bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution, abundance, and metabolic states of microorganisms in the water column and sediments of the Black Sea1
Authors: Karl David M. 
Published: March 2010

The vertical distribution, abundance, and metabolic states of microorganisms have been measured within the water column of the Black Sea. Samples collected from the O2–HS− interface revealed a vertically restricted layer (<20–30 m) of metabolically active cells. Within the anoxic portion of the water column (200–2,100 m), ATP concentrations were 5–10 times greater than in oxygenated environments of comparable depth; biomass and various metabolic activities increased with increasing water depth, implying a vertical gradient in specific organic substrates required for bacterial growth and metabolism.The vertical distribution of ATP was also measured in two sediment cores raised from the western basin of the Black Sea. The ATP concentration within the uppermost sediment layer (0–10 cm) was 4 orders of magnitude greater than in the overlying water column, on a per volume basis (150 ng ATP · cm−3 for the sediments, vs. 10 ng ATP · liter−1 for the water column). Scanning electron micrographs are presented depicting early stages in the diagenesis of framboidal iron sulfide.
Vertical distribution of Calanus hyperboreus in the central Arctic Ocean1
Authors: Dawson John K. 
Published: March 2010

The vertical distribution of Culanus hyperboreus was determined for a 23‐month period from net samples collected from T‐3 Ice Island in the central Arctic Ocean. Distributions of copepodite stages were similar, but dissimilar to that of the adults. The depth range of the copepodites was 300–500 m, except during summer when they rise to the surface. The adult female population sank gradually from 100 to 300 m in the spring. During summer, females were at the surface and by fall they were centered at about 150 m, where they remained throughout winter. Adult males were centered deeper (400–700 m) than the females and were present only during spring and early summer.Calanus hyperhoreus appears to have a generation length of at least 3 years in the central Arctic Ocean.
Length and weight relationships of Acartia clausi from Narragansett Bay, R.I. 1
Authors: Durbin Edward G. , Durbin Ann Gall 
Published: March 2010

Changes in the cephalothorax length and dry weight of Formalin‐preserved copepodite and adult Acartia clausi were followed from 12 March–1 June 1976 and naupliar weights and lengths determined for one sample. Preservation in Formalin caused a significant loss of dry weight, carbon, and nitrogen in adult females, mostly during the first 24 h, but did not significantly affect the C:N ratio or the cephalothorax length of the animals.Length and weight were inversely related to seawater temperature at the time of sampling. As the animals became older this relationship was increasingly affected by their past temperature history. Separate linear relationships between log length and log weight were observed for the nauplii, the CIs, the CII–CVs, and the adults, making it possible to estimate the weight of individual stages from measurements of length.Animals collected on the same day from different stations sometimes showed significant differences in weight for a given length. Such differences could be more clearly expressed by calculation of a condition factor relating weight to the cube of cephalothorax length. The differences in the condition factor appeared to be related to food availability and such differences may be even more apparent when weights of live animals are examined.
The enigma of Daphnia death rates1
Authors: Prepas E. , Rigler F. II. 
Published: March 2010

Birth rates, rates of population change, and mortality rates were computed for Daphnia pulex and Daphnia rosea collected at three separate stations in. 2.5‐ha meromictic Crawford Lake. Birth and death rates for the same species at the three separate stations, or at the same station but living at slightly different mean depths were substantially different. A correction for tow net efficiency for young and adult animals increased birth rate values by 40%.Mean finite birth rate, B, for Daphnia in a thermally stratified lake is calculated from the relation
urn:x-wiley:00243590:media:lno19782350970:lno19782350970-math-0001
where for each stratum, s, E is number of eggs, D is egg development time, N is number of animals, and n is number of strata. An assumption of this formulation is that all individuals in the population behave similarly, hut at Crawford Lake D. pulex behaves like two separate populations for at least part of the year.High death rates were calculated for D. rosea in midsummer. A comparison of observed neonates with expected neonates during this period led to the conclusion that most mortality in the population occurs either in late embryos or at hatching.
Daphnia grazing on natural bacteria1
Authors: Peterson Bruce J. , Hobbie John E. , Haney James F. 
Published: March 2010

Ten to sixteen Daphnia were placed in small vials filled with natural water from a lake and incubated for 0.5 to 2.0 h. The small (ca. 0.10 µ3) bacteria were counted on Nuclepore filters by an Acridine Orange direct count method with epifluorescence. Filtering rates were calculated from counts of bacteria before and after the incubations.For D. pulex, D. middendorffiana, and D. longiremis the filtering rates ranged from 0.2 to 1.5 · ml animal−1 · h−1 depending on the size of the animal and temperature. Simultaneous comparisons with rates of filtering on larger yeast cells indicated that these bacteria were filtered at about 30% the rate for yeast.
Transport of particulate organic matter by bubbles in marine waters 1
Authors: Wallace Gordon T. , Duce Robert A. 
Published: March 2010

Flotation experiments with surface marine waters collected from estuarine, continental shelf, slope, and open ocean waters showed that about half of the originally present particulate organic carbon and nitrogen was adsorbed and transported by bubbles to the surface froth. Recovery values were a function of primary production and other environmental parameters. In only one instance was there evidence of selective removal of particles with C:N ratios differing from those left behind.The estimated open ocean transport of POC by bubbles was five times higher than an earlier estimate due to the unexpected efficiency of the flotation column at low concentrations of open ocean POC. Budget calculations indicated little or no conversion of dissolved to particulate organic carbon. Large macroscopic particles quickly formed in the froth produced by bubbling, an aggregation phenomenon which may be of importance in the transport of large particle POC to deep waters.
A comparison between the cell division rate of natural populations of the marine diatom Skeletonema costatum (Greville) Cleve grown in dialysis culture and that predicted from a mathematical model1
Authors: Yoder James A. , Yoder James A. 
Published: March 2010

At weekly intervals from January through May 1977, during the winter‐spring phytoplankton bloom in Narragansett Bay, Rhode Island, a phytoplankton sample was collected from the bay, encapsulated in dialysis bags, incubated in flowing seawater for 2–5 days at two different light levels, and the cell division rate of Skeletonema costatum was determined. Light intensity, water temperature, and the ambient concentrations of dissolved inorganic nitrogen, phosphorus, and silicon were measured during each experiment. Observed cell division rates were compared with those predicted from a mathematical model incorporating terms for the effect on growth of light intensity, temperature, and silicate concentration.Regression analysis revealed that equations incorporating only the effect of temperature and light intensity were sufficient to explain the observed cell division rate in many experiments, hut the inclusion of silicate concentration improved the relationship. The cell division rate of these natural populations of S. costatum grown in dialysis bags in flowing seawater could thus be predicted with reasonable accuracy with a simple mathematical model primarily formulated from the results of a batch culture study of a single clone of this species.
A population dynamics analysis of the cladoceran disappearance from Lake Tahoe, California‐Nevada1
Authors: Goldman Charles R. , Morgan Mark D. , Threlkeld Stephen T. , Angeli Nadine 
Published: March 2010

A comparison of the population dynamics of Daphnia pulicaria and Daphnia rosea in 1967–1969 and during their decline from Lake Tahoe in 1970 showed that the decline resulted from a combination of increased death rates and decreased birth rates. The remaining cladoceran, Bosmina longirostris, disappeared from the plankton in 1971. The elimination of cladocerans coincided with high densities of the opossum shrimp, Mysis relicta, and the kokanee salmon, Oncorhynchus nerka. Predation by these two introduced species is believed to have increased cladoceran death rates. Changes in the timing of the peaks of primary productivity are a possible cause for the decline in birth rates.A brief resurgence of Bosmina in late 1974 was associated with a dramatic decline of the mysid population and the continued decline of kokanee which began in 1970. The mysids recovered by late 1975 but Bosmina again disappeared and has remained absent since. The failure of Daphnia to reappear suggests that factors in addition to predation by kokanee and Mysis exclude them from Lake Tahoe. Changes in the phytoplankton community composition may have altered the ability of the cladocerans to maintain birth rates sufficiently high to offset increased losses due to predation.
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.
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%.
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.
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.
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)
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.
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.
Attenuation of light and daily integral rates of photosynthesis attained by planktonic algae1
Authors: Megard R. O. , Combs W. S. , Smith P. D. , Knoll A. S. 
Published: March 2010

The daily integral rate of photosynthesis attained by planktonic algae in Lake Minnetonka, Minnesota, conforms to an equation for a rectangular hyperbola proposed by Bannister. The rate depends on the concentration of chlorophyll a in the mixed layer and also upon two kinetic parameters that are analogous to the kinetic constants in equations for reactions catalyzed by enzymes. One parameter is an upper limit, ψ, that would be attained by very dense populations, and the other is a concentration of chlorophyll, c', at which attenuation of photosynthetically active radiation (PhAR) by the algae equals background attenuation by the water. The parameters were evaluated with the same statistical procedures used to evaluate the kinetic constants for enzyme reactions.The limit, ψ, for the daily integral rate in this lake would be about 0.5 mol O2·m−2·d−1 Observed daily rates are usually <0.7 ψ, because chlorophyll in the water usually intercepts <70% of the radiant energy. Coefficients for the attenuation of PhAR by chlorophyll,, and by the water, were estimated from the linear regression of the total attenuation coefficient, ε, on chlorophyll concentration. The estimate of εc is 0.022 ± 0.005·m−1·(mg Chl·m−3)−1. Background attenuation, εw, affects integral photosynthesis in the same way as a competitive inhibitor affects enzyme reactions: it is a constituent of c′ = εw/εc which, together with chlorophyll concentration, determines the fraction of underwater PhAR intercepted by planktonic algae.
Effects of temperature and fasting on the rate of sinking of Hydra oligactis1
Authors: Schroeder Lauren Alfred , Reeder Patricia S. 
Published: March 2010

Sinking rates of Hydra oligactis Pallas reared at 10°, 15°, and 25°C were determined in a water column at 10°, 21°, and 26°C after fasting intervals ranging from 24 to >500 h. The rearing temperature (Tr), water temperature during sinking (Tw), duration of fasting (Ft), and body conformation (Hc) (i.e. body length, tentacle length, and tentacle orientation) all significantly correlated with sinking rate. The linear regression model: sinking rate (cm·s−1) = 0.684 − 0.0323Hc − 0.00055Ft − 0.00959Tr + 0.00711Tw accounted for 85% of the observed variability.Hydra density (g·cc−1) was inversely related to rearing temperature and decreased from 1.030 g·cc−1 for animals reared at 10°C and 1.025 for those reared at 25°C to a plateau of 1.017 g·cc−1 for both rearing temperatures after 200 h and 80 h of fasting for hydras reared at 10° and 25°C. Hydra size also was inversely related to rearing temperature ranging from >100 µg (dry wt) per single hydra at 10°C to 30 µg dry wt at 25°C. Hydra size decreased with fasting to <10 µg dry wt. Changes in hydra density and surface area:volume ratio account for 80 and 97% of the change in sinking rate of fasting hydras reared at 10°C and 25°C.Hydras are especially susceptible to planktonic existence during spring and fall turnover and may become dispersed throughout lakes, but during summer stratification the increased sinking rates would significantly reduce the potential for their lateral transport in the epilimnion.
Groundwater transport of a salt tracer through a sandy lakebed1
Authors: Lee David Robert , Cherry John A. , Pickens John F. 
Published: March 2010

In an investigation of groundwater advection and dispersion in a lakebed, a vertical zone of salt solution was injected between 1.7 and 3 m beneath the shoreline and entered the lake through a large area of lakebed at a reduced concentration. Migration of the tracer pulse and flux to the lake were monitored over a 7‐ × 8‐m area of lakebed by measuring the electrical conductance of water collected from sampling points beneath the lakebed and from seepage meters on the lakebed. The tracer moved horizontally, curved gently upward, and entered the lake through an area of 17 m2—an area 5.7 times larger than the initial cross‐sectional area of the tracer zone. Seepage flux through the sediment‐water interface declined exponentially with offshore distance and averaged 240 m3·yr −1 per meter of shoreline.Results showed that prediction of solute flux from onshore zones of groundwater contamination requires consideration of dispersion (mixing) and the ratio of horizontal to vertical permeability (Kh:Kv). Numerical simulations showed that with increasing Kh:Kv, tracer‐ or contaminant‐entry areas on the lakebed extend over larger areas and are displaced farther offshore. A Kh:Kv of 10 matched the field observations. An analytical model indicated that the observed reduction in peak concentration (a decline to 31% of the initial value over a 6‐m flow path) would result from values of longitudinal dispersivity as small as 1 cm.
Recent sedimentation and its relationship with primary productivity in four western Washington lakes1
Authors: Birch Peter B. , Barnes Robert S. , Spyridakis Dimitris E. 
Published: March 2010

Studies of sedimentation processes in four western Washington lakes reveal up to sixfold variations in sedimentation rates over the past 130 years of settlement in the region. These variations in sedimentation can be linked with known changes in land use in the watersheds, especially logging, which appears to have accelerated erosion.Contemporary deposition of phosphorus into profundal sediments is positively correlated with phytoplankton productivity in the four lakes. If a similar relationship existed in the past when sedimentation rates of phosphorus were different, then increases in primary productivity from twofold to fourfold could have occurred in three of the lakes since about 1840.