Pond Boss Forums INTRO Questions & Observations Observations On Oxygen

I've been considering aeration systems to prevent this from happening.....hmmm.

Bruce, your pond must be big and deep enough to stratify and build up quite a hypolimnion. Did the bad October event correlate to a sudden fall turnover?

I'm surprised that the macrophytes crash so suddenly. Is that normal? How steep are your shorelines and what percentage of the pond contains macrophytes?

Your instincts are good. According to a National Geographic (IIRC!)program I saw, red tide is very toxic, and kills by poisoning. It's so toxic that humans can be sickened by eating fish and shellfish caught within the blooms. Really bad stuff! It's not impossible that red tide has a fresh water analog(s) that hasn't yet been observed. Toxins can be subtle, and hard to find if researchers don't know exactly what they are looking for.

Bobad,

Yep, my thoughts exactly. Would explain completely why aeration had no effect in Bruce's case.

p.s. my complete theory for Bruce's case...a sudden temperature change kicks off a chain reaction that eventually creates a toxic algae that then kills the fish.

Hey, guys...don't forget, my water is lightly saline. I measure as high as 6 ppt (seawater is 35 ppt). Maybe we're onto another etiology. You'd almost have to assume that oxygen is one factor though, because of the air gulping phenomenon.

Not necessarily...Tilapia gulp for air when dying in low temps. Gulping for air is an indication that the organs are shutting down, not that air is not present.

This article is a pretty good summary

Light reading

Steve, I definitely have a significant stratification of my big pond due to good depth, and the fact that I'm in a valley and don't get exposed to lots of wind energy. The October '03 event occurred during a time that you would expect fall turnover, but this was the one that the fish quit feeding for ten days before the die off. It seemed like the stress was anything but sudden. My shorelines are 4:1 slopes, so fairly steep, but I have macrophyte growth down to eight feet. Sago will grow deep and is very agressive, so I'd say that at least 50% of the pond has macrophytic growth. It becomes very difficult to fish because the sago is everywhere. Interestingly, you can't see it on the surface unless you get right on top of it because most of the biomass is in the water column.

Theo, I actually think I've got a full grip on your thesis. It makes me ponder something that's yet to cross my mind. Could the complete abscence of silt in my ponds reduce my ability to dampen the sunlight? It seems like the fact that my water is ultraclear minus the algae would mean that my sunlight penetration would oscillate much more wildly than someone with a little bit of suspended inorganics like silt. This could be promoting my algae bloom crash cycle considerably. Just another thought.

And BTW guys. How does toxic algae kill? Does it ruin a fish's ability to process oxygen, like rotenone? The first big kill I had, in June of 2002 had a very unique characteristic. It killed every single fish of every single size in my big pond. There were no survivors. Not even one fathead minnow or baby bluegill was spared. From what I've heard, O2 crashes usually leave a few survivors, and in my other "events" there have been some.

Guys :

Look at the sites referenced in my post above re red plankton bloom in an aquqculture pond which killed fish. Also the other sites talk about conditions for such events in fresh water. the site is from Texas but the fish farm was in North Cara. ewest

Bruce - I will get you some sample bottles and preservative during the fish stomach contents study. The next time you "have brown water" we can then identify the dominant species. I have also observed those similar chain of events in some fish kills of NW Ohio. The predominant submerged vegetation at the time was curly-leaf pondweed.

How is algae preserved, Bill? I so appreciate the offer to help. I pretty much know for a fact that the brown algae will rear it's ugly head yet this year, so it would be fascinating to see what I've got.

Bruce :

From my reading it seems that many of the red/brown algae change colors due to light conditions {turn red/brown in bright light} and may turn back to green. If that is true about your algae {plankton} if you catch some and keep it for long will you be able to ID it later. I bet if you have a microscope you can catch some and quickly determine at least if it is a flagellate like a euglena or if it has a red/brown eyespot. See pics. below or on prior posts. That might narrow the investigation. ewest

http://www.fcps.edu/StratfordLandingES/Ecology/mpages/euglena.htm

http://microscope.mbl.edu/scripts/microscope.php?func=imgDetail&imageID=323

ps I think that I will get a sample ours today if still there and keep it in a jar in a window to see what happens.

The greatest number of Euglena species have only the green color of their chlorophyll. Only a few species (10-12) of Euglenoid algae have the migratory red granules (haematochrome) that allow for the color change. Thousands of other algae species which belong to 12 divisions or algal groups have relatively stable non-color changing photosynthetic pigments. Dying or decaying algae can result in changes of the hue of water.

Bill :

Thanks for the info . I recall from your prior posts that there are thousands of possible " planktonic/algae " types in ponds . The 2 links in the above post alone show well over a hundred different euglena . I have often seen the dead and decaying algae in our ponds have gray/brown hues and a rainbow of colors on various wind blown live varities.

Interestingly today the red/brown type is not visable .I took a water sample in a clear jar and put outside in a window to watch for the next week. Not scientific but may be interesting. In the last week something has changed but not the weather. Visibility has increased 20% and the fish are much more active. The variable-leaf pondweed {potamogeton diversifolius} continues to die and decay where sprayed with Habitat. This area covers about 1/2 acre spread out over a 16 acre lake. There have been at least 4 forum reports on brown/red blooms in the last 3 weeks. Penn. , Ga. , Miss. ,and Neb. as best I recall. Thanks to all for any info . ewest

Bruce - There are five common preservatives for algae. 1. Lugol's solution (iodine, potassium iodide, water) 2. M3 fixative (Lugol's, with acetic acid and formalin), 3. Glutaraldehyde - 2.5-5%, 4. buffered formalin 2-4%, 5. FAA (ethanol, formalin, acetic acid, H20).

It is important to use a preservative that fixes and retains all flagellar structures and causes minimal distortion. Staining of starch helps to separate certain algae.

ewest- Much still needs to be learned about algae and its physiology and ecology. Lots of unknowns still exist about the Euglenoids.