Showing papers on "Water flow published in 1980"

The Internal Element Cycles of an Old‐Growth Douglas‐Fir Ecosystem in Western Oregon

Abstract: Information on primary production, decomposition, hydrology, and element cycling was intergrated in annual budgets of accumulation and flux among components of a mature Douglas-fir forest ecosystem. Annual N input in precipitation and dust was 2.0 kg/ha, and an estimated 2.8 kg/ha were fixed by cyanophycophilous lichens in the canopy. Annual N loss to groundwater was 1.5 kg/ha. Microparticulate litterfall provided a large input of N to the forest floor. Total annual loss to ground water was 9400 eq/ha and, because of little cation accumulation, loss exactly balanced input. Net transfers of P were small. Total annual input was 0.5 kg/ha, total loss was 0.7 kg/ha, and net accumulation was -0.2 kg/ha. Input of elements in precipitation and dryfall was small compared with that in the Eastern United States. Water chemistry profiles showed that the biologically important elements N, P, and K increased in concentration as water passed through the canopy and litter layer but decreased as water passed through the rooted part of the mineral soil. In contrast, Na increased by a factor of 20 as water passed through the rooted soil. Concentrations of all elements except Mg were lower in the stream water than in solution at 2.0-m depthmore » in the subsoil. Total return to the forest floor in litterfall was greater than that reported for other Douglas-fir stands mainly because of plentiful microparticulate forms and coarse woody debris. Leaf fall accounted for less than half of the total litterfall input of N to the forest floor. Fluxes of hydrogen ions (H/sup +/) resulting from water flow were negligible compared with H/sup +/ release during carbonic acid dissociation and H/sup +/ removal accompanying cation release in weathering. Uptake of metalic cations by vegetation and release during decomposition exceeded uptake and release of sulfur and phophorus anions, resulting in a net H/sup +/ flux of approximately 1 x 10/sup 3/ eq x ha/yr.« less

The status of three ecosystem-level hypotheses regarding salt marsh estuaries: tidal subsidy, outwelling, and detritus-based food chains

Abstract: During the first 10 years of salt marsh research at Sapelo Island (1952–1962), three general hypotheses emerged as follows: (1) tides provide an energy subsidy that enhances productivity, (2) organic matter is exported from productive estuaries to offshore waters (outwelling), and (3) detritus rather than grazing food chains predominate in the salt marsh ecosystem. These hypotheses, which we judge to be “emergent properties” of the salt marsh estuary as a whole, have now been challenged and tested in many places up and down the coast. The tidal subsidy hypothesis has been verified sufficiently to stand as a general principle. Outwelling seems to be strictly a local question depending on relative productivity of inshore and offshore waters and the magnitude of water flow in and out of the estuary; some estuaries export while some import, and the material exported (or imported) may involve nutrients, organic matter, or organisms. Although dominance of detritus-based food chains has been verified for most shallow water estuaries (in contrast to dominance of the grazing food chain in open water marine habitats), recent work has indicated that detritus complexes are like autotroph-heterotroph microcosms with algae, protozoa, fungi and bacteria providing major energy sources for detritus consumers which in turn are the chief food for fish and higher trophic levels in general.

Errors Arising From Rapid Water Loss in the Measurement of Leaf Water Potential by the Pressure Chamber Technique

Abstract: In rapidly transpiring leaves, the water potentials of uncovered leaves measured in a pressure chamber were 0.2-0.7 MPa lower than the water potentials of leaves that were covered with a plastic sheath from just prior to their excision to the completion of the measurement. The error in the water potential of uncovered leaves arose from rapid water loss in the first 30 s after excision. The degree to which the water potentials were lowered depended on the rate of transpiration, the leaf water potential at the time of excision, the species, and whether the plants were grown in the glasshouse or field. It is suggested that the variation between species and between glasshouse-grown and field-grown plants arises from differences in water retention characteristics of plant tissue as well as to differences in the rates of transpiration at excision. The size of the error induced by the rapid water loss on diurnal changes in leaf water potential is demonstrated and the effect of the error in the calculation of turgor potentials and in the resistances to water flow through the plant is discussed.

The Suction Feeding Mechanism in Sunfishes (Lepomis): An Experimental Analysis

Abstract: The process of prey capture by inertial suction was studied in three species of sunfishes ( Lepomis auritus, L. macrochirus , and L. gibbosus ) by the simultaneous recording of buccal and opercular cavity pressures in order to test current hydrodynamic models of feeding in fishes. Synchronous high-speed films permitted the correlation of kinematic patterns of jaw bone movement with specific pressure waveforms. Opercular cavity pressures averaged onefifth buccal pressures and pressure magnitude was correlated with prey type. Peak buccal and opercular pressures were −650 cm H 2 O and −150 cm H 2 O respectively; peak rate of pressure change was −100 cm H 2 O/ms. Buccal pressure magnitude varied inversely with degree of predator satiation. Opercular pressure waveforms have an initial positive phase followed by a prolonged negative phase and then a final positive phase. The initial positive pressure may be absent during slow strikes at worms. Buccal pressure waveforms show considerable variability. The modal waveform consists of a sharp negative pressure pulse followed by a positive phase and finally by another pressure reduction. Delayed opercular abduction relative to mouth cavity compression correlates with the presence of a positive buccal phase. The second buccal negative pressure is the result of rapid mouth closing causing a pressure reduction (water hammer effect) as water flow continues posteriorly. These data indicate that (1) the buccal and opercular cavities are functionally separated by a gill curtain of high resistance, (2) that inertial effects of water are important in the description of the suction feeding process, (3) that a reverse flow of water (opercular to buccal cavity) may occur during the early phase of mouth opening prior to establishment of a buccal to opercular flow regime, and (4) current models of respiratory pressure and flow pattern cannot be applied to feeding. Current hydrodynamic models of suction feeding in fishes are re-evaluated in the light of this analysis.

Relation between particle size selection and clearance in suspension‐feeding ciliates

Abstract: Suspension-feeding, ciliated protozoans retain particles by sieving the feeding currents through ciliary organelles and show well-defined size spectra with respect to the particles retained and ingested. When different species of ciliates are compared, clearance is correlated with the particle size most efficiently retained. Thus, species specialized on particles of bacterial dimensions (0.2–1 µm) have a strongly reduced clearance, due to a decreased rate of water propulsion through the filter, from that of species specialized on larger food particles. It is suggested that this is related to the increased resistance to water flow in filters with a decreasing porosity, since cilia can only generate a small hydrostatic pressure. Ciliary suspension feeders specialized on small particles have relatively high requirements with respect to the minimum food particle concentration; they could not maintain populations at bacterial concentrations typical of offshore waters.

Applied Soil Physics: Soil Water and Temperature Applications

Abstract: This textbook presents a practical approach to teaching basic concepts of soil water and heat flow, with numerous examples and problems to assist the student. Soil water content and soil water potential are discussed and related to water flow and evapo-transpiration. The book also considers the relationships of soil physics to climate and crop production. Heat flow and the temperature of soils are treated as basic concepts that allow estimates of real world diurnal and annual fluctuations.

Observations and LDA measurements of confined turbulent vortex flow

Abstract: A series of LDA measurements and visual observations of confined turbulent vortex flow are described. The experiments were performed with water as the fluid medium in a vortex tube of length-to-diameter ratio L/D = 3.8 for a range of exit diameters De between De/D = 1 and 0.18. The experiments reveal a remarkable change in the vortex structure as De is reduced: from a thick core with an axial-velocity defect in the centre, and even reversed flow, to a thin annular jet-like core with a peak axial velocity more than an order of magnitude greater than the average value and again a central velocity deficit. The corresponding swirl profiles are not remarkable and are well-represented under all conditions by the solution of Burgers (1948), albeit with a velocity maximum which is strongly dependent upon De.

Comparative Resistance of the Soil and the Plant to Water Transport

Abstract: The resistances to liquid water transport in the soil and plant were determined directly and simultaneously from measurements of soil, root, and leaf water potentials and the flux of water through the soil-plant system to the sites of evaporation in the leaf. For soybean (Merr.) transporting water at a steady rate, water potential differences between soil and root were smaller than between root and leaf over the range of soil water potentials from −0.2 to −11 bars. As soil water was depleted, water flow through the soil and plant decreased to one-tenth the maximum rate, but both the soil resistance and plant resistance increased. The plant resistance remained larger than the soil resistance over the entire range of soil water availability. Previous suggestions that the soil is the major resistance have ignored the increase in plant resistance and/or assumed root densities that were too low.

The Use of a New Tilting Tunnel Respirometer to Investigate Some Aspects of Metabolism and Swimming Activity of the Plaice (Pleuronectes Platessa L.)

Abstract: 1.Plaice and other flatfish can be induced to swim down a slope of about 60° against an upwelling water flow in a water tunnel. 2. A tilting Brett-type tunnel respirometer based on the above principle enabled laboratory experiments on swimming plaice to be carried out. 3. From trials at 5°, 10°, 15 °C, the relationship between specific swimming speed, V (body lengths s −1 ), oxygen consumption, R (mg −1 . kg −1 h −1 ) and temperature, T is: log 10 = 0.3318 V + log 10 (2.45 T +26.52). 4. If the fish is resting (i.e. V = 0), the oxygen consumption is lower than predicted by the above equation. At rest: R = 3.14 T +2.66. 5. The cost of swimming in plaice is very similar to that of typical round fish such as haddock but the resting metabolic rate is lower than for haddock. 6. Before swimming, a negatively buoyant fish such as plaice must lift off the bottom. This cost of lift-off or posture effect makes it uneconomical for plaice to swim at speeds below 0.6 V .

Swimming in Amusium pleuronectes (Bivahia: Pectinidae)*

Abstract: Aspects of functional design in the Pectinidae have led scientists to speculate that scallops of the Amusium group (Hertlein, 1969) are among the best swimmers. This study of Amusium pleuronectes confirms this view, with average swimming speeds ranging from 37–45 cm/second. A speed of 73 cm/second was recorded from one scallop. Swimming times varied, on average, between 8–10 seconds; one scallop, however, swam for 18 seconds, covering a distance of 10 metres. This study has also investigated pertinent aspects of the functional design of A. pleuronectes, including the adaptations to the shell, mantle and musculature that increase swimming efficiency: These include: (1) A thin, very smooth, biconvex, rounded shell; (2) Internal strengthening ribs; (3) A small valve convexity; (4) A more central point of maximum valve convexity; (5) Upturned antero- and postero-lateral upper valve margins; (6) Emarginated anterior and posterior shell margins; (7) A highly elastic ligament; (8) A single large, centrally located, adductor muscle; (9) Small perpendicularly oriented “slow” and large obliquely oriented “quick” adductor muscle components; (10) Expulsion of water both antero-and postero-dorsally; (11) Highly muscular middle and inner mantle folds acting as a (mechanical) “valve” to direct and regulate water flow. It has occasionally been reported in the literature that small scallops swim “better” than large specimens of the same species; this has been investigated for A. pleuronectes and the general conclusion is that large scallops can swim just as well as small specimens (indeed distances covered are greater in animals of the former category), but that the threshold stimulus necessary for swimming to occur is raised. This is true also of the escape reaction; small scallops are much more likely to perform an escape response of between one to three adductions than large specimens which seem to rely more on sustained adduciion for protection. Earlier authors have advocated ontogenetic allometric growth changes in the position and obliquity of the “quick” component of the adductor muscle to explain how larger scallops overcome the increasingly negative forces of gravity and drag. No evidence of such allometric changes have been recorded for A. pleuronectes and the present author believes that the increasingly negative forces of drag and gravity are easily overcome by scallops of any size. Increasing weight with age and physiological ageing of the adductor muscle is probably sufficient to account for differences in swimming ability between small and large specimens of A. pleuronectes. It is finally concluded that swimming in A. pleuronectes is not a response to predation. Circumstantial evidence is presented which, when considered with the efficiency of swimming and aspects of functional design in this species, suggests that swimming is concerned with active and seasonal migration, possibly linked to reproduction.

Characteristics of Low Flows

Abstract: A Task Committee (TC) of the Surface Water Hydrology Committee was organized in 1976 to determine the types of low-flow information needed, to describe available methods of characterizing low flows, and to identify needed analyses and data collection. Responses to a TC survey of users of low-flow information indicated the need for better estimates of low-flow characteristics at ungaged sites. Available analytical methods are described and evaluated, sources of low-flow information are given, and some recently proposed techniques are reported. Low-flow data on many additional streams are needed.

Pinocytosis in plants

Abstract: Summary The question considered is whether pinocytosis is the principal means of transporting major nutrients across the plasmalemma. It is argued that ultrastructural evidence previously advanced in favour of pinocytosis in plant cells can be interpreted in other ways and does not uniquely support the hypothesis of pinocytosis. Physiological evidence - particularly, selectivity in uptake, competition between substances, differential effects on influx of changes in internal states, and the associated electrical currents - is incompatible with the characteristics of pinocytosis in animal cells. The suggestion that pinocytosis in plants involves selective binding prior to uptake cannot be accepted because the required density of binding sites is at least three orders of magnitude greater than is possible. On theoretical grounds it is shown that the water flow that would be associated with pinocytosis would generate high values of turgor which are not observed and probably could not be sustained. Further, it is calculated that during pinocytosis the probable energy to overcome turgor would be needed at a rate greater than the cell could supply. Thus it appears not only that pinocytosis does not occur, but also that it could not occur in plant cells.

Effects of Stream Habitat Improvements on Invertebrates, Trout Populations, and Mink Activity

Abstract: Two years of data were studied to determine the effect of increasing the brook trout (Salvelinus fontinalis) biomass in a section of stream on mink (Mustela vison) activity in the area. The study area consisted of 2 homogeneous sections of stream, one of which served as a control. The other section was improved by physically altering stream habitat. Habitat improvement resulted in trout population and biomass increases of 208% and 179%, respectively, after 2 years. Crayfish (Cambarus bartoni) biomass was 220% greater in the improved section. Mink activity, as determined by a modified sand-transect technique, averaged 52.5% higher in the area surrounding the improved section. However, mink did not respond to the trout biomass increases, nor was mink activity correlated with the activity patterns of any terrestrial prey species. Analysis of mink scats revealed that trout was not an important prey species, whereas crayfish occurred in 20% of all scats found, and in 50% of those from the study area. Thus, habitat improvement and the resulting increases in crayfish production resulted in greater use of that area by mink, but the trout biomass, which increased due to greater available space, mean section depth, and available cover, did not appear to be exploited by the local mink population. J. WILDL. MANAGE. 44(4):871-880 The mink is well recognized as a species inhabiting riparian habitats, and often depends on aquatic prey such as fish and crayfish as an important part of its diet. Alexander (1976) stated that mink are important predators of trout in Michigan, as did Erlinge (1969) for southern Sweden. Little is known of the food habits of mink in the southern Laurentians of Quebec; however, it might be expected that in areas where small trout streams abound, trout would form an important part of the mink's diet. Mink activity patterns also are said to be determined primarily by prey availability (Gerell 1970), which suggests that areas with high biomass of aquatic prey should be used preferentially by mink. Many factors influence brook trout production in streams, including water temperature, dissolved oxygen, pH, and food availability. Other physical factors, such as stream flow, water depth, cover, and available space are important population regulators. Where the latter factors are limiting, physical alteration of the stream habitat by modifying flow characteristics and introducing cover has been shown by Hubbs et al. (1932), Saunders and Smith (1962), Hunt (1972), and White (1975) to have great potential as a means of increasing trout populations. However, no attempt has been made to determine the indirect effects of these changes on use of improved areas by predators of trout. Cote (1970) investigated the ecology of brook trout in the typical southern Laurentian stream that we studied in 197677, and he found that although production of fry was extremely high, winter mortality of 1st-year fish, lack of cover, and heavy angling pressure resulted in poor trout production. Establishment of a management program involving creation of pools, introduction of cover, and restriction of angling should correct these problems. The piscivorous predators that comJ. Wildl. Manage. 44(4):1980 871 This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 05:38:57 UTC All use subject to http://about.jstor.org/terms 872 TROUT HABITAT IMPROVEMENT AND MINK* Burgess and Bider monly occur in the southern Laurentians of Quebec include mink, water shrews (Sorex palustris), belted kingfishers (Megaceryle alcyon), common mergansers (Mergus merganser), and great blue herons (Ardea herodias). However, in areas where the tree canopy is dense and the stream shallow, the mink is the only widely distributed and potentially important predator of trout. Aquatic prey, fish in particular, constitute a variable but often important part of the mink's diet, depending upon locality, season, and availability of alternate prey species. If mink depend on trout as a prey item in this area, a significant increase in the trout biomass in a section of stream should cause mink to concentrate their activity in that area. We acknowledge financial support from the National Research Council of Canada, Ministere de l'lEducation Quebec, and J. Hackney, Senneville, Quebec. Thanks also are extended to C. Wood, J. Struger, C. Smith, K. Asquith, and A. Denis, all of whom helped with the fieldwork. STUDY AREA AND PERIOD The study area was about 105 km northwest of Montreal, near the village of Lac Carre, in the southern Laurentians of Quebec. Local topography, climate, and vegetation were described in detail by Bider (1961, 1968). Vegetation on the area under investigation consisted primarily of speckled alder (Alnus rugosa), although white spruce (Picea glauca), balsam fir (Abies balsamea), white ash (Fraxinus americana), and willows (Salix spp.) also were present. The stream under investigation was a typical spring-fed mountain stream and the study area was about 8 km from its source. It was composed primarily of extensive riffle areas and had a mean September flow rate of 0.55 m3/sec. Mean depth was less than 0.3 m and the width was approximately 4-5 m. The streambed was composed of bedrock and gravel, and had some accumulation of organic matter in areas of reduced current. Large boulders and fallen trees served to deflect flow and create cover for trout. Data were collected from 22 June to 14 September 1976, and from 22 May to 9 September 1977. MATERIALS AND METHODS A 100-m section of stream that divides to form 2 roughly equivalent channels was chosen as an experimental area. These channels were approximately 3-4 m wide and had flow characteristics similar to those of the main stream. Sluices were constructed at the head of each section to allow the regulation of water flow through the 2 channels, as well as to enable the diversion of all water from either section whenever necessary. One channel then was improved, whereas the other was left as a control. Small dams were constructed of rocks and logs at various locations in the improved section, causing the formation of pools (up to 1 m deep and occupying approximately 50% of the channel) interspersed with riffles. Subsequently, cover in the form of logs, stumps, and rafts of alders lashed together (Saunders and Smith 1962) was placed at strategic locations, such as areas close to zones of abundant food, in the improved section. Large rocks also were placed randomly in the pools to provide the trout with a means of visual isolation, thus reducing intraspecific aggression as the population increased (Stewart 1972). The control section was unaltered, except for the regulation of water flow through it. Angling J. Wildl. Manage. 44(4):1980 This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 05:38:57 UTC All use subject to http://about.jstor.org/terms TROUT HABITAT IMPROVEMENT AND MINK* Burgess and Bider 873 was eliminated to nullify any bias that might be introduced by the removal of fish. Two factors that influence brook trout production and that might inadvertently be altered by stream habitat improvement are production and availability of aquatic insects and water temperature. Because the tree canopy over the stream allowed little direct solar radiation to penetrate, we felt that habitat manipulation should have no significant effect on water temperatures. To determine if this were the case, thermometers were placed near the outlets of both the experimental and control sections. Another thermometer, located in the pool upstream from the sluices, measured the temperature of the water entering the 2 sections. These were read twice daily, in the morning and evening, throughout the study, and daily averages were calculated. During summer 1976, 4 insect-emergence traps were placed randomly in both the experimental and the control sections to determine the effect of habitat manipulation on production of invertebrates. Traps were checked and emptied once a week for 7 weeks, beginning 12 July and ending 30 August. All specimens were preserved in 40% alcohol and labeled according to the date and location of capture. The number of insects per sample was counted and an analysis of variance was performed to determine the variation in emergence between lo-

Resistance to water flow in the sorghum plant.

Abstract: Knowledge of the location and magnitude of the resistance to water flow in a plant is fundamental for describing whole plant response to water stress. The reported magnitudes of these resistances vary widely, principally because of the difficulty of measuring water potential within the plant. A number of interrelated experiments are described in which the water potential of a covered, nontranspiring leaf attached to a transpiring sorghum plant (Sorghum bicolor [L.] Moench) was used as a measure of the potential at the root-shoot junction. This allowed a descriptive evaluation of plant resistance to be made.The water potentials of a covered, nontranspiring leaf and a nonabsorbing root in solution, both attached to an otherwise actively transpiring and absorbing plant, were found to be similar. This supported the hypothesis that covered leaf water potential was equilibrating at a point shared by the vascular connections of both leaves and roots, i.e. the nodal complex of the root-shoot junction or crown. The difference in potential between a covered and exposed leaf together with calculated individual leaf transpiration rates were used to evaluate the resistance between the plant crown and the exposed leaf lamina called the connection resistance. There was an apparent decrease in the connection resistance as the transpiration rate increased; this is qualitatively explained as plant capacitance.Assuming that the covered leaf water potential was equal to that in the root xylem at the point of water absorption in the experimental plants with relatively short root axes, calculated radial root resistances were strongly dependent on the transpiration rate. For plants with moderate to high transpiration rates the roots had a slightly larger resistance than the shoots.

FEMWATER: a finite-element model of water flow through saturated-unsaturated porous media

Abstract: Upon examining the Water Movement Through Saturated-Unsaturated Porous Media: A Finite-Element Galerkin Model, it was felt that the model should be modified and expanded. The modification is made in calculating the flow field in a manner consistent with the finite element approach, in evaluating the moisture-content increasing rate within the region of interest, and in numerically computing the nonlinear terms. With these modifications, the flow field is continuous everywhere in the flow regime, including element boundaries and nodal points, and the mass loss through boundaries is much reduced. Expansion is made to include four additional numerical schemes which would be more appropriate for many situations. Also, to save computer storage, all arrays pertaining to the boundary condition information are compressed to smaller dimension, and to ease the treatment of different problems, all arrays are variably dimensioned in all subroutines. This report is intended to document these efforts. In addition, in the derivation of finite-element equations, matrix component representation is used, which is believed more readable than the matrix representation in its entirety. Two identical sample problems are simulated to show the difference between the original and revised models.

Detection, pursuit, and overgrowth of tropical gorgonians by milleporid hydrocorals: perseus and medusa revisited.

Abstract: Encounters leading to competitive interactions between colonies on coral reefs are to some extent accidents of patterns of recruitment and growth. In contrast, colonies of Millepora spp. actively detect nearby arborescent gorgonians and subsequently redirect growth in order to contact and overgrow them. Detection is dependent on water flow over the two colonies.

Hydrophilic monomer treated microporous films and process

Abstract: The present invention is directed to a process for rendering a normally hydrophobic polyolefinic open celled microporous film relatively permanently hydrophilic, improving the water flow rate therethrough, and reducing the electrical resistance thereof by chemically fixing a controlled amount of at least one hydrophilic organic hydrocarbon monomer to the surface of the micropores of the film with ionizing radiation. The amount of hydrophilic monomer which is chemically fixed to the surface of the micropores is controlled to avoid plugging of the pores subsequent to the radiation treatment.

A subharmonic route to turbulent convection

Abstract: It has recently been discovered that the transition to turbulent convection can occur in a variety of qualitatively distinct ways as the temperature difference across a fluid layer is increased.'-' One common route to turbulence involves a succession of instabilities, which cause the fluid to oscillate quasi-periodically a t two, or sometimes three, incommensurate frequencies. These oscillations can exhibit phase locking and the interactions among them can result in broadband spectral noise in the velocity field.',4 The resulting nonperiodic motion may be defined as the onset of turbulence. A second route to turbulence involves successive subharmonic bifurcations, each of which halves the characteristic frequency of a periodic oscillation.',' I t has been known for some time that a one-parameter family of maps on an interval can show a sequence of subharmonic bifurcations.' Furthermore, maps can be generated from continuous flows by observing the intersections of trajectories with a fixed hyperplane in phase space. Thus, it is not far-fetched to imagine a connection between the properties of maps and the physical behavior of a fluid system. Feigenbaum has recently shown that a wide class of maps with a single extremum exhibit a sequence of subharmonic bifurcations as a parameter X is varied, with the bifurcation points, A,, forming a geometric series in the limit,\

Hydro-electric power plant

Abstract: A hydro-electric power plant for use in any location having flowing streams of water including a diversion dam which extends part way into the flowing stream to divert water to a spillway which includes a plurality of water wheels driven by the water flow to operate turbine-generators for the generation of electricity.

Microhabitat resource use, activity patterns, and episodic catastrophe: conus on tropical intertidal reef rock benches'

Abstract: Low species richness (five to nine species) and high population density (means of 0.2-8.6 individuals per square metre) characterize Conus assemblages on intertidal benches throughout the tropical Indo-West Pacific region. Data from 16 such habitats in Hawaii, Marshall Islands, Australia, Maldives, and Seychelles indicate that similarity of microhabitats between species is equal to or greater than random expectation. Significant between-species differences in zonation pattern occur across benches at a given time and place. The peak of C. ebraeus abundance typically occurs closest to shore; C. chaldaeus and C. sponsalis are usually most distant from shore. However, we found about as many significant within-species differences between censuses made at different times on the same bench as between-species differences within censuses. Co-occurring species thus tend not to use microhabitat resources differentially. Physical environmental variables including tide level, strength of water flow and time of day determine refuging and foraging activity patterns, and all species apear to respond similarly to these factors. The data thus do not support the hypothesis of temporal resource partitioning. We found evidence neither for homing, as mark-recapture results suggested that individuals occupy any convenient refuge after foraging, nor for interference competition for protected sites among Conus. Conus speciesmore » diversity is significantly correlated with (1) substrate topographic diversity measured either independently or as the diversity of microhabitats utilized by all species together, and (2) the proportion of individuals occupying protected sites.« less

An endogenous rhythm in shell deposition in cerastoderma edule

Abstract: The intertidal bivalve, Cerastoderma edule, when grown under constant conditions of temperature, salinity, water flow, light and food supply lays down faint internal shell bands at approximately semi-diurnal intervals, though with wide variations in periodicity from individual to individual. Animals grown continuously immersed under natural light/ dark cycles on a raft or below the tide marks produce similar bands. These bands are very faint compared with those in the shells of animals grown intertidally or under simulated semi-diurnal tidal conditions of emersion and immersion. The bands of intertidal animals also differ in their almost exact coincidence with the number of emersions. Cockles subjected to a diurnal cycle of immersion lay down strong bands coinciding approximately with the number of daily emersions, together with irregular faint bands. Thus the total number of bands exceeds the number of emersions.

Chapter 26 Relationship between Localization of Na+-K+-ATPase, Cellular Fine Structure, and Reabsorptive and Secretory Electrolyte Transport

Abstract: Publisher Summary This chapter emphasizes the development of morphological methods to delineate the interrelationships among Na + –K + -adenosine phosphatase (ATPase), cell and tissue architecture, and the ability of reabsorptive and secretory epithelia to couple electrolyte transport to water flow in the elaboration of hypo-, iso-, and hyper-osmotic fluids in view of the common structural and enzymatic specializations of transporting cells. Three independent techniques with a high level of specificity and with adequate sensitivity may localize Na + –K + -ATPase: the cytochemical and immunoferritin techniques provide resolution of Na + pump localization at the ultrastructural level, whereas the autoradiographic method delineates an Na + pump distribution at the light microscopic level. Sodium ion pump sites appear to be distributed uniformly along the expanded basolateral surfaces that delimit the intercellular channels. The nonluminal localization of Na + pumps in secretory epithelia suggests a model for NaCl secretion in which Na + follows a paracellular route to reach the lumen via low resistance zonulae occludentes.

Field studies of water relations and photosynthesis in Scots pine using manual techniques.

Abstract: Water potential, stomatal conductance, rate of photosynthesis and stem radial changes in Scots pine {Pinus sylvestris L.) were measured in a 120-year-old and a 20-year-old stand, the latter stand submitted to differing nutrient and water regimes. Water potential was measured on fascicles with a pressure chamber, stomatal conductance on shoots with a null balance diffusion porometer and rate of photosynthesis as incorporation of 14C02 into separate needles. Stem radius changes were measured with strain gauge transducers connected to a computer system. Interrelations between the variables as well as their relations to abiotic and biotic variables were studied. Calculations were made of the transpiration rate and the apparent total liquid pathway conductance from bulk soil to needle. A high sensitivity of total liquid pathway conductance to varying soil water potential was found. About 60% of the total liquid resistance from bulk soil to needle was found in the soil-root part of the system in a 20-year-old Scots pine, while the resistance at about the same flow rate in the soil-root part of the system in 120-year-old trees was calculated to about 30% of the total liquid resistance, in spite of low soil water potential. A stem height gradient of 0.2-0.8 bar mr1, depending on prevailing water flow through the soil-plant atmosphere continuum was found. Fertilization and irrigation were both found to affect water potential in the stand, causing smaller amplitude in the diurnal variation of water potential. Reasons for this and the influence of differing water status and nutrient regimes on radial stem increment rate are discussed. Additional keywords: 14C02-technique, fertilization, irrigation, liquid pathway conductance, stand height gradient, stem radial change, stomatal conductance, water potential.

Solvent drag of large solutes indicates paracellular water flow in leaky epithelia

Abstract: Net fluxes ( J s n ) of sucrose, inulin, dextran (relative molecular mass 15000–17000), albumin and haemoglobin were measured across guineapig gall bladder unilateral preparations in which the absorptive flow ( J v ) was varied over a wide range (without transepithelial osmotic gradients) by perfusing their lumina either with isosmotic solutions or with solutions of reduced osmolalities (a procedure that increased J v ). The absorptive flow J v was inhibited by 10 –4 M ouabain. The net flux J s n was a linear function of J v for sucrose, inulin and dextran, the slopes being inversely related to the size of the solute. Albumin and haemoglobin barely crossed the preparation. The large increase in J s n cannot be accounted for by increased leakiness of the preparation or by unstirred layer effects. The logarithms of the unidirectional flux ratios for sucrose, inulin and dextran in bilateral preparation were also linear functions of J v . It is concluded that solvent drags these solutes via the paracellular pathway. More than 50% of the water flows paracellularly also under normal physiological conditions, since J s n for sucrose was also a linear function of J v in experiments performed only at the physiological osmolality (0.3osm). This value is calculated from the slope of the line relating J s n to J v .

Hydraulic turbine system with siphon action

Abstract: The hydraulic turbine system includes: an electric generator; rotary turbine blades; a hydraulic pump for operation by rotation of the turbine blades; a hydraulic motor for driving the generator; a hydraulic reservoir; and connections between the pump, the motor and the reservoir for causing the motor to operate in response to rotation of the turbine blades by water flow In the present improvement, the turbine blades and the hydraulic pump are unified in an axial flow unit which has an annular outer casing through which water flows to drive the turbine blades which in turn drive the pump The motor, the generator and the reservoir may be located remotely from the axial flow unit The axial flow unit is preferably generally U-shaped so that it can be placed inverted over a dam with the legs extending down into the water on opposite sides of the dam A priming unit is provided for starting flow of water through the axial flow unit, and the priming unit may preferably include a vacuum pump connected to the casing for pumping air from the casing to draw water up into the legs thereof until water starts flowing by siphon action