Garden pond surveys

With Win Fairchild of West Chester University (Philadelphia) – who’s visiting Pond Conservation – I’ve started some detailed surveys of garden ponds in Abingdon.

These surveys will give us the first indication of exactly what’s living in garden ponds, what affects the variety of wildlife they contain, and how they compare to ponds in the rest of the landscape.

I’ll keep you posted as to how the results are going.

This is the first survey we did: Sally’s pond, just across the road from us.

It’s just about the cushiest survey work I’ve ever done! And complete with generous supplies of tea and biscuits!

Reply to Ruth: the sour milk smelling pond

All's not well with Ruth's new pond

Ruth has asked whether I could diagnose the source of a sour milk smell in her new pond. She wrote a little while ago:

“Help please!
My new pond smells of sour milk!
It was made for me about 2 months ago.
It’s filled with rain water. It is 2′ deep at the centre and about 2×1.5m surface – it has a logpile next to it. It has lots of wiggly things – some kind of larvae I guess – water now looks quite black. I added some snails and weed from a local pond 2 wks ago.”

So……what’s the answer?

First – I don’t know why its smelling of sour milk, but I would guess that somewhere along the line water quality is a problem.

The rain water is a good start but there’s no reason I can think of why that should go black or smell unless something else had been added to make that happen. A black colour is often a sign of overloading with organic matter.

I wonder whether the emergent plants have been planted in a compost that might be adding either organic matter or nutrients to the pond. It’s also possible that the plants you added (nothing wrong with that) could have died and now be rotting down.

My advice would be to start again: its very difficult to get pollutants out of the water once they’re in – and on the small scale of a pond its perfectly feasible to take the water out, take out anything thats been added to the pond that might be adding pollutants and start again with water that you know for sure is clean.

This is what I did with my second pond when I found it had a conductivity of 300 – nearly 3x what it should have been. I just knew this was a bad start so I chucked the water and refilled it with rainwater.

It may seem like a lot of trouble but clean water, free from added pollutants is so fundamental that it’s worth the effort.

The larvae are probably mosquitos, which are usually amongst the first colonists of new ponds. As other animals colonise they’ll be eaten – mosquitos are usually a very small part of the life in a garden pond, if they occur at all (we have none).

What’s in the pond now?

Broad Bodied Chaser and (probably) Southern Hawker larvae from the pond today

Nobody has every carefully studied the changing life of a garden pond year round.

So whatever’s in the pond now is going to be interesting.

Today I found:

Dozens of Large Red Damselfly larvae and a surprising number of Broad-bodies Chaser dragonfly larvae, too – big and small. And also the larva of a hawker dragonfly – there are only one or two of these in the pond. This is probably a southern hawker.

There were hundreds of tiny Whirlpool Ram’s-horn snails, but I couldn’t find any of my usual Dwarf Pond Snails today.

Pond Olive mayflies are still numerous but not in the huge abundance I have sometimes seen them.

I’ve got quite a few backswimmers – all seem to be spotted backswimmers – but no lesser water boatmen at all.

I’ve seen five different kinds of water beetles today, which is actually not such a great variety: 10 to 15 species would be a more normal haul. But there are lots of developing larvae which will probably become adults in the spring.

I was a little surprised to see no caddis flies: it may be that there are eggs still to hatch.

There were a few pond skaters, though with the lush growths of mosses there is less open water for them than there has been.

Today: one I my little frogs in the tray with a Broad Bodied Chaser larva (a terrible photo, I know, but I liked the difference in size)

And frogs: I’ve got all stages still. Tadpoles with no legs, tadpoles with back legs, froglets with four legs that have not yet absorbed their tails, baby frogs recently emerged and the young of this year now growing up.

Today’s Big Pond Dip score is 42, 10 down on earlier in the year – the difference was becuase I didn’t find caddis flies.