Pond teeming with lifeafter holiday

I CAME back from a short holiday to find the pond on the patio in need of attention.

The weather had been warm and breezy while I was away. The warmth had caused a heavy growth of green algae and the breezes had deposited a lot of dead leaves in the water.

It’s a very small pond – not much bigger than a bath tub – so the easiest way to clean it is to get down on your knees and do it by hand. This causes consternation among the pond’s inhabitants – three goldfish, two shubunkins and the frog that comes to cool off in hot weather – but they get over it fairly rapidly.

Some of the leaves were floating on the surface and others had sunk to the bottom where they were threatening to rot. Rotting leaves can pollute a small pond quite quickly.

Most of them I identified as ivy leaves. Ivy is an evergreen, perennial, woody plant and, like all trees and other plants of this type it sheds leaves all year round, rather than concentrating on the autumn as deciduous plants do. It produces two

types of leaf – the familiar three-lobed version is the juvenile leaf. The adult leaf is different, paler in colour and a narrow oval or shield shape. Most, though not all, the leaves in the pond were adult leaves.

I was scraping clumps of algae and dead leaves off the bottom of the pond and piling them up on the patio when I noticed movement in them. There were more things living down there than I had realised. I moved the piles of detritus to the water’s edge to give this unexpected wildlife a chance to wriggle back to safety and sat down to watch.

I was surprised. The pond is less than 18 months old. It’s filled with treated tap water. The fish came from very sterile looking tanks in a pet shop. The oxygenating plants were bought in plastic containers from a garden centre. The garden is on a dry esker ridge with no natural open water for many hundreds of metres in any direction. And yet it had been colonised by so many living things.

There were little ‘worms’ as thin as a hair and reddish in colour. These were bloodworms, the larvae of certain types of midge. It was easy to understand how a midge could have flown in on the wind and laid its eggs in the pond. Shiny black water beetles the size of a little finger nail seemed more mysterious but although beetles look like the most un-aerodynamic creatures on earth most of them, including water beetles, carry concealed wings and can fly in search of new territory.

What really took me aback were quite large numbers of asellus aquaticus. This creature has a variety of English names including water slater and water hog louse. It’s not an insect, it’s a crustacean that is, in fact, closely related to the land-based wood louse or slater. And there’s no way crustaceans can fly.

The pond’s too small to attract water birds so they couldn’t have been the vectors that introduced these strange creatures. I wondered if asellus eggs could have come in stuck to one of the water plants I had introduced. Then something stirred in my memory. I checked on the internet and I was right. The female water slater does not lay eggs on water plants. She carries them around in a brood pouch on her body like an aquatic kangaroo.

Did they come down in the rain? It’s unlikely but not totally impossible. Even small frogs have been known to drop from the clouds in thunder showers. I have no other explanation.

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