temps versus DO

[nymphingmaniac]

Some may find this surprising about DO versus stream temps. The biologists out there won't be surprised. I constructed a graph of temps versus DO on the upper J.
As you can see DO actually rises as temperatures are rising. The reason for this is the the uptick in temps is associated with the intensity of the sun on the river (correlates with time of day). The sun activate photosynthesis in the algae (and plants) in the stream bed, leading to a burst in release in O2. Once the temps peak and get high, then the amount of DO drops, probably because the output from microbes is over taken be the reduced physical properties of water to hold O2 and the activity of O2 consuming microbes.

This shows the complexity of a biological ecosystem and predictions based solely on the contributions of one element (temp vs DO) can be imprecise.
There are even some correlations with pH changes during the winter months with sunlight, DO and pH that are even more wild.

 

[k-bob]

Interesting example of how oxygen may not move w water temp as would usually be expected.... shame we can't have workable oxygen gauges in stead of thermometers.... love to have one on a tumbling mountain stream.

 

[Zak]

I agree because gradient of a stream would certainly impact the amount of dissolved O2 in the water at a certain temp. A tumbling stream will have more 02 at 70 degrees than a slow oozing stream. How much, I'm not sure.

 

[attackone]

O2 being the most important of the 2, if there was a way to check the O2 level in stream would that make water temps irrelevant?

 

[afishinado]

attackone wrote:
O2 being the most important of the 2, if there was a way to check the O2 level in stream would that make water temps irrelevant?

One is not more important than another, the two are linked and have an inverse relationship > the higher the water temp, the lower the O2 level

Here is a great article about dissolved oxygen in water >

https://www.fondriest.com/environmental-measurements/parameters/water-quality/dissolved-oxygen/

 

[k-bob]

bummer, but measuring dissolved oxygen in stream doesn't look that easy versus zapping stream w infrared thermometer (video) ... and why is there no rhodo behind this man?

https://www.youtube.com/watch?v=9Jk0AmmuLSY

probably higher d.o. level needed for safe catch and release fishing versus a more general fish suitability level?

my possibly screwed up take is that if we stop fishing at about 65F, that would tend to be about 9.4-9.5 mg/l d.o. in the water, while the dissolved oxygen might be about 10 mgl/l in the 59F water we dont worry about.

 

[salmonoid]

Temperature is the biggest factor for what DO water can hold, but as has been noted, other factors can put a "wiggle" in the carrying capacity of different waters, temperature being equal.

There are digital meters that will measure DO - no experience with them, a little pricey for me to pick up on a whim.

A question that I have regarding DO is what mechanism do the fish have to detect a low DO condition? There must be some sort of biological feedback mechanism in their bodies that allows them to sense DO content. In our bodies, lack of O2 will cause us to have headaches, fatigue, blackout, etc. In something with the brain the size of a pea, how does it know that it's time to hunker down and conserve energy (and use less oxygen), or use the last remaining energy to move to a spot with higher DO content?

 

[troutbert]

attackone wrote:
O2 being the most important of the 2, if there was a way to check the O2 level in stream would that make water temps irrelevant?

I don't think that it would.

O2 level is of course important for trout.

But I'm pretty sure that the warm temperatures alone has negative effects on trout metabolism.

Some animals have metabolisms suited for cooler temperatures than others. It's probably related to enzyme systems, the functioning of the nervous system, etc.

 

[Tigereye]

@Salmonoid.... It's probably just comfort level and instinct. If its getting difficult for the fish to breath due to low O2 levels, he is going to move to a more condusive comfortable environment.

Think of sitting down at a campfire, suddenly the wind shifts and you get a lung full of smoke. You get up and move more as an involuntary reaction than conscious thought.

 

[Mike]

Daytime DO in streams is usually at the saturation point for a given temp and atmospheric pressure. When overcast, the DO may be below saturation by 0.1-0.2 mg/l. No big deal. When there is "some" organic enrichment, such as in farm country, it may be off by 1 mg/l, especially if it is overcast and it is a low gradient stream, but this is not very common. Usually, streams are saturated. Tumbling streams are also saturated, but not supersaturated since the aggitation blows off any excess gas in a hurry. Big pools in creeks usually have the same temp and DO as the surface unless there is a groundwater entry point along or within a pool. Even in the Delaware Estuary in Phila the Temp and DO only vary by about 0.1 deg C and o.1 mg/l from surface to bottom in around 40 ft of water.

 

[k-bob]

thanks for that info mike. sounds like water temp, easy to measure, is a good enough proxy for dissolved oxygen...

 

[Zak]

Dang that was interesting Mike. I didn't know that streams are basically always at saturation relative you atmospheric conditions. That sheds a new light on things for me. Thanks.

 

[Tigereye]

https://www.usgs.gov/special-topic/water-science-school/science/dissolved-oxygen-and-water?qt-science_center_objects=0#qt-science_center_objects

 

[PAgeologist]

You can get a meter for measuring DO. They are pricey though, not very portable, and can be a pain to maintain.