When I first installed my garden pond, it was an almost sterile environment. I put some soil in the bottom and filled it with rain water and aquatic plants.
The first wildlife to arrive were, of course, mosquito wrigglers, so I installed some small native fish (Pacific Blue Eyes) to take care of them. Goldfish would have been more "interesting", but they eat tadpoles too ... and I wanted to encourage frogs.
More insect life soon came - ones that swim in the water that I think are called daphnea; a water spider took up residence on the surface; and bees came to drink.
Then, two weeks later, I heard a strange noise at night ... like someone was using a hammer. I eventually tracked it down to the pond. My first frog - a male, striped marshfrog - was calling for a mate. He called on his ownsome for many weeks until, one night, I discovered him with a female. She was laying eggs and paddling like crazy to create a foam raft for them.
There were no predators in the pond so, before long, I had hundreds of growing tadpoles. I fed them with frozen lettuce and every night I watched as they developed their legs, then lost their tails and hopped out of the pond as fully formed frogs.
I have devoted a shady part of my small garden to frog-scaping. I only have to push aside some leaf litter nowadays to discover a marshfrog resting in the cool moistness among the ferns. They are part of a natural garden.
Then I noticed a red percher dragonfly dipping its tail into the pond. Before long, I had dragonfly larva. This development brought about a reduction of the tadpole population, but a balance seems to have emerged. A wonderful experience was coming out one morning to discover my first dragonfly larva had emerged from the pond and was coming out of its casing. It opened its wings, dried them in the morning sun and flew off. Magic.
I put a mesh fence around the pond to allow frogs in but keep cane toads out. Cane toads cannot jump or climb over it. Once, I accidentally knocked the fence open and a cane toad got into the pond. I removed it, but not before it had poisoned the water and killed my fish.
So, I waited for the water quality to improve before installing more fish. Naturally, there were heaps of mosquito wrigglers, which I removed every day with a plastic sieve. Then one day ... there were no wrigglers in the pond. And the next day. And the next. I thought that my fish must have laid eggs before dying and that these had now hatched. Every night I looked for these elusive fish by torchlight, but none was to be found. It's been a couple of years now and still no mossie wrigglers or fish. I can only deduce that the dragonfly larva population had reached "critical mass" and were eating all the wrigglers.
So, a kind of ecological balance has developed over time. It is its own little world.
As I sit by the pond, a bee lands on a lilypad. Tiny insects skate along the water surface. Tadpoles of different sizes dart through the water. Some have legs and are nearly ready to go out into the world. Others have just emerged from a raft of eggs. A dragonfly larva casing hangs from a branch, evidence of a new dragonfly having just emerged this morning. And to think it all started off as plain water.