FYI

[bfishn]

1 hour ago, fishinwrench said:

Good stuff.  Thanks

You're welcome! Now I have some Qs for you... Would a surface film of boat fuel/exhaust inhibit or prevent the normal exchange of atmospheric oxygen? How long would it persist? Would the effect be more prevalent near a marina given the seemingly unavoidable leakage/spillage?

[fishinwrench]

3 hours ago, bfishn said:

You're welcome! Now I have some Qs for you... Would a surface film of boat fuel/exhaust inhibit or prevent the normal exchange of atmospheric oxygen? How long would it persist? Would the effect be more prevalent near a marina given the seemingly unavoidable leakage/spillage?

Absolutely would inhibit the exchange, but the slick would have to be HUGE to cause a measurable effect.  In essence it wouldn't be any different than a floating dock, or an air mattress floating on the surface.  

An oil slick in calm water will actually defy gravity and climb up anything floating (sticks, logs, rocks, or anything dry it can come into contact with) like a wick in a kerosene lamp.  Not sure how that works but I do it in my test tank all the time.  I stand some 2x4's in my test tank and the next day there will be oil and crud 6" above the water line on those boards. That's how I clean it out.   And no matter how nasty that water gets the tadpoles are always just fine.  

Any idea what the DO requirements are for tadpoles?

[bfishn]

5 hours ago, fishinwrench said:

... And no matter how nasty that water gets the tadpoles are always just fine.  

Any idea what the DO requirements are for tadpoles?

Good grief man, get those poor pollies out of that nastyazz test tank and into a proper puddle. We need all the frogs we can get in the war on carp!

Nah, I was fishing the day the teacher talked about tadpoles. You'll have to figure that one out on your own. 🙂

[vernon]

11 hours ago, bfishn said:

I borrowed the chart below from an aquarium site because it has a Fahrenheit temperature scale. Whoever made it mistakenly labeled the oxygen scale as %, it should be parts per million (ppm). Otherwise accurate.
 

As previously mentioned, DO levels are directly related to water temperature. Saturation is the most DO water can contain under natural conditions at atmospheric pressure and the indicated temperature. I posted this to illustrate what a narrow range there can be between DO saturation and lethal limits. For instance, at 86 degrees, the maximum DO is ~7.6 ppm, just 3.6 parts per million above lethality for most fish. At 50-59 degrees (common thermocline temps), the spread doubles to ~6-7 ppm.

 
Considering the dynamic, ever-changing nature of DO, it’s pretty amazing that we have as few DO-related fish kills as we do. Surface aeration replenishes DO, Biological Oxygen Demand depletes it. Then you have the daily phytoplankton cycle that replenishes DO in the day and depletes it at night. Inflows can be beneficial or detrimental simply depending on the specific conditions at that particular time and place.

I’ll make no claims as to what I think a fish knows or thinks, or whether it’s smart enough to sense potentially lethal conditions and relocate accordingly. In the case of walleye that are conditioned to summer thermocline temperatures, I know it wouldn’t do them much good to leave that zone because DO was dropping and move the mere ~30’ to the surface where it’s better, because the sudden change from ~55 degrees to ~85 would croak them in a fairly short time. Maybe that’s what happened.

Now I remember why I hated biology.

And chemistry.

And math.

In fact, that was the stuff that made having to read Homer's The Odyssey and other unintelligible crap like Steppenwolf and Beowulf seem attractive by comparison!

[tjm]

Quote

Oxygen is produced during photosynthesis and consumed during respiration and decomposition. Because it requires light, photosynthesis occurs only during daylight hours. Respiration and decomposition, on the other hand, occur 24 hours a day. This difference alone can account for large daily variations in DO concentrations. During the night, when photosynthesis cannot counterbalance the loss of oxygen through respiration and decomposition, DO concentration may steadily decline. It is lowest just before dawn, when photosynthesis resumes.   http://www.lakeaccess.org/russ/oxygen.htm

As  I understand it algae/phytoplankton  make much/most of the available DO when the sun shines, but on cloudy days and at night consume more oxygen than they produce. Any algae die off hurts DO in two ways- lack of production and greater use by decomposition. Wind is also a means of adding DO and of mixing it throughout the water. Interesting stuff to read, but too complicated for me to translate and report.

list of O2 required for some fish

   Lowest Oxygen Level for Life

Lake Trout 8.3 ppm
Brown Trout 7.8 ppm
Perch and Walleye 6.4 pmm
Large and Smallmouth Bass 5.1 ppm
Sunfish, Crappie 4.7 ppm
Bullheads, Carp, Suckers 4.0 ppm

Might note that many science papers will list mg/L - metric measure that is ppm. 

 

Behavior when in low DO

Quote

After encountering an area of low oxygen content, fish often start to swim rapidly and to zig-zag all over the place. This is probably an adaptive response to escape the danger zone. However, if hypoxic conditions persist, most fish will greatly curtail their general activity. The advantage of inactivity in the face of hypoxia is simple: less muscular work means less need for oxygen. As part of his doctoral research at Laval University in Quebec City, Fred Whoriskey observed sticklebacks breeding in tide pools along the St-Lawrence Estuary, and he reported that during periods when

dissolved oxygen levels dropped, the fish became very sluggish, even failing to show normal fright responses...

http://howfishbehave.ca/pdf/oxygen.pdf

Becoming sluggish to (an instinctive behavior) conserve oxygen  might explain  why fish get "trapped" in a pocket of low DO, the fish probably doesn't think "this is just a pocket of  bad air, I'll swim 30 feet to a better place"; I have serious doubts that fish even think at all, at all.

 

 

 

[Johnsfolly]

43 minutes ago, tjm said:

As  I understand it algae/phytoplankton  make much/most of the available DO when the sun shines, but on cloudy days and at night consume more oxygen than they produce. Any algae die off hurts DO in two ways- lack of production and greater use by decomposition. Wind is also a means of adding DO and of mixing it throughout the water. Interesting stuff to read, but too complicated for me to translate and report.

TJM - thanks for posting this. I didn't go into algal/plant effects on dissolved oxygen. The reason that runoff containing high amount of nutrients/fertilizers like phosphorus and nitrogen affects the dissolved oxygen levels is mainly because of the affect on algae and plant biomass. With the increase nutrient loading into the water the algae will reproduce rapidly and "bloom". In a heavy algal bloom a few things can happen.

1) populations of toxin producing algae/blue-green algae (cyanobacteria) can dominate the system and cause detrimental effects like those during a red tide (dinoflagellates cause these).

2) and as you mentioned the increase algal and plant biomass can shade out other plants and algae which creates a large die off of the algae and plants being shaded leading to decomposition and a drop in DO.

[vernon]

Man, my head hurts.

I could use a good comic book about now.

Or maybe the back of an old baseball card.

MAD magazine might work too...........

[rogerdodger]

I doubt if the eagle rock area has advanced to the higher septic standards of stone and Branson areas....heavy rain causing excess runoff of “nutrients “ which dumped into already hot lake created a dead zone.... in that area I can smell banks that smell of sh?? When was the last time septic systems were ever tested.... only when they’re put up for sale but no one wants to admit their systems are causing algae blooms and fish kills.

[dan hufferd]

Interesting thread, I throw a spoon at walleye a lot, many times I feel like the walleye feed under the spots.

It happens so frequently, that when I see feeding spots on the graph, I try to get a spoon under them, which can be tough unless you cast beyond them.

So maybe the 2 species tend to hang together.

And I also gave up a way to pattern them, there you go. 

I like the trouble shooting aspect of most of this thread.

Thanks