Re: [Killietalk] Cool water killies and related considerations

[Jaime Prieto <jaimeprieto at gmail_com>]

Hello to all.
Dr Watters, it is fantastic to be able to read somebody that explains
a topic so detailedly.
Firstly I need to apologize for my poor english, I would like to
express me in english like you, but I can't.

I Know the area From Bs As to Necochea(south of Bs As), and I Know the
area from Bs As to Ceibas (north of Bs As, state of Entre Rios).
I am from the south of Argentina, region called Patagonia, here there
isn't Austrolebias.
I go to Bs As in 2003 and 2004.
In both areas I found Austrolebias in september (from 15 to 30 of
September), sexed and bigs, in north I found A. alexandri in 4.5 to 5
cm. Because of that I think this fishs have at least 2.5 months old or
more, this mean that they born in first days of July, may be the eggs
developed in watter, and they born whit out a dry season.
In the south I found some A. aff robustus in last 19 September they
have 1 to 2 cm, and I think 1 month old, But I found some pools whit
A. bellottii sexed and bigs too, I think whit 2 to 3 month old.
In 19 September, the temp. of watter was around 18 º celcius.
One explanation, the temp in january in Rosario (Now) have a max of
35/36 whit normals 29 to 32 every days, except a raining day.
In ceibas last September 2003 we measure 28 /29 º celcius in a pool of
A. alexandri, and A. nigripinnis and A. bellotttii.
Greetings.


On Fri, 07 Jan 2005 10:01:22 -0600, Brian R. Watters
<bwatters at sasktel_net> wrote:
> Lee harper wrote:
> 
> >
> > In a message dated 1/6/05 11:11:00 PM, bwatters at sasktel_net writes:
> >
> > << I am not sufficiently familiar with the rainfall pattern in So. America
> > to argue with you. >>
> >
> > I don't think we are arguing. My point was that rainfall in the
> > autumn (April
> > to June) causes a rise in the water table and some flooding which in turn
> > begins the swimming phase of the annual killifish cycle. There
> > may be other
> > periods when they are submerged, but winter is a major period
> > when they are
> > actively growing and breeding and thus they are definitely cold
> > water fish. I was
> > reporting my own observations in the field about water
> > temperature. That was the
> > beginning and still is the title of this thread.
> >
> 
> To some extent, I think we are talking at cross purposes. My involvement in
> this thread started when I questioned the comment made by Curtis Smith that
> "......  their summer (our winter) is the dry season in
> Argentina and Uruguay when the pools dry up......."
> 
> There is a mountain of indisputable climate data to show that this is
> incorrect. The summer months (our winter months) in Argentina and Uruguay
> are the wettest months, in terms of rainfall.
> 
> If I interpret the climate data and your comments correctly, the situation
> for that region would be as follows:
> 
> The increased rainfall starts to build up in October reaching a high during
> December-March. Following March, there is a fairly sharp decline and
> July-August are the driest months. The build-up in the water table will take
> place over a number of months and is mainly due to the rainfall during the
> period December-March (rather than April to June as you suggest because
> these are relatively dry months ?). The water table will, however, remain
> high through the early part of the dry season because it lowers slowly.
> August is a good time to collect because the water table is still high
> enough to maintain pools of surface water and the fish have already hatched
> and grown to a decent size. August will also be relatively cool because by
> then it is the winter season. To use the same example as I did in my last
> message (the town of Rosario), the average air temperature in August is 11.4
> C (the coolest month is July at 10.1 C) whereas the warmest month is January
> at 24 C. Obviously, there will be some regional variations depending on
> local geography.
> 
> The situation is analogous in most respects to East and Southeast Africa. To
> take Malawi as an example, the rainfall season may start in
> November-December, reach a peak in February and by April the rains have
> ended. The best time to collect Nothos is late March-April at the end of the
> rainy season or the start of the dry season, when the water table is still
> high enough so that there are pools, the fish have grown to a reasonable
> size, the roads are mainly dry and one does not get rained on every day.
> Many of the seasonal pools will persist into June. The hottest months in
> Malawi coincide with the peak period of rainfall so, by April it is already
> starting to cool down. However, the difference between East Africa and
> Argentina-Uruguay is that the former is at or close to the equator so that
> the differences between summer and winter temperatures are not as great.
> 
> One thing that intrigues me about the Argentina-Uruguay situation is that
> while the temperatures are relatively very low at the time the fish are
> present in the pools, the temperatures that prevail during the incubation
> period of the eggs is substantially higher. This is not the case for
> conditions to which Notho habitats are subjected. The other interesting fact
> is that in that part of So. America there is still a significant amount of
> rainfall during the "dry" season. While this is not enough to maintain the
> surface pools that constitute annual fish habitats, nevertheless, the soil
> moisture content must be much higher than it is in Notho habitats during the
> "dry" season. In East and Southeast Africa the distinction between the wet
> and dry seasons is generally much more profound.
> ___________________________________________
> Brian R. Watters
> University of Regina
> Regina, Sask. S4S 0A2, Canada
> Ph: (306) 584-9161 (home); (306) 585-4663 (work)
> Fax: (306) 585-5433
> E-mail: bwatters at sasktel_net
> 
> To join the AKA see http://www.aka.org/pages/join.html
> Archives are at http://fins.actwin.com/killietalk/
> 


-- 
Jaime Prieto
Patagonia - Argentina


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