bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on a Kentucky Knobs Lake. IV
Authors: KRUMHOLZ LOUIS A. , COLE GERALD A. 
Published: March 2010

Physical and chemical conditions in Tom Wallace Lake, Kentucky, were studied through three intermittent ice covers for a period of 49 days during January and February 1958.A Birgean heat budget, based on temperatures observed from a station over the deepest part of the basin, involved a loss of 80 g‐cal/cm2 for the entire period. However, temperature profiles made from several stations revealed that there was considerable vertical and horizontal turbulence within the water mass beneath the ice, and that isotherms were not horizontal.Although temperatures of the sediment and deep waters fluctuated, the direction of heat flow from the thin layer of profundal sediment was always upward into the overlying one or two meters of water. Most temperature changes at mid depths, especially at 5 m, were probably caused by lateral transport of heat, since vertical thermal gradients were nonexistent or very slight at those levels. The direction of thermal gradients in the uppermost one or two meters beneath the ice was more varied. At times heat seemed to be moving downward from the ice; at other times an inverse gradient was observed even though the upper water was gaining heat.On several days the vertical temperature profile could not be reconciled with the density of water as a function of the prevailing temperatures, and in a few instances these anomalous stratifications could not be correlated with available chemical data. Some relative‐density determinations of water from different depths showed on one occasion that there was no instability in spite of an anomalous temperature profile.Freezing‐out effects during times of ice formation, and diluting caused by rain and melting were reflected beneath the ice in changing values of total alkalinity, total iron, and total solids.Stratification and variation in values of dissolved oxygen, total alkalinity, iron, and total solids are discussed.
Algal Productivity in Salt Marshes of Georgia1
Authors: POMEROY LAWRENCE R. 
Published: March 2010

Gross primary production of algae in the intertidal marshes on the coast of Georgia was measured at various seasons. Measurements were also made of light, temperature, pH, depth of flooding at high tide, and sedimentary chlorophyll. Migration of the algae in the sediments was observed along creek borders.Production during low tide is 150 mg C/m2/hr in winter and 20–30 mg C/m2/hr in summer. Production under water, during high tide is 200 mg C/m2/hr in August and drops to 50 mg in winter. A relation between the changes in production and the regime of light, temperature, and tides is postulated. Changes in production during high and low tide alternate so as to result in a nearly constant daily production throughout the year. The annual gross algal production is estimated to be 200 g C/m2. Net production is not less than 90 per cent of gross production. Photosynthetic efficiency varied from 3 per cent to less than 0.1 per cent.
COMPARATIVE LABORATORY AND FIELD STUDIES OF PHOTOSYNTHESIS BY A MARINE PLANKTONIC DIATOM1
Authors: Tailing J. F. 
Published: March 2010

A study is described of the factors affecting measurements of phytoplankton photosynthesis by the much used field method, based upon changes of oxygen concentration in clear and darkened bottles as determined by the Winkler method. Unialgal cultures of a marine plankton diatom, Chaetoceras affinis, were used with short exposures of 1–3 hours in both laboratory and sea. Indications of a limitation of photosynthetic rate by inadequate CO2 supply were only found for culture media with pH raised by prolonged photosynthesis. Otherwise photosynthetic rates were unaltered by the bicarbonate concentration over a wide range, including that of unenriched sea‐water, or by cell sedimentation in unshaken cultures. A comparison of the Winkler and manometric methods of measuring oxygen production gave very similar results. High rates of photosynthesis were well maintained over the main period of each exposure, despite the development of oxygen supersaturation. Lower rates were however always found during an initial induction phase.Photosynthetic characteristics deduced from exposures in laboratory and sea, carried out almost simultaneously and with the same algal material, were in general agreement. Data from the experiments as a whole indicated the development of unusually high photosynthetic capacities at light saturation, assessed per unit content of chlorophyll a. The onset of light saturation, and the development of photo‐inhibition, occurred at intensities similar to those recorded for many other plankton algae. Some ecological implications of the findings are discussed.
STUDIES OF THE NIANTIC RIVER, CONNECTICUT WITH SPECIAL REFERENCE TO THE BAY SCALLOP, AEQUIPECTEN IRRADIANS1
Authors: Marshall Nelson 
Published: March 2010

The Niantic River is a shallow estuary with a tidal prism equal to half the mean low water volume of the basin, and with a twelve‐hour freshwater inflow of less than 3% of the tidal prism. The tidal waters mix offshore with the waters of eastern Long Island Sound, rich in plankton and nutrients. The estuary functions as an ecological concentrating system as the dense and varied populations of grazers consuming the food of these tidal waters benefit from the resources of offshore mixing in addition to the production endemic to the estuary.The disappearance of the eelgrass, Zostera marina, with the epidemic of the early 1930's permitted better circulation near the river bottom. Apparently this was advantageous to the bay scallop, which thereafter became the predominant sessile grazer with a production calculated at 2.2g C/m2/yr. Anchorage previously offered by eelgrass for the early setting stages of scallops was subsequently available through the abundance of small branching algae.The brief life history of a bay scallop is outlined on its shell as the surface laid down in each successive year appears rougher or more “weathered” than that formed the year before. By following this differentiation of shell surface, annual rings were determined with more certainty than in earlier studies. Though the time of year when the differentiation of shell surface commences may vary with populations and even with year classes, it is probably due to a common cause, seasonal change in growth rate being most likely. The life history interpreted from shells from Indian middens was essentially the same as observed for living scallops.The scallops of the Niantic River spawn from mid‐June through July. The young of a given year reach maturity and are the chief brood stock of the succeeding spawning season. Mortality rates for all sizes are high during all seasons and few individuals survive to the time of second spawning.The estuaries in which the bay scallop occurs have the following hydrographic features: the ratio of tidal volume to river flow is high, thus the salinity remains high; the basin is relatively shallow, with a resulting high ratio of tidal volume to the volume at low water; the circulation is such as to retain the planktonic scallop larvae in sufficient numbers for reseeding and to provide an adequate supply of planktonic food, perhaps in part supplied by offshore waters.
A QUANTITATIVE METHOD FOR THE COLLECTION AND MEASUREMENT OF STREAM PERIPHYTON1
Authors: Grzenda Alfred R. , Brehmer Morris L. 
Published: March 2010

Two methods for the collection and estimation of stream periphyton production are presented.The periphyton was collected on 1.4 dm2 plexiglass plates attached to a horizontal crossbar. The crossbar was supported by a vertical post driven into the stream bottom or supported by a concrete block. The plates were removed from the stream and the established population estimated by determining the absorbency of the ethanol‐soluble phytopigments and by gravimetric procedures.A reliable estimate of the population can be made from the phytopigment absorbency values if the latter are corrected for deviations from the absorbency:concentration relationship and if the substrata are removed from the stream before the growth is too profuse. Confidence limits are given for the phytopigment density:weight of organic material relationship.
RECENT AND POSTGLACIAL PRODUCTION RATES OF A MARL LAKE1
Authors: Wetzel Robert G. 
Published: March 2010

Pigment degradation products were analyzed spectrophotometrically in postglacial, 14C‐dated sediments from the central depression and a marl lakemount of Pretty Lake in northeastern Indiana. Fluctuations in pigment products were examined in relation to the development of the productivity of the lake and to environmental parameters that might effect differential rates of preservation and deposition. Agreement was good between quantities of pigment degradation products and organic matter and other paleolimnological indices of productivity. There was a major peak of pigment products per gram of organic matter following the Boreal period, subsequent regression of productivity with several lesser peaks, especially during the millennium 6,500–5,500 B.P., and a slow increase in recent times. Contemporary rates of primary production were extrapolated to the inception of the lake. A general inverse relationship was evident between chlorophyll degradation products per unit organic content and carbonate levels. Changing levels of carbonate are discussed in relation to contemporary nutritional interactions and photosynthetic regulation.Rates of sedimentation at the central depression of the lake differed markedly from those of the littoral lakemount. While the rates in the central depression accelerated, those of the marl lakemount fluctuated sigmoidally, greatly accelerated during the interval 9,000– 7,000 B.P. The lakemount ceased accretion abruptly 1 m from the lake surface at 2,740 B.P. The probable ontogeny of marl lakemounts is discussed.
FORAMINIFERAL POPULATIONS AND MARINE MARSH PROCESSES1
Authors: Phleger Fred B. 
Published: March 2010

Low marsh and high marsh foraminiferal populations are related to mean tide levels in some places. This information can be used to estimate tidal regime, current velocities, and water exchange in a coastal lagoon containing marshes if area and bathymetry of the lagoon are known. The least diverse faunas have agglutinated tests and occur in high runoff areas in tropical, temperate, and subarctic areas studied. The most diverse faunas contain abundant calcareous lagoon and open‐ocean species and result from invasion of undiluted marine water in an area of low runoff. High runoff causes displacement of marsh species into adjacent environments.Large standing stocks of foraminifera in most marshes indicate abundant food and high organic production. Fast deposition of detrital sediment is reflected in high ratios of living specimens to empty tests. Some strongly hypersaline marshes support large populations of calcareous species. Calcareous tests may not be preserved in ancient sediments because of low pH below the surface in most marsh sediments.
EFFECTS OF ALEWIFE PREDATION ON ZOOPLANKTON POPULATIONS IN LAKE MICHIGAN1
Authors: Wells LaRue 
Published: March 2010

The zooplankton populations in southeastern Lake Michigan underwent striking, size‐related changes between 1954 and 1966. Forms that declined sharply were the largest cladocerans (Leptodora kindtii, Daphnia galeata, and D. retrocurva), the largest calanoid copepods (Limnocalanus macrurus, Epischura lacustris, and Diaptomus sicilis), and the largest cyclopoid copepod (Mesocyclops edax). Two of these, D. galeata and M. edax (both abundant in 1954), became extremely rare. Certain medium‐sized or small species increased in numbers: Daphnia longiremis, Holopedium gibberum, Polyphemus pediculus, Bosmina longirostris, Bosmina coregoni, Ceriodaphnia sp., Cyclops bicuspidatus, Cyclops vernalis, and Diaptomus ashlandi.Evidence is strong that the changes were due to selective predation by alewives. The alewife was uncommon in southeastern Lake Michigan in 1954 but had increased to enormous proportions by 1966; there was a massive dieoff in spring 1967, and abundance remained relatively low in 1968. The composition of zooplankton populations in 1968 generally had shifted back toward that of 1954, although D. galeata and M. edax remained rare.The average size, and size at onset of maturity, of D. retrocurva decreased noticeably between 1954 and 1966 but increased between 1966 and 1968.
LIMNOLOGICAL OBSERVATIONS ON LAKE KARIBA DURING 1967 WITH EMPHASIS ON SOME SPECIAL FEATURES1
Authors: Begg G. W. 
Published: March 2010

Results of limnological recordings made during 1967 on Lake Kariba are described. Kariba is monomictic, mesotrophic, and has five defined basins, each of which exhibits its own individuality. The two upstream basins are riverine; they are flushed out in May by the Zambezi River floods and thereby assume turnover characteristics earlier than the other three basins, which are truly lacustrine with temperature‐induced turnover.Great amplitude of variation in water chemistry exists relating to the basin locality, biotope (river, estuary, cleared area, open water), time of year (turnover winter/summer), and depth. Generally, values of dissolved oxygen, conductivity, alkalinity, and pH fall from surface to bottom. When H2S is present, alkalinity and conductivity values increase. A chemocline follows the profile of the thermocline. Occasionally density currents occur at depth, particularly after the first seasonal floods. Transparency decreases toward the head of the lake and in all areas decreases after turnover.The source of H2S is the Salvinia‐infested rivers. Dissolved oxygen in the hypolimnion is depleted 4 to 5 months after turnover. The hydrobiological effects of Salvinia are discussed, and the influence of the bottom topography is described.
SEDIMENT PROFILE CAMERA FOR IN SITU STUDY OF ORGANISM‐SEDIMENT RELATIONS1
Authors: RHOADS DONALD C. , CANDE STEVEN 
Published: March 2010

An instrument is described that will take high resolution photographs of silt‐clay bottom types in profile. The bottom (10–20 cm) is penetrated by a slowly descending (⩽7 cm/sec) wedge‐shaped Plexiglas chamber, and the sediment profile that is cut is photographed. Such photographs reveal in situ details of bottom topography, sediment texture, depth of bioturbation, biogenic structures, and living positions of mud‐dwelling benthos.The instrument can be modified to take closeup vertical photographs of the bottom and to obtain undisturbed core samples.
PALEOLIMNOLOGY OF LAKE TEXCOCO, MEXICO. EVIDENCE FROM DIATOMS1
Authors: Bradbury John P. 
Published: March 2010

A 46‐in core from the lacsutrine sediments beneath Mexico City was analyzed to establish a stratigraphic sequence of diatom assemblages for use in interpreting the climatic and limnologic history of ancient Lake Texcoco.Diatoms were found in nearly every 20‐cm sample interval, and several major zones were established. Planktonic and benthonic‐epiphytic assemblages alternate throughout the core, both of fresh‐ and brackish‐water types. The alternations reflect the fact that the coring site is marginal to the main basin of the lake, and limnologic conditions change as water levels rise and fall.A freshwater planktonic assemblage dominated by Stephanodiscus niagarae in deeper parts of the core indicates that a large, cool, and possibly deep lake existed about 100,000 years ago, either because of pluvial or because of tectonic factors. This is replaced (depth 35 to 30 m) by a freshwater benthonic‐epiphytic assemblage characterized by Denticula elegans and other marsh diatoms. The marshes were probably maintained by springs from the shore when the lake was reduced to saline pools in the center of the basin.As water levels rose again (core depths 30 to 5 m), brackish water flooded the marshes, and brackish benthonic diatoms (such as Anomoeoneis costata, Campylodiscus clypeus, and Nitzschia frustulum) replaced the earlier floras. These were periodically replaced by brackish planktonic diatoms (as Cyclotella striata and Cyclotella quillensis) when the lake was deeper, but the earlier freshwater planktonic flora never recurred. The same brackish planktonic and benthonic diatoms that prevailed for several tens of thousands of years are found today confined to the brackish pools of Lake Texcoco that are remnants of the former larger lake. The long interval of fluctuating brackish floras probably represents Wisconsin time.The last 10,000 years of the lake’s history is marked by a return of the marsh flora, suggesting a climate drier than that of Wisconsin time. A marked climatic change, however, is not necessary to explain this last change in the diatom flora, and it seems likely that the pluvial climate inferred for the southwestern United States had less effect at the latitude of Mexico City (19° 30′) than farther north.
CHANGES IN THE CHEMICAL COMPOSITION OF SEDIMENTS OF LAKE WASHINGTON, 1958–1970
Authors: Shapiro Joseph , Edmondson W. T. , Allison David E. 
Published: March 2010

Comparisons are made among three cores taken in deep water in different parts of Lake Washington in 1958 and 1959 and two cores taken at one of the same locations in 1968 and 1970. During the interval between the two sets of cores, all the sewage effluent that had been causing eutrophication of the lake was diverted, and the lake began to regress to a relatively unproductive condition.All the cores show higher concentrations of organic matter, phosphorus, and nitrogen (expressed as a fraction of dry weight) in the top few centimeters than deeper, but in general, the higher surface values of the earlier material have decreased somewhat now that they lie below the surface in the recent cores. Nevertheless, it appears that the high phosphorus content of the sediment laid down in the years of maximum enrichment will continue to be indicated by a clear maximum, which was at a depth of 4.0 cm in 1970. Nitrogen, although enriched in present surface sediments, does not show a corresponding older maximum.In parts of the lake, erratic, very high concentrations of phosphorus are associated with several types of particles containing much iron. Fractionation of sedimentary phosphorus by a biochemical procedure showed that a large part (70–80%) of the phosphorus content of the mud is acid‐soluble, but that the fraction releasable by reduction decreases with depth.These conditions may be related to events in the hypolimnion; during each summer, a dense population of an undescribed iron‐depositing microorganism has been observed to form.
CYCLIC CHANGES IN INTERSTITIAL WATER CONTENT, ATMOSPHERIC EXPOSURE, AND TEMPERATURE IN A MARINE BEACH1
Authors: Pollock Leland W. , Hummon William D. 
Published: March 2010

Seasonal, tidal, and spring‐vs.‐neap changes in water content, atmospheric exposure, and temperature were studied within the interstices of a porous, semiprotected beach. Semidiurnal tides were nearly equal in amplitude and reached 120 cm from spring low to high. Overall mean grain size was 660 µm and mean sorting, 500 µm, with finer, better sorted, and more layered sand in the upper beach. Pore space averaged 36.5%.Water content at low tide reached minima of 10% pore‐space saturation in shallow sands of the upper beach; most sand above the minimum water table lost >50% of its water. The upper beach drained more completely at neap than at spring tides. Draining occurred more slowly than filling, and deeper sediments drained more slowly than shallow ones, resulting in a progressive landward delay of up to 4 hr in the water table’s “low tide.” Little seasonal variation was noted.Beach temperatures were basically those of the sea surface, modified by duration of exposure. Temperatures of sea and water table followed a gradual cycle of seasonal change, averaging IC/week. Daily temperature variations exceeding 5C were confined to the upper 10 cm of sand in mid‐ and upper beach areas. Neap tides exposed the upper beach for long periods and produced thermal extremes.Salvat’s concept of environmental zones along fine‐sand beaches was modified and applied to both superficial and depth vectors at this coarse‐sand beach.
OXYGEN CONSUMPTION BY THE SEABED IV. SHIPBOARD AND LABORATORY EXPERIMENTS1
Authors: Pamatmat Mario M. 
Published: March 2010

A shipboard method for measuring the oxygen uptake of undisturbed cores of sediment with their original overlying water and intact mud‐water interface gave the same results as in situ measurements at 22‐m depth. Hydrostatic pressures up to 18 atm have no effect on total oxygen uptake of cores from 180‐m depth. Partitioning experiments with intact cores show that oxygen uptake by inorganic chemical oxidation is often greater than respiratory consumption; in these experiments the rate of chemical oxidation decreases with decreasing oxygen tension, while the rate of respiration is relatively constant down to a critical oxygen concentration of about 1 ml/liter.Sweeping away the surface layer and exposing subsurface sediment, either in situ or aboard ship, leads to increased rates of oxygen uptake. Where chemical oxidation predominates, the rate of uptake is a function not only of oxygen concentration but also of stirring of the water overlying the sediment. Undisturbed cores where respiration predominates show a constant rate of uptake for many hours, even after cessation of stirring for 1 hr.Presumptive evidence is presented that active denitrification could be taking place as deep as 20–21 cm in the sediment of the continental shelf off Peru. The unknown relationship between chemical oxidation and anaerobic metabolism clouds understanding of the biological meaning of total oxygen uptake by the sediment, but this is still the best measure of the integrated biological activity in the seabed.
EFFECTS OF TEMPERATURE, SALINITY, AND SURFACE WATER FLOW ON DISTRIBUTION OF THE SEA SNAKE PELAMIS1
Authors: Dunson William A. , Ehlert Gary W. 
Published: March 2010

The pelagic yellow‐bellied sea snake Pelamis platurus is a surface feeder which apparently drifts passively with surface currents. In areas of horizontally convergent surface water flows, hundreds or even thousands of Pelamis are concentrated in slicks, apparently characteristic members of a community of organisms associated with slicks.The distribution of Pelamis in the tropical Indian and Pacific Oceans is correlated with surface water temperatures; colonization of the Atlantic Ocean has likely been prevented by low surface temperatures off the tips of South Africa and South America. Breeding populations apparently occur only in areas in which mean monthly temperatures exceed 20C. The upper lethal temperature of Pelamis is about 33C. Thermoregulatory diving may be a mechanism of avoiding heat death in tropical seas where surface water temperatures reach 31C and insolation is intense.Pelamis can survive in freshwater for periods longer than 6 months.