If I built a concrete pool, would it ever contain fish?

Question

Imagine that I built a concrete-walled pool the size of a football field and filled it with fresh water - obtained from another lake but free of bacteria, plantlife, eggs, etc. Would it ever, over time, become a life-filled "lake" - with fish, amphibians, algae, plants and other water-dwellers? If yes, how? What would the chain of events look like? I'm assume plant-life would get there first but how would it develop an established eco-system? Please re-tag as appropriate as I am new to this SE site.

Answer 1

The short answer is yes, it would eventually turn into a full fledged lake with an abundance of life! It would take a very long time and would depend on a multitude of factors. You are very right that plant life will likely find the water first. Just like algae can start to grow in a pool that is left unattended, algae spores carried by wind would make it to the football-field sized water body first and take over. As the algae dies and organisms fall into the pool and cannot get out, a layer of sediment will form on the bottom of the pool that will be rich in nutrients that aquatic plats could take root in (if the seeds are dropped from another species like a duck or deer). The next likely colonizer of this new body of water would be macro invertebrates like flies and mosquitoes. They would lay their eggs in the predator free environment and have huge booms in population around this body of water. The larval states of many macro invertebrates act as decomposes and would help break down the build up of dead material at the bottom of the pool. These insects would likely draw in two other classes of organisms if the water alone has not already which would be frogs and aquatic birds (ducks). The number one way for fish to make it into a new isolated body of water is on the feet of birds as they move from lake to lake. Fish eggs are very sticky and will stick to the bottom of the feet of birds. This is an extremely abridged version of events and there are many outcomes were this concrete pool would just fill with sediment over time. Many factors about the way you build the pool would determine how quickly the events above take place. How deep the pool is, how even the bottom is, the amount of trees around the pool (if any), how much annual rainfall is there, is it a smooth or rough concrete, and if it freezes in the location it is built would all play a role in what life can survive and thrive in the pool. If you put water in any location, life will find it; if it is given time (hundreds and thousands of years) it will establish a stale ecosystem.