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.
April 7, 2010 at 2:25 pm |
Where did you take your oxygen samples Jeremy – was it at the surface, the deepest point or in some other way?
April 7, 2010 at 5:21 pm |
Hi Tristan
Most of the oxygen measurements I’ve described so far (for example the under-ice measurements) have been near the surface – say the top 5 cm of water. Though it’s worth saying that in the shallow ponds this is one-fifth of the total depth!
We’ve also done measurements at top, middle and bottom which, as you’d expect, usually show a drop from top to bottom.
Jeremy