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Eric A. Laux wrote:
>
> I did my graduate work on fish and egg survival after passing through hydro
> power turbines. We would collect eggs in the tailrace and try and incubate
> them in floating, flow thru chambers. I noted that we had some egg survival
> in early parts of the year, prior to excessive periphyton growing on the
> chambers, but in the heat of the summer, when periphyton levels were high, we had no survival of eggs. I had pondered the idea that periphyton may be the cause, but found nothing pertinent in the literature.
It may be worthy of note that a number of bottom egg laying fishes,
including cyprinids, scour the bottom or build fresh nests of pebbles,
before laying their eggs. Perhaps this avoids problems with periphyton
- night-time oxygen consumption, dampening of water flow over the eggs
reducing oxygen supply, or even possible toxic effects from the algae.
don
--
Don E. McAllister /& Canadian Centre for Biodiversity
Ocean Voice International /Canadian Museum of Nature
Box 37026, 3332 McCarthy Rd. /Box 3443, Station D
Ottawa, ON K1V 0W0, Canada /Ottawa, ON K1P 6P4
URL: http://www.ovi.ca E-mail: [log in to unmask]
(or: [log in to unmask]) Tel: (613) 264-8986, Fax: (613)
264-9204
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