## Abstract Both male and female blue crabs were shown to hyperosmoregulate efficiently at low salinities. The posterior gill pairs, particularly numbers six and seven, exhibited the highest specific activity of Na, KβATPase in crabs adapted to fullβstrength seawater. When the crabs were acclimated
The influence of environmental salinity on hemocyanin function in the blue crab,Callinectes sapidus
β Scribed by Weiland, A. L. ;Mangum, C. P.
- Publisher
- John Wiley and Sons
- Year
- 1975
- Tongue
- English
- Weight
- 671 KB
- Volume
- 193
- Category
- Article
- ISSN
- 0022-104X
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β¦ Synopsis
Abstract
The effects of inorganic ions and of the hydrogen ion on oxygenβbinding properties of most respiratory pigments are opposite. The addition of salt to the medium increases oxygen affinities, and the addition of H+ decreases oxygen affinities of crustacean hemocyanins. These oxygenation properties, as observed in vitro, suggest that the oxygenβtransport system must adapt to ionic changes in the blood.
In fact, decreases in the salt concentration of the blood of estuarine blue crabs are accompanied by increases in pH, probably resulting from the input of ammonia produced in deamination of the intracellular pool of free amino acids as the cells conform to osmotic changes in body fluids. The result is a stability of hemocyanin function until the blood becomes very dilute.
As the acclimation salinity is reduced from 35 to 15 o/oo, the ionic effects on respiratory transport are balanced and there is no change in total oxygen uptake. At 5 o/oo salinity, however, the higher blood pH is manifested in an elevation of the total oxygen concentration of prebranchial blood, probably because the Bohr shift is no longer opposed by a critical level of salt in the blood. Under these conditions the role of hemocyanin in aerobic respiration is reduced at high environmental oxygen levels, but it may be enhanced in hypoxic waters.
π SIMILAR VOLUMES
Juvenile blue crabs, Callinectes sapidus, extensively utilize oligohaline and freshwater regions of the estuary. With a presumptively larger surface-area-to-body weight ratio, juvenile crabs could experience osmo-and ionoregulatory costs well in excess of that of adults. To test this hypothesis, cra
## Abstract The output of ammonia increases in dilute waters in which blue crabs absorb Na^+^ against a gradient, but not those in which crabs remain in salt balance with the medium. Net acid output does not clearly vary with salinity. The balance between ammonia and urea output shifts towards ammo
## Abstract Blood PO~2~ in the blue crab __Callinectes sapidus__, a very active species of tropical origin, is lower at 22Β°C than that of larger crabs in colder waters. These low oxygen levels permit its hemocyanin to be highly oxygenated at the gill, and to deliver almost half of its oxygen to the