Where does the aquatic life come from?

I have just watched a short documentary about the raising of a steam navvy from the water known as the Blue Lagoon, which apparently is the quarry hole of Arlesey Quarry in Bedfordshire. HERE is a link to the location of the Blue Lagoon on a map.

Now, clearly this quarry hole is no different to many others dotted around the country in that it has been abandoned and has filled with rainwater/run-off. I can even understand that before too long, wildlife will be attracted to the area - however, what I don't get is how fish and fresh water mussels have gotten into this quarry hole?

It is not connected to any rivers (at least, not that can be seen on the maps), and yet there clearly is fish in this quarry pool - they were shown swimming around the divers who were part of the lifting operation to lift the steam navvy from the water - so how in the name of the wee man did they get into this particular body of water?

 

The carrier of life has always been the Bird carrying eggs on it's legs and seeds in it's stomach

 

Well I never - I wouldn't have thought fish eggs would survive out of the water. Nature really is clever!

 

Not really, FC, it evolved us!!