A normal scene, some small fish in a ditch, but if we look more 'up close ..
A half 'of 2010, some Italian authors published an article in the journal Biological Invasions, which makes no small talk and conservationists around the world.
describe the environment of a ditch in the province of Livorno with its hot springs offers a rather unusual (but not unique, as we shall see) and draw up a checklist of species. A checklist
quite bizarre, with few native species (eel, tench, rutile) and a para-native species (carp) followed by a long list of introduced species that is done via via more 'exotic read on.
Livio, and that 'much more' me sensitive to the cichlids, publish a guide already 'in October, but I, on the contrary they are very slow, I was unable to complete the article before you today.
fish appear very strange in the ditch, are Tilapia!
Mystery and 'easily explained when you go to watch the temperature of the water of this ditch, with an average of 36 degrees, and' comparable to a good natural aquarium. The fact
species are characteristic of tropical systems with fewer than 3 members of the family dei ciclidi (tilapie) e 1 appartenente alla famiglia dei loricaridi (pesci gatto corazzati). Le comunita' ittiche alloctone sono strutturate, si trovano cioe' popolazioni con individui di tutte le dimensioni, e si assiste alla nascita di interazioni nuove tra specie alloctone che vanno a formare delle comunita' complete.
Tra parentesi gli autori dell'articolo sono stati anche aspramente criticati per aver suggerito di testare metodi di controllo su questa comunita'. Come se la normalita' fosse avere pesci tropicali e non salvaguardare specie endemiche come Melanopsis etrusca anch'essa presente nel fosso..
Beh fino a qui si potrebbe dire che e' un caso straordinario..una cosa che succede per una combinazione fortuita di fattori ambientali ed immissioni dell'uomo..
D'altra parte anche gli autori dell'articolo constatano che dove calano le temperature dell'acqua le popolazioni sono meno strutturate e meno dense. Pero'...c'e' sempre un pero'....
Pero' l'italia e' terra notorialmente soggetta ad attivita' vulcanica e ci sono zone termali da nord a sud con altrettante acque piu' o meno calde. Vuoi che non esista altro?
Se tanto mi da' tanto basta mettere il retino in acqua calda e..
Detto fatto, basta spostarsi di qualche centinaio di metri e si scopre che il lago termale che alimenta il fosso alimenta anche due laghetti di cui uno dedicato alla pesca sports. Ponds, which, needless to say, they are also home to the same species.
And if we go a bit 'over? Well I do not need to go away. This summer in Viterbo and 'was discovered a whole community' of "Guppy" (poeciliidae, in reality, 'but probably endler vabbe') in another ditch spa where the temperature never drops below 20 degrees. Again aquarium probable introduction and acclimatization thanks to the peculiar environmental conditions.
Another striking example, also published in 2010 and 'that of tilapia in the Padua area studied by White and Turin, another channel with thermal waters, another population of Oreochromis ..
In Italy, as already 'mentioned, there are many sources thermal as well as many micro-climates with details. Warm waters all year round can be found not only in volcanic areas, but also behind the house as a result of industrial cooling process, such as power plants.
The endler of Viterbo
Even in this case returns to the leitmotif of the new settlements. Where there are environmental conditions that allow survival and reproduction and 'very likely a new species is acclimated and dig a niche, more' or less. And, as already 'mentioned, and' hard to curb the number of introductions of species or type ..
Well after all, you say, however, are exceptional, restricted areas ..
Well, we're really sure? Well apparently the tilapia, which generally does not tolerate water more 'cold of 17 degrees are by no means limited to the spa but I have become widespread in many other waters with temperatures well over' hard, it seems that they can safely spend winters in the waters at 9-10 degrees ..
Here we explain the numerous captures nell'areale Po where tilapia (not further defined, probably Oreochromis ) forms large populations and poorly documented except in the occasional catch of a fisherman.
The "piranhas" caught Po
also made news in August 2009 fishing for a "piranha" in the Summer Po newspaper, notoriously thirsty for news during the summer, we're rushing headlong out to make a minimum of verification.
Any ichthyologist, or even an aquarium would have seen the teeth edges and the size and would have correctly identified the fish for a "pacu", common name that is used to indicate a "pirnha omnivore" (including several species under one umbrella).
So do not worry for swimmers (and which) of the Po, but perhaps a little 'fear of the ecosystem (already' martyred) and most of the great river 'in general on the peninsula. It is because 'in this case we are dealing with a fish convention that does not tolerate low temperatures ..
The pacu caught by Max in Veneto
About a year later, in October 2010, another fisherman caught a pacu, an area well with water most of the Veneto 'cold that which can 'be the Po in August ...
Resistance? One specimen in the end of life (though he ate and fought with force)? A fish released the day before from an aquarium?
not be alarmed at this stage, to better monitor the situation and keep the environment and monitored the spread of new species before making claims easy.
course and 'that so many certainties, on closer inspection, are not so' certain and we should think not once but many times before risking to download the contents of your aquarium in the river ..
Bibliography:
White and Turin 2010
Piazzini et al. 2010
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