Pond Boss Forums INTRO Questions & Observations Weekly Observations

The slight increase in DO was maybe, maybe not due to extra oxygen production at the bottom. Here are some possibilities.
1. Meter error, variance, or calibration error.
2. Increase of inflow, seepage of ground water that contained some dissolved oxygen and do water layer remained near the bottom.
3. If your water clarity is adequate to allow 1% of surface sunlight to reach the bottom and there are either submerged plants (rooted or attached algae) on the bottom they could be making some oxygen and the oxygen is accumulating at the near bottom, sediment water interface so hopefully the removal of snow did help increase DO where the 'plant' density was greatest at the bottom area or aka benthic zone.

I went back to the weekly data page and saw that the water clarity at freeze up was around 6ft. This means that without ice cover green plant photosynthesis can occur at 1.7 to 3 times the Secchi disk reading; in this case 10.2 to 18ft deep depending on the water characteristics. If we assume that ice cover reduces light penetration compared to ice free water, the amount of light that penetrates through the ice and into the water is probably not very much compared to ice free conditions. Thus my WAG estimate is day light penetration through 12"-15" of ice would at a maximum be 1 to 1.4 times the Secchi disk reading. We do not have a secchi disk reading for the current conditions of Dwight's pond. Dwight if you or Stick cut an ice hole big enough to drop a Secchi disk, check the measurement.

Bill, that was priceless!!!

Recent clarity reading was 60 inches. Ice is 18.5". So the calculations on those numbers would be even more restrictive of light penetration near the bottom.

With 60" (5ft) of Secchi water clarity, I think 1% light penetration through 18" of clear ice on a sunny day would be in most all bottom areas of 7-8ft and less, maybe 9ft. Water convection currents could move water with higher DO to some deeper areas depending??? How deep was the bottom DO measured?

Bottom D.O. at 12 feet.

Winds steady 30 mph gusting to 39 out there this morning. Blowing snow hurts the face at those speeds.

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The fact that you were out there on a day like this says something about you.

The winds have no effect on me today 'cause I'm hiding inside!

Pretty comfortable toasty and fluffy for a crappy day. Should really clear up by April tho.

Not sure what that would be, crazy maybe.

Even though we have plenty of clear ice windows into the pond it has been tough getting even one day in a row with sunshine. I surmise that the lack of sunshine has some effect on the dropping D.O. numbers.

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Moving toward convergence. Plenty of DO.

Convergence means that the pond is acting normally. There are two convergences that occur each year, spring and fall.

Does convergence occur in southern ponds?

Yes convergence does occur in southern ponds but in far to many cases it is accompanied with low DO events.

O.K. What's convergence?

Convergence is where the D.O. and water temperatures cross or nearly cross each other on the graph.

In southern cases it would occur when water temps are either rising or falling and DOs are headed the other direction - usually associated with fall or spring turnover. Could be from a weather or rain event which is all to often a fish kill here.

Thank you gentlemen! I've never heard of that in any of my fisheries classes, texts, or even online. You learn something every day!

Yes I do Cecil - every day !

Its 5 degrees here in Southern Maryland this morning. I checked, its colder here than at Bremer pond. LOL.

The brackish water creeks around here are even frozen.

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Somebody down there is making a little oxygen.

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Notice that the DO increase appears to be getting mixed into even the deep layers. Maybe mixing is due to the underground water seepage that is entering the pond? With snow off the ice as seen in the 'Bremer Pond Weather' link, it is evidently allowing some 'below the ice' photosynthesis to occur and produce some DO.

Groundwater and deep sunlight will do the trick.

The circulator is churning away over there doing some mixing as well.

It is never just one thing.......

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