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Lake Victoria

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Lake Victoria

Postby Becca » Tue Mar 02, 2010 9:24 am

I Have been discussing a topic on another forum about lake tanganyika and the crossing of frontosa collection points....anyway someone compared it to the situation in lake victoria (females breeding with different males) and put this up explaining why the victorian cichlidss are not as true as they used to be... just wondering if this is correct, as i dont really understand what the situation is in Victoria and the problems with the cichlids hybridising:

"As far as what happened in Victoria.
Cichlids in tanganyika evolved with the perch present, so they have been fine, it has not impacted them, though its not the same Lates as in Victoria, it is a predator nevertheless.

The next component that has ruined Victoria is pollution from industrial runoff.
Like Victoria industrial and farming runoff is starting to impact fish in Burundi and Zambia.
what happened in Victoria is that Lates not only ate all the cichlids, it caused them to also move higher in the surface, to areas they would not normally eat.

The runoff has made the water murky in the shallows
and hypoxic at deeper levels, so now, females can't tell the subtle differences between "SPECIES", so they cross with any male they see.
so there is natural hybridization occurring in the lake.
It always was happening but now its a larger scale.

There is always going to be a cross breeding issue.
Too hard to ID frontosa from frontosa.
Too hard to ID VIC female from other VIC female, plus even if pure, the same type VIC in one tank will look different than another tank."
Becca
 

Re: Lake Victoria

Postby mbunasam » Tue Mar 02, 2010 10:40 am

:text-goodpost:

I've always wondered if at the meeting points they were full of hybrids


Shame if tanganyika becomes polluted like victoria
mbunasam
 

Re: Lake Victoria

Postby Paul B » Tue Mar 02, 2010 7:40 pm

Becca the thing you must realise is that with lake tanganyika the fish have evolved over 2 million years, lake victoria is much younger and her cichlids are much closely related to the riverine ancestors. It is in a state of explosive radiation where the fish are splitting off filling all the niches. This means most of the fish are still closely related and will hybridise more readily.

As stated a perch is naturally found in tanganyika and the fish have evolved with it present. With an introduced species the native fish do not realise it is a threat. The survivors will have learnt to evade the nile perch but these things take time.

Another point is that there is a natural process of hybridisation (more so for same species - separate location points but are these really hybrids?) that occurs naturally, less so in lake tanganyika as it is so old and may have already gone through such a process. My opinion is this process is on going but may take decades for any visible signs in a particular fish.

Since the collapse of nile perch stocks and 60% of fishery's in Uganda have closed down some species have been making a come back but they have changed/adapted to their changing environment. The scientist have known this for some time and given up maintaining victorians in captivity because future restocking is impossible - Chester zoo are re-evaluating whether to carry on keeping the 2 species they have.

Some of the species to have been kept in captivity may now look like a totally different fish to its wild counterpart. The speed of this adaptation was not heard of in fish before.

You can not make comparisons between the two, the problem with a growing population around the shore is found on all lakes and results in deforestation,pollution and so on with out perch present.
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Re: Lake Victoria

Postby Becca » Wed Mar 03, 2010 9:56 am

alanastar wrote:
Another point is that there is a natural process of hybridisation (more so for same species - separate location points but are these really hybrids?) that occurs naturally, less so in lake tanganyika as it is so old and may have already gone through such a process. My opinion is this process is on going but may take decades for any visible signs in a particular fish.



I always thought of this as speciation, rather than hybridisation... but i suppose it makes sense that Tanganyika being much much older that the speciation process is complete- whre as the fish in Victoria are still in its infancy (to an extent).

I personally wouldnt compare the Vics situation with Frontosa, and not sure how much damage industrial runoff would cause to such a deep water fish (obviously collossal amonts wiould take its toll) but then im not an expert on the matter.

None the less, a very imfortative post Paul :text-thankyoublue:
Becca
 

Re: Lake Victoria

Postby Paul B » Wed Mar 03, 2010 6:51 pm

I hope it came across ok, i am not that good at putting things across. :handgestures-thumbup:
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Re: Lake Victoria

Postby mbunasam » Wed Mar 03, 2010 8:40 pm

Becca wrote:None the less, a very imfortative post Paul :text-thankyoublue:



:text-thankyoublue:


:text-lol:
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Re: Lake Victoria

Postby cichlid crazy » Sat Mar 06, 2010 7:06 pm

:text-goodpost: :text-goodpost: :text-goodpost:
cichlid crazy
 

Re: Lake Victoria

Postby Becca » Thu Mar 11, 2010 10:24 am

Becca
 


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