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iLabs: Update on Search for Information Spirogyra Control in Ponds

August 4, 2012

I am still trying to track down an expert on the topic of controlling pond algae, especially Spirogyra. A couple of weeks ago a gentleman  visited us in the lab and asked the following questions:

One man noted our Spirogyra culture on the counter and asked for help in dealing with it in pond environments. He noted that it seemed that even when you couldn’t see the algae on the surface, it was still present beneath the surface, and still causing problems in the pond environment. He was very anxious to learn more.

He spoke both of Spirogyra as well as unicellular types and Microcystis. He was aware of harvesting techniques for Spirogyra, and knew that prevention was the best approach but he specifically wanted to know:
– what do you do with unicellular varieties as those you can’t “cut down” in the pond?
– what do you do once you HAVE a bloom in full force? How can you turn it around?

I have found a number of online links, most of which  seem to mention the same steps: physical, chemical, natural-carp, bottom covers, water dyes .

From the NC State University and NC A&T State University Cooperative Extension booklet, “Managing Aquatic Weeds,” by Charlotte Glen, Horticulture Agent, Pender County:

Variety of Control Methods

• Cultural–preventing weeds, altering habitat

• Mechanical –hand/machine removal

• Biological –natural predators

• Chemical–aquatic herbicides

Which is right for your situation depends on the weed to be controlled, how body of water used, budget, and environmental and aesthetic considerations.

Each link below has slightly different information, including one that points out that for Spirogyra, carp is not effective because Spirogyra isn’t a food source for carp.

Another problem is that the carp themselves become a problem:

“ROUGH FISH REMOVAL The bottom-feeding activities of “rough” fish, particularly the common carp, can contribute greatly to the resuspension of bottom sediments and the release of sediment-bound nutrients to the overlying lake water, thus contributing to algal growth. Habitat conditions are degraded by the increased sediment and algal turbidity and reduced macrophyte growth, which all can affect a lake’s fishery. Manage-ment alternatives to reduce carp numbers include hook-and-line, seining, and partial lake treatments using the fish toxicant rotenone applied to areas of congregating carp (i.e., in shallow waters during carp spawning). When carp populations become overabundant, a whole-lake rotenone treatment is the only way to reestablish a balanced fish population. A profound increase in water transparency has been seen in several Illinois lakes following whole-lake carp eradication. A shift in the lake’s plant population from algae to macrophyte dominance also may occur.”

So the carp, in eating some of the aquatic plants and thus reducing them, disturb the sediment, where a lot of nutrients are held. The swirling sediment redistributes settled out nutrients thus causing another algae bloom.

And there is also the problem that if clarity of the water can be achieved, then sunlight can reach deeper into the water and causing algae and plant blooms all over again.

I have a query into a resource at NC State University to see if there’s anything else I can find for this gentleman, and all of our readers. But that is taking time. So in the meantime I wanted to give the links to the above booklet as well as a few others I found. It’s a start. As soon as I hear back from NC State, I will update on this topic again.

S. H. KAY, Crop Science Department:    Aquatic Weed Control

College of Agriculture and Life Sciences – NC State University
AQUATIC WEED CONTROL K. D. GETSINGER, US Army Engineer Research and Development Center, Vicksburg, MS, and Adjunct Professor, Crop Science Department, NC State University: NC Agricultural Chemicals Manual

Link from Ohio State University Cooperative Extension Fact Sheet,  Controlling Filamentous Algae in Ponds
William E. Lynch Jr.
Program Specialist, Aquatic Ecosystem Management
School of Environment and Natural Resources:  Pond management of filamentous algae

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