Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Winter algae

I researched some of the earlier posts on algae, the slimy looking green stuff that floats near the pond banks that is what I guess you call filamentous algae. I saw methods suggested for controlling it, such as applying Cutrine and even applying lime around the pond banks. But, not a lot of discussion on what causes it. Of course, excessive nutrients in the water would seem obvious, but in the dead of winter and with virtually no inflow in the past year due to drought, how might this be possible ? Only one of the ponds on my place has this problem. I'm curious as to what's so different about the affected one. This pond is about 1 1/2 years old and the water is fairly clear with a slight greenish tint. It would be difficult to treat with chemicals as its about 1/4 mile in length.
Any insight to this ?

squeeky, algae are very adaptive. Spirogyra for example have flourished in Ohio waters this year due to the ice on/off 4-5 times this winter, lots and lots of light.Cold water plays very little part in certain FA production.Sunlight and any water that is not very very clouded will probably have FA in northern waters this year.These FA's will run their growth cycle and be gone and more will probably replace them.The nutrients really dont have to be "excessive" as it takes very little to spawn some algae. The bright side is you will get some 02 production from them, the downside is they will die off and become part of the organic sediment load and become nutrients and the cycle has started all over again.

Thanks for the info. This sounds like something that I'll just have to live with.

Squeeky, Some ponds age quicker than normal. This usually due to low assimilation ability of the pond. In other words, there are not enough beneficial organisms to consume the phosphates, nitrates, and other nutrients that are entering the pond. This is due to low oxygen levels typically found at the bottom of the pond.

If a pond has good oxygen content from top to bottom,the habitat for beneficial bacteria (aerobic bacteria) and benthic organisms (slugs, snails, mussels, worms) will begin to move throughout the entire pond bottom and begin to clean up the pond.

By increasing the oxygen levels from top to bottom, an organism (zooplankton) now has a larger area to feed. Zooplankton is the largest consumer of plankton algae in a pond. They are also the basis of the food chain for fish.

Other things happen to help limit the release of nutrients in the water column. One measurement we use as Limnologist is called Redox Potential. This is a measure of the proportion of oxidation to reduce substances. In a pond that is low in oxygen or (anaerobic) the redox typically is in the negatives. Once we aerate the redox now turns to the positive thereby bonding the phosphorous and nitrates to the bottom of the pond, limiting the release for the algae to use as a food source.

In summary, by adding an aeration system we have now increased the pond's ability to assimilate the nutrients that are washing in.

Keep in mind that an aeration system is just another tool in the lake manager's tool box and is not a one-stop cure all. The source of the nutrients must be limited as well.

Cary and Ted

How do you measure the Redox Potential? Is there a test kit? The county extension service I use (with labs at University of Georgia) does not list this water test. They do list BOD(Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand).

Thanks guys.

Frank

Certainly, I can appreciate the benefits of aeration, but an available electric power source is an issue in my case. The local power co charges by the foot for extending power lines into the property, and the cost can be large. Oh well, maybe someday.

squeeky:

See if you can get a larger electric service for less. Our service is about 750 feet from the main. The local power company would only run a 200 amp service 500 feet for free. But they had no length limit for a 400 Amp service (I believe the theory was a customer with a bigger service will use more electricity). Guess what size service I put in.

Don't know if you could get a deal like this, but it could be worth checking.

Frank, Squeeky and Others -
Firstly you measure redox potential with a meter that measures the hydrogen electron flow and it is read as a voltage. If the electrons flow from the solution to the electrode then it is considered reducing conditions. When the electrons are flowing from the electrode to the solution, it is considered an oxidizing condition (positive voltage). To relate if you have oxygenated water at DO saturation and a pH of 7 the redox potential should be 0.80 volts. However when one measures the redox of oxygenated natural waters the redox in actuality ranges from 0.45-0.52 volts. As long as DO is present the redox potential remains about 0.5 volts. When oxygen is depleated redox drops rapidly and is in the negative values (-0.25to -0.30 volts) during anaerobic conditions (oxygen deficient).

Secondly I want to clarify - but not attack- a few of Cary's comments. He said ""there are not enough beneficial organisms to consume the phosphates, nitrates, and other nutrients that are entering the pond. This is due to low oxygen levels typically found at the bottom of the pond." He goes on to say ""If a pond has good oxygen content from top to bottom,the habitat for beneficial bacteria (aerobic bacteria) and benthic organisms (slugs, snails, mussels, worms) will begin to move throughout the entire pond bottom and begin to clean up the pond"".

When I read these two statements it sounded as though he is saying that the beneficial organisms - bacteria and benthics i.e. animals- are consuming phosphours, nitrates and other nutrients that are entering the pond. This is only indirectly true. These animals do not eat nutirents directly but a majority of them do consume organic materials - they are grazers of living and dead plant materials. Dead animal materials are consumed by some of them. A lot of these organic materials at the bottom of a pond are plant based. These plants when living were the ones who actually "consumed" (absorbed) the phosphorus, nitrogen and other nutrients, not the animals.

3. Cary's second statement that I want to clarify is "" In summary, by adding an aeration system we have now increased the pond's ability to assimilate the nutrients that are washing in.""
Nutrients that are dissolved in water and wash or drain into a pond can not be abated or directly reduced by aeration. If this is possible then I want to read the scientific article that stated this. Dissolved nutrients will grow plants in the presence of sunlight and water. Bubbling the water and even improving or enhancing the oxygen concentration of the water containing dissolved nutrients will not lower the dissolved nutrient concentrations. Plants absorb nutrients and reduce the nutrient concentrations. Animals eat plants and or other animals.

However it has been proven, and the results published, that if oxygenated water is maintained at the mud-water interface (bottom of a pond/lake) then this can lower the amount of phosphorus that will be released from the anoxic or oxygen starved sediments. Bottom aeration can reduce the amount of nutrient recycing from the sediments. However to my knowledge, aeration cannot reduce the amount of nutrients in drainage water that enters a pond or lake. Nor can it reduce the amount of dissolved nutrients from direct application of fertilizers to pond water.

4. A scientific, published paper of a study conducted in ten Minnesota lakes and titled "Sedimentological Effects of Aeration Induced Lake Circulation" by Engstrom and Wright even questioned the ability of bottom aeration to cause the reduction of lake sediments. They said and I quote: "Sedimentary organic content does not decline in any of the lakes, aerated or non-aerated, during the last two decades. Historic patterns of sediment accumulation and composition in the aerated lakes are no different from that shown by non-aerated lakes. Results from this study do not support claims that aeration induced circulation will enhance the removal of organic sediments from lake basins either by mineralization or offshore transport." Lake and Reservour Management. 2002. Vol 18(3):201-214.

Frank, You may want to have a BOD test but be aware that it can and does change. The demand varies with temperature, sunlight time of year etc. Results are normally expressed in Mg/L or ppm and the goal number would be "zero"or in other words the supply of O2 meets or exceeds the "demand" You may see a number like 10-12 or even 15 on a test report. You may also find a negative redox or "ORP" (Oxidation Reduction Potential) with the test results of a redox test. They also can swing as most waste water treatment plants will do a constant monitoring of their redox value for this reason.When o2 is added to the water obviously the intended result is to lower the BOD number and meet the demand and when this occurs the ORP may rise to a positive millivolt reading which is a good.A lot of the tests are sensitive to timing as is DO. Test for DO in the early AM and it will be lower than the early afternoon on a sunny day.Test in the top 24 inches and will be higher than on the bottom. Point being on test results be aware that they are but a "snapshot" of the immediate present and not always the longterm average. Even a composite sample can mislead.Ponds with high amounts of organic sediments may have a negative redox and a high "demand" BOD. Hope this helps. Ted

Bill, What do you think of the Engstrom and Wright study compared to your own experiences and observations.When I looked at this study (summary) a few years ago I questioned the OTR of the devices in a "lake" setting.I have wondered if the bottom temps were monitored as I believe very difficult to maintain a very high "yearly" average in the northeren waters.I do not see a lot of digestion at temps in bottom waters below 55F. I also considered the notion/ suggestion in the study that diffusers may have "displaced" the bottom sediments to other areas or simply resuspended them. In my own very unsceintific observations I have seen a lot of reduction in organic sediments but only with warmer bottom temps. I normally notice lesser material within 50 ft of a diffuser placed i 10-15 feet of water initially. When the reduction continues to take place and the Seechi reading stay the same or better I dont seem to have any resuspension as the study indicates.I also believe that small lakes and ponds (tanks in Tx) are easier to turn and heat.I continue to maintain one- two turns in a mature high organic high BOD potentially low ORP situation. My small pond which fit that description 5 years ago is void of the original 12-18 inches of "muck"Our larger pond that was redone in late 2002 still shows the dozer track lines and sheepsfoot indentations in 14 ft of water so not a lot of accumulation to date. Even though I have a light layer of organics 1/4 > 3/8 inch over the winter it will be gone by the first of June if history repeats itself.This pond can be turned over 4 times per day when needed to reduce the iron and sulfur from the well that feeds it. I have found the reduction in organics a great side benefit to aeration and heating the bottom waters providing it does not conflict with other things such as cold water species etc.Your comments always appreciated, Ted

Ted - Note that I did not offer an opinion aboutthe Engstrom & Wright study. Their methodology and size of water could have affected the outcome. More research needs to be done on this topic. There is still a lot of information about aeration and the affects upon the ecosystem that is still unknown. Temperature of the bottom water and chemistry of the sediments (natural and polluted) no doubt play big roles in the fate of sediments.

Your observations are good pieces of information.

The filamentous algae in Missouri ponds are already growing fast - probably due to the mild winter and low water levels. My 2 acre pond is only three years old and I got large mats, 10 feet wide circling the whole shoreline. Water level is two feet below the spill pipe and I have not had any overflow in 13 months. I have a bottom aerator, but I turned it off for the winter. The water shed is 30 acres of hardwoods. I would like to knock back the algea before it gets worse.
Could a good spring rain kill some of the algea if the water level suddenly went up two feet? Would planting other water plants help reduce algea? Is it too early to apply one of the copper type products? I sure wish I could find a Tilapia source in Missouri.
What would you do - Any comments are appreciated.

Bill, Frank & Ted,

I must first appologize for the long response time. I have my irons in too many fires this week and just now making it back to the forum page.

Bill, thank you for the clarification of my statements. I make these answers as general as possible since the majority of our clients that we deal with are not limnologist or biologist. If they question my statements and are interested as Frank is, that opens the door for us to "dive deeper" (pun intened), into the description as you did.

As you stated, you were clarifying my statements and not attacking them. Thank you for that preface.

Jeff,Spring rains wont kill your algae but this "batch" will probably be dead by then (only a few weeks away)but new will probably replace it.As far as planting other water plants to compete this is possible but difficult.Copper type products need some warmer temps to be effective. 60-70F minimum seems to work best.If you must use copper consider the chelated products only for a pond your size. You mention a bottom aerator, be sure you are turning your entire water column over enough as if you have a single diffuser you may have voids in the shallows, Enough DO to keep fish alive but perhaps lacking in a complete coverage of aerobic bacteria. 2 acre pond 9 ft average depth is 6 million gallon.Your 3 year old pond now has a higher "demand" for DO then it did when it was new,this is quite common.What is the depth (s) at which you are having the majority of your problems? Do you fertilize (Im guessing no) Do you use a UV inhibitor and if yes when and which one?

Alright guys, I gotta jump in here, last night I observed what appears to be a very significant cold water algea bloom going at our pond. In the last twenty years I have never seen anything like this, the water looks like a late summer algea bloom, it's starting to look like pea soup in the middle of the pond. The water clarity has gone from 9-10ft of visibilty down to just 4-5ft and this is only a day after the ice has come completely off the pond. I think this last cold front that swept in 12-14 days ago actually killed off a bunch of aquatic vegetation on the windy side of the pond and this die off is feeding the current bloom. I say this because peices of milfoil I reeled in with my crankbait actually looked frost bitten even though it is nowhere near the surface, there is also noticable absence of Chara where the wind churned up the water, I know it was there before this last cold front came in. We had an awful lot of wind with this cold front and it took several days before an ice cap formed, there was still open water with highs only in the upper teens, a cap did not form until the wind died and it only took 2-1/2 days to put 4-5" of ice on. Has anyone ever seen anything like this before with cold water temps? Should I be concerned? Right now I am inclined to just wait and see what happens as the water temps are still in the lower 40's. Maybe this reduced visibilty will slow the milfoil, coontail and chara down a bit. Those weeds were off to an unusually good start with all of this January/Febuary warm weather which was followed by a super cooling of the water.

My neighbors pond also has much more algea active this winter. We can see very large clusters of green growing under the surface. We do not fertilize. This is a response from my Fisheries agent:

"Algae problems always stem from nutrient loading. All ponds go though a process called eutrophication in which the pond gets ever shallower and more nutrient rich. If unnatural sources of nutrients (fertilizers, leaky septic tanks, cow manure, etc.) are present this process will be accelerated, otherwise the rate of eutrophication depends upon the natural fertility of the soil and accumulation of other organic debris (ie leaves). If your pond is nutrient rich, something is going to use those nutrients. Usually that something is algae. It is very opportunistic.

You can kill the algae with copper sulfate, but as the nutrients are still there, the algae will return. How quickly it will return depends on how heavy the nutrient load is. The other option is using Aluminum Sulfate (Alum). Alum, when applied to your pond, will bind to the phosphorus (a major nutrient) in the water and make it unusable for the algae, basically starving the algae to death. This should have a much longer lasting effect. Alum sometimes causes a lowering of pH that can kill fish. We have not had this problem in any Missouri ponds, but if you are worried about it you can buy buffered alum. Also, Alum or Copper sulfate should only be applied when water temperatures are cool, 60 - 80 degrees. Killing any vegetation in a pond can cause a dip in dissolved oxygen levels that may cause a fish kill."

I may try the Alum.

Keep us informed, Steve.

All of the ponds I've checked had increases in rooted winter vegetation. My theory is that since the ponds are down, and it hasn't rained much the last year, that the sunlight penetration is excellent, even to the point of reaching areas of the pond bottoms that it hasn't reached in a long, long time. Picture this. Nutrient rich pond muck, which hasn't seen the light of day in years is now closer to the surface, and the ice lately, which was not snow covered allowed for the water to reach it's maximum clarity. Suddenly you have a bloom. Once the ice goes off, then the wind whips it up a little and decreases the clarity. Almost immediately the vegetation starts to stress and die.

Is this plausible?

Absolutley Bruce, we have chara growing all the way accross the bottom now and both milfoil and coontail in deep water where it has never been. My theory on this also invloves the warmth prior to this extreme cold front coming in. In effect a super cooling of the water when the weeds had already started actively growing. Our milfoil was definatley already lifting itself of the bottom and starting to activley grow towards the surface. It normally lays down when it goes dormant in cold water. What boggles me is that the peices of milfoil I was pulling up last night also looked like they had been frost bitten even though the tops were 1-3 feet under water. The leaves where much darker green, it felt more brittle, and looked like it had been hit by a hard frost, more something you would see in your garden rather than in your pond when the plants are about to die from the first hard frost. Now the water looks like it does in late summer when the algea is starting to bloom hard.

I am hoping this turns into a blessing in disguise rather than another problem to deal with. I am going to keep an eye on it, this may force some changes in how we deal with too many weeds this spring.

Quick update, I was out last night an this cold water algae bloom has subsided, the water clarity is back to 7-8ft and the green tint is gone.

I still think this was pretty wierd to happen this time of year.

Quick update, the cold water algae bloom is still going on. I surveyed some areas of the pond and it looks like the cold front did in 50-60% of the chara in depths up to 9 ft deep on the south side of the pond, I believe this significant chara die off is feeding the algae bloom. Has anyone every seen an algae bloom in water temps that are less than 50 degrees?