Relationships between wind speed and gas transfer, combined with knowledge of the partial pressure difference of CO2 across the air-sea interface are frequently used to determine the CO2 flux between the ocean and the atmosphere. Little attention has been paid to the influence of variability in wind speed on the calculated gas transfer velocities and the possibility of chemical enhancement of CO2 exchange at low wind speeds over the ocean. The effect of these parameters is illustrated using a quadratic dependence of gas exchange on wind speed which is fit through gas transfer velocities over the ocean determined by the natural-14C disequilibrium and the bomb-14C inventory methods. Some of the variability between different data sets can be accounted for by the suggested mechanisms, but much of the variation appears due to other causes. Possible causes for the large difference between two frequently used relationships between gas transfer and wind speed are discussed. To determine fluxes of gases other than CO2 across the air-water interface, the relevant expressions for gas transfer, and the temperature and salinity dependence of the Schmidt number and solubility of several gases of environmental interest are included in an appendix.

Relationship between wind speed and gas exchange over the ocean

A method is described which permits measurement of sap pressure in the xylem of vascular plants. As long predicted, sap pressures during transpiration are normally negative, ranging from -4 or -5 atmospheres in a damp forest to -80 atmospheres in the desert. Mangroves and other halophytes maintain at all times a sap pressure of -35 to -60 atmospheres. Mistletoes have greater suction than their hosts, usually by 10 to 20 atmospheres. Diurnal cycles of 10 to 20 atmospheres are common. In tall conifers there is a hydrostatic pressure gradient that closely corresponds to the height and seems surprisingly little influenced by the intensity of transpiration. Sap extruded from the xylem by gas pressure on the leaves is practically pure water. At zero turgor this procedure gives a linear relation between the intracellular concentration and the tension of the xylem.

https://science.sciencemag.org/content/sci/148/3668/339.full.pdf

Sap Pressure in Vascular Plants: Negative hydrostatic pressure can be measured in plants.

Fish, like other living systems, must conform to the laws of thermodynamics. Fish gain matter and energy in food, and they lose absorbed matter and energy as a result of catabolism—which provides energy for maintenance and activity—and the elaboration of reproductive products. Physiological energetics, or animal bioenergetics, concerns the rates of energy expenditure, the losses and gains, and the efficiencies of energy transformation, as functional relations of the whole organism. The majority of such presentations commence with an energy-flow diagram indicating the main steps that the energy of food intake follows through the organism, and the paths of energy distribution. Each of these steps with their appropriate values is subject to quantitative change, depending on many biotic and abiotic factors. With the thought that the basis of these energy exchanges needs to be elaborated first, it was deemed more fitting to conclude with a quantitatively expressed flow diagram. An understanding of the physical, chemical, and biological basis on which the energetics is built, and the equivalents employed, constitutes the opening section of this chapter. Some necessary distinctions between mammalian and nonmammalian systems are made. An adequately nutritious diet is assumed; the basic source of fuel for the fire of life is solely derived from the food.

6 – Physiological Energetics

Quantitative fisheries stock assessment : , Quantitative fisheries stock assessment : , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Quantitative fisheries stock assessment

http://science.sciencemag.org/content/sci/168/3934/939.full.pdf

Cryobiology: The Freezing of Biological Systems

Spartina plants have continuous gas spaces from the leaves to the tips of the roots. Oxygen values in the roots are as low as 3 per cent and increase toward the stem. Carbon dioxide values are highest in the rhizome and decrease up the stem and toward the root tips. Oxygen and carbon dioxide moved through the plants at equal rates for equal gradients, and these rates agree with measurements made on plants in the marsh. Calculated oxygen and carbon dioxide fluxes for the observed gradients in the observed gas spaces agreed with measured fluxes. We conclude that gases move in and out of Spartina roots by diffusion through uninter rupted gas spaces within the plant.

Gas Transport in the Marsh Grass, Spartina alterniflora

Supercooling and osmoregulation in arctic fish

SYNOPSIS. Two groups of fishes, the tuna and the lamnid sharks, have evolved ounter-currentheat-exchange mechanisms for conserving metabolic heat and raising their body temperatures. Warm muscle can produce more power, and considering the other adaptations for fast swimming in these fish, it seems likely that the selective advantages of greater speed made possible by the warm muscle were important in the evolution of this system. Some tunas such as the yellowfin and skip jack are at a fixed temperature difference above the water, but bluefin tuna can thermoregulate. Telemetry experiments show that the bluefin tuna can maintain a constant deep body temperature during marked changes in the temperature of its environment.

Warm-Bodied Fish

The oxygen consumption of the undisturbed marsh surface, of well-stirred mud samples, and of aboveand below-ground portions of Spartina was measured as were oxygen and rcdox profiles and sediment particle size. All but the uppermost fraction of the sediment was oxygen free and the intensity of reduction was high in all but the best drained areas an d was not correlated with amount of reduced material present. The latter was, however, roughly correlated with primary productivity. The rate of energy degradation of the bacteria living in the marsh mud was increased about 25 times when they were supplied with oxygen. Spartina, the major marsh producer, consumes more oxygen than any other group. Next in importance are the bacteria of the mud.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1961.6.4.0388

Gas Exchange in a Georgia Salt MARSH1

A bottlenose porpoise was trained to dive untethered in the open ocean and to exhale into an underwater collecting funnel before surfacing from prescribed depths down to 300 meters. The animal was also taught to hold its breath for periods up to 4 minutes at the surface and then blow in the funnel. Alveolar collapse is probably complete at around 100 meters, and little pulmonary respiratory exchange occurs below that depth. Thoracic collapse was observ visually at 10 to 50 meters and by underwater television to 300 meters.

http://science.sciencemag.org/content/sci/166/3913/1651.full.pdf

John Kanwisher

Papers

Gas Transport in the Marsh Grass, Spartina alterniflora

Supercooling and osmoregulation in arctic fish

Warm-Bodied Fish

Gas Exchange in a Georgia Salt MARSH1

Respiration and deep diving in the bottlenose porpoise