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Re: pH sexratio Pelvicachromis
Yes, I agree with you there. A. borellii is a weird little apisto. It comes from a different
climate zone, for the most part, and even has different behavioral and brood color patterns
compared to most apistos. That's why it's been placed in a species-group all by itself.
Mike Wise
jonathan wrote:
> Sorry Mike, you are right. Specific species and their distributions might
> involve other pH ranges in the remote corners of the watershed. I think
> what I was trying to convey is that since Rubin found pH to affect sex in
> developing A. borellii throughout 6.2 to 7.2, it seems that Romer's 4.5,
> 5.5, and 6.5 are not thoroughly investigating the spectrum but rather the
> acidic extreme of the speectrum specific to A. borellii.
>
> -------------------------------------------
> Jonathan Fung... Reef Geek
> Dalhousie University Honours Marine Biology
> Aqua Creations Inc. Assistant Manager
> writer for Marine Fish Monthly
> -------------------------------------------
>
> On Tue, 27 Feb 2001, jonathan wrote:
>
> >
> > Studies on the Amazon watershed indicate that the seasonal pH regime
> > fluctuates between 6 to 7.2. Thus, 4.5, 5.5, and 6.5 falls on the acidic
> > extreme of the pH variation spectrum found in natural annual pH regimes.
> >
> > Growth and development (specifically mitosis rates) are affected, even
> > while raising fry. At 82 F, eggs hatch after 2 days, at 72 F, eggs hatch
> > after 5 days. The window of sensitivity appears to be between 72hrs and
> > 800 hrs. I was implying growth as synonymous with development, my bad.
> >
> > Your suggestion sounds interesting, but I am only doing one thesis and
> > the deadline is approaching. Someone else might wish to try.
> >
> > -------------------------------------------
> > Jonathan Fung... Reef Geek
> > Dalhousie University Honours Marine Biology
> > Aqua Creations Inc. Assistant Manager
> > writer for Marine Fish Monthly
> > -------------------------------------------
> >
> >
> >
> >
> > On Tue, 27 Feb 2001, Mike & Diane Wise wrote:
> >
> > > Jonathan,
> > >
> > > Your use of the term "acidic extremes" bothers me. What pH values are "extreme" actually
> > > depends on the species being bred. There are many species that find pH 5.5 (e.g. A.
> > > paucisquamis) and even 4.5 (e.g. A. sp. Weißsaum) not only acceptable, but necessary for
> > > successful reproduction. Neutral to slightly alkaline conditions don't just produce
> > > unsuccessful spawns, but even the adults have problems surviving in them.
> > >
> > > You will also note that Römer & Beisenherz claim that spawning temperatures are not the
> > > primary sex determinant. It is the temperature at which the fry are raised. I imagine
> > > that growth could play a part in this. You might be able to test this by seeing if poorly
> > > fed fry raised at high temperatures produce the same sex ratios as well fed fry at lower
> > > temperatures (This assumes that both groups would grow at about the same rate.). If this
> > > could be proved, then we would see temperature being less important > for Apistogramma <
> > > than growth rate. Pelvicachromis, however, don't seem to work the same as apistos.
> > >
> > > Mike Wise
> > >
> > > jonathan wrote:
> > >
> > > > Romer and Beisenherz found that temperature has more effect than pH.
> > > > However, they only looked at 4.5, 5.5, and 6.5 which can be considered
> > > > acidic extremes. Furthermore, since temperature has an effect on growth
> > > > rate, it is possible that growth rate is a confounding variable.
> > > > Therefore, the validity of the claim is compromised.
> > > >
> > > > -------------------------------------------
> > > > Jonathan Fung... Reef Geek
> > > > Dalhousie University Honours Marine Biology
> > > > Aqua Creations Inc. Assistant Manager
> > > > writer for Marine Fish Monthly
> > > > -------------------------------------------
> > > >
> > > > On Tue, 27 Feb 2001, Jacques BESSON wrote:
> > > >
> > > > > Is the influence of the pH about sexratio on the fry of this fish the same as to
> > > > > apisto ?
> > > > > The study of Romer , about Apisto, concludes ( if I remember correctly) : " Low pH
> > > > > (5.5 and below) produced more males", and influence of temperature is more
> > > > > significant than pH.
> > > > > An idea about ?
> > > > > Thanks
> > > > > J.Besson
> > > > >
> > > > >
> > > > >
> > > > >
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