[Zbrafish] Re: seasonal mortality?

David G. White via zbrafish%40net.bio.net (by dgw5079 from u.washington.edu)
Thu Dec 11 14:21:57 EST 2008


Chloramine maybe a factor here. The stability of this molecule can be troublesome. Here is a thought, during the fall the first few rains might "wash" the watershed clean increasing turbidity as it makes its way to the local water treatment plant. The plant that may already use chloramine to treat the water may increase the dosage during these times. Chloramine may do damage to fish over time and/or may have a more direct impact on your nursery fish survival. I would also imagine that chloramine would be harmful to your biofilter.

Activated carbon isn't 100% effective at removing chloramine. A bigger problem might be if you or someone else is treating the water for chlorine and you have chloramine. You would be producing a harmless chloride ion and toxic ammonia. But this would show up on routine testing. Whomever maintenance's your source water may not know the parameters needed for fish. There is a lot of background noise in trying to figure this out. The reason why most buildings even have a source of clean water RO/DI is for the HVAC system surely these systems operate differently as we pass from summer to fall. Since another fish lab in your building has a similiar problem one thing you probably both have in common is source water.



David G White
Research Coordinator
H225 Zebrafish Lab
University of Washington
Department of Biological Structure
HSB G514 Box 357420
1959 NE Pacific Street
Seattle, WA  98195-7420
Tel. 206-685-7512
FAX 206-543-1524

On Wed, 10 Dec 2008, Lawrence, Christian wrote:

> I see the logic in seasonal changes in water supply, but I guess the reason why I tend to not be much of a believer in this affecting survival in controlled facilities is that these changes, if and when they occur, should be for the most part be detected by routine water quality testing.
>
> However, I suppose at least one problematic parameter that would go undetected in most facilities (ours included) is chloramines/chlorines.  One could certainly imagine a scenario in which there is an increase in the use of such chemical treatments during the fall in certain regions, and if you're not testing for it (because you don't expect it to be there), AND your RO water service provider (if you have one) isn't checking for it, or isn't maintaining the RO system properly, then it could get through and be causing a problem.  In such circumstances, one could simply test for it to see if this might be the case and ensure that RO units be serviced regularly.
>
> But changes in other parameters, like pH, alkalinity, salinity, etc. should be readily observable and therefore correctable.
>
> The other issue is that aside from toxins or heavy metals, zebrafish - even larval and juvenile stages - are very tolerant of variable conditions. Or they should be, at least.  If they aren't, poor tolerance for challenges is likely indicative of an underlying problem more serious in nature.
>
> CL
>
> On 12/10/08 6:16 PM, "Jocelyn" <jocelyn.mcauley from gmail.com> wrote:
>
> Off list I received three emails indicating a shared experience of
> increased nursery mortality in fall.
>
> More about our parameters:
> + we have an RO/DI water source.
> + we have consistent personnel year round (ie full time staff, no
> student workers).
> + we feed powdered AP diet and raise brine shrimp for our nursery fish
> (no paramecia, rotifers, etc ).
> + another zebrafish facility in the same building reported anecdotally
> about similar problems at the same time.
>
> Will seasonal changes in city water persist through a RO/DI system?
> I'm coming to think so?
>
> thanks for your feedback.
> As always, its been interesting.
>
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