The Garden Pond Blog

Oxygen measurements from the Abingdon ponds today are interesting [Click on the graph to see a clearer version].

They vary from almost completely de-oxygenated – and these are mostly ponds with big accumulation’s of leaves in quite deep ponds – to supersaturated with oxygen.

They show just how much ponds differ one from another, and how inappropriate one-size-fits-all management advice is likely to be.

At this time of year you would expect oxygen levels to be generally fairly high: and the supersaturated ponds are mainly those with abundant growths of plants.

Interestingly those abundant growths can be ‘nice’ mosses, as in Jeremy’s Old pond, or caused by thick (and unwanted!) growths of filamentous algae, as in Liz’s Pond.

So should we pull out leaves? Well, not necessarily – in my pond there are plenty of fallen leaves – which are good habitat – but the shallow water prevents a thick layer of oxygen accumulating rotting organic matter building up.

See the latest comment where Paula asks:

‘What’s the best way to enlarge my pond without disturbing it? I thought to make two ponds with a bog area between the two? Any other ideas?‘

Well, actually I don’t have a better suggestion and this is pretty much exactly what I’d do too.

Indeed, unless the pond is dug into a natural substrate, like clay, it’s probably the only practical way of extending the water area in a garden.

The bog area would be good – though not essential, as you don’t need a physical water connection between the ponds for them to work as a unit. Plenty of animals and plants using the ponds will be able to move between them without a wetland connection. One thing to be careful of would be to make sure the bog garden wasn’t a source of nutrients – make it with very low nutrient substrate (and avoid using peat aka destroyed wetland).

My only other thought is why stop at two!

This headline in The Times the other day made me sit up:

Angling Trust calls for cull of otters eating too much fish

Apart from the slightly infelicitous use of English (shouldn’t that be too many fish?), I can’t really believe anglers want to dispatch otters wholesale.

My experience of anglers is that they are mostly harmless folk who simply love fish. If there is a point of criticism its that maybe they sometimes love them just a bit too much.

And it’s understandable, I suppose, if you’ve spent a lot of money getting a good lake full of fish ready for people to catch, to be upset when an otter comes along and grabs your prize (and beloeved) specimens.

But I can’t help thinking that the headline probably wasn’t quite what the Angling Trust really meant to say. The Angling Trust is a respectable organisation that campaigns for anglers and does much good helping to protect rivers from pollution.

The article was meant to publicise their lobbying plans for 2010 – a worthy document but, like all such documents (our own at Pond Conservation included), unlikely to be your first choice for a bedtime read, unless you were trying to overcome a really long-term problem with insomnia. Maybe the headline was just a way of getting attention?

I checked the report – it’s online here – and the nearest it gets to the alarmist (and alarming) headline is to say that the Angling Trust will  ‘Lobby the Environment Agency for more funds to……..support the cost of fencing and other deterrents at still water fisheries to keep out otters.’

Sounds OK to me, and no mention of a cull – which is good news.

Here are the lastest oxygen levels in my pond and, just as important, in our neighbours Sally’s.

Sally’s pond is the green line: I began measurements there part way through the freeze, just before snow covered all the ponds.

Click the graph for a better quality image.

In Sally’s pond oxygen is always much lower. This has been really important to see because at times I’ve found it hard to believe quite how high the oxygen levels have been in my ponds. Sally’s pond has been an important reality check.

Sally’s pond probably has lower oxygen levels because the pond is quite deep, and has more organic matter using up oxygen.

In both my ponds you can see the clear effect of the snow – levels were high under the ice, especially in the old pond, but dropped fast once snow covered the ponds.

Oxygen levels bounced back quickly once the snow melted. The ‘bounce’ is highest in the old pond (the red and purple lines) and a little lower in the new pond – the blue line – which has fewer plants under the water.

Sally’s pond hardly changed during the cold weather – a slight increase as the snow melted, but I think this pond will always be quite low.

With the recent icing over (with no snow) oxygen levels in my ponds have risen again – often my old pond is off the scale as my dissolved oxygen meter only goes up to 20, and its often been higher than that in the latest freeze.

I still don’t know exactly why values are so high but I think the dense moss growth, producing oxygen under the water, and the shallow water are an important part of it.

Great Crested Newts get a lot of bad press.

The stock newspaper story these days about these beautiful animals is ‘newts get in the way of my school/hospital/grandmothers funeral’ (you can add your own deserving cause here which is stopped or disrupted, at great cost, by the animals presence).

Just search the sceptical press for the word ‘newt’ and you will see what I mean (see here and here). And I sometimes feel they do have a bit of a point – for £60,000 we could build 100 new high quality, clean and unpolluted in the Million Ponds Project. And a million pounds – well, that’s a lot of new ponds.

So it was good to see a bit of sympathetic (if sad) coverage of crested newts getting into a local paper following the report here of Sally’s dead Great Crested Newts in her Shropshire garden.

This short paean to newts is from the Shropshire Star.

A dirty polluting pipe flowing into a new pond?

No, its a bat tunnel at water level leading to a pond-side summer roost, the breeze block construction below.

Pond-side summer bat roost

This is part of an innovative pond creation project taking place in Suffolk which I visited yesterday.

Spring is springing already in the south-west of England and south-west Wales as the first frog spawn appears.

Keep up to date with how things are progressing with Nature’s Calendar run by the Woodland Trust and the Centre for Ecology and Hydrology.

Thanks to everyone who’s submitting Big Pond Thaw forms at the moment.

I’d been expecting a lull in returns, but as they’re still coming in pretty frequently we will hold on a bit longer before reporting back.

The Big Pond Dip 2009 results will be following soon after that – but as you can probably imagine things have been hectic and our timetable for reporting back has been a bit disrupted.

The authoritative BES policy website picked up the ponds report last week.

And the BES also noted another issue that we were keen to link to the generally poor quality of ponds.

And that is the fact that 75% of rivers and streams in England and Wales will fail new standards which define the range of plants, fish, invertebrates and algae you should find in clean and unpolluted rivers.

The Environment Agency says:

“Using the new classification system [for a thing called the Water Framework Directive], results for assessed rivers in England and Wales show that for overall ecological classification 26% of rivers are good or better, 60% are moderate, 12% are poor and 2% are bad.”

It’s worth noting that the new system is a five point scale with water bodies assessed as: bad, poor, moderate, good or high. In theory, all waters should be at ‘good’ or ‘high’ status. Most are not and, at present, virtually no rivers in England and Wales are ‘high’ status.

More information on the Environment Agency website.

Alongside Jeremy Cooke’s report we also filmed a short piece on the pollution problems facing ponds, and how we can make a real difference with new pond creation.

View it here.

For more information look at Pond Conservation’s Million Ponds Project.