Re: [Killietalk] Couple of questions and observations

["Markus Brown" <thefishbiologist at charter_net>]

Barry and all...



It is interesting that fish, in general, can acclimate and thrive in high 
saline environments, but if you try to adapt them to an environment rich in 
Mg or even the common Ca+ ions, they tend to die immediately or wither and 
die. Many fish are more resistant of either substance in the water than 
others. The common Molly or even guppies can withstand incredible changes 
much better than the common characin or other cyprinids. I believe, the last 
I heard, is that the science of how some salmonids (Oncorhynchus mykiss, 
Salmo salar) can convert to salt and then back to fresh is still a bit of a 
mystery.



Markus


----- Original Message ----- 
From: "Barry Cooper" <bjc3 at centurytel_net>
To: "killifish discussion list" <killietalk at aka_org>
Sent: Thursday, February 02, 2006 4:03 PM
Subject: Re: [Killietalk] Couple of questions


> Yes. Low osmotic environments cause the cells to swell, with the
> potential to rupture, or at least become dysfunctional. Gill cells would
> be vulnerable due to their direct exposure. Fish need time to adapt to
> such changes, to allow the mechanisms they possess for pumping ions in
> and out to adapt. In biological systems water goes where ions go. There
> are no water pumps, but there are water channels, that also can be up
> and down regulated.
>
> Barry
>
> Barry J. Cooper
> Sweet Home, OR 97386
>
>
>
> Bill Shenefelt wrote:
>
>>Isn't going from High TDS to low TDS simply a matter of pressurizing cells
>>with more pure water entering the cell than minerals exiting the cell, 
>>maybe
>>to the bursting point?  Going the other direction although it may deplete
>>the cells at least does not explode them.  A small change 25% can be 
>>handled
>>by the fish'es system but larger changes (halving the TDS) or more reesult
>>in more stress and potentially death.
>>Bill Shenefelt
>>http://sheneskillies.com/
>>
>>
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>>
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