bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of competitive interactions between manganese and copper on cellular manganese and growth in estuarine and oceanic species of the diatom Thalassiosira1,2
Authors: Sunda William G. , Huntsman Susan A. 
Published: April 2010

We investigated the relationship between growth rate and cellular manganese concentrations for an estuarine diatom Thalassiosira pseudonana (clone 3H) and a related oceanic species Thassiosira oceanica (clone 13‐1). Both species were exposed to a matrix of low manganese and cupric ion activities using ethylenediaminetetraacetic acid (EDTA)‐trace metal ion buffered seawater media. The growth rate of Mn‐limited cultures was related to the cellular concentration of Mn, which in turn was directly related to manganese ion activity and inversely to cupric ion activity. The interaction between manganese and cupric ion activities in controlling cellular manganese and growth rate could be explained quantitatively by competitive binding models in which copper competitively blocked either cellular manganese uptake or the binding of manganese within intracellular pools.Clone 13‐1, isolated from Mn‐poor Sargasso seawater, was able to grow more rapidly at low manganese ion activities than clone 3H, isolated from a eutrophic estuary, provided that cupric ion activity remained below ca. 10‒11 mol·liter‒1. Adaptation of 13‐1 to growth at low Mn activities appeared to involve two mechanisms: a greater ability for cellular uptake of manganese and a lower cellular manganese requirement (i.e. Mn cell quota) for growth. Comparison of our data with estimates of manganese and cupric ion activities in marine waters suggests that manganese deficiency could be important in controlling phytoplankton growth rate or community composition in some marine waters.
The carbonate system in hypersaline solutions: Alkalinity and CaCO3 solubility of evaporated seawater
Authors: Lazar B. , Starinsky A. , Katz A. , Sass E. , Ben‐Yaakov S. 
Published: April 2010

Changes in total alkalinity and in pH during the evaporation of seawater in the laboratory were studied for an evaporation range extending between 1.1 and 26 (as defined by the concentration ratio of Mg in the evaporated sample relative to mean ocean water).The evaporation experiments were performed with and without suspended aragonite. The results of the two experimental sets define an alkalinity field for evaporated, marine‐derived brines. Data from naturally formed marine brines fall within the experimental field. Deviations therefrom can be explained by changes in alkalinity unrelated to CaCO3 precipitation/ dissolution reactions.
Problems with accurate carbon measurements in marine sediments and particulate matter in seawater: A new approach1
Authors: Weliky Karen , Suess Erwin , Ungerer C. Andre , Muller Peter J. , Fischer Kathy 
Published: April 2010

The determination of carbon concentrations in marine sediments and particulate matter is hindered by the difficulty in analytically partitioning the total carbon between organic carbon and carbonate carbon phases. Attempts to “selectively” remove organic carbon by burning the sample at 500°C, or carbonate carbon by acidifying with HCl, usually affect the carbon of the remaining phase as well.A new approach permits direct measurement of both organic and carbonate carbon in a single sediment sample. The carbonate carbon concentration is determined from the CO2 evolved during phosphoric acid treatment. Subsequently, a concentrated dichromate/sulfuric acid solution is added to the remaining sediment‐acid mixture, and the CO2 liberated from the oxidation of organic carbon is measured. Total carbon is calculated as the sum of organic and carbonate carbon. A LECO carbon analyzer is modified so that the amount of CO2 evolved can be measured by the instrument’s thermal conductivity detector. In addition, total carbon content is determined on another subsample using the LECO dry combustion furnace. This provides a check on the values determined by the H3PO4/dichromate technique. Any other commercially available instrument relying on combustion furnace and thermal conductivity or infrared absorption for CO2 detection could be converted in an analogous manner.
Peru upwelling region sediments near 15°S. 1. Remineralization and accumulation of organic matter1
Authors: Henrichs Susan M. , Farrington John W. 
Published: April 2010

Six cores were obtained along a 70‐km transect perpendicular to the Peru coast in the highly productive upwelling region near 15°S, at depths ranging from 90 to 5,300 m. All of the sediments sampled were diatomaceous oozes. Three cores overlain by poorly oxygenated water had Thioploca‐like filamentous bacteria in surface sediments. Total organic carbon and total nitrogen contents of the sediments ranged from 0.8 to 10% and from 0.1 to 1% (dry wt). For the 90‐m and 268‐m cores, which had 210Pb surface sediment accumulation rates of about 0.6 and 1.1 cm · yr‒1, surface sediment organic carbon accumulation rates were 40 and 70 g C·m‒2·yr‒1. The organic carbon and total nitrogen distributions in the three cores from the oxygen minimum zone indicate that there have been variations in the rate of accumulation of organic matter over time. These variations may be related in part to the frequency and intensity of El Niño events.Porewater ammonium, nitrate, nitrite, total carbon dioxide, sulfate, and sulfide concentrations were measured. Remineralization rates in sediments calculated from the dissolved carbon dioxide profiles range from 0.6 to 20 g C·m‒2·yr‒1. Total carbon dioxide concentrations in porewaters of two oxygen‐minimum‐zone sediments were modeled using both steady state and nonsteady state distributions of metabolizable organic matter.
Peru upwelling region sediments near 15°S. 2. Dissolved free and total hydrolyzable amino acids1
Authors: Henrichs Susan M. , Farrington John W. , Lee Cindy 
Published: April 2010

Dissolved free and total hydrolyzable amino acid concentrations were measured in five cores of Peru coastal sediments collected along a 70‐km transect perpendicular to the coast in the upwelling region near 15°S at depths of 92, 268, 506, 1,428, and 5,300 m. Total hydrolyzable amino acids (THAA) made up 20–70% of the total nitrogen in these sediments, with the highest proportions in surface sediments of the 92‐, 268‐, and 506‐m cores. Variations in THAA content with depth were attributable to a combination of remineralization and varying inputs to the sediment surface over time. The individual amino acid residue composition was remarkably uniform, both with depth in core and between stations.Dissolved free amino acid (DFAA) concentrations ranged from about 1 µM to µM. The highest concentrations were found near the sediment‐water interface of sulfide‐containing sediments. Concentrations generally decreased with depth in sediment. Glutamic acid was a major constituent of nearly all samples, suggesting a bacterial source for most of the DFAA. A nonprotein amino acid, β‐aminoglutaric acid, was also a major component and was the most abundant DFAA below 20‐cm depth in the 92‐, 268‐, and 506‐m cores. The major trends in DFAA concentration and composition appear to be the net result of biological (largely bacterial) sources and sinks.
Depositional fluxes of metals and phytoplankton in Windermere as measured by sediment traps1
Authors: Hamilton‐Taylor J. , Willis M. , Reynolds C. S. 
Published: April 2010

Monthly sediment trap samples collected from a deep water station (42 m) in Windermere for a period of 1 year were analyzed for 0.5 M HCl extractable and total Fe, Mn, Al, Pb, Cu, Zn, total C, N, and total solids. Concomitant algal counts showed the year to be fairly typical in terms of the known sequence of phytoplankton.The annual depositional fluxes are compared with previously determined values based on sediment studies. The ratio of the annual trap to sediment flux for Al (≤ 1) indicates the absence of local sediment resuspension. The ratios for Fe, Pb, and Zn (1.1, 1.4, and 1.5, but not significantly > 1) suggest some possible biogeochemical cycling at the sediment‐water interface. The deposition of Fe, Al, and Pb is predominantly associated with detrital material and occurs mainly during winter. The behavior of Zn is largely independent of other variables examined. The ratios for C (1.8), total solids (2.2), N (3.2), Mn (8.6), and Cu (9.5) are all significantly > 1. The C and N values are thought to reflect the microbial breakdown of organic matter at the sediment surface and more particularly the preferential degradation of proteinaceous (i.e. N rich) material. The major influence on the deposition and recycling of Mn is its well known redox cycle involving oxidative precipitation and reductive remobilization. Cu undergoes an independent deposition‐remobilization cycle, probably related to uptake by diatoms and their rapid microbial decomposition after sedimentation.
Particle production by planktonic ciliates1
Authors: Stoecker Diane K. 
Published: April 2010

Favella sp. (a tintinnid) and Balanion sp. (a nonloricate ciliate) produce fecal aggregates which overlap in size with their dinoflagellate food. These aggregates have a higher C:N ratio than the dinoflagellates. As the aggregates disintegrate, smaller particles are produced. For Favella grazing on the thecate dinoflagellate, Heterocapsa triquetra, the volume of the fecal material produced is 22–23% of the volume of algae consumed.The similarity in size of microplanktonic algae and ciliate fecal aggregates makes the Coulter Counter inappropriate for use in determining clearance or ingestion rates in ciliate feeding experiments unless egestion rates can be estimated. Visual counts were compared with Coulter Counter data for an experiment in which Favella and Balanion grazed Heterocapsa. The Coulter Counter underestimated ingestion rates by 30% for Favella and by 18% for Balanion and confounded the results in respect to particle size selectivity. However, because electronic particle counting measures the net change in particle concentration (ingestion — egestion) it can be used to measure assimilation rates. The assimilation efficiencies for Favella and Balanion eating Heterocapsa were thus estimated to be 70 and 82%.
Selective particle ingestion by a filter‐feeding fish and its impact on phytoplankton community structure1
Authors: Drenner Ray W. , Mummert John R. , deNoyelles Frank , Kettle Dean 
Published: April 2010

The ingestion rates of filter‐feeding gizzard shad for different sizes of suspended particles were measured using mixtures of microspheres and zooplankton. Ingestion rate increases as a function of particle size, leveling off at 60 µm. The particle‐size‐dependent ingestion rates were consistent with a model of filtering efficiency based on the cumulative frequency of interraker distances of gizzard shad gill rakers.Comparison of ponds containing gizzard shad with control ponds without fish showed that gizzard shad suppressed Ceratium, the only phytoplankton species large enough to be ingested at a maximum rate. Gizzard shad did not have a significant effect on populations of Synedra, Peridinium, Navicula, Kirchneriella, Cyclotella, and Chlamydomonas. Populations of Ankistrodesmus, Cryptomonas, Cosmarium, Rhodomonas, and algae and bacteria from 2‐4 µm were enhanced by gizzard shad.
Utilization of detritus by the copepod, Acartia tonsa1
Authors: Roman Michael R. 
Published: April 2010

Ingestion, survivorship, and growth experiments were conducted with the marine calanoid copepod, Acartia tonsa, various concentrations of the diatom, Thalassiosira weissflogii, and detritus derived from the macrophyte, Thalassia testudinum. Copepod ingestion rates of detritus increased with detritus concentration from <50 to > 1,700 µg C·liter−1.Copepod survival in detritus suspensions was significantly greater than in filtered seawater controls. The instantaneous mortality coefficient, z, of A. tonsa was a linear (negative) function of the diatom concentration (r2 = 0.7831). When T. weissflogii suspensions were supplemented with detritus (1,000 µg C·liter−1), the copepod instantaneous mortality rate decreased (0.3002–0.1362 in 50 µg C liter−1 T. weissflogii; 0.1345–0.0406 in 200 µg C·liter−1 T. weissflogii). The growth rate of A. tonsa was a linear function of diatom concentration (r2 = 0.8816). When the diatom suspensions were supplemented with T. testudinum detritus, the growth rate of the copepod increased.Thalassiosira weissflogii contained 12 × the protein, 8 × the fatty acids, and a greater amount and diversity of amino acids and polyunsaturated fatty acids per unit dry weight than T. testudinum detritus. Although A. tonsa could not grow from egg to adult on a detrital diet, T. testudinum detritus did supplement algal diets to increase copepod production rates.
Carbon flow through oxygen and sulfate reduction pathways in salt marsh sediments1
Authors: Howes Brian L. , Dacey John W. H. , King Gary M. 
Published: April 2010

We measured surface O2 uptake, 35SO42− reduction, and total sediment metabolism (CO2 production) in sediments (0–30 cm) supporting stands of short Spartina alterniflora in a New England salt marsh. Sediment CO2 production was highest at the surface where O2 was present and declined rapidly with depth. In deeper sediments (below 5 cm) CO2 production was equal to 35SO42− reduction as determined by the Cr2+ reduction technique. Time‐course experiments using CO2 production and 35SO42− reduction (by Cr2+ reduction and aqua regia digest) indicate that the aqua regia technique is not reliable for measuring SO42− reduction and that the rate of SO42− reduction is much less than previously reported for this marsh.Our estimates of annual O2 uptake conform with those for CO2 production and belowground production. We estimate carbon mineralization to average about 180 mmol C·m−2·d 1, among the highest measured for marine sediments. Our simultaneous measurements of O2 uptake, CO2 production, and SO42− reduction suggest that at least half of this decomposition occurs via SO42− reduction. We conclude that the mechanisms underlying carbon and sulfur cycling in salt marsh sediments are much more similar to subtidal sediments than previously recognized.
TMicroorganisms and detritus in the diet of a typical neotropical riverine detritivore, Prochilodus platensis (Pisces: Prochilodontidae)1
Authors: Bowen Stephen H. , Bonetto Argentino A. , Ahlgren Molly O. 
Published: April 2010

Quantitative analyses of stomachcontents indicate Prochilodus platensis depends on detritus rather than microorganisms for its nutrition. Chemical data suggest that this detritus is of a different origin than previously supposed.
Relationships between phosphorus loading and trophic state in calcareous lakes of southeast Wisconsin
Authors: Stauffer Robert E. 
Published: April 2010

The relationships among external phosphorus loading, lake phosphorus concentrations, and indices of lake trophic state are investigated for four calcareous and one noncalcareous lake in southeast Wisconsin. The total P and molybdate‐reactive P concentrations during winter and spring overturn are significantly higher in the calcareous lakes than predicted by models based on regional studies of Canadian Shield (ELA) lakes and the central New York Finger Lakes. The calcareous Wisconsin lakes have relatively low phosphorus retention coefficients and are eutrophic despite their low or only moderate external P loadings. By contrast, noncalcareous Devils Lake is oligotrophic; it is also adequately represented by the ELA loading vs. response equations.The calcareous Wisconsin lakes and edaphically similar Lake Minnetonka, Minnesota, have lower epilimnetic chlorophyll concentrations in summer than predicted by the Dillon and Rigler equation (based on lake mean total P at spring overturn). Because these stratified lakes are frequently phosphorus‐limited in midsummer, the failure of the Dillon‐Rigler model may be related to seasonal cycles of mixed‐layer concentrations of total P (and SRP) and also to the seasonal patterns of loading. From other studies I suggest that these observations may be part of a larger edaphic pattern related to low phosphorus binding tendencies of certain calcareous lake sediments.
Does settling seston release soluble reactive phosphorus in the hypolimnion of lakes?
Authors: Gächter René , Mares Antonin 
Published: April 2010

Organic material collected with sediment traps at depths of 20, 40, and 60 m in mesotrophic, phosphorus‐limited Lake Lucerne was decomposed aerobically at a rate of about 0.01 day−1 at 6°C. However, this material is not a source, but rather a sink, for soluble reactive phosphorus (SRP). As a consequence, during stratification, in the upper part of the hypolimnion concentrations of oxygen and SRP decrease simultaneously, and the ratio POC:PP (particulate organic carbon: particulate phosphorus) decreases significantly with increasing sampling depth and hence with increasing age of the seston. Once deposited at the aerobic sediment surface, the particulate matter continues to accumulate SRP.Since settling particles and the aerobic sediment surface both act as sinks for SRP, anaerobic subsurface sediments are the only possible source for the SRP accumulating in the hypolimnion during summer stagnation. The aerobic sediment layer may however become an apparent source for SRP if the supply from deeper anoxic sediments exceeds its biological‐chemical sorption capacity.Based on these observations and on additional information from the literature it is hypothesized that in phosphorus‐limited lakes decomposing organisms do not release, but rather take up, SRP while mineralizing phosphorus‐poor organic material.
The fauna associated with drift algae captured with a plankton‐mesh purse seine net1
Authors: Kingsford M. J. , Choat J. H. 
Published: April 2010

A plankton‐mesh purse seine used to encircle drift algae in open coastal waters was compared with seines in open water and conventional ichthyoplankton hauls. Densities of small fish and invertebrates were higher in association with drift algae than in open water. Most fish that occurred with drift algae were well pigmented. The fauna of drift algae differed from that of attached algae. Large numbers of epiphytic animals vacated attached algae which were experimentally detached from the substratum. The fauna on drift algae, therefore, is largely the result of colonization from open water. Fish and invertebrates were quickly attracted to clumps of experimental algae that were left to drift. This suggested that drifting algae may quickly influence the distribution of animals in open water.Appreciable quantities of drift algae may influence the survivorship and recruitment processes of species which associate with algae during the planktonic phase of their life cycles.
The rise and decline of a bloom of halobacteria in the Dead Sea1
Authors: Oren Aharon 
Published: April 2010

A massive bloom of halobacteria that had developed in the upper water layers of the Dead Sea in summer 1980 together with a bloom of the unicellular green algae Dunaliella was present for more than 2 years. Simulation experiments performed in ponds in the Dead Sea area showed that the availability of phosphate, the extent of dilution with less saline water, and the availability of a suitable carbon source determine the extent of the development of halobacteria in Dead Sea water.The number of particles resembling bacteria per milliliter of surface water decreased more than fivefold between November and December 1982, while the particulate protein decreased to below detection limits. This sudden decrease was correlated with a change in the physical structure of the water column from stratification to overturn.
The dominant processes of sediment distribution and focusing in a small, eutrophic, monomictic lake
Authors: Hilton J. , Lishman J. P. , Allen P. V. 
Published: April 2010

There is evidence for 10 mechanisms of sediment distribution in small lakes. The sediment accumulation rates measured from a common horizon in cores from 64 sites on Esthwaite Water, U.K., were used to determine the relative importance of these mechanisms on the distribution of sediment in the lake.River inflows generally produced localized effects but there were indications of periodic turbidity flows to the deepest point of the lake from the major inflow. Active sediment focusing processes were the dominant distribution mechanisms, a major resuspension of sediment at autumn overturn probably being the most important. The remaining variance was much greater than observed in similar work elsewhere, suggesting that redistribution of sediment by direct and indirect wave action may be taking place all over the lakebed during isothermal periods. The relative contributions of the different processes were corroborated by analysis of previously published sediment trap data.
The effects and implication of tides and rainfall on the circulation of water within salt marsh sediments1
Authors: Carr Alan P. , Blackley Michael W. L. 
Published: April 2010

The response of the water table of an intertidal salt marsh in NW England has been investigated. During neap tides, water seeps upward from the underlying sand‐silt‐clay interface. This effect continues as the marsh is overtopped during spring tides but is then dwarfed by penetration of water downward from the surface.Under “typical conditions” the delay between high water in the river and maximum apparent water level for the marsh becomes less as the spring‐tide cycle maximum is approached. Lags also appear smaller during summer, probably mainly due to desiccation cracks. Precipitation effects are only important when rainfall is significant in quantity and coincides with low water during neap tides.
The use of 15N to measure nitrogen uptake in eutrophic oceans; experimental considerations1,2
Authors: Dugdale R. C. , Wilkerson F. P. 
Published: April 2010

The use of 15N to measure the flux of nitrogen compounds has become increasingly popular as the techniques and instrumentation for stable isotope analysis have become more widely available. Questions concerning equations for calculating uptake, effect of isotope dilution (in the case of ammonium), duration of incubation, and relationship between disappearance of a nitrogen compound and the 15N uptake measurement have arisen, especially for the research conducted in oligotrophic regions. Fewer problems seem to have occurred in eutrophic areas. However, sufficient literature now exists to allow some generally accepted experimental procedures for 15N studies in eutrophic regions to be laid down.Incubation periods of 2–6 h appear to avoid problems related to isotope dilution and to overcome the bias introduced in some cases by initial high rate or surge uptake. During such incubation periods, assimilation is measured rather than uptake or transport into the cell. Incorporation of 15N into the particulate fraction is usually linear with time over the periods currently used. The 15N method provides a better estimate of incorporation into phytoplankton than 14N disappearance, but a small fraction appears to be lost. Although most workers suggest the loss to be a result of dissolved organic nitrogen production, direct evidence is lacking.If the considerations discussed here are applied with the 15N techniques currently available, reliable estimates of phytoplankton nitrogen flux in eutrophic areas can be obtained.