bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen fixation in Clear Lake, California. 3. Repetitive synoptic sampling of the spring Aphanizomenon blooms1
Authors: Home Alexander J. , Sandusky James C. , Carmiggelt Coen J. W.
Published: March 2010

Nitrogen fixation (as acetylene reduction) and factors most likely to influence it were estimated simultaneously for 31 sites at eight stages of the 1971 and 1972 spring blooms of Aphanizomenon in naturally eutrophic Clear Lake. The major factor controlling rates of N2 fixation was the number of Aphanizomenon heterocysts (P < 0.001). Environmental influences on fixation were largely mediated through heterocyst induction or repression. Regression analysis showed heterocysts highly negatively related to NO3 (P < 0.05). At high (linear regressions) but not at low (log‐transformed regressions) numbers, heterocysts were positively correlated with phosphate (P < 0.05). At low rates of N2 fixation, heterocysts were also positively related to water clarity, chlorophyll (both P < 0.05), and temperature (P < 0.01). The role of very low levels of nitrate (2–22 µg·liter−1 NO3‐N) in (apparently) indirectly suppressing heterocyst induction was unexpected. Only at high rates was N2 fixation correlated with phosphate. Presumably at low rates sufficient phosphorus is available in this P‐rich lake (14– 43 µg·liter−1 PO4‐P) to permit repression of heterocyst formation by low NO3 levels. Ammonium suppressed N2 fixation and heterocyst formation only where it was present in relatively large quantities (20–170 µg·liter−1 NH4‐N). Early in the blooms, low rates of vegetative (i.e. nonheterocyst) N2 fixation were indicated in the “flake” colonies of Aphanizomenon. These may have an anoxic center like that of Trichodesmium.
Nitrogen fixation in Clear Lake, California. 4. Diel studies on Aphanizomenon and Anabaena blooms1
Authors: Horne A. J.
Published: March 2010

Day and night measurements of N2 fixation (as acetylene reduction) were made during spring blooms of Aphanizomenon flos‐aquae and two autumn blooms of Anabaena spp. From 9 to 23% of the 24‐h fixation occurred between 1100 and 1300 hours. Nitrogen fixation in spring showed complex, physically shallow but optically deep and mobile subsurface peaks of nitrogenase activity, which were totally unrelated to Aphanizomenon biomass but may have been due to diel changes in light penetrating the relatively clear water. Nocturnal fixation was uniformly distributed with depth and accounted for ⅕ to of daylight fixation. In more turbid autumn waters, the pattern of N2 fixation for Anabaena blooms was simpler, with a surface (or near‐surface) peak decreasing with depth. Nocturnal fixation was more uniformly distributed with depth. The difference in fixation patterns between the two species is attributable to the interactions of oxygen with the nitrogenase enzyme system. The diel changes in nitrogenase activity suggest a need to establish whether the precursors of nitrogenase accumulate in an oxygen‐stable form.
The productivity of San Cristobal Reef, Puerto Rico
Authors: Rogers Caroline S.
Published: March 2010

San Cristobal Reef, Puerto Rico, was the site of a community metabolism study based on a new upstream‐downstream method with experimental channels 4 m deep. Net productivity rates varied from 0.03 to 1.85 g O2·m2 reef area · h−1 (x̄ = 0.39; n = 59). Respiration measurements of one reef section from which light was excluded ranged from 0.26 to 0.48 g O2·m−2 reef area·h−1. The linear regression equation y = 0.58x − 0.18, where y = g O2·m−2 reef area·h−1 and x = mEin·m−2·s−1, describes the correlation between light and metabolism at this site. Net primary productivity was 2.45 g O2·m−2 reef area and gross primary productivity 5.42. The ratio of gross primary productivity to 24‐h respiration was 0.7. Productivity rates of this heterotrophic zone are lower than those reported for shallower reef zones with greater algal cover.
Ammonium adsorption in nearshore anoxic sediments1
Authors: Rosenfeld Jeffrey K.
Published: March 2010

The distributions of dissolved, exchangeable, and fixed ammonium were measured in sediment cores from Long Island Sound, Florida Bay, and Pettaquamscutt River, Rhode Island, and in laboratory experiments to determine the importance of ammonium adsorption in anoxic sediments. Apparently, a “dynamic equilibrium” exists between dissolved, exchangeable, and fixed ammonium in sediments. The concentration of exchangeable ammonium increased linearly with increasing concentrations of dissolved ammonium; exchangeable ammonium adsorption was rapid, reversible, and predominantly associated with the organic matter rather than the clay minerals. The concentration of fixed ammonium also increased with increasing concentrations of dissolved ammonium, but this change, due to diagenesis, is small compared to the total fixed ammonium in sediments and is also smaller than the corresponding increase in exchangeable ammonium. The ammonium adsorption coefficient for Long Island Sound sediment was between one and two: of the ammonium produced by organic matter decomposition, as much or twice as much is associated with the sediment as is dissolved in the interstitial water. Therefore, ammonium adsorption by sediments is an important process in the diagenesis of nitrogen in nearshore anoxic sediments.
The effect of flow patterns on uptake of phosphorus by river periphyton
Authors: Lock Maurice A. , John Peter H.
Published: March 2010

The effect of various flow patterns on the uptake of 32P by river periphyton was examined in a laboratory flume. In general, water movement increased 32P uptake, except where the phosphorus demand of the microorganisms was presumably satisfied by molecular diffusion at high phosphorus concentrations (105 µg·liter−1 PO4‐P). However, there was little difference in 32P uptake between the several distinct flow regimes produced by increasing or decreasing velocity and turbulence associated with a hump and hydraulic jump. It appears that the threshold limit for water movement, after which no further stimulation occurs, is ⩽5.4 cm·s−1, the lowest velocity tested. A reduction in 32P uptake by formaldehyde‐killed films of periphyton indicated that 50–75% of the uptake of the untreated films was due to biological activity.
Combined measurement of oxygen and sulfide in water samples
Authors: Ingvorsen Kjeld , Jorgensen Bo Barker
Published: March 2010

A method is described for chemical determination of oxygen and sulfide in the same water sample. Sulfide is first separated by precipitation with zinc hydroxide, oxygen then determined by the Winkler technique in the clear supernatant. The mutual interference between the oxygen and the sulfide determinations is <1–2%. The method has proven useful for field applications: as an example, the diurnal variation in oxygen and sulfide of a shallow lagoon is presented.
Determination of sulfate in seawater and natural brines by 133Ba and membrane dialysis
Authors: Seyfried William E. , Rosenbauer Robert J. , Rischoff James L.
Published: March 2010

Dissolved sulfate is determined by precipitation with the radioisotope 133Ba and counting of the precipitate on a scintillation counter. Precipitation is carried out in dialysis bags; excess 133 Ba is removed via diffusion by soaking the bags in distilled water for 12 h, and the bags are then placed directly in the well of the scintillation counter. The procedure eliminates previous errors caused by washing and transferring of the precipitate and permits analysis of 0.5–3,000 µg·ml−1 sulfate in a 1.0‐ml sample. The detection limit is increased by simply increasing the sample volume up to 5.0 ml. The technique is interference‐free in natural waters ranging from freshwater to brines of 1.5 times the salinity of seawater.
Sorption of ammonium by glass frits and filters: Implications for analyses of brackish and freshwater
Authors: Eaton Andrew D. , Grant Virginia
Published: March 2010

Glass support frits for 47‐mm Millipore filter holders rapidly adsorb up to 600 nmol of ammonium from fresh or brackish waters (salinity <5‰). Certain glass‐fiber filters may also adsorb at least 200 nmol of ammonium. The adsorbed ammonium is released on contact with higher salinity or high K+ waters. Distilled deionized water is not an effective cleaning agent for the frits and filters, but either seawater or 2 mM K+ solution is efficient. Significant analytical errors can occur if one does not compensate for the effect by rinsing with copious amounts of sample before collection of water for analysis, by adding K+ to samples at levels of 2 mM or greater to reduce sorption, or by silanizing frits and filters to block sorption.
A relation between lake morphometry and primary productivity and its use in interpreting whole‐lake eutrophication experiments
Authors: Fee Everett J.
Published: March 2010

Rates of primary production during the ice‐free season expressed per unit volume of epilimnion were linearly related to the ratio of epilimnion sediment area to epilimnion volume in unfertilized lakes in the Experimental Lakes Area (ELA), northwestern Ontario. This ratio is mathematically equivalent to the probability of retention of sedimenting particles in the epilimnion of a lake divided by the mean depth of the epilimnion and is a measure of the nutrient recycling rate of a lake. Evidence indicates that epilimnetic nutrient recycling in ELA lakes is dominated by processes occurring at the sediment‐water interface and not within the sediment. The relationship between the ratio of sediment area to epilimnion volume and primary production is used as the basis for interpreting whole‐lake eutrophication experiments. In comparison to control lakes, the ratio of production to chlorophyll in the experimental lakes was high when chlorophytes dominated and low when cyanophytes dominated. Lakes that were fertilized with both nitrogen and phosphorus had much higher chlorophyll concentrations and productivities than control lakes. Lakes that received either of these nutrients alone showed weaker responses. Both elements appear to be in short supply relative to the metabolic requirements of phytoplankton. Phosphorus control is still the key to controlling eutrophication.
Atmospheric enhancement of metal deposition in Adirondack lake sediments1
Authors: Galloway James N. , Likens Gene E.
Published: March 2010

Sediment cores were collected from Woodhull Lake (Adirondack State Park, New York) in July 1975. Of 44 metals analyzed by neutron activation and atomic absorption spectrophotometry, 9 (Ag, Au, Cd, Cr, Cu, Pb, Sb, V, and Zn) showed increased rates of deposition in the last 30 years. These increases are attributed to increased rates of atmospheric deposition. Similar results were obtained from cores of Honnedaga Lake (Adirondack State Park, New York) and Lake of the Clouds (Mt. Washington, New Hampshire).
The 210Pb chronology of a core from Mirror Lake, New Hampshire1
Authors: Von Damm Karen L. , Benninger Lurry K. , Turekian Karl K.
Published: March 2010

A core from Mirror Lake (New Hampshire) was analyzed in detail for 210Pb and other members of the uranium decay series. The core shows periods of episodic redistribution and deposition of contemporaneously deposited indigenous lake sediment to the site interspersed with periods of constant sediment accumulation at an average rate of 0.16 cm·yr−1. 226Ra does not provide a reasonable chronometric tool in this lake.
Cadmium incorporation by the marine copepod Pseudodiaptomus coronatus1
Authors: Sick Lowell V. , Baptist Garry J.
Published: March 2010

Pseudodiaptomus coronatus, after exposure to phytoplankton and cadmium in concentrations like those in temperate, coastal environments, incorporated 109Cd at higher rates from ambient water than from phytoplankton food. When ambient stable cadmium concentrations were increased from 0.03 to 1.00 µg·liter−1, cadmium concentration by phytoplankton cells increased and the rate of cell ingestion by P. coronatus decreased. This inverse relation between the accumulation of cadmium in phytoplankton cells and the animal’s ingestion rate resulted in relatively small net increases in the cadmium accumulated from phytoplankton by copepods.

Rates of stable cadmium ingestion for P. coronatus ranged from 0.18 to 0.38 ng·mg animal dry wt−1·h−1, depending on the initial algal cell density and the ambient cadmium concentration. For cadmium concentrations of 0.03 to 1.00 µg·liter−1, percentage assimilation efficiencies ranged from 13.20 to 68.40. Both rates of cadmium ingestion and assimilation efficiencies were higher than published values for carnivorous zooplankton.
Functionally distinct classes of complex phosphorus compounds in lake water1
Authors: Francko David A. , Heath Robert T.
Published: March 2010

Complex phosphorus compounds were classified functionally according to the manner by which orthophosphate was released. Filtrable phosphorus compounds in two eutrophic lakes (East and West Twin lakes) and a humic bog (Crazy Eddie Bog) in northeastern Ohio were fractionated by anion‐exchange and gel‐filtration chromatography. Fractions were analyzed for soluble reactive phosphorus and total dissolved phosphorus; absorbance at 400 nm was used as a measure of filtrable “yellow acids.” The eutrophic lakes contained numerous low molecular weight compounds which were resistant to low‐dose ultraviolet irradiation but readily released orthophosphate upon treatment with alkaline phosphatase. Filtrable phosphorus compounds of the humic bog were predominantly high molecular weight, cochromatographed with the yellow acids in each fractionation procedure, and resisted enzyme hydrolysis, but released orthophosphate upon irradiation with low doses of ultraviolet light.
Biological production and the exchange of oxygen and carbon dioxide across the sea surface in Stuart Channel, British Columbia1
Authors: Johnson Kenneth S. , Pytkowicz Ricardo M. , Wong C. S.
Published: March 2010

The rates at which concentrations of oxygen and carbon dioxide in Stuart Channel changed due to biological production and to exchange with the atmosphere were determined from measurements of the simultaneous changes in oxygen, pH, and titration alkalinity over a 15‐day period in July 1976. Carbon dioxide was consumed by plankton at a rate of 10.8 µmol CO2·liter−1·d−1.CO2 entered the surface layer by atmospheric exchange at a rate of 0.49 µmol CO2·liter−1·d−1. The piston velocity was calculated to be 2.2 × 10−3 cm·s1. Oxygen was produced at a rate of 14.1 µmol O2·liter1·d−1, due to photosynthetic activity. The rate of oxygen loss to the atmosphere was 9.8 µmol O2·liter−1·d−1. The piston velocity was 1.6 × 10−3 cm·s−1.
Nitrate and phytoplankton production in southern California coastal waters1
Authors: Eppley R. W. , Renger E. H. , Harrison W. G.
Published: March 2010

The transport of nitrate into the euphotic zone appears to be a major factor regulating the standing stock and production of phytoplankton in southern California coastal waters. The evidence is as follows. 1) The rate of photosynthetic carbon assimilation is proportional to the rate of nitrate assimilation and to the ratio of nitrate:total N assimilated. 2) The phytoplankton standing stock (g C·m−3) and its production rate are related to the depth of the vertical nitrate concentration gradient. 3) The chemical composition of the particulate organic matter, as the POC:PON ratio, is related to the carbon:nitrogen assimilation ratio of the phytoplankton. 4) Regenerated production, measured as ammonium assimilation, is proportional to the nitrate assimilation rate, implying parallel and concurrent increases in the production of heterotrophic microplankton and phytoplankton attending new inputs of nitrate into the euphotic zone. 5) The vertical diffusion of nitrate, when calculated from the vertical nitrate concentration gradients and nitrate assimilation rates, appears to give reasonable estimates of the vertical eddy diffusivity coefficient for nitrate.
Ammonium distribution in southern California coastal waters and its role in the growth of phytoplankton1
Authors: Eppley Richard W. , Render E. H. , Harrison W. G. , Cullen J. J.
Published: March 2010

The average concentration of ammonium in the euphotic zone of the Southern California Bight was about 0.35 µg‐atom·liter−1 in 1974–1977. Concentrations up to 5–20 µg‐atoms ·liter−1 were found in Santa Monica Bay surface and bottom waters. Elsewhere maximum concentrations were 2–3 µg‐atoms·liter−1 at the bottom of the euphotic zone of inshore stations.

Ammonium provided an average of 35% of the nitrogen assimilated by the phytoplankton and a much higher proportion in Santa Monica Bay. The rate of ammonium assimilation was modified primarily by the phytoplankton standing stock, and also by ambient concentration of ammonium, temperature, irradiance, and the carbon:chlorophyll a ratio of the phytoplankton. These variables accounted for 52% of the explained variance in three “winter” cruises and 83% in a summer cruise. Remineralization processes account for most of the ammonium in the bight, while human inputs account for about 10%.
1
Authors: Glover Hilary E. , Morris Ian
Published: March 2010

Measurements of ribulose‐1,5‐bisphosphate carboxylase (RUBPCase) and phosphoenolpyruvate carboxylase (PEPCase) in several phytoplankton cultures and natural phytoplankton populations showed a positive correlation of photosynthesis with RUBPCase activity but not with PEPCase activity. Observed ratios of RUBPCase:PEPCase were high in log phase cultures when photosynthesis was maximal and low in stationary phase. There was no significant correlation between photosynthesis and the ratio of RUBPCase:PEPCase activity in natural populations. The rate of carbon assimilation by the intact algae was significantly greater than that by the isolated carboxylases. In both natural phytoplankton populations and laboratory cultures, the ratio of photosynthesis:carboxylase activity depended on the physiological state of the cells, being greatest when the photosynthetic rate was highest.
The effect of incomplete recovery of large particles from water samplers on the chemical composition of oceanic particulate matter1
Authors: Calvert S. E. , McCartney M. J.
Published: March 2010

The incomplete recovery of large suspended particles from Niskin water sampling bottles, due to the positioning of the bottom spigots, results in underestimation of the major element concentrations in oceanic particulate material. Moreover, the effect varies for different elements; Si and Ca, elements present predominantly in large biogenic particles, are more concentrated in samples settling below the spigots.
Enclosed chambers for the convenient reverse flow concentration and selective filtration of particles1
Authors: Hinga Kenneth R. , Davis Paul G. , Sieburth John McN.
Published: March 2010

Enclosed chambers for reverse flow concentration allow convenient and gentle concentration of particles for a wide variety of purposes, including routine 1,000× concentrations of oceanic particles. The recovery of viable organisms from the enclosed concentrators is considerably greater than in previously used reverse flow techniques.
Measurements of mineralization of phytoplankton detritus in an oligotrophic lake1
Authors: Cole Jonathan J. , Likens Gene E.
Published: March 2010

Rates of mineralization (decom position) were determined by monitoring [14C]CO2 evolved from microbial respiration of naturally occurring particulate and dissolved phytoplankton material labeled with 14C. Added substrate concentrations approximated in situ levels. The design of the incubation bottle and [14C]CO2 trapping system provided a method for measuring mineralization rates in intact microbial communities under in situ temperatures and dissolved gas concentrations without extreme experimental manipulations.

In short term incubations, bacteria appear to be the major agents of phytoplankton decomposition.
Amazon lakes: Water storage and nutrient stripping by algae1
Authors: Fisher Thomas R. , Parsley Patricia E.
Published: March 2010

During the annual 10‐m rise in water level, water from the Amazon River floods into bordering nutrient‐poor lakes, and river‐derived nitrate (12 µM) and phosphate (0.9 µM) are utilized during intense phytoplankton growth. The influence of the nutrient‐rich water appears to extend laterally in a 50‐km band, creating a ribbon of highly pro ductive lakes along its length that, in turn, may have a significant impact on Amazon water chemistry.
Ceratium in Fire Island Inlet, Long Island, New York (1971‐1977)
Authors: Weaver Sylvia S.
Published: March 2010

Documentation of the occurrence of the dinoflagellate Ceratium tripos (O. F. Muller) Nitzsch, at Fire Island Inlet from 1971 through 1977 provides a perspective for its 1976 mid‐Atlantic coastal bloom.
A chemostat device adapted to planktonic Oscillatoria cultivation1
Authors: Feuillade Jacques , Feuillade Mauricette
Published: March 2010

Differences between cell densities in the growth vessel and in the effluent samples when planktonic Oscillatoria is cultivated in continuous cultures may be avoided by use of a simple all glass growth vessel as a chemostat. The device ensures long axenic cultivation and reproducible results with good mixing and no wall growth.
Arctic Bosmina morphology and copepod predation1
Authors: O'Brien W. John , Schmidt David
Published: March 2010

There are significant morphological differences between populations of Bosmina longirostris in an arctic lake without the planktivorous Heterocope septentrionalis and in a nearby lake which has this predator. Predation experiments demonstrated that Bosmina from the lake without Heterocope was more vulnerable to Heterocope predation than similar‐sized animals from the lake containing the predator.
Predation by Noctiluca miliaris Souriray on Acartia tonsa Dana eggs in the inshore waters of southern California
Authors: Kimor Baruch
Published: March 2010

Predation by Noctiluca miliaris on Acartia tonsa eggs off the coast of southern California in March 1976 appeared to take place mainly in the upper 20 m where Noctiluca was most abundant. Noctiluca miliaris, in spite of its nonselective feeding pattern, at times may exert an important influence on the A. tonsa population.
DNA polymerase activity and growth rates in Artemia salina nauplii1
Authors: Sapienxa Carmen , Mague Timothy H.
Published: March 2010

In 14 experiments with Artemia salina nauplii, the specific activity of DNA polymerase was positively correlated with the rate of increase of protein in this organism.
Respiratory electron transport activities in phytoplankton and bacteria: Comparison of methods1
Authors: Christensen J. P. , Packard T. T.
Published: March 2010

Six methods of measuring the activity of the respiratory electron transport system (ETS) were intercalibrated using cultures of algae and bacteria and natural plankton assemblages from Lake Washington and Puget Sound. The ETS methods fall into a group that uses the detergent Triton X‐100 and a group that does not. Within either group, the methods yielded similar results. Between the groups, the results differed 4–10‐fold, the detergent‐containing methods having the greater activity. Conversion tables are given to compare the results of one assay with another. The results show that differences in the published relationships between ETS activity and respiration in phytoplankton‐dominated plankton samples are largely explained by methodology.
A versatile, interchangeable chamber seawater sampler1,2
Authors: Gagosian Robert B. , Dean Jerome P. , Hamblin Robert , Zafiriou Oliver C.
Published: March 2010

A 30‐liter seawater sampling device which can be lowered closed through the sea‐air interface is designed to allow for interchangeable containers so that aluminum or glass cylinders for organic analyses can be replaced by PVC or other plastics for trace metal analyses.
Estimating cladoceran birth rates: The importance of egg mortality and the egg age distribution1
Authors: Threlkeld Stephen T.
Published: March 2010

Three models of egg hatching in zooplankton populations gave significant differences depending on whether egg mortality was included. The differences were due to the effect of adult mortality on reducing the probability that eggs survive from the time of laying until they are released as live young. Adult mortality results in a population of eggs disproportionately dominated by younger stages, with resulting recruitment rates being lower than expected from development times alone.

A technique based on the relative duration of various developmental stages was used to determine the age of eggs from two natural populations during periods of decline. The observed tendency for the age distribution of eggs to be dominated by younger eggs was as expected from models of egg hatching which included mortality but was not as expected from models of declining populations which did not incorporate egg mortality.
Species‐specific factors affecting predator‐prey interactions of the copepod Acanthocyclops vernalis with its natural prey
Authors: Li Judith L. , Li Hiram W.
Published: March 2010

Experiments of prey selection by Acanthocyclops vernalis demonstrate that many factors govern this process. Evidence from search and handling times required for complete consumption, behavioral observations, and carapace wound examinations indicated that body shape, carapace integrity, and mode of swimming were major influences on the selective process. Soft‐bodied species were quickly and completely consumed; others were more difficult to handle and some of these were rejected. Escape strategies were different for each prey species, and the success of escape depended in part upon swimming direction relative to the mode of horizontal attack by Acanthocyclops. Size affects all of these characteristics because of correlative relationships to body allometry, carapace integrity, and swimming speed.
Upwelling and estuary flushing1
Authors: Duxbury Alyn C.
Published: March 2010

Salinity data collected during 1965–1969 in Grays Harbor, Washington, along with river discharge data, were used to determine the water and salt budgets of the inner harbor. The fluxes of water at the seaward end of the inner harbor, To seaward at the surface and Ti inward at depth, were calculated. To was proportional to but larger than the river discharge throughout the year except for the months of August through October, when To was related to Ti and Ti was driven by the influx of dense water into the harbor caused by upwelling along the coast. Thus the flushing rate of the inner harbor, as determined by its volume divided by To, is much greater during late summer than previously suspected. The calculated rate of removal of material associated with the water in the inner harbor, based on a To derived from river flow and the percentages of river and harbor water making up To, is 19% per day, in agreement with a previous flushing study.
Seasonal changes in the spectral composition of downwelling irradiance in Lake Kinneret (Israel)1,2
Authors: Dubinsky Zvy , Berman Thomas
Published: March 2010

A submersible scanning radiometer was used to measure seasonal variations in the intensity and spectral characteristics of downwelling irradiance in Lake Kinneret, Israel. Extinction coefficients for photosynthetically active radiation (350–750 nm) varied from 0.2 to 3.3 ln units·m−1, the euphotic zone (1% of light energy at surface) ranged from 1.7 to 11 m.

Specific extinction coefficients of chlorophyll, kc (ln units mg−1·n−2), and water kw (ln units·m−1) were dependent on the wavelength at which they were measured (at 650 nm, kc = 0.011, kw = 0.693; for 350 to 750 nm, kc = 0.007, kw = 0.489). High concentrations of chlorophyll and other cell pigments during the annual Peridinium bloom strongly attenuated light penetrance and caused a spectral shift toward the red to give elevated quantum to joule (Q:W) ratios (2.96 × 1018)
The production and fate of phytoplankton size fractions in the plume of the Hudson River, New York Bight1
Authors: Malone Thomas C. , Chervin Mira B.
Published: March 2010

Seasonal effects of water column stability, phytoplankton growth, and copepod grazing on the biomass of phytoplankton size fractions are described in the context of variations in particulate organic carbon (POC). Net plankton biomass was more variable in time (between weeks and months), while nanoplankton biomass was more variable in space (between surface and bottom layers and between stations). Biomass was highest and most uniformly distributed during February–March when net plankton diatoms dominated and doubling times approximated the flushing time of the plume. Biomass declined rapidly with depth and distance from the mouth of the estuary during June–July when nanoplankton dominated and doubling times were short relative to the flushing time of the plume. Variations in POC were well correlated with phytoplankton biomass when net plankton dominated and biomass was limited by sinking and mixing. When nanoplankton dominated, biomass was limited mainly by grazing and correlations between POC and biomass were poor. It appears that most of the biomass produced by net plankton diatoms sinks from the surface layer before the summer thermocline develops, while most of the biomass produced by nanoplankton during the summer enters pelagic food chains before sinking from the surface layer.
Distribution of suspended bacteria in neritic waters south of Long Island during stratified conditions1
Authors: Ferguson Randolph L. , Palumbo Anthony V.
Published: March 2010

Bacteria (direct counts) averaged 1.85 × 106 cells·m1−1 in highly stratified waters south of Long Island during September 1976. The vertical distribution of bacteria was related to the location of the thermocline and the bottom, the horizontal distribution to distance from shore indicating longshore continuity. The average numbers of bacteria (× 106 cells·ml−1) in neritic water were 2.14 nearshore, 1.96 midshelf, and 0.67 near the shelf break.

Overall the number of bacteria was positively correlated with chlorophyll and ammonium concentrations but not with measurements of heterotrophic activity. The location of a large, relatively inactive population of bacterial cells near the surface of the highly stratified midshelf water corresponds to the approximate location of unusually persistent phytoplankton blooms observed during March–June 1976.
Denitrification in a salt marsh ecosystem1
Authors: Kaplan Warren , Valiela Ivan , Teal John M.
Published: March 2010

The rate of denitrification measured throughout the year in various habitats of a New England salt marsh was correlated to temperature and was highest in the wettest habitats. Over 60% of the denitrification took place in the muddy creek bottoms. Annual denitrification exceeds nitrogen fixation. An amount of nitrate similar to the quantity consumed by denitrifiers is supplied by the flow of groundwater into the marsh and by nitrifiers within the marsh itself.
Chemical aspects of a brine pool at the East Flower Garden bank, northwestern Gulf of Mexico1
Authors: Brooks James M. , Bright Thomas J. , Bernard Bernie B. , Schwab Claude R.
Published: March 2010

A small pool on the flank of the East Flower Garden bank at a depth of 72 m in the Gulf of Mexico contains anoxic, hypersaline (∼200 g·kg−1) water. The flux of brine into and out of the pool contributes to erosional processes on the bank. The bulk ionic composition of the brine is similar to that of the Orca Basin brine, but differences between the two in gaseous hydrocarbon and carbon isotope content indicate different modes of origin. High levels of bacterial activity in the brine are indicated by ATP (>80 ng·liter−1), hydrogen sulfide (>2,000 µmol·liter−1), isotopically light ∑CO2 (δ13C = −23%), and the apparent generation of elemental sulfur.
Microbial dark assimilation of CO2 in the Cariaco Trench1
Authors: Tuttle Jon H. , Jannasch Holger W.
Published: March 2010

Dark assimilation of carbon dioxide has been measured in water from the oxygen‐sulfide interface and the deep anoxic zone in the Cariaco Trench. Comparison of rates of interface‐associated dark assimilation with primary production and organic carbon flux to the deep anoxic water indicates that chemoautotrophic sulfur bacteria cannot be wholly responsible for carbon dioxide assimilation at the observed magnitude. It is suggested that dark assimilation of carbon dioxide near the interface chiefly represents the metabolic activities of facultatively and obligately anaerobic bacteria which use inorganic sulfur compounds as electron acceptors, and sulfide or thiosulfate‐oxidizing bacteria whose growth is dependent upon organic carbon.
Measurement of phytoplankton growth by particle counting
Authors: Sheldon R. W.
Published: March 2010

Growth of phytoplankton in the presence of detritus will follow an asymptotic function. It is theoretically possible to estimate the phytoplankton and detrital standing stock and the phytoplankton growth rates from serial measurements of particle concentration, but the measurements must be very precise, and in practice this is rarely attainable. Small errors in measurement produce large errors in the plankton and detrital estimates. To measure phytoplankton growth, the phytoplankton must be identified relative to its place on the size spectrum. Within a restricted size range particle growth is exponential and represents phytoplankton growth.
Microbial transformations of sulfur compounds in a stratified lake (Solar Lake, Sinai)1
Authors: Jorgensen Bo Barker , Kuenen J. Gijs , Cohen Yehuda
Published: March 2010

Microbiological and chemical aspects of the sulfur cycle were studied in the chemocline of a tropical salt lake. Oxygen and sulfide coexisted in a 0–10‐cm layer which migrated up and down during a diurnal cycle. Sulfide was rapidly oxidized by oxygen, with a half‐life of 5–10 min, to produce mainly sulfate and thiosulfate. Thiosulfate and elemental sulfur had concentration maxima in the chemocline while polysulfide was abundant throughout the sulfide zone. Radiotracer experiments showed that the elemental sulfur was produced by anoxygenic photosynthesis in cyanobacteria. The elemental sulfur was further oxidized or again reduced, depending on the presence or absence of oxygen. Cyanobacteria in the chemocline shifted between anoxygenic photosynthesis in the morning and oxygenic photosynthesis in the afternoon. A high dark CO2 fixation was found in the chemocline which could be stimulated by sulfide, elemental sulfur, and thiosulfate. The oxidation rate of sulfide in the chemocline was dependent on the presence of bacteria.
Release of weak and strong copper‐complexing agents by algae1
Authors: McKnight Diane M. , Morel Francois M. M.
Published: March 2010

By means of potentiometric titrations, the copper‐complexing properties of organic compounds released by 21 algal species are characterized. Most eucaryotic species released measurable amounts (10−6 M) of copper‐complexing agents that could be modeled as weak organic acids with log{*KCuL} = 0.5. Of seven blue‐green algal species studied, four produced about 5 × 10−7 M concentrations of strong copper‐complexing agents with conditional stability constants in the range 108 to 1012; two produced complexing agents similar to those produced by the eucaryotes. In time‐course experiments with three chlorophytes and two cyanophytes, the release of measurable concentrations of copper‐complexing agents occurred principally during stationary phase.
The transport and budget of sterols in the western North Atlantic Ocean1,2
Authors: Gagosian Robert B. , Nigrelli Gale E.
Published: March 2010

A general correlation exists between total free sterols, particulate organic carbon, particulate organic nitrogen, and chlorophyll a in the upper 300 m of the water column in the western North Atlantic Ocean. High values are found in shelf waters and in the subsurface chlorophyll a maximum in the Sargasso Sea, lower values at a Gulf Stream meander or ring fringe station.

A diatom sterol, 24‐methylcholesta‐5,22‐dienol, appears to be produced only within the euphotic zone. Below this, consumption or removal processes dominate and the concentration of this compound decreases with depth. On the other hand, a zooplankton sterol, cholesterol, occurs throughout the water column, exhibiting maxima at the base of the mixed layer and at depths where particles tend to accumulate because of favorable chemical or density gradients.

Flux calculations show that at most 0.05–0.3% of the sterols produced by phytoplankton in Sargasso Sea surface waters is deposited to the ocean floor. The sterol residence time (the average lifetime of a sterol molecule before it is metabolized) in the euphotic zone was calculated to be about 1 month, whereas the deep water residence time is 20–150 years.
Marine snow: Microscale nutrient patches1
Authors: Shanks Alan L. , Trent Jonathan D.
Published: March 2010

Measurements of ammonia, nitrite, nitrate, and phosphate indicate significant differences in nutrient concentrations associated with marine snow from those of the surrounding water. In eight sets of nutrient measurements, ammonia was more concentrated in aggregates in seven sets, nitrite in three sets, and nitrate in one set. Phosphate was more concentrated in one set, but less concentrated in three sets. Aggregates represent nutrient micropatches ranging in size from <1 mm to several centimeters in diameter.
Ingestion rate of a selective deposit feeder in a complex mixture of particles: Testing the energy‐optimization hypothesis1
Authors: Doyle Roger W.
Published: March 2010

A simple, hyperbolic model describes the relationship between the rate at which Corophium volutator (Crustacea: Amphipoda) ingests sediment and the particle‐size spectrum in the sediment. Mixtures of natural sedimentary floc and glass spheres were used in the feeding experiments. Ingestion rate depends not only on the concentration of edible material but also on its composition as measured by the ratio of sphere volume:floc volume. The parameters of the model are therefore functions of the nutritional value of the ingested material, as required by the hypothesis that feeding rate is adjusted to maximize the energy return.
The filter‐feeding rates and particle retention efficiencies of three species of Cyclosalpa (Tunicata, Thaliacea)1
Authors: Harbison G. R. , McAlister V. L.
Published: March 2010

The particle retention spectra of the mucous nets of three species of salps were determined by measuring differences in grazing rates on particles of different sizes with a Coulter Counter. It is pointed out that the only correct method for determining these spectra for an organism feeding in a closed vessel is to compare rates of clearance for each particle size class; if ratios of the quantity ingested to the initial amount in each size class are used, incorrect retention spectra will be produced. Cyclosalpa floridana, Cyclosalpa affinis, and Cyclosalpa polae can all remove particles about 4 µ in diameter and larger with 100% efficiency. Observed differences between species in the retention characteristics of the filtration apparatus can be ascribed to differences in the sizes of the. animals. In general, smaller salps can retain a greater fraction of small particles than can larger ones. Although quantitative differences in the particle retention spectra between generations and species exist, there is little evidence that qualitative differences arc also present. Depending on the abundance of these salps, their grazing impact on particles with diameters as small as 1 µ could be significant.
Zooplankton respiration and its relation to plankton dynamics in two lakes of contrasting trophic state1
Authors: Devol Allan H.
Published: March 2010

The seasonal cycles of respiration of net zooplankton and microplankton were determined for euphotic zones of Lake Washington and Findley Lake. In Lake Washington net zooplankton respiration rates estimated from ETS activity ranged from 22.4 to 1,194 mg O·m−2·d−1 with the maximum occurring during the spring bloom. Net zooplankton respiration rates in Findley Lake ranged from 27 mg O·m−2·d−1 under ice cover to a maximum of 205 mg O·m−2·d−1, which occurred well after the bloom. Respiration rates estimated from ETS activity agreed well with those estimated from zooplankton species abundance. Zooplankton community respiration never exceeded 60% of primary production in Lake Washington; however, in Findley Lake zooplankton community respiration rates exceeded primary production during the latter part of the ice‐free growing season. Phosphorus regeneration rates calculated from zooplankton respiration appeared sufficient to supply most of the phytoplankton phosphorus requirement during summer stratification in Lake Washington.
An evaluation of errors in the 14C method of primary production measurement
Authors: Lean D. R. S. , Burnison B. K.
Published: March 2010

Membrane filtration is an integral part of the 14C method of measuring primary productivity in natural waters. Polycarbonate, cellulose ester, and glass‐fiber filters retain about 0.0003, 0.09, and 0.24 mg water per mm2 surface area. The [14C]bicarbonate in this retained water must be eliminated before the filter is assayed for radioactivity. Air‐drying, desiccator‐drying in the presence or absence of a CO2 absorbant, and oven‐drying are only partially effective decontamination procedures; washing with pH 2 filtered lake water removes most of the contaminating activity. A plot (dpm·filter−1 vs. volume filtered) is used to diagnose the efficiency of decontamination. A simple and safe decontamination procedure is shown to eliminate effectively all residual [14C]bicarbonate activity. Membrane filters are placed in scintillation vials, 0.1–1.0 ml of 0.5 N HCl is added, and, after a 2–3‐h interval, the scintillation fluor is added.
Effects of elevated nitrogen and phosphorus on coral reef growth1
Authors: Kinsey Donald W. , Davies Peter J.
Published: March 2010

Long term phosphate (2 µM) and nitrogen (20 µM urea + ammonium) enrichment of a patch reef at One Tree Island, Great Barrier Reef, caused >50% suppression of reef calcification. This is attributed primarily to the phosphate. It is suggested that this effect is involved, together with algal competition and the more usually accepted depression of temperature, in reducing the growth rate of reefs adjacent to upwellings. It is possible that the effect was more general during the first half of the Holocene transgression.
The application of pattern analysis to freshwater phytoplankton communities1
Authors: Richards Martin C. , Happey‐Wood Christine M.
Published: March 2010

The horizontal distribution of four species of planktonic algae (Asterionella formosa, Tabellaria flocculosa, Chlorella vulgaris, and Chlamydomonas moewussii) growing during summer in surface lake water is described. All showed considerable variation in standing crop. By application of a pattern analysis technique, these surface distributions of algae were shown to be contagious with patterns of horizontal distribution which differed between species in dimensions and intensity. More extensive analysis of the distribution of A. formosa at contrasting times of year showed the existence of pattern in horizontal distribution to be a recurrent phenomenon.
Effects of 22‐µm screens on size‐frequency distributions of suspended particles and biomass estimates of phytoplankton size fractions1
Authors: Malone Thomas C. , Chervin Mira B. , Boardman David C.
Published: March 2010

Fractionation of whole water samples through 22‐µm mesh screens reduced the concentration of particles with mean spherical diameters (MSD) >10 µm. Fractionation did not affect particle concentrations <10 µm when nanoplankton dominated but resulted in an increase when net plankton dominated as a consequence of the breakup of chains. A 50% removal usually occurred at a MSD of 16 µm. Correlations between the chlorophyll a content and volume of size fractions were significant, and nanoplankton had more chlorophyll a per unit volume than net plankton.
The removal of organic surface films by rain1
Authors: Green T. , Houk D. F.
Published: March 2010

Laboratory experiments suggest that natural rainfall can remove organic surface films from a water surface in minutes, or tens of minutes. The removal rate varies with raindrop size and seems to be associated with breaking bubbles, in turn due to the rain.
Alkalinity and pH in the southern Chesapeake Bay and the James River estuary1
Authors: Wong George T. F.
Published: March 2010

The ranges of alkalinity and pH in the southern Chesapeake Bay and the James River estuary were 2.25 meq·liter−1 at 32‰ to <0.85 at salinities below 6‰ and 7.5– 8.3 during the sampling period. Alkalinity is linearly related to salinity in southern Chesapeake Bay. In the James River estuary, the relationship is more complicated as a result of the mixing of various sources of water or the removal of alkalinity. pH values increase with salinity. The variations in pH may be caused by the salinity‐dependence of the apparent dissociation constants of carbonic acid.
Modifications to the Mackereth corer
Authors: Barton C. E. , Burden F. R.
Published: March 2010

The 6‐m Mackereth corer has proved excellent for many aspects of Quaternary research, particularly in the growing field of paleormagnetic work on lake sediments. A 12‐m version of the corer is described together with a magnetic orientation system.
A close‐interval water sampler with minimal disturbance properties
Authors: Blakar Inggard Arne
Published: March 2010

A simple, pneumatically operated multilevel sampler easily constructed of cheap, readily available material is described. Syringes of different volumes can be attached swiftly and interchanged at appropriate intervals. External parts are immovable during filling, thus reducing disruption of microstratifications and keeping contamination of samples to an absolute minimum. The sampler can be used for dissolved gas analyses and multiple bioassay investigations.
A device to hold and identify rock‐filled baskets for benthic sampling in large rivers1
Authors: Page T. L. , Neitzel D. A.
Published: March 2010

A holder with rock‐filled baskets attached at intervals in specific, easily identifiable locations provides a means of benthic sampling under adverse conditions of current and visibility. Two methods of bagging the rock‐filled baskets are described.
A durable, reusable enclosure system that compensates for changing water levels
Authors: Landers Dixon Hamilton
Published: March 2010

Low‐cost enclosures (2‐m diameter) made of UV‐resistant, cross‐laminated polyolefin sheeting reinforced with a grid of twisted polyester filaments have a depth‐compensating capacity from 0.5 to 2.2 m and can be used where water level may fluctuate. Field testing for 126 days showed six such enclosures to be convenient and durable.
Amino acid diagenesis and adsorption in nearshore anoxic sediments1
Authors: Rosenfeld Jeffrey K.
Published: March 2010

Amino acid diagenesis and free amino acid adsorption by sediments were studied in cores of nearshore anoxic sediments from Long Island Sound, Florida Bay, and Pettaquamscutt River (Rhode Island). Both organic nitrogen and amino acid content decreased by a factor of about two in the top meter of the sediment. Individual amino acid profiles showed that the acidic and neutral amino acids, despite their different chemical composition, appeared to be equally utilized in both elastic and carbonate sediments. This result differs from the preferential utilization of certain amino acids generally found in deep‐sea sediments. The results of laboratory adsorption experiments suggest that in clay sediments, free amino acids are predominantly adsorbed by the organic matter in the sediment rather than by the clay minerals. However, in the carbonate sediments, the organic matter seems to inhibit the adsorption of free amino acids on the carbonate grains.