reef although an increasingly enriched organic surface layer could be detected as distance from shore increased.
The design and evaluation of a measurement system for photosynthetically active quantum scalar irradiance1
Authors: Booth Charles R.
Published: March 2010

An instrument system has been developed to measure photosynthetically active quantum scalar irradiance, the number of photosynthetically active photons arriving at a point from all directions. One instrument in the system is designed to measure vertical profiles in the ocean, one to monitor solar radiation for reference purposes, and one to measure quantum scalar irradiance in laboratory incubators. A method of evaluating the performance of light measuring instruments and estimating the errors in actual field use is described and applied to these instruments and also to instruments in common use.
Grazing in Lake Erken
Authors: Cushing D. H.
Published: March 2010

The seasonal cycles of plants, animals, detritus, and nutrients have been studied in Lake Erken in Sweden by Nauwerck and Pechlaner. The animal populations are heavier by weight than the algal populations by a factor of about five. Both investigators have suggested that the animals do not control the algal populations; Nauwerck suggests that the copepods, at least, subsist on bacteria and detritus. This paper attempts to show that the algae are controlled by the grazing animals and that the proportions by weight are those expected.
Factors controlling methane oxidation in shield lakes: The role of nitrogen fixation and oxygen concentration1
Authors: Rudd John W. M. , Furutani Akira , Flett R. J. , Hamilton R. D.
Published: March 2010

During summer stratification methane‐oxidizing bacteria in Lake 227 are confined to a narrow zone within the thermocline because of their sensitivity to high epilimnetic oxygen concentrations. This oxygen sensitivity is based on the dependence of the oxidizers on an oxygen‐sensitive nitrogen fixation process. Thus epilimnetic methane oxidation is absent during periods of nitrogen limitation, since high epilimnetic oxygen concentrations prevent nitrogen fixation. During periods of overturn and throughout the winter, the methane oxidizers become oxygen insensitive and oxidation occurs rapidly throughout the water column. This oxygen insensitivity likely occurs as a result of high in situ concentrations of dissolved inorganic nitrogen, which replaces nitrogen fixation as a source for fixed nitrogen. Under ice‐cover, rapid methane oxidation throughout the water column can be a major cause of total anoxia.
An analysis of the horizontal regime of denitrification in the eastern tropical North Pacific1
Authors: Codispoti L. A. , Richards F. A.
Published: March 2010

A method using isentropic analysis to estimate nitrate removals by denitrification in the oxygen deficient waters of the eastern tropical North Pacific agreed reasonably well with a technique based on vertical distributions. Dynamic computations permitted an estimate of the horizontal advective transport of these nitrate deficits out of the study region; such transport was a large fraction of the total, indicating that horizontal processes are important.

The horizontal transports used in combination with estimates for vertical losses and horizontal diffusive losses yielded a denitrification rate of ⋍2 × 1013 g N yr‒1 for the portion of the eastern tropical North Pacific east of ⋍112°W. This value was in good agreement with estimates based on the application of respiration rates to the appropriate volumes of oxygen deficient water and with an estimate based on a vertical model.
Observations of the California Undercurrent off Washington and Vancouver Island
Authors: Reed R. K. , Halpern D.
Published: March 2010

A detailed oceanographic survey was conducted in the Pacific off the coast of Washington and Vancouver Island in September 1973, and 12‐h time‐series measurements were made at eight sites. Data from the time‐series stations suggest the presence of semidiurnal internal tidal waves seaward of the continental shelf. The resulting disturbances to the geopotential anomalies, however, had little effect on the derived patterns of geostrophic flow. During this survey, the surface flow relative to 1,000 db was generally southward, but a northward flow was present at intermediate depths along the continental slope. This northward flow appears to be an extension of the California Undercurrent, which remains an identifiable feature to at least 49°N but weakens along its path by mixing with adjacent water. An additional northward flow in the northern part of the area resulted from a cyclonic eddylike feature.
Upwelling near Samalga Pass1
Authors: Swift James H. , Aagaard Knut
Published: March 2010

Recent summer hydrographic data from the vicinity of Samalga Pass in the eastern Aleutians show upwelling of relatively saline water, poor in oxygen and rich in nutrients. A steady state oxygen model in which the photosynthetic production of oxygen in the euphotic zone is balanced by an upwelling of low‐oxygen water yields an upper bound on the vertical velocity of 7 × 10‒3 cm s‒1. Examination of various possible driving mechanisms for the upwelling, including winds and entrainment, suggests that the upwelling is driven by subsurface convergence.
Silicic acid uptake and incorporation by natural marine phytoplankton populations1
Authors: Azam F. , Chisholm S. W.
Published: March 2010

68Ge‐germanic acid was used as a tracer to study the uptake and incorporation of silicic acid by natural phytoplankton populations in the Gulf of California. The technique was useful in measuring silicic acid incorporation rates as low as 0.5 nM h‒1. The incorporation followed saturation kinetics. Ks values at two stations were 1.59 and 2.53 µM. The incorporation was light dependent, maximum rates being achieved at 0.28 × 1021 photons cm‒2 d‒1 (0.044 ly min‒1; 9% of surface irradiance) and half‐maximum rate at 0.02 × 1021 photons cm‒2 d‒1 (0.003 ly min‒1; 0.6% of surface irradiance); rate of incorporation in the dark was 44% of that at light saturation. Enrichment with silicic acid caused stimulation of photosynthetic carbon fixation at two stations.
The fate of “dissolved” organic carbon derived from autumn‐shed maple leaves (Acer saccharum) in a temperate hard‐water stream1
Authors: Maurice A. Lock , H. B. N. Ilynes
Published: March 2010

A freeze‐dried autumn leaf leachate of maple (Acer saccharum) was prepared and its decomposition in hard water (⋍90 mg Ca liter‒1 and in hard water overlying freshly collected stream sediments was examined. In water alone there was very little change in the leachate levels measured as “dissolved” organic carbon (DOC); in water over sediments the leachate level was reduced to 15% of the initial level in 1 day. Rates of leachate removal during the first 9 h from water over sediments in July and October 1974 were not significantly different. Also, there was no increase in the rate of leachate removal after repeated additions of leachate. A Tyndalization sterilization technique was used to estimate the extent of removal of leachate by the sediment microflora. It appeared that at least 40% and possibly as much as 100% of the removal was a biotic process.
Nonliving organic particle formation from bubble dissolution1
Authors: Johnson Bruce D.
Published: March 2010

Particles are formed by bubble dissolution in filtered seawater, as demonstrated by photographs and by particulate organic analysis. The dissolution of large numbers of small bubbles in the ocean suggests that particles produced from these dissolving bubbles may constitute a significant fraction of the nonliving organic particulate matter present.
Respiration and photosynthesis during resting cell formation in Amphora coffeaeformis (Ag.) Kutz.1
Authors: Anderson O. Roger
Published: March 2010

Changes in respiratory and photosynthetic rates were correlated with previous research on resting cell cytology and cytochemistry. Resting cells possess a contracted mass of granular cytoplasm within an unmodified frustule. Although the respiration rate of resting cells is less than 20% of that in light‐grown cells, cytochrome oxidase activity is reduced to about 80%. Therefore, respiratory rate decline cannot be attributed to a decrease in available cytochrome oxidase. Photosynthesis rapidly declines during the first week of resting cell formation. The survival value of these mechanisms is discussed.
Temperature responses of a coccolithophorid, Cricosphaera carterae, measured in a simple and inexpensive thermal‐gradient device1
Authors: Blankley William F. , Lewin Ralph A.
Published: March 2010

An illuminated thermal‐gradient device is described which is of simple construction, very low cost, and wide adaptability to various culture vessels. It can be readily adapted for use in crossed gradients with temperature along one axis. The thermal gradient produced depends on several factors including the heat source (one or more incandescent lamps), heat sink (cold air in a refrigerated box or room), and type of culture vessel. By use of the device, the temperature range for growth of Cricosphaera carterae was found to be 10–26°C, with a maximal growth rate at 20°C.
Quantitative estimation of bacteriochlorophyll c in the presence of chlorophyll a in aquatic environments1
Authors: Madigan Michael T. , Brock Thomas D.
Published: March 2010

A method is described which enables the individual quantification of chlorophyll a and bacteriochlorophyll c when the two are present in a mixture. The method involves the use of thin‐layer chromatography to first separate the pigments, followed by the standard spectrophotometric assays of the isolated chlorophylls. The method is readily adaptable to field studies, rapid, and relatively inexpensive.
Comparison of 137Cs concentrations measured after in situ absorption with those determined by bulk water analyses or calculated from 90Sr analyses1
Authors: Kupferman Stuart L. , Bowen Vaughan T.
Published: March 2010

Concentrations of 90Sr and 137Csence between analyses performed by the two methods appears to be close to 0.6 dpm per 100 liters. determined at Woods Hole Oceanographic Institution by bulk water analysis were compared with 137Cs concentrations determined at the University of Delaware following absorption in situ. Five groups of profiles from the North Atlantic were used. Bulk water values and in situ values were compared by plotting radioisotope concentrations against στ and comparing values, obtained by linear interpolation, at the same values of στ. When compared with mean analytical uncertainties, data obtained by the two methods seem in excellent agreement. The systematic differ
The extraction and measurement of adenosine triphosphate from marine sediments1
Authors: Bancroft K. , Paul E. A. , Wiehe W. J.
Published: March 2010

A technique has been developed, using boiling sodium bicarbonate buffer, to extract adenosine triphosphate (ATP) from marine sediments and has been tested on a variety of sediments, including those with high organic content, clay, and carbonate. Recovery of ATP, as measured by the addition of bacteria of known ATP content to sediment, varied from 64–100%. The technique also was as effective as the conventional Tris buffer for extraction of ATP from both pure cultures of bacteria grown in broth and natural seawater samples.
Emission of sulfur from Lake Ontario sediments
Authors: Nriagu J. O. , Coker R. D.
Published: March 2010

Calculations indicate that about 6.0 × 105 kg of sulfur is released annually from Lake Ontario sediments. This constitutes about 1% of the annual sulfur input into the sediments and is insignificant compared to the total sulfur that cycles annually through the lake. The sulfur released from the sediments is enriched in 32S with the result that the sulfur in the historical layers is characterized by high δ34S values.
Model of copepod filtering response to changes in size and concentration of food1
Authors: Lam Ronald K. , Frost Bruce W.
Published: March 2010

Observations indicate that there are three phases in the feeding response of adult females of Calanus pacificus to differences in food concentration. At low concentrations of food, the copepods filter at some reduced rate. As the food supply is increased, the animals increase their filtration rate until some maximum rate is reached. They then maintain this maximum rate until a critical food density is exceeded, at which point the copepods decrease their filtering rate (hold a constant ingestion rate) with further increases in food concentration. A model based on simple arguments concerning the net rate of energy gain to a filter feeder is constructed which predicts functional dependencies of the filtering rate on food concentration for three regions, corresponding to the three phases of feeding behavior observed. The parameters controlling the filtering response in the model are functions of the animal’s characteristic length and the size of the food particles.
The filter‐feeder as an optimal forager, and the predicted shapes of feeding curves
Authors: Lehman John T.
Published: March 2010

If a filter‐feeder is assumed to maximize the net rate of energy gained from its food, then the theoretically predicted relations between filtering r.ate, ingestion rate, and the abundance of food agree with empirical models at high concentrations of food cells, but not at low particle densities where experimental results are scarce. A general model is derived for filter‐feeding behavior in mixtures of particle types and is used to evaluate selective ingestion of particles based on their comparative abundances, sizes, and digestibilities. Filter‐feeders are predicted to harvest optimally in a mixture if their rates of ingestion are maximal for particles slightly larger than those most numerous in the mixture. Conditions which could lead to the passage of viable cells of some species of algae through the gut of a filter‐feeder are examined.
The relationship between the diurnal movements of some of the zooplankton and the sardine Limnothrissa miodon in Lake Kariba, Rhodesia1
Authors: Begg G. W.
Published: March 2010

The numbers of zooplankton at the surface in the open waters of Lake Kariba increased at night. Of the dominant species, the most extensive migrations were shown by adults of Mesocyclops leuckartii; their nauplii did not show any distinct diurnal movements. Bosmina longirostris exhibited similar, but lesser, movements. Keratella tropica, Keratella cochlearis, and Trichocerca chattoni remained more or less static in the epilimnion throughout the study.

For some months after turnover, certain zooplankters move from the floor of the lake to the surface (60 m) each day. When temperature stratification in the monomictic lake intensifies and the hypolimnion becomes devoid of oxygen, these migrations are limited to the depth of the thermocline.

These movements are similar to those of the Tanganyika sardine Limnothrissa miodon.
Mathematical formulation of the relationship between photosynthesis and light for phytoplankton
Authors: Jassby Alan D. , Platt Trevor
Published: March 2010

Eight different mathematical formulations of the photosynthesis—light curve for phytoplankton (up to and including light saturation) were recast in terms of the same two parameters: the initial slope α, and the assimilation number PmB. Each equation was tested for its ability to describe empirical data from natural populations of marine phytoplankton: the results of 188 light‐saturation experiments at three coastal locations in Nova Scotia over a 2‐year period. The most consistently useful mathematical representation of the data was found to be the hyperbolic tangent function.
Chemical and biological characteristics of a water column in Lake Tahoe1
Authors: Holm‐Hamen O. , Goldman C. R. , Richards R. , Williams P. M.
Published: March 2010

A central station in Lake Tahoe has been sampled from the surface to 400 m at four times of year for measurement of phytoplankton biomass; particulate and dissolved organic carbon, nitrogen, and phosphorus; inorganic nutrients; primary productivity; and light, temperature, and oxygen.

The gradients observed in distribution of dissolved and particulate material from the surface to 400 m did not vary greatly from summer to winter, even though the water temperature at the February sampling time was almost isothermal. When the water in Tahoe undergoes a winter overturn, biological activity in the lake soon returns the water column to the distinct vertical profiles of inorganic and organic material reported here.
Organic matter losses from four watersheds in the humid tropics1
Authors: Brinson Mark M.
Published: March 2010

Organic matter (OM) losses in runoff water were examined for four watersheds in Guatemala, ranging in size between 170 and 5,247 km2. Total organic matter (TOM) concentrations for the largest river were highest (14.8–19.3 mg liter‒1) at the beginning of the wet season, due to an abrupt increase in particulate fractions. This initial flushing effect was followed by lower concentrations which had decreased to near dry season values (3.90–5.35 mg TOM liter‒1) 4 months later. Export of TOM was estimated to be between 5.4 and 12 g m‒2 yr‒1 for three of the four watersheds. The fourth, dominated by swamp forest, showed a higher maximum concentration (43.7 mg TOM liter‒1) and greater export, the latter partially attributable to flushing by floodwaters that overflowed an adjacent watershed. These data and those from studies in higher latitudes suggest a direct relationship between the quantity of TOM exported and runoff volume per unit area of watershed. A plausible explanation is that dissolved OM is the major form of OM in most running waters and varies less in magnitude than hydrologic runoff from one watershed to another.
Track autoradiography: A method for the determination of phytoplankton species productivity
Authors: Knoechel R. , Kalff J.
Published: March 2010

Track autoradiography permits quantitative determination of 14C fixation rates of individual phytoplankton species within natural communities following in situ incubations. Rates measured are comparable with those obtained by liquid scintillation counting. Procedures are described and an example of field results is presented.
The measurement of temperature tolerance: Verification of an index
Authors: Bradley Brian P.
Published: March 2010

A shock‐recovery assay for temperature tolerance is demonstrated to predict survival of the copepod Eurytemora affinis at high temperature. The assay can be modified to allow comparison between widely divergent treatment groups.
Bioluminescence in McMurdo Sound, Antarctica1
Authors: Raymond James A. , DeVries Arthur L.
Published: March 2010

McMurdo Sound is inhabited by a number of bioluminescent organisms not previously described as bioluminescent. A dinoflagellate, two ostracods, a copepod, fish fecal pellets probably illuminated by bacteria, four polychaetes, a brittle star, a euphausiid, and a sponge illuminated by dinoflagellates are described. The dinoflagellate luminescence appeared to have a seasonal but not a circadian rhythm.
Field determination of the densities of lake ice sheets
Authors: Adams W. P.
Published: March 2010

A method of calculating the mean density for a lake ice sheet and estimating the mean density of the white ice component of such a sheet makes use of the buoyancy equation for floating ice in the form

urn:x-wiley:00243590:media:lno19762140602:lno19762140602-math-0001
where p′ and h′ are mean density and thickness respectively and the subscripts are ice (i), water (w), and (s). The technique requires the measurement of snow density on the lake. Mean ice sheet densities of 0.89 and 0.85 g cm‒3 and mean white ice densities of 0.84–0.87 are reported from two lakes.
Influence of surface waves on subsurface current measurements in shallow water1
Authors: Halpern David , Pillsbury R. Dale
Published: March 2010

Aanderaa current‐meter readings were taken at 43 m at two sites 0.2 km apart in water 50 m deep near the central Oregon coast. The uppermost extensions of the subsurface moorings were about 3 and 18 m deep. During a 25‐day period in July and August 1973, mean speeds differed by about 47%. For low frequencies (<0.7 cph) there was a 1 : 1 correspondence between the shapes of the kinetic‐energy density spectra. For all frequencies, spectral density estimates of the data recorded beneath the deeper placed topmost float were lower than the estimates of the other data. The effect of surface wave motion on Aanderaa current measurements is discussed.
A lightweight, power‐independent filtration apparatus for field use
Authors: Blakar Inggard Arne , Hongve Dag , Digernes Ivan
Published: March 2010

A lightweight filtration apparatus is based on the vacuum created by means of a falling column of water inside a flexible tube. Large volumes can be filtered automatically. The equipment is noiseless, can be installed indoors, and can be modified for use aboard boats.
Lago Verde and Lago Flaco: Gypsum‐bound lakes of the Chilean altiplano1
Authors: Hurlbert Stuart H. , Berry Richard W. , Lopez Matilde , Pezzani Silvia
Published: March 2010

Two small perennial salt lakes in a salar of the Chilean altiplano have indurated bottom sediments and are bordered by damlike ramparts composed of almost pure gypsum. The bottom of one lake is constituted of polygonal plates (5–15‐m diam) of gypsum buckled upward into pressure ridges and overthrust slabs. Overthrust slabs that have reached the lake surface have developed massive iceberglike accumulations of gypsum on their leading edges. Expansion of anhydrite (CaSO4) on alteration to gypsum (CaSO4 ·2H2O) is speculated to be involved in formation of the pressure ridges. The two lakes are about four times deeper (2 m) than any other lakes in the salar, and their surfaces are elevated as much as 1.2 m above the adjacent salar crust, only the gypsum ramparts intervening. The ramparts range to 2 m high. The buildup of these ramparts via evaporative precipitation of wave‐wash, spray, and capillary brine, elevation of the lip of the small outflow channels, and deflation of the salar crust probably account for the lakes’ depths and elevated positions.
Ecological and nutritional studies on Dinobryon Ehrenb.: Seasonal periodicity and the phosphate toxicity problem
Authors: Lehman John T.
Published: March 2010

Although field studies show inverse correlations between concentrations of dissolved phosphate and abundances of Dinobryon, phosphorus is not toxic even at high concentrations. Species abundance in water of low phosphate concentration may be traced instead to effective mechanisms for phosphate uptake which allow the cells to thrive at low ambient levels of PO4‐P. Half‐saturation constants of less than 0.5 µM PO4‐P can be demonstrated both in laboratory cultures and in situ in lakes. Ambient concentrations of potassium ion can be toxic to a variety of species of Dinobryon and thus can limit both their geographical and seasonal occurrence. Ammonium serves as a better nitrogen source than does nitrate, an observation supported by both field and laboratory data. At least one species, Dinobryon sertularia, is physiologically limited to water temperatures below 20°C.
Effects of nitrate and ammonium enrichment on growth and nitrogen physiology in Fucus spiralis1
Authors: Topinka Jerry A. , Robbins Jon V.
Published: March 2010

Growth and physiological responses of whole specimens of Fucus spiralis to nitrate and ammonium enrichment were measured in a continuous‐flow system using seawater from the Massachusetts coast. As physiological indicators of nitrogen status, total C and N, dark ammonium uptake, and respiratory stimulation by ammonium were examined in plant apices. Total nitrogen content and growth rate increased with the level of nitrate or ammonium addition, both supporting similar growth. Dark ammonium uptake was not as sensitive an indicator of nitrogen status as the respiratory stimulation by ammonium. Although the growth of F. spiralis may become nitrogen limited, plants did not exhibit severe nitrogen deficiency responses.
In situ experiments on the dissolved and colloidal state of iron in an acid bog lake1
Authors: Koenings Jeffery P.
Published: March 2010

A sampler and an analytical and characterization scheme were developed to investigate the chemical and physical state of iron in a highly stained acid bog lake (North Gate Lake). Iron fractions were chemically separated by reactivity to bathophenanthroline (BPN) after specific digestion procedures. Physical separation by anaerobic in situ filtration (450 nm) and in situ dialysis (4.8 nm) resulted in three size classes: particulate, colloidal, and dissolved.

Inorganic, nonreactive species of iron [e.g. Fe(OH)3] represent minor amounts of the total iron in North Gate Lake, in contrast to lakes of pH 6–8. In situ radiochemical analyses revealed that colloidal reactive ferric iron predominates in the oxygenated epilimnion, while dialyzable or dissolved ferrous iron increases with depth. Unlike iron, organic matter is present in a nontransient colloidal state. In acid (pH 4–5) bog lakes ferric iron may be colloidal not as an inorganic complex (OH‒) but as reactive Fe3+ by complexation with the colloidal organic acids.

After thermally induced mixing with anaerobic waters, ferric iron is reduced and dissolved; however some of the BPN reactive iron remains colloidal, suggesting the presence of a residual ferrous organic complex.
Microbial utilization of thiosulfate in the deep sea1
Authors: Tuttle Jon H. , Jannasch Holger W.
Published: March 2010

Natural microbial populations in deep and shallow North Atlantic water and previously isolated heterotrophic thiosulfate‐oxidizing bacteria have the potential to metabolize thiosulfate when incubated in situ at elevated hydrostatic pressure and low temperature.
Pelagic food webs in the tropical Pacific
Authors: Roger Claude , Grandperrin Rene
Published: March 2010

Analysis of stomach contents, feeding rhythms, vertical distributions, and day—night migrations of the successive links of a pelagic food chain leads to a functional model of the prevailing trophic relationships and to identification of basic mechanisms determining the food web structure. This model demonstrates the existence of processes which support the downward energy transfer and reduce the upward one.
Hydrochemistry of the Parana River
Authors: Depetris Pedro J.
Published: March 2010

Recent monthly data from the Paraná River show that its hydrochemistry is controlled by the nature of the rocks in the basin, with significant contributions from saline environments during low discharge. The discharge‐weighted mean dissolved salts concentration (79.8 mg liter‒1) allows a new calculation of 56.7 mg liter‒1 for the mean dissolved salts concentration of South American rivers.
An analysis of salinity variations within Great South Bay, New York
Authors: Moskowitz Paul D.
Published: March 2010

A series of correlation coefficients comparing stream flows with Great South Bay salinities indicates that changes in salinity observed within the bay were statistically associated with variations in stream flow. No significant correlation between salinity and rainfall was observed. The results may have significance to outfall sewering on Long Island.
Laminated sediments in holomictic Berkshire lakes1
Authors: Ludlam Stuart D.
Published: March 2010

Laminated sediments are common in the profundal sediments of the deeper holomictic lakes in the Berkshire Hills of Massachusetts. The laminae are best developed in lakes subject to prolonged seasonal hypolimnetic anoxia and in one lake are limited to water depths in which seasonal anoxia occurs.
The use of the Robertson meter to measure the penetration of solar middle‐ultraviolet radiation (UV‐B) into natural waters1
Authors: Smith Raymond C. , Calkins John
Published: March 2010

The Robertson meter, developed and widely used to respond to the erythemal‐action spectrum, has been adapted to measure the penetration of UV‐B into natural waters. When used underwater it is subject to a relatively small systematic error (<10%) only when it is used to make measurements at less than about five optical depths; it may then be assigned a specific mean wavelength near 312 nm. Measurements made at greater than five optical depths are subject to increasingly larger systematic error.
Loss of radiocarbon in direct use of Aquasol for liquid scintillation counting of solutions containing 14C‐NaHCO31
Authors: Iverson Richard L. , Bittaker Henry F. , Myers Vernon B.
Published: March 2010

Carbon‐14 activity was lost when 14C‐NaHCO3 in aqueous solution was added to Aquasol. Phenethylamine can be used to form carbamates which are stable in Aquasol in order to achieve complete retention of 14C in the liquid scintillation cocktail.
A diurnally fluctuating thermal system for studying the effect of temperature on aquatic organisms1
Authors: Sweeney Bernard W.
Published: March 2010

An open, flow‐through system with diurnally fluctuating temperature regimes has been designed to study growth and developmental dynamics of benthic macroinvertebrates. Animals are kept in five sets of plastic troughs and trays arranged in a longitudinal series and separated by polyethylene‐lined warming pools. Five diurnally oscillating temperature regimes of various magnitudes are produced depending on pool size. The magnitudes of the temperature pulse are quite predictable for each regime.
Respiration of the antarctic copepod, Rhincalanus gigas1
Authors: Rakusa‐Suszczewski S. , McWhinnie M. A. , Cahoon M. O.
Published: March 2010

Oxygen consumption and CO2 production of R. gigas were measured during the austral winter. O2 uptake was lower than for low latitude species; the RQ was substantially below 0.7. High lipid content and low respiratory gas exchange in antarctic plankton indicate lipid oxidation for energy, suggesting metabolic adaptation through utilization of NADP‐dependent oxidations. Two periods of reproduction of R. gigas are evident.
The vertical and seasonal distribution of chlorophyll in lakes of the Experimental Lakes Area, northwestern Ontario: Implications for primary production estimates
Authors: Fee Everett J.
Published: March 2010

An in vivo flow‐through fluorometer system revealed narrow bands of very high chlorophyll concentrations in the meta‐ or hypolimnia of all clear, stratified ELA lakes. In two experimentally fertilized lakes chlorophyll concentrations in the hypolimnion exceeded 300 µg liter−1 while epilimnetic chlorophyll was only 3 µg liter−1. The hypolimnetic bloom represented the major response to enhanced nutrient loading. The peak was in or below the thermocline at depths where 1–3% of photosynthetically available surface irradiance penetrated; the algae at the peak were actively growing flagellated colonial chrysophyceans. The autumn surface “bloom” was due to entrainment of this previously produced chlorophyll, not to growth caused by mixing in of hypolimnetic nutrients.