bluuebunny/crossref_metadata_2025 huggingface dataset:
Immediate detection of heterogeneities in continuous multivariate, oceanographic recordings. Application to time series analysis of changes in the bay of Villefranche sur Mer
Authors: Ibanez Frederic
Published: March 2010

An index is described for immediate detection of discontinuities in continuously monitored, multivariatc recordings. At every sampling point, the generalized distance is computed between the new multivariate observation and the centroid of the n previously recorded observations (D2 to the centroid). These n points form a window, whose width determines the sensitivity of the index. By its mathematical formulation the distance takes into account the variations in range of the variables and their correlations. The validity of the index was first tested on simulated series into which different types of changes were arbitrarily introduced. Applying the index to a 4‐year temperature and salinity series (weekly observations at the surface of a station in the bay of Villefranche sur Mer) leads to a coherent pattern of hydrological events.
Postdepositional mobility of phosphorus in lake sediments1
Authors: Carignan R. , Flett R. J.
Published: March 2010

Fifteen sediment cores from Lake Memphremagog showed pronounced peaks of total phosphorus concentration within the 210Pb‐defined mixed layer, suggesting that P was migrating upward and accumulating near the mud surface. The mobility of P in the sediments was confirmed by the rapid development (5 weeks) of a marked total P maximum in the upper centimeter of a previously homogenized sediment. Associated with the P migration was a steep gradient of soluble reactive P (SRP) concentration, presumably the result of a redox gradient in the sediments. Similar gradients of total P and SRP were observed in nondisturbed sediments, strongly suggesting that such an upward migration mechanism also operates under natural conditions. The remobilized P seems to be isotopically exchangeable (mobile) under anaerobic conditions. These observations indicate that profiles of sediment total P may not always be useful in determining historical P loading or P sedimentation rates in lakes.
Variation in sexual size differentiation in North American diaptomids (Copepoda: Calanoida): Does variation in the degree of dimorphism have ecological significance?
Authors: Geddes Michael C. , Cole Gerald A.
Published: March 2010

There is considerable intraspecific variation in the degree of sexual dimorphism in species of Diaptomus. The ratio of female length to male length in 42 species of Diaptomus varied only from 1.02 to 1.23 and did not reflect ecological differences between species. It is concluded that North American diaptomids do not show patterns of dimorphism like those of freshwater centropagids in Australia.
An in situ method for measuring the primary productivity and standing crop of the epilithic periphyton community in lentic systems1
Authors: Loeb Stanford L.
Published: March 2010

An incubation chamber and a quantitative sampler were developed to measure the primary productivity and standing crop of the epilithic periphyton community in Lake Tahoe. The method allows in situ measurements with minimal disturbance to the natural community. In an experiment comparing the substrate colonization method with the natural epilithic periphyton community, artificial substrate methods underestimated productivity by as much as 95%. The species composition of the periphyton on the colonized substrates was quite different from that of the natural sublittoral epilithic community.
Long‐distance horizontal migrations of zooplankton (Scyphomedusae: Mastigias)1
Authors: Ilamner William M. , Hauri Ivan R.
Published: March 2010

Perennial swarms of sexually immature medusae of the germs Mastigias occur at high densities in three marine lakes in Palau, Western Caroline Islands. Numbers per lake are 1.76 ± 0.10 × 105, 1.61 ± 0.17 × 106, and 4.69 ± 0.51 × 106. Local density within a swarm may exceed 1,000·m‒2. Behaviorally generated swarms form in the early morning and late afternoon and are temporarily dispersed by directional horizontal migration of the entire swarm twice a day to opposite ends of the lake. Distance swum each day is up to 1 km, depending on the size of the lake. Compass direction of migration is different in each lake and appears to depend on both light and basin morphometry.
Phototoxicity and fish predation: Selective factors in color morphs in Heterocope1
Authors: Luecke Chris , O'Brien W. John
Published: March 2010

In the Toolik Lake region of arctic Alaska, Heterocope septentrionalis occurs in two distinct color morphs, dark red and pale green. The dark form tends to occur in shallow fishless ponds and the pale form in large, deep lakes with fish. Phototoxicity and fish predation experiments on the two morphs showed that the dark red form had better survivorship in bright sunlight and the pale green form was less susceptible to predation by visually feeding fish. The red color is caused by a keto‐carotenoid pigment. In lakes where predation presents a threat than sunlight the keto‐carotenoid pigment is complexed with a protein to produce green Heterocope.
Chaoborus prey capture efficiency in the light and dark1
Authors: Swift Michael C. , Forwarder. Richard B.
Published: March 2010

The strike efficiency of fourth‐instar Chaoborus punctipennis larvae on different size copepods was measured in the light and dark in the laboratory. Dark measurements were made with near‐infrared illumination and a closed circuit television system. There was no significant difference between strike efficiency in the light and dark during either day (0900–1800) or night (2100–0600). Strike efficiency generally increased as the prey size decreased, and the longest prey captured was about 1.4 mm. However, 29% of the larvae which contacted egg‐bearing female copepods longer than 1.4 mm ingested all or part of the female’s egg sac. The lack of a measurable difference in larval strike efficiency in the light and dark suggests that the diel vertical migration pattern followed by Chaoborus larvae is not related to diel changes in prey vulnerability.
Production ecology of Cricotopus sylvestris (Fabricius) (Diptera: Chironomidae) in a shallow estuarine cove
Authors: Menzie Charles A.
Published: March 2010

Cricotopus sylvestris was the predominant chironomid (80% composition by abundance) living on Myriophyllum spicatum in a cove of the Hudson River estuary. Annual production of C. sylvestris was conservatively estimated by the size‐frequency method to be 5.8 g·m‒2·yr‒1 (dry weight).

The annual (P:B) ratio for the species was 21.0, one of the highest values reported for chironomids. Laboratory‐reared larvae completed development in 10 days at 22° and 29°C and 28 days at 15°C, while development in the field was conservatively estimated to take 42 days. Production of C. sylvestris accounted for 31% of total chironomid production in the cove and 60% of the production of chironomid species associated with M. spicutum. The biomass of emerged adults of C. sylvestris was estimated to be 2 g·m‒2·yr‒1, or 34% of the produced larval biomass. Cage experiments in the field and laboratory studies of feeding rates indicated that damselfly naiads consumed much of the larval biomass not removed by adult emergence. The larvae also were eaten by other invertebrates and fish.
Energy balance in a shallow seagrass flat for winter conditions1
Authors: Smith Ned P.
Published: March 2010

Meteorological and hydrographic data from a 68‐day period in winter 1973–1974 are used to obtain a numerical model of local energy exchanges for a station in northern Laguna Madre, Texas, The standard deviations of the errors of simulated temperatures are 0.8°–1.0°C for calculations over periods of up to 1 month. Model results indicate that sensible and latent heat energy exchanges are of primary importance and together explain nearly all of the computed day‐to‐day temperature changes. Sensible and latent heat fluxes are highly and positively correlated, as frontal passages alternate warm, air with relatively cold, dry air. Conductive exchanges between the water and the sediments are relatively minor. Effects of incoming solar radiation and outgoing longwave radiation are highly but negatively correlated, although neither is related significantly to the computed net daily heating or cooling. The energy balance seems to be between the sum of the sensible and latent heat flux terms and the storage term.
Properties of the seawater‐air interface. 2. Rates of surface film formation under steady state conditions1
Authors: Dragcevic Dj. , Pravdic V.
Published: March 2010

The laboratory techniques of dynamic surface tension and of surface electrical potential measurements were used to determine rates of formation and of reorientation of organic surface films at the seawater‐air interface. Relaxation times of surface films were determined for three characteristic samples obtained by screen and bottle sampling in the coastal waters of the northern Adriatic area. These data were compared with those for model samples produced by spreading oleic acid and crude oil on or dissolving polyethyleneglycol and sodium dodecyl sulfate in artificial seawater.

Relaxation times were in the range of 0.1–1 s for most of samples. A good representative value for field samples is 0.2 s. The temperature‐dependence (the energies of activation) for the surface film relaxation indicates that several processes control material transport toward the seawater‐air interface.

The findings are interpreted as showing that an almost ever‐present organic surface film influences the mechanism and the rate of material transport across the sea‐atmosphere boundary.
Chemistry of interstitial water and bottom sediments as indicators of seepage patterns in Perch Lake, Chalk River, Ontario1
Authors: Frape S. K. , Patterson R. J.
Published: March 2010

A coring and squeezing technique was used to study seepage processes in Perch Lake. This lake was selected because a portion of the shallow aquifer in its basin contains tritium, which is an excellent tracer. Tritium analyses of interstitial water samples and well waters from piezometers adjacent to the lake indicate a pattern of groundwater discharge, or seepage, consistent with the predictions of mathematical simulations. Shallow groundwaters in the aquifer discharge almost vertically into the lake near the shore; water deeper in the aquifer enters the lake farther from shore. As a result of this groundwater discharge, metals such as iron and manganese are being deposited in the sediments.

Interstitial waters in Perch Lake, especially nearshore, are groundwaters or groundwaters mixed with lake waters. The chemistry of interstitial waters in lake sediments may thus be determined by the quality of local groundwaters as well as by sediment‐water reactions and vertical diffusional mixing. Data from nests of piezometers near the lake and from cores or multilevel piezometers in the lake bottom, information about bottom sediments, and measurements of seepage flux will be needed to estimate the contributions to lakes of dissolved components from groundwater discharge.
A numerical simulation of the vertical and horizontal M2 tide in the Bristol Channel and comparisons with observed data1
Authors: Uncles R. J.
Published: March 2010

A depth‐averaged hydrodynamical numerical model is used to investigate the M2 tide in the Bristol Channel and Severn Estuary—a large, partially enclosed, vertically mixed body of water having one of the largest tidal ranges in the world. The computed vertical M2 tide is compared with observed data at 17 coastal stations and the computed tidal ellipses with observations at 30 current meter stations.
In situ calibration of a sediment trap1,2
Authors: Lorenzen C. J. , Shuman F. R. , Bennett J. T.
Published: March 2010

A relatively small self‐contained sediment trap with a timed closing system was deployed in Dabob Bay, Washington, for 1 year. Samples were collected representing 326 trap exposure days. An in situ calibration was obtained by comparing the capture and retention of unsupported 210Pb by the traps with the steady state accumulation rate of unsupported 210Pb in the underlying bottom. The efficiency of the traps to collect a representative sample of the sedimenting material is 118%.
The effect of environmental factors on phytoplankton growth: Temperature and the interactions of temperature with nutrient limitation1
Authors: Rhee G‐Yull , Gotham Ivan J.
Published: March 2010

The combined stress of nutrient limitation and suboptimal temperature on growth was studied with turbidostat and chemostat cultures of Scenedesmus sp. and Asterionella formosa. The combined effects were greater than the sum of individual effects and were not multiplicative. In N‐ and P‐limited Scenedesmus sp. and A. formosa the cell (q) of both limiting and nonlimiting nutrients increased with decreasing temperature. At a given temperature cell quotas of limiting nutrients also increased with the growth rate (µ) and followed a saturation function. Higher values of the minimum cell quota (qo) at lower temperatures show that cells require more nutrient with decreasing temperature. The change of qo with temperature varies with the type of limiting nutrient. This change for N and P in Scenedesmus sp. suggests that their optimum ratio, the ratio at which one limitation changes over to the other, is higher at suboptimal temperatures.

Cell quotas of nutrient‐sufficient cultures (qm) for C, N, and P and cellular chlorophyll a concentration increased with decreasing temperature. The quota of each nonlimiting nutrient in nutrient‐limited cultures had the same value as qm. The rate of protein synthesis per unit RNA decreased with temperature.

The highest apparent maximum N uptake was observed at 15°C for N‐limited Scenedesmus sp. growing at 0.5·d‒1. The optimal growth temperature range, however, was 20°–25°C. The highest apparent maximum P uptake in A. formosa was found at 19°–20°C, when µ = 0.4·d‒1. These temperatures were also optimal for growth.
Thermal tolerance and acclimation of two species of Hydra1
Authors: Schroeder Lauren Alfred , Callaghan William M.
Published: March 2010

The upper lethal temperature for Hydra pseudoligactis was greater than for Hydra oligactis and increased from 31° to 34°C as the rearing temperature increased from 5° to 27°C. The upper lethal temperature for H. oligactis was constant (26°C) between rearing temperatures of 5° and 21°C. However, when it was reared at 27°C the upper lethal temperature increased to 31°C.

The low upper lethal temperature for H. oligactis may exclude it from shallow pond habitats and contribute to the rapid population decline often observed in the epilimnion of temperate lakes.
Summer population fluctuations, feeding, and growth of Hydra in an arctic lake1
Authors: Cuker Benjamin E. , Mozley Samuel C.
Published: March 2010

During 1977, the population density of Hydra in the rocky littoral community in Toolik Lake, Alaska, increased from June to a maximum in late July or early August, then remained stable or decreased slightly through late August. The summer increase of Hydra corresponded to increases in the availability of copepods and Bosmina (the preferred prey) until late July. Hydra kept at lake temperatures in the laboratory with unlimited prey reproduced fast enough asexually to account for these increases: at 19°C the intrinsic rate of increase (r, biomass) was 0.53 g·g‒1·d‒1, and at 11°C, r = 0.31·d‒1. These rates, much higher than those for other Hydra at comparable temperatures, seem to be a metabolic adaptation to arctic conditions. Failure of the Hydra population to continue to increase while food resources increased in August is attributed to predation by Lymnaea, displacement by epilithic algal growth, endogenously controlled emigration from the rocky littoral, or some combination of these.

Hydra appears to be the most important predator on Bosmina. Hydra at densities of 135·m‒2 on the rocky shoals could take 1,620 Bosmina · m‒2·d−1 during late July and early August 1977, about 10% per day consumption of the estimated lake standing crop of Bosmina. This is the first evidence that Hydra plays a major role in controlling a prey population.
Solubilities of gypsum and halite in the Dead Sea and in its mixtures with seawater1
Authors: Katz Amitai , Starinsky Avraham , Taitel‐Goldman Nurit , Beyth Michael
Published: March 2010

The solubilities of gypsum (CaSO4·2H2O) and halite (NaCl) in aqueous solutions with ionic strengths between 3 and 13 were studied under ambient conditions. Mixtures of Mediterranean seawater and Dead Sea brines, evaporated to various degrees, served as experimental solutions.

The practical solubility constant of gypsum [KGsp = (mCa × mSO4) eq] was found to be related to the ionic strength (I) of the solution by the empirical expression
urn:x-wiley:00243590:media:lno19812640709:lno19812640709-math-0001

This relationship was then applied to calculate the degree of saturation with respect to gypsum (DSG) of the present Dead Sea water column.

Calculations indicate that the entire Dead Sea water column (ionic strength = 9–10) is saturated or even slightly oversaturated with respect to both minerals studied.
Estimating mortality from growth parameters and a size distribution when recruitment is periodic1
Authors: Ebert Thomas A.
Published: March 2010

A size distribution of organisms is determined by growth and survivorship functions together with variability in recruitment. If recruitment is seasonal and constant from year to year, then the instantaneous mortality coefficient, Z, is equal to ln{[1 ‒ C]/ [1 ‒ C·exp(K)]} where C = {S∞ ‒1/n ‒ X̄}/ {S∞‒1/n b·exp[K(1 ‒ t)]}, X̄ is mean size of individuals in the population at time t since recruitment of the year, and other parameters are from the Richards function. Examples are presented for a simulated population and for a population of the sea urchin diadema setosum, which has an annual mortality of 25% and an average lifespan of about 3.5 years.
Zooplankton filtering rates: Error due to loss of radioisotopic label in chemically preserved samples
Authors: Holtby L. Blair , Knoechel Roy
Published: March 2010

Zooplankton fed 32P‐labeled yeast or 14C‐labeled algae were preserved with Formalin, ethanol, or Lugol’s iodine and the subsequent loss of labeled materials was followed by analysis of sample filtrates. The commonly used combination of 32P‐labeled yeast and Formalin preservation produced maximal loss in both magnitude and duration, reaching a value of 73% loss after 3 days; ethanol preservation resulted in only 5% loss for the same food. Lugol’s iodine yielded the best results for animals fed 14C‐labeled algae, resulting in a 40% loss that stabilized within 3 h. Nonchemical preservation (heat‐killing and drying) produced filtering rates comparable with those of the best chemical preservative.
Liquid scintillation counting for 14C uptake of single algal cells isolated from natural samples
Authors: Rivkin Richard B. , Seliger Howard H.
Published: March 2010

Short term rates of 14C uptake for single cells and small numbers of isolated algal cells of five phytoplankton species from natural populations were measured by liquid scintillation counting. Regression analysis of uptake rates per cell for cells isolated from unialgal cultures of seven species of dinoflagellates, ranging in volume from ca. 103 to 107 µm3, gave results identical to uptake rates per cell measured by conventional 14C techniques. Relative standard errors of regression coefficients ranged between 3 and 10%, indicating that for any species there was little variation in photosynthesis per cell.
Dissolved humic substances: A major source of error in fluorometric analyses involving lake waters1
Authors: Carlson Robert E. , Shapiro Joseph
Published: March 2010

Dissolved humic substances in lake waters fluoresce strongly and may cause a substantial proportion of the fluorescence usually ascribed to in vivo chlorophyll. Chlorophyll measurements and other allied measurements such as DCMU‐enhanced fluorescence may thus be in serious error.
Formation of particulate organic carbon in water from a southeastern swamp‐stream1
Authors: Mulholland Patrick J.
Published: March 2010

The rate of particulate organic carbon (POC) formation in water from a small North Carolina swamp‐stream, low in ionic strength but high in dissolved organic carbon (DOC), was low. Mean POC formation rate, expressed as DOC utilization, was about 0.2% of DOC per day and was primarily the result of microbial activity. When Ca2+ and Hg2+ were added to swamp water, and when swamp water and seawater were mixed, the rate of POC formation increased as a result of a rapid physiochemical flocculation process. Although the DOC load of rivers and streams of the southeastern U.S. represents a substantial energy input to estuarine regions, these results indicate that only about 25–30% of it is transformed through flocculation to a form more readily retained and utilized within the estuarine system. The remainder may be transported to the sea.
A device for the measurement of infiltration in intermittently flooded wetlands1
Authors: Hemond H. F. , Burke R.
Published: March 2010

An infiltrometer has been designed to measure infiltration and exfiltration in intermittently or continuously inundated soils, such as occur in tidal salt marshes. The device isolates a column of water while actively maintaining natural head conditions, and yields infiltration/exfiltration rates from mass balance considerations. It incorporates a Stevens recorder, a reversible positive‐displacement metering pump, and solid‐state circuitry. It can detect <5 mm of infiltration or exfiltration per tidal cycle.
Biochemical modeling in coastal waters of the Middle Atlantic States1
Authors: Sharp Jonathan H. , Church Thomas M.
Published: March 2010

Biochemical dynamics in coastal waters off the U.S. Middle Atlantic States are examined by applying the Redfield model of nutrient regeneration and apparent oxygen utilization. The modeling takes advantage of the comparatively uniform spatial conditions of the seasonally stratified central shelf region and follows temporal changes in the isolated bottom waters on an integrated mesoscale. A seasonally averaged rate of bottom water nutrient regeneration of 0.0044 µmol P· −1·d−1 results and this permits estimation of a nitrogen flux across the thermocline equivalent to 0.02 µmol N·liter−1·d−1. This nitrogen flux and an extrapolated surface water nutrient regeneration could supply at least one‐third and maybe close to two‐thirds of the total nitrogen requirement for the phytoplankton productivity during summer in these coastal waters.
An analysis of grain size modification in biogenic carbonate sediments by deposit‐feeding holothurians and echinoids (Eehinodermata)1
Authors: Hammond L. S.
Published: March 2010

Changes of total alkalinity in seawater during laboratory experiments showed that Holothuria mexicana, Holothuria arenicola, and Isostichopus badionotus dissolve 0.065–0.256% of the calcium carbonate sediments ingested. These and other species of holothurians have acid pH levels in the gut when it is empty. The spatangoid echinoids Meoma ventricosa and Plagiobrissus grandis have alkaline foreguts, even when empty, and do not dissolve calcium carbonate. The process of dissolution by holothurians has insignificant implications for the carbonate mass balance of coral reefs, as only 2% or less of the annual carbonate fixation in reef flats or lagoons may be lost. Sedimentological effects are also inappreciable, as experimental dissolution of 10% of various grades of sediment resulted in only minor changes in their size frequency distributions. The changes were much smaller than the variability of the available sediment and did not conform to the predictions of a simple model, probably due to the nonlinearity of the specific surface area/size relationship of carbonate reef sands. These phenomena, together with the movement of these nonselective deposit feeders through their heterogeneous sedimentary environment while feeding, obviate the utility of sieve analysis for detecting the effects of dissolution.
Chemistry of a 7.5‐m sediment core from Lake Valencia, Venezuela1
Authors: Lewis William M. , Weibezahn Franz H.
Published: March 2010

A 7.5‐m core from the middle of Lake Valencia, Venezuela, was analyzed chemically and mineralogically. This information is interpreted with assistance from studies of the modern lake and other supplementary paleolimnological information. The basin appears to have been dry between 13,000 and 10,500 b.p. At about 10,000 b.p., a very saline lake formed. Saline but less extreme conditions prevailed until about 9000 b.p., as indicated by precipitated aragonite, high Mg:Ca ratios in the carbonates, and other indicators; salinity had been considerably reduced by 8000 b.p., when the lake almost certainly discharged water. Indicators including allogenic loading, Mg:Ca ratios, carbonate precipitation, shallow‐water cores, and microfossils suggest two subsequent returns to higher salinity, the latest of which began about 2500 b.p., causing the lake to become endorheic in a.d. 1727. The general sequence of events in the lake over the last 13,000 years is strikingly similar to sequences documented from the African lowland tropics. The chemical conditions of Lake Valencia have varied in a major way over the recent geologic past.
Effects of water‐table configuration on seepage through lakebeds
Authors: Winter Thomas C.
Published: March 2010

The interaction of lakes and groundwater is controlled in part by the configuration of the water table near a lake. Seepage from lakes does not occur if the water‐table mound between the lake and a regional groundwater discharge area is sufficiently high and the water‐table gradient between the mound and the discharge area sufficiently small. Water‐table configurations associated with two groundwater systems of different geometry were examined by digital simulation. For the first setting, there is no seepage from the lake if the water‐table gradient from the mound to the regional discharge area is ≲0.011; for the second, the critical gradient is about 0.009. Seepage from the lake occurs if water‐table gradients are greater than these two values. For various glacial terrains, in which most natural lakes occur, water‐table gradients of 0.010 or greater are most common in the more rugged end moraines consisting of silty till, and gradients of ≪0.010 are common in areas of ground moraine, outwash plains, and flood plains.
An analysis of the influence of ice on spring phytoplankton population structure in the southeast Bering Sea1
Authors: Schandelmeier L. , Alexander V.
Published: March 2010

Phytoplankton populations in the southeast Bering Sea were examined with respect to the influence of ice on population structure. Techniques of numerical analysis were applied to the data collected from 109 stations over a 3‐year period. Two major groups were present in spring—an ice‐edge group and a shelf‐break group. Our results suggest that the ice‐edge spring bloom is a distinct but short‐lived community, and that ice flora may act as an inoculum early in the spring bloom.
Physiology of photosynthesis by marine coccoid cyanobacteria—Some ecological implications
Authors: Morris Ian , Glover Hilary
Published: March 2010

Recent discoveries of minute coccoid cyanobacteria as ubiquitous and previously unrecognized components of the photosynthetic organisms of the oceans have raised important questions about their role in the primary productivity of the sea. We have identified photosynthetic characteristics of two strains of Synechococcus sp. which will determine their role in primary productivity. Photosynthesis and growth rate of these cyanobacteria saturate at very low irradiances. Their photosynthesis is sensitive to oxygen, suggesting a tendency for photorespiration. In natural phytoplankton populations, photosynthesis by cells <1 µm contributed more to productivity at lower than at higher light intensities. Cyanobacteria, therefore, might be expected to make a significant contribution to phytoplankton photosynthesis at the bottom of the euphotic zone.
Lateral compression and visibility in cladocerans
Authors: Zaret Robert E.
Published: March 2010

A simple mathematical model suggests that lateral compression affects a cladoceran’s visibility to fish. The results of a simple test using the lengths and widths of cladocerans suggest that handling by copepods probably does not exert any significant selection on lateral compression in cladocerans, but fish gill rakers and visibility to fish might result in such selection.
Photosynthetic response of lake plankton to nutrient enrichment: A test for nutrient limitation
Authors: Lean D. R. S. , Pick F. R.
Published: March 2010

Measurements of carbon uptake by lake plankton at different levels of added phosphorus reveal some phytoplankton strategies that contribute to their survival in low‐nutrient waters. Nutrient‐deficient populations seem to temporarily reduce, rather than enhance, photosynthesis when phosphorus becomes available. This contradicts the basic hypothesis of the 14C bioassay used to determine “limiting” nutrients in natural waters. The reduction of carbon uptake rate continues until either the nutrient addition is taken up or no further storage is possible; at this time carbon upake may be enhanced. Concurrent measurements of phosphorus uptake showed no light response unless the plankton were exposed to significant phosphorus concentrations in the dark for several hours. Phytoplankton seem to be adapted for and dependent upon intermittent events exposing them to nutrient‐enriched water. The ability of phosphate‐depleted plankton to take up phosphate in excess of their growth requirements was used to develop an index for phosphate deficiency. To normalize for different biomass levels, the optimum photosynthetic rate was divided by the maximum uptake velocity giving a range for the C:P maximum uptake from 1.2 to 206 for plankton samples of varying phosphate deficiency.
Products of photosynthesis in phytoplankton off the Orinoco River and in the Caribbean Sea1
Authors: Morris I. , Smith A. E. , Glover H. E.
Published: March 2010

Incorporation of [14C]bicarbonate into the major end‐products of photosynthesis (low molecular weight metabolites, lipid, polysaccharide, and protein) was measured at a number of stations in tropical waters. Stations with highest chlorophyll concentrations showed almost equal synthesis of low molecular weight metabolites, lipid, polysaccharide, and protein. The “oligotrophic” stations showed a greater incorporation into polysaccharide and protein and proportionally less into the other two fractions. Inshore stations also showed higher activities of the photosynthetic carboxylating enzyme, ribulose‐1,5‐bisphosphate carboxylase, in relation to that of the anaplerotic replenishment enzyme, phospho(enol) pyruvate carboxylase.

The inshore, high chlorophyll stations were characterized by higher particulate : chlorophyll ratios. However, the polysaccharide and protein contents (normalized to particulate carbon) were not higher in the offshore samples showing high incorporation of 14C into those polymers. Carbon‐specific assimilation rates were greater for total C incorporation than for incorporation into the various polymers. This was most marked when assimilation was measured only over a period in the light.
Loss rates from sedimentation, parasitism, and grazing during the growth, nutrient limitation, and dormancy of a diatom crop
Authors: Jewson D. H. , Rippey B. H. , Gilmore W. K.
Published: March 2010

Factors controlling the growth and decline of a diatom crop were measured in well mixed Lough Neagh, Northern Ireland. Net population increase in spring was interrupted for a short period, due to stormy weather causing changes in the underwater light climate. The increase in chlorophyll ceased when soluble reactive phosphorus was depleted, while biomass continued to increase until silica reached undetectable levels. Losses due to washout (between 0.25 and 0.5% of the crop per day), parasitism (4% infestation by chytrids), and grazing by zooplankton (mainly Cyclops abyssorum Sars) were small in relation to the net population growth rate of 4% per day. Sedimentation rate showed a rapid increase during calm weather at the time of nutrient limitation, with over 90% of the population of Melosira italica (Ehr.) Kutz. and Stephanodiscus astraea (Ehr.) Grun reaching the sediment. Changes in internal morphology and a drop in the adenylate energy charge from 0.81 to 0.55 indicated that these cells formed resting stages. Decay was limited until 4 weeks later when, in association with increased activity of the benthic fauna, 75% of the chlorophyll a was consumed in the next 40 days. This resulted in only 1% of the population surviving through to the following year.
Spines on diatoms: Do copepods care?1
Authors: Gifford Dian J. , Bohrer Richard N. , Boyd Carl M.
Published: March 2010

Calanus finmarchicus was allowed to feed on two forms of the diatom Thalassiosira weissflogii (=T. fluviatilis): normal cells, which are spinose, and cells which did not have spines. Filtration rates of Calanus on the spinose form were on average 1.7 times higher than on cells with no spines.
Circulation in Enewetak Atoll lagoon1
Authors: Atkinson M. , Smith S. V. , Stroup E. D.
Published: March 2010

Currents at Enewetak Atoll, Marshall Islands, were measured on the reef margins, in the channels, and in the lagoon. Lagoon circulation is dominated by wind‐driven downwind surface flow and an upwind middepth return flow. This wind‐driven flow has the characteristics of an Ekman spiral in an enclosed sea. Lagoon flushing is accomplished primarily by surf‐driven water input over the windward (eastern) reefs and southerly drift out the South Channel. Mean water residence time is 1 month, while water entering the northern portion of the atoll takes about 4 months to exit.
Role of Gulf Stream frontal eddies in forming phytoplankton patches on the outer southeastern shelf1
Authors: Yoder James A. , Atkinson Larry P. , Lee Thomas N. , Kim Hongsuk H. , McClain Charles R.
Published: March 2010

Continuous surface mapping of temperature, salinity, and chlorophyll along a 300‐km segment of the Gulf Stream cyclonic front defined the spatial scales of a large diatom patch that persisted throughout a 10‐day study. The patch was localized in the upwelled cold core of a Gulf Stream frontal eddy centered over the 200‐m isobath off Jacksonville, Florida, in April 1979. The 2 µg·liter−1 surface chlorophyll isopleth enclosed an area >1,000 km2 with an alongshore dimension of 130 km. Surface chlorophyll exceeded 5 µg·liter−1 within the upwelled cold core of the eddy, 10–100× higher than concentrations in Gulf Stream or resident shelf surface water. Diatoms dominated the patch with the maximum observed abundance >106 cells·liter−1. Several days after the initial shipboard mapping, the size, location, and strong chlorophyll gradients of the patch were confirmed with a surface chlorophyll image generated from an ocean color scanner (OCS) flown aboard a NASA U‐2 aircraft. We show that the upwelling associated with eddies forming along the Gulf Stream cyclonic front results in localized zones of high near‐surface production and plant biomass that lie adjacent to oligotrophic surface waters of the Gulf Stream.
Oceanography of the eastern Bering Sea ice‐edge zone in spring1
Authors: Alexander V. , Niebauer H. J.
Published: March 2010

The ice‐edge region of the southeast Bering Sea was studied in terms of the hydrographic regime, phytoplankton biomass, and primary productivity during the springs of 1975 through 1977. The results showed that a phytoplankton bloom occurs at the ice edge just as the spring ice‐decay period begins, and that this accounts for a significant proportion of the annual carbon input over the shallow shelf. The bloom is intensified in time and space by the influence of the ice edge on the physical structure of the water column. Specifically, melting ice seems to increase the stability of the water column, near and under the ice, by lowering the salinity. Frontal structure in salinity and temperature are apparent at the ice edge and are attributed to the melting ice but also, at times, to wind‐driven Ekman‐type upwelling.

These data are also related to recent short term (ca. months‐year) climatic fluctuations that seem to control the seasonal position of the ice‐edge zone relative to the shelf break. In “cold” years, the ice edge comes southward to the shelf break and overlies the more nutrient‐rich Alaska Stream/Bering Sea source water. In “warm” years, the ice‐edge zone does not reach this nutrient‐rich water. This may be important to the biology of the ice‐edge ecosystem.
Hydrographic observations and mixing processes in the New York Bight, 1975–1977
Authors: Han Gregory , Niedrauer Terren
Published: March 2010

A series of 15 hydrographic cruises in the New York Bight over 1975–1977 is described and analyzed. The cruises cover all seasons but focus primarily on spring and summer. Temperature and salinity data show wide seasonal and interannual variability. Each of the three regions—inner bight, midshelf, and outer shelf slope—has distinctive properties and dynamics.

The inner bight properties are affected primarily by river flow and wind‐driven flows up the shelf valley which often splits the freshwater surface layer into two plumes, one east and one west of the valley head. The “cold pool” temperature structure on the midshelf is different each year. The water with the lowest recorded temperature (2.58°C) was on the bottom after the thermocline formation in May 1977.

Mixing models of the inner bight confirmed previous estimates of residence time as 6.8 days and yielded Kr = 5 × 106 cm2·s−1 with an advective transport component of 1 cm·s−1 to the southwest. A model of the mixing of the lower layer cold pool on the midshelf with onshore, offshore, and upper layer waters yields Kx = 7 × 106 and Kz = 0.1 cm2·s−1 as the on‐offshore horizontal and vertical diffusion coefficients.
Phosphorus availability in Lake Memphremagog and its tributaries1
Authors: Peters Robert Henry
Published: March 2010

The percentage of total phosphorus in samples from Lake Memphremagog and five of its tributaries which was biologically available was measured on three dates, with criteria the distribution of radioactive P among exchanging fractions and the enzymatic release of soluble P from particulate P when stored with chloroform. In lake water, available P formed 83% of the total; in rivers much less (18–57%) was available. Large molecular weight phosphorus (>5,000 mol wt), separated by gel filtration, was usually the most refractory fraction, but substantial amounts of unavailable P were also associated with particles and small molecular weight P (<400 mol wt). Soluble P of intermediate molecular weight formed too small a fraction for determination of its availability. Variations in the percentage of available P in natural waters could substantially alter the biological effect of a given phosphorus load.
The influence of Acilius (Dytiscidae) predation on Daphnia in a small pond
Authors: Arts Michael T. , Maly Edward J. , Pasitschniak Maria
Published: March 2010

Experiments were performed in 100‐liter cages in which Daphnia pulex and larvae of the predatory dytiscid Acilius semisulcatus were enclosed. Results indicate that individual predators have feeding rate coefficients >20 liters·d−1 on all sizes of Daphnia combined and that the vertical distribution of Daphnia >1 mm long is significantly altered by the presence of this predator. Density of Acilius was determined in a small pond near Montreal, and simple calculations suggest that this macroinvertebrate predator, although occurring at a low density, may exert considerable influence on the numbers of Daphnia in the pond.
Hysteresis in relationships between discharge and water chemistry in the Fraser River basin, British Columbia
Authors: Whitfield Paul H. , Schreier Hanspeter
Published: March 2010

River loading rates are frequently determined from discharge and water chemistry relationships using regression techniques. Such methods were inadequate in a study of the Fraser River where hysteresis was present in most sampling stations. Over a 4‐year period the year‐by‐year fluctuations in hysteresis were relatively consistent but there were dramatic differences in its shape and direction between sampling stations in the same river basin. Events on two time scales were discerned: one forming minor loop relationships was related to individual storms, the other forming major loop relationships to seasonal changes. Conventional techniques are inadequate for dealing with this problem.
The isolation of cyclic adenosine 3′:5′‐monophosphate (cAMP) from lakes of differing trophic status: Correlation with planktonic metabolic variables1
Authors: Francko David A. , Wetzel Robert G.
Published: March 2010

The seasonal dynamics of particulate and dissolved cyclic adenosine 3′:5′‐monophosphatc (cAMP) were examined in the epilimnia and littoral zones of two trophically dissimilar lakes. Each cAMP fraction was found in quantities comparable to those reported for cultured phytoplankton species. Both cAMP fractions varied greatly in concentration during the season and between the oligotrophic and hypereutrophic lakes. Increases in phytoplankton community densities were paralleled by weight‐specific changes in particulate cAMP levels, depending on the phytoplankton species present. A linear relationship between cellular cAMP levels and in situ primary productivity rates was found in the oligotrophic lake. In both lakes, certain phytoplanktonic associations had particulate cAMP levels linearly related to chlorophyll a content and specific activity of alkaline phosphatase.
Assessment of factors limiting growth rate of Oscillatoria agardhii in hypertrophic Lake Wolderwijd, 1978, by use of physiological indicators1
Authors: Zevenboom Wanda , Bij de Vaate Abraham , Mur Luuc R.
Published: March 2010

Physiological information from chemostat‐cultured Oscillatoria agardhii Gomont has been used to assess the nature of factors limiting growth rate in a natural population of this cyanobacterium, which dominates the phytoplankton in Lake Wolderwijd. Phosphorus, light (E), and nitrogen limited the growth rate of the population at different times of year: E and P limitation, alternately during January, February, and March; P limitation during April and May; N followed by E limitation in June; N limitation in July until mid‐August, followed by P limitation until October; E limitation in October, November, and December. In winter, however, an effect of temperature on the phytoplankton growth could not be excluded. Internal nutrient and pigment contents cannot be used as physiological indicators without prior knowledge of the growth rates and light conditions in nature. Similarly, N:P ratios (internal or external) are not reliable indicators of N‐ or P‐limited phytoplankton growth. On the other hand, nutrient uptake capacity values (Vmax) are useful in assessing factors that limit growth rates in nature.
Wind stress effects on chlorophyll distribution in stratified eutrophic lakes1
Authors: Stauffer Robert E.
Published: March 2010

The spatial distributions of Chl a in eutrophic Lakes Mendota and Delavan, Wisconsin, were studied during the 1971–1972 stratified seasons. A surface bloom was present on only 6 of 64 sampling dates, always associated with calm, sunny weather following cold fronts. A subsurface Chl a maximum was often observed at 3–5 m, associated with a transient upper breeze thermocline. Analysis of distributed‐lag antecedent wind stress showed that stress during the 6 h immediately before sampling predicts lateral gradients in chlorophyll standing crop (CSC) unless slight recent stress follows both high stress and an important directional shift. The short response time agrees with fetch transit times for the surface wind drift current and lag times involving the epilimnetic set‐up. Increasing the average CSC increases its lateral response to wind stress, possibly because large standing crops tend to be buoyant and hence readily advected by the wind.
A nitrogen budget of the ribbed mussel, Geukensia demissa, and its significance in nitrogen flow in a New England salt marsh1
Authors: Jordan Thomas E. , Valiela Ivan
Published: March 2010

The annual nitrogen budget of a mussel (Geukensia demissa = Modiolus demissus) population in a salt marsh was determined and compared to the nitrogen budget of the marsh. During each tidal cycle in summer, the mussels filter a volume of water in excess of the tidal volume of the marsh. Yearly, the mussels filter 1.8 times the particulate nitrogen exported from the marsh by tidal flushing. Half the nitrogen filtered is absorbed by the mussels and half deposited as feces and pseudofeces (biodeposition). Of the nitrogen absorbed, 55% is excreted as ammonia. As a result, the mussel population releases more ammonia into the marsh water than does any other population in the marsh. Four percent of the nitrogen absorbed by the mussels is secreted in byssal threads, 20% invested in growth, and 21% released in gametes. Gametes are the largest component of mussel production to enter the food web, because mortality of adult mussels is very low.
Field and laboratory measurements of bivalve filtration of natural marine bacterioplankton1
Authors: Wright Richard T. , Coffin Richard B. , Ersing Curtis P. , Pearson Daniel
Published: March 2010

Clearance of natural bacterioplankton and phytoplankton by Mytilus edulis, Geukensia demissa, and Mya arenaria was measured in the laboratory. Of the three, only Geukensia proved capable of efficient clearance of bacteria. Field measurements of clearance across a 46‐m‐wide Mytilus bed showed substantial removal of phytoplankton but no effect on bacterial concentrations. Measurements of the living gill tissue of the two mussel species revealed closer spacing and more lateral overlapping of filtering cilia in G. demissa. The ability of Geukensia to filter bacteria appears to be a key adaptation to a food resource deriving largely from salt marsh primary production.
Subsurface flow in salt marsh peat: A model and field study1
Authors: Hemond Harold F. , Fifield Jayne L.
Published: March 2010

Subsurface flow within the peat at a site 15 m from the nearest creek in Great Sippewissett Marsh was investigated by field measurements and mathematical modeling. Tidal influence was found to be slight; the subsurfice flow regime was dominated by an upward flow of groundwater in response to evapotranspirational demand. This subsurface regime may be typical of much of the marsh, but does not describe conditions near the creekbanks. Sensitivity analyses show that permeability is the most important peat property influencing subsurface flow in the interior marsh.
Vertical eddy diffusivities in a large tropical lake1
Authors: Lewis William M.
Published: March 2010

Vertical eddy diffusivities below the thermocline were estimated for Lake Lanao, Philippines, from vertical heat transport. Mean values range from 1.08 cm2·s−1 at 22 m to 0.22 at 44 m. The values are not notably divergent from expected values in temperate lakes of similar sizes and depth.
Changes in pH and buffering capacity of lakes in the Colorado Rockies
Authors: Lewis William M.
Published: March 2010

A set of pH, alkalinity, and total residue data on lakes in the central Rockies for the period 1938–1960 is compared with a second set of such data taken on the same days of the year in 1979. The total comparison group includes 64 lakes, but some exclusions are made on the basis of water diversions and other complicating factors. A correction is made for variation among years in total runoff. After this correction, there remains a 17% (±2.2%) decline in alkalinity from the early samples to the 1979 samples. The total residue is lower (16%), as is the pH of surface water from the lakes (0.22 units). These changes are attributed to acidification of precipitation, which has been previously documented in the region.