Pond Boss Forums AERATION Should I aerate? Anatomy of an oxygen crash, or "Am I Willie Mays, or Jose Canseco?"

I didn't think it was possible.

My arrogance was almost palpable as I discussed my brilliant horizontal aeration, surface agitated pond, and all of the wonderful fish that I was growing in it.

The year started out great.

I was regularly monitoring dissolved oxygen (DO), and was seeing numbers near or at saturation.

The fish were in beautiful shape and seemingly growing by the day.

The beginning of the problem apparently was in early May. A nice healthy looking bloom of submergent vegetation was taking hold. A big thick band of horned pondweed encircled the pond. About eight feet wide, it was green and vibrant and full of tens of thousands of invertebrates.

And producing oxygen by the pound I might add.

Things were going so well that I quit the hassle of taking oxygen readings in mid-June.

A little mini bloom of single celled algae followed the end of June, and Secchi readings dropped to an acceptable 24 inches and went into a holding pattern.

Water temperatures were in the upper 70's and life was good.

A few statistics for you.

1. The pond is .15 surface acre and contains about a quarter million gallons of water.

2. I'm injecting 20 gpm of well water.

3. The water is injected in with two sweeper nozzles, creating a significant circulating effect.

4. A surface agitator runs at night to give me a redundant oxygen source to protect against a well shut off, or other emergencies.

The pond has anywhere from 250 pounds to 300 pounds of fish, including bluegill, yellow perch, redears, smallies, etc.

Here's where it gets interesting.

I've found that the best way to assess the health of a pond is to fish it.

If you throw in a night crawler (sometimes I don't even use a hook), the fish should hammer it immediately, and you know all is well. It's a fool proof method. If DO levels are low, fish don't bite.

Another way of assessing the health of the pond is to observe feeding behavior. Rapid consumption of food means healthy fish.

Up until the third week in July everything was great.

Then the signs started.

Feeding levels began to drop off.

The thick band of vegetation began to regress.

The water smelled a little funny and took on a distinctive brown appearance.

The frogs started to disappear.

Then the worm was ignored.

For some reason all of this snuck up on me in a few days and it wasn't registering that I really had a problem. There's NO WAY I could be having a problems with all that circulation, aeration and fresh water.

Carbon dioxide had hit a long, fly ball straight for the warning track.

Was I going to be Willie Mays and make a beautiful over the shoulder basket catch?

Or was I going to be Jose Canseco and let the ball hit me square in the noggin and bounce into the third row for a home run?

Now I need to do two things, and in the following order.

Take appropriate action, and figure out what the heck was going on.

I took the following steps.

1. Turned the agitator on full time. This should add much needed oxygen.

2. Turn off the feeder. Dying fish don't need decaying pellets.

3. Add more fresh water. Hoping to push some of the cruddy water out the overflow.

4. Pray.

I took an oxygen reading before I took the aforementioned actions and found the following.

DO readings were 4 ppm in the top two feet of the water column, and 2 ppm at the bottom two feet.

It's obvious that the circulation and aeration were providing some oxygen, but not enough to keep up with....what?

OK, here my assessment based on observed facts.

My horned pondweed represented a "monoculture". A good 90 percent of my rooted vegetation was represented by this one species.

Some kind of environmental effect, such as increasing temperatures, or photoperiod, or some other such evil, caused the horned pond weed to die off. This occurred over a relatively short period. Seven days is my best guess.

During these seven days, the massive amount of dying submergent vegetation began to draw heavily on my oxygen reserves. The rotting veggies were subtracting oxygen more quickly than my devices could add.

My surface aerator kept the oxygen levels at sublethal values, so I didn't have an immediate fish kill.

Yellow perch found the lower, deeper oxygen levels to be intolerable, so they were forced to rise into the shallower levels, but encountered water that was too hot (pushing 90 degrees) and began to stress.

I lost 18 of my very best yellow perch over the next week, but their observed amounts of decay indicated to me that they all died around the same time, about one to two days before I realized what was going on, and they bubbled up, about three each day.

The bluegill were able to survive by milling around the agitator, which I saw them do, and I didn't kill any, although I'm sure I didn't do them any favors. I'm sure their overall health will take a while to return to pre-stress levels.

This evening I went to the pond for the first time since taking a California vacation.

The pond was looking much better.

A nice, light green new algae bloom was returning, and the fish were biting like crazy.

I'm expecting to find a few additional mortalities, but eighteen perch only represents about ten percent of the individuals present in the pond. My experience tells me that I killed at least two fish for every one that I found. Probably closer to three.

Was I Willie Mays, and make the dramatic crowd pleasing catch?

Heck no.

But was I Jose Canseco and let carbon monoxide go yard?

Not exactly.

I'm probably somewhere in between.

I'm a decent, second year outfielder who's playing in anonimity for the Royals, or Blue Jays, and the ball tipped off the edge of my glove, hit the wall and ended up being a stand-up double.

But I can live with that.

I'll do better next time.

At least you did it " steriod" free

Good lesson, Bruce. And much less painful than it potentially could have been (without corrective action) - I'm glad you still have 999,982 fish to go for your second million.

I haven't ever thought about the problems with a plant monoculture underwater before, but they are the same as on dry ground - whatever happens to the plants will probably happen to all of them at the same time.

A beautiful (to some) lawn of pedigreed grass needs fertilizing, watering, etc. to stay healthy. My yard full of "weeds" (to some) stays green in a dry August with no rain, no watering, and no fertilizer (not counting well-trained house pets).

If unattended (and who here knows how to give perfect care for horned pond weed, other than the Bill Codys?), we are probably better off with a pond full of diverse "weeds" than a monoculture.

Ok Bruce, now you have me worried about our late June and July herbicide applications.

Bruce,

Sorry to hear about that. I am constantly battling Chara up to three feet thick in my ponds. Been removing one wheel barrow load a day out of the trout pond and two out of the perch pond. The main pond has so much I will be draining it this fall and starting over after recovering and temporarily moving or harvesting as many fish as possible.

One day I took out several wheel barrow loads out of the trout pond and really stirred up the bottom. Had a couple of floater browns the next day. Not sure if it was due to bringing up some oxygen eating hydrogen sulfide or muck, stressing them by throwing in the rake over and over again, or the fact that I forgot to turn on the diffuser that evening. Could have been all of the above. (See I'm learning by the school of hard knocks too!)

Once again sorry to hear about your partial fish kill. I guess I've been lucky so far as I'm sure not that smart.

That was a close call Bruce !! Anytime plants (including plankton)die in the summer in the pond steps should be taken quickly .

Bruce was there a reason you did not remove the dead pondweed ?

Bruce, I wonder if your water temps got too hot for the pond weed or maybe a good rain muddying up the water a little bit with cloud cover for several days was enough to start the pond weed die off. One thing I have noticed is that when weeds start to die off there is self feeding loop that propagates and feeds the die off sometimes. The chlorophyll leaches out of the dead vegetation turning the water a brown tea color very quickly, the reduced water clarity then feeds more die off with both the remaining weeds and any good algea bloom that is going on.

Hi Bruce, aka Jose striving for a Willie status, When we visited this your ponds this spring I was a little nervious about the stability your "dad's pond" ecosystem. However you seemed to have things well under control due to past experiences. I guess there are always new things to learn. At least presently, I think what happened is the Zannichellia died off naturally in its annual cycle. It is an annual. Many annuals die off once the seeds are fully mature such as curly- leaf and narrow leaf pondweeds. The abudant monoculture dieoff and decay caused the oxygen sag. Part of your bloom could could have also died at the same time. To prevent this in the future I would do at least one or two things or a combination thereof. 1. When pondweed is growing well remove at least 25%- maybe 40%-50% of it from the pond. 2. Introduce a competing submerged species that will tolerate the water movement from the sweeper nozzles such as eelgrass - Vallisneria. Eel grass typically develops in mid summer and remains viable through fall into winter.

Just to show you how prolific weed growth can get, here is my daily wheel barrow rake up of Chara with some Potmogeton pusillus mixed in. (Only about four or five rake fulls!)

The reddish stuff is dead Chara underneath the live Chara which is tinted with iron deposits. That much dead Chara decomposing makes me nervous so I try and stay on top of it. Even if it isn't problematic to the fish respiration it will gradually build up a muck layer as it decomposes, which I don't want.

Good question.

Actually the pondweed just sunk out of sight, leaving little or no trace. It was as if it just vanished, but I think it just broke apart into some of the brown particulate that I saw everywhere.

This is extremely plausible about the feedback loop. Very consistent with my observations.

Agreed.

Can I apply a herbicide early on to knock back the horned pondweed bloom? I have the same plant community every year, so I'd assume I'll be dealing with the same issues in 2008.

I have several of those beautiful floating islands created by Bruce Kania's company. Could I use an agressive emergent plant such as cattails on the islands to compete for nutrients? It seems like a lot of the biomass currently being committed to pondweed could be transferred to cattail mass. My cattails love the light salinity of the water, and seem to stay green right through late fall.

Bruce, just an obserbvation, we also have had a massive vegetation die off here in the month of July through herbicide applications. We havn't had any fish deaths from it and I think the reason why is that the majority of nutirents in our pond have been tied up in the vegetation preventing an algea bloom. We didn't get an algea bloom going until after the weeds died and the nuturients became available (aka a herbicide induced algea bloom). It sounds like your pond had a good algea bloom going on when the pond weeds died off naturally. So my thoughts are that a large scale weed die off when a good algea bloom is present is probably more likely to cause a fish kill than a weed die off when there is almost no algea bloom present, thoughts?

Sounds legit, but keep in mind that if I had the same species of fish in my pond as you do in yours I wouldn't have had a die-off either. I only lost yellow perch, and I'm positive it wasn't from lack of oxygen, because yellow perch are more tolerant of low DO than bluegill or largemouth. I only lost them because they were forced out of the cooler water refuge to seek better oxygen and probably died from heat induced stress.

In effect I didn't have a summer kill--I only saw a decrease in overall water quality and consequently the perch decided it was time to take a nap.

Bruce,

Makes perfect sense to me. I have literature (The Yellow Perch Culture Guide NCRAC Culture Series # 103 October 2006) that says, "Yellow perch are more tolerant to low dissolved oxygen than sunfish. Reports have indicated dissolved oxygen levels as low as 3.5 mg/l (ppm) for 67 days will not be detrimental to perch growth."

But when it comes to temps it says, "Yellow Perch are deemed a cool water fish and show a preference for water temps between 21-24 C. (70 to 75); they have a physiological optimum temp of 22 to 24 C. (72 to 75 F.). Upper lethal temperatures for yellow perch have been reported as 26 - 30 C. (79-86 F.)."

My big pond that I have grown out some big ones in gets up into the low 80's in really hot weather. (Apparently the low 70 degree water that flows in does do some modification of temps.) With good mixing by the diffusers it only drops to 79 at about 9 feet. When the water gets that warm I don't see any perch feeding (rarely did anyway), and when I did catch them in deep water, if I handled them by just pressing slightly on the gill covers their gills would hemmorage. That tells me they were stressed and probably seek out cooler pockets on the bottom an wait out the heat. I've seen literature here that say at the upper temp limits they can't take any handling whatsoever.

http://www.thefishsite.com/articles/241/species-profile-yellow-perch-perca-flavescens



Here's your solution: Dig a small steep sided 1/10th acre pond upstream of your dad's pond. pump 45 gpms into that pond and over flow that into your dad's pond like I do, to keep temps in the low 70's. But if you went this route you may want to drain your dad's pond and make sure that it too is steep sided with no shallow areas to allow the pond to warm up fast.

This would give you a great excuse to have a trout pond!

See there's a silver lining to everything!

Then it would follow that the perch fled the 2 ppm DO levels up to the surface. It makes me wonder if I really have any yellow perch at all. I should have had at least 180 before the "event", but maybe I still have a lot of dead fish that I didn't see. Maybe they sank to the bottom. Maybe they're still dying. And maybe Meadowlark sent some Texas-size raccoons to collect the carcasses. I wish there was a good way to find out, but the underwater camera isn't going to be very effective for some time.

Only way to find out is with a seine and with water temps the way they are that of course wouldn't be a good idea.

I say there are survivors. From my experience perch are tough fish. If they can still grow normally at 3.5 mg/l which would stress other fish and put them off of feed, then it's entirely plausible they can survive 2.0 mg/l for a short period of time.

Perhaps the survivors would be candidates for selective breeding for fish that can tolerate higher water temps? Or get s shipment of fingerlings via air freight in the future from a North Carolina hatchery where they alledgedly can tolerate warmer temps?

Bruce the quick decline of some pondweeds is common behavior when it is dying at the end of its annual cycle - the beds can collapse fairly quickly - in a few days. The dieoff could have been also enhanced by the lower transparencies due to affects of your bloom (24").

I suppose you could apply a hericide early to knock back the initial growth. Zannchillia produces a lot of seeds so expect to see some new plants form or sprout from old seeds after the herbicide dissipates. To counter this, maybe use a long lasting herbicide like Sonar - check label for effectiveness.

The abundant growth of Zannichellia consumes a lot of nutrients from the pond so I am not sure how much plant growth would be needed to provide an equivalent alternative nutrient sink. A lot of all this depends on which nutrients are in excess or limiting in your system. If you don't have enough of a vascular plant nutrient sink you are liable to see a big growth of FA instead of a plankton bloom. Often bluegreen algae surface films appear when phosphorus is available and nitrogen becomes a limiting factor because surface growing bluegreens can get their source of nitrogen from the air.

Try the islands and see what happens. You now know what to expect if they are not absorbing enough nutrients - FA or bluegreen algae or maybe even another type of growth. It is hard to fool "mother nature".

Perch survival. I know what to exect with my YP stock but I'm not really sure about your stock or strain of YP. I, like Cecil, suspect you still have some YP. You probably lost the most vulnerable individuals leaving behind those most tolerant. Once the water cools a little, try fishing specifically for YP - use fish as bait. Bgill and RES do not usually bite well on medium sized minnows 2"-2.5". Even dead minnows work well on my YP.

OK, this is starting to crystallize a little bit.

I thought I was being thorough, but I failed to mention a couple of pertinent points.

This particular scenario is virtually identical to every other die-off I've had in some respects, but one really interesting similarity lies in the presence of a disgusting film of smelly algae that forms on the bottom of the pond in a blueish-green, gooey mat. This substance (maybe bluegreen algae?) then breaks apart and rises to the surface in puzzle-piece looking increments. I don't know why I didn't mention it, but this also happened in this last oxygen loss event. This leads me to the following question.

Could I not apply Sonar early to hammer the horned pondweed, then apply an alum slurry two or three times over the following few weeks to suppress the bluegreen algae, and tie up phosphorous that would have been utilized like FA and single celled algae? All the time growing cattails on the islands to stay ahead of the problem? I really don't need thousands of pounds of tightly woven vegetation to maintain an adequate invertebrate community. The fish can't really get to most of the nymphs anyway because they have so many hiding areas. And how much does Sonar cost, and how much would I use? And where do I send my check for all of this valuable advice? Maybe I could pick up the check for your next Pond Boss subscription.

HORNED PONDWEED IMAGE

Iv'e been seeing the some of same thing you just described in our pond but you can still make out remnents of the dead and decaying coontail on the underside of it. I have alsways assumed that this was part of decay process on the dead vegeation.

Hmmmmm.....Looking at your picture Bruce I may have mistaken horned pond weed in our pond for Sago, I will have to double check the seeds. In years past I have seen this grow all the way to the surface in our pond in 11 ft of water before.

I am eagerly awaiting to hear what Bill says.

Reminds me of the Potamogeton pusillis I have. It too grows all the way to the surface.

"horned pondweed has inconspicuous underwater flowers and fruits located at the leaf bases"

Evidently this is one of the keys, with the flowers and fruits kind of tucked into the leaf base.

Here's another Zanichellia photo (different species, same family) with an enhancement of the fruit.

I'm not sure what Shorty means by this- "I am eagerly awaiting to hear what Bill says". What is my question?

Bruce definately has Zanichellia - Horned pondweed. I verified the ID when I was out to his pond in May.

Bruce, you are treading on new ground here with your new ideas for managing your vegetation with chemical and floating mats. Try it and see what happens. If your puzzle algae is what I think it is as a form of bluegreen filametous called Lyngbya, then it is resistant to copper treatments.