286
J. H. 8. BLAXTER AND F. 0 . T. HOLLIDAY
body fluids and yolk were regulated to a concentration equivalent to
la%,. They showed that whereas newly hatched larvae died in distilled
water, larvae two days old survived for at least 24 hr, although the
body fluids were reduced in concentration to about 9.7%,.
3. Sites of regulation
These have not been determined experimentally in fish larvae.
Shelbourne (1957) suggested the epidermis, and this seems to be most
likely.
4. Effects on metabolism
It might be expected that as the degree of regulation required
depended on the difference between the environmental salinity and the
tissue concentration, more metabolic effort would be required to
survive in the extreme salinities. Lasker and Theilacker (19624 found
no difference in oxygen uptake in Sardinops caerulea larvae living in sea
water or in sea water diluted until it w a isotonic with the tissues.
This work was extended by Laaker and the present authors, who found
that there was no difference in oxygen consumption of herring larvae
incubated and hatched in salinities ranging from 5-50L. However,
some variations occurred in the few hours immediately following abrupt
transfer from one salinity to another, but as regulation was achieved
the value returned to its previous level.
5. Effects of starvation
Ivlev (1955) showed that there was little difference in salinity
tolerance between starved and normal C m p i a h a volgemis larvae,
although the range of salinitieH te~ted WRR #mall.
1. Oxygen uptake
ReRpirntory axehnngu in youngcor tarvat, afrnctst csrtainly takes
placa ovcr tho tmiy Hirrfncch. Ilartlor (1054) roportcal that thc gills of
hcrring were iiot functional until a lcngth of about 20 mm. Volodin
(1956) suggosted that carotenoids in tho yolk ected aIs respiratory
pigments. A scnsitive technique is required to meamro ths oxygon
consumption of singlo larvae. AH the activity of tho larvao is dominant
in determining the oxygcn requirement, comparisons of metabolism in
larvae of different age or in different environmental conditions are best
made on individuals anaesthetized to the same level (determined by
heart rate). Table I V gives values of oxygen uptake in some clupeid
larvae.
J. H. 8. BLAXTER AND F. 0 . T. HOLLIDAY
body fluids and yolk were regulated to a concentration equivalent to
la%,. They showed that whereas newly hatched larvae died in distilled
water, larvae two days old survived for at least 24 hr, although the
body fluids were reduced in concentration to about 9.7%,.
3. Sites of regulation
These have not been determined experimentally in fish larvae.
Shelbourne (1957) suggested the epidermis, and this seems to be most
likely.
4. Effects on metabolism
It might be expected that as the degree of regulation required
depended on the difference between the environmental salinity and the
tissue concentration, more metabolic effort would be required to
survive in the extreme salinities. Lasker and Theilacker (19624 found
no difference in oxygen uptake in Sardinops caerulea larvae living in sea
water or in sea water diluted until it w a isotonic with the tissues.
This work was extended by Laaker and the present authors, who found
that there was no difference in oxygen consumption of herring larvae
incubated and hatched in salinities ranging from 5-50L. However,
some variations occurred in the few hours immediately following abrupt
transfer from one salinity to another, but as regulation was achieved
the value returned to its previous level.
5. Effects of starvation
Ivlev (1955) showed that there was little difference in salinity
tolerance between starved and normal C m p i a h a volgemis larvae,
although the range of salinitieH te~ted WRR #mall.
1. Oxygen uptake
ReRpirntory axehnngu in youngcor tarvat, afrnctst csrtainly takes
placa ovcr tho tmiy Hirrfncch. Ilartlor (1054) roportcal that thc gills of
hcrring were iiot functional until a lcngth of about 20 mm. Volodin
(1956) suggosted that carotenoids in tho yolk ected aIs respiratory
pigments. A scnsitive technique is required to meamro ths oxygon
consumption of singlo larvae. AH the activity of tho larvao is dominant
in determining the oxygcn requirement, comparisons of metabolism in
larvae of different age or in different environmental conditions are best
made on individuals anaesthetized to the same level (determined by
heart rate). Table I V gives values of oxygen uptake in some clupeid
larvae.