247
pressure gauge
ure because the rain gauges used on land, if used at sea, are affected by the
wind disturbances around the platform and may also sample sea spray. The
precipitation values at sea are therefore mainly based upon indirect estimates.
predator-prey relationship there are several predator-prey relationships in a community. The dynamics of both populations react on each other. The number
of prey animals eaten per predator per time unit increases with prey density (functional response), as does the growth rate of the predator population
(numerical response). The impact of predation on prey mortality depends on
both responses. Hence predation pressure and rate of increase of the predator population are correlated with prey density, which can lead to density
oscillations in both populations.
predatory feeding --7raptorial feeding.
preservation (1) marine foods can be preserved deep frozen, dried, salted,
smoked, cooked, tinned, etc; (2) for scientific purposes (marine) organisms
can be preserved in chemicals like alcohol and formalin or deep frozen; (3)
populations can be preserved by limitation of their exploitation. Local,
national, and international regulations are necessary to preserve habitats and
(migratory) animals and plants.
pressure force per unit of surface, expressed in pascal (Pa) =1 newton m- 2 , but
in oceanography often in atmosphere (atm) or (deci)bar (1 bar = 0.987 atm
= 10 5 Pa). The pressure in the sea is related to depth by the hydrostatic equation. Usually the atmospheric pressure is assumed to be constant in the estimation of the subsurface pressure. Pressures in the oceans are often given in
decibars as 1 decibar equals roughly 1 m increase in depth. At the high pressures (> 1000 decibars) in the deep ocean some chemical effects occur
because equilibrium reactions will seek the smallest possible volume, thus
counteracting compression. Those known are limited to the bicarbonate
system and saturation of calcium carbonate as related to compensation depth.
Effects of pressure on deep-sea animals must be of great physiological
importance, but observations are few. Shallow-water organisms usually do
not survive several hours of pressures encountered in the abyssal zone (> 200
atm. at > 2000 m depth; --7zonation).
pressure gauge instrument used to determine the depth of an instrument (to
which it is attached) below the sea surface, or, alternatively, when mounted
at the sea bottom, to determine sea-level variations. An early method for
measuring the depth of an observation by means of a pressure sensor is the
combination of two reversing thermometers, one of which is not protected
against pressure and therefore gives a higher temperature reading. This
deviation can be used to calculate the pressure (depth).
pressure gauge
ure because the rain gauges used on land, if used at sea, are affected by the
wind disturbances around the platform and may also sample sea spray. The
precipitation values at sea are therefore mainly based upon indirect estimates.
predator-prey relationship there are several predator-prey relationships in a community. The dynamics of both populations react on each other. The number
of prey animals eaten per predator per time unit increases with prey density (functional response), as does the growth rate of the predator population
(numerical response). The impact of predation on prey mortality depends on
both responses. Hence predation pressure and rate of increase of the predator population are correlated with prey density, which can lead to density
oscillations in both populations.
predatory feeding --7raptorial feeding.
preservation (1) marine foods can be preserved deep frozen, dried, salted,
smoked, cooked, tinned, etc; (2) for scientific purposes (marine) organisms
can be preserved in chemicals like alcohol and formalin or deep frozen; (3)
populations can be preserved by limitation of their exploitation. Local,
national, and international regulations are necessary to preserve habitats and
(migratory) animals and plants.
pressure force per unit of surface, expressed in pascal (Pa) =1 newton m- 2 , but
in oceanography often in atmosphere (atm) or (deci)bar (1 bar = 0.987 atm
= 10 5 Pa). The pressure in the sea is related to depth by the hydrostatic equation. Usually the atmospheric pressure is assumed to be constant in the estimation of the subsurface pressure. Pressures in the oceans are often given in
decibars as 1 decibar equals roughly 1 m increase in depth. At the high pressures (> 1000 decibars) in the deep ocean some chemical effects occur
because equilibrium reactions will seek the smallest possible volume, thus
counteracting compression. Those known are limited to the bicarbonate
system and saturation of calcium carbonate as related to compensation depth.
Effects of pressure on deep-sea animals must be of great physiological
importance, but observations are few. Shallow-water organisms usually do
not survive several hours of pressures encountered in the abyssal zone (> 200
atm. at > 2000 m depth; --7zonation).
pressure gauge instrument used to determine the depth of an instrument (to
which it is attached) below the sea surface, or, alternatively, when mounted
at the sea bottom, to determine sea-level variations. An early method for
measuring the depth of an observation by means of a pressure sensor is the
combination of two reversing thermometers, one of which is not protected
against pressure and therefore gives a higher temperature reading. This
deviation can be used to calculate the pressure (depth).