When I was working in Tasmania, every year around spring time, fish farmers will be gearing up to move their fish from the freshwater ponds to the sea. How do you know when they’re ready? Visually, they will start to lose their parr marks, turning a wholly more silver colour.
When this happens, a random sample of fish are placed in seawater ponds for a ‘challenge’ trial. These fish are then taken to the lab and
we would take blood samples from salmon to check whether they were ready to go to sea. We would test their blood for any elevations in blood sodium or blood chloride. If they are able maintain these parameters within their normal reference range, then it means that the fish are ready to be trucked to sea cages. If not, then the fish are held back till they are ready.
But how does this affect the fish’s acid-base balance ? This paper tells us a little more…
| Aquaculture | |||||||||||||||||
| Volume 341, Number 5 (March 2012) | |||||||||||||||||
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The effect of environmental salinity on H+efflux in the euryhaline barramundi (Lates calcarifer) | ||||||||||||||||
| Authors: | J.C. Weakley, J.B. Claiborne, K.A. Hyndman, S.L. Edwards | ||||||||||||||||
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| Source: | Aquaculture, Volume 341, Number 5 (March 2012) | ||||||||||||||||
| Page Numbers: | 190 – 196 | ||||||||||||||||
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| Abstract: | Euryhaline fishes such as the barramundi (Lates calcarifer), have the physiological ability to move between waters of various salinities and are often exposed to rapid changes in ionic gradients that may alter acid–base homeostasis. It has recently been proposed that these species may utilize gill H+ATPase and Na+/H+exchanger mechanisms to regulate systemic pH, and that the differential expression of the acid/base relevant transporters is governed by environmental salinity. This study examined acid–base regulation in juvenile barramundi adapted to fresh, brackish, or salt water (ranging from 0 to 32ppt) and exposed to 1% environmental hypercapnia. Our findings suggest that barramundi increase net acid excretion in all salinities tested, with a more rapid response observed in fish adapted 22,5 and 32ppt. In contrast, the relative change in net H+transfers was greatest in the groups adapted to the lower salinities. Fish in 15ppt exhibited an apparent relationship between increased in net H+excretion and increases in branchial H+ATPase protein expression. | ||||||||||||||||
| Citation: | J.C. Weakley, J.B. Claiborne, K.A. Hyndman, S.L. Edwards . The effect of environmental salinity on H+efflux in the euryhaline barramundi (Lates calcarifer). Aquaculture, Volume 341, Number 5 (March 2012), pp. 190-196, ; | ||||||||||||||||
| URL: | http://ejournals.ebsco.com/direct.asp?ArticleID=4209B784BA6F79B35F3F | ||||||||||||||||
