i would love to know if barbel are in brackish water in any numbers, i have a pet theory there is....j.w
Hi John,
It's long been known that freswater fish can inhabit regions of high salinity, such as the coarse species that are found in the estuaries of the baltic.
I would think barbel are no different in that they are capable of it.
The physical factors that prevent a freshwater fish from a rapid transformation from fresh water to high salinity, is the process of Osmosis, which will by a natural process affect the natural balance of salt in the fishes body. The the transisition was sudden wether from fresh to salt or vice versa, the fish would die very quickly.
The process would see a fish from freshwater absorb salt too rapidly for it's system to cope, it would basically die from dehydration very quickly.
The reverse would happen for a saltwater fish where if it where put straight into fresh water, the process of Osmosis would see the fish absorb fresh water faster than it's system could cope with, and also die quickly.
In the case of brackish waters - estuaries, the difference of salinity between
fresh river water and pure sea water is not so great either way that fish from both enviroments would not be able to cope with the change provided that it was gradual enough.
Theres an interesting article on some studies done on how the transition from fresh to salt water affects the cell structure of the gills in freshwater fish, the studies wre done on trout, if you can wade through the nuclear science
it makes interesting reading.
Here......
http://jeb.biologists.org/cgi/reprint/209/23/4591.pdf