Osmotic and structural changes during early development of eggs and larvae of the cod, Gadus morhua L.

• Published in: Journal of Fish Biology
• Main Authors: Davenport, J., Lønning, S., Kjørsvik, E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1981
• Subjects: Gadus morhua
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1981.tb05835.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1981.tb05835.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1981.tb05835.x

Newly extruded cod eggs have a similar osmoconcentration ( c. 400 mosmol kg ‐1 ) to maternal blood, maternal ovarian fluid and paternal semen. After extrusion, average egg osmolarities rise rapidly to about 520 mosmol kg ‐1 but this is entirely due to the cortical reaction resulting in the formation of a perivitelline space filled with fluid isosmotic with the external medium. The ovoplasm remains at around 400 mosmol throughout development; free swimming cod larvae also possess body fluids of this concentration. Over the salinity range 10.2‐37.4% 0 , salinity had no effect on egg dimensions and average egg osmolarities were consistent with a model assuming changes in perivitellic fluid concentration only.