bluuebunny/crossref_metadata_2025 huggingface dataset:
Some consequences of distributional heterogeneity of phytoplankton and zooplankton1
Authors: Mullin Michael M. , Brooks Elaine R.
Published: March 2010

Information on the small‐scale distributions of phytoplankton and the developmental stages of the copepod Calanus pacificus was combined with estimates of ingestion and respiration to examine the consequences of distributional heterogeneity on the nutrition of the copepods. During two cruises, in April and June, the average situation was such that the population of copepods in the water above the thermocline could at least meet its metabolic requirement by feeding on all sizes of phytoplankton. Although the rate of ingestion by the population was insufficient to meet its requirement at 25 of the 61 points sampled in April, there was at least one depth at each of the ten stations where the requirement was being met. In June the population was better nourished, on the average, than in April, but at five of the twelve stations there was no depth above the thermocline at which ingestion equalled respiration. The duration of this patchiness will determine its ecological impact.
Energetically efficient swimming behavior of negatively buoyant zooplankton1
Authors: Haury Loren , Weihs Daniel
Published: March 2010

A number of species of negatively buoyant zooplankton perform a swimming behavior characterized by a repeated upward swimming followed by passive sinking. This hop and sink behavior is shown theoretically to save energy relative to continuous swimming at a fixed depth. The maximum energy saving is a function of the drag ratio and speeds of swimming and sinking.
Vertical migration in zooplankton as a predator avoidance mechanism1
Authors: Zaret Thomas M. , Suffern J. Samuel
Published: March 2010

Field data and laboratory feeding experiments support the hypothesis that predation can be an important factor in the adaptive significance of vertical migration among zooplankton. In both Gatun Lake in Panama and Fuller Pond in Connecticut the diel vertical migration patterns of prey populations assume distributions which result in lessened predation by the dominant lake planktivores. It is concluded that such patterns of vertical migration will result when prey populations are under intense, selective pressures from visually dependent predators.
Diel feeding and respiration rhythms in zooplankton1
Authors: Duval W. S. , Geen G. H.
Published: March 2010

Diel rhythms in respiration and feeding of zooplankton from three British Columbia lakes were examined in laboratory experiments conducted at constant temperature and in the absence of light. Endogenous rhythms in respiration and feeding were demonstrated at temperatures from 10–22°C and were typically bimodal with maximum rates found at dawn and dusk and lowest values near midday. Dawn and dusk respiration rates were an average of 2.3 times higher than during midday; the corresponding diel difference in feeding was 6.6 times.
Influences of light regime on postembryonic development in two strains of Daphnia pulex1
Authors: Starkweather Peter L.
Published: March 2010

Two strains of Daphnia pulex were used to assess the influence of continuous illumination, darkness, and light‐dark cycles on the developmental rate of preadult animals. In one strain, animals reared in continuous illumination or darkness developed more slowly than siblings held under a photocycle. Animals in 24‐h photocycles developed at the same rate, irrespective of the relative length of the light and dark periods. The effects were probably independent of nutritional differences. Animals of the second strain developed at comparable rates in both photocycle and continuous light regimes, but differed in primaparous instar timing between the treatments.
The role of surface and extracellular phosphatases in the phosphorus requirement of Ochromonas1
Authors: Aaronson S. , Patni N. J.
Published: March 2010

Acid and alkaline phosphomonoesterase (PME) activity of phosphorus‐depleted Ochromonas danica could be partially but not completely repressed by exogenous inorganic phosphate (Pi). Acid and alkaline PME activities were found in the plasma membrane as well as the cytosol and acid PME was secreted in the cell’s environment. The extracellular and surface PME could provide the necessary phosphate for the growth of phosphorus‐depleted algae in the presence of organic phosphates; specific organic phosphates, glucose‐1‐phosphate (G‐1‐P) and glucose‐6‐phosphate (G‐6‐P), supported growth with small inocula, other organic phosphates were inactive. G‐1‐P and G‐6‐P induced almost double the normal PME secretion, and this extra secretion is shown to be sufficient to provide for the growth of phosphorus‐depleted cells inoculated in relatively small numbers.
Fractionation by molecular weight of organic substances in Georgia coastal water1
Authors: Wheeler John R.
Published: March 2010

Ultrafiltration membranes were used to separate organic substances in Georgia coastal water into fractions to which approximate molecular weight (MW) ranges could be assigned. Salt marsh water contained high concentrations of dissolved organic carbon between 1,000 and 30,000 MW, as well as high concentrations of dissolved carbohydrate in all MW classes. Concentrations of dissolved carbohydrate in offshore waters were low, and in some MW fractions (especially those >30,000 MW) carbohydrate was at times undetectable. Absorbances at 254 run by MW fractions roughly paralleled concentrations of dissolved organic carbon. Most of the color of marsh, sound, nearshore, and offshore waters, once the particles were removed, was due to substances between 1,000 and 30,000 MW.
Partial molal volumes of some major ions in seawater1
Authors: Poisson Alain , Chanu Jacques
Published: March 2010

A densimetric method is used for determining the partial molal volumes, V*(i), of NaCl, KCl, CaCl2, MgCl2, Na2SO4, and MgSO4 in seawater and thermal expansibilities of V*(i) of these salts are deduced. A semiempirical relation is proposed for the partial molal volumes of salts, in the range of temperatures and salinities of the world ocean. The partial molal volumes of these ions are estimated on the assumption that the partial molal volume at infinite dilution of proton, V* °(H*), is exact and that the volume of transfer of Cl− from pure water to seawater does not vary with temperature. A convenient equation of partial molal volume of ions as a function of temperature and salinity is given.
Production of epibenthic salt marsh algae: Light and nutrient limitation1
Authors: Charlene D. Van Raalte , Ivan Valiela , John M. Teal
Published: March 2010

Epibenthic algal production was measured in Great Sippewissett Marsh, Falmouth, Massachusetts, in plots treated with two levels of a mixed fertilizer and with urea or phosphate. Production, which followed a consistent seasonal pattern with short‐lived peaks in spring and fall, was increased by the highest dosage of mixed fertilizer but not by the other treatments. Fertilization also increased production of the marsh grasses. Algal production at the marsh surface was limited due to shading by the grass canopy. The production rate decreased with increasing biomass of the grasses.

To separate the effects of light and nutrients in the treated areas, additional small plots were enriched with three levels of nitrogen (suspected as the limiting nutrient) and provided with three levels of canopy cover cross‐classified to the nitrogen treatments. Shading by the grasses reduced, while fertilization with nitrogen significantly increased, production. When the grasses were dormant, prediction from a model of epibenthic production based on limitation by light compared well with observed measurements. The predicted production rate was higher than that observed during the growing season of the grasses. In the plots receiving the highest doses of mixed fertilizer the added nutrients compensated for the light limitation, since the discrepancy between predicted and observed values was smaller than in the control plots.
Relation between the stable carbon isotope composition of fiddler crabs, plants, and soils in a salt marsh1
Authors: Haines Evelyn B.
Published: March 2010

The fiddler crab Uca pugnax consumes detrital material on the soil surface in monospecific and mixed species stands of C3 and C4 plants in Georgia salt marshes. The carbon isotopic ratios of U. pugnax collected in eight separate areas of a salt marsh were linearly related to the 13C : 12C ratios of the plants; the relation between the 13C : 12C ratios of the crabs and marsh soils was less direct. The stable isotopic composition of the crab carbon was biased toward the 13C : 12C ratios of the C4 plants.
Concentration of diatom frustules in Lake Michigan sediment cores1
Authors: Parker Jon I. , Edgington David N.
Published: March 2010

The concentration of diatom frustules was determined in 14 sediment cores that were dated by 210Pb and 137Cs techniques. The concentration in the 0–0.5‐cm sediment layer varied from 6.31 × 105 to 3.71 × 107 frustules g dry wt−1. The annual deposition of frustules to the sediment ranged from 7.00 × 103 to 5.20 × 105 frustules cm−2 yr−1, <5% of the estimated annual diatom production based on average annual diatom standing crop, turnover rate, and depth of the euphotic zone. The vertical distribution of frustules in every core showed a logarithmic decrease of at least two orders of magnitude in a depth equivalent to 80–100 years B.P. Scanning electron photomicrographs of frustules from the sediment show evidence of dissolution. Dissolved silica concentrations in deep and interstitial water support the conclusion that diatom frustules are dissolving in both the water column and sediment. The permanent sediment is probably not a major sink for particulate biogenic silica in Lake Michigan.
Environmental differentiation of morphology of ferromanganese oxide concretion in Shebandowan Lakes, Ontario1
Authors: Sozanski A. G. , Cronan D. S.
Published: March 2010

Ferromanganese oxide concretions in Shebandowan Lakes show morphological differences depending on the environments of deposition. Six main morphological types have been defined, with subsidiary varieties. The best developed concretions occupy the shallowest most oxygenated portion of the lake. Changes in pH and Eh have resulted in the partial dissolution of some concretions in deeper water. The establishment of a relationship between concretion morphology and lake properties may aid in paleoenvironmental reconstructions in other lakes.
The analysis of SO42− in seawater by difference chromatography1
Authors: Sayles Frederick L. , Mangelsdorf Paul C.
Published: March 2010

A method of analysis of SO42− in seawater or seawaterlike samples is based on difference chromatography techniques and achieves a precision of better than 0.1% in the determination of SO42− : Cl− ratios. The determination is made on only 0.5 ml of seawater, making the technique particularly suitable for interstitial water studies where limited volumes of sample are available.
A squeezer for efficient extraction of pore water from small volumes of anoxic sediment1
Authors: Robbins John A. , Gustinis John
Published: March 2010

A simple, small‐volume, low pressure, diaphragm‐type sediment squeezer made from inexpensive standard nylon stock material, suitable for trace metal studies, features a removable sediment cassette with prefilter which greatly facilitates loading and cleaning. Pore water is recovered rapidly through a large active area membrane filter without clogging, impermeable cake formation, or gas breakthrough. A minimal pore water dead volume significantly reduces flushing losses and facilitates online electrode measurements. The squeezer is designed to accept small quantities of unconsolidated sediment (20–100 ml) from refrigerated cores sectioned in a nitrogen‐filled glove box.
Chemical water sampling in lakes and sediments with dialysis bags1
Authors: Mayer Lawrence M.
Published: March 2010

An inexpensive interstitial water sampler using dialysis bags for the in situ separation of water from particulate matter in lake waters and sediments is described, and an example of dissolved silica is given.
An in situ sampler for close interval pore water studies1
Authors: Hesslein Raymond H.
Published: March 2010

A sampler for defining compositional changes over distances on the order of 1 cm in aqueous systems operates by equilibration of water contained by a dialysis membrane with the surrounding water. Depth profiles of methane and phosphate in Hudson Estuary sediments are presented as examples.
A continuously monitored column for the study of stratification by planktonic organisms1
Authors: Booker M. J. , Dinsdale M. T. , Walsby A. E.
Published: March 2010

An apparatus is described for modeling stratified water systems. It comprises a cylindrical tank (about 2 × 0.5 m) illuminated from above and cooled at the bottom. Various chemical and physical conditions are automatically monitored by a collection of probes which continuously tracks up and down throughout the depth of the tank. A device for taking integrated water samples is incorporated in the apparatus.
A fixed net method to determine the vertical migration of plankton
Authors: Bovbjerg Richard V. , Freitag Judy , McHaney Dana
Published: March 2010

A vertical, fixed net method allows plankton to migrate directly into that net in a given time; the data are then a direct measure of the rate of vertical migration. A pilot study demonstrated feasibility.
The effect of acidification on measurements of microbial uptake of radioactive glucose in freshwater
Authors: Ramsay Angela J.
Published: March 2010

Untake and retention of 14C‐glucose by bacteria in freshwater was studied using the heterotrophic potential method. Fixing the organisms with acid and immediately cooling to 0°C eliminated the loss of labeled material frequently observed when organisms were acidified only. The cooling treatment also reduced the variability between replicate kinetic parameters calculated from assimilation data.
Improved extraction of chlorophyll a and b from algae using dimethyl sulfoxide
Authors: Shoaf W. Thomas , Lium Bruce W.
Published: March 2010

Dimethyl sulfoxide (DMSO) and 90% acetone extracted equal amounts of chlorophyll from diatoms and blue‐green algae, but DMSO was superior to 90% acetone for all green algae tested giving 2–60 times more chlorophyll depending on the species. The absorbance spectra of pure chlorophyll a (and b) from 600 nm to 750 nm were identical whether dissolved in 90% acetone or a mixture of DMSO and 90% acetone (1:1 v/v). Thus, several equations for estimating chlorophyll concentration based on extinction in 90% acetone are applicable with this solvent.
Microbial methane consumption reactions and their effect on methane distributions in freshwater and marine environments1
Authors: Reeburgh William S. , Heggie David T.
Published: March 2010

A survey of reported methane distributions in sediments and the adjacent overlying water shows distinct differences between freshwater and marine environments. These differences may be explained by the activities of sulfate‐reducing bacteria and appear to be the result of differences in sulfate concentration between freshwater and marine environments.
Interstitial water chemistry of anoxic Long Island Sound sediments. 1. Dissolved gases1
Authors: Martens Christopher S. , Berner Robert A.
Published: March 2010

Measurements of dissolved N2, Ar, CH4, and SO42− and salinity and temperature are used to examine the processes controlling their distributions in the interstitial waters of nearshore sediments. Where sulfate reduction is incomplete, dissolved N2 and Ar concentrations in the upper 10–30 cm appear to be controlled by macroinfaunal irrigation activities and vary in accordance with overlying water conditions. Below 30 cm, N2 and Ar concentrations appear to have been last affected by August through October irrigation. In harbor sediments where sulfate reduction is complete at shallow depths, low N2 and Ar concentrations result from in situ stripping by methane bubbles.

Methane concentrations remain below about 0.1 mM until about 90% of seawater sulfate is removed. As sulfate concentrations approach zero, methane builds up to bubble saturation. Concave‐up methane depth distributions can be explained by methane consumption following first‐order kinetics in the zone of sulfate reduction. Laboratory jar experiments with natural sediments indicate no methane production during sulfate reduction, in agreement with previous models and distribution studies of sulfate reducing and methanogenic bacteria in lake sediments. Combined laboratory and field results support the hypothesis that methane is produced mainly after sulfate is depleted but is consumed within the sulfate reduction zone as it diffuses upward.
Acetate uptake by aquatic bacterial communities measured by autoradiography and filterable radioactivity1
Authors: Stanley Patricia M. , Staley James T.
Published: March 2010

In a pulp mill waste aeration lagoon with a high organic content including measurable amounts of acetate, community uptake of acetate followed Michaelis‐Menten kinetics at concentrations of added acetate up to 30 µg ml−1. The measured in situ substrate level, Sn, was <6% to 46% of the K + Sn value calculated from the Michaelis‐Menten equation.

Autoradiography was used to determine the uptake kinetics of individual bacterial cells. Two morphologically distinct bacterial types followed Michaelis‐Menten kinetics, but one was at least four times more active in situ. Comparison of several different cell types indicated a minimum uptake activity range of 20‐fold. A few cell types did not absorb acetate. Different cells of the same type showed a 10‐fold range of activity, and the activity per cell did not follow a Poisson distribution.
Effect of benzoate on microbial decomposition of fulvic acids in Tjeukemeer (the Netherlands)
Authors: de Haan H.
Published: March 2010

The addition of benzoic acid to water from Tjeukemeer stimulated bacterial growth and decreased both the fluorescence and the color of the water, indicating disappearance of fulvic acids. This stimulation of bacterial growth is shown to result most likely from a priming effect of benzoic acid on the slow microbial decomposition of fulvic acid.

During growth of an Arthrobacter from the lake on benzoic acid in the presence of fulvic acid, fulvic acid of relatively small molecular size was formed from fulvic acid of relatively large molecular size, suggesting that microbial activity may play a role in the seasonal fluctuations in the molecular size distribution of fulvic acids in Tjeukemeer.
Iron‐rich rhythmically laminated sediments in Lake of the Clouds, northeastern Minnesota1
Authors: Anthony R. S.
Published: March 2010

Sediments from the deepest part of Lake of the Clouds (31 m) are rhythmically laminated throughout all but the basal part of the column. The laminations can be correlated with events in the lake during the annual cycle. Ferrous iron (maximum 620 ppm) accumulates in a layer of water about 2 m thick in the deepest part of the lake. The laminations form in the sediments only where overlain by this stagnant iron‐rich water. The light‐colored portion of the couplet presumably forms from iron oxides precipitated from partially oxygenated bottom water during fall and spring overturns, the dark layer from organic remains that settle out during summer.

Chemical analysis and electron‐microprobe studies reveal a much higher concentration of iron and manganese in the light layers than in the dark. Vivianite [Fe8(PO4)2 · 8H2O] and probably limonite (Fe2O3 · nH2O) occur extensively in nodules throughout the core. Siderite (FeCO3) was identified by X‐ray diffraction. Numerous orange spherical aggregates occur in the light layers. An iron and manganese profile of the sediment column suggests that the most distinct laminae are found where the iron content of the sediment is at least 4%.
Nitrogen fixation, distribution, and production of Oscillatoria (Trichodesmium) spp. in the western Sargasso and Caribbean Seas1
Authors: Carpenter Edward J. , Price Charles C.
Published: March 2010

Measurements of Oscillatoria spp. standing crop, primary production, and N2 fixation were made at 46 stations on three cruises to the Caribbean and western Sargasso Seas. Oscillatoria is a major component of the Caribbean Sea plankton, comprising 60% of the total chlorophyll a in the upper 50 m and about 20% of the primary production. Through N2 fixation it contributes an average of 1.3 mg N m−2 d−1 to the Caribbean Sea, and this may be a major input of nitrogen to this area. Oscillatoria appears to be of relatively little importance in the western Sargasso Sea.
Sustained viability of aphotic phytoplankton in Lake Tahoe (California‐Nevada)
Authors: Tilzer Max M. , Paerl Hans W. , Goldman Charles R.
Published: March 2010

Biomass, chlorophyll a, and photosynthetic potential of phytoplankton were measured year‐round throughout a 450‐m water column of ultraoligotrophic Lake Tahoe. Phytoplankton biomass was uniform from the surface to the maximum depth while the lake mixed completely in March, but was lower in aphotic waters during thermal stratification. Aphotic chlorophyll a concentrations decreased progressively in fall and reached a minimum of 17% of mean euphotic concentrations in January, before the mixing depth exceeded the euphotic depth. Photosynthetic rates measured in an incubator under constant light conditions were significantly correlated with pigment concentrations in both euphotic and aphotic phytoplankton and demonstrated viability of the aphotic phytoplankton throughout the year.

High surface : volume ratios of the small species dominating the phytoplankton assemblage suggest low sinking velocities. Extremely slow decomposition is postulated to explain the vertical pigment concentration gradients in the aphotic zone.

Re‐entry of viable aphotic phytoplankton into the euphotic zone during deep mixing of the lake can diminish the dilution of euphotic phytoplankton, thereby increasing the magnitude of the subsequent vernal bloom.
Respiration and ammonium excretion by open ocean gelatinous zooplankton1
Authors: Biggs Douglas C.
Published: March 2010

Warm‐water species of siphonophores, medusae, ctenophores, heteropods, pseudothecosomatous pteropods, salps, and doliolids were individually collected in jars by SCUBA divers in the western North Atlantic Ocean. In situ rates of oxygen consumption and ammonium excretion were estimated by difference from control jars of seawater enclosed simultaneously. The cystonect siphonophores Rhizophysa filiformis and Bathyphysa sibogae had low respiration and excretion rates [4–7 µl O2 (mg protein‐h)−1 and 0.3–0.5 NH4+(mg protein‐h)−1], while several calycophore siphonophores, heteropods, and salps had high rates [19–192 µl O2 (mg protein‐h)−1 and 1.0–3.1 µg NH4+ (mg protein‐h)−1]. Most O: NH4+ ratios ranged from 16–38 and suggest that both protein and lipid are important metabolites in tropical and subtropical gelatinous zooplankton. Many physonect siphonophores, scyphomedusae, heteropods, and salps excreted ammonium at rates exceeding 0.3 µg‐atom NH4+‐N h−1 and may play an important role in recycling nitrogen in the upper mixed layer of oligotrophic ocean regions.
Copepods in a hurry: Sustained high‐speed upward migration1
Authors: Enright J. T.
Published: March 2010

Replicated data on the vertical migration of the copepod Metridia pacifica indicate that this 2–3‐mm animal can maintain upward swimming velocities of from 30 to 90 m h−1 for durations of more than an hour. Internal evidence in the data suggests that much of the variability within this range reflects differences in motivation of the animals, rather than sampling error. These data are apparently the greatest sustained swimming speeds ever substantiated for any copepod and are larger by a factor of from two to ten than several previous field estimates for copepods.
A device for measuring seepage flux in lakes and estuaries1
Authors: Lee David Robert
Published: March 2010

Seepage flux can be measured and samples of groundwater flowing into lakes and estuaries collected by enclosing an area of bottom with a cylinder vented to a plastic bag. The method has the advantage of not requiring measurements of permeability of bottom sediments. Seepage velocities from −0.1–2.58 µm s−1 were measured in Minnesota and Wisconsin lakes and in Nova Scotia and North Carolina estuaries.

Where seepage inflow was rapid (0.4–0.8 s−1), water collected with the seepage meter was chemically similar to water from wells on the same flow path, and the distribution and chemistry of the seepage concurred with a theoretical flow net. The rate and direction of seepage flux were correlated with water surface elevation during a tidal cycle.
The diurnal vertical migration of motile phytoplankton through temperature gradients1
Authors: Kamykowski Daniel , Zentara Sara‐Joan
Published: March 2010

In experiments in a 10 m, thermally stratified seawater column, Cachonina niei crossed a 5°C gradient during a 4‐m diurnal vertical migration, while Amphidinium carteri remained in the upper, isothermal, part of the water column during a 1‐m diurnal vertical migration. The experiments confirm that some marine dinoflagellates have access to subthermocline nutrient pools. These same species may also exhibit spatial and temporal patchiness in response to countercurrent flow across the thermocline.
Evidence for strong currents and turbulence in a deep coral reef groove1
Authors: Roberts H. H. , Murray S. P. , Suhayda J. N.
Published: March 2010

High levels of turbulence (turbulence intensity ≃23 cm s−1, diffusion coefficient ≃ 2.4 ✕ 103 cm2 s−1), and strong currents (≃35 cm s−1) were found in a deep coral reef groove (≃33 m). This unexpected turbulence is likely related to the ambient current acting on reef roughness elements, e.g. coral heads. Well developed coral communities that commonly occur at the deep margins of island shelves may in part be associated with these unusual levels of turbulent diffusion.
A simplified expression for calculating cohort production
Authors: LeBlond P. H. , Parsons T. R.
Published: March 2010

A simplified method for calculating the production of a cohort is given in terms of readily measured parameters involving ΔB, the observed change in biomass, m the mortality of individuals, and g the observed growth rate of the biomass.
A new method for physical limnology—tritium‐helium‐3 ages—results for Lakes Erie, Huron, and Ontario1
Authors: Torgersen T. , Top Z. , Clarke W. B. , Jenkins W. J. , Broecker W. S.
Published: March 2010

A new method in physical limnology based on the radioactive tracer tritium and its stable daughter product, 3He, is examined. The 3He produced by the in situ decay of tritium can be used to calculate an effective water mass age. These ages can then be used to estimate gas exchange rates, gas renewal at turnover, and vertical diffusivity in the epilimnion.
Effect of the Aswan High Dam on the Nile flood and on the estuarine and coastal circulation pattern along the Mediterranean Egyptian coast
Authors: Sharaf El Din S. H.
Published: March 2010

From 60–180 million tons of sediments and 18 ✕ 109 to 55 ✕ 109 m3 of water were transported to the Mediterranean Sea by the Nile annually before the Aswan High Dam was erected in 1964. Before completion of the dam, during the flood period the estuarine circulation pattern was a two‐layer flow at the mouth of the two estuaries. In winter the circulation pattern was a one‐layer flow of seawater; this pattern has persisted during most of the year since 1964. The velocity of the currents at the mouth of the Nile branches reached more than 4 knots at the surface but was less than 0.5 knot at the bottom during the flood period before 1964; after 1964 this velocity dropped considerably. General oceanographic conditions in the offshore region beyond the continental shelf did not change noticeably, but hydrographic conditions over the continental shelf in front of the delta showed considerable change after 1964. Also, since 1964 almost no sediment has been discharged from the Nile. This has produced an imbalance in the near‐coast sediment budget, increasing erosion at the two mouths of the river and shifting the sediments along the coast.
Dynamics of O2 and CO2 exchange, photosynthesis, and respiration in rivers from time‐delayed correlations with ideal sunlight
Authors: Schurr J. M. , Ruchti J.
Published: March 2010

The oxygen exchange constant, photosynthetic rate, and respiration rate for several Swiss rivers have been determined using only the continuous data record of a single oxygen electrode, the measured temperature, and an assumed ideal light intensity curve in conjunction with a simple model rate equation and a novel cross‐correlation computational technique. The method can, in favorable circumstances, be extended to determine also total carbonate dynamics from continuous pH measurements.

For the Aare at Bern in March 1974, the oxygen exchange constant was 0.38 h−1, the respiration rate was 0.6 mg liter−1 h−1, and mean photosynthetic rate was 0.28 mg liter−1 The exchange rate for dissolved (but not hydrated or ionized) CO2 was 0.91 times that for dissolved oxygen, and the ratio of O2 molecules released to CO2 molecules consumed during photosynthesis was about 1.2.
A model of river benthic algal photosynthesis in response to rapid changes in light1
Authors: Gallegos Charles L. , Ilornberger George M. , Kelly Mahlon G.
Published: March 2010

A linear relationship has been found between light and community productivity in a river, but the correlation is reduced when radiation varies rapidly due to the passage of cumulus clouds. To investigate the relationship during periods of patchy cloudiness we developed a method of calculating short term variations in oxygen exchange based on oxygen measurements taken at very frequent intervals. The method has a high degree of resolution when used with data recorded at 1‐min intervals and the results indicate that large fluctuations in oxygen exchange on time scales of about 5 min can be discerned. Cross‐spectral analysis of the productivity data and measured radiation indicated that a linear lead model for algal photosynthesis in rivers is appropriate. This model has the property that the change in net oxygen productivity per unit change in light is enhanced during periods of rapidly varying radiation relative to periods of slowly varying light.
Red tide in the upwelling region of Baja California1
Authors: Blasco Dolors
Published: March 2010

Predominant organisms in a red water dinoflagellate bloom during the seasonal onset of coastal upwelling off Baja California were Gonyaulax polyedra, Ceratium furca, and Gymnodinium sp. The major part of the chlorophyll and the 14C assimilation in the area was related to the G. polyedra population. The maximum concentration of these organisms was associated with low salinity water of the surface California Current. The dinoflagellates remained in the area during the 20‐day cruise, although the vertical stability coefficient was low, with no steep temperature gradient. The high concentrations of small copepods suggest them as major grazers of G. polyedra.
The uptake and release of dissolved phosphorus by reef corals1,2
Authors: D'Elia Christopher F.
Published: March 2010

The fluxes of dissolved reactive, organic, and total phosphorus into and out of non‐feeding corals were measured by chemical and radiochemical techniques. A net uptake of reactive phosphorus from seawater by corals containing zooxanthellae was not, at typical ambient phosphorus levels, sufficient to offset simultaneous losses of organic P. Consequently, there was a net loss of total P. A coral without zooxanthellae was unable to remove net amounts of reactive P from solution even at levels above ambient. Reactive phosphorus uptake was light sensitive, was highly temperature dependent, showed characteristics of Michaelis‐Menten kinetics, and could be inhibited by arsenate. An active transport mechanism appears to be involved. The kinetics of net reactive phosphorus uptake were described by a Michaelis‐Menten equation modified to include a correction for an efflux of reactive P accompanying uptake. The mean half‐saturation (K) for uptake was 377 nM and the mean maximum rate of uptake (vmax) was 293 ng atoms P · mg Chl a−1 · h−1.

Although the symbiotic corals tested cannot obtain all of the phosphorus they require by means of reactive phosphorus uptake at typical environmental concentrations, the ability of corals to obtain part of it in this manner, and the presence of mechanisms for efficient recycling of phosphorus within the symbiotic association, may help enable corals to flourish in waters low in phosphorus sources.
Implications of copepod predation1
Authors: Kerfoot W. Charles
Published: March 2010

The copepod Epischura nevadensis selectively preys on zooplankton communities in a way that reduces the abundance of the cladoceran Bosmina longirostris and favors larger‐bodied species. Bosmina responds to this predation by behavioral and morphological adjustments that frustrate the searching and handling strategies of the predatory copepods; this response implies considerable evolution between the two antagonists. Predation by copepods and other freshwater invertebrates seems an important factor in determining not only the size composition of lake communities, but the shape in some species.
Growth rules in the marine copepod genus Acartia1,2
Authors: Miller Charles B. , Johnson John Kenneth , Heinle Donald R.
Published: March 2010

Several species of the copepod genus Acartia are shown from existing data to complete each molt‐to‐molt phase of the life cycle in a constant time period. This molting pattern is termed isochronal development. Increase in mass at each stage is a nearly constant fraction of the weight at the beginning of the stage (with the exception of the late naupliar stages). Coupled with isochronal development this implies that growth in Acartia is exponential in time through most of the life cycle. Under isochronal development a proportionately shorter part of the total development is spent in the copepodite stages than in forms with stages of progressively greater duration. This may be a response to preference of the predators of Acartia for the older stages or a general adaptation leading to a shorter life cycle and higher rates of population increase.
Composition and stratigraphy of the fossil phorbin derivatives of Little Round Lake, Ontario
Authors: Brown S. R. , Daley R. J. , McNeely R. N.
Published: March 2010

The chlorophyll derivatives from the sediment of meromictic Little Round Lake, Ontario, have been analyzed by artifact‐free paper chromatography. Sixteen native and allomerized a and b chlorophylls, chlorophyllides, pheophytins, and pheophorbides, together with bacteriopheophytin a and one unknown phorbin, were isolated from the core. No chlorophyll c derivatives were found. An average of 52% of the phorbins were devoid of Mg, 19% were allomerized, and 47% had lost the phytol group. Unaltered native chlorophyll b occurred in much higher proportions (22%) than chlorophyll a (0.3%), indicating that the b phorbins are more resistant than the a pigments to diagenesis. Continuous changes in derivative proportions with depth were not apparent; hence, little phorbin diagenesis occurred after burial in the sediment. The complexity of the profiles from this one lake suggests that using chlorophyll derivatives as paleolimnological indicators will be difficult.
Chromatographic and SCDP measurements of fossil phorbins and the postglacial history of Little Round Lake, Ontario
Authors: Daley R. J. , Brown S. R. , McNeely R. N.
Published: March 2010

Estimates are compared of total chlorophyll derivatives from the sediments of meromictic Little Round Lake, Ontario, as determined by the relative SCDP procedure and by quantitative paper chromatographic fractionation. Contrasting profiles of total phorbins were obtained with the two techniques. By comparing SCDP:chromatographic phorbin ratios with extinction coefficients of purified derivatives, the discrepancies are tentatively ascribed to errors in the SCDP procedure resulting from variations in a phorbin composition, interference by b phorbins, and possible interference by nonphorbin contaminants in the 90% acetone extracts. SCDP data must, therefore, be interpreted with great care.

From the algal phorbin data and additional information on bacterial phorbins, bacterial carotenoids, and the contemporary limnology of Little Round Lake, it appears that primary productivity increased to a maximum early in postglacial time and then declined progressively to the present low levels. The decline began with the probable onset of biogenic meromixis shortly after the early production maximum. The a:b phorbin ratio indicates strong differential diagenesis of the a phorbins in the lake and also the dominance of plankton containing only chlorophyll a (probably cyanophytes) since the beginning of agriculture in the area.
A trophic state index for lakes1
Authors: Carlson Robert E.
Published: March 2010

A numerical trophic state index for lakes has been developed that incorporates most lakes in a scale of 0 to 100. Each major division (10, 20, 30, etc.) represents a doubling in algal biomass. The index number can be calculated from any of several parameters, including Secchi disk transparency, chlorophyll, and total phosphorus.
Independent estimate of the pH of Dead Sea brine
Authors: Ben‐Yaakov Sam , Sass Eytan
Published: March 2010

The pH of artificial Dead Sea brine was measured by an electrochemical cell without a liquid junction. The cell consisted of a pH sensitive glass electrode and a Ag/AgCl electrode. The system was standardized in HCl solutions and pH was calculated from a measurement by this cell after estimating theoretically the activity of Cl in the brine. It is suggested that the pH of artificial Dead Sea brine is 5.86, consistent with pH values obtained by conventional pH measurements.
Tritium oxide uptake by algae: An independent measure of phytoplankton photosynthesis1
Authors: McKinley Kelton R. , Wetzel Robert G.
Published: March 2010

A new method for estimating algal productivity using tritium oxide shows close agreement with the 14C‐CO2 uptake and O2 evolution techniques, with acceptably low error, and can also be used under conditions where conventional methods are inappropriate.
Excretion of dissolved organic carbon by eelgrass (Zostera marina) and its epiphytes1
Authors: Penhale Polly A. , Smith Walker O.
Published: March 2010

The release of dissolved organic carbon (DOC) by eelgrass (Zostera marina) and its epiphytic community was examined in a shallow estuarine system near Beaufort, North Carolina. Excretion by eelgrass alone, by epiphytes alone, and by heavily epiphytized eelgrass was determined by radiocarbon techniques. The percent of total photosynthate excreted was small in all cases: 0.9% for heavily colonized plants, 1.5% for Zostera alone, and 2.0% for the epiphytic community. The amount released by the eelgrass and epiphytes was proportional to the total amount of carbon fixed. Excretion rates in the dark were much lower than in the light. The rate of excretion increased after the plant underwent desiccation. The annual primary production and DOC excretion by phytoplankton, cordgrass (Spartina alterniflora), and the eelgrass community was estimated: 47% of the total annual primary production and 14% of the total excreted material was contributed by eelgrass and its epiphytes. Thus the eelgrass and epiphytes can play an important role in carbon cycling in estuarine systems.
Sorption and hydrolysis of added organic phosphorus compounds in lake sediments1
Authors: Rodel M. G. , Armstrong D. E. , Harris R. F.
Published: March 2010

The sorption and hydrolysis of three types of organic phosphate compounds in a lake sediment‐water system were investigated. An intact, nonsterilized sediment was used to allow evaluation of chemical and biological effects. Sorption was attributed mainly to chemical interactions and hydrolysis to sediment microorganisms. The extent of sorption varied with the type of compound and was partly related to the number of phosphate groups per molecule. Hydrolysis rates were decreased by organic P sorption and by incubation at 4°C rather than room temperature.
Short term sedimentation response in lakes in western United States as measured by automated sampling1
Authors: Anderson Roger Y.
Published: March 2010

Sediment traps that can greatly amplify the rate of sedimentation and automatically time the depositional process were set out in El Vado Lake and Morgan Lake (New Mexico), Lake Powell (Utah), and Pyramid Lake (Nevada). In El Vado and Morgan lakes, sediment fluctuations on the scale of days were responsive to local weather factors, with the deposition rate in Morgan Lake greater near the bottom of the water column than near the top. Sedimentation in El Vado and Pyramid lakes appeared to have some diurnal control. Sedimentation in Pyramid Lake and Lake Powell, the two lakes fed by large rivers, was strongly influenced by river discharge and showed lag effects proportional to the distance of sediment transport.
Short term variability in vertical chlorophyll structure1
Authors: Denman Kenneth L.
Published: March 2010

A 26‐h series of vertical profiles of chlorophyll a and temperature, one every 15 min, was obtained during 22–23 April 1974 in 35 m of water in St. Margaret’s Bay, Nova Scotia. From the original profiles, derived contour plots, and spectral analysis of the series, it appears that the temporal changes in the vertical structure resulted mainly from tidal advection. Of the several simple parameters examined, the average chlorophyll and the maximum chlorophyll over the profile were the best indices of changes in the vertical structure. The most commonly used parameter, chlorophyll concentration at a fixed depth, is shown to be readily contaminated by internal waves and therefore makes a poor indicator of changes representative of the whole chlorophyll layer.
Seasonal variation in temperature, salinity, and density over the continental shelf off Oregon1
Authors: Huyer Adriana
Published: March 2010

Seasonal variations in the hydrography of the waters over the continental shelf off Oregon were observed in a set of hydrographic data collected along 44°39′N at intervals of a few weeks to a few months from 1961 through 1970. The temperature is determined only partly by the local heating and cooling cycle: at the surface it is low (9°C) in winter, increasing in spring, lowest in summer, highest in early fall, and decreasing in winter; near the bottom, it is highest in winter and lowest in summer. The summer minimum is associated with coastal upwelling and a strong southward geostrophic current. Variations in salinity are governed by runoff, both locally and through the Columbia River effluent, as well as by coastal upwelling and advection. Neither temperature nor salinity is negligible in determining sigma‐t. In summer, sigma‐t decreases with distance offshore, and isopyenals slope downward from shore; in winter, sigma‐t increases with distance offshore, and isopyenals slope upward from shore. Steric sea level also slopes downward from the coast in winter, and upward in summer. Alongshore geostrophic flow is southward in summer and northward in winter. The variations in temperature, salinity, and sigma‐t are caused by seasonal cycles in the surface heat balance, precipitation and runoff, the local wind, and the alongshore flow.
The dynamics of aquatic systems. 2. The effects of nutrient enrichment on model plankton communities1,2
Authors: Lam Patricia , Levins Richard
Published: March 2010

When results of laboratory experiments on the effects of nutrient enrichment of algal cultures are extrapolated to field conditions, the predictions of the experiments are seldom fulfilled, because the behavior of a species in a network of interacting variables in nature is quite different from its behavior under controlled conditions.

The method of loop analysis is used to demonstrate the properties of a set of models containing three kinds of algae and three kinds of nutrients. Many unexpected effects develop from the interactions within the network, and one‐link physiological effects cannot be extrapolated to ecological situations. For these situations, it is recommended that Liebig’s law of the minimum be replaced by a more holistic approach.
Feeding behavior of Calanus pacificus in mixtures of food particles1
Authors: Frost Bruce W.
Published: March 2010

The hypothesis was proposed that apparent size‐selective feeding by copepods is not behaviorally determined. The hypothesis was tested by feeding adult females of Calanus pacificus pairs of single‐celled diatoms of different sizes and comparing predicted and observed clearance rates on the two sizes of cells. In 24 experiments, representing a broad range of relative proportions of two sizes of cells, individual abundances of two sizes of cells, and absolute abundance of food, C. pacificus invariably filtered the large cell at a higher rate than the small cell. This suggested a strong passive or mechanical component to apparent size‐selective feeding in C. pacificus. Measurements of clearance rates of the copepod on different size‐classes of single diatom species and of feeding behavior of copepods in suspensions containing several sizes of plastic spheres and diatoms supported this interpretation. It is concluded that C. pacificus differentially filters particles of different sizes and that the mechanism is purely mechanical, reflecting variable retention efficiency of the second maxillae for particles of different sizes. That is, the copepod indiscriminantly filters suspensions of food particles, but captures, handles, and ingests large particles more efficiently than small particles.
Dissolved amino acids in the equatorial Pacific, the Sargasso Sea, and Biscayne Bay1
Authors: Lee Cindy , Bada Jeffrey L.
Published: March 2010

Seawater samples from several depths in the Sargasso Sea and equatorial Pacific and from surface stations in Biscayne Bay were analyzed for dissolved free amino acids and dissolved combined amino acids by a ligand‐exchange chromatography technique. Enantiomeric ratios of dissolved total amino acids from Atlantic and Pacific samples were also determined. On the basis of these ratios, a bacterial source is postulated for the origin of the dissolved d‐amino acids in seawater. The possible contributions from chemical racemization are compared to biological production as a source for these d‐amino acids.
Diel changes in sedimentation characteristics of Ditylum brightwelli: Changes in cellular lipid and effects of respiratory inhibitors and ion‐transport modifiers1
Authors: Anderson Lars W. J. , Sweeney Beatrice M.
Published: March 2010

Temperature‐controlled seawater columns were used to investigate settling rates of Ditylum brightwelli grown on light‐dark schedules. Ficoll density gradient centrifugation was used to examine the effects of KCN, DNP, and the ion‐transport modifiers valinomycin, nigericin, and gramicidin on sedimentation characteristics in the gradients. Sedimentation rates were minimal at the end of the dark period (L8: D16; L12: D12) and maximal during the latter half of the light period. The presence of maximum lipid per cell during the period of maximum settling rate argues against a fat‐mediated buoyancy mechanism. Cells exposed to respiratory inhibitors, valinomycin, or nigericin sedimented more rapidly than did control cells; gramicidin appeared to decrease sedimentation rate. The effectiveness of these agents suggests that settling rate in this diatom is controlled through ion regulation.
Quantitative sampling of demersal plankton migrating from different coral reef substrates1
Authors: Porter James W. , Porter Karen Glaus
Published: March 2010

Continuous quantitative sampling of demersal zooplankton rising from a Philippine coral reef reveals a distinct pattern of nocturnal vertical migration. Demersal plankton live within the reef by day and migrate into the water column by night. The amount of plankton rising from specific reef substrates is significantly related to the degree of three‐dimensional structure of the substrates: branching coral provides the most demersal plankton and sand the least. Coral rubble resulting from dynamite fishing is comparable to sand in its plankton production.